Tuesday, August 14, 2018

In Neutron Stars, Protons May Do The Heavy Lifting

Neutron stars are the smallest, densest stars in the universe, born out of the gravitational collapse of extremely massive stars. True to their name, neutron stars are composed almost entirely of neutrons — neutral subatomic particles that have been compressed into a small, incredibly dense celestial package.

A new study in Nature, co-led by MIT researchers, suggests that some properties of neutron stars may be influenced not only by their multitude of densely packed neutrons, but also by a substantially smaller fraction of protons — positively charged particles that make up just 5 percent of a neutron star.

Instead of gazing at the stars, the researchers came to their conclusion by analyzing the microscopic nuclei of atoms on Earth.

MIT researchers used archived data from the CLAS detector to study interactions in neutron-rich atoms.
MIT researchers used archived data from the CLAS detector to study interactions in neutron-rich atoms.
Courtesy of the researchers

The nucleus of an atom is packed with protons and neutrons, though not quite as densely as in neutron stars. Occasionally, if they are close enough in distance, a proton and a neutron will pair up and streak through an atom’s nucleus with unusually high energy. Such “short-range correlations,” as they are known, can contribute significantly to the energy balance and overall properties of a given atomic nucleus.

The researchers looked for signs of proton and neutron pairs in atoms of carbon, aluminum, iron, and lead, each with a progressively higher ratio of neutrons to protons. They found that, as the relative number of neutrons in an atom increased, so did the probability that a proton would form an energetic pair. The likelihood that a neutron would pair up, however, stayed about the same. This trend suggests that, in objects with high densities of neutrons, the minority protons carry a disproportionally large part of the average energy.

“We think that when you have a neutron-rich nucleus, on average, the protons move faster than the neutrons, so in some sense, protons carry the action,” says study co-author Or Hen, assistant professor of physics at MIT. “We can only imagine what might happen in even more neutron-dense objects like neutron stars. Even though protons are the minority in the star, we think the minority rules. Protons seem to be very active, and we think they might determine several properties of the star.”

Digging through data

Hen and his colleagues based their study on data collected by CLAS — the CEBAF (Continuous Electron Beam Accelerator Facility) Large Acceptance Spectrometer, a particle accelerator and detector based at Jefferson Laboratory in Virginia. CLAS, which operated from 1998 to 2012, was designed to detect and record the multiple particles that are emitted when beams of electrons impinge on atomic targets.

“Having this property of a detector that sees everything and also keeps everything for offline analysis is extremely rare,” Hen says. “It even has kept what people considered ‘noise,’ and we’re now learning that one person’s noise is another person’s signal.”

The team chose to mine CLAF’s archived data for signs of short-range correlations — interactions that the detector was not necessarily meant to produce, but that it captured nonetheless.

“People were using the detector to look at specific interactions, but meanwhile, it also measured in parallel a bunch of other reactions that took place,” says collaborator Larry Weinstein, a professor of physics at Old Dominion University. “So we thought, ‘Let’s dig into this data and see if there’s anything interesting there.’ We want to squeeze as much science as we can out of experiments that have already run.”

A full dance card

The team chose to mine CLAS data collected in 2004, during an experiment in which the detector aimed beams of electrons at carbon, aluminum, iron, and lead atoms, with the goal of observing how particles produced in nuclear interactions travel through each atom’s respectively larger volume. Along with their varying sizes, each of the four types of atoms have different ratios of neutrons to protons in their nuclei, with carbon having the fewest neutrons and lead having the most.

The reanalysis of the data was done by graduate student Meytal Duer from Tel Aviv University in a collaboration with MIT and Old Dominion University, and was led by Hen. The overall study was conducted by an international consortium called the CLAS Collaboration, made up of 182 members from 42 institutions in 9 countries.

The group studied the data for signs of high-energy protons and neutrons — indications that the particles had paired up — and whether the probability of this pairing changed as the ratio of neutrons to protons increased.

“We wanted to start from a symmetric nucleus and see, as we add more neutrons, how things evolve,” Hen says. “We would never get to the symmetries of neutron stars here on Earth, but we could at least see some trend and understand from that, what could be going on in the star.”

In the end, the team observed that as the number of neutrons in an atom’s nucleus increased, the probability of protons having high energies (and having paired up with a neutron) also increased significantly, while the same probability for neutrons remained the same.

“The analogy we like to give is that it’s like going to a dance party,” Hen says, invoking a scenario in which boys who might pair up with girls on the dance floor are vastly outnumbered. “What would happen is, the average boy would … dance a lot more, so even though they were a minority in the party, the boys, like the protons, would be extremely active.”

Hen says this trend of energetic protons in neutron-rich atoms may extend to even more neutron-dense objects, such as neutron stars. The role of protons in these extreme objects may then be more significant than people previously suspected. This revelation, Hen says, may shake up scientists’ understanding of how neutron stars behave. For instance, as protons may carry substantially more energy than previously thought, they may contribute to properties of a neutron star such as its stiffness, its ratio of mass to size, and its process of cooling.

“All these properties then affect how two neutron stars merge together, which we think is one of the main processes in the universe that create nuclei heavier than iron, such as gold,” Hen says. “Now that we know the small fraction of protons in the star are very highly correlated, we will have to rethink how [neutron stars] behave.”

This research was supported, in part, by the U.S. Department of Energy, the National Science Foundation, the Israel Science Foundation, the Chilean Comisión Nacional de Investigación Científica y Tecnológica, the French Centre National de la Recherche Scientifique and Commissariat a l’Energie Atomique, the French-American Cultural Exchange, the Italian Istituto Nazionale di Fisica Nucleare, the National Research Foundation of Korea, and the UK’s Science and Technology Facilities Council.

Contacts and sources:
Jennifer ChuMassachusetts Institute of Technology

Monday, August 13, 2018

Earth’s Mini-Moons: Potential for Exciting Commercial Opportunities

The detection of "mini-moons" -- small asteroids temporarily captured in orbit around Earth -- will vastly improve our scientific understanding of asteroids and the Earth-Moon system, says a new review published in Frontiers in Astronomy and Space Science. These small and fast-moving visitors have so-far evaded detection by existing technology, with only one confirmed mini-moon discovery to date. The advent of the Large Synoptic Survey Telescope (LSST) will verify their existence and track their paths around our planet, presenting exciting scientific and commercial opportunities.

"Mini-moons can provide interesting science and technology testbeds in near-Earth space. These asteroids are delivered towards Earth from the main asteroid belt between Mars and Jupiter via gravitational interactions with the Sun and planets in our solar system," reports Dr Robert Jedicke, lead author, based at the University of Hawaii, Honolulu, USA. "The challenge lies in finding these small objects, despite their close proximity."

Asteroid 2016 HO3 has an orbit around the sun that keeps it as a constant companion of Earth. 
Asteroid 2016 HO3 has an orbit around the sun that keeps it as a constant companion of Earth
Credit: NASA/JPL-Caltech

"At present we don't fully understand what asteroids are made of," adds Dr Mikael Granvik, co-author, affiliated with both the Luleå University of Technology, Sweden and the University of Helsinki, Finland. "Missions typically return only tiny amounts of material to Earth. Meteorites provide an indirect way of analyzing asteroids, but Earth's atmosphere destroys weak materials when they pass through.

"Mini-moons are perfect targets for bringing back significant chunks of asteroid material, shielded by a spacecraft, which could then be studied in detail back on Earth."

Predicted to be up to 1-2 meters in size, mini-moons are temporarily gravitationally bound in the Earth-Moon system. They may just fly-by the Earth or make at least one revolution around the planet, eventually escaping the gravitational tug of our planet or entering our atmosphere.

Reviewing the last ten years of mini-moon research, Jedicke and colleagues show that existing technology can only detect these small, fast moving objects by chance.

"Mini-moons are small, moving across the sky much faster than most asteroid surveys can detect," explains Jedicke. "Only one minimoon has ever been discovered orbiting Earth, the relatively large object designated 2006 RH120, of a few meters in diameter."

Currently under construction and operational in a few years, LSST hopes to confirm the existence of mini-moons and help track their orbits around Earth. The review -- part of a special article collection on the Earth-Moon neighborhood -- highlights the opportunities that the detection of mini-moons will bring, to capitalize on LSST's capabilities once it begins operations.

"The LSST is the dream instrument for discovering tiny, fast-moving asteroids and we expect it will regularly discover temporarily-captured objects within the next five years," reports Jedicke. "It has a gigantic mirror to collect light from faint objects and a camera with a tremendous field-of-view to cover the entire sky more than once a week."

He continues, "Once we start finding mini-moons at a greater rate they will be perfect targets for satellite missions. We can launch short and therefore cheaper missions, using them as testbeds for larger space missions and providing an opportunity for the fledgling asteroid mining industry to test their technology."

"We don't know whether small asteroids are monolithic blocks of rock, fragile sand piles, or something in between," says Granvik. "Mini-moons that spend significant time in orbit around Earth allow us to study the density of these bodies and the forces that act within them, and therefore solve this mystery."

Jedicke concludes by sharing his aspirations for these asteroids: "I hope that humans will someday venture into the solar system to explore the planets, asteroids and comets -- and I see mini-moons as the first stepping stones on that voyage."

Contacts and sources:
Emma Duncan

Citation:  Earth's Minimoons: Opportunities for Science and Technology

Supermassive Black Hole Discovered in an Ultracompact Dwarf Galaxy

Fornax UCD3 is a part of a Fornax galaxy cluster and belongs to a very rare and unusual class of galaxies - ultracompact dwarfs. The mass of such dwarf galaxies reaches several dozen millions of solar masses and the radius, typically, does not exceed three hundred light years. This ratio between mass and size makes UCDs the densest stellar systems in the Universe.

"We have discovered a supermassive black hole in the center of Fornax UCD3. The black hole mass is 3.5 million that of the Sun, similar to the central black hole in our own Milky Way" explained Anton Afanasiev, the first author of the article, a student of the department of the Faculty of Physics, MSU.

An optical image of the giant elliptical galaxy NGC 1399 and its satellite UCD3. Left panel: the image of UCD3 in F606W filter obtained by Hubble telescope. Right panel: an infrared image of UCD3 obtained using the SINFONI spectrograph.

Courtesy of NASA/STScI/ESO/Afanasiev et al.

In the course of the study the scientists used the data collected with SINFONI, an infrared integral field spectrograph installed at one of the 8-m VLT telescopes in Chile operated by the European Southern Observatory. Having analyzed the observed spectra, the authors derived the dependence between stellar velocity dispersion and radius in Fornax UCD3. Velocity dispersion quantifies the average variation between the individual stellar line-of-sight velocity and the mean velocity of the entire stellar population.

 In the presence of a massive body such as a black hole the stars are influenced by its gravity and accelerate in various directions. Due to that their average speed does not grow but the dispersion increases considerably. This is the very effect that was observed in this galaxy: the velocity dispersion in its center is so high that it can only be explained by the presence of a massive central black hole.

After that the scientists compared the dependence of velocity and dispersion with dynamic models based on different assumptions of the black hole mass. They found that the model suggesting the mass of the black hole being equal to 3.5 million solar masses agreed with the observations best. They also considered the possibility that no black hole was present there at all, but that hypothesis was excluded with the statistical significance of (99.7%).

The black hole discovered by the authors is the fourth ever to be found in UCDs and corresponds to 4% of the total galaxy mass. In "normal" galaxies this ratio is considerably lower (about 0.3%). Despite there are few known examples, the existence of massive black holes in UCDs is a strong argument for the tidal origin of such galaxies. According to this hypothesis, an average-sized galaxy passed a bigger and more massive one on a certain stage of its evolution and as a result of influence of tidal forces lost the majority of its stars. The remaining compact nucleus has become what we know as an ultracompact dwarf.

"To be able to say with complete assurance that this hypothesis is correct, we need to discover more supermassive black holes in UCDs. This is one of the prospects of this work.

Moreover, a similar methodology may be applied to more massive and less dense compact elliptical galaxies. In one of our next works we will study the population of central black holes in objects of this kind," concluded the scientist.

The work was carried out in collaboration with the scientists from the European Southern Observatory (Germany and Chile), Max Planck Institute for Astronomy, Institute for Astrophysics Potsdam (Germany), University of Michigan, San Jose State University, Texas A&M University, University of Utah, University of California (USA), Australian Astronomical Observatory, Macquarie University, University of Queensland (Australia), as well as from Swiss Federal Institute of Technology Zurich.

Contacts and sources:
Yana Khlyustova
Lomonosov Moscow State University

Citation: A 3.5 million Solar masses black hole in the centre of the ultracompact dwarf galaxy fornax UCD3
Anton V Afanasiev Igor V Chilingarian Steffen Mieske Karina T VoggelArianna Picotti Michael Hilker Anil Seth Nadine Neumayer Matthias FrankAaron J Romanowsky
George Hau Holger Baumgardt Christopher Ahn Jay StraderMark den Brok Richard McDermid Lee Spitler Jean Brodie Jonelle L Walsh
Monthly Notices of the Royal Astronomical Society, Volume 477, Issue 4, 11 July 2018, Pages 4856–4865, https://doi.org/10.1093/mnras/sty913 http://dx.doi.org/10.1093/mnras/sty913

Ultrahot Planets Have Starlike Atmospheres

Recent observations by NASA's Hubble and Spitzer space telescopes of ultrahot Jupiter-like planets have perplexed theorists. The spectra of these planets have suggested they have exotic -- and improbable -- compositions.

However, a new study just published by a research team that includes Arizona State University astrophysicist Michael Line, an assistant professor in ASU's School of Earth and Space Exploration, proposes an explanation -- that these gas-rich planets have compositions that are basically normal, going by what is known about planet formation. What's different about them is that the atmospheres on their daysides look more like the atmosphere of a star than a planet.

These simulated views of the ultrahot Jupiter WASP-121b show what the planet might look like to the human eye from five different vantage points, each illuminated to different degrees by its parent star. The images were made with a computer simulation being used to help scientists understand the atmospheres of these planets. Ultrahot Jupiters reflect almost no light, much like charcoal. However, their daysides have temperatures of between 3,600 F and 5,400 F, so they produce their own glow like a hot ember. The orange color in this simulated image thus comes from the planet's own heat. 

Credit: NASA/JPL-Caltech/Vivien Parmentier/Aix-Marseille University (AMU)

"Interpreting the spectra of the hottest of these Jupiter-like planets has posed a thorny puzzle for researchers for years," Line said.

The biggest puzzle is why water vapor appears to be missing from these worlds' atmospheres, when it is abundant in similar but slightly cooler planets.

According to the new study, ultrahot Jupiters do in fact possess the ingredients for water (hydrogen and oxygen atoms). But due to the strong radiation on the planet's daysides, temperatures there go high enough that water molecules are completely torn apart.

With ultrahot Jupiters orbiting extremely close to their stars, one side of the planet faces the star perpetually, while the nightside is gripped by endless darkness.

Dayside temperatures reach between 3,600 to 5,400 degrees Fahrenheit (2,000 to 3,000 degrees Celsius), ranking ultrahot Jupiters among the hottest exoplanets known. And nightside temperatures are around 1,800 degrees Fahrenheit cooler.

Star-planet hybrids

Among the growing catalogue of planets outside our solar system -- known as exoplanets -- ultrahot Jupiters have stood out as a distinct class for about a decade.

"The daysides of these worlds are furnaces that look more like a stellar atmosphere than a planetary atmosphere," said Vivien Parmentier, an astrophysicist at Aix Marseille University in France and lead author of the new study published in Astronomy and Astrophysics. "In this way, ultrahot Jupiters stretch out what we think planets should look like."

While telescopes like Spitzer and Hubble can gather some information about the daysides of ultrahot Jupiters, their nightsides are difficult for current instruments to probe.

The new paper proposes a model for what might be happening on both the illuminated and dark sides of these planets. The model is based largely on observations and analysis from three recently published studies, coauthored by Parmentier, Line, and others, that focus on three ultrahot Jupiters, WASP-103b, WASP-18b, and HAT-P-7b.

Jupiter-like exoplanets are 99 percent molecular hydrogen and helium with smaller amounts of water and other molecules. But what their spectra show depends strongly on temperature. Warm-to-hot planets form clouds of minerals, while hotter planets make starlight-absorbing molecules of titanium oxide. Yet to understand ultrahot Jupiter spectra, the research team had to turn to processes more commonly found in stars. 
Image credit: Michael Line/ASU

The new study suggests that fierce winds driven by heating may blow the torn-apart water molecules into the planets' cooler nightside hemispheres. There the atoms can recombine into molecules and condense into clouds, all before drifting back into the dayside to be ripped apart again.

Family resemblance?

Hot Jupiters were the first widely discovered kind of exoplanet, starting back in the mid-1990s. These are cooler cousins to ultrahot Jupiters, with dayside temperatures below 3,600 degrees Fahrenheit (2,000 Celsius).

Water has proven to be common in their atmospheres, and thus when ultrahot Jupiters began to be found, astronomers expected them to show water in their atmospheres as well. But water turned out to be missing on their easily observed daysides, which got theorists looking at alternative, even exotic, compositions.

One hypothesis for why water appeared absent in ultrahot Jupiters has been that these planets must have formed with very high levels of carbon instead of oxygen. Yet this idea could not explain the traces of water sometimes detected at the dayside-nightside boundary.

To break the logjam, the research team took a cue from well-established physical models of stellar atmospheres, as well as "failed stars," known as brown dwarfs, whose properties overlap somewhat with hot and ultrahot Jupiters.

"Unsatisfied with exteme compositions, we thought harder about the problem," Line said. "Then we realized that many earlier interpretations were missing some key physics and chemistry that happens at these ultrahot temperatures."

The team adapted a brown dwarf model developed by Mark Marley, one of the paper's co-authors and a research scientist at NASA's Ames Research Center in Silicon Valley, California, to the case of ultrahot Jupiters. Treating the atmospheres of ultrahot Jupiters more like blazing stars than conventionally colder planets offered a way to make sense of the Spitzer and Hubble observations.

"With these studies, we are bringing some of the century-old knowledge gained from studying the astrophysics of stars, to the new field of investigating exoplanetary atmospheres," Parmentier said.

"Our role in this research has been to take the observed spectra of these planets and model their physics carefully," Line said. "This showed us how to produce the observed spectra using gases that are more likely to be present under the extreme conditions. These planets don't need exotic compositions or unusual pathways to make them."

Contacts and sources:
Robert Burnham
Arizona State University

Citation: From thermal dissociation to condensation in the atmospheres of ultra hot Jupiters: WASP-121b in context
V. Parmentier, M. Line, J. Bean, M. Mansfield, L. Kreidberg, R. Lupu, C. Visscher, J-M. Désert, J. Fortney, M. Deleuil, J. Arcangeli, A. Showman, M. Marley
A&A, Forthcoming article
Received: 20 March 2018 / Accepted: 17 May 2018
DOI: https://doi.org/10.1051/0004-6361/201833059

Soft Hardware: Researchers Incorporate Optoelectronic Diodes into Fibers and Weave Washable Fabrics.

The latest development in textiles and fibers is a kind of soft hardware that you can wear: cloth that has electronic devices built right into it. Researchers incorporated optoelectronic diodes into fibers and wove them into washable fabrics.

Researchers at MIT have now embedded high speed optoelectronic semiconductor devices, including light-emitting diodes (LEDs) and diode photodetectors, within fibers that were then woven at Inman Mills, in South Carolina, into soft, washable fabrics and made into communication systems. This marks the achievement of a long-sought goal of creating “smart” fabrics by incorporating semiconductor devices — the key ingredient of modern electronics — which until now was the missing piece for making fabrics with sophisticated functionality.

This discovery, the researchers say, could unleash a new “Moore’s Law” for fibers — in other words, a rapid progression in which the capabilities of fibers would grow rapidly and exponentially over time, just as the capabilities of microchips have grown over decades.

For the first time, the researchers from MIT and AFFOA have produced fibers with embedded electronics that are so flexible they can be woven into soft fabrics and made into wearable clothing.
For the first time, the researchers from MIT and AFFOA have produced fibers with embedded electronics that are so flexible they can be woven into soft fabrics and made into wearable clothing.
Courtesy of the researchers

The findings are described this week in the journal Nature in a paper by former MIT graduate student Michael Rein; his research advisor Yoel Fink, MIT professor of materials science and electrical engineering and CEO of AFFOA (Advanced Functional Fabrics of America); along with a team from MIT, AFFOA, Inman Mills, EPFL in Lausanne, Switzerland, and Lincoln Laboratory.

Optical fibers have been traditionally produced by making a cylindrical object called a “preform,” which is essentially a scaled-up model of the fiber, then heating it. Softened material is then drawn or pulled downward under tension and the resulting fiber is collected on a spool.

The key breakthrough for producing these new fibers was to add to the preform light-emitting semiconductor diodes the size of a grain of sand, and a pair of copper wires a fraction of a hair’s width. When heated in a furnace during the fiber-drawing process, the polymer preform partially liquified, forming a long fiber with the diodes lined up along its center and connected by the copper wires.

A spool of fine, soft fiber made using the new process shows the embedded LEDs turning on and off to demonstrate their functionality. The team has used similar fibers to transmit music to detector fibers, which work even when underwater.

(Courtesy of the researchers)

In this case, the solid components were two types of electrical diodes made using standard microchip technology: light-emitting diodes (LEDs) and photosensing diodes. “Both the devices and the wires maintain their dimensions while everything shrinks around them” in the drawing process, Rein says. The resulting fibers were then woven into fabrics, which were laundered 10 times to demonstrate their practicality as possible material for clothing.

“This approach adds a new insight into the process of making fibers,” says Rein, who was the paper’s lead author and developed the concept that led to the new process. “Instead of drawing the material all together in a liquid state, we mixed in devices in particulate form, together with thin metal wires.”

One of the advantages of incorporating function into the fiber material itself is that the resulting fiber is inherently waterproof. To demonstrate this, the team placed some of the photodetecting fibers inside a fish tank. A lamp outside the aquarium transmitted music (appropriately, Handel’s “Water Music”) through the water to the fibers in the form of rapid optical signals. The fibers in the tank converted the light pulses — so rapid that the light appears steady to the naked eye — to electrical signals, which were then converted into music. The fibers survived in the water for weeks.

The fiber with embedded LEDs is so fine that it can be used to thread a needle.
The fiber with embedded LEDs is so fine that it can be used to thread a needle.
Courtesy of the researchers

Though the principle sounds simple, making it work consistently, and making sure that the fibers could be manufactured reliably and in quantity, has been a long and difficult process. Staff at the Advanced Functional Fabric of America Institute, led by Jason Cox and Chia-Chun Chung, developed the pathways to increasing yield, throughput, and overall reliability, making these fibers ready for transitioning to industry. At the same time, Marty Ellis from Inman Mills developed techniques for weaving these fibers into fabrics using a conventional industrial manufacturing-scale loom.

“This paper describes a scalable path for incorporating semiconductor devices into fibers. We are anticipating the emergence of a ‘Moore’s law’ analog in fibers in the years ahead,” Fink says. “It is already allowing us to expand the fundamental capabilities of fabrics to encompass communications, lighting, physiological monitoring, and more. In the years ahead fabrics will deliver value-added services and will no longer just be selected for aesthetics and comfort.”

He says that the first commercial products incorporating this technology will be reaching the marketplace as early as next year — an extraordinarily short progression from laboratory research to commercialization. Such rapid lab-to-market development was a key part of the reason for creating an academic-industry-government collaborative such as AFFOA in the first place, he says. These initial applications will be specialized products involving communications and safety. “It's going to be the first fabric communication system. We are right now in the process of transitioning the technology to domestic manufacturers and industry at an unprecendented speed and scale,” he says.

A spool of fine, soft fiber made using the new process shows the embedded LEDs turning on and off to demonstrate their functionality. The team has used similar fibers to transmit music to detector fibers, which work even when underwater.
A spool of fine, soft fiber made using the new process shows the embedded LEDs turning on and off to demonstrate their functionality. The team has used similar fibers to transmit music to detector fibers, which work even when underwater.
Courtesy of the researchers

In addition to commercial applications, Fink says the U.S. Department of Defense — one of AFFOA’s major supporters — “is exploring applications of these ideas to our women and men in uniform.”

Beyond communications, the fibers could potentially have significant applications in the biomedical field, the researchers say. For example, devices using such fibers might be used to make a wristband that could measure pulse or blood oxygen levels, or be woven into a bandage to continuously monitor the healing process.

The research was supported in part by the MIT Materials Research Science and Engineering Center (MRSEC) through the MRSEC Program of the National Science Foundation, by the U.S. Army Research Laboratory and the U.S. Army Research Office through the Institute for Soldier Nanotechnologies. This work was also supported by the Assistant Secretary of Defense for Research and Engineering.

Contacts and sources:
David L. Chandler
Massachusetts Institute of Technology
Citation: Diode fibres for fabric-based optical communications
Michael Rein, Valentine Dominique Favrod, Chong Hou, Tural Khudiyev, Alexander Stolyarov, Jason Cox, Chia-Chun Chung, Chhea Chhav, Marty Ellis, John Joannopoulos, Yoel Fink.. Nature, 2018; 560 (7717): 214 DOI: 10.1038/s41586-018-0390-x

Europe Facing Catastrophic Flooding by The End of The Century

Without increased investment in coastal adaptation, the expected annual damage caused by coastal floods in Europe could increase from €1.25 billion today to between €93 billion and €961 billion by the end of the century.

Due to an increase in extreme sea levels driven by global warming, these coastal floods could impact up to 3.65 million people every year in Europe by 2100, compared to around 102,000 today.

One in three EU citizens lives within 50 km of the coast.

The findings are the result of two JRC studies, where scientists project both how global extreme sea levels will change during the present century and how rising seas combined with socioeconomic change will affect future losses from coastal flooding.

Scientists found unprecedented flood risk unless timely adaptation measures are taken. 
Credit: ©jerik, Adobe Stock 2018

They considered both a scenario where moderate policy efforts are made to mitigate climate change and a 'business as usual' scenario.

The scientists found unprecedented flood risk unless timely adaptation measures are taken.

In order for Europe to keep future coastal flood losses constant relative to the size of the economy, defence structures need to be installed or reinforced to withstand increases in extreme sea levels ranging from 0.5 to 2.5 metres.
Why the added risk?

Climate change is the main driver of the projected rise in costs from coastal flooding, with the importance of coastward migration, urbanisation and rising asset values rapidly declining with time.

This is a change from the current situation globally, where rising risk has primarily been driven by socioeconomic development.

The rising extreme sea levels are primarily driven by the growing volume of water in the oceans as a direct result of temperatures increasing, a process known as thermal expansion.

Another major contributing factor is 'ice mass loss' - ice melting from glaciers and ice sheets in Greenland and Antarctica and making sea levels rise.

In conducting this study, scientists used the JRC's LISCoAsT – Large scale Integrated Sea-level and Coastal Assessment Tool, under the framework of the PESETA project and in cooperation with the European Commission's department for climate action.

LISCoAsT is a coastal flood impact assessment tool that considers the spatial and temporal dynamics of all major components contributing to a flood's severity and impact.

This includes dynamic, gridded projections of exposure, and changes in all extreme sea level components, from sea level to tides and storm surges.

Using the tool, the scientists conducted a global scale assessment accurate to 100 metres, around the same length as a football pitch.

The results of the studies have been published in Nature Climate Change and Nature Communication.

Contacts and sources:
European Commission Joint Research Centre


From Office Windows to Mars: Scientists Debut Super-Insulating Gel

Can a new type of transparent gel, made from readily-available beer waste, help engineers build greenhouses on Mars?

CU Boulder physicists have developed an insulating gel that they say could coat the windows of habitats in space, allowing the settlers inside to trap and store energy from the sun—much like a greenhouse stays warm during the winter. And unlike similar products on the market, the material is mostly see-through.

“Transparency is an enabling feature because you can use this gel in windows, and you could use it in extraterrestrial habitats,” said Ivan Smalyukh, a professor in the Department of Physics. “You could harvest sunlight through that thermally insulating material and store the energy inside, protecting yourself from those big oscillations in temperature that you have on Mars or on the moon.”

The defining feature of aerogels, as their name suggests, is air, Smalyukh explained. By weight, these thin films are 90 percent gas. Engineers achieve this feather weight by generating crisscrossing patterns of solid material that trap air inside billions of tiny pores, similar to the bubbles in bubble wrap. It’s that trapping capacity that makes them such good insulators.

“You create a very tortuous network of these nanoparticles that link together in the aerogel, preventing the heat from going through,” Smalyukh said.

Beer to windows

That same network, however, tends to scatter light, making aerogels look cloudy and explaining why some engineers call them “frozen smoke.”

To make a more translucent gel, Smalyukh and his colleagues begin with the common plant sugar cellulose. By carefully controlling how cellulose molecules link up, the team is able to orient them into a lattice-like pattern.

That pattern is so uniform, he said, that it allows light to pass through unbothered, giving the gel its transparent appearance.

Problem solved. In order to find a ready supply of cellulose for their space-age material, the researchers turned to a substance with humble beginnings: a refreshing IPA.

Beer wort, or the waste liquid produced during the brewing process, can make cellulose when scientists add in specialized bacteria. The researchers began driving to breweries across the Boulder area to collect tubs of the unwanted substance from beer-makers.

“So not only are we recycling and saving this valuable material from entering the landfill, but we’re also producing this raw material cheaply,” said Andrew Hess, a Ph.D. student in physics at CU Boulder.

Currently, it takes the team about two weeks to culture the cellulose, but the rest of the process of making the aerogel moves quickly. The final product of the team’s efforts is a thin, flexible film that is roughly 100 times lighter than glass. This gel is so resistant to heat that you could put a strip of it on your hand and light a fire on top—without feeling a thing.

Joshua De La Cruz, a Ph.D. student in the CU Boulder Materials Science and Engineering Program, pours beer wort into a tray before adding cellulose-producing bacteria.

 Credit: CU Boulder

Mars to Antarctica

While the researchers have their eye on putting this material on space habitats, more immediate applications are already available on Earth.

Most windows are poor insulators. According to the Department of Energy, roughly one-quarter of the energy that is expended to heat and cool buildings in the United States goes toward offsetting the loss of heat through windows, potentially costing building operators billions of dollars per year.

Qingkun Liu inspects a jar holding dissolved cellulose, which, in this state, naturally scatters light, producing a rainbow-like appearance.

 Credit: CU Boulder 

Covering glass in sheets of the aerogel, however, could dramatically slow down the loss of heat, said Hess, who also leads the project’s tech-to-market transfer work. And you wouldn’t have to replace the windows in the process.

“Windows are incredibly expensive to replace,” Hess said. “We’re envisioning a retrofitting product that would basically be a peel-and-stick film that a consumer would buy at Home Depot.”

Researchers pick up a pane of glass from a tub used to settle the final aerogel film.
Credit: CU Boulder

On a larger scale, cities could use the gel to retrofit windows on skyscrapers, dramatically increasing energy efficiency.

To get to that point, the researchers say that they would need to learn how to produce more aerogel faster. But they’re already moving forward on that goal. Smalyukh’s team has been exploring partnerships with window manufacturing companies.

Earlier this summer, they won NASA’s 2018 iTech competition, a national contest that seeks out Earth-bound technologies that might one day help people travel to space. The team’s research has also been supported by the National Science Foundation and the Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E).

“Our approach so far has been around windows,” Hess said. “However, we also see our technology being enabling for so many other applications, including smart clothes, for insulating cars and protecting firefighters.”

And there are more fanciful uses, too. Smalyukh said that one afternoon, his lab got a visit from the young daughter of one of his team members. For fun, the researchers coated her hand in the non-toxic aerogel, giving her a crystal-clear and flexible glove. That inspired Smalyukh to think about using aerogels to make clothing that would be both ultra-warm and transparent.

“This opens your imagination,” he said. “We were joking about going to the South Pole and doing a group outing with penguins. You could sun tan on top of the ice.”

Contacts and sources:
Daniel Strain
University of Colorado at Boulder

New Evidence of How Neolithic People Adapted to Climate Change

Research led by the University of Bristol has uncovered evidence that early farmers were adapting to climate change 8,200 years ago.

The study, published today in the journal Proceedings of the National Academy of Sciences of the United States of America(PNAS), centred on the Neolithic and Chalcolithic city settlement of Çatalhöyük in southern Anatolia, Turkey which existed from approximately 7500 BC to 5700 BC.

During the height of the city's occupation a well-documented climate change event 8,200 years ago occurred which resulted in a sudden decrease in global temperatures caused by the release of a huge amount of glacial meltwater from a massive freshwater lake in northern Canada.

In situ pottery at the archaeological site of Çatalhöyük.

Credit: Çatalhöyük Research Project.

Examining the animal bones excavated at the site, scientists concluded that the herders of the city turned towards sheep and goats at this time, as these animals were more drought-resistant than cattle. Study of cut marks on the animal bones informed on butchery practices: the high number of such marks at the time of the climate event showed that the population worked on exploiting any available meat due to food scarcity.

The authors also examined the animal fats surviving in ancient cooking pots. They detected the presence of ruminant carcass fats, consistent with the animal bone assemblage discovered at Çatalhöyük. For the first time, compounds from animal fats detected in pottery were shown to carry evidence for the climate event in their isotopic composition.

Indeed, using the "you are what you eat (and drink)" principle, the scientists deducted that the isotopic information carried in the hydrogen atoms (deuterium to hydrogen ratio) from the animal fats was reflecting that of ancient precipitation. A change in the hydrogen signal was detected in the period corresponding to the climate event, thus suggesting changes in precipitation patterns at the site at that time.

The paper brings together researchers from the University of Bristol’s Organic Geochemistry Unit (School of Chemistry) and the Bristol Research Initiative for the Dynamic Global Environment (School of Geographical Sciences).

Co-authors of the paper include archaeologists and archaeozoologists involved in the excavations and the study of the pottery and animal bones from the site.

Dr Mélanie Roffet-Salque, lead author of the paper, said: “Changes in precipitation patterns in the past are traditionally obtained using ocean or lake sediment cores.

“This is the first time that such information is derived from cooking pots. We have used the signal carried by the hydrogen atoms from the animal fats trapped in the pottery vessels after cooking.

“This opens up a completely new avenue of investigation – the reconstruction of past climate at the very location where people lived using pottery.”

Co-author, Professor Richard Evershed, added: “It is really significant that the climate models of the event are in complete agreement with the H signals we see in the animal fats preserved in the pots.”

“The models point to seasonal changes farmers would have had to adapt to – overall colder temperatures and drier summers – which would have had inevitable impacts on agriculture.”

Contacts and sources:
Melanie Roffet-Salque University of Bristol

Citation:  ‘Evidence for the impact of the 8.2-kyBP climate event on Near Eastern early farmers’ by M. Roffet-Salque et al in PNAS.  

Meteorite Bombardment Likely To Have Created The Earth's Oldest Rocks

Scientists have found that 4.02 billion year old silica-rich felsic rocks from the Acasta River, Canada - the oldest rock formation known on Earth - probably formed at high temperatures and at a surprisingly shallow depth of the planet's nascent crust. The high temperatures needed to melt the shallow crust were likely caused by a meteorite bombardment around half a billion years after the planet formed. This melted the iron-rich crust and formed the granites we see today. These results are presented for the first time at the Goldschmidt conference in Boston tomorrow (14 August), following publication in the peer-reviewed journal Nature Geoscience*.

Deep time. Oldest rock. A fist-sized sample from the Acasta River, an obscure little drainage up near Great Bear Lake, Northwest Territories, Canada. This was collected from what is the oldest known rock formation on the planet, clocking in at 4.03 billion years in age, as dated by many labs. Postscript: Further age-dating has now pushed matters in the Acasta River locale back to 4.2 billion years

At the Ice Age's End, North Atlantic Ocean Currents Changed Increasing Greenland Ice Sheet Melt

New research has found that changes in North Atlantic Ocean circulation at the end of the last ice age triggered a considerable increase in Greenland Ice Sheet melt.

The Greenland Ice Sheet is a vast body of ice covering roughly 80% of the surface of Greenland. It is the second largest ice body in the world, after the Antarctic, and holds enough water to raise sea levels by six metres if melted in its entirety. The research published in the Nature journal Scientific Reports, led by researchers at Keele University and the University of New South Wales, has found that the rate of melt of one of Greenland’s largest outlet glaciers dramatically increased around 12,000 years ago, during a period known as the ‘Younger Dryas’. This occurred despite atmospheric temperatures up to 10°C cooler than those of today

Rapid melt of Greenland Ice Sheet at end of last ice age reveals importance of ocean circulation, study finds
Credit:  Keele University

With many current Greenland glaciers sensitive to ocean warming, this study highlights the vulnerability of the Greenland Ice Sheet to changing ocean circulation, and shows that increased ice-sheet melt – such as that happening today – can enhance the effects of climate change, and could drive further melt of the Greenland Ice Sheet under scenarios of projected warming over the next century.

Lead researcher Eleanor Rainsley, from Keele University’s ICELAB, said: “The rate of glacier thinning that we discovered in southeast Greenland 12,000 years ago is comparable to that seen in some of today’s most rapidly melting polar glaciers.

“Our team analysed these results against climate models, and observed that the changes during the Younger Dryas– a cooling period driven by the input of meltwater from the great ice sheets that once covered North America and Europe – led to a reconfiguration of ocean circulation that caused substantial ocean warming at depth. Previously masked by the apparent cooling of the surface ocean waters, it shows that this massive reorganisation of the North Atlantic Ocean triggered enhanced melt of the Greenland Ice Sheet, overwhelming the cooling effect of the atmosphere.”

The circulation of the world’s ocean waters, also known as the ‘global ocean conveyor belt’, drives the transport of heat around the planet from the equator to the poles. Disruption to this conveyor belt, through altering how much fresh, cold water is added to the oceans from ice-sheet and glacier melt, can dramatically influence our climate.

Co-author Professor Chris Fogwill, Professor of Glaciology and Palaeoclimatology at Keele University, said: “As the climate warms, we are already seeing huge changes to North Atlantic circulation. Given recent findings that show feedbacks such as we have found here could lead us into a ‘Hothouse Earth’ scenario, it is crucial that we incorporate this into the computer models we use to predict future change. These feedbacks – knock-on effects of climate change which can amplify change even further – could lead to the destabilisation of the Earth’s climate, tipping it into a state of warmer temperatures and higher sea levels from which it will be hard to return.”

Dr Laurie Menviel, from University of New South Wales, said: “This study shows the importance of investigating extreme environmental changes preserved in the recent geological record to better understand what we might experience in the future.”

Contacts and sources:
Keele University

Citation: Rainsley et al., Greenland ice mass loss during the Younger Dryas driven by Atlantic Meridional Overturning Circulation feedbacks, Scientific Reports. www.nature.com/articles/s41598-018-29226-8 DOI: 10.1038/s41598-018-29226-8

Unnoticed Behavior of Water: Scientists Find New Properties of H2O

A team of scientists has uncovered new molecular properties of water—a discovery of a phenomenon that had previously gone unnoticed.

Liquid water is known to be an excellent transporter of its own autoionization products; that is, the charged species obtained when a water molecule (H2O) is split into protons (H+) and hydroxide ions (OH−). This remarkable property of water makes it a critical component in emerging electrochemical energy production and storage technologies such as fuel cells; indeed, life itself would not be possible if water did not possess this characteristic.

An ocean wave.

 Credit:  (c)iStock/Nuture

Water is known to consist an intricate network of weak, directional interactions known as hydrogen bonds. For nearly a century, it was thought that the mechanisms by which water transports the H+ and OH− ions were mirror images of each other – identical in all ways except for directions of the hydrogen bonds involved in the process.

Current state-of-the-art theoretical models and computer simulations, however, predicted a fundamental asymmetry in these mechanisms. If correct, this asymmetry is something that could be exploited in different applications by tailoring a system to favor one ion over the other.

Experimental proof of the theoretical prediction has remained elusive because of the difficulty in directly observing the two ionic species. Different experiments have only provided glimpses of the predicted asymmetry.

A team of scientists at New York University, led by Professor Alexej Jerschow and including Emilia Silletta, an NYU postdoctoral fellow, and Mark Tuckerman, a professor of chemistry and mathematics at NYU, devised a novel experiment for nailing down this asymmetry. The experimental approach involved cooling water down to its so-called temperature of maximum density, where the asymmetry is expected to be most strongly manifest, thereby allowing it to be carefully detected.

It is common knowledge that ice floats on water and that lakes freeze from the top. This is because water molecules pack into a structure with lower density than that of liquid water—a manifestation of the unusual properties of water: the density of liquid water increases just above the freezing point and reaches a maximum at four degrees Celsius (39 degrees Fahrenheit), the so-called temperature of maximum density; this difference in density dictates that liquid is always situated below ice.

By cooling water down to this temperature, the team employed nuclear magnetic resonance methods (the same type of approach is medically in magnetic resonance imaging) to show that the difference in lifetimes of the two ions reaches a maximum value (the greater the lifetime, the slower the transport). By accentuating the difference in lifetimes, the asymmetry became glaringly clear.

As noted previously, water consists of one oxygen atom and two hydrogen atoms, but the hydrogen atoms are relatively mobile and can hop from one molecule to another, and it is this hopping that renders the two ionic species so mobile in water.

In seeking explanations for the temperature-dependent characteristics, the researchers focused on the speed with which such hops can occur.

Prior research had indicated that two main geometrical arrangements of hydrogen bonds (one associated with each ion) facilitate the hops. The researchers found that one of the arrangements led to significantly slower hops for OH− than for H+ at four degrees Celsius. Being that this is also the temperature of maximum density, the researchers felt that the two phenomena had to be linked. In addition, their results showed that molecules’ hopping behavior changed abruptly at this temperature.

“The study of water’s molecular properties is of intense interest due to its central role in enabling physiological processes and its ubiquitous nature,” says Jerschow, the corresponding author of this study. “The new finding is quite surprising and may enable deeper understanding of water's properties as well as its role as a fluid in many of nature’s phenomena.”

Tuckerman, who was one of the first researchers to predict the asymmetry in the transport mechanisms and the difference in the hydrogen bond arrangements, says, “It is gratifying to have this clear piece of experimental evidence confirm our earlier predictions. We are currently seeking new ways to exploit the asymmetry between H+ and OH− transport to design new materials for clean energy applications, and knowing that we are starting with a correct model it central to our continued progress.”

A large swath of other research, ranging from the study of enzyme function in the body to understanding how living organisms can thrive in harsh conditions, including sub-freezing temperatures and highly acidic environments, will also be impacted by the team’s findings.

The research was supported by grants from the National Science Foundation (CHE 1710046, CHE-1534374) and partially by the MRSEC Program of the National Science Foundation (DMR-1420073).

Contacts and sources:
James Devitt
New York University

Citation: Unusual Proton Transfer Kinetics in Water at the Temperature of Maximum Density
Emilia V. Silletta, Mark E. Tuckerman, Alexej Jerschow.. Physical Review Letters, 2018; 121 (7)
  1. DOI: 10.1103/PhysRevLett.121.076001

Drones Learn to Herd Birds Away From Airports

Scientists have equipped a drone with a new algorithm to herd birds without human input, saving aeroplanes and birds alike.

The technology, developed by CalTech, Imperial College London, and the Korea Advanced Institute of Science and Technology (KAIST), allows a single drone to herd an entire flock of birds away from the airspace of an airport, without harming individual birds or the flock’s formation.

This is the first time a drone has been trialled for saving aeroplanes and birds without human input. The researchers tested the equipped drone on flocks of birds near a field in Daejeon, Korea. The experiments were guided and analysed by a team including Dr Aditya Paranjape from Imperial’s Department of Aeronautics.

They found that their single autonomous drone could keep a flock of dozens of birds out of a designated airspace. The findings are published in IEEE Transactions on Robotics.

Fly-by damage

Engineers at Caltech have developed a new control algorithm that enables a single drone to herd an entire flock of birds away from the airspace of an airport. The algorithm is presented in a study in IEEE Transactions on Robotics.
Credit: Soon-Jo Chung/Caltech

The project was inspired by the 2009 "Miracle on the Hudson," when US Airways Flight 1549 struck a flock of geese shortly after takeoff and pilots Chesley Sullenberger and Jeffrey Skiles were forced to land in the Hudson River off Manhattan.

"The passengers on Flight 1549 were only saved because the pilots were so skilled," says Soon-Jo Chung, an associate professor of aerospace and Bren Scholar in the Division of Engineering and Applied Science as well as a JPL research scientist, and the principal investigator on the drone herding project. "It made me think that next time might not have such a happy ending. So I started looking into ways to protect airspace from birds by leveraging my research areas in autonomy and robotics."

Current strategies for controlling airspace include modifying the surrounding environment to make it less attractive to birds, using trained falcons to scare flocks off, or even piloting a drone to scare the birds. These strategies can be costly or—in the case of the hand-piloted drone—unreliable, says Chung, who is a researcher at Caltech's Center for Autonomous Systems and Technologies.

"When herding birds away from an airspace, you have to be very careful in how you position your drone. If it's too far away, it won't move the flock. And if it gets too close, you risk scattering the flock and making it completely uncontrollable. That's difficult to do with a piloted drone."
An illustration of how the bird herding drone works
Credit: Imperial College London

Herding relies on the ability to manage a flock as a single, contained entity—keeping it together while shifting its direction of travel. Each bird in a flock reacts to changes in the behavior of the birds nearest to it. Effective herding requires an external threat—in this case, the drone—to position itself in such a way that it encourages birds along the edge of a flock to make course changes that then affect the birds nearest to them, who affect birds farther into the flock, and so on, until the entire flock changes course. The positioning has to be precise, however: if the external threat gets too zealous and rushes at the flock, the birds will panic and act individually, not collectively.

In 2013, while he was an assistant professor at the University of Illinois at Urbana-Champaign, Chung received a National Science Foundation CAREER Award to tackle the problem. Originally, Chung intended to build a self-guided, flapping robot whose flight would mimic that of a falcon, figuring that the bioinspired design would make it even more effective at controlling flocks by presenting them with a natural-seeming threat. While the work in that direction did yield an entirely new style of drone—the "Bat Bot" that Chung unveiled in 2017—he found that an off-the-shelf quadrotor drone was just as effective at herding birds.

To teach the drone to herd autonomously, Chung and his colleagues, including Aditya Paranjape of Imperial College London, one of his former graduate students, studied and derived a mathematical model of flocking dynamics to describe how flocks build and maintain formations, how they respond to threats along the edge of the flock, and how they then communicate that threat through the flock. Their work improves on algorithms designed for herding sheep, which only needed to work in two dimensions, instead of three.

"We carefully studied flock dynamics and interaction between flocks and pursuers to develop a mathematically sound herding algorithm that ensures safe relocation of flocks using autonomous drones," says Kyunam Kim, postdoctoral scholar in aerospace at Caltech and a co-author of the IEEE paper.

Once they were able to generate a mathematical description of flocking behaviors, the researchers reverse engineered it to see exactly how approaching external threats would be responded to by flocks, and then used that information to create a new herding algorithm that produces ideal flight paths for incoming drones to move the flock away from a protected airspace without dispersing it.

An illustration of how the bird herding drone works

Credit: Imperial College London

"My previous research focused on spacecraft and drone swarms, which turned out to be surprisingly relevant for this project," Chung says.

The team tested the algorithm on a flock of birds near a field in Korea and found that a single drone could keep a flock of dozens of birds out of a designated airspace. The effectiveness of the algorithm is only limited by the number and size of the incoming birds, Chung says, adding that the team plans to explore ways to scale the project up for multiple drones dealing with multiple flocks.

The study, titled "Robotic Herding of a Flock of Birds Using an Unmanned Aerial Vehicle," was also co-authored by Hyunchul Shim from the Korea Advanced Institute of Science and Technology. Support for the research came from the National Science Foundation.

Contacts and sources:
Imperial College London

Citation:  "Robotic Herding of a Flock of Birds Using an Unmanned Aerial Vehicle," 

It’s a Tough Life for Chimpanzees in the Savannah


Chimpanzees are generally known as the ripe fruit specialist among the great apes but also incorporate other food items such as leaves and seedpods into their diets. 

Savannah chimpanzees are thought to rely on these non-fruit resources more than their forest counterparts. The mechanical properties of plant foods can vary substantially but to date there were no comparative data available for chimpanzee populations living in distinct habitat types. Adam van Casteren of the Max Planck Weizmann Center for Integrative Archaeology and Anthropology at the Max Planck Institute for Evolutionary Anthropology went out to compare the material properties of various plant foods eaten by chimpanzees in a tropical rainforest (Ngogo, Uganda) and a savannah woodland (Issa Valley, Tanzania).

The Issa Valley in Tanzania is a mosaic habitat made up mainly of gallery forest and woodland savannah.

Credit: Adam van Casteren

 Using a portable mechanical tester, he measured the physical properties of plant tissues and found that some plant parts from the mosaic savannah woodland habitat, such as the outer casing of the Strychnos fruit, had much higher toughness and stiffness values than the plant tissues he tested from the rainforest. "I was surprised to see that some values even exceed those recorded for orangutan foods as they are generally considered to consume the most mechanically challenging diet of all the great apes," says van Casteren.

The scientists also combined their plant food mechanical data with data from a stable isotope analysis from both plant and chimpanzee hair samples. Carbon stable isotopes are commonly used to reconstruct dietary ecology and habitat use of living and extinct primates. Although the carbon isotope values of plants were remarkably similar in both habitats, the isotope data obtained from chimpanzee hair suggested that savannah chimpanzees frequently feed on plants growing in open canopy areas. These likely include those plants which are particularly demanding when processed with the teeth. 

The outer casing of the Strychnos fruit had much higher toughness and stiffness values than the plant tissues the researchers tested from the rainforest.
Credit: Adam van Casteren

The authors believe that the consumption of such tough foods is facilitated by the large front teeth of chimpanzees. "While some chimpanzee populations are using tools to crack open nuts, others like these savannah chimpanzees still rely on their teeth to get access to nutrients. Such differences in selection pressures acting on the teeth are likely to have played a key role during the evolution of hominins," says Kornelius Kupczik, co-author and Track Leader of the Max Planck Weizmann Center.

Dental morphology, food mechanical properties and carbon stable isotopes are all highly relevant for reconstructing past diets of our early ancestors in Africa. "If we better understand the foundations and interactions of food material properties, dental wear processes and isotopes in extant chimpanzees this opens a window into the past and helps to interpret the data obtained from fossil specimens who lived in the African savannah several million years ago," concludes co-author Vicky Oelze from the University of California in Santa Cruz and the Max Planck Institute for Evolutionary Anthropology, who conducted the stable isotope analysis.

Contacts and sources:
Dr. Adam van Casteren / Dr. Kornelius Kupczik
Max Planck Institute for Evolutionary Anthropology, Leipzig
Dr. Vicky M. Oelze
University of California, Santa Cruz

Citation: Food mechanical properties and isotopic signatures in forest versus savannah dwelling eastern chimpanzees.  Adam van Casteren, Vicky M. Oelze, Samuel Angedakin, Ammie K. Kalan, Mohamed Kambi, Christophe Boesch, Hjalmar S. Kühl, Kevin E. Langergraber, Alexander K. Piel, Fiona A. Stewart, Kornelius Kupczik: Communications Biology, 10 August 2018

Fake, Low-Quality Medicines Prevalent in The Developing World, New Study Finds

A new study from the University of North Carolina at Chapel Hill found that substandard and falsified medicines, including medicines to treat malaria, are a serious problem in much of the world. In low- and middle-income countries, more than 13 percent of the essential medicines that satisfy the priority health care needs of the population fall in this category. When looking specifically at African countries, the portion of substandard and falsified medicines rises to almost 19 percent.

Falsified medicines are medical products that deliberately and fraudulently misrepresent their identity, composition or source. Substandard medicines are real medical products that fail to meet quality standards or specifications for a variety of reasons, including poor manufacturing, shipping or storage conditions, or because the drug is sold beyond its expiration date.

Researchers analyzed 96 previous studies of falsified and substandard medicines and each of the studies tested more than 50 medications. The team found that antimalarials and antibiotics were the medicines most commonly sold in substandard or falsified conditions. In low- and middle-income countries, 19 percent of antimalarials and 12 percent of antibiotics are substandard or falsified.

The color-coded map shows the percentage of fake and substandard medicines found in 63 developing countries.

Credit: UNC Eshelman School of Pharmacy

Sachiko Ozawa, an associate professor at the UNC Eshelman School of Pharmacy, led the research along with collaborators. The paper published in the journal JAMA Network Open on August 10.

"The prevalence of substandard and falsified medicines is a substantial public health problem because these medicines can be ineffective or harmful and can prolong illnesses, cause poisoning or lead to dangerous drug interactions," said Ozawa. "Our study shows that a concerted global effort is needed to improve supply chain management for medicines and to identify solutions to this understudied issue."

The researchers searched five databases for studies related to substandard and falsified medicines. They reviewed 256 studies and included 96 studies in their analysis.

"We need more global collaboration to implement laws on drug quality, increase quality control capacity, and improve surveillance and data sharing," said James Herrington, a professor in the UNC Gillings School of Global Public Health and a co-author of the study. "This can strengthen the global supply chain against poor quality medicines, improve health outcomes by reducing antimicrobial and anti-parasitic resistance and, ultimately, help governments, businesses and patients save money."

The team's analysis found limited information on the economic impact of poor quality medicines, with the estimates of market size ranging widely from $10 billion to $200 billion. Substandard and falsified medicines can burden health systems by diverting resources to ineffective or harmful therapies and cause additional treatment costs and reduced worker productivity due to treatable illnesses, but these effects have not been measured.

Ozawa's research collaborators included Daniel Evans, Tatenda Yemeke and Sarah Laing of the UNC Eshelman School of Pharmacy; James Herrington of UNC Gillings School of Global Public Health; Sophia Bessias of Enterprise Analytics and Data Sciences with University of North Carolina Health Care; and Deson Haynie of the University of Virginia School of Medicine.

Contacts and sources:
Audrey Smith
University of North Carolina at Chapel Hill

Citation: Prevalence and Estimated Economic Burden of Substandard and Falsified Medicines in Low- and Middle-Income CountriesA Systematic Review and Meta-analysis http://dx.doi.org/10.1001/jamanetworkopen.2018.1662

Easter Island's Society May Not Have Collapsed

You probably know Easter Island as "the place with the giant stone heads." This remote island 2,300 miles off the coast of Chile has long been seen as mysterious--a place where Polynesian seafarers set up camp, built giant statues, and then destroyed their own society through in-fighting and over-exploitation of natural resources. However, a new article in the Journal of Pacific Archaeology hints at a more complex story--by analyzing the chemical makeup of the tools used to create the big stone sculptures, archaeologists found evidence of a sophisticated society where the people shared information and collaborated.

"For a long time, people wondered about the culture behind these very important statues," says Field Museum scientist Laure Dussubieux, one of the study's authors. "This study shows how people were interacting, it's helping to revise the theory."

Examples of the Easter Island statues, or moai.

Credit: Dale Simpson, Jr.

"The idea of competition and collapse on Easter Island might be overstated," says lead author Dale Simpson, Jr., an archaeologist from the University of Queensland. "To me, the stone carving industry is solid evidence that there was cooperation among families and craft groups."

The first people arrived on Easter Island (or, in the local language, Rapa Nui) about 900 years ago. "The founding population, according to oral tradition, was two canoes led by the island's first chief, Hotu Matu?a," says Simpson, who is currently on the faculty of the College of DuPage. Over the years, the population rose to the thousands, forming the complex society that carved the statues Easter Island is known for today. These statues, or moai, often referred to as "Easter Island heads," are actually full-body figures that became partially buried over time. The moai, which represent important Rapa Nui ancestors, number nearly a thousand, and the largest one is over seventy feet tall.

According to Simpson, the size and number of the moai hint at a complex society. "Ancient Rapa Nui had chiefs, priests, and guilds of workers who fished, farmed, and made the moai. There was a certain level of sociopolitical organization that was needed to carve almost a thousand statues," says Simpson.

Easter Island moai

Credit: Dale Simpson, Jr.

Recent excavations of four statues in the inner region of Rano Raraku, the statue quarry, were conducted by Jo Anne Van Tilburg of Cotsen Institute of Archaeology, UCLA and director of the Easter Island Statue Project, along with her Rapa Nui excavation team. To better understand the society that fabricated two of the statues, Simpson, Dussubieux, and Van Tilburg took a detailed look at twenty one of about 1,600 stone tools made of volcanic stone called basalt that had been recovered in Van Tilburg's excavations. About half of the tools, called toki, recovered were fragments that suggested how they were used.

For Van Tilburg, the goal of the project was to gain a better understanding of how tool makers and statue carvers may have interacted, thus gaining insight into how the statue production industry functioned. "We wanted to figure out where the raw materials used to manufacture the artifacts came from," explained Dussubieux. "We wanted to know if people were taking material from close to where they lived."

There are at least three different sources on Easter Island that the Rapa Nui used for material to make their stone tools. The basalt quarries cover twelve square meters, an area the size of two football fields. And those different quarries, the tools that came from them, and the movement between geological locations and archaeological sites shed light on prehistoric Rapa Nui society.

"Basalt is a grayish rock that doesn't look like anything special, but when you look at the chemical composition of the basalt samples from different sources, you can see very subtle differences in concentrations of different elements," explains Dussubieux. "Rock from each source is different because of the geology of each site."

Dussubieux led the chemical analysis of the stone tools. The archaeologists used a laser to cut off tiny pieces of stone from the toki and then used an instrument called a mass spectrometer to analyze the amounts of different chemical elements present in the samples. The results pointed to a society that Simpson believes involved a fair amount of collaboration.

Easter Island statues in Rano Raraku.
Credit: Dale Simpson, Jr.

"The majority of the toki came from one quarry complex--once the people found the quarry they liked, they stayed with it," says Simpson. "For everyone to be using one type of stone, I believe they had to collaborate. That's why they were so successful--they were working together."

To Simpson, this level of large-scale cooperation contradicts the popular narrative that Easter Island's inhabitants ran out of resources and warred themselves into extinction. "There's so much mystery around Easter Island, because it's so isolated, but on the island, people were, and still are, interacting in huge amounts," says Simpson. While the society was later decimated by colonists and slavery, Rapa Nui culture has persisted. "There are thousands of Rapa Nui people alive today--the society isn't gone," Simpson explains.

Van Tilburg urges caution in interpreting the study's results. "The near exclusive use of one quarry to produce these seventeen tools supports a view of craft specialization based on information exchange, but we can't know at this stage if the interaction was collaborative. It may also have been coercive in some way. Human behavior is complex. This study encourages further mapping and stone sourcing, and our excavations continue to shed new light on moai carving." In addition to potentially paving the way for a more nuanced view of the Rapa Nui people, Dussubieux notes that the study is important because of its wider-reaching insights into how societies work. "What happens in this world is a cycle, what happened in the past will happen again," says Dussubieux. "Most people don't live on a small island, but what we learn about people's interactions in the past is very important for us now because what shapes our world is how we interact."

Contacts and sources:
Kate GolembiewskiField Museum

Sunday, August 12, 2018

North American Diets Require More Land Than We Have Concludes Study

If the global population adopted recommended North American dietary guidelines, there wouldn't be enough land to provide the food required, according to a new study co-authored by University of Guelph researchers.

The researchers found that global adherence to United States Department of Agriculture (USDA) guidelines would require one giga-hectare of additional land--roughly the size of Canada--under current farming practice. Their findings were published in PLOS ONE today.

"The data shows that we would require more land than what we have if we adopt these guidelines. It is unsustainable," said Prof. Madhur Anand, director of the Global Ecological Change and Sustainability lab where the study was undertaken.
Credit: Gary Csoff

"This is one of the first papers to look at how the adoption of Western dietary guidelines by the global population would translate into food production, including imports and exports, and specifically how that would dictate land use and the fallouts of that," she said.

Although the dietary guidelines are viewed as an improvement on the current land-intensive diet of the average American, the researchers say that dietary guidelines should be further developed using not just health but also global land use and equity as criteria.

"We need to look at diet not just as an individual health issue but as an ecosystem health issue," said Anand, a professor in U of G's School of Environmental Sciences (SES).

Prof. Madhur Anand

Credit:  University of Guelph

The authors found a strong east-west division worldwide. Most Western Hemisphere countries would use less land by adopting a USDA guideline diet, while most Eastern Hemisphere countries would use more land.

Co-authors of the paper are U of G Prof. Evan Fraser, holder of a Canada Research Chair in Global Food Security; SES graduate student Sarah Rizvi; Chris Pagnutti, an NSERC post-doctoral researcher in SES; and Prof. Chris Bauch, Department of Applied Mathematics, University of Waterloo.

"We need to understand human and environmental systems in a coordinated manner, and this is where the interdisciplinary aspect of the work shines. This is also why we worked with an applied mathematician," said Anand.

The authors call for international coordination of national dietary guidelines because global lands are a limited resource.

"This could be similar, at least in principle, to how greenhouse gas emissions are increasingly being coordinated internationally to address another major global problem: climate change," Anand said.

Fraser, scientific director of the Food from Thought project and director of the Arrell Food Institute at U of G, added: "One of the 21st century's great challenges is to develop diets that are both healthy for our bodies and sustainable for the planet.

"Developing the technologies and insights to help industry and consumers is part of what many of us at the University of Guelph are working on through the Food from Thought initiative."

This research was supported by an NSERC Discovery Grant and is associated with the University of Guelph's Food from Thought project, supported by the Canada First Research Excellence Fund. The project is intended to increase the sustainability and productivity of global food production through leading-edge data science, agri-food research and biodiversity science.

Contacts and sources:
Prof. Madhur Anand / Prof. Evan Fraser
University of Guelph

Citation: Global land use implications of dietary trends Sarah Rizvi, Chris Pagnutti, Evan Fraser, Chris T. Bauch, Madhur Anand Published: August 8, 2018https://doi.org/10.1371/journal.pone.0200781 http://dx.doi.org/10.1371/journal.pone.0200781

Ice Sheets of the Last Ice Age Seeded the Ocean with Silica

New research led by glaciologists and isotope geochemists from the University of Bristol has found that melting ice sheets provide the surrounding oceans with the essential nutrient silica.

Silica is needed by a group of marine algae (the microscopic plants of the oceans) called diatoms, who use it to build their glassy cell walls (known as frustules).

These plankton take up globally significant amounts of carbon - they remove carbon dioxide from the atmosphere via photosynthesis, and act as a natural carbon sink when they die and fall to the bottom of the ocean - and form the base of the marine food chain.

Researchers from the Bristol Glaciology Centre look over the vast Greenland Ice Sheet, which stretches beyond the horizon, during a field campaign lasting over three months in 2015. The researchers camped in a remote region of Greenland, monitoring a large meltwater river and taking samples to look at the silica concentration and isotopic signature.

Credit: Dr Jon Hawkings, University of Bristol

The study published today in the journal Nature Communications suggests that glacial meltwater, both in the present and during past ice ages, contains silica that could be useful in sustaining the growth of diatoms in the oceans around ice sheets, which are home to economically important fisheries and marine life.

The researchers show that the silica in glacial meltwaters from the Greenland Ice Sheet has a distinctive isotopic signature, different to the that found in other rivers.

Researchers have previously found that diatoms and sponges (which build their skeletons from silica) gradually buried in ocean sediments since the last ice age have a different silicon isotopic signature to their modern-day relatives.

This lighter isotopic signature was thought to be the result of changing diatom activity and ocean currents during and between ice ages. However, researchers now think that a change in the isotopic signature of the river waters supplied to the ocean might account for these shifts.

Dr Jon Hawkings, lead author of the study from the University of Bristol's School of Geographical Sciences, Bristol Glaciology Centre and Cabot Institute for the Environment said: "In this study we wanted to find out if silica in glacial meltwaters from a large ice sheet (Greenland) has a distinctive isotopic signature.

Vast quantities of milky glacial meltwaters sourced from Greenland Ice Sheet make their way toward the ocean. The milky colour of meltwaters is caused by the large quantities of finely ground rock flour carried by the meltwater.

Credit: Dr Jon Hawkings, University of Bristol

"If it does, then the huge quantities of meltwater coming from melting ice sheets during the deglaciation could account for some of the change in ocean silicon isotopic signature that have been recorded previously. Rapid ice sheet melting during the last ice age led to periods of sea level rise great than 3 cm per year (compared to around 0.3 cm per year at present).

"At peaks ice sheet melting an estimated 25,000 km3 of water was entering the oceans from melting ice sheets every year - this is more than three times the amount of water currently flowing from the Amazon river.

"If silica carried by ice sheet meltwaters does have a distinctive isotopic signature, then this reshapes how important ice sheets, and large deglaciation events, are in global biogeochemical cycles."

Researchers examined silica concentrations in meltwaters and the silicon isotopic signature of those meltwaters (referred to as δ30Si, which we're using as a "marker" of glacial silica), alongside a computer model using this data, and results from a marine sediment core off the coast of Iceland which shows distinctive changes in the silicon isotopic composition of sponges during periods of ice sheet collapse. They wanted to determine:

Glacial meltwaters carrying silica with a distinctive isotopic signature flow into marine ecosystems, where microscopic algae known as diatoms use the silica to build their glassy cell walls.

Credit: Dr Jon Hawkings, University of Bristol

If glacial meltwaters have a distinct silica signal that can be used to trace inputs into the ocean

If there were any changes to the isotopic signal over the course of a summer melt period (which might reflect where the silica comes from within a glacier)

To predict the impact from rapidly melting ice sheets of the last ice age on marine ecosystems

The study concluded that glaciers and ice sheets are an under-appreciated component of the silica cycle, exporting large quantities of reactive silica into the ocean, which could be used by diatoms. This might, say researchers, have major implications for the health of marine siliceous organisms during periods of significant ice cover and rapid deglaciation.

The study showed ice sheet runoff has the lightest silicon isotopic composition ever measured in running water - values for glacial meltwaters are much lower than any measurements of non-glacial riverine runoff.

Using this data combined with a simple computer model of the ocean since the last ice age maximum (around 21,000 years ago) the study predicts that up to a third of the observed changes in the silicon isotopic signature of siliceous organisms can be explained by the melting of the massive ice sheets that at their peak covered up to 30 percent of the land surface, including much of North America and Europe, including much of the United Kingdom.

The isotopic composition also helps to explain that meltwater is sourced from further into the ice sheet as the annual melting period progresses, flushing liquid water stored hundreds of meters under the ice.

Dr Hawkings added: "Our findings re-frame the traditional view of the importance of ice sheets in biogeochemical cycles, specifically of the silica cycle.

"Previously the huge quantities of water and sediment delivered from the ice sheets of the last ice age wasn't fully considered as having a significant impact on marine chemistry and biology, but our study points that this is likely an oversight.

"Our interpretation of a number of other isotopic systems, and of changes to biogeochemical cycles since the last glacial maximum therefore likely needs re-evaluating."

There is still a lot of work needed to discover the importance of ice sheets in global nutrient cycles.

The research team will now work to establish if other glaciers carry significant quantities of isotopically distinctive silica to the oceans, by visiting a range of glaciers around Greenland (and further afield) to see if this relationship holds.

Dr Kate Hendry, one of the Bristol co-authors, is currently leading a European Research Council funded project, ICY-LAB, to provide unprecedented insights into nutrient cycling, biomineralization, and the taxonomy and biogeography of siliceous organisms in an ecologically important region near Greenland. This will link into a Leverhulme Trust funded project based in Greenland this year led by Cabot Institute Director Professor Jemma Wadham, which will further explore the role of sub-ice weathering in the global silica cycle.

These projects will further establish what the passage of glacial meltwaters and sediments from glaciers through fjord systems (meltwater and seawater mixing zones) does to silica concentration and its isotopic composition, for example what proportion of the fine sediments carried by glacial meltwaters which contain a large proportion of the "diatom-available" silica are buried in the fjord. This is important for predicting how much silica is exported further off the coast of the ice sheets into the open ocean.

The researchers are also planning to use more complex and realistic computer models to delve deeper into the potential changes in the global silica cycle since the last glacial maximum. These might include more accurate representations of ocean currents, recycling of silica in the water column, and potential changes to the marine algal community.

The work was funded by the Leverhulme Trust and the Natural Environment Research Council (NERC).

Contacts and sources:
Jon Hawkings
University of Bristol
Citation:  The silicon cycle impacted by past ice sheets Jon R. Hawkings, Jade E. Hatton, Katharine R. Hendry, Gregory F. de Souza, Jemma L. Wadham, Ruza Ivanovic, Tyler J. Kohler, Marek Stibal, Alexander Beaton, Guillaume Lamarche-Gagnon, Andrew Tedstone, Mathis P. Hain, Elizabeth Bagshaw, Jennifer Pike & Martyn Tranter Nature Communications volume 9, Article number: 3210 (2018) https://www.nature.com/articles/s41467-018-05689-1