Friday, September 30, 2016

Three Earth-Sized Worlds Orbiting Low-Mass Star Discovered

The discovery of three Earth-sized planets likely orbiting a low-mass star is looking like the real thing.

Astronomers combined the power of the 8-meter Gemini South telescope in Chile with an extremely high-resolution camera to scrutinize the star TRAPPIST-1. Previous observations of the star, which is only about 8% the mass of our Sun, revealed dips in the star’s light output that would be expected if several Earth-sized planets orbited the star. However, the situation would be greatly complicated if, upon closer examination, the star was found to have a yet-unseen stellar companion.

No such companion was found with Gemini, which essentially seals the case for multiple Earth-sized planets orbiting TRAPPIST-1.

Artist’s concept of what the view might be like from inside the TRAPPIST-1 exoplanetary system showing three Earth-sized planets in orbit around the low-mass star. This alien planetary system is located only 40 light years away. Gemini South telescope imaging, the highest resolution images ever taken of the star, revealed no additional stellar companions providing strong evidence that three small, probably rocky planets orbit this star. 
Credit: Robert Hurt/JPL/Caltech.

Steve Howell of NASA’s Ames Research Center led the extremely high-resolution observations using the Differential Speckle Survey Instrument (DSSI), an instrument he has used before at both Gemini telescopes to probe other exoplanetary systems. The new observations reinforced the hypothesis that several Earth-sized planets are responsible for the fluctuations in the star’s brightness. 

“By finding no additional stellar companions in the star’s vicinity we confirm that a family of smallish planets orbit this star,” says Howell. “Using Gemini we can see closer to this star than the orbit of Mercury to our Sun. Gemini with DSSI is unique in being able to do this, bar none.”

The research, led by Howell, is published in the September 13th issue of The Astrophysical Journal Letters.

TRAPPIST-1 is what astronomers call a late M-type star; stars which are small, ultra-cool (compared to most stars), and faint. Late M stars are so faint that the only specimens we can observe are relatively close-by in space and, as the Gemini observations demonstrate, allow astronomers to probe very close to these stars in the search for companions.

“While no current telescope can actually image an Earth-size planet around another star, even if orbiting a nearby star such as TRAPPIST-1, our instrument on Gemini allows us to detect close companion stars and even brown dwarfs.” says Elliott Horch, [Southern Connecticut State University] co-author of the paper. “Such observations validate not only the existence of exoplanets, but their small size as well.”

M stars are of great interest to astronomers today as their diminutive size allows easier detection of small, Earth-size planets. The intrinsic faintness of M stars means that potentially habitable planets will have short orbital periods, on the order of weeks. Such planets will be the targets of detailed study by both ground- and space-based telescopes, studies that will attempt to measure the composition of their atmospheres and see if they are indeed Earth-like beyond just their size.

The discovery of TRAPPIST-1’s likely exoplanet pedigree began late in 2015 with data from the TRAPPIST (the TRansiting Planets and PlanetesImals Small Telescope) project. This work, published in the 12 May 2016 issue of the journal Nature, and led by Michael Gillon, observed TRAPPIST-1 over 62 nights. During that period, the star was found to fluctuate in a manner that is consistent with at least three Earth-sized planets orbiting and periodically eclipsing and blocking part of the star’s light from our view on the Earth. 

While work is still ongoing to refine the total number of planets, two of them appear to orbit in 1.5 and 2.4 days and are so close that they receive four and two times the radiation that our Earth receives from the Sun, respectively. The third planet is more difficult to characterize, having possible orbital periods between 4 to 73 days. However, this third planet’s most likely period, 18 days, would place this world well within the system’s habitable-zone where liquid water could exist on its surface.

The Gemini observations, made with the DSSI instrument, were made during a temporary visit of the instrument at the Gemini South telescope in Chile. “Gemini’s flourishing Visitor Instrument program is producing superb results in all areas of astronomy,” said Chris Davis, a program director at the U.S. National Science Foundation, one of the agencies that funds the International Gemini Observatory and which also provided initial funding for DSSI. “The DSSI observations of the TRAPPIST-1 system of exoplanets is just one example. The instrument team and their collaborators deserve credit for building such a versatile and productive instrument and also for making it available to all of Gemini’s users."

The DSSI instrument on Gemini provides a unique capability to characterize the environment around exoplanetary systems. The instrument provides extreme-resolution images by taking multiple extremely short (60 millisecond) exposures of a star to capture fine detail and “freeze” the turbulence caused by the Earth’s atmosphere. By combining the images and removing the momentary distortions caused by the Earth’s atmosphere, the final images yield a resolution equal to what the telescope would produce if it was in space. With this technique, called speckle interferometry, astronomers can see details at, or very near, the theoretical limit of the 8-meter Gemini mirror yielding the highest-resolution single telescope images available to astronomers. The available resolution is like being able to separate an automobile’s two headlights at a distance of about 2000 miles.

Contacts and sources:
Dr. Steve B. Howell, NASA Ames Research Center
Dr. Elliott P. Horch, Professor of Physics, Southern Connecticut State University
Peter Michaud, Gemini Observatory

A Male Mammal without the Y Chromosome Confounds Researchers

Hokkaido University researchers have revealed that key sex-determining genes continue to operate in a mammalian species that lacks the Y chromosome, taking us a step further toward understanding sex differentiation.

In most placental mammals, the Y chromosome induces male differentiation during development, whereas embryos without it become female. The sex-determining gene SRY is present on the Y chromosome and induces other regulatory genes that suppress female differentiation. The Amami spiny rat (Tokudaia osimensis) is exceptional as it lacks a Y chromosome and thus the SRY gene, raising the question of why male differentiation can still occur.

The Amami spiny rat (Tokudaia osimensis) lacks a Y chromosome

Credit: Hokkaido University

Tomofumi Otake and Asako Kuroiwa of Hokkaido University in Japan performed gene mapping to determine the chromosomal locations of sex-related genes in the T. osimensis genome. They then compared its nucleotide and amino acid sequences with those of the mouse and rat. Furthermore, using cultured cells, they examined how the sex-related genes were regulated.

SRY has been well-investigated in previous research and is known to turn on a range of regulatory genes such as Sox9 and AMH that play an important role in male differentiation. The team’s results suggest that, even though there is no SRY gene in T. osimensis, the regulatory genes that normally turns on are present and operate as they do in other placental mammals.

Chromosomal location of the sex-related gene AMH (arrowheads) in male T. osimensis. Chromosomes are double-stained with different fluorescent substances (red and blue) for the precise gene mapping.

Credit: Otake T. and Kuroiwa A. Molecular mechanism of male differentiation is conserved in the SRY-absent mammal. Tokudaia osimensis. September 9, 2016, Scientific Reports

“We speculate that there is an unknown gene that acts as a substitute for SRY in T. osimensis,” says Professor Kuroiwa. “The mammalian Y chromosome has been shrinking through an evolutionary process by reducing the number of its genes, and some scientists think that it will completely disappear at some point. I hope our research will help in the understanding of the sex determination mechanism that is independent on the Y chromosome and its evolutionary aspect.”

Contacts and sources:
Professor Asato Kuroiwa. Hokkaido University
Naoki Namba. Hokkaido University

Citation: Otake T. and Kuroiwa A. Molecular mechanism of male differentiation is conserved in the SRY-absent mammal. Tokudaia osimensis. September 9, 2016, Scientific Reports. 
DOI: 10.1038/srep32874

New Insights into 'Golden Age' of Galaxy Formation

An international team of astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) has explored the same distant corner of the universe first revealed in the iconic image of the Hubble Ultra Deep Field (HUDF).

The new ALMA observations, which are significantly deeper and sharper than previous surveys at millimeter wavelengths, trace the previously unknown abundance of star-forming gas at different points in time, providing new insights into the "Golden Age" of galaxy formation approximately 10 billion years ago.

ALMA surveyed the Hubble Ultra Deep Field, uncovering new details of the star-forming history of the universe. This animated GIF reveals one such galaxy (orange), rich in carbon monoxide, showing it is primed for star formation. The blue features are galaxies imaged by Hubble. 

The researchers presented their findings today at the Half a Decade of ALMA conference in Palm Springs, California. The results also are accepted for publication in a series of seven scientific papers appearing in the Astrophysical Journal.

Animation revealing ALMA's exploration of the Hubble Ultra Deep Field. The new ALMA observations, which are significantly deeper and sharper than previous surveys at millimeter wavelengths, reveal a population of galaxies that is not clearly evident in any other deep surveys of the sky and trace the previously unknown abundance of star-forming gas at different points in time. The ALMA data (orange) is supperimposed on the Hubble data. 
Credit: B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO); NASA/ESA Hubble. Music: Mark Mercury

Just like the pioneering deep-field observations with the NASA/ESA Hubble Space Telescope, scientists using ALMA surveyed a seemingly unremarkable section of the cosmos in a so-called "blind search." This type of observation probes a specific region of space to see what can be discovered serendipitously rather than homing in on a predetermined target, like an individual galaxy or star-forming nebula.

ALMA surveyed the Hubble Ultra Deep Field, uncovering new details of the star-forming history of the universe. This close-up image reveals one such galaxy (orange), rich in carbon monoxide, showing it is primed for star formation. The blue features are galaxies imaged by Hubble. 

"We conducted the first fully blind, three-dimensional search for cool gas in the early universe," said Chris Carilli, an astronomer with the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico, and member of the research team. "Through this, we discovered a population of galaxies that is not clearly evident in any other deep surveys of the sky."]

Unlike Hubble, which studies visible and infrared light from bright cosmic objects like stars and galaxies, ALMA studies the faint millimeter-wavelength light emitted by cold gas and dust, the raw material of star formation. ALMA's ability to see a completely different portion of the electromagnetic spectrum allows astronomers to study a different class of astronomical objects, such as massive star-forming clouds and protoplanetary disks, as well as objects that are too faint to observe in visible light.

A trove of galaxies, rich in dust and cold gas (indicating star-forming potential) was imaged by ALMA (orange) in the Hubble Ultra Deep Field. 

The new ALMA observations were specifically tailored to detect galaxies that are rich in carbon monoxide (CO), a tracer molecule that identifies regions rich in molecular gas and primed for star formation. Even though these molecular gas reservoirs give rise to star formation in galaxies, they are invisible to Hubble. ALMA can therefore reveal the "missing half" of the galaxy formation and evolution process.

Animated GIF showing a trove of galaxies, rich in dust and cold gas (indicating star-forming potential) that was imaged by ALMA (orange) in the Hubble Ultra Deep Field. 

"These newly detected carbon-monoxide rich galaxies represent a substantial contribution to the star-formation history of the universe," said Roberto Decarli, an astronomer with the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany, and member of the research team. "With ALMA we have opened a pathway for studying the early formation and assembly of galaxies in the Hubble Ultra Deep Field."

The new ALMA observations of the HUDF include two distinct, yet complementary types of data: continuum observations, which reveal dust emission and star formation, and a spectral line survey, which looks at the cold molecular gas fueling star formation. The line survey is particularly valuable because it includes information about the degree to which light from distant objects has been redshifted by the expansion of the universe. Greater redshift means that an object is further away and seen farther back in time.

Looking back through cosmic time in the Hubble Ultra Deep Field, ALMA traced the presence of carbon monoxide gas. This enabled astronomers to create a 3-D image of the star-forming potential of the cosmos. 
Credit: R. Decarli (MPIA); ALMA (ESO/NAOJ/NRAO)

With the most recent observations, astronomers were able to create a three-dimensional map of star-forming gas as it evolves over cosmic time, from the present to about two billion years after the Big Bang.

"The new ALMA results imply a rapidly rising gas content in galaxies with increasing look-back time," said Manuel Aravena, an astronomer with the Diego Portales University in Santiago, Chile, and member of the research team. "This increasing gas content is likely the root cause for the remarkable increase in star formation rates during the peak epoch of galaxy formation, some 10 billion years ago."

Astronomers specifically selected the area of study in the HUDF, a region of space in the constellation Fornax, so ground-based telescopes in the Southern Hemisphere, like ALMA, could probe the region as well, expanding our knowledge of the very distant universe.

Interview with astronomer Fabian Walter explaining recent ALMA observations of the Hubble Ultra Deep Field. 
Credit: B. Saxton & J. Hellerman (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO); NASA/ESA Hubble
The current ALMA observations, which required approximately 40 hours of observing time, cover an area of the sky that is one arcminute on each side, about one sixth of the total HUDF. An approved future 150-hour observing campaign dubbed ASPECS – the ALMA Spectroscopic Survey in the Hubble UDF -- will cover a much larger area and further illuminate the star-forming potential history of the universe.

"By supplementing our understanding of this missing star-forming material, the forthcoming large spectroscopic survey will complete our view of the well-known galaxies in the iconic Hubble Ultra Deep Field," said Fabian Walter, also with the MPIA and member of the research team.

Contacts and sources:
Charles Blue
The National Radio Astronomy Observatory  

Spiral Arms Embrace Young Star; First Direct Evidence for Density Waves in a Protoplanetary Disk

Swirling around the young star Elias 2-27 is a stunning spiral-shape pinwheel of dust. This striking feature, seen with the Atacama Large Millimeter/submillimeter Array (ALMA), is the product of density waves – gravitational perturbations in the star's protoplanetary disk that produce sweeping arms reminiscent of a spiral galaxy, but on a much smaller scale.

“These observations are the first direct evidence for density waves in a protoplanetary disk,” said Laura Pérez, an astronomer and Alexander von Humboldt Research Fellow with the Max Planck Institute for Radio Astronomy in Bonn, Germany, and lead author on a paper published in the journal Science.

ALMA peered into the Ophiuchus star-forming region to study the protoplanetary disk around the young star Elias 2-27. Astronomers discovered a striking spiral pattern in the disk. This feature is the product of density waves – gravitational perturbations in the disk. 

Credit: L. Pérez (MPIfR), B. Saxton (NRAO/AUI/NSF), ALMA (ESO/NAOJ/NRAO), NASA/JPL Caltech/WISE Team

Previously, astronomers noted compelling spiral features on the surfaces of protoplanetary disks, but it was unknown if these same spiral patterns also emerged deep within the disk where planet formation takes place. ALMA, for the first time, was able to peer deep into the mid-plane of a disk and discover the clear signature of spiral density waves.

Nearest to the star, ALMA found a familiar flattened disk of dust, which extends past what would be the orbit of Neptune in our own solar system. Beyond that point, ALMA detected a narrow band with significantly less dust, which may be indicative of a planet in formation. Springing from the outer edge of this gap are two sweeping spiral arms that extend more than 10 billion kilometers away from their host star.

Finding density waves at these extreme distances may have implications for planet-formation theory, Pérez notes. The standard picture of planet formation begins with small planetesimals coming together under gravity. In the outer reaches of a protoplanetary disk, where there is a dearth of planetesimals, disk instabilities may also lead directly to the formation of a planet. ALMA’s detection of spiral density waves may be evidence that such a process is taking place.

Elias 2-27 is located approximately 450 light-years from Earth in the Ophiuchus star-forming complex. Even though it contains only about half the mass of our Sun, this star has an unusually massive protoplanetary disk. The star is estimated to be at least one million years old and still encased in its parent molecular cloud, obscuring it from optical telescopes.

ALMA discovered sweeping spiral arms in the protoplanetary disk surrounding the young star Elias 2-27. This spiral feature was produced by density waves – gravitational perturbations in the disk.

“There are still questions of how these features form. Perhaps they are the result of a newly forged planet interacting with the protoplanetary disk or simply gravitational instabilities driven by the shear mass of the disk,” said Andrea Isella, an astronomer at Rice University in Houston, Texas, and co-author of the paper.

“Fortunately, the power of ALMA will be used in the future to answer this puzzle,” concludes Pérez. “ALMA will further dissect this and other similar disks in an upcoming large program, helping astronomers understand the seemingly chaotic forces that eventually give rise to stable planetary systems like our own.”

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Contacts and sources: 
Charles Blue
National Radio Astronomy Observatory

New Technique for Finding Weakness in Earth’s Crust

Scientists have developed a method to estimate weakness in the Earth’s outer layers which will help explain and predict volcanic activity and earthquakes.

Published in the journal Science today, the research describes a new model of the Earth’s movement in the upper crust through to upper mantle (400km below the surface), allowing predictions at a much smaller scale than previously possible.

The research is a collaboration between researchers at the University of Illinois in the US and University of Adelaide in Australia.
Geodynamic modelling relies on knowing the ‘viscosity’ or resistance to changing shape of the Earth’s outer layers.
Credit: Jiashun Hu, University of Illinois

Geodynamic modelling relies on knowing the ‘viscosity’ or resistance to changing shape of the Earth’s outer layers.

Geodynamic modelling relies on knowing the ‘viscosity’ or resistance to changing shape of the Earth’s outer layers.

“Producing realistic models of these movements has been difficult because the small scale variations in viscosity are often poorly known,” says co-author Dr Derrick Hasterok, from the University of Adelaide’s School of Physical Sciences.

Comparison between relative viscosity of the Earth and common food items.
Comparison between relative viscosity of the Earth and common food items.
Credit: University of Adelaide

“In essence, we’ve developed a method to estimate small scale (between one and 10 kilometer) variations of viscosity within the upper 400 km of the Earth’s crust using surface-based electromagnetic imaging techniques.”University of Adelaide
Comparison between relative viscosity of the Earth and common food items.
The resulting model allows the dramatic improvement of flow models which can be used to make predictions about the forces driving tectonic plate deformation and sources of potential seismic and volcanic activity.

“This method will aid our understanding of the processes happening that cause earthquakes and volcanic activity,” says Dr Hasterok. “We’ll be able to see why earthquakes and volcanoes have occurred in the past and look for places where this might potentially happen in the future.”

The method they have developed uses an electromagnetic imaging technique called magnetotellurics to estimate the electrical conductivity beneath the Earth's surface.

“The same factors which affect electrical conductivity ─ temperature, water content, and the presence of molten material (magma) ─ also affect the viscosity or strength. The hotter, wetter or more molten, the weaker the structure,” says lead author Dr Lijun Liu, from the University of Illinois.

“We’ve been able to look at processes operating beneath the Earth’s surface at a much smaller scale than previous geodynamic modelling.”

The researchers used data from a magnetotelluric survery of western United States to show their model works. Currently there is a continent-wide project mapping the Australian upper mantle using the same electromagnetic technique, and the researchers believe applying this data to their new model will bring improved understanding of volcanic and earthquake activity along the southeastern and eastern coast of Australia.

Contacts and sources:
Dr Derrick Hasterok, University of Adelaide
Dr Lijun Liu, University of Illinois at Urbana-Champaign

Ancient Reptile with Bizarre Forelimb Evolution Found

Fossil remains from an ancient reptile known as Drepanosaurus reveals unusual skeletal adaptations in the forelimb that scientists have never before recorded in land animals. A Stony Brook University-led national team of paleontologists published their findings in Current Biology. Their findings suggest that more than 200 million years ago reptiles had already evolved specialized modern ecological roles with their strange forelimb adaptation.

The research stems from a decade-long project collecting Late Triassic fossils, including those of Drepanosaurus, from the Hayden Quarry in Ghost Ranch, northern New Mexico. Drepanosaurs are an extinct group of reptiles that although lizard-like are not lizards nor are they dinosaurs. Most were small (only 1 to 2 feet in length) and known to have lived exclusively during the Late Triassic (235 to 201 million years ago). Prior to the team’s discoveries at Ghost Ranch, Drepanosaurus was known from decades-old, badly crushed skeletons from Italy.

New fossils from 212 million-year-old rocks in New Mexico indicate that the small reptile Drepanosaurus used its massive claw and powerful and unusual limp arm to rip away tree bark to expose insects within it. 

Credit: Victor Leshyk

In nearly all four-limbed vertebrates, including in diverse species such as dolphins, bats, or birds, the forelimb consists of two elongate and parallel bones—the radius and ulna. These bones contact a set of wrist bones that form the bridge between the forearm and the hand. However, the researchers found that in Drepanosaurus the radius and ulna are no longer parallel, and the ulna is flat and retracted toward the elbow. Additionally two of the wrist bones have effectively moved into the forearm.

“Many of the Drepanosaur fossils we collected are preserved in three dimensions but are very fragile”, said co-author Alan H Turner, PhD, Associate Professor in the Department of Anatomical Sciences at Stony Brook University School of Medicine. “Because of this we were able to leverage high resolution imaging, such as microCT, to reveal aspects of the forelimb and claw morphology previously unattainable from the Italian fossils. This proved critical in unraveling the strange anatomy of these animals.”

“Drepanosaurus really stretches the bounds of what we thought were the evolutionary constraints on limb evolution,” added Dr. Adam Pritchard, lead author and a postdoctoral fellow at Yale University. “Ecologically, the animal seems to be a sort of chameleon-anteater hybrid, which is really bizarre for the Triassic Period. It possesses a totally unique forelimb among vertebrate animals.

“When you combine this with a claw nearly as large as the arm, you get an arm well adapted for powerful hook-and-pull digging. Think of anteaters digging into insect mounds.”

In addition to the forelimb specialization, Drepanosaurus had grasping feet and a claw-like structure at the end of the tail that might have assisted a life spent in the trees.

The research was funded by the National Science Foundation, the Stony Brook Research Foundation, University of California Museum of Paleontology, University of Utah, Field Museum Women’s Board, and the National Geographic Society Committee for Research & Exploration.

Co-authors of the paper are Randall Irmis of the University of Utah, Sterling Nesbitt of Virginia Polytechnic Institute and State University, and Nathan Smith of the Dinosaur Institute at the Natural History Museum of Los Angeles County.

Contacts and sources:
Stony Brook University

Plastic Pollution Has Truly Reached the Furthest Ends of The Earth

Scientists working in the mid-Atlantic and south-west Indian Ocean have found evidence of microfibers ingested by deep sea animals including hermit crabs, squat lobsters and sea cucumbers, revealing for the first time the environmental fallout of microplastic pollution.

The UK government recently announced that it is to ban plastic microbeads, commonly found in cosmetics and cleaning materials, by the end of 2017. This followed reports by the House of Commons Environmental Audit Committee about the environmental damage caused microbeads. The Committee found that a single shower can result in 100,000 plastic particles entering the ocean.

Credit: Robinson-Isis ROV-ERC

Researchers from the universities of Bristol and Oxford, working on the Royal Research Ship (RRS) James Cook at two sites, have now found evidence of microbeads inside creatures at depths of between 300m and 1800m. This is the first time microplastics – which can enter the sea via the washing of clothes made from synthetic fabrics or from fishing line nets – have been shown to have been ingested by animals at such depth.

The results are published in the journal Scientific Reports.

Laura Robinson, Professor of Geochemistry in Bristol’s School of Earth Sciences, said: “This result astonished me and is a real reminder that plastic pollution has truly reached the furthest ends of the Earth.”

Sea pen - type of coral 

Credit David Shale

Microplastics are generally defined as particles under 5mm in length and include the microfibres analysed in this study and the microbeads used in cosmetics that will be the subject of the forthcoming Government ban.

Among the plastics found inside deep-sea animals in this research were polyester, nylon and acrylic. Microplastics are roughly the same size as ‘marine snow’ – the shower of organic material that falls from upper waters to the deep ocean and which many deep-sea creatures feed on.

Dr Michelle Taylor of Oxford University’s Department of Zoology, and lead author of the study, said: “The main purpose of this research expedition was to collect microplastics from sediments in the deep ocean – and we found lots of them. Given that animals interact with this sediment, such as living on it or eating it, we decided to look inside them to see if there was any evidence of ingestion. What’s particularly alarming is that these microplastics weren’t found in coastal areas but in the deep ocean, thousands of miles away from land-based sources of pollution.”

Microplastic fibre on hermit crab claw

Credit Michelle Taylor 

The animals were collected using a remotely operated underwater vehicle. The study, funded by the European Research Council (ERC) and the Natural Environment Research Council (NERC), was a collaboration between The University of Oxford, the University of Bristol, the Natural History Museum in London, and Staffordshire University’s Department of Forensic and Crime Science, which made sure the results were robust and the study was free from potential contamination.

Dr Claire Gwinnett, Associate Professor in Forensic and Crime Science at Staffordshire University, said: “Existing forensic approaches for the examination of fibres are tried and tested for their robustness and must stand up to the scrutiny of the courts of law. These techniques were employed in this research in order to effectively reduce and monitor contamination and therefore provide confidence in the fact that the microplastics found were ingested, and not from the laboratory or other external contaminant.

“Using forensic laboratory techniques, we have identified that microplastics are present in ingested material from deep sea creatures. Forensic science is still a fairly new science, but we are delighted that our work and techniques are starting to inform other sciences and important environmental research such as this.”

Contacts and sources:
University of Bristol

Paper: ‘Plastic microfibre ingestion by deep-sea organisms’ by M Taylor, L Robinson, et al is published in the journalScientific Reports:

Rosetta Collides with Comet in Controlled Impact, Videos

ESA’s historic Rosetta mission has concluded as planned, with the controlled impact onto the comet it had been investigating for more than two years.

Rosetta was an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander was provided by a consortium led by DLR, MPS, CNES and ASI. Rosetta was the first mission in history to rendezvous with a comet and escort it as they orbited the Sun together. It was also the first to deploy a lander to a comet’s surface, and later end its mission in a controlled impact on the comet.

Comets are time capsules containing primitive material left over from the epoch when the Sun and its planets formed. By studying the gas, dust and structure of the nucleus and organic materials associated with the comet, via both remote and in situ observations, the Rosetta mission is a key to unlocking the history and evolution of our Solar System.

Confirmation of the end of the mission arrived at ESA’s control centre in Darmstadt, Germany at 11:19 GMT (13:19 CEST) with the loss of Rosetta’s signal upon impact.

Landing site

Rosetta carried out its final manoeuvre last night at 20:50 GMT (22:50 CEST), setting it on a collision course with the comet from an altitude of about 19 km. Rosetta had targeted a region on the small lobe of Comet 67P/Churyumov–Gerasimenko, close to a region of active pits in the Ma’at region.

Comet from 51 m – wide-angle camera

The descent gave Rosetta the opportunity to study the comet’s gas, dust and plasma environment very close to its surface, as well as take very high-resolution images.

Pits are of particular interest because they play an important role in the comet’s activity. They also provide a unique window into its internal building blocks.

The information collected on the descent to this fascinating region was returned to Earth before the impact. It is now no longer possible to communicate with the spacecraft.

“Rosetta has entered the history books once again,” says Johann-Dietrich Wörner, ESA’s Director General. “Today we celebrate the success of a game-changing mission, one that has surpassed all our dreams and expectations, and one that continues ESA’s legacy of ‘firsts’ at comets.”

“Thanks to a huge international, decades-long endeavour, we have achieved our mission to take a world-class science laboratory to a comet to study its evolution over time, something that no other comet-chasing mission has attempted,” notes Alvaro Giménez, ESA’s Director of Science.

“Rosetta was on the drawing board even before ESA’s first deep-space mission, Giotto, had taken the first image of a comet nucleus as it flew past Halley in 1986.

“The mission has spanned entire careers, and the data returned will keep generations of scientist busy for decades to come.”

Rosetta’s planned impact point in Ma’at shown in context with Philae’s first and final touchdown sites. All three sites are on the smaller of Comet 67P/Churyumov–Gerasimenko’s two lobes.

“As well as being a scientific and technical triumph, the amazing journey of Rosetta and its lander Philae also captured the world’s imagination, engaging new audiences far beyond the science community. It has been exciting to have everyone along for the ride,” adds Mark McCaughrean, ESA’s senior science advisor.

Since launch in 2004, Rosetta is now in its sixth orbit around the Sun. Its nearly 8 billion-kilometre journey included three Earth flybys and one at Mars, and two asteroid encounters.

The craft endured 31 months in deep-space hibernation on the most distant leg of its journey, before waking up in January 2014 and finally arriving at the comet in August 2014.

After becoming the first spacecraft to orbit a comet, and the first to deploy a lander, Philae, in November 2014, Rosetta continued to monitor the comet’s evolution during their closest approach to the Sun and beyond.

“We’ve operated in the harsh environment of the comet for 786 days, made a number of dramatic flybys close to its surface, survived several unexpected outbursts from the comet, and recovered from two spacecraft ‘safe modes’,” says operations manager Sylvain Lodiot.

“The operations in this final phase have challenged us more than ever before, but it’s a fitting end to Rosetta’s incredible adventure to follow its lander down to the comet.”

The decision to end the mission on the surface is a result of Rosetta and the comet heading out beyond the orbit of Jupiter again. Further from the Sun than Rosetta has ever journeyed before, there would be little power to operate the craft.

Rosetta’s final path

Animation of Rosetta’s final trajectory in the last 10 days of its mission at Comet 67P/Churyumov–Gerasimenko.

On 24 September 2016, Rosetta left a close flyover orbit and transfer into the start of a 16 x 23 km orbit that will be used to prepare and line up for the final descent. In the evening of 29 September (20:50 GMT) Rosetta manoeuvred onto a collision course with the comet, beginning the descent from an altitude of 19 km. The spacecraft will fall freely, without further manoeuvres, collecting scientific data during the descent.

The trajectory shown in this animation is created from real data provided in the last month, but may not necessarily follow the exact distance/time details because of natural deviations in the trajectory associated with the comet’s gravity and outgassing. 

Mission operators were also faced with an imminent month-long period when the Sun is close to the line-of-sight between Earth and Rosetta, meaning communications with the craft would have become increasingly more difficult.

“With the decision to take Rosetta down to the comet’s surface, we boosted the scientific return of the mission through this last, once-in-a-lifetime operation,” says mission manager Patrick Martin.

Many surprising discoveries have already been made during the mission, not least the curious shape of the comet that became apparent during Rosetta’s approach in July and August 2014. Scientists now believe that the comet’s two lobes formed independently, joining in a low-speed collision in the early days of the Solar System.

Long-term monitoring has also shown just how important the comet’s shape is in influencing its seasons, in moving dust across its surface, and in explaining the variations measured in the density and composition of the coma, the comet’s ‘atmosphere’.

Some of the most unexpected and important results are linked to the gases streaming from the comet’s nucleus, including the discovery of molecular oxygen and nitrogen, and water with a different ‘flavour’ to that in Earth’s oceans.

Rosetta impact

Together, these results point to the comet being born in a very cold region of the protoplanetary nebula when the Solar System was still forming more than 4.5 billion years ago.

While it seems that the impact of comets like Rosetta’s may not have delivered as much of Earth’s water as previously thought, another much anticipated question was whether they could have brought ingredients regarded as crucial for the origin of life.

Rosetta did not disappoint, detecting the amino acid glycine, which is commonly found in proteins, and phosphorus, a key component of DNA and cell membranes. Numerous organic compounds were also detected ¬by Rosetta from orbit, and also by Philae in situ on the surface.

“It’s a bittersweet ending, but in the end the mechanics of the Solar System were simply against us: Rosetta’s destiny was set a long time ago. But its superb achievements will now remain for posterity and be used by the next generation of young scientists and engineers around the world.”

While the operational side of the mission has finished today, the science analysis will continue for many years to come.

Comet outbursts

Overall, the results delivered by Rosetta so far paint comets as ancient leftovers of early Solar System formation, rather than fragments of collisions between larger bodies later on, giving an unparalleled insight into what the building blocks of the planets may have looked like 4.6 billion years ago.

“Just as the Rosetta Stone after which this mission was named was pivotal in understanding ancient language and history, the vast treasure trove of Rosetta spacecraft data is changing our view on how comets and the Solar System formed,” says project scientist Matt Taylor.

“Inevitably, we now have new mysteries to solve. The comet hasn’t given up all of its secrets yet, and there are sure to be many surprises hidden in this incredible archive. So don’t go anywhere yet – we’re only just beginning."

Contacts and sources:
European Space Agency

Thursday, September 29, 2016

Quantum Weirdness Video: Molecules Filmed in Two States at One Time Like Schroedinger’s Cat

One of the most famous mind-twisters of the quantum world is the thought experiment known as “Schroedinger’s Cat,” in which a cat placed in a box and potentially exposed to poison is simultaneously dead and alive until someone opens the box and peeks inside.

Scientists have known for a long time that an atom or molecule can also be in two different states at once. Now researchers at the Stanford PULSE Institute and the Department of Energy’s SLAC National Accelerator Laboratory have exploited this Schroedinger’s Cat behavior to create X-ray movies of atomic motion with much more detail than ever before.

Just as the hypothetical Schroedinger’s Cat is alive and dead at the same time, molecules hit with a burst of laser light exist in two states at once – excited (top) and unexcited. This weird quantum property allowed scientists at SLAC to make a molecular movie of excited iodine atoms in unprecedented detail. 
Credit: SLAC National Accelerator Laboratory

The first test of this idea, at SLAC’s Linac Coherent Light Source (LCLS) X-ray laser, created the world’s most detailed X-ray movie of the inner machinery of a molecule – in this case, a two-atom molecule of iodine. The results, based on an experiment led by SLAC staff scientist Mike Glownia, were reported in a paper that’s been posted on the arXiv online repository and accepted for publication in Physical Review Letters.

An animation explains the basic concept behind using 'Schroedinger's Cat' states to make a molecular movie.

Credit: SLAC National Accelerator Laboratory

Zooming in on Atomic Vibrations

The team was able to see details of the molecule’s behavior as small as .3 angstrom ­– less than the width of an atom – and as brief as 30 millionths of a billionth of a second, a timescale that captures the vibrations of atoms and molecules. What’s more, they say their method can be retroactively applied to data from past experiments, not just to future studies.

“Our method is fundamental to quantum mechanics, so we are eager to try it on other small molecular systems, including systems involved in vision, photosynthesis, protecting DNA from UV damage and other important functions in living things,” said Phil Bucksbaum, a professor at SLAC and Stanford University and director of PULSE, which is jointly operated by the lab and the university.

The new technique is based on the fact that when a molecule absorbs a short burst of energy, it splits into two versions of itself – one excited, the other not. A follow-up burst of X-ray laser light scatters off both versions of the molecule and recombines to form an X-ray hologram that, after some clever processing, reveals the excited state of the molecule in stunning detail. By stringing together a series of these X-ray snapshots, scientists can make a stop-action movie.

“Our movie, which is based on images from billions of iodine gas molecules, shows all the possible ways the iodine molecule behaves when it’s excited with this amount of energy,” Bucksbaum said.

“We see it start to vibrate, with the two atoms veering toward and away from each other like they were joined by a spring. At the same time, we see the bond between the atoms break, and the atoms fly off into the void. Simultaneously we see them still connected, but hanging out for a while at some distance from each other before moving back in. As time goes on, we see the vibrations die down until the molecule is at rest again. All these possible outcomes happen within a few trillionths of a second.”

This movie, derived from LCLS data, shows an iodine molecule moving in the first 2 trillionths of a second after being excited by a laser pulse. The clouds of blue dots represent the molecule’s two atoms, at top and bottom, which are joined by a bond through the middle. As the molecule starts to vibrate, the atoms oscillate back and forth. In some cases the bonds break and the atoms fly away. Clouds of red dots represent atoms in the unexcited state of the molecule, which exists simultaneously with its excited state in a Schroedinger’s Cat-like quantum paradox. 
(J.M. Glownia et al., Physical Review Letters)

Using Cat States to Make a Movie

Although the initial laser pulse hits only 4 or 5 percent of the molecules in the iodine gas cloud, it would be incorrect to say that only this small fraction was excited and the rest were not, Bucksbaum added. In quantum mechanical terms, every single molecule was excited a little bit, like a Schroedinger’s Cat that’s both dead and alive.

This dual state was key to making the molecular movie. It allowed the X-rays to bounce off both states of a molecule at once and recombine to form a hologram – a pattern of concentric rings that are brighter where the two signals reinforce each other and darker where they cancel each other out. The fact that this pattern formed in the LCLS detector proves that the excited and unexcited states were simultaneously present in each and every molecule, Bucksbaum said; if they had been separated by even a tiny distance, the pattern could not have formed.

The team used mathematical techniques borrowed from atomic physics to amplify the signal from the excited state, which would form the basis of the movie. But the signal from the unexcited state also played an important role, serving as a reference point that helped them reconstruct the behavior of the excited molecule in three dimensions in a process known as “phasing.”

A “film strip” from the molecular movie shows all the possible behaviors of one of the atoms in an iodine molecule that’s been excited with a burst of laser light: a) The light hits and sets the molecule vibrating; b) Yellow areas represent the most intense vibrations; c) The bond holding the molecule together breaks, and the atom flies away; d) The atom remains at some distance from its partner for a while, although their bond still holds; e) The vibrations taper off. All these things take place within 2 picoseconds, or trillionths of a second. 

Credit: J.M. Glownia et al., Physical Review Letters

Any group of molecules hit with a laser pulse will respond the same way, splitting into the equivalent of live and dead cats, Bucksbaum said. But the process can only be clearly and directly observed with intense, ultrashort pulses of coherent light like those from an X-ray laser, and until now no one had thought to take advantage of the Schroedinger’s Cat connection to sharpen images taken with X-rays.

“The X-ray diffraction community had never used these tools the way we did,” said Adi Natan, a PULSE research associate and experimental physicist who led that part of the project. He said the team is already applying their method to data from previous experiments at LCLS to see if they can create more molecular movies.

LCLS is a DOE Office of Science User Facility. The research was funded by the DOE Office of Science and included scientists from PULSE, LCLS and Stanford.

Contacts and sources: 
Andrew Gordon 
SLAC National Accelerator Laboratory

Citation: "Self-referenced coherent diffraction x-ray movie of Angstrom- and femtosecond-scale atomic motion" J.M. Glownia et al., accepted by Physical Review Letters (arXiv:1608.03039)

Praise or Food? What Most Dogs Choose May Surprise You

Given the choice, many dogs prefer praise from their owners over food, suggests a new study published in the journal Social, Cognitive and Affective Neuroscience. The study is one of the first to combine brain-imaging data with behavioral experiments to explore canine reward preferences.

"We are trying to understand the basis of the dog-human bond and whether it's mainly about food, or about the relationship itself," says Gregory Berns, a neuroscientist at Emory University and lead author of the research. "Out of the 13 dogs that completed the study, we found that most of them either preferred praise from their owners over food, or they appeared to like both equally. Only two of the dogs were real chowhounds, showing a strong preference for the food."

Most of the dogs in the experiments preferred praise over food, or liked them both equally. Kady, a Labrador-golden retriever mix, was the top dog when it came to the strength of her preference for praise.

Photo by Gregory Berns, Emory University

Dogs were at the center of the most famous experiments of classical conditioning, conducted by Ivan Pavlov in the early 1900s. Pavlov showed that if dogs are trained to associate a particular stimulus with food, the animals salivate in the mere presence of the stimulus, in anticipation of the food.

"One theory about dogs is that they are primarily Pavlovian machines: They just want food and their owners are simply the means to get it," Berns says. "Another, more current, view of their behavior is that dogs value human contact in and of itself."

Berns heads up the Dog Project in Emory's Department of Psychology, which is researching evolutionary questions surrounding man's best, and oldest friend. The project was the first to train dogs to voluntarily enter a functional magnetic resonance imaging (fMRI) scanner and remain motionless during scanning, without restraint or sedation. In previous research, the Dog Project identified the ventral caudate region of the canine brain as a reward center. It also showed how that region of a dog's brain responds more strongly to the scents of familiar humans than to the scents of other humans, or even to those of familiar dogs.

For the current experiment, the researchers began by training the dogs to associate three different objects with different outcomes. A pink toy truck signaled a food reward; a blue toy knight signaled verbal praise from the owner; and a hairbrush signaled no reward, to serve as a control.

The dogs then were tested on the three objects while in an fMRI machine. Each dog underwent 32 trials for each of the three objects as their neural activity was recorded.

All of the dogs showed a stronger neural activation for the reward stimuli compared to the stimulus that signaled no reward, and their responses covered a broad range. Four of the dogs showed a particularly strong activation for the stimulus that signaled praise from their owners. Nine of the dogs showed similar neural activation for both the praise stimulus and the food stimulus. And two of the dogs consistently showed more activation when shown the stimulus for food.

The dogs then underwent a behavioral experiment. Each dog was familiarized with a room that contained a simple Y-shaped maze constructed from baby gates: One path of the maze led to a bowl of food and the other path to the dog's owner. The owners sat with their backs toward their dogs. The dog was then repeatedly released into the room and allowed to choose one of the paths. If they came to the owner, the owner praised them.

"We found that the caudate response of each dog in the first experiment correlated with their choices in the second experiment," Berns says. "Dogs are individuals and their neurological profiles fit the behavioral choices they make. Most of the dogs alternated between food and owner, but the dogs with the strongest neural response to praise chose to go to their owners 80 to 90 percent of the time. It shows the importance of social reward and praise to dogs. It may be analogous to how we humans feel when someone praises us."

The experiments lay the groundwork for asking more complicated questions about the canine experience of the world. The Berns' lab is currently exploring the ability of dogs to process and understand human language.

"Dogs are hypersocial with humans," Berns says, "and their integration into human ecology makes dogs a unique model for studying cross-species social bonding."

Contacts and sources:
Emory University

Iron Nanoparticles Make Immune Cells Attack Cancer

Stanford researchers accidentally discovered that iron nanoparticles invented for anemia treatment have another use: triggering the immune system’s ability to destroy tumor cells.

Iron nanoparticles can activate the immune system to attack cancer cells, according to a study led by researchers at the Stanford University School of Medicine.

The nanoparticles, which are commercially available as the injectable iron supplement ferumoxytol, are approved by the Food and Drug Administration to treat iron deficiency anemia.

A mouse study found that ferumoxytol prompts immune cells called tumor-associated macrophages to destroy tumor cells.

Credit: Amy Thomas

The mouse study found that ferumoxytol prompts immune cells called tumor-associated macrophages to destroy cancer cells, suggesting that the nanoparticles could complement existing cancer treatments. The discovery, described in a paper published online Sept. 26 in Nature Nanotechnology, was made by accident while testing whether the nanoparticles could serve as Trojan horses by sneaking chemotherapy into tumors in mice.

“It was really surprising to us that the nanoparticles activated macrophages so that they started to attack cancer cells in mice,” said Heike Daldrup-Link, MD, who is the study’s senior author and an associate professor of radiology at the School of Medicine. “We think this concept should hold in human patients, too.”

Daldrup-Link’s team conducted an experiment that used three groups of mice: an experimental group that got nanoparticles loaded with chemo, a control group that got nanoparticles without chemo and a control group that got neither. The researchers made the unexpected observation that the growth of the tumors in control animals that got nanoparticles only was suppressed compared with the other controls.

Getting macrophages back on track

The researchers conducted a series of follow-up tests to characterize what was happening. Experimenting with cells in a dish, they showed that immune cells called tumor-associated macrophages were required for the nanoparticles’ anti-cancer activity; in cell cultures without macrophages, the iron nanoparticles had no effect against cancer cells.

Before this study was done, it was already known that in healthy people, tumor-associated macrophages detect and eat individual tumor cells. However, large tumors can hijack the tumor-associated macrophages, causing them to stop attacking and instead begin secreting factors that promote the cancer’s growth.

The study showed that the iron nanoparticles switch the macrophages back to their cancer-attacking state, as evidenced by tracking the products of the macrophages’ metabolism and examining their patterns of gene expression.

Furthermore, in a mouse model of breast cancer, the researchers demonstrated that the ferumoxytol inhibited tumor growth when given in doses, adjusted for body weight, similar to those approved by the FDA for anemia treatment. Prior studies had shown that the nanoparticles are metabolized over a period of about six weeks, and the new study showed that the anti-cancer effect of a single dose of nanoparticles declined over about three weeks.

The scientists also tested whether the nanoparticles could stop cancer from spreading. In a mouse model of small-cell lung cancer, the nanoparticles reduced tumor formation in the liver, a common site of metastasis in both mice and humans. In a separate model of liver metastasis, pretreatment with nanoparticles before tumor cells were introduced greatly reduced the volume of liver tumors.
Potential clinical applications

The study’s results suggest several possible applications to test in human trials, Daldrup-Link said. For instance, after surgery to remove a potentially metastatic tumor, patients often need chemotherapy but must wait until they recover from the operation to tolerate the severe side effects of conventional chemo. The iron nanoparticles lack the toxic side effects of chemotherapy, suggesting they might be given to patients during the surgical recovery period.

The nanoparticles may also help cancer patients whose tumors can’t be completely removed. “If there are some tumor cells left after surgery, the situation that cancer surgeons call positive margins, we think it might work to inject iron nanoparticles there, and the smaller tumor seeds could potentially be taken care of by our immune system,” Daldrup-Link said.“We think this could bridge the time when the patient is quite sick after surgery, and help keep the cancer from spreading until they are able to receive chemotherapy,” said Daldrup-Link.

The fact that the nanoparticles are already FDA-approved speeds the ability to test these applications in humans, she added.

The new findings will also help cancer researchers conduct more accurate evaluations of nanoparticle-drug combinations, Daldrup-Link said. “In many studies, researchers just consider nanoparticles as drug vehicles,” she said. “But they may have hidden intrinsic effects that we won’t appreciate unless we look at the nanoparticles themselves.”

The study’s lead author is Saeid Zanganeh, PhD, postdoctoral scholar in radiology. Other Stanford co-authors are Gregor Hutter, MD, PhD, visiting instructor in neurosurgery; Ryan Spitler, PhD, senior research scientist in radiology; Olga Lenkov, life science research assistant in the Molecular Imaging Program at Stanford; Morteza Mahmoudi, PhD, a visiting scientist in cardiology; Jukka Sakari Pajarinen, MD, PhD, postdoctoral scholar in orthopaedic surgery; Hossein Nejadnik, MD, PhD, clinical science research associate in pediatric radiology; Stuart Goodman, MD, PhD, professor of surgery; and Michael Moseley, PhD, professor of radiology.

Scientists at the Oregon Health and Science University also contributed to the study.

The research was funded by the National Cancer Institute (grant R21CA176519). Stanford’s Department of Radiology also supported the work.

Contacts and sources:
Erin Digitale
Stanford Medicine


Lighting the Past: X-Ray Analyses Reveal True Colors of Extinct Animals

An international team of scientists led by The University of Manchester has used state-of-the-art X-ray methods to analyse the chemistry of feathers of birds, in order to discover the true colors of extinct ancient animals such as dinosaurs.

Credit: University of Manchester

In order to discover the true colors of ancient animals, scientists are using X-rays to closely examine the chemical details of modern bird feathers.

The researchers were able to map elements that make up pigments responsible for red and black colors in feathers. They hope to use this information to find traces of the same pigments in fossil specimens of extinct animals, such as dinosaurs.  The team published their results in the journal Scientific Reports.

This latest discovery means that scientists may be able to go beyond monochrome in their depictions of fossilized creatures, and make steps towards portraying their colors more accurately. Melanin is the dominant pigment in mammals and birds that gives them either a black/dark brown color, for example in ravens, or a reddish/yellow hue, as in foxes. The black pigment is called eumelanin, while the reddish type is pheomelanin.

Scientists were able to map the chemical environments of two different types of melanin, a pigment responsible for black/dark brown or reddish/yellow color in feathers. This illustration shows an American kestrel feather (left), and the X-ray fluorescence maps of zinc (shown with a red filter), calcium (blue) and benzo-sulfur (yellow) in the same feather. The researchers will use the information provided by these maps to identify melanin in fossil specimens. 
Credit: SLAC National Accelerator Laboratory 

Pioneering research at The University’s Interdisciplinary Centre for Ancient Life has studied the feathers of modern birds in order to find long-lived chemical markers for these different pigments, so that traces may be reconstructed in fossil specimens.

In collaboration with the UK’s Diamond Light Source x-ray laboratories and Stanford University in the USA, the scientists analysed feathers shed by birds housed in animal sanctuaries. Their research has been able to show that the trace metal zinc, when it is bonded to sulfur compounds in a specific way, is a reliable and sensitive indicator for the presence of pheomelanin within the distinct feathers of birds of prey.

This remarkable discovery means that scientists may perhaps now be able to go beyond monochrome depictions of extinct creatures, and make the first steps towards portraying colors based upon chemical evidence.

“Melanin is a very important component in biology, but its exact chemistry is still not precisely known, especially as to how metals such as calcium, copper and zinc interact with it” said Nick Edwards, a Post Doctoral Research Associate at the University of Manchester and the lead author of the study. “Here we have used a new approach to probe these components of melanin and have found that there are subtle but measurable differences between the different types of melanin with regards to certain elements”.

”The avian descendants of dinosaurs have kept the chemical key to unlocking colour precisely locked in their feather chemistry” added Professor Phil Manning, co-author of the study.

The article ‘Elemental characterization of melanin in feathers via synchrotron X-ray imaging and absorption spectroscopy’ appears in September’s Scientific Reports journal.

“A fundamental rule in geology is that the present is the key to the past. This work on modern animals now provides another chemical ‘key’ for helping us to accurately reconstruct the appearance of long extinct animals." says Roy Wogelius, Professor of Geochemistry and senior author of the study

Contacts and sources:
Joe Paxton, University of Manchester

SLAC National Accelerator Laboratory 

Citation:  Elemental characterisation of melanin in feathers via synchrotron X-ray imaging and absorption spectroscopyN. Edwards et al., Scientific Reports, 23 September 2016 (doi:10.1038/srep34002)

New Finds Shift the Timeline Back for Human Arrival in The Americas

Ancient artifacts found at an archeological site in Argentina suggest that humans occupied South America earlier than previously thought.

Approximately 13,000 years ago, a prehistoric group of hunter-gathers known as the Clovis people lived in Northern America. Previous research suggests that the Clovis culture was one of the earliest cultures in the Americas. However, more recent research from the Pampas region of Argentina supports the hypothesis that early Homo sapiens arrived in the Americas earlier than the Clovis hunters did.

The evidence for earlier human arrival in the Americas comes from a rich archaeological site in southeastern South America called Arroyo Seco 2. A group of scientists led by Gustavo Politis from CONICET and the Universidad Nacional del Centro de la Provincia de Buenos Aires present the research in a new PLOS ONE study.

Credit: Politis et al (2016)

At Arroyo Seco 2, the researchers excavated ancient tools, bone remains from a variety of extinct species, and broken animal bones containing fractures caused by human tools. They used radiocarbon dating to determine the age of the mammal bones and analyzed the specimens under a microscope.

The analysis revealed the presence of limb bones from extinct mammals at the site, which may indicate human activities of transporting and depositing animal carcasses for consumption at a temporary camp. The bones of some mammal species were concentrated in a specific part of the site, which could indicate designated areas for butchering activities. Microscopic examination also revealed that some bones contained fractures most likely caused by stone tools. The remains were dated between 14,064 and 13,068 years ago, and the authors hypothesize that Arroyo Seco 2 may have been occupied by humans during that time.

This timeline, along with evidence from other South American sites, indicates that humans may have arrived in southern South America prior to the Clovis people inhabiting the Americas, but after the onset of the Last Glacial Maximum, the last glacial period, which took place 19,000 to 20,000 years ago.

While the characteristics of some of these archaeological materials could be explained without human intervention, the combination of evidence strongly suggests human involvement. Humans’ arrival in southern South America 14,000 years ago may represent the last step in the expansion of Homo sapiens throughout the world and the final continental colonization.

Contacts and sources:

Citation: Politis GG, Gutiérrez MA, Rafuse DJ, Blasi A (2016) The Arrival of Homo sapiens into the Southern Cone at 14,000 Years Ago. PLoS ONE 11(9): e0162870. doi:10.1371/journal.pone.0162870


New Research Could Help Build Better Hearing Aids

Scientists at Binghamton University, State University of New York want to improve sensor technology critical to billions of devices made every year. With a three-year grant from the National Science Foundation, they will start by making a high-performance sensor and applying it to hearing aids.
Image result for hearing aids memes
Credit: Wikimedia

“This [grant] allows us to explore a new sensing mechanism that can revolutionize capacitive sensing by addressing the severe limitation of limited range of motion. This could lead to devices with better sensitivity and functionality,” said principal investigator Sherry Towfighian, an assistant professor of mechanical engineering within the Thomas J. Watson School of Engineering and Applied Science at Binghamton University.

How a tiny fly’s ears could help you hear better

Distinguished Professor and Chair of the Mechanical Engineering Department Ron Miles is a co-principal investigator on the project.

Capacitive sensing uses differences in electrical storage capacity of two electrodes, one fixed and one movable, to detect physical quantities. The technology can measure position, humidity, fluid levels, acceleration or noise in devices like accelerometers, gyroscopes, touchscreens, proximity sensors and microphones. The miniature sensors and devices are Micro-Electro-Mechanical Systems, or “MEMS.”

All hearing aids contain a miniature microphone (often two), a signal processor/filter to compensate for hearing loss, a small amplifier and a receiver which sends amplified sound into the ear, much like an ear bud, according to Miles.

While digital signal processing technology has produced significant performance improvements in hearing aids over the past decade, the ability to understand speech in noisy environments is still hampered by limitations in microphone technology with regard to microphone self-noise and directionality.

“This research will lead to new ways to sense sound that will overcome many performance limitations,” Miles said. “While this project uses microphones as an application area for capacitive sensing research, the intent is to overcome design constraints that plague all capacitive sensing devices.”

“MEMS microphones have the potential of providing significant performance improvements in hearing aids,” Towfighian said in the grant description. “However, they have not yet demonstrated sufficient performance for this demanding application in general. If successful, this research will lead to more sensitive MEMS microphones for hearing aids and will have a tremendous impact on the lives of hearing impaired.”

Contacts and sources: 
Binghamton University
State University of New York

X-rays Illumnate New Path In Battle Against Mosquito-borne Illness

Structural biology research conducted at the U.S. Department of Energy’s SLAC National Accelerator Laboratory has uncovered how small insecticidal protein crystals that are naturally produced by bacteria might be tailored to combat dengue fever and the Zika virus. 

BinAB is a naturally occurring paracrystalline larvicide distributed worldwide to combat the devastating diseases borne by mosquitoes.

SLAC’s X-ray free-electron laser – the Linac Coherent Light Source (LCLS), a DOE Office of Science User Facility – offered unprecedented views of the toxin BinAB, used as a larvicide in public health efforts against mosquito-borne diseases such as malaria, West Nile virus and viral encephalitis.

The larvicide is currently ineffective against the Aedes mosquitos that transmit Zika and dengue fever, and therefore not used to combat these species of mosquitos at this time. The new information provides clues to how scientists could design a composite toxin that would work against a broader range of mosquito species, including Aedes.

The mosquito larvicide BinAB is composed of two proteins, BinA (yellow) and BinB (blue). Inside bacterial cells, BinAB naturally forms nanocrystals. Using these crystals and the intense X-ray pulses produced by SLAC’s Linac Coherent Light Source, scientists shed light on the three-dimensional structure of BinAB and its mode of action. 
Credit: SLAC National Accelerator Laboratory 

Today, Nature published the study.

“A more detailed look at the proteins’ structure provides information fundamental to understanding how the crystals kill mosquito larvae,” said Jacques-Philippe Colletier, a scientist at the Institut de Biologie Structurale in Grenoble, France and lead author on the paper. “This is a prerequisite for modifying the toxin to adapt it to our needs.”

Selective Mosquito Control, Courtesy of Bacteria

The BinAB crystals are produced by Lysinibacillus sphaericus bacteria, which release the crystals along with spores at the end of their life cycle. Mosquito larvae eat the crystals along with the spores, and then die.

BinAB is inactive in the crystalline state and does not work on contact. For the crystals to dissolve, they must be exposed to alkaline conditions, such as those in a mosquito larva’s gut. The binary protein is then activated, recognized by a specific receptor at the surface of cells and internalized.

Because Aedes larvae can evade one of these steps of intoxication, they are resistant to BinAB. These larvae do not express the correct receptors at the surface of their intestinal cells. Many other insect species, small crustaceans and humans also lack these receptors, as well as alkaline digestive systems.

“Part of the appeal is that the larvicide’s safe because it’s so specific, but that’s also part of its limitation,” said Michael Sawaya, a scientist at the University of California, Los Angeles-DOE Molecular Biology Institute and co-author on the paper.

For public health officials who want to prevent mosquito-borne disease, BinAB could also offer an alternative for controlling certain species of mosquitos that have begun to show resistance to other forms of chemical control.

Creating a Tailored Insecticide

The research team already knew the larvicide is composed of a pair of proteins, BinA and BinB, that pair together in crystals and are later activated by larval digestive enzymes.

In the LCLS experiments, they learned the molecular basis for how the two proteins paired with each other – each performing an important, unique function. Previous research had determined that BinA is the toxic part of the complex, while BinB is responsible for binding the toxin to the mosquito’s intestine. BinB ushers BinA into the cells; once inside, BinA kills the cell.

The scientists also identified four “hot spots” on the proteins that are activated by the alkaline conditions in the larval gut. All together, they trigger a change from a nontoxic form of the protein to a version that is lethal to mosquito larvae.

Using the information gathered during the crystallography study, the research team has already begun to engineer a form of the BinAB proteins that will work against more species of mosquitos. This is ongoing work at Institut de Biologie Structurale, UCLA, University of California, Riverside and SLAC.

Solving the Structure

Only coarse details were known about the unique three-dimensional structure and biological behavior of BinAB prior to the experiment at LCLS.

“We chose to look at the BinAB larvicide because it is so widely used, yet the structural details were a mystery,” said Brian Federici, professor of entomology at UC Riverside.

The small size of the crystals made them difficult to study at conventional X-ray sources. So the research team used genetic engineering techniques to increase the size of the crystals, and the bright, fast pulses of light at LCLS allowed the scientists to collect detailed structural data from the tiny crystals before X-rays damaged their samples.

The researchers used a crystallography technique called de novo phasing. This involves tagging the crystals with heavy metal markers, collecting tens of thousands of X-ray diffraction patterns, and combining the information collected to obtain a three-dimensional map of the electron density of the protein.

“This is the first time we’ve used de novo phasing on a crystal of great interest at an X-ray free-electron laser,” said Sebastien Boutet, SLAC scientist.

The technique had so far only been used on test samples where the structure was already known, in order to prove that it would work.

“The most immediate need is to now expand the spectrum of action of the BinAB toxin to counter the progression of Zika, in particular,” said Colletier. “BinAB is already effective against Culex [carrier of West Nile encephalitis] and Anopheles [carrier of malaria] mosquitos. With the results of the study, we now feel more confident that we can design the protein to target Aedes mosquitos.”

Additional contributors to the research include scientists from the Howard Hughes Medical Institutes at UCLA, Lawrence Berkeley National Laboratory, and Stanford University. The Institut de Biologie Structurale is a research center for integrated structural biology funded by the Commissariat à l’Énergie Atomique, the Centre National de la Recherche Scientifique and the Université Grenoble Alpes. The Collaborative Innovation Award program of Howard Hughes Medical Institute (HCIA-HHMI), W.M Keck Foundation, National Institutes of Health, National Science Foundation, France Alzheimer Foundation, Agence Nationale de la Recherche, and DOE Office of Science supported the research.

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the U.S. Department of Energy Office of Science. To learn more, please visit

SLAC National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit

Contacts and sources:
Andrew Gordon
U.S. Department of Energy SLAC National Accelerator Laboratory

Citation: De novo phasing with X-ray laser reveals mosquito larvicide BinAB structure
 Colletier, J-P et al., Nature, 28 September 2016 (10.1038/nature19825)

New Research Provides Strongest Evidence Oxygen Levels Were Key to Evolution of Early Animals

It has long puzzled scientists why, after 3 billion years of nothing more complex than algae, complex animals suddenly started to appear on Earth. Now, a team of researchers has put forward some of the strongest evidence yet to support the hypothesis that high levels of oxygen in the oceans were crucial for the emergence of skeletal animals 550 million years ago.

The new study is the first to distinguish between bodies of water with low and high levels of oxygen. It shows that poorly oxygenated waters did not support the complex life that evolved immediately prior to the Cambrian period, suggesting the presence of oxygen was a key factor in the appearance of these animals.

Cloudina fossils 
Cloudina fossils
Credit: Rachel Wood

The research, based on fieldwork carried out in the Nama Group in Namibia, is published in the journal Nature Communications.

Dr Rosalie Tostevin, a postdoctoral researcher in the Department of Earth Sciences at Oxford University and lead author of the study, said: 'The question of why it took so long for complex animal life to appear on Earth has puzzled scientists for a long time. One argument has been that evolution simply doesn’t happen very quickly, but another popular hypothesis suggests that a rise in the level of oxygen in the oceans gave simple life-forms the fuel they needed to evolve skeletons, mobility and other typical features of modern animals.

'Although there is geochemical evidence for a rise in oxygen in the oceans around the time of the appearance of more complex animals, it has been really difficult to prove a causal link. By teasing apart waters with high and low levels of oxygen, and demonstrating that early skeletal animals were restricted to well-oxygenated waters, we have provided strong evidence that the availability of oxygen was a key requirement for the development of these animals. However, these well-oxygenated environments may have been in short supply, limiting habitat space in the ocean for the earliest animals.'

The team, which also included geochemists, palaeoecologists and geologists from University College London and the universities of Edinburgh, Leeds and Cambridge, as well as the Geological Survey of Namibia, analysed the chemical elemental composition of rock samples from the ancient seafloor in the Nama Group – a group of extremely well-preserved rocks in Namibia that are abundant with fossils of early Cloudina, Namacalathus and Namapoikia animals.

Rosalie Tostevin in Namibia 
Rosalie Tostevin
Credit: Fred Bowyer

The researchers found that levels of elements such as cerium and iron detected in the rocks showed that low-oxygen conditions occurred between well-oxygenated surface waters and fully 'anoxic' deep waters. Although abundant in well-oxygenated environments, early skeletal animals did not occupy oxygen-impoverished regions of the shelf, demonstrating that oxygen availability (probably >10 micromolar) was a key requirement for the development of early animal-based ecosystems.

Dr Tostevin, who carried out the analyses for the study while completing her PhD at University College London, added: 'We looked at the last 10 million years of the Proterozoic Eon, when, although the Earth looked very different, some of the major animal groups we recognise today began to appear. Our results tell us that there is a link between the environment and the evolution that took place during this time, and that oxygen levels were key to this.'

Contacts and sources:

Stuart Gillespie
University of Oxford 

The paper 'Low-oxygen waters limited habitable space for early animals' is published in Nature Communications.

Where Does the Universe Grow? Does It Spin or Stretch?

The universe is expanding uniformly according to research led by University College London (UCL) which reports that space isn’t stretching in a preferred direction or spinning. 

The new study, published September 22 in Physical Review Letters, studied the cosmic microwave background (CMB) which is the remnant radiation from the Big Bang. It shows the universe expands the same way in all directions, supporting the assumptions made in cosmologists’ standard model of the universe.  Cosmology can be said to be safe as universe has no sense of direction

Credit: ESA/Hubble and NASA

First author, Daniela Saadeh (UCL Physics & Astronomy), said: “The finding is the best evidence yet that the universe is the same in all directions. Our current understanding of the universe is built on the assumption that it doesn’t prefer one direction over another, but there are actually a huge number of ways that Einstein’s theory of relativity would allow for space to be imbalanced. Universes that spin and stretch are entirely possible, so it’s important that we’ve shown ours is fair to all its directions.”

The team from UCL and Imperial College London used measurements of the CMB taken between 2009 and 2013 by the European Space Agency's Planck satellite. The spacecraft recently released information about the polarisation of CMB across the whole sky for the first time, providing a complementary view of the early universe that the team was able to exploit.

The researchers modeled a comprehensive variety of spinning and stretching scenarios and how these might manifest in the CMB, including its polarization. They then compared their findings with the real map of the cosmos from Planck, searching for specific signs in the data.

Daniela Saadeh, explained: “We calculated the different patterns that would be seen in the cosmic microwave background if space has different properties in different directions. Signs might include hot and cold spots from stretching along a particular axis, or even spiral distortions.”

Illustration of the possible patterns an anisotropic universe would leave in the cosmic microwave background, including (clockwise from bottom left) the contribution from quantum fluctuations, and from three different aspects of the anisotropic expansion

Credit: Saadeh et al.

Collaborating author Dr Stephen Feeney (Imperial College London) added: “We then compare these predictions to reality. This is a serious challenge, as we found an enormous number of ways the Universe can be anisotropic. It's extremely easy to become lost in this myriad of possible universes — we need to tune 32 dials to find the correct one.”

Previous studies only looked at how the universe might rotate, whereas this study is the first to test the widest possible range of geometries of space. Additionally, using the wealth of new data collected from Planck allowed the team to achieve vastly tighter bounds than the previous study. “You can never rule it out completely, but we now calculate the odds that the universe prefers one direction over another at just one in 121,000,” said Daniela Saadeh.

Most current cosmological studies assume that the Universe behaves identically in every direction. If this assumption were to fail, a large number of analyses of the cosmos and its content would be flawed.

Daniela Saadeh, added: “We’re very glad that our work vindicates what most cosmologists assume. For now, cosmology is safe.”

The work was kindly supported by the Perren Fund, IMPACT fund, Royal Astronomical Society, Science and Technology Facilities Council, Royal Society, European Research Council, and Engineering and Physical Sciences Research Council.

Contacts and sources:
Bex Caygill
University College London