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Tuesday, September 29, 2015

Flood Risk on Rise for New York City and New Jersey Coast, Study Finds

Flood risk for New York City and the New Jersey coast has increased significantly during the last 1,000 years due to hurricanes and accompanying storm surges, according to a study by Penn State University, Rutgers University, Massachusetts Institute of Technology, Princeton University and Tufts University.

For the first time, climate researchers compared both sea-level rise rates and storm surge heights in prehistoric and modern eras and found that the combined increases of each have raised the likelihood of a devastating 500-year flood occurring as often as every 25 years.

Flood heights increased 1.2 meters from the prehistoric era to the modern era, mainly due to rising sea level, researchers found.
Credit: PNAS

"A storm that occurred once in seven generations is now occurring twice in a generation," said Benjamin Horton, a Rutgers marine and coastal sciences professor. Horton also is the principal investigator on the National Oceanic and Atmospheric Administration and National Science Foundation grants funding the research.

The study, "Increased Threat of Tropical Cyclones and Coastal Flooding During the Anthropogenic Era," was published today in PNAS (Proceedings of the National Academy of Sciences). This study is unique because researchers combined sea-level records, hurricane and storm surge models to look at flooding in the New York City region in the two time periods - prehistoric (pre-anthropogenic, A.D. 850 to 1800) and modern (anthropogenic, 1970 - 2005).

Flooding heights increased 1.2 meters from the prehistoric era to the modern era, researchers found. "This is mainly due to the rising sea level. Sea levels have been rising in the modern era because of human activity," Horton said. "Sea-level rise between hurricanes raises the 'baseline' water level and makes flooding more likely."

Flood heights increased 1.2 meters from the prehistoric era to the modern era, mainly due to rising sea level, researchers found.

In the new study, researchers provided a continuous sea-level reconstruction since A.D 850. They showed that since the late 19th century sea level has risen at its steepest rate for more than 1,000 years. What does that mean for residents along the New York/New Jersey coast? "An extra 100,000 people flooded in the region during Hurricane Sandy who would not have flooded if sea level had not been rising," Horton said of the 2012 storm.

Climate researchers compared sea-level rise rates and storm surge heights in prehistoric and modern eras and found that the combined increases of each have dramatically increased the likelihood of major storms that cause excessive flooding. Above, Hurricane Sandy damage in Lavallette, N.J.

Credit: Glynis Jones/Shutterstock

Climate scientists have established that two types of storms cause the most damage - big, slow-moving storms and smaller but higher-intensity storms - and this study found that both have significantly increased in the modern era. "What we do know is that as sea level rise accelerates into the future, we are going to have more frequent flooding," Horton said.

To reconstruct sea level, the research team used microfossils called foraminifera preserved in sediment cores from coastal salt marshes in New Jersey. The age of these cores was estimated using radiocarbon dating and several other complementary techniques. "Every inch deeper in a core takes you further back in time," Horton explained. "We can stretch this technique back hundreds of years and thousands of years."

Researchers have established that the drivers of climate changes in the prehistoric era were natural causes, while in the later period human actions have driven increases in sea-level heights and other climate measures that affect storm activity.

The paper found that flood heights have increased during the modern era not only because of relative sea-level rise but also due to changing hurricane characteristics, leading to an increased risk of coastal inundation. "The increasing flood risk projected for the coming decades presents a hazard to New York City's and New Jersey's intense concentrations of population, economic production, and static infrastructure, and indicates the necessity for risk management solutions," Horton said.

As sea levels continue to rise at an accelerated pace, the risk of coastal flooding will rise as well. That's why the next phase of this research, led by doctoral candidate Andra Reed at Penn State University, will use the data gathered to make models to predict future sea levels and hurricane activity and when major storms like Hurricane Sandy will strike.

"We need to do this so we can provide better information to residents of New York and New Jersey and to policymakers, insurance industries and the states to prepare for how often an event as severe as Hurricane Sandy will occur," Horton said.

Contacts and sources: 
Ken Branson
Rutgers University

Researchers ID Pigment from Fossils, Revealing Color of Extinct Animals

Scientists from Virginia Tech and the University of Bristol have revealed how pigment can be detected in mammal fossils, a discovery that may end the guesswork in determining the colors of extinct species.

Scientists were able to determine the reddish brown color of a bat species known as Palaeochiropteryx from fossils found in Messel, Germany. The fossil is estimated to about 49 million years old.
Photo by Jakob Vinther/University of Bristol.

The researchers discovered the reddish brown color of two extinct species of bat from fossils dating back about 50 million years, marking the first time the colors of extinct mammals have been described through fossil analysis.

The techniques can be used to determine color from well-preserved animal fossils that are up to 300 million years old, researchers said.

"We have now studied the tissues from fish, frogs, and tadpoles, hair from mammals, feathers from birds, and ink from octopus and squids," said Caitlin Colleary, a doctoral student of geosciences in the College of Science at Virginia Tech and lead author of the study. "They all preserve melanin, so it's safe to say that melanin is really all over the place in the fossil record. Now we can confidently fill in some of the original color patterns of these ancient animals."

The research involved scientists from the U.S., the United Kingdom, Germany, Ethiopia, and Denmark. It is being published this week (Sept. 28) in the Proceedings of the National Academy of Sciences.

The researchers said microscopic structures traditionally believed to be fossilized bacteria are in fact melanosomes -- organelles within cells that contain melanin, the pigment that gives colors to hair, feathers, skin, and eyes.

Fossil melanosomes were first described in a fossil feather in 2008 by Jakob Vinther, a molecular paleobiologist at the University of Bristol and the senior author of the current study.

Since then, the shapes of melanosomes have been used to look at how marine reptiles are related and identify colors in dinosaurs and, now, mammals.

"Very importantly, we see that the different melanins are found in organelles of different shapes: reddish melanosomes are shaped like little meatballs, while black melanosomes are shaped like little sausages and we can see that this trend is also present in the fossils," Vinther said. "This means that this correlation of melanin color to shape is an ancient invention, which we can use to easily tell color from fossils by simply looking at the melanosomes shape."

Caitlin Colleary, a doctoral student of geosciences in the College of Science at Virginia Tech, says the original color patterns of ancient animals can be determined through fossils.
Credit: Virginia Tech

In addition to shape, melanosomes are chemically distinct.

Using an instrument called a time-of-flight secondary ion mass spectrometer, scientists identified the molecular makeup of the fossil melanosomes to compare with modern melanosomes.

In addition, researchers replicated the conditions under which the fossils formed to identify the chemical alteration of melanin, subjecting modern feathers to high temperatures and pressures to better understand how chemical signatures changed during millions of years of burial.

"By incorporating these experiments, we were able to see how melanin chemically changes over millions of years, establishing a really exciting new way of unlocking information previously inaccessible in fossils, Colleary said.

The work was carried out at the University of Bristol, where Colleary was a master's student working with Vinther, and the University of Texas at Austin. It was supported by funds from UT Austin, National Geographic, and the University of Bristol.

"It was important to bring microchemistry into the debate, because discussion has been going on for years over whether these structures were just fossilized bacteria or specific bodies where melanin is concentrated," said Roger Summons, the Schlumberger Professor of Earth Science at the Massachusetts Institute of Technology, who was not involved in the research. "These two things have very different chemical compositions."

Summons, who was part of a research team that studied fossils of squid to show that ink from the Jurassic period was chemically indistinguishable from modern cuttlefish ink, said the study further helps demonstrate how all living things on Earth have evolved in concert.

"How color is imparted and how we characterize it in fossils are important, because they inform us about a very specific aspect of the history of life on our planet," Summons said. "For complex animal life, color is a factor in how individuals recognize and respond to others, determine friend or foe, and find mates. This research provides another thread to understand how ancient life evolved. Color recognition was an important part of that process, and it goes far back in the history of animals."

Contacts and sources:
John Pastor
Virginia Tech

Microsnails Defy Current Understanding, World's Smallest Land Snail Crawls in Eye of a Needle

"Again I tell you, it is easier for a camel to go through the eye of a needle than for someone who is rich to enter the kingdom of God." Matthew 19:24.

For a newly discovered and nearly microscopic snail passing through the eye of a needle is no problem. 

Perhaps the world's smallest land snail species, Angustopila dominikae, in the eye of a sewing needle.

Credit: Dr. Barna Páll-Gergely and Nikolett Szpisjak.

Minuscule snails defy current knowledge and scientific terminology about terrestrial "microsnails". While examining soil samples collected from the base of limestone rocks in Guangxi Province, Southern China, scientists Barna Páll-Gergely and Takahiro Asami from Shinshu University, Adrienne Jochum, University and Natural History Museum of Bern, and András Hunyadi, found several minute empty light grey shells, which measured an astounding height of less than 1 mm.
New snail species, Angustopila dominikae, the only known specimen measuring the astounding 0.86 mm in shell height.
Credit:  Dr. Barna Páll-Gergely

The single known shell of Angustopila dominikae, named after the wife of the first author, was measured a mere 0.86 mm in shell height. Thus, it is considered to be perhaps the World's smallest land snail species when focusing on the largest diameter of the shell. With very few reported instances of species demonstrating this degree of tininess, the team have described a total of seven new land snail species in their paper, published in the open access journal ZooKeys.
Another of the herein described new species, called Angustopila subelevata, measured 0.83-0.91 mm (mean = 0.87 mm) in height.

Two of the authors have previously described other species of tiny land snails from China andKorea in the same journal.
New snail species, Angustopila subelevata, measuring from 0.83 to 0.91 mm in shell height of different specimens (average of 0.87 mm).

Credit: Dr. Barna Páll-Gergely

In their present paper, Dr. Pall-Gergely and his team also discuss the challenges faced by scientists surveying small molluscs, since finding living specimens is still very difficult. Thus, the evolutionary relationships between these species, as well as the number of existing species are yet little known.

"Extremes in body size of organisms not only attract attention from the public, but also incite interest regarding their adaptation to their environment," remind the researchers. "Investigating tiny-shelled land snails is important for assessing biodiversity and natural history as well as for establishing the foundation for studying the evolution of dwarfism in invertebrate animals."

"We hope that these results provide the taxonomic groundwork for future studies concerning the evolution of dwarfism in invertebrates," they finished up.

Contacts and sources:
Dr. Barna Páll-Gergely
Pensoft Publishers

Citation:  Páll-Gergely B, Hunyadi A, Jochum A, Asami T (2015) Seven new hypselostomatid species from China, including some of the world's smallest land snails (Gastropoda, Pulmonata, Orthurethra). ZooKeys 523: 31-62. doi: 10.3897/zookeys.523.6114

NASA Lays the Groundwork for Homesteading in Space with 3D Printing

When moving from one city to another, people rarely bring their house with them -- they just rent, buy or build a new one. Astronauts don't have the luxury of a realtor on other planets, or even a hardware store in space. They generally bring everything they might need on their journey, no matter how small, which increases cargo mass – and mission cost.

Rather than loading all their materials or waiting for a resupply mission, scientists and engineers at NASA's Marshall Space Flight Center in Huntsville, Alabama, are asking -- what if astronauts could simply use what they found when they arrived on a new destination like Mars? What if they could live off the land, make tools, equipment and even habitats with Martian dirt or a recyclable material?

Additive manufacturing, or 3-D printing, can help do just that. This developing field is rapidly changing the way space systems are designed and manufactured, reducing cost and production time.

An artist's rendition of what building a structure using on-site regolith and additive manufacturing might look like. This is a technology under development for use in deep space exploration.
Credit: NASA

In November 2014, crew members aboard the International Space Station began testing a 3-D printer that layers a heated plastic filament to create a variety of three-dimensional test designs, including a wrench. The Marshall Center is managing the on-orbit development of this technology and is now analyzing and testing the durability of the first items made in space by comparing them to similar items manufactured on Earth.

Marshall became involved in additive manufacturing when it was still an emerging technology, and purchased one of the first printers in 1990, primarily for rapid prototyping. Today, the Marshall team is using state-of-the-art 3-D printers that work with a variety of plastics and metals, including titanium, aluminum, nickel, and other alloys widely used in aerospace manufacturing.

The ability to print a replacement part or tool in orbit means NASA doesn’t have to send the parts, just the computer data file of the design, saving that mass for other important items that may be needed on a deep space mission. Proving this technology is also the next step toward manufacturing with resources found on planetary surfaces to build what humans need to survive there.

Engineers at Marshall are working on methods to bind or mold raw building materials out of regolith -- the soil or dirt found on planets, asteroids, or moons. The process would involve special mobile machines that work much like a 3-D printer, only they extrude materials made from mixing soil and a binder to “print" bricks, or even walls and other structures, to make houses for astronauts and equipment on another planet. These rovers could be controlled remotely from Earth or from space, so the shelters could be set up well in advance of a human setting foot on the surface.

An early prototype of such a machine is proving effective in building small structures on Earth out of sand. The next step is to make bricks and walls with simulated Mars regolith that has the same characteristics as real Martian dirt. With this technology under development, astronauts could arrive at new destinations and already have a home that is move-in ready.

Contacts and sources:
Tracy McMahan
Marshall Space Flight Center

NASA Confirms Liquid Water on Mars Now

New findings from NASA's Mars Reconnaissance Orbiter (MRO) provide the strongest evidence yet that liquid water flows intermittently on present-day Mars.

Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet. These darkish streaks appear to ebb and flow over time. They darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons. They appear in several locations on Mars when temperatures are above minus 10 degrees Fahrenheit (minus 23 Celsius), and disappear at colder times.

These dark, narrow, 100 meter-long streaks called recurring slope lineae flowing downhill on Mars are inferred to have been formed by contemporary flowing water. Recently, planetary scientists detected hydrated salts on these slopes at Hale crater, corroborating their original hypothesis that the streaks are indeed formed by liquid water. The blue color seen upslope of the dark streaks are thought not to be related to their formation, but instead are from the presence of the mineral pyroxene. The image is produced by draping an orthorectified (Infrared-Red-Blue/Green(IRB)) false color image (ESP_030570_1440) on a Digital Terrain Model (DTM) of the same site produced by High Resolution Imaging Science Experiment (University of Arizona). Vertical exaggeration is 1.5.

Credits: NASA/JPL/University of Arizona

“Our quest on Mars has been to ‘follow the water,’ in our search for life in the universe, and now we have convincing science that validates what we’ve long suspected,” said John Grunsfeld, astronaut and associate administrator of NASA’s Science Mission Directorate in Washington. “This is a significant development, as it appears to confirm that water -- albeit briny -- is flowing today on the surface of Mars.”

These downhill flows, known as recurring slope lineae (RSL), often have been described as possibly related to liquid water. The new findings of hydrated salts on the slopes point to what that relationship may be to these dark features. The hydrated salts would lower the freezing point of a liquid brine, just as salt on roads here on Earth causes ice and snow to melt more rapidly. Scientists say it’s likely a shallow subsurface flow, with enough water wicking to the surface to explain the darkening.

Dark narrow streaks called recurring slope lineae emanating out of the walls of Garni crater on Mars. The dark streaks here are up to few hundred meters in length. They are hypothesized to be formed by flow of briny liquid water on Mars. The image is produced by draping an orthorectified (RED) image (ESP_031059_1685) on a Digital Terrain Model (DTM) of the same site produced by High Resolution Imaging Science Experiment (University of Arizona). Vertical exaggeration is 1.5.
Dark narrow streaks, called "recurring slope lineae," emanate from the walls of Garni Crater on Mars
Credits: NASA/JPL/University of Arizona 

"We found the hydrated salts only when the seasonal features were widest, which suggests that either the dark streaks themselves or a process that forms them is the source of the hydration. In either case, the detection of hydrated salts on these slopes means that water plays a vital role in the formation of these streaks," said Lujendra Ojha of the Georgia Institute of Technology (Georgia Tech) in Atlanta, lead author of a report on these findings published Sept. 28 by Nature Geoscience.

Ojha first noticed these puzzling features as a University of Arizona undergraduate student in 2010, using images from the MRO's High Resolution Imaging Science Experiment (HiRISE). HiRISE observations now have documented RSL at dozens of sites on Mars. The new study pairs HiRISE observations with mineral mapping by MRO’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM).

This animation simulates a fly-around look at one of the places on Mars where dark streaks advance down slopes during warm seasons, possibly involving liquid water. This site is within Hale Crater. The streaks are roughly the length of a football field.

The spectrometer observations show signatures of hydrated salts at multiple RSL locations, but only when the dark features were relatively wide. When the researchers looked at the same locations and RSL weren't as extensive, they detected no hydrated salt.

Ojha and his co-authors interpret the spectral signatures as caused by hydrated minerals called perchlorates. The hydrated salts most consistent with the chemical signatures are likely a mixture of magnesium perchlorate, magnesium chlorate and sodium perchlorate. Some perchlorates have been shown to keep liquids from freezing even when conditions are as cold as minus 94 degrees Fahrenheit (minus 70 Celsius). On Earth, naturally produced perchlorates are concentrated in deserts, and some types of perchlorates can be used as rocket propellant.

Perchlorates have previously been seen on Mars. NASA's Phoenix lander and Curiosity rover both found them in the planet's soil, and some scientists believe that the Viking missions in the 1970s measured signatures of these salts. However, this study of RSL detected perchlorates, now in hydrated form, in different areas than those explored by the landers. This also is the first time perchlorates have been identified from orbit.

MRO has been examining Mars since 2006 with its six science instruments.

"The ability of MRO to observe for multiple Mars years with a payload able to see the fine detail of these features has enabled findings such as these: first identifying the puzzling seasonal streaks and now making a big step towards explaining what they are," said Rich Zurek, MRO project scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

For Ojha, the new findings are more proof that the mysterious lines he first saw darkening Martian slopes five years ago are, indeed, present-day water.

"When most people talk about water on Mars, they're usually talking about ancient water or frozen water," he said. "Now we know there’s more to the story. This is the first spectral detection that unambiguously supports our liquid water-formation hypotheses for RSL."

The discovery is the latest of many breakthroughs by NASA’s Mars missions.

“It took multiple spacecraft over several years to solve this mystery, and now we know there is liquid water on the surface of this cold, desert planet,” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program at the agency’s headquarters in Washington. “It seems that the more we study Mars, the more we learn how life could be supported and where there are resources to support life in the future.”

There are eight co-authors of the Nature Geoscience paper, including Mary Beth Wilhelm at NASA’s Ames Research Center in Moffett Field, California and Georgia Tech; CRISM Principal Investigator Scott Murchie of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland; and HiRISE Principal Investigator Alfred McEwen of the University of Arizona Lunar and Planetary Laboratory in Tucson, Arizona. Others are at Georgia Tech, the Southwest Research Institute in Boulder, Colorado, and Laboratoire de Planétologie et Géodynamique in Nantes, France.

The agency’s Jet Propulsion Laboratory (JPL) in Pasadena, California manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington. Lockheed Martin built the orbiter and collaborates with JPL to operate it.

Contacts and sources:
Guy Webster
Jet Propulsion Laboratory

Monday, September 28, 2015

2-Million-Year-Old Fossils Reveal Hearing Abilities of Early Humans

Research into human fossils dating back to approximately two million years ago reveals that the hearing pattern resembles chimpanzees, but with some slight differences in the direction of humans.

Rolf Quam, assistant professor of anthropology at Binghamton University, conducts research into human fossils dating back to approximately two million years ago to reveal how the hearing pattern resembles chimpanzees, but with some slight differences in the direction of humans. Quam led an international research team in reconstructing an aspect of sensory perception in several fossil hominin individuals from the sites of Sterkfontein and Swartkrans in South Africa.

Credit:  Casey Staff

Rolf Quam, assistant professor of anthropology at Binghamton University, led an international research team in reconstructing an aspect of sensory perception in several fossil hominin individuals from the sites of Sterkfontein and Swartkrans in South Africa. The study relied on the use of CT scans and virtual computer reconstructions to study the internal anatomy of the ear. The results suggest that the early hominin species Australopithecus africanus and Paranthropus robustus, both of which lived around 2 million years ago, had hearing abilities similar to a chimpanzee, but with some slight differences in the direction of humans.

This is a lateral view of the Paranthropus robustus skull SK 46 from the site of Swartkrans, South Africa showing the 3-D virtual reconstruction of the ear and the hearing results for the early hominins.

Credit: Rolf Quam

Humans are distinct from most other primates, including chimpanzees, in having better hearing across a wider range of frequencies, generally between 1.0-6.0 kHz. Within this same frequency range, which encompasses many of the sounds emitted during spoken language, chimpanzees and most other primates lose sensitivity compared to humans.

"We know that the hearing patterns, or audiograms, in chimpanzees and humans are distinct because their hearing abilities have been measured in the laboratory in living subjects," said Quam. "So we were interested in finding out when this human-like hearing pattern first emerged during our evolutionary history."

Previously, Quam and colleagues studied the hearing abilities in several fossil hominin individuals from the site of the Sima de los Huesos (Pit of the Bones) in northern Spain. These fossils are about 430,000 years old and are considered to represent ancestors of the later Neandertals. The hearing abilities in the Sima hominins were nearly identical to living humans. In contrast, the much earlier South African specimens had a hearing pattern that was much more similar to a chimpanzee.

These are hearing results for the early hominins. Points higher on the curve indicate greater auditory sensitivity. Note the sharp dropoff in sensitivity above about 3 kHz.
Credit: Rolf Quam

In the South African fossils, the region of maximum hearing sensitivity was shifted towards slightly higher frequencies compared with chimpanzees, and the early hominins showed better hearing than either chimpanzees or humans from about 1.0-3.0 kHz. It turns out that this auditory pattern may have been particularly favorable for living on the savanna. In more open environments, sound waves don't travel as far as in the rainforest canopy, so short range communication is favored on the savanna.

"We know these species regularly occupied the savanna since their diet included up to 50 percent of resources found in open environments" said Quam. The researchers argue that this combination of auditory features may have favored short-range communication in open environments.

That sounds a lot like language. Does this mean these early hominins had language? "No," said Quam. "We're not arguing that. They certainly could communicate vocally. All primates do, but we're not saying they had fully developed human language, which implies a symbolic content."

The emergence of language is one of the most hotly debated questions in paleoanthropology, the branch of anthropology that studies human origins, since the capacity for spoken language is often held to be a defining human feature. There is a general consensus among anthropologists that the small brain size and ape-like cranial anatomy and vocal tract in these early hominins indicates they likely did not have the capacity for language.

"We feel our research line does have considerable potential to provide new insights into when the human hearing pattern emerged and, by extension, when we developed language," said Quam.

Ignacio Martinez, a collaborator on the study, said, "We're pretty confident about our results and our interpretation. In particular, it's very gratifying when several independent lines of evidence converge on a consistent interpretation."

How do these results compare with the discovery of a new hominin species, Homo naledi, announced just two weeks ago from a different site in South Africa?

"It would be really interesting to study the hearing pattern in this new species," said Quam. "Stay tuned."

The study was published on Sept. 25 in the journal Science Advances.

Contacts and sources:
Rolf Quam
Binghamton University

Research Leads to New View of the Earth’s Core

There is more oxygen in the core of Earth than originally thought.

Lawrence Livermore geologist Rick Ryerson and international colleagues discovered some new findings about Earth’s core and mantle by considering their geophysical and geochemical signatures together.

This research provides insight into the origins of Earth’s formation.

Based on the higher oxygen concentration of the core, Ryerson’s team concludes that Earth must have accreted material that is more oxidized than the present-day mantle, similar to that of planetesimals such as asteroidal bodies. A planetesimal is an object formed from dust, rock and other materials and can be can be anywhere in size from several meters to hundreds of kilometers.

This model shows planetesimals (objects formed from dust, rock and other materials that can be anywhere in size from several meters to hundreds of kilometers) accreting to a growing Earth 4.56 billion years ago. The cutaway reveals the simultaneous formation of the Earth’s core as dense, iron-rich metallic material descending through a planetary magma ocean. 
Image courtesy of Antoine Pitrou/Institut de Physique du Globe de Parise Physique.

Earth formed about 4.56 billion years ago over a period of several tens of millions of years through the accretion of planetary embryos and planetesimals. The energy delivered by progressively larger impacts maintained Earth’s outer layer and an extensively molten magma ocean. Gravitational separation of metal and silicate within the magma ocean results in the planet characterized by a metallic core and a silicate mantle.

The formation of Earth’s core left behind geophysical and geochemical signatures in the core and mantle that remain to this day. In the past, core formation models have only attempted to address the evolution of core and mantle compositional signatures separately rather than looking for a joint solution.

By combining experimental petrology, geochemistry, mineral physics and seismology, the team found that core formation occurred in a hot (liquid) moderately deep magma ocean not exceeding 1,800-kilometer depth, under conditions more oxidized than present-day Earth.

“This new model is at odds with the current belief that core formation occurred under reduction conditions,” Ryerson said. “Instead we found that Earth’s magma ocean started out oxidized and has become reduced through time by oxygen incorporation into the core.”

They found the oxygen concentrations in the core are higher than previously thought and silicon concentrations are lower than previous estimates.

Other collaborators include Institut de Physique du Globe de Paris, École Polytechnique Fédérale de Lausanne and University College London.

The research appears in the online edition of the Sept. 21-25 edition of theProceedings of the National Academy of Sciences(link is external).

Contacts and sources:
Anne Stark

New Theory of Stealth Dark Matter May Explain Universe's Missing Mass

Lawrence Livermore scientists have come up with a new theory that may identify why dark matter has evaded direct detection in Earth-based experiments.

A group of national particle physicists known as the Lattice Strong Dynamics Collaboration, led by a Lawrence Livermore National Laboratory team, has combined theoretical and computational physics techniques and used the Laboratory's massively parallel 2-petaflop Vulcan supercomputer to devise a new model of dark matter. It identifies it as naturally "stealthy" (i.e. like its namesake aircraft, difficult to detect) today, but would have been easy to see via interactions with ordinary matter in the extremely high-temperature plasma conditions that pervaded the early universe.

This 3D map illustrates the large-scale distribution of dark matter, reconstructed from measurements of weak gravitational lensing by using the Hubble Space Telescope.
Credit: HST

"These interactions in the early universe are important because ordinary and dark matter abundances today are strikingly similar in size, suggesting this occurred because of a balancing act performed between the two before the universe cooled," said Pavlos Vranas of LLNL, and one of the authors of the paper, "Direct Detection of Stealth Dark Matter through Electromagnetic Polarizability". The paper appears in an upcoming edition of the journalPhysical Review Letters and is an "Editor's Choice."

Dark matter makes up 83 percent of all matter in the universe and does not interact directly with electromagnetic or strong and weak nuclear forces. Light does not bounce off of it, and ordinary matter goes through it with only the feeblest of interactions. Essentially invisible, it has been termed dark matter, yet its interactions with gravity produce striking effects on the movement of galaxies and galactic clusters, leaving little doubt of its existence.

The key to stealth dark matter's split personality is its compositeness and the miracle of confinement. Like quarks in a neutron, at high temperatures, these electrically charged constituents interact with nearly everything. But at lower temperatures they bind together to form an electrically neutral composite particle. Unlike a neutron, which is bound by the ordinary strong interaction of quantum chromodynamics (QCD), the stealthy neutron would have to be bound by a new and yet-unobserved strong interaction, a dark form of QCD.

Lawrence Livermore scientists have devised a new model of dark matter. It identifies it as naturally "stealthy" today, but would have been easy to see via interactions with ordinary matter in the extremely high-temperature plasma conditions that pervaded the early universe.
Credit: LLNL

"It is remarkable that a dark matter candidate just several hundred times heavier than the proton could be a composite of electrically charged constituents and yet have evaded direct detection so far," Vranas said.

Similar to protons, stealth dark matter is stable and does not decay over cosmic times. However, like QCD, it produces a large number of other nuclear particles that decay shortly after their creation. These particles can have net electric charge but would have decayed away a long time ago. In a particle collider with sufficiently high energy (such as the Large Hadron Collider in Switzerland), these particles can be produced again for the first time since the early universe. They could generate unique signatures in the particle detectors because they could be electrically charged.

"Underground direct detection experiments or experiments at the Large Hadron Collider may soon find evidence of (or rule out) this new stealth dark matter theory," Vranas said.
The LLNL lattice team authors are Evan Berkowitz, Michael Buchoff, Enrico Rinaldi, Christopher Schroeder and Pavlos Vranas, who is the lead of the team. The LLNL Laboratory Directed Research and Development and Grand Challenge computation programs supported this research. Other collaborators include researchers from Yale University, Boston University, Institute for Nuclear Theory, Argonne Leadership Computing Facility, University of California, Davis, University of Oregon, University of Colorado, Brookhaven National Laboratory and Syracuse University.

Contacts and sources:
Anne Stark

Discovery of Potential Gravitational Lenses Shows Citizen Science Value

Around 37,000 citizen scientists combed through 430,000 images to help an international team of researchers to discover 29 new gravitational lens candidates through Space Warps, an online classification system which guides citizen scientists to become lens hunters.

Gravitational lens systems are massive galaxies that act like special lenses through their gravity, bending the light coming from a distant galaxy in the background and distorting its image. Dark matter around these massive galaxies also contributes to this lensing effect, and so studying these gravitational lenses gives scientists a way to study this exotic matter that emits no light.

Twenty-nine gravitational lens candidates found through Space Warps.
Credit: Space Warps, Canada-France-Hawaii Telescope Legacy Survey

Since gravitational lenses are rare, only about 500 of them have been discovered to date, and the universe is enormous, it made sense for researchers to call on an extra pair of eyes to help scour through the mountain of images taken from the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). Details of the discoveries will be published in Monthly Notices of the Royal Astronomical Society.

"Computer algorithms have been somewhat successful in identifying gravitational lenses, but they can miss lensed images that appear similar to other features commonly found in galaxies, for example the blue spiral arms of a spiral galaxy," said Anupreeta More, co-principal investigator of Space Warps and project researcher at the University of Tokyo's Kavli Institute for the Physics and Mathematics of the Universe.

"All that was needed was the ability to recognise patterns of shapes and colours," said citizen scientist and paper co-author Christine Macmillan from Scotland. "It was fascinating to look at galaxies so far away, and realize that there is another behind it, even further away, whose light gets distorted in an arc."

Not only did this project give the public a chance to make scientific discoveries, it also gave them a chance to develop as researchers themselves. "I benefited from this project with an increase of my knowledge and some experience on making models of lenses," said citizen scientist and paper co-author Claude Cornen from France.

More, and two other collaborators, Phil Marshall at the Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, and Aprajita Verma at the Department of Physics, University of Oxford, are co-principal investigators of Space Warps, which taps into the unique strength of humans in analysing visual information essential for finding gravitational lenses.

The team will now move onto studying some of the interesting gravitational lens candidates by observing them with telescopes to uncover some of the mysteries related to dark matter. They are keen to work together with more volunteers in the near future as they are preparing new images from other ongoing imaging surveys to discover many more lenses.

Contacts and sources:
Motoko Kakubayashi
Kavli Institute for the Physics and Mathematics of the Universe

Perplexing Pluto: New ‘Snakeskin’ Image and More Photos from New Horizons

The newest high-resolution images of Pluto from NASA’s New Horizons are both dazzling and mystifying, revealing a multitude of previously unseen topographic and compositional details. The image below -- showing an area near the line that separates day from night -- captures a vast rippling landscape of strange, aligned linear ridges that has astonished New Horizons team members.

“It’s a unique and perplexing landscape stretching over hundreds of miles,” said William McKinnon, New Horizons Geology, Geophysics and Imaging (GGI) team deputy lead from Washington University in St. Louis. “It looks more like tree bark or dragon scales than geology. This’ll really take time to figure out; maybe it’s some combination of internal tectonic forces and ice sublimation driven by Pluto’s faint sunlight.”

The “snakeskin” image of Pluto’s surface is just one tantalizing piece of data New Horizons sent back in recent days. The spacecraft also captured the highest-resolution color view yet of Pluto, as well as detailed spectral maps and other high-resolution images.

In this extended color image of Pluto taken by NASA’s New Horizons spacecraft, rounded and bizarrely textured mountains, informally named the Tartarus Dorsa, rise up along Pluto’s day-night terminator and show intricate but puzzling patterns of blue-gray ridges and reddish material in between. This view, roughly 330 miles (530 kilometers) across, combines blue, red and infrared images taken by the Ralph/Multispectral Visual Imaging Camera (MVIC) on July 14, 2015, and resolves details and colors on scales as small as 0.8 miles (1.3 kilometers).


The new “extended color” view of Pluto – taken by New Horizons’ wide-angle Ralph/Multispectral Visual Imaging Camera (MVIC) on July 14 and downlinked to Earth on Sept. 19 – shows the extraordinarily rich color palette of Pluto.

“We used MVIC’s infrared channel to extend our spectral view of Pluto,” said John Spencer, a GGI deputy lead from Southwest Research Institute (SwRI) in Boulder, Colorado. “Pluto’s surface colors were enhanced in this view to reveal subtle details in a rainbow of pale blues, yellows, oranges, and deep reds. Many landforms have their own distinct colors, telling a wonderfully complex geological and climatological story that we have only just begun to decode.”

This cylindrical projection map of Pluto, in enhanced, extended color, is the most detailed color map of Pluto ever made. It uses recently returned color imagery from the New Horizons Ralph camera, which is draped onto a base map of images from the NASA’s spacecraft’s Long Range Reconnaissance Imager (LORRI). The map can be zoomed in to reveal exquisite detail with high scientific value. Color variations have been enhanced to bring out subtle differences. Colors used in this map are the blue, red, and near-infrared filter channels of the Ralph instrument.


Additionally, a high-resolution swath across Pluto taken by New Horizons’ narrow-angle Long Range Reconnaissance Imager (LORRI) on July 14, and downlinked on Sept. 20, homes in on details of Pluto’s geology. These images -- the highest-resolution yet available of Pluto -- reveal features that resemble dunes, the older shoreline of a shrinking glacial ice lake, and fractured, angular water ice mountains with sheer cliffs. Color details have been added using MVIC’s global map shown above.

High-resolution images of Pluto taken by NASA’s New Horizons spacecraft just before closest approach on July 14, 2015, reveal features as small as 270 yards (250 meters) across, from craters to faulted mountain blocks, to the textured surface of the vast basin informally called Sputnik Planum. Enhanced color has been added from the global color image. This image is about 330 miles (530 kilometers) across. For optimal viewing, zoom in on the image on a larger screen.


This closer look at the smooth, bright surface of the informally named Sputnik Planum shows that it is actually pockmarked by dense patterns of pits, low ridges and scalloped terrain. Dunes of bright volatile ice particles are a possible explanation, mission scientists say, but the ices of Sputnik may be especially susceptible to sublimation and formation of such corrugated ground.

High-resolution images of Pluto taken by NASA’s New Horizons spacecraft just before closest approach on July 14, 2015, are the sharpest images to date of Pluto’s varied terrain—revealing details down to scales of 270 meters. In this 75-mile (120-kilometer) section of the taken from the larger, high-resolution mosaic above, the textured surface of the plain surrounds two isolated ice mountains.


Beyond the new images, new compositional information comes from a just-obtained map of methane ice across part of Pluto's surface that reveals striking contrasts: Sputnik Planum has abundant methane, while the region informally named Cthulhu Regio shows none, aside from a few isolated ridges and crater rims. Mountains along the west flank of Sputnik lack methane as well.

The distribution of methane across the surface is anything but simple, with higher concentrations on bright plains and crater rims, but usually none in the centers of craters or darker regions. Outside of Sputnik Planum, methane ice appears to favor brighter areas, but scientists aren’t sure if that’s because methane is more likely to condense there or that its condensation brightens those regions.

“It's like the classic chicken-or-egg problem,” said Will Grundy, New Horizons surface composition team lead from Lowell Observatory in Flagstaff, Arizona. “We’re unsure why this is so, but the cool thing is that New Horizons has the ability to make exquisite compositional maps across the surface of Pluto, and that’ll be crucial to resolving how enigmatic Pluto works.”

“With these just-downlinked images and maps, we’ve turned a new page in the study of Pluto beginning to reveal the planet at high resolution in both color and composition,” added New Horizons Principal Investigator Alan Stern, of SwRI. “I wish Pluto’s discoverer Clyde Tombaugh had lived to see this day.”

The Ralph/LEISA infrared spectrometer on NASA’s New Horizons spacecraft mapped compositions across Pluto’s surface as it flew by on July 14. On the left, a map of methane ice abundance shows striking regional differences, with stronger methane absorption indicated by the brighter purple colors here, and lower abundances shown in black. Data have only been received so far for the left half of Pluto’s disk. At right, the methane map is merged with higher-resolution images from the spacecraft’s Long Range Reconnaissance Imager (LORRI).


Contacts and sources:
Tricia Talbert

Hubble Shears a "Woolly" Galaxy

This new image of the spiral galaxy NGC 3521 from the NASA/ESA Hubble Space Telescope is not out of focus. Instead, the galaxy itself has a soft, woolly appearance as it a member of a class of galaxies known as flocculent spirals.

Image credit: ESA/Hubble & NASA and S. Smartt (Queen's University Belfast); Acknowledgement: Robert Gendler

Like other flocculent galaxies, NGC 3521 lacks the clearly defined, arcing structure to its spiral arms that shows up in galaxies such as Messier 101, which are called grand design spirals. In flocculent spirals, fluffy patches of stars and dust show up here and there throughout their disks. Sometimes the tufts of stars are arranged in a generally spiraling form, as with NGC 3521, but illuminated star-filled regions can also appear as short or discontinuous spiral arms.

About 30 percent of galaxies share NGC 3521's patchiness, while approximately 10 percent have their star-forming regions wound into grand design spirals.

NGC 3521 is located almost 40 million light-years away in the constellation of Leo (The Lion). The British astronomer William Herschel discovered the object in 1784. Through backyard telescopes, NGC 3521 can have a glowing, rounded appearance, giving rise to its nickname, the Bubble Galaxy.

Contacts and sources:
Ashley Morrow
European Space Agency

Hubble Zeroes in on Shrapnel from an Exploded Star

NASA’s Hubble Space Telescope has unveiled in stunning detail a small section of the expanding remains of a massive star that exploded about 8,000 years ago.

Called the Veil Nebula, the debris is one of the best-known supernova remnants, deriving its name from its delicate, draped filamentary structures. The entire nebula is 110 light-years across, covering six full moons on the sky as seen from Earth, and resides about 2,100 light-years away in the constellation Cygnus, the Swan.

NASA's Hubble Space Telescope has unveiled in stunning detail a small section of the Veil Nebula - expanding remains of a massive star that exploded about 8,000 years ago.

Credits: NASA/ESA/Hubble Heritage Team

This view is a mosaic of six Hubble pictures of a small area roughly two light-years across, covering only a tiny fraction of the nebula’s vast structure.

This close-up look unveils wisps of gas, which are all that remain of what was once a star 20 times more massive than our sun. The fast-moving blast wave from the ancient explosion is plowing into a wall of cool, denser interstellar gas, emitting light. The nebula lies along the edge of a large bubble of low-density gas that was blown into space by the dying star prior to its self-detonation.

The image shows an incredible array of structures and detail from the collision between the blast wave and gas and dust that make up the cavity wall. The nebula resembles a crumpled bed sheet viewed from the side. The bright regions are where the shock wave is encountering relatively dense material or where the “bed sheet” ripples are viewed edge-on.

This 3-D visualization flies across a small portion of the Veil Nebula as photographed by the Hubble Space Telescope. This region is a small part of a huge expanding remnant from a star that exploded many thousands of years ago. Hubble resolves tangled rope-like filaments of glowing gases. The 3-D model has been created for illustrative purposes and shows that that the giant bubble of gas has a thin, rippled surface. It also highlights that the emission from different chemical elements arises from different layers of gas within the nebula. In the imagery, emission from hydrogen, sulfur, and oxygen are shown in red, green, and blue, respectively. 
Credits: NASA, ESA, and F. Summers, G. Bacon, Z. Levay, and L. Frattare (Viz 3D Team, STScI)

In this image, red corresponds to the glow of hydrogen; green from sulfur; and blue from oxygen. The bluish features, outlining the cavity wall, appear smooth and arched in comparison to the fluffy green and red structures. The red glow is from cooler gas that was excited by the shock collision at an earlier time and has subsequently diffused into a more chaotic structure.

A few thin, crisp-looking red filaments arise after gas is swept into the shock wave at speeds of nearly 1 million miles an hour, so fast that it could travel from Earth to the moon in 15 minutes.

Astronomers are comparing these new images to ones taken by Hubble in 1997. This comparison allows scientists to study how the nebula has expanded since it was photographed over 18 years ago.

The supernova that created the Veil Nebula would have been briefly visible to our very distant ancestors about 8,000 years ago as a bright “new star” in the northern sky.

This video opens with a backyard view of the nighttime sky centered on the constellation Cygnus, the Swan. We zoom into a vast donut-shaped feature called the Veil Nebula. It is the tattered expanding bubble of debris from a star that exploded about 8,000 years ago. The bubble has expanded to a diameter of roughly 110 light-years. Our zoom continues down to a two-light-year-wide segment of the nebula as photographed by the Hubble Space Telescope. Hubble resolves tangled rope-like filaments of glowing gases.

Credits: NASA, ESA, and G. Bacon (STScI)

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington.

 Contacts and sources:
 Ashley Morrow
 NASA, ESA, and the Hubble Heritage Team (AURA/STScI)

NASA Study Shows Oceanic Phytoplankton Declines in Northern Hemisphere

The world's oceans have seen significant declines in certain types of microscopic plant-life at the base of the marine food chain, according to a new NASA study. The research, published Sept. 23 in Global Biogeochemical Cycles, a journal of the American Geophysical Union, is the first to look at global, long-term phytoplankton community trends based on a model driven by NASA satellite data.

Phytoplankton blooms in the Barents Sea off the coast of Norway and Russia, shown in natural color from NASA's Aqua satellite on July 10, 2014. Without sampling the water directly it's impossible to know the type of phytoplankton, but past analyses suggest that the green bloom is diatoms and the white bloom is coccolithophores.

Credits: NASA's Earth Observatory

Diatoms, the largest type of phytoplankton algae, have declined more than 1 percent per year from 1998 to 2012 globally, with significant losses occurring in the North Pacific, North Indian and Equatorial Indian oceans. The reduction in population may reduce the amount of carbon dioxide drawn out of the atmosphere and transferred to the deep ocean for long-term storage.

"Phytoplankton need carbon dioxide for photosynthesis, just like trees," said oceanographer and lead author Cecile Rousseaux, of Universities Space Research Association and NASA's Goddard Space Flight Center in Greenbelt, Maryland. Carbon dioxide (CO2) from the atmosphere dissolves in cold ocean water. During a phytoplankton bloom, which can span hundreds of miles and be seen from space, the tiny organisms take up the dissolved CO2 and convert it to organic carbon - a form that animals can use as food to grow, the essential base of the marine food web. Then when the phytoplankton cell dies, it sinks to the ocean floor, taking with it the carbon in its body.

Because they are larger than other types of phytoplankton, diatoms can sink more quickly than smaller types when they die. A portion will circulate back to the surface because of ocean currents, and, like fertilizer, fuel another phytoplankton bloom. But the rest will settle on the sea floor miles below, where they will accumulate in sediment and be stored for thousands or millions of years. The process is one of the long-term storage options for carbon removed from the atmosphere.

This narrated video provides an overview of the study findings and features NASA scientist Cecile Rousseaux.

Credit:  NASA

 The decline in diatoms is one of several regional shifts observed in four types of phytoplankton in the 15-year study period.

Rousseaux and her colleagues took ocean color measurements of chlorophyll, the green pigment plants produce as part of photosynthesis, from NASA's Sea-viewing Wide Field of View Sensor (SeaWiFS) that flew aboard the Geo Eye OrbView-2 satellite from 1997 to 2010 and the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA's Aqua satellite from 2002 to the present. The data show the total chlorophyll in the ocean of all the phytoplankton types combined together. In previous work, they had observed that in the Northern Hemisphere, total chlorophyll was declining - but they didn't know what types of phytoplankton were declining or why.

That's where the computer model of the ocean comes in. Informed by other satellite data and field observations from ocean buoys and ships, NASA's Ocean Biogeochemical Model recreates the conditions in the ocean, from its currents to the amount of sunlight and nutrients available in different ocean basins. Since different types of phytoplankton use up nutrients at different rates and amounts, the model allowed the researchers to distinguish between large diatoms and smaller phytoplankton: coccolithophores, chlorophytes, and tiny cyanobacteria.

"Inclusion of satellite data into this kind of biogeochemical modeling is really exciting," said oceanographer Jeremy Werdell at Goddard, who was not involved in the study. The challenge with studying phytoplankton communities is that satellites cannot always unequivocally distinguish between different types of phytoplankton or the nutrients levels that may be affecting them. Sampling from ships and other direct measures can't observe the entirety of the global oceans on high spatial and time scales.

"This kind of tool allows you to start exploring that problem in a way we're not able to do by using just a satellite alone, or just a model alone," said Werdell. "By combining satellite data, models, and additional environmental information, you can start telling a more holistic story."

According to the model, the diatom declines are due to the uppermost layer of ocean water, called the mixed layer, becoming shallower. Taking into account seasonal variation, it shallowed by 1.8 meters (5.9 feet) over the 15-year study period.

The mixed layer is at the surface where waves and currents continually churn, drawing up nutrients from a deeper layer of water below. The upper section, or sometimes the whole mixed layer depending on how deep it is, receives sunlight. Together, these are the conditions that promote phytoplankton growth. But a shallower mixed layer has less volume, and thus can hold fewer nutrients, than a deeper mixed layer.

"The phytoplankton can run out of nutrients," said Rousseaux, which is what they observed in the nutrient levels essential to diatoms reported by the model. Why the mixed layer shallowed is still uncertain. One possibility is changes in winds, which cause some of the churning, she said.

The diatom decline, while statistically significant, is not severe, said Rousseaux. But it is something to monitor in the future as ocean conditions change, whether due to natural variation or climate change.

You can read the paper here or at Global Biogeochemical Cycles.

Contacts and sources:
Ellen Gray

Black Holes Merging and Creating Gravitational Waves

One hundred years since Einstein proposed gravitational waves as part of his general theory of relativity, an 11-year search performed with CSIRO's Parkes telescope has failed to detect them, casting doubt on our understanding of galaxies and black holes.

For scientists gravitational waves exert a powerful appeal, as it is believed they carry information allowing us to look back into the very beginnings of the Universe. Although there is strong circumstantial evidence for their existence, they have not yet been directly detected.

A simulation of black holes merging.

Credit: Michael Koppitz / aei

Using the high-precision Parkes telescope scientists spent 11 years looking for the existence of gravitational waves, but have detected nothing.

The work, led by Dr Ryan Shannon (of CSIRO and the International Centre for Radio Astronomy Research), is published today in the journal Science.

Using Parkes, the scientists expected to detect a background 'rumble' of the waves, coming from the merging galaxies throughout the Universe.

"But we heard nothing. Not even a whimper," Dr Shannon said.

"It seems to be all quiet on the cosmic front -- at least for the kind of waves we are looking for."

Galaxies grow by merging and every large one is thought to have a supermassive black hole at its heart. When two galaxies unite, the black holes are drawn together and form an orbiting pair. At this point, Einstein's theory is expected to take hold, with the pair predicted to succumb to a death spiral, sending ripples known as gravitational waves through space-time, the very fabric of the Universe.

Although Einstein's general theory of relativity has withstood every test thrown at it by scientists, gravitational waves remain its only unconfirmed prediction.

Black holes merging and creating gravitational waves. Scientists using CSIRO's Parkes telescope have been looking for the effect of these waves on small stars called pulsars.
Credit: John Rowe Animations / CSIRO

To look for the waves, Dr Shannon's team used the Parkes telescope to monitor a set of 'millisecond pulsars'. These small stars produce highly regular trains of radio pulses and act like clocks in space. The scientists recorded the arrival times of the pulsar signals to an accuracy of ten billionths of a second.

A gravitational wave passing between Earth and a millisecond pulsar squeezes and stretches space, changing the distance between them by about 10 metres -- a tiny fraction of the pulsar's distance from Earth. This changes, very slightly, the time that the pulsar's signals arrive on Earth.

The scientists studied their pulsars for 11 years, which should have been long enough to reveal gravitational waves.

So why weren't they found? There could be a few reasons, but the scientists suspect it's because black holes merge very fast, spending little time spiralling together and generating gravitational waves.

"There could be gas surrounding the black holes that creates friction and carries away their energy, letting them come to the clinch quite quickly," said team member Dr Paul Lasky, a postdoctoral research fellow at Monash University.

Whatever the explanation, it means that if astronomers want to detect gravitational waves by timing pulsars they'll have to record them for many more years.

"There might also be an advantage in going to a higher frequency," said Dr Lindley Lentati of the University of Cambridge, UK, a member of the research team who specialises in pulsar-timing techniques. Astronomers will also gain an advantage with the highly sensitive Square Kilometre Array telescope, set to start construction in 2018.

Not finding gravitational waves through pulsar timing has no implications for ground-based gravitational wave detectors such as Advanced LIGO (the Laser Interferometer Gravitational-Wave Observatory), which began its own observations of the Universe last week.

"Ground-based detectors are looking for higher-frequency gravitational waves generated by other sources, such as coalescing neutron stars," said Dr Vikram Ravi, a member of the research team from Swinburne University (now at Caltech, in Pasadena, California).

Contacts and sources:
Eamonn Bermingham
The International Centre for Radio Astronomy Research (ICRAR)

Thursday, September 24, 2015

Total Lunar Eclipse of Super Blood Moon On September 27

People across the western hemisphere may be surprised to see a rust-coloured Moon in the sky on 28 September. Early that morning (the evening of the 27 September for observers in North and South America) will be this year’s second total eclipse of the Moon. From the UK, this will be the first total lunar eclipse visible since 2008, and the last one visible in its entirety until 2019.

The total lunar eclipse of 4 April 2015. 
 Credit: Alfredo Garcia Jr. CC BY-SA 4.0.  

In a total lunar eclipse, the Earth, Sun and Moon are almost exactly in line and the Moon is on the opposite side of the Earth from the Sun. The Moon is full, moves into the shadow of the Earth and dims dramatically but usually remains visible, lit by sunlight that passes through the Earth’s atmosphere. Stronger atmospheric scattering of blue light means that the light that reaches the lunar surface is predominantly red in colour so observers on Earth see a Moon that may be brick-coloured, rusty, blood red or sometimes dark grey, depending on terrestrial conditions.

The Moon travels to a similar position every month, but the tilt of the lunar orbit means that it normally passes above or below the terrestrial shadow. So in most months the full Moon is seen but no eclipse takes place.

Lunar eclipses are visible wherever the Moon is above the horizon. The whole of this eclipse will be visible from west Africa, most of Western Europe including the British Isles, most of North America and the whole of South America. Depending on their location, sky watchers just outside these regions should be able to see at least part of the eclipse too.

In the UK night owls and early risers will both have a chance to watch the eclipse. It begins at 0110 BST when the Moon enters the lightest part of the Earth’s shadow, the penumbra. Soon after the Moon will have a slight yellowish hue. At 0207 BST the Moon starts to enter the dark core of the Earth’s shadow, the umbra. At 0311 BST the Moon will be completely within the umbra – the ‘total’ part of the eclipse has begun. This is the time when it should have an obvious red colour. Mid-eclipse is at 0347 BST and the total phase ends at 0424 BST. At 0527 BST the Moon leaves the umbra and the eclipse ends when the Moon leaves the penumbra at 0624 BST.

During the eclipse the Moon lies in front of the stars of the constellation of Pisces, in the UK appearing to be beneath and to the left of the square of Pegasus. As the eclipse progresses the Moon will move from roughly due south to southwest in the sky.

The Moon will also be very near its minimum distance from the Earth (perigee), so will be appear to be near its maximum apparent size. This means that in clear skies, the lunar eclipse promises to be a spectacular sight.

Unlike the solar equivalent, the whole event is also completely safe to watch and needs no special equipment, so can just be enjoyed as a free astronomical spectacle.

Contacts and sources:
Dr Robert Massey
Royal Astronomical Society

Dr Sheila Kanani
Royal Astronomical Society

Monstrous Black Hole Found: 350 Million Times Solar Masses

The central supermassive black hole of a recently discovered galaxy is far larger than should be possible, according to current theories of galactic evolution. New work, carried out by astronomers at Keele University and the University of Central Lancashire, shows that the black hole is much more massive than it should be, compared to the mass of the galaxy around it. The scientists publish their results in a paper in Monthly Notices of the Royal Astronomical Society.

An image of the galaxy SAGE0536AGN, from the Vista Magellanic Clouds survey. The galaxy is the elliptical object in the centre of the frame .The galaxy, SAGE0536AGN, was initially discovered with NASA's Spitzer space telescope in infrared light. Thought to be at least 9 billion years old, it contains an active galactic nucleus (AGN), an incredibly bright object resulting from the accretion of gas by a central supermassive black hole. The gas is accelerated to high velocities due to the black hole's immense gravitational field, causing this gas to emit light.
Credit:  RAS 

The team has now also confirmed the presence of the black hole by measuring the speed of the gas moving around it. Using the Southern African Large Telescope, the scientists observed that an emission line of hydrogen in the galaxy spectrum (where light is dispersed into its different colours – a similar effect is seen using a prism) is broadened through the Doppler Effect, where the wavelength (colour) of light from objects is blue- or red-shifted depending on whether they are moving towards or away from us. The degree of broadening implies that the gas is moving around at high speed, a result of the strong gravitational field of the black hole.

A still frame from a movie, illustrating an active galactic nucleus, with jets of material flowing from out from a central black hole.
 Credit: NASA / Dana Berry / SkyWorks Digital 
These data have been used to calculate the black hole's mass: the more massive the black hole, the broader the emission line. The black hole in SAGE0536AGN was found to be 350 million times the mass of the Sun. But the mass of the galaxy itself, obtained through measurements of the movement of its stars, has been calculated to be 25 billion solar masses. This is seventy times larger than that of the black hole, but the black hole is still thirty times larger than expected for this size of galaxy.

Credit; NASA

"Galaxies have a vast mass, and so do the black holes in their cores. This one though is really too big for its boots – it simply shouldn’t be possible for it to be so large", said Dr Jacco van Loon, an astrophysicist at Keele University and the lead author on the new paper.

In ordinary galaxies the black hole would grow at the same rate as the galaxy, but in SAGE0536AGN the black hole has grown much faster, or the galaxy stopped growing prematurely. Because this galaxy was found by accident, there may be more such objects waiting to be discovered. Time will tell whether SAGE0536AGN really is an oddball, or simply the first in a new class of galaxies.

Contacts and sources:
Dr Robert Massey
Royal Astronomical Society

Dr Jacco van Loon
Keele University

Citation:  "An evolutionary missing link? A modest-mass early-type galaxy hosting an oversized nuclear black hole", Jacco Th. van Loon and Anne E. Sansom, Monthly Notices of the Royal Astronomical Society, vol. 453 (3), pp. 2341-2348, Oxford University Press.

9,000 Year Old Case of Human Decapitation Discovered in Brazil

A 9,000 year-old case of human decapitation has been found in the rock shelter of Lapa do Santo in Brazil, according to a study published September 23, 2015 in the open-access journal PLOS ONE by André Strauss from the Max Planck Institute for Evolutionary Anthropology, Germany and colleagues.

This is a schematic representation of Burial 26 from Lapa do Santo.

Drawing by Gil Tokyo.

An archaeological site called Lapa do Santo, located in east-central Brazil, contains evidence of human occupation dating back to ~12,000 years ago. In 2007, researchers found fragments of a buried body, Burial 26, including a cranium, jaw, the first six cervical vertebrae, and two severed hands at the site. They dated the remains back to ~9,000 years ago using accelerator mass spectrometry. The researchers found amputated hands laid over the face of the skull arranged opposite each other and observed v-shaped cut marks on the jaw and sixth cervical vertebra.

Based on strontium analysis comparing Burial 26's isotopic signature to other specimens from Lapa do Santo, the researchers suggest Burial 26 was likely a local member of the group. Additionally, the presentation of the remains, lead the authors to think that this was likely a ritualized decapitation instead of trophy-taking. If this is the case, these remains may demonstrate sophisticated mortuary rituals among hunter-gatherers in the Americas during this time period. The authors think this may be the oldest case of decapitation found in the New Word, leading to a re-evaluation of the previous interpretations of this practice, particularly with regards to its origins and geographic dispersion.


Contacts and sources:
Kayla Graham

Citation: Strauss A, Oliveira RE, Bernardo DV, Salazar-García DC, Talamo S, Jaouen K, et al. (2015) The Oldest Case of Decapitation in the New World (Lapa do Santo, East-Central Brazil).PLOS ONE 10(9): e0137456.   http://dx.plos.org/10.1371/journal.pone.0137456

New Safe Cathode Developed for Low-Cost Sodium Batteries

Led by the inventor of the lithium-ion battery, a team of researchers in the Cockrell School of Engineering at The University of Texas at Austin has identified a new safe and sustainable cathode material for low-cost sodium-ion batteries.

During the past five years, sodium-ion batteries have emerged as a promising new type of rechargeable battery and an alternative to lithium-ion batteries because sodium, better known as the main element of salt, is abundant and inexpensive. In contrast, lithium-ion batteries are limited by high production costs and availability of lithium.

This illustration showcases the crystal structure of the eldfellite cathode for a sodium-ion battery. 
Credit: Cockrell School of Engineering

If researchers can figure out how to improve the performance and safety of sodium-ion batteries enough to widely commercialize them, then they could one day be used for wind and solar energy storage and to power electric vehicles.

To that end, professor John Goodenough, the inventor of the lithium-ion battery, and his team have identified a new cathode material made of the nontoxic and inexpensive mineral eldfellite, presenting a significant advancement in the race to develop a commercially viable sodium-ion battery. The researchers reported their findings Aug. 27 in the journal Energy & Environmental Science.

"At the core of this discovery is a basic structure for the material that we hope will encourage researchers to come up with better materials for the further development of sodium-ion batteries," said Preetam Singh, a postdoctoral fellow and researcher in Goodenough's lab.

Sodium-ion batteries work just like lithium-ion batteries. During the discharge, sodium ions travel from the anode to the cathode, while electrons pass to the cathode through an external circuit. The electrons can then be used to perform electrical work.

Although sodium-ion batteries hold tremendous potential, there are obstacles to advancing the technology including issues related to performance, weight and instability of materials. The team's proposed cathode material addresses instability. Its structure consists of fixed sodium and iron layers that allow for sodium to be inserted and removed while retaining the integrity of the structure.

One challenge the team is currently working through is that their cathode would result in a battery that is less energy dense than today's lithium-ion batteries. The UT Austin cathode achieved a specific capacity (the amount of charge it can accommodate per gram of material) that is only two-thirds of that of the lithium-ion battery.

"There are many more possibilities for this material, and we plan to continue our research. " Singh said. "We believe our cathode material provides a good baseline structure for the development of new materials that could eventually make the sodium-ion battery a commercial reality."

Contacts and sources:
Sandra Zaragoza
The University of Texas at Austin 

Reading Minds: Two Brains Linked in Question and Answer Experiment - Video

Imagine a question-and-answer game played by two people who are not in the same place and not talking to each other. Round after round, one player asks a series of questions and accurately guesses the object the other is thinking about.

Sci-fi? Mind-reading superpowers? Not quite.

University of Washington researchers recently used a direct brain-to-brain connection to enable pairs of participants to play a question-and-answer game by transmitting signals from one brain to the other over the Internet. The experiment, detailed today in PLOS ONE, is thought to be the first to show that two brains can be directly linked to allow one person to accurately guess what's on another person's mind.

University of Washington graduate student Jose Ceballos wears an electroencephalography (EEG) cap that records brain activity and sends a response to a second participant over the Internet
Credit:  University of Washington

"This is the most complex brain-to-brain experiment, I think, that's been done to date in humans," said lead author Andrea Stocco, an assistant professor of psychology and a researcher at UW's Institute for Learning & Brain Sciences.

"It uses conscious experiences through signals that are experienced visually, and it requires two people to collaborate," Stocco said.

Here's how it works: The first participant, or "respondent," wears a cap connected to an electroencephalography (EEG) machine that records electrical brain activity. The respondent is shown an object (for example, a dog) on a computer screen, and the second participant, or "inquirer," sees a list of possible objects and associated questions. With the click of a mouse, the inquirer sends a question and the respondent answers "yes" or "no" by focusing on one of two flashing LED lights attached to the monitor, which flash at different frequencies.

A "no" or "yes" answer both send a signal to the inquirer via the Internet and activate a magnetic coil positioned behind the inquirer's head. But only a "yes" answer generates a response intense enough to stimulate the visual cortex and cause the inquirer to see a flash of light known as a "phosphene." The phosphene -- which might look like a blob, waves or a thin line -- is created through a brief disruption in the visual field and tells the inquirer the answer is yes. Through answers to these simple yes or no questions, the inquirer identifies the correct item.

The experiment was carried out in dark rooms in two UW labs located almost a mile apart and involved five pairs of participants, who played 20 rounds of the question-and-answer game. Each game had eight objects and three questions that would solve the game if answered correctly. The sessions were a random mixture of 10 real games and 10 control games that were structured the same way.

The researchers took steps to ensure participants couldn't use clues other than direct brain communication to complete the game. Inquirers wore earplugs so they couldn't hear the different sounds produced by the varying stimulation intensities of the "yes" and "no" responses. Since noise travels through the skull bone, the researchers also changed the stimulation intensities slightly from game to game and randomly used three different intensities each for "yes" and "no" answers to further reduce the chance that sound could provide clues.

The researchers also repositioned the coil on the inquirer's head at the start of each game, but for the control games, added a plastic spacer undetectable to the participant that weakened the magnetic field enough to prevent the generation of phosphenes. Inquirers were not told whether they had correctly identified the items, and only the researcher on the respondent end knew whether each game was real or a control round.

"We took many steps to make sure that people were not cheating," Stocco said.

Participants were able to guess the correct object in 72 percent of the real games, compared with just 18 percent of the control rounds. Incorrect guesses in the real games could be caused by several factors, the most likely being uncertainty about whether a phosphene had appeared.

"They have to interpret something they're seeing with their brains," said co-author Chantel Prat, a faculty member at the Institute for Learning & Brain Sciences and a UW associate professor of psychology. "It's not something they've ever seen before."

University of Washington postdoctoral student Caitlin Hudac wears a cap that uses transcranial magnetic stimulation (TMG) to deliver brain signals from the other participant.
University of Washington postdoctoral student Caitlin Hudac wears a cap that uses transcranial magnetic stimulation (TMG) to deliver brain signals from the other participant.
Credit; University of Washington

Errors can also result from respondents not knowing the answers to questions or focusing on both answers, or by the brain signal transmission being interrupted by hardware problems.

"While the flashing lights are signals that we're putting into the brain, those parts of the brain are doing a million other things at any given time too," Prat said.

The study builds on the UW team's initial experiment in 2013, when it was the first to demonstrate a direct brain-to-brain connection between humans. Other scientists have connected the brains of rats and monkeys, and transmitted brain signals from a human to a rat, using electrodes inserted into animals' brains. In the 2013 experiment, the UW team used noninvasive technology to send a person's brain signals over the Internet to control the hand motions of another person.

The first experiment evolved out of research by co-author Rajesh Rao, a UW professor of computer science and engineering, on brain-computer interfaces that enable people to activate devices with their minds. In 2011, Rao began collaborating with Stocco and Prat to determine how to link two human brains together.

In 2014, the researchers received a $1 million grant from the W.M. Keck Foundation that allowed them to broaden their experiments to decode more complex interactions and brain processes. They are now exploring the possibility of "brain tutoring," transferring signals directly from healthy brains to ones that are developmentally impaired or impacted by external factors such as a stroke or accident, or simply to transfer knowledge from teacher to pupil.

The team is also working on transmitting brain states -- for example, sending signals from an alert person to a sleepy one, or from a focused student to one who has attention deficit hyperactivity disorder, or ADHD.

"Imagine having someone with ADHD and a neurotypical student," Prat said. "When the non-ADHD student is paying attention, the ADHD student's brain gets put into a state of greater attention automatically."

Many technological advancements over the past century, from the telegraph to the Internet, were created to facilitate communication between people. The UW team's work takes a different approach, using technology to strip away the need for such intermediaries.

"Evolution has spent a colossal amount of time to find ways for us and other animals to take information out of our brains and communicate it to other animals in the forms of behavior, speech and so on," Stocco said. "But it requires a translation. We can only communicate part of whatever our brain processes.

"What we are doing is kind of reversing the process a step at a time by opening up this box and taking signals from the brain and with minimal translation, putting them back in another person's brain," he said.

Contacts and sources: 
Deborah Bach
University of Washington