Apr 26, 2017

'Iceball' planet discovered through microlensing

This artist's concept shows OGLE-2016-BLG-1195Lb, a planet discovered through a technique called microlensing.
Scientists have discovered a new planet with the mass of Earth, orbiting its star at the same distance that we orbit our sun. The planet is likely far too cold to be habitable for life as we know it, however, because its star is so faint. But the discovery adds to scientists' understanding of the types of planetary systems that exist beyond our own.

"This 'iceball' planet is the lowest-mass planet ever found through microlensing," said Yossi Shvartzvald, a NASA postdoctoral fellow based at NASA's Jet Propulsion Laboratory, Pasadena, California, and lead author of a study published in the Astrophysical Journal Letters.

Microlensing is a technique that facilitates the discovery of distant objects by using background stars as flashlights. When a star crosses precisely in front of a bright star in the background, the gravity of the foreground star focuses the light of the background star, making it appear brighter. A planet orbiting the foreground object may cause an additional blip in the star's brightness. In this case, the blip only lasted a few hours. This technique has found the most distant known exoplanets from Earth, and can detect low-mass planets that are substantially farther from their stars than Earth is from our sun.

The newly discovered planet, called OGLE-2016-BLG-1195Lb, aids scientists in their quest to figure out the distribution of planets in our galaxy. An open question is whether there is a difference in the frequency of planets in the Milky Way's central bulge compared to its disk, the pancake-like region surrounding the bulge. OGLE-2016-BLG-1195Lb is located in the disk, as are two planets previously detected through microlensing by NASA's Spitzer Space Telescope.

"Although we only have a handful of planetary systems with well-determined distances that are this far outside our solar system, the lack of Spitzer detections in the bulge suggests that planets may be less common toward the center of our galaxy than in the disk," said Geoff Bryden, astronomer at JPL and co-author of the study.

For the new study, researchers were alerted to the initial microlensing event by the ground-based Optical Gravitational Lensing Experiment (OGLE) survey, managed by the University of Warsaw in Poland. Study authors used the Korea Microlensing Telescope Network (KMTNet), operated by the Korea Astronomy and Space Science Institute, and Spitzer, to track the event from Earth and space.

KMTNet consists of three wide-field telescopes: one in Chile, one in Australia, and one in South Africa. When scientists from the Spitzer team received the OGLE alert, they realized the potential for a planetary discovery. The microlensing event alert was only a couple of hours before Spitzer's targets for the week were to be finalized, but it made the cut.

With both KMTNet and Spitzer observing the event, scientists had two vantage points from which to study the objects involved, as though two eyes separated by a great distance were viewing it. Having data from these two perspectives allowed them to detect the planet with KMTNet and calculate the mass of the star and the planet using Spitzer data.

"We are able to know details about this planet because of the synergy between KMTNet and Spitzer," said Andrew Gould, professor emeritus of astronomy at Ohio State University, Columbus, and study co-author.

Although OGLE-2016-BLG-1195Lb is about the same mass as Earth, and the same distance from its host star as our planet is from our sun, the similarities may end there.

OGLE-2016-BLG-1195Lb is nearly 13,000 light-years away and orbits a star so small, scientists aren't sure if it's a star at all. It could be a brown dwarf, a star-like object whose core is not hot enough to generate energy through nuclear fusion. This particular star is only 7.8 percent the mass of our sun, right on the border between being a star and not.

Alternatively, it could be an ultra-cool dwarf star much like TRAPPIST-1, which Spitzer and ground-based telescopes recently revealed to host seven Earth-size planets. Those seven planets all huddle closely around TRAPPIST-1, even closer than Mercury orbits our sun, and they all have potential for liquid water. But OGLE-2016-BLG-1195Lb, at the sun-Earth distance from a very faint star, would be extremely cold -- likely even colder than Pluto is in our own solar system, such that any surface water would be frozen. A planet would need to orbit much closer to the tiny, faint star to receive enough light to maintain liquid water on its surface.

Ground-based telescopes available today are not able to find smaller planets than this one using the microlensing method. A highly sensitive space telescope would be needed to spot smaller bodies in microlensing events. NASA's upcoming Wide Field Infrared Survey Telescope (WFIRST), planned for launch in the mid-2020s, will have this capability.

"One of the problems with estimating how many planets like this are out there is that we have reached the lower limit of planet masses that we can currently detect with microlensing," Shvartzvald said. "WFIRST will be able to change that."

Read more at Science Daily

Early evidence of Middle Stone Age projectiles found in South Africa's Sibudu Cave

Analyzed serrated pieces.
Innovations in stone knapping technology during the South African Middle Stone Age enabled the creation of early projectile weapons, according to a study published April 26, 2017 in the open-access journal PLOS ONE by Veerle Rots from University of Liège, Belgium, and colleagues.

The South African Middle Stone Age (MSA) is considered a period of major technological advancement, with hunter-gatherers introducing new manipulative techniques using heat and pressure to create stone projectile weapons. However, the timing and location of these developments is a topic of much debate.

The authors of the present study examined 25 weapon point fragments excavated from the Sibudu Cave site, analyzing their technological and functional differences and comparing them with reference samples produced for the purpose by an experienced knapper. Some of the points had two faces, a likely result of applying pressure to both sides. Some had serrations, or jagged edges, that were likely produced by a technique known as pressure flaking.

The researchers found that 14 of the 25 point fragments bore evidence of impact-related damage, animal residues, and wear features that strongly indicated that these points may have been were used for hunting. Examination of the impact-related fractures and the distribution of the points indicated that these points may have been attached to handles to form projectile weapons and that these weapons were projected from a distance, most likely with a flexible spear-thrower or a bow.

While further research would help to confirm the timeline and development of stone knapping techniques, the new Sibudu Cave site data may push back the evidence for the use of pressure flaking during the MSA to 77,000 years ago. The authors note that these findings highlight the diversity of technical innovations adopted by southern African MSA humans.

From Science Daily

Paleontologists identify new 507-million-year-old sea creature with can opener-like pincers

This specimen of Tokummia katalepsis shows a number of strong legs on the left partially protruding from the body, the shape of the bivalved carapace and dozens of small paddle-like limbs below the trunk at the lower right. This nearly complete fossil was chosen as the main reference for the new genus Tokummia and new species katalep.
Paleontologists at the University of Toronto (U of T) and the Royal Ontario Museum (ROM) have uncovered a new fossil species that sheds light on the origin of mandibulates, the most abundant and diverse group of organisms on Earth, to which belong familiar animals such as flies, ants, crayfish and centipedes. The finding was announced in a study published today in Nature.

The creature, named Tokummia katalepsis by the researchers, is a new and exceptionally well-preserved fossilized arthropod -- a ubiquitous group of invertebrate animals with segmented limbs and hardened exoskeletons. Tokummia documents for the first time in detail the anatomy of early "mandibulates," a hyperdiverse sub-group of arthropods which possess a pair of specialized appendages known as mandibles, used to grasp, crush and cut their food. Mandibulates include millions of species and represent one of the greatest evolutionary and ecological success stories of life on Earth.

"In spite of their colossal diversity today, the origin of mandibulates had largely remained a mystery," said Cédric Aria, lead author of the study and recent graduate of the PhD program in the Department of Ecology & Evolutionary Biology at U of T, now working as a post-doctoral researcher at the Nanjing Institute for Geology and Palaeontology, in China. "Before now we've had only sparse hints at what the first arthropods with mandibles could have looked like, and no idea of what could have been the other key characteristics that triggered the unrivaled diversification of that group."

Tokummia lived in a tropical sea teeming with life and was among the largest Cambrian predators, exceeding 10 cm in length fully extended. An occasional swimmer, the researchers conclude its robust anterior legs made it a preferred bottom-dweller, as lobsters or mantis shrimps today. Specimens come from 507 million-year-old sedimentary rocks near Marble Canyon in Kootenay national park, British Columbia. Most specimens at the basis of this study were collected during extensive ROM-led fieldwork activities in 2014.

"This spectacular new predator, one of the largest and best preserved soft-bodied arthropods from Marble Canyon, joins the ranks of many unusual marine creatures that lived during the Cambrian Explosion, a period of rapid evolutionary change starting about half a billion years ago when most major animal groups first emerged in the fossil record," said co-author Jean-Bernard Caron, senior curator of invertebrate paleontology at the ROM and an associate professor in the Departments of Ecology & Evolutionary Biology and Earth Sciences at U of T.

Analysis of several fossil specimens, following careful mechanical preparation and photographic work at the ROM, showed that Tokummia sported broad serrated mandibles as well as large but specialized anterior claws, called maxillipeds, which are typical features of modern mandibulates.

"The pincers of Tokummia are large, yet also delicate and complex, reminding us of the shape of a can opener, with their couple of terminal teeth on one claw, and the other claw being curved towards them," said Aria. "But we think they might have been too fragile to be handling shelly animals, and might have been better adapted to the capture of sizable soft prey items, perhaps hiding away in mud. Once torn apart by the spiny limb bases under the trunk, the mandibles would have served as a revolutionary tool to cut the flesh into small, easily digestible pieces."

The body of Tokummia is made of more than 50 small segments covered by a broad two-piece shell-like structure called a bivalved carapace. Importantly, the animal bears subdivided limb bases with tiny projections called endites, which can be found in the larvae of certain crustaceans and are now thought to have been critical innovations for the evolution of the various legs of mandibulates, and even for the mandibles themselves.

The many-segmented body is otherwise reminiscent of myriapods, a group that includes centipedes, millipedes, and their relatives. "Tokummia also lacks the typical second antenna found in crustaceans, which illustrates a very surprising convergence with such terrestrial mandibulates," said Aria.

The study also resolves the affinities of other emblematic fossils from Canada's Burgess Shale more than a hundred years after their discovery. "Our study suggests that a number of other Burgess Shale fossils such as Branchiocaris, Canadaspis and Odaraia form with Tokummia a group of crustacean-like arthropods that we can now place at the base of all mandibulates," said Aria.

The animal was named after Tokumm Creek, which flows through Marble Canyon in northern Kootenay National Park, and the Greek for "seizing." The Marble Canyon fossil deposit was first discovered in 2012 during prospection work led by the Royal Ontario Museum and is part of the Burgess Shale fossil deposit, which extends to the north into Yoho National Park in the Canadian Rockies. All specimens are held in the collections of the Royal Ontario Museum on behalf of Parks Canada.

Read more at Science Daily

Earliest Evidence of Humans in the Americas Could ‘Change Everything’ If True

A mastodon skeleton on display in a diorama with a model of a Native American.
When archaeologist Steven Holen and his team recently completed an extensive analysis of mastodon fossils excavated in California, they were shocked by what they discovered.

“The findings went against nearly everything that we have been taught about early human history in North America,” Holen, co-director of the Center for American Paleolithic Research, told Seeker. “Shock and disbelief initially set in, because we knew that our conclusions would be so controversial.”

He was right. A very heated scientific debate is now raging over the team's study, published in the journal Nature. The paper holds that early humans modified the now-extinct large mammal’s bones around 130,000 years ago. That’s 128,508 years before Christopher Columbus began to explore the Central and South American coasts, and some 115,400 years before humans were thought to have entered North America.

The mastodon's remains were initially spotted in late 1992 during routine paleontological mitigation work at a freeway expansion project site managed by the California Department of Transportation. The location, off State Route 54 in San Diego, has since been named the Cerutti Mastodon site in honor of field paleontologist Richard Cerutti, who led the excavation.

Mastodon bones, tusks, and molars were found buried deeply alongside large stone tools, according to co-author Cerutti, Holen, and their colleagues.

“The tools include stone hammers and stone anvils to break bones to enable marrow extraction and/or to acquire raw material for bone and tooth tools,” explained co-author Richard Fullager, a researcher at the University of Wollongong’s Center for Archaeological Science.

Co-author Daniel Fisher, director of the University of Michigan’s Museum of Paleontology, added that the stone tool wielders “very strategically set up a process” to harvest the marrow from the mammoth’s long bones and to recover “dense fragments of bone” for tool production.

Mastodon remains and stones found at the Cerutti Mastodon site.
In 2014, research geologist and co-author James Paces of the US Geological Survey conducted rigorous uranium-series dating of the mastodon fossils and yielded an estimated burial age of approximately 130,000–130,700 years ago.

More recently, he and the rest of the research team — including senior author and archaeologist Kathleen Holen, Steven Holen’s wife — evaluated microscopic damage present on the mastodon fossils and stones. They compared those patterns with marks produced during experimental studies where they used stone cobbles for percussion of large elephant bones. (Modern elephants are distantly related to mastodons, which became extinct 10,000–11,000 years ago.)

The Holens and their international team of nine other scientists say that they ruled out natural or geological reasons for the mastodon bone breakages, stone shapes, and arrangement of the objects at the San Diego site. They even studied other areas where flood events left bone materials redistributed, and could find nothing like what was discovered at Cerutti Mastodon.

When Erella Hovers, head of the Institute of Archaeology at the Hebrew University of Jerusalem, learned about the new findings, her initial reaction mirrored that of Steven Holen.

She told Seeker that she felt “surprised” and that there was “some brow raising.” Nevertheless, she said, she believes that “the conclusions are well supported.”

“The Eurasian archaeological record of the period shows a lot of movement of various hominins [early humans] across continents,” Hovers continued. “It is not too inconceivable that the Americas were also reached, even if not fully colonized, at that time.”

If true, the scenario begs the question: What species of human was in what is now San Diego around 130,000 years ago?

Possible candidates include Homo erectus (aka Upright Man), Neanderthals, Denisovans, and anatomically modern humans from that time.

Recreation of a Neanderthal.
“Anatomically modern humans have not been found so early in northeastern Asia, but it is not totally impossible that they were around and even made it to North America, if the earliest dates for modern humans further south in China prove to be right,” Fullager said. “It seems unlikely — but again, not impossible — that any human species other than ‘cognitively modern humans’ could make the journey by boat.”

“Neanderthals, Denisovans, or some mix of these genetic populations were in southern Siberia, and feasibly in northeastern Siberia, at this time,” he added. “They could have made the journey by land to North America at the right window of opportunity — after temperatures had risen, ice had melted and the sea levels had not yet drowned Beringia [the Bering Land Bridge].”

Regarding the possibility that early humans arrived in the Americas via watercraft, Holen pointed out that there is evidence for early human travels over water. Mariners are thought to have arrived on the island of Crete 130,000 years ago, and human activity on the island of Sulawesi is believed to have occurred 118,000 years ago. It is therefore possible, he said, that early humans “crossed larger bodies of water like the Bering Strait as well.”

Mastodon remains at the Cerutti Mastodon site.
Numerous scientists question these theories and Holen and his team's conclusions concerning the mastodon remains.

“The presence of a Homo population in North America 130,000 years ago is a huge claim, and I can only remain extremely skeptical for the moment,” Bastien Llamas of the Australian Center for Ancient DNA (ACAD) told Seeker.

Alan Cooper conducted a genetic study with Llamas of the early peopling of the Americas and is the director of ACAD.

“Extraordinary claims such as this require extraordinary evidence,” he said, noting that he does not see such evidence in the new paper.

Anthropologist David Meltzer of Southern Methodist University, a leading expert on the colonization of North America, echoed Cooper’s concerns.

“If you are going to push human antiquity in the New World back more than 100,000 years in one fell swoop, you’ll have to do so with a far better archaeological case than this one,” Meltzer said. “Extraordinary claims require extraordinary proof. We have none of the detailed taphonomic [fossil] evidence necessary to support such a grandiose and extraordinary claim.”

Read more at Discovery News

Cassini Begins Its Grand Finale With a Dive Between Saturn’s Rings

This artist's rendering shows NASA's Cassini spacecraft above Saturn's northern hemisphere, heading toward its first dive between Saturn and its rings on April 26, 2017.
Running low on fuel, NASA's Cassini spacecraft has begun the final — and most daring — phase of its epic mission to Saturn.

After using a final flyby of the moon Titan on Friday to boost its speed, Cassini was flung by the moon's gravity to a trajectory that sent it diving through the 1,200-mile (1,930 kilometers) gap between the planet's upper atmosphere and innermost rings, NASA officials said.

Cassini completed the first crossing of the ring plane at about 2 a.m. PDT (5 a.m. EDT, or 0900 GMT) Wednesday, the space agency said in a statement.

This final journey will end Sept. 15 when the spacecraft burns up in Saturn's crushing atmosphere. There is no turning back now; Cassini is on a "ballistic trajectory," and its fate is sealed, NASA scientists have said. The Grand Finale has been designed to prevent the spacecraft from contaminating the potentially habitable Saturnian moons.

"We're guaranteed to end up in Saturn's atmosphere in September," said Scott Edgington, Cassini deputy project scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. "If we get hit by a particle [during the first dive] that disables the spacecraft, we are still guaranteed to end up in Saturn," he told Space.com.

Cassini is expected to be out of contact for about a day after this first dive while it takes detailed observations of Saturn and the ring gap, NASA officials said in a statement. The earliest the spacecraft is expected to check in is 12:05 a.m. PDT (3:05 a.m. EDT, or 0705 GMT) on Thursday (April 27), and it should return data and images soon after.

Saturn mysteries remain

Assuming a successful first dive, Cassini will loop around Saturn's southern hemisphere on a wide orbit, setting itself up for another 21 weekly dives that will take it to within 1,840 miles (2,960 km) of the planet's atmosphere, where it will continue its unprecedented investigations into Saturn's mysteries. NASA tracks the spacecraft's path in its Grand Finale Orbit Guide.

Cassini launched in October 1997 through a collaboration among NASA, the European Space Agency and the Italian Space Agency, and it has been in orbit around the ringed gas giant since 2004. In that time, it has gathered numerous observations of the planet, its rings and its moons. Long-duration missions such as Cassini are essential for studying the massive planet; indeed, 13 years is a very short time to explore a world with a 29-year orbit around the sun, mission scientists said.

"We've only been at Saturn for what is, effectively, half a Saturn year," Edgington said. "But [in that time], we're seeing all these detailed changes going on within that system."

Over the course of Cassini's stay at the gas giant, ferocious storms have come and gone in Saturn's turbulent atmosphere. Planetary scientists have also been able to study the dynamics of the moon Titan's thick atmosphere, even forecasting weather systems as its seasons slowly change, Edgington noted.

But many questions remain, and hopes are high that Cassini's Grand Finale will yield some of the biggest discoveries yet to come in the 20 years since the mission's launch, Cassini researchers have said.

"The Grand Finale is a brand-new mission," Linda Spilker, Cassini project scientist at JPL, said during a news conference on April 4. "We're going to a place that we've never been before … and I think some of the biggest discoveries may come from these final orbits."

For instance, the length of a day on Saturn is still unknown, Edgington noted. The planet's axis of rotation and axis of its magnetic field are parallel, which makes it very difficult to measure how long it takes for the planet's core to complete one rotation. By making very close passes to Saturn, however, Cassini's Grand Finale will be able to measure the small-scale fluctuations in magnetism to not only pin down how long a Saturnian day is but also reveal its internal structure, he said.

"We're also going to be measuring the tiny particles that will be inside that gap [between Saturn and its rings]," Edgington said. "These are particles that come from the rings. They're charged particles; they become trapped along the magnetic-field lines that intersect the rings. And we'll be able to measure them as they travel along the magnetic field. We're talking tiny ice grains, or maybe even products of water being broken up by sunlight in that region."

These intimate studies of Saturn's rings could reveal how much material they contain and how old they are, Edgington said. Using this information, scientists could test planetary formation models that may ultimately reveal how planets evolve and how their moons accrete material, he added.

Protecting Enceladus and Titan


For Cassini's Grand Finale, scientists took significant measures to ensure Saturn's moons would not be contaminated with microbes from Earth, Edgington said.

"NASA has certain rules to follow about not contaminating any place that we think might be habitable," he said.

Although engineers put great effort into sterilizing the spacecraft before they launched, researchers have found that a few hardy bacteria can survive for long periods in extreme environments, and some of these Earth microbes may be lurking inside Cassini's components. NASA decided to incinerate Cassini at the mission's end to reduce the risk that these tough microbes would contaminate the Saturn moons Enceladus or Titan, which scientists regard as two of the best places in the solar system to search for life.

In 2005, Europe's Huygens probe landed on Titan's surface and, at the time, met all planetary protection requirements. Since Cassini has been studying Titan over the years after Huygen's landing, however, the atmospheric moon's habitable potential has become clear. The potential habitability and planetary protection standards for Enceladus are higher than for Titan, but making sure Cassini avoids both moons is a bonus, said Cassini mission scientists.

Enceladus is a small, icy moon that could easily fit inside the state of New Mexico, but its implication in the search for life elsewhere in the solar system is huge. Thanks to Cassini, we now know that Enceladus has a subsurface ocean of liquid water that erupts through the moon's ice as plumes. The spacecraft has been able to "taste" the particles being released to space, revealing that the moon contains organic molecules (carbon-containing compounds).

Read more at Discovery News

Apr 25, 2017

Lull in Mars' giant impact history

Mars bears the scars of five giant impacts, including the ancient giant Borealis basin (top of globe), Hellas (bottom right), and Argyre (bottom left). An SwRI-led team discovered that Mars experienced a 400-million-year lull in impacts between the formation of Borealis and the younger basins.
From the earliest days of our solar system's history, collisions between astronomical objects have shaped the planets and changed the course of their evolution. Studying the early bombardment history of Mars, scientists at Southwest Research Institute (SwRI) and the University of Arizona have discovered a 400-million-year lull in large impacts early in Martian history.

This discovery is published in the latest issue of Nature Geoscience in a paper titled, "A post-accretionary lull in large impacts on early Mars." SwRI's Dr. Bill Bottke, who serves as principal investigator of the Institute for the Science of Exploration Targets (ISET) within NASA's Solar System Exploration Research Virtual Institute (SSERVI), is the lead author of the paper. Dr. Jeff Andrews-Hanna, from the Lunar and Planetary Laboratory in the University of Arizona, is the paper's coauthor.

"The new results reveal that Mars' impact history closely parallels the bombardment histories we've inferred for the Moon, the asteroid belt, and the planet Mercury," Bottke said. "We refer to the period for the later impacts as the 'Late Heavy Bombardment.' The new results add credence to this somewhat controversial theory. However, the lull itself is an important period in the evolution of Mars and other planets. We like to refer to this lull as the 'doldrums.'"

The early impact bombardment of Mars has been linked to the bombardment history of the inner solar system as a whole. Borealis, the largest and most ancient basin on Mars, is nearly 6,000 miles wide and covers most of the planet's northern hemisphere. New analysis found that the rim of Borealis was excavated by only one later impact crater, known as Isidis. This sets strong statistical limits on the number of large basins that could have formed on Mars after Borealis. Moreover, the preservation states of the four youngest large basins -- Hellas, Isidis, Argyre, and the now-buried Utopia -- are strikingly similar to that of the larger, older Borealis basin. The similar preservation states of Borealis and these younger craters indicate that any basins formed in-between should be similarly preserved. No other impact basins pass this test.

"Previous studies estimated the ages of Hellas, Isidis, and Argyre to be 3.8 to 4.1 billion years old," Bottke said. "We argue the age of Borealis can be deduced from impact fragments from Mars that ultimately arrived on Earth. These Martian meteorites reveal Borealis to be nearly 4.5 billion years old -- almost as old as the planet itself."

Read more at Science Daily

This Artificial Womb Could Reduce Mortality and Disability in Premature Babies

Pediatric researchers in Philadelphia have created a liquid-filled chamber that could simulate conditions in the womb for premature babies, allowing their organs to mature in the critical weeks following their birth. The preliminary findings could reduce mortality and disability in some of the estimated 30,000 babies born critically preterm each year.

“These infants have an urgent need for a bridge between the mother’s womb and the outside world,” Alan Flake, director of the Center for Fetal Research and leader of the study, said in a statement. “If we can develop an extra-uterine system to support growth and organ maturation for only a few weeks, we can dramatically improve outcomes for extremely premature babies.”

Flake and his colleagues at the Children’s Hospital of Philadelphia tested their device on fetal lambs, which demonstrate a lung development process very similar to that occurring in humans. Throughout their stay in the artificial uterus, the lambs showed normal breathing, growth, neurological function, and organ maturation. They grew wool, opened their eyes, and became more active.

When the lambs were removed from the fluid-filled chambers, they were put on ventilators. Researchers reported that their lungs functioned very closely to those of a normal lamb.

"What we have evidenced is that at the time of delivery, their lung function has essentially caught up to that of a mature infan​t," Emily Partridge, a research fellow working with premature infants at the hospital, said in a news briefing on Monday. "​We would expect that this would translate into a vast improvement in the clinical outcomes of these patients.​"​

The new system, described in a report released today by Nature Communications, attempts to mimic fetal life in the uterus as closely as possible. It differs from previous models in three ways: circulation is powered by heartbeat, oxygen and nutrient exchange take place through the umbilical cord and, in major contrast to an incubator, breathing continues to take place in a fluid environment, by way of amniotic fluid created in the lab.

“Fetal lungs are designed to function in fluid, and we simulate that environment here, allowing the lungs and other organs to develop, while supplying nutrients and growth factors,” Marcus Davey, a member of the research team, said in a statement.

By maintaining the amniotic fluid, the system eliminates the need for a ventilator, which Flake says can arrest the development of lungs while pumping in atmospheric oxygen that underdeveloped lungs may not be prepared to breathe. This air could also contain pathogens. Instead, in the new system, the infant remains connected, via their umbilical cord, to an external, low-resistance machine that would substitute for the mother’s placenta, exchanging oxygen and carbon dioxide in the blood while providing nutrients.

In addition, all circulation inside the near-sterile space would be driven by the fetal heartbeat, reducing pressure that could overload an underdeveloped heart.

While previous research has explored the use of an artificial placenta in animal models, systems without a pump have extended the extra-uterine period by a mere 60 hours. In these studies, the animals sustained brain damage. The system developed by Flake and colleagues, in contrast, showed no adverse effects and kept some of the lambs’ health for 670 hours — the equivalent of 28 days.

In the United States, any birth that takes place prior to 37 weeks of gestation is considered to be premature. Of these, one in 10 tends to be “critically preterm,” or less than 26-weeks-old. These are the cases of greatest concern, as extreme prematurity is the leading cause of infant mortality and morbidity in the country. Currently, one-third of all infant deaths and one-half of all cases of cerebral palsy are attributed to prematurity.

Read more at Discovery News

Distant Dwarf Planet DeeDee Stirs Up the Pluto Planethood Debate

Artist concept of the planetary body 2014 UZ224, more informally known as DeeDee. ALMA was able to observe the faint millimeter-wavelength "glow" emitted by the object, confirming it is roughly 635 kilometers across. At this size, DeeDee should have enough mass to be spherical, the criterion necessary for astronomers to consider it a dwarf planet, though it has yet to receive that official designation.
What's a planet? What's a dwarf planet? Should we make a distinction? Should we really care about these definitions in the first place?

As we learn more about the outer solar system, the boundaries begin to blur.

A tiny celestial body called 2014 UZ224 and informally known as DeeDee (for “distant dwarf”) is a distant world about 92 astronomical units, or Earth-sun distances, from our sun. Recent observations from the Atacama Large Millimeter/submillimeter Array (ALMA) revealed that DeeDee is roughly 395 miles (635 kilometers) across, which would give it enough mass to be spherical.

Why does it matter if DeeDee is round? In 2006, a controversial vote by the International Astronomical Union defined three parameters for a planet. Simply speaking, the IAU says a planet must be in orbit around the sun, have enough mass to be round, and have cleared the neighborhood around its orbit — meaning it needs to be gravitationally dominant and hold any nearby bodies within its orbit.

Size comparisons of objects in our solar system, including the recently discovered planetary body "DeeDee."
It's the last part of the definition that most aggravates those who argue that Pluto – redefined as a "dwarf" planet under the IAU – is more planet than not. The argument is that the rocky planets of Earth, Mars, Venus, and Mercury have also not cleared their neighborhoods, as many asteroids co-orbit along with them.

The planetary geologist Kirby Runyon, a Ph.D. student at the Johns Hopkins University Applied Physics Laboratory, wrote a paper this year proposing a geophysical-based definition of a planet that would dispense with the orbital criterion and basically include any round celestial body that isn’t a star. The idea hatched by Runyon and his co-authors — which include Alan Stern, the principal investigator of the New Horizons mission to Pluto — would increase the number of purported planets in our solar system to over 110, including Earth’s moon and DeeDee.

"What it's really showing is the diversity of planets in our solar system,” said Runyon of the DeeDee news, “and giving us a better understanding of planets in the rest of the galaxy.”

"DeeDee is almost certainly made out of ices — water ices, methane, and carbon dioxide — which is similar to what Pluto is made of," he added. "These are very soft materials, compared with rocky silicate. It's more easily pulled into a sphere than rock or metal."

Orbits of objects in our solar system, showing the current location of the planetary body "DeeDee."
Adding more fodder to the debate over the definition, when the New Horizons spacecraft flew by Pluto in 2015, it unveiled a world of surprising complexity, ranging from mountainous areas to vast nitrogen-ice lakes.

"We call Pluto a 'dwarf' planet, but it's just an adjective for 'planet,’” Runyon said. “It's still a planet, and that's where we take umbrage with the IAU.”

"Astronomers aren't experts in planetary science, and they basically passed a bunch of B.S. off on the public back in 2006 with a planet classification so flawed that it rules the Earth out as a planet, too," Stern remarked in 2016. "A week later, hundreds of planetary scientists, more people than at the IAU vote, signed a petition that rejects the new definition. If you go to planetary science meetings and hear technical talks on Pluto, you will hear experts calling it a planet every day."

Read more at Discovery News

Humans Are Threatening the World’s Supply of ‘Fossil’ Groundwater

Human activity risks contaminating pristine water stockpiled deep underground since the age of the mammoths, said a study Tuesday that warns of a looming threat to a critical life source.

So-called "fossil" groundwater — more than 12,000 years old — trickled into sub-surface aquifers long before it could be tarnished by pollution from farming and factory chemicals.

Generally stored at depths of more than 250 meters (820 feet) under the Earth's surface, the ancient resource had been assumed to be shielded from pollution by humans — who rely on it more and more as shallower sources dry up.

Now, researchers have found traces of modern-era rainwater in wells that bring "fossil" groundwater to the surface — pointing to a contamination risk.

"It's a bit like going to an old folks' home and suddenly realizing there are also little kids running around. That's great, except if the little kids have the flu," said study co-author James Kirchner of the Swiss Federal Institute of Technology in Zurich.

The fear, he explained, is that younger water may pollute the ancient aquifers with fertilizers, pesticides, or industrial runoff from Earth's surface — though they have not found any evidence for this yet.

Groundwater is rain or melted ice that filters through Earth's rocky layers to pool in aquifers — a process that can take thousands, even millions, of years.

It is the largest store of unfrozen fresh water on Earth.

Groundwater is pumped to the surface with wells for drinking and irrigation, and supplies about a third of human water needs.

Thinking long-term


For the latest study, presented at a European Geosciences Union meeting in Vienna, a research team set out to determine how old Earth's groundwater really is.

They used radiocarbon and tritium content to distinguish old from young groundwater and determine their relative abundance.

New groundwater has more tritium, a short-lived isotope of hydrogen, as it was more recently exposed to Earth's atmosphere and surface, tainted by nuclear tests since about the 1950s.

Radiocarbon, on the other hand, takes almost 6,000 years to decay. It is therefore much less abundant in fossil water.

The data showed that "most of the groundwater under our feet is surprisingly old," said Kirchner.

Roughly half — potentially more — dates from 12,000 years ago or more.

"The assumption would be if your groundwater comes from a time when mammoths were roaming the Earth, that those mammoths did not have chlorinated hydrocarbons," Kirchner explained.

"If your water dates from a... pre-industrial era, the assumption would be it can't be carrying industrial-era contaminants down underground."

Against expectations, however, the team found that about half of "fossil" groundwater wells they studied contained detectable levels of tritium, indicating the presence of younger water.

"This observation questions the common perception that fossil groundwaters are largely immune to modern contamination," concluded the study, published in the journal Nature Geoscience.

Fellow author Scott Jasechko, of the University of Calgary, said the findings were worrying on two levels.

Not only may "fossil" groundwater be exposed to contamination, it would also take millennia to replenish once used up.

"Conserving groundwater for future generations is important and requires us to consider timespans beyond the typical political or land management timescales of years or decades," he told AFP.

Read more at Discovery News

Apr 24, 2017

Atomic-level motion may drive bacteria's ability to evade immune system defenses

The scientists conducted their experiments in Staphylococcus aureus, a common cause of skin, sinus and lung infections.
A study from Indiana University has found evidence that extremely small changes in how atoms move in bacterial proteins can play a big role in how these microorganisms function and evolve.

The research, recently published in the Proceedings of the National Academy of Sciences, is a major departure from prevailing views about the evolution of new functions in organisms, which regarded a protein's shape, or "structure," as the most important factor in controlling its activity.

"This study gives us a significant answer to the following question: How do different organisms evolve different functions with proteins whose structures all look essentially the same?" said David Giedroc, Lilly Chemistry Alumni Professor in the IU Bloomington College of Arts and Sciences' Department of Chemistry, who is senior author on the study. "We've found evidence that atomic motions in proteins play a major role in impacting their function."

The study also provides new insights into how microorganisms respond to their host's efforts to limit bacterial infection. Serious bacterial infections in people include severe health-care-associated infections and tuberculosis, both of which have grown increasingly common over the past decade due to rising drug resistance in bacteria. About 480,000 people worldwide develop multidrug-resistant tuberculosis each year, for example, according to the Centers for Disease Control and Prevention.

"What we've shown is atomic-level motional disorder -- or entropy -- can impact gene transcription to affect the function of proteins in major ways, and that these motions can be 'tuned' evolutionarily," said Daiana A. Capdevila, a postdoctoral researcher in Giedroc's lab, who is first author on the study. "This may allow bacteria to rapidly evolve new ways to overcome medical treatment since atomic motions can be optimized for function more easily than a physical structure."

In the battle between bacterial infection and modern medicine, she said a key step is "mapping" the enemy's territory. Unraveling the molecular structure of proteins that trigger the mechanisms that thwart the human immune system informs the design of new drugs. However, this approach is based on the assumption that a protein's shape fundamentally controls its behavior.

It also assumes proteins are rigid. The new study shows protein function is better understood by studying the structure's internal atomic motion.

"This work is the clearest example thus far of the central and critical role that conformational entropy plays in protein regulation," said Josh Wand, the Benjamin Rush Professor at the University of Pennsylvania's Perelman School of Medicine, who is the author of a commentary paper on the study. "The authors do an impressive array of difficult and intensive experiments to unveil and confirm this conclusion."

Specifically, Giedroc and colleagues analyzed a protein called CzrA that controls how bacteria regulate zinc levels, an important ability that provides microorganisms the power to resist the human immune system. Zinc regulation allows the body to fight off infection by either flooding invaders with zinc, causing cellular death or completely starving them of the element, which also kills infectious agents.

"CzrA controls a biological mechanism in bacteria called the 'zinc pump,' which pushes extra zinc out of bacterial cells in response to the immune system's attempts to poison them with the metal," said Giedroc, whose lab has been studying this process for over 15 years.

Through the use of nuclear magnetic resonance spectroscopy, he and colleagues measured the movement of atoms in CzrA and identified those most affected by zinc. They then "swapped" these atoms out with different amino acids and found that the protein almost completely lost the ability to regulate zinc levels in cells. The experiment revealed unexpected areas on the molecule that appeared to play a role a role in zinc regulation, despite their physically distant location on the protein "map."

"There's no way anyone could have predicted these areas played a role in zinc regulation by simply looking at the protein structure," Giedroc said. "Once you know where these 'hot spots' are located, however, it's theoretically possible to design a small molecule or drug to produce the same effect as our amino acid-swapping experiment -- that is, to essentially shut off the protein."

In fact, this is one of the main concepts behind a powerful new class of drugs called "allosteric drugs," so named because they're designed to affect areas on a protein -- called allosteric sites -- that enhance or regulate the primary function of the protein, such as zinc binding, without directly targeting the part of the protein that controls the primary function.

Read more at Science Daily

Wax worm caterpillar will eat plastic shopping bags: New solution to plastic waste?

This image shows a wax worm chewing a hole through plastic. Polyethylene debris can be seen attached to the caterpillar.
Generally speaking, plastic is incredibly resistant to breaking down. That's certainly true of the trillion polyethylene plastic bags that people use each and every year. But researchers reporting in Current Biology on April 24 may be on track to find a solution to plastic waste. The key is a caterpillar commonly known as a wax worm.

"We have found that the larva of a common insect, Galleria mellonella, is able to biodegrade one of the toughest, most resilient, and most used plastics: polyethylene," says Federica Bertocchini of the Institute of Biomedicine and Biotechnology of Cantabria in Spain. A previous study (doi: 10.1021/es504038a) has shown that Plodia interpunctella wax worms, the larvae of dian mealmoths, can also digest plastic.

Bertocchini and her colleagues made the discovery quite by accident, after noticing that plastic bags containing wax worms quickly became riddled with holes. Further study showed that the worms can do damage to a plastic bag in less than an hour.

After 12 hours, all that munching of plastic leads to an obvious reduction in plastic mass. The researchers showed that the wax worms were not only ingesting the plastic, they were also chemically transforming the polyethylene into ethylene glycol. This is suspected to be the case in Plodia interpunctella as well.

Although wax worms wouldn't normally eat plastic, the researchers suspect that their ability is a byproduct of their natural habits. Wax moths lay their eggs inside beehives. The worms hatch and grow on beeswax, which is composed of a highly diverse mixture of lipid compounds. The researchers say the molecular details of wax biodegradation require further investigation, but it's likely that digesting beeswax and polyethylene involves breaking down similar types of chemical bonds.

"Wax is a polymer, a sort of 'natural plastic,' and has a chemical structure not dissimilar to polyethylene," Bertocchini says.

As the molecular details of the process become known, the researchers say it could be used to devise a biotechnological solution to managing polyethylene waste. They'll continue to explore the process in search of such a strategy.

Read more at Science Daily

NASA's Cassini, Voyager missions suggest new picture of Sun's interaction with galaxy

New data from NASA's Cassini, Voyager and Interstellar Boundary Explorer missions show that the heliosphere -- the bubble of the sun's magnetic influence that surrounds the inner solar system -- may be much more compact and rounded than previously thought. This illustration shows a compact model of the heliosphere, supported by this latest data. The main difference between this and previous models is the new model's lack of a trailing, comet-like tail on one side of the heliosphere.
New data from NASA's Cassini mission, combined with measurements from the two Voyager spacecraft and NASA's Interstellar Boundary Explorer, or IBEX, suggests that our sun and planets are surrounded by a giant, rounded system of magnetic field from the sun -- calling into question the alternate view of the solar magnetic fields trailing behind the sun in the shape of a long comet tail.

The sun releases a constant outflow of magnetic solar material -- called the solar wind -- that fills the inner solar system, reaching far past the orbit of Neptune. This solar wind creates a bubble, some 23 billion miles across, called the heliosphere. Our entire solar system, including the heliosphere, moves through interstellar space. The prevalent picture of the heliosphere was one of comet-shaped structure, with a rounded head and an extended tail. But new data covering an entire 11-year solar activity cycle show that may not be the case: the heliosphere may be rounded on both ends, making its shape almost spherical. A paper on these results was published in Nature Astronomy on April 24, 2017.

"Instead of a prolonged, comet-like tail, this rough bubble-shape of the heliosphere is due to the strong interstellar magnetic field -- much stronger than what was anticipated in the past -- combined with the fact that the ratio between particle pressure and magnetic pressure inside the heliosheath is high," said Kostas Dialynas, a space scientist at the Academy of Athens in Greece and lead author on the study.

An instrument on Cassini, which has been exploring the Saturn system over a decade, has given scientists crucial new clues about the shape of the heliosphere's trailing end, often called the heliotail. When charged particles from the inner solar system reach the boundary of the heliosphere, they sometimes undergo a series of charge exchanges with neutral gas atoms from the interstellar medium, dropping and regaining electrons as they travel through this vast boundary region. Some of these particles are pinged back in toward the inner solar system as fast-moving neutral atoms, which can be measured by Cassini.

"The Cassini instrument was designed to image the ions that are trapped in the magnetosphere of Saturn," said Tom Krimigis, an instrument lead on NASA's Voyager and Cassini missions based at Johns Hopkins University's Applied Physics Laboratory in Laurel, Maryland, and an author on the study. "We never thought that we would see what we're seeing and be able to image the boundaries of the heliosphere."

Because these particles move at a small fraction of the speed of light, their journeys from the sun to the edge of the heliosphere and back again take years. So when the number of particles coming from the sun changes -- usually as a result of its 11-year activity cycle -- it takes years before that's reflected in the amount of neutral atoms shooting back into the solar system.

Cassini's new measurements of these neutral atoms revealed something unexpected -- the particles coming from the tail of the heliosphere reflect the changes in the solar cycle almost exactly as fast as those coming from the nose of the heliosphere.

"If the heliosphere's 'tail' is stretched out like a comet, we'd expect that the patterns of the solar cycle would show up much later in the measured neutral atoms," said Krimigis.

But because patterns from solar activity show just as quickly in tail particles as those from the nose, that implies the tail is about the same distance from us as the nose. This means that long, comet-like tail that scientists envisioned may not exist at all -- instead, the heliosphere may be nearly round and symmetrical.

A rounded heliosphere could come from a combination of factors. Data from Voyager 1 show that the interstellar magnetic field beyond the heliosphere is stronger than scientists previously thought, meaning it could interact with the solar wind at the edges of the heliosphere and compact the heliosphere's tail.

The structure of the heliosphere plays a big role in how particles from interstellar space -- called cosmic rays -- reach the inner solar system, where Earth and the other planets are.

Read more at Science Daily

Earliest Fungus-Like Fossils Discovered in 2.4 Billion-Year-Old South African Bedrock

An international group of scientists says it has discovered 2.4 billion-year-old fungus-like fossils — approximately 2 billion years older than any previous fungal specimen and a billion or more years earlier than scientists currently think fungi first evolved. If accurate, the finding could reset the spacing of some of the earliest branches on the tree of life.

Birger Rasmussen, a professor at the Western Australian School of Mines, was looking for minerals to date ancient submarine lava collected from bedrock in Northern Cape Province, South Africa, when he found microfilaments in millimeter-sized gas bubbles.

“I was startled to find a dense mesh of tangled fossilized microbes,” Rasmussen said.

But gas bubbles in submarine lava can provide a habitat for microorganisms, and knowing that, “we were on the active lookout for fossils in the ancient deep biosphere,” said Stefan Bengtson, professor emeritus in paleobiology at the Swedish Museum. He is the lead author of a paper describing the findings, which is published today in Nature Ecology & Evolution. Rasmussen was not looking for the fungus-like structures, “but he had the right mindset to recognize them as fossils,” Bengtson said. “It was not accidental.”

a, Section through complete vesicle; frame indicates region depicted in e. b,c, Anastomoses and false branching. d,e, Brooms. f,g, Y-junctions, T-junctions and touching filaments. h,i, Loops and touching filaments. j, Bulbous protrusions. an, anastomosis; bf, basal film; bp, bulbous protrusion; br, broom; fb, false branching; lo, loop; tf, touching filaments; Tj, T-junction; Yj, Y-junction.
The South African lava surrounding the fossils was dated at 2.4 billion years old. The structures were found in tiny bubbles and voids within the lava that generally fill with other minerals within 10 million years of forming, Bengtson said, meaning the fossils would be approximately the same age as the rock.

“Our organisms had only a limited time to thrive,” he said.

It is possible, according to Bengtson, that an organism other than fungi formed the structures.

“This is why we call the fossils ‘fungus-like’ rather than ‘fungal’,” he said. “We have been careful to point out that the filaments we see are very simple.”

He described the fossil samples as looking like jumbles of tangled threads that branch and rejoin and said what appear to be bumps along the threads may be spores. There are no known non-fungal equivalents to what was found, Bengtson said.

"[The fossils] are practically indistinguishable in habitus and habitat from the proven fungi in the much younger fossil record,” Bengtson said. “We were quite excited that the fossils were so fungus-like."

The fossiliferous sample is from the lower part of the Ongeluk Formation (drill depth 21.79 m). Fm., formation; subgrp, subgroup. Modified from ref. 53, Geological Society of America.
If the research holds, it would dramatically change “our sense of the timetable of evolutionary history,” said Andrew H. Knoll, Fisher Professor of Natural History at Harvard University.

Knoll, however, remains cautious.

“Without actually having seen [the research], and giving them the benefit of the doubt, I wouldn't immediately rule out the idea that they are correct in their interpretation,” he said.

He is skeptical about the timeframe. A fungus is a eukaryote — an organism with a complex cell structure that needs oxygen. A 2.4 billion-year-old fungus-like eukaryote would have been using oxygen at nearly the same time scientists think oxygen first appeared in notable amounts on the planet.

Read more at Discovery News

Apr 23, 2017

Making batteries from waste glass bottles

Waste glass bottles are turned into nanosilicon anodes using a low cost chemical process.
Researchers at the University of California, Riverside's Bourns College of Engineering have used waste glass bottles and a low-cost chemical process to create nanosilicon anodes for high-performance lithium-ion batteries. The batteries will extend the range of electric vehicles and plug-in hybrid electric vehicles, and provide more power with fewer charges to personal electronics like cell phones and laptops.

Titled "Silicon Derived from Glass Bottles as Anode Materials for Lithium Ion Full Cell Batteries," an article describing the research was published in the Nature journal Scientific Reports. Cengiz Ozkan, professor of mechanical engineering, and Mihri Ozkan, professor of electrical engineering, led the project.

Even with today's recycling programs, billions of glass bottles end up in landfills every year, prompting the researchers to ask whether silicon dioxide in waste beverage bottles could provide high purity silicon nanoparticles for lithium-ion batteries.

Silicon anodes can store up to 10 times more energy than conventional graphite anodes, but expansion and shrinkage during charge and discharge make them unstable. Downsizing silicon to the nanoscale has been shown to reduce this problem, and by combining an abundant and relatively pure form of silicon dioxide and a low-cost chemical reaction, the researchers created lithium-ion half-cell batteries that store almost four times more energy than conventional graphite anodes.

To create the anodes, the team used a three-step process that involved crushing and grinding the glass bottles into a fine white power, a magnesiothermic reduction to transform the silicon dioxide into nanostructured silicon, and coating the silicon nanoparticles with carbon to improve their stability and energy storage properties.

As expected, coin cell batteries made using the glass bottle-based silicon anodes greatly outperformed traditional batteries in laboratory tests. Carbon-coated glass derived-silicon (gSi@C) electrodes demonstrated excellent electrochemical performance with a capacity of ~1420 mAh/g at C/2 rate after 400 cycles.

Changling Li, a graduate student in materials science and engineering and lead author on the paper, said one glass bottle provides enough nanosilicon for hundreds of coin cell batteries or three-five pouch cell batteries.

"We started with a waste product that was headed for the landfill and created batteries that stored more energy, charged faster, and were more stable than commercial coin cell batteries. Hence, we have very promising candidates for next-generation lithium-ion batteries," Li said.

Read more at Science Daily

New quantum liquid crystals may play role in future of computers

These images show light patterns generated by a rhenium-based crystal using a laser method called optical second-harmonic rotational anisotropy. At left, the pattern comes from the atomic lattice of the crystal. At right, the crystal has become a 3-D quantum liquid crystal, showing a drastic departure from the pattern due to the atomic lattice alone.
Physicists at the Institute for Quantum Information and Matter at Caltech have discovered the first three-dimensional quantum liquid crystal -- a new state of matter that may have applications in ultrafast quantum computers of the future.

"We have detected the existence of a fundamentally new state of matter that can be regarded as a quantum analog of a liquid crystal," says Caltech assistant professor of physics David Hsieh, principal investigator on a new study describing the findings in the April 21 issue of Science. "There are numerous classes of such quantum liquid crystals that can, in principle, exist; therefore, our finding is likely the tip of an iceberg."

Liquid crystals fall somewhere in between a liquid and a solid: they are made up of molecules that flow around freely as if they were a liquid but are all oriented in the same direction, as in a solid. Liquid crystals can be found in nature, such as in biological cell membranes. Alternatively, they can be made artificially -- such as those found in the liquid crystal displays commonly used in watches, smartphones, televisions, and other items that have display screens.

In a "quantum" liquid crystal, electrons behave like the molecules in classical liquid crystals. That is, the electrons move around freely yet have a preferred direction of flow. The first-ever quantum liquid crystal was discovered in 1999 by Caltech's Jim Eisenstein, the Frank J. Roshek Professor of Physics and Applied Physics. Eisenstein's quantum liquid crystal was two-dimensional, meaning that it was confined to a single plane inside the host material -- an artificially grown gallium-arsenide-based metal. Such 2-D quantum liquid crystals have since been found in several more materials including high-temperature superconductors -- materials that conduct electricity with zero resistance at around -150 degrees Celsius, which is warmer than operating temperatures for traditional superconductors.

John Harter, a postdoctoral scholar in the Hsieh lab and lead author of the new study, explains that 2-D quantum liquid crystals behave in strange ways. "Electrons living in this flatland collectively decide to flow preferentially along the x-axis rather than the y-axis even though there's nothing to distinguish one direction from the other," he says.

Now Harter, Hsieh, and their colleagues at Oak Ridge National Laboratory and the University of Tennessee have discovered the first 3-D quantum liquid crystal. Compared to a 2-D quantum liquid crystal, the 3-D version is even more bizarre. Here, the electrons not only make a distinction between the x, y, and z axes, but they also have different magnetic properties depending on whether they flow forward or backward on a given axis.

"Running an electrical current through these materials transforms them from nonmagnets into magnets, which is highly unusual," says Hsieh. "What's more, in every direction that you can flow current, the magnetic strength and magnetic orientation changes. Physicists say that the electrons 'break the symmetry' of the lattice."

Harter actually hit upon the discovery serendipitously. He was originally interested in studying the atomic structure of a metal compound based on the element rhenium. In particular, he was trying to characterize the structure of the crystal's atomic lattice using a technique called optical second-harmonic rotational anisotropy. In these experiments, laser light is fired at a material, and light with twice the frequency is reflected back out. The pattern of emitted light contains information about the symmetry of the crystal. The patterns measured from the rhenium-based metal were very strange -- and could not be explained by the known atomic structure of the compound.

"At first, we didn't know what was going on," Harter says. The researchers then learned about the concept of 3-D quantum liquid crystals, developed by Liang Fu, a physics professor at MIT. "It explained the patterns perfectly. Everything suddenly made sense," Harter says.

The researchers say that 3-D quantum liquid crystals could play a role in a field called spintronics, in which the direction that electrons spin may be exploited to create more efficient computer chips. The discovery could also help with some of the challenges of building a quantum computer, which seeks to take advantage of the quantum nature of particles to make even faster calculations, such as those needed to decrypt codes. One of the difficulties in building such a computer is that quantum properties are extremely fragile and can easily be destroyed through interactions with their surrounding environment. A technique called topological quantum computing -- developed by Caltech's Alexei Kitaev, the Ronald and Maxine Linde Professor of Theoretical Physics and Mathematics -- can solve this problem with the help of a special kind of superconductor dubbed a topological superconductor.

Read more at Science Daily

Apr 22, 2017

In young bilingual children, two languages develop simultaneously but independently

Erika Hoff, Ph.D., lead author of the study, a psychology professor in FAU’s Charles E. Schmidt College of Science, and director of the Language Development Lab.
A new study of Spanish-English bilingual children by researchers at Florida Atlantic University published in the journal Developmental Science finds that when children learn two languages from birth each language proceeds on its own independent course, at a rate that reflects the quality of the children's exposure to each language.

In addition, the study finds that Spanish skills become vulnerable as children's English skills develop, but English is not vulnerable to being taken over by Spanish. In their longitudinal data, the researchers found evidence that as the children developed stronger skills in English, their rates of Spanish growth declined. Spanish skills did not cause English growth to slow, so it's not a matter of necessary trade-offs between two languages.

"One well established fact about monolingual development is that the size of children's vocabularies and the grammatical complexity of their speech are strongly related. It turns out that this is true for each language in bilingual children," said Erika Hoff, Ph.D., lead author of the study, a psychology professor in FAU's Charles E. Schmidt College of Science, and director of the Language Development Lab. "But vocabulary and grammar in one language are not related to vocabulary or grammar in the other language."

For the study, Hoff and her collaborators David Giguere, a graduate research assistant at FAU and Jamie M. Quinn, a graduate research assistant at Florida State University, used longitudinal data on children who spoke English and Spanish as first languages and who were exposed to both languages from birth. They wanted to know if the relationship between grammar and vocabulary were specific to a language or more language general. They measured the vocabulary and level of grammatical development in these children in six-month intervals between the ages of 2 and a half to 4 years.

The researchers explored a number of possibilities during the study. They thought it might be something internal to the child that causes vocabulary and grammar to develop on the same timetable or that there might be dependencies in the process of language development itself. They also considered that children might need certain vocabulary to start learning grammar and that vocabulary provides the foundation for grammar or that grammar helps children learn vocabulary. One final possibility they explored is that it may be an external factor that drives both vocabulary development and grammatical development.

"If it's something internal that paces language development then it shouldn't matter if it's English or Spanish, everything should be related to everything," said Hoff. "On the other hand, if it's dependencies within a language of vocabulary and grammar or vice versa then the relations should be language specific and one should predict the other. That is a child's level of grammar should predict his or her future growth in vocabulary or vice versa."

Turns out, the data were consistent only with the final possibility -- that the rate of vocabulary and grammar development are a function of something external to the child and that exerts separate influences on growth in English and Spanish. Hoff and her collaborators suggest that the most cogent explanation would be in the properties of children's input or their language exposure.

"Children may hear very rich language use in Spanish and less rich use in English, for example, if their parents are more proficient in Spanish than in English," said Hoff. "If language growth were just a matter of some children being better at language learning than others, then growth in English and growth in Spanish would be more related than they are."

Detailed results of the study are described in the article, "What Explains the Correlation between Growth in Vocabulary and Grammar? New Evidence from Latent Change Score Analyses of Simultaneous Bilingual Development."

Read more at Science Daily

How Venus flytrap triggers digestion

The traps' insides are lined with red glands (a) that work like a plant 'stomach' after a prey is caught. The glands secrete a digestive enzyme. This secretory mechanism was shown at the vesicle level in plants for the first time (b). The model illustration (c) shows that activated glands absorb calcium (Ca2+), thereby triggering the jasmonate signalling pathway and the secreting of hydrochloric acid (HCL) and digestive enzymes.
Venus flytrap (Dionaea muscipula) is a carnivorous plant. Catching its prey, mainly insects, with a trapping structure formed by its leaves, the plants' glands secrete an enzyme to decompose the prey and take up the nutrients released.

Although postulated since Darwin's pioneering studies, these secretory events have not been measured and analysed until now: An international team of researchers headed by Rainer Hedrich, a biophysicist from Julius-Maximilians-Universität (JMU) Würzburg in Bavaria, Germany, present the results in the journal PNAS.

When a prey tries to escape the closed trap, it will inevitably touch the sensory hairs inside. Any mechanical contact with the hairs triggers an electrical signal that spreads across the trap in waves. From the third signal, the plant produces the hormone jasmonate; after the fifth signal, the digestive glands that line the inside of the traps like turf are activated.

Glands secrete acidic vesicles to decompose prey

What happens next in the gland cells? They increasingly produce membranous bubbles filled with liquid (secretory vesicles) and give off their content. This happens after mechanical stimulation of the sensory hairs but also when the glands come into contact with the hormone jasmonate. The entire process depends on calcium and is controlled by a number of specific proteins.

Moreover, genes are activated in the glands: "We assume that they provide for the vesicles being loaded with protons and chloride, that is hydrochloric acid," Hedrich explains and he adds: "We used ion-sensitive electrodes to measure that repeated touching of the sensory hairs triggers the influx of calcium ions into the gland. The rising calcium level in the cytoplasm causes the vesicles to fuse with the plasma membrane, similarly to the neurotransmitter secretion of neurons. The influx of calcium is followed by the efflux of protons and chloride after a time delay."

Conclusive analysis with carbon fibre electrodes

What else do the gland vesicles contain? This was analysed using carbon fibre electrodes in cooperation with Erwin Neher (Göttingen), winner of the Nobel Prize, who has a lot of experience with this technique. Together with Neher, the JMU researcher Sönke Scherzer adjusted the measurement method to the conditions prevailing inside the Venus flytrap.

The team positioned a carbon fibre electrode over the gland surface and waited with excitement what would happen. "At first, we were disappointed because we did not immediately detect signals as known from secretory cells in humans and animals," Scherzer recalls.

Should the vesicles contain hydrochloric acid in the first hours after catching the prey but no digestive enzymes yet? And no molecules yet that assure the enzymes' functioning in the acidic environment? Does the plant have to produce all this first?

That's exactly how it works: Molecular biologist Ines Fuchs found out that the plant only starts to produce the enzymes that decompose the prey after several hours. The first characteristic signals occurred after six hours and the process was in full swing 24 hours later. During this phase, the trap is completely acidic and rich in digestive enzymes.

Stabilising effect of glutathione keeps enzymes fit


Professor Heinz Rennenberg (Freiburg) also found glutathione (GSH) in the secreted enzyme. This molecule keeps the enzymes functional in the acidic environment of the Venus flytrap.

The same processes as described above take place in the same chronological order both when the sensory hairs are stimulated and when exposing the trap to the hormone jasmonate only. "A touch will very quickly trigger the jasmonate signalling pathway, but it takes time until the vesicles are produced and loaded with the proper freight which is facilitated by the hormone," Hedrich explains.

Read more at Science Daily

Apr 21, 2017

Environmental 'memories' passed on for 14 generations

This is a C. elegans worm.
Led by Dr Ben Lehner, group leader at the EMBL-CRG Systems Biology Unit and ICREA and AXA Professor, together with Dr Tanya Vavouri from the Josep Carreras Leukaemia Research Institute and the Institute for Health Science Research Germans Trias i Pujol (IGTP), the researchers noticed that the impact of environmental change can be passed on in the genes for many generations while studying C. elegans worms carrying a transgene array -- a long string of repeated copies of a gene for a fluorescent protein that had been added into the worm genome using genetic engineering techniques.

If the worms were kept at 20 degrees Celsius, the array of transgenes was less active, creating only a small amount of fluorescent protein. But shifting the animals to a warmer climate of 25 degrees significantly increased the activity of the transgenes, making the animals glow brightly under ultraviolet light when viewed down a microscope.

When these worms were moved back to the cooler temperature, their transgenes were still highly active, suggesting they were somehow retaining the 'memory' of their exposure to warmth. Intriguingly, this high activity level was passed on to their offspring and onwards for 7 subsequent generations kept solely at 20 degrees, even though the original animals only experienced the higher temperature for a brief time. Keeping worms at 25 degrees for five generations led to the increased transgene activity being maintained for at least 14 generations once the animals were returned to cooler conditions.

Although this phenomenon has been seen in a range of animal species -- including fruit flies, worms and mammals including humans -- it tends to fade after a few generations. These findings, which will be published in the journal Science, represent the longest maintenance of transgenerational environmental 'memory' ever observed in animals to date.

"We discovered this phenomenon by chance, but it shows that it's certainly possible to transmit information about the environment down the generations," says Lehner. "We don't know exactly why this happens, but it might be a form of biological forward-planning," adds the first author of the study and CRG Alumnus, Adam Klosin. "Worms are very short-lived, so perhaps they are transmitting memories of past conditions to help their descendants predict what their environment might be like in the future," adds Vavouri.

Comparing the transgenes that were less active with those that had become activated by the higher temperature, Lehner and his team discovered crucial differences in a type of molecular 'tag' attached to the proteins packaging up the genes, known as histone methylation.

Transgenes in animals that had only ever been kept at 20 degrees had high levels of histone methylation, which is associated with silenced genes, while those that had been moved to 25 degrees had largely lost the methylation tags. Importantly, they still maintained this reduced histone methylation when moved back to the cooler temperature, suggesting that it is playing an important role in locking the memory into the transgenes.

Read more at Science Daily

Astronomers perform largest-ever survey of high-mass binary star systems

The Milky Way.
In addition to solo stars like our Sun, the universe contains binary systems comprising two massive stars that interact with each other. In many binaries the two stars are close enough to exchange matter and may even merge, producing a single high-mass star that spins at great speed.

Until now the number of known high-mass binaries has been very small, basically confined to those identified in our galaxy, the Milky Way.

An international group of astronomers led by researchers at the University of São Paulo's Institute of Astronomy, Geophysics & Atmospheric Sciences (IAG-USP) in Brazil, have just extended the list of by identifying and characterizing 82 new high-mass binaries located in the Tarantula Nebula, also known as 30 Doradus, in the Large Magellanic Cloud. The LMC is a satellite galaxy of the Milky Way and is about 160,000 light years from Earth.

The results of the study are described in article published in the journal Astronomy & Astrophysics.

"By identifying and characterizing these 82 high-mass binaries, we have more than doubled the number of these objects, and in a completely new region with very different conditions from those found in the Milky Way," said Leonardo Andrade de Almeida, a postdoctoral fellow at IAG-USP and first author of the study.

In research supervised by Augusto Damineli Neto, a full professor at IAG and a co-author of the article, Almeida analyzed the data obtained during the VLT-FLAMES Tarantula Survey and Tarantula Massive Binary Monitoring observation campaigns performed by the European Southern Observatory (ESO) from 2011.

Using FLAMES/GIRAFFE, a spectrograph coupled to ESO's Very Large Telescope (VLT), which has four 8 m primary mirrors and operates in Chile's Atacama Desert, the observation campaigns collected spectral data for over 800 high-mass objects in the region of the Tarantula Nebula, so named because its glowing filaments resemble spider legs.

From this total of 800 observed objects, the astronomers who worked on the two surveys identified 100 candidate binaries of spectral type O (very hot and massive) in a sample of 360 stars based on parameters such as the amplitude of variations in their radial velocity (the velocity of motion away from or toward an observer).

For the last two years, Almeida has collaborated with colleagues in other countries on an analysis of these 100 candidate high-mass binaries using the FLAMES/GIRAFFE spectrograph and has managed to characterize 82 of them completely.

"This represents the largest survey and spectroscopic characterization of massive binary systems every performed," he said. "It was only possible thanks to the technological capabilities of the FLAMES/GIRAFFE spectrograph."

The scientific instrument developed by ESO can be used to obtain spectra for a number of objects simultaneously, and weaker objects can be observed because it is coupled to the VLT, which has large mirrors and captures more light, Almeida explained.

"We can collect 136 spectra in a single observation using FLAMES/GIRAFFE," he said. "Nothing similar could be done before. Our instruments could only observe individual objects and it took much longer to characterize them."

Spectroscopic analysis of the 82 binaries showed that properties such as mass ratio, orbital period (the time taken to complete one orbit) and orbital eccentricity (the amount by which the orbit deviates from a perfect circle) were highly similar to those observed in the Milky Way.

This was unexpected since the LMC embodies a phase of the universe prior to the Milky Way when the largest number of high-mass stars were formed. For this reason, its metallicity -- the proportion of its matter made up of chemical elements different from hydrogen and helium, the primordial atoms that gave rise to the first stars -- is only half that of the binaries found in the Milky Way, whose metallicity is very close to the Sun's.

"At the beginning of the universe, stars were metal-poor but chemical evolution increased their metallicity," Almeida said.

This analysis of binaries in the LMC, he added, provides the first direct constraints on the properties of massive binaries in galaxies whose stars were formed in the early universe and have the LMC's metallicity.

"The discoveries made during the study may provide better measurements for use in more realistic simulations of how high-mass stars evolved in the different phases of the universe. If so, we'll be able to obtain more precise estimates of the rate at which black holes, neutron stars and supernovae were formed in each phase, for example," he said.

High-mass stars are the most important drivers of the chemical evolution of the universe. Because they are more massive, they produce more heavy metals, evolve more rapidly, and end their lives as supernovae, ejecting all their matter into the interstellar medium. This matter is recycled to form a new population of stars.

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