Sep 23, 2016

Protoplanetary Disk Could Reveal Planetary Abortion

TW Hydrae is a young star sporting a beautiful protoplanetary disk that is almost perfectly face-on from our perspective. Within that disk, dark tracks have captivated astronomers who believe they hold clues to the earliest stages of planetary formation. In short, TW Hydrae is a stellar "petri dish," only 175 light-years away, showing us exactly where baby planets come from.

This now-famous observation, captured by the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, has gone one step further. In March, astronomers studying the emissions from the protoplanetary dust spotted something potentially groundbreaking. Close to the 10 million year-old star was a region lacking dust, possibly evidence for a world being born at roughly the same distance from the star as Earth orbits the sun. Could this be the earliest stages of the birth of an Earth-like planet? If so, the implications would be profound.

However, after carrying out computer simulations of the TW Hydrae protoplanetary disk, an international team of researchers led by Barbara Ercolano of Ludwig-Maximilians-Universität München, Germany, believes there may be another explanation for this innermost empty region and, sadly, it doesn't include a baby "Earth 2.0." In fact, the star may have aborted its birth.

When stars are young, they pump out huge amounts of ionizing radiation and blast out powerful stellar winds, vaporizing any dust that strays too close and blowing away any gases. In the case of a planet-forming disk around a young star, this could mean a region close to the star would be burnt away, leaving a gap.

ALMA observation of the TW Hydrae planet-forming disk, including the suspected Earth-like planet formation region that may, actually, be a region of photoevaporation.
The process, called "photoevaporation," could be ongoing in the TW Hydrae system, directly impacting the innermost region of the disk. The outer rings in the disk, however, are still likely being formed by accreting exoplanets sweeping up material as they orbit, it's just the inner region that is being vaporized.

Although this is obviously bad news for seeing the birth of an Earth-like exoplanent, TW Hydrae is proving an unprecedented opportunity for astronomers to study the destructive nature of a star in its earliest stages of evolution.

From Discovery News

Earth's Atmospheric Oxygen Levels Continue Long Slide

Researchers analyzed samples from ice core drilling stations in Antarctica and Greenland to evaluate the planet's atmospheric oxygen levels throughout history.
Atmospheric oxygen levels have declined over the past 1 million years, although not nearly enough to trigger any major problems for life on Earth, a new study finds.

The research behind this new finding could help shed light on what controls atmospheric oxygen levels over long spans of time, the researchers said.

Atmospheric oxygen levels are fundamentally linked to the evolution of life on Earth, as well as changes in geochemical cycles related to climate variations. As such, scientists have long sought to reconstruct how atmospheric oxygen levels fluctuated in the past, and what might control these shifts.

However, models of past atmospheric oxygen levels often markedly disagree, differing by as much as about 20 percent of Earth's atmosphere, which is oxygen's present-day concentration, the researchers said. 1 It is not even known if atmospheric oxygen levels varied or remained steady over the past 1 million years.

"There was no consensus on whether the oxygen cycle before humankind began burning fossil fuels was in or out of balance and, if so, whether it was increasing or decreasing," said study lead author Daniel Stolper, a geochemistat Princeton University in New Jersey.

In the new study, researchers calculated past atmospheric oxygen levels by looking at air trapped inside ancient polar ice samples. Specifically, they looked at samples from Greenland and Antarctica.

The new estimates suggest that atmospheric oxygen levels have fallen by 0.7 percent over the past 800,000 years. The scientists concluded that oxygen sinks — processes that removed oxygen from the air — were about 1.7 percent larger than oxygen sources during this time.

Although a drop in atmospheric oxygen levels might sound alarming, the decrease the researchers found "is trivial in regard to ecosystems," Stolper told Live Science. "To put it in perspective, the pressure in the atmosphere declines with elevation. A 0.7 percent decline in the atmospheric pressure of oxygen occurs at about 100 meters (330 feet) above sea level — that is, about the 30th floor of a tall building."

There are two hypotheses that may help explain this oxygen decline over the past million years, Stolper said.

"The first is that global erosion rates may have increased over the past few to tens of millions of years due to, among other things, the growth of glaciers — glaciers grind rock, thereby increasing erosion rates," Stolper said.

Rising erosion rates would have exposed more pyrite and organic carbon to the atmosphere. Pyrite is better known as fool's gold, and organic carbon consists of the remains of organisms, mostly land plants and aquatic photosynthetic microorganisms such as algae. Previous research found that both pyrite and organic carbon can react with oxygen and remove it from the atmosphere.

"Alternatively, when the ocean cools, as it has done over the past 15 million years, before fossil fuel burning, the solubility of oxygen in the ocean increases. That is, the oceans can store more oxygen at colder temperatures for a given concentration of oxygen in the atmosphere," Stolper said. Oxygen-dependent microbes in the ocean and in sediments can then become more active and consume this oxygen, leaving less of the element in the atmosphere, he added.

Read more at Discovery News

'Marsquakes' Could Give Alien Life a Boost

Humans and most animals, plants and fungi get their energy mainly from chemical reactions between oxygen and organic compounds such as sugars. However, microbes depend on a wide array of different reactions for energy; for instance, reactions between oxygen and hydrogen gas help bacteria called hydrogenotrophs survive deep underground on Earth, and previous research suggested that such reactions may have even powered the earliest life on Earth.

Prior work suggested that when rocks fracture and grind together during earthquakes on Earth, silicon in those rocks can react with water to generate hydrogen gas. Study lead author Sean McMahon, a geomicrobiologist at Yale University, and his colleagues wanted to see if marsquakes could generate enough hydrogen to support any microbes that might potentially live on the Red Planet.

The scientists examined special types of rocks that are created when rocks grind against each other during earthquakes. The samples the researchers analyzed from Scotland, Canada, South Africa, the Isles of Scilly off the coast of England and the Outer Hebrides of Scotland were up to hundreds of times richer in trapped hydrogen gas than surrounding rocks that were not generated from such grinding.

"These findings were surprising and exciting because we didn't know if we were going to find anything at all," McMahon said.

The researchers said the hydrogen gas in the samples they analyzed was abundant enough to support hydrogenotrophs on Earth.

"Our findings are a contribution to a broader picture of how geological processes can support microbial life in extreme environments," McMahon told "There's not much of what we think of as food miles below Earth's surface, but over the last few decades, scientists have found that Earth has a huge amount of biomass down there, maybe 20 percent or more of Earth's biomass."

When it comes to whether marsquakes and water might work together to generate hydrogen on Mars, previous research suggested that liquid water was once abundant on the surface of Mars. It also suggests that large reserves of liquid water may still exist underground on the Red Planet at depths of about 3 miles (5 kilometers) on average. However,Mars has much fewer quakes than Earth, because the Red Planet nowadays lacks both volcanism and plate tectonics.

Still, the researchers noted that conservative models of marsquakes based off data from NASA's Mars Global Surveyor suggest that, on average, the Red Planet experiences a magnitude-2 event every 34 days and a magnitude-7 event every 4,500 years. This means that marsquakes may on average generate less than 11 tons (10 metric tons) of hydrogen annually over the whole of Mars, which may be still enough to sporadically fuel pockets of microbial activity there, the researchers said.

Read more at Discovery News

Teeth Suggest Humans Killed Hobbits

Recreation of a Homo floresiensis male.
Humans were on hobbit turf at around the same time that the small people (Homo floresiensis) seemingly disappeared from Earth, according to new evidence presented this week in Madrid at the European Society for the Study of Human Evolution.

The evidence -- a pair of 46,000-year-old human teeth -- is described in a Nature report. The teeth were discovered at the former hobbit homeland, Liang Bua cave on the island of Flores in Indonesia.

Scientists exploring Liang Bua cave on the Indonesian island of Flores.
Earlier research determined that members of our species were living in southeast Asia by around 50,000 years ago. Around this time in Liang Bua, H. floresiensis -- and animals including giant storks, pygmy elephants and Komodo dragons -- disappeared. Scientists began to suspect that Homo floresiensis was not a stranger to Homo sapiens.

This possibility was deemed a "smoking gun" by Bert Roberts of the University of Wollongong earlier this year, but he had not yet found the "bullet" linking the two human groups.

"The exact cause of the demise of the hominids and associated animals is not yet understood, but in my view, may be related to the appearance in the area of the most aggressive of all hominin species, Homo sapiens, modern humans," said Donald Johanson, founding director of the Institute of Human Origins at Arizona State University.

Recreation of a Homo floresiensis individual.
The 46,000-year-old human teeth, consisting of an upper premolar and a lower molar, support Johanson's view. Roberts, archaeologist Thomas Sutikna and their team found the teeth while excavating the hobbit cave.

The researchers also found freshwater mollusk shells, which are commonly associated with early Homo sapiens sites in Europe, Africa and other parts of Asia. Stone tools made from a hard rock known as chert were additionally unearthed, as was evidence for fire hearths. All are typical of early human settlements.

Read more at Discovery News

Sep 22, 2016

Exotic Star System Discovered via Spacetime Warp

For the vast majority of exoplanetary discoveries, one or more planets are found orbiting one star. However, there are a few exotic exoplanets orbiting two stars and the Hubble Space Telescope has helped confirm the discovery of a unique star system.

Way back in 2007, a ground-based system looking for transient brightenings -- called "microlensing" events -- detected a peculiar signal.

Microlensing events are caused when a massive object, like a planet or star, passes in front of a more distant background star. As predicted by Einstein's theory of general relativity, the lensing object will warp spacetime, causing any light passing by to slightly change its path. Should the alignment between distant star, lensing object and Earth be just right, the object can create a spacetime lens -- akin to passing a magnifying lens in front of a candle flame.

The result is a short-lived brightening of the background star. By studying the microlensing event light-curve (i.e. how the brightening fluctuates with time), we can learn many things about the object(s) creating the lens.

But in the case of the 2007 event, the ground-based Optical Gravitational Lensing Experiment (or "OGLE") detected something else in the light-curve that confused matters. This wasn't a single object, it was a whole star system -- with a twist.

"A detailed analysis revealed a third lensing body in addition to the star and planet that were quite obvious from the data," said astronomer David Bennett, of NASA's Goddard Space Flight Center, in a statement.

But what does this mean? Through analysis of the signal, called OGLE-2007-BLG-349, there were two explanations. According to Bennett, there was either "a Saturn-mass planet orbiting a close binary star pair or a Saturn-mass and an Earth-mass planet orbiting a single star."

As microlensing events are, by their nature, one-offs, astronomers needed another way to confirm the nature of OGLE-2007-BLG-349 and Hubble has been used to zoom in on the star system that triggered the 2007 brightening.

It turns out that OGLE-2007-BLG-349 was caused by a planet orbiting two stars, both tiny red dwarfs, drifting in front of a more distant bright star. This is the first time a binary system plus single exoplanet has been discovered through microlensing. "We were helped in the analysis by the almost perfect alignment of the foreground binary stars with the background star, which greatly magnified the light and allowed us to see the signal of the two stars," Bennett added.

Read more at Discovery News

Wanna-Be Dino? Prehistoric Reptile Looked Like a Dinosaur

The preserved remains of Triopticus (left) show the evolution of a thickened domed skull in the Triassic Period, 150 million years before the evolution of the famous dome-headed pachycephalosaur dinosaurs, such as Stegoceras (right). The background image shows the field site in Texas where WPA crews in 1940 found the curious fossils of Triopticus.
A reptile that lived before the Dinosaur Age resembled a dino, suggesting that iconic dinosaur body shapes were present long before the dinosaurs themselves actually emerged.

The newly identified reptile, described in the journal Current Biology, resembled pachycephalosaur dinosaurs that lived more than 100 million years later. Other extinct animals found with the reptile looked like later dinos too.

The reptile has been named Triopticus primus, meaning the "First of Three Eyes" because the natural pit at the top of its skull lends the appearance of an extra eye.

"Triopticus is an extraordinary example of evolutionary convergence between the relatives of dinosaurs and crocodylians and later dinosaurs that is much more common than anyone ever expected," co-author and project leader Michelle Stocker, a Virgnia Tech College of Science researcher, said in a press release. "What we thought were unique body shapes in many dinosaurs actually evolved millions of years before in the Triassic Period, about 225 million years ago."

Convergence refers to when distantly related animals evolve to look very similar to each other. A classic example of this is a bird wing and a bat wing. Both animals use their wings for flight, yet the inner details of their wings are different and evolved independently.

Three Eyes dates to about 230 million years ago, according to the researchers. The reptile's partial skull was originally collected at a site called Otis Chalk near Big Spring, Texas, by the Works Progress Administration in 1940.

President Franklin Roosevelt had initiated a monumental effort to put Americans back to work at end the Great Depression. With so much digging going on, numerous fossils were unearthed. In fact, so many fossils were found during such a short time span that several of them were just put into storage uncleaned.

Such was the case for Three Eyes, whose skull was eventually sent to the Texas Vertebrate Paleontology Collections in 2010. It is there that Stocker and her team rediscovered and analyzed the specimen.

They determined that the reptile had an extremely thickened skull roof, just like the very distantly related pachycephalosaur dinosaurs that lived more than 100 million years after the lifetime of Three Eyes.

"CT scanning showed us that the similarity of Triopticus with the much later dome-headed pachycephalosaur dinosaurs was more than skin deep, extending to the structure of the bone and even the brain." co-author Lawrence Witmer of Ohio University's Heritage College of Osteopathic Medicine said.

It was not a coincidence that the reptile and dinosaurs resembled each other.

"After the enormous mass extinction 250 million years ago, reptiles exploded onto the scene and almost immediately diversified into many different sizes and shapes," co-author Sterling Nesbitt of Virginia Tech said. "These early body shapes were later mimicked by dinosaurs."

Read more at Discovery News

Dead Sea Scroll 'Virtually Unwrapped'

Shown is the completed virtual unwrapping for the En-Gedi scroll.
The En-Gedi scroll, a text that includes part of the Book of Leviticus in the Hebrew Bible that was ravaged by fire about 1,400 years ago, is now readable, thanks to a complex digital analysis called "virtual unwrapping."

Rather than physically unfurl the scroll, which would have destroyed the crumbling artifact, experts digitally scanned the document, and then virtually flattened the scanned results, allowing scholars to read its ancient text.

"We're reading a real scroll," lead study author Brent Seales, professor and chairman in the department of computer science at the University of Kentucky, said in a news conference yesterday (Sept. 20). "It hasn't been read for millennia. Many thought it was probably impossible to read."

Archaeologists found the scroll in 1970 in En-Gedi, where an ancient Jewish community thrived from about the late 700s B.C. until about A.D. 600, when a fire destroyed the site, the researchers said. Excavations of the synagogue's Holy Ark, a chest or cupboard that holds the Torah scrolls, revealed charred scrolls of parchment, or animal skin. But each scroll was "completely burned and crushed, had turned into chunks of charcoal that continued to disintegrate every time they were touched," the researchers wrote in the study.

The En-Gedi scroll is different than the original Dead Sea Scrolls, which a young shepherd discovered in caves near Qumran in the Judean Desert in 1947. However, Dead Sea Scroll has become an umbrella term for many ancient scrolls found in the area, and some researchers also call the En-Gedi artifact a Dead Sea Scroll.

The scorched En-Gedi scroll fragments sat in storage for more than 40 years until experts decided to give them another look, and try the newly developed "virtual unwrapping" method for the first time on the scroll.

Potential scroll fragments from En-Gedi that are severely burned.
The virtual journey began in Israel, where experts digitally scanned the rolled-up scroll with X-ray-based micro-computed tomography (micro-CT). At this point, they weren't sure whether the scroll had text within it, said study co-author Pnina Shor, curator and head of the Dead Sea Scrolls Projects at the Israel Antiquities Authority. So, they increased the spatial resolution of the scan, allowing them to capture whether or not each layer had detectable ink.

Their exhaustive attention to detail paid off: There was ink, and it likely contained metal, such as iron or lead, because it showed up on the micro-CT scan as a dense material, the researchers said.

However, the text was illegible. So Shor and her colleagues in Israel sent the digital scans to Seales in Kentucky so he and his team could try the new "virtual unwrapping" technique.

"It was certainly a shot in the dark," Shor said.

This new method marks the first time that experts have virtually unrolled and noninvasively studied a severely damaged scroll with ink text, Seales said.

The unwrapping took time and involved three steps: segmentation, texturing and flattening, he said.

With segmentation, they identified each segment, or layer, within the digital scroll, which had five complete revolutions of parchment in the scroll. Then, they created a virtual geometric mesh for each layer made of tiny, digital triangles. They were able to manipulate this mesh, which helped them "texture" the document, or make the text more visible.

"This is where we see letters and words for the first time on the recreated page," the researchers wrote in the study.

Finally, they digitally flattened the scroll, and merged the different layers together into one, flat 2D image that could easily be read.

The scroll holds the beginning of the Book of Leviticus, the third of the five books of Moses (known as the Pentateuch) that make up the Hebrew Bible, biblical scholars said. In fact, the En-Gedi scroll contains the earliest copy of a Pentateuchal book ever found in a Holy Ark, the researchers said.

The virtual unwrapping revealed two distinct columns of text that include, in total, 35 lines of Hebrew. Each line has 33 to 34 letters. However, there are only consonants, no vowels. This indicates that the text was written before the ninth century A.D., when Hebrew symbols for vowels were invented, said study co-author Emanuel Tov, a professor emeritus in the department of Bible at Hebrew University of Jerusalem.

Radiocarbon dating places the scroll in the third or fourth century A.D., but studies based on historical handwriting place it at either the first or second century A.D., the researchers said. Regardless, the data suggest that it was written within the first few centuries of the Common Era, they said.

Read more at Discovery News

Earth Wobbles May Have Driven Ancient Humans Out of Africa

 A computer model simulated human density 80,000 years ago, showing the arrival of humans in eastern China and southern Europe as well as migrations out of Africa along vegetated paths in Sinai and the Arabian Peninsula. 
Ancient human migrations out of Africa may have been driven by wobbles in Earth's orbit and tilt that led to dramatic swings in climate, a new study finds.

Modern humans first appeared in Africa about 150,000 to 200,000 years ago. It remains a mystery as to why it then took many millennia for people to disperse across the globe. Recent archaeological and genetic findings suggest thatmigrations of modern humans out of Africa began at least 100,000 years ago, but most humans outside of Africa most likely descended from groups who left the continent more recently — between 40,000 and 70,000 years ago.

Previous research suggested that shifts in climate might help explain why modern human migrations out of Africa happened when they did. For instance, about every 21,000 years, Earth experiences slight changes to its orbit and tilt. These series of wobbles, known as Milankovitch cycles, alter how much sunlight hits different parts of the planet, which in turn influences rainfall levels and the number of people any given region can support.

Now scientists have developed a new computer simulation of Earth to pinpoint how these changes in orbit and solar radiation levels might have affected rainfall, temperature, sea levels, glacial ice, vegetation, carbon dioxide levels and global modern human migration patterns over the past 125,000 years. The researchers noted that this model's predictions agree well with previous findings regarding ancient climates.

The model suggests that modern humans dispersed from Africa in multiple waves across the Arabian Peninsula and the area known as the Levant, the eastern Mediterranean region that includes Israel and Syria. These results closely align with previous estimates garnered from archaeological and fossil data of when modern humans arrived in areas such as the Middle East, Europe, Asia, Australia and the Americas.

"Earth's wobble with a periodicity of 21,000 years played a huge role in our dispersal across the planet and most likely also in our evolution and adaptation," said study lead author Axel Timmermann, a climate researcher at the University of Hawaii at Manoa. "If the climate had been constant over the past 125,000 years, we would have evolved in a very different way."

Specifically, the researchers found that intensified rainfall in northern Africa, the Arabian Peninsula and the Levant would have generated habitable green corridors for modern humans to migrate through the Sahara and Arabian deserts. These corridors would have been open during four distinct times — about 106,000 to 94,000 years ago; 89,000 to 73,000 years ago; 59,000 to 47,000 years ago; and 45,000 to 29,000 years ago — "enabling Homo sapiens to leave northeastern Africa and embark onto their grand journey into Eurasia, Australia and the Americas," Timmermann told Live Science.

The model suggests these migrations were not one-way in nature away from Africa, "as is often portrayed in schematics," Timmermann said. "A green migration corridor between Africa and the eastern Mediterranean meant that Africans were migrating into Eurasia, and Eurasians were moving into Africa. The backflow of Homo sapiens into certain regions and the corresponding backflow of genes may be crucial for understanding who we are, why we are, where we are."

Read more at Discovery News

This Is the Iceman’s Voice

The 5,300-year-old mummy's speech is recreated by scientists.

The "best possible approximation" of Ötzi the Iceman's voice has been reconstructed by scientists who aimed to discover the timbre and color of his Stone Age vowels.

Ötzi broke his silence with a deep male voice after 5,300 years at the EURAC Institute for Mummies and the Iceman in Bolzano.

He spoke Italian -- but just vowels, as you can hear below.

The experiment was presented on Wednesday morning during a major congress to celebrate the 25th anniversary of the mummy's discovery in the Ötztal Alps in South Tyrol.

"We can't say we have reconstructed Ötzi's original voice because we miss some crucial information from the mummy," Rolando Füstös, chief of the ENT department at Bolzano's General Hospital, told Discovery News.

"But with two measurements, the length of both the vocal tract and the vocal cords, we have been able to recreate a fairly reliable approximation of the mummy's voice. This is a starting point for further research," he added.

Füstös and colleagues Francesco Avanzini, ENT specialist and phoniatrician at the city's General Hospital, Piero Cosi, at the Institute of Cognitive Sciences e Technology, National Research Council in Padova, Andrea Sandi, at SINTAC Biomedical Engineering in Padova,and others based their research on the CT scans of the mummy to create a model of his vocal tract.

"The vocal chords are the source of the vocal sound, but the main contribution to it is given by the selective filtering accomplished by the vocal tract configuration," Füstös said.

The researchers had to face several challenges as they worked to reconstruct the structure of the 5,300-year-old mummy's vocal tract.

"We had to deal with Ötzi's position, whose arm is covering his throat," Avanzini told Discovery News. "For our project this is the worst position you can imagine. Moreover, the hyoid bone, or tongue-bone, was party absorbed and dislocated."

With special software, the researchers moved Ötzi's arm, repositioned his skull in the erect position, reconstructed his vertebrae, from the first one (C1) closest to the skull, to the first thoracic vertebra (T1), and reconstructed and repositioned the hyoid bone, which supports the tongue.

They ended up with a complete model of the vocal tract, including the vocal cords and mouth, though they missed important data such as the tension and density of the vocal cords or the thickness and composition of the soft tissues that affect the human voice.

MRI scans would have helped the researchers getting more insights, but the technology could not be used because of the condition of Ötzi's mummified body.

"We had to rely on mathematical models and a software that simulates the way the vocal tract works," Cosi said.

He explained that calculations of vocal area functions applied on the structure of the vocal tract produce a certain vocal sound.

"We ... tried to extract the formants of a synthesized sound 'injected' in the reconstructed vocal tract," Cosi said.

Taking into consideration that Ötzi had a rather large head and slender body, the researchers concluded that his voice likely had a fundamental frequency between 100 Hz and 150 Hz, in line with today's average male.

Read more at Discovery News

Sep 21, 2016

NASA scientists find 'impossible' cloud on Titan -- again

The hazy globe of Titan hangs in front of Saturn and its rings in this natural color view from NASA's Cassini spacecraft.
The puzzling appearance of an ice cloud seemingly out of thin air has prompted NASA scientists to suggest that a different process than previously thought -- possibly similar to one seen over Earth's poles -- could be forming clouds on Saturn's moon Titan.

Located in Titan's stratosphere, the cloud is made of a compound of carbon and nitrogen known as dicyanoacetylene (C4N2), an ingredient in the chemical cocktail that colors the giant moon's hazy, brownish-orange atmosphere.

Decades ago, the infrared instrument on NASA's Voyager 1 spacecraft spotted an ice cloud just like this one on Titan. What has puzzled scientists ever since is this: they detected less than 1 percent of the dicyanoacetylene gas needed for the cloud to condense.

Recent observations from NASA's Cassini mission yielded a similar result. Using Cassini's composite infrared spectrometer, or CIRS -- which can identify the spectral fingerprints of individual chemicals in the atmospheric brew -- researchers found a large, high-altitude cloud made of the same frozen chemical. Yet, just as Voyager found, when it comes to the vapor form of this chemical, CIRS reported that Titan's stratosphere is as dry as a desert.

"The appearance of this ice cloud goes against everything we know about the way clouds form on Titan," said Carrie Anderson, a CIRS co-investigator at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study.

The typical process for forming clouds involves condensation. On Earth, we're familiar with the cycle of evaporation and condensation of water. The same kind of cycle takes place in Titan's troposphere -- the weather-forming layer of Titan's atmosphere -- but with methane instead of water.

A different condensation process takes place in the stratosphere -- the region above the troposphere -- at Titan's north and south winter poles. In this case, layers of clouds condense as the global circulation pattern forces warm gases downward at the pole. The gases then condense as they sink through cooler and cooler layers of the polar stratosphere.

Either way, a cloud forms when the air temperature and pressure are favorable for the vapor to condense into ice. The vapor and the ice reach a balance point -- an equilibrium -- that is determined by the air temperature and pressure. Because of this equilibrium, scientists can calculate the amount of vapor where ice is present.

"For clouds that condense, this equilibrium is mandatory, like the law of gravity," said Robert Samuelson, an emeritus scientist at Goddard and a co-author of the paper.

But the numbers don't compute for the cloud made from dicyanoacetylene. The scientists determined that they would need at least 100 times more vapor to form an ice cloud where the cloud top was observed by Cassini's CIRS.

One explanation suggested early on was that the vapor might be present, but Voyager's instrument wasn't sensitive enough in the critical wavelength range needed to detect it. But when CIRS also didn't find the vapor, Anderson and her Goddard and Caltech colleagues proposed an altogether different explanation. Instead of the cloud forming by condensation, they think the C4N2 ice forms because of reactions taking place on other kinds of ice particles. The researchers call this "solid-state chemistry," because the reactions involve the ice, or solid, form of the chemical.

The first step in the proposed process is the formation of ice particles made from the related chemical cyanoacetylene (HC3N). As these tiny bits of ice move downward through Titan's stratosphere, they get coated by hydrogen cyanide (HCN). At this stage, the ice particle has a core and a shell composed of two different chemicals. Occasionally, a photon of ultraviolet light tunnels into the frozen shell and triggers a series of chemical reactions in the ice. These reactions could begin either in the core or within the shell. Both pathways can yield dicyanoacteylene ice and hydrogen as products.

The researchers got the idea of solid-state chemistry from the formation of clouds involved in ozone depletion high above Earth's poles. Although Earth's stratosphere has scant moisture, wispy nacreous clouds (also called polar stratospheric clouds) can form under the right conditions. In these clouds, chlorine-bearing chemicals that have entered the atmosphere as pollution stick to crystals of water ice, resulting in chemical reactions that release ozone-destroying chlorine molecules.

"It's very exciting to think that we may have found examples of similar solid-state chemical processes on both Titan and Earth," said Anderson.

The researchers suggest that, on Titan, the reactions occur inside the ice particles, sequestered from the atmosphere. In that case, dicyanoacetylene ice wouldn't make direct contact with the atmosphere, which would explain why the ice and the vapor forms are not in the expected equilibrium.

"The compositions of the polar stratospheres of Titan and Earth could not differ more," said Michael Flasar, CIRS principal investigator at Goddard. "It is amazing to see how well the underlying physics of both atmospheres has led to analogous cloud chemistry."

Read more at Science Daily

Iceman Killed After Sneak Attack From Behind

The murder of Ötzi the Iceman was likely committed at the end of a harsh personal conflict, researchers at a three-day mummy congress in Bolzano, north Italy, concluded.

Launched to celebrate the 25th anniversary of the Iceman's discovery in the Ötztal Alps in South Tyrol, the meeting presented new insights on the 5,300-year-old mummy, including a profile carried out with latest criminological methods.

According to this analysis, Ötzi did not flee up the mountain to escape his enemies. On the contrary, he was just resting and taken by surprise by his attacker(s) who shot the arrow from behind and at a distance.

The theory is the latest of a series of speculations over Ötzi's death. No corpse has been more thoroughly investigated.

"In terms of his significance for science, Ötzi is not simply an isolated mummy discovery. He could be seen as a typical European from earlier times and is precious for this reason alone," Albert Zink, director at the EURAC Institute for Mummies and the Iceman in Bolzano, said.

Scientists have learned a lot about Ötzi in the past 25 years. Among many things, they discovered that he had brown eyes, was about 5 foot, 3 inches tall and weighed 110 pounds.

He died at around 45, was arthritic, lactose intolerant, suffered from atherosclerosis and had cavities, worn teeth and periodontal diseases. He was also infected with Helicobacter pylori, the pathogen that gives people gastritis and stomach ulcers. Genetic tests revealed he belonged to the European haplogroup K and was probably infertile.

"What concerns us most these days is to know who the Iceman was, what role he played in society and what happened to him in the last days of his life," said Angelika Fleckinger, director of the South Tyrol Museum of Archaeology where the mummy is housed in refrigerated cell with an observation window.

To help solve the coldest of cold cases, Fleckinger asked chief inspector Alexander Horn, at the Criminal Investigation Department in Muinch, Germany, to probe the "Ötzi Murder Case" using behavioral investigative analysis.

Horn began his inquire by examining the crime scene as it appeared on Sept. 19, 1991 when a human corpse was found near a melting glacier in the Ötztal Alps.

The corpse was lying with the chest against a flat rock. Only the back of the head, the bare shoulders and part of the back emerged from the ice and meltwater.

He reconstructed the crime scene with the objects that were found in the vicinity and added to his analysis the data from the forensic medical examinations.

"I actually had more information with Ötzi than in certain modern crime cases," Horn said.

The results of his investigation were that Ötzi did not feel threatened shortly before his murder.

"He wasn't escaping, but resting. He had placed down his gear and enjoyed a hearty meal," Horn said.

Indeed, previous research established that Otzi had eaten Alpine ibex -- a wild goat --- just 30 minutes to 2 hours before his death.

"When you run away, you do not just sit and stop to eat a big meal," Horn told Discovery News.

He noted however that a few days prior to the murder, the Iceman had incurred an injury to his right hand.

Read more at Discovery News

Earliest Signs Of Animal Life May Be From Microbes

Shown is a Dickinsonia Costa fossil from the Ediacaran period.
Evidence suggests that microbes existed on Earth as far back as 3.7 billion years ago, a billion years after the planet formed. Animal remains, however, don't appear in the fossil record until 600 million years ago during the Ediacaran period, though there are indirect signs that animal life may have gotten started much earlier.

Scientists are attempting to put a date on the earliest lifeforms in the kingdom of Animalia, but without an actual cast of a body they've had to rely on the credibility of "trace" fossils to show signs of an animal's presence in the form of footprints, scratches, feeding marks or burrows. Some scientists claim to have found trace fossils made by animals more than a billion years ago, raising controversy over whether animal life could have existed this early. There are also trace fossils from the Ediacaran Period and soft bodied animals were known to exist during this period, so understanding the tracks they made is important for studying the early animals.

Giulio Mariotti, an oceanographer from Louisiana State University, and colleagues, examined supposed animal trace fossils from the Ediacaran Period, and found that it is possible that some of them could be microbial in origin. The results, which were recently published in a paper entitled "Microbial Origin of Early Animal Trace Fossils" in the Journal of Sedimentary Research, raise questions about the reliability of trace fossils as evidence for early animal life.

The research was funded by the Exobiology & Evolutionary Biology element of the NASA Astrobiology Program.

Many of the Ediacaran animal trace fossils are found within "wrinkle" structures, small ridges and pits interpreted as evidence of ancient microbial mats. Microbial mats are comprised of layers of microorganisms, and fossilized mats are among the earliest clear signs of microbial life. Microbial mats were widespread in the Precambrian, the period before animal life became extremely common and diverse. But the mats were no longer able to flourish in certain marine areas when grazing animals became more abundant because the animals destroyed the structures.

Mariotti and colleagues devised an experiment to try to create trails of grooves and pits similar to the trace fossils. They did this by moving microbial aggregates across sand at the bottom of a tank of water by creating waves in the water. Microbial aggregates are small cluster of microbes which are larger than sand but less dense. This low density enables them to be moved across the sand at the bottom of the tank by very low energy waves.

The use of low energy waves is important as waves with higher energy would also erase the trail left in the sand. A wide variety of trails were produced by the aggregates depending on the wave conditions and the size of the aggregate. Some of these trails were strikingly similar to those that are currently deemed to be Ediacaran trace fossils, meaning that it is possible that some trace fossils are actually not fossils at all and are instead caused by the movement of microbial aggregates.

However, not only did the trails produced by the wave tank experiment replicate the supposed animal traces, the experiment also produced a wrinkle structure in the sand. The aggregates caused the wrinkle structure when they were smaller than the amplitude of the wave, where as the trails were formed when the aggregates were larger than the wave amplitude.

This research does not necessarily mean that all early trace fossils were caused by microbial aggregates, however it does put forward a plausible alternative explanation for those that occur alongside wrinkle structures. Therefore, possible trace fossils from the Ediacaran period or earlier should be looked upon with skepticism until it is possible to rule out microbial aggregates as a cause of the grooves and pits in the rock.

Trails caused by aggregates and those caused by animals can be distinguished in some cases if certain distinctive features exist. For example an animal trail can be "self avoiding," meaning that the animal didn't cross back over its own trail as it had already searched for food in that location. Unfortunately, most of the more distinctive signs of animal activity are rare until the very end of the Ediacaran period.

Read more at Discovery News

Grand Finale: Cassini Preps For Last Days at Saturn

Cassini snapped this backlit view of Saturn in July 2013. Next year, Cassini will end its mission with 22 passes through the narrow gap between the planet and its rings.
Before the Cassini project bids farewell to one of NASA's most successful probes, the spacecraft will make a daring jump across Saturn's rings, setting up 22 passes through the narrow, unexplored gap between the planet and its closest ring.

"It really and truly for Cassini is a brand new mission," said project scientist Linda Spilker, with NASA's Jet Propulsion Laboratory in Pasadena, Calif.

The Cassini spacecraft left Earth on Oct. 5, 1997, and set sail for Saturn, the second-largest planet in the solar system after Jupiter. Seven years later, after traveling nearly 2.2 billion miles, Cassini put itself into orbit around the ringed beauty.

Data collected by Cassini and radioed back to Earth will keep scientists busy for decades, but the spacecraft's days are numbered: Next September, Cassini will fly itself into Saturn and incinerate.

The suicidal plunge, scheduled for Sept. 15, eliminates the chance that one of Saturn's potentially habitable moons becomes a new home to an uber-hearty colony of hitchhiking Earth microbes, still alive on a crashing Cassini spacecraft after decades in deep space.

Cassini will fly into Saturn using its steering jets, leaving little to chance.

During the 22 final orbits, and particularly during Cassini's closest approach, scientists want to collect data that will let them figure out how much material is in Saturn's rings. That, in turn, would resolve a long-standing mystery about if the rings are as old as Saturn, or a more modern-day phenomenon.

They also want to measure the length of a Saturn day, learn more about planet's magnetic field, map its internal structure and take close-up pictures of the planet's powerful aurora. Cassini even could discover a moon-like mass inside Saturn, which could explain some mysterious wave motions detected in the C-ring, Spilker said.

"The rings are actually a very sensitive detector of what's going on inside Saturn," Spilker said last week during a webcast meeting of the National Academy of Sciences Committee on Astrobiology and Planetary Science.

"We saw a series of waves in the rings and they were damping in the wrong direction. Usually, when there's resonance with a moon, the waves damp out toward the moon. These particular waves were damping in toward Saturn. It looks almost like you have a mass or like tiny moon inside Saturn itself," Spilker said.

The journey in toward Saturn promises suspense. Scientists aren't exactly sure how many particles Cassini might encounter as it flies closer to Saturn. To be on the safe side, Cassini will makes its first few close passes using its big communications antenna as a shield. If too many particles hit the antenna, Cassini can fly that way the rest of the mission, Spilker said.

"In just a little over an hour, you go from north pole to south pole, through the ring gap. You're going incredibly fast -- 75,000 mph. That's why even a particle a millimeter or so in size hitting in the wrong place wouldn't be so good for Cassini," Spilker said.

Read more at Discovery News

Sep 20, 2016

New ways to track stars eaten by black holes

Illustration shows a glowing stream of material from a star as it is being devoured by a supermassive black hole in a tidal disruption flare.
Research led by Johns Hopkins University astrophysicists using information from a NASA space telescope breaks new ground in ways to observe a star swallowed by a black hole, promising to help paint a clearer picture of this cosmic phenomenon.

The results, published online in the Astrophysical Journal, are based on two methods that are new in the study of this sort of star destruction: the first infrared observations, and using galaxy dust to reflect, or "echo," the electromagnetic energy burst of a star being devoured by a black hole, called a "tidal disruption flare."

The approach, which in this case allowed scientists to measure flare energy more precisely than had been done before, offers fresh ways to understand "tidal disruptions." The phenomena were first raised hypothetically in the 1970s, and only studied closely since 2005, although the first possible examples were claimed several years earlier, said Julian H. Krolik, a professor in the Department of Physics and Astronomy at Johns Hopkins and one of four authors of the paper.

"What happens to the mass of the star once it's torn apart?" Krolik said. "Is it heated up? Does it go quickly into the black hole? Does it swirl around for a while? These are the questions" that this approach could help to answer, Krolik said. He co-wrote the paper with lead author Sjoert van Velzen, a Hubble Fellow at Johns Hopkins; Alexander J. Mendez, who was a post-doctoral fellow at the university when the work was done; and Varoujan Gorjian, an astronomer at NASA's Jet Propulsion Laboratory, a division of Caltech.

The four scientists used images that had been compiled by the Wide-field Infrared Survey Explorer (WISE) telescope, which NASA launched into Earth's orbit in 2009. The study considered five instances in which a star had apparently moved close enough to the gravitational pull of a black hole to be drawn in, have its mass stretched and compressed into long strands, and be devoured -- a "tidal disruption."

The events -- each of which can unfold over a period of months -- occurred in five galaxies, the closest of which is 840 million light years from Earth.

In each case, the destruction of the star set off a burst of energy, or flare. Krolik said it's been generally expected that the flares would emit most of their energy in low-energy X-rays or extreme ultraviolet light, but these bands are very difficult to observe. For that reason, most observations have been in visible or near ultraviolet light.

This research relied on indirect observation of the flare. The scientists compiled information gathered by the telescope on the temperature of the dust roughly 2 trillion miles away from where the stars were destroyed by the black holes. The intense radiation of the flare first burns away the dust, cleaning out a sphere with a radius of about 2 trillion miles. At the edge of this sphere, dust absorbs and then re-emits the heat from the tidal disruption flare, creating a thermal "echo" picked up by the telescope.

"The dust echo thus provides a unique means to measure total energy that is emitted during the stars' destruction," van Velzen said. "A measurement of the total energy is very important; without this we have an incomplete picture of what happens during a stellar tidal disruption. For example, the total energy is needed to understand if the star got fully destroyed, or if the black hole only nibbled a piece of the star."

The study refined the understanding of the energy produced by these flares. The flare energy was measured at 10 times more than previous observations saw, but one tenth the energy predicted in the earliest, most simple models.

That point is part of an emerging understanding of a cosmic event that has only been observed a few dozen times. The picture is bound to become clearer as researchers develop new methods, including the first infrared observations.

Read more at Science Daily

Body ornamentation among Neanderthals: Dig in France confirmed as Neaderthal remains

Châtelperronian body ornaments and bone points from the Grotte du Renne in Arcy-sur-Cure.
Researchers from the University of York have helped to solve an archaeological dispute -- confirming that Neandertals were responsible for producing tools and artefacts previously argued by some to be exclusively in the realm of modern human cognitive abilities.

Using ancient protein analysis, the team took part in an international research project to confirm the disputed origins of bone fragments in Châtelperron, France.

Led by the Max Planck Institute (MPI) for Evolutionary Anthropology in Germany, researchers set out to settle the debate as to whether hominin remains in the Grotte du Renne, an archaeological site in Arcy-sur-Cure, France, date to Neandertal ancestry or whether they indicate the first evidence of modern humans in Europe.

Known as the Châtelperronian industry due to numerous artefacts and body ornaments found in this area of central France and northern Spain, the area is critical to the debate regarding the extent of Neandertal cognition, their replacement by modern humans and eventual extinction.

Despite intense research, the exact biological nature of the Châtelperronian people has previously been disputed, with no direct molecular data for a Neandertal association obtained.

However, using peptide mass fingerprinting for rapid, low-cost detection of hominin remains, the team identified 28 additional hominin specimens among previously unidentifiable bone fragments at the Grotte du Renne.

It is thought the bone fragments most likely represent the remains of a single, immature, breastfed individual, with radiocarbon dating being fully consistent with its direct association to Neandertal ancestry.

Professor Matthew Collins, Director of BioArCh at the University of York's Department of Archaeology and co-author of the paper, said: "For the first time, this research demonstrates the effectiveness of recent developments in ancient protein amino acid analysis and radiocarbon dating to discriminate between Late Pleistocene clades. To identify proteins related to specific developmental stages of bone formation highlights one of the main strengths of this new analysis, especially in a multi-disciplinary context.

"These methods open up new avenues of research throughout Late Pleistocene contexts in which hominin remains are scarce and where the biological nature of remains is unclear due to ancient DNA not being preserved. This represents a significant advance in palaeoproteomic phylogenetics and is of direct relevance to our understanding of hominin evolution."

Frido Welker, PhD student at the Max Planck Institute for Evolutionary Anthropology and lead author, said: "To differentiate between modern humans, Neandertals and Denisovans on the basis of ancient protein research provides really exciting opportunities for future research into the origins of our and their evolutionary history."

Read more at Science Daily

Rare Marine Life Found in Mysterious Sea 'Mountains'

Shown is the launch of the Pisces IV submersible to dive on the McCall seamount.
Scientists recently traveled thousands of miles below the ocean's surface to explore underwater mountain ranges of cone-shaped dormant and active volcanoes with peaks rising 9,843 feet (3,000 meters) above the seafloor off the coast of Hawaii.

Living along these seamounts, Conservation International researchers spied enough quirky and unusual marine life to fill a Dr. Seuss book.

Their findings provide a window into some of the most mysterious spots in the ocean: Tens of thousands of seamounts extend across the world's oceans, but many have never been explored, and scientists are only just beginning to discover the complexity of the ecosystems they support, one of the expedition scientists told the Conservation International (CI) blog Human Nature.

Using twin submersibles named Pisces IV and Pisces V, equipped with multiple cameras, scientists led by CI dove to three seamounts: Cook seamount on Sept. 6, McCall seamount on Sept. 7, and Lo?'ihi seamount on Sept. 8. The Cook and McCall seamounts are part of a region known as the Geologist Seamounts — a ring of ancient volcanoes estimated to be about 80 million years old, according to a CI statement emailed to Live Science.

In the dark, cold and high-pressure ocean depths, the researchers found that each seamount had its own distinct and diverse ecosystem, they described Sept. 16 in Human Nature. From the submersibles, scientists observed rare and unusual creatures, such as a floppy-"eared" dumbo octopus, kitefin sharks, cutthroat eels and several unusual species of coral that could be new to science, including a colorful variety that the researchers nicknamed "purple haze."

In a video captured by the Pisces V submersible on Sept. 6, a dumbo octopus gracefully glides above the seafloor at the Cook seamount, its body color subtly shifting as it swims. One of the observing scientists can be heard in the video remarking that the octopus appeared to be molting, since folds of what looked like shedding skin were visible on its body.

A Pacific sleeper shark estimated to measure between 7 and 8 feet (2.1 and 2.4 m) in length appeared in another video filmed by Pisces V at the Lo?'ihi seamount on Sept. 8. As the shark slowly passed in front of the camera, it prompted excited exclamations of "Come see this!" and "Oh, wow!" from scientists watching the animal through the cameras.

Expeditions like this one will improve scientists' understanding of the role that seamounts play in ocean ecology, and could inform future policy decisions affecting seamount conservation, CI officials told Live Science in the email.

From Discovery News

Water Bear Dries to a Crisp Then Comes Back to Life

Small aquatic animals known as water bears can survive near complete desiccation and other extreme states, and now researchers have identified a unique protein that makes such feats possible.

Since the protein, reported in the journal Nature Communications, protects human cells from damage, it could lead to new medical treatments. At the very least, its discovery helps explain how water bears, also known as tardigrades, are among the world's most durable creatures.

Watch how this water bear dries to a crisp before before being brought back to life with a drop of water:

"The dehydrated tardigrades withstand a wide range of physical extremes that normally disallow survival of most organisms, such as extreme temperatures, high pressure, immersion in organic solvent, exposure to high dose irradiation and even direct exposure to open space," wrote lead author Takuma Hashimoto of The University of Tokyo and colleagues.

"Space" refers to the vacuum of outer space, so even NASA is interested in water bears because they suggest that life could be possible in the extreme conditions of other planets.

To determine why water bears are near indestructible, Hashimoto and his team conducted a genetic analysis on one of the most stress tolerant tardigrade species: Ramazzottius varieornatus. It is the toughest of the tough in the animal kingdom.

The researchers identified a unique water bear protein that suppresses X-ray induced damage by about 40 percent in human cultured cells. It also made human cells more tolerant of radiation. Those findings open up a whole new line of research on the water bears' proteins , which could prove to be very beneficial to humans.

The research also presents the first ever genome sequence for an "extremotolerant" tardigrade. As that descriptor indicates, these animals can again survive almost anything.

It is especially impressive that they can live through being dried to a crisp. Novelty aquarium pets known as Sea Monkeys, which are actually brine shrimp, have a similar ability. When desiccated, these brine shrimp go into a different state of being called cryptobiosis or anhydrobiosis. It's a condition of apparent lifelessness that allows survival, even when the temporary water pools in which the brine shrimp live in the wild dry up.

Microscopic water bears live in almost every place on Earth. They can be found in leaf litter and soil, beaches, dunes, fresh and salt water, and even in the slimy film of water that collects on lichens and mosses.

A water bear walking on moss:

Water bears can also survive under conditions of very high pressure. For example, they have no problem withstanding six times the pressure of the deepest part of the ocean. They can be placed in boiling alcohol and come out just fine. Being frozen in a block of ice poses no problem for water bears. They can alsowithstand levels of X-ray radiation that are 1,000 times the lethal human dose.

At the root of many of these abilities is the water bears' ability to survive oxidative stress. This is a disturbance to the balance between the production of reactive oxygen molecules (free radicals) and antioxidant defenses.

Learning more about how they avoid extreme stress could lead to important medical discoveries. The newfound protein is just a start.

From Discovery News

Sep 19, 2016

Shedding light on Pluto’s glaciers

The polar cap of "Sputnik Planum," in false colors, is surrounded by mountains which have been eroded and shaped by the glacial activity. The dark areas are covered by organic materials produced by the photolysis of methane by solar ultraviolet light.
What is the origin of the large heart-shaped nitrogen glacier revealed in 2015 on Pluto by the New Horizons spacecraft? Two researchers from the Laboratoire de météorologie dynamique (CNRS/École polytechnique/UPMC/ENS Paris) show that Pluto's peculiar insolation and atmosphere favor nitrogen condensation near the equator, in the lower altitude regions, leading to an accumulation of ice at the bottom of Sputnik Planum, a vast topographic basin. Through their simulations, they also explain the surface distribution and atmospheric abundance of other types of volatiles observed on Pluto. These results are published in Nature on September 19, 2016.

Pluto is a paradise for glaciologists. Among the types of ice covering its surface, nitrogen is the most volatile: when it sublimes (at -235 ° C), it forms a thin atmosphere in equilibrium with the ice reservoir at the surface. One of the most unexpected observations from New Horizons, which flew by Pluto in July 2015, showed that this reservoir of solid nitrogen is extremely massive, and mostly contained in "Sputnik Planum," a topographic basin located within the tropics of Pluto. Methane frost also appears all over the northern hemisphere, except at the equator, while carbon monoxide ice in smaller amounts was only detected in Sputnik Planum.

Until now, the distribution of Pluto's ice remained unexplained. To better understand the physical processes at work on Pluto, the researchers developed a numerical thermal model of the surface of the dwarf planet able to simulate the nitrogen, methane and carbon monoxide cycles over thousands of years, and compared the results with the observations made by the New Horizons spacecraft. Their model shows that the solid-gas equilibrium of nitrogen is responsible for trapping the ice in Sputnik Planum. At the bottom of the basin, the pressure of the atmosphere -- and therefore of gaseous nitrogen -- increases, and the corresponding frost temperature is higher than outside the basin, which allows the nitrogen to preferably condense into ice. Simulations show that the nitrogen ice inevitably accumulates in the basin, thus forming a permanent nitrogen reservoir, as observed by New Horizons.

The numerical simulations also describe the methane and carbon monoxide cycles. Because of its volatility similar to that of nitrogen, carbon monoxide ice is entirely sequestered with nitrogen in the basin, in keeping with the New Horizons measurements. Regarding the methane ice, its lower volatility at the temperatures prevailing on Pluto allows it to exist elsewhere than in the Sputnik Planum glacier. The model shows that pure methane ice seasonally covers both hemispheres, in agreement with New Horizons data.

Read more at Science Daily

Bird brain? Pigeons have quite a way with words

Dr Damian Scarf.
Pigeons can learn to distinguish real words from non-words by visually processing their letter combinations, surprising new research from the University of Otago in New Zealand and Ruhr University in Germany shows.

The researchers found that pigeons' performance was on a par with that previously reported in baboons for this type of complex task. Their study, which is published in the journal Proceedings of the National Academy of Sciences (PNAS), is the first to identify a non-primate species as having "orthographic" abilities.

In the experiment, pigeons were trained to peck four-letter English words as they came up on a screen, or to instead peck a symbol when a four-letter non-word, such as "URSP" was displayed. The researchers added words one by one with the four pigeons in the study eventually building vocabularies ranging from 26 to 58 words and over 8000 non-words.

To check whether the pigeons were learning to distinguish words from non-words rather than merely memorising them, the researchers introduced words the birds had never seen before.

The pigeons correctly identified the new words as words at a rate significantly above chance.

According to the study's first author, Dr Damian Scarf of the University of Otago's Department of Psychology, they performed this feat by tracking the statistical likelihood that "bigrams," letter pairs such as "EN" and "AL," were more likely associated with words or non-words.

Professor Onur Güntürkün, one of the co-investigators from of Ruhr University's Department of Biopsychology, says "that pigeons -- separated by 300 million years of evolution from humans and having vastly different brain architectures -- show such a skill as orthographic processing is astonishing."

Read more at Science Daily

Reptilian anachronism: American alligator older than we thought

"If we could step back in time 8 million years, you'd basically see the same animal crawling around then as you would see today in the Southeast. Even 30 million years ago, they didn't look much different," said Evan Whiting, a former UF undergraduate and the lead author of two studies.
From climate to the peninsula’s very shape, not much in Florida has stayed the same over the last 8 million years.

Except, it turns out, alligators.

While many of today’s top predators are more recent products of evolution, the modern American alligator is a reptile quite literally from another time. New University of Florida research shows these prehistoric-looking creatures have remained virtually untouched by major evolutionary change for at least 8 million years, and may be up to 6 million years older than previously thought. Besides some sharks and a handful of others, very few living vertebrate species have such a long duration in the fossil record with so little change.

“If we could step back in time 8 million years, you’d basically see the same animal crawling around then as you would see today in the Southeast. Even 30 million years ago, they didn’t look much different,” said Evan Whiting, a former UF undergraduate and the lead author of two studies published during summer 2016 in the Journal of Herpetology and Palaeogeography, Palaeoclimatology, Palaeoecology that document the alligator’s evolution – or lack thereof. "We were surprised to find fossil alligators from this deep in time that actually belong to the living species, rather than an extinct one."

Whiting, now a doctoral student at the University of Minnesota, describes the alligator as a survivor, withstanding sea-level fluctuations and extreme changes in climate that would have caused some less-adaptive animals to rapidly change or go extinct. Whiting also discovered that early American alligators likely shared the Florida coastline with a 25-foot now-extinct giant crocodile.

In modern times, however, he said alligators face a threat that could hinder the scaly reptiles’ ability to thrive like nothing in their past — humans.

Despite their resilience and adaptability, alligators were nearly hunted to extinction in the early 20th century. The Endangered Species Act has significantly improved the number of alligators in the wild, but there are still ongoing encounters between humans and alligators that are not desirable for either species and, in many places, alligator habitats are being destroyed or humans are moving into them, Whiting said.

“The same traits that allowed alligators to remain virtually the same through numerous environmental changes over millions of years can become a bit of a problem when they try to adapt to humans,” Whiting said. “Their adaptive nature is why we have alligators in swimming pools or crawling around golf courses.”

Whiting hopes his research findings serve to inform the public that the alligator was here first, and we should act accordingly by preserving the animal’s wild populations and its environment. By providing a more complete evolutionary history of the alligator, his research provides the groundwork for conserving habitats where alligators have dominated for millions of years.

“If we know from the fossil record that alligators have thrived in certain types of habitats since deep in time, we know which habitats to focus conservation and management efforts on today,” Whiting said.

Study authors began re-thinking the alligator’s evolutionary history after Whiting examined an ancient alligator skull, originally thought to be an extinct species, unearthed in Marion County, Florida, and found it to be virtually identical to the iconic modern species. He compared the ancient skull with dozens of other fossils and modern skeletons to look at the whole genus and trace major changes, or the lack thereof, in alligator morphology.

Whiting also studied the carbon and oxygen compositions of the teeth of both ancient alligators and the 20- to 25-foot extinct crocodile Gavialosuchus americanus that once dominated the Florida coastline and died out about 5 million years ago for unknown reasons. The presence of alligator and Gavialosuchus fossils at several localities in north Florida suggest the two species may have coexisted in places near the coast, he said.

Analysis of the teeth suggests, however, that the giant croc was a marine reptile, which sought its prey in ocean waters, while alligators tended to hunt in freshwater and on land. That doesn’t mean alligators weren’t occasionally eaten by the monster crocs, though.

“Evan’s research shows alligators didn’t evolve in a vacuum with no other crocodilians around,” said co-author David Steadman, ornithology curator at the Florida Museum of Natural History at the University of Florida. “The gators we see today do not really compete with anything, but millions of years ago it was not only competing with another type of crocodilian, it was competing with a much larger one.”

Steadman said the presence of the ancient crocodile in Florida may have helped keep the alligators in freshwater habitats, though it appears alligators have always been most comfortable in freshwater.

Read more at Science Daily

Rare, Complete Mammoth Skull Found in Channel Islands

Researchers have hit paleontology pay dirt with the unearthing of a well-preserved mammoth skull fossil on Santa Rosa Island, in Southern California's Channel Islands.

"I have seen a lot of mammoth skulls and this is one of the best preserved I have ever seen," said a member of the team that made the find, The Mammoth Site paleontologist Justin Wilkins, in a statement.

The fossil, Wilkins added, "is extremely rare and of high scientific importance. It appears to have been on the Channel Islands at the nearly same time as humans."

Scientists with the U.S. Geological Survey (USGS) have dated the skull to about 13,000 years ago. The timing makes the find all the more tantalizing, because it is the same timeline assigned to the so called "Arlington Man," a 13,000-year-old human skeleton also found on Santa Rosa.

Among the questions yet to be answered involves the species of mammoth represented by the skull. To date, the researchers say it appears too large to have come from a pygmy mammoth and too small to have come from a Columbian mammoth.

The scientists say a closer examination of the fossil teeth, a process not yet complete, should be able to tell them whether the animal was a pygmy or a Columbian mammoth. (The chance of its being a transitional mammoth species was called "less likely" in a release.) It will also help them peg the animal's age at the time of death to within two years.

Mammoths first appeared in North America roughly 2 million years ago. The Columbian species, about 14 feet tall, reached the Channel Islands in two migrations during the last two ice ages, when the land was more accessible due to lower sea levels, scientists think. Pygmy mammoths of only about 6 feet tall descended from those Columbian travelers and were endemic to the islands.

According to USGS geologist Dan Muhs, who in 2013 found an 80,000-year-old pygmy mammoth tusk on Santa Rosa, the new find helps solidify that story on the island.

"The discovery of this mammoth skull increases the probability that there were at least two migrations of Columbian mammoths to the island: during the most recent ice age 10 to 30,000 years ago, as well as the previous glacial period that occurred about 150,000 years ago," said Muhs.

Read more at Discovery News

Sep 18, 2016

New tech promises to boost electric vehicle efficiency, range

The new inverter, made using silicon carbide components.
Researchers at North Carolina State University have developed a new type of inverter device with greater efficiency in a smaller, lighter package -- which should improve the fuel-efficiency and range of hybrid and electric vehicles.

Electric and hybrid vehicles rely on inverters to ensure that enough electricity is conveyed from the battery to the motor during vehicle operation. Conventional inverters rely on components made of the semiconductor material silicon.

Now researchers at the Future Renewable Electric Energy Distribution and Management (FREEDM) Systems Center at NC State have developed an inverter using off-the-shelf components made of the wide-bandgap semiconductor material silicon carbide (SiC) -- with promising results.

"Our silicon carbide prototype inverter can transfer 99 percent of energy to the motor, which is about two percent higher than the best silicon-based inverters under normal conditions," says Iqbal Husain, ABB Distinguished Professor of Electrical and Computer Engineering at NC State and director of the FREEDM Center.

"Equally important, the silicon carbide inverters can be smaller and lighter than their silicon counterparts, further improving the range of electric vehicles," says Husain, who co-authored two papers related to the work. "And new advances we've made in inverter components should allow us to make the inverters even smaller still."

Range is an important issue because so-called "range anxiety" is a major factor limiting public acceptance of electric vehicles. People are afraid they won't be able to travel very far or that they'll get stuck on the side of the road.

The new SiC-based inverter is able to convey 12.1 kilowatts of power per liter (kW/L) -- close to the U.S. Department of Energy's goal of developing inverters that can achieve 13.4 kW/L by 2020. By way of comparison, a 2010 electric vehicle could achieve only 4.1 kW/L.

"Conventional, silicon-based inverters have likely improved since 2010, but they're still nowhere near 12.1 kW/L," Husain says.

The power density of new SiC materials allows engineers to make the inverters -- and their components, such as capacitors and inductors -- smaller and lighter.

"But, frankly, we are pretty sure that we can improve further on the energy density that we've shown with this prototype," Husain says.

That's because the new inverter prototype was made using off-the-shelf SiC components -- and FREEDM researchers have recently made new, ultra-high density SiC power components that they expect will allow them to get closer to DOE's 13.4 kW/L target once it's incorporated into next generation inverters.

What's more, the design of the new power component is more effective at dissipating heat than previous versions. This could allow the creation of air-cooled inverters, eliminating the need for bulky (and heavy) liquid cooling systems.

"We predict that we'll be able to make an air-cooled inverter up to 35 kW using the new module, for use in motorcycles, hybrid vehicles and scooters," Husain says. "And it will boost energy density even when used with liquid cooling systems in more powerful vehicles."

The current SiC inverter prototype was designed to go up to 55 kW -- the sort of power you'd see in a hybrid vehicle. The researchers are now in the process of scaling it up to 100 kW -- akin to what you'd see in a fully electric vehicle -- using off-the-shelf components. And they're also in the process of developing inverters that make use of the new, ultra-high density SiC power component that they developed on-site.

A paper on the new inverter, "Design Methodology for a Planarized High Power Density EV/HEV Traction Drive using SiC Power Modules," will be presented at the IEEE Energy Conversion Congress and Exposition (ECCE), being held Sept. 18-22 in Milwaukee. Lead author of the paper is Dhrubo Rahman, a Ph.D. student at NC State. The paper was co-authored by Adam Morgan, Yang Xu and Rui Gao, who are Ph.D. students at NC State; Wensong Yu and Douglas Hopkins, research professors in NC State's Department of Electrical and Computer Engineering; and Husain.

A paper on the new, ultra-high density SiC power component, "Development of an Ultra-high Density Power Chip on Bus Module," will also be presented at ECCE. Lead author of the paper is Yang Xu. The paper was co-authored by Yu, Husain and Hopkins, as well as by Harvey West, a research professor in NC State's Edward P. Fitts Department of Industrial and Systems Engineering.

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New spectroscopic technique may help zero in on Martian life

Mars’ Valles Marineris canyon, pictured, spans as much as 600 kilometers across and delves as much as 8 kilometers deep. The image was created from over 100 images of Mars taken by Viking Orbiters in the 1970s.
In 2020, NASA plans to launch a new Mars rover that will be tasked with probing a region of the planet scientists believe could hold remnants of ancient microbial life. The rover will collect samples of rocks and soil, and store them on the Martian surface; the samples would be returned to Earth sometime in the distant future so that scientists can meticulously analyze the samples for signs of present or former extraterrestrial life.

Now, as reported in the journal Carbon, MIT scientists have developed a technique that will help the rover quickly and non-invasively identify sediments that are relatively unaltered, and that maintain much of their original composition. Such "pristine" samples give scientists the best chance for identifying signs of former life, if they exist, as opposed to rocks whose histories have been wiped clean by geological processes such as excessive heating or radiation damage.

Spectroscopy on Mars

The team's technique centers on a new way to interpret the results of Raman spectroscopy, a common, non-destructive process that geologists use to identify the chemical composition of ancient rocks. Among its suite of scientific tools, the 2020 Mars rover includes SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals), an instrument that will acquire Raman spectra from samples on or just below the Martian surface. SHERLOC will be pivotal in determining whether life ever existed on Mars.

Raman spectroscopy measures the minute vibrations of atoms within the molecules of a given material. For example, graphite is composed of a very orderly arrangement of carbon atoms. The bonds between these carbon atoms vibrate naturally, at a frequency that scientists can measure when they focus a laser beam on graphite's surface.

As atoms and molecules vibrate at various frequencies depending on what they are bound to, Raman spectroscopy enables scientists to identify key aspects of a sample's chemical composition. More importantly, the technique can determine whether a sample contains carbonaceous matter -- a first clue that the sample may also harbor signs of life.

But Roger Summons, professor of earth, atmospheric, and planetary sciences at MIT, says the chemical picture that scientists have so far been able to discern using Raman spectroscopy has been somewhat fuzzy. For example, a Raman spectrum acquired from a piece of coal on Earth might look very similar to that of an organic particle in a meteorite that was originally made in space.

"We don't have a way to confidently distinguish between organic matter that was once biological in origin, versus organic matter that came from some other chemical process," Summons says.

However, Nicola Ferralis, a research scientist in MIT's Department of Materials Science and Engineering, discovered hidden features in Raman spectra that can give a more informed picture of a sample's chemical makeup. Specifically, the researchers were able to estimate the ratio of hydrogen to carbon atoms from the substructure of the peaks in Raman spectra. This is important because the more heating any rock has experienced, the more the organic matter becomes altered, specifically through the loss of hydrogen in the form of methane.

The improved technique enables scientists to more accurately interpret the meaning of existing Raman spectra, and quickly evaluate the ratio of hydrogen to carbon -- thereby identifying the most pristine, ancient samples of rocks for further study. Summons says this may also help scientists and engineers working with the SHERLOC instrument on the 2020 Mars rover to zero in on ideal Martian samples.

"This may help in deciding what samples the 2020 rover will archive," Summons says. "It will be looking for organic matter preserved in sediments, and this will allow a more informed selection of samples for potential return to Earth."

Seeing the hidden peaks

A Raman spectrum represents the vibration of a molecule or atom, in response to laser light. A typical spectrum for a sample containing organic matter appears as a curve with two main peaks -- one wide peak, and a sharper, more narrow peak. Researchers have previously labeled the wide peak as the D (disordered) band, as vibrations in this region correlate with carbon atoms that have a disordered makeup, bound to any number of other elements. The second, more narrow peak is the G (graphite) band, which is typically related to more ordered arrangements of carbon, such as is found in graphitic materials.

Ferralis, working with ancient sediment samples being investigated in the Summons' lab, identified substructures within the main D band that are directly related to the amount of hydrogen in a sample. That is, the higher these sub-peaks, the more hydrogen is present -- an indication that the sample has been relatively less altered, and its original chemical makeup better preserved.

To test this new interpretation, the team sought to apply Raman spectroscopy, and their analytic technique, to samples of sediments whose chemical composition was already known. They obtained additional samples of ancient kerogen -- fragments of organic matter in sedimentary rocks -- from a team based at the University of California at Los Angeles, who in the 1980s had used meticulous, painstaking chemical methods to accurately determine the ratio of hydrogen to carbon.

The team quickly estimated the same ratio, first using Raman spectroscopy to generate spectra of the various kerogen samples, then using their method to interpret the peaks in each spectrum. The team's ratios of hydrogen to carbon closely matched the original ratios.

"This means our method is sound, and we don't need to do an insane or impossible amount of chemical purification to get a precise answer," Summons says.

Mapping a fossil

Going a step further, the researchers wondered whether they could use their technique to map the chemical composition of a microscopic fossil, which ordinarily would contain so little carbon that it would be undetectable by traditional chemistry techniques.

"We were wondering, could we map across a single microscopic fossil and see if any chemical differences were preserved?" Summons says.

To answer that question, the team obtained a microscopic fossil of a protist -- an ancient, single-celled organism that could represent a simple alga or its predator. Scientists deduce that such fossils were once biological in origin, simply from their appearance and their similarity to hundreds of other patterns in the fossil record.

The team used Raman spectroscopy to measure the atomic vibrations throughout the fossil, at a sub-micron resolution, and then analyzed the resulting spectra using their new analytic technique. They then created a chemical map based on their analysis.

"The fossil has seen the same thermal history throughout, and yet we found the cell wall and cell contents have higher hydrogen than the cell's matrix or its exterior," Summons says. "That to me is evidence of biology. It might not convince everybody, but it's a significant improvement than what we had before."

Ultimately, Summons says that, in addition to identifying promising samples on Mars, the group's technique will help paleontologists understand Earth's own biological evolution.

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