Study explains why galaxies stop creating stars

ESO 137-001 is a perfect example of a spiral galaxy zipping through a crammed cluster of galaxies. Gas is being pulled from its disc in a process called ram pressure stripping. The galaxy appears to be losing gas as it plunges through the Norma galaxy cluster.

Galaxies come in three main shapes -- elliptical, spiral (such as the Milky Way) and irregular. They can be massive or small. To add to this mix, galaxies can also be blue or red. Blue galaxies are still actively forming stars. Red ones mostly are not currently forming stars, and are considered passive.

The processes that cause galaxies to "quench," that is, cease star formation, are not well understood, however, and constitute an outstanding problem in the study of the evolution of galaxies. Now, using a large sample of around 70,000 galaxies, a team of researchers led by University of California, Riverside astronomers Behnam Darvish and Bahram Mobasher may have an explanation for why galaxies stop creating stars.

The research team, which included scientists at the California Institute of Technology and Lancaster University, United Kingdom, combed through available data from the COSMOS UltraVISTA survey that give accurate distance estimates for galaxies over the past 11 billion years, and focused on the effects of external and internal processes that influence star formation activity in galaxies.

External mechanisms, the research team notes, include drag generated from an infalling galaxy within a cluster of galaxies, which pulls gas away; multiple gravitational encounters with other galaxies and the dense surrounding environment, resulting in material being stripped away from the galaxy; and the halting of the supply of cold gas to the galaxy, thus strangling the galaxy of the material needed to produce new stars over a prolonged period of time.

The researchers explain that internal mechanisms include the presence of a black hole (in which jets, winds, or intense radiation heat up hydrogen gas in the galaxy or blow it out completely, thus preventing the gas from cooling and contracting to form stars) and "stellar outflow" (for example, high-velocity winds produced by massive young stars and supernovae that push the gas out of the host galaxy).

"By using the observable properties of the galaxies and sophisticated statistical methods, we show that, on average, external processes are only relevant to quenching galaxies during the last eight billion years," said Darvish, a former graduate student in the UC Riverside Department of Physics and Astronomy and the first author of the research paper that appears today in The Astrophysical Journal. "On the other hand, internal processes are the dominant mechanism for shutting off star-formation before this time, and closer to the beginning of the universe."

The finding gives astronomers an important clue towards understanding which process dominates quenching at various cosmic times. As astronomers detect quenched non-star-forming galaxies at different distances (and therefore times after the Big Bang), they now can more easily pinpoint what quenching mechanism was at work.

In astronomy, much debate continues on whether it is only internal, external or a combination of both phenomena that makes a galaxy quench star formation. It is still not clear what processes are mostly responsible, and unclear, too, is the fractional role of different physical processes in shutting down the star-formation. It is also not fully understood when these processes come to play an important role in the evolutionary life of galaxies.

"The situation becomes more complex when we realize that all these mechanisms may depend on properties of galaxies being quenched, they may evolve with time, they act at different time-scales -- fast or slow -- and they may depend on the properties of the quenching factors as well," Darvish said.

Mobasher, a professor of physics and astronomy who supervised Darvish during the course of the research, said, "We found that on average the external processes act in a relatively short time-scale, around one billion years, and can more efficiently quench galaxies that are more massive. Internal effects are more efficient in dense clusters of galaxies. The time-scale is very important. A short time-scale suggests that we need to look for external physical processes that are fast in quenching. Another important result of the work is that internal and external processes do not act independently of each other in shutting-off the star formation."

Read more at Science Daily

Chicken-Sized Ostrich Relative Roamed N. America

Calciavis, a new species and early relative of ostriches, stands by the shores of an Eocene lake.

Picture a modern-day ostrich – the world's largest bird, anywhere from around 6 to nearly 9 feet tall -- and then shrink it down to the size of a chicken. That's what you get if it's Calciavis grandei you're picturing: a 50-million-year-old, newly documented bird species and an early relative of the ostrich we know and run from today.

Fossils of the bird were found 10 years ago in Wyoming's Green River Formation, an area that's considered a bonanza for extinct fish fossils as well as other long-dead creatures such as crocodiles, bats and turtles.

After long examination of the fossils, the new species has been documented in a study in the Bulletin of the American Museum of Natural History by researchers from Virginia Tech and the University of Texas.

The authors of the research consider the fossils singular finds for paleontologists.

"This is among one of the earliest well-represented bird species after the age of large dinosaurs," said study co-author Sterling Nesbitt, of Virginia Tech, in a statement. Nesbitt has been studying the fossils since 2009.

In all, two fossils of the species were found, one of which a near-complete skeleton, with soft-tissue remains, covered in feather remnants. They date from the Eocene epoch, some 30 to 56 million years ago.

Shown is a nearly complete skeleton of Calciavis grandei, a close relative of ostriches, kiwis, and emus.

The scientists say the ancient bird would have been about the size of a chicken and would have lived primarily on the ground, flying only for short bursts in the "Wyoming" of its day -- a much different place at the time.

"Back whenCalciavis was alive," Nesbitt said, "it lived in a tropical environment that was rich with tropical life, and this is in stark contrast to the high-desert environment in Wyoming today."

Read more at Discovery News

Like humans, lowly cockroach uses a GPS to get around, scientists find

By recording activity in the brain of a restrained cockroach, researchers found the insects use sight and a vestibular-like system to track direction and angle.

Rats, men and cockroaches appear to have a similar GPS in their heads that allows them to navigate new surroundings, researchers at Case Western Reserve University report.

The finding, published in journal Current Biology, is likely an example of convergent evolution--that is, distinct animals developed similar systems to manage the same problems.

Due to their simpler brain, further studies on cockroaches that would be difficult--if not impossible--on mammals may yield new insights into how humans orient themselves and navigate. Or, what goes awry in people who have extreme trouble getting their bearings.

"We've known that a mammal can come into a new area and, after a short period of being disoriented, find its way around," said Roy Ritzmann, a biology professor at Case Western Reserve and an author of the new study.

Humans and other mammals rely on head-direction, place and grid cells in their brains to process, integrate and update sensory information. The cues come from the direction they look, what they see and motion, he said.

Insects must maneuver through new environments, too.

"Orienting contributes to spatial memory, so they can return to point A or navigate to something they like or away from something they don't like," said PhD student Adrienn G. Varga, lead author of the study.

By repeating experiments that uncovered head-direction cells in rats, Ritzmann and Varga found head-direction-like activity and evidence of contextual cue processing in cockroaches.

The experiment

The researchers recorded cell activities in an area of the brain called the central complex while roaches were restrained in a tube.

Each roach was placed on a platform that rotated clockwise or counter clockwise. The platform was encircled by a black wall with a single removable landmark: a white square.

The insects were rotated 360 degrees in 30-degree increments, four to six times, both clockwise and counterclockwise.

Roaches could see, and though they lack an inner ear, have a vestibular-like system that appears to provide directional cues.

Similar to humans, who appear to have different cells that fire when turning clockwise compared to counterclockwise, the cell activity in roaches was different when turning clockwise from counterclockwise.

"The cells signaled which direction the animal just turned," Varga said.

The greatest cell activity came while the white card was inserted in the wall, providing a visual landmark along with the cues provided by the passive motion from the rotating platform.

When the card was removed, the activity of some cells was the same at the same angles as the roaches rotated, indicating the insects knew their orientation without visual input.

To test this further, the researchers put a foil cover over the heads of a new set of cockroaches. As they rotated, the blinded roaches showed similar central complex activity to the earlier roaches that were turned without the landmark.

The researchers then removed the foil and inserted the card in the wall. As the roaches rotated, some central complex cells shifted their peak activity, suggesting the GPS was remapping by including the new visual information.

Some cells, however, showed no change in peak activity, indicating they rely only on the internal cues that were provided by the passive motion as they rotated.

When the researchers closely examined the activity of central complex cells, they found that some neurons appear to encode head direction like a compass, while others appeared to encode the relative direction of the rotation (clockwise or counterclockwise) after each stop, storing navigational context. And a small subset did both.

The upshot

"The fact we found these cell activities that are very similar to those in mice and rats and us strongly indicates insects rely on the same sensory inputs we need to orient ourselves and their brains process these inputs in a similar manner," Varga said.

Ritzmann said either humans and cockroaches have a common ancestor, and this capability was retained or, more likely, represents convergent evolution.

"We argue that there are relatively few right solutions, that physics drives evolution and, ultimately, we get a very similar solution," he said. "Each animal has receptors that take in critical information in order to navigate a complex environment."

Read more at Science Daily

Physicists discover family of tetraquarks

A tetraquark is a particle with four quarks, which are the fundamental constituents of matter.

Physicists in the Syracuse University College of Arts and Sciences have made science history by confirming the existence of a rare four-quark particle and discovering evidence of three other "exotic" siblings.

Their findings are based on data from the Large Hadron Collider (LHC), the world's biggest, most powerful particle accelerator, located at the CERN science laboratory in Geneva, Switzerland.

Professor Tomasz Skwarnicki and Ph.D. student Thomas Britton G'16, both members of the Experimental High-Energy Physics Group at Syracuse and the Large Hadron Collider beauty (LHCb) collaboration at CERN, have confirmed the existence of a tetraquark candidate known as X(4140). They also have detected three other exotic particles with higher masses, called X(4274), X(4500) and X(4700).

All four particles were the subject of Britton's Ph.D. dissertation, which he defended in May and then submitted, on behalf of the LHCb collaboration, as a journal article to Physical Review Letters (American Physical Society, 2016).

A tetraquark is a particle made of four quarks: two quarks and two antiquarks.

Tetraquarks--and, by extension, pentaquarks, containing five quarks--are considered exotic because they have more than the usual allotment of two or three quarks.

"Even though all four particles contain the same quark composition, each of them has a unique internal structure, mass and set of quantum numbers," says Skwarnicki, who, in April 2014, confirmed the existence of the world's first charged tetraquark candidate, called Z(4430)+. A year earlier, he and Ph.D. student Bin Gui G'14 determined the quantum numbers of the first neutral, heavy tetraquark candidate, X(3872).

Quantum numbers describe each particle's subatomic properties.

Skwarnicki says the measurement of all four particles is the largest single one of its kind to date. Unlike other exotic particle candidates, his and Britton's do not contain ordinary nuclear matter (i.e., quarks found in protons and neutrons).

"We've never seen this kind of thing before. It's helping us distinguish among various theoretical models of particles," Skwarnicki says.

A fellow of the American Physical Society, Skwarnicki is a longtime member of the LHCb collaboration, involving approximately 800 other scientists from 16 countries. Their goal is to discover all forms of matter, in hopes of explaining why the universe is made of it, instead of anti-matter.

Skwarnicki's work focuses on quarks--fundamental constituents of matter that serve as a kind of scaffolding for protons and neutrons. While most particles have two or three quarks, Skwarnicki and others, in the past decade, have observed ones with four or five.

Last summer, he and doctoral student Nathan Jurik G'16 teamed up with Distinguished Professor Sheldon Stone and Liming Zhang, a professor at Tsinghua University in Beijing, to announce their discovery of two rare pentaquark states. The news made headlines, thrusting Syracuse and CERN into the international spotlight.

According to the Standard Model of particle physics, there are six kinds of quarks, whose intrinsic properties cause them to be grouped into pairs with unusual names: up/down, charm/strange and top/bottom.

The particles that Skwarnicki and Britton study have two charm quarks and two strange quarks. Charm and strange quarks are the third- and fourth-most massive of all quarks.

That all four quarks in the new family are "heavy" is noteworthy.

"The heavier the quark, the smaller the corresponding particle it creates," says Skwarnicki, adding that the names of the particles reflect their masses. "The names are denoted by mega-electron volts [MeV], referring to the amount of energy an electron gains after being accelerated by a volt of electricity. ... This information, along with each particle's quantum numbers, enhances our understanding of the formation of particles and the fundamental structures of matter."

Evidence of X(4140) first appeared in 2009 at the Fermi National Accelerator Laboratory, outside of Chicago, but the observation was not confirmed until three years later at CERN.

A rendering of the enormous LHCb detector, which registers approximately 10 million proton collisions per second. Scientists study the debris from these collisions to better understand the building blocks of matter and the forces controlling them. Extremely rare and four times heavier than a proton, X(4140) has been initially detected only 20 times out of billions of human-made energy collisions. LHCb is uniquely suited to study such particles, and thus, has gone on to detect X(4140) nearly 560 times.

Skwarnicki attributes the discovery of X(4140)'s three siblings, culled from LHCb data from 2011 to 2012, to increased instrumental sensitivity. It is the energy configuration of the quarks, he explains, that gives each particle its unique mass and identity.

"Quarks may be tightly bound, like three quarks packed inside a single proton, or loosely bound, like two atoms forming a molecule," Skwarnicki says. "By examining the particles' quantum numbers, we were able to narrow down the possibilities and rule out the molecular hypothesis."

A snapshot of LHCb detector data, singling out the collisions that have resulted in the four tetraquarks. Not that the process has been easy. An "aporetic saga" is how Britton describes studying molecular structures that seem to "jump out of the data."

"We looked at every known particle and process to make sure that these four structures couldn't be explained by any pre-existing physics," he says. "It was like baking a six-dimensional cake with 98 ingredients and no recipe--just a picture of a cake."

Read more at Science Daily

The debut of a robotic stingray, powered by light-activated rat cells

This is a tissue-engineered soft-robotic ray and a little skate, Leucoraja erinacea.

Researchers have created a robotic mimic of a stingray that's powered and guided by light-sensitive rat heart cells.

The work exhibits a new method for building bio-inspired robots by means of tissue engineering. Batoid fish, which include stingrays, are distinguished by their flat bodies and long, wing-like fins that extend from their heads. These fins move in energy-efficient waves that emulate from the front of the fin to the back, allowing batoids to glide gracefully through water. Inspired by this design, Sung-Jin Park et al. endeavored to build a miniature, soft tissue robot with similar qualities and efficiency.

They created neutrally charged gold skeletons that mimic the stingray's shape, which were overlaid with a thin layer of stretchy polymer. Along the top of the robotic ray, the researchers strategically aligned rat cardiomyocytes (muscle cells). The cardiomyocytes, when stimulated, contract the fins downward.

Since stimulating the fins to turn in an upward motion would require a second layer of cardiomyocytes, the researchers instead designed the gold skeleton in a shape that stores some downward energy, which is later released as the cells relax, allowing the fins to rise. So that the researchers can control the robot's movement using pulses of light, the cardiomyoctyes were genetically engineered to respond to light cues.

Asymmetrical pulses of light can be used to turn the robot to the left or right, the researchers showed, and different frequencies of light can be used to control its speed, as demonstrated in a series of videos. The method works well enough to guide the robot through a basic obstacle course. The robotic stingray, containing roughly 200,000 cardiomyocytes, is 16 millimeters long and weighs just 10 grams.

From Science Daily

Curiosity Finds Unique Ripples in Mars' Dunes

Though both Mars and Earth possess wind-blown sand dunes with very similar characteristics, it seems Martian dunes have a little something extra.

Mars is a planet shaped by aeolian -- or "wind-driven" -- processes. So it probably doesn't come as a surprise to know the Red Planet also sports some pretty big sand dunes.

From afar, these dunes strongly resemble the dunes we have on our planet. But in a new study carried out by NASA's Mars rover Curiosity, an active dune field on Mars has revealed that, though many of the processes that shape Martian dunes are the same processes that shape terrestrial dunes, there's an extra ripple that can only form in Mars' atmosphere.

"Earth and Mars both have big sand dunes and small sand ripples, but on Mars, there's something in between that we don't have on Earth," said graduate student Mathieu Lapotre, of Caltech in Pasadena, Calif., in a NASA statement.

On both Earth and Mars dunes can be as large as a football field and consist of a gently-sloping upwind face and a steep downwind face that is shaped by continuous sand avalanches as the prevailing wind keeps pushing material over the apex of the dune. Classical arc-shaped barchan dunes can often result on both planets and Mars satellites have captured some stunning observations of these types of dunes from orbit. Just look at them, they're amazing.

On Earth, the surfaces of these dunes are often rippled with peaks and troughs spaced around 30 centimeters (12 inches) apart. These rows of ripples are created by wind-carried grains of sand colliding with stationary grains, eventually creating a corrugated texture on dunes covering sandy deserts and beaches.

Until Curiosity started its approach to the active dark Bagnold Dunes six months ago on the northwestern slopes of Mount Sharp, scientists didn't know whether these small-scale "impact ripples" existed. From orbit, larger ripples measuring around three meters (10 feet) from peak to peak could be seen and it was generally assumed that these larger-scale ripples were equivalent to Earth's impact ripples, only much larger owing to the thin Martian atmosphere and lower gravity.

But when Curiosity arrived at Bagnold, the rover didn't only see the 10 feet-wide ripples, but it also saw the small-scale ripples just like Earth's impact ripples.

"As Curiosity was approaching the Bagnold Dunes, we started seeing that the crest lines of the meter-scale ripples are sinuous," said Lapotre, who's also science team collaborator for the Curiosity mission. "That is not like impact ripples, but it is just like sand ripples that form under moving water on Earth. And we saw that superimposed on the surfaces of these larger ripples were ripples the same size and shape as impact ripples on Earth."

So it turns out that Mars dunes have an added complexity that could only be proven by rolling up close and taking photos. Mars dunes have the small impact ripples, plus medium-sized "sinuous ripples" that can be resolved from space.

Interestingly, though Earth's dunes don't possess sinuous ripples, they can form underwater -- on a riverbed, for example. Rather than particles colliding, these sinuous ripples are created as flowing water drags particles, causing them to settle in a rippled pattern.

Lapotre, who is lead author of a study that was published on July 1 in the journal Science, thinks that the Martian sinuous ripples are being driven in a similar way, but it's the Red Planet's thin atmosphere that's dragging the particles to form the medium-sized ripples on the sand dunes. Lapotre's team have nicknamed them "wind-drag ripples."

"The size of these ripples is related to the density of the fluid moving the grains, and that fluid is the Martian atmosphere," he said. "We think Mars had a thicker atmosphere in the past that might have formed smaller wind-drag ripples or even have prevented their formation altogether. Thus, the size of preserved wind-drag ripples, where found in Martian sandstones, may have recorded the thinning of the atmosphere."

Read more at Discovery News

Beating heart of the Crab Nebula

Crab Nebula.

Peering deep into the core of the Crab Nebula, this close-up image reveals the beating heart of one of the most historic and intensively studied remnants of a supernova, an exploding star. The inner region sends out clock-like pulses of radiation and tsunamis of charged particles embedded in magnetic fields.

The neutron star at the very center of the Crab Nebula has about the same mass as the sun but compressed into an incredibly dense sphere that is only a few miles across. Spinning 30 times a second, the neutron star shoots out detectable beams of energy that make it look like it's pulsating.

The NASA Hubble Space Telescope snapshot is centered on the region around the neutron star (the rightmost of the two bright stars near the center of this image) and the expanding, tattered, filamentary debris surrounding it. Hubble's sharp view captures the intricate details of glowing gas, shown in red, that forms a swirling medley of cavities and filaments. Inside this shell is a ghostly blue glow that is radiation given off by electrons spiraling at nearly the speed of light in the powerful magnetic field around the crushed stellar core.

The neutron star is a showcase for extreme physical processes and unimaginable cosmic violence. Bright wisps are moving outward from the neutron star at half the speed of light to form an expanding ring. It is thought that these wisps originate from a shock wave that turns the high-speed wind from the neutron star into extremely energetic particles.

When this "heartbeat" radiation signature was first discovered in 1968, astronomers realized they had discovered a new type of astronomical object. Now astronomers know it's the archetype of a class of supernova remnants called pulsars -- or rapidly spinning neutron stars. These interstellar "lighthouse beacons" are invaluable for doing observational experiments on a variety of astronomical phenomena, including measuring gravity waves.

Observations of the Crab supernova were recorded by Chinese astronomers in 1054 A.D. The nebula, bright enough to be visible in amateur telescopes, is located 6,500 light-years away in the constellation Taurus.

From Science Daily

Weathering of rocks by mosses may explain climate effects during the Late Ordovician

Moss on rock.

During the Ordovician period, the concentration of CO2 in Earth's atmosphere was about eight times higher than today. It has been hard to explain why the climate cooled and why the Ordovician glaciations took place. A new study, published in Nature Communications, shows that the weathering of rock caused by early non-vascular plants had the potential to cause such a global cooling effect.

"When we can better understand the carbon cycle in the past, we can better predict what happens with the climate in the future," says Philipp Porada of Stockholm University, one of the authors of the study.

Non-vascular plants, such as mosses, hornworts and liverworts, probably evolved during the Ordovician period, around 450 million years ago. They are older than vascular plants, such as trees and grasses, and together with lichens, which are a symbiosis of fungi and algae, they formed the earliest terrestrial vegetation. Today's successors of these organisms are distributed worldwide and are characterised by their ability to survive in environments in which the supply of both water and nutrients is scarce. They are found in both cold and warm desert regions and are able to grow on rock surfaces and the bark of trees. Although they do not have real roots, they affect the surfaces on which they grow: the release of various organic acids dissolves underlying rock minerals.

This process of dissolution and chemical transformation of rock minerals is called chemical weathering. Non-vascular plants and lichens may considerably increase weathering rates of the rock surfaces on which they grow. This has important implications for the climate system, since chemical weathering of silicate rocks such as granite results in a drawdown of atmospheric CO2 and may therefore lead to global cooling. During the weathering process CO2 dissolves in water as acid, and is then transported to the ocean where the carbon is buried as carbonate rock. Consequently, it has been hypothesised that early non-vascular vegetation caused an interval of glaciations at the end of the Ordovician period, when they became globally abundant. Without the drawdown of atmospheric CO2 caused by the enhancement of weathering rates, the Ordovician glaciations are hard to explain, since they started under conditions of eight times higher atmospheric CO2 than today.

"I believe that the most interesting thing about the study is that tiny plants such as mosses and lichens can influence global climate in the long run," says Philipp Porada.

Read more at Science Daily

Can New Equation Calculate Odds of Alien Life?

Artist's impression of the view from a relatively close planet orbiting a cool dwarf star.

Could a mathematical formula help scientists find ET?

SETI pioneer Frank Drake thought so. Or at least Drake believed that an equation would give seekers of intelligent life beyond Earth a clue about what their odds are.

The so-called Drake Equation, published in 1961, was the first attempt to quantify the number of advanced civilizations in the Milky Way based on the rate of star formation in the galaxy, the fraction of stars with planets, the number planets suitably located to support life, and other metrics.

Now, a team of scientist is suggesting an alternative equation based on a planet's chemistry and its "origin of life"-type events.

"It has somewhat of the methodology of the Drake Equation because it's trying to compute some parameter that might help you evaluate the prevalence of life in the cosmos," said astronomer Seth Shostak, with the SETI Institute in Mountain View, Calif., and who was not involved in the study.

SETI is an acronym for The Search for Extraterrestrial Intelligence.

The new study is based on the idea that life's origin on early Earth, and presumably other planets, was not a one-shot process.

The idea is that there were "lots and lots of experiments going on and it may be that they actually helped one another, though not deliberately … Some molecule that's made over here by accident and which isn't alive may help that molecule over there, which also is not alive, take another step toward something that is alive," Shostak said.

"They're just trying to put all that into some mathematics so that it gives you some idea of the probability that all that will work. That's my take on it," Shostak said.

Origin of life-type events, "may be the critical difference between cosmic environments where life is potentially more or less abundant but, more importantly, points to constraints on the search," SETI researchers Caleb Scharf, with Columbia University, and Leroy Cronin, with the University of Glasgow, write in the new study.

Read more at Discovery News

Volcanic Lightning: How Does It Work?

The fusion of flash with ash! Say the words aloud, together, and it sounds impossible – the kind of thing a six-year-old might think up. And yet, volcanic lightning is very real. But how does it happen?

Few phenomena can compete with the raw beauty and devastating power of a raging thunderstorm, save for a particularly violent volcanic eruption. But when these two forces of nature collide, the resulting spectacle can be so sublime as to defy reason.

The photograph above offers some important insights into the formation and study of volcanic lightning. It was taken late last month by German photographer Martin Rietze, on a visit to Japan's Sakurajima volcano. Only very big eruptions, he tells us via email, can generate major thunderbolts like the ones seen above.

Smaller eruptions tend to be accompanied by more diminutive storms, which can be difficult to spot through thick clouds of ash. What's more, lightning activity is highest during the beginning stages of an eruption, making it all the more challenging to capture on film. Photographing a big volcanic event at any stage is hard enough as it is; if you're not nearby when it happens, says Rietze, "you will always arrive too late."

It turns out the same things that make volcanic lightning hard to photograph also make it difficult to study. The first organized attempt at scientific observation was made during Iceland's Surtsey eruption in 1963 (pictured here). The investigation was later recounted in a May 1965 issue of Science:
"Measurements of atmospheric electricity and visual and photographic observations lead us to believe that the electrical activity is caused by the ejection from the volcano into the atmosphere of material carrying a large positive charge."

Translation? Volcanic lightning, the researchers hypothesize, is the result of charge-separation. As positively charged ejecta makes its way skyward, regions of opposite but separated electrical charges take shape. A lightning bolt is nature's way of balancing the charge distribution. The same thing is thought to happen in regular-old thunderstorms. But this much is obvious, right? So what makes volcanic lightning different?

Close to 50 years have transpired since Surtsey exploded in November 1963. Since then, only a few studies have managed to make meaningful observations of volcanic eruptions. One of the most significant was published in 2007, after researchers used radio waves to detect a previously unknown type of lightning zapping from the crater of Alaska's Mount Augustine volcano in 2006.

"During the eruption, there were lots of small lightning (bolts) or big sparks that probably came from the mouth of the crater and entered the (ash) column coming out of the volcano," said study co-author Ronald J. Thomas in a 2007 interview with National Geographic. "We saw a lot of electrical activity during the eruption and even some small flashes going from the top of the volcano up into the cloud. That hasn't been noticed before."

The observations suggest that the eruption produced a large amount of electric charge, corroborating the 1963 hypothesis – but the newly identified lightning posed an interesting puzzle: where, exactly, do these charges come from? "We're not sure if it comes out of the volcano or if it is created just afterwards," Thomas explains. "One of the things we have to find out is what's generating this charge."

Since 2007, a small handful of studies have led to the conclusion that there exist at least two types of volcanic lightning – one that occurs at the mouth of an erupting volcano, and a second that dances around in the heights of a towering plume (an example of the latter occurred in 2011 above Chile's Puyehue-Cordón Caulle volcanic complex, as pictured here. (Photograph by Carlos Gutierrez/Reuters.) Findings published in a 2012 article in the geophysics journal Eos reveal that the largest volcanic storms can rival the intensity of massive supercell thunderstorms common to the American midwest. Still, the source of the charge responsible for this humbling phenomenon remains hotly debated.

Read more at Discovery News

Evolution may have moved at a furious pace on a much warmer earth

A much faster pace of evolution means that species could have proliferated much more rapidly than they do now, affording the flora and fauna of Earth ample time to acquire their enormous diversity and complexity.

Early life forms on Earth are likely to have mutated and evolved at much higher rates than they do today, suggests a new analysis from researchers at the University of North Carolina.

In a study published this week in the Proceedings of the National Academy of Sciences, Richard Wolfenden, PhD, and his colleagues found that the rate of a certain chemical change in DNA -- a key driver of organisms' spontaneous mutation rates and thus of evolution's pace -- increases extremely rapidly with temperature. Combining that finding with recent evidence that life arose when our planet was much warmer than it is now, the scientists concluded that the rate of spontaneous mutation was at least 4,000 times higher than it is today.

"At the higher temperatures that seem to have prevailed during the early phase of life, evolution was shaking the dice frantically," said Wolfenden, Alumni Distinguished Professor of Biochemistry and Biophysics at the UNC School of Medicine.

A much faster pace of evolution means that species could have proliferated much more rapidly than they do now, affording the flora and fauna of Earth ample time to acquire their enormous diversity and complexity.

That issue -- whether life could have evolved to its present level of complexity within the time available -- has lingered ever since Darwin published his theory more than a century and a half ago. Throughout that debate, both skeptics and proponents of evolutionary theory have often assumed that evolution's pace has stayed more or less constant over the eons.

The planet formed about 4.6 billion years ago from the cloud of dust and gas surrounding the early sun, and began as a hellish world of molten rock. It cooled until a crust condensed, and eventually, around 4.3 billion years ago, liquid brine began to fill the lower elevations, forming oceans.

"Recent evidence from rock samples in Australia indicates that life forms arose on Earth as early as 4.1 billion years ago -- almost in the blink of an eye after the appearance of liquid oceans," Wolfenden said.

At that time, the average temperature at Earth's surface would have been near the boiling point of water -- 100 degrees Celsius, about 75 degrees higher than today.

To get some idea of the effect of such a high temperatures on the rate of evolution, Wolfenden's team examined a chemical reaction known as cytosine deamination, which occurs from time to time in all cells and may be the single most frequent cause of spontaneous DNA mutations.

In the deamination reaction, cytosine -- the DNA base molecule known as "C" in the genetic code -- loses an ammonia-like "amine" group of atoms. Deamination leads to the mutation of the cytosine into the DNA base thymine ("T" in the genetic code).

Wolfenden's team experimentally determined the rates of spontaneous deamination at different temperatures for cytosine and several cytosine-related molecules. In collaboration with the UNC lab of Ronald Swanstrom, PhD, the Charles P. Postelle, Jr. Distinguished Professor of Biochemistry at UNC, the researchers also measured the rates of cytosine deaminations and spontaneous C-to-T mutations in single-stranded DNA from the HIV virus that causes AIDS. The results showed that the rates of cytosine deamination, for isolated molecules and for single-stranded DNA, rose very steeply as the temperature increased. The scientists then added the assumption that Earth's surface temperature has itself changed exponentially -- following Newton's law of cooling -- over the period in which life has existed.

"Cytosine-based mutations, when the temperature was near 100 degrees C, occurred at more than 4,000 times the modern rate,"Wolfenden said. "To me, that was surprising. I thought the ancient rate would be more rapid than the modern rate, but not that rapid."

How could early life forms have coped with a high-temperature environment where their genetic material was being altered so rapidly?

"That question is still out there," Wolfenden said. He noted, though, that there are microorganisms even now that normally live in hot springs or deep-sea thermal vents, and somehow survive and multiply at temperatures as high as 120 degrees C.

Read more at Science Daily

A new look at the galaxy-shaping power of black holes

Data from a now-defunct X-ray satellite is providing new insights into the complex tug-of-war between galaxies, the hot plasma that surrounds them, and the giant black holes that lurk in their centres.

Launched from Japan on February 17, 2016, the Japanese space agency (JAXA) Hitomi X-ray Observatory functioned for just over a month before contact was lost and the craft disintegrated. But the data obtained during those few weeks was enough to paint a startling new picture of the dynamic forces at work within galaxies.

New research, published in the journal Nature today, reveals data that shows just how important the giant black holes in galactic centres are to the evolution of the galaxies as a whole.

"We think that supermassive black holes act like thermostats," said Brian McNamara, University Research Chair in Astrophysics at the University of Waterloo. "They regulate the growth of galaxies."

Champagne bubbles of plasma

During its brief life, the Hitomi satellite collected X-ray data from the core of the Perseus cluster, an enormous gravitationally-bound grouping of hundreds of galaxies. Located some 240 million light years from earth, the Perseus cluster is one of the largest known structures in the universe. The cluster includes not only the ordinary matter that makes up the galaxies, but an "atmosphere" of hot plasma with a temperature of tens of millions of degrees, as well as a halo of invisible dark matter.

Earlier studies, going back to the 1960s, have shown that each of the galaxies in the cluster -- and indeed most galaxies -- likely contains a supermassive black hole in its centre, an object 100 million to more than ten billion times as massive as our sun.

"These giant black holes are among the universe's most efficient energy generators, a hundred times more efficient than a nuclear reactor," said McNamara from Waterloo's Department of Physics and Astronomy in the Faculty of Science. "Matter falling into the black hole is ripped apart, releasing vast amounts of energy in the form of high speed particles and thermal energy."

This heat is released from just outside the black hole's event horizon, the boundary of no return. The remaining matter gets absorbed into the black hole, adding to its mass. The released energy heats up the surrounding gas, creating bubbles of hot plasma that ripple through the cluster, just as bubbles of air rise up in a glass of champagne.

The research is shedding light on the crucial role that this hot plasma plays in galactic evolution. Researchers are now tackling the foremost issue in the formation of structure in the universe and asking: why doesn't most of the gas cool down, and form stars and galaxies? The answer seems to be that bubbles created by blasts of energy from the black holes keep temperatures too high for such structures to form.

"Any time a little bit of gas falls into the black hole, it releases an enormous amount of energy," said McNamara. "It creates these bubbles, and the bubbles keep the plasma hot. That's what prevents galaxies from becoming even bigger than they are now."

Because plasma is invisible to the eye, and to optical telescopes, it wasn't until the advent of X-ray astronomy that the full picture began to emerge. In visible light, the Perseus cluster appears to contain many individual galaxies, separated by seemingly-empty space. In an X-ray image, however, the individual galaxies are invisible, and the plasma atmosphere, centred on the cluster's largest galaxy, known as NGC 1275, dominates the scene.

Although the black hole at the heart of NGC 1275 has only one-thousandth of the mass of its host galaxy, and has a much smaller volume, it seems to have a huge influence on how the galaxy and how the surrounding hot plasma atmosphere evolve.

"It's as though the galaxy somehow knows about this black hole sitting at the centre," said McNamara. "It's like nature's thermostat, that keeps these galaxies from growing. If the galaxy tries to grow too fast, matter falls into the black hole, releasing an enormous amount of energy, which drives out the matter and prevents it from forming new stars."

McNamara notes that the actual event horizon of the black hole is about the same size as our solar system, making it as small compared to its host galaxy as a grape is to the Earth. "What's going on in this tiny region is affecting a vast volume of space," he said.

Thanks to the black hole's regulatory effect, the gas that would have formed new stars instead remains a hot plasma -- whose properties Hitomi was designed to measure.

Doomed satellite missions

Hitomi employed an X-ray spectrometer which measures the Doppler shifts in emissions from the plasma; those shifts can then be used to calculate the speed at which different parts of the plasma are moving. At the heart of the spectrometer is a microcalorimeter; cooled to just one-twentieth of a degree above absolute zero, the device records the precise energy of each incoming X-ray photon.

Getting an X-ray satellite equipped with a microcalorimeter into space has proved daunting: McNamara was deeply involved with NASA's Chandra X-ray Observatory, launched in 1999, that was initially set to include a microcalorimeter, but the project was scaled back due to budget constraints, and the calorimeter was dropped. Another mission with the Japanese space agency known as ASTRO-E was equipped with a microcalorimeter; it was set for launch in 2000, but the rocket exploded shortly after liftoff. A third effort, Japan's Suzaku satellite, launched in 2005, but a leak in the cooling system destroyed the calorimeter. Hitomi launched and deployed perfectly, but a series of problems with the attitude control system caused the satellite to spin out of control and break up.

The data from Hitomi, limited as it is, is enough to make astronomers re-think the role of plasma in galactic evolution, according to McNamara. "The plasma can be thought of forming an enormous atmosphere that envelopes whole clusters of galaxies. These hot atmospheres represent the failure of the past -- the failure of the universe to create bigger galaxies," he said. "But it's also the hope for the future. This is the raw material for the future growth of galaxies -- which is everything: stars, planets, people. It's the raw material that in the next several billion years is going to make the next generation of suns and solar systems. And how rapidly that happens is governed by the black hole."

Read more at Science Daily

Chemical trail on Saturn's Moon Titan may be key to prebiotic conditions

An image of Titan's surface, as taken by the European Space Agency's Huygens probe as it plunged through the moon's thick, orange-brown atmosphere on Jan. 14, 2005. Today, Cornell scientists have chemical evidence that suggests prebiotic conditions may exist there.

NASA's Cassini and Huygens missions have provided a wealth of data about chemical elements found on Saturn's moon Titan, and Cornell scientists have uncovered a chemical trail that suggests prebiotic conditions may exist there.

Titan, Saturn's largest moon, features terrain with Earthlike attributes such as lakes, rivers and seas, although filled with liquid methane and ethane instead of water. Its dense atmosphere -- a yellow haze -- brims with nitrogen and methane. When sunlight hits this toxic atmosphere, the reaction produces hydrogen cyanide -- a possible prebiotic chemical key.

"This paper is a starting point, as we are looking for prebiotic chemistry in conditions other than Earth's," said Martin Rahm, postdoctoral researcher in chemistry and lead author of the new study, "Polymorphism and Electronic Structure of Polyimine and Its Potential Significance for Prebiotic Chemistry on Titan," published in the Proceedings of the National Academy of Sciences, July 4.

To grasp the blueprint of early planetary life, Rahm said we must think outside of green-blue, Earth-based biology: "We are used to our own conditions here on Earth. Our scientific experience is at room temperature and ambient conditions. Titan is a completely different beast." Although Earth and Titan both have flowing liquids, Titan's temperatures are very low, and there is no liquid water. "So if we think in biological terms, we're probably going to be at a dead end," he said.

Hydrogen cyanide is an organic chemical that can react with itself or with other molecules -- forming long chains, or polymers, one of which is called polyimine. The chemical is flexible, which helps mobility under very cold conditions, and it can absorb the sun's energy and become a possible catalyst for life.

"Polyimine can exist as different structures, and they may be able to accomplish remarkable things at low temperatures, especially under Titan's conditions," said Rahm, who works in the lab of Roald Hoffmann, winner of the 1981 Nobel Prize in chemistry and Cornell's Frank H.T. Rhodes Professor of Humane Letters Emeritus. Rahm and the paper's other scientists consulted with Hoffmann on this work.

Read more at Science Daily

Ghostly Deep-Sea Fish Seen Alive for First Time

During its ongoing exploration of the Marianas Trench in the Pacific Ocean -- the world's deepest undersea formation -- scientists with the National Oceanic and Atmospheric Administration (NOAA) caught something special on video: a fish no one had ever seen alive before.

The NOAA team shot footage of a pale, nearly translucent representative of the family Aphyonidae, an eel-like clan that lives in the deepest of waters, from 8,000 to about 20,000 feet (2,438 to 6,096 meters) below the surface. It reminded viewers of "Casper," the ghostly octopus spotted by NOAA on a prior mission.

NOAA researchers on the video (see below) brim with excitement at the sight of the small fish (typically running just under 4 inches -- 10 centimeters -- long), whose skin has no scales and no pigment.

It was spotted about 8,200 feet down (2,500 meters).

"I am sure this is the first time a fish in this family has ever been seen alive," NOAA fishery biologist Bruce Mandy said on the accompanying video below. "This is really an unusual sighting."

"Look at those eyes!" NOAA researcher and expedition team leader Shirley Pomponi exclaimed.

In addition to the sighting itself being a thrill, the video may help answer an ongoing debate about the Aphyonidae. Mandy explains that some believe the fish live in the pelagic (not close to the bottom or the shore) zone while others think the aphyonidae are bottom dwellers.

While not conclusive, Mandy indicated, the video could present a "strong argument that, yes, this family is a bottom-living family."

From Discovery News

Urine-Based Dye Found in Ancient New Testament

Behind one of the oldest surviving illuminated manuscripts of the New Testament lies a mixture of urine and weeds, according to analysis carried out during a lengthy restoration project of the sacred text.

For centuries scholars wondered how the precious purple parchments of the 1,500-year-old Byzantine book known as the Codex Purpureus Rossanensis were obtained.

It was generally assumed that Tyrian purple, extracted from Murex (sea snails) was used to dye the parchment sheets.

On the contrary, analysis have shown the mysterious purple resulted from the use of orcein, a natural dye extracted from the lichen Roccella Tinctoria and processed with fermented urine, which at that time was the only source of ammonia.

Included in UNESCO's Memory of the World Register in 2015, the Codex Purpureus Rossanensis was found in 1879 in the sacristy of the Cathedral of Rossano, a town in the Calabria region of southern Italy.

The incomplete manuscript tells the life of Jesus according to the gospels of Matthew and Mark. It was likely made in Syria between the 5th and 6th centuries A.D. and consists of 188 parchment sheets filled with finely executed miniatures and Greek text written in gold and silver ink.

"Most likely, what we have today represents half of the original book," the museum of the diocese of Rossano, where the manuscript returned after the three-year long restoration, said in a statement.

It is believed the two lacking gospels were destroyed during a fire that occurred in the cathedral in the 17th century.

Restorers at the Central Institute for Restoration and Conservation of Archival and Library Heritage (Icrcpal) in Rome led by Maria Luisa Riccardi had to deal with a previous restoration carried out in 1917–19 which irreversibly modified the aspect of the illuminated sheets.

Given the manuscript's frailty, the restorers decided to avoid invasive procedures. They limited the intervention to stitching cuts, tears and small gaps and rather focused on the composition of the codex's pictorial palette.

"Even though early medieval illuminated manuscripts have been deeply studied from the historical standpoint, they have been rarely fully described in their material composition," Marina Bicchieri, director of the Icrcpal's chemistry lab, said.

Since X-ray fluorescence ruled out the presence of bromine, which is characteristic of Tyrian purple, Bicchieri turned to experimental data.

She prepared natural dyes using recipes described in the Stockholm papyrus, a manuscript written in Greek around 300 A.D. which contains 154 recipes for the manufacture of dyes and colors.

"Fibre optics reflectance spectra (FORS) showed a perfect match between the purple parchment of the codex and a dye obtained with orcein and an addition of sodium carbonate," Bicchieri told Discovery News.

Read more at Discovery News

Let there be light: Super bright galaxies of the early Universe

A very distant galaxy cluster in the early Universe.

Astronomers have shed further light on the evolution of the early Universewith the discovery of a "team" of super bright galaxies.

For about 150 million years after the Big Bang, the Universe was a "dark" place, made of just hydrogen and helium atoms, as the first stars had yet to be formed.

This all changed with the first generation of stars, so bright and powerful that their light started to break apart hydrogen atoms around them, while their cores produced the elements essential for life itself.

By peering back through time, Dr David Sobral and his team at Lancaster University have now confirmed a sample of galaxies that are giving us a unique glimpse into that era.

The fifth galaxy to be discovered and confirmed (at a Redshift of 7) has been named VR7, in tribute to the astrophysicist Vera Rubin, who in 1996 became the first woman to win the Gold Medal of the Royal Astronomical Society for 150 years.

The Lancaster team used the Subaru and Keck telescopes on Hawaii, and the Very Large Telescope in Chile to discover several galaxies which seem to have large bubbles of ionised gas around them, allowing light to pass through.

Dr Sobral said: "Stars and black holes in the earliest, brightest galaxies must have pumped out so much high energy/ultraviolet light that they quickly broke up hydrogen atoms. These galaxies are visible because large enough bubbles have been carved around them, but what is really surprising is how numerous these spectacular galaxies are."

Sergio Santos is another co-author of the study and will soon be a PhD student at Lancaster University. He adds: "Our results highlight how hard it is to study the small faint sources in the early universe. The neutral hydrogen gas blocks out most of their light, and because they are not capable of building their own local bubbles as quickly as the bright ones, they are much harder to detect."

The full team consists of David Sobral (Lancaster), Sergio Santos (Lancaster), Jorryt Matthee (Leiden), and Behnam Darvish (Caltech).

In 2015, Sobral led a team that found the first example of a spectacularly bright galaxy that may harbor first generation stars.

The galaxy was named Cosmos Redshift 7 or CR7 (the name also pays homage to footballer Cristiano Ronaldo). The team also discovered a similar galaxy, MASOSA, which, together with Himiko, discovered by a Japanese team, hinted at a larger population of similar objects, perhaps made up of the earliest stars and/or black holes.

With five bright sources now confirmed, and more to follow, CR7 is now part of a unique 'team' of bright early galaxies, suggesting there are tens to hundreds of thousands of similar sources in the entire visible Universe.

Read more at Science Daily

Amazonian Butterfly Steals Precious Goo from Ants

A bizarre Amazonian butterfly is the ultimate freeloader, researchers say.

The butterfly species steals and eats gooey bamboo secretions from its ant neighbors, in a relationship known as kleptoparasitism, new research has found.

"They're kind of jerks at the adult stage," said study co-author Aaron Pomerantz, a field biologist at thenextgenscientist.com. "They're just stealing a resource, and they're getting away with it for now."

Pomerantz and his colleagues have now captured images of the odd behavior — the first time that kleptoparasitism has been documented between adult butterflies and ants.

The goo-stealing butterflies, Adelotypa annulifera, are a wide-ranging species thatlives in a swath of South America from Bolivia to Guyana.

In 2013, Pomerantz's colleague Phil Torres was taking photos in the Amazon forest near the Tambopata Research Center in Peru when he noticed the butterflies feeding on bamboo sap where ants were congregating.

Torres told Pomerantz about it, and the two soon realized that although the species had been identified a century earlier, almost nothing was known about the life cycle of this butterfly.

"We had no idea what the caterpillars looked like; no one had ever seen them before," Pomerantz said.

So, upon returning to the site, Pomerantz went on a hunt to find the caterpillars of the species. He spent many weeks looking through the bamboo forest where Torres had originally found the creatures.

"Finally, I peeled back this little leaf, and that's when we saw the larvae," Pomerantz said.

As they returned over and over again to study the butterflies and ants, they noticed that the two species stuck together through all of the butterflies' life stages, from larvae to adults, the researchers reported in the June issue of the Journal of the Lepidopterists' Society.

When the relationship starts out, it seems to be more of a two-way street. Multiple ant species — even those known as bullet ants, which deliver the world's most painful sting — offer bodyguard duty while the caterpillars give the ants a nutritious "protein shake" of amino acids and sugars through a specialized body part called the tentacle nectary organ.

Caterpillars from the same family, called Riodinidae, even lure ants by singing to them with a special vibratory organ. (The caterpillar songs are too quiet for humans to hear them without specialized equipment.)

But as adults, the butterflies become freeloaders. The butterflies sport bright-red dots on their wings — a pattern that mimics stinging ants — allowing them to disguise themselves as ants and avoid predators, Pomerantz said.

"The butterflies aren't all that skittish; they just hang out in the open, and that's uncommon for a lot of butterflies," Pomerantz said.

Read more at Discovery News

Is This the Legendary Throne of Agamemnon?

A stone fragment that might belong to the lost throne of the kingdom of Mycenae has been found by a Greek archaeologist, if his claims are right.

Made of a type of stone that has not been found anywhere else in Mycenae, the 110-pound slab is dubbed the throne of Agamemnon after the legendary king of Mycenae and leader of the Greeks in the Trojan War.

One of the central figures in the "Iliad," Homer's epic poem about the war, Agamemnon is also known for his bloody end in a bathtub, hacked to death by his wife and her lover as he returned from his victorious expedition against Troy.

A team led by Greek archaeologist Christofilis Maggidis found the fragment two years ago in the now-dry riverbed of the Chavos River, within the city's Lower Town.

Maggidis, associate professor at Dickinson College and president of the Mycenaean Foundation, said the polished stone block was found directly below Mycenae's royal palace. The hilltop building had partially fell down during a catastrophic earthquake in about 1200 BC.

"The throne fragment had fallen, rolled and was subsequently buried by the river fill when the southeastern part of palace collapsed in the ravine," Maggidis said.

Shortly after the stone fragment was brought to light in 2014, the finding was questioned.

Vassilios Petrakos, the Secretary General of Archaeological Society at Athens, appointed a committee to examine the piece. At the end, the stone fragment was dismissed as a basin. The committee's conclusion was accepted by the Ministry of Culture and the case appeared settled.

But Maggidis, who has been leading excavations at the site of ancient Mycenae in southern Greece since 2007, announced recently that further studies indicate conclusively that the find is "a fragment of the stone seat of the monumental royal throne of the palace at Mycenae."

"The assessment of the Petrakos committee about a 'basin' is unreliable and fallacious, as it was based on unfounded assumptions and erroneous observations," Maggidis told Discovery News.

He noted that the fragment is made of porous stone and would have been useless to hold liquids had it been a basin.

"The importance of an archaeological find is assessed by the international academic community on the basis of its scientific publication and in due time, not by committees or organizations," he added.

Maggidis, who will detail his findings in a scientific publication in 2017, said the block shows a stunning resemblance to another, older and smaller throne found in the Minoan palace of Knossos.

"It is similar in terms of shape, size and proportions," Maggidis said.

He noted that all the other alternative interpretations of a basin, altar, offering table or mortar are eliminated when considering the high quality of fine carving and polishing and the morphology of the block, which is carved in such a way as to support being sat upon.

"For example, the shallow central depression, which is only 3cm (1.18 inch) deep, and the way in which it slightly deepens towards the rear side, identical to the Knossos throne, are indisputable traits of a seat," Maggidis said.

"This is one of the most important and emblematic finds of the Mycenaean age," he added.

Read more at Discovery News

Juno Arrives at Jupiter

A NASA spacecraft has arrived at the solar system's largest planet after a picture-perfect orbital insertion.

NASA's Juno space probe ended a five-year, 1.7-billion mile trek to Jupiter on Monday, nailing a do-or-die braking burn to shave its speed and settle into orbit around the largest planet in the solar system.

Confirmation of Juno's safe arrival came at 11:53 p.m. EDT when flight controllers reported an expected shift in tones coming from the probe, a live NASA TV broadcast showed.

"A big sigh of relief," said mission commentator Gay Yee Hill, at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Had the 35-minute burn of Juno's main engine failed, the spacecraft would have sailed past Jupiter, ending the mission before it began. Only one other spacecraft, NASA's Galileo probe, has orbited Jupiter.

Juno, named for the mythical Roman goddess who was the wife and sister of Zeus and who had the power to see through clouds, is designed to answer some key questions left over from Galileo's eight-year study of the Jovian system.

Topping scientists' wish list is knowing how much water Jupiter contains, information that they can feed into computer simulations to calculate how and where the planet formed.

"If Jupiter formed really far from the sun and drifted inward you'll get a different amount of water than if it formed where it is now," said Juno project scientist Steven Levin, at NASA's Jet Propulsion Laboratory.

Jupiter orbits about five times farther away from the sun than Earth.

"If it formed, as we think is likely, from icy planetesimals -- large chunks of ice that collided together -- and made a giant planet, then you'll get a different amount of water than if it formed some other way, such as directly condensing from the same material that made the sun," Levin said.

As the largest planet, Jupiter influenced the rest of the solar system's formation, including the location of Earth and its suitability for life.

"By studying Jupiter you're going to get on piece of the puzzle, not necessarily how life formed but maybe how the ingredients that made up life eventually got spread around in the early solar system and got to us," said Juno lead scientist Scott Bolton, with the Southwest Research Institute in San Antonio, Texas.

To collect its data, Juno will spend 20 months flying as close as 3,000 miles form the tops of Jupiter's clouds, a position that leaves it vulnerable to the planet's massive radiation.

The spacecraft's electronics are protected inside a radiation-resistant titanium vault, but NASA expects to end the mission after 37 orbits, each of which will last 14 days.

Read more at Discovery News

Expanding Antarctic sea ice linked to natural variability

The recent trend of increasing Antarctic sea ice extent -- seemingly at odds with climate model projections -- can largely be explained by a natural climate fluctuation, according to a new study led by the National Center for Atmospheric Research (NCAR).

The study offers evidence that the negative phase of the Interdecadal Pacific Oscillation (IPO), which is characterized by cooler-than-average sea surface temperatures in the tropical eastern Pacific, has created favorable conditions for additional Antarctic sea ice growth since 2000.

The findings, published in the journal Nature Geoscience, may resolve a longstanding mystery: Why is Antarctic sea ice expanding when climate change is causing the world to warm?

The study's authors also suggest that sea ice may begin to shrink as the IPO switches to a positive phase.

"The climate we experience during any given decade is some combination of naturally occurring variability and the planet's response to increasing greenhouse gases," said NCAR scientist Gerald Meehl, lead author of the study. "It's never all one or the other, but the combination, that is important to understand."

Study co-authors include Julie Arblaster of NCAR and Monash University in Australia, Cecilia Bitz of the University of Washington, Christine Chung of the Australian Bureau of Meteorology, and NCAR scientist Haiyan Teng. The study was funded by the U.S. Department of Energy and by the National Science Foundation, which sponsors NCAR.

Expanding ice

The sea ice surrounding Antarctica has been slowly increasing in area since the satellite record began in 1979. But the rate of increase rose nearly five fold between 2000 and 2014, following the IPO transition to a negative phase in 1999.

The new study finds that when the IPO changes phase, from positive to negative or vice versa, it touches off a chain reaction of climate impacts that may ultimately affect sea ice formation at the bottom of the world.

When the IPO transitions to a negative phase, the sea surface temperatures in the tropical eastern Pacific become somewhat cooler than average when measured over a decade or two. These sea surface temperatures, in turn, change tropical precipitation, which drives large-scale changes to the winds that extend all the way down to Antarctica.

The ultimate impact is a deepening of a low-pressure system off the coast of Antarctica known as the Amundsen Sea Low. Winds generated on the western flank of this system blow sea ice northward, away from Antarctica, helping to enlarge the extent of sea ice coverage.

"Compared to the Arctic, global warming causes only weak Antarctic sea ice loss, which is why the IPO can have such a striking effect in the Antarctic," said Bitz. "There is no comparable natural variability in the Arctic that competes with global warming."

Sifting through simulations

To test if these IPO-related impacts were sufficient to cause the growth in sea ice extent observed between 2000 and 2014, the scientists first examined 262 climate simulations created by different modeling groups from around the world.

When all of those simulations are averaged, the natural variability cancels itself out. For example, simulations with a positive IPO offset those with a negative IPO. What remains is the expected impact of human-caused climate change: a decline in Antarctic sea ice extent.

But for this study, the scientists were not interested in the average. Instead, they wanted to find individual members that correctly characterized the natural variability between 2000-2014, including the negative phase of the IPO. The team discovered 10 simulations that met the criteria, and all of them showed an increase in Antarctic sea ice extent across all seasons.

"When all the models are taken together, the natural variability is averaged out, leaving only the shrinking sea ice caused by global warming," Arblaster said. "But the model simulations that happen to sync up with the observed natural variability capture the expansion of the sea ice area. And we were able to trace these changes to the equatorial eastern Pacific in our model experiments."

Read more at Science Daily

Analysis of anatomy and diet finds evolution follows least resistant path

Peter Ungar, University of Arkansas.

Evolution follows the path of least resistance, which can result in suboptimal physical traits that don't ideally match the functional need, according to a new analysis by University of Arkansas anthropologist Peter Ungar.

Ungar, distinguished professor, chair of Department of Anthropology and director of the environmental dynamics doctoral program at the University of Arkansas, detailed his findings in Science this month with coauthor Leslea Hlusko, associate professor at the University of California Berkeley.

"Paleontologists typically reconstruct past behavior by assuming that function follows form," Ungar said. "We need to look at things in a different way and consider the number of genetic steps it takes to get from one anatomy to another. There can be more than one function for a given form and different forms can serve the same function."

Ungar analyzed teeth from two human ancestors with similar dental and jaw structure and found that dental anatomy historically associated with a hard food diet was used to eat mainly plant-based diets. And while the two species had similar anatomies and teeth, their diets were different.

The Paranthropus boisei from eastern Africa and Paranthropus robustus from southern Africa are groups of species from 4.2 to 1.3 million years ago that share similar head and tooth anatomy characterized by large, flat teeth with thick enamel and jaws and faces that indicate strong chewing muscles.

Those characteristics have often been interpreted as adaptive for crushing hard foods. Ungar and his colleagues analyzed the microwear on the teeth and used previously published data on carbon isotopes to conclude that P. robustus had a diet of plant foods and only occasional consumption of hard objects like nuts or roots, while the microwear and isotope values on the teeth of P. boisei indicate it consumed softer, tougher and possibly more abrasive foods like grasses.

"So despite their similar masticatory morphology, chemical and wear traces of the foods eaten suggest that these two species differed markedly in their diets," Ungar said.

And neither diet matched previous inferences that the large muscles and facial structure indicated a diet of hard, crunchy food.

More crested molars like those in gorillas would be more efficient in tearing fibrous plant material, but flatter molars with thicker enamel, like those of modern humans, advanced through the genetic record.

Ungar said the form of the tooth and jaw anatomy in this case is ideal for the diets these hominins ate, but it took fewer genetic changes to get there. Thicker enamel with a simpler tooth architecture was more adaptable for a variety of challenging diets through time, so it carried on as the human species developed.

Read more at Science Daily

First sleeper goby cavefish in Western Hemisphere

The Oaxaca Cave Sleeper has not been collected or seen in more than 20 years and lives in a cave system threatened by damming.

Researchers have described a new genus and species of cavefish from Mexico -- the Oaxaca Cave Sleeper. It has not been collected or seen in more than 20 years and lives in a cave system threatened by damming. Less than 0.5 percent of all fish species are cave-adapted and most of them are endangered because their cave habitats are limited and vulnerable to environmental threats.

This new species, Caecieleotris morrisi, is a sleeper goby in the family Eleotridae, and is the first cave-adapted member of this group to be found in the Western Hemisphere. All previous cave-adapted members of this family are from the Indian Ocean.

There are only 13 known individuals of this new species, which were all taken during one collecting event. The researchers examined and compared them to other known species and ultimately created a new genus for the species, because it does not resemble other known sleeper gobies. The Oaxaca Cave Sleeper is morphologically adapted to the cave environment. It does not have eyes or pigment, but it has a shovel-shaped head and well-developed sensory papillae, which contain its taste buds. Curator of Fishes at the LSU Museum of Natural Science Prosanta Chakrabarty and U.S. Geological Survey Research Fish Biologist Stephen Walsh discovered and described the Oaxaca Cave Sleeper. Their research was published in Copeia this month. Chakrabarty presented a TED talk on this research recently.

Individuals of this new species have been kept preserved in natural history collections for more than 20 years, waiting to be described. Despite being potentially extinct, natural history museums saved this new species from being completely unknown. This new species calls attention to the importance of natural history museums like the LSU Museum of Natural Science.

From Science Daily

Injectable biomaterial could be used to manipulate organ behavior

In the campy 1966 science fiction movie "Fantastic Voyage," scientists miniaturize a submarine with themselves inside and travel through the body of a colleague to break up a potentially fatal blood clot. Right. Micro-humans aside, imagine the inflammation that metal sub would cause.

Ideally, injectable or implantable medical devices should not only be small and electrically functional, they should be soft, like the body tissues with which they interact. Scientists from two UChicago labs set out to see if they could design a material with all three of those properties.

The material they came up with, published online June 27, 2016, in Nature Materials, forms the basis of an ingenious light-activated injectable device that could eventually be used to stimulate nerve cells and manipulate the behavior of muscles and organs.

"Most traditional materials for implants are very rigid and bulky, especially if you want to do electrical stimulation," said Bozhi Tian, an assistant professor in chemistry whose lab collaborated with that of neuroscientist Francisco Bezanilla on the research.

The new material, in contrast, is soft and tiny -- particles just a few micrometers in diameter (far less than the width of a human hair) that disperse easily in a saline solution so they can be injected. The particles also degrade naturally inside the body after a few months, so no surgery would be needed to remove them.

Nanoscale 'sponge'
Each particle is built of two types of silicon that together form a structure full of nano-scale pores, like a tiny sponge. And like a sponge, it is squishy -- a hundred to a thousand times less rigid than the familiar crystalline silicon used in transistors and solar cells. "It is comparable to the rigidity of the collagen fibers in our bodies," said Yuanwen Jiang, Tian's graduate student. "So we're creating a material that matches the rigidity of real tissue."

The material constitutes half of an electrical device that creates itself spontaneously when one of the silicon particles is injected into a cell culture, or, eventually, a human body. The particle attaches to a cell, making an interface with the cell's plasma membrane. Those two elements together -- cell membrane plus particle -- form a unit that generates current when light is shined on the silicon particle.

"You don't need to inject the entire device; you just need to inject one component," João L. Carvalho-de-Souza , Bezanilla's postdoc said. "This single particle connection with the cell membrane allows sufficient generation of current that could be used to stimulate the cell and change its activity. After you achieve your therapeutic goal, the material degrades naturally. And if you want to do therapy again, you do another injection."

The scientists built the particles using a process they call nano-casting. They fabricate a silicon dioxide mold composed of tiny channels -- "nano-wires" -- about seven nanometers in diameter (less than 10,000 times smaller than the width of a human hair) connected by much smaller "micro-bridges." Into the mold they inject silane gas, which fills the pores and channels and decomposes into silicon.

And this is where things get particularly cunning. The scientists exploit the fact the smaller an object is, the more the atoms on its surface dominate its reactions to what is around it. The micro-bridges are minute, so most of their atoms are on the surface. These interact with oxygen that is present in the silicon dioxide mold, creating micro-bridges made of oxidized silicon gleaned from materials at hand. The much larger nano-wires have proportionately fewer surface atoms, are much less interactive, and remain mostly pure silicon.

"This is the beauty of nanoscience," Jiang said. "It allows you to engineer chemical compositions just by manipulating the size of things."

Web-like nanostructure

Finally, the mold is dissolved. What remains is a web-like structure of silicon nano-wires connected by micro-bridges of oxidized silicon that can absorb water and help increase the structure's softness. The pure silicon retains its ability to absorb light.

The scientists have added the particles onto neurons in culture in the lab, shone light on the particles, and seen current flow into the neurons which activates the cells. The next step is to see what happens in living animals. They are particularly interested in stimulating nerves in the peripheral nervous system that connect to organs. These nerves are relatively close to the surface of the body, so near-infra-red wavelength light can reach them through the skin.

Tian imagines using the light-activated devices to engineer human tissue and create artificial organs to replace damaged ones. Currently, scientists can make engineered organs with the correct form but not the ideal function.

To get a lab-built organ to function properly, they will need to be able to manipulate individual cells in the engineered tissue. The injectable device would allow a scientist to do that, tweaking an individual cell using a tightly focused beam of light like a mechanic reaching into an engine and turning a single bolt. The possibility of doing this kind of synthetic biology without genetic engineering is enticing.

Read more at Science Daily