Scientists discover what powers celestial phenomenon STEVE

Amateur astronomer's photograph used in the new research. The photograph was taken on May 8, 2016, in Keller, Wash. The major structures are two bands of upper atmospheric emissions 160 kilometers (100 miles) above the ground, a mauve arc and green picket fence. The black objects at the bottom are trees. The background star constellations include Gemini and Ursa Major.

The celestial phenomenon known as STEVE is likely caused by a combination of heating of charged particles in the atmosphere and energetic electrons like those that power the aurora, according to new research. In a new study, scientists found STEVE's source region in space and identified two mechanisms that cause it.

Last year, the obscure atmospheric lights became an internet sensation. Typical auroras, the northern and southern lights, are usually seen as swirling green ribbons spreading across the sky. But STEVE is a thin ribbon of pinkish-red or mauve-colored light stretching from east to west, farther south than where auroras usually appear. Even more strange, STEVE is sometimes joined by green vertical columns of light nicknamed the "picket fence."

Auroras are produced by glowing oxygen and nitrogen atoms in Earth's upper atmosphere, excited by charged particles streaming in from the near-Earth magnetic environment called the magnetosphere. Scientists didn't know if STEVE was a kind of aurora, but a 2018 study found its glow is not due to charged particles raining down into Earth's upper atmosphere.

The authors of the 2018 study dubbed STEVE a kind of "sky-glow" that is distinct from the aurora, but were unsure exactly what was causing it. Complicating the matter was the fact that STEVE can appear during solar-induced magnetic storms around Earth that power the brightest auroral lights.

Authors of a new study published in AGU's journal Geophysical Research Letters analyzed satellite data and ground images of STEVE events and conclude that the reddish arc and green picket fence are two distinct phenomena arising from different processes. The picket fence is caused by a mechanism similar to typical auroras, but STEVE's mauve streaks are caused by heating of charged particles higher up in the atmosphere, similar to what causes light bulbs to glow.

"Aurora is defined by particle precipitation, electrons and protons actually falling into our atmosphere, whereas the STEVE atmospheric glow comes from heating without particle precipitation," said Bea Gallardo-Lacourt, a space physicist at the University of Calgary and co-author of the new study. "The precipitating electrons that cause the green picket fence are thus aurora, though this occurs outside the auroral zone, so it's indeed unique."

Images of STEVE are beautiful in themselves, but they also provide a visible way to study the invisible, complex charged particle flows in Earth's magnetosphere, according to the study's authors. The new results help scientists better understand how particle flows develop in the ionosphere, which is important goal because such disturbances can interfere with radio communications and affect GPS signals.

Where does STEVE come from?

In the new study, researchers wanted to find out what powers STEVE and if it occurs in both the Northern and Southern Hemispheres at the same time. They analyzed data from several satellites passing overhead during STEVE events in April 2008 and May 2016 to measure the electric and magnetic fields in Earth's magnetosphere at the time.

The researchers then coupled the satellite data with photos of STEVE taken by amateur auroral photographers to figure out what causes the unusual glow. They found that during STEVE, a flowing "river" of charged particles in Earth's ionosphere collide, creating friction that heats the particles and causes them to emit mauve light. Incandescent light bulbs work in much the same way, where electricity heats a filament of tungsten until it's hot enough to glow.

Interestingly, the study found the picket fence is powered by energetic electrons streaming from space thousands of kilometers above Earth. While similar to the process that creates typical auroras, these electrons impact the atmosphere far south of usual auroral latitudes. The satellite data showed high-frequency waves moving from Earth's magnetosphere to its ionosphere can energize electrons and knock them out of the magnetosphere to create the striped picket fence display.

The researchers also found the picket fence occurs in both hemispheres at the same time, supporting the conclusion that its source is high enough above Earth to feed energy to both hemispheres simultaneously.

Public involvement has been crucial for STEVE research by providing ground-based images and precise time and location data, according to Toshi Nishimura, a space physicist at Boston University and lead author of the new study.

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New fallout from 'the collision that changed the world'

Neither the continents nor the oceans have always looked the way they do now. These 'paleomaps' show how the continents and oceans appeared before (top) and during (bottom) 'the collision that changed the world,' when the landmass that is now the Indian subcontinent rammed northward into Asia, closing the Tethys Sea and building the Himalayas. Global ocean levels were higher then, creating salty shallow seas (pale blue) that covered much of North Africa and parts of each of the continents. A team of Princeton researchers, using samples gathered at the three starred locations, created an unprecedented record of ocean nitrogen and oxygen levels from 70 million years ago through 30 million years ago that shows a major shift in ocean chemistry after the India-Asia collision. Another shift came 35 million years ago, when Antarctica began accumulating ice and global sea levels fell.

When the landmass that is now the Indian subcontinent slammed into Asia about 50 million years ago, the collision changed the configuration of the continents, the landscape, global climate and more. Now a team of Princeton University scientists has identified one more effect: the oxygen in the world's oceans increased, altering the conditions for life.

"These results are different from anything people have previously seen," said Emma Kast, a graduate student in geosciences and the lead author on a paper coming out in Science on April 26. "The magnitude of the reconstructed change took us by surprise."

Kast used microscopic seashells to create a record of ocean nitrogen over a period from 70 million years ago -- shortly before the extinction of the dinosaurs -- until 30 million years ago. This record is an enormous contribution to the field of global climate studies, said John Higgins, an associate professor of geosciences at Princeton and a co-author on the paper.

"In our field, there are records that you look at as fundamental, that need to be explained by any sort of hypothesis that wants to make biogeochemical connections," Higgins said. "Those are few and far between, in part because it's very hard to create records that go far back in time. Fifty-million-year-old rocks don't willingly give up their secrets. I would certainly consider Emma's record to be one of those fundamental records. From now on, people who want to engage with how the Earth has changed over the last 70 million years will have to engage with Emma's data."

In addition to being the most abundant gas in the atmosphere, nitrogen is key to all life on Earth. "I study nitrogen so that I can study the global environment," said Daniel Sigman, Princeton's Dusenbury Professor of Geological and Geophysical Sciences and the senior author on the paper. Sigman initiated this project with Higgins and then-Princeton postdoctoral researcher Daniel Stolper, who is now an assistant professor of Earth and planetary science at the University of California-Berkeley.

Every organism on Earth requires "fixed" nitrogen -- sometimes called "biologically available nitrogen." Nitrogen makes up 78% of our planet's atmosphere, but few organisms can "fix" it by converting the gas into a biologically useful form. In the oceans, cyanobacteria in surface waters fix nitrogen for all other ocean life. As the cyanobacteria and other creatures die and sink downward, they decompose.

Nitrogen has two stable isotopes, 15N and 14N. In oxygen-poor waters, decomposition uses up "fixed" nitrogen. This occurs with a slight preference for the lighter nitrogen isotope, 14N, so the ocean's 15N-to-14N ratio reflects its oxygen levels.

That ratio is incorporated into tiny sea creatures called foraminifera during their lives, and then preserved in their shells when they die. By analyzing their fossils -- collected by the Ocean Drilling Program from the North Atlantic, North Pacific, and South Atlantic -- Kast and her colleagues were able to reconstruct the 15N-to-14N ratio of the ancient ocean, and therefore identify past changes in oxygen levels.

Oxygen controls the distribution of marine organisms, with oxygen-poor waters being bad for most ocean life. Many past climate warming events caused decreases in ocean oxygen that limited the habitats of sea creatures, from microscopic plankton to the fish and whales that feed on them. Scientists trying to predict the impact of current and future global warming have warned that low levels of ocean oxygen could decimate marine ecosystems, including important fish populations.

When the researchers assembled their unprecedented geologic record of ocean nitrogen, they found that in the 10 million years after dinosaurs went extinct, the 15N-to-14N ratio was high, suggesting that ocean oxygen levels were low. They first thought that the warm climate of the time was responsible, as oxygen is less soluble in warmer water. But the timing told another story: the change to higher ocean oxygen occurred around 55 million years ago, during a time of continuously warm climate.

"Contrary to our first expectations, global climate was not the primary cause of this change in ocean oxygen and nitrogen cycling," Kast said. The more likely culprit? Plate tectonics. The collision of India with Asia -- dubbed "the collision that changed the world" by legendary geoscientist Wally Broecker, a founder of modern climate research -- closed off an ancient sea called the Tethys, disturbing the continental shelves and their connections with the open ocean.

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33-year study shows increasing ocean winds and wave heights

Global trends in extreme (90th percentile) wind speed over the period 1985-2018. Areas in red indicate increasing values, whereas blue indicates decreases.

Extreme ocean winds and wave heights are increasing around the globe, with the largest rise occurring in the Southern Ocean, University of Melbourne research shows.

Researchers Ian Young and Agustinus Ribal, from the University's Department of Infrastructure Engineering, analysed wind speed and wave height measurements taken from 31 different satellites between 1985-2018, consisting of approximately 4 billion observations.

The measurements were compared with more than 80 ocean buoys deployed worldwide, making it the largest and most detailed dataset of its type ever compiled.

The researchers found that extreme winds in the Southern Ocean have increased by 1.5 metres per second, or 8 per cent, over the past 30 years. Extreme waves have increased by 30 centimetres, or 5 per cent, over the same period.

As the world's oceans become stormier, Professor Young warns this has flow on effects for rising sea levels and infrastructure.

"Although increases of 5 and 8 per cent might not seem like much, if sustained into the future such changes to our climate will have major impacts," Professor Young said.

"Flooding events are caused by storm surge and associated breaking waves. The increased sea level makes these events more serious and more frequent.

"Increases in wave height, and changes in other properties such as wave direction, will further increase the probability of coastal flooding."

Professor Young said understanding changes in the Southern Ocean are important, as this is the origin for the swell that dominates the wave climate of the South Pacific, South Atlantic and Indian Oceans.

"Swells from the Southern Ocean determine the stability of beaches for much of the Southern Hemisphere, Professor Young said.

"These changes have impacts that are felt all over the world. Storm waves can increase coastal erosion, putting costal settlements and infrastructure at risk."

International teams are now working to develop the next generation of global climate models to project changes in winds and waves over the next 100 years.

Read more at Science Daily

Diamonds reveal how continents are stabilized, key to Earth's habitability

A raw diamond from Sierra Leone with sulfur-containing mineral inclusions.

The longevity of Earth's continents in the face of destructive tectonic activity is an essential geologic backdrop for the emergence of life on our planet. This stability depends on the underlying mantle attached to the landmasses. New research by a group of geoscientists from Carnegie, the Gemological Institute of America, and the University of Alberta demonstrates that diamonds can be used to reveal how a buoyant section of mantle beneath some of the continents became thick enough to provide long-term stability.

"We've found a way to use traces of sulfur from ancient volcanoes that made its way into the mantle and eventually into diamonds to provide evidence for one particular process of continent building," explained Karen Smit of the Gemological Institute of America, lead author on the group's paper, which appears this week in Science. "Our technique shows that the geologic activity that formed the West African continent was due to plate tectonic movement of ocean crust sinking into the mantle."

Diamonds may be beloved by jewelry collectors, but they are truly a geologist's best friend. Because they originate deep inside the Earth, tiny mineral grains trapped inside of a diamond, often considered undesirable in the gem trade, can reveal details about the conditions under which it formed.

"In this way, diamonds act as mineralogical emissaries from the Earth's depths," explained Carnegie co-author Steve Shirey.

About 150 to 200 kilometers, 93 to 124 miles, beneath the surface, geologic formations called mantle keels act as stabilizers for the continental crust. The material that comprises them must thicken, stabilize, and cool under the continent to form a strong, buoyant, keel that is fundamental for preserving the surface landmass against the relentless destructive forces of Earth's tectonic activity. But how this is accomplished has been a matter of debate in the scientific community.

"Solving this mystery is key to understanding how the continents came to exist in their current incarnations and how they survive on an active planet," Shirey explained. "Since this is the only tectonically active, rocky planet that we know, understanding the geology of how our continents formed is a crucial part of discerning what makes Earth habitable."

Some scientists think mantle keels form by a process called subduction, by which oceanic plates sink from the Earth's surface into its depths when one tectonic plate slides beneath another. Others think keels are created by a vertical process in which plumes of hot magma rise from much deeper in the Earth.

A geochemical tool that can detect whether the source of a mantle keel's makeup originated from surface plates or from upwelling of deeper mantle material was needed to help resolve this debate. Luckily, mantle keels have the ideal conditions for diamond formation. This means scientists can reveal a mantle keel's origin by studying inclusions from diamonds that formed in it.

The research group's analysis of sulfur-rich minerals, called sulfides, in diamonds mined in Sierra Leone indicate that the region experienced two subduction events during its history.

They were able to make this determination because the chemistry of the sulfide mineral grains is only seen in samples from Earth's surface more than 2.5 billion years ago -- before oxygen became so abundant in our planet's atmosphere. This means that the sulfur in these mineral inclusions must have once existed on the Earth's surface and was then drawn down into the mantle by subduction.

The team's comparison to diamonds from Botswana showed similar evidence of keel-creation through subduction. But comparison to diamonds mined from northern Canada does not show the same sulfur chemistry, meaning that the mantle keel in this region originated in some way that did not incorporate surface material.

The group's findings suggest that thickening and stabilization of the mantle keel beneath the West African continent happened when this section of mantle was squeezed by collision with the sinking ocean floor material. This method of keel thickening and continent stabilization is not responsible for forming the keel under a portion of northern Canada. The sulfide minerals inside Canadian diamonds do not tell the researchers how this keel formed, only how it didn't.

"Our work shows that sulfide inclusions in diamonds are a powerful tool to investigate continent construction processes," Smit concluded.

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Mysterious eruption came from Campi Flegrei caldera

View of the eastern part of the populated Campi Flegrei caldera from the Camadoli Hill. The volcano is the source of the Masseria del Monte Tuff eruption 29,000 years ago. More than 300,000 people live within this active caldera that has experienced more than 60 eruptions in the last 15,000 years. One of these recent eruptions formed the small Nisida cone that is seen lying just off the mainland. The Bay of Naples and Capri can be seen in the background.

The caldera-forming eruption of Campi Flegrei (Italy) 40,000 years ago is the largest known eruption in Europe during the last 200,000 years, but little is known about other large eruptions at the volcano prior to a more recent caldera-forming event 15,000 years ago. A new Geology article by Paul Albert and colleagues discusses a 29,000-year-old eruption, here verified as coming from Campi Flegrei, that spread a volcanic ash layer more than 150,000 square kilometers of the Mediterranean.

Knowledge of large explosive eruptions is mostly established from geological investigations of the exposed deposits found around the source volcano, with the deposits of large eruptions forming thick sequences. However, since the late 1970s, a widespread volcanic ash layer, dated at about 29,000 years ago, was commonly identified in marine and lake sediment cores from across the Mediterranean, documenting the occurrence of a large-magnitude eruption. Despite this widespread distribution and relatively young age, no clear evidence of such an event was identified at any of the main active volcanoes in the region.

In this study, the team's detailed chemical analysis (volcanic glass) of an eruption deposit found five kilometers northeast of Campi Flegrei caldera in Naples, Italy, are entirely consistent with the distinctive composition of this ash layer. This, combined with new dating of the near-source eruption deposit, verifies that Campi Flegrei was responsible for this widespread ash layer.

Constraints on the size of the eruption were determined by the team using a computational ash dispersal model which integrated the thicknesses of the near-source eruption deposits, named here the Masseria del Monte Tuff, with those of the related ash fall across the Mediterranean.

The results indicate that this eruption at Campi Flegrei caldera was similar in scale to the younger of two known large-magnitude, caldera-forming eruptions at the volcano, the Neapolitan Yellow Tuff (about 15,000 years ago). The Masseria del Monte Tuff eruption was smaller than the older caldera-forming eruption, the enormous Campanian Ignimbrite (about 40,000 years old), which dispersed ash as far as Russia (more than 2,500 km from the volcano).

The 29,000 year old Masseria del Monte Tuff eruption positioned between known caldera-forming events significantly reduces the recurrence interval of large magnitude events in the eruptive history of Campi Flegrei caldera.

In contrast to other large magnitude events at Campi Flegrei, the lack of thick, traceable, deposits for this eruption appear to be the result of the eruption dynamics and their destruction and burial by more recent activities. This research highlights the benefits of investigating explosive eruption records preserved as ash fall in sedimentary records when attempting to accurately reconstruct the tempo and magnitude of past activity at highly productive volcanoes such as Campi Flegrei.

From Science Daily

Meet Callichimaera perplexa, the platypus of crabs

The diversity of body forms among crabs, including the enigmatic Callichimaera perplexa (center).

The crab family just got a bunch of new cousins -- including a 95-million-year-old chimera species that will force scientists to rethink the definition of a crab.

An international team of researchers led by Yale paleontologist Javier Luque announced the discovery of hundreds of exceptionally well-preserved specimens from Colombia and the United States that date back to the mid-Cretaceous period of 90-95 million years ago. The cache includes hundreds of tiny comma shrimp fossils, several true shrimp, and an entirely new branch of the evolutionary tree for crabs.

The most intriguing discovery, according to the researchers, is Callichimaera perplexa, the earliest example of a swimming arthropod with paddle-like legs since the extinction of sea scorpions more than 250 million years ago. The name derives from a chimera, a mythological creature that has body features from more than one animal. Callichimaera's full name translates into "perplexing beautiful chimera."

Luque noted that Callichimaera's "unusual and cute" appearance, including its small size -- about the size of a quarter -- large compound eyes with no sockets, bent claws, leg-like mouth parts, exposed tail, and long body are features typical of pelagic crab larvae. This suggests that several of the larval traits seen in this "perplexing chimera" might have been retained and amplified in miniaturized adults via changes in the timing and rates of development. This is a process called "heterochrony," which may lead to the evolution of novel body plans.

"Callichimaera perplexa is so unique and strange that it can be considered the platypus of the crab world," said Luque. "It hints at how novel forms evolve and become so disparate through time. Usually we think of crabs as big animals with broad carapaces, strong claws, small eyes in long eyestalks, and a small tail tucked under the body. Well, Callichimaera defies all of these 'crabby' features and forces a re-think of our definition of what makes a crab a crab."

A study about the discovery appears in the April 24 online edition of the journal Science Advances.

"It is very exciting that today we keep finding completely new branches in the tree of life from a distant past, especially from regions like the tropics, which despite being hotspots of diversity today, are places we know the least about in terms of their past diversity," Luque said.

From Science Daily

The first laser radio transmitter

This device uses a frequency comb laser to emit and modulate microwaves wirelessly. The laser uses different frequencies of light beating together to generate microwave radiation. The researchers used this phenomenon to send a song wirelessly to a receiver.

You've never heard Dean Martin like this.

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences transmitted a recording of Martin's classic "Volare" wirelessly via a semiconductor laser -- the first time a laser has been used as a radio frequency transmitter.

In a paper published in the Proceedings of the National Academy of Sciences, the researchers demonstrated a laser that can emit microwaves wirelessly, modulate them, and receive external radio frequency signals.

"The research opens the door to new types of hybrid electronic-photonic devices and is the first step toward ultra-high-speed Wi-Fi," said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, at SEAS and senior author of the study.

This research builds on previous work from the Capasso Lab. In 2017, the researchers discovered that an infrared frequency comb in a quantum cascade laser could be used to generate terahertz frequencies, the submillimeter wavelengths of the electromagnetic spectrum that could move data hundreds of times faster than today's wireless platforms. In 2018, the team found that quantum cascade laser frequency combs could also act as integrated transmitters or receivers to efficiently encode information.

Now, the researchers have figured out a way to extract and transmit wireless signals from laser frequency combs.

Unlike conventional lasers, which emit a single frequency of light, laser frequency combs emit multiple frequencies simultaneously, evenly spaced to resemble the teeth of a comb. In 2018, the researchers discovered that inside the laser, the different frequencies of light beat together to generate microwave radiation. The light inside the cavity of the laser caused electrons to oscillate at microwave frequencies -- which are within the communications spectrum.

"If you want to use this device for Wi-Fi, you need to be able to put useful information in the microwave signals and extract that information from the device," said Marco Piccardo, a postdoctoral fellow at SEAS and first author of the paper.

The first thing the new device needed to transmit microwave signals was an antenna. So, the researchers etched a gap into the top electrode of the device, creating a dipole antenna (like the rabbit ears on the top of an old TV). Next, they modulated the frequency comb to encode information on the microwave radiation created by the beating light of the comb. Then, using the antenna, the microwaves are radiated out from the device, containing the encoded information. The radio signal is received by a horn antenna, filtered and sent to a computer.

The researchers also demonstrated that the laser radio could receive signals. The team was able to remotely control the behavior of the laser using microwave signals from another device.

"This all-in-one, integrated device holds great promise for wireless communication," said Piccardo. "While the dream of terahertz wireless communication is still a ways away, this research provides a clear roadmap showing how to get there."

The Harvard Office of Technology Development has protected the intellectual property relating to this project and is exploring commercialization opportunities.

Read more at Science Daily

Synthetic speech generated from brain recordings

Gopala Anumanchipalli, PhD, holding an example array of intracranial electrodes of the type used to record brain activity in the current study.

A state-of-the-art brain-machine interface created by UC San Francisco neuroscientists can generate natural-sounding synthetic speech by using brain activity to control a virtual vocal tract -- an anatomically detailed computer simulation including the lips, jaw, tongue, and larynx. The study was conducted in research participants with intact speech, but the technology could one day restore the voices of people who have lost the ability to speak due to paralysis and other forms of neurological damage.

Stroke, traumatic brain injury, and neurodegenerative diseases such as Parkinson's disease, multiple sclerosis, and amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease) often result in an irreversible loss of the ability to speak. Some people with severe speech disabilities learn to spell out their thoughts letter-by-letter using assistive devices that track very small eye or facial muscle movements. However, producing text or synthesized speech with such devices is laborious, error-prone, and painfully slow, typically permitting a maximum of 10 words per minute, compared to the 100-150 words per minute of natural speech.

The new system being developed in the laboratory of Edward Chang, MD -- described April 24, 2019 in Nature -- demonstrates that it is possible to create a synthesized version of a person's voice that can be controlled by the activity of their brain's speech centers. In the future, this approach could not only restore fluent communication to individuals with severe speech disability, the authors say, but could also reproduce some of the musicality of the human voice that conveys the speaker's emotions and personality.

"For the first time, this study demonstrates that we can generate entire spoken sentences based on an individual's brain activity," said Chang, a professor of neurological surgery and member of the UCSF Weill Institute for Neuroscience. "This is an exhilarating proof of principle that with technology that is already within reach, we should be able to build a device that is clinically viable in patients with speech loss."

Virtual Vocal Tract Improves Naturalistic Speech Synthesis

The research was led by Gopala Anumanchipalli, PhD, a speech scientist, and Josh Chartier, a bioengineering graduate student in the Chang lab. It builds on a recent study in which the pair described for the first time how the human brain's speech centers choreograph the movements of the lips, jaw, tongue, and other vocal tract components to produce fluent speech.

From that work, Anumanchipalli and Chartier realized that previous attempts to directly decode speech from brain activity might have met with limited success because these brain regions do not directly represent the acoustic properties of speech sounds, but rather the instructions needed to coordinate the movements of the mouth and throat during speech.

"The relationship between the movements of the vocal tract and the speech sounds that are produced is a complicated one," Anumanchipalli said. "We reasoned that if these speech centers in the brain are encoding movements rather than sounds, we should try to do the same in decoding those signals."

In their new study, Anumancipali and Chartier asked five volunteers being treated at the UCSF Epilepsy Center -- patients with intact speech who had electrodes temporarily implanted in their brains to map the source of their seizures in preparation for neurosurgery -- to read several hundred sentences aloud while the researchers recorded activity from a brain region known to be involved in language production.

Based on the audio recordings of participants' voices, the researchers used linguistic principles to reverse engineer the vocal tract movements needed to produce those sounds: pressing the lips together here, tightening vocal cords there, shifting the tip of the tongue to the roof of the mouth, then relaxing it, and so on.

This detailed mapping of sound to anatomy allowed the scientists to create a realistic virtual vocal tract for each participant that could be controlled by their brain activity. This comprised two "neural network" machine learning algorithms: a decoder that transforms brain activity patterns produced during speech into movements of the virtual vocal tract, and a synthesizer that converts these vocal tract movements into a synthetic approximation of the participant's voice.

The synthetic speech produced by these algorithms was significantly better than synthetic speech directly decoded from participants' brain activity without the inclusion of simulations of the speakers' vocal tracts, the researchers found. The algorithms produced sentences that were understandable to hundreds of human listeners in crowdsourced transcription tests conducted on the Amazon Mechanical Turk platform.

As is the case with natural speech, the transcribers were more successful when they were given shorter lists of words to choose from, as would be the case with caregivers who are primed to the kinds of phrases or requests patients might utter. The transcribers accurately identified 69 percent of synthesized words from lists of 25 alternatives and transcribed 43 percent of sentences with perfect accuracy. With a more challenging 50 words to choose from, transcribers' overall accuracy dropped to 47 percent, though they were still able to understand 21 percent of synthesized sentences perfectly.

"We still have a ways to go to perfectly mimic spoken language," Chartier acknowledged. "We're quite good at synthesizing slower speech sounds like 'sh' and 'z' as well as maintaining the rhythms and intonations of speech and the speaker's gender and identity, but some of the more abrupt sounds like 'b's and 'p's get a bit fuzzy. Still, the levels of accuracy we produced here would be an amazing improvement in real-time communication compared to what's currently available."

Artificial Intelligence, Linguistics, and Neuroscience Fueled Advance

The researchers are currently experimenting with higher-density electrode arrays and more advanced machine learning algorithms that they hope will improve the synthesized speech even further. The next major test for the technology is to determine whether someone who can't speak could learn to use the system without being able to train it on their own voice and to make it generalize to anything they wish to say.

Preliminary results from one of the team's research participants suggest that the researchers' anatomically based system can decode and synthesize novel sentences from participants' brain activity nearly as well as the sentences the algorithm was trained on. Even when the researchers provided the algorithm with brain activity data recorded while one participant merely mouthed sentences without sound, the system was still able to produce intelligible synthetic versions of the mimed sentences in the speaker's voice.

The researchers also found that the neural code for vocal movements partially overlapped across participants, and that one research subject's vocal tract simulation could be adapted to respond to the neural instructions recorded from another participant's brain. Together, these findings suggest that individuals with speech loss due to neurological impairment may be able to learn to control a speech prosthesis modeled on the voice of someone with intact speech.

"People who can't move their arms and legs have learned to control robotic limbs with their brains," Chartier said. "We are hopeful that one day people with speech disabilities will be able to learn to speak again using this brain-controlled artificial vocal tract."

Read more at Science Daily

New Hubble measurements confirm universe is expanding faster than expected

This is a ground-based telescope's view of the Large Magellanic Cloud, a satellite galaxy of our Milky Way. The inset image, taken by the Hubble Space Telescope, reveals one of many star clusters scattered throughout the dwarf galaxy.

New measurements from NASA's Hubble Space Telescope confirm that the Universe is expanding about 9% faster than expected based on its trajectory seen shortly after the big bang, astronomers say.

The new measurements, published April 25 in the Astrophysical Journal Letters, reduce the chances that the disparity is an accident from 1 in 3,000 to only 1 in 100,000 and suggest that new physics may be needed to better understand the cosmos.

"This mismatch has been growing and has now reached a point that is really impossible to dismiss as a fluke. This is not what we expected," says Adam Riess, Bloomberg Distinguished Professor of Physics and Astronomy at The Johns Hopkins University, Nobel Laureate and the project's leader.

In this study, Riess and his SH0ES (Supernovae, H0, for the Equation of State) Team analyzed light from 70 stars in our neighboring galaxy, the Large Magellanic Cloud, with a new method that allowed for capturing quick images of these stars. The stars, called Cepheid variables, brighten and dim at predictable rates that are used to measure nearby intergalactic distances.

The usual method for measuring the stars is incredibly time-consuming; the Hubble can only observe one star for every 90-minute orbit around Earth. Using their new method called DASH (Drift And Shift), the researchers using Hubble as a "point-and-shoot" camera to look at groups of Cepheids, thereby allowing the team to observe a dozen Cepheids in the same amount of time it would normally take to observe just one.

With this new data, Riess and the team were able to strengthen the foundation of the cosmic distance ladder, which is used to determine distances within the Universe, and calculate the Hubble constant, a value of how fast the cosmos expands over time.

The team combined their Hubble measurements with another set of observations, made by the Araucaria Project, a collaboration between astronomers from institutions in Chile, the U.S., and Europe. This group made distance measurements to the Large Magellanic Cloud by observing the dimming of light as one star passes in front of its partner in eclipsing binary-star systems.

The combined measurements helped the SH0ES team refine the Cepheids' true brightness. With this more accurate result, the team could then "tighten the bolts" of the rest of the distance ladder that uses exploding stars called supernovae to extend deeper into space.

As the team's measurements have become more precise, their calculation of the Hubble constant has remained at odds with the expected value derived from observations of the early universe's expansion by the European Space Agency's Planck satellite based on conditions Planck observed 380,000 years after the Big Bang.

"This is not just two experiments disagreeing," Riess explained. "We are measuring something fundamentally different. One is a measurement of how fast the universe is expanding today, as we see it. The other is a prediction based on the physics of the early universe and on measurements of how fast it ought to be expanding. If these values don't agree, there becomes a very strong likelihood that we're missing something in the cosmological model that connects the two eras."

Read more at Science Daily

Why unique finches keep their heads of many colors

Gouldian Finch.

There appears to be an underlying selection mechanism at work among Gouldian Finches -- a mechanism that allows this species to produce and maintain individuals with red heads, black heads, and yellow heads. Research by scientists from the the University of Sheffield in the United Kingdom, the Cornell Lab of Ornithology, and other institutions, reveals what this additional evolutionary process might be. Findings were published today in the journal Nature Communications.

"Most people have heard of natural selection," says lead author Kang-Wook Kim at the University of Sheffield. "But 'survival of the fittest' cannot explain the color diversity we see in the Gouldian Finch. We demonstrate that there is another evolutionary process -- balancing selection -- that has maintained the black or red head color over thousands of generations."

The yellow-headed type (actually more orange) is produced by a completely different mechanism that is not yet understood. Yellow-headed Gouldian Finches make up less than one percent of the wild population.

"Having distinct multiple color types -- a polymorphism -- maintained within a species for a long time is extremely rare," explains co-author David Toews, who did this work as a postdoctoral researcher at the Cornell Lab and who is now at Pennsylvania State University. "Natural selection is typically thought of in a linear fashion -- a mutation changes a trait which then confers some reproductive or survival advantage, which results in more offspring, and the trait eventually becomes the sole type in the population."

Studies from Macquarie University in Australia have shown the red-headed finches have the apparent advantage. Female Gouldian Finches of all colors prefer the red-headed males, who also happen to be more dominant in the social hierarchy. So why hasn't the black-headed type disappeared? It turns out there are disadvantages to having a red head, too, such as higher levels of stress hormones in competitive situations.

"If advantages are cancelled out by concurrent disadvantages, these two color types can be maintained -- that's balancing selection," Toews says. "Red forms are not as common in the wild, so the counterbalancing pressure reduces the advantage of being red. That's super cool!"

Teams from the University of Sheffield and the Cornell Lab independently zeroed in on a particular gene called follistatin which is found on the Gouldian Finch sex chromosome and regulates melanin to produce either red- or black-headed finches. Rather than competing, the two teams decided to join forces and share their data. For the yellow morph, a different gene, not located on the sex chromosome, is controlling the head pigmentation, but it hasn't yet been found and it's not clear what forces are allowing the yellow morph to persist in the wild.

In another twist, Toews and co-author Scott Taylor, at the University of Colorado-Boulder, have done previous research that revealed the genes likely governing the plumage differences between North American Blue-winged and Golden-winged Warblers -- and one of those regions is in the same spot on the sex chromosome that differs among Gouldian Finches with different head colors.

Read more at Science Daily

Simple sea anemones not so simple after all

This Pachycerianthus magnus tube anemone has a surprisingly complex mitochondrial genome, Ohio State researchers found.

The tube-dwelling anemone is an ancient sea creature that resembles a prehistoric flower. The animals live slow, long and predictable lifestyles and look fairly similar from species to species.

It'd be easy to use the word "simple" when considering this relative of coral and jellyfish. But wait -- not so fast.

New research on tube anemones is challenging everything that evolutionary biologists thought they knew about sea animal genetics. The mitochondrial DNA of the tube anemone, or Ceriantharia, is a real head scratcher, from its unexpected arrangement to its previously unimagined magnitude.

Researchers, including a team from The Ohio State University, have published new findings showing that the DNA of the tube anemone does what few other species' mitochondrial genomes have been shown to do. It defies the classic doughnut shape it "should" be in and is arranged in several fragmented pieces, the number of which vary depending on the species.

On top of that, the animal now holds the record for the largest mitochondrial genome reported to date. It contains almost 81,000 base pairs, or pieces of genetic information, according to the new study, published online in the journal Scientific Reports. Human mitochondrial DNA contains fewer than 17,000 base pairs.

"These ancient animals have simple behavior and simple anatomy, and so we've thought of them as fairly simple creatures until now. But their biology is quite complicated. The genomes of these tube anemones may be more dynamic than those of more-complex and more-recent animals like snails, insects and vertebrates," said Meg Daly, a professor of evolution, ecology and organismal biology at Ohio State.

About the mitochondrial DNA that is central to this study: This isn't the DNA most of us remember learning about in school -- the instructions found within the nucleus of each cell of an organism and organized in the linear double-helix.

Rather, mitochondrial DNA is usually circular in shape and contains much less information than nuclear DNA. And it lives inside the mitochondria -- double-membraned structures found in multitudes within the cell, outside the nucleus. Mitochondria are responsible for energy production, and are sometimes called the "cellular powerhouses" of living beings.

While scientists have been able to sequence the mitochondrial DNA of other similar animals, they've hit a roadblock with these tube anemones until now, Daly said. About two decades ago, a researcher tried to create a blueprint of the mitochondrial genome based on the theory that it would be circular.

"It was impossible and no one really knew why until now," said Daly, who has made a career of studying sea anemones and their biodiversity.

Using advanced supercomputer technology, researchers examined two species of tube anemone and found that one has five linear fragments of mitochondrial DNA and the other has eight. Previously, scientists had found a linear genome in the mitochondria of the jellyfish, but the linear structure combined with the variation in size and number of fragments seen in the tube anemone is unprecedented.

"We think that the typical loop arrangement we find makes sense, because one of the advantages of the mitochondria having a circular genome is that that it replicates easily," she said.

"We've thought of this loop-shaped design as something that helps the mitochondria do its job quickly and efficiently."

Now, it is left to Daly and others who study these creatures to figure out why this might have happened from an evolutionary perspective.

"So far, there's no rhyme or reason to the anemones having this unusual mitochondrial genome," Daly said.

Sergio Stampar, the Brazilian researcher who led the study, said the two species examined in this research represent the largest groups of Ceriantharia.

"These results present a considerable 'photograph' of the group. Besides the large size of genomes, the most surprising thing that we found is the significant difference between the two species," said Stampar, who works at the Universidade Estadual Paulista in São Paulo.

Stampar said the work raises many questions, since the presumable change from circular to linear genomes in anemones should not be a simple process. A broad discussion about the evolution of several groups of related animals called Cnidaria -- which includes jellyfish, corals and sea-anemones -- is imperative, he said.

It would be tempting to expect similarities in evolutionary pressures among sea animals that are all old and relatively simple in terms of appearance and function, but this new evidence is calling that into question, Daly said.

"Maybe they all started at the same place but have been subject to different evolutionary schemes and opportunities."

Read more at Science Daily

Bacteria reveal strong individuality when navigating a maze

Behavioral experiment with bacteria: a T-maze with a chemical gradient presents bacterial cells with the choice of approaching or avoiding the attractant at each branching.

Although they are considered the simplest of all life forms, even microorganisms sense their environment and are able to actively move within it. This allows them to identify both food and harmful substances and to move towards or away from them, guided by the concentration gradient of the substance in their environment. The journey of many microbes can thus be viewed as a sequence of decisions based on chemical gradients.

The ability of cells to target or avoid particular substances is called chemotaxis. Until now, scientists have generally considered the chemotactic properties of bacteria to be a common feature of a species or population -- as if all cells behaved more or less the same. In this case, average values are sufficient to describe their movement behaviour. Now, researchers at ETH Zurich have observed the chemotaxis of bacteria in a behavioural experiment. "If you look with the appropriate technology, you'll find astonishing behavioural differences even within a population of genetically identical cells," report Mehdi Salek and Francesco Carrara, the lead authors of a study recently published in Nature Communications.

Microbes in the T-maze

Together with their colleagues in the research group led by Professor Roman Stocker at the Institute of Environmental Engineering, they have developed a special microfluidic system that allows them to observe the movement of thousands of individual bacteria in a liquid at extremely small scales. The system comprises a series of narrow channels that branch out on to a thin glass plate to form a sort of microscopic maze through which the bacteria swim.

Such mazes are often used in experimental studies of the behavioural preferences of other organisms, such as insects or worms (and also plant roots). With their microfluidic system, the ETH researchers were able for the first time to apply this traditional tool of ecologists on a microscopic scale. Their maze resembles a family tree, with a starting channel that branches out again and again towards the bottom, where the concentration of a chemical attractant is at its highest.

Decisions at the fork in the road

The bacteria all start in the same place -- and visibly divide up within the channel system as they are forced to decide at each fork whether to swim up or down the gradient of attractant. The bacteria owe their chemotactic abilities to specialised receptors that allow them to identify the attractant. In addition, they have about half a dozen flagella, which can rotate either clockwise or anti-clockwise. "Based on this, the bacterium changes its direction or continues to swim in one direction," explain Salek and Carrara.

Even within a group of genetically identical cells -- that is, clones -- the ETH researchers found individuals that were able to follow the attractant well (by navigating towards the higher concentration whenever they came to a fork), and those that were less able to negotiate the maze. The scientists attribute these behavioural differences to variations in the genetic activity of identical genes in sister cells. This means the cells have different amounts of the corresponding proteins. "There is biochemical noise in every cell. As a fundamental random component, this causes diversity of appearance and behaviour," say the researchers.

Successful population of individualists

Diversity, or heterogeneity, of chemotaxis may provide an evolutionary advantage for the bacteria, since although those skilled at chemotaxis can quickly locate and exploit locally stable food sources, their sister cells less affected by the attractant are more likely to venture into new territory, where they may encounter additional food sources in a constantly changing environment.

Read more at Science Daily

NASA's InSight detects first likely 'quake' on Mars

This image of InSight's seismometer was taken on the 110th Martian day, or sol, of the mission. The seismometer is called Seismic Experiment for Interior Structure, or SEIS.

NASA's Mars InSight lander has measured and recorded for the first time ever a likely "marsquake."

The faint seismic signal, detected by the lander's Seismic Experiment for Interior Structure (SEIS) instrument, was recorded on April 6, the lander's 128th Martian day, or sol. This is the first recorded trembling that appears to have come from inside the planet, as opposed to being caused by forces above the surface, such as wind. Scientists still are examining the data to determine the exact cause of the signal.

"InSight's first readings carry on the science that began with NASA's Apollo missions," said InSight Principal Investigator Bruce Banerdt of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. "We've been collecting background noise up until now, but this first event officially kicks off a new field: Martian seismology!"

The new seismic event was too small to provide solid data on the Martian interior, which is one of InSight's main objectives. The Martian surface is extremely quiet, allowing SEIS, InSight's specially designed seismometer, to pick up faint rumbles. In contrast, Earth's surface is quivering constantly from seismic noise created by oceans and weather. An event of this size in Southern California would be lost among dozens of tiny crackles that occur every day.

"The Martian Sol 128 event is exciting because its size and longer duration fit the profile of moonquakes detected on the lunar surface during the Apollo missions," said Lori Glaze, Planetary Science Division director at NASA Headquarters.

NASA's Apollo astronauts installed five seismometers that measured thousands of quakes while operating on the Moon between 1969 and 1977, revealing seismic activity on the Moon. Different materials can change the speed of seismic waves or reflect them, allowing scientists to use these waves to learn about the interior of the Moon and model its formation. NASA currently is planning to return astronauts to the Moon by 2024, laying the foundation that will eventually enable human exploration of Mars.

InSight's seismometer, which the lander placed on the planet's surface on Dec. 19, 2018, will enable scientists to gather similar data about Mars. By studying the deep interior of Mars, they hope to learn how other rocky worlds, including Earth and the Moon, formed.

Three other seismic signals occurred on March 14 (Sol 105), April 10 (Sol 132) and April 11 (Sol 133). Detected by SEIS' more sensitive Very Broad Band sensors, these signals were even smaller than the Sol 128 event and more ambiguous in origin. The team will continue to study these events to try to determine their cause.

Regardless of its cause, the Sol 128 signal is an exciting milestone for the team.

"We've been waiting months for a signal like this," said Philippe Lognonné, SEIS team lead at the Institut de Physique du Globe de Paris (IPGP) in France. "It's so exciting to finally have proof that Mars is still seismically active. We're looking forward to sharing detailed results once we've had a chance to analyze them."

Most people are familiar with quakes on Earth, which occur on faults created by the motion of tectonic plates. Mars and the Moon do not have tectonic plates, but they still experience quakes -- in their cases, caused by a continual process of cooling and contraction that creates stress. This stress builds over time, until it is strong enough to break the crust, causing a quake.

Detecting these tiny quakes required a huge feat of engineering. On Earth, high-quality seismometers often are sealed in underground vaults to isolate them from changes in temperature and weather. InSight's instrument has several ingenious insulating barriers, including a cover built by JPL called the Wind and Thermal Shield, to protect it from the planet's extreme temperature changes and high winds.

SEIS has surpassed the team's expectations in terms of its sensitivity. The instrument was provided for InSight by the French space agency, Centre National d'Études Spatiales (CNES), while these first seismic events were identified by InSight's Marsquake Service team, led by the Swiss Federal Institute of Technology.

"We are delighted about this first achievement and are eager to make many similar measurements with SEIS in the years to come," said Charles Yana, SEIS mission operations manager at CNES.

JPL manages InSight for NASA's Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supports spacecraft operations for the mission.

Read more at Science Daily

Brains of blind people adapt to sharpen sense of hearing, study shows

Left: Researchers began by measuring responses in the auditory cortex to find a map of how frequency responses were represented in the brain. The warm colors represent regions of the brain that showed the greatest response to low-pitched tones, while blue colors represent regions that responded more to high-pitched tones. Right: When researchers examined the range of frequencies each vertex of the brain was selective to, they found tuning tended to be narrower for blind individuals, which may underlie the enhanced ability of blind individuals to pick out and identify sounds in the environment.

Research has shown that people who are born blind or become blind early in life often have a more nuanced sense of hearing, especially when it comes to musical abilities and tracking moving objects in space (imagine crossing a busy road using sound alone). For decades scientists have wondered what changes in the brain might underlie these enhanced auditory abilities.

Now, a pair of research papers published the week of April 22 from the University of Washington -- one in the Journal of Neuroscience, the other in the Proceedings of the National Academy of Sciences -- use functional MRI to identify two differences in the brains of blind individuals that might be responsible for their abilities to make better use of auditory information.

"There's this idea that blind people are good at auditory tasks, because they have to make their way in the world without visual information. We wanted to explore how this happens in the brain," said Ione Fine, a UW professor of psychology and the senior author on both studies.

Instead of simply looking to see which parts of the brain were most active while listening, both studies examined the sensitivity of the brain to subtle differences in auditory frequency.

"We weren't measuring how rapidly neurons fire, but rather how accurately populations of neurons represent information about sound," said Kelly Chang, a graduate student in the UW Department of Psychology and lead author on the Journal of Neuroscience paper.

That study found that in the auditory cortex, individuals who are blind showed narrower neural "tuning" than sighted subjects in discerning small differences in sound frequency.

"This is the first study to show that blindness results in plasticity in the auditory cortex. This is important because this is an area of the brain that receives very similar auditory information in blind and sighted individuals," Fine said. "But in blind individuals, more information needs to be extracted from sound -- and this region seems to develop enhanced capacities as a result.

"This provides an elegant example of how the development of abilities within infant brains is influenced by the environment they grow up in."

The second study examined how the brains of people who are born blind or become blind early in life -- referred to as "early blind" individuals -- represent moving objects in space. The research team showed that an area of the brain called the hMT+ -- which in sighted individuals is responsible for tracking moving visual objects -- shows neural responses that reflect both the motion and the frequency of auditory signals in blind individuals. This suggests that in blind people, area hMT+ is recruited to play an analogous role -- tracking moving auditory objects, such as cars, or the footsteps of the people around them.

The paper in the Journal of Neuroscience involved two teams -- one at the UW, the other at the University of Oxford in the United Kingdom. Both teams measured neural responses in study participants while participants listened to a sequence of Morse code-like tones that differed in frequency while the fMRI machine recorded brain activity. The research teams found that in the blind participants, the auditory cortex more accurately represented the frequency of each sound.

"Our study shows that the brains of blind individuals are better able to represent frequencies," Chang said. "For a sighted person, having an accurate representation of sound isn't as important because they have sight to help them recognize objects, while blind individuals only have auditory information. This gives us an idea of what changes in the brain explain why blind people are better at picking out and identifying sounds in the environment."

The Proceedings of the National Academy of Sciences study examined how the brain's "recruitment" of the hMT+ region might help blind people track the motion of objects using sound. Participants once again listened to tones that differed in auditory frequency, but this time the tones sounded like they were moving. As has been found in previous studies, in blind individuals the neural responses in area hMT+ contained information about the direction of motion of the sounds, whereas in the sighted participants these sounds did not produce significant neural activity.

By using sounds that varied in frequency, the researchers could show that in blind individuals, the hMT+ region was selective for the frequency as well as the motion of sounds, supporting the idea that this region might help blind individuals track moving objects in space.

"These results suggest that early blindness results in visual areas being recruited to solve auditory tasks in a relatively sophisticated way," Fine said.

This study also included two sight-recovery subjects -- individuals who had been blind from infancy until adulthood, when sight was restored via surgery in adulthood. In these individuals, area hMT+ seemed to serve a dual purpose, capable of processing both auditory and visual motion. The inclusion of people who used to be visually impaired lends additional evidence to the idea that this plasticity in the brain happens early in development, Fine said, because the results show that their brains made the shift to auditory processing as a result of their early-life blindness, yet maintains these abilities even after sight was restored in adulthood.

According to Fine, this research extends current knowledge about how the brain develops because the team was not only looking at which regions of the brain are altered as a result of blindness, but also examining precisely what sort of changes -- specifically, sensitivity to frequency -- might explain how early blind people make sense of the world. As one of the study participants described it, "You see with your eyes, I see with my ears."

Read more at Science Daily

Arctic warming will accelerate climate change and impact global economy

Iceberg in Greenland.

Carbon released into the atmosphere by the increasing loss of Arctic permafrost, combined with higher solar absorption by Earth's surface due to the melting of sea ice and land snow, will accelerate climate change -- and have a multi-trillion dollar impact on the world economy.

A new paper in Nature Communications reveals a combination of these factors has the potential to increase the long-term economic impact of climate change by just under $70 trillion, under mitigation levels consistent with current national pledges to cut carbon emissions (5% of the estimated total cost of climate change for this scenario).

Under the Intergovernmental Panel on Climate Change (IPCC) Paris Agreement target of global temperature rises being limited to 1.5C from pre-industrial levels, the extra impact drops to $25 trillion (4% of the total cost for this scenario). In both cases, the primary driver behind the additional costs is the emitted permafrost carbon.

The interdisciplinary research team hope their assessments will provide a better understanding of the socio-economic risks from climate change under different scenarios and help guide policy-makers towards prudent decisions on emissions reduction targets.

Researchers explored simulations of complex, state-of-the-art, physical models to quantify the strength of the permafrost carbon feedback (PCF), driven by the additional carbon released from thawing permafrost, and of the surface albedo feedback (SAF), driven by the extra solar energy absorbed by Earth's surface as the white sea ice and land snow cover declines, exposing darker ocean and land.

Nearly all climate policy studies to date have implied a constant SAF and zero PCF. However, recent observations and computer models show the permafrost feedback is the stronger of the two and that both are nonlinear, their strength changing in complex ways as the climate warms. This affects their impact on both the global climate and economy.

"Arctic sea ice and land snow currently contribute around a third each to the global albedo feedback," said lead author Dmitry Yumashev, of the Pentland Centre for Sustainability in Business at Lancaster University.

"These two components are set to peak for global temperatures within the range covered by the Paris Agreement, but if the climate warms further, the summer and spring sea ice and land snow covers will retreat further north and the albedo feedback will actually weaken.

"The permafrost feedback, however, grows progressively stronger in warmer climates. Both feedbacks are characterised by nonlinear responses to warming, including a varying lag between rising global temperature and permafrost carbon emissions.

"Compared with zero PCF and constant SAF from present-day climate -- legacy values used in climate policy modelling to this point -- the combined nonlinear PCF and SAF cause significant extra warming globally under low and medium emissions scenarios.

Low emissions scenarios in the study include meeting the 1.5°C and 2°C Paris Agreement targets relative to pre-industrial conditions by 2100, while medium emissions scenarios include mitigation levels consistent with current national pledges (NDCs). Under the NDCs, the world is set to warm by around 3°C relative to pre-industrial by 2100.

High emissions scenarios, such as the current business as usual trajectory (BaU) -- expected to lead to around 4°C of warming by 2100 and cause by far the highest impacts on ecosystems and societies -- are also included. Under these, the strength of the PCF reaches its peak and does not increase further, while the continued weakening of the SAF gradually cancels the warming effect of the PCF.

For the purposes of the research, other major planetary feedbacks, such as those driven by changes in clouds and water vapour in response to warming, are assumed to remain constant, supported by the last two generations of climate models.

Under all scenarios, using the nonlinear Arctic feedbacks compared to previous constant values leads to an increase to the total cost of climate change, consisting of the mitigation costs of cutting emissions, climate adaptation costs and residual climate-related impacts. The increases occur primarily through additional temperature-driven impacts on economy, ecosystems and human health, and additional impacts from sea level rise.

All costs were estimated using simulations in specially developed integrated assessment model PAGE-ICE, which includes simple statistical representations of the Arctic feedbacks derived from complex models. It has multiple updates to climate science and economics, including up-to-date uncertainty estimates.

Under the NDCs scenario, the additional estimated impact based on thousands of simulations of the nonlinear PCF and SAF is just under $70 trillion compared to their previously used values -- exceeding by around 10 times current estimates for long-terms economic gains from transit shipping routes and mineral resource extraction in the Arctic region.

With previous estimates for Arctic feedbacks, the total cost of climate change associated with the 1.5C and 2C scenarios is virtually the same and is around $600 trillion -- in comparison, the estimated cost of business as usual is around $2000 trillion. Nonlinear PCF and SAF add further $25 trillion to the $600 trillion figure for the 1.5C scenario and $34 trillion for the 2C scenario. Thus, the nonlinear Arctic feedbacks make the more ambitious 1.5C target marginally more economically attractive.

Dr Yumashev added: "Our findings support the need for more proactive mitigation measures to keep global temperature rise well below 2C.

Read more at Science Daily

Quantum gas turns supersolid

Several tens of thousands of particles spontaneously organize in a self-determined crystalline structure while sharing the same macroscopic wavefunction -- hallmarks of supersolidity.

Supersolidity is a paradoxical state where the matter is both crystallized and superfluid. Predicted 50 years ago, such a counter-intuitive phase, featuring rather antithetic properties, has been long searched in superfluid helium. However, after decades of theoretical and experimental efforts, an unambiguous proof of supersolidity in these systems is still missing. Two research teams led by Francesca Ferlaino, one at the Institute for Experimental Physics at the University of Innsbruck and one at the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences now report on the observation of hallmarks of this exotic state in ultracold atomic gases.

While so far, most work has focused on helium, researchers have recently turned to atomic gases -- in particular, those with strong dipolar interactions. The team of Francesca Ferlaino has been investigating quantum gases made of atoms with a strong dipolar character for a long time. "Recent experiments have revealed that such gases exhibit fundamental similarities with superfluid helium," says Lauriane Chomaz referring to experimental achievements in Innsbruck and in Stuttgart over the last few years. "These features lay the groundwork for reaching a state where the several tens of thousands of particles of the gas spontaneously organize in a self-determined crystalline structure while sharing the same macroscopic wavefunction -- hallmarks of supersolidity."

The researchers in Innsbruck experimentally created states showing these characteristics of supersolidity by tuning the interaction strength between the particles, in both erbium and dysprosium quantum gases. "While in erbium the supersolid behavior is only transient, in line with recent beautiful experiments in Pisa and in Stuttgart, our dysprosium realization shows an unprecedented stability," says Francesca Ferlaino. "Here, the supersolid behavior not only lives long but can also be directly achieved via evaporative cooling, starting from a thermal sample." Like blowing over a cup of tea, the principle here is to remove the particles that carry the most of energies so that the gas becomes cooler and cooler and finally reaches a quantum-degenerate stationary state with supersolid properties at thermal equilibrium.

This offers exciting prospects for near-future experiments and theories as the supersolid state in this setting is little affected by dissipative dynamics or excitations, thus paving the way for probing its excitation spectrum and its superfluid behavior. The work was financially supported by the Austrian Science Fund FWF, the Austrian Academy of Sciences and the European Union.

Read more at Science Daily

Defying the laws of physics? Engineers demonstrate bubbles of sand

Development of a "bubble" of lighter sand (blue) forming in heavier sand (white).

The flow of granular materials, such as sand and catalytic particles used in chemical reactors, and enables a wide range of natural phenomena, from mudslides to volcanos, as well as a broad array of industrial processes, from pharmaceutical production to carbon capture. While the motion and mixing of granular matter often display striking similarities to liquids, as in moving sand dunes, avalanches, and quicksand, the physics underlying granular flows is not as well-understood as liquid flows.

Now, a recent discovery by Chris Boyce, assistant professor of chemical engineering at Columbia Engineering, explains a new family of gravitational instabilities in granular particles of different densities that are driven by a gas-channeling mechanism not seen in fluids. In collaboration with Energy and Engineering Science Professor Christoph Müller's group at ETH Zurich, Boyce's team observed an unexpected Rayleigh-Taylor (R-T)-like instability in which lighter grains rise through heavier grains in the form of "fingers" and "granular bubbles." R-T instabilities, which are produced by the interactions of two fluids of different densities that do not mix -- oil and water, for example -- because the lighter fluid pushes aside the heavier one, have not been seen between two dry granular materials.

The study, published today in the Proceedings of the National Academy of Sciences, is the first to demonstrate that "bubbles" of lighter sand form and rise through heavier sand when the two types of sand are subject to vertical vibration and upward gas flow, similar to the bubbles that form and rise in lava lamps. The team found that, just as air and oil bubbles rise in water because they are lighter than water and do not want to mix with it, bubbles of light sand rise through heavier sand even though two types of sand like to mix.

"We think our discovery is transformational," says Boyce "We have found a granular analog of one of the last major fluid mechanical instabilities. While analogs of the other major instabilities have been discovered in granular flows in recent decades, the R-T instability has eluded direct comparison. Our findings could not only explain geological formations and processes that underlie mineral deposits, but could also be used in powder-processing technologies in the energy, construction, and pharmaceuticals industries."

Boyce's group used experimental and computational modeling to show that gas channeling through lighter particles triggers the formation of finger and bubble patterns. The gas channeling occurs because the clusters of lighter, larger particles have a higher permeability to gas flow than do the heavier, smaller grains. The R-T-like instability in granular materials arises from a competition between upward drag force increased locally by gas channeling and downward contact forces, a physical mechanism entirely different from that found in liquids.

They found that this gas-channeling mechanism also generates other gravitational instabilities, including the cascading branching of a descending granular droplet. They also demonstrated that the R-T-like instability can occur under a wide variety of gas flow and vibration conditions, forming different structures under different excitation conditions.

"These instabilities, which can be applied to a variety of systems, shed new light on granular dynamics and suggest new opportunities for patterning within granular mixtures to form new products in the pharmaceutical industry, for example," Boyce adds. "We are especially excited about the potential impact of our findings on the geological sciences -- these instabilities can help us understand how structures have formed over the long history of the Earth and predict how others may form in the future."

Read more at Science Daily

Infamous 'death roll' almost universal among crocodile species

Paleosuchus palpebrosus, also known as Cuvier's dwarf caiman.

The iconic "death roll" of alligators and crocodiles may be more common among species than previously believed, according to a new study published in Ethology, Ecology & Evolution and coauthored by a researcher at the University of Tennessee, Knoxville.

Contrary to popular belief, crocodiles can't chew, so they use a powerful bite coupled with a full-bodied twisting motion -- a death roll -- to disable, kill, and dismember prey into smaller pieces. The lethal movement is characteristic of both alligators and crocodiles and has been featured in numerous movies and nature documentaries.

Until now, the death roll had only been documented in a few of the 25 living crocodilian species, but how many actually do it?

"We conducted tests in all 25 species, and 24 of them exhibited the behavior," said lead author Stephanie Drumheller-Horton, a paleontologist and adjunct assistant professor in the Department of Earth and Planetary Sciences at UT.

For the research, Drumheller-Horton teamed up with Kent Vliet from the University of Florida and Jim Darlington, curator of reptiles at the St. Augustine Alligator Farm.

It was previously believed that slender-snouted species, like the Indian gharial, didn't roll because their diets consist of small prey like fish, eaten whole.

But it turns out that feeding isn't the only time the animals might roll.

"Aggression between individual crocodylians can become quite intense, often involving bites and death rolls in establishing dominance or competition for females," Vliet said.

Paleosuchus palpebrosus, commonly called Cuvier's dwarf caiman, is the only species that did not perform a death roll under experimental conditions. "Although, it's also possible that they were just being uncooperative," said Darlington.

And the fossil ancestors of modern crocodiles? If they share a similar body plan and lifestyle with their modern counterparts, it's likely that they could death roll, too.

"Crocodile relatives have played the role of semi-aquatic ambush predator since the Age of Dinosaurs," said Drumheller-Horton.

Whether in the Northern Territories of Australia, a lake in the Serengeti, or a watering hole in the late Cretaceous, chances are that a patient predator is waiting in the water to surprise its next meal with a burst of speed, a powerful bite, and a spinning finish.

From Science Daily

Island lizards are expert sunbathers, and researchers find it's slowing their evolution

Anolis chloris soaks up the sun while displaying.

If you've ever spent some time in the Caribbean, you might have noticed that humans are not the only organisms soaking up the sun. Anoles -- diminutive little tree lizards -- spend much of their day shuttling in and out of shade. But, according to a new study in Evolution led by assistant professor Martha Muñoz at Virginia Tech and Jhan Salazar at Universidad Icesi, this behavioral "thermoregulation" isn't just affecting their body temperature. Surprisingly, it's also slowing their evolution.

The idea that evolution can be slow on islands is actually somewhat strange. Ever since Darwin's journey to the Galapagos, islands have been recognized as hotspots of rapid evolution, resulting in many ecologically diverse species. The reason why evolution often goes into overdrive on islands has to do with the ecological opportunity presented by simplified environments. When organisms wash up on remote islands, they find themselves freed of their usual competitors and predators, which frees them to rapidly diversify to fill new niches. This phenomenon of faster evolution is often referred to as the "island effect."

Yet, the researchers discovered that physiological evolution in Anolis lizards is actually much slower on islands than on the mainland. What is causing evolution to stall?

The same ecological opportunity that frees island organisms from predators also facilitates behavioral thermoregulation. "Whereas mainland lizards spend most of their time hiding from predators, island lizards move around more, and are able to spend much of their day precisely shuttling between sun and shade," said Muñoz, assistant professor in the Department of Biological Sciences in the College of Science.

If it gets too hot, island lizards simply go find a shady spot. If it gets too cold, they can dash onto a sunny perch. By thermoregulating, island lizards are not just buffering themselves from thermal variation. They are effectively shielding themselves from natural selection. If lizards aren't exposed to extreme temperatures, then selection on physiology is weakened. The result? Slower rates of physiological evolution. Effectively, island lizards use behavioral thermoregulation like SPF against natural selection!

Jhan Salazar said, "Our results show that faster evolution on islands is not a general rule." This slower physiological evolution on islands stands in stark contrast to morphology, which has been shown to evolve faster in island anoles. When it comes to morphology and physiology on islands, it seems we are looking at different sides of the same coin. The same ecological release from predators and competition that allowed for the truly impressive amount of morphological diversification that has appeared quickly among island anoles, seems to additionally allow for more behavioral thermoregulation which slows physiological evolution.

"We are discovering that organisms are the architects of their own selective environments meaning that behavior and evolution are locked together in a delicate dance. This pas de deux tells us something important about how diversity arises in nature," said Muñoz, who is an affiliated faculty member of the Global Change Center, housed within the Fralin Life Science Institute.

From Science Daily

Hubble celebrates its 29th birthday with unrivaled view of the Southern Crab Nebula

This is the Southern Crab Nebula -- Hubble's 29th anniversary image.

This incredible image of the hourglass-shaped Southern Crab Nebula was taken to mark the NASA/ESA Hubble Space Telescope's 29th anniversary in space. The nebula, created by a binary star system, is one of the many objects that Hubble has demystified throughout its productive life. This new image adds to our understanding of the nebula and demonstrates the telescope's continued capabilities.

On 24 April 1990, the NASA/ESA Hubble Space Telescope was launched on the space shuttle Discovery. It has since revolutionised how astronomers and the general public see the Universe. The images it provides are spectacular from both a scientific and a purely aesthetic point of view.

Each year the telescope dedicates a small portion of its precious observing time to take a special anniversary image, focused on capturing particularly beautiful and meaningful objects. This year's image is the Southern Crab Nebula, and it is no exception [1].

This peculiar nebula, which exhibits nested hourglass-shaped structures, has been created by the interaction between a pair of stars at its centre. The unequal pair consists of a red giant and a white dwarf. The red giant is shedding its outer layers in the last phase of its life before it too lives out its final years as a white dwarf. Some of the red giant's ejected material is attracted by the gravity of its companion.

When enough of this cast-off material is pulled onto the white dwarf, it too ejects the material outwards in an eruption, creating the structures we see in the nebula. Eventually, the red giant will finish throwing off its outer layers, and stop feeding its white dwarf companion. Prior to this, there may also be more eruptions, creating even more intricate structures.

Astronomers did not always know this, however. The object was first written about in 1967, but was assumed to be an ordinary star until 1989, when it was observed using telescopes at the European Southern Observatory's La Silla Observatory. The resulting image showed a roughly crab-shaped extended nebula, formed by symmetrical bubbles of gas and dust.

These observations only showed the outer hourglass emanating from a bright central region that could not be resolved. It was not until Hubble observed the Southern Crab in 1998 that the entire structure came into view. This image revealed the inner nested structures, suggesting that the phenomenon that created the outer bubbles had occurred twice in the (astronomically) recent past.

It is fitting that Hubble has returned to this object twenty years after its first observation. This new image adds to the story of an active and evolving object and contributes to the story of Hubble's role in our evolving understanding of the Universe.

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Decline in measles vaccination is causing a preventable global resurgence of the disease

This is an illustration of the virus which causes measles.

In 2000, measles was declared to be eliminated in the United States, when no sustained transmission of the virus was seen in this country for more than 12 months. Today, however, the United States and many other countries that had also eliminated the disease are experiencing concerning outbreaks of measles because of declines in measles vaccine coverage. Without renewed focus on measles vaccination efforts, the disease may rebound in full force, according to a new commentary in the New England Journal of Medicine by infectious diseases experts at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and the Penn State University College of Medicine's Milton S. Hershey Medical Center.

Measles is an extremely contagious illness transmitted through respiratory droplets and aerosolized particles that can remain in the air for up to two hours. Most often seen in young children, the disease is characterized by fever, malaise, nasal congestion, conjunctivitis, cough and a red, splotchy rash. Most people with measles recover without complications within a week. However, for infants, people with immune deficiencies, and other vulnerable populations, the consequences of a measles infection can be severe. Rare complications can occur, including pneumonia, encephalitis, other secondary infections, blindness and even death. Before the measles vaccine was developed, the disease killed between two and three million people annually worldwide. Today, measles still causes more than 100,000 deaths globally each year.

Measles can be prevented with a vaccine that is both highly effective and safe. Each complication and death related to measles is a "preventable tragedy that could have been avoided through vaccination," the authors write. Some people are reluctant to vaccinate their children based on widespread misinformation about the vaccine. For example, they may fear that the vaccine raises their child's risk of autism, a falsehood based on a debunked and fraudulent claim. A very small number of people have valid medical contraindications to the measles vaccine, such as certain immunodeficiencies, but almost everyone can be safely vaccinated.

When levels of vaccine coverage fall, the weakened umbrella of protection provided by herd immunity -- indirect protection that results when a sufficiently high percentage of the community is immune to the disease -- places unvaccinated young children and immunocompromised people at greater risk. This can have disastrous consequences with measles. The authors describe a case in which a single child with measles infected 23 other children in a pediatric oncology clinic, with a fatality rate of 21 percent.

If vaccination rates continue to decline, measles outbreaks may become even more frequent, a prospect the authors describe as "alarming." This is particularly confounding, they note, since measles is one of the most easily prevented contagious illnesses. In fact, it is possible to eliminate and even eradicate the disease. However, they say, achieving this goal will require collective action on the part of parents and healthcare practitioners alike.

From Science Daily