Apr 22, 2017

In young bilingual children, two languages develop simultaneously but independently

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

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

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

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

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

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

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

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

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

Read more at Science Daily

How Venus flytrap triggers digestion

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

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

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

Glands secrete acidic vesicles to decompose prey

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

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

Conclusive analysis with carbon fibre electrodes

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

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

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

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

Stabilising effect of glutathione keeps enzymes fit

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

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

Read more at Science Daily

Apr 21, 2017

Environmental 'memories' passed on for 14 generations

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

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

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

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

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

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

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

Read more at Science Daily

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Read more at Science Daily

Genetic evidence points to nocturnal early mammals

Many modern mammals, like this wood mouse, are nocturnal, thanks to evolutionary developments such as night vision in their distant ancestors, Stanford researchers say.
Our earliest mammalian ancestors likely skulked through the dark, using their powerful night-time vision to find food and avoid reptilian predators that hunted by day. This conclusion, published by Stanford researchers April 21 in Scientific Reports, used genetic data to support existing fossil evidence suggesting that our distant relatives may have adapted to life in the dark.

The team, led by Liz Hadly, professor of biology and senior author on the paper, examined genes involved in night vision in animals throughout the evolutionary tree, looking for places where those genes became enhanced.

"This method is like using the genome as a fossil record, and with it we've shown when genes involved in night vision appear," Hadly said. "It's a very powerful way of corroborating a story that has been, up to now, only hypothesized."

Mammals versus reptiles

Mammals and reptiles share a common ancestor, with the earliest mammal-like animals appearing in the Late Triassic (about 200 million years ago). Fossil evidence suggests that early mammals had excellent hearing and sense of smell and were likely also warm-blooded. All of these features are common in their descendants, the living mammals, most of whom are nocturnal. Therefore, experts have hypothesized that early mammals were also nocturnal. This study offers direct, genetic evidence for that hypothesis.

To trace the evolution of nocturnality, the researchers studied genes that the lead author, visiting scholar Yonghua Wu, had previously found associated with night vision in certain birds, such as owls. The team members examined those night-vision genes in many mammals and reptiles, including snakes, alligators, mice, platypuses and humans. Using what they know about how those animals are related, they figured out when in their evolutionary histories, if ever, the function of these genes was enhanced.

From this, they deduced that the earliest common ancestor did not have good night vision and was instead active during the day. However, soon after the split, mammals began enhancing their night vision genes, allowing them to begin to roam at night, thus avoiding the reptiles that hunted during the day.

"Early mammals coexisted with early reptiles in the Age of the Dinosaurs and somehow escaped extinction," Wu said. "This research further supports the hypothesis that diurnal reptiles, such as lizards, snakes and their relatives, competed with mammals and may have led them to better adapt to dim light conditions."

In the millions of years that have elapsed since mammals and reptiles diverged, natural selection and evolution haven't stopped. Not all mammals are still nocturnal. Some groups of mammals have reoccupied the day, adapting in various ways to daylight activity. These animals include cheetahs, pikas, camels, elephants, and, of course, humans.

"Understanding the constant pressure to get better at seeing the world at night for over 100 million years is a beautiful way of thinking about evolution," Hadly said. "We think of it as something simple -- seeing in the light or the dark -- but these genes are being constantly refined and altered by natural selection."

Filling in our history

The methods used by these researchers could be applied to different areas of the animal evolutionary tree to learn more about the evolution of vision, including how humans made the switch to bright-light vision. This study is also an example of how little information we have about the first mammals, compared to what we know about our ancient and more compelling reptile cousins, the dinosaurs.

Read more at Science Daily

Origins of Indonesian Hobbits finally revealed

This is a reconstructed skull of Homo floresiensis.
The most comprehensive study on the bones of Homo floresiensis, a species of tiny human discovered on the Indonesian island of Flores in 2003, has found that they most likely evolved from an ancestor in Africa and not from Homo erectus as has been widely believed.

The study by The Australian National University (ANU) found Homo floresiensis, dubbed "the hobbits" due to their small stature, were most likely a sister species of Homo habilis -- one of the earliest known species of human found in Africa 1.75 million years ago.

Data from the study concluded there was no evidence for the popular theory that Homo floresiensis evolved from the much larger Homo erectus, the only other early hominid known to have lived in the region with fossils discovered on the Indonesian mainland of Java.

Study leader Dr Debbie Argue of the ANU School of Archaeology & Anthropology, said the results should help put to rest a debate that has been hotly contested ever since Homo floresiensis was discovered.

"The analyses show that on the family tree, Homo floresiensis was likely a sister species of Homo habilis. It means these two shared a common ancestor," Dr Argue said.

"It's possible that Homo floresiensis evolved in Africa and migrated, or the common ancestor moved from Africa then evolved into Homo floresiensis somewhere."

Homo floresiensis is known to have lived on Flores until as recently as 54,000 years ago.

The study was the result of an Australian Research Council grant in 2010 that enabled the researchers to explore where the newly-found species fits in the human evolutionary tree.

Where previous research had focused mostly on the skull and lower jaw, this study used 133 data points ranging across the skull, jaws, teeth, arms, legs and shoulders.

Dr Argue said none of the data supported the theory that Homo floresiensis evolved from Homo erectus.

"We looked at whether Homo floresiensis could be descended from Homo erectus," she said.

"We found that if you try and link them on the family tree, you get a very unsupported result. All the tests say it doesn't fit -- it's just not a viable theory."

Dr Argue said this was supported by the fact that in many features, such as the structure of the jaw, Homo floresiensis was more primitive than Homo erectus.

"Logically, it would be hard to understand how you could have that regression -- why would the jaw of Homo erectus evolve back to the primitive condition we see in Homo floresiensis?"

Dr Argue said the analyses could also support the theory that Homo floresiensis could have branched off earlier in the timeline, more than 1.75 million years ago.

"If this was the case Homo floresiensis would have evolved before the earliest Homo habilis, which would make it very archaic indeed," she said.

Professor Mike Lee of Flinders University and the South Australian Museum, used statistical modeling to analyse the data.

Read more at Science Daily

Apr 20, 2017

Tarantulas use their lateral eyes to calculate distance

This is the arrangement of the 4 pairs of eyes on the cephalothorax of the spider Lycosa tarantula.
The tarantula species Lycosa tarantula ambushes its prey and lives in burrows around 20 cm deep topped by a structure, a kind of turret which the tarantula build from twigs, leaves and small stones, fastened with the spider's silk. From the turret, the tarantula surprises its prey and runs to pursue it, subsequently returning to the burrow from distances between 30 and 40 cm.

L. tarantula uses path integration to return to its burrow. With this mechanism, it does not follow the same path back to its burrow; instead, it moves as though it had followed the sides of a right-angle triangle, returning along the hypotenuse.

In 1999, a research team from the Autonomous University of Madrid discovered that these animals used polarised light from the sky to know their position with respect to their nest. In the new research, the scientists wanted to go beyond this, and have analysed the role of each pair of the tarantula's eyes (they have four pairs in total) in the process of distance measurement, or odometry.

"To calculate the distance it has travelled, the animal needs an odometer that registers the route, its location with respect to the finish point, which would be the burrow, and a 'compass' to track the direction of travel," according to Joaquin Ortega Escobar, lead author of a paper published in the Journal of Experimental Biology on the function of each eye in these processes.

The 'compass' would correspond to polarised light, which the median eyes use to measure the angle; direction is detected by the anterior lateral eyes. Through this research, the scientists have learned that it is principally the anterior lateral eyes (which until now had not been analysed), and to a lesser extent the posterior lateral eyes, that help tarantulas measures the distance to their nest.

Orientation with covered eyes

"These eyes look at the substrate. Seeing as they point downwards, it seems logical to think they would have a role in measuring the distance travelled. In the experiment, we covered these eyes with a water-soluble paint and observed that instead of travelling 30 cm from the nest, which is the distance we initially set, they stopped 8.5 centimetres before they reached their objective," explains the researcher.

This explains that with those eyes covered and the other six active, they have problems determining distance. "When we uncovered them, they could return to their nests perfectly. They need the lateral anterior eyes to measure the distance," he adds.

In previous work with the lateral eyes of other animals, such as desert ants (Cataglyphis fortis), the researchers observed that animals moving across a grid of black and white bands, like those used in the tarantula study, with the ventral region of their compound eyes (the part that perceives the grid) covered did not present a significant difference in the return trip to the nest compared to when the eyes were uncovered.

"The situations of these two animals are analogous. In the case of the spider, it is the anterior lateral eye that perceives the ventral field of view, while in the ant it is the ventral region of the compound eye. Spiders have simple eyes like our own, rather than compound eyes," Ortega Escobar explains.

Read more at Science Daily

Why animals have evolved to favor one side of the brain

Why do people and animals naturally favor one side over the other, and what does it teach us about the brain's inner workings?
Most left-handers can rattle off a list of their eminent comrades-in-arms: Oprah Winfrey, Albert Einstein, and Barack Obama, just to name three, but they may want to add on cockatoos, "southpaw" squirrels, and some house cats. "Handed-ness" or left-right asymmetry is prevalent throughout the animal kingdom, including in pigeons and zebrafish. But why do people and animals naturally favor one side over the other, and what does it teach us about the brain's inner workings? Researchers explore these questions in a Review published April 19 in Neuron.

"Studying asymmetry can provide the most basic blueprints for how the brain is organized," says lead author Onur Güntürkün, of the Institute of Cognitive Neuroscience at Ruhr-University Bochum, in Germany. "It gives us an unprecedented window into the wiring of the early, developing brain that ultimately determines the fate of the adult brain." Because asymmetry is not limited to human brains, a number of animal models have emerged that can help unravel both the genetic and epigenetic foundations for the phenomenon of lateralization.

Güntürkün says that brain lateralization serves three purposes. The first of those is perceptual specialization: the more complex a task, the more it helps to have a specialized area for performing that task. For example, in most people, the right side of the brain focuses on recognizing faces, while the left side is responsible for identifying letters and words.

The next area is motor specialization, which brings us to the southpaw. "What you do with your hands is a miracle of biological evolution," he says. "We are the master of our hands, and by funneling this training to one hemisphere of our brains, we can become more proficient at that kind of dexterity." Natural selection likely provided an advantage that resulted in a proportion of the population -- about 10% -- favoring the opposite hand. The thing that connects the two is parallel processing, which enables us to do two things that use different parts of the brain at the same time.

Brain asymmetry is present in many vertebrates and invertebrates. "It is, in fact, an invention of nature, which evolved because many animals have the same needs for specialization that we do," says Güntürkün, who is also currently a visiting fellow at the Stellenbosch Institute for Advanced Study in South Africa. Studies have shown that birds, like chickens, use one eye to distinguish grain from pebbles on the ground while at the same time using the other eye to keep watch for predators overhead.

Research on pigeons has shown that this specialization often is a function of environmental influences. When a pigeon chick develops in the shell, its right eye turns toward the outside, leaving its left eye to face its body. When the right eye is exposed to light coming through the shell, it triggers a series of neuronal changes that allow the two eyes to ultimately have different jobs.

A zebrafish model of lateralization, meanwhile, has enabled researchers to delve into the genetic aspects of asymmetrical development. Studies of important developmental pathways, including the Nodal signaling pathway, are uncovering details about how, very early in an embryo's development, the cilia act to shuffle gene products to one side of the brain or the other. By manipulating the genes in Nodal and other pathways, researchers can study the effects of these developmental changes on zebrafish behaviors.

Read more at Science Daily

Light rays from a supernova bent by the curvature of space-time around a galaxy

The light from the supernova iPTF16geu and of its host galaxy is warped and amplified by the curvature of space mass of a foreground galaxy. In the case of the point-like supernova, the light is split into four images. These have been resolved with the Hubble Space Telescope.
An international research team led by Ariel Goobar at Stockholm University has detected for the first time multiple images from a gravitationally lensed Type Ia supernova. The new observations suggest promising new avenues for the study of the accelerated expansion of the Universe, gravity and distribution of dark matter in the universe.

Type Ia supernovae, nature's own "standard candles," have been used for many years by astronomers to measure cosmological distances. These studies led to the discovery of the accelerated expansion of the Universe, a sensational discovery that won the 2011 Nobel prize in Physics. Professor Ariel Goobar at the Department of Physics at Stockholm University was a member of the team led by one of the Nobel laureates, Saul Perlmutter.

An international team of physicists and astronomers led from Stockholm University has now seen, for the first time, the rare appearance of multiple images of the same exploding star dubbed iPTF16geu, which belongs to a class of supernovae known as Type Ia. The phenomenon, called strong gravitational lensing is a result of the intense warping of the supernova light by an intervening galaxy positioned between us and the star in near perfect alignment. In this special case, the supernova appeared magnified, but also multiplied. The new observations provide a promising new tool to test key cosmological theories about the accelerating expansion of the universe and the distribution of a mysterious substance known as dark matter.

Type Ia supernovae are abundant and frequently used by astronomers to accurately measure distances in the universe. Gravitational lensing -- the curving of space due to gravity -- has also been observed many times since the early 20th century when it was predicted by Einstein. Yet, imaging a gravitationally lensed Type Ia supernova had proven formidably difficult, until now.

"Resolving, for the first time, multiple images of a strongly lensed "standard candle" supernova is a major breakthrough. We can measure the light focusing power of gravity more accurately than ever before, and probe physical scales that may have seemed out of reach until now," says Ariel Goobar, Professor at Oskar Klein Centre, Stockholm University and a lead author of the study, published today in the journal Science.

Goobar and his group are partners in two Caltech-led international scientific collaborations -- iPTF (intermediate Palomar Transient Factory) and GROWTH (Global Relay of Observatories Watching Transients Happen). The iPTF takes advantage of the Palomar Observatory and its unique capabilities to scan the skies and discover, in near real time, fast-changing cosmic events such as supernovae. GROWTH manages a global network of researchers and telescopes that can swiftly perform follow-up observations to study these transient events in detail.

Within two months of detection, the team observed iPTF16geu supernova with NASA/ESA Hubble Space Telescope, and the adaptive-optics instruments on the Keck Observatory atop Mauna Kea, Hawaii, and the VLT telescopes in Chile. Apart from producing a striking visual effect, capturing the image of the strongly lensed Type Ia supernova such as iPTF16geu is extremely useful scientifically. Astronomers can now measure very accurately how much time it takes for the light from each of the multiple images of the supernova to reach us. The difference in the time of arrival can then be used to estimate with a high precision the expansion rate of the universe known as the Hubble constant. Currently, the different methods to measure the Hubble constant produce slightly different results but even these small changes can result in significantly different scenarios for the predicted evolution and expansion of the universe.

The study of iPTF16geu is already delivering interesting results. Based on current knowledge of supernovae and gravitational lensing, observing an event such as iPTF16geu is rather improbable. Moreover, using data from Keck and Hubble the team finds that the lensing galaxy needs a great deal of substructure to account for the observed differences in the four supernova images, and the total lens magnification.

This may introduce new questions about the way matter clumps in the universe and challenge astronomers' understanding of gravitational lensing at small scales.

Read more at Science Daily

Streams of Meltwater Are Running Across Antarctica

Massive summer melting on East Antarctica's Amery Ice Shelf is seen from NASA's Landsat 4 satellite. The image shows about 520 square miles.
Researchers have found streams of water running across Antarctica, even in the perpetual deep freeze near the South Pole — a discovery that could be trouble for some of the ice shelves on the continent’s rim.

Explorers have reported pools of liquid water as far back Ernest Shackleton’s 1909 expedition to Antarctica. But by compiling aircraft and satellite photos dating back to the 1940s, researchers at Columbia University in New York and Britain’s Sheffield University have found melted ice flowing in channels as far as 85 degrees south.

“What is really surprising is that there is actually enough of those pockets of water, and melting actually occurs often enough, that these large drainage systems can be maintained,” said Jonathan Kingslake, a Columbia glaciologist who led the study. “They’re not only small pockets of water, but there’s streams moving that water up to 70 kilometers.”

The researchers detailed their findings in a pair of papers in the journal Nature.

Average temperatures in the Antarctic interior run more than 50 degrees below zero Celsius (-70 degrees Fahrenheit). But patches of rock that stick up above the ice sheets absorb the sun’s rays, melting the surrounding ice and starting that water flowing downhill, the researchers found. So-called blue ice, which reflects less sunlight than the surrounding snow, can also start to melt.

That water starts flowing into a network of hundreds of streams, eventually collecting in pools that can stretch as long as 80 kilometers (50 miles). And that water can damage the ice shelves that fringe Antarctica, deepening crevasses and weakening those structures. “The water collects in ponds and basically acts like a jackhammer,” said Robin Bell, another glaciologist at Columbia’s Lamont-Doherty Earth Observatory.

As global temperatures rise, more meltwater is likely to collect atop those shelves, putting more pressure on huge sheets of ice that are already being eaten away from underneath  by warmer ocean water. The 1,200-square-mile Larsen B ice shelf broke apart in 2002, and scientists have been watching a huge crack spread across the Delaware-sized Larsen C shelf for the past year.

Those breakups have little effect on sea level: “That ice cube is already in the water,” as Bell puts it. But when they disintegrate, they make it easier for ice from glaciers to flow off the continent. And at the Nansen ice shelf, on the continent’s east coast, the river of runoff these studies documented is pouring over the side in a 130-meter (400-foot) waterfall.

Those effects will have to be worked into computer models of future sea-level rise, said Bell, who was the lead author of a paper that focused on the Nansen shelf.

Antarctica is now regularly crisscrossed by satellites. But the gaps in earlier coverage mean the researchers are almost certain to have missed other drainage systems, Kingslake said — and more study will be needed to determine how they might affect sea levels.

Read more at Discovery News

Frog Mucus Compound Kills Many Strains of the Human Flu

The frog Hydrophylax bahuvistara, which produces a flu-fighting compound found in mucus on its skin.
Before refrigeration, many people from Russia and Finland used to follow an old practice of putting a frog into a bucket of milk in order to prevent the liquid from going sour. The unusual technique often worked, because frog skin is covered with a slimy mucus that can kill many different species of bacteria and viruses. (The milk preservation method is not something to try today, however, both for the sake of the frog and for the dairy consumer.)

Today, researchers announce that they have just discovered that a colorful tennis-ball sized frog from India produces a compound in its skin mucus that can neutralize numerous strains of H1 flu viruses, which are known to infect humans and other animals. As a result, the compound — a host defense peptide described in the journal Immunity — could lead to a future powerful influenza vaccine and/or drug treatment.

“In the past when you did drug discovery, you might have to investigate thousands or even millions of candidates to find one or two peptides that can neutralize viruses affecting humans,” senior author Joshy Jacob, an associate professor at Emory University’s Emory Vaccine Center, told Seeker. “In this case, we screened 32 peptides from the frog and had four hits. I was very surprised and was almost knocked off my chair!”

Out of the four frog peptides found to neutralize viruses that can infect humans, three proved to be toxic to our species. The scientists made this determination after exposing isolated human red blood cells in a dish to the compounds.

The fourth appears to be safe for human use. Electron microscopy indicates that this defense peptide disrupts the integrity of the H1 flu virus while leaving overall cells intact. It achieves this feat by binding to the stalk of hemagglutinin, a less variable region of the flu virus that has been the focus of other research groups trying to develop a universal influenza vaccine.

The researchers named the flu-fighting peptide “urumin” after the urumi, which is a sword with a flexible blade that snaps and bends like a whip. The weapon comes from the same Indian province, Kerala, as the frog.

Jacob said that frogs are not somehow more antimicrobial than the rest of us. All animals, including humans, produce defense peptides to keep bacteria and viruses in check.

“It’s just that it is easier to collect the peptides from the mucus on frog skin,” he said, mentioning that giving the frogs very small electrical shocks or rubbing a powder on their skin can cause them to secrete their peptide-rich slime.

A side-by-side electron microscope image of a flu virus before (left) and after (right) being exposed to urumin, a virus-fighting compound found in frog mucus.
All frogs produce different defense peptides. In this case, the frog (Hydrophylax bahuvistara) happens to produce one that works against H1. Flu viruses from humans cannot infect frogs, so the orange and dark brown amphibian likely evolved urumin to fight off some other pathogen.

To investigate how well urumin might help mammals, the researchers placed some of it inside the noses of unvaccinated mice. They then exposed the mice to flu viruses. The peptide neutralized all H1 strains, including those going back to 1930. It was not, however, effective against other known influenza viruses, such as H3N2.

Jacob and his team are now attempting to stabilize urumin and other potentially beneficial peptides, which can easily be broken down by enzymes in the body. He estimates that it could take about a decade before any possible related treatment is ready and approved for human use.

The researchers are now also seeking frog-derived peptides that might neutralize viruses like those that cause Zika and dengue. There is a rush to do so, as many frog populations have plummeted in recent years due to habitat loss, pollution, climate change, infectious diseases like chytridiomycosis that are spread by human activity, and other human-associated threats.

Read more at Discovery News

Apr 19, 2017

Eye expressions offer a glimpse into the evolution of emotion

People in a new study linked wide-open eyes, left, with emotions related to sensitivity, like fear and awe. Narrowed eyes, right, were linked to emotions such as disgust and suspicion.
New research by Adam Anderson, professor of human development at Cornell University's College of Human Ecology, reveals why the eyes offer a window into the soul.

According to the recent study, published in Psychological Science, we interpret a person's emotions by analyzing the expression in their eyes -- a process that began as a universal reaction to environmental stimuli and evolved to communicate our deepest emotions.

For example, people in the study consistently associated narrowed eyes -- which enhance our visual discrimination by blocking light and sharpening focus -- with emotions related to discrimination, such as disgust and suspicion. In contrast, people linked open eyes -- which expand our field of vision -- with emotions related to sensitivity, like fear and awe.

"When looking at the face, the eyes dominate emotional communication," Anderson said. "The eyes are windows to the soul likely because they are first conduits for sight. Emotional expressive changes around the eye influence how we see, and in turn, this communicates to others how we think and feel."

This work builds on Anderson's research from 2013, which demonstrated that human facial expressions, such as raising one's eyebrows, arose from universal, adaptive reactions to one's environment and did not originally signal social communication.

Both studies support Charles Darwin's 19th-century theories on the evolution of emotion, which hypothesized that our expressions originated for sensory function rather than social communication.

"What our work is beginning to unravel," said Anderson, "are the details of what Darwin theorized: why certain expressions look the way they do, how that helps the person perceive the world, and how others use those expressions to read our innermost emotions and intentions."

Anderson and his co-author, Daniel H. Lee, professor of psychology and neuroscience at the University of Colorado, Boulder, created models of six expressions -- sadness, disgust, anger, joy, fear and surprise -- using photos of faces in widely used databases. Study participants were shown a pair of eyes demonstrating one of the six expressions and one of 50 words describing a specific mental state, such as discriminating, curious, bored, etc. Participants then rated the extent to which the word described the eye expression. Each participant completed 600 trials.

Participants consistently matched the eye expressions with the corresponding basic emotion, accurately discerning all six basic emotions from the eyes alone.

Anderson then analyzed how these perceptions of mental states related to specific eye features. Those features included the openness of the eye, the distance from the eyebrow to the eye, the slope and curve of the eyebrow, and wrinkles around the nose, the temple and below the eye.

The study found that the openness of the eye was most closely related to our ability to read others' mental states based on their eye expressions. Narrow-eyed expressions reflected mental states related to enhanced visual discrimination, such as suspicion and disapproval, while open-eyed expressions related to visual sensitivity, such as curiosity. Other features around the eye also communicated whether a mental state is positive or negative.

Further, he ran more studies comparing how well study participants could read emotions from the eye region to how well they could read emotions in other areas of the face, such as the nose or mouth. Those studies found the eyes offered more robust indications of emotions.

Read more at Science Daily

Newly discovered exoplanet may be best candidate in search for signs of life

This artist's impression shows the exoplanet LHS 1140b, which orbits a red dwarf star 40 light-years from Earth and may be the new holder of the title 'best place to look for signs of life beyond the Solar System'. Using ESO's HARPS instrument at La Silla, and other telescopes around the world, an international team of astronomers discovered this super-Earth orbiting in the habitable zone around the faint star LHS 1140. This world is a little larger and much more massive than the Earth and has likely retained most of its atmosphere.
The newly discovered super-Earth LHS 1140b orbits in the habitable zone around a faint red dwarf star named LHS 1140, in the constellation of Cetus (The Sea Monster)[1]. Red dwarfs are much smaller and cooler than the Sun and, although LHS 1140b is ten times closer to its star than the Earth is to the Sun, it only receives about half as much sunlight from its star as the Earth and lies in the middle of the habitable zone. The orbit is seen almost edge-on from Earth and as the exoplanet passes in front of the star once per orbit it blocks a little of its light every 25 days.

"This is the most exciting exoplanet I've seen in the past decade," said lead author Jason Dittmann of the Harvard-Smithsonian Center for Astrophysics (Cambridge, USA). "We could hardly hope for a better target to perform one of the biggest quests in science -- searching for evidence of life beyond Earth."

"The present conditions of the red dwarf are particularly favourable -- LHS 1140 spins more slowly and emits less high-energy radiation than other similar low-mass stars," explains team member Nicola Astudillo-Defru from Geneva Observatory, Switzerland [2].

For life as we know it to exist, a planet must have liquid surface water and retain an atmosphere. When red dwarf stars are young, they are known to emit radiation that can be damaging for the atmospheres of the planets that orbit them. In this case, the planet's large size means that a magma ocean could have existed on its surface for millions of years. This seething ocean of lava could feed steam into the atmosphere long after the star has calmed to its current, steady glow, replenishing the planet with water.

The discovery was initially made with the MEarth facility, which detected the first telltale, characteristic dips in light as the exoplanet passed in front of the star. ESO's HARPS instrument, the High Accuracy Radial velocity Planet Searcher, then made crucial follow-up observations which confirmed the presence of the super-Earth. HARPS also helped pin down the orbital period and allowed the exoplanet's mass and density to be deduced [3].

The astronomers estimate the age of the planet to be at least five billion years. They also deduced that it has a diameter 1.4 times larger than the Earth -- almost 18,000 kilometres. But with a mass around seven times greater than the Earth, and hence a much higher density, it implies that the exoplanet is probably made of rock with a dense iron core.

This super-Earth may be the best candidate yet for future observations to study and characterise its atmosphere, if one exists. Two of the European members of the team, Xavier Delfosse and Xavier Bonfils both at the CNRS and IPAG in Grenoble, France, conclude: "The LHS 1140 system might prove to be an even more important target for the future characterisation of planets in the habitable zone than Proxima b or TRAPPIST-1. This has been a remarkable year for exoplanet discoveries!" [4,5].

In particular, observations coming up soon with the NASA/ESA Hubble Space Telescope will be able to assess exactly how much high-energy radiation is showered upon LHS 1140b, so that its capacity to support life can be further constrained.

Read more at Science Daily

Leonardo da Vinci ‘Relics’ Discovered That Can Potentially Provide His DNA

An illustration of Leonardo da Vinci's presumed remains in Amboise, France.
Italian researchers say that they have found two “relics” belonging to Leonardo da Vinci, which may help in sourcing the DNA of the genius whose work typified the Renaissance.

The mysterious relics were traced during a decades-long genealogical study into Leonardo's family.

Historian Agnese Sabato and Alessandro Vezzosi, director of the Museo Ideale in Vinci, will announce their findings on Thursday at a conference in the Tuscan town of Vinci, where the artist was born in 1452.

“I can’t yet disclose the nature of these relics,” Vezzosi told Seeker. “I can only say that both are historically associated with Leonardo da Vinci. One is an object, the other is organic material.”

If genuine, the organic relic would represent Leonardo’s only known biological evidence.

It was believed that no traces were left of the painter, engineer, mathematician, philosopher and naturalist. The remains of Leonardo, who died in 1519 at the age of 67 in Amboise, France, are known to have been dispersed before the 19th century.

But in 1863 a skeleton and large skull were found at the site of the church of Saint-Florentin, where Leonardo was originally interred, which was plundered in the 16th century during religious wars and completely destroyed in 1808.

A stone inscription was unearthed near the skeleton. It read LEO DUS VINC, pointing to Leonardo's name.

The bones attributed to Leonardo went lost for a decade. They were rediscovered in 1874 and reburied in the chapel of Saint-Hubert at the Château d'Amboise. There, a plaque correctly states that the grave contains Leonardo's “presumed remains.”

Permission to exhume the bones for analysis has always been denied for ethical reasons. The organic relic claimed by the researchers was sourced from an unidentified private collector.

“We have verified its historical accuracy, and we can now say the relic is associated to the skeleton unearthed in 1863,” Sabato said.

Vezzosi and Sabato, who have founded an organization called Leonardo da Vinci Heritage to safeguard and promote his legacy, have been searching for biological traces of Leonardo since 2000. They began by scrutinizing the master’s paintings and manuscripts for his fingerprints.

“We pieced together an archive of hundreds of Leonardo’s fingerprints, hoping to get some biological material,” Vezzosi said. “At that time, cracking da Vinci’s DNA code was just a wild dream. Now it’s a real possibility.”

A crucial twist in the research occurred last year, when Vezzosi and Sabato announced the existence of dozens of Leonardo’s living descendants at a crowded conference in Vinci.

“It has been a long and exhausting research, as we had to deal with repeating names and confusing da Vinci and Vinci surnames,” Vezzosi said.

Leonardo was the illegitimate son of Ser Piero da Vinci, a Florentine legal notary, and Caterina, an enigmatic woman described in documents as being “the wife of Achattabriga di Piero del Vaccha da Vinci." He had a sprawling family that included four stepmothers and as many as 24 half-brothers and half-sisters.

Since last year, Vezzosi and Sabato have updated the official da Vinci family tree, adding more than 150 names.

“The hunt for Leonardo DNA can now rely on a good, well-referenced genealogy,” Sabato told Seeker.

She explained that all of the direct descendants come from Leonardo’s father Ser Piero, since Caterina's relatives appear to be lost in history.

“But we are working to track them down,” Sabato said. “We discovered that one of Caterina’s daughters had three daughters, so we are searching in this direction.”

Finding Caterina’s descendants — living or dead — might help in retrieving Leonardo’s mitochondrial DNA, which is passed down through the maternal line.

The researchers are now conferring with several international universities to begin a broader scientific investigation on the relics and Leonardo’s descendants. They plan to carry out DNA analysis on the relic and compare it to Leonardo’s newly discovered living descendants and to bones found in recently identified da Vinci burials throughout Tuscany.

The study is part of a wider project to find Leonardo’s DNA by 2019, to mark the 500th anniversary of his death.

“Overall, we have more than promising material to continue our research and isolate da Vinci’s DNA, 15 generations later,” Vezzosi said.

Even if it won’t be possible to retrieve any usable DNA from the relic, Leonardo’s reconstructed family tree still leaves hope to track down his Y chromosome.

Vezzosi and Sabato have found a direct and uninterrupted line which runs from Leonardo's half-brother Domenico Matteo to living male descendants.

Read more at Discovery News

New Fossil Carnivore May Explain Why Our Primate Relatives Stayed in Trees

The skull of a hyaenodont.
A new and very toothy fossil carnivore has just been discovered in Egypt, and corresponding research could help to explain why our early primate relatives tried to spend as much time as possible in trees.

The meat lover has been named Masrasector nananubis, after the canine-headed Egyptian god Anubis, who was associated with the afterlife. Unearthed at a site called “Locality 41” in Egypt’s Fayum Depression, located west of the Nile and south of Cairo, the new fossil is described in the journal PLOS ONE.

“We found that M. nananubis had limbs most like a fast-moving, ground based carnivore, similar to a fox or mongoose,” lead author Matthew Borths, who co-authored the paper with Erik Seiffert, told Seeker. “It likely hunted by stalking its prey on the ground, or by waiting in ambush in the dense foliage of the forested Fayum for small prey to scamper by.”

The researchers determined that the Anubis namesake lived 34 million years ago and was a hyaenodont. Borths, a researcher at Ohio University’s department of biomedical sciences, and Seiffert, a professor in the department of integrative anatomical sciences at the University of Southern California, explained that hyaenodonts were the top predators in Africa after the extinction of the dinosaurs.

Fayum Depression of Egypt where the fossils for Masrasector nananubis were found.
“Despite their name, hyaenodonts are not closely related to hyenas,” Borths continued. “The name means they had hyena-like teeth, which is true. Like hyenas, hyaenodonts were meat eaters and some were bone crackers.”

What’s more, they found that M. nananubis belongs to a lineage of hyaenodonts called the teratodontines, which means “monstrous teeth.” Based on other fossils discovered at Locality 41, this carnivore lived alongside even larger hyaenodonts, such as the coyote-sized Brychotherium and the wolf-sized Akhnatenavus. Large snakes and crocodiles also existed at the site.

“The environment they all lived in 34 million years ago was a marshy forest, reminiscent of parts of the Everglades or the Louisiana gulf coast, which makes sense because geologists hypothesize the coast was close to the site where these fossils were preserved,” Borths said.

He added that some localities at the site “include fossils of large fruits and trees, evidence this forested habitat would have also been appealing to our early primate relatives.”

It's little wonder that our early relatives tried to spend as much time as possible in trees, given the tasty food above ground and the hungry, blood-thirsty carnivores on the ground. The researchers said that some hyaenodonts did evolve to become tree-dwellling, which could have made life all the more interesting for our primate ancestors.

Life reconstruction of Hyaenodon, a relative of Masrasector nananubis.
The impressive teeth of M. nananubis — which featured both meat-slicing, blade-like teeth and teeth designed for grinding — suggest that this carnivore could forage on fruits and seeds, in addition to consuming meaty flesh.

Hyaenodonts over time spread out of Africa and into Europe, Asia and North America. They were once a very successful and widespread bunch, and yet, as far as researchers know, they all died out and left no descendants. Their extinction remains a mystery.

Read more at Discovery News

Apr 18, 2017

Ancient Sea Scorpion's Weaponized Tail Made Mincemeat of Our Aquatic Ancestors

Illustration of the sea scorpion Slimonia acuminata attacking an early vertebrate.
Long before the evolution of sharks and barracudas, some of the scariest predators lurking in the primordial seas were eurypterids, better known as sea scorpions. Related to modern scorpions and horseshoe crabs, these animals included species that had sharp pinching claws and the ability to crawl out of water to hunt on land. They thrived around 430 million years ago, with certain species growing to over 10 feet long.

A newly discovered, well-preserved fossil eurypterid adds a weapon to the known arsenal of these ancient formidable predators: a slapping, slashing tail spine. Its wielder, Slimonia acuminata, represents a new species of eurypterid that once even feasted on our early fish ancestors. It is described in the journal The American Naturalist.

“Slimonia would have lurked in the shallow waters of lagoons and lakes along the coast of primordial Europe, during the Silurian Period (443.7–416 million years ago),” lead author Scott Persons, of the University of Alberta’s Department of Biological Sciences, told Seeker. “At the time, our vertebrate ancestors were primitive fish.”

Persons and co-author John Acorn studied Slimonia’s remains, which were unearthed at the Patrick Burn Formation near Lesmahagow, Scotland. This sea scorpion was not one of the largest eurypterids, given that it measured about a foot and a half long. Its weaponized tail gave it an edge over most other predators, though.

Slimonia acuminata fossil.
One specimen preserves the sea scorpion’s serrated and spine-tipped tail, curved strongly to one side. The tail actually consists of two attached parts: a rounded area that looks a bit like an arrowhead, and then the actual knife-like spine. The researchers suspect that the former might have served double duty as a rudder when Slimonia was swimming.

As for how this predator dispatched prey, Persons said that Slimonia probably used its chelicerae, or segmented mouth parts, to hold onto our ancestors and other victims, “while repeatedly striking with sidelong blows from the tail spine.”

Unlike today’s lobsters and shrimps, which can flip their broad tails up and down to help them swim, sea scorpion tails were vertically inflexible but horizontally highly mobile. A cool feature was that they could aggressively slap and slash sideways, while still meeting a minimum of hydraulic resistance. This helped to prevent them from propelling themselves away from an intended target with each forceful strike.

The other top ocean predators at the time were enormous cephalopods, meaning the relatives of modern squid, octopus and the chambered nautilus.

“These were real Lovecraftian monsters, with sharp beaks and lots of tentacles,” Persons explained, referring to the horror fiction of H. P. Lovecraft.

The giant squid surely feasted on our ancient ancestors, but also probably took on Slimonia from time to time.

Close-up of the weaponized tail of Slimonia acuminata.
“A soft cephalopod body would not have wanted to get struck by Slimonia’s tail, but we know that octopus are capable of handling lots of spiky dangerous prey by dexterously immobilizing them with the strong tentacles,” Persons said.

He added that, unlike sea scorpions, whose fossilized shells reveal their full body size and shape, the remains of ancient cephalopods require more scientific guesswork. That's because their soft bodies do not easily fossilize.

Clues to their existence are cephalopod shells, some of which were spiral shaped, like a snail’s, while others were swirl shaped, Persons said, “like a tall helping of soft-serve ice cream.”

“Of the swirl-shelled Silurian cephalopods — say that five times fast — a few grew to well over a meter (3.3 feet) in length,” he continued. “Like modern squid, they could have reached out with their tentacles, snagged a victim and then pulled it back into their mouths.”

Read more at Discovery News

Despite Debate, Estimates of Humanity’s Impact on Climate Change Are Accurate

Climate change contrarians have used many arguments to cast doubt on the scientific consensus that the atmosphere is warming and humans are to blame.

They’ve alleged that tens of thousands of scientists, working across dozens of different disciplines, have organized a vast conspiracy to manipulate data. They’ve said more carbon dioxide in the atmosphere will actually be a benefit because it will boost agricultural production. And they’ve even said that global warming has paused in recent years.

But their primary tactic these days appears to be to acknowledge that the concentration of greenhouse gases in the atmosphere is increasing due to human causes, but suggest that the scientific community just can’t pin down what impact those emissions will have on the climate system.

Trump’s EPA administrator Scott Pruitt made that claim during his Senate confirmation hearing, as did former ExxonMobil CEO turned Secretary of State Rex Tillerson.

Kyle Armour of the University of Washington, writing in Nature Climate Change, says that, actually, the scientific community has done quite well at developing accurate predictions of how sensitive the atmosphere and oceans are to carbon pollution.

The debate, he says, pivots around a number called equilibrium climate sensitivity (ECS), which is the temperature change that scientists expect to occur with a doubling of carbon dioxide in the atmosphere compared to before the Industrial Revolution.

“This is the number that’s been essentially at the heart of climate change predictions for decades now,” he said. “It has a lot of policy relevance. If this number is high, we have a very sensitive Earth that will warm up a lot in response to greenhouse gases. If the number is low, we have a less sensitive climate system that would warm up a lot less.”

Put another way, climate sensitivity tells us how we need to limit greenhouse gas emissions in order to stay well below an average global temperature increase of 2°C compared to the mid-19th century, which many scientists say is a dangerous threshold to pass.

The problem is observations collected over the past 100 years have shown the climate to be less sensitive to increasing greenhouse gas concentrations than computer models of the climate have predicted.

And that’s where Armour got to work.

“It appeared that newer observations suggested a fairly low climate sensitivity in the range of about 2°C for a doubling of CO2, whereas the models suggested a higher climate sensitivity more in the range of 3°C for a doubling of CO2,” he said. “What I was interested in with the study was basically how much of the discrepancy between the observations and the models could be explained by the fact that climate sensitivity changes over time.”

There’s an incredible amount of inertia built into Earth’s climate system. The increased amount of energy trapped in the atmosphere due to all of the greenhouse gas emissions from our coal-fired power plants and internal combustion engines takes many decades to fully take effect.

And the climate system works in complex ways. When rising air temperatures in the Arctic melt summer sea ice, for example, it creates larger areas of dark, open ocean which absorb rather than reflect sunlight, which in turn causes more global warming. That type of feedback loop combined with the inertia of the climate system means climate change doesn’t move along smooth, linear plots on a line graph.

Armour found that while observations might show climate sensitivity to be on the lower end, the models are picking up quite well the amount of warming that emerges over the long-term.

“The conclusions are really two-fold,” said Armour. “When the models are treated consistently with the observations, that is measuring climate sensitivity within the models in the same way you would with the observations, it brings that value of sensitivity in the models downward, meaning they’re not too sensitive.”

“But the other way you could view the results,” he added, “is that the model range of future warming is rather realistic, meaning that our apparent climate sensitivity we get from the observations can be expected to increase in the future, meaning more global warming than you might naïvely expect from taking just that low value that people have been talking about from the observations.”

Gavin Schmidt, a NASA climate scientist not involved in the study, said Armour's findings complemented the results of a 2016 report on climate sensitivity conducted by researchers at NASA and Columbia University.

“What Armour finds is that [feedback loops] do change and in such a way that if you estimate the final sensitivity from just the early period you will end up underestimating the ECS,” he said in an email. “This is important because that’s almost exactly what’s happening when we try and use recent temperature trends to estimate the ECS. Those estimates have tended to come in lower than others, in ways that aren’t consistent with our understandings of processes or paleoclimate. So this result makes those studies much more consistent with other methods.”

Armour pointed to a pair of feedbacks that have yet to take effect, but are likely to lead to significant levels of warming.

“Over the next several decades to centuries we expect the Southern Ocean to warm up almost as much as the Arctic and get that big, positive feedback to start kicking in,” he said. “So it’s really that delay in the positive feedbacks kicking in that causes this increase in climate sensitivity into the future.”

That feedback in the southern hemisphere is projected to occur when ocean temperatures in the Southern Ocean warm, melting sea ice, like is already happening in the Arctic, causing the ocean to absorb more sunlight and leading to greater amounts warming.

Increased warming in the eastern tropical Pacific over the next several decades, he added, is is likely to diminish cloud cover in the region. That cloud cover, like sea ice in the Arctic and Southern Ocean, reflects incoming sunlight.

“Initially in the very early stages of global warming, like today, like we’ve seen over the last hundred years, your clouds in the eastern tropical Pacific are actually acting to limit global warming, it has a negative, damping impact,” he said. “But in the future, say over the next several decades, we expect those to be a positive feedback, enhancing global warming.”

Read more at Discovery News

Mythic Giant Shipworm Survives on Fart Gas and Bacteria

A rare species of giant shipworm has mostly lived in myth since its 3 to 5 foot-long tusk-resembling shells were first documented in the 18th century. Shipworms  — which are actually a type of saltwater clam — once conquered the seas by feasting on wood, sinking ships in the process, but this particular species, Kuphus polythalamia, was recently found planted like carrots in mud at the bottom of a lagoon in Mindanao, Philippines.

The stench of the site, which was previously used as a log storage area, was overwhelming, yet researchers from Sultan Kudarat State University managed to collect five live Kuphus individuals, allowing them to study the live specimen inside the shell for the first time.

The scientists packed their precocious cargo into PVC pipes and escorted the shipworms to the University of the Philippines, where Daniel Distel and his team eagerly awaited their arrival.

“We really did not know what to expect,” Distel, a research professor and director of the Ocean Genome Legacy Center at Northeastern University, told Seeker. “Most clams are white or beige or pinkish inside.”

His colleague Margo Haygood described the moment when they first set eyes on the live giant shipworms.

“We turned the pipes upright and filled them with seawater and airstones and put the animals in to acclimate," she recalled. "Before long, I looked into the pipe and could see a strong jet of water coming out of the animal’s siphon. It was alive!”

“The animal inside is dark gray, shiny and floppy,” added Haygood, who is a research professor in medicinal chemistry at the University of Utah College of Pharmacy. “It looks like an alien creature.”

The researchers continued to investigate the specimens, with their results reported in the journal Proceedings of the National Academy of Sciences.

The scientists determined that, unlike other shipworms, which munch on wood in the ocean, Kuphus depends on two primary things for its survival: hydrogen sulfide and beneficial bacteria that live in its gills. Hydrogen sulfide, commonly found in rotten eggs and human flatulence, is very poisonous, corrosive, and flammable in large amounts.

Kuphus loves it, though. Distel explained that the bacteria burn it “the same way we burn carbohydrate or sugar to make energy.” The bacteria-made sugars are ultimately what the shipworm lives on. It would seem to have an endless supply of hydrogen sulfide, since its organic-rich mud habitat emits the smelly gas in large quantities.

A scientist removes the top of a shipworm shell to reveal the living animal inside.
It is a mystery as to how Kuphus evolved this unusual mode of survival. What is known is that its wood-eating relatives have had a tougher time finding food since human activity has actually reduced the overall amount of wood in the oceans.

Distel explained, “Most wood gets in the oceans via erosion of coastal forests and riverbanks. People like to clear forests away from coasts and riverbanks so they can build homes, businesses and resorts. We also like to build dams and have dammed most of the great rivers of the world. As a result, a lot less wood makes it to the sea.”

Read more at Discovery News

Tatooine-Like Planets May Be ‘Excellent Candidates’ for Supporting Life

This artist's concept shows a hypothetical planet covered in water around the binary star system of Kepler-35A and B.
Life on an alien planet with two suns in its sky, like Luke Skywalker's home world Tatooine in the "Star Wars" films, may indeed be possible, a new study suggests.

A Tatooine world could be habitable despite its inevitably complicated orbit, as long as the planet stays within a particular range of distances from its two host stars, researchers said.

"This means that double-star systems of the type studied here are excellent candidates to host habitable planets, despite the large variations in the amount of starlight hypothetical planets in such a system would receive," Max Popp, an associate research scholar at Princeton University in New Jersey and the Max Planck Institute of Meteorology in Hamburg, Germany, said in a statement.

Popp and Siegfried Eggl, a Caltech postdoctoral scholar at NASA's Jet Propulsion Laboratory in Pasadena, California, investigated the "habitable zone" for Tatooine worlds — that just-right range of orbital distances at which liquid water, and perhaps life as we know it, could exist on a planet's surface.

Nailing down the habitable zone for single-star planets isn't simple or straightforward; details of the zone depend heavily on the nature of a world's atmosphere, for example. But habitable zones get even trickier when the planet in question has two suns.

Tatooine planets' habitable zones, after all, depend on the distance from the two host stars' center of mass, not just the distance from any particular star. And Tatooine worlds don't orbit in a circular path; their paths wobble considerably due to the gravitational influences of their parent stars, researchers said.

To better understand such factors, Popp and Eggl modeled conditions on a hypothetical Earth-size, water-covered world in Kepler-35, a real two-star system more than 5,000 light-years from Earth that's known to host a planet eight times more massive than our own. (Popp and Eggl ignored the gravitational influence of this actual planet, which is known as Kepler-35b, for simplicity's sake.)

"Our research is motivated by the fact that searching for potentially habitable planets requires a lot of effort, so it is good to know in advance where to look," Eggl said in the same statement. "We show that it's worth targeting double-star systems."

The duo's simulations investigated what this imaginary Tatooine world's climate would be like if it orbited with periods between 341 and 380 Earth days.

They found that, near the outer edge of Kepler-35's presumed habitable zone, the planet would be relatively cold and dry. The dearth of atmospheric water vapor would also make the climate quite variable; global average surface temperatures would swing by as much as 3.6 degrees Fahrenheit (2 degrees Celsius), the researchers said.

"This is analogous to how, on Earth, in arid climates like deserts, we experience huge temperature variations from day to night," Eggl said. "The amount of water in the air makes a big difference."

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