The larva of the sleeping chironomid, Polypedilum vanderplanki -- a mosquito-like insect that inhabits semi-arid areas of Africa -- is well known for being able to come back to life after being nearly completely desiccated, losing up to 97 percent of its body's water content. However, the genetic mechanisms the insects use to achieve this feat, and, especially is the identity of the master gene that induces desiccation tolerance have remained largely elusive. Now, researchers from an international collaboration including Oleg Gusev of the RIKEN Innovation Center and collaborators from NARO, Kazan Federal University (Russia) and Skoltech University (Russia) have discovered that a gene called heat shock factor -- which is present in some form in nearly all living organisms on earth -- has been coopted by the species to survive desiccation.
Heat shock factor -- which exists in a single form in invertebrates but multiple forms in vertebrates -- is an essential part of the ability of living cells to survive stressful conditions such as heat, cold, radiation, and, it turns out, desiccation. In desert insects, the researchers found, the gene is able in certain conditions to upregulate itself, and this upregulation leads to a number of downstream processes, including the synthesis of heat shock proteins that are able to protect proteins in the cell from misfolding.
To perform the research, published in the Proceedings of the National Academy of Sciences, the researchers compared data on RNA expression in the sleeping chironomid with a closely related species, Polypedilum nubifer, which is not capable of surviving desiccation. They found that in the sleeping chironomid, hundreds of genes, including genes known to be involved in forming a "molecular shield" against damage due to dehydration, were already expressed during the early stages of desiccation. They discovered that a certain DNA motif, TCTAGAA, which is the binding site for HSF, was strongly enriched around the transcription start site of the genes activated by desiccation in the sleeping chironomid, but not the other species. Intriguingly, they found that in the desiccation-tolerant species, but not the other, genes responsible for the synthesis of trehalose -- a sugar that can stabilize cells in a dry state -- contained the TCTAGAA motif.
To shed further light on the role of trehalose, they treated a cultured cell line from the sleeping chironomid with the sugar, and found that many of the genes activated by desiccation were also activated, and further, that the trehalose treatment led to the activation of the HSF gene. This effect of trehalose was prevented by knocking down the HSF gene, showing the HSF was clearly involved in the response.
According to Oleg Gusev, who led the group, "The discovery that heat shock factor is an important regulator of gene expression in response to desiccation was very interesting for us. It seems that these extremophilic insects in the process of evolution have coopted a very conservative transcription factor and its action for their own needs to survive without water by evolving a special gene structure and "adjusting" their genome sequence for these "needs." Our data suggests the following story: HSF is activated during dehydration, and then HSF actually self-activates by binding to the upstream region of its own gene. This leads to the activation of the downstream genes that allow the insects to survive desiccation. What was very surprising to us was the finding that trehalose itself can activate HSF."
Read more at Science Daily
Mar 9, 2018
First laboratory simulation of exoplanet atmospheric chemistry
 |
| Lead author Sarah Hörst, right, and assistant research scientist Chao He examine samples of simulated atmospheres in a dry nitrogen glove box, where they are stored to avoid contamination from Earth's atmosphere. |
The simulations are necessary to establish models of the atmospheres of far-distant worlds, models that can be used to look for signs of life outside the solar system. Results of the studies appeared this week in Nature Astronomy.
"One of the reasons why we're starting to do this work is to understand if having a haze layer on these planets would make them more or less habitable," said the paper's lead author, Sarah Hörst, assistant professor of Earth and planetary sciences at the Johns Hopkins University.
With telescopes available today, planetary scientists and astronomers can learn what gases make up the atmospheres of exoplanets. "Each gas has a fingerprint that's unique to it," Hörst said. "If you measure a large enough spectral range, you can look at how all the fingerprints are superimposed on top of each other."
Current telescopes, however, do not work as well with every type of exoplanet. They fall short with exoplanets that have hazy atmospheres. Haze consists of solid particles suspended in gas, altering the way light interacts with the gas. This muting of spectral fingerprints makes measuring the gas composition more challenging.
Hörst believes this research can help the exoplanet science community determine which types of atmospheres are likely to be hazy. With haze clouding up a telescope's ability to tell scientists which gases make up an exoplanet's atmosphere -- if not the amounts of them -- our ability to detect life elsewhere is a murkier prospect.
Planets larger than Earth and smaller than Neptune, called super-Earths and mini-Neptunes, are the predominant types of exoplanets, or planets outside our solar system. As this class of planets is not found in our solar system, our limited knowledge makes them more difficult to study.
With the coming launch of the James Webb Space Telescope, scientists hope to be able to examine the atmospheres of these exoplanets in greater detail. JWST will be capable of looking back even further in time than Hubble with a light collecting area around 6.25 times greater. Orbiting around the sun a million miles from Earth, JWST will help researchers measure the composition of extrasolar planet atmospheres and even search for the building blocks of life.
"Part of what we're trying to help people figure out is basically where you would want to look," said Hörst of future uses of the James Webb Space Telescope.
Given that our solar system has no super-Earths or mini-Neptunes for comparison, scientists don't have "ground truths" for the atmospheres of these exoplanets. Using computer models, Hörst's team was able to put together a series of atmospheric compositions that model super-Earths or mini-Neptunes. By varying levels of three dominant gases (carbon dioxide, hydrogen, gaseous water), four other gases (helium, carbon monoxide, methane, nitrogen) and three sets of temperatures, they assembled nine different "planets."
The computer modeling proposed different percentages of gases, which the scientists mixed in a chamber and heated. Over three days, the heated mixture flowed through a plasma discharge, a setup that initiated chemical reactions within the chamber.
"The energy breaks up the gas molecules that we start with. They react with each other and make new things and sometimes they'll make a solid particle [creating haze] and sometimes they won't," Hörst said.
"The fundamental question for this paper was: Which of these gas mixtures -- which of these atmospheres -- will we expect to be hazy?" said Hörst.
The researchers found that all nine variants made haze in varying amounts. The surprise lay in which combinations made more. The team found the most haze particles in two of the water-dominant atmospheres. "We had this idea for a long time that methane chemistry was the one true path to make a haze, and we know that's not true now," said Hörst, referring to compounds abundant in both hydrogen and carbon.
Furthermore, the scientists found differences in the colors of the particles, which could affect how much heat is trapped by the haze. "Having a haze layer can change the temperature structure of an atmosphere," said Hörst. "It can prevent really energetic photons from reaching a surface."
Like the ozone layer that now protects life on Earth from harmful radiation, scientists have speculated a primitive haze layer may have shielded life in the very beginning. This could be meaningful in our search for external life.
Read more at Science Daily
A new kind of star
A new kind of star comes up from a study by SISSA's postdoctoral researcher Raúl Carballo-Rubio. In a piece of research recently published in Physical Review Letters, Carballo-Rubio has developed a novel mathematical model that combines general relativity with the repulsive effect of quantum vacuum polarization. The inclusion of this repulsive force allows describing ultracompact configurations of stars, which were previously considered by scientists not to exist in equilibrium.
"As a consequence of the attractive and repulsive forces at play, a massive star can either become a neutron star, or turn into a black hole" says Carballo-Rubio. In neutron stars, stellar equilibrium is the result of the "fight" between gravity, which is an attractive force, and a repulsive force called degeneracy pressure, of quantum mechanical origin. "But if the star's mass becomes higher than a certain threshold, about 3 times the solar mass, the equilibrium would be broken and the star collapses due to the overwhelming pull of the gravitational force."
In this study, the researcher has investigated the possibility that additional quantum mechanical forces that are largely expected to be present in nature, permit new equilibrium configurations for stars above this threshold. The additional force that has been taken into account is a manifestation of the effect known as "quantum vacuum polarization," which is a robust consequence of mixing gravity and quantum mechanics in a semiclassical framework. "The novelty in this analysis is that, for the first time, all these ingredients have been assembled together in a fully consistent model. Moreover, it has been shown that there exist new stellar configurations, and that these can be described in a surprisingly simple manner."
There are still several important issues that remain to be studied, including the observational applications of these results. "It is not clear yet whether these configurations can be dynamically realized in astrophysical scenarios, or how long would they last if this is the case." From an observational perspective, these "semiclassical relativistic stars" would be very similar to black holes. However, even minute differences would be perceptible in the next generation of gravitational wave observatories: "If there are very dense and ultracompact stars in the Universe, similar to black holes but with no horizons, it should be possible to detect them in the next decades."
From Science Daily
"As a consequence of the attractive and repulsive forces at play, a massive star can either become a neutron star, or turn into a black hole" says Carballo-Rubio. In neutron stars, stellar equilibrium is the result of the "fight" between gravity, which is an attractive force, and a repulsive force called degeneracy pressure, of quantum mechanical origin. "But if the star's mass becomes higher than a certain threshold, about 3 times the solar mass, the equilibrium would be broken and the star collapses due to the overwhelming pull of the gravitational force."
In this study, the researcher has investigated the possibility that additional quantum mechanical forces that are largely expected to be present in nature, permit new equilibrium configurations for stars above this threshold. The additional force that has been taken into account is a manifestation of the effect known as "quantum vacuum polarization," which is a robust consequence of mixing gravity and quantum mechanics in a semiclassical framework. "The novelty in this analysis is that, for the first time, all these ingredients have been assembled together in a fully consistent model. Moreover, it has been shown that there exist new stellar configurations, and that these can be described in a surprisingly simple manner."
There are still several important issues that remain to be studied, including the observational applications of these results. "It is not clear yet whether these configurations can be dynamically realized in astrophysical scenarios, or how long would they last if this is the case." From an observational perspective, these "semiclassical relativistic stars" would be very similar to black holes. However, even minute differences would be perceptible in the next generation of gravitational wave observatories: "If there are very dense and ultracompact stars in the Universe, similar to black holes but with no horizons, it should be possible to detect them in the next decades."
From Science Daily
A lifetime of regular exercise slows down aging, study finds
 |
| Researchers at the University of Birmingham and King's College London have found that staying active keeps the body young and healthy. |
The researchers set out to assess the health of older adults who had exercised most of their adult lives to see if this could slow down ageing.
The study recruited 125 amateur cyclists aged 55 to 79, 84 of which were male and 41 were female. The men had to be able to cycle 100 km in under 6.5 hours, while the women had to be able to cycle 60 km in 5.5 hours. Smokers, heavy drinkers and those with high blood pressure or other health conditions were excluded from the study.
The participants underwent a series of tests in the laboratory and were compared to a group of adults who do not partake in regular physical activity. This group consisted of 75 healthy people aged 57 to 80 and 55 healthy young adults aged 20 to 36.
The study showed that loss of muscle mass and strength did not occur in those who exercise regularly. The cyclists also did not increase their body fat or cholesterol levels with age and the men's testosterone levels also remained high, suggesting that they may have avoided most of the male menopause.
More surprisingly, the study also revealed that the benefits of exercise extend beyond muscle as the cyclists also had an immune system that did not seem to have aged either.
An organ called the thymus, which makes immune cells called T cells, starts to shrink from the age of 20 and makes less T cells. In this study, however, the cyclists' thymuses were making as many T cells as those of a young person.
The findings come as figures show that less than half of over 65s do enough exercise to stay healthy and more than half of those aged over 65 suffer from at least two diseases.* Professor Janet Lord, Director of the Institute of Inflammation and Ageing at the University of Birmingham, said: "Hippocrates in 400 BC said that exercise is man's best medicine, but his message has been lost over time and we are an increasingly sedentary society.
"However, importantly, our findings debunk the assumption that ageing automatically makes us more frail.
"Our research means we now have strong evidence that encouraging people to commit to regular exercise throughout their lives is a viable solution to the problem that we are living longer but not healthier."
Dr Niharika Arora Duggal, also of the University of Birmingham, said: "We hope these findings prevent the danger that, as a society, we accept that old age and disease are normal bedfellows and that the third age of man is something to be endured and not enjoyed."
Professor Stephen Harridge, Director of the Centre of Human & Aerospace Physiological Sciences at King's College London, said: "The findings emphasise the fact that the cyclists do not exercise because they are healthy, but that they are healthy because they have been exercising for such a large proportion of their lives.
"Their bodies have been allowed to age optimally, free from the problems usually caused by inactivity. Remove the activity and their health would likely deteriorate."
Norman Lazarus, Emeritus Professor at King's College London and also a master cyclist and Dr Ross Pollock, who undertook the muscle study, both agreed that: "Most of us who exercise have nowhere near the physiological capacities of elite athletes.
"We exercise mainly to enjoy ourselves. Nearly everybody can partake in an exercise that is in keeping with their own physiological capabilities.
"Find an exercise that you enjoy in whatever environment that suits you and make a habit of physical activity. You will reap the rewards in later life by enjoying an independent and productive old age."
The research findings are detailed in two papers published today in Aging Cell and are the result of an ongoing joint study by the two universities, funded by the BUPA foundation.
Read more at Science Daily
Mar 8, 2018
Hawaiian stick spiders re-evolve the same three guises every time they island hop
 |
| This picture shows an undescribed species of Ariamnes from Molokai, Hawaiian Archipelago. Gillespie et al. describe an adaptive radiation of stick spiders that demonstrate repeated evolution of a discrete set of ecomorphs -- gold (shown here), dark, and matte white. The deterministic evolution of forms is associated with camouflage against a limited set of island predators, reduced dispersal and cursoriality, coupled with conserved pathways of color formation. |
The stick spiders live in the forests of the Hawaiian archipelago, over 2,000 feet above sea level, on the islands of Kauai, Oahu, Molokai, Maui, and Hawaii. Although they're nocturnal arthropods that can't see well, they're still brightly and distinctly colored. "You've got this dark one that lives in rocks or in bark, a shiny and reflective gold one that lives under leaves, and this one that's a matte white, completely white, that lives on lichen," explains Rosemary Gillespie, an evolutionary biologist at the University of California, Berkeley.
These different colorings allow the spiders to camouflage themselves against specific similarly colored surfaces in their respective habitats and avoid their major predator, birds called Hawaiian honeycreepers. But what's remarkable is that as the spiders have moved from one island to the next during their evolutionary history, these same forms have evolved over and over again. This process produces new species that are more closely related to spiders of different forms on the same island than they are to lookalikes from other islands.
And it happens fast -- at least in evolutionary time. A dark spider that hops from an old island to a new one can diversify into new species of dark, gold, and white spiders before gold and white spiders from the old island have time to reach the new one. "They arrive on an island, and boom! You get independent evolution to the same set of forms," Gillespie says.
It's also important that these forms are the same each time. "They don't evolve to be orange or striped. There isn't any additional diversification," she says. This, she believes, suggests that the Ariamnes spiders have some sort of preprogrammed switch in their DNA that can be quickly turned on to allow them to evolve rapidly into these successful forms. But how that process might work is still unclear.
It hasn't really been studied, because ecomorphs aren't common. "Most radiations just don't do this," she says. Typical adaptive radiation, like with Darwin's finches, usually produces a wide diversity of forms. And convergent evolution, where two different species independently evolve the same strategy for fulfilling a certain niche, doesn't usually happen repeatedly. There are just a few good examples of this kind of fixed pattern of repeated evolution: the Ariamnes spiders, the Hawaiian branch of the Tetragnatha genus of long-jawed spiders, and the Anolis lizards of the Caribbean.
"Now we're thinking about why it's only in these kinds of organisms that you get this sort of rapid and repeated evolution," Gillespie says. While it's a question she's still working on, the three lineages do all live in remote locations, have few predators, and rely on their coloring to camouflage them in a very particular habitat. They are also all free living in the vegetation: neither of the two spider groups builds a web, which means that they, like the lizards, are free to move about and find the kind of habitat they require for camouflage. She hopes that examining what these groups have in common will "provide insight into what elements of evolution are predictable, and under which circumstances we expect evolution to be predictable and under which we do not."
Read more at Science Daily
A peculiar galactic clash
 |
| Arp 256 is a stunning system of two spiral galaxies, about 350 million light-years away, in an early stage of merging. The image, taken with the NASA/ESA Hubble Space Telescope, displays two galaxies with strongly distorted shapes and an astonishing number of blue knots of star formation that look like exploding fireworks. The star formation was triggered by the close interaction between the two galaxies. |
350 million light-years away in the constellation of Cetus (the Sea Monster), a pair of barred spiral galaxies have just begun a magnificent merger. This image suspends them in a single moment, freezing the chaotic spray of gas, dust and stars kicked up by the gravitational forces pulling the two galaxies together.
Though their nuclei are still separated by a large distance, the shapes of the galaxies in Arp 256 are impressively distorted. The galaxy in the upper part of the image contains very pronounced tidal tails -- long, extended ribbons of gas, dust and stars.
The galaxies are ablaze with dazzling regions of star formation: the bright blue fireworks are stellar nurseries, churning out hot infant stars. These vigorous bursts of new life are triggered by the massive gravitational interactions, which stir up interstellar gas and dust out of which stars are born.
Arp 256 was first catalogued by Halton Arp in 1966, as one of 338 galaxies presented in the aptly-named Atlas of Peculiar Galaxies. The goal of the catalogue was to image examples of the weird and wonderful structures found among nearby galaxies, to provide snapshots of different stages of galactic evolution. These peculiar galaxies are like a natural experiment played out on a cosmic scale and by cataloguing them, astronomers can better understand the physical processes that warp spiral and elliptical galaxies into new shapes.
Many galaxies in this catalogue are dwarf galaxies with indistinct structures, or active galaxies generating powerful jets -- but a large number of the galaxies are interacting, such as Messier 51, the Antennae Galaxies, and Arp 256. Such interactions often form streamer-like tidal tails as seen in Arp 256, as well as bridges of gas, dust and stars between the galaxies.
Long ago, when our expanding Universe was much smaller, interactions and mergers were more common; in fact, they are thought to drive galactic evolution to this day. The galaxies in the Arp 256 system will continue their gravitational dance over the next millions of years, at first flirtatious, and then intimate, before finally morphing into a single galaxy.
Read more at Science Daily
Water's mysterious phase transitions
 |
| Frost. |
Angell, a Regents Professor in ASU's School of Molecular Sciences, has spent a good portion of his distinguished career tracking down some of water's more curious physical properties. In a new piece of research just published in Science (March 9), Angell and colleagues from the University of Amsterdam have, for the first time, observed one of the more intriguing properties predicted by water theoreticians -- that, on sufficient super-cooling and under specific conditions it will suddenly change from one liquid to a different one. The new liquid is still water but now it is of lower density and with a different arrangement of the hydrogen bonded molecules with stronger bonding that makes it a more viscous liquid.
"It has nothing to do with 'poly-water,'" Angell adds recalling a scientific fiasco of many decades ago. The new phenomenon is a liquid-liquid phase transition, and until now it had only been seen in computer simulations of water models.
The problem with observing this phenomenon directly in real water is that, shortly before the theory says it should happen, the real water suddenly crystallizes to ice. This has been called the "crystallization curtain" and it held up progress in understanding water physics and water in biology for decades.
"The domain between this crystallization temperature and the much lower temperature at which glassy water (formed by deposition of water molecules from the vapor) crystallizes during heating has been known as a 'no-man's land,'" Angell said. "We found a way to pull aside the 'crystallization curtain' just enough to see what happens behind -- or more correctly, below -- it," Angell said.
Phase transitions of water are important to understand for a multitude of applications. For example, the well-known and destructive heaving of concrete roads and footpaths in winter is due to the phase transition from water to ice under the concrete. The phase transition between liquid states, described in the current work, has much in common with the transition to ice but it occurs at a much lower temperature, about -90 C (-130 F), and only under super-cooled conditions so it is likely to remain mostly a scientific curiosity for the foreseeable future.
Angell explained that a couple of years ago he and his research associate Zuofeng Zhao, were studying the thermal behavior of a special type of "ideal" aqueous solution they had been using to explore the folding and unfolding of globular proteins. They wanted to observe these solutions' ability to supercool and then vitrify. Seeking the limit to the glassy domain, they added extra water to enhance the probability of ice crystallization and found that instead of finally evolving heat as ice crystallized (leaving a residual unfrozen solution) as is normally found when cooling saline solutions, it actually gave off heat to form a new liquid phase.
The new liquid was much more viscous, maybe even glassy. Furthermore, by reversing the direction of the temperature change, Angell and Zhao found that they could transform the new phase back into the original solution before any ice would start to crystallize.
"This observation, published in Angewandte Chemie, raised considerable interest but there was no structural information to explain what was happening," Angell said. That changed when Angell visited the University of Amsterdam two summers ago, and met Sander Woutersen, a specialist in infrared spectroscopy who became very interested in the structural aspects of the phenomenon.
In the Science paper, the team with Woutersen, his student Michiel Hilbers and his computational colleague Bernd Ensing has now shown that the structures involved in the liquid-liquid transition have the same spectroscopic signatures -- and the same hydrogen bonding patterns -- as are seen in the two known glassy forms of ice produced by laborious alternative processes (high- and low-density amorphous solid phases of water).
"The liquid-liquid transition we had found was now seen to be the 'living analog' of the change between two glassy states of pure water that had been reported in 1994, using pure pressure as the driving force," Angell explained.
Read more at Science Daily
NASA Juno finds Jupiter's jet-streams are unearthly
 |
| This composite image, derived from data collected by the Jovian Infrared Auroral Mapper (JIRAM) instrument aboard NASA's Juno mission to Jupiter, shows the central cyclone at the planet's north pole and the eight cyclones that encircle it. |
Other Juno science results released today include that the massive cyclones that surround Jupiter's north and south poles are enduring atmospheric features and unlike anything else encountered in our solar system. The findings are part of a four-article collection on Juno science results being published in the March 8 edition of the journal Nature.
"These astonishing science results are yet another example of Jupiter's curve balls, and a testimony to the value of exploring the unknown from a new perspective with next-generation instruments.Juno's unique orbit and evolutionary high-precision radio science and infrared technologies enabled these paradigm-shifting discoveries," said Scott Bolton, principal investigator of Juno from the Southwest Research Institute, San Antonio. "Juno is only about one third the way through its primary mission, and already we are seeing the beginnings of a new Jupiter."
The depth to which the roots of Jupiter's famous zones and belts extend has been a mystery for decades. Gravity measurements collected by Juno during its close flybys of the planet have now provided an answer.
"Juno's measurement of Jupiter's gravity field indicates a north-south asymmetry, similar to the asymmetry observed in its zones and belts," said Luciano Iess, Juno co-investigator from Sapienza University of Rome, and lead author on a Nature paper on Jupiter's gravity field.
On a gas planet, such an asymmetry can only come from flows deep within the planet; and on Jupiter, the visible eastward and westward jet streams are likewise asymmetric north and south. The deeper the jets, the more mass they contain, leading to a stronger signal expressed in the gravity field. Thus, the magnitude of the asymmetry in gravity determines how deep the jet streams extend.
"Galileo viewed the stripes on Jupiter more than 400 years ago," said Yohai Kaspi, Juno co-investigator from the Weizmann Institute of Science, Rehovot, Israel,and lead author of a Nature paper on Jupiter's deep weather layer. "Until now, we only had a superficial understanding of them and have been able to relate these stripes to cloud features along Jupiter's jets. Now, following the Juno gravity measurements, we know how deep the jets extend and what their structure is beneath the visible clouds. It's like going from a 2-D picture to a 3-D version in high definition."
The result was a surprise for the Juno science team because it indicated that the weather layer of Jupiter was more massive, extending much deeper than previously expected. The Jovian weather layer, from its very top to a depth of 1,900 miles (3,000 kilometers), contains about one percent of Jupiter's mass (about 3 Earth masses).
"By contrast, Earth's atmosphere is less than one millionth of the total mass of Earth," said Kaspi "The fact that Jupiter has such a massive region rotating in separate east-west bands is definitely a surprise."
The finding is important for understanding the nature and possible mechanisms driving these strong jet streams. In addition, the gravity signature of the jets is entangled with the gravity signal of Jupiter's core.
Another Juno result released today suggests that beneath the weather layer, the planet rotates nearly as a rigid body."This is really an amazing result, and future measurements by Juno will help us understand how the transition works between the weather layer and the rigid body below," said Tristan Guillot, a Juno co-investigator from the Université Côte d'Azur, Nice, France, and lead author of the paper on Jupiter's deep interior. "Juno's discovery has implications for other worlds in our solar system and beyond. Our results imply that the outer differentially-rotating region should be at least three times deeper in Saturn and shallower in massive giant planets and brown dwarf stars."
A truly striking result released in the Nature papers is the beautiful new imagery of Jupiter's poles captured by Juno's Jovian Infrared Auroral Mapper (JIRAM) instrument. Imaging in the infrared part of the spectrum, JIRAM captures images of light emerging from deep inside Jupiter equally well, night or day. JIRAM probes the weather layer down to 30 to 45 miles (50 to 70 kilometers) below Jupiter's cloud tops.
"Prior to Juno we did not know what the weather was like near Jupiter's poles. Now, we have been able to observe the polar weather up-close every two months," said Alberto Adriani, Juno co-investigator from the Institute for Space Astrophysics and Planetology, Rome, and lead author of the paper. "Each one of the northern cyclones is almost as wide as the distance between Naples, Italy and New York City -- and the southern ones are even larger than that. They have very violent winds, reaching, in some cases, speeds as great as 220 mph (350 kph). Finally, and perhaps most remarkably, they are very close together and enduring. There is nothing else like it that we know of in the solar system."
Jupiter's poles are a stark contrast to the more familiar orange and white belts and zones encircling the planet at lower latitudes. Its north pole is dominated by a central cyclone surrounded by eight circumpolar cyclones with diameters ranging from 2,500 to 2,900 miles (4,000 to 4,600 kilometers) across. Jupiter's south pole also contains a central cyclone, but it is surrounded by five cyclones with diameters ranging from 3,500 to 4,300 miles (5,600 to 7,000 kilometers) in diameter. Almost all the polar cyclones, at both poles, are so densely packed that their spiral arms come in contact with adjacent cyclones. However, as tightly spaced as the cyclones are, they have remained distinct, with individual morphologies over the seven months of observations detailed in the paper.
"The question is, why do they not merge?" said Adriani. "We know with Cassini data that Saturn has a single cyclonic vortex at each pole. We are beginning to realize that not all gas giants are created equal."
Read more at Science Daily
Mar 7, 2018
Hubble finds huge system of dusty material enveloping the young star HR 4796A
 |
| Hubble uncovers a vast, complex dust structure, about 150 billion miles across, enveloping the young star HR 4796A. A bright, narrow inner ring of dust is already known to encircle the star, based on much earlier Hubble images. This newly discovered huge dust structure around the system may have implications for what a yet-unseen planetary system looks like around the 8-million-year-old star. |
The debris field of very fine dust was likely created from collisions among developing infant planets near the star, evidenced by a bright ring of dusty debris seen 7 billion miles from the star. The pressure of starlight from the star, which is 23 times more luminous than the Sun, then expelled the dust far into space.
But the dynamics don't stop there. The puffy outer dust structure is like a donut-shaped inner tube that got hit by a truck. It is much more extended in one direction than in the other and so looks squashed on one side even after accounting for its inclined projection on the sky. This may be due to the motion of the host star plowing through the interstellar medium, like the bow wave from a boat crossing a lake. Or it may be influenced by a tidal tug from the star's red dwarf binary companion (HR 4796B), located at least 54 billion miles from the primary star.
"The dust distribution is a telltale sign of how dynamically interactive the inner system containing the ring is," said Glenn Schneider of the University of Arizona, Tucson, who used Hubble's Space Telescope Imaging Spectrograph (STIS) to probe and map the small dust particles in the outer reaches of the HR 4796A system, a survey that only Hubble's sensitivity can accomplish.
"We cannot treat exoplanetary debris systems as simply being in isolation. Environmental effects, such as interactions with the interstellar medium and forces due to stellar companions, may have long-term implications for the evolution of such systems. The gross asymmetries of the outer dust field are telling us there are a lot of forces in play (beyond just host-star radiation pressure) that are moving the material around. We've seen effects like this in a few other systems, but here's a case where we see a bunch of things going on at once," Schneider further explained.
Read more at Science Daily
Genetic Hack Makes Plants Use 25 Percent Less Water
 |
| Tobacco plants |
By altering a single gene, scientists coaxed tobacco plants — a model crop often used in experiments — to grow to near normal size with only 75 percent of the water they usually require.
If major food crops respond the same way, they said, the first-of-its-kind genetic "hack" could help feed the growing population of an increasingly water-starved world.
"This is a major breakthrough," said senior author Stephen Long, a professor at the Institute of plant biology at the University of Illinois.
"When water is limited, these modified plants will grow faster and yield more."
The findings were reported in the journal Nature Communications.
Today, 1.2 billion people live in regions where water is scarce, and four billion — two-thirds of humanity — experience scarcity at least one month every year.
By 2030, the planet will face a 40 percent water deficit if global warming continues at its current pace, according to the UN World Water Development report.
Agriculture guzzles three-quarters of all groundwater withdrawals — 90 percent in poor countries.
"Making crop plants more water-use efficient is arguably the greatest challenge for current and future plant scientists," said lead author Johannes Kromdijk, also from the University of Illinois.
Long and his team tweaked the gene that codes a protein — known as PsbS — crucial to photosynthesis, the process by which plants convert light into nutrients.
PsbS plays a key role in relaying information about the quantity of daylight, which triggers the opening and closing of microscopic leaf pores called stomata.
Some Help From Global Warming
When stomata are open, plants can absorb the CO2 needed for photosynthesis.
At the same time, however, water also escapes into the air.
In the genetically engineered plants, increased levels of PsbS caused the tiny leaf pores to close earlier than they normally would, allowing the plant to retain more precious liquid.
Ironically, this gain in water storage is only made possible by global warming, which has increased the concentration of carbon dioxide in the atmosphere by about 25 percent since 1950.
In the experiments, the tobacco plants could take in enough CO2 — despite the stomata's shortened work day — because of this higher concentration.
"Evolution has not kept pace with this rapid change, so scientists have given it a helping hand," said Long.
Read more at Seeker
This New Technique May Be Able to Boost Gravitational-Wave Detection
To spot these space-time ripples, which have traveled billions of light-years in some cases, scientists must build some of the most sensitive equipment the world has ever seen. But the very sensitivity of this gear means that vibrations, turbulence, and even gas molecules in our atmosphere can drown out even the most powerful gravitational-wave signals in a crescendo of background noise.
Ingenious engineering solutions are therefore needed to pull the weak signal of gravitational waves out of the noise. In new research published in the journal Physical Review Letters, physicists describe a potentially powerful new method that could, theoretically, be used to remove a key component of noise from gravitational-wave detectors and, in doing so, remove the requirement of having to build costly and complex vacuum chambers.
A Sensitive Business
In September 2015, the historic first gravitational-wave signal, caused by two colliding black holes, was spotted by the Laser Interferometer Gravitational-wave Observatory (LIGO), a project that operates two detectors — one in Washington and the other in Louisiana.
This detection was achieved by using powerful "interferometers" that can detect minuscule warps in space-time. The twin L-shaped LIGO buildings measure 2.5 miles (4 kilometers) along each arm and consist of highly efficient vacuum chambers through which the lasers and all optics are directed. Based on the principle of Michelson interferometers, from the famous Michelson-Morley experiment in 1887, laser light is directed from one end of the L to a beam splitter at the intersection. The split laser light is then reflected back and forth along the tunnels and then allowed to converge once again at the intersection, after the photons have traveled 700 miles (1,120 km).
When the two laser beams are recombined, they cancel each other out, as both have traveled the exact same distance along their respective tunnels; the waves of laser light are finely tuned to be out of phase and will therefore destructively interfere with one another. However, should a gravitational wave travel through our planet, one of the detector's arms will distort slightly, causing one of the beams to travel a slightly longer or shorter distance, creating a tiny mismatch in phase. The fine-tuning is knocked out of balance, the waves constructively interfere and a signal is recorded. It's like a high-tech trip wire for gravitational waves. And the ripples cause a minuscule fluctuation in distance; LIGO can detect a change in arm length thousands of times smaller than the width of a proton.
Because this signal is so slight, physicists must ensure that sources of noise are kept to a minimum. So the entire system is encased inside a vacuum chamber (to remove sources of noise, such as air turbulence, sound waves, and gas molecules), and the mirrors and other optics are shielded from other sources of vibrations, such as seismic waves and even nearby traffic.
"The main challenge in the LIGO vacuum tubes is to keep the pressure low; we need it to be around a trillion times less than atmospheric pressure," said LIGO team member Rana Adhikari, a professor of physics at the California Institute of Technology in Pasadena, who wasn’t involved in the new study. "This is relatively easy in a small, high-quality, laboratory setup but extremely challenging for a 4-kilometer-long tube."
From 2010 to 2015, LIGO underwent significant detector upgrades to reduce distortions in its mirrors and even molecular-scale vibrations in the system that kept the ultraprecise mirrors isolated from noise. After this upgrade, the sensitivity of "Advanced LIGO" (or aLIGO) was such that, after a 13-year search, gravitational waves were finally discovered. Advanced LIGO has now been joined by the Advanced Virgo detector, located near Pisa, Italy, and partnerships with more international detectors are being planned.
 |
| The Laser Interferometer Gravitational-wave Observatory (LIGO) facility in Louisiana. Another LIGO detector operates in Washington state. |
One of the biggest components of current gravitational-wave detectors is the vacuum chamber where all the interferometer optics are housed — a component that, according to the new study, could be removed from future gravitational-wave interferometers.>
"What we demonstrate in our paper was a turbulence-free double-slit interferometer, which isn't exactly ideal for gravitational-wave detection, but the mechanism that produces the turbulence-free interference can theoretically be applied to any interferometer," said lead author Thomas Smith, a postgraduate from the University of Maryland, Baltimore County (UMBC).
"Our future steps are to look at those interferometers that are ideal for gravitational-wave detection by their layout and see if we can apply this mechanism to those," Smith added. "We could, theoretically, have a gravitational-wave detector out in the open air."
In the study, Smith and Yanhua Shih, a physics professor also at UMBC, argue that the quantum properties of light could be used as a powerful and, potentially, revolutionary new tool for dealing with interferometer noise and detecting even the weakest gravitational-wave signals.
Weird Physics
The experimental setup proposed by Smith and Shih is based on an 1801 double-slit experiment devised by English physicist Thomas Young to demonstrate the wave theory of light. It was later used to demonstrate the wave-particle duality concept in quantum mechanics in the early 20th century. In its most basic form, the experiment consists of a light source that illuminates a plate, which has two slits for light to pass through. Behind the plate is a screen. As the light passes through the slits, the waves constructively and destructively interfere, creating a classic pattern of light and dark bands on the screen.
But what if you were to fire just one photon at the slits? Well, through the weirdness of quantum physics, that photon is just as probable to travel through slit A as it is slit B and can therefore interfere with itself to create an interference pattern on the screen. (For an in-depth explanation, read this classic Space.com piece.) This is a useful demonstration of quantum physics, but it would be useless in a gravitational-wave detector; single photons will be affected by air turbulence, so the paths to slit A and slit B will vary, jumbling the photons' phase and blurring out any interference pattern.
So, Smith and Shih suggested that, instead of the one-photon interference, two-photon interference patterns can be measured, and the noise that muddles the one-photon interference pattern will simply disappear from the equation. Much of the detail behind this method is buried in complex math, but it could provide a surprisingly elegant solution for laser interferometers, the researchers said.
Two-photon interference "is kind of a new concept in physics in the past few decades, and it seems to be catching hold," Smith told Space.com. "You can have two potential paths for the two photons to travel. And when you scan your two detectors in approximately the same location, these two potential paths for the two photons overlap. And, because of that overlap, both potential paths experience the same turbulence, the same phase shifts. And, because they're experiencing the same phase shifts, the interference pattern is unaffected … Within the math, the turbulence cancels."
The researchers even demonstrated this method with a tabletop experiment incorporating a laser light source, double slits, and a toaster oven in between to create air turbulence. When the oven is turned on, the classic interference pattern abruptly disappears; the air turbulence disrupts the photons, preventing interference from occurring. But if you carefully position two detectors to precisely measure the two-photon interference pattern and then turn the oven on, the interference pattern persists as if there were no turbulence at all.
"The classic interference pattern disappeared [when the oven was switched on], but the interference pattern we measured from the intensity fluctuation correlation in this turbulence-free interferometer remained at nearly 100 percent — still very clear," Shih said.
In this situation, the researchers can measure the pattern generated when pairs of photons interfere with themselves after traveling the same path from the coherent light source to the slits. In effect, these pairs of photons experience the exact same turbulence during their journey, like two passengers sitting next to each other on a roller-coaster ride. Sure, the two passengers will experience a lot of ups, downs, loops, and wobbles, but they will arrive at the end of the ride having traveled along the exact same path. Like the roller-coaster passengers, to the pairs of photons (and the interference pattern they create), it's as if the air turbulence weren't even there.
By the researchers' logic, if this system could be scaled up and somehow incorporated into the optical system of gravitational-wave interferometers, these detectors could function in the open air, and highly efficient vacuum systems would no longer be required. And once this complex system was removed, the possibilities would become very exciting.
"We could have one station on the surface of Earth and others on satellites … We could make a much bigger interferometer that would be much more sensitive than the ones we currently have," Shih said. The bigger the interferometer, he said, the more sensitive the detector would become to weaker and lower-frequency gravitational waves.
 |
| A simplified layout of the Advanced LIGO detector. |
The researchers emphasized that turbulence-free interferometry has a long way to go before it can be used for gravitational-wave detectors. But gravitational-wave scientists are skeptical that highly efficient vacuum tubes will ever be removed from ground-based detectors.
"Our detectors could not work in 'open air,'" Nicolas Arnaud, a physicist with the Virgo experiment, told Space.com via email. "The mirrors (key interferometer components) would lose their unique properties, as their surface would be contaminated by dust; and dust particles would actually be burnt due to the high laser power incident on the mirrors, damaging their surface more. In addition, the laser beams traveling along the kilometers-long detector arms would undergo scattering due to air, which would impact the detector sensitivity."
Although he agrees that the theory behind two-photon interference as a method to remove atmospheric turbulence is interesting, Adhikari argues that a far more significant problem is the noise caused by laser light hitting gas molecules in the air.
"If we allow the pressure to get 10 times higher than our goal, we run into problems with light scattering from gas molecules," Adhikari told Space.com via email. "Each molecule makes a little twinkle as it passes through the beam, and the stochastic [chaotic] motion of many individual molecules makes a noise in our beam. It's like covering up the 'chirp' made by gravitational waves with a hiss.
"While I imagine their setup can be used to reduce the noise due to turbulent air motion, it would have to also reduce the stochastic scintillation (not due to turbulence) by a factor of 1 million to make gravitational-wave detection feasible," Adhikari said.
However, in the two-photon setup, only coherent light will create the required interference pattern. As this stochastic interference is, by definition, incoherent, Shih pointed out that this source of noise will also be removed from the results. "These kinds of scintillation, in principle, will not have any contribution to the intensity fluctuation correlation," he said.
Although this may work for small interferometers, scaling it up for use in "open-air" gravitational-wave detectors would mean there are many gas molecules being hit by laser light, attenuating the laser energy and making it inefficient at detecting gravitational waves.
Read more at Seeker
Artificial Photoreceptors Restore Sight in Blind Mice
Retinal diseases like macular degeneration and retinitis pigmentosa slowly rob people of their sight as the rods and cones in the retina gradually atrophy and fail. One of the only hopes for averting total blindness in those cases is to receive a “bionic eye,” a wireless retinal implant that receives electrical signals from a video camera worn on a pair of sunglasses.
These bionic devices, while potentially life-changing for people with total vision loss, have some limitations: They can only be implanted in one eye, they require patients to wear a power source and processor at all times, and even the best cases report a very low visual acuity of 20/1200 with no color recognition and few perceptible details.
Now a team of Chinese researchers believes it has developed a new type of retinal prosthesis that restores full-color vision without any external power or processors. The implant replaces the malfunctioning layer of rods and cones with artificial photoreceptors made from gold-titania nanowires, according to a paper in Nature Communications.
The retina is a thin membrane on the back of the eye that converts incoming light into electrical signals that are then processed by the brain. The retina is only half a millimeter thick, but contains three distinct cellular layers. The bottom layer, farthest from the light source, holds the rods and cones, also known as photoreceptor cells. It’s the photoreceptor layer that’s compromised in people with retinal diseases.
The top layer of the retina is formed by glial cells, a type of neuron or nerve cell typically found in the brain. It’s the glial cells that capture the electrical impulses from the photoreceptors and channel them through the optic nerve to be processed by the brain into images.
Back in the 1980s, scientists discovered that they could bypass the photoreceptor layer entirely and send electrical impulses directly to the glial cells. Since glial cells are usually unaffected in patients with macular degeneration and retinitis pigmentosa, researchers started looking for ways to replace the faulty photoreceptor layer with implanted electrodes.
The Argus II Retinal Prosthesis System developed by California-based Second Sight is the current state-of-the-art solution. An external video camera worn on a pair of sunglasses captures images that are sent to a small video-processing unit carried by the patient. The images are translated into electrical signals that are transmitted wirelessly to an electrode array implanted in the back of the eye. The implant broadcasts the electrical signals to the glial cells, which carry them to the brain.
The Argus II is marketed as a “humanitarian device,” not a cure for blindness. With lots of training, patients slowly learn to interpret what they’re seeing — flashes of contrasting light and blurry shapes — as familiar faces and objects. But the idea of the implant was never to recover full vision.
The Chinese approach seems to offer new hope for people with congenital or degenerative retinal diseases. The idea is to replace the retina’s biological photoreceptors with artificial cells that carry the same innate ability to convert light into electricity.
Jiayi Zhang and Gengfeng Zheng at Fudan University in Shanghai developed semiconducting nanowires of titania flecked with gold nanoparticles that replicate the retina’s real photoreceptors in both form and function. In an email, Zhang told Seeker that the nanowires have a pillar structure like rods and cones, and can convert light into electricity without the need of an outside power source.
The Chinese research team used the pillar-like nanowires to make a tiny photodiode array that could be implanted directly into the retina of blind mice. To test if the implant successfully restored vision, they implanted a second electrode array in each mouse’s visual cortex to record the electrical signals transmitted from the eye’s glial cells.
Five months post-surgery, wrote Zhang, the mice with nanowire retinal implants produced responses in the visual cortex that were similar to wild-type mice with no history of retinal disease.
Read more at Seeker
Mar 6, 2018
How a fish species in Lake Tanganyika works together to secure additional food sources
 |
| These are helpers of Neolamprologus obscurus in their nest. |
Neolamprologus obscurus is a highly sociable species of cichlid found only in the southern reaches of Lake Tanyanika. These zebra-striped fish feed mainly on shrimp and other invertebrates found along the bottom of the lake. At night, shrimp move into the water column, but by dawn they sink back to the lake bottom to hide in crevices and holes, including the shelters that the fish have dug out under stones. Such excavation work is always done as a group, as is subsequent maintenance efforts. Breeding fish seldom leave these safe havens and are supported by up to ten helpers from their family group. The helpers protect the brood, and constantly remove sand and debris that fall into the cavities.
"The function of these excavated cavities is much like that of the webs of social spiders, which live in groups and share the trapped prey among group members," explains Tanaka.
In this study, Tanaka and his colleagues wanted to find out if the size of the cavities at the bottom of the lake relate to the abundance of food available in the area, and if the presence of helpers influences the size. Through hours of scuba diving in Lake Tanyanika, the researchers created artificial cavities and examined the stomach contents of some of the fish. In another experiment, the researchers removed helpers that were assisting breeding fish. Within a week, enough sand had fallen into the cavities to decidedly shrink these spaces. This effect was augmented when the helpers removed were big.
One of the key findings was that the size of an excavated crevice had an influence on the amount of shrimps that subsequently gathered in it. When there were more helpers around, the space that could be created was bigger and more shrimps could be gathered.
"Helpers in Neolamprologus obscurus extend and maintain the excavated cavities, and by doing so, contribute to an increase in food abundance inside the territory of breeding females," explains Tanaka.
Read more at Science Daily
Photosynthesis originated a billion years earlier than we thought, study shows
 |
| This image is the crystal structure of Photosystem I. |
Ancient microbes may have been producing oxygen through photosynthesis a billion years earlier than we thought, which means oxygen was available for living organisms very close to the origin of life on earth. In a new article in Heliyon, a researcher from Imperial College London studied the molecular machines responsible for photosynthesis and found the process may have evolved as long as 3.6 billion years ago.
The author of the study, Dr. Tanai Cardona, says the research can help to solve the controversy around when organisms started producing oxygen -- something that was vital to the evolution of life on earth. It also suggests that the microorganisms we previously believed to be the first to produce oxygen -- cyanobacteria -- evolved later, and that simpler bacteria produced oxygen first.
"My results mean that the process that sustains almost all life on earth today may have been doing so for a lot longer than we think," said Dr. Cardona. "It may have been that the early availability of oxygen was what allowed microbes to diversify and dominate the world for billions of years. What allowed microbes to escape the cradle where life arose and conquer every corner of this world, more than 3 billion years ago."
Photosynthesis is the process that sustains complex life on earth -- all of the oxygen on our planet comes from photosynthesis. There are two types of photosynthesis: oxygenic and anoxygenic. Oxygenic photosynthesis uses light energy to split water molecules, releasing oxygen, electrons and protons. Anoxygenic photosynthesis use compounds like hydrogen sulfide or minerals like iron or arsenic instead of water, and it does not produce oxygen.
Previously, scientists believed that anoxygenic evolved long before oxygenic photosynthesis, and that the earth's atmosphere contained no oxygen until about 2.4 to 3 billion years ago. However, the new study suggests that the origin of oxygenic photosynthesis may have been as much as a billion years earlier, which means complex life would have been able to evolve earlier too.
Dr. Cardona wanted to find out when oxygenic photosynthesis originated. Instead of trying to detect oxygen in ancient rocks, which is what had been done previously, he looked deep inside the molecular machines that carry out photosynthesis -- these are complex enzymes called photosystems. Oxygenic and anoxygenic photosynthesis both use an enzyme called Photosystem I. The core of the enzyme looks different in the two types of photosynthesis, and by studying how long ago the genes evolved to be different, Dr. Cardona could work out when oxidative photosynthesis first occurred.
He found that the differences in the genes may have occurred more than 3.4 billion years ago -- long before oxygen was thought to have first been produced on earth. This is also long before cyanobacteria -- microbes that were thought to be the first organisms to produce oxygen -- existed. This means there must have been predecessors, such as early bacteria, that have since evolved to carry out anoxygenic photosynthesis instead.
"This is the first time that anyone has tried to time the evolution of the photosystems," said Dr. Cardona. "The result hints towards the possibility that oxygenic photosynthesis, the process that have produced all oxygen on earth, actually started at a very early stage in the evolutionary history of life -- it helps solve one of the big controversies in biology today."
One surprising finding was that the evolution of the photosystem was not linear. Photosystems are known to evolve very slowly -- they have done so since cyanobacteria appeared at least 2.4 billion years ago. But when Dr. Cardona used that slow rate of evolution to calculate the origin of photosynthesis, he came up with a date that was older than the earth itself. This means the photosystem must have evolved much faster at the beginning -- something recent research suggests was due to the planet being hotter.
Read more at Science Daily
Technique to see objects hidden around corners
 |
| Illustration of the non-line-of-sight imaging system. |
This scenario is one of many that researchers at Stanford University are imagining for a system that can produce images of objects hidden from view. They are focused on applications for autonomous vehicles, some of which already have similar laser-based systems for detecting objects around the car, but other uses could include seeing through foliage from aerial vehicles or giving rescue teams the ability to find people blocked from view by walls and rubble.
"It sounds like magic but the idea of non-line-of-sight imaging is actually feasible," said Gordon Wetzstein, assistant professor of electrical engineering and senior author of the paper describing this work, published March 5 in Nature.
Seeing the unseen
The Stanford group isn't alone in developing methods for bouncing lasers around corners to capture images of objects. Where this research advances the field is in the extremely efficient and effective algorithm the researchers developed to process the final image.
"A substantial challenge in non-line-of-sight imaging is figuring out an efficient way to recover the 3-D structure of the hidden object from the noisy measurements," said David Lindell, graduate student in the Stanford Computational Imaging Lab and co-author of the paper. "I think the big impact of this method is how computationally efficient it is."
For their system, the researchers set a laser next to a highly sensitive photon detector, which can record even a single particle of light. They shoot pulses of laser light at a wall and, invisible to the human eye, those pulses bounce off objects around the corner and bounce back to the wall and to the detector. Currently, this scan can take from two minutes to an hour, depending on conditions such as lighting and the reflectivity of the hidden object.
Once the scan is finished, the algorithm untangles the paths of the captured photons and, like the mythical image enhancement technology of television crime shows, the blurry blob takes much sharper form. It does all this in less than a second and is so efficient it can run on a regular laptop. Based on how well the algorithm currently works, the researchers think they could speed it up so that it is nearly instantaneous once the scan is complete.
Into the 'wild'
The team is continuing to work on this system, so it can better handle the variability of the real world and complete the scan more quickly. For example, the distance to the object and amount of ambient light can make it difficult for their technology to see the light particles it needs to resolve out-of-sight objects. This technique also depends on analyzing scattered light particles that are intentionally ignored by guidance systems currently in cars -- known as LIDAR systems.
"We believe the computation algorithm is already ready for LIDAR systems," said Matthew O'Toole, a postdoctoral scholar in the Stanford Computational Imaging Lab and co-lead author of the paper. "The key question is if the current hardware of LIDAR systems supports this type of imaging."
Before this system is road ready, it will also have to work better in daylight and with objects in motion, like a bouncing ball or running child. The researchers did test their technique successfully outside but they worked only with indirect light. Their technology did perform particularly well picking out retroreflective objects, such as safety apparel or traffic signs. The researchers say that if the technology were placed on a car today, that car could easily detect things like road signs, safety vests or road markers, although it might struggle with a person wearing non-reflective clothing.
Read more at Science Daily
Massive astrophysical objects governed by subatomic equation
 |
| Schrödinger in Space: An artist's impression of research presented in Batygin (2018), MNRAS 475, 4. Propagation of waves through an astrophysical disk can be understood using Schrödinger's equation - a cornerstone of quantum mechanics. |
The work, done by Konstantin Batygin, a Caltech assistant professor of planetary science and Van Nuys Page Scholar, is described in a paper appearing in the March 5 issue of Monthly Notices of the Royal Astronomical Society.
Massive astronomical objects are frequently encircled by groups of smaller objects that revolve around them, like the planets around the sun. For example, supermassive black holes are orbited by swarms of stars, which are themselves orbited by enormous amounts of rock, ice, and other space debris. Due to gravitational forces, these huge volumes of material form into flat, round disks. These disks, made up of countless individual particles orbiting en masse, can range from the size of the solar system to many light-years across.
Astrophysical disks of material generally do not retain simple circular shapes throughout their lifetimes. Instead, over millions of years, these disks slowly evolve to exhibit large-scale distortions, bending and warping like ripples on a pond. Exactly how these warps emerge and propagate has long puzzled astronomers, and even computer simulations have not offered a definitive answer, as the process is both complex and prohibitively expensive to model directly.
While teaching a Caltech course on planetary physics, Batygin (the theorist behind the proposed existence of Planet Nine) turned to an approximation scheme called perturbation theory to formulate a simple mathematical representation of disk evolution. This approximation, often used by astronomers, is based upon equations developed by the 18th-century mathematicians Joseph-Louis Lagrange and Pierre-Simon Laplace. Within the framework of these equations, the individual particles and pebbles on each particular orbital trajectory are mathematically smeared together. In this way, a disk can be modeled as a series of concentric wires that slowly exchange orbital angular momentum among one another.
As an analogy, in our own solar system one can imagine breaking each planet into pieces and spreading those pieces around the orbit the planet takes around the sun, such that the sun is encircled by a collection of massive rings that interact gravitationally. The vibrations of these rings mirror the actual planetary orbital evolution that unfolds over millions of years, making the approximation quite accurate.
Using this approximation to model disk evolution, however, had unexpected results.
"When we do this with all the material in a disk, we can get more and more meticulous, representing the disk as an ever-larger number of ever-thinner wires," Batygin says. "Eventually, you can approximate the number of wires in the disk to be infinite, which allows you to mathematically blur them together into a continuum. When I did this, astonishingly, the Schrödinger Equation emerged in my calculations."
The Schrödinger Equation is the foundation of quantum mechanics: It describes the non-intuitive behavior of systems at atomic and subatomic scales. One of these non-intuitive behaviors is that subatomic particles actually behave more like waves than like discrete particles -- a phenomenon called wave-particle duality. Batygin's work suggests that large-scale warps in astrophysical disks behave similarly to particles, and the propagation of warps within the disk material can be described by the same mathematics used to describe the behavior of a single quantum particle if it were bouncing back and forth between the inner and outer edges of the disk.
The Schrödinger Equation is well studied, and finding that such a quintessential equation is able to describe the long-term evolution of astrophysical disks should be useful for scientists who model such large-scale phenomena. Additionally, adds Batygin, it is intriguing that two seemingly unrelated branches of physics -- those that represent the largest and the smallest of scales in nature -- can be governed by similar mathematics.
"This discovery is surprising because the Schrödinger Equation is an unlikely formula to arise when looking at distances on the order of light-years," says Batygin. "The equations that are relevant to subatomic physics are generally not relevant to massive, astronomical phenomena. Thus, I was fascinated to find a situation in which an equation that is typically used only for very small systems also works in describing very large systems."
Read more at Science Daily
Mar 5, 2018
Mammals share mechanisms controlling the heart with a 400 million-year-old fish
 |
| This is a South American lungfish, Lepidosiren paradoxa. |
Mammals show an increase in heart rate when breathing in and a decrease during expiration -- a cardiorespiratory process known as respiratory sinus arrhythmia (RSA). This process and its underlying control mechanisms have been considered by many scientists to be solely mammalian but the present study questions this assumption.
Scientists in Britain and Brazil studied the South American lungfish, Lepidosiren paradoxa, and discovered that systems enabling this primitive vertebrate to control blood flow during bouts of air-breathing have close similarities to those identified in mammals.
Lungfish are members of an ancient group of lobe-finned fishes (Class Dipnoi), having a continuous fossil record originating in the Devonian period around 400 million years ago. This was a time when the first vertebrates crawled on to land to give rise to amphibians and over succeeding millennia reptiles, birds and mammals.
With their proto-lungs and proto-limbs, lungfish represent the earliest stage in the evolution of air-breathing vertebrates. They inhabit tropical, freshwater pools and slow-flowing rivers, which often contain very low levels of dissolved oxygen and can disappear during the dry season.
The lungfish shares a periodic breathing pattern with the terrestrial vertebrates, rising to the water's surface at regular intervals to ventilate its lung-like air-breathing organ and depending exclusively on these lungs for oxygen uptake during drought.
Led by experts at the University of Birmingham and the Federal University of São Carlos (UFSCar), in São Paulo, the international team published its findings in Science Advances.
Professor Ted Taylor, from the University of Birmingham, said: "When lungfish gulp air at the water's surface, their heart rate instantly increases -- signalling a diversion of blood to the creature's lungs.
"This is possible because the animal has an undivided heart, enabling the proportion of blood diverted to the lungs to be varied; unlike mammals, as we have a completely divided heart with equal volumes of blood pumped separately to lungs and body with each heartbeat.
"Our study established a clear function in lungfish for these increases in heart rate in maximising oxygen uptake during each air breath that has not been definitively demonstrated for RSA in mammals. This suggests that it may be a relic of their link to ancient amphibious ancestors."
Professor Taylor added that "The lungfish has a relatively complex control system which generates these respiration-related changes in heart rate, with properties that anticipate those described for mammals.
"We found that these include multiple locations for nerve cells in the brainstem that innervate the heart with insulated fibres that conduct rapid impulses, causing an instantaneous cardiac response to each air-breath."
This illustration in a fish with a proven ancient lineage of a highly evolved system controlling variations in heart rate suggests that its evolution was necessarily linked to the advent of air breathing over primitive vertebrate lungs rather than the much later appearance of mammals.
Read more at Science Daily
A leopard may not change its spots but venomous creatures change their venom recipe often
 |
| This is the Nematostella. |
For a long time scientists believed that an animal's venom was consistent over time: once a venomous creature, always a venomous creature. However, through a close study of sea anemones, Dr. Yehu Moran of Hebrew University's Alexander Silberman Institute of Life Science, found that animals change their venom several times over the course of a lifetime, adapting the potency and recipe of their venom to suit changing predators and aquatic environments.
Today, in a study published in eLife Science Magazine, Moran and his team describe their spectacular findings. They studied the Nematostella, a relative of the jellyfish, from cradle to grave. Nematostella are sea anemones that belong to the Cnidaria family of jellyfish and corals. They begin their life as tiny larvae and grow into animals measuring several inches long. While in the larvae stage, the Nematostella fall prey to larger fish but once mature, they become predators themselves, catching shrimp and small fish with their venomous tentacles.
Dr. Moran found that while in the larvae stage, sea anemones produce uniquely potent venom that causes predators to immediately spit them out if swallowed. Later on, when the sea anemones grow big and become predators themselves, their venom adapts to their new lifestyle by producing a different kind of toxin, one best suited to catch small fish and shrimp. Over the course of a lifetime, as the Nematostella's diet changes and they move from one aquatic region to another, they adapt their venom to suit their new needs and environment.
"Until now, venom research focused mainly on toxins produced by adult animals. However, by studying sea anemones from birth to death, we discovered that animals have a much wider toxin arsenal than previously thought. Their venom evolves to best meet threats from predators and to cope with changing aquatic environments," explained Dr. Yehu Moran.
To track these changes, Moran's team labeled the sea anemone's venom-producing cells and monitored them over time. The researchers also recorded significant interactions that Nematostella had over their lifetime -- first as prey and later as predators.
These findings are significant for several reasons. First, venom is often used in medicines and pharmacological compounds. This study suggests that for animals with a complex life cycle there are many venom components that have remained unknown to researchers since, until now, researchers have only studied venom from adult sea anemones, missing out on the unique compounds that exist in larvae venom. These "new" compounds could lead to new medicines and drugs. Second, sea anemones, jellyfish and coral play a significant role in marine environments. A better understanding of their venomous output and effect on marine life ecology is crucial.
Read more at Science Daily
These tropical hummingbirds make cricket-like sounds other birds can't hear
 |
| This is a photograph of a black Jacobin hummingbird. |
"These vocalizations are fast and high pitched, and in fact they do not sound at all like your typical bird sound," says Claudio Mello from Oregon Health and Science University. "They sound more like an insect, such as a cricket, or like a tree frog."
Mello and his colleagues stumbled onto the discovery quite by accident while studying many species of hummingbirds in the forested mountains of Eastern Brazil.
"We heard prominent high-pitch sounds that sounded perhaps like a cricket or a tree frog," Mello says. "But then we noticed that the sounds were actually coming from these black hummingbirds."
The researchers thought the vocalizations had to be at an unusually high pitch, but they didn't have the equipment needed to measure it. So, on a later trip, they took detectors with them that are normally used to pick up the high-frequency sounds of bats. They confirmed that the detectors picked up on these unusual hummingbird sounds.
More recently, they made recordings of the sounds using special recording equipment designed to study bat calls. The recordings showed that the sounds were quite remarkable, having a high degree of complexity and being produced at high frequency, including components in the ultrasonic range that humans can't hear.
The discovery suggests that either black jacobins hear sounds other birds can't or that the birds produce sounds they can't even hear. The researchers speculate that the birds might rely on the unusual calls as a private channel of communication. That could be especially useful given that black jacobins live among a diverse group of bird species, including 40 other species of hummingbirds.
"It seems more reasonable to assume they do hear the sounds they make, but we have not yet examined whether this is true," Mello says.
Bird hearing generally has to be tested in a lab, either by recording from the brains of anesthetized birds or by watching how birds respond to sounds. Those studies aren't amenable to studying hummingbirds in the wild.
The findings suggest that the hummingbirds must have an unusual vocal organ, the syrinx, to produce these sounds. "They would need to vibrate very quickly and likely have a special composition, which may be different from other birds," he says.
Read more at Science Daily
Hubble observes exoplanet atmosphere in more detail than ever before
 |
| A team of British and American astronomers used data from several telescopes on the ground and in space -- among them the NASA/ESA Hubble Space Telescope -- to study the atmosphere of the hot, bloated, Saturn-mass exoplanet WASP-39b, about 700 light-years from Earth. The analysis of the spectrum showed a large amount of water in the exoplanet's atmosphere -- three times more than in Saturn's atmosphere. |
Investigating exoplanet atmospheres can provide new insight into how and where planets form around a star. "We need to look outward to help us understand our own Solar System," explains lead investigator Hannah Wakeford from the University of Exeter in the UK and the Space Telescope Science Institute in the USA.
Therefore the British-American team combined the capabilities of the NASA/ESA Hubble Space Telescope with those of other ground- and space-based telescopes for a detailed study of the exoplanet WASP-39b. They have produced the most complete spectrum of an exoplanet's atmosphere possible with present-day technology.
WASP-39b is orbiting a Sun-like star, about 700 light-years from Earth. The exoplanet is classified as a "Hot-Saturn," reflecting both its mass being similar to the planet Saturn in our own Solar System and its proximity to its parent star. This study found that the two planets, despite having a similar mass, are profoundly different in many ways. Not only is WASP-39b not known to have a ring system, it also has a puffy atmosphere that is free of high-altitude clouds. This characteristic allowed Hubble to peer deep into its atmosphere.
By dissecting starlight filtering through the planet's atmosphere the team found clear evidence for atmospheric water vapour. In fact, WASP-39b has three times as much water as Saturn does. Although the researchers had predicted they would see water vapour, they were surprised by the amount that they found. This surprise, combined with the water abundance allowed to infer the presence of large amount of heavier elements in the atmosphere. This in turn suggests that the planet was bombarded by a lot of icy material which gathered in its atmosphere. This kind of bombardment would only be possible if WASP-39b formed much further away from its host star than it is right now.
"WASP-39b shows exoplanets are full of surprises and can have very different compositions than those of our Solar System," says co-author David Sing from the University of Exeter, UK.
The analysis of the atmospheric composition and the current position of the planet indicate that WASP-39b most likely underwent an interesting inward migration, making an epic journey across its planetary system. "Exoplanets are showing us that planet formation is more complicated and more confusing than we thought it was. And that's fantastic!," adds Wakeford.
Having made its incredible inward journey WASP-39b is now eight times closer to its parent star, WASP-39, than Mercury is to the Sun and it takes only four days to complete an orbit. The planet is also tidally locked, meaning it always shows the same side to its star. Wakeford and her team measured the temperature of WASP-39b to be a scorching 750 degrees Celsius. Although only one side of the planet faces its parent star, powerful winds transport heat from the bright side around the planet, keeping the dark side almost as hot.
"Hopefully this diversity we see in exoplanets will help us figure out all the different ways a planet can form and evolve," explains David Sing.
Read more at Science Daily
Subscribe to:
Posts (Atom)