Astronomy
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New Study Finds Martian Volcano’s Last Eruption
The rough estimate for the dinosaurs’ extinction was about 50 million years ago, but NASA reveals that may not be the only thing that disappeared around that time.
New research from NASA shows that Arsia Mons, a large volcano just south of Mars’ equator, has been inactive for about 50 million years.
The last time Arsia Mons erupted was in the bowl-shaped depression at the top of the volcano, called the caldera. The caldera is 68 miles (110 kilometers) across and has enough space to hold all of Lake Huron with some spare room.
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“We estimate that the peak activity for the volcanic field at the summit of Arsia Mons probably occurred approximately 150 million years ago -- the late Jurassic period on Earth -- and then died out around the same time as Earth’s dinosaurs,” Jacob Richardson, a postdoctoral researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a press release. “It’s possible, though, that the last volcanic vent or two might have been active in the past 50 million years, which is very recent in geological terms.”
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“A major goal of the Mars volcanology community is to understand the anatomy and lifecycle of the planet’s volcanoes. Mars’ volcanoes show evidence for activity over a larger time span than those on Earth, but their histories of magma production might be quite different,” Jacob Bleacher, a planetary geologist at Goddard and a co-author on the study, said. “This study gives us another clue about how activity at Arsia Mons tailed off and the huge volcano became quiet.”
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Process Behind Martian Streaks Continues To Puzzle
It’s a well-documented fact that roughly 4 billion years ago, Mars had liquid water flowing on its surface. However, there have also been recent findings that suggest that Mars might periodically have liquid water on its surface today. One of the strongest bits of evidence comes in the form of Recurring Slope Lineae, which are ventured to be seasonal flows of salty water which occur during Mars’ warmest months.
However, a new study produced by an international team of scientists has casts doubt on this theory and offered another possible explanation. Using numerical simulations, they show how a “dry” process – where rarefied gas is pumped up through the soil (due to temperature variations) – could lead to the formation of the dark streaks that have been observed on Martian slopes.
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This theory has met with its share of excitement, considering that the presence of water on the Martian surface would mean that the chances of finding present-day life there would be significantly greater. Unfortunately, recent studies have cast doubt on this by showing how there is insufficient water on Mars to account for the lineae that have been observed on various slopes.
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However, Mars does have sufficient air pressure to allow for another process known as thermal creep. Also known as thermal transpiration, this process involves gas molecules drifting from the cold end of a narrow channel to the warm end. This occurs as a result of the walls of the channel experiencing temperature changes, which triggers a gas flow.
According to their study, sections of the Martian surface could be heated by solar radiation while others remained cooler because they were covered by a source of shade. When this happens, rarefied gas beneath the surface (i.e. gas with lower pressure than the atmosphere) could be pumped up through the Martian soil. Once it reached the surface, this gas would disturb patches of small particles, triggering tiny avalanches along Martian slopes.
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Biology
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Need For Speed May Contribute To Dolphin And Whale Strandings
Dolphins swimming at top speed use more than twice the amount of energy per fin beat than dolphins swimming at a more relaxed pace, according to a study by scientists at UC Santa Cruz. The researchers also found that startled beaked whales fleeing human noises use 30.5 percent more energy during the flight, suggesting that the high cost of escape could contribute to recent dolphin and whale strandings.
Diving marine mammals must balance speed and the duration of breath-hold with the need to conserve limited oxygen reserves, leaving them vulnerable when they try to escape from perceived threats. "Amazingly, there has been only a handful of studies that have actually measured the energetic cost of a dive for dolphins or whales," said Terrie Williams, professor of ecology and evolutionary biology at UC Santa Cruz.
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Working with a team of expert trainers, Williams and her colleagues spent over 6 months training six bottlenose dolphins that had previously worked with the U.S. Navy to participate in swimming tests that would allow the scientists to measure the metabolic costs of the different swimming styles. In the first test, the dolphins learned to swim at their most comfortable speed while pushing against a force plate in the wall of the pool as the researchers filmed the number of fin beats. The second test required the animals to dive down 10 meters wearing a fin-beat tracker and swim through a series of hoops before returning to the surface.
Williams was able to take advantage of the animals' marine lifestyle to directly measure the metabolic cost of each dive by training the animals to surface in an air dome where she could record how much oxygen the animals inhaled as they recharged the oxygen stores that they had consumed while swimming. When Williams included killer whales in the metabolic measurements, she had to build an outsized 1.7-square-meter respiration dome to accommodate the larger animals.
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But what are the conservation implications of the increased cost of each fin beat when whales and dolphins need to avoid danger? Loud man-made noise pollution is thought to be responsible for some mass strandings, so Williams contacted Brandon Southall, a research associate at UCSC's Institute of Marine Sciences, who had recorded how a Cuvier's beaked whale reacted to 20 minutes of loud sonar. With the recording showing that the whale's fin-beat pattern increased significantly, from about 13.6 to 16.9 strokes per minute, she calculated that the startled animals would use 30.5 percent more energy as their metabolic rate rocketed to power the fleeing animals' fin beats. And the whale did not recover swiftly, continuing to use the most costly fin beats for almost two hours after the noise stopped.
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Life On Earth May Have Begun As Dividing Droplets
In a primordial soup on ancient Earth, droplets of chemicals may have paved the way for the first cells. Shape-shifting droplets split, grow and split again in new computer simulations. The result indicates that simple chemical blobs can exhibit replication, one of the most basic properties of life, physicist Rabea Seyboldt of the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany, reported March 16 at a meeting of the American Physical Society.
Within a liquid, small droplets of particular chemicals can separate out, like beads of oil in water. Such globules typically remain spherical, growing as they merge with other drops. But in simulations, Seyboldt and colleagues found that droplets might behave in a counterintuitive way under certain conditions, elongating and eventually dividing into two.
If additional droplet material is continuously produced in reactions in the primordial soup, chemicals will accumulate on either end of a droplet, causing it to elongate, the simulations show. Meanwhile, waste products from the droplet are eliminated from the middle, causing the droplet to pinch in and eventually split. The resulting pair of droplets would then grow and split again to create a new generation. In addition to the above reactions, the process requires an energy source, such as heat or chemicals from a hydrothermal vent, to get reactions going.
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How such droplets would have evolved into vastly more complicated cells is unknown. “This is really a minimal scenario that’s supposed to give the very first indications of something that goes towards life, but if you look at living cells today, they’re infinitely more complex,” Seyboldt said.
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Chemistry
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Super-Hard Transparent Ceramic Looks Good
One of the hardest materials known – silicon nitride – has been turned transparent for the first time. The see through ceramic could be used for ultra-tough windows able to withstand extreme conditions.
Windows that let users peer into engines and industrial reactors, or protect optical sensors from high pressures or heat are usually made of diamond – an expensive material that becomes unstable at temperatures above 750°C.
Norimasa Nishiyama, from the German Electron Synchrotron DESY, and an international group of researchers from Germany and Japan have now created a disc of transparent silicon nitride 2mm in diameter. The ultra-hard but cheap material can withstand temperatures up to 1400°C.
Silicon nitride is usually opaque, but at 1800°C and 15.6 gigapascals its crystal structure changes from a hexagonal to a cubic arrangement. The cubic structure is transparent as it has fewer crystal defects on which impurities like oxygen, which can make the material opaque, accumulate.
The size of any transparent silicon nitride window might be limited, however. The extreme pressure it takes to transform the ceramic into its transparent form requires specialised instruments, the largest of which could only create windows up to 1cm in diameter . Diamond windows 2.5cm in diameter are already on the market.
Ecology
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UTA Biologist Quantifying Coral Species' Disease Susceptibility By Examining Immune Traits
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During the past three decades, environmental changes – including global warming – have likely led to the sharp increase in coral disease in reefs around the world. Unhealthy coral reefs cannot support the fish and other forms of life that make reefs such vibrant and diverse ecosystems. Coral reefs in the Caribbean Sea are disease hotspots and many reefs have experienced population collapses due to outbreaks of disease, [Laura Mydlarz, associate professor of biology, is principal investigator of the project] explained. Coral species vary in their susceptibility to disease, but the reasons behind this variation are unknown.
“Coral diseases don’t affect all coral species in a reef the same,” Mydlarz said. “Some coral are more susceptible to certain diseases. A reef is made up of many different species of coral. If a disease kills off one species of coral in a reef, that’s going to greatly affect the reef community as a whole. We want to learn why some coral species are more tolerant of certain diseases.”
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The project will use immune-challenge experiments that will quantify novel components of the innate immune system of corals, coupled with the application of a trait-based model, to fulfill three goals, Mydlarz said. The first is to determine variability of coral immune traits in seven common coral species found on Caribbean reefs; the second is to determine the variability in resistance to white plague disease transmission in the same coral species; and the third is to develop a predictive model of coral community assemblage that incorporates immune traits.
The coral species which will be examined differ in disease susceptibility, growth rates and reproductive strategies. Susceptibility to white plague disease will be measured by exposing the corals to active white plague and calculating disease transmission rates in a laboratory setting. The immune responses of each species will be measured by exposing samples to bacterial immune stimulators. Samples will be collected and injected with lipopolysaccharides, which are molecules that elicit strong immune responses in some organisms.
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NASA Study Confirms Biofuels Reduce Jet Engine Pollution
Using biofuels to help power jet engines reduces particle emissions in their exhaust by as much as 50 to 70 percent, in a new study conclusion that bodes well for airline economics and Earth’s environment.
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During flight tests in 2013 and 2014 near NASA’s Armstrong Flight Research Center in Edwards, California, data was collected on the effects of alternative fuels on engine performance, emissions and aircraft-generated contrails at altitudes flown by commercial airliners. The test series were part of the Alternative Fuel Effects on Contrails and Cruise Emissions Study, or ACCESS.
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"Soot emissions also are a major driver of contrail properties and their formation," said Bruce Anderson, ACCESS project scientist at NASA’s Langley Research Center in Hampton, Virginia. "As a result, the observed particle reductions we’ve measured during ACCESS should directly translate into reduced ice crystal concentrations in contrails, which in turn should help minimize their impact on Earth’s environment."
That’s important because contrails, and the cirrus clouds that evolve from them, have a larger impact on Earth’s atmosphere than all the aviation-related carbon dioxide emissions since the first powered flight by the Wright brothers.
The tests involved flying NASA's workhorse DC-8 as high as 40,000 feet while its four engines burned a 50-50 blend of aviation fuel and a renewable alternative fuel of hydro processed esters and fatty acids produced from camelina plant oil. A trio of research aircraft took turns flying behind the DC-8 at distances ranging from 300 feet to more than 20 miles to take measurements on emissions and study contrail formation as the different fuels were burned.
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Physics
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Artificial Photosynthesis Steps Into The Light
Rice University scientists have created an efficient, simple-to-manufacture oxygen-evolution catalyst that pairs well with semiconductors for solar water splitting, the conversion of solar energy to chemical energy in the form of hydrogen and oxygen.
The lab of Kenton Whitmire, a Rice professor of chemistry, teamed up with researchers at the University of Houston and discovered that growing a layer of an active catalyst directly on the surface of a light-absorbing nanorod array produced an artificial photosynthesis material that could split water at the full theoretical potential of the light-absorbing semiconductor with sunlight.
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The researchers coated the three-dimensional arrays of titanium dioxide nanorods with the metallic-looking film. The composite material showed potential as a high-surface-area semiconductor for photoelectrochemical cells.
Growing the transition metal coating directly onto the nanorods allows for maximum contact between the two, Whitmire said. "That metallic, conductive interface between the semiconductor and the active catalytic surface is key to the way this device works," he said.
The film also has ferromagnetic properties, in which the atoms' magnetic moments align in the same direction. The film has a low Curie temperature, the temperature at which some materials' magnetic properties need to be induced. That could be useful for magnetic refrigeration, the researchers said.