Astronomy
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Huge Mars Lakes Formed Much More Recently Than Thought
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Some Red Planet streams and lakes — including one bigger than several of North America's Great Lakes — formed just 2 billion to 3 billion years ago, a new study suggests. That's a surprise, because researchers think that, by that epoch, Mars had already lost most of its atmosphere, and therefore had likely become too cold to host liquid water on its surface.
"This paper presents evidence for episodes of water modifying the surface on early Mars for possibly several hundred million years later than previously thought, with some implication that the water was emplaced by snow, not rain," Mars Reconnaissance Orbiter (MRO) project scientist Rich Zurek, of NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement.
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The study team arrived at their age estimate by looking at the valleys in the lake-and-stream system. Specifically, researchers checked if those valleys had carved into the aprons of debris surrounding 22 impact craters in the area whose rough ages were already known. (If a valley did cut into such an apron, water was flowing after the crater-creating impact occurred.)
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"The rate at which water flowed through these valleys is consistent with runoff from melting snow," she said, "These weren't rushing rivers. They have simple drainage patterns and did not form deep or complex systems like the ancient valley networks from early Mars."
But it's unclear how that snow heated up enough to melt, she said. One possibility is a shift in Mars' axial tilt, which resulted in greater illumination of the ice caps at the planet's poles, researchers said. (Valleys like those seen in Arabia Terra also occur in Mars' southern hemisphere, suggesting that lakes and streams existed over broad stretches of the planet, study team members said.)
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Curiosity Captures A Snapshot Of Mars' Past
Curiosity, NASA’s rover currently exploring Mars, captured images on Thursday, September 8 of layered rock formations in the “Murray Buttes” region of Mount Sharp. The images, which were taken by Curiosity’s Mastcam, show the beautiful formation in spectacular detail. Scientists say the formations were caused by sand dunes becoming buried, chemically changed, exhumed, and then eroded.
Curiosity was launched from Cape Canaveral Air Force Station in Florida in November 2011. It then landed on Mount Sharp in August of 2012 and reached the base of the mountain in 2014. The rover studies the climate and layout of Mars in preparation for future human exploration, and the information collected will serve as a foundation for the Mars 2020 rover.
Curiosity found evidence for ancient lakes, providing evidence that if Mars ever hosted life it would have been sustainable for microbes. It is also looking into how earlier habitable conditions transformed into Mars’ current dry, inhospitable state.
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Curiosity has been driving in the Murray Buttes for over one month and is currently driving south up the base of the final butte on its last stop. On September 9, it started a drilling campaign and will continue higher up Mount Sharp once the campaign is completed.
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Biology
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Fish Lose Personalities When They Go To School
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They found that just like in humans, braver individuals led the groups, and that the fish stuck together when making a risky decision.
But they concluded that the conformity needed to make a group decision is stronger than braver fish leading, meaning overall, that the individual personalities of fish were lost when in a group.
Dr Ioannou said: "This is the first time that the suppression of personality in groups has been linked to its underlying cause, which is conformity in group decision making."
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Dr Ioannou added: "The behaviour of the fish seems to be 'plastic' to the social situation -- they show consistent individual differences in behaviour when tested alone -- reflecting personality, but they are also happy to suppress this to be able to stick together with their shoal mates if there are others around."
The research, published in Science Advances, suggests that in social animals, when things get dangerous and animals form cohesive groups, risk-taking tendency when alone may not be a good indicator of the risk an individual actually faces.
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Tasty Letters? Sensory Connections Spill Over In Synesthesia
Synesthesia is a stable trait, and estimated to be present in 1 to 4 percent of people. It can be inherited, although the precise genes have not been identified. One of the most common forms of synesthesia is when people involuntarily see particular colors in connection with letters, numbers or sounds.
Many artists and composers have described their experiences with synesthesia. Children with synesthesia say sometimes that it is distracting when they are trying to read. Thus, understanding the origins of synesthesia may help people with dyslexia or other learning differences, or people who have lost their sight or hearing and are trying to engage in sensory substitution for rehabilitation.
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People with synesthesia were not significantly more sensitive to purely sensory associations between the pitch of a sound and the size or position of a shape, compared to non-synesthetes. In this situation, sensitivity on the IAT means that study participants would have a greater difference in response times to congruent pairings of shape and sound (a high position in space, and a high pitch, for example) in comparison to incongruent pairings.
Participants in the study were recruited through advertisements on the Emory campus and screened with an online test called the Synesthesia Battery. This test confirms whether people who report they have synesthesia have consistent associations.
A connection between letters or other symbols and colors, also known as "grapheme-color" synesthesia, was the most common type in the Emory study. It may represent the presence of idiosyncratic wrinkles in how people learned their letters or other symbols during childhood. Indeed, Sathian notes that one study suggests that a popular brand of refrigerator magnets had an influence on what letter-color associations people with this form of synesthesia developed.
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Chemistry
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Turning Ubiquitous Lignin Into High-Value Chemicals
Abundant, chock full of energy and bound so tightly that the only way to release its energy is through combustion -- lignin has frustrated scientists for years. With the help of an unusual soil bacteria, researchers at Sandia National Laboratories believe they now know how to crack open lignin, a breakthrough that could transform the economics of biofuel production.
Lignin is a component of lignocellulosic biomass, the dry plant matter found virtually everywhere. As a biomass source that does not compete with food or feed, lignin is critical to biofuel production. Lignin makes up the fortress-like cell walls of plants to enable water transport against gravity while protecting them from microbial attack and environmental stress. These beneficial traits make lignin hard to break down and even harder to convert into something valuable.
By following the metabolic pathway of an unusual soil bacteria that lives off lignin, Sandia research team members led by principal investigator Seema Singh believe they can develop technologies to break down lignin and extract valuable platform chemicals. High-value chemicals like muconic acid and adipic acid can be derived from the platform chemicals.
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But if you add the production of high-value chemicals to the biorefinery business model the economics fall into place -- just as with the refinery industry, where crude oil is used to produce high-value chemicals and high-volume polymers used in our daily lives.
"Gasoline is a low-value, high-volume product. This is balanced by the high-value chemicals derived from about 6-10 percent of every barrel of oil," said Singh.
Lignin is seen as a byproduct of limited use, typically burned for its energy content. Using biomass for chemical production could yield at least 10 times more value, compared to burning it to make electricity.
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Engineers Stop Soap Bubbles from Swirling
The spinning rainbow surface of a soap bubble is more than mesmerizing -- it's a lesson in fluid mechanics. Better understanding of these hypnotic flows could bring improvements in many areas, from longer lasting beer foam to life-saving lung treatments.
The whirling on the surface of bubbles is caused in part by the Marangoni effect. This phenomenon occurs when molecules called surfactants move from areas of low surface tension to areas of higher surface tension along the boundary between two different substances. Your body is full of natural surfactants, such as the tear film of our eyes and the fluid contained in the tiny air sacs within our lungs. In a soap bubble, the Marangoni effect helps stabilize the bubble by creating a more even distribution of surface tension.
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Stopping the swirl
The researchers achieved this control by creating an air bubble about 1 millimeter across under the surface of a soapy solution, raising the bubble quickly to the surface, pausing and then raising it again. With each bump upward, they launched a new layer of Marangoni flows at the outer rim of the bubble, which trapped the previous layer. They were able to create as many as seven different Marangoni flows in one bubble.
These halted flows are mysterious because they are akin to freezing a crashing wave.
"The colors on the bubbles indicate the thickness of the film, so you have these valleys and hills that are in a geometrical frustrated state on a surface that itself is ephemeral," said lead author Saad Bhamla, who conducted the work in Fuller's lab as a graduate student and is now a postdoctoral scholar in bioengineering. "An interesting question is why you are able to do that in the first place."
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Ecology
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All Polar Bears Across The Arctic Face Shorter Sea Ice Season
A new University of Washington study, with funding and satellite data from NASA and other agencies, finds a trend toward earlier sea ice melt in the spring and later ice growth in the fall across all 19 polar bear populations, which can negatively impact the feeding and breeding capabilities of the bears. The paper, to appear Sept. 14 in The Cryosphere, is the first to quantify the sea ice changes in each polar bear subpopulation across the entire Arctic region using metrics that are specifically relevant to polar bear biology.
"This study shows declining sea ice for all subpopulations of polar bears," said co-author Harry Stern, a researcher with the UW's Polar Science Center. "We have used the same metric across all of the polar bear subpopulations in the Arctic so we can compare and contrast, for example, the Hudson Bay region with the Baffin Bay region using the same metric."
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Greenhouse Gas Monitoring Aircraft Keep Tabs On The Amazon's Rising Methane Levels
Research led by the National Centre of Earth Observation at the University of Leicester is going to new heights in the atmosphere to get a better handle on methane emitted from wetlands in the Amazon.
Using small aircraft flying in an upward spiral and collecting samples of the air, the team has measured the levels of methane in the atmosphere over the Amazon basin in unprecedented detail.
In the process they've shown the value of satellite measurements of methane for the region, paving the way for research that will keep better tabs on the greenhouse gas.
Methane is a potent greenhouse gas, second only to carbon dioxide in its contribution to global warming.
Atmospheric concentrations of the gas have increased by 150% since the beginning of the industrial era.
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Physics
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Simple Math, Antimatter, And The Birth Of The Universe
If x2 = 4, then what is x? Did you just think "2"? Is that correct? Well, yes and no. The fact that there is a parallel but equally valid answer that x is negative 2 has been a difficult and intriguing conundrum to everyone who comes across it. But this concept can be applied to far more than simple algebra. It can be applied to one of the most confusing areas of science—antimatter, an odd sort of "opposite" to the stuff that makes up our ordinary world.
Paul Dirac was the first to conceive the idea of antimatter, using exactly the same reasoning. He had written an equation that explained an electron's spin. However, he realized that it had two possible answers: one for positive energy, one for negative energy. This amazing leap of imagination and theory is the foundation for today's study of antimatter, where particles have the same mass as ordinary matter particles, but opposing properties such as opposite charge.
The physicist Freeman Dyson said of Dirac: "His discoveries were like exquisitely carved statues falling out of the sky, one after another. He seemed to be able to conjure laws of nature from pure thought."
The above quotation demonstrates the compelling beauty of particle physics—the endless frontier between what is known and what is unknown constantly being pushed back by scientists at the center of it all, studying physics by seemingly defying physics.
And that is exactly what the physicists and engineers of STAR (Solenoidal Tracker At RHIC) are doing. RHIC (the Relativistic Heavy Ion Collider, a particle collider at Brookhaven National Laboratory in the U.S.) accelerates gold ions to almost the speed of light before allowing them to collide with one another. The subatomic interactions in these collisions produce a fountain of rare particles—including particles of antimatter—revealing hints of what matter looked like at the dawn of time. That's right: In a particle detector in a building in a laboratory on Long Island, New York, USA, whose matter was formed 13.82 billion years ago in the Big Bang, we see 13.82 billion years into the past, just a few microseconds after the Universe began.
[Editors Note: I recommend this article and regret that fair use limits what I can republish here.]
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