Astronomy
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Opportunity Leaving ‘Tribulation’ Behind
You’d have to be an intrepid explorer to investigate something named ‘Cape Tribulation’. Opportunity, NASA’s long-lived rover on Mars’ surface, has been just that. But Opportunity is now leaving Cape Tribulation behind, after being in that area since late 2014, or for about 30 months.
Cape Tribulation is the name given to a segment of crater rim at Endeavour Crater, where Opportunity has been for over 5 1/2 years. During that time, Opportunity reached some important milestones. While there, it surpassed 26 miles in distance travelled, the length of a marathon race. It also reached its highest elevation yet, and in ‘Marathon Valley’, it investigated clay outcrops seen from orbit. Opportunity also had some struggles there, when its flash memory stopped working, meaning all data had to be transmitted every day, or lost.
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The rover’s next destination is Perseverance Valley, where it will investigate how it was carved out billions of years ago: by water, by wind, or perhaps flowing material lubricated by water. Before leaving Cape Tribulation, Opportunity captured the panoramic image of Rochefort Ridge, a section of the Endeavour Crater rim marked by grooves on its side.”The degree of erosion at Rocheport is fascinating,” said Opportunity Deputy Principal Investigator Ray Arvidson, of Washington University in St. Louis. “Grooves run perpendicular to the crest line. They may have been carved by water or ice or wind. We want to see as many features like this on the way to Perseverance Valley as we can, for comparison with what we find there.”
Endeavour crater is about 22km in diameter, and Perseverance Valley is about 2 football fields long. The goal at Endeavour is to investigate its segmented rim, where the oldest rocks ever investigated on Mars are exposed. Since the beginning of April, Opportunity has travelled about 98 meters, to a point where Cape Tribulation meets the plain around the crater.
“From the Cape Tribulation departure point, we’ll make a beeline to the head of Perseverance Valley, then turn left and drive down the full length of the valley, if we can,” Arvidson said. “It’s what you would do if you were an astronaut arriving at a feature like this: Start at the top, looking at the source material, then proceed down the valley, looking at deposits along the way and at the bottom.”
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Finding The Milky Way’s Hydrogen Halo
Our galaxy is missing matter — baryonic matter, to be specific. Baryonic matter consists of baryons: particles such as protons and neutrons. It’s the everyday matter around you and makes up every element on the periodic table. Astronomers have been puzzled by the fact that the Milky Way and other galaxies are missing baryonic matter when the mass of their easily measured components, the disk and the bulge, are summed. Recent observations have indicated that galaxies may host a diffuse halo of gas out to great distances (hundreds of thousands of light-years), which is particularly hard to detect but could account for the missing matter. And now, as all-sky surveys amass ever more data, astronomers are finally starting to uncover more information about these halos.
In a paper published in Nature Astronomy April 18, authors Huanian Zhang and Dennis Zaritsky describe their research exploring the Milky Way’s galactic halo of cool, diffuse hydrogen gas by observing the light of other galaxies as it passes through the halo on its way to Earth. When this light is broken up by a prism, it forms a spectrum that contains key details about the material the light has traveled through, which includes not only the matter in the distant galaxy from which it came, but also any intervening matter the light may have encountered on its journey — such as our galactic halo.
This type of line-of-sight observation has been used before to study the galaxy’s halo, but has typically been limited to a few bright objects such as distant quasars (the extremely bright disks of gas and dust around supermassive black holes) or distant stars in our own galaxy’s halo. But with the ongoing releases of data from surveys such as the Sloan Digital Sky Survey (SDSS), millions of distant galaxy spectra are available for use. The vast amount of data allows astronomers to more easily separate out effects from the “nearby” gas in our galaxy’s halo as the light passes through it.
Zhang and Zaritsky compiled a sample of 732,225 galaxy spectra from the 12th data release of the SDSS. By “stacking” or combining these spectra together, they were able to essentially boost the otherwise weak signal of the galaxy’s hydrogen halo, making it much easier to observe and characterize. The result was a clear detection of hydrogen-alpha, a specific “thumbprint” left on the light as it passed through the neutral hydrogen of the galactic halo.
Based on the stacked signal, the pair determined that the gas could be moving at speeds up to 435 miles per second (700 kilometers per second). It has no net infall or loss, meaning it stays in the halo for the most part, rather than streaming away as outflows or falling inward to provide fuel for new stars. They also estimate the gas’ temperature could be about 21,000 degrees Fahrenheit (11,700 degrees Celsius).
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Biology
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Fungi Have Enormous Potential For New Antibiotics
Antibiotics have saved millions of lives since they were discovered in the 1940s. But recently we've had to learn a new term: antibiotic resistance. More and more bacteria are developing their own protection against antibiotics, thereby becoming resistant to treatment. This will lead to simple infections becoming lethal once again. Our need for new antibiotics is urgent.
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In the study, recently published in the journal, Nature Microbiology, the research group scanned the genomes of 24 different kinds of fungi to find genes responsible for the production of various bioactive compounds, like antibiotics. More than 1000 pathways were discovered, showing immense potential for fungi to produce a large variety of natural and bioactive chemicals that could be used as pharmaceuticals.
In about 90 cases, the researchers were able to predict the chemical products of the pathways. As evidence of this, they followed the production of the antibiotic, yanuthone, and identified new fungi able to produce the compound, but also that some species could produce a new version of the drug.
All in all, the study shows vast potential for fungi, not only in producing new antibiotics but also in enabling more efficient production of existing ones -- and maybe also more effective versions of the existing ones.
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"Governments need to act. The pharmaceutical industry doesn't want to spend money on new antibiotics, it's not lucrative. This is why our governments have to step in and, for instance, support clinical studies. Their support would make it easier to reach the market, especially for smaller companies. This could fuel production," says Jens Christian Nielsen.
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Partners In Parasitism, Lice And Their Bacterial Sidekicks Share Long History
Lice depend on bacteria to supply essential vitamins missing from blood, their only food source. These bacterial partners live in specialized cells inside their insect hosts and pass from a female louse to her offspring. Lice could not survive without their symbiotic bacteria, and the bacteria, in turn, cannot live outside their insect hosts.
As primates evolved, so did lice, and the evolution of their bacterial partners stayed closely in step.
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Many species of blood-sucking lice only parasitize one species of host, a specificity that can offer glimpses into primate and human evolution, said Reed, curator of mammals and associate director of research and collections at the Florida Museum.
“Certain parts of our history are murky and hard to reconstruct,” he said. “The evolution of lice and their symbiotic bacteria helps shed light on human and primate evolutionary history, providing new clues to our past.”
To gain a more complete picture of how lice and their bacterial symbionts have coevolved, the researchers sequenced and assembled genomes of endosymbionts from human, chimpanzee, gorilla and red colobus monkey lice. They found that the bacteria’s genomes are tiny, hovering between 530,000 and 570,000 base pairs — E. coli’s genome, by comparison, is about 4.6 million base pairs. Small genomes are a typical feature of insect symbionts, which lose much of their genome over the course of their relationships with their hosts.
Comparing different symbiont genomes, the researchers discovered evidence of extensive genome remodeling during the last 25 million years that has resulted in genes critical to louse-symbiont symbiosis being close to one another in the bacterial genome. This arrangement likely proved advantageous, as it persists in many louse symbionts today, Boyd said.
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Chemistry
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Plot Twist In Methane Mystery Blames Chemistry, Not Emissions, For Recent Rise
A recent upsurge in planet-warming methane may not be caused by increasing emissions, as previously thought, but by methane lingering longer in the atmosphere.
That’s the conclusion of two independent studies that indirectly tracked concentrations of hydroxyl, a highly reactive chemical that rips methane molecules apart. Hydroxyl levels in the atmosphere decreased roughly 7 or 8 percent starting in the early 2000s, the studies estimate. The two teams propose that the hydroxyl decline slowed the breakdown of atmospheric methane, boosting levels of the greenhouse gas. Concentrations in the atmosphere have crept up since 2007, but during the same period, methane emissions from human activities and natural sources have remained stable or even fallen slightly, both studies suggest.
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Methane enters the atmosphere from a range of sources, from decomposing biological material in wetlands to leaks in natural gas pipelines. Ton for ton, that methane causes 28 to 36 times as much warming as carbon dioxide over a century.
Since the start of the Industrial Revolution, atmospheric methane concentrations have more than doubled. By the early 2000s, though, levels of the greenhouse gas inexplicably flatlined. In 2007, methane levels just as mysteriously began rising again. The lull and subsequent upswing puzzled scientists, with explanations ranging from the abundance of methane-producing microbes to the collapse of the Soviet Union.
Those proposals didn’t account for what happens once methane enters the atmosphere. Most methane molecules in the air last around a decade before being broken apart during chemical reactions with hydroxyl. Monitoring methane-destroying hydroxyl is tricky, though, because the molecules are so reactive that they survive for less than a second after formation before undergoing a chemical reaction.
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Ecology
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Chesapeake Bay Pollution Extends to Early 19th Century, UA Study Confirms
Humans began measurably and negatively impacting water quality in the Chesapeake Bay in the first half of the 19th century, according to a study of eastern oysters by researchers at The University of Alabama.
The work, published in Scientific Reports, show pollution’s effect appears a bit earlier than previously thought, but it generally confirms increasing deforestation and industrialization around the Bay led to water quality issues before the Civil War, which has been shown by other studies with different testing methods.
The study shows using oyster shells from archeological sites is an effective way to measure the environmental impacts of waste input on estuaries, particularly levels of nitrogen that impact the oyster’s shell chemistry as it feeds from nutrients in the water, according to the paper.
“We were one of the first to try this on archeological shells, and the first to identify an ancient period of pollution using this method,” said Dr. C. Fred T. Andrus, associate professor and chair of the UA department of geological sciences.
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A Costa Rican Volcano Sees Its Biggest Blast In Years
On April 13, Poás in Costa Rica had its largest explosive eruption in years. The explosion was mainly driven by waterheated at the summit crater lake/vent area, generating what is called a “phreatic” eruption. Although water turning to steam is the main player, these explosions can still produce plumes that reach over 1 kilometer (~3200 feet). This eruption at Poás did just that, with plumes 500-1000 meters tall. News reports also mentioned ash fall in the surrounding region, incandescent blocks suggesting magma relatively close to the surface, and boulders two meters wide being thrown from the lake vent. (They broke the floor at the Poas visitor’s center!) Passengers on a flight out of San Jose got quite a view of the eruption. You can watch video of the eruption that was captured by the webcam at Poás. The eruptions have continued, with another blast on April 18.
A video posted by OVSICORI showed the new ash around the Poás crater. Large blocks are evident on the crater floor along with dark grey ash. The view of the summit region shows off the volcano’s multiple crater vents, including the active one and another at slightly higher elevation still filled with a bright blue lake. The OVSICORI scientists have determined that although most of the material that has been erupted so far is old lavas, there is a small percentage of new magma. This means that we are not likely to see these explosions ending soon—so the area around Poás has been closed to all people.
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Physics
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The 3D Printing Of Glass Takes A Step Forward
The 3D-printing of glass objects has been achieved before – we've seen it done by extruding molten glass, and even via a modern take on an ancient Egyptian technique. A new process developed at Germany's Karlsruhe Institute of Technology, however, is claimed to produce complex glass items of a higher quality than has ever previously been possible.
Created by a team led by mechanical engineer Dr. Bastian E. Rapp, the process starts with a solution made up of a light-sensitive liquid polymer and nanoparticles of high-purity quartz glass.
Using a technique known as stereolithography, an ultraviolet laser is focused onto that solution at various points, causing it to cure and harden at those locations. In that way, the object is progressively built up from the solution, a layer at a time.
A solvent bath is subsequently used to wash away any leftover uncured solution, leaving a rough version of the desired structure behind – it's still rather porous and unstable. That structure is then heated at a high temperature, however, causing the glass nanoparticles to melt and fuse together. The end result is a smooth, solid object ranging in size from a few micrometers up to several centimeters.
It has been suggested that the technology could find use in fields such as optics, data transmission, and biotechnology.