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Updated: 3 hours 38 min ago

Collider made for quasiparticles

12 May 2016

Science News: Particle colliders have been a standard part of the physicist's toolkit for around 100 years, with different kinds of colliders being created for different kinds of particles. Now, Rupert Huber of the University of Regensburg in Germany and his colleagues have developed a collider that smashes electrons into quasiparticles known as holes. A hole is a void that is formed by the absence of an electron in a sea of electrons and that behaves like a particle. Huber's group created pairs of electrons and holes in tungsten diselenide with a short pulse of light and then applied an oscillating electric field. The field pulled the electrons and holes apart and then slammed them back together at several thousand kilometers per second. The collision results in the emission of light, which Huber's team analyzed to measure the energy required to separate the electron–hole pair. Huber says the information could be useful for improving solar cells, which collect the energy from the separation of electron–hole pairs generated by sunlight.

arXiv considering overhaul for its 25th birthday

12 May 2016

Wired: Established as a site for scientists to share and discuss their work before publication in peer-reviewed journals, arXiv now stores more than 1 million scientific papers and supports more than 125 million downloads per year. But the site's front-facing design has not changed much over the past 25 years, and its back end is running on a lot of legacy code, so site operators are planning on some refurbishment. In April arXiv asked users for design and functionality requests. The survey also asked whether the site should change how it handles checking the quality of uploaded papers and whether it should allow users to directly comment on and annotate papers. Any of these changes could significantly alter how the site, often viewed as a bastion of open-access research, fits into the larger realm of scientific publishing.

NASA's 747 makes first measurement of Martian oxygen since 1970s

12 May 2016

Ars Technica: In the 1970s NASA's Viking lander found that Mars's atmosphere was 95% carbon dioxide, with only minuscule levels of the nitrogen and oxygen that are a significant part of Earth's atmosphere. Over the past 40 years, no subsequent measurements of those trace gases in the Martian atmosphere have been made. Now NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA) has taken a look at Mars's upper atmosphere, where it measured levels of oxygen that were about half of what Viking measured. SOFIA is a Boeing 747 that is specially modified to fly at an altitude of 45 000 ft (13.7 km) and is equipped with a highly sensitive spectrometer that enables measurements in the far-IR. The SOFIA team says the lower-than expected oxygen levels are likely the result of an uneven distribution of the gas in the atmosphere caused by localized releases of oxygen from chemical reactions in the Martian soil.

Hurricane forecasts will be different this year

12 May 2016
Extra Dimensions: Remembering William Gray, the charismatic and controversial tropical meteorologist who invented the seasonal hurricane forecast.

Carbon dioxide emissions are down in the US as fracking increases

11 May 2016
Movement away from coal reduces CO2 output and fuels a surge in hydraulically fractured oil and gas production.

Affordable virtual reality headsets are becoming valuable research tools

11 May 2016
Nature: Because of the proliferation and growing sophistication of video games and other commercial applications, virtual reality (VR) headsets have improved in quality and dropped in price. As a result, they are becoming much more affordable to not just individual users but also research laboratories. Already, researchers have used VR to treat a number of human psychological conditions, such as paranoia and claustrophobia, by virtually exposing patients to the source of their problem, like a crowded elevator or an underground train. Also gaining ground is a related technology called augmented reality, which superimposes images into a real-time environment rather than replacing the real world with a simulated one.

Questions and answers with Michael E. Mackay

11 May 2016
The materials science researcher has written his text as a general introduction to solar-energy utilization and an inspiration for new photovoltaic technologies.

Five islands have disappeared as Pacific sea levels rise

11 May 2016

BBC: The Solomon Archipelago is a lightly populated chain of islands in the South Pacific Ocean. A survey of aerial and satellite images collected between 1947 and 2014 has revealed that five of the islands have been swallowed by the ocean through a combination of rising sea levels and erosion. The islands were vegetated reefs that were unpopulated and relatively small—the largest was only 12 acres (0.05 km2). However, larger, populated islands are also being damaged. One of them, Nuatambu, has lost half its inhabitable area and 11 houses since 2011. The study notes that although the islands have seen sea levels rise as much as 10 mm/year over the last two decades, extreme weather events and inappropriate development are also responsible for some of the damage.

Obama to make symbolic visit to Hiroshima

11 May 2016
New York Times: When President Obama travels to Hiroshima, Japan, on 27 May, he will become the first sitting US president to visit the first city targeted by a nuclear weapon. Hiroshima was devastated by the atomic bomb the US dropped on 6 August 1945; it killed more than 100 000 people and caused widespread destruction. More than 70 years later, the city has been rebuilt and features the 30-acre Peace Memorial Park, which is among the sites Obama plans to visit. Rather than focus on the past, the president intends to direct attention to the future and his efforts to limit nuclear weapons around the world. That sentiment has been echoed by Japan’s prime minister, Shinzo Abe, who has said the visit will be a chance to both honor the dead and lend support to worldwide nuclear disarmament.

<em>Kepler</em> finds 1284 more exoplanets

11 May 2016

Los Angeles Times: On 10 May, the team running NASA's Kepler space telescope announced that the spacecraft had identified another 1284 extrasolar planets, which brings the total number to 2325. The majority of the newly discovered planets are super-Earths or mini-Neptunes—both defined as planets roughly 1.25 to 10 times the mass of Earth. Nine of the planets orbit in the habitable zone of their parent star. The new planet haul resulted not from more data but from a new algorithm that determined how likely a signal detected by Kepler was a planet rather than a false positive. The algorithm was applied to the full dataset of 4302 candidate planets identified by the telescope, including the 984 previously confirmed exoplanets. The algorithm correctly identified the previously confirmed planets and pulled out the 1284 other signals that the team presented.

Earth’s ancient atmosphere may have been much thinner

10 May 2016
New Scientist: The atmosphere on Earth some 2.7 billion years ago may have been less than half as thick as it is today. That finding is based on a new study in which Sanjoy Som of NASA’s Ames Research Center and colleagues looked at gas bubbles trapped in ancient lava covering thousands of square kilometers in the Australian outback. By comparing the larger bubbles that rose to the top with the smaller ones that got trapped at the bottom, the researchers were able to determine that the air pressure billions of years ago when the lava hardened was probably 0–0.5 atmospheres; the best estimate is that the atmosphere was 23% as thick as it is today. That finding contradicts earlier theories that said the atmosphere must have been thicker to prevent Earth’s surface from freezing over when the Sun was much younger and fainter. The researchers say the key may be nitrogen, which might have dominated the primeval atmosphere, warming it and fueling nascent microbial life.

Space agencies develop plan for network of emissions-tracking satellites

10 May 2016
New York Times: The space agencies of China, France, India, the US, and several other countries have distributed a draft of a plan that calls for six to eight satellites to map carbon dioxide emissions with enough precision to identify individual nations as the source. The satellite array, which is estimated will cost $5 billion and be in orbit by 2030, would be similar to the network of satellites that monitors cloud cover. The ability to measure the emissions contributions from individual countries would be a major improvement over the current system of self-reported values based on surface readings, economic analyses, and ecological estimates. In the current system, established in 1992, industrialized nations report yearly but developing nations only have to report occasionally. However, in the 2000s, emissions from developing nations surpassed those of industrial nations and currently are estimated to be 60% of the annual global emissions total.

<em>LRO</em> team asks NASA to extend mission another two years

10 May 2016
Science News: Launched in 2009 for a one-year expedition to study the Moon, the Lunar Reconnaissance Orbiter (LRO) has had its mission extended repeatedly over the last seven years. Mission researchers have completed the primary goals of scouting potential future landing sites for astronauts, looking for water, and probing radiation hazards. LRO is now the longest-lived lunar orbiter, and the team hopes to add at least two more years. Over its extended mission LRO has watched three other spacecraft crash into the Moon's surface, mapped numerous craters, spotted water ice covered by the Moon's regolith, and found evidence of past volcanic activity.

Magnetically levitated, tube-based transportation system would travel at rocket speed

10 May 2016
IEEE Spectrum: Passive magnetic levitation is the key to a proposed next-generation high-speed mass transit system. Hyperloop Transportation Technologies (HTT), a startup based in Southern California, is working on the concept with scientists from Lawrence Livermore National Laboratory, where the technology was first developed. The HTT system would consist of a magnetically levitated capsule that travels at the speed of sound inside a reinforced vacuum tube laid atop pylons. Levitation is achieved by lining the bottom of the capsule with a Halbach array of permanent magnets and running it over a railbed of electromagnetic coils. Such a system could cut travel times between major cities significantly. According to the HTT website, commuters would be able to go from New York City to Washington, DC, in just half an hour. Said to be cheaper and safer than active magnetic levitation systems, such as MagLev, which require power stations along the track, the HTT system is one of several levitated trains currently in development.

Monsoon season may not provide drought relief in India

9 May 2016

CNN: India is experiencing its worst drought in decades. Exceptionally high temperatures some 3–5 °C above average over the past year and two years of below-average rainfall have severely reduced groundwater levels. According to India's Central Water Commission, the country's major water reservoirs are 79% empty, and three-quarters of the country's basins have less water than the 10-year average. They are so depleted that the next monsoon season, which begins in June, will likely not be enough to fully replenish them, says Nitya Jacob of WaterAid India. 

Antarctic sediment core reveals ancient transition from greenhouse to icehouse

9 May 2016
New Scientist: A single marine sediment core has revealed Antarctica’s climatological history from tropical forest to icy wasteland, according to Ulrich Salzmann of Northumbria University in Newcastle upon Tyne, UK, and his colleagues. Collected from the seafloor off Wilkes Land in East Antarctica during the Integrated Ocean Drilling Program, the core contains pollen grains that indicate a change in vegetation between 54 million and 12 million years ago. During the Eocene epoch, when its temperature hovered around 16 °C, the continent was covered with lush tropical forests, which included palms and monkey puzzle trees. By the early Oligocene, those trees had been replaced by more temperate species, including pines, conifers, and beeches. By the Miocene, some 23 million years ago, temperatures had dropped to about 6 °C and mosses and similar tundra plants had begun to take over. All greenery disappeared around 12.5 million years ago when the glaciers took over. Understanding Antarctica’s climate history may become important as climate change causes the continent to once more warm up and its ice to melt. Salzmann and his team presented their work at the April meeting of the European Geosciences Union General Assembly in Vienna.

First full-planet topological map of Mercury released

9 May 2016

Mashable: On Friday, researchers from the Johns Hopkins University Applied Physics Laboratory released the first full-planet mapping of elevations on Mercury. The map was produced from data collected by the MESSENGER spacecraft, which finished its mission roughly one year ago. To produce the map, the scientists used more than one-third of the 300 000 images of Mercury taken by MESSENGER. From the images, the researchers calculated the average ground level and then measured the lowest and highest points on the planet, with the lowest point being 5.38 km below the average and the highest point 4.48 km above the average.

Mount St Helens earthquake activity does not necessarily mean eruption

9 May 2016
Discovery: Despite some 130 small earthquakes that have occurred since 14 March, Mount St Helens in Washington State is not likely to erupt anytime soon, according to the US Geological Survey (USGS). The earthquake activity is reminiscent of what occurred more than 35 years ago, when a series of small quakes starting in March 1980 preceded the cataclysmic 18 May eruption that killed 57 people. Earthquakes around a volcano are caused by magma bubbling up from deep within Earth and putting pressure on the surrounding rock layers, which can fracture and slip. The magma pools in underground chambers, where it can collect until there is enough pressure to erupt to the surface. Such recharging of a volcanic magma chamber, although worrisome, occurs over long periods of time. Similar seismic swarms occurred around Mount St Helens in 2013 and 2014. Nonetheless, the USGS continues to use its state-of-the-art volcano monitoring network to watch for any other signs, such as changes in gas emissions, shallow quakes, or crust deformation, that indicate a volcanic eruption is imminent.

How the bacterium <em>Pseudomonas syringae</em> induces water to crystallize

9 May 2016
The surface of a specialized protein arranges nearby water molecules to promote efficient ice formation.

Holdren lauds Obama’s science and technology accomplishments

6 May 2016
The president has been an unrelenting supporter of science throughout his two terms, his science adviser asserts.