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# News Picks

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Selected by the staff of Physics Today
March 7, 2014 3:14 PM

### Sensor converts radio waves to laser pulses with minimal noise

Nature: Radio wave receivers use resonance in an antenna to induce an electrical signal that is then amplified electronically. However, even when the equipment is supercooled, the amplification process introduces noise into the signal. A new sensor, developed by Eugene Polzik of the University of Copenhagen and his colleagues, converts the radio signal into an optical signal with no electrical amplification. In the sensor, a laser is reflected off a silver nitride membrane, which is coated with a thin layer of aluminum and suspended over a gold plate. As with previous receivers, the radio signal produces an oscillating electrical signal, but instead of being amplified it creates a voltage between the gold plate and aluminum-sided membrane, which causes the membrane itself to oscillate. The oscillation causes pulses in the reflected laser light, which provides an easy-to-read signal that matches the original radio wave, with 100 times less noise than the best previous receivers. The technique could be used in satellite radio telescopes, MRI scans, and quantum technologies; however, the system is still very inefficient.
March 7, 2014 2:59 PM

Space.com: Today the White House revealed its proposed budget for the 2015 fiscal year. It requests $17.5 billion for NASA, 1% less than was given the agency in the 2014 budget approved in January. The amount is$600 million more than was given in 2013, while the government operated under the effects of the sequester. Of the total amount allocated for 2015, $5 billion would go to fund science, with allocations of$607 million to the astrophysics division and $1.3 billion to planetary science. Funding for the James Webb Space Telescope would continue under guidelines established in 2012. The controversial mission to visit and capture an asteroid did not receive direct funding, but money was put into programs for developing the necessary technologies for the larger mission. One surprise was the loss of some funding for the SOFIA telescope, which will cease operating unless Germany increases its contribution to the project. All of the allocations are likely to change as Congress and the White House attempt to reach a final version of the budget over the next several months. March 4, 2014 4:32 PM ### Rectangular concert halls increase range of perceptible sound Science: The structure of concert halls has a significant impact on how well the audience can hear the music being played. The study of room geometry and how sounds travel through the room is a complex one. In some cases, the simpler the shape, the more effective it is at increasing the "perceived dynamic range" of the music. A rectangular concert hall can increase the range of sound by up to two decibels by reflecting more sounds off the side walls and toward the audience, according to a recent study. March 4, 2014 2:50 PM ### Giant virus found in Siberian permafrost Telegraph: The largest virus found to date was discovered buried about 30 meters down in the permafrost of northeast Siberia, where it has probably lain for tens of thousands of years. About 1.5 micrometers in length, the so-called Pithovirus poses no threat to humans, according to researchers. It is, however, lethal to amoebas. The find points up the possibility that other such giant viruses, long thought extinct and potentially harmful to humans, could turn up as global warming melts permafrost. But giant viruses may also contain genes never before seen in living things and thus yield clues to the origin of life on Earth. March 4, 2014 2:40 PM ### France testing viability of underground nuclear waste repository BBC: The French nuclear waste agency Andra is currently working on what may become the world’s first underground repository for nuclear waste. The site consists of a series of tunnels carved out of 160-million-year-old rock about one-half kilometer below the small town of Bure in northeast France. Huge bore holes drilled into the walls would hold capsules of the radioactive material for tens of thousands of years. The agency is testing the geological soundness of the site and various waste-containment strategies. If all goes according to plan, Andra will open an industrial-scale facility by 2025. February 28, 2014 3:05 PM ### Laser-light mirror inspires design for space telescopes Nature: A new type of mirror may revolutionize space telescopes, but only if a number of significant engineering challenges are overcome, reports David McGloin in Nature. More than 35 years ago astronomer Antoine Labeyrie proposed building a space-based mirror consisting of millions of microscopic particles held in place by laser light. Such a mirror could "self-heal" in the event of being hit with debris and have a diameter tens of meters greater than more "standard" space telescopes. Now in Physical Review Letters, Tomasz Grzegorczyk and colleagues describe their first step toward this goal. They have created an optically bound structure of about 150 spherical polystyrene particles, each with a diameter of 3 micrometers, that can act as a mirror. So far the mirror can only work in water and is unstable over long time periods, and the image quality is too crude for optical astronomy. The researchers have high hopes that those issues can be overcome. February 28, 2014 3:00 PM ### New quasiparticle found, named a dropleton Scientific American: Researchers working with lasers and a gallium arsenide semiconductor created a new quasiparticle that has liquid properties; they've dubbed it a “dropleton.” Energy pulses from the laser created electron–hole pairs, called excitons, in the gallium arsenide. At a certain threshold, the electrons and holes rearranged themselves and started flowing around one another like particles in a liquid. The new particles require at least four electron–hole pairs to be stable. More a mathematical tool than an actual particle, quasiparticles such as the dropleton may help scientists better understand the quantum mechanics involved in microscopic systems of large numbers of interacting particles. February 28, 2014 12:35 PM ### Joint US–Japan weather satellite launches Universe Today: Earlier this morning the Global Precipitation Measurement Core Observatory launched from Japan. Jointly developed by the US and Japanese space agencies NASA and JAXA, the weather research satellite will orbit Earth at an altitude similar to that of the International Space Station and monitor global rain and snowfall. It will be one of nine highly advanced weather satellites orbiting Earth. With the new satellite, researchers around the world will be better able to study climate change, manage water resources, and track severe weather events like hurricanes, floods, and droughts. February 28, 2014 4:18 AM ### Surveying a lead-laced ocean Science: A$300 million international collaboration has been working to document the presence of trace metals and other chemicals in the world’s oceans. Among its findings is a vast plume of lead located about 1000 meters deep in the Atlantic Ocean. That lead fingerprint is included in a map the group has created, called eGEOTRACES. It was constructed from nearly 30 000 water samples collected at 787 study sites over the past few years. Traces of other elements have also been found, including iron, nickel, and zinc. The lead plume is from water that was once at the ocean's surface and is slowly sinking into its depths. It represents a time capsule of the amount of lead the industrialized world emitted in the past, primarily from the burning of leaded fuel in cars. Lead contamination continues to be a problem in parts of Africa and Asia, where leaded gas is still being used.

February 27, 2014 1:00 PM

### Pine forests’ scent may help mitigate global warming

BBC: The pine scent emitted by forests may be more than just a sweet smell. Researchers have been studying the scented compounds given off by pine trees and the way they react with oxygen to form airborne particles, called aerosols. Aerosols are known to reflect sunlight and cause clouds to form, which can have a cooling effect on the atmosphere. Because about half of the aerosols over pine forests seem to come from those pine-scented vapors, the researchers believe they could play a major role in reducing the impact of global warming. Moreover, as temperatures continue to warm, more plants will grow and emit more vapors.
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