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News Picks

Physics Today’s online staff summarize the most important and interesting news about science from the world's top media outlets.

There are 16 posts for the selected month (July 2015).
July 7, 2015 2:08 PM

Sediment cores reveal regional history of tsunamis

Economist: Knowing that a coastal region has been hit by tsunamis in the past, and how frequently, is important for preparing for potential future strikes. A team led by Harvey Kelsey of Humboldt State University in California has found that evidence of past tsunamis can be found in sediment cores taken near shorelines. The researchers took cores from the Aceh region of Indonesia, which was seriously hit by a tsunami in December 2004. Before the tsunami, the region was heavily covered by mangrove forests. The top of the sediment core consisted of loose sand deposited by the tsunami. Just below it was a layer of soil rich in mangrove pollen and small fossilized animals known as foraminifera. Deeper in the core, that pattern was repeated several times, revealing that three more tsunamis had occurred within the last 8000 years. Layers of sand on top of sand indicated that even more tsunamis struck before the mangrove forests grew back. Kelsey's group believes that similar analysis of coastal sediment cores from other regions could reveal their level of tsunami risk.

July 7, 2015 1:55 PM

Study questions whether mammograms do more harm than good

Washington Post: A new study published in JAMA Internal Medicine questions the effectiveness of mammograms in reducing mortality due to breast cancer. In 2000 the researchers looked at data on 16 million US women who were 40 years old or older and found that more than 53 000 were diagnosed with breast cancer. After following those women for the next 10 years, they found that the mammography screenings led to the diagnosis of more smaller cancers but not to that of larger and more dangerous ones. In addition, they found no difference in the overall rate of death from the disease. Particularly alarming were the number of false-positive results. The researchers conclude that breast cancer screening, more so than other types of cancer screening, may unintentionally lead to overdiagnosis and overtreatment, which could outweigh its benefits.
July 7, 2015 1:36 PM

McNutt to be first woman to head US National Academy of Sciences

Science: Marcia McNutt, editor-in-chief since 2013 of Science and other journals published by the American Association for the Advancement of Science, has been nominated to be the next president of the National Academy of Sciences. The NAS will hold the final election in December 2015, but the vote is mostly a formality as there has never been more than one candidate for the presidency. McNutt is a geophysicist and previously served as head of the US Geological Survey. She says that she will continue to work at AAAS until taking her position at NAS on 1 July 2016, replacing two-term president and atmospheric scientist Ralph J. Cicerone.

July 7, 2015 11:40 AM

Biggest space telescope yet proposed would succeed Hubble

Nature: As the Hubble Space Telescope celebrates its 25th anniversary, a group of US astronomers are discussing a potential successor. In their study, commissioned by the Association of Universities for Research in Astronomy, the researchers propose building the High-Definition Space Telescope (HDST), a 12-m-class instrument that, like Hubble, operates at UV and optical wavelengths. The HDST would have a mirror five times the width of Hubble and nearly twice that of the James Webb Space Telescope (JWST), scheduled to launch in 2018. The JWST, however, operates only in IR light, so the researchers say a telescope like the HDST will be needed to continue Hubble’s search for Earth-like planets and life outside our solar system. Because such a giant telescope could cost more than $10 billion, NASA may need to scale down the project or partner with other space agencies to build it.
July 6, 2015 4:37 PM

Report: More attention needed on oceanic carbon dioxide

BBC: An international collaboration of marine scientists has published a paper in Science detailing the variety of threats the oceans face from rising carbon dioxide levels. The scientists say the combination of the effects is causing a change in ocean chemistry at a level unseen since the Permian–Triassic extinction event 250 million years ago. Since 1750, the oceans have absorbed 30% of the CO2 that humans have released into the atmosphere, and as a result, seawater is becoming more acidic. Since 1970, the oceans have also absorbed 90% of the additional heat generated by industrialization, which is making it harder for the oceans to store oxygen. That combination poses a threat to oceanic life that has not been addressed by climate change proposals.

July 6, 2015 3:30 PM

New Horizons spacecraft sees spots on Pluto, temporarily loses contact with Earth

Los Angeles Times: On 1 July NASA reported that the New Horizons spacecraft had sent back color images of Pluto in which four mysterious black spots, each about 500 km across, can be seen along the equator. Although no one knows what the spots are, scientists hope to get more information as the craft makes its closest approach ever to the distant dwarf planet on 14 July. However, on 4 July, New Horizons suffered a communications glitch, during which NASA lost contact with it for 1 hour and 21 minutes. Because the spacecraft is some 4.8 billion km from Earth, it takes about 9 hours for messages to travel back and forth. That time delay is exacerbating attempts to fix the problem. Nevertheless, mission controllers say the probe is on course to fly within 12 500 km of Pluto. Scientists hope it will be operating normally by then and able to make some key science observations.
July 6, 2015 2:48 PM

Ultrasound provides better fingerprint scanner

Nature: Most electronic fingerprint scanners identify prints by generating a current where the fingers' ridges touch the scanner and mapping their pattern. The scanners are susceptible to failure, however, due to moisture and dirt, which can prevent them from detecting the ridges and the valleys in between. Now David Horsley of the University of California, Davis, and his colleagues have developed an alternative scanner that uses ultrasound. The scanner employs a chip covered in aluminum nitride, which can convert mechanical stress to electrical signals. When a finger is pressed against the device, an ultrasound pulse is generated that reflects back from the finger with a pattern dependent on its ridges and valleys. With a longer pulse, the scanner can even measure the depth of the valleys, which can help identify fake fingerprints. Horsley's team says that the use of aluminum nitride—already used in chip manufacturing—may overcome some of the difficulties of incorporating ultrasound devices into commercial electronics.

July 6, 2015 1:30 PM

Universe’s Big Bang may end with a Big Rip

Guardian: Most scientists agree that the universe began with a Big Bang, but how it will end continues to be a matter of discussion. Various scenarios have been proposed, among them the Big Crunch, in which the universe’s expansion slows and gravity causes the universe to collapse in on itself, and the Big Freeze, in which the universe continues to expand to the point where matter becomes so spread out and cold that all movement ceases. The latest theory is the Big Rip, in which the universe’s ever-accelerating expansion results in the explosive tearing apart of all matter. In their paper in Physical Review D, Marcelo Disconzi of Vanderbilt University in Tennessee and colleagues reexamine the concept of cosmological bulk viscosity, or the ability of a fluid-like universe to expand or contract. They put forth the idea that the expansion of the universe could continue to accelerate until it reaches some critical point—the Big Rip—at which everything, even the constituents of matter, will be annihilated. Fortunately, that won’t happen for at least another 22 billion years.
July 2, 2015 2:10 PM

Celestial sleuths pinpoint exact moment iconic VJ-day photo was taken

Los Angeles Times: It has long been assumed that the famous VJ-day photo of a US Navy sailor and a woman in white kissing in Times Square was taken just after 7:00pm on 14 August 1945—when the end of World War II was officially announced. Now a team of astronomers has used a distinctive shadow to determine that the iconic photo by Life magazine photographer Alfred Eisenstaedt was actually taken earlier that day. Donald Olson of Texas State University and colleagues studied hundreds of vintage photos, maps, and building blueprints to discover what cast the shadow: an L-shaped sign on the roof of the Hotel Astor. Using trigonometry and geometry, they then figured out where in the sky the Sun had to have been to cast the shadow. From that they were able to pinpoint the exact moment the photo was taken: 5:51pm. The researchers' findings have been published in the August 2015 issue of Sky & Telescope.
July 2, 2015 2:00 PM

Solar Impulse breaks record for longest solo flight

BBC: Andre Borschberg, who is piloting the long-range solar-powered aircraft Solar Impulse 2, has broken the record for the longest nonstop solo flight without refueling. Traveling from Japan to Hawaii on the seventh leg of an around-the-world tour, Borschberg surpassed the previous record of 76 hours in the air—set by Steve Fossett in 2006—and still has at least another 40 hours to go. Borschberg has been tag-teaming with copilot Bertrand Piccard, who will take over in Hawaii to fly the next leg of the journey to Phoenix, Arizona. Once they complete their circumnavigation of the globe, which began and will end in Abu Dhabi, United Arab Emirates, the aircraft will have flown a total of 35 000 km. Solar Impulse 2 runs entirely on solar power, and its average speed is just 50–100 km/hr, much slower than that of liquid-fueled aircraft.
July 2, 2015 1:57 PM

Comet 67/P covered in sinkholes and caves

Ars Technica: The European Space Agency's Rosetta spacecraft, which is in orbit around comet 67P/Churyumov-Gerasimenko, has been supplying astronomers with highly detailed pictures of the comet's surface. Many of those pictures have revealed sinkholes as wide as 200 m and as deep as 180 m. At first it was thought that the sinkholes could be the result of outgassing—as the comet approaches the Sun, frozen gases warm and explode—but the amount of material in outgassing events didn't match the size of any of the sinkholes. Instead, Dennis Bodewits of the University of Maryland, College Park, and his colleagues say it appears to be the other way around—the outgassing results from the formation of the sinkholes. The holes themselves form as surface ice sublimates and dust fills the depression until it collapses, creating a deeper hole. Bodewits's team believes that the comet's nucleus is 75–80% empty space, which is what allows so many sinkholes to form.

July 2, 2015 11:55 AM

Potential dark-matter signal likely just undiscovered pulsars

New Scientist: In 2009, NASA's Fermi satellite began detecting an apparent excess concentration of gamma rays that appeared to come from the Milky Way's central region. According to some theories, the signal could be the result of dark-matter collisions in the dense core region of the galaxy. Now, two independent teams analyzing the data argue that the signal did not account for thousands of previously undiscovered pulsars, which are rapidly rotating neutron stars that emit bright pulses of radiation. The finding is significant not just for potentially eliminating a sign of dark-matter collisions but for massively increasing the number of known pulsars in the Milky Way. More data will soon be available from Fermi that is expected to clarify the situation even further.
July 1, 2015 3:00 PM

Low-dose radiation has small but measureable long-term risk

Nature: A study of 300 000 nuclear-industry employees from France, the UK, and the US has provided the first clear look at the risks of low-dose ionizing radiation. The researchers obtained exposure records dating back 60 years for employees who worked in the industry for at least one year while wearing a dosimeter. The researchers then followed up to track mortality from leukemia, lymphoma, and multiple myeloma. The study revealed that on average the workers received 1.1 mSv per year above the average yearly background radiation, which is about 2–3 mSv. As the amount of radiation exposure increased, there was a linear increase in the rate of leukemia as well. Similar patterns for other cancers were not statistically significant. Instead of the 134 deaths expected from leukemia, the researchers found there were 531. And while none of those deaths occurred in any employee who received less than 50 mSv of radiation, the linear extrapolations suggest that every 10 mSv of radiation exposure increases the risk of leukemia by 0.002%.

July 1, 2015 2:30 PM

European Space Agency gets new director general

BBC: As of today the European Space Agency (ESA) has a new director general—Johann-Dietrich Woerner. He replaces Jean-Jacques Dordain, who had held the position since 2003. Besides continuing ESA’s ongoing programs and projects, such as the Rosetta mission, Woerner says he wants to plan for ESA's future, what he terms Space 4.0. That future includes the commercialization of space and increased interaction with society. Before assuming the ESA directorship, Woerner served as chief of the executive board of the German Aerospace Center.
July 1, 2015 1:54 PM

Hubble suggests quasars are driven by galactic collisions

Ars Technica: Quasi-stellar radio sources, or "quasars," are supermassive black holes, found at the center of galaxies, that produce extreme amounts of light as they pull material into themselves. The material swirling around the black holes is much brighter than the starlight of their host galaxies and can be up to 100 times brighter than all the stars in the Milky Way put together. That brightness disparity makes it hard to study quasars and to look past them to study their host galaxies. However, the difference in brightness is much less in certain areas of the spectrum. C. Megan Urry of Yale University and her colleagues used a near-IR camera on the Hubble Space Telescope to examine 11 quasars, all roughly 12 billion light-years away. They were selected because each is partially obscured by dust, which further reduces the brightness disparity. Urry's team found that all 11 of the host galaxies were undergoing collisions with other galaxies. That discovery supports the theory that galactic collisions drive the feeding of the black holes by disrupting the material surrounding them.

July 1, 2015 12:30 PM

Muon tomography used to inspect industrial equipment

Science: A new technique to scan equipment for problems or to look for nuclear material and other contraband uses the scattering of muons created when cosmic rays collide with molecules in Earth’s upper atmosphere. Able to penetrate matter more deeply than some other particles, muons have been used to image concrete degradation, valve conditions, and pipe-wall thickness at nuclear plants, according to a study published in AIP Advances. Imaging muons requires two sets of detectors to map the muons' trajectories before and after they pass through the object being studied. The denser the object, the more the muons are deflected. That information is then used to create a three-dimensional image of the mass distribution. Because muon radiation is ubiquitous on Earth and nonharmful to humans, muon tomography poses fewer problems and requires fewer safety measures than x-ray imaging. However, it takes longer to create an image, so it is better suited for routine inspections and monitoring.
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