Physics Today Daily Edition
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Updated: 2 weeks 18 min ago
New Yorker: Currently under construction in the south of France, ITER is slated to become the world’s largest experimental tokamak nuclear fusion reactor. Once it is up and running, the facility will function like a synthetic star, ionizing hydrogen atoms to form helium and generating 10 times as much heat as the Sun. The result will be a giant power plant that produces “no carbon, virtually no pollution, and scant radioactive waste,” writes Raffi Khatchadourian for the New Yorker. In his lengthy article, Khatchadourian writes in depth about the history of thermonuclear power, the genesis of ITER, and his visit to the construction site and meetings with key personnel.
Mangalyaan has relatively modest capabilities and goals, but almost order-of-magnitude savings.
Space.com: There is a type of star that continues to accrete gas even as it shines. Such stars are 10 times as massive as the Sun and most active in the UV spectrum. The common models for star formation show that the radiation those stars emit should push the protostellar gas away from the star. But with young massive stars, that is not what has been observed. Now Mac Low of the American Museum of Natural History and his colleagues have created a model in which the gas around the star has denser pockets and filaments that absorb most of the radiation, which shields the gas farther from the star.
Guardian: The eruption of at least 17 volcanoes since 2000 is partly responsible for a temporary slowing of global warming. World surface temperatures have been rising over the past century due to increased levels of anthropogenic greenhouse gases being released into the atmosphere. However, since 1998, when temperatures peaked, the overall rise has been less than predicted by modeling and observational data. According to a recent study published in Nature Geoscience, the slowdown may be partly attributed to Sun-blocking aerosols, like sulfur, ejected by volcanoes. Nevertheless, the researchers point out that many factors are involved and that volcanic activity provides only a “temporary respite.”
New Scientist: Kaposi's sarcoma, which is caused by a herpes virus, is the most common cancer in sub-Saharan Africa. Up to 70% of those infected die within three years, so early detection is key. The KS-Detect, built by Li Jiang and David Erickson of Cornell University, may provide doctors with that ability. The device focuses sunlight on a microscopic channel etched on a microchip. The channel is filled with a sample from a patient, and the heat from the sunlight drives a polymerase chain reaction (PCR), which amplifies the presence of DNA from the herpes virus that causes the cancer. A dye mixed into the sample glows when the DNA concentration reaches a detectable level. The chip then sends the result to an attached smartphone. Normally, PCR requires a lot of electricity, which is not readily available in much of sub-Saharan Africa. The technology may also be adaptable for other diseases, such as tuberculosis.
BBC: The oldest piece of Earth’s crust—a zircon crystal—has been found in the Jack Hills region of Western Australia. At least 4.4 billion years old, the zircon is being studied by John Valley of the University of Wisconsin–Madison and colleagues, whose paper appears in Nature Geoscience. The researchers determined the crystal’s age by looking at the ratio of uranium atoms to those of lead, its decay product. Due to its hardness and durability, zircon can survive many geologic processes; that ability makes it one of the oldest materials on Earth. By looking at oxygen isotope ratios and other properties of the zircon, the researchers have determined that Earth’s crust is older than previously believed and that its surface became habitable very early on in the planet’s existence.
For the first time, it’s possible to create depth-resolved images of a painting without damaging it.
Feeding the world's increasingly urban population could entail building multistory farms in cities.
Max von Laue was awarded the 1914 Nobel Prize in Physics for his discovery of the diffraction of x rays by crystals.
Ars Technica: To better understand how a supernova explodes, astronomers analyze the glowing debris left behind. Theoretical models predict that such explosions are asymmetrical, but until now observational evidence has been inconclusive. In a recent study of Cassiopeia A, a massive star in our Milky Way galaxy that went supernova more than 400 years ago, researchers looked for evidence of a radioactive isotope of titanium, one of the many heavy elements created when stars explode. As predicted, the distribution of the isotope showed evidence of asymmetry in the boundary layer between the collapsing core and the exploding outer layers. However, the distribution of iron and nickel did not match that of titanium, and so the evidence remains inconclusive.
Science: After years of trying to create artificial muscle from such expensive materials as shape-memory alloys and single-walled carbon nanotubes, researchers have found a far cheaper alternative: ordinary plastic fishing line and sewing thread. In a paper published today in Science, Ray Baughman of the University of Texas at Dallas and colleagues describe their work of twisting plastic fibers and threads into long yarns that contract and expand when stimulated by heat or zapped with electricity. Such muscle materials could be used in a number of technologies, from prosthetic limbs to robots.
Nature: The US Department of Energy has approved $6.5 billion in loan guarantees for two nuclear power plants under construction in Georgia. Along with two others that have been approved for construction in South Carolina, those are the first new reactors to be built in the US in three decades. The Obama administration supports nuclear power as a way for the US to reduce its greenhouse gas emissions and dependence on foreign oil, but it is also funding other energy sources, such as natural gas and renewables, which have been providing stiff competition.
BBC: The UK has announced it will be lending its support to the US Long Baseline Neutrino Experiment, one of several big neutrino experiments that have been proposed around the world. The LBNE will send a beam of trillions of neutrinos underground from Fermilab in Illinois over a distance of 1300 km to South Dakota’s Sanford Lab. Neutrinos, which are among the most abundant particles in the universe, are thought to be key to understanding fundamental principles about the nature of matter. The experiment is projected to cost some $1.5 billion. While the US has committed to $1 billion in funding, it has been seeking international partners to provide the remainder. The UK will be contributing some $30 million, and nine of its universities will be involved in the project, which is expected to be completed over the next decade.
In his quest to discover general biophysics principles, the theoretician found some that govern seemingly disparate phenomena—for example, protein folding, embryonic development, and neural computation.
Ars Technica: Earlier this week, the Chandra X-Ray Observatory imaged the particle jet emitted by one of the fastest-moving neutron stars ever observed. Traveling 4 million–8 million km/hr, IGR J11014−6103 was probably set in motion when a supernova exploded some 15 000 years ago. As the neutron star speeds through space, it has left in its wake a trail of particles stretching for trillions of kilometers. That particle jet may yield clues not only to the neutron star’s motion and axis of rotation but also to the supernova itself and the processes that produced it.
Nature: Despite the $20 million prize being offered by the X Prize Foundation for the first privately funded team to land a rover on the Moon, and an additional $6 million being offered in “milestone prizes,” it may be some time before any private group can raise sufficient funds to accomplish such a mission. Currently 18 teams are working to put a lander on the Moon by the end of 2015, and 5 teams are in the running to demonstrate a prototype by September 2014. However, the technological hurdles are too high and the financial incentives too low for any team to succeed at this time, according to Jonathan McDowell of the Harvard–Smithsonian Center for Astrophysics. Since the rules and deadlines for the X Prize were first announced in 2007, they have had to be modified several times. Nevertheless, most of the competitors plan to continue working toward a Moon launch, with or without the chance to win the X Prize.
BBC: Yesterday some 100 tons of highly radioactive water leaked from a storage tank at Japan’s Fukushima nuclear plant. Ever since being damaged in the March 2011 earthquake and tsunami, the plant has suffered multiple problems, including leaks and power cuts. This leak was not as severe as the one last August, which released about 300 tons of radioactive water. According to Masayuki Ono, a spokesman for the Tokyo Electric Power Company, which operates the plant, the leaked water is unlikely to reach the ocean, and the company is in the process of cleaning up the spill.
Los Angeles Times: Every year about 60 tons of helium gas escapes into the atmosphere from steam vents and hot springs in Yellowstone National Park. The helium, which has been accumulating underground over hundreds of millions of years, only started seeping out over the past 2 million years. On a geologic time scale, that seepage is considered a recent phenomenon, according to William Evans of the US Geological Survey, coauthor of a recent study published in Nature. While helium is constantly being produced in Earth’s crust as uranium and thorium decay, it usually escapes via groundwater or as the result of tectonic activity. At Yellowstone, however, the helium has collected over time in the 2.5-billion-year-old rock unique to the area. Volcanic activity that began some 2 million years ago probably triggered the helium release, and that activity is still evident in the area’s numerous geysers, hot springs, and fumaroles. Although there is currently a helium shortage for use in industry and electronics, it wouldn’t be economical to try to capture and purify the helium in Yellowstone, says Evans.