Physics Today’s online staff summarize the most important and interesting news about science from the world's top media outlets.
Science: Even if water levels don't rise as much as expected over the coming century, Washington, DC, will still suffer additional flooding as the land it's built on sinks 16 cm over the next 100 years. It may eventually be under water as the land drops up to 40 m over the next 80 000 years. The cause is the last ice age, and in particular the Laurentide Ice Sheet, which covered much of northern North America. The sheet's weight pressed down the underlying earth, which pushed up land farther south, such as the Washington, DC, area. When the ice sheets retreated, the land started sinking back down. The details, published in GSA Today, are from sediment core samples that have undergone a new technique using electrons trapped in quartz crystals for dating sediment. Electrons are trapped at a predictable rate when the sediment is underground. When they are exposed, the rate changes. Not everyone agrees with the interpretation, but the findings, if backed up with other evidence, will significantly affect our understanding of the geology of the region.
The Daily Telegraph: A spoonful of sugar doesn't just mask the bitter taste of caffeine in coffee in a process called caffeine dimerization; it also changes the chemistry of the drink. Previously, sugar and salt were thought to simply change the water structure of the drink, but new statistical thermodynamics research, published in Food and Function by Seishi Shimizu of York University, has turned this idea on its head. The sugar actually causes the caffeine molecules to clump together, so they have less surface area to stimulate the taste buds. Shimizu tells The Telegraph that such findings "show how complex the study of food is and that we should be conducting research using first principle physics to better understand it."
Nature: Philae, the cometary lander from the European Space Angeny's Rosetta mission, may never be heard from again, but it has provided a wealth of data already, much of it contrary to expectations. When Philae landed it bounced because the surface was not, as expected, a deep layer of dust. Measurements of the leg compression and from the hammer that was supposed to penetrate the surface have revealed that the comet's surface is a hard crust covered in areas with thin layers of dust and ice. The hard surface could have formed due to reactions with solar radiation and compaction, but regardless of the cause it challenges the assumption that cometary material is essentially unchanged since the formation of the solar system. The presence of complex polymers in the surface material is also likely a recent phenomenon. Philae's cameras revealed a wide range of hard-to-explain surface features. Radio signals used to probe the comet show that the interior has a relatively consistent composition and is much more porous than expected based on the nature of the surface.
Science: The Fair Access to Science and Technology Research Act (FASTR) requires federal agencies that spend more than $100 million on research to make freely available any peer-reviewed papers from the research within 12 months of publication. On Wednesday, the Senate Committee on Homeland Security and Governmental Affairs approved the proposal, and next it will go to the full Senate for approval. The original proposal for FASTR set the deadline for open access at 6 months, but it was pushed back due to opposition from scientific societies and university and research groups. The 12-month timeline is consistent with the current National Institutes of Health standards.
Verge: After Virgin Galactic's VSS Enterprise, an experimental SpaceShipTwo design, broke apart in flight last year, the National Transportation Safety Board (NTSB) found that the failure was due to the craft's wings, which had shifted position. Now the agency has confirmed that the problem was caused by human error. In normal operations, the wings are moved into a "feathering" position as the craft reaches apogee in order to slow it down for reentry into Earth's atmosphere. The NTSB's investigation revealed, however, that the copilot unlocked the wings while the craft was still climbing and before it went supersonic. As the craft passed Mach 1, the force on the unlocked wings pushed them into feathering position. Because the craft was not in the proper orientation for the feathering maneuver, the resulting forces on the craft caused it to break up. Virgin Galactic said that it has now added an inhibitor that prevents the wings from being unlocked before the craft has reached Mach 1.4.
Scientific American: With the recent launch of Breakthrough Listen—the privately funded, large-scale search for extraterrestrial intelligence, or SETI—the governing committee of the Arecibo Observatory in Puerto Rico has been confronted with a problem: If the committee decides to partner with Breakthrough Listen and accept funding from Yuri Milner’s $100 million initiative, Arecibo, the world’s largest and most sensitive single-dish radio telescope, could risk losing its financial support from NSF, the US federal agency that owns it. Budget cuts have forced NSF to start divesting from older facilities in order to fund newer ones. Although funding from Breakthrough Listen would help to keep the facility running, it would not cover all the expenses, such as Arecibo’s basic operational costs. Whether NSF will continue to contribute to Arecibo's maintenance, however, depends on the details of the proposed partnership, which have yet to be provided to NSF by Arecibo’s management, and on how such a partnership would affect NSF’s broader mission regarding use of the telescope.
IEE Spectrum: A transistor consists of two electrodes, a source and a sink, and a gate that controls the flow of current between them. Recently researchers created a single-molecule transistor, and now a new and improved technique uses charged atoms for the gate. In this new transistor, a phthalocyanine molecule functions as the transmission channel, which rests on an indium arsenide substrate. Using a scanning tunneling microscope (STM), the researchers arranged indium ions around the H2Pc channel. The transistor turns "on" when enough indium ions are collected around the channel to create sufficient charge to alter the energy of the H2Pc molecule's electrons. When that happens, electrons from the STM, now being used as the transistor's source, can pass through the channel into the substrate.
World Nuclear News: After the Fukushima Daiichi Nuclear Power Plant was severely damaged by a tsunami and earthquake in 2011, Japan closed all of its nuclear power plants. The following year, the country established the Nuclear Regulation Authority (NRA), which drew up new standards for nuclear power plant operation. Now, after a series of upgrades and inspections at the Sendai Nuclear Power Plant, Kyushu Electric Power Company plans to ask the NRA to perform a final inspection of the Sendai 1 reactor. If no problems are found during the week-long process, which is expected to begin on 3 August, the reactor could start operations as soon as 10 August. It would be the first nuclear reactor to restart in Japan since 2011, and 20 more reactors are in line to follow. The government hopes that nuclear power will produce up to 22% of the country's electricity by 2030 and decrease its reliance on fossil fuel imports.
Scientific Computing: A black hole 100 million solar masses in size has been spotted in the process of devouring a star. While examining spectra of objects taken by the Sloan Digital Sky Survey, Andrea Merloni of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, and his colleagues found an unusual change between 1998 and 2005 in the spectrum of one galaxy located some 3.5 billion light-years away. Further confirmation of the high-energy emission came when the team discovered that both the European Space Agency's XMM-Newton and NASA's Chandra X-Ray Observatory, which had taken pictures of the region at about the same time, had also seen the massive flare. An analysis of the data from the three archival sources confirmed that the flare fit the model of a star being pulled into a massive black hole.
Guardian: Researchers from CERN's Large Hadron Collider (LHC) are presenting their latest results at the European Physical Society's Conference on High Energy Physics in Vienna. The ATLAS team confirmed an unexpected finding from the CMS team during the previous LHC run—that regardless of the incident collision angle of the particles, there is an increased probability they are being emitted at a similar azimuthal angle. That behavior is expected in heavy particle collisions but not in proton–proton collisions. From the new run, ATLAS also released the first measurement of the jets of hadrons produced from the collision of quarks and gluons. The measurement, which is in line with the measurements taken during the previous run, reveals that the higher collision energy is producing noticeably more frequent jets.
Science: Mammoths and many other large mammals suffered a massive population decline between 30 000 and 20 000 years ago that eventually led to their extinction. Human expansion, and the hunting associated with it, is widely considered to be a major factor in that decline, but a new study of DNA collected from mammoth fossils suggests that the populations were shrinking well before human expansion was significant. Alan Cooper of the University of Adelaide in Australia and his colleagues established a connection between the diversity of DNA found at specific sites and the size of the species population. Creating a timeline of temperature changes from sediment cores, they found that drops in DNA diversity, and therefore overall population size, were tied to periods of significant short-term warming.