Physics Today Daily Edition
New Scientist: Thanks to the close packing of the cells that line the blood vessels in our brains, only the smallest molecules can pass from the circulatory system into the central nervous system. Bacteria and viruses are too large to pass through the blood–brain barrier (BBB), but so too are antibiotics and drugs that treat cancer. Six years ago researchers from Harvard University and the University of Toronto used ultrasound to breach the BBB in lab rabbits by inducing microbubbles in the blood to vibrate and push apart the barrier's cells. Now a team from a Paris-based medical startup called CarThera has demonstrated a way of implementing that approach in human subjects. Rather than direct the ultrasound through the skull, as was done in the case of the rabbits, the researchers surgically implant an ultrasound transducer. The four patients in the ongoing trial all suffer from recurrent gliobastoma. After their tumors had been surgically removed, the transducers were installed through the same hole in the skull. Once a month the transducers are switched on while the patients receive normal chemotherapy. The success of the therapy in preventing the cancer's recurrence is likely to be known in a few months' time.
BBC: Disordered layers of nanoscopic crystals in the iridescent wings and carapaces of various insects are known to cause the glittery shininess of those animals. Now the same phenomenon has been shown to be responsible for the silvery nature of fish scales. Nicholas Roberts of the University of Bristol in the UK and his colleagues have demonstrated that fish scales have a similar crystalline structure as other iridescent surfaces. As light enters the material, it bounces off different structural layers and reflects back with varying levels of interference and wavelength absorption, resulting in brilliant colors and luster. Adapting the structure could allow for the creation of highly reflective surfaces for use in lighting systems and other technologies.
Nature: Since its inception in 1971, the Protein Data Bank (PDB) has served as a freely accessible depository and archive for the three-dimensional structures of proteins and other biomolecules. Most of the structures in the PDB are for single molecules determined by x-ray crystallography. Now new techniques—and new combinations of techniques—record the structures of bulky molecular complexes, such as the ribosome. Some structures consist of movies. Earlier this month a workshop convened in Hinxton in the UK to tackle the challenge of storing those structures. Not only do they require more disk space, they also require new formats to define them. As Ewen Callaway reports for Nature, the workshop resolved to seek funding to meet those challenges and to set up a new database dedicated to the ribosome, RNA polymerase, and other molecular machines.
Science: Lockheed Martin recently received a lot of publicity for revealing a project to create a compact fusion reactor. At a press conference yesterday, Tom McGuire, the project leader, said the goal of going public was to help find R&D partners. The company has been working on the project for the past four years and believes it has a viable design that combines aspects of several past fusion projects. The core of the reactor uses multiple layers of magnetic confinement and recirculates particles through the system. McGuire said the test device that the team built sustained a stable plasma on more than 200 runs, but he did not provide any details about the measurements. The team hopes to have enough information to publish sometime next year.
Nature: An appeal is in progress for the six Italian seismologists and one government official who were implicated in the deaths of 29 people during the 2009 L’Aquila earthquake. In 2012 the seven were convicted of failing in their duty to evaluate and communicate the risk of a large earthquake to the general public. Sentenced to six years in prison and permanently banned from public service, the men maintain their innocence. They deny having made any reassuring statements, point out that their meeting to discuss the issue had been private, and instead blame the media for the subsequent misunderstanding. The prosecution maintains that the accused did not sufficiently highlight the probability of a strong earthquake and did nothing to contradict what was reported. The appeal, which began 10 October, is expected to be concluded by early November.
Guardian: A hollow laser has been developed that performs like a tractor beam to push and pull objects over relatively large distances. The objects it moves are only 0.2 mm in diameter, but it can move them up to 20 cm—more than 100 times as far as any previous tractor beam. Created by Wieslaw Krolikowski of the Australian National University and his colleagues, the hollow laser acts like a tube and surrounds the object, and the light heats the object's surface. When air particles hit the heated areas, they are accelerated away, which causes the object to move in the opposite direction. The researchers believe that the effect could be extended over distances of meters, but their lab was not large enough to test the theory.
Sydney Morning Herald: Weather bureaus around the world are keeping a close eye on conditions in the tropical Pacific Ocean, where it looks like an El Niño event may be imminent. Sea-surface temperatures around Australia have been warming since March, and the last two weeks have seen a marked rise. In addition, the continent has been experiencing warmer and drier conditions than usual. All are signs of an impending El Niño, and the US National Oceanic and Atmospheric Administration predicts one will begin in the next one to two months. El Niño events in the Pacific have global repercussions, and combined with global warming in general, even a weak El Niño this year could make 2014 the hottest year since record keeping began in 1880.
New York Times: Getting permission to build new nuclear reactors is difficult, and building them is extremely expensive. To help fill the gap before new reactors are operational, power companies have sought and been granted extensions for their existing reactors. Most were originally built in the 1980s, with a predicted economic lifespan of 40 years. To date, more than 70 reactors have been granted 20-year extended licenses by the Nuclear Regulatory Commission. Now, three power companies are requesting extensions of yet another 20 years for some of their reactors. Although concerns have been expressed about the possible long-term effects of radiation on the metal and concrete in the reactors and their cooling systems, both NRC staff and industry experts agree that with proper monitoring, the extended operations should be safe. The question now is what that proper monitoring would entail.
New York Times: As the US negotiates with Iran over its nuclear program, President Obama may end up striking a temporary deal without the approval of Congress. According to the Treasury Department, the president has the authority to suspend many of the US sanctions against Iran without waiting for a congressional vote. However, such a suspension would only be temporary, as only Congress has the power to permanently terminate them. The sanctions have proven to be a valuable bargaining point with Iran. Hence proponents emphasize that lifting any sanctions must be a gradual process, with Iran allowing the International Atomic Energy Agency to verify step by step that the necessary benchmarks have been met. It is hoped that some agreement can be reached so that Iran does not revert to covert means of obtaining nuclear technology.
Ars Technica: Piezoelectric materials develop an electric field when they are stretched or compressed. Practical piezoelectrics tend to be bulk crystals or crystalline thin films, but piezoelectricity has been predicted in crystals just one atom thick. Now, molybdenum disulfide (MoS2), which is not piezoelectric in bulk, has been shown to be piezoelectric under certain interesting conditions. The material is strongly piezoelectric when it is just one atom thick, but the effect is eliminated when a second layer is added. With a third layer, it is piezoelectric again, but less so than before. Experimentation revealed that the material is piezoelectric only when there is an odd number of layers, and that its strength decreases as the number of layers increases. Computational modeling suggests that the layers have random orientations, causing them to cancel each other out. Further testing also showed that the more single-layer flakes that are arranged in series, the higher the produced voltage. That means that MoS2 could potentially be used for powering nanoelectronics and wearable technologies.
Nature: Axions are hypothetical, uncharged, extremely light particles that were originally proposed to explain the absence of CP violation in the strong nuclear force. The particles were later adopted by theorists as a potential form of dark matter, and now, they may have been detected. George Fraser of the University of Leicester, UK, and his colleagues analyzed 12 years of x-ray data collected by the European Space Agency’s X-Ray Multi Mirror Mission (XMM-Newton) as it orbited Earth. They found an unexplained surplus of x rays as the satellite passed between Earth and the Sun. After ruling out all known possible causes, Fraser’s team proposes that the surplus could be caused by axions from the Sun being transformed into x-ray photons by Earth’s magnetic field. They have also found tentative evidence of the same signal in data from the Chandra X-Ray Observatory, but several more years of data are needed to confirm the signal. Even if the signal holds up, the cause could lie in the physics of the Sun's x-ray emitting corona rather than in the transformation of axions into x rays.
BBC: A large-scale solar export project is in the works that would transport energy from Tunisia to the UK. The TuNur project, a partnership between a group of Tunisian investors and UK-based Nur Energie, would consist of concentrated solar power plants located in the Tunisian desert and a 2-GW high-voltage direct-current cable to transport the energy to Italy. From there it could be sold to customers in the UK and, perhaps, various other European countries. The developers claim the electricity supplies will be secure, deliverable on demand, and cheaper than home-based sources, such as offshore wind. The project is one of several being proposed by renewable energy developers that are based outside the UK.
Nature: The Chinese government has charged seven leading scientists with misusing millions of dollars in government research grants. The charges are based on an investigation by the National Audit Office (NAO) of more than a dozen large engineering and applied research projects, which together receive $8 billion a year in funding. Among the allegations are the appropriation of research funds for personal use and the forging of receipts and invoices. And the problem may be even more widespread. According to a report released by the NAO last year, it's possible that up to half of all research funds have been misused. At least one science policy expert says that it points up the lack of guidelines and oversight mechanisms concerning the allocation of research grants in China.
New Scientist: Titan has ethane and methane rivers and lakes. Enceladus has eruptions of water at its southern pole. Now it appears that Mimas may have a subsurface liquid layer. The moon was considered unlikely to have any liquids because it isn't geologically active and has a nonmolten core. Nevertheless, Radwan Tajeddine of Cornell University and his colleagues believe otherwise. Examining pictures of the moon taken by Cassini, they observed an irregularity in the rotation of the moon's surface, which could be explained by the presence of a layer of liquid lying beneath it. The more likely explanation for the wobble, however, may be the possibility that Mimas's silicate core is not spherical, as it is unlikely that a subsurface water layer could remain liquid for so long without any core heating. Another Cassini flyby could provide evidence for either option. If the core is irregularly shaped, it would have an uneven gravitational effect on the spacecraft.
New York Times: The long-contested Yucca Mountain nuclear waste repository, located in Nevada, may be allowed to move forward in light of the recent release of a long-delayed report by the Nuclear Regulatory Commission (NRC), which says the site should be secure for at least a million years. First proposed in 1986 as one of five candidate sites, Yucca Mountain was designated the prime site by Congress a year later. However, over the past several decades, protests by environmentalists and Nevada residents, combined with numerous technical problems, have delayed its opening. Political wrangling has also played a part: While Republicans have worked hard to promote the site, the election in 2008 of President Obama, who vowed to kill the project, has proved a major setback. Meanwhile, the indecision is costing taxpayers money because the Department of Energy has been held liable by the courts for billions of dollars of damages for failure to fulfill its contract for storing the nuclear waste.
Science: For decades, the US has averaged nearly 500 tornados per year. However, a pair of recent studies has revealed that whereas the average number of days with at least one damaging tornado was higher in the 1970s, there are now more days during which multiple tornados occur. Harold Brooks of the National Oceanic and Atmospheric Administration (NOAA) National Severe Storms Laboratory in Norman, Oklahoma, and his colleagues performed one study, and James Elsner of Florida State University in Tallahassee and his colleagues performed the other. Both groups used data from NOAA's National Weather Service, which began tracking tornados in 1953 and recording their scale in the 1970s. The researchers had to discard the F0 rating because of the inconsistency in the reporting of minor tornados, but the remaining data set was found to be relatively unbiased. Although the change in tornado patterns may be tied to changing climate patterns, the actual connections are still not clear. Moisture, land temperatures, and differences between polar and midlatitude temperatures are all root causes of tornado formation, but exactly how they interact and affect each other is unknown.