Physics Today Daily Edition
MIT Technology Review: Geckos are known for their ability to adhere to and climb vertical surfaces, including sheer ones like glass. They can do so because of the stickiness of their feet, which is due to the weak electrical attraction called van der Waals forces between the surface and the hair-like setae on gecko footpads. Now researchers led by Mark Cutkosky of Stanford University have developed a human climbing system based on the structure of gecko toes. They attached tiles of an adhesive polymer material called PDMS to a flat, hexagonal, hand-sized gripper backed with a spring to distribute the user's weight across the pad. The system allowed a 70-kg graduate student using two of the grippers to scale a vertical glass wall. So far, however, the climbing system has been tested only on very smooth, clean, flat surfaces. If it is to be put to practical use, such as by construction workers for manipulating huge solar panels or by the military for maneuvering in difficult terrain, it will need to be tested under less ideal conditions, such as on wet or dusty surfaces or in zero gravity.
New York Times: To power its burgeoning economy, India has been pushing to harvest its vast stores of domestic coal. The country has the fifth-largest coal reserves in the world and very little oil or natural gas. However, the coal is twice as polluting as that from Western nations because of its high ash content, and 90% of it comes from strip mines, which are laying waste to the land, water, and air. As a result, smog levels in India have become worse than China’s. Yet the country’s power minister, Piyush Goyal, has pledged to double the use of domestic coal by 2019. Nevertheless, one promising alternative is being pursued by Prime Minister Narendra Modi, who is working to take advantage of another of India’s natural resources: sunlight. Modi is currently pushing for arrays of solar power stations, one of which has already been built by Welspun Energy and is the largest so far in Asia. Whether solar power will keep India from pushing the world past the brink of irreversible climate change remains to be seen.
New Scientist: The network of GPS satellites is nearly 50 000 km in diameter, and each satellite is equipped with a very precise clock. Along with Earth and the rest of the solar system, the GPS network travels through the galaxy at nearly 300 km/s. Andrei Derevianko of the University of Nevada, Reno, and Maxim Pospelov of the Perimeter Institute in Waterloo, Ontario, Canada, argue that this combination of factors makes the network a potentially useful tool for detecting a version of dark matter that may not consist of particles. They propose that dark matter could instead take the form of bends or cracks in the quantum fields that fill the universe. As the solar system passes through one of those cracks, it is possible that the GPS network would detect a variation in the satellites' clocks. The effect would appear as a wave that spreads across the network at the rate of the solar system's movement. Derevianko is now examining 15 years' worth of GPS data to look for such a signal. If his initial search is unsuccessful, he plans to use a network of ground-based atomic clocks currently being built in Europe, which will be even more sensitive than the satellites' clocks.
BBC: Orion is NASA's next-generation manned space capsule that is currently under development. NASA has now signed an agreement with the European Space Agency (ESA) and Airbus, which will work together to create a propulsion and service module for Orion's first full test flight, scheduled for 2017. The module will be developed by Airbus with €390 million ($490 million) in funding from the ESA. NASA will receive the module for free as the ESA's payment in kind for costs the ESA will incur at the International Space Station (ISS) between 2018 and 2020. The service module design was heavily influenced by the ESA's Automated Transfer Vehicle, an unmanned craft currently being used for cargo deliveries to the ISS.
Sydney Morning Herald: Two different groups of researchers have written computer algorithms that can not only pick out individual objects in an image but also describe the entire scene. Both groups, one at Google and the other at Stanford University, were inspired by the neural networks found in the brain. They incorporated two types of networks: one that recognizes images and one that focuses on human language. The researchers trained the artificial-intelligence software by exposing it to images that had descriptive sentences written by humans. Once it learned to pick out patterns in the pictures and descriptions, the researchers tried it out on unfamiliar images. A few of the sentences the software generated included "man in black shirt is playing guitar" and "girl in pink dress is jumping in air." Although still nowhere as accurate as humans, the new system is much more advanced than previous designs. Possible uses include sifting through the billions of images and video online to better catalog and describe them, helping people who are visually impaired to navigate on their own, and monitoring public spaces for illegal activity and alerting the police.
MIT Technology Review: A series of boxes spaced 10 km apart, each of which pairs an IR laser with a directional millimeter-wave radio transmitter, may soon provide wireless internet access. Developed by a company called AOptix, the paired signals each transmit the same data at 2 GB/s, which provides redundancy in case conditions prevent one signal from reaching the next box. Chandra Pusarla, the company's senior vice president of products and technology, says the redundancy guarantees the system will experience only five minutes or less of downtime per year. It is currently undergoing tests by three US wireless carriers and is already being used in Mexico and Nigeria. The technology is useful both in urban environments, where upgrading copper wiring to fiber optics can be costly, and in rural environments, which lack any fiber-optic infrastructure.
Nature: Synthetic biology creates cells that perform logic operations through gene expression. To truly function as computers, those cells need a way to store and access data, but most attempts to achieve that goal have been limited. Now, MIT's Timothy Lu and Fahim Farzadfard have developed a way to use DNA for data storage that can take multiple inputs simultaneously and also keep a record of the accumulation of data over time. The technique, which they call Synthetic Cellular Recorders Integrating Biological Events (SCRIBE), uses a cellular structure known as a retron, which produces single-strand DNA. Lu and Farzadfard created a culture of Escherichia coli in which the retrons responded to the presence of a certain chemical by making the bacteria resistant to antibiotics. The amount of chemical introduced altered the proportion of the bacteria that became resistant. Used that way, the distributed system can store information in a range instead of in a binary state. Lu and Farzadfard also showed that the process is reversible, can be triggered by light, and can "record" the influence of multiple triggers.
New York Times: An electrical device that attaches to the scalp has been shown to slow the growth of brain tumors. Produced by Novocure, a company in the UK, the device consists of four pads that are glued to a patient’s shaved scalp and connected by wires to an operating system and power supply. The system delivers low-intensity, alternating electric fields, called tumor-treating fields, that disrupt cell division. The device is being tested on people with glioblastoma, the most aggressive and malignant type of brain tumor. Early results show that the device extended patients’ lives by three months, and some have survived more than two years. The company next plans to test the device on other types of cancer.
Ars Technica: At 90 km long and 40 km wide, the Markagunt gravity slide in southwest Utah is a manifestation of the largest known landslide on Earth. During the event, which happened about 21 million to 22 million years ago, rocks up to 2.5 km2 and 200 m thick were sent sprawling some 30 km or more. Because the debris field is so large, geologists had thought that it represented a series of individual landslides. In a recent paper published in Geology, however, a group of researchers propose that it was the result of a single, catastrophic event. Over time, they say, volcanic eruptions may have built up a thick wedge of material on top of the clay-rich sedimentary soil, which is structurally weaker. Pressure from the underlying magma then pushed the surface upward, which in turn put stress on the rocks and created faults and fractures. A violent eruption or earthquake could have then set the whole thing in motion. The researchers say the site could provide insights into the potential hazards of such catastrophic collapse.
Science: Since 2005 the US Census Bureau has been conducting an annual 72-question survey to collect housing and demographic information from some 3.5 million people. The survey supplements the decennial census required by the US Constitution. Some members of Congress, however, have objected on the grounds that it poses an unnecessary burden on the public and that the government has no business asking some of the questions. This year the Census Bureau conducted an extensive review of each survey question to determine two criteria: whether a law required the collection of that information and how much time it takes the respondents to answer. As a result, seven questions may get dropped. Social science researchers are unhappy with the proposal to drop question 12, which asks survey takers to identify their college major. The researchers say the information is essential for science and technology policy planning. Next follows a 60-day comment period, during which the statistical community hopes to persuade the Obama administration to reverse the decision.
Los Angeles Times: Astronomers believe that Uranus does not have a warm core and that heating from the Sun drives the formation of the planet's storms. Therefore, storm activity on the planet should peak during equinoxes. But recent observations have revealed a spate of storms at a rate much higher than during the most recent equinox, seven years ago. In August, Imke de Pater of the University of California, Berkeley, and her colleagues, with the help of amateur astronomers and time on the Hubble Space Telescope, spotted eight storms at various altitudes. One of those storms was the brightest ever at the 2.2-µm wavelength. That height puts the storm just below Uranus's tropopause. The researchers are uncertain what could have been driving the storms, but they know that whatever the cause, it will require revising theories about Uranus.
New York Times: Two independent studies ordered by the Pentagon have revealed wide-ranging problems with the management of the US Air Force's and US Navy's nuclear weapons, facilities, and ships. The probes were initiated following the uncovering of academic cheating and several incidents of misbehavior by senior officers. The problems include blast doors that failed to seal and the fact that only a single wrench existed for attaching nuclear warheads to missiles. That one wrench was being shipped via FedEx between the facilities that manage the warhead stockpiles. The emergency repairs and equipment replacements are expected to add several billions of dollars to the Department of Defense's expenses over the next five years. The two studies' investigators—senior Pentagon officers conducted one study, and two retired officers ran the other—visited all the military's nuclear installations and interviewed nearly 1500 personnel. Both investigations found that the problems were rooted in staffing shortages, long-standing cultures of micromanagement that ignored larger issues, personnel management practices that degraded morale and favored test scores over effectiveness, and the age of many of the systems.
BBC: A nearly 50% increase in the number of yearly lightning strikes is expected between 2000 and 2100 if current predictions for global temperatures are correct. A study by David Romps of the University of California, Berkeley, and his colleagues found a new method for relating temperature and lightning by estimating the amount of energy available to drive lightning storms. They found that every 1 °C of temperature increase corresponds to a 12% increase in the number of lightning strikes. Romps's team compared that prediction with data from the US National Lightning Detector Network and found it matched. An increase in lightning strikes will also cause an increase in wildfires, which contribute to air pollution. Lightning also causes chemical reactions in the upper atmosphere that already account for the majority of the nitrogen oxide greenhouse gases present there.