Physics Today Daily Edition

Subscribe to Physics Today Daily Edition feed
Please follow the links to view the content.
Updated: 1 hour 4 min ago

House science chairman’s <em>Wall Street Journal</em> op-ed: “Climate-change religion”

27 April 2015
Representative Lamar Smith answers President Obama’s Earth Day statements with a vigorous attack.

Security flaws revealed in teleoperated surgical robots

27 April 2015
MIT Technology Review: Teleoperated surgical robots allow highly skilled surgeons to operate remotely on patients that they would not otherwise be able to reach easily. The number of such robots is growing every year. Although there have been no recorded incidents in which machines malfunctioned because of problems with the fiber-optic networks connecting the surgeon to the machine, Tamara Bonaci of the University of Washington in Seattle and her colleagues have now demonstrated a variety of potential security vulnerabilities. They attempted to hack a surgical robot system, developed at the University of Washington, that makes use of public, unencrypted communication systems. In their attacks, they were able to disrupt the signals transmitted by the user, which affected the robot's movements either subtly or significantly. They were also able to trigger the robot's built-in stop functionality, designed to prevent dangerous movements, in such a way that they could completely prevent the robot from being available for use. Bonaci's team then applied encryption to the robot's communication system. Although the encryption reduced the effectiveness of several of the attacks, it was not foolproof against all hacks.

Silk may be green alternative for optical devices

27 April 2015
Chemical & Engineering News: As a more environmentally friendly alternative to plastic or glass, researchers are developing optical devices, such as lenses, made from the fibers of a silkworm’s cocoon. Vamsi Yadavilli of Virginia Commonwealth University and colleagues used photolithography to create two simple optical devices: a Fresnel zone plate and an iridescent pattern. To do so, they applied photoreactive acrylates to silk proteins to make them light sensitive, coated a surface with them, and shined UV light on them through a patterned mask. So far, the researchers have been able to create features 1 μm in size, but they are working to improve the resolution.

Liquid mercury found in Teotihuacan pyramid

27 April 2015
Guardian: Archaeologists excavating the third largest pyramid in the ancient Mesoamerican city of Teotihuacan have come across a large reservoir of liquid mercury in a newly discovered chamber. Led by Sergio Gómez, the team has spent the last six years clearing a tunnel discovered in the Pyramid of the Feathered Serpent in 2003. In November 2014, they announced that three rooms had been found at the end of the 300-ft (91-m) passageway. The presence of liquid mercury has been reported in other Mesoamerican ruins, but the metallic element had no known practical use for the ancient civilizations. Rather, because of mercury's shimmering, reflective qualities, it may have served a symbolic purpose by representing an underworld river or lake. Gómez says that he believes the discovery could be a sign that the team is close to finding the first royal tomb of the unnamed culture that built the city of Teotihuacan, which was given that name by the later Aztec civilization.

Geological factors combined to make Nepal earthquake particularly deadly

27 April 2015
New York Times: Saturday a magnitude 7.8 earthquake struck to the northwest of Kathmandu, the capital and largest city of Nepal. Thousands of people are known to have died and many more have been reported injured. The quake was particularly devastating because of the tectonics of that region, the local geology, and poor building construction, according to geologists. Nepal lies near the subduction zone between two major tectonic plates. The colliding continental crust created the Himalayas, where 9 of the 10 highest peaks on Earth are located, including the highest—Mount Everest. Because the two land masses are still colliding, the area is prone to earthquakes: In 1934 a magnitude 8.1 quake killed more than 10 000 people. Saturday’s quake occurred at a relatively shallow depth of about nine miles, so it caused greater surface shaking than the 1934 quake. In addition, Kathmandu sits on an ancient lake bed with very soft soil, which further amplified the shaking. Because of the city's high population density and tall, flimsy buildings, the region was more vulnerable than many others that sit near major tectonic faults.

A liquid-crystal Etch A Sketch

27 April 2015
A new laser-based approach makes it simple to add complexity to a liquid crystal’s microstructure.

Wearable electronic skin allows for thought-controlled devices

24 April 2015

New Scientist: An electroencephalogram (EEG) is a common device for measuring brain activity. The technology has also been used to allow a wearer to remotely control a variety of devices. However, the electrodes and wires of a normal EEG make it unwieldy in any but the most controlled conditions. Now, John Rogers of the University of Illinois at Urbana-Champaign and his colleagues have built an EEG into a thin wearable skin that adheres to the body via the van der Waals force and stays in place for up to two weeks. The small patch is worn just behind the ear, and test subjects used it to spell words on a screen in front of them. During the testing, the EEG was still connected to the screen by wires. Rogers's team is working to incorporate wireless connectivity into the device. The researchers' primary goal is to use the device for remote monitoring of medical conditions such as seizures, but they think it could also be used to control a variety of simple devices.

New algorithm improves 3D imaging of complex biomolecules

24 April 2015

MIT Technology Review: Determining the three-dimensional structure of large proteins and other biomolecules has proven difficult. X-ray crystallography works well for molecules that form crystals, but many proteins do not. Now, Marcus Brubaker of the University of Toronto and his colleagues have developed an algorithm that improves a different, previously less effective, imaging technique called electron cryomicroscopy. The technique involves freezing molecules in a thin film and imaging them with transmission electron microscopy. A 3D composite of multiple 2D images of the same molecule can then be constructed. However, the process is time-consuming due to the amount of noise in the images and uncertainty concerning the molecules' orientations when they were imaged. Thanks to two algorithmic innovations, Brubaker's team was able to reduce the imaging time from 2 weeks to just 24 hours. The key improvements were using a machine learning process to sift through the noise in the images to glean the useful information and incorporating importance sampling. The latter relies on the fact that molecules in thin films are usually positioned on their sides, so the algorithm can skip evaluating potential head-on structural orientations.

Electrode implants reveal tinnitus’s manifestation in the brain

24 April 2015
BBC: Tinnitus, the hearing of phantom sounds, may affect a larger area of the human brain than previously thought. The condition is often caused by noise-induced hearing loss or neurological damage. Until now, it was thought that only the hearing pathway was affected. Recently Phillip Gander of the University of Iowa and colleagues were able to gather much more extensive data on the condition by studying a man who had had electrodes planted on his brain to monitor his epilepsy. Through the use of those electrodes, the researchers were able to compare his brain activity when his tinnitus was loud with when it was quiet. They found that brain wave oscillations associated with tinnitus extended far beyond the sections of the brain involved with just hearing. The results are based on only one subject, but the researchers hope to be able to expand their study by gaining access to other patients undergoing similar electrode monitoring.

Radio telescope probes the relationship between cosmic rays and lightning

24 April 2015
Nature: The connection between cosmic rays and thunderstorms is one of many phenomena being investigated by researchers using the Low-Frequency Array (LOFAR), a network of radio antennas and particle detectors spread across five European countries. When cosmic rays hit Earth’s atmosphere, they collide with air molecules and create a shower of electrically charged particles that fall toward the ground. The particles emit radio waves, which can be detected by LOFAR. The researchers noticed that the radio waves fall in orderly patterns with their polarizations neatly aligned when the weather is fair, but they get scrambled when passing near thunderclouds, which consist of layers of positively and negatively charged particles. Although lightning strikes have long been known to provide a form of electrostatic discharge between electrically charged layers in a cloud or between clouds and the ground, what triggers a lightning strike has remained a mystery. Now the LOFAR researchers propose that it may be those cosmic rays raining in from distant space that push the clouds’ electric fields past the tipping point.

A good name rather than great riches

24 April 2015
When and why did solid-state physics become condensed-matter physics?

Thomas A. O’Halloran

24 April 2015

Introducing GSOFT

24 April 2015
A new topical group within the American Physical Society is devoted to the science of soft condensed matter.

Canadian budget proposal emphasizes industry connections

23 April 2015

Nature: Prime Minister Stephen Harper's Conservative government released its budget proposal on 21 April. With modest increases in scientific spending in some areas, the budget continues the Conservative Party's push for more applied research and connections between government, universities, and industry. The budget includes Can$1.33 billion (US$1.09 billion) for new university and hospital research facilities. The money is to be spread out over 6 years beginning in 2017. Many of the increased areas of funding have language specifically related to business and industry. The budget also includes Can$243 million to support Canada's involvement over the next 10 years in the international Thirty Meter Telescope project in Hawaii.

Blocking a certain protein may help prevent blindness

23 April 2015
New Scientist: Age-related macular degeneration, which can eventually lead to blindness, is caused by the abnormal growth of blood vessels in the retina. The weakened vessels can then leak blood, resulting in a hemorrhage. To better understand the processes involved, researchers led by Alain Chédotal of the Institute of Vision in Paris studied the effect of a certain protein, Slit2, on angiogenesis. In experiments conducted on mice, the researchers found that suppressing production of that protein severely reduced the growth of retinal blood vessels. Thus controlling Slit2 might also "block the chaotic development of blood vessels in ocular diseases," according to Chédotal.

Young crust in subduction zone under Cascades produces unusual magma

23 April 2015

Ars Technica: Subduction zones occur where oceanic crust is forced down under continental crust. As the subducted material is pushed toward the mantle, it melts into magma. The amount of water present in the different layers of the rock affects how quickly pockets of magma form. Rock that formed more recently is still warm, which means that it doesn't have to descend as far down into the mantle to start heating up and become dehydrated. Kristina Walowski of the University of Oregon and her colleagues, who have collected minerals from volcanos in the southern region of the Cascades, have confirmed that the subducted plate there is quite young. However, a simulation based on the isotopes in the minerals suggests that the water escaped the rock well before it reached the depth at which magma forms. That led Walowski's team to adjust the model to incorporate water trapped at the bottom layer of the crust. That reservoir of water leads to the formation of magma, and the ratios of other elements in the minerals in the Cascades support the idea that a young oceanic plate is being turned into magma there.

Diving bird runs on water to attract a mate

23 April 2015
Science: Few vertebrates have the ability to defy gravity by running across the surface of water. One species that has managed the feat is the grebe, a type of freshwater diving bird that lives in western North America. For both the western and Clark’s grebes, “rushing” for brief periods of up to seven seconds is used as a courting display. But until recently, researchers did not know exactly how grebes, which can weigh up to about 2 kg, manage to skim across the water. In May 2012 Glenna Clifton of Harvard University and her colleagues spent a month in the field, where they managed to capture high-speed video of the novel display. From that footage, the researchers have determined that the grebes are able to slap their feet rapidly against the water’s surface, as many as 20 times per second. However, the force generated is just half that needed to keep them up. To determine how they generate the rest of the force may require filming under the water.

Measuring ionization potential one atom at a time

23 April 2015
Researchers in Japan have begun probing the atomic physics of elements that can be produced only in minute quantities.

Wisconsin state agency hit with official Florida-like climate-change taboo

23 April 2015
Chicago Tribune headline says, “Daughter of Earth Day founder banned from global warming work in Wisconsin.”

Radio waves detected from individual electrons

22 April 2015
Science: Charged particles traveling through magnetic fields are deflected from their linear paths and instead follow curved trajectories. In doing so, they release radiation. For the first time, researchers have detected the radio waves of a single electron trapped in a spiral in a strong magnetic field. To achieve this, a team of scientists at the University of Washington in Seattle trapped krypton-83 gas produced by the decay of rubidium-83. When trapped, each krypton atom ejected a single electron with a known energy. The electrons were piped into a waveguide cell in the presence of a superconducting magnet. The waveguide was designed to detect electromagnetic radiation between 25 GHz and 27 GHz and transmit the radiation to amplifiers. That allowed the researchers to track the change in frequency of the emissions of individual electrons as they lost energy and spiraled inward. The technique provides researchers with a new method for measuring the energy of electrons in a nondestructive manner. It may also be useful for calculating the mass of neutrinos by using electrons emitted from tritium atoms via beta decay.

Pages