Physics Today Daily Edition
Los Angeles Times: The US Environmental Protection Agency is proposing to reduce the federal standard for ground-level ozone. The EPA is required by the Clean Air Act to review the standard every five years. California, which has 16 areas that don’t meet the current ozone limit, will be particularly hard pressed if it is lowered. "We're going to need to have zero or near-zero emissions across the entire economy,” said Sam Atwood, a spokesman for the South Coast Air Quality Management District. Although industry representatives and Republican members of Congress insist that lowering the environmental limit will damage the economy, Janice Nolen, assistant vice president of national policy at the American Lung Association, claims just the opposite: “Since the 1970s, we've reduced major air pollutants by 70% and the economy has more than doubled."
New Scientist: According to a recent paper published in Precambrian Research, both the average rate of continental collisions and the average speed with which the continents change latitude have doubled over the past 2 billion years. Kent Condie of the New Mexico Institute of Mining and Technology and colleagues based their findings on two sets of data: the timing and locations of mountain-range formation and average plate velocities based on magnetic data from volcanic rocks. The researchers think the acceleration may be due to the amount of water in Earth’s mantle, which has recently been found to be much vaster than previously thought. As a result, the mantle may becoming runnier, which could speed up the rock flow. However, the work is considered controversial because it contradicts a previous study that says plate motion has been slowing for the past 1.2 billion years due to the cooling of Earth’s core and mantle.
BBC: Type Ia supernovae have long been thought to be caused when a white dwarf gains enough mass to push it over the Chandrasekhar limit. White dwarfs are the remains of stars that have burned through most of their light elements and have a core of carbon and oxygen that is no longer undergoing fusion. If they steal enough material from a companion star, or merge with another white dwarf, the extra mass compresses the core and causes the heavier elements there to fuse. The sudden release of energy causes the star to explode into a supernova. Although the theory has been widely accepted for decades, a supernova detected on 21 January 2014 has provided the first confirmation that a white dwarf is the source of type Ia supernovae. When a white dwarf’s carbon and oxygen fuse, they create a radioactive isotope of nickel that decays into radioactive cobalt that then decays to stable iron. Observations of the supernova using the European Space Agency’s INTEGRAL spacecraft revealed the signature gamma-ray emissions associated with the cobalt isotope’s decay. The emissions also closely matched the model of a white dwarf explosion. However, there is still not enough information to determine whether it was a white dwarf drawing material from a companion or a collision of two white dwarfs that caused the supernova.
New Scientist: To probe space and time at the very smallest scales, researchers at Fermilab have built a holographic interferometer, or holometer. At the quantum level, matter and energy behave more like waves than particles. The researchers propose that a similar concept may apply to space and time. Their device consists of two 40-meter-long tubes fitted with mirrors through which they shine powerful lasers. If both sets of mirrors are seen to change position as much as a billionth of a billionth of a meter, it could indicate the existence of fluctuations in the fabric of space. If such a spacetime jitter exists, it would present another explanation of why the universe is accelerating besides the current one involving dark energy.
NPR: As the most severe Ebola epidemic ever unfolds in West Africa, some researchers are studying it through the use of computer simulations. The goal is to see how the outbreak might spread and which public health measures could prove most effective in containing it. The effort is complicated by a number of factors, including the uncertainty in the total number of dead and infected people, how many infected people stay at home rather than go to hospitals, and how burial practices can spread the infection. Although the situation is too complex for computer models to come up with definitive answers on how many people will ultimately die and exactly when the epidemic will end, they do underscore the need to act quickly before the Ebola outbreak becomes too large to contain.
Climate Progress: Among the developed countries of the world, Germany is proving to be very successful at making the switch to renewable energy sources for its electricity production. That effort was reflected in the first half of 2014, when the country managed to generate one-third of its electrical power from renewables. That is a remarkable accomplishment in view of the fact that most renewables are inherently intermittent: The Sun only shines during the day, and the wind doesn’t always blow. Moreover, Germany's electrical power grid has proven to be very reliable: Since 2008 the average number of minutes that electricity was lost per customer each year has been less than 16—far less than in any other country in Europe or the US. However, the switch has not come without a price: Germans pay more for their electricity. Regardless, the country remains committed to getting 80% of its power from renewables by 2050.
BBC: Researchers have built a swarm of more than 1000 small robots that can shuffle around on three spindly legs to form two-dimensional shapes. Although the 3-cm-sized robots are fed the same computer program, they modify their movements based on what their neighbors are doing. Modeled on the swarm behavior of living organisms such as ants and birds, the so-called Kilobots could one day be used to develop self-assembling tools and structures. The tiny robots are not fast, however: Each shape can take 6 to 12 hours. "Actually watching the experiment run is like watching paint dry,” says Michael Rubenstein of Harvard University, coauthor of the group’s study published in Science.
Telegraph: NASA’s Stardust spacecraft was launched 15 years ago to collect dust samples from the coma of comet Wild 2 and from the outer reaches of space. Fitted with collectors made of a silica-based aerogel, Stardust returned to Earth in 2006 with at least a million particles in separate sets of detectors. One set was open when the craft passed through Wild 2 and then closed, the other closed through the comet's passage and kept open in a region of space suspected to have interstellar particles. To help sort the vast amounts of data, NASA turned to crowdsourcing, in which citizen scientists used their home computers to scan the collectors for the tracks left as particles hit the aerogel and became embedded. Scientists say that seven of the particles in the second set may be interstellar dust from outside our solar system.
MIT Technology Review: Being made of plastic, organic LEDs are intrinsically flexible. Although OLEDs could be used for displays that can be bent or rolled, it's challenging to protect the material from the few molecules of oxygen or water vapor that suffice to degrade performance. Kateeva, a startup in Menlo Park, California, has devised a solution to the protection problem. By using inkjet technology, the company can coat OLED displays faster and more cheaply than can current processes. Meanwhile, another startup, Canatu of Helsinki, Finland, has resolved a problem that besets flexible touch-sensitive displays. The flat, rigid screens of tablet computers and smartphones rely on tin-doped indium oxide, which is too brittle for use on a flexible screen. For its displays, Canatu replaces the oxide with a thin, flexible film covered with a layer of carbon nanobuds—that is, carbon nanotubes topped with spheres of carbon atoms.
New Scientist: Asteroids are agglomerations of rubble. The smallest have so little gravity that if they were to spin with a period shorter than 2.2 hours, they would fly apart. That limit, derived in 1996 by Alan Harris of the Space Science Institute in Boulder, Colorado, has been breached by a 1.1-kilometer-wide near-Earth asteroid known as (29075) 1950 DA. Ben Rozitis of the University of Tennessee and his collaborators argue in a paper published this week in Nature that a type of weak intermolecular interaction known as the van der Waals force holds 1950 DA together. Although the asteroid poses no threat to Earth, its integrity remains weak. If such an asteroid were on target to hit Earth, deflecting it would have to be done in such a way as to avoid breaking it up and creating a swarm of smaller, yet still deadly fragments that continue toward our planet.
Nature: When midges swarm, they do not execute the dramatic collective swoops and turns of flocks of starlings or schools of fish. Nevertheless, by tightly confining their individual flight patterns, the small flying insects do exhibit collective, self-organized behavior. Nicholas Ouellette and James Puckett of Yale University used high-speed video cameras to investigate the statistics of swarming. In a paper published this week in Journal of the Royal Society Interface, the pair reports that just 10 midges are needed to trigger the onset of self-organized behavior. Their results will constrain generic models that seek to mimic swarming based on interactions among the swarm's members.