Ars Technica: A team of researchers from Caltech and the University of Rochester, New York, has created the world’s most sensitive accelerometer. Accelerometers are most familiar in reference to smartphones, which use them to recognize when the device has been rotated. Accelerometers are also used to trigger airbags in cars to inflate during a collision. The new accelerometer, however, is more likely to be used in research labs than in consumer products. The researchers etched a spring-like system out of a silicon nitride membrane, with a mass on the spring of just 10 pg. The resulting system had a resonance frequency of just under 30 kHz and could detect accelerations at a rate of about 15 kHz. That sensitivity is then enhanced further by pairing the mechanical resonator with an optical resonator. Next to the spring the researchers placed a zipper-like structure, which works like a pair of mirrors that bounce light back and forth. Oscillations in the spring stretch the structure, altering the frequency of the light in the optical resonator. The altered frequency allows for easy detection of the otherwise unnoticeable variations in the physical spring’s frequency. The researchers also showed that the device can detect such tiny accelerations that anything smaller would be undetectable because of quantum fluctuations.
Nature: Deposits of methane trapped in the sea floor could greatly increase the effects of global warming if released through drilling or natural processes. A newly discovered deposit of methane hydrate off the coast of Canada is the shallowest such deposit found to date, at just 290 m below sea level. Above 270 m, gas hydrates—crystalline solids of gas trapped in ice—are unstable. Because the deposit is so close to the boundary level, any warming in the water above the sea floor could cause the crystalline ice formation to melt and release the trapped methane. The newly discovered deposit is relatively small, says Charles Paull of the Monterey Bay Aquarium Research Institute in California, so its release would not have a significant impact on climate. However, the shallowness of the methane provides researchers an opportunity to study the nature of such deposits and the events that occur as they decompose.
Washington Post: A Chinese auto parts manufacturer, Wanxiang America, won the bidding for bankrupt lithium-battery manufacturer A123 Systems, based in Waltham, Massachusetts. Wanxiang will pay $256.6 million for A123’s technology, manufacturing facilities in the US and China, and contracts with utilities and automakers. A123’s government and military contracts, however, will go to a US company, Navitas System, in Woodridge, Illinois. Despite $249 million in grant money from the US Department of Energy, A123 was forced to declare bankruptcy last October after suffering a series of setbacks, including a major battery recall.
Science News: Dating from the period of the Nazca civilization, the famous large-scale drawings in the Peruvian desert have puzzled archaeologists for almost a century. Clive Ruggles of the University of Leicester and Nicholas Saunders of the University of Bristol, both in the UK, believe that at least one of the patterns is a walkable labyrinth. Because the pattern can only be seen clearly from the air, walkers would not have known what path they were taking. The path Ruggles and Saunders examined consists of 15 sharp turns, several large curves around hills, and even a spiral, before ending about 60 m away from where it began. They believe the total walking time would have been only about one hour. The two researchers had to reconstruct parts of the path that had been washed away by rain, and it took four years of fieldwork to piece together a map of the full labyrinthine pattern. Although they don’t know the reason why people would have walked the labyrinth, Ruggles and Saunders point to the lack of damage to the rocks lining the paths as evidence that the paths were well taken care of.