Physics Today Daily Edition
Ars Technica: Until recently the oldest fossils on Earth were thought to be contained in the 3.46-billion-year-old Apex chert in Western Australia. But now researchers claim that the microscopic structures found in the rock are not actually fossils of single-celled organisms, as had been previously proposed. In an earlier study, Martin Brasier of Oxford University and his colleagues had argued that the shapes are actually microscopic hydrothermal vents. Now they have used transmission electron microscopy to examine 0.1-µm-thick slices of the chert. If the structures were fossils, they would be surrounded by a wall of carbon-rich material left from the hydrocarbons created by the microorganisms. Instead, Brasier's team found that the structures are filled with mica and that carbon material is distributed throughout. However, the researchers also examined rocks just 20 million years younger than the Apex chert, and the images revealed the expected structure of fossils. So the oldest fossils are still very, very old.
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.
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.
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.
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.