Astronomers at the University of Michigan have, for the first time, directly measured the spin of a distant supermassive black hole.
The high-energy lasers at the National Ignition Facility (NIF), Lawrence Livermore National Laboratory (LLNL) employ exquisite pulse-shaping control to achieve ramp compression pressures to 50 Mbar (15x center of earth pressure) and higher. Ramp compression, contrasted to shock compression, keeps sample temperatures low and allows the study of extreme-density compressed-matter.
Using these capabilities, researchers will gain experimental access to giant-planet interior states and the phase space relevant to exotic crystal structures predicted by modern theory. Early experiments are underway, and in Denver Jon Eggert of LLNL will present some of the first results of extreme-compression experiments, which show the ability to compress solid iron and tantalum to nearly 10 Mbar, carbon to 50 Mbar and the first x-ray diffraction done on NIF.
Unwanted, harmful bacterial cells can be found fouling surfaces everywhere from lifesaving medical devices to toe-jamming pond scum — often in the form of “biofilms,” where they clump together into a slimy, protective surface. In recent years, many researchers have been exploring the physics behind biofilm formation and trying to figure out better ways mitigate the problem or to prevent the fouling films from forming in the first place.
Howard Stone and his colleagues at Princeton are exploring the mechanics and molecular biology of one biofilm-related phenomenon known as streamer formation. When biofilms grow and develop in the presence of fluid flow, they form three-dimensional thread-like offshoots made of polymers and cells. These “streamers” can rapidly clog small channels and quickly foul sanitary surfaces.
One of the basic drivers of evolution is natural selection, the gradual process by which traits take hold or disappear within a population depending on whether or not they confer a competitive advantage. Many of the traits nature selects for can be traced to small, random genetic changes in DNA that alter the dynamics or activity of individual proteins within an organism’s cells and confer some profound survival advantage, like the ability to resist a plague (or a catastrophic disadvantage, like the inability to resist the cold when the ice age cometh).
3-D printing, which can make a solid object of virtually any shape, requires discharging a fine metallic powder or plastic grains and then heating them to the point of melting. Recent studies have shown that putting an obstacle near where the powder or grains are discharged can speed up their flow rate and reduce their probability of jamming by 100 times. But it was not clear whether there was an ideal shape for this flow-improving obstacle.
Now researchers at Osaka University in Japan and Yale University in New Haven, Conn., will report what may be the best way to discharge the grains and powders used in today’s 3-D printers. According to the team’s simulations, using ultra-fine (so-called “monodisperse” or one-sized) grains, and passing them through an orifice with a round obstacle placed at a certain height above it, yields the fastest flow rate.
The work, which will be presented at the APS 2014 March Meeting in Denver, Colo., emerged from the team’s rigorous approach to the problem, said Guo-Jie Gao of Osaka University, who will present this work.