Physics Today Daily Edition
New Scientist: Asteroids and comets more than 1 km across could devastate Earth if they were to hit the planet. However, Desireé Cotto-Figueroa of Arizona State University in Tempe and her colleagues say that we may not have as much to worry about from asteroids as we thought. Cotto-Figueroa's team tested centimeter-sized cubes from meteorites recovered on the ground. By crushing the samples, the researchers found that the asteroids were nearly as brittle as concrete, which means they are much weaker than most Earth rocks. The researchers extrapolated their measurements of the samples up to much larger scales to calculate the break-up rate for different sizes and types of meteorites. The calculations suggest that rocky asteroids are much more likely to break apart in Earth's atmosphere and turn into a spray of fireballs instead of remaining whole and creating large impacts.
Economist: Each year in the US alone, more than 3500 people—primarily children—swallow button-cell batteries, which can burn holes in the stomach. Removing the batteries generally requires surgery. Now Daniela Rus and Shuhei Miyashita of MIT have developed a magnet-containing robot that can be placed inside a capsule and swallowed. Once the capsule dissolves, the robot unfolds itself and can be moved via magnetic fields from outside the body. After the robot latches onto the battery, the robot tows its haul to the intestine, from which the battery and robot are later excreted. A second robot can then be swallowed and moved to the location where the battery was found to deliver medication that speeds healing of any burns incurred. The team, which tested the robots in a transparent artificial stomach system, now plans to try them out on live pigs, a procedure that will require additional imaging systems to locate the battery and maneuver the robots.
Nature: In the US, the average yearly salary for a postdoc is about $45 000, and many postdocs work much more than 40 hours per week. A new rule finalized by the US Department of Labor, which takes effect on 1 December, will make overtime pay mandatory for many postdoctoral researchers who make less than $47 476 per year. In the US, overtime pay is 1.5 times the normal hourly wage; that rate is triggered when a worker exceeds 40 hours at a single job in a week. Many institutions and funders of postdoc positions will likely opt to increase salaries above the minimum level. However, other positions may get eliminated to compensate. The overtime rule does not apply to postdoctoral positions for which the primary duty is teaching, which means that many humanities postdocs will not benefit.
Nature: Online preprint servers, such as arXiv, allow researchers to publicly share their papers prior to peer review. The sites are growing in popularity because they provide free access to cutting-edge research, albeit in draft form. Journal publisher Elsevier, which has tried unsuccessfully to establish its own preprint server, has now purchased the Social Science Research Network, one of the most popular preprint servers for economics, law, and the social sciences. The move appears to be part of the publisher's larger effort to broaden its services in order to increase web traffic and protect its subscription-based journals.