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2 February 2013 | NewScientist | 15 Rogue pulsar has a split personality IT’S not just people that can have fractured personas. Pulsars are prized as cosmic timekeepers for their regular flashes, but now one turns out to behave most erratically: it shines at different frequencies at different times. Pulsars are spinning neutron stars that emit beams of radiation from their magnetic poles. These poles are offset from the star’s axis of rotation, so the beams sweep around like a lighthouse and the star appears to pulse. Pulsars could be useful in detecting gravitational waves, because the timing of flashes should be slightly altered by these ripples in space-time. Now a pulsar called B0943+10 has shattered this reputation for reliability. The star tones down its radio emissions unpredictably while pumping out extra X-rays, resuming its old behaviour a few hours later, found a team led by Wim Hermsen of the Netherlands Institute for Space Research in Utrecht (Science, doi.org/kbk). “This variability has never been seen before,” Hermsen says. Astronomers already disagree over exactly what creates pulsar beams. B0943+10’s quirks just make things worse as they do not fit any of our existing models. Think that massage feels good? Try adding drugs YOU don’t need us to tell you that certain types of touch – massage and stroking – can be pleasurable. Nerves dedicated to creating these feelings have been identified and artificially stimulated in mice, leading to hope that the work could aid the development of drugs that relieve pain or stress. Some nerves rapidly transmit sensations of touch or pain to the brain, but others work much more slowly. These C-tactile fibres, as they are known in humans, are found under hairy skin and respond to stroking. David Anderson at the California Institute of Technology in Pasadena and colleagues used calcium imaging to identify similar bundles of nerves in mice. When the mice were in a special chamber, the team injected them with a chemical that activated these nerves. Afterwards, the mice visited the chamber almost twice as often as they had before, suggesting that they enjoyed the experience and wanted more (Nature, DOI: 10.1038/nature11810). A drug that evokes a similar response in humans could WHO needs the moon? Dung beetles can use the Milky Way to navigate. Back in 2003, Marie Dacke of Lund University in Sweden and colleagues showed that beetles use polarised light from the moon to help them move in a straight line. But the researchers were surprised to find that the insects could stay on course even on a moonless night. To see what else is going on, the team timed beetles crawling from the centre of a cylindrical drum to the edge. The drum was open-topped, so the insects could use the night sky to orientate themselves. On a moonless night, the insects took twice as long as they did under a full moon. And with a cap on that hid the night sky from their view, they needed six times longer, implying that the stars were involved. The team then moved to a planetarium. By switching stars on and off, Dacke identified the guiding light as the Milky Way. It had been assumed that insects could not navigate in this way because their eyes cannot make out individual stars, but using the Milky Way does away with the need for such resolution (Current Biology, doi.org/kbm). By the light of the silvery... Milky Way DACKE ET AL, CURRENT BIOLOGY boost the beneficial effects of skin-to-skin contact such as massage in rehabilitation or for psychiatric conditions, says Johan Wessberg at the University of Gothenburg in Sweden. Interactions involving stroking are common among many mammals, particularly in nurturing, and removing this contact can impair development. “For the first time we are getting a neurological basis for these phenomena,” says Francis McGlone at Liverpool John Moores University in the UK. 3D-printed proof of Archimedes ARCHIMEDES was at the cutting- edge of Ancient Greek technology but he might have increased his ability to engage with ordinary folk had he access to a 3D printer. One of the polymath’s favourite proofs was showing mathematically that a sphere that fits exactly inside a cylinder fills two thirds of its volume. A representation of this was displayed on his tomb. Now, to mark the 2300th anniversary of his birth, Elizabeth Slavkovsky and Oliver Knill of Harvard University have used a 3D printer to create an object of the precise dimensions needed to demonstrate the insight visually. They printed a slightly different version of the proof – a hollow hemisphere supported above a cylinder which contains a cone that takes up one third of the cylinder’s volume (pictured below). Fill the hemisphere with water and it drains into the cylinder, filling it exactly to the brim. Using a hemisphere means you can see the water drain, making it easy to grasp what Archimedes proved (arxiv.org/abs/1301.5027). The pair reckon that 3D printers – which make it easy to create objects based on equations – could transform mathematics education. Slavkovsky has helped students print personalised mathematical objects. “It gave them a tangible thing to consider,” she says. ELIZABETH SLAVKOVSKY & OLIVER KNILL For new stories every day, visit newscientist.com/news
