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14 | NewScientist | 10 April 2010 HOW do you create efficient fusion power with fewer radioactive by-products? Start it off by using a laser to generate the equivalent of a seismic wave. Nuclear fusion – creating energy by fusing together light nuclei, such as hydrogen – could begin at the National Ignition Facility (NIF) in California this year. To kick- start the reaction, the plan is to convert energy from high-power laser beams into heat and then X-rays, which will compress a pellet of deuterium and tritium to force the nuclei together. Now Heinrich Hora at the University of New South Wales in Sydney, Australia, and colleagues propose that using the mechanical punch of a laser could be a better approach. They suggest using a “flat-faced” laser pulse; ordinary pulses are pointed. Clock is ticking for undersea volcano A VOLCANO under the Mediterranean could collapse any time, causing a tsunami that would swamp southern Italy. But that timing is impossible to predict. Enzo Boschi of the National Institute for Geophysics and Volcanology in Rome, Italy, used remote sensing to peek at the internal structure of the active Marsili seamount. He found that parts of the steep flanks are made of particularly unstable rock, likely weakened by hot fluids. This means a local earthquake or eruption within Marsili would be sufficient to cause the seamount’s flank to collapse, triggering a tsunami that would strike the coast of southern Italy (Geophysical Research Letters, DOI: 10.1029/2009GL041757). Bill McGuire of University College London says it’s impossible to say when the volcano might erupt, though no one will be surprised if it does. Mysterious ‘night shining’ clouds have a solar controller THE comings and goings of noctilucent or “night shining” clouds in the extreme upper atmosphere may be linked to the sun’s rotation. Noctilucent clouds appear about 80 kilometres above the Earth in each hemisphere’s summer. Their extent and brightness varies over days, weeks and years, but no one knows why. Now Charles Robert of the University of Bremen, Germany, and colleagues think they have an answer. By measuring changes in the light reflected from the clouds, they found that the clouds appear to wax and wane in FLPA IN BRIEF Laser ‘punch’ could boost fusion power It would strike the surface of the fuel rather than penetrating it. This would create a layer of plasma from ionised gas, which would generate a thermonuclear shock wave that ripples through the fuel, promoting compression (Energy & Environmental Science, DOI: 10.1039/b904609g). This process would use less energy, says Hora. What’s more, fewer neutrons would be produced, reducing the number of radioactive isotopes formed. prevalence over a 27-day cycle. As the sun takes 27 days to rotate around its axis, the team suggest a link (Journal of Geophysical Research, DOI: 10.1029/2009jd012359). The researchers suspect that the amount of ultraviolet light Earth receives from the sun explains the link. The sun’s emissions of UV light are not uniform, so as it rotates UV-bright regions move in and out of view of Earth. Increased UV light may break down water molecules in the upper atmosphere, reducing cloud formation, says James Russell of Hampton University in Virginia, who was not involved in the study. However, the sun’s rotation does not explain all the variations seen, says Russell. An observed long-term increase in the number of these clouds may be due in part to the rise in atmospheric carbon dioxide levels, he says. DRUG-resistant tumours might be made vulnerable again. It seems reversible changes to the DNA scaffold might underlie drug resistance in some cancer cells. Jeffrey Settleman of the Massachusetts General Hospital Cancer Center in Charlestown and his colleagues treated tumour cells with cancer drugs. A small subset survived. But placing these “resistant” cells temporarily in a drug-free environment was enough to reverse the resistance: “offspring” of these cells were once again killed by the drugs. Resistance seemed to be due to enzyme-driven changes in the protein scaffold that DNA wraps around. Impeding the enzyme could stop resistance (Cell, DOI: 10.1016/j.cell.2010.02.027). Resistant cancer not a life sentence
