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Bacterial hairs behave just like electrical wires
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Roy Hsu/Corbis
THANKS to a rare genetic mutation, a handful of people have no fingerprints. That’s not the implausible premise of a crime story but a real condition, more notable for causing confusion at border control than for baffling detectives. Now, geneticists have identified a mutation that may cause it. Fingerprints form halfway through a normal pregnancy. Every individual has a unique set – even identical twins – making them an ideal way to establish identity. The biological function of fingerprints remains a matter of controversy. It has long been thought that the ridges improve grip, but a recent study suggests they actually reduce friction between skin and a surface. But not in people with adermatoglyphia – a lack of fingerprints – which has been diagnosed in only five families worldwide. Eli Sprecher at Tel Aviv University, Israel, studied three generations in one of the families and found that everyone with the condition shared a mutation in the gene SMARCAD1 (The American Journal of Human Genetics, DOI: 10.1016/j.ajhg.2011.07.004). That is unlikely to help them grow fingerprints, but Sprecher says studying this and other new genes “may lead to treatments for more common conditions”.
Optical cloaks hide objects in broad daylight JAMES BOND may have to up his game. Cloaking materials can now hide tiny microphones placed on a wall – and they will do the job at all visible wavelengths. Optical cloaks can hide a freefloating object by bending light all the way around it, but only at specific wavelengths. They are usually made of synthetic metamaterials, which have a structure on a scale smaller than the wavelength of light they are meant to deflect. Bumps or objects on a floor or wall are relatively easy to hide,
since merely changing the angle at which light bounces off them can make the surface look flat. Previously, such “carpet cloaking” had only been achieved at infrared and microwave wavelengths. Now two different cloak designs have managed to conceal bumps over the full visible spectrum. Chris Gladden and Majid Gharghi of the University of California, Berkeley, etched holes into a thin layer of silicon nitride. Varying the diameter of the holes between 20 and 65 nanometres – smaller than the wavelengths of visible
light – changed the way the layer refracted light, allowing it to cloak a small bump (Nano Letters, DOI: 10.1021/nl201189z). Earlier this year, Baile Zhang and colleagues at the SingaporeMIT Alliance for Research and Technology achieved a similar effect with light whose electric field is lined up in one direction. The team aligned calcite crystals, which have refractive properties that depend on the field’s direction, to hide a 2-millimetre-high bump (Physical Review Letters, DOI: 10.1103/PhysRevLett.106.033901). DEREK LOVLEY/SPL
Genetic (lack of) fingerprints
Lost the plot? The pill might be of help HORMONAL contraceptives might inadvertently change how the brain functions. In particular, a new study shows that taking the pill alters the way women recall an emotional narrative. Shawn Nielsen of the University of California, Irvine, and her colleagues asked 34 women who were on the pill and 35 who were not taking any hormonal contraceptive to watch a slide show depicting either an emotionally charged story or a similar but less emotional tale. A week later, they were asked to write down what they could recall of whichever story they had seen. Both groups recalled more slides of the emotional story, on average, than the neutral one. However, women on the pill remembered the central plot better, whereas those who were not were better at recalling the peripheral details (Neurobiology of Learning and Memory, DOI: 10.1016/j.nlm.2011.06.013). “What we found is a change in the type of information remembered, not necessarily a deficit,” Nielsen says. She adds that memory studies should take into account whether participants are on the pill or not.
Bacterial ‘wires’ an electronic dream THE hair-like threads sticking out of some species of bacteria may hold the secret to more powerful electronics and circuits that will work underwater. Bacteria use pili, as the threads are known, to connect with other bacteria, and they also conduct electricity, says microbiologist Derek Lovley at the University of Massachusetts at Amherst. Lovley’s team sheared some from Geobacter bacteria to study their properties in isolation. They found that conductivity increases with pH and as temperatures fall – just as in
metals. The team then engineered the bacteria to boost pili production, which in turn boosted the overall conductivity of Geobacter biofilms (Nature Nanotechnology, DOI: 10.1038/nnano.2011.119). The applications are numerous, says Lovley’s colleague Mark Tuominen. The small size of pili and their ability to form a lattice could dramatically increase surface area inside capacitors, allowing them to store more electrical charge. What’s more, because the bacteria live in water, they may also help develop waterproof electronics.
13 August 2011 | NewScientist | 17
Roy Hsu/Corbis
THANKS to a rare genetic mutation, a handful of people have no fingerprints. That’s not the implausible premise of a crime story but a real condition, more notable for causing confusion at border control than for baffling detectives. Now, geneticists have identified a mutation that may cause it. Fingerprints form halfway through a normal pregnancy. Every individual has a unique set – even identical twins – making them an ideal way to establish identity. The biological function of fingerprints remains a matter of controversy. It has long been thought that the ridges improve grip, but a recent study suggests they actually reduce friction between skin and a surface. But not in people with adermatoglyphia – a lack of fingerprints – which has been diagnosed in only five families worldwide. Eli Sprecher at Tel Aviv University, Israel, studied three generations in one of the families and found that everyone with the condition shared a mutation in the gene SMARCAD1 (The American Journal of Human Genetics, DOI: 10.1016/j.ajhg.2011.07.004). That is unlikely to help them grow fingerprints, but Sprecher says studying this and other new genes “may lead to treatments for more common conditions”.
Optical cloaks hide objects in broad daylight JAMES BOND may have to up his game. Cloaking materials can now hide tiny microphones placed on a wall – and they will do the job at all visible wavelengths. Optical cloaks can hide a freefloating object by bending light all the way around it, but only at specific wavelengths. They are usually made of synthetic metamaterials, which have a structure on a scale smaller than the wavelength of light they are meant to deflect. Bumps or objects on a floor or wall are relatively easy to hide,
since merely changing the angle at which light bounces off them can make the surface look flat. Previously, such “carpet cloaking” had only been achieved at infrared and microwave wavelengths. Now two different cloak designs have managed to conceal bumps over the full visible spectrum. Chris Gladden and Majid Gharghi of the University of California, Berkeley, etched holes into a thin layer of silicon nitride. Varying the diameter of the holes between 20 and 65 nanometres – smaller than the wavelengths of visible
light – changed the way the layer refracted light, allowing it to cloak a small bump (Nano Letters, DOI: 10.1021/nl201189z). Earlier this year, Baile Zhang and colleagues at the SingaporeMIT Alliance for Research and Technology achieved a similar effect with light whose electric field is lined up in one direction. The team aligned calcite crystals, which have refractive properties that depend on the field’s direction, to hide a 2-millimetre-high bump (Physical Review Letters, DOI: 10.1103/PhysRevLett.106.033901). DEREK LOVLEY/SPL
Genetic (lack of) fingerprints
Lost the plot? The pill might be of help HORMONAL contraceptives might inadvertently change how the brain functions. In particular, a new study shows that taking the pill alters the way women recall an emotional narrative. Shawn Nielsen of the University of California, Irvine, and her colleagues asked 34 women who were on the pill and 35 who were not taking any hormonal contraceptive to watch a slide show depicting either an emotionally charged story or a similar but less emotional tale. A week later, they were asked to write down what they could recall of whichever story they had seen. Both groups recalled more slides of the emotional story, on average, than the neutral one. However, women on the pill remembered the central plot better, whereas those who were not were better at recalling the peripheral details (Neurobiology of Learning and Memory, DOI: 10.1016/j.nlm.2011.06.013). “What we found is a change in the type of information remembered, not necessarily a deficit,” Nielsen says. She adds that memory studies should take into account whether participants are on the pill or not.
Bacterial ‘wires’ an electronic dream THE hair-like threads sticking out of some species of bacteria may hold the secret to more powerful electronics and circuits that will work underwater. Bacteria use pili, as the threads are known, to connect with other bacteria, and they also conduct electricity, says microbiologist Derek Lovley at the University of Massachusetts at Amherst. Lovley’s team sheared some from Geobacter bacteria to study their properties in isolation. They found that conductivity increases with pH and as temperatures fall – just as in
metals. The team then engineered the bacteria to boost pili production, which in turn boosted the overall conductivity of Geobacter biofilms (Nature Nanotechnology, DOI: 10.1038/nnano.2011.119). The applications are numerous, says Lovley’s colleague Mark Tuominen. The small size of pili and their ability to form a lattice could dramatically increase surface area inside capacitors, allowing them to store more electrical charge. What’s more, because the bacteria live in water, they may also help develop waterproof electronics.
13 August 2011 | NewScientist | 17