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Galaxy-mapping telescope gets an eye test from Pluto
IN BRIEF
PAUL STAROSTA/CORBIS
THAT reptile is hot stuff! The tegu can heat its body to as much as 10 °C above its surroundings, making it the first lizard known to do this. But it flicks on its internal heating only for the reproductive season. The Argentine black and white tegu (Salvator merianae) lives across much of South America and grows to between 60 and 90 centimetres long. It was thought to be like most other cold-blooded reptiles and stay the same temperature as its surroundings. Indeed, a team led by Glenn Tattersall of Brock University in Canada and Cleo Leite at the Federal University of São Carlos in Brazil has found that, for much of the year, tegus cool down when the sun sets, reaching a low similar to that of their burrows in the early morning. But during the reproductive season, the lizard’s breathing and heart rate rise and its temperature reaches as much as 10 °C above that of its burrow (Science Advances, doi.org/bb3j). No one knows how the tegu generates its heat. It may secrete a hormone that causes tissue to go into overdrive, producing heat in the process. The discovery may provide a clue to how warm-bloodedness evolved, says Tattersall, because tegu might represent a transition state from cold- to warm-bloodedness.
18 | NewScientist | 30 January 2016
Galaxy-mapping telescope gets an eye test from Pluto GAIA spies, with its gigapixel eye, something beginning with “P”. The European Space Agency launched its Gaia space telescope in December 2013 to map the locations of a billion stars in the Milky Way, but it can also spot objects a little closer to home. Between September 2014 and December 2015 it made nine observations of Pluto and its moon Charon, which have served as a kind of eye test for the probe. When you take an eye exam, the optometrist asks you to distinguish between increasingly
small letters on a chart. The test is designed to determine the resolution of your vision. Having 20/20 vision means you can distinguish two distant objects separated by one-sixtieth of a degree, or an arc minute. Any closer and the objects blur together, appearing as one. Gaia can do the same trick with Pluto and Charon, though it is a little more difficult because both bodies are moving with respect to each other and the telescope, slightly changing their angular separation. In seven observations,
Gaia was able to make out both Pluto and its moon, but saw a single point of light in the others. From these measurements, Gaia team member François Mignard of the Côte d’Azur Observatory in Nice, France, calculated that Gaia’s resolving power is between 0.23 and 0.36 arc seconds – around 200 times better than 20/20 vision. This value should improve once the Gaia team starts detailed analysis of data from binary stars, which also orbit each other. But this is a good warm-up challenge. LEWIS LAB/HARVARD UNIVERSITY
The lizard with an internal radiator
For new stories every day, visit newscientist.com/news
Track your sweat to track your health IF GENIUS is 99 per cent perspiration, then that’s a lot of valuable knowledge coming out of our pores. Capturing this is the idea behind a wearable sensor that measures the molecular make-up of your sweat to provide real-time information about your health. Other devices have used wearable sensors to measure individual components of sweat such as sodium before, but this is just the tip of what’s possible, says Ali Javey at the University of California at Berkeley. Javey’s team combined tiny plastic sensors with flexible silicon-based circuits on a wristband. It measures glucose, lactate, potassium and sodium ions, and can transmit the data via Bluetooth for over an hour before it needs recharging. The ions reveal how hydrated you are, while lactate is a sign of muscle fatigue (Nature, DOI: 10.1038/ nature16521). The sensors can be altered to measure other chemicals, such as the stress hormone cortisol or proteins whose concentrations tell us about the mental state of people with depression, says Javey. “The device could remind someone to take a pill.”
4D-printed flowers bloom and glow THIS delicate, glowing flower could one day help save lives. It’s the latest example of “4D printing” – 3D-printed objects that change shape over time – and it can move in a way that mimics natural processes. Similar materials could help create replacement organs. Previous 4D printing relied on multiple materials, but Jennifer Lewis of Harvard University and her colleagues wanted to simplify the process. “We set out to take a page from nature,” she says. They mixed cellulose fibres from wood pulp with acrylamide hydrogel, a jelly-like substance that expands in
water. When extruded through a 3D printer nozzle, the fibres line up inside the gel, so the printed object can only “grow” lengthways, not sideways. They also developed a way to print curved shapes from criss-crossed designs, to encode bending, twisting and ruffling. To test this, they printed two flowers that curl their petals in different directions when exposed to water. They also added a fluorescent dye, making the flower easier to see and giving it a pleasant glow (Nature Materials, DOI: 10.1038/NMAT4544). The team is now exploring possible applications in tissue engineering.
PAUL STAROSTA/CORBIS
THAT reptile is hot stuff! The tegu can heat its body to as much as 10 °C above its surroundings, making it the first lizard known to do this. But it flicks on its internal heating only for the reproductive season. The Argentine black and white tegu (Salvator merianae) lives across much of South America and grows to between 60 and 90 centimetres long. It was thought to be like most other cold-blooded reptiles and stay the same temperature as its surroundings. Indeed, a team led by Glenn Tattersall of Brock University in Canada and Cleo Leite at the Federal University of São Carlos in Brazil has found that, for much of the year, tegus cool down when the sun sets, reaching a low similar to that of their burrows in the early morning. But during the reproductive season, the lizard’s breathing and heart rate rise and its temperature reaches as much as 10 °C above that of its burrow (Science Advances, doi.org/bb3j). No one knows how the tegu generates its heat. It may secrete a hormone that causes tissue to go into overdrive, producing heat in the process. The discovery may provide a clue to how warm-bloodedness evolved, says Tattersall, because tegu might represent a transition state from cold- to warm-bloodedness.
18 | NewScientist | 30 January 2016
Galaxy-mapping telescope gets an eye test from Pluto GAIA spies, with its gigapixel eye, something beginning with “P”. The European Space Agency launched its Gaia space telescope in December 2013 to map the locations of a billion stars in the Milky Way, but it can also spot objects a little closer to home. Between September 2014 and December 2015 it made nine observations of Pluto and its moon Charon, which have served as a kind of eye test for the probe. When you take an eye exam, the optometrist asks you to distinguish between increasingly
small letters on a chart. The test is designed to determine the resolution of your vision. Having 20/20 vision means you can distinguish two distant objects separated by one-sixtieth of a degree, or an arc minute. Any closer and the objects blur together, appearing as one. Gaia can do the same trick with Pluto and Charon, though it is a little more difficult because both bodies are moving with respect to each other and the telescope, slightly changing their angular separation. In seven observations,
Gaia was able to make out both Pluto and its moon, but saw a single point of light in the others. From these measurements, Gaia team member François Mignard of the Côte d’Azur Observatory in Nice, France, calculated that Gaia’s resolving power is between 0.23 and 0.36 arc seconds – around 200 times better than 20/20 vision. This value should improve once the Gaia team starts detailed analysis of data from binary stars, which also orbit each other. But this is a good warm-up challenge. LEWIS LAB/HARVARD UNIVERSITY
The lizard with an internal radiator
For new stories every day, visit newscientist.com/news
Track your sweat to track your health IF GENIUS is 99 per cent perspiration, then that’s a lot of valuable knowledge coming out of our pores. Capturing this is the idea behind a wearable sensor that measures the molecular make-up of your sweat to provide real-time information about your health. Other devices have used wearable sensors to measure individual components of sweat such as sodium before, but this is just the tip of what’s possible, says Ali Javey at the University of California at Berkeley. Javey’s team combined tiny plastic sensors with flexible silicon-based circuits on a wristband. It measures glucose, lactate, potassium and sodium ions, and can transmit the data via Bluetooth for over an hour before it needs recharging. The ions reveal how hydrated you are, while lactate is a sign of muscle fatigue (Nature, DOI: 10.1038/ nature16521). The sensors can be altered to measure other chemicals, such as the stress hormone cortisol or proteins whose concentrations tell us about the mental state of people with depression, says Javey. “The device could remind someone to take a pill.”
4D-printed flowers bloom and glow THIS delicate, glowing flower could one day help save lives. It’s the latest example of “4D printing” – 3D-printed objects that change shape over time – and it can move in a way that mimics natural processes. Similar materials could help create replacement organs. Previous 4D printing relied on multiple materials, but Jennifer Lewis of Harvard University and her colleagues wanted to simplify the process. “We set out to take a page from nature,” she says. They mixed cellulose fibres from wood pulp with acrylamide hydrogel, a jelly-like substance that expands in
water. When extruded through a 3D printer nozzle, the fibres line up inside the gel, so the printed object can only “grow” lengthways, not sideways. They also developed a way to print curved shapes from criss-crossed designs, to encode bending, twisting and ruffling. To test this, they printed two flowers that curl their petals in different directions when exposed to water. They also added a fluorescent dye, making the flower easier to see and giving it a pleasant glow (Nature Materials, DOI: 10.1038/NMAT4544). The team is now exploring possible applications in tissue engineering.