Tech

Two putative human sex pheromones turn out not to be

No pheromones here FOR several decades biologists have pondered the question of whether men and women produce pheromones. A pheromone is a chemical signal from one animal to another. Often, though not always, such chemicals indicate sexual availability—and when it comes to human mating signals in particular, those looking into the matter have a couple of specific molecules in mind. ...

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Yellow cabs are less likely to crash than blue ones

IN 1907 John D. Hertz, the owner of a taxi firm in Chicago, asked some academics at the University of Chicago to do a piece of research for him. He wanted to know what colour he should paint his cabs in order to make them stand out among the sea of black vehicles that then inhabited American city streets. The ...

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Two races to the Moon are hotting up

The grandest tour THE $30m Google Lunar XPRIZE has had a slow time of it. Set up in 2007, it originally required competitors to land robots on the Moon by 2012. But the interest in returning to the Moon that the prize sought to catalyse did not quickly materialise; faced with a dearth of likely winners, the XPRIZE Foundation was ...

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A machine-learning census of America’s cities

“WOULD it not be of great satisfaction to the king to know, at a designated moment every year, the number of his subjects?” A military engineer by the name of Sébastien le Prestre de Vauban posed this question to Louis XIV in 1686, pitching him the idea of a census. All France’s resources, the wealth and poverty of its towns ...

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A memory chip that can compute

Resistance for change ELECTRONICS has long relied on a division of labour. At the heart of myriad devices, from computers and smartphones to drones and dishwashers, a microprocessor can be found busily crunching data. Switch the power off, though, and this chip will forget everything. Devices therefore contain other, different sorts of chips that work as a memory. That is ...

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The 48 uses of dragon’s blood

MYTHOLOGY is rich with tales of dragons and the magical properties their innards possess. One of the most valuable bits was their blood. Supposedly capable of curing respiratory and digestive disorders, it was widely sought. A new study has provided a factual twist on these fictional medicines. Barney Bishop and Monique van Hoek, at George Mason University in Virginia, report ...

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