23 November 2013 | NewScientist | 17

QUANTUM computers won’t be cool for long. Room-temperature atoms in a fragile quantum state have survived for 39 minutes – long enough to perform 2 million calculations if they were part of a quantum computer. That could help make such devices practical.

Instead of storing data as bits that are 1s or 0s, quantum computers have qubits, which can be both at the same time, a state

known as superposition. This could allow them to crunch numbers much more rapidly, but superpositions are delicate so most quantum computers need to be chilled to near absolute zero to work, limiting their use.

So Mike Thewalt of Simon Fraser University in Burnaby, British Columbia, Canada, and his colleagues infused a slab of silicon with phosphorus atoms. Each

Lost dino tail keeps birds on small side

BIRDS are related to T. rex, one of the largest predators ever to stalk the Earth, so why are they so puny by comparison, even those that don’t fly?

Theropod dinosaurs, the ancestor of birds, walked with their legs vertical using their tail for balance. As their progeny evolved to fly, their tails shrank so they had to crouch to balance. This made their femurs stronger, even after some had ceased to fly.

Nicholas Chan at Macquarie University in Sydney compared the length and circumference of fossil femurs in 43 flightless birds to those of 81 theropods. The dino femurs grew longer and wider as body size increased, Chan says. In birds, there was a “distinct plateau”, with length and body mass limited by the need to keep the knee near the centre of gravity. The work was presented at the Society of Vertebrate Paleontology meeting in Los Angeles.

Hunters tamed wolves to kick off dog domestication

IT’S no shaggy dog story. European hunter-gatherers were the first to bring dogs to heel, according to the latest attempt at dating the origins of man’s best friend.

Robert Wayne at the University of California, Los Angeles, and his colleagues looked at mitochondrial DNA from the bones of 18 prehistoric canids (wolves and dogs) from Eurasia, the US and Argentina. They also gathered this DNA from 130 modern wolves and dogs from all over the world. By comparing the DNA, the team worked out how all of the animals related to each other.

They found that modern dogs clustered into four

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Record survival for warm quantum state one’s nucleus has a “spin” that can be up, down or a superposition of the two. Suspecting that electrons whizzing around the phosphorus atoms might help destroy superpositions, the team knocked an electron from each atom.

The resulting superpositions lasted for 3 hours at 4.2 degrees above absolute zero – compared with just 3 minutes in previous super-chilled experiments – and 39 minutes at room temperature (Science, doi.org/p4k).

groups, all with European roots, the oldest of which are between 19,000 and 32,000 years old (Science, doi.org/p4p). It’s likely that the first domestic dogs emerged at that time, says Wayne.

This contradicts previous suggestions that early farmers first domesticated canines, when wolves were attracted to food waste outside their settlements. Agriculture and village life only arrived in Europe about 7500 years ago.

Wayne says wolves may have followed roaming groups of hunter-gatherers to take advantage of the carcasses left after hunts. That would have kept other carnivores at bay, offering a benefit for the hunter-gatherers too. Over time, he claims, the two species became the ultimate odd couple.

HOW slow does your blood flow? A blood tracking technique could help detect tiny but dangerous clots in small veins or the growth of new blood vessels in tumours.

Current ultrasound methods can only measure flow rates down to 10 millimetres per second, while infrared imaging works only for veins less than a millimetre beneath the skin.

Lidai Wang of Washington University in St Louis, Missouri, and his colleagues have now mixed ultrasound and infrared, letting them track flow by watching heat diffuse through blood. The system can sense flow rates down to 0.24 millimetres per second at a tissue depth of 5 millimetres (Physical Review Letters, doi.org/p4v).

Sound method to track your blood

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