4 July 2009 | NewScientist | 17

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AN OPTICAL transistor that switches a laser beam on and off, rather than an electric current, could form the building block of future light-based computers.

Vahid Sandoghdar and colleagues at the Swiss Federal Institute of Technology in Zurich suspended a hydrocarbon dye molecule in a crystalline matrix cooled by liquid helium. They then aimed a weak orange laser beam at the molecule, which soaks up most of its energy.

When they zapped the hydrocarbon molecule with a weak green beam it re-radiated orange light (Nature, DOI: 10.1038/nature08134). “That light then constructively interferes with the orange beam and makes it brighter, effectively amplifying it,” says researcher Jaesuk Hwang . The team hopes to use its transistor to build an optical circuit.

Metal to rescue plastic planeTHE midst of the deepest recession

the aviation industry has ever seen is

not the best time to discover that your

revolutionary aircraft design has yet

another serious structural weakness.

But that’s the predicament Boeing

found itself in last week.

The company hopes its 787 airliner

will be the first with a pressurised

fuselage made from lightweight,

fuel-saving carbon-fibre reinforced

plastic (CFRP) composite materials,

rather than aluminium.

But in 2008, the firm found that

the 787’s carbon-fibre “wingbox”, the

internal fuselage structure the wings

attach to, was not strong enough and

needed stiffening with metal spars.

That redesign helped put back the

plane’s first flight by 15 months.

Then last week, other stress tests

on an airframe showed that the plane

needs strengthening at 18 points on

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First steps for an optical computer

either side of the fuselage just above

the area where the wing attaches.

Titanium or aluminium stiffeners are

being developed to strengthen those

“side-of-body” points.

“Data from the test did not match

our computer model,” says Boeing

vice-president Scott Fancher. That

highlights the difficulty of predicting

the behaviour of advanced CFRP

materials being used in very large

structures for the first time.

Boeing says its computer model

will now be modified in the light of

the new data to help its engineers

design the stiffeners. A new date for

the 787’s first flight has not been set.

THREE years after online DVD rental firm Netflix offered a $1 million prize to anyone who could improve its movie recommendation system by 10 per cent, an international team of computer scientists has made the grade.

To take part in the competition, dozens of teams have been training their algorithms using records of the way some 480,000 customers rated 18,000 films. The algorithms are then tested on another data set of customer ratings which are known only to the Netflix judges.

Your taste in movies revealed

Several teams have been closing in on the target. In December 2008, Netflix awarded a $50,000 “progress prize” to a team called BellKor in BigChaos for achieving a 9.44 per cent improvement over the Cinematch system Netflix has been using till now.

That group recently joined forces with four others. On 26 June the combined team, which calls itself BellKor’s Pragmatic Chaos , announced it had achieved a 10.05 per cent improvement.

The prize money isn’t guaranteed yet. The rules of the competition give other competitors 30 days to beat the new figure before the winner can be officially named.

–Not quite ready for take-off–

The increase in uploads to YouTube from cellphones after the launch of Apple’s iPhone 3GS on 19 June Source: Google

400%

R. J. Pittman of Google explains how a huge increase in the number of searches for the

term “Michael Jackson” after the singer’s death was announced led Google News to display

an error message (Official Google Blog, 26 June)

“The spike was so big Google mistook it for an attack”

“The plane needs strengthening at 18 points just above the area where the wing attaches”