Antihydrogen trapped at long last

ATOMS made of antimatter have been trapped for the first time, a feat that will allow us to test whether antimatter responds to the fundamental forces in the same way as regular matter.

Antiparticles are the oppositely charged twins of normal particles. Since matter and antimatter annihilate on contact, antimatter experiments have been limited to using charged antiparticles, which can be corralled within electromagnetic traps.

Several teams have made antihydrogen atoms in the past, but no one had managed to trap them for detailed experiments as they have no net charge. Now an experiment called the Antihydrogen Laser Physics Apparatus(ALPHA) at the CERN particle physics laboratory near Geneva, Switzerland, has finally managed to ensnare atoms of antihydrogen.

ALPHA produced anti-atoms by combining antiprotons from CERN's Antiproton Decelerator ring with positrons emitted by a radioactive isotope of sodium. Where it went one better than previous experiments was in being able to manipulate the anti-atoms magnetically.

Even though anti-atoms are electrically neutral, they do behave like tiny magnets and will respond to a magnetic field. This response is so weak, however, that the anti-atoms have to be moving very slowly if they are to be captured magnetically.

With this in mind, the ALPHA team members tried to create sluggish anti-atoms by bouncing antiprotons at -70 °C off much colder positrons at -230 °C. The antiprotons lost energy in the collisions before some finally combined with the positrons to form antihydrogen. The slowest anti-atoms, at a temperature of just -272.5 °C, then became trapped in a powerful cylinder-shaped magnetic field created by superconducting magnets. The field was then turned off so the antihydrogen could annihilate with normal matter, creating particles that silicon detectors picked up.

After 335 runs of the experiment, mixing around 10 million antiprotons and 700 million positrons, only 38 of the antihydrogen atoms the team made were moving slowly enough to be trapped (Nature, DOI: 10.1038/nature09610). "Our efficiency isn't very good yet," says ALPHA spokesman Jeffrey Hangst of Aarhus University in Denmark. "We make a lot more antihydrogen than we can trap." The team expects their success rate to improve when they start using a new antiproton cooling technique tested earlier this year.

The achievement means researchers can now test whether anti-atoms obey the same physical laws as regular atoms. For example, matter and antimatter should absorb and emit light at the same wavelengths, according to the standard model of particle physics.

"This is an encouraging step towards the goal that I laid out long ago - to confine useful numbers of cold antihydrogen atoms long enough for precise laser spectroscopy," says Gerald Gabrielse of Harvard University. He heads arival experiment at CERN called ATRAP.

If the spectrum of antihydrogen does not match that of ordinary hydrogen, it would leave the standard model in disarray. But any discrepancies could shed light on the long-standing mystery of why the universe is dominated by matter when the big bang should have created equal amounts of matter and antimatter, Gabrielse says.

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first planet from another galaxy

The first planet has been found around a star that seems to be an interloper from another galaxy. Curiously, the star also contains fewer heavy elements – thought to be needed to build planets – than any other planet-hosting star yet discovered.

The planet, which is 1.25 times as massive as Jupiter, lies 2300 light years from Earth and orbits a bloated, ageing star slightly less massive than the sun. Johny Setiawan of the Max Planck Institute for Astronomy in Heidelberg, Germany, and colleagues found the planet by the way its gravity caused its host star to wobble.

The host star, called HIP 13044, is a member of a group of stars called the Helmi stream that have unusual, elongated orbits that bring them far above and below the disc of the galaxy, where the sun and most other Milky Way stars reside. The Helmi stars are thought to be remnants of a small galaxy torn apart by the Milky Way 6 billion to 9 billion years ago.

Dearth of metals

Astronomers announced a possible planet in the nearby Andromeda galaxy in 2009, but its presence has not yet been confirmed. So this makes the newly found planet, called HIP 13044 b, the first to be discovered around a star apparently from another galaxy.

"This cosmic merger has brought an extragalactic planet within our reach," says team member Rainer Klement, also of the Max Planck Institute for Astronomy.

In addition to its unusual origins, the host star is puzzling because it has fewer elements heavier than hydrogen and helium than any other star known to host a planet. Its light spectrum suggests it has just 10 per cent as much iron as the previous record holder, and only 1 per cent as much as the sun.

Planets are thought to form from discs of gas and dust left over from the formation of the parent star. In the prevailing theory of planet formation, called core accretion, dust grains stick together to form rocky worlds, and some of these rocky bodies then grow massive enough to attract surrounding gas, becoming gas giants like Jupiter.

Alternative scenario

Dust is made up of heavy elements, so stars depleted in these elements would have a hard time making planets in this scenario.

This suggests the planet formed another way, says Alan Boss of the Carnegie Institution of Washington, DC, who was not a member of the team.

He proposes an alternative mechanism that he has long championed, in which dense regions of the planet-forming disc simply collapse under their own gravity to form planets. In this scenario, planets could form mainly from gas, without first forming a rocky core.

He adds: "The fact that the star is also likely to have come from somewhere other than the disc of our galaxy makes it even more remarkable, and supports the suspicion that planetary systems are rife in the universe"

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Nanotechnology [nanorobot repairing red blood cells with intracytoplasmic nanomanipulators ]

The idea of nanotechnology was born in 1959 when physicist Richard Feynman gave a lecture exploring the idea of building things at the atomic and molecular scale. He imagined the entire Encyclopaedia Britannica written on the head of a pin.

However, experimental nanotechnology did not come into its own until 1981, when IBM scientists in Zurich, Switzerland, built the first scanning tunnelling microscope (STM). This allows us to see single atoms by scanning a tiny probe over the surface of a silicon crystal. In 1990, IBM scientists discovered how to use an STM to move single xenon atoms around on a nickel surface - in an iconic experiment, with an inspired eye for marketing, they moved 35 atoms to spell out "IBM".

Further techniques have since been developed to capture images at the atomic scale, these include the atomic force microscope (AFM), magnetic resonance imaging (MRI) and the even a kind of modified light microscope.

Other significant advances were made in 1985, when chemists discovered how to create a soccer-ball-shaped molecule of 60 carbon atoms, which they called buckminsterfullerene (also known as C₆₀ or buckyballs). And in 1991, tiny, super-strong rolls of carbon atoms known as carbon nanotubes were created. These are six times lighter, yet 100 times stronger than steel.

Both materials have important applications as nanoscale building blocks. Nanotubes have been made into fibres, long threads and fabrics, and used to create tough plastics, computer chips, toxic gas detectors, and numerous other novel materials. The far future might even see the unique properties of nanotubes harnessed to build a space elevator.

More recently, scientists working on the nanoscale have created a multitude of other nanoscale components and devices, including:

Tiny transistors, superconducting quantum dots, nanodiodes, nanosensors,molecular pistons, supercapacitors, "biomolecular" motors, chemical motors,a nano train set, nanoscale elevators, a DNA nanowalking robot,nanothermometers, nano containers, the beginnings of a miniature chemistry set, nano-Velcro, nanotweezers, nano weighing scales, a nano abacus, a nano guitar, a nanoscale fountain pen, and even a nanosized soldering iron

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Whip-tailed bacteria could 'tweet' to nanobots

Injecting bacteria into the bloodstream might sound like a health risk, but those propelled by a whirling helical tail, or flagellum, could one day be used to send messages between cancer-fighting nanobots.

Maria Gregori and Ignacio Llatser at the Polytechnic University of Catalonia in Barcelona, Spain, envision a future in which nanobots in the body sense tumour cells and release anticancer drugs to fight them. But one machine can't defeat a tumour single-handedly; it needs some way of telling the others to swarm on the target.

Radio signals won't travel through a liquid, and chemical forms of communication using pheromones or calcium ions work only across large or microscopic distances. On the scale of a few millimetres – the distance from one blood vessel to another – there is no way to transmit information reliably.

So the pair came up with the idea of using bacteria with flagella, in this case a non-pathogenic strain of E. coli, to send the information. The idea is to encode a message in a DNA sequence that is inserted into each bacterium's cytoplasm. Each nanobot would contain bacteria inscribed with every message that could be needed

When a nanobot encounters a tumour, it would release the correctly encoded bacteria. These would then swim towards other nanobots, attracted by the nutrients stored there. Once there, the encoded DNA sequence binds with chemical receptors and its message – telling it where to swarm or to release its drugs – is acted upon.

Six minute transfer

In a computer simulation, the pair found bacteria that had flagella took about 6 minutes to traverse a distance of 1 millimetre from a transmitting to a receiving nanobot. They used an encoding scheme that enabled them to encode up to 300,000 DNA base pairs – or 600 kilobits of information.

"That's a bandwidth of 1.7 kilobits per second. It's not high, but for the biomedical applications we envisage it should be [fast] enough," Llatser says.

Others need convincing, however. "These are just simulation results. Everything is possible in simulation," says Andrew Adamatzky of the unconventional computing department at the University of the West of England in Bristol, UK.

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This new robot arm - or should that be trunk?

This new robot arm - or should that be trunk? - from Festo of Denkendorf, Germany, is nothing if not graceful and flexible. But the firm says it also addresses the safety fears that have thus far kept industrial-scale robots and humans some distance apart.

Making robots safe for human interaction is one of the biggest drives in robotics research. Without smart sensing skins that keep the motion of lightweight limbs and motors from injuring people, experts say there will be no personal robotics revolution - robots will instead remain in their industrial safety cages, welding and spraying cars.

Not so, says Festo. Alongside the Fraunhofer Institute for Manufacturing Engineering and Automation in Stuttgart, it turned to 3D printing technology to make soft, compliant lightweight trunk segments that can nevertheless be steered by strong, pneumatically-powered artificial muscles hidden deep within.

Festo says its elephant's trunk-inspired limb, dubbed the Bionic Handling Assistant, is peppered with resistance sensors that limit its extension when it senses contact - potentially making it safe for anyone to use and interact with.

At the end of the "trunk", Festo has placed a novel gripper with three fin-shaped fingers comprised of collapsible compartments. As the outermost ends of these digits wrap around an object, they collapse and trap the object - so very little force is needed to grasp it, and the risk of injury is reduced.

"We are currently developing three sizes for gripping different types of objects - from hazelnuts to grapefruit. Test customers are already using the FinGripper in their production lines," says Festo on its website.

Despite its futuristic appearance, Festo's isn't the only odd robot arm in development. A European-wide team has developed something similarly flexible - but here the inspiration came from an octopus's limb. Instead of pneumatics, the EU team wants to drive their arm with "electroactive polymers" - smart plastics that bend when a voltage is applied.

Festo's decision to seek inspiration from a lumbering mammal marks a departure: it has previously created the most graceful of robotic penguins, jellyfish and manta rays.

And another German team has created the AirFish: an airship that wags its tail like a rainbow trout.

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