Icy river: A man climbs on big chunks of melting ice moving on the Danube River in Belgrade, Serbia. Picture: AFP Source: AFP

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• Greece, Bulgaria battle flooding; 8 dead NEWS.com.au, 8 Feb 2012

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ICE floes up to one metre thick have smashed into hundreds of boats on the River Danube near Belgrade, sinking a floating restaurant.

Barges also broke adrift under the pressure of the ice as it melted and broke up following a rise in temperature at the end of a two-week cold snap that killed hundreds of people across Europe.

“Hundreds of small boats were damaged or sunk, while almost 90 per cent of rafts were moved up to 20 metres downstream,” Zoran Matic of the Belgrade water company said.

Three ice-breakers had been brought in to reduce the pressure on rafts “in order to save what could be saved”, Mr Matic said, adding that at least one raft-restaurant sank.

“The damage is enormous. This is a disaster,” a desperate boat owner told a local radio.

During the cold snap, which brought temperatures well below freezing for days on end, the 2860km Danube, which flows through 10 countries and is vital for transport, power, irrigation, industry and fishing, was nearly wholly blocked by ice from Austria to its mouth on the Black Sea.

Read more: http://www.news.com.au/world/ice-smashes-boats-apart-on-danube/story-fn6sb9br-1226276485901#ixzz1mxtDHBlq

Aussie scientists unveil single-atom transistor

Updated February 20, 2012 15:23:56

Photo: A 3D perspective scanning tunnelling microscope (STM) image of a hydrogenated silicon surface. (supplied: Dr Martin Fuechsle)

A team of Australian physicists has created the world’s first functioning single-atom transistor, which could prove a critical building block toward the development of super-fast computers.

The tiny electronic device, described today in a paper published in the journal Nature Nanotechnology, uses as its active component an individual phosphorus atom patterned between atomic-scale electrodes and electrostatic control gates.
While single-atom devices have been developed before, these had an error of about 10 nanometres in positioning of the atoms, which is large enough to affect functionality.
Professor Michelle Simmons, group leader and director of the ARC Centre for Quantum Computation and Communication at the University of New South Wales (UNSW), says it is the first time “anyone has shown control of a single atom in a substrate with this level of precise accuracy”.
“Several groups have tried this, but if you want to make a practical computer in the long-term you need to be able to put lots of individual atoms in,” she said.
“Then you find the separation between the atoms is quite critical so you need to have atomic precision to do that, so then you can also bring electrodes in to address each of those individual atoms.”

The UNSW team used a scanning tunnelling microscope (STM) to see and manipulate atoms at the surface of the crystal inside an ultra-high vacuum chamber.
Using a lithographic process, they patterned phosphorus atoms into functional devices on the crystal, then covered them with a non-reactive layer of hydrogen.
Hydrogen atoms were removed selectively in precisely defined regions with the super-fine metal tip of the STM.
A controlled chemical reaction then incorporated phosphorus atoms into the silicon surface.
Finally, the structure was encapsulated with a silicon layer and the device contacted electrically using an intricate system of alignment markers on the silicon chip to align metallic connects.
The electronic properties of the device were in excellent agreement with theoretical predictions for a single phosphorus atom transistor.
First author Dr Martin Fueschle says this individual position is very important if you want to use the transistor as a future quantum bit (or qbit).
“If you want to have precise control at this level you need to position the individual atoms with atomic precision with respect to control gates and electrodes,” he said.
The device is also remarkable, says Dr Fuechsle, because its electronic characteristics exactly match theoretical predictions undertaken with Professor Gerhard Klimeck’s group at Purdue University in the United States and Professor Hollenberg’s group at the University of Melbourne, the joint authors on the paper.
The team also believes the use of silicon to encase the transistor increases its potential for future manufacturing.
It is predicted that transistors will reach the single-atom level by about 2020 to keep pace with Moore’s Law, which describes an ongoing trend in computer hardware that sees the number of chip components double every 18 months.
“We really decided 10 years ago to start his program to try and beat that law,” Professor Simmons said.
“So here we are in 2012 and we’ve made a single-atom transistor about 8-10 years ahead of where industry is going to be.”

Topics:computers-and-technology, science-and-technology, australia