Functional MRI tracks neurotransmitters

Published in MPW, 3 June 2013

Researchers in the US have for the first time used MRI to follow the dynamics of neurotransmitters with molecular precision. They have demonstrated the technique on dopamine, a neurotransmitter that represents processes of reward and motivation in the brain.

Neurotransmitters are the chemicals released at the end of nerve fibres to communicate signals to other nerve fibres in the vicinity. An understanding of their dynamics is important for a more general understanding of brain function, yet they are hard to study. In the past, scientists have resorted to PET, an imaging technique that relies on a radioactive tracer being inserted into the body so that its path can be monitored by emitted gamma rays. But PET can only supply images that are spatially accurate to within a few millimetres and temporally accurate to within a few minutes. […]

The rest of this article is available here.

Winds of change

Published in Physics World, 1 June 2014

The future of the wind industry is looking brighter thanks to a decades-old laser technology. Jon Cartwright explains how laser anemometry could cut the cost of wind energy and boost its share of the world’s energy market

On a coastal plain in Østerild, north Denmark, a gargantuan white structure turns solemnly in the breeze. The latest wind turbine designed by the Danish manufacturer Vestas, the V164, is the biggest yet: at 220m, it is well over twice the height of the Statue of Liberty. And when it was finally tested in Østerild at the beginning of 2014, it also proved to be the world’s most powerful – capable of generating 8 MW of power, enough to provide electricity for some 7500 homes.

The V164 is a symbol of the wind industry’s recent success. Over the past 14 years, the number of installed turbines across the world has risen dramatically, from an output of just 17 MW in 2000 to nearly 320000MW last year – corresponding to about 4% of the world’s total energy demand, according to the Global Wind Energy Council. The boom has been due partly to a surge in the construction of turbines in China, but many smaller countries are also adopting the technology. The UK, for example, generated 10% of its electricity from wind power last year, and it has more offshore wind capacity than the rest of the world combined.

Despite this success, however, the industry has sometimes struggled politically – not least because of a conflict between the cost and location of wind farms. Onshore wind power is relatively cheap: it costs about $87 per megawatt-hour, midway between natural gas ($66/MWh) and coal ($100/MWh), according to a 2013 report by the Energy Information Administration (an agency of the US Department of Energy). Plans for new onshore wind farms often face strong local opposition, however, which is why politicians frequently look offshore for new opportunities. But offshore wind is far more costly: the same 2013 report rates it as more expensive than nearly any other energy technology – renewable or otherwise – at about $222/MWh. The high cost of offshore wind was highlighted in March this year when Scottish and Southern Energy, a UK gas and electric company, announced that it would cut its investment in offshore turbines in order to assure a two-year price freeze for its customers. […]

To read the rest of this article please send an email to for a pdf.

Shrinking electronics to its ultimate limit

Published in Horizon, 16 May 2014

Your laptop, smartphone or tablet could one day see a massive performance boost thanks to scientists who are shrinking electronics down to its ultimate limit: the size of single atoms or molecules.

All modern computing devices get their power from silicon chips, which are filled with transistors, and these transistors are very small – no more than a few dozen nanometres in diameter, or about a thousand times smaller than the width of a human hair.

However, for some people, that’s not small enough. Every two years or so, computer engineers have managed to double the number of transistors on chips in order to make the chips faster – a trend famously noted by the Intel Corporation co-founder Gordon Moore. To keep up with the squeeze, those engineers have had to employ smaller and smaller transistors.

That is why scientists are trying to make transistors and other electronic devices from single atoms and molecules. ‘An entire computer based on molecular electronics would overcome Moore’s Law,’ said physicist Angelika Kühnle at Johannes Gutenberg University in Mainz, Germany. […]

The rest of this article is available here.

Cerenkoscopy tested on human patient

Published in MPW, 7 May 2014

Cerenkoscopy – the monitoring of radiation therapy using Cerenkov radiation – has been tested on a human patient for the first time by scientists in the US. The technique, which involves capturing the flashes of Cerenkov light produced as radiation penetrates tissue, could improve the success of radiotherapy by visualizing radiation dose in real time (Int. J. Radiat. Oncol. Biol. Phys. doi: 10.1016/j.ijrobp.2014.01.046).

Side effects of radiation therapy can only be minimized by carefully regulating radiation doses, but knowing exactly how much radiation enters a body is not easy to assess. Normally, treatment is planned according to computer simulations generated by CT scans, and, at select points during a course of treatment, a patient can also have a detector inserted into them to estimate the amount of incident radiation. Such methods are not foolproof, however: a patient could lose weight, for instance, leading to a relatively high dose. […]

The rest of this article is available here.

‘Solar’ jet fuel made out of thin air

Published in Chemistry World, 2 May 2014

The dream of producing hydrocarbon fuels from carbon dioxide and sunlight is one step closer thanks to chemists in Europe who have made jet fuel from scratch in a solar reactor for the first time. Although the chemists only produced enough kerosene to fill a glass jar, they believe a full-scale solar concentrator could produce 20,000 litres of jet fuel a day.

‘This technology means we might one day produce cleaner and plentiful fuel for planes, cars and other forms of transport,’ said Máire Geoghegan-Quinn, European commissioner for research, innovation and science. ‘This could greatly increase energy security and turn one of the main greenhouse gases responsible for global warming into a useful resource.’ […]

The rest of this article is available here.

Roll over, Boltzmann

Published in Physics World, 1 May 2014

To many physicists, “Tsallis entropy” has been a revolution in statistical mechanics. To others, it is merely a useful fitting technique. Jon Cartwright tries to make sense of this world of disorder

Physics may aim for simplicity, yet the world it describes is a mess. There is disorder wherever we look, from an ice cube melting to the eventual fate of the cosmos. Of course, physicists are well aware of that untidiness and have long used the concept of “entropy” as a measure of disorder. One of the pillars of physical science, entropy can be used to calculate the efficiency of heat engines, the direction of chemical reactions and how information is generated. It even offers an explanation for why time flows forwards, not backwards.

Our definition of entropy is expressed by one of the most famous formulae in physics, and dates back over a century to the work of the Austrian physicist Ludwig Boltzmann and the American chemist J Willard Gibbs. For more than 20 years, however, the Greek- born physicist Constantino Tsallis, who is based at the Brazilian Centre for Physics Research (CBPF) in Rio de Janeiro, has been arguing that entropy is in need of some refinement. The situation, accord- ing to Tsallis, is rather like Newtonian mechanics – a theory that works perfectly until speeds approach that of light, at which point Einstein’s special theory of relativity must take over.

Likewise, says Tsallis, entropy – as defined by Boltzmann and Gibbs – works perfectly, but only within certain limits. If a system is out of equilibrium or its component states depend strongly on one another, he believes an alternative definition should take over. Known as “Tsallis entropy” or “non-additive entropy”, it was first proposed by Tsallis himself in a 1988 paper (J. Stat. Phys. 52 479) that has gone on to become the most cited article written by a scientist (or group of scientists) based in Brazil. So far it has clocked more than 3200 citations, according to the Thomson Reuters Web of Science.

To many who study statistical mechanics, Tsallis entropy makes for a much broader view of how dis- order arises in macroscopic systems. “Tsallis entropy provides a remarkable breakthrough in statistical mechanics, thermodynamics and related areas,” says applied mathematician Thanasis Fokas at the University of Cambridge in the UK. In fact, Fokas goes as far as saying that subsequent work motivated by Tsallis’s discovery has been “a new paradigm in theoretical physics”.

Tsallis entropy has, though, been divisive, with a significant number of physicists believing he has not uncovered anything more general at all. But the voices of these detractors are fast being lost in the crowd of support, with Tsallis’s original paper being applied to everything from magnetic resonance imaging to particle physics. So are these applications exploiting a truly revolutionary theory? Or to put it another way: is Tsallis to Boltzmann and Gibbs what Einstein was to Newton? […]

To read the rest of this article, please email for a pdf.

 

Quantum telescope could make giant mirrors obsolete

Published in Physics World, 29 Apr 2014

Quantum mechanics, rather than a huge telescope, could be the best route to high-resolution space images, according to new research carried out in the UK. If confirmed, a telescope of any size could resolve ever-smaller features of the night sky, allowing astronomers to discover exoplanets and other distant objects much more easily than is currently possible.

The Gran Telescopio Canarias (GTC) telescope on the volcanic island of La Palma in the Canary Islands is a prime example of a massive telescope. With a mirror spanning more than 10 metres, it is the biggest single-aperture optical telescope in the world, and has delivered some of the clearest images ever recorded of distant galaxies, globular clusters and nebulae. But the GTC was not cheap to build: it cost €130 million and took seven years. […]

The rest of this article is available here.

Reusable dosimeter targets radiotherapy

Published in MPW, 28 April 2014

Scientists in the US have invented a reusable dosimeter that could improve the accuracy of radiation delivery during cancer therapy. The dosimeter, which is based on europium-doped potassium chloride, has a high spatial resolution and a tissue-like response (Phys. Med. Biol. 59 1899).

Modern types of radiotherapy, such as intensity-modulated radiation therapy, employ highly complex dose distributions and therefore operate with spatial resolutions under a millimetre. To make sure that the correct amount of radiation is reaching a tumour, and not interfering with surrounding tissue, a radiation oncologist needs to record the incoming radiation with something that mimics tissue’s own response. […]

The rest of this article is available here.

Europe starting work on world’s brightest neutron beam

Published in Horizon, 28 Mar 2014

Europe is starting work on the world’s brightest generator of neutron beams so scientists can peer deep into the hearts of molecules.

Engineers are making final preparations to start building the EUR 1.84 billion European Spallation Source (ESS), in the southern Swedish city of Lund, which will enable scientists to make 3D maps of molecules to understand proteins and complex materials.

Construction work is due to start in the summer on the facility, which will be 30 times brighter than current neutron sources. That’s the difference between candlelight and the flash of a camera. […]

The rest of this article is available here.

Single-atom gates open the door to quantum computing

Published in Physics World, 11 Apr 2014

A quantum-information analogue of the transistor has been unveiled by two independent groups in Germany and the US. Both devices comprise a single atom that can switch the quantum state of a single photon. The results are a major step towards the development of practical quantum computers.

Unlike conventional computers, which store bits of information in definite values of 0 or 1, quantum computers store information in qubits, which are a superposition of both values. When qubits are entangled, any change in one immediately affects changes in the others. Qubits can therefore work in unison to solve certain complex problems much faster than their classical counterparts. […]

The rest of this article is available here.