JON CARTWRIGHT – Page 26 – & THREE QUARKS EDITORIAL

Quantized vibrations are essential to photosynthesis, say physicists

Physics WorldJon Cartwright22 January, 2014

Published in Physics World, 22 Jan 2014

Physicists in the UK claim to have shown unambiguously that the high efficiency of photosynthesis is driven at least partly by a purely quantum-mechanical phenomenon. Their work could lead to discoveries of other quantum processes in biology, or help in the development of new and better technologies for harvesting solar energy.

Arguably the most important chemical reaction on Earth, photosynthesis allows a plant to harness sunlight by converting carbon dioxide and water into energy-rich carbohydrates. For the most part, this takes place in chlorophyll molecules, which are arranged such that neighbouring molecules have different energy levels. When light shines on one of these molecules, an electron is momentarily excited before passing its energy over to a nearby molecule with a slightly lower energy level. In this way, energy can flow “downhill” from energy level to energy level, via different routes, until it reaches a reaction centre where actual photosynthesis occurs. […]

The rest of this article is available here.

Cerenkov light tracks radiation dose

MPWJon Cartwright20 January, 2014

Published in MPW, 20 Jan 2014

Scientists in the US have demonstrated that Cerenkov light emitted during radiation therapy on a live animal can reveal the radiation dose being administered. The technique could enable doctors to make sure that the correct radiation doses are administered to humans undergoing radiation therapy (J. Biomed. Opt. 18 110504).

It is important to carefully regulate the amount of radiation that a patient receives when undergoing radiation therapy, to minimize the risk of side effects. Unfortunately, knowing exactly how much radiation enters the body is tricky. Normally, treatment is planned according to computer simulations of the body, generated with CT scans. One or two times during a treatment course, a patient can also have a detector inserted into them to estimate the amount of incident radiation. But these methods aren’t foolproof: a patient could lose weight, for instance, leading to a relatively high dose. […]

The rest of this article is available here.

Newer telecoms standard reduces exposure

MPWJon Cartwright13 January, 2014

Published in MPW, 13 Jan 2014

Researchers in Switzerland have found that a mobile-phone communications protocol exposes users to about 100 times less low-frequency electromagnetic fields than its predecessor. The result builds on previous research to show that UMTS offers less overall exposure to electromagnetic fields than GSM (Phys. Med. Biol. 588339).

Characterizing the emission of electromagnetic fields from mobile phones is seen to be an important area of research because of widespread concern that wireless devices can affect human health. Strong radio signals are known to heat tissue, while strong low-frequency fields – generated, for instance, by supply currents or audio speakers – are known to provoke neurones in the brain into firing spontaneously. For these reasons, governments issue strict safety guidelines about the maximum exposure that users should receive. […]

The rest of this article is available here.

Spin revolution

New ScientistJon Cartwright11 January, 2014

Published in New Scientist, 11 Jan 2014

A much misunderstood quantum property is set to turn computing on its head, says Jon Cartwright

ONE foggy day in early December 1943, a giant awoke. Born in an engineering lab in north-west London, Colossus was the world’s first digital, programmable electronic computer – a tower of racks and wires that ate its way through miles of punched-card instructions every hour. Its processing power would enable the Allies to quickly decipher messages from Nazi high command – and help them win the second world war.

Computers have come a long way in the 70 years since, but deep down they work in essentially the same way: by manipulating electrical charge. Guided by its punched cards, Colossus moved charge through thousands of glowing valves. In modern computers, charge passes through millions upon millions of transistors to make the texts, images and sounds that form our digital worlds. It has proved an eminently upscalable approach: the average smartphone today is a million times faster than Colossus, not to mention a hundred thousand times smaller.

But charge is beginning to feel the squeeze. As components have shrunk, they have been handling fewer and fewer moving charges. There is only so far this can go before random charge fluctuations make the operation of the transistors unreliable. “We’re simply running out of electrons,” says Dan Hutcheson of VLSI Research, a company that analyses technology markets. Add to that the effect of the large amounts of heat generated by very many transistors in a small space, and it is clear we are reaching some fundamental barriers. […]

The rest of this article is available here.

Keeping serendipity alive

Physics WorldJon Cartwright1 January, 2014

Published in Physics World, 1 Jan 2014

As lead editor of Physical Review Letters, Pierre Meystre, from the University of Arizona at Tucson, tells Jon Cartwright about the challenges facing one of the most influential physics journals

What is your research background?

My PhD was in quantum optics, which I did at the Swiss Federal Institute of Technology in Lausanne in 1974. After finishing a postdoc in the US in 1977, I then moved to the Max Planck Institute of Quantum Optics in Garching, Germany, where I worked on micromasers and cavity quantum electro dynamics. I then joined the University of Arizona in 1986, where I have been ever since, to work on laser cooling, atom optics and Bose–Einstein condensation. I now work in quantum optomechanics, which is nice because it combines everything together. […]

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Vibrations couple light to graphene

Chemistry WorldJon Cartwright11 December, 2013

Published in Chemistry World, 11 Dec 2013

Two independent groups have shown that light can be effectively turned into surface plasmons in graphene if the carbon sheet is made to vibrate. The proposal could solve the problem of how to generate this electronic phenomenon in graphene, and could one day help integrate optical and electrical data processing.

Optics and electronics are both widely used to carry data in telecoms, but it is currently difficult to switch from one medium to the other without incurring heat losses and time delays. Plasmons – waves of confined electrons in a conductor – could help. In principle, light incident on a conductor can rouse the conduction electrons into a plasmon, which can then be processed by electronic components. […]

The rest of this article is available here.

Micromotors clean polluted water

Chemistry WorldJon Cartwright9 December, 2013

Published in Chemistry World, 9 Dec 2013

Researchers in Germany have invented micromotors that can propel themselves through water while degrading organic pollutants. The micromotors, which run on dilute hydrogen peroxide, could be used to clean up small reservoirs, pipes and other hard to reach places.

Organic pollutants are found in many industrial wastewaters, including those of textile companies, pharmaceutical companies and agriculture. They are an increasing problem, because they are often resistant to environmental degradation and cannot be processed with conventional biological or chemical water treatments. […]

The rest of this article is available here.

What goes on in babies’ brains

Physics WorldJon Cartwright1 December, 2013

Published in Physics World, 1 Dec 2013

How do you map the brain of a very small, very active person? Just ask those scientists working on the Developing Human Connectome project, says Jon Cartwright

Eighty-five billion neurones, and upwards of 100 trillion connections – the adult human brain is the most complex object in the known universe. But how does such a rich neural network grow from a tiny foetus? And how does that growth affect the way our brains ultimately function?

Scientists have a rough picture of how a brain develops in the womb. About three weeks after conception, brain cells begin to form at the tip of the embryo into a tube that will eventually form the spinal cord. This tube then begins to form a brain, where the neurones – brain cells – develop and begin to form contacts with each other. Until the foetus is about 20 weeks old, some quarter of a million cells are growing every minute. […]

The rest of this article is available here.

Super-resolution ultrasound maps the brain

MPWJon Cartwright26 November, 2013

Published in MPW, 26 Nov 2013

Physicists in Canada have overcome an inability of ultrasound to map capillaries and other vessels in the brain by injecting micrometre-sized bubbles into the bloodstream. Although the technique has been demonstrated only on a model brain so far, it promises to be a simple, inexpensive way to provide a complete mapping of a real brain’s vascular networks.

The mapping of blood vessels in the brain is known to be an effective tool in studying diseases such as Alzheimer’s. Current technology, however, makes vascular mapping difficult. CT scans have a resolution of about 400 micrometres, which rules out all but the largest blood vessels. MRI using higher field strengths of 3–7 Tesla can reveal more vessels, but this is a costly process that is rarely available. More common, clinical MRI, on the other hand, has a resolution of 300 micrometres. […]

The rest of this article is available here.

Thousands being interviewed in mobile phone brain cancer study

HorizonJon Cartwright20 November, 2013

Published in Horizon, 20 Nov 2013

Thousands of young people are being interviewed as the EU backs the largest study in the world into the links between mobile phone use and brain cancer in children.

Brain cancer is the most common type of cancer in children, after leukaemia. In the UK alone, some 450 children under the age of 18 are diagnosed with brain tumours every year.

Many people are tempted to blame the spiralling use of mobile phones. A study conducted at the beginning of this decade on behalf of the European Commission’s Directorate-General for Health and Consumers found that more than two-thirds of people in the EU believe their health is affected to some extent by mobile phone masts and mobile phone handsets. […]

The rest of this article is available here.