Dark matter ‘no result’ comes under fire

Physics WorldJon Cartwright

Published in Physics World, 6 May 2010

A war of words has broken out in the dark-matter community over a report posted on the arXiv preprint server earlier this week. The preprint from the XENON100 collaboration poured cold water on claims that dark matter has been detected by two other experiments – but now the report itself has been attacked by other researchers in the field.

On Monday the XENON100 collaboration published an analysis of the first experimental results from its dark-matter detector. It reported no evidence of dark matter, the substance thought to constitute over 80% of mass in the universe. The experiment covered a similar parameter range as dark-matter searches DAMA and CoGeNT, which have previously claimed possible evidence for dark matter. As a result, the XENON100 team concluded that both the DAMA and CoGeNT evidence could be excluded. […]

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AIDS contrarian ignored warnings of scientific misconduct

NatureJon Cartwright

Published in Nature, 4 May 2010

A controversial scientist who is under investigation at the University of California, Berkeley, for making false claims in a paper and failing to declare a colleague’s alleged conflict of interest ignored an earlier warning that he could face misconduct charges if the paper was published.

Earlier this month, molecular and cell biologist Peter Duesberg told the ScienceInsider policy blog that the publication of his paper in the journal Medical Hypotheses prompted two letters of complaint to Berkeley. After receiving the letters, the institution opened a misconduct investigation.

But Duesberg had earlier submitted the paper for publication in the Journal of Acquired Immune Deficiency Syndromes (JAIDS), and a review of the paper, seen by Nature, explicitly warns Duesberg that “cherry-picking” of results and a co-author’s “obvious conflict of interest” could lead to misconduct charges if the paper were to be published. Despite the warnings, Duesberg chose to publish the paper in Medical Hypotheses, which does not peer review submissions. […]

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Model gives insight into HIV vaccines

Physics WorldJon Cartwright

Published in Physics World, 30 Apr 2010

Researchers in China have created what they claim is the most “detailed and realistic” model of HIV to date, and say that it could help in the creation of a vaccine for the deadly virus. However, immunologists warn that the model is yet to catch up with modern clinical trials.

According to the World Health Organization, HIV is one of the world’s biggest health challenges, infecting almost three million people and killing some two million people every year. When a person is infected, HIV enters into the immune system’s crucial T lymphocytes – or T cells – and replicates itself by integrating with the DNA. As a result the cells die and the immune system slowly weakens until it can no longer fight off opportunistic infections, a status classified as AIDS. […]

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Blingtronics

New ScientistJon Cartwright

Published in New Scientist, 27 Apr 2010

It’s like walking into a bank vault. Pass codes secure the doors. The walls and floor are made of reinforced concrete up to 2 metres thick – all built on solid sandstone. The ventilation ducts have automatic shut-offs. Not even cellphone signals can sneak in.

All this might seem fitting given that the place houses diamonds by the hundred. Yet this is no vault. It’s a lab in the Centre for Nanoscience and Quantum Information at the University of Bristol, UK, and the diamonds stored here are each no bigger than a speck of dust. Diamonds this size might not interest a bank robber, but they are turning out to be a physicist’s best friend. […]

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Physicists find a particle accelerator in the sky

Physics WorldJon Cartwright

Published in Physics World, 19 Apr 2010

The first evidence that thunderstorms can function as huge natural particle accelerators has been collected by an international team of researchers.

In a presentation at a meeting of the Royal Astronomical Society in Glasgow last week, Martin Füllekrug of Bath University described how the team detected radio waves coinciding with the appearance of “sprites” – glowing orbs that occasionally flicker into existence above thunderstorms. The radio waves suggest the sprites can accelerate nearby electrons, creating a beam with the same power as a small nuclear power plant. […]

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Randomness no lottery thanks to entangled ions

Physics WorldJon Cartwright

Published in Physics World, 14 Apr 2010

An international team of physicists has created the first system that can produce verifiably random numbers. The technique relies on the inherent uncertainties in quantum mechanics and future versions could help cryptographers to encode information more securely than ever before.

Randomness is central to modern cryptography, which uses long strings of random numbers to form “keys” that can encode and decode sensitive information. Normally such strings are churned out by complex mathematical algorithms, called pseudo random-number generators. But these only approximate random strings, and there is the constant worry that hackers could somehow predict the sequences and gain access to secret files. […]

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Combing makes for neat qubits

Physics WorldJon Cartwright

Published in Physics World, 12 Apr 2010

Physicists in the US have used an optical “frequency comb” to reliably entangle a pair of atomic qubits. The breakthrough bodes well for practicable quantum computing because it allows for simpler manipulation of quantum states than in previous systems.

Quantum computing exploits the innate ambiguities of quantum physics to process certain calculations, such as searching or factorizing, much faster than any of today’s computers. Whereas conventional bits of information can take only the values 0 or 1, a quantum computer’s “qubits” exist in a mixed-up superposition of both. This uncertainty allows any number of qubits, N, to be lumped together – or “entangled”, in quantum speak – to represent a huge 2Nvalues, and then processed in parallel. Or, to put it another way, a quantum computer with just 10 entangled qubits could perform 1024 calculations at once. […]

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Top South African astronomer reinstated

Physics WorldJon Cartwright

Published in Physics World, 1 Apr 2010

One of South Africa’s top astronomers, Phil Charles, has been reinstated as director of the South African Astronomical Observatory (SAAO) having been cleared of sharing confidential information with “outsiders”. Charles had been suspended last month by the National Research Foundation (NRF) of South Africa for “leaking” parts of “confidential foundation documents”. Physics World has learned that these documents concerned proposals to restructure the management of national facilities such as the SAAO, and plans for the site of the operations centre for the forthcoming MeerKAT radio telescope. […]

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Nanotube ‘fuse’ generates power

Chemistry WorldJon Cartwright

Published in Chemistry World, 10 Mar 2010

A fundamentally new type of power generation may be on the horizon thanks to researchers in the US and Korea who have created a nanotube ‘fuse’ that harnesses the energy from chemical reactions. The device converts chemical energy into electrical energy, yet is so small compared with traditional batteries that it opens the door to applications such as floating sensors or new fuel cells.

Carbon nanotubes are known to have unusually high thermal conductivity because of a streamlined way in which packets of heat energy, known as phonons, can travel through the structures. Recent theory shows that if the average distance between phonon collisions matches the physical size of an external exothermic reaction, the phonons should be able to create an accelerating ‘reaction wave’ that quickly spreads down the nanotube. […]

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Hydrocarbon turns superconductor

Chemistry WorldJon Cartwright

Published in Chemistry World, 3 Mar 2010

Researchers in Japan have created the first superconducting material based on a molecule of carbon and hydrogen atoms. Although the superconducting transition occurs at a chilly 18K, the simplicity of the molecule, which consists of just five benzene rings, suggests that it will open the door to other molecules that have higher transition temperatures.

Superconductivity occurs when a material is cooled below a certain transition temperature (Tc) so that its electrical resistance disappears. The first superconductors were pure metals and had Tc values close to absolute zero, but over the past 25 years scientists have begun to discover various ‘high-Tc‘ materials, including cuprates and, most recently, iron arsenides. Ideally, the material would have a Tc at or above room temperature, so that it could be used without cooling in technologies such as lossless power transmission and magnetic levitation. […]

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