University of St Andrews

About: University of St Andrews is a education organization based out in St Andrews, Fife, United Kingdom. It is known for research contribution in the topics: Population & Laser. The organization has 16260 authors who have published 43364 publications receiving 1636072 citations. The organization is also known as: St Andrews University & University of St. Andrews.

Dynamic light scattering by non-ergodic media

Abstract: We consider dynamic light scattering (DLS) by non-ergodic media, such as glasses or gels, in which the scattering elements are able only to make limited Brownian excursions about fixed average positions. We point out that, for such media, the time-averaged correlation function of the intensity of scattered light, the quantity obtained from a single DLS measurement, is different from the ensemble-averaged function. An expression for this time-averaged intensity correlation function is derived and its properties and experimental analysis are discussed. Some of the literature on DLS by polymer gels is re-evaluated in the light of these new theoretical predictions.

Experimental violation of Bell's inequality based on phase and momentum.

Abstract: Two-color photon pairs are selected by two double apertures placed to satisfy the phase-matching conditions at a down-conversion crystal. The different wavelengths are superposed at spatially separated points on a beamsplitter and coincident two-photon detections are measured. On adjusting phase plates in the beams before the beamsplitter an apparent nonlocal fourth-order interference effect is seen which violates Bell's inequality by several standard deviations.

Meta) population dynamics of infectious diseases

Abstract: The metapopulation concept provides a very powerful tool for analysing the persistence of spatially-disaggregated populations, in terms of a balance between local extinction and colonization. Exactly the same approach has been developed by epidemiologists, in order to understand patterns of diseases persistence. There is great scope for further cross-fertilization between areas. Recent work on the spatitemporal dynamics of measles illustrates that the large datasets and rich modelling literature on many infectious diseases offer great potential for developing and testing ideas about metapopulations.

Mode-locked quantum-dot lasers

Abstract: Semiconductor lasers are convenient and compact sources of light, offering highly efficient operation, direct electrical control and integration opportunities. In this review we describe how semiconductor quantum-dot structures can provide an efficient means of amplifying and generating ultrafast (of the order of 100 fs), high-power and low-noise optical pulses, with the potential to boost the repetition rate of the pulses to beyond 1 THz. Such device designs are opening up new possibilities in ultrafast science and technology.

Crystal structures of oseltamivir-resistant influenza virus neuraminidase mutants.

Abstract: The potential impact of pandemic influenza makes effective measures to limit the spread and morbidity of virus infection a public health priority. Antiviral drugs are seen as essential requirements for control of initial influenza outbreaks caused by a new virus, and in pre-pandemic plans there is a heavy reliance on drug stockpiles. The principal target for these drugs is a virus surface glycoprotein, neuraminidase, which facilitates the release of nascent virus and thus the spread of infection. Oseltamivir (Tamiflu) and zanamivir (Relenza) are two currently used neuraminidase inhibitors that were developed using knowledge of the enzyme structure. It has been proposed that the closer such inhibitors resemble the natural substrate, the less likely they are to select drug-resistant mutant viruses that retain viability. However, there have been reports of drug-resistant mutant selection in vitro and from infected humans. We report here the enzymatic properties and crystal structures of neuraminidase mutants from H5N1-infected patients that explain the molecular basis of resistance. Our results show that these mutants are resistant to oseltamivir but still strongly inhibited by zanamivir owing to an altered hydrophobic pocket in the active site of the enzyme required for oseltamivir binding. Together with recent reports of the viability and pathogenesis of H5N1 (ref. 7) and H1N1 (ref. 8) viruses with neuraminidases carrying these mutations, our results indicate that it would be prudent for pandemic stockpiles of oseltamivir to be augmented by additional antiviral drugs, including zanamivir.