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Search Results: 1 - 10 of 405288 matches for " Peter G. R. Smith "
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Fiber and Integrated Waveguide-Based Optical Sensors
Valerio Pruneri,Christos Riziotis,Peter G. R. Smith,Athanasios Vasilakos
Journal of Sensors , 2009, DOI: 10.1155/2009/171748
Abstract:
Detection of C60 in embedded young stellar objects, a Herbig Ae/Be star and an unusual post-AGB star
Kyle R. G. Roberts,Keith T. Smith,Peter J. Sarre
Physics , 2012, DOI: 10.1111/j.1365-2966.2012.20552.x
Abstract: The first detection of the C60 (Buckminsterfullerene) molecule in massive embedded young stellar objects (YSOs) is reported. Observations with Spitzer IRS reveal the presence of C60 in YSOs ISOGAL-P J174639.6-284126 and SSTGC 372630 in the Central Molecular Zone in the Galactic centre, and in a YSO candidate, 2MASS J06314796+0419381, in the Rosette nebula. The first detection of C60 in a Herbig Ae/Be star, HD 97300, is also reported. These observations extend the range of astrophysical environments in which C60 is found to YSOs and a pre-main sequence star. C60 excitation and formation mechanisms are discussed in the context of these results, together with its presence and processes in post-AGB objects such as HR 4049.
Phase-controlled integrated photonic quantum circuits
Brian J. Smith,Dmytro Kundys,Nicholas Thomas-Peter,P. G. R. Smith,I. A. Walmsley
Physics , 2009, DOI: 10.1364/OE.17.013516
Abstract: Scalable photonic quantum technologies are based on multiple nested interferometers. To realize this architecture, integrated optical structures are needed to ensure stable, controllable, and repeatable operation. Here we show a key proof-of-principle demonstration of an externally-controlled photonic quantum circuit based upon UV-written waveguide technology. In particular, we present non-classical interference of photon pairs in a Mach-Zehnder interferometer constructed with X couplers in an integrated optical circuit with a thermo-optic phase shifter in one of the interferometer arms.
Sustainable development of a GCP-compliant clinical trials platform in Africa: the Malaria Clinical Trials Alliance perspective
Bernhards R Ogutu, Rita Baiden, Diadier Diallo, Peter G Smith, Fred N Binka
Malaria Journal , 2010, DOI: 10.1186/1475-2875-9-103
Abstract: Sixteen research centres in 10 African malaria-endemic countries were selected that were already working with the Malaria Vaccine Initiative (MVI) or the Medicines for Malaria Venture (MMV). All centres were visited to assess their requirements for research capacity development through infrastructure strengthening and training. Support provided by MCTA included: laboratory and facility refurbishment; workshops on GCP, malaria diagnosis, strategic management and media training; and training to support staff to undertake accreditation examinations of the Association of Clinical Research Professionals (ACRP). Short attachments to other network centres were also supported to facilitate sharing practices within the Alliance. MCTA also played a key role in the creation of the African Media & Malaria Research Network (AMMREN), which aims to promote interaction between researchers and the media for appropriate publicity and media reporting of research and developments on malaria, including drug and vaccine trials.In three years, MCTA strengthened 13 centres to perform GCP-compliant drug and vaccine trials, including 11 centres that form the backbone of a large phase III malaria vaccine trial. MCTA activities have demonstrated that centres can be brought up to GCP compliance on this time scale, but the costs are substantial and there is a need for further support of other centres to meet the growing demand for clinical trial capacity. The MCTA experience also indicates that capacity development in clinical trials is best carried out in the context of preparation for specific trials. In this regard MCTA centres involved in the phase III malaria vaccine trial were, on average, more successful at consolidating the training and infrastructure support than those centres focussing only on drug trials.About one million African children die of malaria each year [1]. Advances in molecular biology and biotechnology have brought an increased focus on the development of new drugs, vacci
The Ross Sea in a Sea of Change
Walker O. Smith Jr.,Peter N. Sedwick,Kevin R. Arrigo |,David G. Ainley
Oceanography , 2012,
Abstract: The Ross Sea, the most productive region in the Antarctic, reaches farther south than any body of water in the world. While its food web is relatively intact, its oceanography, biogeochemistry, and sea ice coverage have been changing dramatically, and likely will continue to do so in the future. Sea ice cover and persistence have been increasing, in contrast to the Amundsen-Bellingshausen sector, which has resulted in reduced open water duration for its biota. Models predict that as the ozone hole recovers, ice cover will begin to diminish. Currents on the continental shelf will likely change in the coming century, with a projected intensification of flow leading to altered deep ocean ventilation. Such changes in ice and circulation will lead to altered plankton distributions and composition, but it is difficult at present to predict the nature of these changes. Iron and irradiance play central roles in regulating phytoplankton production in the Ross Sea, but the impacts of oceanographic changes on the biogeochemistry of iron are unclear. Unlike other Southern Ocean regions, where continental shelves are very narrow and Antarctic krill dominates the herbivorous fauna, the broad shelf of the Ross Sea is dominated by crystal krill and silverfish, which are the major prey items for higher trophic levels. At present, the Ross Sea is considered to be one of the most species-rich areas of the Southern Ocean and a biodiversity "hotspot" due to its heterogeneous habitats. Despite being among the best-studied regions in the entire Southern Ocean, accurate predictions of the impacts of climate change on the oceanography and ecology of the Ross Sea remain fraught with uncertainty.
Demonstration of UV-written waveguides, Bragg gratings and cavities at 780 nm, and an original experimental measurement of group delay
Guillaume Lepert,Michael Trupke,Ed A. Hinds,Helen Rogers,James C. Gates,Peter G. R. Smith
Physics , 2011, DOI: 10.1364/OE.19.024933
Abstract: We present direct UV-written waveguides and Bragg gratings operating at 780 nm. By combining two gratings into a Fabry-Perot cavity we have devised and implemented a novel and practical method of measuring the group delay of Bragg gratings.
Array of Fabry-Pérot waveguide resonators with tunable coupling
Guillaume Lepert,E. A. Hinds,Helen L. Rogers,James C. Gates,Peter G. R. Smith
Physics , 2013, DOI: 10.1063/1.4820915
Abstract: We demonstrate the elements of a coupled-resonator optical waveguide in a side-coupled Fabry-P\'erot configuration, and show that the coupling rate between adjacent waveguides can be widely tuned through the thermo-optic effect. The device is linearly scalable and can be combined with other integrated devices, with applications as an optical delay line or as a key element in a cavity-QED based quantum simulator.
The epidemics of bovine spongiform encephalopathy and variant Creutzfeldt-Jakob disease: current status and future prospects
Smith,Peter G.;
Bulletin of the World Health Organization , 2003, DOI: 10.1590/S0042-96862003000200009
Abstract: the large epidemic of bovine spongiform encephalopathy (bse) in the united kingdom has been in decline since 1992, but has spread to other countries. the extensive control measures that have been put in place across the european union and also in switzerland should have brought the transmission of bse under control in these countries, provided that the measures were properly enforced. postmortem tests on brain tissue enable infected animals to be detected during the late stages of the incubation period, but tests that can be performed on live animals (including humans) and that will detect infections early are urgently needed. the number of infected animals currently entering the food chain is probably small, and the controls placed on bovine tissues in the european union and switzerland should ensure that any risks to human health are small and diminishing. vigilance is required in all countries, especially in those in which there has been within-species recycling of ruminant feed. fewer than 150 people, globally, have been diagnosed with variant creutzfeldt-jakob disease (vcjd), but there are many uncertainties about the future course of the epidemic because of the long and variable incubation period. better control measures are necessary to guard against the possibility of iatrogenic transmission through blood transfusion or contaminated surgical instruments. these measures will require sensitive and specific diagnostic tests and improved decontamination methods.
The epidemics of bovine spongiform encephalopathy and variant Creutzfeldt-Jakob disease: current status and future prospects
Smith Peter G.
Bulletin of the World Health Organization , 2003,
Abstract: The large epidemic of bovine spongiform encephalopathy (BSE) in the United Kingdom has been in decline since 1992, but has spread to other countries. The extensive control measures that have been put in place across the European Union and also in Switzerland should have brought the transmission of BSE under control in these countries, provided that the measures were properly enforced. Postmortem tests on brain tissue enable infected animals to be detected during the late stages of the incubation period, but tests that can be performed on live animals (including humans) and that will detect infections early are urgently needed. The number of infected animals currently entering the food chain is probably small, and the controls placed on bovine tissues in the European Union and Switzerland should ensure that any risks to human health are small and diminishing. Vigilance is required in all countries, especially in those in which there has been within-species recycling of ruminant feed. Fewer than 150 people, globally, have been diagnosed with variant Creutzfeldt-Jakob disease (vCJD), but there are many uncertainties about the future course of the epidemic because of the long and variable incubation period. Better control measures are necessary to guard against the possibility of iatrogenic transmission through blood transfusion or contaminated surgical instruments. These measures will require sensitive and specific diagnostic tests and improved decontamination methods.
Glucagon-Like Peptide-1 Induced Signaling and Insulin Secretion Do Not Drive Fuel and Energy Metabolism in Primary Rodent Pancreatic β-Cells
Marie-Line Peyot, Joshua P. Gray, Julien Lamontagne, Peter J. S. Smith, George G. Holz, S. R. Murthy Madiraju, Marc Prentki, Emma Heart
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006221
Abstract: Background Glucagon like peptide-1 (GLP-1) and its analogue exendin-4 (Ex-4) enhance glucose stimulated insulin secretion (GSIS) and activate various signaling pathways in pancreatic β-cells, in particular cAMP, Ca2+ and protein kinase-B (PKB/Akt). In many cells these signals activate intermediary metabolism. However, it is not clear whether the acute amplification of GSIS by GLP-1 involves in part metabolic alterations and the production of metabolic coupling factors. Methodology/Prinicipal Findings GLP-1 or Ex-4 at high glucose caused release (~20%) of the total rat islet insulin content over 1 h. While both GLP-1 and Ex-4 markedly potentiated GSIS in isolated rat and mouse islets, neither had an effect on β-cell fuel and energy metabolism over a 5 min to 3 h time period. GLP-1 activated PKB without changing glucose usage and oxidation, fatty acid oxidation, lipolysis or esterification into various lipids in rat islets. Ex-4 caused a rise in [Ca2+]i and cAMP but did not enhance energy utilization, as neither oxygen consumption nor mitochondrial ATP levels were altered. Conclusions/Significance The results indicate that GLP-1 barely affects β-cell intermediary metabolism and that metabolic signaling does not significantly contribute to GLP-1 potentiation of GSIS. The data also indicate that insulin secretion is a minor energy consuming process in the β-cell, and that the β-cell is different from most cell types in that its metabolic activation appears to be primarily governed by a “push” (fuel substrate driven) process, rather than a “pull” mechanism secondary to enhanced insulin release as well as to Ca2+, cAMP and PKB signaling.
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