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Search Results: 1 - 10 of 227461 matches for " Peter G. Smith "
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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.
Germ cell specification and ovary structure in the rotifer Brachionus plicatilis
James M Smith, Andrew G Cridge, Peter K Dearden
EvoDevo , 2010, DOI: 10.1186/2041-9139-1-5
Abstract: Bpvasa and Bpnos RNA expression have very similar distributions in the Brachionus ovary, showing ubiquitous expression in the vitellarium, with higher levels in the putative germ cell cluster. Bpvas RNA expression is present in freshly laid eggs, remaining ubiquitous in embryos until at least the 96 cell stage after which expression narrows to a small cluster of cells at the putative posterior of the embryo, consistent with the developing ovary. Bpnos RNA expression is also present in just-laid eggs but expression is much reduced by the four-cell stage and absent by the 16-cell stage. Shortly before hatching of the juvenile rotifer from the egg, Bpnos RNA expression is re-activated, located in a subset of posterior cells similar to those expressing Bpvas at the same stage.The observed expression of vasa and nanos in the developing B. plicatilis embryo implies an epigenetic origin of primordial germ cells in Rotifer.The segregation of the germline from somatic tissues is an essential process in the development of all animals. Despite this, specification of the progenitors of the germline, the primordial germ cells (PGCs), takes place via two broadly different strategies across animal phyla (reviewed in [1]). Germ cells can be specified early in embryogenesis by the inheritance of maternal determinants inherited in the cytoplasm of the oocyte ('preformation'), as in Drosophila, Danio rerio, Xenopus laevis and Caenorhabditis elegans. Alternately, as in the mouse, germ cells can be selected later in the embryonic development from undifferentiated precursors by a localized inductive signal ('epigenesis'). While the majority of genetic model organisms specify germ cells by preformation, epigenesis is the more prevalent mechanism for PGC specification across animal phyla. This, along with the prevalence of epigenesis for germline specification in basal metazoans, implicates epigenesis as the ancestral mechanism of germ line specification in animals [2]. It should be noted,
Clinical trials to estimate the efficacy of preventive interventions against malaria in paediatric populations: a methodological review
Vasee S Moorthy, Zarifah Reed, Peter G Smith
Malaria Journal , 2009, DOI: 10.1186/1475-2875-8-23
Abstract: To prepare for a WHO consultation on design issues in malaria vaccine trials, controlled trials of preventive interventions against malaria in children in endemic countries were identified in which clinical malaria, or death, had been one of the main end-points. Trials were included that evaluated the impact of vaccines, insecticide-treated bed nets (ITN), intermittent presumptive or preventive therapy in infants (IPTi) or, in one instance, vitamin A supplementation. Methods that had been used in these trials were summarized and compared in order to identify issues that were directly relevant to the design of malaria vaccine trials.29 controlled trials of preventive malaria interventions were identified, of which eight were vaccine trials. Vaccine trials that were designed to detect an effect on clinical malaria all reported the incidence rate of first episodes of clinical malaria as their primary endpoint. Only one trial of a preventive intervention (of ITN) was identified that was designed to detect an effect on severe malaria. A group of larger trials were designed to detect an effect of impregnated bed nets or curtains on all-cause mortality as the primary end-point. Key methodological and reporting differences between trials are noted in the text. Two issues have been identified that are of some concern. Firstly, the choice of primary endpoint is not stated in the reports of a number of the trials and, secondly, the relationship between pre-specified analysis plans and trial reports is rarely made clear.This article reports an investigation into the ways in which trial design and reporting could be improved and standardized to enable comparative evaluation of the relative merits of malaria control measures, and specifically with respect to the design of malaria vaccine trials. The need for standardization of clinical trial design, conduct, analysis and reporting has been also affirmed as a priority area by the Malaria Vaccine Technology Roadmap.The development
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:
The natural history of HIV-1 and HIV-2 infections in adults in Africa: a literature review
Jaffar Shabbar,Grant Alison D.,Whitworth Jimmy,Smith Peter G.
Bulletin of the World Health Organization , 2004,
Abstract: About 30 million people in Africa are estimated to be living with human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS), yet data about the natural history of infection on the continent are sparse. We reviewed the literature on the natural history of HIV-1 and HIV-2 infections among African adults. Only one study, conducted in rural Uganda, has reported on survival from the time of HIV-1 seroconversion: the median was 9.8 years, which is similar to that reported in developed countries in the early stages of the epidemic and consistent with the findings from the follow-up of individuals identified by serological testing during community-based prevalence studies from Africa. Progression to symptomatic disease was faster in Uganda than in developed countries, due largely to the high background level of morbidity. Various studies suggest that people infected with HIV-2 survive longer and the course of the disease is possibly more variable than in people infected with HIV-1. However no studies have investigated survival from time of seroconversion among people infected with HIV-2. The majority of patients in hospital in Africa with either HIV-1 or HIV-2 have the clinical features of AIDS just before they die, and many are severely immunosuppressed. This is similar to the situation in developed countries before the introduction of highly active antiretroviral therapy (HAART). Potentially preventable infections are the leading causes of death among individuals infected with HIV-1. Prophylactic regimens and better treatments could have some effect on survival, but major improvements in life expectancy will require HAART.
Adiabatic quantum optimization with qudits
M. H. S. Amin,Neil G. Dickson,Peter Smith
Physics , 2011,
Abstract: Most realistic solid state devices considered as qubits are not true two-state systems but multi-level systems. They can approximately be considered as qubits only if the energy separation of the upper energy levels from the lowest two is very large. If this condition is not met, the upper states may affect the evolution and therefore cannot be neglected. Here, we consider devices with double-well potential as basic logical elements, and study the effect of higher energy levels, beyond the lowest two, on adiabatic quantum optimization. We show that the extra levels can be modeled by adding additional (ancilla) qubits coupled to the original (logical) qubits. The presence of these levels is shown to have no effect on the final ground state. We also study their influence on the minimum gap for a set of 8-qubit spin glass instances.
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.
Propagation using Chain Event Graphs
Peter Thwaites,Jim Q. Smith,Robert G. Cowell
Computer Science , 2012,
Abstract: A Chain Event Graph (CEG) is a graphial model which designed to embody conditional independencies in problems whose state spaces are highly asymmetric and do not admit a natural product structure. In this paer we present a probability propagation algorithm which uses the topology of the CEG to build a transporter CEG. Intriungly,the transporter CEG is directly analogous to the triangulated Bayesian Network (BN) in the more conventional junction tree propagation algorithms used with BNs. The propagation method uses factorization formulae also analogous to (but different from) the ones using potentials on cliques and separators of the BN. It appears that the methods will be typically more efficient than the BN algorithms when applied to contexts where there is significant asymmetry present.
The Liar Hypodox: A Truth-Teller’s Guide to Defusing Proofs of the Liar Paradox  [PDF]
Peter Eldridge-Smith
Open Journal of Philosophy (OJPP) , 2019, DOI: 10.4236/ojpp.2019.92011
Abstract: It seems that the Truth-teller is either true or false, but there is no accepted principle determining which it is. From this point of view, the Truth-teller is a hypodox. A hypodox is a conundrum like a paradox, but consistent. Sometimes, accepting an additional principle will convert a hypodox into a paradox. Conversely, in some cases, retracting or restricting a principle will convert a paradox to a hypodox. This last point suggests a new method of avoiding inconsistency. This article provides a significant example. The Liar paradox can be defused to a hypodox by relatively minimally restricting three principles: the T-schema, substitution of identicals and universal instantiation. These restrictions are not arbitrary. For each, I identify the source of a contradiction given some presumptions. Then I propose each restriction as a reasonable way to deal with that source of contradiction.
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