95 research outputs found

    Radioscopic and ultrasonic data fusion via the evidence theory

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    A data fusion method, based on the the Dempster-Shafer evidence theory, is presented that aims at improving the reliability of taking a decision by simultaneously exploiting complementary information from two different sources . Within this framework, both discrete and continuous hypotheses are studied in a systematic manner. The data fusion method is applied to problems of improving the reliability of Non Destructive Testing (NDT) using real-time x-ray (RX) radioscopy and ultrasounds (US). It is illustrated with the aid of radioscopic and ultrasonic data corresponding to the same test objects . The results of detection, identification and quantification of defects are discussed and compared in detail, in both monomodality and multimodality.Cet article propose une méthode de fusion, basée sur la théorie de l'évidence, qui vise à améliorer la fiabilité d'une prise de décision en exploitant simultanément des informations complémentaires issues de deux sources différentes. Dans ce cadre, les hypothèses aussi bien discrètes que continues sont traitées de manière systématique. La méthode de fusion est appliquée au problème d'amélioration de la fiabilité du contrôle non destructif (CND) utilisant la radioscopie numérique par rayons X (RX) et les ultrasons (US). Elle est illustrée à l'aide des données radioscopiques et ultrasonores correspondant aux mêmes pièces test. Les résultats de la détection, de l'identification et de la quantification des défauts dans le cas de la monomodalité et de la multimodalité sont discutés et comparés en détail

    Fusion de données complémentaires en vue de l'amélioration de la dynamique des systèmes d'imagerie

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    Le but de cette communication consiste à montrer que la théorie de l'évidence de Dempster-Shafer peut être appliquée au problème de fusion dans le domaine de l'amélioration de la dynamique d'un système d'imagerie à rayons X. Une hypothèse étant définie comme une épaisseur d'objet, l'incertitude et l'imprécision sur les épaisseurs sont réduites grâce à la gestion des hypothèses composées ainsi qu'à la définition de leur fonctions de masse à partir de la modélisation des histogrammes des niveaux de gris. La prise de décision est basée sur le critère de maximum de crédibilité sur des hypothèses simples (singletons) ou composées (union des hypothèses). L'augmentation de la dynamique du système d'imagerie à rayons X est réalisée en combinant chaque couple de pixels correspondant au même point physique de l'objet grâce à la règle de Dempster et à la consultation d'une table de fusion

    Estimating the burden of rubella virus infection and congenital rubella syndrome through a rubella immunity assessment among pregnant women in the Democratic Republic of the Congo: Potential impact on vaccination policy.

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    BACKGROUND: Rubella-containing vaccines (RCV) are not yet part of the Democratic Republic of the Congo's (DRC) vaccination program; however RCV introduction is planned before 2020. Because documentation of DRC's historical burden of rubella virus infection and congenital rubella syndrome (CRS) has been minimal, estimates of the burden of rubella virus infection and of CRS would help inform the country's strategy for RCV introduction. METHODS: A rubella antibody seroprevalence assessment was conducted using serum collected during 2008-2009 from 1605 pregnant women aged 15-46years attending 7 antenatal care sites in 3 of DRC's provinces. Estimates of age- and site-specific rubella antibody seroprevalence, population, and fertility rates were used in catalytic models to estimate the incidence of CRS per 100,000 live births and the number of CRS cases born in 2013 in DRC. RESULTS: Overall 84% (95% CI 82, 86) of the women tested were estimated to be rubella antibody seropositive. The association between age and estimated antibody seroprevalence, adjusting for study site, was not significant (p=0.10). Differences in overall estimated seroprevalence by study site were observed indicating variation by geographical area (p⩽0.03 for all). Estimated seroprevalence was similar for women declaring residence in urban (84%) versus rural (83%) settings (p=0.67). In 2013 for DRC nationally, the estimated incidence of CRS was 69/100,000 live births (95% CI 0, 186), corresponding to 2886 infants (95% CI 342, 6395) born with CRS. CONCLUSIONS: In the 3 provinces, rubella virus transmission is endemic, and most viral exposure and seroconversion occurs before age 15years. However, approximately 10-20% of the women were susceptible to rubella virus infection and thus at risk for having an infant with CRS. This analysis can guide plans for introduction of RCV in DRC. Per World Health Organization recommendations, introduction of RCV should be accompanied by a campaign targeting all children 9months to 14years of age as well as vaccination of women of child bearing age through routine services

    Field assessment of dog as sentinel animal for plague in endemic foci of Madagascar

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    Funding Information: Sincere thanks to Mrs. L Angeltine Ralafiarisoa for technical assistance and the staff of the Plague Unit for their assistance during sample collections. This work was funded by an internal research grant (Ref: PA 14.25) from the Institut Pasteur de Madagascar. This research was also funded in part by the Wellcome Trust [095171/Z/10/Z]. For the purpose of Open Access, the authors have applied a CC BY public copyright license to any Author Accepted Manuscript version arising from this submission.Peer reviewedPublisher PD

    Development and Evaluation of Two Simple, Rapid Immunochromatographic Tests for the Detection of Yersinia pestis Antibodies in Humans and Reservoirs

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    Plague is due to the bacterium Yersinia pestis. It is accidentally transmitted to humans by the bite of infected fleas. Currently, approximately 20 developing countries with very limited infrastructure are still affected. A plague case was defined according to clinical, epidemiological and biological features. Rapid diagnosis and surveillance of the disease are essential for its control. Indeed, the delay of treatment is often rapidly fatal for patients and outbreaks may occur. Bubo aspirate is the most appropriate specimen in case of bubonic plague, but its collection is not always feasible. The main current biological approaches for the diagnosis of human plague are F1 antigen detection, serology for antibody detection by ELISA and Y. pestis isolation. The biological diagnosis of plague remains a challenge because the clinical signs are not specific. In this study, we developed some simple, rapid and affordable tests able to detect specific plague antibodies. These tests can be used as alternative methods for plague diagnosis in the field and for plague surveillance

    Immune Responses to Plague Infection in Wild Rattus rattus, in Madagascar: A Role in Foci Persistence?

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    Plague is endemic within the central highlands of Madagascar, where its main reservoir is the black rat, Rattus rattus. Typically this species is considered susceptible to plague, rapidly dying after infection inducing the spread of infected fleas and, therefore, dissemination of the disease to humans. However, persistence of transmission foci in the same area from year to year, supposes mechanisms of maintenance among which rat immune responses could play a major role. Immunity against plague and subsequent rat survival could play an important role in the stabilization of the foci. In this study, we aimed to investigate serological responses to plague in wild black rats from endemic areas of Madagascar. In addition, we evaluate the use of a recently developed rapid serological diagnostic test to investigate the immune response of potential reservoir hosts in plague foci.We experimentally infected wild rats with Yersinia pestis to investigate short and long-term antibody responses. Anti-F1 IgM and IgG were detected to evaluate this antibody response. High levels of anti-F1 IgM and IgG were found in rats one and three weeks respectively after challenge, with responses greatly differing between villages. Plateau in anti-F1 IgM and IgG responses were reached for as few as 500 and 1500 colony forming units (cfu) inoculated respectively. More than 10% of rats were able to maintain anti-F1 responses for more than one year. This anti-F1 response was conveniently followed using dipsticks.Inoculation of very few bacteria is sufficient to induce high immune response in wild rats, allowing their survival after infection. A great heterogeneity of rat immune responses was found within and between villages which could heavily impact on plague epidemiology. In addition, results indicate that, in the field, anti-F1 dipsticks are efficient to investigate plague outbreaks several months after transmission

    Genetic relatedness among isolates of Shigella sonnei carrying class 2 integrons in Tehran, Iran, 2002–2003

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    <p>Abstract</p> <p>Background</p> <p><it>Shigella </it>spp. are major cause of diarrhoeal disease in both developing and developed countries. <it>Shigella sonnei </it>is the serogroup of <it>Shigella </it>most frequently responsible for sporadic and epidemic enteritis in developed countries. In recent years the emergence and spread of <it>S. sonnei </it>biotype g carrying class 2 integron have been frequently reported in many countries. Recently, <it>S. sonnei </it>has been reported as the prevalent serogroup of <it>Shigella </it>in Iran.</p> <p>The present study was carried out to investigate phenotypic and genetic characteristics of <it>Shigella sonnei </it>isolates identified in the years 2002 and 2003 in Tehran, Iran.</p> <p>Methods</p> <p>Biotyping, drug susceptibility testing, pulsed field gel electrophoresis (PFGE) and analysis of class 2 integrons have been carried out on 60 <it>S. sonnei </it>isolates, including 57 sporadic isolates from paediatric cases of shigellosis occurring in 2002 and 2003, two sporadic isolates recovered in 1984 and the ATCC 9290 strain.</p> <p>Results</p> <p>Biotype g and resistance to streptomycin, sulfamethoxazole-trimethoprim and tetracycline were exhibited by 54 of the 57 recent isolates. Of the 54 biotype g isolates, 28 exhibited a class 2 integron of 2161 bp, and 24 a class 2 integron of 1371 bp, respectively. Class 2 integrons were not detected in four isolates only, including the two endemic isolates recovered in 1984 and two strains from recent sporadic cases. PFGE divided the strains into eight pulsotypes labeled A to H, three major pulsotypes – A to C – including the large majority of the recent sporadic <it>S. sonnei </it>isolates. Pulsotypes A and C were the most prevalent groups, accounting for 41.6% and 35.0%, respectively, of the isolates under study.</p> <p>Conclusion</p> <p>The results suggest that biotype g, class 2 integron carrying <it>S. sonnei </it>are prevalent in our geographic area. <it>S. sonnei </it>isolated in the years 2002 and 2003 could be attributed to a few predominant clusters including, respectively, strains with pulsotypes B and C carrying a 2161 bp class 2 integron, and those having pulsotype A and a 1371 bp class 2 integron. A few epidemic clones are responsible for the apparently endemic occurrence of shigellosis in Tehran, Iran.</p
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