66 research outputs found

    A Dynamic Preconditioner for Newton-Krylov Algorithms: Application to Fluid-Structure Interaction

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    We consider linear and nonlinear convergence acceleration techniques in the framework of Newton or inexact Newton methods. The proposed procedure is based on a new dynamic preconditioner to be used in combination with the GMRES method for reducing the cost of solving a sequence of linear systems. A nonlinear convergence acceleration technique based on a previous work by Washio et al. is also added. The benefits of this combination of acceleration techniques is shown on fluid-structure interaction problems in haemodynamics for two- and three-dimensional applications

    Dengue Spatial and Temporal Patterns, French Guiana, 2001

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    To study a 2001 dengue fever outbreak in Iracoubo, French Guiana, we recorded the location of all patients’ homes and the date when symptoms were first observed. A geographic information system was used to integrate the patient-related information. The Knox test, a classic space-time analysis technique, was used to detect spatiotemporal clustering. Analysis of the relative-risk (RR) variations when space and time distances vary, highlighted the maximum space and time extent of a dengue transmission focus. The results show that heterogeneity in the RR variations in space and time corresponds to known entomologic and epidemiologic factors, such as the mosquito feeding cycle and host-seeking behavior. This finding demonstrates the relevance and potential of the use of GIS and spatial statistics for elaborating a dengue fever surveillance strategy

    Plasmodium vivax Malaria among Military Personnel, French Guiana, 1998–2008

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    We obtained health surveillance epidemiologic data on malaria among French military personnel deployed to French Guiana during 1998–2008. Incidence of Plasmodium vivax malaria increased and that of P. falciparum remained stable. This new epidemiologic situation has led to modification of malaria treatment for deployed military personnel

    Value of syndromic surveillance within the Armed Forces for early warning during a dengue fever outbreak in French Guiana in 2006

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    <p>Abstract</p> <p>Background</p> <p>A dengue fever outbreak occured in French Guiana in 2006. The objectives were to study the value of a syndromic surveillance system set up within the armed forces, compared to the traditional clinical surveillance system during this outbreak, to highlight issues involved in comparing military and civilian surveillance systems and to discuss the interest of syndromic surveillance for public health response.</p> <p>Methods</p> <p>Military syndromic surveillance allows the surveillance of suspected dengue fever cases among the 3,000 armed forces personnel. Within the same population, clinical surveillance uses several definition criteria for dengue fever cases, depending on the epidemiological situation. Civilian laboratory surveillance allows the surveillance of biologically confirmed cases, within the 200,000 inhabitants.</p> <p>Results</p> <p>It was shown that syndromic surveillance detected the dengue fever outbreak several weeks before clinical surveillance, allowing quick and effective enhancement of vector control within the armed forces. Syndromic surveillance was also found to have detected the outbreak before civilian laboratory surveillance.</p> <p>Conclusion</p> <p>Military syndromic surveillance allowed an early warning for this outbreak to be issued, enabling a quicker public health response by the armed forces. Civilian surveillance system has since introduced syndromic surveillance as part of its surveillance strategy. This should enable quicker public health responses in the future.</p

    Syndromic surveillance of potentially epidemic infectious diseases: Detection of a measles epidemic in two health centers in Gabon, Central Africa

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    Measles is a respiratory disease caused by the measles virus (MV) belonging to the Paramyxovirus family and the Morbillivirus genus. Due to a failure in maintaining immunization coverage in some countries, measles is a re-emerging disease in the human population, especially in Africa. The aim of this study was to describe a measles epidemic in Gabon. At first, a syndromic surveillance was set up. Blood samples from febrile patients with maculopapular rash were taken and sent to the measles reference center in Cameroon for laboratory confirmation. Between March and May 2016, 79 clinically suspected cases were reported including 82.3% (n=65) and 17.7% (n=14) in Oyem and Libreville, respectively. In total, 39.2% (n=31) of children were 11 months-old, 34.2% (n=27) were children aged 1 to 4 years, 11.4% (n=9) were older children from 5 to 9 years, 6.3% (n=5) of children were aged 10 to 15 years and 8.9% (n=7) were 15 years and older. 53.3% (16/30) were laboratory confirmed. This measles outbreak reiterates the importance of maintaining a high level of vaccine coverage in Gabon for vaccine-preventable diseases, as well as the usefulness of a near-real-time surveillance system for the detection of infectious diseases

    A biocodicological analysis of the medieval library and archive from Orval Abbey, Belgium.

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    Biocodicological analysis of parchments from manuscript books and archives offers unprecedented insight into the materiality of medieval literacy. Using ZooMS for animal species identification, we explored almost the entire library and all the preserved single leaf charters of a single medieval Cistercian monastery (Orval Abbey, Belgium). Systematic non-invasive sampling of parchment collagen was performed on every charter and on the first bifolium from every quire of the 118 codicological units composing the books (1490 samples in total). Within the genuine production of the Orval scriptorium (26 units), a balanced use of calfskin (47.1%) and sheepskin (48.5%) was observed, whereas calfskin was less frequent (24.3%) in externally produced units acquired by the monastery (92 units). Calfskin was preferably used for higher quality manuscripts while sheepskin tends to be the standard choice for 'ordinary' manuscript book production. This finding is consistent with thirteenth-century parchment accounts from Beaulieu Abbey (England) where calfskin supply was more limited and its price higher. Our study reveals that the making of archival documents does not follow the same pattern as the production of library books. Although the five earliest preserved charters are made of calfskin, from the 1230s onwards, all charters from Orval are written on sheepskin

    MĂ©thodes innovantes pour le diagnostic d'infection par le virus de la dengue

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    Les caractĂ©ristiques Ă©pidĂ©miologiques de l infection par le virus de la dengue nĂ©cessitaient la mise en place de nouveaux outils diagnostics afin de pouvoir poser un diagnostic diffĂ©rentiel de primo- ou de rĂ©-infection par cet arbovirus, et d effectuer des investigations de terrain. Les travaux prĂ©sentĂ©s dans cette thĂšse apportent, par deux approches distinctes, des outils de diagnostic innovants pour une meilleure prise en charge des patients en zone d endĂ©mie. De fait, alors que le test d aviditĂ© des IgG permet de poser un diagnostic diffĂ©rentiel prĂ©coce d infection par une approche immuno-enzymatique rapide et performante (Se=95,1% - Sp= 80%), les investigations rĂ©alisĂ©es Ă  partir de sang capillaire sur papier buvard montrent l intĂ©rĂȘt de ce compartiment biologique tant pour la simplicitĂ© du prĂ©lĂšvement et son transport, que pour ses performances, en terme de sensibilitĂ© et de spĂ©cificitĂ© (82% et 90%), et son utilitĂ© lors d Ă©tudes Ă©pidĂ©miologiques sur le terrain. Par ailleurs, les rĂ©sultats obtenus ouvrent de nouveaux champs d investigation concernant la physiopathologie du virus de la dengue au niveau du sang capillaire.PARIS-BIUSJ-ThĂšses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF
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