946 research outputs found

    Evaluation of the epidemiological importance of classical swine fever infected, E2 sub-unit marker vaccinated animals with RT-nPCR positive blood samples

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    &lt;p&gt;It has been demonstrated that pigs that have been double vaccinated with an E2 sub-unit marker vaccine and that are infected with classical swine fever virus (CSFV) through a natural contact infection may react positive in a CSFV detecting RT-nPCR test, whereas no virus could be isolated by using the conventional virus isolation (VI) technique. To evaluate whether these vaccinated and infected pigs may spread the virus, three experiments were set up. In the first, susceptible pigs were inoculated with serum originating from vaccinated RT-nPCR positive pigs. In the second, vaccinated RT-nPCR positive pigs were brought into contact with sentinel animals. In the third, vertical transmission was evaluated in RT-nPCR positive vaccinated pregnant gilts. In the first two experiments, no proof of virus transmission was found, whereas in the third vertical transmission was observed. The conclusion is that in vaccinated pigs that are positive in RT-nPCR but negative in VI, the level of circulating virus is probably not high enough for horizontal transmission, whereas vertical transmission of the virus is possible.&lt;/p&gt;</p

    Bilateral National Metrology Institute Comparison of Guarded-Hot-Plate Apparatus

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    Two national metrology institutes have conducted an international interlaboratory comparison on thermal conductivity for two thermal insulation reference materials. The Laboratoire national de métrologie et d’essais (LNE), France, and the National Institute of Standards and Technology (NIST), United States, present measurements obtained by the guarded-hot-plate method. The study involved two materials: expanded polystyrene board (EPS) and fibrous glass board (FGB). The EPS was provided by the LNE and is issued as a transfer specimen; the FGB provided by NIST was issued as Standard Reference Material (SRM) 1450c. For each reference material, the study was based on four independent measurements at a mean temperature of 24°C and two additional mean temperatures of 10°C and 35°C

    Methodology of the biological risk classification of animal pathogens in Belgium

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    The biological hazards posed by micro-organisms have lead to their categorisation into risk groups and the elaboration of classification lists. Current classification systems rely on criteria defined by the World Health Organization, which cover the severity of the disease the micro-organism might cause, its ability to spread and the availability of prophylaxis or efficient treatment. Animal pathogens are classified according to the definitions of the World Organization of Animal Health, which also consider economic aspects of disease. In Europe, classification is often directly linked to containment measures. The Belgian classification system however, only considers the inherent characteristics of the micro-organism, not its use, making the risk classification independent of containment measures. A common classification list for human and animal pathogens has been developed in Belgium using as comprehensive an approach as possible. Evolution of scientific knowledge will demand regular updating of classification lists. This paper describes the Belgian risk classification system and the methodology that was used for its peer-reviewed revision (with a focus on animal pathogens)

    Bi-objective goal programming for balancing costs vs. nutritional adequacy

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    IntroductionLinear programming (LP) is often used within diet optimization to find, from a set of available food commodities, the most affordable diet that meets the nutritional requirements of an individual or (sub)population. It is, however, not always possible to create a feasible diet, as certain nutritional requirements are difficult to meet. In that case, goal programming (GP) can be used to minimize deviations from the nutritional requirements in order to obtain a near feasible diet. With GP the cost of the diet is often overlooked or taken into account using the ε-constraint method. This method does not guarantee to find all possible trade-offs between costs and nutritional deficiency without solving many uninformative LPs.MethodsWe present a method to find all trade-offs between any two linear objectives in a dietary LP context that is simple, does not solve uninformative LPs and does not need prior input from the decision maker (DM). This method is a bi-objective algorithm based on the NonInferior Set Estimation (NISE) method that finds all efficient trade-offs between two linear objectives.ResultsIn order to show what type of insights can be gained from this approach, two analyses are presented that investigate the relation between cost and nutritional adequacy. In the first analysis a diet with a restriction on the exact energy intake is considered where all nutrient intakes except energy are allowed to deviate from their prescription. This analysis is especially helpful in case of a restrictive budget or when a nutritionally adequate diet is either unaffordable or unattainable. The second analysis only relaxes the exact energy intake, where the other nutrients are kept within their requirements, to investigate how the energy intake affects the cost of a diet. Here, we describe in what situations the so-called more-for-less paradox takes place, which can be induced by requiring an exact energy intake.ConclusionTo the best of our knowledge, we are the first to address how to obtain all efficient trade-offs of two linear objectives in a dietary LP context and how this can be used for analyses

    Risk Factors for Course of Posttraumatic Stress Disorder Among Vietnam Veterans: A 14-Year Follow-Up of American Legionnaires

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    Risk factors affecting the course of posttraumatic stress disorder (PTSD) are poorly understood. As part of a larger study on characterizing exposure to herbicides in Vietnam, the authors investigated this issue in a random sample of 1,377 American Legionnaires who had served in Southeast Asia during the Vietnam War and were followed over a 14-year period. High combat exposure, perceived negative community attitudes at homecoming, minority race, depression symptoms at Time 1, and more anger at Time 1 predicted a more chronic course. Community involvement at Time 1 was protective and associated with decreased risk at Time 2. Discomfort in disclosing Vietnam experiences was associated with an increased risk for developing PTSD but did not predict its course. Combat exposure predicted PTSD course more strongly than any other risk factor. Findings suggest recovery from PTSD is significantly influenced by perceived social support
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