6,724 research outputs found

    Epizootic rabbit enteropathy. Study of early phenomena with fresh inoculum and attempt at inactivation

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    [EN] Using 180 35-day-old SPF rabbits, this study used the effectiveness of bacitracin as a tool for acquiring more information on the various phases of ERE, in particular during the hours inoculation. Five groups of animals were used, including 3 treatments with Bacivet S(R) (bacitracin) at different times from inoculation, with the standard inoculum TEC3. Three parameters were studied: growth, mortality and stomach noises (borborygmi). A significant fall in growth rate was observed during the first 18 hours following the inoculation in all the inoculated groups, both medicated and not medicated. Treatment with bacitracin eliminated mortality and borborygmi, but not the initial fall in growth rate. Treatment starting 18 hours after inoculation is less effective during the acute phase than the preventive treatment. With a preventive treatment interrupted as soon as 18 hours after inoculation, a delay of several days was observed before the appearance of the disease (fall in growth rate, manifestation of borborygmi) and total mortality was reduced. Very few pathogens can explain this early fall in growth rate. Bacitracin is an antibiotic which offers good control of the disease, and probably of the pathogen but not of the physio-pathological disturbances in the first few hours. The intervention of an exogenic toxin in the first hours of contamination seems likely. Borborygmi are important criteria. The intensity and/or frequency could be used as semi-quantitative criteria to characterize the disease and for the prognosis. In a simultaneous trial, a group was contaminated with the same inoculum, heated for 10 min at 55°C, in order to obtain more information on the type of pathogen involved in the etiology of ERE. This treatment did not modify the virulence of the inoculum.This research received financial help from the Ministry for Agriculture of France (DGAL - ITAVI).Coudert, P.; Licois, D. (2005). Epizootic rabbit enteropathy. Study of early phenomena with fresh inoculum and attempt at inactivation. World Rabbit Science. 13. doi:10.4995/wrs.2005.515SWORD1

    Reactive scheduling using a multi-agent model: the SCEP framework

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    Multi-agent systems have been successfully applied to the scheduling problem for some time. However, their use often leads to poorly unsatisfactory disappointing results. A new multi-agent model, called supervisor, customers, environment, producers (SCEP), is suggested in this paper. This model, developed for all types of planning activities, introduces a dialogue between two communities of agents leading to a high level of co-operation. Its two main interests are the following: first it provides a more efficient control of the consequences generated by the local decisions than usual systems to each agent, then the adopted architecture and behaviour permit an easy co-operation between the different SCEP models, which can represent different production functions such as manufacturing, supply management, maintenance or different workshops. As a consequence, the SCEP model can be adapted to a great variety of scheduling/planning problems. This model is applied to the basic scheduling problem of flexible manufacturing systems, andit permits a natural co-habitation between infinite capacity scheduling processes, performedby the manufacturing orders, and finite capacity scheduling processes, performed by the machines. It also provides a framework in order to react to the disturbances occurring at different levels of the workshop

    Necessary and Sufficient Elastic Stability Conditions in Various Crystal Systems

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    While the Born elastic stability criteria are well-known for cubic crystals, there is some confusion in the literature about the form it should take for lower symmetry crystal classes. We present here closed form necessary and sufficient conditions for elastic stability in all crystal classes, as a concise and pedagogical reference to stability criteria in non-cubic materials

    Computational characterization and prediction of metal-organic framework properties

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    In this introductory review, we give an overview of the computational chemistry methods commonly used in the field of metal-organic frameworks (MOFs), to describe or predict the structures themselves and characterize their various properties, either at the quantum chemical level or through classical molecular simulation. We discuss the methods for the prediction of crystal structures, geometrical properties and large-scale screening of hypothetical MOFs, as well as their thermal and mechanical properties. A separate section deals with the simulation of adsorption of fluids and fluid mixtures in MOFs

    Component-based simulation for a reconfiguration study of transitic systems

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    This paper is organized as follows. Part A presents the context of reconfiguring transitic systems and the main idea in implementing the decision step. It comprises sections 1 to 3. Section 3 presents an example that illustrates the concepts presented in the next sections. Parts B and C express the models and principles used to simulate transitic systems, the result of which will be helpful for choosing the new configuration. Part B focuses mainly on models. It comprises sections 4 to 6. Part C focuses mainly on simulation principles. It comprises sections 7 to 10

    Novel Porous Polymorphs of Zinc Cyanide with Rich Thermal and Mechanical Behavior

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    We investigate the feasibility of four-connected nets as hypothetical zinc cyanide polymorphs, as well as their thermal and mechanical properties, through quantum chemical calculations and molecular dynamics simulations. We confirm the metastability of the two porous phases recently discovered experimentally (Lapidus, S. H.; et al. J. Am. Chem. Soc. 2013, 135, 7621-7628), suggest the existence of seven novel porous phases of Zn(CN)2, and show that isotropic negative thermal expansion is a common occurrence among all members of this family of materials, with thermal expansion coefficients close to that of the dense dia-c phase. In constrast, we find a wide variety in the mechanical behavior of these porous structures with framework-dependent anisotropic compressibilities. All porous structures, however, show pressure-induced softening leading to a structural transition at modest pressure.Comment: Chem. Mater. 201

    Oil Price and the Dollar

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    The aim of this paper is to test whether a stable long-term relationship exists between oil prices and the US effective exchange rate, expressed in real terms. To this end, weproceed to a cointegration and causality study between the two variables. Our results indicate that causality runs from oil prices to the exchange rate and that the relationship between the two variables is transmitted through the US net foreign asset position.oil prices; effective exchange rate; net foreign asset position; cointegration; causality; error correction model
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