166 research outputs found
POD-based reduced order model for flows induced by rigid solids in forced rotation
This paper deals with the construction of reduced order models (ROMs) for the simulation of the interaction between a fluid and a rigid solid with imposed rotation velocity. The approach is a follows. First, we derive a monolithic description of the fluid/structure interaction by extending the Navier-Stokes equations from the fluid domain to the solid (rotor) domain similarly to the fictitious-domain approach. Second, we build a ROM by a proper orthogonal decomposition (POD) of the resulting multi-phases flow. This method consists in (i) constructing an optimal albeit empirical spatial basis for a very small sub-space of the solution space, and (ii) projecting the governing equations on this reduced basis. Third, we cope with the reconstruction of the high-dimensional velocity field needed to evaluate the imposed velocity constraint by a POD of the solid membership function. Fourth, we use state of the art method to interpolate between available POD bases to build the proposed POD-ROM for a range of parameters values. The proposed method is applied to an academic configuration and proves efficient in the reconstruction of the velocity in both the fluid and solid domains while substantially reducing the computational cost
Statut parasitaire du vison d'Europe (Mustela lutreola) en France : Etude comparative de la faune helminthique du vison d'Europe, du vison d'Amérique (Mustela vison) et du putois (Mustela putorius)
Le vison d'Europe est une des espÚces les plus menacées de disparition en Europe actuellement. C'est aussi une espÚce peu étudiée jusqu'à présent sur le plan scientifique.
Le vison d'Amérique et le putois, sont deux autres Mustélidés présents en France mais dont la démographie est bien meilleure.
Ce travail entre dans le cadre du Plan National de Sauvegarde du vison d'Europe, lequel vise à mieux connaßtre l'espÚce afin de découvrir et de mettre en oeuvre les moyens d'enrayer sa disparition. Notre étude a pour but de recenser les helminthes présents chez ces trois espÚces, d'abord dans la littérature scientifique, puis de maniÚre expérimentale. L'étude a concerné 13 visons d'Europe, 12 visons d'Amérique et 4 putois originaires du Sud-Ouest de la France.
Nous avons donc pu montrer que les visons d'Europe semblent héberger des vers plus nombreux et avec une plus grande diversité que les visons d'Amérique. Les putois sont, eux aussi, assez fortement parasités
Fibromatose du Lapin
Lombard Charles, Liberge J. Fibromatose du lapin. In: Bulletin de l'Académie Vétérinaire de France tome 112 n°2, 1959. pp. 153-154
Politique africaine, dossier « Justice et réconciliation ; ambiguïtés et impensés »
Politique africaine nous propose une rĂ©flexion Ă plusieurs voix sur les expĂ©riences de justice transitionnelle, menĂ©es dans quatre pays africains ayant traversĂ© de longues pĂ©riodes de conflits politiques meurtriers : lâAfrique du Sud, la Sierra Leone, le Rwanda, le Burundi. Les auteurs ont voulu aborder lâĂ©tude des diffĂ©rents dispositifs testĂ©s sans rĂ©itĂ©rer les analyses centrĂ©es sur les aspects cathartiques ou thĂ©rapeutiques, ni porter eux-mĂȘmes de jugement ou dresser de bilan dĂ©finitif de c..
Toxicological pathology in drug safety assessment
In preclinical toxicology studies, pathology includes postmortem macroscopic and microscopic examinations
of the tissues. These examinations are carried out under the responsibility of the pathologist
in compliance with the principles of GLP (Good Laboratory Practice). The pathologistâs duties involve
comparing animals given a known drug at different doses with control animals to detect any adverse
effects of the test compound. A disciplined, consistent approach is essential to ensure uniform reporting
levels and avoid any drift in the diagnostic descriptions used between the animals during the course
of the study. This is one of the most difficult constraints inherent to the work of the pathologist. At
the end of a study, the pathologist writes a report describing any drug-related effects on organ weights
as well as any macroscopic and microscopic abnormality. The pathology report is a key element in
the final toxicological report. Nonetheless, pathology results should be evaluated in the light of the
other study data, particularly those generated by the clinical examination, as well as hematology and
biochemistry tests.Dans les Ă©tudes de toxicologie
préclinique, le terme de « Pathologie » recouvre l'ensemble des examens
anatomo-pathologiques (macroscopie et microscopie), effectués aprÚs le sacrifice des
animaux. Ces examens se déroulent sous la responsabilité du « Pathologiste » qui travaille
dans un environnement conforme aux « BPL » (Bonnes Pratiques de Laboratoire). Son travail
consiste à comparer des lots d'animaux recevant un produit connu à différentes doses avec
des animaux témoins, pour mettre en évidence d'éventuels effets indésirables liés à ce
produit. Rigueur et homogénéité des seuils de description et de diagnostic entre les animaux
sont essentielles pour ne pas introduire de dérive au cours du temps. Cette contrainte est
l'une des grandes difficultés inhérentes au travail du pathologiste toxicologue. Enfin, le
pathologiste rédige un rapport décrivant les effets du produit sur les poids d'organes ainsi
que les éventuelles anomalies macroscopiques et microscopiques. Ce rapport est un élément
clé du rapport toxicologique final, toutefois les résultats anatomo-pathologiques doivent
ĂȘtre analysĂ©s Ă la lumiĂšre des autres donnĂ©es de l'Ă©tude, particuliĂšrement celles issues de
la clinique et de l'hématobiochimie
Néphrome embryonnaire de la cane et hérédité
Lombard Charles, Liberge J. Néphrome embryonnaire de la Cane et hérédité. In: Bulletin de l'Académie Vétérinaire de France tome 115 n°3, 1962. pp. 105-109
Changes in TNFα, NFÎșB and MnSOD protein in the vestibular nuclei after unilateral vestibular deafferentation
BACKGROUND: Unilateral vestibular deafferentation results in strong microglial and astroglial activation in the vestibular nuclei (VN) that could be due to an inflammatory response. This study was aimed at determining if markers of inflammation are upregulated in the VN after chemical unilateral labyrinthectomy (UL) in the rat, and if the inflammatory response, if any, induces the expression of neuroprotective factors that could promote the plasticity mechanisms involved in the vestibular compensation process. The expressions of inflammatory and neuroprotective factors after chemical or mechanical UL were also compared to verify that the inflammatory response was not due to the toxicity of sodium arsanilate. METHODS: Immunohistological investigations combined the labeling of tumor necrosis factor α (TNFα), as a marker of the VN inflammatory response, and of nuclear transcription factor ÎșB (NFÎșB) and manganese superoxide dismutase (MnSOD), as markers of neuroprotection that could be expressed in the VN because of inflammation. Immunoreactivity (Ir) of the VN cells was quantified in the VN complex of rats. Behavioral investigations were performed to assess the functional recovery process, including both static (support surface) and dynamic (air-righting and landing reflexes) postural tests. RESULTS: Chemical UL (arsanilate transtympanic injection) induced a significant increase in the number of TNFα-Ir cells in the medial and inferior VN on both sides. These changes were detectable as early as 4 h after vestibular lesion, persisted at 1 day, and regained nearly normal values at 3 days. The early increase in TNFα expression was followed by a slightly delayed upregulation of NFÎșB 8 h after chemical UL, peaking at 1 day, and regaining control values 3 days later. By contrast, upregulation of MnSOD was more strongly delayed (1 day), with a peak at 3 days, and a return to control values at 15 days. Similar changes of TNFα, NFÎșB, and MnSOD expression were found in rats submitted to mechanical UL. Behavioral observations showed strong posturo-locomotor deficits early after chemical UL (1 day) and a complete functional recovery 6 weeks later. CONCLUSIONS: Our results suggest that the upregulation of inflammatory and neuroprotective factors after vestibular deafferentation in the VN may constitute a favorable neuronal environment for the vestibular compensation process
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