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See detailÉtude des risques liés aux pratiques d’élevage sur la santé mammaire des exploitations laitières en Wallonie
Theron, Léonard ULg

Master of advanced studies dissertation (2008)

As most of production pathologies in dairy farming, mastitis is characterized by a multifactorial aetiology. Its diagnosis and treatment requires a good knowledge of its determinant and predisposing ... [more ▼]

As most of production pathologies in dairy farming, mastitis is characterized by a multifactorial aetiology. Its diagnosis and treatment requires a good knowledge of its determinant and predisposing factors. The comparative epidemiology of 349 walloon farms registered to individual milk analysis programs led to highlight the practices used in farms whose last 3 months' herd somatic cell count was above 400.000 cells/ml. We identified the following risk indicators relative to 1) herd demography : age, composition, herd production average, percentage of high cell counts animals 2) the animal housing : use of straw as bedding stall for all classes of animals and lack of a calving pen 3) the milking machine : milking cups cleaning 4) the dairy practices : lack of washing cloth towels between 2 milkings, occasional foremilk check, stripping, lack of post-dip and 5) animal nutrition : mould on beet pulp silos, adding salt in the diet and composition of the main concentrate. This descriptivre and univariate analysis confirmed the risky situation of a large majority of dairy farms regarding the recommendations of good dairy practices guides. [less ▲]

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See detailEtude des rôles du produit d'expression du gène M138L du virus Myxoma dans la pathogénie de la myxomatose
Boutard, Bérengère ULg

Doctoral thesis (2016)

Myxoma virus belongs to the Poxviridae family and induces a severe and often lethal disease called myxomatosis in the European rabbit (Bertagnoli & Marchandeau, 2015). Numerous genes of the virus encode ... [more ▼]

Myxoma virus belongs to the Poxviridae family and induces a severe and often lethal disease called myxomatosis in the European rabbit (Bertagnoli & Marchandeau, 2015). Numerous genes of the virus encode for proteins with immunomodulatory functions (Spiesschaert et al., 2011; Zuniga, 2002). Among them, it has been demonstrated that the virus encodes for an α-2,3-sialyltransferase (Jackson et al., 1999; Markine-Goriaynoff et al., 2004b) that catalyzes the transfer of sialic acid to the N and O-glycans of glycoproteins and glycolipids (Varki & Schauer, 2009). Glycans, and especially sialic acids, are known to play significant roles in interactions and recognition between cells and between cells and viruses (Cohen & Varki, 2010; Raman et al., 2005; Vigerust & Shepherd, 2007). The aim of this thesis was to better understand the roles played by the viral α-2,3-sialyltransferase in the pathogenesis of myxomatosis. Using the Lausanne strain as parental strain, we have constructed strains deficient for the M138L gene encoding the α-2,3-sialyltransferase, and a revertant strain. Although no difference could be detected between the strains in vitro, the M138L knockout strains were highly attenuated in vivo. Especially, we observed more neutrophils at the beginning of infection and then an important mononuclear cells infiltrate in the dermis of the primary sites of infection for rabbits infected with the M138L knockout strains. We then wanted to determine which viral and / or cellular proteins were affected by the viral α-2,3-sialyltransferase, to check if their modification could explain the phenotype that we observed. We showed that the viral M-T7 protein was sialylated by the viral enzyme. M-T7 is a homologue of the interferon-γ receptor (Mossman et al., 1995) which is also able to bind and inhibit several chemokines, to block the chemokine gradient formation and to inhibit the inflammatory cells attraction towards the site of infection (Alcami, 2003; Lalani et al., 1997). However, we could not detect any effect of sialylation on the secretion or the activity of the M-T7 proteins purified from the four strains, either in vitro or in vivo. Altogether , these results show that the viral α-2,3-sialyltransferase is a virulence factor of the virus that could act directly or indirectly on several immunomodulatory viral proteins, and so on the immune cells attraction and adaptive immunity development. [less ▲]

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See detailETUDE DES SÉDIMENTS COTIERS DU CAP CORSE: RECONSTRUCTION PALÉOENVIRONNEMENTALE ET SUIVI DE LA CONTAMINATION EN ÉLÉMENTS TRACES MÉTALLIQUES AU COURS DE LA PÉRIODE HISTORIQUE
Fontaine, François ULg; Goiran, Jean-Philippe; PRUDENCIO, Isabel et al

Conference (2014, April)

Les sédiments sont d’excellentes archives de la contamination de notre environnement. Depuis l’Antiquité, les activités humaines génèrent des aérosols anthropiques enrichis en métaux lourds (e.g. Pb, Zn ... [more ▼]

Les sédiments sont d’excellentes archives de la contamination de notre environnement. Depuis l’Antiquité, les activités humaines génèrent des aérosols anthropiques enrichis en métaux lourds (e.g. Pb, Zn, Cu, Cd, Hg) ou associés (As, Sb). Ces polluants métalliques se mélangent aux aérosols naturels (altération des roches) et leurs retombées sont incorporées dans les sols et les sédiments où ils sont préservés (Boyd, 2004). Sur des sédiments datés, une approche géochimique permet de quantifier l’apport anthropique en éléments métalliques par rapport aux sources naturelles et de reconstituer l’historique de la pollution. Les côtes méditerranéennes sont caractérisées par d’intenses échanges commerciaux, et ce depuis l’Antiquité. Nous proposons une reconstruction paléoenvironnementale ainsi qu’un suivi de la contamination anthropique au cours de la période historique pour différents sites du Cap Corse (France ; Figure 1). Cette région de Méditerranée se caractérise par une riche activité économique au cours de la période historique. Depuis le VIème siècle, la Corse a été colonisée successivement par les Grecs, les Carthaginois, les Etrusques puis par les Romains. En milieu continental, des témoins archéologiques (sépulture, oppidum, chapelle) attestent d’une occupation de cette zone sur une période assez longue. Cependant de nombreuses interrogations subsistent quant à l’importance des établissements, leurs périodes d’occupation, leurs activités économiques et leurs rapports commerciaux avec les autres cités du Cap Corse et des côtes méditerranéennes (de La Brière, 2010). Des carottes de 1 m à 1,5 m ont été prélevées à la tarière dans différents sites du Cap Corse. Les concentrations en éléments majeurs et en éléments traces métalliques ont été mesurées par spectrométrie de masse (ICP-MS), activation neutronique (INAA) et par XRF core scanner. Les datations 14C réalisées sur des macrorestes de matières végétales et charbons montrent que ces carottes couvrent toute la période historique, à l’exception de celle prélevée à Méria qui ne couvre qu’environ 300 ans. Cette carotte a également la particularité de contenir d’importantes concentrations en métaux lourds tels que le Sb (2000 ppm) et l’As (300 ppm). Cette contamination est d’origine locale et liée à la présence d’une ancienne mine d’antimoine à 2 km en amont de Méria. Afin d’obtenir un enregistrement sur les 2000 dernières années, un carottage plus long sera réalisé lors d’une nouvelle campagne de terrain. D’autres carottages seront également réalisés entre la mine et la côte actuelle afin d’observer la variation spatiale dans le but de quantifier l’impact environnemental des activités humaines locales et régionales. [less ▲]

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See detailEtude des sémiochimiques volatils impliqués dans le mutualisme fourmis-pucerons
Fischer, Christophe ULg

Doctoral thesis (2016)

For decades, the mutualistic relationship that ant and aphids may present has fascinated entomologists, as evidenced by the abundant literature on the subject. The principles of this interaction are ... [more ▼]

For decades, the mutualistic relationship that ant and aphids may present has fascinated entomologists, as evidenced by the abundant literature on the subject. The principles of this interaction are simple: as long as their colony remains, aphids provide ants with a stable and abundant source of sugars, honeydew. In exchange, ants tend aphid colonies and provide them cleaning and protection against various natural enemies. Nevertheless, some aspects of this relationship remain misunderstood. This is for example the case of the factors influencing the search and the discovery of a potential partner, first step to any potential mutualistic interaction. The role held by volatile chemical cues, called semiochemicals, in this relationship is also misunderstood. The objective of this thesis is to improve understanding of the role played by volatile semiochemicals in this mutualistic relationship, especially during the partner search stage, both from the perspective of the ant and of the aphid. The black garden ant, Lasius niger L., and the black bean aphid, Aphis fabae Scop., constitute our biological model. The impact of volatile compounds on the search behavior of the ant has first been investigated. These compounds are from multiple origins, either directly emitted by the aphid or induced by its presence. First, the ability of ants to perceive E-β-farnesene, the main component of many aphid alarm pheromone, and to use it to locate aphid colonies has been highlighted. This compound has indeed shown attractiveness to ants, even at low doses corresponding to the emissions of an unstressed aphid colony. Then, the roles played by honeydew volatile compounds in ant attraction have been demonstrated. These compounds also allow ants to remotely discriminate different aphid species and to direct their searches accordingly. These semiochemicals are produced by honeydew microflora, and a particularly attractive bacterial strain, Staphylococcus xylosus, has been isolated from A. fabae honeydew. Finally, the active role of winged aphids, which are aphid’s dispersal form, in the search for a mutualistic partner was also studied. Aphids do not appear to be preferentially attracted toward a host plant frequented by ants or close an ant nest. Nevertheless, once a potential host plant reached, they remain longer on it in case of ant presence. This thesis highlights the importance of volatile semiochemicals and honeydew microflora in ant-aphid mutualistic relationships, thus completing by a new aspect an already well documented biological model. [less ▲]

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See detailL'étude des sémiochimiques. Applications en écologie chimique
Heuskin, Stéphanie ULg

Scientific conference (2014, December)

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See detailL'étude des sémiochimiques. Applications en écologie chimique
Heuskin, Stéphanie ULg

Scientific conference (2013, November 21)

Detailed reference viewed: 13 (0 ULg)
See detailEtude des séries chronologiques par la méthode de Box et Jenkins
Palm, Rodolphe ULg

in Notes de Statistique et d'Informatique (1987), 2

This note briefly describes the BOX-JENKINS methodology for time series analysis. The method is illustrated by an example analyzed with the Minitab software.

Detailed reference viewed: 83 (4 ULg)
See detailEtude des séries chronologiques par les méthodes de décomposition
Palm, Rodolphe ULg

in Notes de Statistique et d'Informatique (1987), (1), 25

This note briefly describes the main methods of analyzing time series by a decomposition into a trend, a seasonal variation, and residuals. The methods are illustrated by an example analyzed with the ... [more ▼]

This note briefly describes the main methods of analyzing time series by a decomposition into a trend, a seasonal variation, and residuals. The methods are illustrated by an example analyzed with the Minitab sofware. [less ▲]

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See detailEtude des séries chronologiques par les méthodes de décomposition
Palm, Rodolphe ULg; Brostaux, Yves ULg

in Notes de Statistique et d'Informatique (2009), (1), 1-17

This note briefly describes the main methods of analysing time series by a decomposition into a trend, a seasonal variation, and residuals. The methods are illustrated by an example analysed with Minitab ... [more ▼]

This note briefly describes the main methods of analysing time series by a decomposition into a trend, a seasonal variation, and residuals. The methods are illustrated by an example analysed with Minitab software. [less ▲]

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See detailEtude des séries chronologiques par les méthodes de lissage
Palm, Rodolphe ULg

in Notes de Statistique et d'Informatique (2007), (1), 1-22

This note briefly describes forecasting procedures for time series based on smoothing techniques. The following procedures are examined : exponential smoothing for non-seasonal time series showing no ... [more ▼]

This note briefly describes forecasting procedures for time series based on smoothing techniques. The following procedures are examined : exponential smoothing for non-seasonal time series showing no trend, Holt procedure for non-seasonal time series with trend and Holt-Winters procedure for time series containing trend and seasonal variation. The methods are illustrated by an example processed with Minitab software. [less ▲]

Detailed reference viewed: 73 (6 ULg)
Peer Reviewed
See detailEtude des sollicitations et des mouvements tourbillonnaires autour des colonnes d'une plate forme océanique sous l'action de courants alternés
Marchal, Jean ULg; Lejeune, A.; Davister, G.

in Bulletin de l'Association Technique Maritime et Aéronautique (1978)

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See detailEtude des structures élastiques anisotropes pouvant être incompressibles et application à un élément fini de tore triangulaire
Debongnie, Jean-François ULg

Report (1975)

This paper presents the extension of herrmann's formulation to all cases, isotropic or not, where the local flexibility matrix presents at most one singularity, that is an isotropic pressure. Starting ... [more ▼]

This paper presents the extension of herrmann's formulation to all cases, isotropic or not, where the local flexibility matrix presents at most one singularity, that is an isotropic pressure. Starting from Reissner's principle, a matrix is introduced, which behaves as the inverse of the flexibility matrix for any deviatoric stress. This matrix may be obtained in a full-automatic scheme. Then, a triangular tor element is developped from this formulation. Finally, tests are presented. [less ▲]

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See detailEtude des sulfonylurées en traitement de postémergence au printemps en culture d'escourgeon.
Bodson, Bernard ULg; Salembier, Jean-François; Gomand, Michel

in Mededelingen van de Faculteit Landbouwwetenschappen (Rijksuniversiteit te Gent) (1991, May 07), 56(3a), 719-726

Durant 2 années d'essais 1989 et 1990 les sulfonylurées les plus couramment utilisées en froment d'hiver ont été comparées dans la culture d'escourgeon en traitement de postémergence au printemps.La ... [more ▼]

Durant 2 années d'essais 1989 et 1990 les sulfonylurées les plus couramment utilisées en froment d'hiver ont été comparées dans la culture d'escourgeon en traitement de postémergence au printemps.La sélectivité des produits seuls et de quelques associations de ces matières actives entre elles a été étudiée avec les produits appliqués seuls ou en mélange avec de l'isoproturon. Par rapport au metsulfuron-méthyl, au tribenuron-méthyl et au triasulfuron, le thifensulfuron-méthyl seul ou associé au métsulfuron-méthyl ou au tribenuron-méthyl a montré un manque de sélectivité. [less ▲]

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See detailL'etude des taxocenoses de carabides (Coleoptera) dans un parc periurbain (Parc Tournay-Solvay a Boitsfort)
Janssens, B.; Dufrêne, Marc ULg

in Annales - Societe Royale Zoologique de Belgique (1988), 118

Emphasises the important role of substratum humidity in spatial distribution of species and in population. The open biotope also provides an explanatory factor. -from English summary

Detailed reference viewed: 7 (5 ULg)