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See detailAbout almost periodic sequences of integers and related concepts
Crama, Yves ULg

Scientific conference (2014, May 07)

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See detailCOMPARISON AND MOLECULAR CHARACTERIZATION OF ANIMAL AND HUMAN CLOSTRIDIUM DIFFICILE STRAINS
Rodriguez Diaz, Cristina ULg; Taminiau, Bernard ULg; Korsak Koulagenko, Nicolas ULg et al

Poster (2014, May 07)

The main objective of this study was to characterize and compare animal and human C. difficile strains with respect to the PCR-ribotype and the antibiotic resistance. Multilocus sequence typing analysis ... [more ▼]

The main objective of this study was to characterize and compare animal and human C. difficile strains with respect to the PCR-ribotype and the antibiotic resistance. Multilocus sequence typing analysis (MLST) was performed in order to study clonal relationships of the isolates. [less ▲]

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See detailContributions à l’amélioration des systèmes d’évaluations génétiques
Vanderick, Sylvie ULg; Gengler, Nicolas ULg

Conference given outside the academic context (2014)

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See detailL'Etat congolais souverain ou sous-tutelle? Essai d'analyse de la dynamique politique nationale.
Baenda Fimbo, Zacharie ULg

Scientific conference (2014, May 07)

Après la définition de certains concepts tels que l'Etat, la souveraineté et la tutelle, la présente communication a analysé la dynamique politique congolaise à travers l'histoire. De la première ... [more ▼]

Après la définition de certains concepts tels que l'Etat, la souveraineté et la tutelle, la présente communication a analysé la dynamique politique congolaise à travers l'histoire. De la première république à la troisième. Des interventions étrangères ayant divisé les leaders politiques congolais pendant la première législative à la présence quasi permanente de la Communauté internationale à travers la Mission des Nations Unies au Congo, en passant par la deuxième république de Mobutu, les réalités locales laissent voir que certaines décisions politiques, voire certaines prises de position sont dictées de l'étranger. Les faits analysés fait douter l'applicabilité de la notion de souveraineté à la gestion politique de l'Etat congolais. [less ▲]

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See detailPolitiques institutionelles et migrations. Quelle place les institutions belges laissent-elles à la diversité ?
Grandjean, Geoffrey ULg

Conference given outside the academic context (2014)

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See detailLa Cour européenne des droits de l'homme
Habran, Maxime ULg

Scientific conference (2014, May 07)

Cette conférence vise à mettre en perspective la liberté d'expression dans le cadre des arrêts de la CEDH

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See detailAvancées récentes dans l'investigation olfactive de la mort
Stefanuto, Pierre-Hugues ULg; Focant, Jean-François ULg

Scientific conference (2014, May 07)

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See detailÉcrire les «petites langues»: entre transparence et universalisme
Baiwir, Esther ULg

Conference (2014, May 06)

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See detailL'astaxanthine: de la biologie à l'industrie
Fratamico, Anthony ULg

Scientific conference (2014, May 06)

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See detailStudy of the microbial flora of steak tartare by metagenomic approach
Korsak Koulagenko, Nicolas ULg; Delhalle, Laurent ULg; Nezer, Carine et al

Poster (2014, May 06)

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See detailHas oxygen depletion an impact on nutrients and macrofauna in a highly dynamic macrophytodetritus accumulation?
Remy, François ULg; Mascart, Thibaud ULg; Dauby, Patrick ULg et al

Poster (2014, May 06)

Posidonia oceanica is an endemic Mediterranean highly productive seagrass. Depending on the ability of the primary consumers to digest it alive, a generally important part of its foliar primary production ... [more ▼]

Posidonia oceanica is an endemic Mediterranean highly productive seagrass. Depending on the ability of the primary consumers to digest it alive, a generally important part of its foliar primary production falls in autumn, to decay inside the meadow or to be exported to sand patches to form “exported litter accumulations”. These accumulations are highly dynamic depending on hydrodynamics and seafloor geomorphology. Literature says that low O2 conditions might occur inside litter accumulations, but the annual oxygen dynamics or its impact on the litter-associated macrofauna has never been measured. We focused on 2 exported litter accumulations in Calvi Bay (Corsica), during 2 years for a total of 8 seasons. For each season, we collected water samples (n=6) from 3 different strata: Water Column (WC), Water Just Above the litter (WJA) and Water Inside the litter (WI). Oxygen was measured for each replicate using a Winkler-based automated routine for oxygen concentration measurements on micro-volumes. At the same time, nutrients concentrations (PO4, NH4, and NO2+NO3) were measured in WC, WJA and WI, but also in the Interstitial Water (IW) using a spectrophotometric continuous flow analyzer (adapted for low nutrients level in an oligotrophic environment). In parallel, macrofaunal (size >500µm) samples (n=3-6) were also collected, counted and identified to the specific level. Our results show significant differences between O2 concentrations/saturation from WI and the two other strata. Significant differences were detected between seasons, sites and years for WI which is the only stratum where really low O2 conditions can be observed. Significant differences were also detected between seasons for both WC and WJA but no differences between sites and years. On the other hand no significant differences were detected between WC and WJA. A similar observation was made for the nutrients at the annual, seasonal and spatial level. Moreover differences are also observed between the nutrients themselves. Our data shows no correlation between WI O2 concentrations and saturation, and global macrofauna abundance or biodiversity. Results are more contrasting at an individual specific level for the 4 most dominant species. For two amphipod species, Gammarella fucicola (55% of the global abundance) and Gammarus aequicauda, no significant correlations were detected between their abundance and O2. For the leptostracan species, Nebalia strausi, a significant negative correlation with O2 concentration was detected. For the last amphipod species, Melita hergensis, a significant positive correlation was observed. Our analyses also show significant correlations between WI O2 concentration/saturation, and WI / IW nutrients concentration. To conclude, this work shows that WI is a very particular and dynamic environment considering O2 concentration and saturation. Low O2 conditions can be observed in WI but never in WC or WJA showing that internal processes and relations with the sediment determine the O2 dynamics in WI and showing a potential “barrier” effect between WI and WC. Moreover O2 dynamics and its consequences may play a role in the nutrients dynamics and cycles. It is clear that faunal responses to low O2 conditions are not identifiable at a global community level. At a specific level, we show a more complex situation: some species do not seem to be impacted by low O2 conditions, but some present a significant positive, or a significant negative response. This shows the existence and complexity of species-dependent low O2 tolerance/adaptation, and the importance of a specific level data analyses to detect responses of dominant litter associated macro- invertebrates to O2 concentration and saturation variations. [less ▲]

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See detailLa Spiruline : a star is born (a long time ago)
de Marchin, Thomas ULg

Scientific conference (2014, May 06)

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See detailNew perspectives on probabilistic methods for nonlinear transient dynamics in civil engineering
Canor, Thomas ULg

Doctoral thesis (2014)

The objective of this thesis is to develop probabilistic methods to perform nonlinear transient analysis in civil engineering applications. The manuscript is divided into two parts. For large-dimensional ... [more ▼]

The objective of this thesis is to develop probabilistic methods to perform nonlinear transient analysis in civil engineering applications. The manuscript is divided into two parts. For large-dimensional structures subject to coherent random loads, an asymptotic expansion-based method is used to improve linear evolutionary spectral analysis. Then, this method is extended to equivalent statistical linearization by a multiple timescales approach. The second part of the thesis is focused on small-dimensional systems. It explores the solution of the Fokker-Planck equation with the smoothed particle hydrodynamics method. This meshless Lagrangian method particularly ensures the conservation and the positivity of the probability field. The accuracy and efficiency of both approaches are compared with Monte-Carlo simulations. [less ▲]

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See detailApprentissages et scolarité des primo-arrivants
Defays, Jean-Marc ULg

Conference given outside the academic context (2014)

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See detailIdentification et rôle des médiateurs sonores dans les phases de colonisation et d’installation de poissons dans un environnement corallien
Berten, Laetitia ULg

Doctoral thesis (2014)

La majorité des poissons de récifs coralliens présentent un cycle de vie complexe, caractérisé par une phase larvaire pélagique dispersive en milieu océanique, suivie d’une phase benthique au sein du ... [more ▼]

La majorité des poissons de récifs coralliens présentent un cycle de vie complexe, caractérisé par une phase larvaire pélagique dispersive en milieu océanique, suivie d’une phase benthique au sein du lagon ou sur la pente externe du récif. Ce travail porte sur l'influence du stimulus sonore lors de la colonisation et de l'installation, au sein du récif, des larves de poissons. De récentes études ont montré un effet attracteur du son de récifs sur les larves de poissons et de crustacés. Mais on ignore encore la distance à laquelle les larves sont capables de repérer le son du récif, ni si elles sont attirées par une signature spectrale complexe ou plus simplement par la présence d'un "bruit". Enfin, on ignore si les différents habitats d’un récif peuvent présenter des signatures acoustiques propres, ni si les sons des habitats peuvent guider les larves lors de leur installation au sein du récif. L'étude de mesures de pression sonore le long de trois transects de 2 km effectuées sur la côte nord de l'île de Moorea (Polynésie Française) met en évidence une diminution régulière de l'intensité sonore jusqu'à une distance à la crête de 750-1000 m. Au-delà de cette distance, et jusqu'à 2 km, une augmentation graduelle de la pression sonore est observée. Dès lors, une larve située à 750-1000 m du récif se retrouve confrontée à deux gradients de pression, l'un dirigés vers l'océan et l'autre vers le récif, et devra faire appel à d'autres stimuli pour s'orienter vers ce dernier. Au sein du récif, les sons provenant de 5 habitats de Moorea (crête interne, récif barrière, récif frangeant, chenal et mangrove) ont été étudiés. Les signatures sonores de chaque habitat (hormis crête interne et récif barrière) diffèrent des autres sur une certaine gamme de fréquences, et ces différences sont conservées avec la distance (plusieurs km). De plus, l'étude de l'influence des sons d'habitats et d'un son artificiel sur le comportement des larves met en évidence une modification du comportement chez 16 des 20 espèces testées. Les différentes réponses illustrent deux stratégies d'installation sur base du son: soit une sélection directe de l'habitat, soit un évitement de certains habitats, et donc une sélection "par défaut" des habitats restants. Pourtant, les niveaux de pression sonore des habitats du lagon sont sous les seuils de capacités sonores des juvéniles d'Abudefduf vaigiensis, Acanthurus triostegus, Chaetodon citrinellus, Rhinecanthus aculeatus et Myripristis kuntee. Ce paradoxe nous pousse à remettre en question l'utilisation de l'outil "ABR" (Auditory Brainstem Response) dans les études de perception et d'influence des sons sur le comportement des poissons. [less ▲]

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See detailPassive temperature tomography experiments to characterize transmissivity and connectivity of preferential flow paths in fractured media
Klepikova, Maria ULg

in Journal of Hydrology (2014)

The detection of preferential flow paths and the characterization of their hydraulic properties are major challenges in fractured rock hydrology. In this study, we propose to use temperature as a passive ... [more ▼]

The detection of preferential flow paths and the characterization of their hydraulic properties are major challenges in fractured rock hydrology. In this study, we propose to use temperature as a passive tracer to characterize fracture connectivity and hydraulic properties. In particular, we propose a new temperature tomography field method in which borehole temperature profiles are measured under different pumping conditions by changing successively the pumping and observation boreholes. To interpret these temperature-depth profiles, we propose a three step inversion-based framework. We consider first an inverse model that allows for automatic permeable fracture detection from borehole temperature profiles under pumping conditions. Then we apply a borehole-scale flow and temperature model to produce flowmeter profiles by inversion of temperature profiles. This second step uses inversion to characterize the relationship between temperature variations with depth and borehole flow velocities (Klepikova et al., 2011). The third inverse step, which exploits cross-borehole flowmeter tests, is aimed at inferring inter-borehole fracture connectivity and transmissivities. This multi-step inverse framework provides a means of including temperature profiles to image fracture hydraulic properties and connectivity. We test the proposed approach with field data obtained from the Ploemeur (N.W. France) fractured rock aquifer, where the full temperature tomography experiment was carried out between three 100 m depth boreholes 10 m apart. We identified several transmissive fractures and their connectivity which correspond to known fractures and corroborate well with independent information, including available borehole flowmeter tests and geophysical data. Hence, although indirect, temperature tomography appears to be a promising approach for characterizing connectivity patterns and transmissivities of the main flow paths in fractured rock. [less ▲]

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