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See detailAstrophysical parameters and multiplicity of massive stars: a mathematical approach
Mahy, Laurent ULg

Doctoral thesis (2011)

Often quoted for their crucial role in the ecology of galaxies, massive stars remain mysterious. The exact process leading to their formation, their stability or their stellar winds are so many questions ... [more ▼]

Often quoted for their crucial role in the ecology of galaxies, massive stars remain mysterious. The exact process leading to their formation, their stability or their stellar winds are so many questions which are still unanswered. Since the lifetime of these objects is too short to allow them to move far away from their birth places, the large majority of massive stars are located in young open clusters or in OB associations. The observations of massive stars in these locations thus provide with promising information on their formation mechanisms. One of the most interesting properties, in this context, is their multiplicity. Indeed, the proportion of multiple systems, the values of orbital periods, of eccentricities, or of mass ratios are parameters directly linked to the formation mechanism and to the dynamical interactions occurring during the earliest stages of their existence. Moreover, constraining this multiplicity with a sufficient accuracy allows to obtain a better determination of the nature and physical parameters of massive stars. The present work is devoted to the study of the O star populations located in the young open cluster NGC2244 and in the surrounding Mon OB2 association as well as in several OB associations of the Cygnus complex. We establish not only the multiplicity of about thirty stars but also their fundamental parameters such as their masses or their N content. However, the complexity of observed spectra of multiple systems makes these objects difficult to investigate. Their analysis thus requires the development and the utilization of mathematical tools such as the "disentangling" which allows to separate the spectra of the components from the observed ones or such as the Doppler tomography which aims at mapping the wind interactions seen in some binary systems. The first part of this dissertation is dedicated to the development and to the characterization of these mathematical methods whilst the second part focuses on the study of populations of massive stars. We refine the orbital and physical parameters of systems already known as multiple. In this context, the analysis of the two components of LZ Cep system reveals modified abundances for the secondary star, confirming a mass transfer from the secondary towards to primary. We also detect for the first time a third star in the HD150136 system. This object, composed of an O3, an O5.5 and an O6.5, constitutes a new test to apply these mathematical methods and thus to better constrain the physical properties of the system as well as those of each component. Moreover, we find, in the population of NGC2244, of Mon OB2 and of the Cygnus OB associations, six new binary systems and derive the orbital solutions for five of them. These results show that NGC2244 hosts only one long-period binary and none with a short period whilst four short-period and no long-period systems are detected in the Cygnus complex. This obvious lack of short-period system in NGC2244 contrasts with the O star populations in other young open clusters such as NGC6231 or IC 2944. Besides the multiplicity, the fundamental parameters such as the N content also allows us to, notably, adapt the so-called Hunter-diagram to galactic O stars. Moreover, we have obtained photometric data for six O-type stars in NGC2244 and Mon OB2 with the CoRoT satellite. These data of unprecedented quality allow us to detect the presence, in the O star light curves, of red noise which is supposed to originate from either the sub-surface convection zone, the granulation or an onset of clumping in the winds of the stars. We also highlight the existence of non-radial pulsations in the light curve of Plaskett’s Star as well as a hot spot located between the two components of that system. In addition, numerous frequencies, extracted from the CoRoT light curves, reveal, for some of the observed stars, solar-like oscillations or beta Cephei-like pulsations. This analysis thus gives a first observational constraint on the bright end of the massive star instability strip. [less ▲]

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See detailExpressions et territoires politico-religieux- le cas des Eglises de Réveil (RDC et diaspora
Demart, Sarah ULg

Scientific conference (2011, December 12)

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See detailCASUS 2011 - Droit administratif
Durviaux, Ann-Lawrence ULg

Learning material (2011)

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Peer Reviewed
See detailSinging the ‘dagong’ via the web: suffering, longings and ideals. An exploration of the everyday politics of migrant labour in South China
Florence, Eric ULg

Conference (2011, December 10)

Since the 1980s, new forms of labour, new subjectivities and attitudes related to the market and to flexible capitalism have been more and more prized in the PRC coexisting with older strands of ... [more ▼]

Since the 1980s, new forms of labour, new subjectivities and attitudes related to the market and to flexible capitalism have been more and more prized in the PRC coexisting with older strands of narratives and cultural productions linked to Mao-era state-socialism. The process of cultural re-invention and of contention around “migrant labour” provides a particularly interesting vintage point in order to delve into the twin dynamics of rural workers’ unstable identification processes (at the individual and collective levels) and at the state project of legitimation. Within this paper, I intend to explore how the new media cultures inform and relate to the cultural politics of migrant labour in today’s China, including the shaping of new subjectivities, by examining rural workers’ use of the internet to narrate both their hometown and their experience of labour. I will look specifically at the everyday politics of rural workers’ practices of “song writing” via the internet and will delve upon the following questions: how does this practice of song writing/listening inform the politics of identity formation among rural labourers? how can one relate rural migrant workers’ song writing to the increasingly “on the ground” organized waves of labour protests in South China? I will argue that the virtual space which this practice provides a useful vintage point in order to examine how state and non-state actors can engage each other and how the Party-state is constantly re-inventing novel ways to shape its system of ideological signs. The datas used for this paper will include songs and poems by rural workers, an extensive analysis by the author of the Shenzhen mainstream written press, participant observation, in-depth interviews, and a large body of unpublished letters to the editor of several migrants’ magazines. [less ▲]

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See detailThe future in the present: "entangled temporalities" and religious life in the Kimbanguist church
Melice, Anne ULg; Sarró, Ramon

Conference (2011, December 09)

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Peer Reviewed
See detailGestion des ressources génétiques animales par les éleveurs de dromadaires de la région d’Ansongo (Mali).
Traore, Bakary; Ouologuem, Bara; Antoine-Moussiaux, Nicolas ULg et al

Poster (2011, December 09)

Detailed reference viewed: 33 (6 ULg)
See detailLe Forem et son service de relations partenariales
Remy, Céline ULg

Conference given outside the academic context (2011)

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See detailClostridium difficile in farm and slaughterhouse animals: prevalence and typing
Rodriguez Diaz, Cristina ULg; Taminiau, Bernard ULg; van Broeck, Johan et al

Scientific conference (2011, December 09)

Clostridium difficile is an anaerobic gram-positive spore-forming bacillus identified as a severe pathogenic agent in animals and humans. Its recent isolation in foods opens up the occurrence of ... [more ▼]

Clostridium difficile is an anaerobic gram-positive spore-forming bacillus identified as a severe pathogenic agent in animals and humans. Its recent isolation in foods opens up the occurrence of alimentary origin infections. The objective of the study is to establish if there is a reservoir of bacteria in animals engaged to human feed and consequent true risk of transmission to humans through the food chain. A total of 437 fecal samples were analyzed. Stools (202 from beef and 194 from pigs) were collected at the slaughterhouse and from breeding farms (18 from calves and 23 from piglets). Enrichment culture was carried out using a cycloserine cefoxitin fructose taurocholate broth. Isolates were identified by PCR detection of tpi, tcdA, tcdB and cdtA genes. Toxic activity was confirmed by a fecal cytotoxin inmmunoessay. Further characterization was performed by PCR ribotyping. Clostridium difficile was cultured from 8% (35/437) of the total samples: 14 from beef at slaughterhouse (6,9%), 17 from piglets (73,9%) and 4 from calves (22,2%) at breeding farms. Thirty-two of the total strains were toxin positive. Sixteen different PCR ribotypes were identified with type 078 predominant in breeding farms of calves (75%) and pigs (64,7%). Isolates from beef presented widest range in ribotypical variety. Present study proves the presence of Clostridium difficile in animals engaged to food in Belgium. The presence of the bacteria at the slaughterhouse and the high prevalence of pathogenic strains states a true risk of contamination to humans through the food chain. [less ▲]

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See detailTechnique(s), médiation et politique chez Georges Canguilhem (II)
Pieron, Julien ULg

Scientific conference (2011, December 09)

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See detailKnowledge and its value
Janvier, Antoine ULg; Leclercq, Bruno ULg

Conference (2011, December 09)

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See detailEvaluation comparative des statuts de races de poules locales : Algérie, Vietnam, Congo (RDC).
Moula, Nassim ULg; Antoine-Moussiaux, Nicolas ULg; Salhi, Abdellah et al

Conference (2011, December 09)

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See detailMyeloid HIF-1alpha prevents airway allergy in mice by promoting macrophage-mediated immunosuppression
Toussaint, Marie ULg; Fievez, Laurence ULg; Lekeux, Pierre ULg et al

in Proceedings of the 1st Scientific Meeting of the Faculty of Veterinary Medicine (2011, December 09)

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See detailPaysage et développement territorial, apports et limites de la démarche de projet local de paysage. Le cas de la Wallonie (Belgique)
Droeven, Emilie ULg

Conference (2011, December 09)

The European Landscape Convention acknowledges landscape as a key element in territorial development, management and planning (assessment of the effects of certain public and private projects on the ... [more ▼]

The European Landscape Convention acknowledges landscape as a key element in territorial development, management and planning (assessment of the effects of certain public and private projects on the environment, re-landscaping, landscape projects design, charters…). Based on a doctoral research investigating the processes of landscape project design on a local scale in Wallonia (Belgium) in Nature Parks, Local Action Groups or River Contracts, the paper tries to analyze how landscape influences territorial practices and issues. It aims also to produce an evaluation on how landscape action transforms territorial governance and decision-making process. In doing so, the paper relates landscape project contributions and limits assuming new landscape management challenges. And finally, it reframes the contribution of the landscape issue to regional and local development. [less ▲]

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See detailDécoder les nouveaux instruments de gestion de l’enseignement supérieur
Fallon, Catherine ULg

Scientific conference (2011, December 09)

Les processus de gestion de la qualité sont relativement récents dans l'enseignement universitaire en Belgique francophone. Sous la pression européenne, avec le soutien des responsables des universités ... [more ▼]

Les processus de gestion de la qualité sont relativement récents dans l'enseignement universitaire en Belgique francophone. Sous la pression européenne, avec le soutien des responsables des universités, les autorités ont mis en places des dispositifs d''évaluation tout à fait nouveaux. Après quelques années de rodage, ces instruments semblent se stabiliser, bien qu'ils continuent encore à susciter çà et là des réactions de rejet. Pour mieux comprendre ces dynamiques, c'est par la base qu'il convient de démarrer l'analyse, pour suivre au plus près les instruments d'évaluation, leur mode d'emploi et comprendre leurs effets inattendus au sein des universités, mais pour observer l'émergence de nouveaux modes de coordination entre universités, avec l'administration, ou avec les autres acteurs sociaux. Ce chapitre présente en détail le processus d'évaluation, après un bref rappel de ses origines et du contexte qui a favorisé son émergence. Ensuite, il proposera un analyse transversale de cet instrument d'action publique : en quoi les nouvelles formes de coopération qui se mettent en place sont emblématiques à la fois d'un nouveau rapport entre gouvernants et gouvernés mais aussi entre les universités et la société qui les nourrit tout en lui fiant leurs enfants. [less ▲]

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See detailLes races de poules belges de grande taille
Moula, Nassim ULg; Jacquet, Michel; Verelst, Andy et al

Poster (2011, December 09)

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See detailZoonotic diseases in pet birds -a short review
Boseret, Géraldine ULg

Poster (2011, December 09)

The term « Pet bird » designates birds housed and breeded for an exclusively ornamental use. This category includes mainly Passeriformes (canaries, finches…) and Psittaciformes (parrots, parakeets…), and ... [more ▼]

The term « Pet bird » designates birds housed and breeded for an exclusively ornamental use. This category includes mainly Passeriformes (canaries, finches…) and Psittaciformes (parrots, parakeets…), and is a not-so-well known vet’s clientship fraction. Many families indeed own their « kitchen canary », which represent a lucrative business for pet shops or local breeders (e.a. via birds fairs and markets). Besides, some birds are bred for their very high value; for example, in the case of canaries, male and female reproductors with recognized genetic potential are presented in international contests for their posture (the Bossu Belge : fig 1a), their colour (red mosaic: fig 1b) and for their song (Harzer: fig 1c) and sold for rising prices. Finally, exotic birds like parrots (ara, cockatoo…), legally or illegaly traded from Asia, are however very popular pets and profusely represented in zoos and parks. Notwithstanding these economic facts, these animals are potential carriers and/or transmitters of zoonotic diseases. Some of them could have an important impact on human health, like ornithosis, salmonellosis or even H5N1 high pathogenic avian influenza. This review, although non exhausive, has as aim to enlighten, by the description of several cases of birds-humans transmission the risks encountered by birds owners, including children, and on another point of view to assess the potential economic consequences. [less ▲]

Detailed reference viewed: 128 (9 ULg)