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See detailContribution to the study on sound production in clownfishes (Perciformes, Pomacentridae): a multidisciplinary approach
Colleye, Orphal ULg

Doctoral thesis (2011)

Clownfishes (Amphiprion spp.) are brightly colored fishes that are members of the Pomacentridae family. They are well known for their mutualistic relationship with tropical sea anemones. These fishes live ... [more ▼]

Clownfishes (Amphiprion spp.) are brightly colored fishes that are members of the Pomacentridae family. They are well known for their mutualistic relationship with tropical sea anemones. These fishes live in social groups in which there is a size-based dominance hierarchy. In this structure where sex is socially controlled, agonistic interactions are numerous and serve to maintain size differences between individuals adjacent in rank. Several studies have reported that vocalizations are associated with agonistic interactions but precise data are lacking and further investigations are needed. The nature of the sound-producing mechanisms also remained unresolved, only resting on few assumptions. Thereby, the main aim of the present thesis is (1) to determine the fundamental components of the acoustic communication in clownfishes, and (2) to explain the mechanisms of sound production. In order to achieve these objectives, the research has been divided into three different axes. Firstly, the study of the acoustic behaviors shows that no acoustic signal is associated with reproductive activities in clownfishes. Sound recordings during agonistic interactions indicate that these fishes produce two types of sounds. Aggressive sounds are produced during chases and threat displays while submissive (or head shaking) sounds are emitted in reaction to aggressive acts by dominant. Both types of sounds show size-related intraspecific differences in dominant frequency and pulse duration: smaller individuals produce higher frequency and shorter duration pulses than larger individuals, and inversely. Consequently, these sonic features might be useful cues for individual recognition and maintenance of cohesion within the group. Secondly, the study of the sound-producing mechanism highlights that aggressive sounds are initiated by buccal jaw teeth snapping caused by rapid mouth closure attributed to a sonic ligament. It appears that the swimbladder does not function as a resonator that amplifies and changes the quality of sounds. This structure is a highly damped sound source prevented from prolonged resonant vibrations. On the other hand, the rib cage might be the major acoustic radiator and its resonant properties might explain the size-related variations observed in pulse duration and dominant frequency. Thirdly, the comparison of aggressive sounds among fourteen clownfish species indicates that the same relationship between fish size and both dominant frequency and pulse duration is spread over the entire group (i.e. tribe Amphiprionini). These results highlight all species use a highly conservative mechanism of vocalization. Pulse period appears to be the most variable acoustic feature and could be involved in species-specific recognition, as well as pulse duration and dominant frequency in a lesser extent through their relationship with body size. Although sound production appears to be restricted to some agonistic behaviors, these sounds seem to constitute an integral part of the peculiar way of life of clownfishes. The aggressive and submissive sounds would also result from two different mechanisms.   [less ▲]

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See detailContribution to the valorisation of pomegranate (Punica granatum L.)
Bchir, Brahim ULg; Roiseux, Olivier; Attia, Hamadi et al

Poster (2007, October 11)

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See detailContribution to the valorization of^pomegranate (Punica granatum L.)
Bchir, Brahim; Roiseux, Olivier; Attia, Hamadi et al

Poster (2007, October 11)

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See detailContribution to the water disinfection study by photosensitization with plants extracts.
Sunda, M.; Rosillon, Françis ULg; Taba, K. M.

in European Journal of Water Quality = Journal Européen d’Hydrologie (2008), 39(2), 199-209

Solar water disinfection study using plants extracts, in tryptophan media (1%), has revealed a photodynamic activity of Cassia alata, Cassia occidentalis, Carica papaya, Phyllantus niruri and Coleus ... [more ▼]

Solar water disinfection study using plants extracts, in tryptophan media (1%), has revealed a photodynamic activity of Cassia alata, Cassia occidentalis, Carica papaya, Phyllantus niruri and Coleus kilimandschari aqueous extracts. Aqueous extracts of Lantana camara, Cymbopogon citratus and Hibiscus rosa-sinensis produce a bactericidal effect. Water disinfection by alkaloid extracts of Cassia alata, Cassia occidentalis, Carica papaya, Phyllantus niruri and Coleus kilimandschari shows a bactericidal effect. On the other hand, unalkaloid extracts of the same compounds especially present a photodynamic activity. The photodynamic activity of unalkaloid extract is due to the presence of quinones and anthraquinones which generate singlet oxygen.The singlet oxygen generated attacks and damages the microorganisms contained in polluted water. The necessary sunlight time for coliform inactivation and other germs is one hour for 2 ml of extracts/liter of polluted water. [less ▲]

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See detailcontribution to understanding of sedimentological and diagenetic processus related to a major emersive surface : example of the middle paleocene unconformity (MPU).
Loisy, Corinne; Kiefer-Ollier, Eloise; Cerepi, Adrian et al

in Book of Abstracts - 26th IAS meeting, Alghero, Sardenia (2009)

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See detailContribution to understanding of sedimentological and diagenetic processus related to major emersive surfaces and their spatial variation
Loisy, Corinne; Da Silva, Anne-Christine ULg; Kieffer, Eloise et al

in Book of Abstracts - 25th meeting of the IAS, Patras, Greece (2007)

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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 detailContributions à l'anatomie et à l'histologie des Echinides
Fredericq, Léon ULg

in Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences (1876), LXXXIII

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See detailContributions à l’Etude de la Relation Evolutive entre deux Herpèsvirus d’Artiodactyles Africains : l’Herpèsvirus Bovin 4 et l’Herpèsvirus Alcélaphin
Dewals, Benjamin G ULg

Doctoral thesis (2006)

Alcelaphine herpesvirus 1 (AlHV 1), carried by wildebeest asymptomatically, causes malignant catarrhal fever (MCF) when cross species transmitted to a variety of susceptible species of the Artiodactyla ... [more ▼]

Alcelaphine herpesvirus 1 (AlHV 1), carried by wildebeest asymptomatically, causes malignant catarrhal fever (MCF) when cross species transmitted to a variety of susceptible species of the Artiodactyla order. There is no available vaccine against AlHV-1. Several studies suggested that the African buffalo (Syncerus caffer) rather than cattle should be considered as the natural host species of bovine herpesvirus 4 (BoHV 4), an apathogenic gammaherpesvirus that is antigenically related to AlHV 1. Rossiter and co-workers (1989) suggested that an evolutionary relationship exists between AlHV 1 and BoHV 4. This hypothesis proposes that the serological antigenic relationship existing between BoHV 4 and AlHV 1 could confer to BoHV 4 infected buffaloes a protective immune response against lethal AlHV 1 infection. In this work, our goal was to generate information and tools that are required to test this hypothesis in the future. Our results are presented as three original studies: (i) Cloning of the alcelaphine herpesvirus 1 genome as an infectious and pathogenic bacterial artificial chromosome Journal of General Virology (2005), in press Dewals B., Boudry C., Gillet L, Markine-Goriaynoff N., de Leval L., Haig D.M. & Vanderplasschen A. Alcelaphine herpesvirus 1 (AlHV 1), carried by wildebeest asymptomatically, causes malignant catarrhal fever (MCF) when cross species transmitted to a variety of susceptible species of the Artiodactyla order. The study of MCF pathogenesis has been impeded by an inability to produce recombinant viruses, due mainly to the fact that AlHV 1 becomes attenuated during passage in culture. In this study, we have overcome these difficulties by cloning the entire AlHV 1 genome as a stable, infectious and pathogenic bacterial artificial chromosome (BAC). A modified loxP flanked BAC cassette was inserted in one of the two large non-coding regions of the AlHV 1 genome. This insertion allowed the production of an AlHV 1 BAC clone stably maintained in bacteria and able to regenerate virions when transfected into permissive cells. The loxP-flanked BAC cassette was excised from the genome of reconstituted virions by growing them in permissive cells stably expressing Cre recombinase. Importantly, BAC derived AlHV 1 virions replicated comparably to the virulent (low passage) AlHV 1 parental strain and induced MCF in rabbits that was indistinguishable from that of the virulent parental strain. The availability of the AlHV 1 BAC is an important advance for the study of MCF that will allow the identification of viral genes involved in MCF pathogenesis as well as the production of attenuated recombinant candidate vaccines. (ii) Antibodies against bovine herpesvirus 4 are highly prevalent in wild African buffaloes throughout eastern and southern Africa Veterinary Microbiology, 2005, 110, 209-220 Dewals B., Gillet L., Gerdes T., Taracha E.L.N., Thiry E. & Vanderplasschen A. Bovine herpesvirus 4 (BoHV 4) has been isolated from cattle throughout the world. Interestingly, a survey of wild African buffaloes mainly from the Maasai Mara Game Reserve in Kenya revealed that 94 % of the animals tested had anti BoHV 4 antibodies (Rossiter et al., Res. Vet. Sci., 1989, 46, 337 343). These authors also proposed that the serological antigenic relationship existing between BoHV 4 and alcelaphine herpesvirus 1 (AlHV 1) could confer to BoHV 4 infected buffaloes a protective immune response against lethal AlHV 1 infection. In the present study, we addressed two questions related to Rossiter et al. paper. Firstly, to investigate the role of the African buffalo as a natural host species of BoHV 4, the seroprevalence of anti BoHV 4 antibodies was analysed in wild African buffaloes throughout eastern and southern Africa. A total of 400 sera was analysed using two complementary immunofluorescent assays. These analyses revealed that independently of their geographical origin, wild African buffaloes exhibit a seroprevalence of anti BoHV 4 antibodies higher than 68 %. This result is by far above the seroprevalence generally observed in cattle. Our data are discussed in the light of our recent phylogenetic study demonstrating that the BoHV 4 Bo17 gene has been acquired from a recent ancestor of the African buffalo. Secondly, we investigated the humoral antigenic relationship existing between BoHV 4 and AlHV 1. Our results demonstrate that among the antigens expressed in AlHV 1 infected cells, epitope(s) recognized by anti BoHV 4 antibodies are exclusively nuclear, suggesting that the putative property of BoHV 4 to confer an immune protection against AlHV 1 relies on a cellular rather than on a humoral immune response. (iii) Phylogenetic analysis of Bovine herpesvirus 4 strains isolated from cattle and from African buffalo In preparation Dewals B., Thirion M., Markine-Goriaynoff N., Gillet L., de Fays K., Minner F., Daix V., Sharp P.M. & Vanderplasschen A. Bovine herpesvirus 4 (BoHV 4) is a gammaherpesvirus which has been isolated from cattle throughout the world. Virological and serological studies have demonstrated that the African buffalo is also a natural host species of BoHV-4. Interestingly, our phylogenetic study on the BoHV 4 Bo17 gene revealed that this gene has been acquired from an ancestor of the African buffalo around 1.5 million years ago. Study of the Bo17 gene also suggested a relatively ancient transmission of BoHV-4 from the ancestor of the African buffalo to the Bos primigenius lineage, followed by a host-dependent split between zebu and taurine BoHV-4 strains. In the present study, we pursued our investigations on the evolution of BoHV 4. To investigate the phylogenetic relationship existing between BoHV 4 strains isolated from African buffalo in Kenya and from cattle throughout the world, nine strains representative of the BoHV 4 species were compared based on six different regions distributed across the genome. Our phylogenetic analyses led to the following conclusions: (i) BoHV 4 strains from African buffalo and from cattle form clades which have split approximately 700,000 years ago. (ii) Since this divergence, inter clade and intra-clade recombination events occurred at different time in the past. (iii) the topology of the tree formed by zebu and taurine BoHV 4 strains is incompatible with a co-speciation process between BoHV 4 and domestic cattle implying that the latter have been contaminated through recent cross-species transmission. A scenario is proposed to explain how BoHV 4 has been transmitted from African buffalo to cattle and how the virus has reached a world wide distribution in the latter host species. In conclusion, this work generated key information and reagents to test in a near future the hypothesis proposed by Rossiter et al. (1989). The results of this work show the complexity of the interactions existing between viruses and their hosts throughout evolution. [less ▲]

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See detailContributions à l'étude des Echinides
Fredericq, Léon ULg

in Archives de zoologie expérimentale et générale (1876), V

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See detailContributions à l'étude des variations physiologiques de la sécrétion interne du pancréas
Fredericq, Léon ULg

in Archives de Zoologie Expérimentale et Générale (1886)

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See detailContributions à l’histoire de la vésicule germinative et du premier noyau embryonnaire
Van Beneden, Édouard ULg

in Bulletins de l'Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique (1876), 41(3), 38-85

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See detailContributions à la didactique de la statistique
Bair, Jacques ULg; Henry, Valérie ULg

Book published by Editions de l'Université de Liège (2005)

Cet ouvrage contient une série d'articles rédigés par des collègues et des anciens collaborateurs du professeur L. Bragard qui ont tenu à rendre hommage à ce dernier. De nombreux thèmes liés à la ... [more ▼]

Cet ouvrage contient une série d'articles rédigés par des collègues et des anciens collaborateurs du professeur L. Bragard qui ont tenu à rendre hommage à ce dernier. De nombreux thèmes liés à la didactique de la statistique sont abordés. [less ▲]

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See detailContributions à la fortune de la "Cène" de Léonard de Vinci en France : la copie de Saint-Germain l'Auxerrois à Paris et la copie de Saint-Martin à Saint Martin des Monts
Fagnart, Laure ULg

in Raccolta Vinciana (2005), XXXI

Cet article fournit une analyse détaillée de l’une des copies anciennes de la "Cène" de Léonard de Vinci, celle qui est conservée dans l’église Saint-Germain l’Auxerrois de Paris depuis 1651 au moins. Il ... [more ▼]

Cet article fournit une analyse détaillée de l’une des copies anciennes de la "Cène" de Léonard de Vinci, celle qui est conservée dans l’église Saint-Germain l’Auxerrois de Paris depuis 1651 au moins. Il s’attache à en retracer l’histoire mais aussi à en identifier le commanditaire : la découverte de signatures, soigneusement grattées dans la couche picturale, permet de supposer qu’il s’agit de Jean V Burdelot, issu d’une famille de notaires et de secrétaires du roi mais aussi procureur général du Sénat de Milan. Comme d’autres Français en charge à Milan, Burdelot a pu visiter le réfectoire du couvent Santa Maria delle Grazie et désirer conserver un souvenir de la "Cène", en commandant une copie. Cet article présente également une autre réplique ancienne du chef-d’œuvre de Léonard, jusqu’alors inconnue de la critique, le relief qui est conservé dans l’église de Saint-Martin-des-Monts (La Ferté-Bernard). [less ▲]

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See detailContributions à la modélisation des incendies dans les bâtiments et de leurs effets sur les structures
Franssen, Jean-Marc ULg

Post doctoral thesis (1997)

Besides the ntroductory and concluding chapter, the body of the thesis is in three parts. The firt part addresses numerical simulation of structural fire behaviour. The second part is dedicated to simple ... [more ▼]

Besides the ntroductory and concluding chapter, the body of the thesis is in three parts. The firt part addresses numerical simulation of structural fire behaviour. The second part is dedicated to simple caluclation methods appropriate for a design office. The this part is dedicated to some aspects of fire safety engineering. In addition, the thesis includes three fire related appendices dedicated to: 1) the evaluation of shear resistance of prestressed concrete beams, 2) the effect of columns failure on the stability of an entire structure, 3) the residual stresses in hot-rolled steel structures sections. [less ▲]

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See detailContributions aux algorithmes d'intégration temporelle conservant l'énergie en dynamique non-linéaire des structures
Noels, Ludovic ULg

Doctoral thesis (2004)

Les points fondamentaux de mes recherches consistent en une étude mathématique des algorithmes d'intégration temporelle d'une discrétisation de type éléments-finis. Les algorithmes traditionnels d ... [more ▼]

Les points fondamentaux de mes recherches consistent en une étude mathématique des algorithmes d'intégration temporelle d'une discrétisation de type éléments-finis. Les algorithmes traditionnels d'intégration temporelle (Newmark, famille alpha-généralisée, ...) peuvent introduire numériquement de l'énergie dans les systèmes non-linéaires. De nouveaux algorithmes sont dès lors apparus pour permettre d'éviter cette perte de stabilité. Lors de mes études, ces algorithmes ont été étendus, de manière originale, au traitement de la plasticité à l'aide d'un modèle de type hypo-élastique. Ils ont également été étendus au traitement généralisé, dans le cadre tridimensionnel, de l'interaction de contact. Ensuite la mise en oeuvre d'une méthode permettant de combiner, au cours du temps un algorithme implicite stable, avec un algorithme explicite traditionnel a été envisagée. La stabilité du passage d'une méthode explicite vers une méthode implicite a été démontrée par nos soins. Une définition originale de critères automatiques de choix de basculement entre les méthodes a été proposée. Des exemples numériques complexes ont mis en évidences les bonnes performances des algorithmes développés, tant du point de vue de la précision des résultats - confrontés aux résultats expérimentaux si ces derniers existent -, que du point de vue de la réduction des coûts de calcul lorsque la méthode combinée est utilisée. [less ▲]

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See detailContributions du sommeil a la consolidation mnésique
Maquet, Pierre ULg; Matarazzo; Foret, Ariane ULg et al

in Biologie Aujourd'hui (2010), 204(2), 139-143

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