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See detailDynamics of the photo-induced orientation and relaxation of new polymethacrylates containing carbazolyl and azobenzene pendant groups
Maertens, Christophe; Dubois, Philippe ULg; Jérôme, Robert ULg et al

in Polymer International (1999), 48(3), 205-211

Polarized-light-induced birefringence has been investigated in copolymers of [-(N-carbazolyl)alkyl methacrylate] and [2,5-dimethylphenyl-[(4-nitrophenyl)azo]phenoxyalkyl methacrylate]. Optical properties ... [more ▼]

Polarized-light-induced birefringence has been investigated in copolymers of [-(N-carbazolyl)alkyl methacrylate] and [2,5-dimethylphenyl-[(4-nitrophenyl)azo]phenoxyalkyl methacrylate]. Optical properties of the side-chain copolymers have been compared with materials in which the azo-dye was merely dispersed in a poly[-(N-carbazolyl)alkyl methacrylate] matrix. Increasing the temperature of the film has a dramatic depressive effect on the maximum of photo-induced orientation near and above the glass transition temperature (Tg) region, while its effect was restricted under this temperature. Kinetics of the photo-orientation and the thermal relaxation as a function of temperature have been analysed by a biexponential model based on two rate constants. The universal Williams-Landel-Ferry (WLF) theory has been used to correlate the writing process and relaxation relative time constants with the relative temperature, i.e. T-Tg . The validity of this model for the studied materials leads to the assumption that photo-orientation and relaxation processes are mainly dependent on the free volume in the polymer matrix. This hypothesis has been assessed in the case of [11-(N-carbazolyl)undecyl methacrylate]-based materials. [less ▲]

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See detailDynamics of the polar aurora
Radioti, Aikaterini ULg

Scientific conference (2012)

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See detailDynamics of total body fatty acids during early ontogeny of pikeperch (Sander lucioperca) larvae
Abi-Ayad, SMEA; Boutiba, Z.; Mélard, Charles ULg et al

in Fish Physiology and Biochemistry (2004), 30(2), 129-136

The fatty acid composition of pikeperch (Sander lucioperca) was determined according to their physiological status, during starvation (10 days) and feeding (28 days). In starved larvae, polyunsaturated ... [more ▼]

The fatty acid composition of pikeperch (Sander lucioperca) was determined according to their physiological status, during starvation (10 days) and feeding (28 days). In starved larvae, polyunsaturated, monounsaturated and saturated fatty acids were utilized as metabolic substrates until day 9. At day 10, all fatty acid levels remained stable or, at least, increased in larval body. Among fatty acids, docosahexaenoic acid 22:6 n-3 was used preferentially (20.3% from total fatty acids utilized) followed by palmitoleic acid 16:1 n-7 (13.9%) and then by oleic 18:1 n-9 (12.3%), linoleic 18:2 n-6 (10.1%), linolenic 18:3 n-3 (9.7%) and eicosapentaenoic 20:5 n-3 (9.1%) acids. On the other hand, arachidonic acid 20:4 n-6 was utilized very lowly (0.3%). In fed larvae, no utilization of body fatty acids was observed during the experiment. It seems that energy requirements (and others) of fed larvae were satisfied by feed. [less ▲]

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See detailDynamics of total lipids and fatty acids during embryogenesis and larval developpement of Eurasian perch (Perca fluviatlis)
Abi-Ayad, Amine; Kestemont, P.; Mélard, Charles ULg

in Fish Physiology and Biochemistry (2000), 23

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See detailDynamics of trace elements in grey seals throughout the lactation period
Habran, Sarah ULg; Pomeroy, P. P.; Debier, Cathy et al

Conference (2011, May 17)

The effects of reproduction and maternal investment (i.e. milk transfer) on trace element levels remain poorly understood in marine mammals. We examined the blood dynamics of Cd, Pb, Hg, Cr, Ni, V, Zn, Cu ... [more ▼]

The effects of reproduction and maternal investment (i.e. milk transfer) on trace element levels remain poorly understood in marine mammals. We examined the blood dynamics of Cd, Pb, Hg, Cr, Ni, V, Zn, Cu, Fe, Ca and Se throughout lactation in a top predator from the North Sea, the grey seal (Halichoerus grypus). Trace element levels were measured in blood and milk of 21 mother-pup pairs in early and late lactation. Maternal hair and natal fur (lanugo) were also collected and analyzed. Trace element levels in blood decreased according to the following pattern: Fe > Ca > Zn > Se > Cu > Hg > Pb > Cr > V in mothers and pups. Cd and Ni were not detected in blood. The substantial levels measured in lanugo indicate nevertheless that all trace elements (including Cd and Ni) were transferred to offspring through the placenta. In maternal hair, Pb levels (~ 2.2 mg/kg dw) were relatively high in comparison with other phocid species. All trace elements, except Cd, were detected in the milk showing a transmammary transfer to offspring, especially for elements such as Ca, Se, V, Ni and Pb. Hg showed the highest levels in blood (up to 0.25 mg/kg ww) and hair (up to 21 mg/kg dw) from the non-essential and toxic metals measured. Levels of Hg and essential elements (Ca, Fe, Zn, Cu and Se) in blood and milk showed significant variations throughout the lactation period. Therefore, physiological processes such as lactation affect trace element levels in tissues of mother and pup elephant seals. Such processes and its relationship to body condition should be considered carefully when interpreting trace element levels in the framework of biomonitoring. [less ▲]

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See detailDe dynamiek van hersemantisering
De Vos, Lien ULg

Scientific conference (2008, November 21)

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See detailDe dynamiek van hersemantisering
De Vos, Lien ULg

in Taal en Tongval (2009)

The southern Dutch variety has a traditional, so-called ‘grammatical’ gender system, in which pronouns agree in gender with their antecedent noun, which can be masculine, feminine or neuter. For most ... [more ▼]

The southern Dutch variety has a traditional, so-called ‘grammatical’ gender system, in which pronouns agree in gender with their antecedent noun, which can be masculine, feminine or neuter. For most nouns, there is no apparent semantic motivation underlying gender assignment. However, this kind of grammatical system may be replaced with a system that makes use of semantically-motivated gender-marked pronouns, by a process termed ‘resemantisation’. Certain elements of semantic gender systems are to be found in the language acquisition of southern children. This paper addresses the question to what extent these semantic tendencies in pronoun usage by children are indicative of an ongoing change in the southern pronominal gender system. Hence it focuses on pronominal gender usage of adults and adolescents as well as language acquiring children. The results reveal fi rst, that even adolescents do not yet reach an adult-like profi ciency in the grammatical gender system, and, second, that the infl uence of grammatical gender on pronominal reference gradually decreases from generation to generation. Though grammatical gender still stands strong, clear semantic patterns are observed, which indicate an ongoing process of resemantisation. The data for adolescents also suggest that the resemantisation process is pushed forward by language acquirers. In this paper the dynamics of this process will be discussed as well as how this fi ts in the typology of resemantisation pathways. [less ▲]

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See detailLes dynamines MX et leur activité anti-influenza.
Garigliany, Mutien-Marie ULg; Zecchinon, Laurent; Cloquette, Karine et al

Poster (2008, September)

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See detailDynamique associative et réduction de la pauvreté rurale: une étude comparative de villages inégalement couverts par des Organisations Non Gouvernementales dans la province du Bandundu et dans l’hinterland de Kinshasa.
Nganda Afumba, Jean Pierre ULg

Doctoral thesis (2012)

Comme bon nombre de pays en développement, la République Démocratique du Congo observe, depuis le début des années 90, un développement sans précédent du mouvement associatif, particulièrement des ... [more ▼]

Comme bon nombre de pays en développement, la République Démocratique du Congo observe, depuis le début des années 90, un développement sans précédent du mouvement associatif, particulièrement des organisations non gouvernementales de développement. Dans un environnement où les pouvoirs publics sont quasi inexistants, ces dernières sont considérées par certains comme des instruments efficaces de réduction de la pauvreté, et par d’autres comme des opportunistes évoluant aux dépens de la misère des gens. La présente recherche se propose de faire une étude comparative entre, d’une part, des ménages de deux villages de l’hinterland de Kinshasa largement couverts par des ONG, et d’autre part, des ménages de deux autres villages dans le Bandundu ne bénéficiant d’aucune intervention d’ONG. Cette étude a pour but la compréhension, l’analyse et l’appréciation empirique de la pertinence de la stratégie de développement et de réduction de la pauvreté rurale orientée vers la promotion des organisations associatives du type ONG, et in fine suggère un outil susceptible d’améliorer les interventions visant la réduction de la pauvreté rurale. [less ▲]

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See detailDynamique d’expansion du Pic mar (Dendrocopos medius) en Belgique
Lehaire, François ULg

in Acte du 33 ième Colloque francophone d’ornithologie (2009, December)

Middle Spotted Woodpecker is one of the key species for which understanding the relationship with its habitat can have important implications for improving biodiversity-friendly management of hardwood ... [more ▼]

Middle Spotted Woodpecker is one of the key species for which understanding the relationship with its habitat can have important implications for improving biodiversity-friendly management of hardwood forests. This species is considered as an indicator of a forest ecosystem comprising a high proportion of mature trees and a botanical composition chiefly associated with oaks. For the last two decades, the Middle Spotted Woodpecker distribution range is expanding remarkably in the Walloon Region while, in contrast, other populations are either decreasing in the south-east of Europe or remain stable elsewhere in Europe. The study of this expansion range within the Walloon Region and of the forest habitats used therein is necessary to better assess the ecological requirements of the species. Based on more than 3,000 location data collected in the framework of the Atlas of breeding birds between 2001 and 2007, our study aimed at comparing forest habitats occupied by Middle Spotted Wood peckers between three geographically distinct areas, defined on the basis of the temporal evolution of the species’ distribution in the Walloon Region: the old distribution range, described from 1973-1977 and corresponding to the Ardennes and the Lorraine regions (southern Belgium), the transition range, defined in 1991-1992 and corresponding to the Fagne-Famenne region, and the expansion range, described in 2001-2007 and corresponding to the area colonized further north in the Loess region and Condroz. Overall, 418 woodpecker locations were crossed with 41 forest habitat variables available as part of the Regional Forest Inventory of the Walloon Region (IPRFW). Preliminary results suggest that, in agreement with previously known environmental requirements, forest stands presenting high densities in oak trees have been colonized by the Middle Spotted Woodpecker during its recent range expansion. However, the species is also expanding towards areas with a lower proportion of beech trees compared to the old distribution range, with a marked preference for forest stands presenting high tree diversity. We conclude that the Middle Spotted Woodpecker may exhibit a certain flexibility regarding its habitats requirements in Walloon forests, which led us to suggest several recommendations aimed at promoting the conservation of the species and of the forest biodiversity in general. [less ▲]

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See detailDynamique d’une espèce ligneuse héliophile longévive dans un monde changeant le cas de Pericopsis elata (Harms) Meeuwen (Fabaceae) au sud-est du Cameroun
Bourland, Nils ULg; Doucet, Jean-Louis ULg

Scientific conference (2014, May 13)

Exposé sur l'origine et la dynamique des peuplements formés par Pericopsis elata au Sud-Est du Cameroon.

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See detailDynamique d’une espèce ligneuse héliophile longévive dans un monde changeant : le cas de Pericopsis elata (Harms) Meeuwen (Fabaceae) au sud est du Cameroun
Bourland, Nils ULg

Doctoral thesis (2013)

The Central African forests are characterized by high species richness. While little light generally reaches their litter layer, among the species encountered are major long-lived light-demanding logged ... [more ▼]

The Central African forests are characterized by high species richness. While little light generally reaches their litter layer, among the species encountered are major long-lived light-demanding logged trees. These species may have established in the past because of large disturbances. Indeed, major climate changes have occurred in the past few millennia, in some areas coupled with strong human occupations. Among these light-demanding species we find the assamela / afrormosia (Pericopsis elata (Harms) Meeuwen, Fabaceae), a large high trading value tree of African semi-deciduous moist forests. Nowadays this logged species suffers from significant regeneration problems on its natural range from Ghana to the Democratic Republic of Congo. Therefore, it is included in CITES Appendix II and is recorded as “Endangered A1cd” on the IUCN Red List. No convincing solution can be found in the available scientific literature to overcome the deficiency of its regeneration. In addition, little or no information is available describing ca. its population dynamics, genetics, silviculture or the probable origin of its stands. It is in this context that the present PhD was undertaken. In this study, we have adopted a multidisciplinary approach to understanding the dynamics of this population rich in long-lived light-demanding species logged in the Congo basin. Moreover, we have suggested ways for their management and conservation in a changing world. To do so, we have adopted as a study-model the case of P. elata in southeastern Cameroon. The main results of the study show that, on a local scale, physico-chemical soil parameters have no influence on the presence or absence of this clustered species. However, on the same scale, large quantities of charcoal were found in the soil, mainly inside those clusters. The anthracological analysis has also shown that the vegetation at the time of the burn was similar to that of today. Numerous fragments of pottery were also found in the top soil layers only inside clusters formed by the species. Finally, some 14C datings go back to ca. 200 years BP, which is approximately the average age of concerned clusters. This body of evidence leads us to conclude on an ancient form of shifting cultivation as the most likely origin of the assamela populations currently present in southeastern Cameroon. In addition to its current population structure within the study area, several parameters controlling its population dynamics were estimated. While the annualized natural mortality of the species reaches about 1%, its average diameter growth rate is 0.31 cm.year-1, which is a relatively low value compared to other long-lived light-demanding species. Selective logging seems to have only a light influence on the behavior of the species. On the other hand, the impact of logging on its seed tree populations is only ca. 12%. Each seed tree bears fruit on average only once every five years. The minimum diameter of reproduction and the effective flowering diameter were respectively 32 and 37 cm. The recovery rate, varying greatly from one country to another, is more than 100% in Cameroon, where the conservation status assigned to the species seems excessive. A sufficient regeneration by planting should allow the perpetuation of the assamela populations in the long run, as with other major logged light-demanding trees. [less ▲]

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See detailDynamique d'une expérience spatiale: analyses et vérifications
Defise, Jean-Marc ULg

in Actes du 3ième Congrès national Belge de Mécanique Théorique et Appliquée (1994)

L'expérience EIT est un des nombreux instruments qui font partie de la charge utile du satellite SOHO de l'Agence Spatiale Européenne. A ce titre, un programme complet d'analyse et de vérification a été ... [more ▼]

L'expérience EIT est un des nombreux instruments qui font partie de la charge utile du satellite SOHO de l'Agence Spatiale Européenne. A ce titre, un programme complet d'analyse et de vérification a été mis en oeuvre pour démontrer la bonne tenue dynamique de l'instrument, sur base des spécifications imposées par l'ESA. Par ailleurs, le télescope est composé de plusieurs sous-systèmes réalisés et testés dans des laboratoires différents. Chaque élément est qualifié séparément, avant intégration du modèle de vol. Une approche de type "proto-flight" a été adoptée. Cet article décrit les principaux résultats des analyses et des essais effectués dans le cadre de ce projet. [less ▲]

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See detailDynamique d'une population de martins pêcheurs (Alcedo atthis) en Belgique en liaison avec la gestion des cours d'eau.
Libois, Roland ULg

in Actes du 1er colloque international "gestion et préservation des ressoures en eau" (2004, September)

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See detailDynamique de défense du nid chez Symphodus ocellatus (Forsskål, 1775), poisson labridé méditerranéen. I. Comportements agonistiques entre le mâle territorial nidificateur et cinq autres espèces de labridés
Ylieff, Marc ULg; Michel, Christian ULg; Voss, Jacques

in Cahiers d'Ethologie (1997), 17(1), 49-74

This research in the field consists of a study of interspecific agonistic behaviour of territorial male in Symphodus ocellatus. This behaviour is useful for brood and nest defense. Four questions ... [more ▼]

This research in the field consists of a study of interspecific agonistic behaviour of territorial male in Symphodus ocellatus. This behaviour is useful for brood and nest defense. Four questions involving Symphodus ocellatus towards S. tinca, S. mediterraneus, S. roissali, Thalassoma pavo et Coris julis were investigated. The questions of interest were: (1) aggressors or intruders motivations (predation of the brood (a) and/or territorial conflicts (b)), (2) the recognition of this or that species (recognition studied with selective attacks by territorial male), (3) the organ(s) of perception used for this recognition and (4) the importance of territorial male investment in nest defense; this role could ensure a successful reproduction of the species. Our observations and experimentations (tested labrid fishes presented to T. males) allow us to affirm that in S. ocellatus, nesting territorial males recognize the various tested labrid fishes; that the organ of perception used for social recognition is the visual channel; that spawn protection insured by territorial male, a task guided by his visual system, is necessary towards menace of his congeners, but also the other fishes living in his habitat. Nevertheless, if it’s becoming clear that the Mediterranean labrid fishes have the ability to recognize and preferentially interact with particular individuals, the answer of the question 1, concerning aggressors motivations, is not yet clearly known. [less ▲]

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See detailDynamique de défense du nid chez Symphodus ocellatus (Forsskål, 1775), poisson labridé méditerranéen. II. Comportements agressifs du mâle territorial nidificateur envers des mollusques gastéropodes
Ylieff, Marc ULg; Michel, Christian ULg; Voss, Jacques

in Cahiers d'Ethologie (1998), 18(1), 39-52

This field research examines aggressive behaviour towards gasteropod molluscs in nesting territorial male of Symphodus ocellatus. This behaviour is useful for brood and nest defense. Four questions ... [more ▼]

This field research examines aggressive behaviour towards gasteropod molluscs in nesting territorial male of Symphodus ocellatus. This behaviour is useful for brood and nest defense. Four questions involving Symphodus ocellatus towards gasteropod molluscs were investigated. Questions of interest were: (1) selective cleaning of the nest according to possible predation danger of molluscs on the eggs, (2) visual recognition of natural mollusc from artificially coloured lure, (3) colours discriminating abilities by the visual system and, more generally (4) the importance of territorial male investment in nest defense; this role could ensure a successful reproduction of the species. Our observations and experimentations (coloured dummies) allow us to conclude that in Symphodus ocellatus, nesting territorial males clean every time their nest, any gasteropod mollusc species whatever; that they have sufficient knowledge of their usual biological environment to be able to discriminate a gasteropod mollusc from a dummy; that the organ of perception used for social recognition is the visual channel constituted by a neural system competent to perceive colours finely , a special quality which support the theory about the use of one preferential colour (red for S.ocellatus) for visual communication; that fry protection insured by territorial male, a task guided by his visual system, is necessary considering dangers from some gasteropod molluscs living in his habitat. [less ▲]

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