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See detailEvaluation des effets à court terme de l’intervention « Bouger plus » sur la pratique d’activité physique des seniors
Rompen, Jérôme ULg; Mouton, Alexandre ULg; Grimont, Pierre et al

Poster (2014, July 03)

Des outils basés sur un site internet sont efficaces pour promouvoir l’activité physique (AP) chez les seniors (Ammann et al., 2013). Cette étude avait pour but d’évaluer les effets de l’intervention « ... [more ▼]

Des outils basés sur un site internet sont efficaces pour promouvoir l’activité physique (AP) chez les seniors (Ammann et al., 2013). Cette étude avait pour but d’évaluer les effets de l’intervention « Bouger plus » sur la pratique d'AP de sujets de 50 ans et plus, au sein d’une commune. Quatre groupes ont reçu une intervention différente pendant trois mois : un site internet (I), un cours collectif (CC), une combinaison des deux (CCI) et pas d'intervention (CO). Des questionnaires ont permis d’évaluer les résultats. Ceux-ci montrent une évolution positive du stade de changement de comportement vis-à-vis de l’AP, au cours de l’intervention, pour les groupes I et CCI. De plus, le niveau de pratique est resté stable malgré la période hivernale pour les groupes CC et CCI alors qu’il a chuté pour le groupe CO. L’intervention a donc eu des effets positifs à court terme sur les comportements en matière d’AP, particulièrement quand le site internet et les cours collectifs étaient combinés. [less ▲]

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See detailEtude de la notoriété des sportifs belges francophones de haut niveau
THEUNISSEN, Catherine ULg; Danse, Nicolas; Cloes, Marc ULg

Poster (2014, July 03)

L’objectif de cette étude est d’analyser la notoriété des sportifs belges francophones de haut niveau ainsi que l'image de la population à leur égard. Pour obtenir ces informations, nous avons choisi ... [more ▼]

L’objectif de cette étude est d’analyser la notoriété des sportifs belges francophones de haut niveau ainsi que l'image de la population à leur égard. Pour obtenir ces informations, nous avons choisi d’interroger un échantillon représentatif de 400 sujets ayant fait l’objet d’une sélection aléatoire basée sur des critères sociodémographiques. Le questionnaire, soumis par téléphone et en face-à-face, porte sur la notoriété spontanée et assistée ainsi que sur l'image des sportifs. Il a été élaboré avec l'aide d'un expert en marketing. Après analyses, nous pouvons classer les sportifs en termes de notoriété. Nous constatons également que certains sont perçus comme de véritables héros tandis que d'autres véhiculent plutôt une image négative. Ces informations s’avèrent cruciales pour les sportifs et leurs entraîneurs dans le sens où à un taux de notoriété élevée et une image positive s’associent plus aisément sponsors pendant la pratique et contrat de reconversion en fin de parcours. [less ▲]

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See detailComparaison du niveau d’estime de soi dans deux populations ayant des caractéristiques démographiques différentes : des arbitres et des non-arbitres
Van Hoye, Martin ULg; Cloes, Marc ULg

Poster (2014, July 03)

Si le sport forge le caractère, l’arbitrage devrait également responsabiliser les individus qui l’exercent. Aussi, on peut considérer que les arbitres pourraient développer une meilleure estime d’eux ... [more ▼]

Si le sport forge le caractère, l’arbitrage devrait également responsabiliser les individus qui l’exercent. Aussi, on peut considérer que les arbitres pourraient développer une meilleure estime d’eux-mêmes ? Dans cette recherche, nous avons tenté de vérifier cette hypothèse en analysant le niveau d’estime de soi de deux échantillons distincts : des arbitres de basket-ball (n=163) et des personnes n’ayant aucune expérience au niveau de l’arbitrage (n=163). L’instrument que nous avons utilisé est « l’Echelle de l’Estime de Soi » (EES). La moyenne générale au questionnaire est légèrement supérieure chez les arbitres (30,9 vs 30,5) mais il ne s’agit pas d’une différence significative (p=0,8372). L’ancienneté dans l’arbitrage ou l’âge des individus ne semblent pas être un facteur influençant l’estime de soi des arbitres. Il conviendrait de vérifier s’il en est de même dans les autres disciplines sportives que le basket-ball. [less ▲]

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See detailAnalyse qualitative du fonctionnement du centre de formation d’une fédération sportive
Lacrosse, Zoé ULg; Martin, Valentine; Cloes, Marc ULg

Poster (2014, July 03)

Cette étude qualitative analyse le fonctionnement d’un centre de formation pour jeunes athlètes de haut niveau dont la finalité consiste à leur permettre de mener conjointement leurs études et leur ... [more ▼]

Cette étude qualitative analyse le fonctionnement d’un centre de formation pour jeunes athlètes de haut niveau dont la finalité consiste à leur permettre de mener conjointement leurs études et leur carrière sportives. Dans la perspective d’aider la structure à améliorer ce qui est mis en place, notre objectif consiste à décrire la situation actuelle. D’un point de vue pratique, nous avons interrogé les dirigeants (n=4) du centre, les sportifs (n=34), leurs parents (n=10), les coaches (n=3) ainsi que plusieurs intervenants externes (médecin, directeur d’école, etc. ; n = 3). Nous avons également réalisé un certain nombre d’observations informelles et collecté des questionnaires permettant de faire émerger le ressenti des joueurs quant à leur vie au sein du centre. Les résultats indiquent (a) un manque de suivi diététique et psychologique, (b) des relations relativement bonnes entre les acteurs sauf entre les joueurs et les éducateurs et, (c) la nécessité d’améliorer les infrastructures. [less ▲]

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See detailEvaluation des effets à court terme de l’intervention « Bougerplus » sur les connaissances en matière d’activité physique des seniors
Mouton, Alexandre ULg; Rompen, Jérôme ULg; Cloes, Marc ULg

Poster (2014, July 03)

La littérature actuelle suggère qu’une meilleure connaissance en matière d’AP encouragerait à l’adoption d’un style de vie plus actif. L’objectif principal de cette étude était d’identifier les effets de ... [more ▼]

La littérature actuelle suggère qu’une meilleure connaissance en matière d’AP encouragerait à l’adoption d’un style de vie plus actif. L’objectif principal de cette étude était d’identifier les effets de trois interventions différentes sur la connaissance en matière d’AP chez les seniors d’une commune francophone belge. D’une durée de 3 mois, l’intervention se composait d’un site internet et d’un cours collectif. Quatre groupes de seniors provenant de la même commune ont été formés : contrôle (C), Internet (I), cours collectif (CC) et combiné (CCI). Des questionnaires ont été complétés par les participants avant l’intervention (T0), après l’intervention (T1) et après deux mois de suivi (T2). Une évolution significative des connaissances en matière d’AP a été constatée pour les groupe CCI et CC entre T0 et T2. L’intervention combinant un cours collectif ainsi qu’un outil Internet semble la plus efficace pour améliorer à court-terme les connaissances en matière d’AP chez les seniors. [less ▲]

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See detailTrait decoupling promotes evolutionary diversification of the trophic and acoustic system of damselfishes
Frederich, Bruno ULg; Olivier, Damien ULg; Litsios, Glenn et al

in Proceedings of the Royal Society B : Biological Sciences (2014)

Trait decoupling, wherein evolutionary release of constraints permits specialization of formerly integrated structures, represents a major conceptual framework for interpreting patterns of organismal ... [more ▼]

Trait decoupling, wherein evolutionary release of constraints permits specialization of formerly integrated structures, represents a major conceptual framework for interpreting patterns of organismal diversity. However, few empirical tests of this hypothesis exist. A central prediction, that the tempo of morphological evolution and ecological diversification should increase following decoupling events, remains inadequately tested. In damselfishes (Pomacentridae), a ceratomandibular ligament links the hyoid bar and lower jaws, coupling two main morphofunctional units directly involved in both feeding and sound production. Here, we test the decoupling hypothesis by examining the evolutionary consequences of the loss of the ceratomandibular ligament in multiple damselfish lineages. As predicted, we find that rates of morphological evolution of trophic structures increased following the loss of the ligament. However, this increase in evolutionary rate is not associated with an increase in trophic breadth, but rather with morphofunctional specialization for the capture of zooplanktonic prey. Lineages lacking the ceratomandibular ligament also shows different acoustic signals (i.e. higher variation of pulse periods) from others, resulting in an increase of the acoustic diversity across the family. Our results support the idea that trait decoupling can increase morphological and behavioral diversity through increased specialization rather than the generation of novel ecotypes. [less ▲]

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See detailQuels agritourismes pour les campagnes périurbaines ? Les cas de la Wallonie et du Grand-Duché de Luxembourg
Dubois, Charline ULg

Doctoral thesis (2014)

To cope with the economic uncertainties of the changes, transformations, and transitions affecting current European and world agriculture, many farmers are rethinking the purposes of their business and ... [more ▼]

To cope with the economic uncertainties of the changes, transformations, and transitions affecting current European and world agriculture, many farmers are rethinking the purposes of their business and are looking to diversify their activities. Taking advantage of certain assets related to their operation and of opportunities for tourism development in the region (such as availability of buildings, subsidies related to ecology and environment images), some of them have chosen agritourism, a tourist activity proposed by the farmer on his/her farm. The literature includes many studies on this topic, but there is no consensus on terminology, definitions, and concepts: they vary from one author to another and evolve over time. Having distinguished different agritourist typologies in which accommodation is a basic element, we have personally chosen to study agritourism defined as "all tourist and leisure activities and services present in a working farm". Wallonia and the Grand Duchy of Luxembourg, our geographical research areas, are neighbouring entities, with similar agriculture, and their tourist markets offer some similarities. Included in rural tourism, agritourism is nevertheless marginal compared to the overall tourist product offered. Some successes might suggest that agritourism could be the panacea against the crisis in agriculture. But is this always the case? Agritourism should be defined, localized, and differentiated. Working on these two periurban entities of Western Europe which are not yet discussed in the literature, we wanted to understand and to identify agritourist dynamics. We wanted to understand the geographic relationship between agritourism, periurban countryside, local resources, and agricultural and tourist specializations. We wanted to understand the logic of the emergence of tourism on a farm and the links between tourist and agricultural functions in a specific spatial context. Finally, we wanted to understand the integration of the motivations of different types of tourists and their reasons for visiting particular regional and local contexts. To do this, we analyse both the location and the agritourist geographical position in relation to the different markets. To meet the objectives, we conducted a comparative heuristic analysis of agritourism in both territories. We interviewed key organisational representatives (31 persons), we made field observations, documents comparisons... We conducted interviews with various Walloon and Luxembourg farmers (34 life histories) affording different agritourist practices that we synthesized by circumstantial geographical sketches. We conducted surveys with potential tourists (1148surveys) in seven Walloon and Luxembourg tourist spots. These steps and the statistical and cartographic processing based on the results allowed us to build a heuristic geographical model of the Walloon and Luxembourg agritourism. The experiences of farmers interviewed allowed us to understand the position of the agritourist system in its spatial context. Each of them develops opportunities and experience threats (economic, social, from heritage) in connection with the launch of the project, a true survival kit in some cases. It appears that agritourism is not always a panacea for farmers. On the farm, the tourist function comes after the agricultural one and is based on the latter, but the agricultural function also benefits from the tourist function because both activities are related. The emergence of tourism is an autonomous decision of the farmers who can be influenced by other actors, including authorities, but also by other factors such as the existence of a local demand or the regional real estate pressure. There is no particular profile of tourists visiting agritourism, but some features, including those of family, are more favourable to the experience of this type of tourism. Definitions and representations as well as the reasons and expectations differ depending on the characteristics of the interviewed tourists: urban or rural origin, level of experience. Three agritourist profiles were also highlighted: those seeking accommodation in a rural environment, those who think about accommodation linked to gastronomy, those who prefer accommodation that would be a comfortable basis from which to tour in a tourist area. The comparison between the experiences of farmers and the expectations of tourists shows that there is a risk of developing different organizational temporalities in the farm "open" to tourists as well as of favouring unbalanced images of agritourism, which could lead to a vision and a promotion of agriculture which does not correspond to its regional reality. By combining the different results and by linking the typology of the Walloon and Luxembourg agritourist products, the types of rural areas and the geographical components, it appears that agritourism should not only be analysed according to the environmental dimensions, but that the analysis must also take into account other factors such as accessibility, local communities, hospitality, rural development policies, the real estate market, the agricultural orientation of farm operations, as well as the degree of complementarity with tourist spots. We have demonstrated that agritourism, combining agriculture with tourism, is not developing, either everywhere, or in the same manner, and differs between different types of periurban countryside, depending on local resources. Moreover, agritourism is not always a solution for all countrysides, nor always a path for each farmer, nor always a perfect tourist destination for all tourists. However, even if strict regionalization of agritourism does not seem possible when we consider all the factors involved in the different regions, trends may emerge depending on agritourist types. There is thus a link between agritourism type and countryside type, which the heuristic model we propose should allow to improve in order to increase the convergence between the expectations of the different stakeholders. [less ▲]

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See detailConférence invitée intitulée: « La démocratie multiculturelle »
Martiniello, Marco ULg

Scientific conference (2014, July 02)

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See detailComparaison entre le profil vertical de la vitesse du vent observé dans les basses couches de la troposphère et celui simulé par le modèle WRF en Belgique
Doutreloup, Sébastien ULg; Fettweis, Xavier ULg; Beaumet, Julien ULg et al

in Camberlin, Pierre; Richard, Yves (Eds.) Actes du XXVIIe Colloque de l'Association Internationale de Climatologie : CLIMAT : SYSTÈME & INTERACTIONS (2014, July 02)

In the framework of FLEXIPAC project funded by the "RELIABLE" program of Walloon Region (Belgium), the Laboratory of Climatology Topoclimatology (LCT) of the University of Liège (Belgium) aims to adjust ... [more ▼]

In the framework of FLEXIPAC project funded by the "RELIABLE" program of Walloon Region (Belgium), the Laboratory of Climatology Topoclimatology (LCT) of the University of Liège (Belgium) aims to adjust the WRF regional model (v.3.4.) forced by the ERA-Interim reanalysis for Belgium. Our analysis shows that wind speeds at 100m simulated by WRF are systematically overestimated compared to wind speeds extracted from wind productions of two wind farms. In order to solve this problem, four ways are considered in this contribution. The first way is to compare the WRF model with the reanalysis data. The second way is to test the influence of the spatial resolution by running WRF with a finer resolution. The third way is to smooth WRF outputs, where in order to analyze the variability created by the model. And finally, the fourth way is to compare the WRF model with the MAR (v3.3.) regional model. This last way seems to confirm that the MAR model better simulates wind speeds at 10m and at 100m than the WRF model. [less ▲]

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See detailAnalyse de l’efficacité de l’accoutumance à l’eau chez l’enfant préscolaire
Mornard, Manhattan ULg; Jidovtseff, Boris ULg; Deflandre, Dorian ULg et al

Conference (2014, July 02)

Beaucoup d’enfants suivent des cours d’accoutumance à l’eau et différentes approches existent. Cette étude vise à comparer deux de ces méthodes et d’en vérifier l’efficacité. Nous avons soumis à trois ... [more ▼]

Beaucoup d’enfants suivent des cours d’accoutumance à l’eau et différentes approches existent. Cette étude vise à comparer deux de ces méthodes et d’en vérifier l’efficacité. Nous avons soumis à trois groupes d’enfants une batterie de tests complète. Vingt-cinq enfants bénéficiaient d’une méthode traditionnelle (TRADITION), 25 autres de la méthode CEReKi (CEREKI) et les 27 derniers ne suivaient aucun cours (CONTRÔLE). Tous ont été testés avant et après une période de cinq mois. L’approche pédagogique des deux écoles a été analysée durant 13 séances filmées. On observe une amélioration linéaire du niveau d’accoutumance à l’eau des enfants en fonction de leur âge qu’ils suivent ou non des cours. Les résultats démontrent l’efficacité des deux écoles. Les enfants CEREKI semblent s’améliorer autant mais en moins de séances. Cela peut être dû à un meilleur temps d’engagement moteur. La méthode CEREKI s’avère donc très efficace, même dans une piscine peu adaptée. [less ▲]

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See detailPopulations of aphid natural enemies in agroecosystems, with special emphasis on the Multicoloured Asian Ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae)
Vandereycken, Axel ULg

Doctoral thesis (2014)

The international trade of goods and food can lead to the introduction of alien species in the importing countries. Even if in the most cases there is no negative impact induced by alien species, in some ... [more ▼]

The international trade of goods and food can lead to the introduction of alien species in the importing countries. Even if in the most cases there is no negative impact induced by alien species, in some cases the new imported species can spread out of control. These species can cause economical and ecological damages. The Multicoloured Asian ladybird Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is one of these species which was intentionally introduced for biological control and has spread from its native range in Central and Eastern Asia to large parts of North and South America, Europe and Africa. The decline of native species is linked to the spread and the aggressive behaviour of H. axyridis. The objective of this thesis is the evaluation of aphid's predator population densities and predator diversities, with a special focus on H. axyridis in agroecosystems in Wallonia, in the South of Belgium. First, field crops preferences of H. axyridis were determined. Later aphid's predator population changes during time were evaluated. Finally H. axyridis population changes between two crop farming were evaluated. Our main findings were as follows. Results, based on insects collected since 2001, highlighted that the first collected H. axyridis was in 2002 and the population of H. axyridis is increasing until 2008. In the same time population of Adalia bipunctata, Propylea quatuordecimpunctata and Psyllobora vigintiduopunctata, three native species, are decreasing. Samplings in agroecosystems highlighted that aphid's predator community is composed of few dominant species: three coccinellids Coccinella septempunctata, P. quatuordecimpunctata and H. axyridis, one syrphid Episyrphus balteatus and one chrysopid Chrysoperla carnea. We have shown that H. axyridis do not invade all Wallonia crops at the same rate because corn and broad bean are more invaded that wheat and potato at both larval and adult stages. Moreover in corn, H. axyridis populations has strongly increased from 2009 to 2011. Finally, organic farming do not enhance abundance of H. axyridis but lead to increase the total abundance of aphid natural enemies. [less ▲]

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See detailMICROPHYSIQUE DES NUAGES ET RAYONNEMENT SOLAIRE : COMPARAISON DES MESURES IN SITU AU MONT RIGI EN HAUTE BELGIQUE ET DES DONNÉES CLOUD PHYSICAL PROPERTIES (CPP) OBTENUES À PARTIR DES IMAGES METEOSAT-9
Beaumet, Julien ULg; Clerbaux, Nicolas; Cornet, Yves ULg et al

in Camberlin, Pierre; Richard, Yves (Eds.) Actes du XXVIIe Colloque de l'Association Internationale de Climatologie : CLIMAT : SYSTÈME & INTERACTIONS (2014, July 02)

Le rayonnement solaire global mesuré au mont Rigi a été comparé à l'épaisseur optique des nuages (COT) estimée à l'aide des données SEVIRI. Une relation logarithmique avec un coefficient de détermination ... [more ▼]

Le rayonnement solaire global mesuré au mont Rigi a été comparé à l'épaisseur optique des nuages (COT) estimée à l'aide des données SEVIRI. Une relation logarithmique avec un coefficient de détermination d'environ 0,5 a été trouvée. Ce résultat plutôt faible peut en grande partie s'expliquer par un nombre limité de cas où subsistent des erreurs de positionnement ou par des interactions plus complexes entre nébulosité et rayonnement. De plus, l'incertitude sur l'estimation de l'épaisseur optique des nuages à l'aide des données SEVIRI pour les nuages optiquement plus épais n'est pas négligeable. [less ▲]

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See detailTransiting exoplanets from the CoRoT space mission. XXVI. CoRoT-24: a transiting multiplanet system
Alonso, R.; Moutou, C.; Endl, M. et al

in Astronomy and Astrophysics (2014), 567

We present the discovery of a candidate multiply transiting system, the first one found in the CoRoT mission. Two transit-like features with periods of 5.11 and 11.76 d are detected in the CoRoT light ... [more ▼]

We present the discovery of a candidate multiply transiting system, the first one found in the CoRoT mission. Two transit-like features with periods of 5.11 and 11.76 d are detected in the CoRoT light curve around a main sequence K1V star of r = 15.1. If the features are due to transiting planets around the same star, these would correspond to objects of 3.7 ± 0.4 and 5.0 ± 0.5 R[SUB]⊕[/SUB] , respectively. Several radial velocities serve to provide an upper limit of 5.7 M[SUB]⊕[/SUB] for the 5.11 d signal and to tentatively measure a mass of 28[SUP]+11[/SUP][SUB]-11[/SUB] M[SUB]⊕[/SUB] for the object transiting with a 11.76 d period. These measurements imply low density objects, with a significant gaseous envelope. The detailed analysis of the photometric and spectroscopic data serves to estimate the probability that the observations are caused by transiting Neptune-sized planets as much as over 26 times higher than a blend scenario involving only one transiting planet and as much as over 900 times higher than a scenario involving two blends and no planets. The radial velocities show a long-term modulation that might be attributed to a 1.5 M[SUB]Jup[/SUB] planet orbiting at 1.8 AU from the host, but more data are required to determine the precise orbital parameters of this companion. The CoRoT space mission, launched on 27 December 2006, has been developed and is operated by the CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Program), Germany, and Spain. Some of the observations were made with the HARPS spectrograph at ESO La Silla Observatory (184.C-0639) and with the HIRES spectrograph at the Keck Telescope (N035Hr, N143Hr 260 and N095Hr). Partly based on observations obtained at ESO Paranal Observatory, Chile (086.C-0235(A) and B).Tables 2-4 and Fig. 12 are available in electronic form at <A href="http://www.aanda.org/10.1051/0004-6361/201118662/olm">http://www.aanda.org</A> [less ▲]

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See detailL'univers romanesque d'Hubert Juin : L'aventure d'une écriture
Kangomba, Lulamba ULg

Doctoral thesis (2014)

The work has as main purpose to study the work of romance Hubert Juin trying to illuminate the paradoxes it contains: regionalist themes whose treatment goes beyond codes of regionalism; writing practices ... [more ▼]

The work has as main purpose to study the work of romance Hubert Juin trying to illuminate the paradoxes it contains: regionalist themes whose treatment goes beyond codes of regionalism; writing practices near New Roman, without the texts claim to this literary movement. This analysis is closely related to the biographical and poetic texts of the author. The approach is characterized, first, by the work of literary pragmatics developed by Dominique Maingueneau; secondly, by the work on the space novel done by Jean Weisgerber. [less ▲]

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See detailRésonance locale et caractérisation de défauts de délaminage par vibrothermographie
Demy, Philippe ULg

Doctoral thesis (2014)

La vibrothermographie est une méthode de thermographie active utilisée en contrôle non destructif qui présente des caractéristiques intéressantes et peu communes pour la détection de défauts. Cependant ... [more ▼]

La vibrothermographie est une méthode de thermographie active utilisée en contrôle non destructif qui présente des caractéristiques intéressantes et peu communes pour la détection de défauts. Cependant, la méthode souffre d’un manque de fiabilité des résultats lié au chaos acoustique inhérent à la nature du contact pour la stimulation. La principale innovation de cette thèse consiste à étudier et proposer une méthode alternative à la vibrothermographie classique à partir d’un couplage linéaire obtenu par collage. La mise en évidence et l’étude d’un phénomène de résonance locale de délaminage a permis la mise au point d’une technique performante et fiable pour la détection et la caractérisation de défauts dans les matériaux composites. [less ▲]

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See detailAre agricultural ecosystems important BVOC « exchangers »? Evidences from 2 measurement years on croplands at Lonzée (Belgium)
Bachy, Aurélie ULg; Aubinet, Marc ULg; Schoon, Niels et al

Poster (2014, July 01)

For the last decades, agricultural ecosystems have been a key biome for diverse socio-economical, environmental and climatic issues. And one of these climatic issues is just BVOC (Biogenic Volatile ... [more ▼]

For the last decades, agricultural ecosystems have been a key biome for diverse socio-economical, environmental and climatic issues. And one of these climatic issues is just BVOC (Biogenic Volatile Organic Compounds) emission from terrestrial ecosystems. Indeed, those compounds which are mostly emitted by plants play a great role in the atmospheric chemistry, thereby influencing the Earth surface radiative budget and the tropospheric air quality. However, so far, very few is known about BVOC exchange by crops, implying that huge uncertainties remain about qualifying, quantifying and determining sources/sinks and driving mechanisms of BVOC exchanges between croplands ecosystems and the atmosphere. We present here the first long term BVOC fluxes measurement study conducted on maize (2012) and winter wheat (2013), respectively the second and first most important worldwide crops (FAOSTAT). BVOC exchange was measured using the disjunct by mass scanning eddy covariance technique (+ PTR-MS, Ionicon) at the Lonzée Terrestrial Observatory (ICOS site) in Belgium. Main results are: (i) crops emit mainly methanol; (ii) BVOC fluxes from studied crops is lower than in literature, suggesting that agricultural ecosystems are poor BVOC exchangers; (iii) soil is a significant BVOC source. [less ▲]

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See detailX-ray emission from magnetic massive stars
Nazé, Yaël ULg; Petit, V.; Rindbrand, M. et al

Poster (2014, July 01)

Magnetically confined winds of early-type stars are expected to be sources of bright and hard X-rays. In an attempt to clarify the systematics of the observed X-ray properties, we have analyzed a large ... [more ▼]

Magnetically confined winds of early-type stars are expected to be sources of bright and hard X-rays. In an attempt to clarify the systematics of the observed X-ray properties, we have analyzed a large series of Chandra and XMM observations, corresponding to over 100 exposures of 60% of the known magnetic massive stars listed recently by Petit et al. (2013). We notably show that the X-ray luminosity is strongly correlated with mass-loss rate, in agreement with predictions of magnetically confined wind models. We also investigated the behavior of other X-ray properties (plasma temperature, absorption, variability), yielding additional constraints on models. This work not only advances our knowledge of the X-ray emission of massive stars, but also suggests new observational and theoretical avenues to further explore magnetically confined winds. [less ▲]

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See detailThe X-ray bright massive stars in Cyg OB2
Nazé, Yaël ULg; Cazorla, Constantin ULg; Rauw, Grégor ULg

Poster (2014, July 01)

As a complement to the results from the Cyg OB2 Chandra Legacy program, we present in this contribution the detailed analysis of the four X-ray bright massive stars dominating the cluster. Cyg OB2 #5, #8A ... [more ▼]

As a complement to the results from the Cyg OB2 Chandra Legacy program, we present in this contribution the detailed analysis of the four X-ray bright massive stars dominating the cluster. Cyg OB2 #5, #8A, and #9 are binary or multiple massive stars in the Cyg OB2 association displaying several peculiarities, such as bright X-ray emission and non-thermal radio emission. Our X-ray monitoring of these stars reveals the details of their behavior at high energies, which can be directly linked to wind-wind collisions (WWCs). In addition, the X-ray emission of Cyg OB2 #12, an evolved massive star, shows a long-term decrease, which could hint at the presence of a companion (with associated colliding winds) or indicate the return to quiescence of the system following a recent eruption. [less ▲]

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