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See detailComparaison of the flower scents of two Impatiens species
Marlet, Christelle ULg; Lognay, Georges ULg; Jacquemart, Anne-Laure et al

Poster (2010, September 27)

The Giant balsam, Impatiens glandulifera Royle (Balsaminaceae) was introduced in Europe from the Himalayas as a garden ornamental plant in 1839. Due to its great success from nursery gardeners (1), it is ... [more ▼]

The Giant balsam, Impatiens glandulifera Royle (Balsaminaceae) was introduced in Europe from the Himalayas as a garden ornamental plant in 1839. Due to its great success from nursery gardeners (1), it is now considered as one of the 100 worst invasive species in Europe. On the contrary, the native I. noli-tangere L. is considered to be in decline. Both species are annuals that absolutely need reproductive output to maintain or extend their populations. High fecundity has frequently been associated with invasiveness. However, traits controlling the reproductive success like pollinator attractiveness have not yet been assessed. The alien species is profusely visited by bumblebees which constituted the main visitors and efficient pollinators (2-3). The native also presents traits linked to insect attractiveness. Flowers produced similar quantities of nectar with the same sugar concentration and composition than the exotic. Therefore, the native could be considered as valuable source of nectar for pollinators. Despite the fact that nectar reward is likely to influence pollinator attractiveness, I. noli-tangere only occasionally received visits. Indeed, a flower of the native is 40 times less visited than a I. glandulifera flower (3). Differences in visitation rates may be explained by several factors, as floral scents, UV patterns or floral display. In summer 2009, a first comparative study of floral scents between these two species was performed. An active sampling in a small glass chamber able to contain single flower left on the plant had been performed on a sorbent tube with Carbograph and Tenax TA. The volatiles of floral scents had been analysed by thermal desorption coupled to gas chromatography and mass spectrometry (4, 5). The composition of flower scents on the basis of area percent of identified peaks had been compared. Terpenes (d-limonene, α-terpinolene, p-cymene, α and β-terpineol) were emitted by the flowers of both species. Higher monoterpenes proportion in area percent was detected for the native species. Terpenes such as β-myrcene, 1,4-cineole, eucalyptol, carveol were absent in the flower scent of the alien I. glandulifera. However, the alien presented a higher alcane proportion. The implication of terpenes in the attractiveness of bumblebees will be studied. [less ▲]

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See detailComparaison of three supplements high in linseeds or linseed oil in dairy cows
Cabaraux, Jean-François ULg; Marche, C.; Hornick, Jean-Luc ULg et al

in Book of absracts of the 54th Annual Meeting of the European Association for Animal Production (2003)

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See detailComparaison par modélisation de la production de ruissellement de toitures stockantes (toitures végétalisées et toiture bac)
Beckers, Eléonore ULg

Master's dissertation (2007)

Rainwater runoff management is becoming extremely complex as the result of the increasingly impervious nature of urban and suburban surfaces. Urbanisation can indeed lead to high volumes of surface water ... [more ▼]

Rainwater runoff management is becoming extremely complex as the result of the increasingly impervious nature of urban and suburban surfaces. Urbanisation can indeed lead to high volumes of surface water runoff. This undesirable effect could be reduced by disconnecting roofs from the sewer system. This study represents a first attempt to establish a model concerning green roofs and flat roof storage systems based on a physical approach method. The aim is to deduce their respective effect on water runoff management by analysing and comparing their performance based on a long period of meteorological conditions data (1989-1995). [less ▲]

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See detailComparaison par simulation de 3 types d'unités d'échantillonage en futaies feuillues de hêtre (Fagus silvatica L.).
Hebert, Jacques ULg; Rondeux, Jacques ULg; Laurent, C.

in Annales des Sciences Forestières (1988), 45(3), 209-222

This study is dealing with the choice of the size and the type of sampling units which could be used in inventories of beech stands (Fagus silvatica L.). Two experimental areas of 16 hectares have been ... [more ▼]

This study is dealing with the choice of the size and the type of sampling units which could be used in inventories of beech stands (Fagus silvatica L.). Two experimental areas of 16 hectares have been considered in evenaged and unevenaged structures. Three types of sampling units were studied : fixed circular plots, Bitterlich plots (non fixed circular plots) and circular plots including a minimum of number of trees (15-20). As regards to the estimations of basal area and number of trees per hectare there is no significative difference between plots of fixed area and plots including a minimum number of trees even if plot sizes and stand structure vary. As expected, compared to the other methods, the Bitterlich plots give little more precise estimations of basal area and less precise estimations of number of trees. The plots with a minimum number of trees would give higher values compared to the other types of plots but no significative difference have been observed. Numerous simulations show that in case of a fixed total cost the use of a great number of small units or of a limited number of large units has little effect on the standard error of estimations. The concept of minimum number of trees (15-20) seems to be valuable according to a compromise between precision and cost. To avoid a risk of bias in stands including large empty zones, it is preferable to use plot radii suitable to normal conditions. [less ▲]

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See detailComparaison pratique de quelques méthodes d'analyse discriminante
Lazaar, N.; Palm, Rodolphe ULg

in Biométrie-Praximétrie (1994), 34

Dans cette étude, on compare les performances des trois méthodes d'analyse discriminante suivantes : analyse discriminante linéaire, analyse discriminante quadratique et analyse discriminante logistique ... [more ▼]

Dans cette étude, on compare les performances des trois méthodes d'analyse discriminante suivantes : analyse discriminante linéaire, analyse discriminante quadratique et analyse discriminante logistique. Les performances sont étudiées dans le cas de données réelles, en envisageant diverses transformations de variables destinées à modifier les conditions de normalité et d'égalité des variances entre populations. Aucune différence significative de performances entre méthodes n'a pu être mise en évidence au niveau de signification de 0,05. Par contre, les performances des trois méthodes diminuent quand les distributions des variables sont nettement non normales ou de variances très inégales. Différentes estimations des taux d'erreur ont également été comparées : resubstitutin, extraction-insertion et utilisation d'un échantillon-test. Les résultats ont montré que, par rapport à l'utilisation d'échantillons-tests, la méthode de resubstitution sous-estime le taux d'erreur. Cette sous-estimation est de l'ordre de 13 % du taux d'erreur réel. La méthode d'extraction-insertion donne par contre des résultats très semblables à la méthode utilisant un échantillon-test. [less ▲]

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See detailComparaison quantitative de différentes techniques de restauration rapide dans les réseaux IP/MPLS
Mélon, Laurent; Leduc, Guy ULg

in Obaid, A. (Ed.) Ingénierie des protocoles - Réseaux mobiles et ad hoc, qualité de service, multimédia, ingénierie de trafic (2002, May 27)

This article is dealing with a quantitative comparison of different fast restoration approaches in the context of a Multi-Protocol Label Switching (MPLS) network. The objective is to analyse the general ... [more ▼]

This article is dealing with a quantitative comparison of different fast restoration approaches in the context of a Multi-Protocol Label Switching (MPLS) network. The objective is to analyse the general behaviour of these approaches (local rerouting, edge-to-edge rerouting, ...) in case of failure by means of simulations. This study is realised in the context of Best Effort only traffic, routing being done with a shortest paths algorithm. Many papers justify the choice between an edge-to-edge or a local scheme by means of intuition and then present a new algorithm for routing backup paths which try to optimize some parameters. Our approach aims to clarify the situation by comparing by means of concrete results the pros and cons of each mechanism. [less ▲]

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See detailComparaisons calculs-essais pour l'éprouvette cylindrique
Beckers, Pierre ULg; Debongnie, Jean-François ULg; Masset, Luc ULg

Report (1996)

In this first application of the machining simulation tool prototype, great difficulties were encountered in the interpretaion of the physical test. In fact, parasitic deformations occured, with a three ... [more ▼]

In this first application of the machining simulation tool prototype, great difficulties were encountered in the interpretaion of the physical test. In fact, parasitic deformations occured, with a three-lobed form. This implied the necessity of filtering the experimental data and a physical interpretation of the undue deformation. A theoretical study is performed, leading to the result that this phenomenon is due to the combined effect of the clearance of the clamping jaws and the pre-stress of the dead center. [less ▲]

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See detailComparaisons calculs-essais pour le carter d'alimentation d'huile TA96
Beckers, Pierre ULg; Debongnie, Jean-François ULg; Masset, Luc ULg

Report (1996)

On this application, the computed results were in the opposite direction as compared to the physical tests. A sound analysis led to the result that a parasitic deformation was due to clamping deformations ... [more ▼]

On this application, the computed results were in the opposite direction as compared to the physical tests. A sound analysis led to the result that a parasitic deformation was due to clamping deformations. In fact, the three supports of the work were found to be unsufficiently coplanar. [less ▲]

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See detailComparaisons calculs-essais pour le palier de suspension J64
Beckers, Pierre ULg; Debongnie, Jean-François ULg; Masset, Luc ULg

Report (1996)

This report is devoted to the J64 suspension bearing benchmark. Unfortunately, the actual machining led to considerable vibrations, rendering any comparison impossible.

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See detailComparant mais pas fondateur
Caprasse, Olivier ULg

in Revue de Jurisprudence de Liège, Mons et Bruxelles (2002)

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See detailLe comparatisme du P. Thomassin
Droixhe, Daniel ULg

in De Clercq, J.; Desmet, P. (Eds.) Florilegium historiographiae linguisticae : Études d'historiographie de la linguistique et de grammaire comparée : à la mémoire de Maurice Leroy (1994)

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See detailComparatisme et transversalité
Delville, Michel ULg; Belloi, Livio ULg

Scientific conference (2006, October 11)

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See detailComparatisme institutionnel et analyse sémiotique du discours métalittéraire francophone : problèmes d’une recherche en cours
Provenzano, François ULg

in Wilhelm, Frank; Baustert, Raymond; Colas-Blaise, Marion (Eds.) et al Le Blé en herbe : actes des premières Journées des Jeunes chercheurs/euses en Littérature et Linguistique françaises (2007)

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See detailComparative advertising versus non comparative advertising in social marketing : the case of tap water
Delcourt, Cécile ULg

Master of advanced studies dissertation (2007)

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See detailComparative analyses of salivary proteins from three aphid species
Vandermoten, Sophie ULg; Harmel, Nicolas; Mazzucchelli, Gabriel ULg et al

in Insect Molecular Biology (2013), under publication

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See detailComparative analysis between analytical approximations and numerical solutions describing recession flow in unconfined hillslope aquifers
Rocha, David; Feyen, Jan; Dassargues, Alain ULg

in Hydrogeology Journal (2007), 15(6), 1077-1091

Recession flow of aquifers from a hillslope can be described by the non-linear Boussinesq equation. Under strong assumptions and for specific conceptual formulations, different authors derived analytical ... [more ▼]

Recession flow of aquifers from a hillslope can be described by the non-linear Boussinesq equation. Under strong assumptions and for specific conceptual formulations, different authors derived analytical approximations or linearized versions to this partial differential equation. A comparative analysis between some analytical approximations of the Boussinesq equation and the numerical solution of the recession flow of an unconfined homogeneous aquifer (horizontal, inclined and concave aquifer floor) was carried out. The objective was to define the range where the analytical solutions approximate the numerical solution. The latter was considered in this study as the reference method, because it requires fewer assumptions. From the considered analytical approximations, exponential decay relationships were found to be mainly valid for fine domain materials when horizontal, mild slopes (less than 2%) and concave aquifer floors were considered, but failed to reproduce coarse aquifer numerical model outflows, in contrast to the quadratic decay relationship, which better reproduce outflows in such domains. On the basis of the comparative analysis, it has been found that recession flows obtained with the considered analytical approximations yield similar values only for certain ranges of aquifer properties and geometries. [less ▲]

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See detailA comparative analysis between the time trade-off and the willingness to pay approaches in hip and knee osteoarthritis
Ethgen, Olivier ULg; Tancredi, Annalisa ULg; Lejeune, Eric ULg et al

in Osteoporosis International (2002, November), 13(Suppl. 3), 47

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See detailComparative analysis of SST interannual variability in the Western Mediterranean Sea and North-East Atlantic Ocean
Djenidi, Salim ULg; Kostianoy, Andrey; Lacroix, Geneviève et al

in Annales Geophysicae. Series B, Terrestrial and Planetary Physics (1998), 16(suppl. II),

Detailed reference viewed: 5 (0 ULg)