Last 7 days
Bookmark and Share    
Full Text
See detailOviposition deterring effect of Ocimum basilicum L. (Lamiaceae) on Tuta absoluta Meyrick (Lepidoptera: Gelechiidae)
Yarou, Boni Barthélémy ULg; Bawin, Thomas ULg; Boullis, Antoine ULg et al

Poster (2016, December 02)

Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is one of the most important pests of tomato, reducing crop yield in greenhouses and fields, in several countries around the world. Because synthetic ... [more ▼]

Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is one of the most important pests of tomato, reducing crop yield in greenhouses and fields, in several countries around the world. Because synthetic insecticides lead to resistance and have adverse effects on natural enemies and producers’ health, there is a need for alternatives. In this study, we assess the oviposition deterring effect of O. basilicum using dual-choice behavioral assays performed in flight tunnels. Two modalities were tested, i.e. (1) a tomato plant associated either with an O. basilicum plant versus a tomato plant associated with a plastic pot only filled with potting soil, and (2) a tomato plant with basil essential oil (EO) formulated in paraffin oil (PO) versus a tomato plant with PO only. A 1 ml cylindrical polyethylene plug loaded with 100 µl of solution (formulated EO or PO) was placed on each plant as a diffuser. Forty-eight hours after the release of unsexed adult individuals randomly sampled from the rearing in the central area of the tunnel, we found that plants and EOs reduced T. absoluta oviposition behavior on a nearby located tomato plant. GC-MS analyses showed that the major constituents include estragol (73.8%), linalool (8.6%), β-elemene (2.9%) in O. basilicum essential oils and E-α-bergamotene (38.9%), methyl eugenol (26.1 %), E-β-ocimene (17.7 % ) in O. basilicum VOCs collected with solid-phase micro-extraction method. These results suggest a valuable potential of O. basilicum and associated essential oils as component of an integrated management strategy against the tomato leafminer. [less ▲]

Detailed reference viewed: 50 (4 ULg)
Peer Reviewed
See detailDésir, mal d'enfant, stérilité
Naziri, Despina ULg

Conference (2016, December 02)

Detailed reference viewed: 32 (2 ULg)
Peer Reviewed
See detailQuelques réflexions autour d'un texte de Théodore Scaltsas
Dawans, Stéphane ULg; Houbart, Claudine ULg

Conference (2016, December 02)

Face à l’extension du champ de l’intervention sur l’existant et au brouillage des limites entre rénovation et restauration d’édifices et d’ensembles allant du monument historique au bâti générique, ancien ... [more ▼]

Face à l’extension du champ de l’intervention sur l’existant et au brouillage des limites entre rénovation et restauration d’édifices et d’ensembles allant du monument historique au bâti générique, ancien ou récent, il semble plus que jamais utile d’accepter la notion de bricolage conceptuel et de réfléchir à une « boîtes à outils » permettant aux futurs architectes de faire face à la complexité des enjeux de la réhabilitation. En effet, face à ceux-ci, les théories de la restauration monumentale qui sont enseignées dans les instituts et facultés d’architecture atteignent parfois leurs limites et nous semblent devoir être complétées par/confrontées à de nouveaux concepts ou théories susceptibles d’élargir et même de renouveler notre vision des choses. C’est ainsi que depuis plusieurs années, nous avons choisi de faire un pas de côté et d’interroger des champs aussi éloignés que la logique formelle, l’ontologie de l’art et les théories littéraires et travaillons actuellement à une anthologie critique de textes variés mais tous susceptibles d’intéresser les conservateurs (du patrimoine mobilier et immobilier) et donc aussi, les architectes intervenant sur l’existant. Parmi ces textes, oeuvres d’auteurs en grande partie méconnus dans le champ du patrimoine, « Identity, Origin and spatio-temporal continuity », du philosophe Théodore Scaltsas, professeur à l’université d’Edimbourg, et extrait d’une revue en grande partie écrite en langage mathématique, nous parait particulièrement intéressant à analyser lors du séminaire. En utilisant des exemples aisément transposables au milieu de l’architecture, il aborde notamment la question de l’intention d’une reconstruction de manière originale et interpellante, qui n’autorise plus les fréquents amalgames justifiant tout et n’importe quoi et émanant non seulement du monde économique mais aussi des milieux du patrimoine dits autorisés. Par ailleurs, il enrichit le débat sur l’authenticité d’une dimension peu prise en compte à ce jour et particulièrement éclairante dans le cas des productions modernes et contemporaines, qui constituent l’un des enjeux les plus actuels de la réhabilitation. [less ▲]

Detailed reference viewed: 21 (2 ULg)
Full Text
Peer Reviewed
See detailLa reconnaissance des génocides et la répression du négationnisme
Grandjean, Geoffrey ULg

in Courrier Hebdomadaire du CRISP (2016), 2304-2305

La reconnaissance politique d’un génocide et la répression de la négation de celui-ci représentent deux enjeux d’une grande importance symbolique. Surtout, elles constituent un exercice très délicat pour ... [more ▼]

La reconnaissance politique d’un génocide et la répression de la négation de celui-ci représentent deux enjeux d’une grande importance symbolique. Surtout, elles constituent un exercice très délicat pour l’autorité politique qui pose de tels actes. Il s’agit en effet de consacrer une vérité historique et de dicter le souvenir qui doit en être véhiculé. L’intervention d’une instance politique dans le champ de l’histoire et de la mémoire est toujours entourée de nombreux débats. Les discussions, souvent vives, portent sur diverses questions. Le principe d’une action législative dans un tel domaine est-il recevable et pertinent ? Quelle définition de « génocide » convient-il d’adopter ? La répression du négationnisme est-elle de nature à justifier une limitation de la liberté d’expression ? Si oui, dans quelle mesure cette restriction s’applique-t-elle aussi aux chercheurs ? Lorsqu’il s’agit d’événements historiques relatifs à un autre État, faut-il faire primer l’éthique et la morale sur la diplomatie ? Les réponses à ces interrogations fondamentales se cristallisent dans des lignes de fracture qui échappent aux clivages partisans classiques. En Belgique, les initiatives de reconnaissance des crimes de génocide et de pénalisation de leur négation sont le fait des deux chambres du Parlement fédéral. Elles ont abouti à diverses dispositions législatives, telles la loi réprimant la négation du génocide commis par le régime nazi à l’encontre des Juifs pendant la Seconde Guerre mondiale (1995), une résolution relative au génocide perpétré par l’Empire ottoman à l’encontre des Arméniens en 1915 (1998), une résolution sur le génocide des Tutsis au Rwanda en 1994 (2004) et une résolution relative à la commémoration du centenaire du génocide arménien (2015). G. Grandjean retrace et éclaire l’ensemble des débats parlementaires qui se sont tenus en Belgique depuis 1992 autour de la question de la mémoire des crimes de masse. Son Courrier hebdomadaire offre les clés de lecture pour la compréhension des débats en cours quant à une extension de la loi de 1995. [less ▲]

Detailed reference viewed: 24 (4 ULg)
Full Text
See detailLa fiction au défi du virtuel
Huppe, Justine ULg

Scientific conference (2016, December 02)

Dans un premier temps, nous reviendrons sur la manière dont on a tenté de définir la fiction, à partir de ses « attracteurs sémantiques » (Schaeffer, 2005), puis en nous attachant à sa définition ... [more ▼]

Dans un premier temps, nous reviendrons sur la manière dont on a tenté de définir la fiction, à partir de ses « attracteurs sémantiques » (Schaeffer, 2005), puis en nous attachant à sa définition pragmatique qui domine largement aujourd’hui (de Searle à Caïra, en passant par Walton, Currie ou encore Schaeffer). Nous interrogerons quelques uns des concepts fondamentaux de cette approche (la feintise, l’immersion, le pacte pragmatique). Ensuite, nous nous intéresserons de plus près à un imaginaire lui aussi dominant : celui de la fiction définie comme « monde » ou « ouvreuse de mondes ». Il s’agira d’éclairer les conditions historiques dans lequel ce paradigme s’est forgé (lassitude du paradigme formaliste, développement de la logique des mondes possibles, popularisation des sciences cognitives, avènement des technologies virtuelles). Dans un second temps, nous nous intéresserons précisément à ces technologies qualifiées de « virtuelles ». Nous décrirons les caractéristiques du codage numériques et les possibilités qu’il offre à la fiction, tout en le replaçant dans une histoire culturelle qui, à l’avènement de nouvelles pratiques et supports pour la fiction, a souvent vu resurgir un certain argumentaire anti-mimétique. Nous mettrons également en lumière les enjeux que le numérique représente pour la fiction : ce qu’il déstabilise (ou non), mais surtout ce qu'il questionne (immersion, identification, frontière juridique…). [less ▲]

Detailed reference viewed: 18 (1 ULg)
Full Text
See detailSpace Thermal Analysis through Reduced Finite Element Modelling
Jacques, Lionel ULg

Doctoral thesis (2016)

The finite element method (FEM) is widely used in mechanical engineering, in particular for structure design. However, it is not often exploited for the thermal analysis of space structures for which the ... [more ▼]

The finite element method (FEM) is widely used in mechanical engineering, in particular for structure design. However, it is not often exploited for the thermal analysis of space structures for which the use of the lumped parameter method is still commonplace. To alleviate the computational burden of the FEM for thermal analyses involving conduction and radiation, an innovative global conductive-radiative reduction scheme based on the clustering of the finite element mesh is presented. The proposed method leads to a significant reduction of the number of radiative exchange factors (REFs) to compute and size of the corresponding matrix. It further keeps accurate conduction information by introducing the concept of physically meaningful super nodes associated to the clusters from which are derived the reduced conductive couplings. To complement the reduction of the number of faces, an improved Monte Carlo ray tracing algorithm is developed. It provides better accuracy and convergence rate than the classic Monte Carlo method. The algorithm is adapted to the partitioned FE mesh and includes quadrics fitting for accurate normal representation. The resulting conductive-radiative reduced model is solved using standard iterative techniques and the detailed mesh temperatures, recovered from the super nodes temperatures, can be directly exploited for thermo-mechanical analysis. The proposed global reduction method is validated on several space structures and is benchmarked against ESATAN-TMS, the standard thermal analysis software used in the European aerospace industry. [less ▲]

Detailed reference viewed: 71 (10 ULg)
See detailHow to use serology in Sexually Transmitted Infections
HUYNEN, Pascale ULg; LIBOIS, Agnes

Conference (2016, December 02)

Detailed reference viewed: 14 (1 ULg)
Full Text
See detailCooperative spontaneous emission with quantized atomic motion
Damanet, François ULg

Doctoral thesis (2016)

In this thesis, we present investigations on the cooperative dynamics of (ultra)cold atoms coupled to the electromagnetic field in vacuum. The main objective is to identify the consequences of the ... [more ▼]

In this thesis, we present investigations on the cooperative dynamics of (ultra)cold atoms coupled to the electromagnetic field in vacuum. The main objective is to identify the consequences of the quantization of the atomic center-of-mass motion on the atoms-field dynamics, more particularly the atomic \emph{internal} dynamics including dipole-dipole interactions and cooperative spontaneous emission processes. For this purpose, we derive a Markovian master equation for the internal state of a collection of two-level atoms coupled to vacuum accounting for all effects related to the quantization of their motion. These effects depend on three characteristic lengths that can be tuned experimentally: the interatomic distance $r$, the wavelength $\lambda$ of the emitted radiation, and the typical size $\ell$ of the atomic wave packets. This leads to a rich panel of phenomena depending on the hierarchy between these characteristic lengths. Our master equation provides a unifying picture of the consequences of recoil and quantum statistics (bosonic or fermionic) on both the internal dissipative and conservative dynamics, and applies equally well to distinguishable and indistinguishable atoms. It is valid even beyond the Lamb-Dicke regime, i.e.\ for large recoil effects. We give general expressions for the decay rates and the dipole-dipole shifts entering the master equation for arbitrary motional states, and we find closed-form formulas for a number of relevant states (Gaussian states, harmonic oscillator eigenstates, Bose-Einstein condensates motional states). In particular, we show they can be strongly influenced by the motional state of the atoms, which suggests the possibility to quantum program their internal dynamics through motional state engineering. Based on the derived master equation, we investigate in full detail the super- and subradiance phenomena arising from a collection of indistinguishable atoms. Due to the symmetry (for bosons) or antisymmetry (for fermions) of the global state under exchange of atoms, the internal dynamics is restricted to the permutation invariant subspace whose dimension grows as $N^2$ with $N$ the number of atoms. In this particular case, the master equation involves only three rates: a single-atom decay rate $\gamma_0$, a cooperative decay rate $\gamma$ and a collective dipole-dipole shift $\Delta_\mathrm{dd}$. We solve the dynamics exactly for $2$ atoms, numerically for up to $30$ atoms, and obtain the large-$N$ limit by a mean-field approach. We show that a superradiant enhancement of the radiated intensity is always observed for a sufficiently large number of atoms. As regards subradiance, we show that exact decoherence free subspaces that protect against spontaneous emission through destructive interference of individual spontaneous emission amplitudes exist only in the limit of classically localized atoms, i.e.\ for atoms in infinitely steep traps. We assess the validity of our master equation in the optical domain through the study of the exact atoms-field dynamics. Among others, this complementary approach gives access to the vibrational state populations of the atoms after a photon emission and to the angular dependence of the emission spectrum. It also highlights the complex interplay between the atomic internal and motional states, such as the entanglement transfer that can occur during the collective decay of the atoms. Moreover, it opens the door for the study of the non-Markovianity of the internal dynamics. In conclusion, our thesis provides a comprehensive picture of the consequences of the quantization of the atomic motion on cooperative spontaneous emission processes and contributes to the development of theoretical tools for the study of the internal dynamics of (ultra)cold atoms. [less ▲]

Detailed reference viewed: 17 (7 ULg)
See detailFrom Silenced Nature to Worldness in American Literature
Lombard, David ULg

Conference (2016, December 02)

As Christopher Manes writes, ‘[n]ature is silent in our culture […] in the sense that the status of being a speaking subject is jealously guarded as an exclusively human prerogative’ (Manes, 1996 ... [more ▼]

As Christopher Manes writes, ‘[n]ature is silent in our culture […] in the sense that the status of being a speaking subject is jealously guarded as an exclusively human prerogative’ (Manes, 1996). According to this view, nature is less silent than silenced, the difference lying in a refusal to have a relationship with the natural world because of the lack of adequate language to describe our relationship with our natural environment. Human faculties promoted by the Enlightenment have led humans to believe that our language ‘ha[s] no analogues in the natural world’. I will show that American authors such as Henry David Thoreau, John Muir, Aldo Leopold or Edward Abbey accounted for a multi-sensorial experience of nature that betrays an attempt to find a form of language that would relate humans to natural elements. Although nature does not ‘speak’, I will argue that humans were provided with their sensory perception that allows them to appreciate worldness and to develop a harmonious relationship with the rest of the world. I will also stress that our alienation from the natural world is as much a cultural problem as it is a consequence of Western consumer capitalism and supermodernity, as suggested, for example, in Don DeLillo’s White Noise (1985). Adopting an ecocritical approach, I will examine the ways in which we tend to perceive worldness as silent and how literary texts may revive worldness and world as essential concepts in the study of the relationship between literature and our physical environment. [less ▲]

Detailed reference viewed: 14 (1 ULg)
See detailInfectious disease of the eye: how to improve the microbiological diagnosis?
DESCY, Julie ULg

Conference given outside the academic context (2016)

Detailed reference viewed: 18 (0 ULg)
Peer Reviewed
See detailSchizophrénie et hyperconscience : Une étude en première personne
Englebert, Jérôme ULg; Valentiny, Caroline

Conference (2016, December 02)

Detailed reference viewed: 41 (1 ULg)
Full Text
See detailInflorescence development in tomato
Périlleux, Claire ULg

Scientific conference (2016, December 02)

Detailed reference viewed: 11 (1 ULg)
Full Text
See detailDevelopment and analysis of low-order models of frame structures under blast loads
Hamra, Lotfi ULg

Doctoral thesis (2016)

The main aim of this thesis is to propose an easy-to-apply tool to assess the level of damage of a structure in which one compartment is subjected to blast loading. This compartment is extracted from the ... [more ▼]

The main aim of this thesis is to propose an easy-to-apply tool to assess the level of damage of a structure in which one compartment is subjected to blast loading. This compartment is extracted from the structure accounting for the interaction with the part of the structure surrounding the loaded compartment, which is assumed to be elastic. Before studying the whole frame structure, the structural elements (i.e. the beam and its adjacent columns) are firstly studied separately taking into account the lateral restraint and mass offered by the indirectly affected part (IAP) of the structure. Secondly, the dynamic behaviour of a simple compartment made of pinned members and laterally braced is investigated. The material laws are assumed to be elastic-perfectly plastic, neglecting the effect of strain rate on the yield strength. The out-of-plane instabilities of the structural members are disregarded. • To explain the context of this study + final aim of this research Two analytical models are developed to predict the dynamic response of the frame beam subjected to blast loading, including the elastic lateral restraint and inertia offered by the IAP of the structure, the development of nonlinear membrane action (P-\delta effect) and also, the interaction between bending moment and axial force in the plastic hinges. The first model is based on a single degree of freedom (SDOF model) which is the transverse mid-span deflection of the beam while the second model is a two-degree-of-freedom (2-DOF) model which also includes the axial elongation of the beam. The accuracy of these two low-order models is assessed with finite element simulations. This validation stage shows that the proposed low-order models capture the physics of the problem in most cases of practical interest. A dimensional analysis of the problem reveals that, under the considered assumptions, four dimensionless parameters mainly influence the required ductility of the beam. Two of them are related to the behavior of the indirectly affected part (the lateral restraint and mass). Another one is related to the mechanical properties of the investigated beam (i.e. the ratio of the bending to axial resistance). The last parameter incorporates scales of the geometry and of the deformed configuration at the onset of the plastic mechanism. Concerning the columns, an analytical model is proposed to assess its dynamic response under constant axial compressive load and lateral blast loading. It accounts for large displacement (P-\delta effect), bending moment-axial force (M-N) plastic interaction as well as its interaction with the indirectly affected part (IAP) of the structure. This model is non-smooth piecewise linear and involves two degrees of freedoms (2 DOFs) in each regime of the motion of the column (related to the possibilities of development of plastic hinges). The dimensional analysis of the problem reveals that, under the considered assumptions, four dimensionless parameters mainly influence the dynamic stability of the beam-column. Two of them are related to the behavior of the indirectly affected part (the lateral restraint and mass). Another one is related to the critical load multiplier (i.e. the ratio of the axial compressive load to Euler elastic buckling resistance). The last parameter is the reduced slenderness of the beam-column. Subsequent to a parametric study, it is demonstrated that a good correlation is found between the results provided by the analytical model and a richer FEM model, despite some little discrepancies observed for some intermediate values of stiffness of the lateral restraint and lateral mass. As a possible improvement, adjustments to the analytical model are suggested. Finally, the dynamic behaviour of a simple frame under constant compressive loads and lateral blast loading is studied with a last 2-DOF analytical model. A multi-layer model of the cross-section of the beam is used to derive the bending moment-axial force (M-N) plastic interaction instead of the Lescouarc'h formula and normality rule. The coupling between the beam and the adjacent columns is ensured through appropriate boundary conditions. For the studied frame, two blast scenarios are contemplated, the first one corresponds to a quasi-static blast loading while the second one refers to a dynamic blast loading. The first case study shows that a very good agreement is achieved between the deflections predicted by the analytical and numerical models although a discrepancy is observed in the assessment of the axial force in the column due to the shape of the inertial force distribution of the beam assumed in the model. The second case study illustrates that, in both analytical and numerical models, the columns are predicted to fail by buckling due to the P-\delta effect although the axial force in the column is again inaccurately captured by the analytical model for the same reason. [less ▲]

Detailed reference viewed: 51 (10 ULg)
Full Text
See detailLa nostra «avvelenata» (Guccini non ne ha colpa)
Curreri, Luciano ULg; Belletti, Gabriele

Article for general public (2016)

Detailed reference viewed: 22 (2 ULg)