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See detailAgisme et jeunisme: Conséquences trop méconnues par les cliniciens et les chercheurs
Adam, Stéphane ULg

Scientific conference (2014, June 26)

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See detailRasa3 Controls Megakaryocyte Rap1 Activation, Integrin Signaling and Differentiation into Proplatelet
Molina Ortiz, Patricia ULg; Polizzi, Séléna; Ramery, Eve ULg et al

in PLoS Genetics (2014), 10(6), 1004420

Rasa3 is a GTPase activating protein of the GAP1 family which targets Ras and Rap1. Ubiquitous Rasa3 catalytic inactivation in mouse results in early embryonic lethality. Here, we show that Rasa3 ... [more ▼]

Rasa3 is a GTPase activating protein of the GAP1 family which targets Ras and Rap1. Ubiquitous Rasa3 catalytic inactivation in mouse results in early embryonic lethality. Here, we show that Rasa3 catalytic inactivation in mouse hematopoietic cells results in a lethal syndrome characterized by severe defects during megakaryopoiesis, thrombocytopenia and a predisposition to develop preleukemia. The main objective of this study was to define the cellular and the molecular mechanisms of terminal megakaryopoiesis alterations. We found that Rasa3 catalytic inactivation altered megakaryocyte development, adherence, migration, actin cytoskeleton organization and differentiation into proplatelet forming megakaryocytes. These megakaryocyte alterations were associated with an increased active Rap1 level and a constitutive integrin activation. Thus, these mice presented a severe thrombocytopenia, bleeding and anemia associated with an increased percentage of megakaryocytes in the bone marrow, bone marrow fibrosis, extramedular hematopoiesis, splenomegaly and premature death. Altogether, our results indicate that Rasa3 catalytic activity controls Rap1 activation and integrin signaling during megakaryocyte differentiation in mouse. [less ▲]

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See detailDétection de l'érosion dans un bassin versant agricole par comparaison d'images multidates acquises par drone
Lisein, Jonathan ULg; Pineux, Nathalie ULg; Pierrot-Deseilligny, Marc et al

Conference (2014, June 26)

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See detailA probabilistic model of the adhesive contact forces between rough surfaces in the MEMS stiction context
Hoang Truong, Vinh ULg; Wu, Ling ULg; Arnst, Maarten ULg et al

Conference (2014, June 26)

Stiction is a common failure mechanism in microelectromechanical systems (MEMS) in which two interacting bodies permanently adhere together. This problem is due to the comparability of adhesive surface ... [more ▼]

Stiction is a common failure mechanism in microelectromechanical systems (MEMS) in which two interacting bodies permanently adhere together. This problem is due to the comparability of adhesive surface forces (e.g. Van der Waals forces, capillary forces) and body forces in the MEMS context. To predict the adhesive contact forces coupled with stiction phenomenon, the combination of the Nayak statistical approach with the asperity-based theories is a common solution. However, this method contains some limitations due to the underlying assumptions: infinite size of the interacting rough surfaces and negligibility of asperity interactions. Furthermore, the Nayak solution suffers from a considerable dependency on the choice of the minimum wave length considered in the surface representation, which remains diXcult to select. The main goal of our research is to propose an improved method (i) which accounts for the Vnite size of the interacting surfaces, (ii) accounts for the uncertainties related to these surface topologies, (iii) in which the minimum wave length selection is physically based, and (iv) in which the validity of the asperity-based theories is demonstrated. From the topology measurements of MEMS samples, an analysis of the power spectral density function is carried out to determine the minimum relevant wave length for the problem of interest (here capillary stiction). We also show that at this scale of interest the asperity-based theories remain valid for polysilicon materials. Moreover, instead of considering inVnite surfaces as in the Nayak approach, a set of surfaces, whose sizes are representative of the MEMS structure, is generated based on the approximated power spectral density analysis and using the Monte Carlo method. From this description of the contacting surfaces, the adhesive contact forces can be evaluated by applying the asperity contact theories, leading to a probabilistic distribution of the adhesive contact forces. In addition, as the contact forces are rooted from the micro-scale adhesive forces, while their consequence, stiction, happens at the macro-scale of the considered device, the multi-scale nature of the phenomenon is accounted for. To predict this macro-scale behavior in a probabilistic form, the uncertainty quantiVcation process is coupled with a multiscale analysis. [less ▲]

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See detailPLANTIGRADY DUE TO A LOCALIZED MYOPATHY IN TWO NEWBORN BELGIAN BLUE CALVES
Genart, Marie; Evrard, Laurence ULg; Garcia da Fonseca et al

Poster (2014, June 26)

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See detailEtude des racémases RacX et YlmE et de la protéine PBP4* de Bacillus subtilis en relation avec la désintégration de biofilms
Vanden Broeck, Arnaud ULg

Master's dissertation (2014)

Bacillus subtilis is a PGPR (Plant Growth Promoting Rhizobacterium) Gram positive bacterium and a model for studying the in vitro formation, maturation or disruption of biofilms. Biofilms have been ... [more ▼]

Bacillus subtilis is a PGPR (Plant Growth Promoting Rhizobacterium) Gram positive bacterium and a model for studying the in vitro formation, maturation or disruption of biofilms. Biofilms have been studied for many years because of their adverse effects in the medical sphere. Some D-amino acids have been reported among the factors playing a role in the disassembly of B. subtilis biofilms and a double ylmE and racX mutant (in which both YlmE and RacX racemases are absent) shows a delay in pellicle disruption [I. Kolodkin et al. Science (2010) 328:627-629]. The racX encoding gene is part of a bicistronic operon in which the first gene (pbpE) codes for a putative Penicillin-Binding Protein, the PBP4* whose function is not characterized. Results from DNA microarrays and Proteomics [D. Ren et al. Biotechnology and Bioengineering (2004) 86:344-364] have shown that in B. subtilis biofilms, the expression of the gene coding for PBP4* is increased. Our study in this master thesis aimed to investigate the functions and the structures of the RacX, YlmE and PBP4* proteins. A wide range of techniques such as cloning, into expression vectors, purification, treatment of the recombinant proteins by specific proteases to eliminate the chromatography affinity tags, structural and biochemical characterizations of the proteins have been used. According to sequence analyses, RacX belongs to the Asp/Glu racemase family. We succeeded to produce and purify 34 mg of RacX whose His-tag has been completely eliminated. The protein appeared active on D-Glutamate as substrate but inactive on D-Aspartate. A physiological role is proposed for RacX in the recovery of D-Glu from the peptidoglycan peptides. However, its implication in the biofilm disassembly process is still elusive. The YlmE racemase was also produced and purified (46 mg). Although a role in the in vivo production of D-Tyrosine in B. subtilis ageing biofilms has been proposed for this protein, our attempts to detect an activity on L-Tyr or any other amino acid remained unsuccessful. Bioinformatic studies relate YlmE to type III PLP dependent enzymes close to Alanine racemases. Alignments of YlmE with Alanine racemases pointed out that a C-terminal domain was missing in YlmE. A model has been proposed to explain the absence of YlmE activity. Several constructs were performed to restore a racemase activity: e.g. a fusion of YlmE to the C-terminal domain of the AlaR2 racemase from B. subtilis, but the chimeric protein was insoluble, or the fusion of the AlaR2 C-terminal domain to TrxA in view to obtain in trans complementation with purified YlmE. PBP4* (encoded by pbpE) has been purified (63 mg) and two activities were detected: L-aminopeptidase and DD-carboxypeptidase activities. This PBP is composed of two distinct domains : a N-Terminal catalytic domain related to the D-aminopeptidase from Ochrobactrum anthropic and a C-terminal one that has a lipocalin-like fold. This domain seems involved in the oligomerization of the protein. First attempts of X-Ray diffraction of the entire protein crystals did not give data with sufficient resolution. Therefore, each domain has been separately produced to determine the 3D structure of this unusual PBP. [less ▲]

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See detailL’ancrage dans les herbiers à Posidonia oceanica. Conséquences chimiques de la destruction mécanique ?
Abadie, Arnaud ULg

Poster (2014, June 26)

La plante marine endémique de Méditerranée Posidonia oceanica, ou posidonie, forme en Corse des herbiers colonisant les substrats depuis la surface jusqu’à 40 m de profondeur. Ces herbiers constituent un ... [more ▼]

La plante marine endémique de Méditerranée Posidonia oceanica, ou posidonie, forme en Corse des herbiers colonisant les substrats depuis la surface jusqu’à 40 m de profondeur. Ces herbiers constituent un véritable écosystème, l’un des plus riches en espèces de Méditerranée. Ils jouent un rôle écologique essentiel en oxygénant le milieu grâce à la photosynthèse et en séquestrant du CO2 au sein de leur complexe racinaire dans le sédiment (ou "matte"). Ces activités métaboliques entraînent une importante modification des conditions biogéochimiques du substrat qui favorisent le maintien de la plante. Les herbiers ont également une grande importance économique servant de nurserie pour de nombreuses espèces exploitées par la pêche commerciale et récréative. Les herbiers de posidonie se développant dans les zones côtières, ils sont impactés par les activités anthropiques (urbanisation, pollution, fermes aquacoles, ancrage) qui peuvent entraîner d’importantes destructions et des régressions de leur zone de recouvrement. L’ancrage intensif dans les herbiers à faible profondeur y génère des trouées, ou "intermattes". Les destructions engendrées par les navires de petite taille (< 10 m) peuvent, dans certaines conditions, être recolonisées par la posidonie. Cependant, dans la plupart des zones d’ancrage intensif en Corse, les intermattes ne sont pas recolonisées et leur surface peut souvent augmenter. De plus, certaines zones sont soumises à l’ancrage intensif de navires de plaisance de grande taille (> 20m), susceptibles de générer des intermattes d’une étendue plus importante. Ce phénomène d’expansion ne peut s’expliquer par la seule destruction mécanique. L’arrachage de la strate foliaire de la posidonie par les ancres semble entraîner de profondes modifications physiques et chimiques dans le sédiment. La photosynthèse via les feuilles étant ainsi altérée, il n’y a plus d’oxygénation du sédiment via les racines de la posidonie et un milieu anoxique défavorable à son développement paraît se créer. Des composés toxiques pour la plante, tel que le sulfure d’hydrogène (H2S), pourraient alors s’introduire dans ses tissues entraînant une limitation de son développement, voire sa disparition menant ainsi à une amplification des dégâts mécaniques de l’ancrage. Des observations seront réalisées tout autour de la Corse et notamment dans la Baie de Calvi, site atelier de la Méditerranée, qui a été définie pour mener la phase d’expérimentation. Les données récoltées à l’issue de ces travaux de recherches, réalisés dans le cadre d’un doctorat en entreprise (bourse CIFRE), seront compilées afin de mettre au point de nouveaux outils d’analyse de l’impact de l’ancrage. [less ▲]

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See detailBone markers in patients with CKD
CAVALIER, Etienne ULg

Conference (2014, June 26)

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See detailPoéticas del fracaso en la narrativa de David Toscana
Scheffer, Aurélie ULg

Doctoral thesis (2014)

Jusqu'à ce jour, l’œuvre de David Toscana (Monterrey, 1961) n'a été abordée par la critique que timidement et de façon partielle. Parmi cette maigre littérature critique, il est intéressant de remarquer ... [more ▼]

Jusqu'à ce jour, l’œuvre de David Toscana (Monterrey, 1961) n'a été abordée par la critique que timidement et de façon partielle. Parmi cette maigre littérature critique, il est intéressant de remarquer la fréquence d’occurrence d'un mot en particulier: “échec” (fracaso). Cette thèse se propose d'examiner les différentes manifestations intratextuelles de l'échec (Bärtschi et Leuzinger) dans l’œuvre toscanienne, c'est-à-dire, les formes fictionnelles de l'échec. Nous avons choisi de diviser notre étude en deux chapitres principaux: personnages et espace. Dans le premier, nous mettons en relation la notion d'échec et les divers protagonistes qui peuplent l'univers toscanien et tentons de comprendre dans quelle mesure ces derniers peuvent recevoir le qualificatif de “ratés” (fracasados). Plus concrètement, cette observation des personnages principaux favorise la réflexion sur ce que David Freundenthal appelle échec interne, en d'autres termes, l'échec très personnel et subjectif que ressent et vit l'individu, frustré dans ses désirs, ses projets et ses tentatives. À notre étude de l'échec interne correspond une perspective d'analyse interne: dans un premier temps, nous privilégions une approche de l’œuvre essentiellement orientée vers le texte même, et par conséquent, volontairement détachée de son contexte. Si nous optons pour ce type d'approche, nous nous refusons cependant à nous limiter à une analyse strictement thématique. Ainsi, nous pensons l'échec tant d'un point de vue thématique qu'en fonction de ses manifestations dans le processus d'écriture, c'est-à-dire, à travers les techniques et structures narratives appliquées au texte littéraire. L’œuvre du narratologue français Gérard Genette intitulée Figures III nous sert d'appui théorique dans l'appréhension des formes narratives de l'échec. Le second chapitre met l'accent sur la relation entre échec et espace narratif. En réalité, tous les personnages de Toscana partagent un même espace, le Mexique. Selon nous, la représentation que l'auteur fait de cet espace est à son tour inséparable de la notion d'échec. Aux antipodes des “foundational fictions” (Sommer), l’œuvre met en scène une nation désunie, incapable de se définir, d'assumer le passer et d'aller vers l'avant, incapable de synthétiser ses divergences, de respecter ses traditions, de s'identifier à un profil de valeurs propre. Ainsi, par exemple, la famille et la religion apparaissent, sous la plume de Toscana, comme des valeurs stériles et insubstantielles. Cette approche ne renvoie donc plus à l'échec interne mais bien à l'échec diagnostiqué de l'extérieur ou échec externe, selon l'expression de Freundenthal: indirectement et avec subtilité, Toscana postule le non-aboutissement d'un projet, celui qui aspirait à la constitution d'une nation mexicaine forte et cohésive, orientée vers l'avenir. Ce second chapitre repose sur les principes majeurs de l'analyse du discours. Pratiquer l'analyse du discours suppose l'acceptation que chaque phrase porte en elle un message qui la dépasse et dont le sens est à chercher tant dans son contexte d'énonciation que d’interprétation. Rejetant l'opposition traditionnelle entre texte et contexte, entre un “intérieur” et un “extérieur”, l'analyse du discours littéraire privilégie une conception du texte comme maillon d'une longue chaîne appelée “interdiscours” et qui correspond à “l'ensemble des unités discursives avec lesquelles un discours particulier entre en relation implicite ou explicite” (Charaudeau et Maingueneau 2005: 334). Le texte littéraire est donc à considérer “relationnellement et historiquement” (Meizoz 2010: 66) puisqu'il s'inscrit toujours dans un processus de communication, dans un échange réel ou virtuel avec la parole d'autrui. Adoptant cette perspective, nous décidons de chercher et de créer du sens à travers la mise en relation du texte toscanien avec un certain discours sur la mexicanité. En fait, l'échec se manifeste selon nous à travers la présence d'une série d'images nationales stéréotypées que l'écrivain régiomontain récupère et manipule à sa guise dans l'ensemble de son œuvre. De ce jeu avec les stéréotypes découle la construction d'un imaginaire national déterminé traduisant, de manière implicite et symbolique, l'échec de la nation mexicaine. Ainsi, nous insistons notamment sur l’affinité entre la fiction toscanienne et le célèbre discours sur la mexicanité d'Octavio Paz, énoncé dans son essai Le labyrinthe de la solitude. Plus que de simples traces de banalité, ces stéréotypes qui envahissent l’œuvre de Toscana constituent à nos yeux de véritables éléments narratifs dotés d'une fonction constructive et productive propre. La théorie des stéréotypes, une des nombreuses théories littéraires qui se revendiquent de l'analyse du discours, constitue le cadre théorique principal de ce second chapitre. [less ▲]

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See detailA wavelet leaders-based climate classification of European surface air temperature signals
Deliège, Adrien ULg; Nicolay, Samuel ULg

Conference (2014, June 25)

We present the wavelet leaders method as a tool to study the pointwise regularity of signals, which is closely related to some functional spaces. We use the associated multifractal formalism to show that ... [more ▼]

We present the wavelet leaders method as a tool to study the pointwise regularity of signals, which is closely related to some functional spaces. We use the associated multifractal formalism to show that the surface air temperature signals are monofractal, i.e. these are regularly irregular. Then we use this result to establish a climate classification of weather stations in Europe which matches the Köppen-Geiger climate classification. This result could give rise to new criteria to determine the effectiveness of current climatic models. [less ▲]

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See detailA wavelet leaders-based climate classification of European surface air temperature signals
Deliège, Adrien ULg; Nicolay, Samuel ULg

in Ruiz Garcia, Gonzalo; Rojas Ruiz, Ignacio (Eds.) Proceedings of the International work-conference on Time Series: Volume 1, Granada 25-27 June 2014 (2014, June 25)

We explain the wavelet leaders method, a tool to study the pointwise regularity of signals, which is closely related to some functional spaces. We use the associated multifractal formalism to show that ... [more ▼]

We explain the wavelet leaders method, a tool to study the pointwise regularity of signals, which is closely related to some functional spaces. We use the associated multifractal formalism to show that surface air temperature signals are monofractal, i.e. these climate time series are regularly irregular. Then we use this result to establish a climate classification of weather stations in Europe which matches the Köppen-Geiger climate classification. This result could give rise to new criteria to determine the efficiency of current climatic models. [less ▲]

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See detailEfficacy of seed extracts of Annona squamosa and Annona muricata (Annonaceae) for the control of Aedes albopictus and Culex quinquefasciatus (Culicidae)
Raveloson Ravaomanarivo, Lala Harivelo; Andrianiaina Razafindraleva, Herisolo; Raharimalala, Fara Nantenaina ULg et al

in Asian Pacific Journal of Tropical Biomedicine (2014), 4(10), 787-795

Objective: To evaluate the potential efficacy of seed extracts of Annona squamosa and Annona muricata used as natural insecticides to control adult and larvae of the vectors Aedes albopictus and Culex ... [more ▼]

Objective: To evaluate the potential efficacy of seed extracts of Annona squamosa and Annona muricata used as natural insecticides to control adult and larvae of the vectors Aedes albopictus and Culex quinquefasciatus under laboratory conditions. Methods: Aqueous and oil extracts of the two plants were prepared from dried identifications of the chemical components of each seed extracts were performed using microreactional and GCP Technique. Larvea and adults of Aedes albopictus and Culex quinquefasciatus were collected for the breeding sites in coastal and highlands regions of Madagascar. WHO standardized tests of susceptibility for larvae and imaginal stage of mosquitoes were realized to 50 of mosquitoes. Results: Chemical identifications showed that these extracts contain alkaloids and flavonoids compounds that probably confer their biological insecticidal propriety. CPG analysis showed also the presenceof various fatty acids. On adults mosquitoes, significant insecticidal effects were observed with both aqueous and oil extracts of the two plant seeds compared to mortality induced by deltamethrin, an insecticide used as reference. Extracts of Annona muricata induced high mortality rate to both species of mosquito compared to extracts of Annona squamosa at all concentrations 50 of seed extracts ranged from 1% to 5% for adults and 0.5% to 1% for larvae. Conclusions: The seed extracts of these two plants may be used as mosquito controlling agents and offer a new approach to a less costly, pratical and environmentally friendly control of vector borne diseases. [less ▲]

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See detailQuelles marges budgétaires pour relancer la Wallonie?
Piron, Damien ULg

Article for general public (2014)

Le PS et le cdH négocient actuellement la formation du gouvernement de la Région wallonne. Il y a fort à parier que ces deux partis chercheront à poursuivre la stratégie de redéploiement économique ... [more ▼]

Le PS et le cdH négocient actuellement la formation du gouvernement de la Région wallonne. Il y a fort à parier que ces deux partis chercheront à poursuivre la stratégie de redéploiement économique amorcée il y a une quinzaine d’années au travers du Contrat d’Avenir pour la Wallonie et prolongée dans deux versions successives du Plan Marshall. De récents développements dans le champ de la comptabilité publique risquent toutefois de contraindre le prochain exécutif régional à de douloureux arbitrages budgétaires. [less ▲]

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See detailVehicle routing problems with multiple trips: using specific local search operators
Arda, Yasemin ULg; Crama, Yves ULg; François, Véronique ULg et al

Conference (2014, June 25)

In vehicle routing problems with multiple trips (VRPM), each vehicle is allowed to perform more than one trip during its working period. Classical solution techniques for this problem make use of existing ... [more ▼]

In vehicle routing problems with multiple trips (VRPM), each vehicle is allowed to perform more than one trip during its working period. Classical solution techniques for this problem make use of existing VRP heuristics to create trips, together with bin packing methods aimed at assigning these trips to the available vehicles. The first contribution of this work is to propose specific local search operators for the VRPM. The operators directly integrate the multi-trip structure of the problem within well-known VRP operators. As a second contribution, heuristics using these operators are compared with classical solution techniques mentioned above. The comparison is performed by using the adaptive large neighborhood search metaheuristic as a common basis for both methods. The most classical version of the problem is studied as well as a variant involving time windows [less ▲]

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See detailTurning land to livelihood : what are the socio-economic and institutional determinations of local land use in Red River Delta region ?
Nguyen Thi, Dien; Lebailly, Philippe ULg; Vu Dinh, Ton

Conference (2014, June 24)

This research analyzes the determinations of household land use strategy in the context of the rapid rural changes due to the industrialization and urbanization in Vietnam. The mechanism that turns land ... [more ▼]

This research analyzes the determinations of household land use strategy in the context of the rapid rural changes due to the industrialization and urbanization in Vietnam. The mechanism that turns land to livelihood from both productive and non-productive processes is investigated to understand the different land use strategies of smallholders in Red River Delta region. Based on the presence of migrating members, the total selected 191 households in Hai Duong province were divided into 3 different groups to do the surveys. The research results show that local land use strategies are various in which 79.06% of surveyed households maintain the allocated land for agricultural production while 65.97% of households leave land idly at least once a year. The factors from productive process such as small landholding, high production cost and overall downward income from agricultural production meantime the greater opportunities from non-farm jobs are the main socio-economical determinations of agricultural land abandonment or less effective use. The security questions of shifting livelihood between farming and non – farming sectors, the inter-household arrangements, the social supports and the institutional constraints are non-productive elements that make the exchange and other forms of commercializing agricultural land are less prominent. The complexity of household land use strategy and its determinations not only reflects the dynamism and flexibility of peasant’s livelihood adaptation but also explain why the land concentration does not proceed faster in Red River Delta region of Vietnam. [less ▲]

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