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See detailLe fonctionnement exécutif dans le vieillissement normal : l’effet médiateur de la vitesse de traitement et du système attentionnel
Gilsoul, Jessica ULg; Simon, Jessica ULg; Collette, Fabienne ULg

Poster (2017, May 19)

Introduction. Le vieillissement normal est associé à une diminution d’efficacité des fonctions exécutives. Cependant, la source de ces difficultés pourrait résider dans certains facteurs « non exécutifs » ... [more ▼]

Introduction. Le vieillissement normal est associé à une diminution d’efficacité des fonctions exécutives. Cependant, la source de ces difficultés pourrait résider dans certains facteurs « non exécutifs ». Dès lors, cette étude a pour but de déterminer si la vitesse de traitement et les variables attentionnelles pourraient médier l’effet de l’âge sur le fonctionnement exécutif. Méthode. Des participants jeunes (N = 104) et âgés (N = 63) ont réalisé une batterie de 21 tâches exécutives (inhibition, flexibilité, mise à jour, et coordination de double tâches), attentionnelles (alerte phasique, attention sélective, et attention soutenue), et de vitesse de traitement. Des modèles de médiation avec la vitesse de traitement et le fonctionnement attentionnel pris séparément comme médiateurs ont été réalisés. Résultats. L’attention sélective médie significativement l’effet de l’âge sur la mise à jour [ΔR2 = 7%, p < ,001]. De plus, la vitesse de traitement médie significativement l’effet de l’âge sur la flexibilité [ΔR2 = 7%, p < ,001], la mise à jour [ΔR2 = 5%, p < ,001], et la coordination de double tâches [ΔR2 = 14%, p < ,001].Discussion. La médiation de l’effet de l’âge sur la plupart des fonctions exécutives par les mesures de vitesse est en accord avec la littérature montrant une grande influence d’un ralentissement de la vitesse de traitement sur la cognition. L’effet de l’âge sur l’inhibition ne semble médié par aucune des variables attentionnelles et de vitesse, ce qui est en accord avec l’hypothèse selon laquelle l’inhibition serait la première fonction cognitive à décliner avec l’avancée en âge (Zacks & Hasher,1988). [less ▲]

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See detailDu définitif sur du provisoire...
Englebert, Jérôme ULg; Follet, Valérie

Conference (2017, May 18)

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Peer Reviewed
See detailRadiohead and Prog Rock
Delville, Michel ULg

Conference (2017, May 18)

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Peer Reviewed
See detailAller au spectacle
Brahy, Rachel ULg

Conference (2017, May 18)

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See detailMécanismes de vieillissement des anodes à base de FeSn2 pour batteries Li-ion
Chamas, Mohamad; Mahmoud, Abdelfattah ULg; Tang, junlei et al

Poster (2017, May 18)

Les intermétalliques d’étain ont été proposés comme matériaux d’anode pour batteries Li-ion à forte densité d’énergie car leur capacité spécifique est bien supérieure à celle des anodes commerciales à ... [more ▼]

Les intermétalliques d’étain ont été proposés comme matériaux d’anode pour batteries Li-ion à forte densité d’énergie car leur capacité spécifique est bien supérieure à celle des anodes commerciales à base de carbone. Le mécanisme électrochimique est basé sur la transformation irréversible de FeSn2 en un composite formé de nanoparticules de fer et de Li3.5Sn lors de la première lithiation, puis de réactions réversibles modifiant la composition de Li3.5Sn, les particules de fer assurant la dispersion de ces particules à base d’étain [1]. Cependant, nous avons observé que l’électrode lithiée était instable dans le temps conduisant à l’autodécharge progressive de la batterie [2]. Ce phénomène de vieillissement a été caractérisé par spectrométrie Mössbauer du 57Fe et de 119Sn, par spectroscopie d’impédance et par mesures magnétiques (Figure 1). On montre que le composite Fe/Li3.5Sn se délithie progressivement au cours du temps conduisant à un composite faiblement lithié Fe/LixSn avec x<1. Les nanoparticules de fer sont stables et ne réagissent pas avec LixSn. Les atomes de lithium libérés réagissent avec l’électrolyte et modifient la morphologie de la couche SEI (Surface Electrolyte Interphase) située à la surface des particules LixSn du composite.[1] M. Chamas, M. T. Sougrati, C. Reibel, P.E. Lippens, Chem. Mater. 25, 2410 (2015). [2] M. Chamas, A. Mahmoud, J. Tang, S. Panero, M. T. Sougrati, P. E. Lippens, J. Phys Chem. C 121, 217 (2017). [less ▲]

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See detailStructural and Magnetic Properties of Nanosized strontium Hexaferrite Powders: Experimental and theoretical investigation
Abraime, Brahim; Ait Tamerd, Mohamed; Mahmoud, Abdelfattah ULg et al

Poster (2017, May 18)

Strontium M-type hexagonal ferrites were synthesized at different calcination temperatures (800 °C, 1000°C and 1100 °C) using sol-gel autocombustion method. Thermogravimetric analysis (TGA), X-ray ... [more ▼]

Strontium M-type hexagonal ferrites were synthesized at different calcination temperatures (800 °C, 1000°C and 1100 °C) using sol-gel autocombustion method. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy (MS) and superconducting quantum interference device magnetometer (SQUID) techniques were used to characterize crystal structure, phase composition, morphology and magnetic properties. TGA gives T=800 °C as beginning of suitable calcination. Hexaferrite structure of single phase is obtained according to XRD results for all samples with crystallite size between 28 nm and 35 nm. SEM images show the growth of grain size with increasing of annealing temperature. (BH)max is calculated based on SQUID results and shows an enhancement between T=800°C and T= 1000°C of 25%. The magnetic properties observed at low temperature are explained and confirmed by ab-initio calculations. [less ▲]

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See detailApplication of wavelet transforms to geosciences: Extraction of functional and frequential information
Deliège, Adrien ULg

Doctoral thesis (2017)

It is now well-known that there exist functions that are continuous but nowhere differentiable. Still, it appears that some of them are less “irregular” than others. The pointwise regularity of a function ... [more ▼]

It is now well-known that there exist functions that are continuous but nowhere differentiable. Still, it appears that some of them are less “irregular” than others. The pointwise regularity of a function can be characterized by its Hölder exponent at each point. For the sake of practicability, it is more appropriate to determine the “size” of the sets of points sharing a same exponent, through their Hausdorff measure. By doing so, one gets the multifractal spectrum of a function, which characterizes in particular its monofractal or multifractal nature. The first part of this work is based on the so-called “wavelet leaders method” (WLM), recently developed in the context of multifractal analysis, and aims at its application to concrete situations in geosciences. First, we present the WLM and we insist particularly on the major differences between theory and practice in its use and in the interpretation of the results. Then, we show that the WLM turns out to be an efficient tool for the analysis of Mars topography from a unidimensional and bidimensional point of view; the first approach allowing to recover information consistent with previous works, the second being new and highlighting some areas of interest on Mars. Then, we study the regularity of temperature signals related to various climate stations spread across Europe. In a first phase, we show that the WLM allows to detect a strong correlation with pressure anomalies. Then we show that the Hölder exponents obtained are directly linked to the underlying climate and we establish criteria that compare them with their climate characteristics as defined by the Köppen-Geiger classification. On the other hand, the continuous version of the wavelet transform (CWT), developed in the context of time-frequency analysis, is also studied in this work. The objective here is the determination of dominant periods and the extraction of the associated oscillating components that constitute a given signal. The CWT allows, unlike the Fourier transform, to obtain a representation in time and in frequency of the considered signal, which thus opens new research perspectives. Moreover, with a Morlet-like wavelet, a simple reconstruction formula can be used to extract components. Therefore, the second part of the manuscript presents the CWT and focuses mainly on the border effects inherent to this technique. We illustrate the advantages of the zero-padding and introduce an iterative method allowing to alleviate significantly reconstruction errors at the borders of the signals. Then, we study in detail the El Niño Southern Oscillation (ENSO) signal related to temperature anomalies in the Pacific Ocean and responsible for extreme climate events called El Niño (EN) and La Niña (LN). Through the CWT, we distinguish its main periods and we extract its dominant components, which reflect well-known geophysical mechanisms. A meticulous study of these components allows us to elaborate a forecasting algorithm for EN and LN events with lead times larger than one year, which is a much better performance than current models. After, we generalize the method used to extract components by developing a procedure that detects ridges in the CWT. The algorithm, called WIME (Wavelet-Induced Mode Extraction), is illustrated on several highly non-stationary examples. Its ability to recover target components from a given signal is tested and compared with the Empirical Mode Decomposition. It appears that WIME has a better adaptability in various situations. Finally, we show that WIME can be used in real-life cases such as an electrocardiogram and the ENSO signal. [less ▲]

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See detailThe epistemic politics of TA institutionalization and international TA collaboration – a cosmopolitan perspective
Rosskamp, Benedikt ULg

Conference (2017, May 18)

When addressing the issue of further institutionalization of TA, two assumptions need to be empirically confronted and conceptually revisited. A first one considers the evolution of TA as a linear ... [more ▼]

When addressing the issue of further institutionalization of TA, two assumptions need to be empirically confronted and conceptually revisited. A first one considers the evolution of TA as a linear progression leading to new institutional creations in an increasing number of countries. Despite a series of calls for distributed, networked, multi-level and multi-actor TA capacities, the idea of creating more single, national, specialized and dedicated TA organizations remains dominant in TA discourse. A second assumption concerns the rationale of Technology Assessment and its performance in terms of “opening up” and “broadening out” (Ely et al. 2014) or “the reflexivity pathway” (Delvenne 2011), notably by resorting to participatory Technology Assessment. Results from case studies in Wallonia, Portugal and the Czech Republic require reconsidering the above-mentioned evolutionary assumptions for a more complex and paradoxical understanding of the future of TA. While the TA achievements in each case study are still uncertain to a high degree, we can sum up these respective TA developments under the banner of “evidence-based governance”. This particular understanding of knowledge and decision-making is coherent with a simultaneous observed shift away from the institutional deficit of TA (creating new institutions in newcomer countries) to a renewed strategy of resorbing a knowledge deficit (making TA knowledge available to a wider number of countries). This renewed approach to TA collaboration and capacity building increasingly gains traction both from a bottom-up perspective where actors try to organize themselves into a critical mass and in a top-down perspective of neoliberal and austerity policies. In such a constellation, positivistic science provides an evidence-base, which supposedly supports multi-level, multi-actor governance as it allows knowledge produced in one place to travel and serve a wide spectrum of actors and decision-making arenas. The consequences of this shift are crucially important to explore the re-makings and futures of Technology Assessment, as they put to the fore the issue of subsidiarity of both the production and the use of TA knowledge. Finally, we identify a shift from coexistence to a cosmopolitan mode of epistemic subsidiarity (Jasanoff 2013, 2014). The latter raises a series of new theoretical, practical and normative questions for the TA community. [less ▲]

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See detailElections présidentielles française de 2017: analyse des résultats.
Verjans, Pierre ULg

Conference given outside the academic context (2017)

A la suite d'une campagne électorale particulièrement agitée, les deux principaux partis du pays depuis des décennies ne sont pas parvenus à placer leur candidat au deuxième tour. Les résultats et leurs ... [more ▼]

A la suite d'une campagne électorale particulièrement agitée, les deux principaux partis du pays depuis des décennies ne sont pas parvenus à placer leur candidat au deuxième tour. Les résultats et leurs conséquences méritent une analyse et une réflexion collective. [less ▲]

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Peer Reviewed
See detailAn exceptional Proterozoic assemblage of organic-walled microfossils and its implications for the early evolution of Eukaryotes
Loron, Corentin ULg; Rainbird, Rob; Greenman, Wilder et al

Conference (2017, May 18)

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See detailL’influence normative de la Chine en Amérique centrale: quels enjeux stratégiques ?
Wintgens, Sophie ULg

Conference (2017, May 18)

La République populaire de Chine (Chine) est aujourd’hui devenue un partenaire commercial incontournable, un important pourvoyeur d’investissements directs étrangers et un grand fournisseur de prêts ... [more ▼]

La République populaire de Chine (Chine) est aujourd’hui devenue un partenaire commercial incontournable, un important pourvoyeur d’investissements directs étrangers et un grand fournisseur de prêts financiers pour un nombre croissant de pays d’Amérique du Sud. Cette tendance s’observe également de plus en plus en Amérique centrale. L’accroissement de ses échanges économiques et commerciaux avec le Costa Rica, membre du Système d’intégration centraméricain (SICA) et premier pays centraméricain à avoir signé un accord de libre-échange avec Pékin, va de pair avec l’imposition des normes économiques et politiques dont sa politique commerciale internationale est porteuse. Ce constat pose dès lors la question du défi stratégique que représente cette influence normative chinoise pour les normes exportées par l’UE en Amérique centrale. Afin de répondre à cette question, cette communication se propose d’analyser la portée normative de la politique commerciale de la Chine envers l’Amérique centrale, afin de voir si elle est porteuse d’un projet politico-économique régional comparable au modèle d’intégration et de gouvernance régionale déployé par l’Europe communautaire dans le sous-continent. [less ▲]

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See detailThe earliest eukaryotes
Javaux, Emmanuelle ULg

Conference (2017, May 18)

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See detailDesign of reprocessable poly(ɛ-caprolactone)-based shape-memory materials
Defize, Thomas ULg

Doctoral thesis (2017)

Shape-memory polymers (SMPs) are remarkable materials able to switch from a temporary shape to their initial permanent shape by crossing a thermal transition, e.g. glass or melting transition. Efficient ... [more ▼]

Shape-memory polymers (SMPs) are remarkable materials able to switch from a temporary shape to their initial permanent shape by crossing a thermal transition, e.g. glass or melting transition. Efficient shape-memory effect is notably observed for chemically cross- linked semi-crystalline polymers. Chemical networks of semi-crystalline poly(ε-caprolactone) (PCL) are widely studied for the development of SMPs especially when biomedical applications are foreseen. As these SMPs are irreversibly cross-linked material, their (re)processing is quite limited since they cannot be molten or solubilized after cross-linking. This prevents any recycling. Thereby, using reversible cross-linking reactions allowing the formation or cleavage of the network upon a selected stimulus raise tremendous interest for the development of smart SMPs. Chemically cross-linked but remarkably (re)processable shape-memory polymers (SMP) were designed by crosslinking poly(ε-caprolactone) (PCL) stars via reversible cycloaddition reactions. The thermo-reversible Diels-Alder (DA) reaction between furan and maleimide was investigated to crosslink the PCL matrix. However, the relatively low retro DA temperature of the furan-maleimide adducts led to some inelastic deformation during shape memory tensile cycles. In order to get rid of this drawback, two alternative approaches were investigated, i.e. the substitution of the DA reaction firstly by the efficient triazolinedione click chemistry, especially the very fast and reversible Alder-ene reaction of 1,2,4-triazoline-3,5- dione (TAD) with indole compounds and secondly by a photo-reversible reaction, typically the photo-induced (2+2) cycloaddition of coumarins. With these networks, the typical shape memory properties of PCL networks (high fixity and recovery ratios) were preserved while upon an external (light or stress) stimulus, the PCL network can be (re)processed efficiently. [less ▲]

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See detailThe prevention of fragility fractures in patients with non-metastatic prostate cancer: a position statement by the international osteoporosis foundation.
CIANFEROTTI, L; BERTOLDO, F; CARINI, M et al

in Oncotarget (2017)

Androgen deprivation therapy is commonly employed for the treatment of nonmetastatic prostate cancer as primary or adjuvant treatment. The skeleton is greatly compromised in men with prostate cancer ... [more ▼]

Androgen deprivation therapy is commonly employed for the treatment of nonmetastatic prostate cancer as primary or adjuvant treatment. The skeleton is greatly compromised in men with prostate cancer during androgen deprivation therapy because of the lack of androgens and estrogens, which are trophic factors for bone. Men receiving androgen deprivation therapy sustain variable degrees of bone loss with an increased risk of fragility fractures. Several bone antiresorptive agents have been tested in randomized controlled trials in these patients. Oral bisphosphonates, such as alendronate and risedronate, and intravenous bisphosphonates, such as pamidronate and zoledronic acid, have been shown to increase bone density and decrease the risk of fractures in men receiving androgen deprivation therapy. Denosumab, a fully monoclonal antibody that inhibits osteoclastic-mediated bone resorption, is also effective in increasing bone mineral density and reducing fracture rates in these patients. The assessment of fracture risk, T-score and/or the evaluation of prévalent fragility fractures are mandatory for the selection of patients who will benefit from antiresorptive therapy. In the future, new agents modulating bone turnover and skeletal muscle metabolism will be available for testing in these subjects. [less ▲]

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