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See detailLeaf fall impact on diversity and trophic ecology of vagile macrofauna associated with exported P.oceanica litter
Remy, François ULg; Mascart, Thibaud ULg; Dauby, Patrick ULg et al

Poster (2012, August 20)

In the Mediterranean Sea, Posidonia oceanica meadows produce a huge amount of detritus, evaluated up to 300 to 2000 g dry wt m-2 yr-1. This litter is mainly composed of dead leaves but also of uprooted P ... [more ▼]

In the Mediterranean Sea, Posidonia oceanica meadows produce a huge amount of detritus, evaluated up to 300 to 2000 g dry wt m-2 yr-1. This litter is mainly composed of dead leaves but also of uprooted P.oceanica shoots and drift macro-algae from adjacent rocky bottoms. Although rich in refractory materials (lignin) and poor in P and N, these underwater accumulations of leaves are colonised by fungi, micro-algae (like diatoms), bacteria, but also by micro and macrofauna assemblages. These organisms could play an important role in leaf litter degradation and enrichment, but also in energy and carbon transfer from P.oceanica to higher trophic levels in adjacent coastal ecosystems. In this study we focus on the vagile macro-fauna (invertebrates with a size > 500µm) inhabiting the exported litter accumulations of the Calvi Bay (France). We took standardised samples at two different sites (a sheltered one and an exposed one) before and after leaf fall. We emphasised that crustaceans represent 65 – 85% of the biodiversity, followed by annelids and molluscs, representing respectively 10-20% and 10-15% of the diversity. That general pattern differs between sampling sites and we highlighted changes after leaf fall at both sites. In order to assess the impact of the autumn period litter input on the trophic structure of these invertebrates, we conducted gut contents observations and “bulk” stable isotope analysis. The isotopic compositions of C and N stable isotopes of the potential detritic food sources and of the most abundant invertebrate’s species were measured using EA-IRMS. We finally focused on the two most abundant Gammaridean Amphipoda species representing up to about 60% of the vagile macrofauna found in litter accumulations: Gammarella fucicola and Gammarus aequicauda. The results of their isotopic measurements were used in the “SIAR” Bayesian mixing model to calculate the potential contribution of their potential food sources. [less ▲]

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See detailLeaf morphology evolution in euphyllophytes of South China through the Late Palaeozoic inferred from numerical analyses
Huang, P.; Xue, J.; Benton, M. J. et al

in Cascales - Miñana, Borja; Villanueva-Amadoz, Uxue; Diez, José B. (Eds.) Proceedings of the II Agora Paleobotanica Meeting (Abstract book) (2013, July)

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See detailLEAFY expression and temporal sequence of floral transition in Sinapis alba L.
Bonhomme, Delphine ULg; Périlleux, Claire ULg

Poster (2005)

The shoot apical meristem (SAM) of Sinapis alba can be switched from vegetative to reproductive fate by exposure of 2-month old plants to a single long day (LD). Floral transition then occurs in good ... [more ▼]

The shoot apical meristem (SAM) of Sinapis alba can be switched from vegetative to reproductive fate by exposure of 2-month old plants to a single long day (LD). Floral transition then occurs in good synchrony within a population, and a number of biochemical, cellular, and morphological changes have been described. Our aim is to integrate gene expression patterns into this timing. We report here the analysis of SaLFY, orthologous to the floral meristem identity gene LEAFY of Arabidopsis. Materials and Methods: Plants of Sinapis were grown in 8-h shorts days for two months before being induced to flower by one 22-h LD. Shoot apices were harvested 24, 32, 40, 48, 56 and 80h after start of the LD, and prepared for in situ hybridization (Melzer et al., 1999). Results and Conclusions: As expected, the expression of SaLFY was very strong in flower primordia. More surprisingly, SaLFY was expressed well before the initiation of flowers. First, a strong signal was detected in the tip of young leaf primordia of vegetative plants. Secondly, SaLFY was transiently expressed in the SAM of induced plants, from 32h after the start of the LD, when cell proliferation increased. The signal formed, in transverse sections, a discontinuous ring with activation where last leaves were to be initiated. Interestingly, this activation in the SAM matched in time and space early growth changes previously described during the transition to flowering, namely an increase of leaf primordia growth and an acceleration of last leaf initiation (Bernier, 1997), suggesting that SaLFY may have dual functions in fate specification during the floral transition of the SAM. References: Bernier G 1997. J Exp Bot 48; 1071-1077. Melzer S, Kampmann G, Chandler J, Apel K 1999. Plant J 18; 395-405. [less ▲]

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See detailLeakage tests applied to the breadboards
Dardenne, Laurent; Ngendakumana, Philippe ULg

Report (2007)

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See detailThe leaky funnel model revisited
Mouchet, Anne ULg; Deleersnijder, Eric; Primeau, François

in Tellus : Series A (2012), 64

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See detailThe leaky funnel model, a metaphor of the ventilation of the World Ocean as simulated in an OGCM
Mouchet, Anne ULg; Deleersnijder, Eric

in Tellus : Series A (2008), 60(4), 761-774

It is seen that an idealized model may suggest an appropriate scaling of the water age in the World Ocean, which is a measure of the ventilation rate. We use a 1-D advection-diffusion model in which the ... [more ▼]

It is seen that an idealized model may suggest an appropriate scaling of the water age in the World Ocean, which is a measure of the ventilation rate. We use a 1-D advection-diffusion model in which the deep ocean is represented as a leaky funnel, allowing recirculation towards the surface. The analytical solutions to the steady-state problem are readily obtained. The three parameters of the leaky funnel model are estimated in such a way that the behaviour of the domain-averaged water age be as similar as possible to that derived from a 3-D model in a series of sensitivity runs. The agreement between both sets of mean ages is excellent, with a linear correlation coefficient very close to unity. A good agreement is also found for the age of radioactive tracers and the associated radioages. The parameters of the leaky funnel model have a clear physical meaning, that is, the order of magnitude of the horizontal velocity, the mean length of water parcel trajectories in the deep ocean, and a horizontal diffusivity scale. The values of all of them turn out to be consistent with our current knowledge of the World Ocean circulation. [less ▲]

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See detailLearn-Nett : un dispositif d'apprentissage collaboratif à distance au service de la formation des enseignants. Communication présentée au séminaire de recherche 'Technologies de l'Information et de la Communication pour l'Education : instruments, dispositifs et usages, Paris, INRP
Denis, Brigitte ULg; Peeters, Robert ULg

Scientific conference (2002, March)

Présentation du dispositif d'apprentissage collaboratif Learn-Nett. Options épistémologiques, organisation, compétences visées chez les apprenants, méthodologie, tutorat.

Detailed reference viewed: 43 (2 ULg)
See detailLearn-Nett : une expérience d'apprentissage collaboratif à distance
Denis, Brigitte ULg; Peeters, Robert

in Actes du 1er congrès des chercheurs francophones en éducation (2000, May)

Présentation du dispositif d'apprentissage collaboratif (Learn-Nett).

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See detailLEARN-NETT : une expérience d'apprentissage collaboratif à distance
Charlier, Bernadette; Daele, Amaury; Docq, Françoise et al

in Le point sur la recherche en éducation en Communauté française : actes du 1er congrès des chercheurs en éducation, Bruxelles, 24-25 mai 2000 (1998)

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See detailLearned material content and acquisition level modulate cerebral reactivation during posttraining rapid-eye-movements sleep
Peigneux, Philippe ULg; Laureys, Steven ULg; Fuchs, Sonia et al

in NeuroImage (2003), 20(1), 125-134

We have previously shown that several brain areas are activated both during sequence learning at wake and during subsequent rapid-eye-movements (REM) sleep (Nat. Neurosci. 3 (2000) 831-836), suggesting ... [more ▼]

We have previously shown that several brain areas are activated both during sequence learning at wake and during subsequent rapid-eye-movements (REM) sleep (Nat. Neurosci. 3 (2000) 831-836), suggesting that REM sleep participates in the reprocessing of recent memory traces in humans. However, the nature of the reprocessed information remains open. Here, we show that regional cerebral reactivation during posttraining REM sleep is not merely related to the acquisition of basic visuomotor skills during prior practice of the serial reaction time task, but rather to the implicit acquisition of the probabilistic rules that defined stimulus sequences. Moreover, functional connections between the reactivated cuneus and the striatum-the latter being critical for implicit sequence learning-are reinforced during REM sleep after practice on a probabilistic rather than on a random sequence of stimuli. Our results therefore support the hypothesis that REM sleep is deeply involved in the reprocessing and optimization of the high-order information contained in the material to be learned. In addition, we show that the level of acquisition of probabilistic rules attained prior to sleep is correlated to the increase in regional cerebral blood flow during subsequent REM sleep. This suggests that posttraining cerebral reactivation is modulated by the strength of the memory traces developed during the learning episode. Our data provide the first experimental evidence for a link between behavioral performance and cerebral reactivation during REM sleep. (C) 2003 Elsevier Inc. All rights reserved. [less ▲]

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See detailLearner Support in the Formasup degree: variety as a key feature and close coaching to drive innovation
Poumay, Marianne ULg

in Supporting the Learner in Distance Education and E-Learning (2004)

Detailed reference viewed: 27 (11 ULg)
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See detailLearning a Dictionary of Prototypical Grasp-predicting Parts from Grasping Experience
Detry, Renaud ULg; Ek, Carl Henrik; Madry, Marianna et al

in IEEE International Conference on Robotics and Automation (2013)

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See detailLearning a motor skill: Effects of blocked versus random practice. A review
Merbah, Sarah ULg; Meulemans, Thierry ULg

in Psychologica Belgica (2011), 51

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See detailLearning a motor skill: Effects of Blocked vs. Random Practice. A review
Merbah, Sarah ULg; Meulemans, Thierry ULg

in Psychologica Belgica (2011), 51(1), 15-48

Procedural learning refers to the ability to learn new perceptual, motor or cognitive skills. While many studies have explored procedural learning abilities in patients with different types of brain ... [more ▼]

Procedural learning refers to the ability to learn new perceptual, motor or cognitive skills. While many studies have explored procedural learning abilities in patients with different types of brain damage, the cognitive mechanisms involved in the acquisition of a new skill are still not well understood. The present review focuses on the conditions that optimize skill acquisition, and more specifically on the contextual interference effect (CIE), which refers to the advantage of a ‘random’ over a ‘blocked’ practice condition in skill learning tasks. According to both the ‘elaboration’ and ‘reconstruction’ hypotheses, the CIE can be explained by the fact that the random schedule requires more cognitive activity than the blocked one. However, if the CIE has been consistently demonstrated in laboratory studies, it is not so clear in fieldbased studies. We discuss this ‘laboratory and field dilemma’, and suggest that two main factors – task complexity and individual variables – may explain the discrepancy between the two types of studies. [less ▲]

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See detailLearning about domestic violence- gender violence and women victimization
Garcet, Serge ULg

Conference given outside the academic context (2004)

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See detailA learning algorithm for synfire chains
Sougné, Jacques ULg

in French, R.; Sougné, Jacques (Eds.) Connectionist models of learning : Development and Evolution (2001)

Detailed reference viewed: 12 (2 ULg)
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See detailLearning and Error Reproduction in Alzheimer Disease
Wansard, Murielle ULg; Erkès, jérôme; Adam, Stéphane ULg et al

Poster (2012, July 15)

Alzheimer disease (AD) is characterized by an early impairment of explicit memory processes associated to a preservation of implicit memory processes (Fleischman & Gabrieli 1998). Due to the role of ... [more ▼]

Alzheimer disease (AD) is characterized by an early impairment of explicit memory processes associated to a preservation of implicit memory processes (Fleischman & Gabrieli 1998). Due to the role of explicit memory in the suppression of errors during learning, AD patients tend to reproduce automatically (implicitly) errors that occurred during a previous learning (Baddeley & Wilson, 1994). Consequently, errorless learning should be more efficient than a classical “trial-and-error” procedure for AD patients. Indeed, errorless learning decreases the involvement of (impaired) explicit memory by avoiding the interference caused by the production of errors (Bier et al., 2002). The present study investigates the automatic post-learning error production in mild AD patients and matched control subjects by using a word stem completion task (Adam et al., 2005) in conditions of both errorless and trial-and-error learning. Results showed a lower word stem completion performance in mild AD than control subjects, but a similar performance in the patients’ group for the two learning conditions. Moreover, in the trial-and-error procedure, the errors consisted mainly in erroneous responses already produced during the learning phase. In addition, correlation analyses indicate that the ability to suppress errors in the trial-and-error learning condition in mild AD patients is subtended by the efficiency of episodic memory processes, but not by inhibitory abilities. These results suggest that the errorless procedure improves the quality of learning of mild AD patients (production of fewer errors) but do not influence the learning rate per se. [less ▲]

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See detailLearning and motivation to transfer after an e-learning programme: Impact of trainees’ motivation to train, personal interaction and satisfaction
Peters, Stéphanie ULg; Barbier, Marie ULg; Faulx, Daniel ULg et al

in Innovations in Education & Teaching International (2012), 49(4), 375-387

While e-learning appears to be increasingly present in training and education, the systematic evaluation of its effectiveness remains understudied. In this paper, we determine the mediating role of ... [more ▼]

While e-learning appears to be increasingly present in training and education, the systematic evaluation of its effectiveness remains understudied. In this paper, we determine the mediating role of satisfaction between motivation to train and personal interaction on the one hand, and learning and motivation to transfer, on the other hand. A particularity of this study is that we distinguish between different dimensions of satisfaction - enjoyment, utility, difficulty, and take into account lack of personal interaction as a variable influencing satisfaction. Results of structural equation modelling analyses show an impact of the enjoyment dimension on learning, and of the utility and difficulty dimensions on motivation to transfer. The results also stress the importance of interaction opportunities, as these have an indirect effect on learning and motivation to transfer. [less ▲]

Detailed reference viewed: 151 (30 ULg)