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See detailHow Does Pollen Chemistry Impact Development and Feeding Behaviour of Polylectic Bees?
Vanderplanck, Maryse; Moerman, Romain; Rasmont, Pierre et al

in PLoS ONE (2014), 9(1), 9

Larvae and imagos of bees rely exclusively on floral rewards as a food source but host-plant range can vary greatly among bee species. While oligolectic species forage on pollen from a single family of ... [more ▼]

Larvae and imagos of bees rely exclusively on floral rewards as a food source but host-plant range can vary greatly among bee species. While oligolectic species forage on pollen from a single family of host plants, polylectic bees, such as bumblebees, collect pollen from many families of plants. These polylectic species contend with interspecific variability in essential nutrients of their host-plants but we have only a limited understanding of the way in which chemicals and chemical combinations influence bee development and feeding behaviour. In this paper, we investigated five different pollen diets (Calluna vulgaris, Cistus sp., Cytisus scoparius, Salix caprea and Sorbus aucuparia) to determine how their chemical content affected bumblebee colony development and pollen/syrup collection. Three compounds were used to characterise pollen content: polypeptides, amino acids and sterols. Several parameters were used to determine the impact of diet on micro-colonies: (i) Number and weight of larvae (total and mean weight of larvae), (ii) weight of pollen collected, (iii) pollen efficacy (total weight of larvae divided by weight of the pollen collected) and (iv) syrup collection. Our results show that pollen collection is similar regardless of chemical variation in pollen diet while syrup collection is variable. Micro-colonies fed on S. aucuparia and C. scoparius pollen produced larger larvae (i.e. better mates and winter survivors) and fed less on nectar compared to the other diets. Pollen from both of these species contains 24-methylenecholesterol and high concentrations of polypeptides/total amino acids. This pollen nutritional “theme” seems therefore to promote worker reproduction in B. terrestris micro-colonies and could be linked to high fitness for queenright colonies. As workers are able to selectively forage on pollen of high chemical quality, plants may be evolutionarily selected for their pollen content, which might attract and increase the degree of fidelity of generalist pollinators, such as bumblebees. [less ▲]

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See detailHow does the age of hoverfly females affect their reproduction?
Almohamad, Raki; Verheggen, François ULg; Francis, Frédéric ULg et al

Conference (2007)

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See detailHow does the age of hoverfly females affect their reproduction?
Almohamad, Raki; Verheggen, François ULg; Francis, Frédéric ULg et al

in Communications in Agricultural and Applied Biological Sciences (2007), 72(3),

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See detailHow does the efficacy of Protelos translate into patient benefits ?
Reginster, Jean-Yves ULg

in Osteoporosis International (2009, March), 20(Suppl.1), 178

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See detailHow does the organizational context influence the Competitive Intelligence process among Walloon SMEs?
Gretry, Anaïs ULg

Master's dissertation (2012)

In this increasingly turbulent, global and competitive context, it becomes critical for companies to create and sustain a competitive advantage. Competitive Intelligence (CI), defined as “the process by ... [more ▼]

In this increasingly turbulent, global and competitive context, it becomes critical for companies to create and sustain a competitive advantage. Competitive Intelligence (CI), defined as “the process by which organizations gather information on competitors and the competitive environment [...]” (Wright, Eid & Fleisher, 2009, p.942), can contribute to do so by enabling managers to be aware of and respond to changes in their competitive environment. The CI process includes four steps: (a) planning and focus, (b) data collection, (c) data analysis and (d) communication. First, this paper assesses the level of deployment of CI among Walloon SMEs. Second, it examines the influence of context variables on the CI process. A questionnaire was distributed to 423 Walloon SMEs’ executives, of whom 81 answered. SMEs’ executives were surveyed about their companies’ CI practices as well as their perception of their company’s formal structure, employee involvement and organizational awareness. We found that Walloon SMEs are not very active to conduct CI effectively. Indeed, while Walloon SMEs have recognized that, theoretically, CI is a necessary activity for maintaining a competitive advantage, in practice, most of them do not have yet a well-established CI process in their company. Then, we established the influence of the context in which CI takes place on the success of the CI process. Specifically, we supported that better formal structure, employee involvement and organizational awareness improve the CI process. Finally, we examined the impact of two extra potential antecedents, namely the innovation orientation and the company’s size. We found that innovation-oriented companies tend to exploit CI more than followers. The results lead to several recommendations for SMEs. First, managers should be aware that CI is critical for their company’s survival since the context in which they operate is increasingly competitive. Second, businesses, especially those that are innovation-oriented, should note that an improvement in their formal infrastructure, organizational awareness and employee involvement processes could significantly enhance their CI efficiency. [less ▲]

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See detailHow does the visuo-spatial deficit impact basic numerical processing in Williams syndrome? The question of domain specificity
Rousselle, Laurence ULg; noel, Marie-Pascale

Conference (2012)

It has been suggested that mathematics learning disabilities, including those of genetic origin, result from a basic impairment of quantitative representations. In Williams syndrome in particular, recent ... [more ▼]

It has been suggested that mathematics learning disabilities, including those of genetic origin, result from a basic impairment of quantitative representations. In Williams syndrome in particular, recent studies report a specific deficit in tasks requiring symbolic and non symbolic numerical magnitude processing (Krajcsi et al., 2009 ; O’Hearn & Landau, 2007; Paterson et al., 2006). However, to our knowledge, the integrity of non numerical quantitative processing has never been investigated. Moreover, in the visual modality, it is difficult to disentangle the influence of the massive visuo-spatial impairment, which is a main characteristic of the cognitive phenotype of Williams syndrome, from the numerical magnitude processing deficit. Therefore, numerical and non numerical acuity were assessed in a group of patients with Williams syndrome using tasks with different visuo-spatial processing requirements. To assess the processing of non numerical continuous quantities, participants were asked to compare the length of two sticks (spatial dimension) vs. the duration of two sounds (temporal dimension). Their ability to process non-symbolic numerical magnitudes was explored in tasks requiring the comparison of two arrays of elements (spatial arrangement) versus two sequences of dots flashed in a single location (no spatial processing). Finally, their access to symbolic number meaning was assessed through the numerical comparison of two Arabic numbers vs two Spoken verbal numerals. In each task, the ratio between the quantities was manipulated in order to measure the entire psychophysic curve and to measure the acuity of their numerical and non numerical magnitude representations in non-symbolic tasks. [less ▲]

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See detailHow does the visuo-spatial deficit impact basic numerical processing in Williams syndrome? The question of domain specificity.
Rousselle, Laurence ULg; Noel, Marie-Pascale

Poster (2014)

It has been suggested that mathematics learning disabilities, including those of genetic origin, result from a basic impairment of quantitative representations. In Williams syndrome (WS) in particular ... [more ▼]

It has been suggested that mathematics learning disabilities, including those of genetic origin, result from a basic impairment of quantitative representations. In Williams syndrome (WS) in particular, latest studies report a specific deficit in tasks requiring symbolic and non-symbolic numerical magnitude processing (Krajcsi et al., 2009 ; O’Hearn & Landau, 2007; Paterson et al., 2006). However, non-numerical quantitative processing has never been investigated. Moreover, as patients with WS were always tested in the visual modality, it remains unclear whether their deficit is specific to the processing of numerical magnitude or result from their basic visuo-spatial impairment, which is a main characteristic of the WS cognitive phenotype. Therefore, numerical and non-numerical acuity were assessed in a group of 20 patients with WS using quantitative comparison tasks with different visuo-spatial processing requirements. They were compared to 40 typically developing children, half of them matched on verbal mental age and the other half matched on nonverbal mental age. Participants were asked to compare: (1) the length of two sticks (spatial dimension) vs. the duration of two sounds (temporal dimension) to assess non numerical quantitative processing, (2) the numerosity of two visual arrays (spatial arrangement) versus two sequences of flashs (no spatial processing) to assess non-symbolic numerical processing, and (3) two Arabic numbers vs two Spoken verbal numerals to examine the access to symbolic number meaning. Compared to verbal matched participants, participants with WS are impaired in quantitative tasks requiring the processing of visuo-spatial dimension(s) (i.e. comparison of lengths or collections) but not in a visual task requiring processing numerosities with no spatial processing component (i.e. numerical comparison of sequences of flashs). They also present difficulties in accessing the meaning of numerical symbols whatever the format. Their performance corresponds to those of the non verbal typically developing children. [less ▲]

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See detailHow does the visuo-spatial deficit impact basic numerical processing in Williams syndrome? The question of domain specificity.
Rousselle, Laurence ULg; Noel, Marie-Pascale

Conference (2014)

It has been suggested that mathematics learning disabilities, including those of genetic origin, result from a basic impairment of quantitative representations. In Williams syndrome (WS) in particular ... [more ▼]

It has been suggested that mathematics learning disabilities, including those of genetic origin, result from a basic impairment of quantitative representations. In Williams syndrome (WS) in particular, latest studies report a specific deficit in tasks requiring symbolic and non-symbolic numerical magnitude processing (Krajcsi et al., 2009 ; O’Hearn & Landau, 2007; Paterson et al., 2006). However, non-numerical quantitative processing has never been investigated and contradictory evidence has been reported about their ability to subitize small collections(Ansari et al., 2007; O’Hearn et al., 2005, 2011). Moreover, as patients with WS were always tested in the visual modality, it remains unclear whether their deficit is specific to the processing of numerical magnitude or result from their basic visuo-spatial impairment, which is a main characteristic of the WS cognitive phenotype. Therefore, numerical and non-numerical acuity were assessed in a group of patients with WS using quantitative comparison tasks with different visuo-spatial processing requirements. Participants were asked to compare: (1) the length of two sticks (spatial dimension) vs. the duration of two sounds (temporal dimension) to assess non numerical quantitative processing, (2) the numerosity of two visual arrays (spatial arrangement) versus two sequences of flashs (no spatial processing) to assess non-symbolic numerical processing, and (3) two Arabic numbers vs two Spoken verbal numerals to examine the access to symbolic number meaning. They also had to enumerate sets of 1 to 7 dots shown for 250 ms to explore their subitizing abilities. Results indicate that participants with WS are impaired in quantitative tasks requiring the processing of visuo-spatial dimension(s) (i.e. comparison of lengths or collections) but not in a visual task requiring processing numerosities with no spatial processing component (i.e. numerical comparison of sequences of flashs). They also present difficulties in accessing the meaning of numerical symbols whatever the format and present smaller subitizing range. [less ▲]

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See detailHow does thymus infection by coxsackievirus contribute to the pathogenesis of type 1 diabetes?
Michaux, Hélène ULg; Martens, Henri ULg; Jaïdane, Hela et al

in Frontiers in Immunology (2015), 6(Article 338), 1-6

Through synthesis and presentation of neuroendocrine self-antigens by major histocom- patibility complex proteins, thymic epithelial cells (TECs) play a crucial role in programing central immune self ... [more ▼]

Through synthesis and presentation of neuroendocrine self-antigens by major histocom- patibility complex proteins, thymic epithelial cells (TECs) play a crucial role in programing central immune self-tolerance to neuroendocrine functions. Insulin-like growth factor- 2 (IGF-2) is the dominant gene/polypeptide of the insulin family that is expressed in TECs from different animal species and humans. Igf2 transcription is defective in the thymus of diabetes-prone bio-breeding rats, and tolerance to insulin is severely decreased in Igf2−/− mice. For more than 15 years now, our group is investigating the hypothesis that, besides a pancreotropic action, infection by coxsackievirus B4 (CV- B4) could implicate the thymus as well, and interfere with the intrathymic programing of central tolerance to the insulin family and secondarily to insulin-secreting islet β cells. In this perspective, we have demonstrated that a productive infection of the thymus occurs after oral CV-B4 inoculation of mice. Moreover, our most recent data have demonstrated that CV-B4 infection of a murine medullary (m) TEC line induces a significant decrease in Igf2 expression and IGF-2 production. In these conditions, Igf1 expression was much less affected by CV-B4 infection, while Ins2 transcription was not detected in this cell line. Through the inhibition of Igf2 expression in TECs, CV-B4 infection could lead to a breakdown of central immune tolerance to the insulin family and promote an autoimmune response against insulin-secreting islet β cells. Our major research objective now is to understand the molecular mechanisms by which CV-B4 infection of TECs leads to a major decrease in Igf2 expression in these cells. [less ▲]

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See detailHow Does Your Formulation of Lesion-Induced States of Diminished Consciousness Fit with AIM? Do You Suppose That Brain Stem Damage Affects Activation (A) and Modulation (M)?
Charland-Verville, Vanessa ULg; Laureys, Steven ULg

in J. Allan Hobson, Nicholas Tranquillo (Ed.) Dream Consciousness: A New Approach to the Brain and Its Mind (2014)

Allan Hobson’s AIM model (Hobson, 1998) is build according to three main dimensions. The first component, Activation, describes brain’s activation processes and is closely linked to the level of ... [more ▼]

Allan Hobson’s AIM model (Hobson, 1998) is build according to three main dimensions. The first component, Activation, describes brain’s activation processes and is closely linked to the level of consciousness. According to the model, the brain is highly active in wakefulness and REM sleep but will show much less activity during NREM sleep. The second component, Input/output gateway, controls the inhibition of external stimuli. When slowly falling asleep, the gateway shuts down and inhibits the external stimuli; the brain is no longer involved in processing external perceptions. Then the brain starts its oniric phase and the focus switches to internal inputs. Finally, the third dimension, Modulation, refers to the different ways of cognitive processing (executive functions), judgment, volition and memory. According to the model, those cognitive processes are lacking in REM sleep (i.e., the brain cannot keep a record of its conscious experience during dreaming as opposed to waking state) because of the changes between the aminergic system (norepinephrine and serotonin; dominant in waking but ineffective in REM sleep) and the cholinergic system (acetylcholine; unfettered in REM sleep). These three dimensions maintain a dynamic and reciprocal interaction over the sleep-wake cycle’s variations (wakefulness, NREM and REM sleep) and each of them can be expressed with lower or higher intensities depending on the level of consciousness. [less ▲]

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See detailHow dynamical clustering triggers Maxwell's demon in microgravity
Opsomer, Eric ULg; Noirhomme, Martial ULg; Vandewalle, Nicolas ULg et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2013), 88

In microgravity, the gathering of granular material can be achieved by a dynamical clustering whose existence depends on the geometry of the cell that contains the particles and the energy that is ... [more ▼]

In microgravity, the gathering of granular material can be achieved by a dynamical clustering whose existence depends on the geometry of the cell that contains the particles and the energy that is injected into the system. By compartmentalizing the cell in several subcells of smaller volume, local clustering is triggered and the so formed dense regions act as stable traps. In this paper, molecular dynamics simulations were performed in order to reproduce the phenomenon and to analyze the formation and the stability of such traps. Depending on the total number N of particles present in the whole system, several clustering modes are encountered and a corresponding bifurcation diagram is presented. Moreover, an iterative model based on the measured particle flux F as well as a theoretical model giving the asymptotical steady states are used to validate our results. The obtained results are promising and can provide ways to manipulate grains in microgravity. [less ▲]

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See detailHow education adapts to meet the requirements?
Billen, Roland ULg

Scientific conference (2015, September 17)

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See detailHow electroencephalography serves the anesthesiologist.
Marchant, Nicolas ULg; Sanders, Robert; Sleigh, Jamie et al

in Clinical EEG and neuroscience (2014), 45(1), 22-32

Major clinical endpoints of general anesthesia, such as the alteration of consciousness, are achieved through effects of anesthetic agents on the central nervous system, and, more precisely, on the brain ... [more ▼]

Major clinical endpoints of general anesthesia, such as the alteration of consciousness, are achieved through effects of anesthetic agents on the central nervous system, and, more precisely, on the brain. Historically, clinicians and researchers have always been interested in quantifying and characterizing those effects through recordings of surface brain electrical activity, namely electroencephalography (EEG). Over decades of research, the complex signal has been dissected to extract its core substance, with significant advances in the interpretation of the information it may contain. Methodological, engineering, statistical, mathematical, and computer progress now furnishes advanced tools that not only allow quantification of the effects of anesthesia, but also shed light on some aspects of anesthetic mechanisms. In this article, we will review how advanced EEG serves the anesthesiologist in that respect, but will not review other intraoperative utilities that have no direct relationship with consciousness, such as monitoring of brain and spinal cord integrity. We will start with a reminder of anesthestic effects on raw EEG and its time and frequency domain components, as well as a summary of the EEG analysis techniques of use for the anesthesiologist. This will introduce the description of the use of EEG to assess the depth of the hypnotic and anti-nociceptive components of anesthesia, and its clinical utility. The last part will describe the use of EEG for the understanding of mechanisms of anesthesia-induced alteration of consciousness. We will see how, eventually in association with transcranial magnetic stimulation, it allows exploring functional cerebral networks during anesthesia. We will also see how EEG recordings during anesthesia, and their sophisticated analysis, may help corroborate current theories of mental content generation. [less ▲]

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See detailHow ergodic is the Fragmentation of the Pyridine Cation ? A Maximum Entropy Ananlysis
Gridelet, E.; Locht, Robert ULg; Lorquet, Andrée ULg et al

in Anton, J.; Cederquist, H.; Larsson, M. (Eds.) et al 23rd International Conference on the Photonic, Electronic and Atomic Collisions: Book of Abstracts. (2003)

The experimental KER and the statistical distributions are compared by the Maximum Entropy Method. An Ergodicity Index F(E) is defined to measure the phase space sampling efficiency. This is applied to ... [more ▼]

The experimental KER and the statistical distributions are compared by the Maximum Entropy Method. An Ergodicity Index F(E) is defined to measure the phase space sampling efficiency. This is applied to the KERD of C4H4+ cation produced by the C5H5N+ -> HCN+C4H4+ fragmentation path. In this particular case the F(E) is found to decrease steadily with increasing internal energy. [less ▲]

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See detailHow ergodic is the fragmentation of the pyridine cation? A maximum entropy analysis
Gridelet, E.; Locht, Robert ULg; Lorquet, Andrée ULg et al

in International Journal of Mass Spectrometry (2003), 228(2-3), 389-402

The kinetic energy released to the C4H4+ and HCN fragments produced by the dissociation of the pyridine ion has been determined by a retarding field technique up to an internal energy of 4eV above the ... [more ▼]

The kinetic energy released to the C4H4+ and HCN fragments produced by the dissociation of the pyridine ion has been determined by a retarding field technique up to an internal energy of 4eV above the reaction threshold. This extends our previous study limited to the metastable domain [Int. J. Mass Spectrom. Ion Process. 185/186/187 (1999) 155]. Retarding potential curves resulting from dissociative photoionization using the He(I), Ne(I), and Ar(II) resonance lines have been analyzed by the maximum entropy method. The comparison between the experimentally measured curves and those calculated for the prior (i.e., most statistical) situation reveals the existence of dynamical constraints that prevent phase space from being fully explored. The "ergodicity index" F(E) that measures the efficiency of phase space sampling as a function of the internal energy E of the molecular ion is found to decrease steadily as a function of E and to level off at a value of about 50% when E greater than or equal to 2.5 eV At these high internal energies where phase space exploration no longer decreases, spontaneous intramolecular vibrational energy redistribution (i.e., resulting from the anharmonicity of the molecular vibrations) is thought to contribute to internal energy randomization to a limited extent only. When the lifetime is short, phase space exploration is believed to result instead from the relaxation of the electronic energy via a cascade of non-radiative transitions, which leads to a great diversity of initial conditions, and thus, contributes to statisticity. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailHow eye movements and expertise can explain memory of visual items of central or marginal interest
Blavier, Adelaïde ULg; Nyssen, Anne-Sophie ULg

in Journal of Vision (2009)

In complex scene, memory for central interest items is better than memory for marginal interest items and this difference remains stable independently of the scene presentation duration (Melcher, 2006 ... [more ▼]

In complex scene, memory for central interest items is better than memory for marginal interest items and this difference remains stable independently of the scene presentation duration (Melcher, 2006). However, without eye movement recording, it is not possible to know whether central interest items are better remembered because they are more fixated or because they are more meaningful. In order to answer this question, we analysed the memory of complex scenes (paintings) according to the eye movements and subjects’ expertise. 15 novice subjects and 15 art historians (experts) were asked to look at 6 paintings that were separately and randomly presented for 10 seconds. After each painting presentation, subjects were asked questions about painting knowledge (author’s name, painting’s name) in order to evaluate their painting knowledge and about pictorial details of 3 categories: details of central or marginal interest and background information. If the expert and novice groups significantly differed concerning the knowledge they had about all paintings, the accuracy of answers about the painting details did not differ between both groups. Moreover, we showed novice’s answers were more accurate when they looked longer at the asked detail and when this detail was watched early on in the presentation while in the expert group, the accuracy of the answer was not influenced by the duration and moment they watched the asked detail. These findings suggest experts have some wrong representations which are not influenced by eye movements contrary to novices whom memory accuracy is influenced by their eye movements. [less ▲]

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See detailHow far and how fast do bryophytes travel at the landscape scale?
Hutsemekers, Virginie ULg; Dopagne, Claude ULg; Vanderpoorten, Alain ULg

in Diversity & Distributions (2008), 14(3), 483-492

Dispersal ability is a factor of prime importance to explain biotic distributions. Yet, it is extremely difficult to measure directly. In this study, we take advantage of the natural experimental design ... [more ▼]

Dispersal ability is a factor of prime importance to explain biotic distributions. Yet, it is extremely difficult to measure directly. In this study, we take advantage of the natural experimental design of slag heap colonization in Belgium to document the timing and range of dispersal of bryophytes at the landscape scale. On the basis of a species atlas with a 4 × 4 km grid, the minimum distance separating species found on 52 slag heaps from potential source populations was determined. Minimum dispersal rates were inferred by coupling the information on minimum distance between slag heap and source populations with time since colonization. The number of species per slag heap is significantly correlated with time since colonization and area size. The frequency distribution of the longest dispersal events is highly skewed, with 44% of the species recruited within the nearest 6 km. In the remaining 56% of the species, recruitments from source populations located within a range of at least 6–86 km occurred within a period of less than 50 years. The majority of the species that are not recruited within the nearest vicinity of the slag heaps, including rare species at the regional scale, occur on slag heaps that have been colonized for 25–50 years. Most recently colonized slag heaps are indeed characterized by 'fugitive', weedy species, whereas slag heaps that have been colonized for > 50 years tend to accumulate perennial species with a 'stayer' life strategy. These observations suggest that rare species may display the dispersal ability to travel across the landscape, but are subsequently limited by their ability to establish a viable community because of more competitive neighbours. Rare species therefore tend to accumulate at intermediate colonization stages, which represent a trade-off between an increasing probability of colonization with time and a decreasing probability of establishment due to competition. [less ▲]

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See detailHow fertilizer and soil nitrogen are distributed into winter wheat plant
Boulelouah, Nadia; Destain, Jean-Pierre ULg; Bodson, Bernard ULg et al

(2007, September 16)

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See detailHow general pedagogical knowledge and teacher’s self-efficacy at the onset of teacher education depend on teaching experience and prior education ?
Vaudroz, Cynthia; Berger, Jean-Louis; Girardet, Céline et al

Conference (2014)

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