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Le jeu de la « balle assise » : un substitut au questionnaire sociométrique ?
No full textNous cherchons à savoir si le jeu de la "balle assise", en raison de sa structure d'ambivalence et d'instabilité, permet l'actualisation des relations socio-affectives des protagonistes. Deux groupes de 23 et 26 étudiants sont sollicités et nous comparons les résultats de questionnaires sociométriques avec les communications motrices observées au cours du jeu. Notre étude révèle une corrélation prononcée entre les relations socio-affectives et les relations fonctionnelles (p<.01). Les relations socio-affectives semblent être omniprésentes dans tous les choix décisionnels des protagonistes. Dans la mesure où nos résultats seraient généralisables, le jeu traditionnel de la " balle assise ", pourtant souvent jugé désuet, offrirait des ressources insoupçonnées. Sur le vif, il permettrait au pédagogue de saisir la personnalité des acteurs et les relations socio-affectives du groupe. Il pourrait ainsi se "substituer", dans une certaine mesure, au questionnaire sociométrique et deviendrait un outil d'intervention psycho-sociologique.nonouirechercheInternationa
Learning conditionally lexicographic preference relations
No full textWe consider the problem of learning a user's ordinal preferences on a multiattribute domain, assuming that her preferences are lexicographic. We introduce a general graphical representation called LP-trees which captures various natural classes of such preference relations, depending on whether the importance order between attributes and/or the local preferences on the domain of each attribute is conditional on the values of other attributes. For each class we determine the Vapnik-Chernovenkis dimension, the communication complexity of preference elicitation, and the complexity of identifying a model in the class consistent with a set of user-provided examples.nonouirechercheInternationa
Reducing the risk of VWAP orders execution - A new approach to modeling intra-day volume
No full textThis paper proposes a new dynamic approach to modelling intra-day trading volume based on factor models. It assumes that intra-day volume can be decomposed into two parts each predicted using separate time-series models. By enabling more accurate prediction of intra-day volume, this methodology allows for a significant reduction in the cost of executing Volume weighted Average Price orders.nonouirechercheInternationa
Collateral effects of a pension reform in France
No full textHow does the retirement age affect the physical and mental health of seniors? We identify this effect based on the 1993 reform of the French pension system, which was heterogeneously introduced among the population. With each cohort, the French government gradually increased the incentive to work using two tools: the contribution period required for entitlement to a full pension and the number of reference earning years taken to calculate pensions. We use a unique database on health and employment in France in 1999 and 2005, when the cohorts affected by the reform started to retire. A difference-in-differences approach, with the control group comprising public sector employees (not concerned by the 1993 reform), finds that the people more affected by the reform, and hence with a stronger incentive to work, were those posting less of an improvement and even a deterioration in their health between 1999 and 2005. Subsequently, taking the reform as a tool to filter out the potential influence of health on employment choices, we show that retirement improves physical and social health. The more physically impacted are the low-educated individuals.nonnonnonrechercheInternationa
Incorporating Shape Variability in Image Segmentation via Implicit Template Deformation
No full textImplicit template deformation is a model-based segmentation framework that was successfully applied in several medical applications. In this paper, we propose a method to learn and use prior knowledge on shape variability in such framework. This shape prior is learnt via an original and dedicated process in which both an optimal template and principal modes of variations are estimated from a collection of shapes. This learning strategy requires neither a pre-alignment of the training shapes nor one-to-one correspondences between shape sample points. We then generalize the implicit template deformation formulation to automatically select the most plausible deformation as a shape prior. This novel framework maintains the two main properties of implicit template deformation: topology preservation and computational efficiency. Our approach can be applied to any organ with a possibly complex shape but fixed topology. We validate our method on myocardium segmentation from cardiac magnetic resonance short-axis images and demonstrate segmentation improvement over standard template deformation.nonouirechercheInternationa
La réforme de l’EU ETS dans le Paquet Energie Climat 2030 : Premières leçons à partir du modèle ZEPHYR
No full textnonnonouirechercheInternationa
Construction of management accountants’ occupational identity in a context where financial performance is in search of legitimacy: the case of the french armed forces
No full textCertain recent articles concerning the arrival of management accountants in the public sector announce the uncontested victory of a financial logic over professional logic which has until now governed many public sector organisations. However, the research works on « New Public Management » have focused on those who resist to this “managerialization” of the public sector to the detriment of other actors. Whilst we do not wish to close the door on the former, this paper proposes to examine the position of these upholders of a ‘managerial/financial’ logic a bit more closely. Who are they ? Where do they come from and in which direction are they headed? How do they experience their position in a context in which financial matters have yet to prove their importance ? Are they recognised by their peers ? If not, how do they create a space for themselves ? These questions remain unanswered and lead us to pose the following research question : how do management accountants construct their professional identity in a context in which financial performance still has to gain credibility ? This paper aims to answer this question through a qualitative study undertaken in conjunction with the French armed forces on the basis of 62 interviews and non-participatory observation sessions.nonouirechercheInternationa
Business as Usual in Financial Markets? The creation of incommensurables as institutional maintenance work
No full textThis paper aims to contribute to the literature on ‘institutional maintenance work’. Focusing on the institutional disruption resulting from a regulatory project of market rationalization, it enriches the description and analysis of the specific institutional maintenance work performed by powerful actors who engage in resistance against what they perceive as a threat to their discretion. Built on an in-depth qualitative study, our case concerns an attempt to change the form of over-the-counter markets as part of a recent financial reform. The paper contributes to the expanding literature on the maintenance of institutions by suggesting, in particular, that the creation of incommensurables should be added to the list of strategies available to powerful incumbents seeking to resist institutional change. Bridging the gap between the literatures on institutional maintenance and commensuration, it also demonstrates that specific institutional changes can usefully be understood as changes in commensuration systems. This innovatively suggests the existence of degrees of commensuration and calls for a finer-grained understanding of the institutional work required to maintain institutions in a context where the degree of commensuration experienced by a field or a market threatens to increase under coercive pressure.nonouirechercheInternationa
Parameterized approximability of maximizing the spread of influence in networks
No full textIn this paper, we consider the problem of maximizing the spread of influence through a social network. Given a graph with a threshold value thr(v)thr(v) attached to each vertex v, the spread of influence is modeled as follows: A vertex v becomes “active” (influenced) if at least thr(v)thr(v) of its neighbors are active. In the corresponding optimization problem the objective is then to find a fixed number k of vertices to activate such that the number of activated vertices at the end of the propagation process is maximum. We show that this problem is strongly inapproximable in time f(k)⋅nO(1)f(k)⋅nO(1), for some function f , even for very restrictive thresholds. In the case that the threshold of each vertex equals its degree, we prove that the problem is inapproximable in polynomial time and it becomes r(n)r(n)-approximable in time f(k)⋅nO(1)f(k)⋅nO(1), for some function f, for any strictly increasing function r. Moreover, we show that the decision version parameterized by k is W[1]W[1]-hard but becomes fixed-parameter tractable on bounded degree graphs.nonouirechercheInternationa
Adoption of IAS/IFRS, liquidity constraints, and credit rationing: the case of the European banking industry
No full textWith imperfections, theory suggests that banks dependent on external resources have greater difficulty refinancing their lending than banks with a lot of internal resources. Hence, there is an increased risk of credit rationing to these institutions. In this context, this empirical study tests the hypothesis that the adoption of the IAS/IFRS, deemed as of superior quality for economic decision-making, results in an increase in the amount of credit offered by banks with liquidity constraints. For a sample of European banks over the period of 2003 to 2008, we find that results are only partly consistent with this hypothesis. The results depend on the measure of the constraint, the bank size, and the enforcement regime. Our results show that the adoption (both voluntary and mandatory) of the IAS/IFRS lead to an increase in the credit supply only for small and constrained banks. These results are important with respect to the goal of banking stability and with the scarcity of credit observed in Europe since the financial crisis.nonouirechercheInternationa