Le discours comme image : énonciation et récit "mimétique" dans le "Timée-Critias" de Platon

Problématique: Pourquoi la mise en scène complexe du Timée-Critias avec ses contextes spatio-temporels emboîtés et ses narrations enchâssées? Quelle est la fonction (pragmatique et argumentative) du discours cosmogonique et anthropogonique de Timée intercalé entre le résumé du récit de l'Atlantide dans le prologue du Timée et la narration même de ce récit dans le Critias! Quel est le rapport entre les discours des deux protagonistes et celui de Socrate sur la cité idéale dans la République? Voilà les principales questions auxquelles cette thèse essaie de répondre. Grâce à une approche discursive et sémio-narrative, elle cherche à montrer la fonction pragmatique et la cohérence narrative et sémantique du double dialogue tout en tenant compte des visions du monde divergentes et même contradictoires des deux protagonistes. Elle essaie de comprendre comment les deux, l'un d'origine italique, l'autre Athénien, dans un contexte énonciatif donné et sur la base de leurs conceptions culturelles et «scientifiques» - sur l'homme et sur le monde - et de leurs idées «philosophiques» - sur l'être, le devenir et la connaissance - produisent des discours de signification différente mais traitant tous deux de la genèse, que ce soit celle du monde, de l'homme et des cités. Elle propose en outre de lire le Timée-Critias à la fois comme une continuation et une réécriture de la République: non seulement les trois dialogues ont le même sujet (la meilleure cité), mais ils se caractérisent par des parallèles dans la situation dramatique et énonciative et dans la manière dont se développe la narration. Plan: Les deux premiers chapitres examinent comment les performances discursives de Timée et de Critias se mettent en place dans le prologue, en prêtant une attention particulière aux aspects dramatiques et énonciatifs, mais aussi poétiques et narratifs (énonciateurs/narrateurs et leurs destinataires, fonction et genre des discours résumés et annoncés). Les troisième et quatrième chapitres, consacrés respectivement au long discours de Timée et à celui de Critias dans le dialogue homonyme, comparent d'abord les deux discours aux Hymnes homériques, à la Théogonie d'Hésiode et à la poésie généalogique afin de mieux saisir la fonction pragmatique et la composition de l'ensemble du Timée-Critias-, puis, à partir des principes ontologiques et épistémologiques explicités dans les proèmes, ils se proposent de dégager, en suivant de près la narration, les conceptions cosmologiques, anthropologiques et épistémologiques des deux protagonistes et de voir comment elles déterminent la production et l'énonciation de leurs discours. Enfin, le dernier chapitre reprend certains éléments essentiels étudiés précédemment en élargissant la perspective à la République et à son rapport intertextuel avec le Timée- Critias: il met en regard les contextes énonciatifs et dramatiques et la problématique des deux oeuvres (le rôle des personnages, la question de la réalisation de la meilleure cité), le discours de Timée et les livres six et sept (la khóra et Yagathón, le statut du discours vraisemblable et l'analogie de la ligne), ainsi que le Critias et les livres huit et dix (la dégénérescence de l'Atlantide et de la meilleure cité, la poésie «mimétique» de Critias et celle des poètes critiquée par Socrate).

Magnetic resonance imaging determinants of intraindividual variability in the elderly: combined analysis of grey and white matter.

Elderly individuals display a rapid age-related increase in intraindividual variability (IIV) of their performances. This phenomenon could reflect subtle changes in frontal lobe integrity. However, structural studies in this field are still missing. To address this issue, we computed an IIV index for a simple reaction time (RT) task and performed magnetic resonance imaging (MRI) including voxel based morphometry (VBM) and the tract based spatial statistics (TBSS) analysis of diffusion tensor imaging (DTI) in 61 adults aged from 22 to 88 years. The age-related IIV increase was associated with decreased fractional anisotropy (FA) as well as increased radial (RD) and mean (MD) diffusion in the main white matter (WM) fiber tracts. In contrast, axial diffusion (AD) and grey matter (GM) densities did not show any significant correlation with IIV. In multivariate models, only FA has an age-independent effect on IIV. These results revealed that WM but not GM changes partly mediated the age-related increase of IIV. They also revealed that the association between WM and IIV could not be only attributed to the damage of frontal lobe circuits but concerned the majority of interhemispheric and intrahemispheric corticocortical connections.

Fonaments i actuacions de lideratge sistèmic d'un equip de bàsquet professional i futures aplicacions

El treball de recerca “Fonaments i actuacions de lideratge sistèmic d’un equip de bàsquet professional i futures aplicacions” fa l’anàlisi d’una experiència real vinculada al món de l’esport professional. Es pretén donar a conèixer com l’estructuració del coneixement de l’entrenador pot afavorir el bon funcionament de l’equip. L’estructuració ens genera criteri i coherència a l’hora de prendre decisions.Es reconeix a l’entrenador com una persona treballadora, apassionada per la seva feina i en constant creixement individual. Valors com la humilitat, l’entusiasme, el compromís, la generositat i l’autoexigència es converteixen en adjectius fonamentals del nostre entrenador.L’estudi en l’autoconeixement en conceptes com lideratge, nivells neurològics, talent i motivació esdevenen el pal de paller en la construcció de l’equip. Un equip amb identitat pròpia, on el benefici pel bé comú (equip) està per sobre de tot, cooperatiu, compromès, i on la figura de l’entrenador intuïtiu amb coneixement influeix més per convenciment que per autoritat.El treball del dia a dia de l’entrenador i de l´equip es fonamenta en l’organització dels pilars de l’entrenador: flexibilitat, creixement de l’entrenador, equip, marges col·lectiu i individual són els motors del bon funcionament del col·lectiu. En el treball presentat, es destaca la importància de saber diferenciar, en el rendiment d’un equip, dues vessants: una més objectiva (tècnica, tàctica, estratègia i física) i l’altra on el factor humà és determinant. La investigació aprofundeix en aquest segon factor i el reconeix com a preferent. Per acabar es presenten tot un seguit d’actuacions utilitzades al llarg de la investigació amb la finalitat de generar, mantenir i millorar l’equip al mateix temps que es mostren diferents eines per tal d’optimitzar l’eficiència de les actuacions. La investigació pretén ser una experiència útil i enriquidora a l’hora d’estructurar el coneixement per tal de poder ser utilitzat en futures aplicacions.

Language and syntactic impairment following stroke in late bilingual aphasics.

PURPOSE: Bilingual aphasia generally affects both languages. However, the age of acquisition of the second language (L2) seems to play a role in the anatomo-functional correlation of the syntactical/grammatical processes, thus potentially influencing the L2 syntactic impairment following a stroke. The present study aims to analyze the influence of late age of acquisition of the L2 on syntactic impairment in bilingual aphasic patients. METHODS: Twelve late bilingual participants (speaking French as L2 and either English, German, Italian or Spanish as L1) with stroke-induced aphasia participated in the study. The MAST or BAT aphasia batteries were used to evaluate overall aphasia score. An auditory syntactic judgement task was developed and used to test participants syntactic performance. RESULTS: The overall aphasia scores did not differ between L1 and L2. In a multiple case analysis, only one patient had lower scores in L2. However, four patients presented significantly lower performances in syntactic processing in the late L2 than in their native language (L1). In these four patients the infarct was localized, either exclusively or at least partially, in the pre-rolandic region. CONCLUSION: This pilot study suggests that, in late bilingual aphasics, syntactic judgment abilities may be more severely impaired in L2, and that this syntactic deficit is most likely to occur following anterior lesions.

Disseny i optimització de membranes compòsit amb xarxes metal•loorgàniques per a nanofiltració i separacions de gasos

Projecte de recerca elaborat a partir d’una estada a la Katholieke Universiteit Leuven, Belgium, entre 2007 i 2009. Aquest projecte descriu la síntesi i aplicació de nous tipus de membranes compòsit basades en xarxes metal•loorgàniques (MOFs). Aquestes es van seleccionar tenint en compte les seves propietats estructurals per tal de discriminar les espècies a separar en funció de la seva mida molecular. Les membranes obtingudes s'han aplicat satisfactòriament tant en separacions líquides, concretament en nanofiltració resistent a dissolvents (SRNF), i en separació de parells de gasos com CO2/CH4, CO2/N2 i H2/CO2. Els resultats obtinguts posen de manifest l'obtenció de membranes sense defectes i amb rendiments prometedors, en la majoria dels casos, amb permeabilitats i selectivitats superiors a membranes purament polimèriques. Tanmateix s'ha desenvolupat un nou equipament d'alt rendiment (HT) per a separacions de gasos que inclou un mòdul que permet realitzar 16 experiments simultàniament. Els resultats obtinguts amb el nou equip són comparables amb els obtinguts amb mòduls convencionals, i alhora presenten una millor reproduïbilitat. Finalment, s'ha establert un nou mètode per a obtenir membranes per a SRNF, que han estat aplicades en processos de separació de catalitzadors homogenis en dissolvents polars apròtics i s'han caracteritzat emprant la tècnica d'espectroscòpia d'annihilació de positrons, que ha permès establir per primer cop una relació entre les propietats estructurals de les membranes a nivell molecular i el seu rendiment en les aplicacions anteriors.

Assessment of adult formulas for glomerular filtration rate estimation in children.

BACKGROUND: Estimated glomerular filtration rate (eGFR) is an important diagnostic instrument in clinical practice. The National Kidney Foundation-Kidney Disease Quality Initiative (NKF-KDOQI) guidelines do not recommend using formulas developed for adults to estimate GFR in children; however, studies confirming these recommendations are scarce. The aim of our study was to evaluate the accuracy of the new Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula, the Modification of Diet in Renal Disease (MDRD) formula, and the Cockcroft-Gault formula in children with various stages of chronic kidney disease (CKD). METHODS: A total of 550 inulin clearance (iGFR) measurements for 391 children were analyzed. The cohort was divided into three groups: group 1, with iGFR >90 ml/min/1.73 m(2); group 2, with iGFR between 60 and 90 ml/min/1.73 m(2); group 3, with iGFR of <60 ml/min/1.73 m(2). RESULTS: All formulas overestimate iGFR with a significant bias (p < 0.001), present poor accuracies, and have poor Spearman correlations. For an accuracy of 10 %, only 11, 6, and 27 % of the eGFRs are accurate when using the MDRD, CKD-EPI, and Cockcroft-Gault formulas, respectively. For an accuracy of 30 %, these formulas do not reach the NKF-KDOQI guidelines for validation, with only 25, 20, and 70 % of the eGFRs, respectively, being accurate. CONCLUSIONS: Based on our results, the performances of all of these formulas are unreliable for eGFR in children across all CKD stages and cannot therefore be applied in the pediatric population group.

Active Learning of Very-High Resolution Optical Imagery with SVM: Entropy vs Margin Sampling

An active learning method is proposed for the semi-automatic selection of training sets in remote sensing image classification. The method adds iteratively to the current training set the unlabeled pixels for which the prediction of an ensemble of classifiers based on bagged training sets show maximum entropy. This way, the algorithm selects the pixels that are the most uncertain and that will improve the model if added in the training set. The user is asked to label such pixels at each iteration. Experiments using support vector machines (SVM) on an 8 classes QuickBird image show the excellent performances of the methods, that equals accuracies of both a model trained with ten times more pixels and a model whose training set has been built using a state-of-the-art SVM specific active learning method

Imaging Properties of MS Lesions Correlate with Attention Deficits in Early Multiple Sclerosis

Introduction: Cognitive impairment affects 40-65% of multiple sclerosis (MS) patients, often since early stages of the disease (relapsing remitting MS, RRMS). Frequently affected functions are memory, attention or executive abilities but the most sensitive measure of cognitive deficits in early MS is the information processing speed (Amato, 2008). MRI has been extensively exploited to investigate the substrate of cognitive dysfunction in MS but the underlying physiopathological mechanisms remain unclear. White matter lesion load, whole-brain atrophy and cortical lesions' number play a role but correlations are in some cases modest (Rovaris, 2006; Calabrese, 2009). In this study, we aimed at characterizing and correlating the T1 relaxation times of cortical and sub-cortical lesions with cognitive deficits detected by neuropsychological tests in a group of very early RR MS patients. Methods: Ten female patients with very early RRMS (age: 31.6 ±4.7y; disease duration: 3.8 ±1.9y; EDSS disability score: 1.8 ±0.4) and 10 age- and gender-matched healthy volunteers (mean age: 31.2 ±5.8y) were included in the study. All participants underwent the following neuropsychological tests: Rao's Brief Repeatable Battery of Neuropsychological tests (BRB-N), Stockings of Cambridge, Trail Making Test (TMT, part A and B), Boston Naming Test, Hooper Visual Organization Test and copy of the Rey-Osterrieth Complex Figure. Within 2 weeks from neuropsychological assessment, participants underwent brain MRI at 3T (Magnetom Trio a Tim System, Siemens, Germany) using a 32-channel head coil. The imaging protocol included 3D sequences with 1x1x1.2 mm3 resolution and 256x256x160 matrix, except for axial 2D-FLAIR: -DIR (T2-weighted, suppressing both WM and CSF; Pouwels, 2006) -MPRAGE (T1-weighted; Mugler, 1991) -MP2RAGE (T1-weighted with T1 maps; Marques, 2010) -FLAIR SPACE (only for patient 4-10, T2-weighted; Mugler, 2001) -2D Axial FLAIR (0.9x0.9x2.5 mm3, 256x256x44 matrix). Lesions were identified by one experienced neurologist and radiologist using all contrasts, manually contoured and assigned to regional locations (cortical or sub-cortical). Lesion number, volume and T1 relaxation time were calculated for lesions in each contrast and in a merged mask representing the union of the lesions from all contrasts. T1 relaxation times of lesions were normalized with the mean T1 value in corresponding control regions of the healthy subjects. Statistical analysis was performed using GraphPad InStat software. Cognitive scores were compared between patients and controls with paired t-tests; p values ≤ 0.05 were considered significant. Spearmann correlation tests were performed between the cognitive tests, which differed significantly between patients and controls, and lesions' i) number ii) volume iii) T1 relaxation time iv) disease duration and v) years of study. Results: Cortical and sub-cortical lesions count, T1 values and volume are reported in Table 1 (A and B). All early RRMS patients showed cortical lesions (CLs) and the majority consisted of CLs type I (lesions with a cortical component extending to the sub-cortical tissue). The rest of cortical lesions were characterized as type II (intra-cortical lesions). No type III/IV lesions (large sub-pial lesions) were detected. RRMS patients were slightly less educated (13.5±2.5y vs. 16.3±1.8y of study, p=0.02) than the controls. Signs of cortical dysfunction (i.e. impaired learning, language, visuo-spatial skills or gnosis) were rare in all patients. However, patients showed on average lower scores on measures of visual attention and information processing speed (TMT-part A: p=0.01; TMT-part B: p=0.006; PASAT-included in the BRB-N: p=0.04). The T1 relaxation values of CLs type I negatively correlated with the TMT-part A score (r=0.78, p<0.01). The correlations of TMT-part B score and PASAT score with T1 relaxation time of lesions as well and the correlation between TMT-part A, TMT-part B and PASAT score with lesions' i) number ii) volume iii) disease duration and iv) years of study did not reach significance. In order to preclude possible influences from partial volume effects on the T1 values, the correlation between lesion volume and T1 value of CLs type I was calculated; no correlation was found, suggesting that partial volume effects did not affect the statistics. Conclusions: The present pilot study reports for the first time the presence and the T1 characteristics at 3 T of cortical lesions in very early RRMS (< 6 y disease duration). It also shows that CLS type I represents the most frequent cortical lesion type in this cohort of RRMS patients. In addition, it reveals a negative correlation between the attentional test TMT-part A and the T1 properties of cortical lesions type I. In other words, lower attention deficits are concomitant with longer T1-relaxation time in cortical lesions. In respect to this last finding, it could be speculated that long relaxation time correspond to a certain degree of tissue loss that is enough to stimulate compensatory mechanisms. This hypothesis is in line with previous fMRI studies showing functional compensatory mechanisms to help maintaining normal or sub-normal attention performances in RR MS patients (Penner, 2003).

Evaluation of two immunoassays for the measurement of human chorionic gonadotropin in urine for anti-doping purposes.

Background: Urinary human chorionic gonadotropin (hCG) concentration is routinely measured in all anti-doping laboratories to exclude the misuse of recombinant or urinary hCG preparations. In this study, extended validation of two commercial immunoassays for hCG measurements in urine was performed. Both tests were initially designed for hCG determination in human serum/plasma. Methods: Access (R) and Elecsys (R) 1010 are two automated immunoanalysers for central laboratories. The limits of detection and quantification, as well as intra-laboratory and inter-technique correlation, precision, and accuracy, were determined. Stability studies of hCG in urine following freezing and thawing cycles (n = 3) as well as storage conditions at room temperature, 4 degrees C and 20 degrees C, were performed. Results: Statistical evaluation of hCG concentrations in male urine samples (n = 2429) measured with the Elecsys (R) 1010 system enabled us to draw a skewed frequency histogram and establish a far outside value equal to 2.3 IU/L. This decision limit corresponds to the concentration at which a sportsman will be considered positive for hCG. Intra-assay precision for the Access (R) analyser was less than 4.0 A, whereas the inter-assay precision was closer to 4.5 % (concentrations of the official external controls contained between 5.5 and 195.0 IU/L). Intra and inter-assay precision for the Elecsys (R) 1010 analyser was slightly better. A good inter-technique correlation was obtained when measuring various urine samples (male and female). No urinary hCG loss was observed after two freeze/thaw cycles. On the other hand, time and inappropriate storage conditions, such as temperatures above 10 degrees C for more than 5 days, can deteriorate urinary hCG. Conclusions: Both analysers showed acceptable performances and are suitable for screening urine for anti-doping analyses. Each laboratory should validate and establish its own reference values because hCG concentrations measured in urine can be different from one immunoassay to another. The time delay between urine collection and analysis should be reduced as much as possible, and urine samples should be transported in optimal conditions to avoid a loss of hCG immunoreactivity.

Ultra-high pressure liquid chromatography-mass spectrometry for plant metabolomics: a systematic comparison of high-resolution quadrupole-time-of-flight and single stage Orbitrap mass spectrometers.

The response of Arabidopsis to stress caused by mechanical wounding was chosen as a model to compare the performances of high resolution quadrupole-time-of-flight (Q-TOF) and single stage Orbitrap (Exactive Plus) mass spectrometers in untargeted metabolomics. Both instruments were coupled to ultra-high pressure liquid chromatography (UHPLC) systems set under identical conditions. The experiment was divided in two steps: the first analyses involved sixteen unwounded plants, half of which were spiked with pure standards that are not present in Arabidopsis. The second analyses compared the metabolomes of mechanically wounded plants to unwounded plants. Data from both systems were extracted using the same feature detection software and submitted to unsupervised and supervised multivariate analysis methods. Both mass spectrometers were compared in terms of number and identity of detected features, capacity to discriminate between samples, repeatability and sensitivity. Although analytical variability was lower for the UHPLC-Q-TOF, generally the results for the two detectors were quite similar, both of them proving to be highly efficient at detecting even subtle differences between plant groups. Overall, sensitivity was found to be comparable, although the Exactive Plus Orbitrap provided slightly lower detection limits for specific compounds. Finally, to evaluate the potential of the two mass spectrometers for the identification of unknown markers, mass and spectral accuracies were calculated on selected identified compounds. While both instruments showed excellent mass accuracy (<2.5ppm for all measured compounds), better spectral accuracy was recorded on the Q-TOF. Taken together, our results demonstrate that comparable performances can be obtained at acquisition frequencies compatible with UHPLC on Q-TOF and Exactive Plus MS, which may thus be equivalently used for plant metabolomics.

A multi-perspective approach to performance anxiety in music students

AbstractPerforming publicly has become increasingly important in a variety of professions. This condition is associated with performance anxiety in almost all performers. Whereas some performers successfully cope with this anxiety, for others it represents a major problem and even threatens their career. Musicians and especially music students were shown to be particularly affected by performance anxiety.Therefore, the goal of this PhD thesis was to gain a better understanding of performance anxiety in university music students. More precisely, the first part of this thesis aimed at increasing knowledge on the occurrence, the experience, and the management of performance anxiety (Article 1). The second part aimed at investigating the hypothesis that there is an underlying hyperventilation problem in musicians with a high level of anxiety before a performance. This hypothesis was addressed in two ways: firstly, by investigating the association between the negative affective dimension of music performance anxiety (MPA) and self-perceived physiological symptoms that are known to co-occur with hyperventilation (Article 2) and secondly, by analyzing this association on the physiological level before a private (audience-free) and a public performance (Article 3). Article 4 places some key variables of Article 3 in a larger context by jointly analyzing the phases before, during, and after performing.The main results of the self-report data show (a) that stage fright is experienced as a problem by one-third of the surveyed students, (b) that the students express a considerable need for more help to better cope with it, and (c) that there is a positive association between negative feelings of MPA and the self-reported hyperventilation complaints before performing. This latter finding was confirmed on the physiological level in a tendency of particularly high performance-anxious musicians to hyperventilate. Furthermore, the psycho-physiological activation increased from a private to a public performance, and was higher during the performances than before or after them. The physiological activation was mainly independent of the MPA score. Finally, there was a low response coherence between the actual physiological activation and the self-reports on the instantaneous anxiety, tension, and perceived physiological activation.Given the high proportion of music students who consider stage fright as a problem and given the need for more help to better cope with it, a better understanding of this phenomenon and its inclusion in the educational process is fundamental to prevent future occupational problems. On the physiological level, breathing exercises might be a good means to decrease - but also to increase - the arousal associated with a public performance in order to meet an optimal level of arousal needed for a good performance.

L'état des communes dans le canton de Vaud

Les communes vaudoises ne sont pas épargnées par les profonds changements que subissent les communes suisses depuis les années 90. Le nombre de réformes a augmenté de manière considérable et les causes de ces changements sont multiples: une complexité croissante des prestations à fournir, la recherche de formes organisationnelles plus efficaces, la difficulté de trouver des personnes s'engageant en politique. Vu ces défis, la fusion de communes a été fréquente dans certains cantons. Quant à lui, le canton de Vaud reste un canton avec un grand nombre de communes de petite taille. C'est entre autre sous l'aspect de la différente taille des communes que cette étude aborde des thèmes concernant les communes vaudoises, comme par exemple les limites de performances des communes, la politique et l'administration communale, les relations et la répartition des tâches entre les communes et le canton, la collaboration intercommunale où encore les fusions de communes. L'analyse se base sur les données de l'enquête auprès des secrétaires communaux suisses qui a lieu régulièrement depuis 1988.

Diagnostic accuracy of free and total metanephrines in plasma and fractionated metanephrines in urine of patients with pheochromocytoma.

BACKGROUND: Plasma free and urinary metanephrines are recognized biomarkers for the assessment of pheochromocytoma. Plasma total metanephrines with a long half-life may represent another useful biomarker. OBJECTIVE: The aim of this study is to evaluate the diagnostic performances of plasma total metanephrines alone or combined with free metanephrines and fractionated 24-h urinary metanephrines. METHODS: A retrospective, case-control diagnostic test study was conducted between 1999 and 2007 in two university hospitals in Switzerland and two institutions in France. The patients included 46 cases with histologically proven pheochromocytoma, and 181 controls suspected of tumor with negative investigations and 3-year follow-up. None had renal dysfunction. Sensitivity and specificity were compared after expressing each measurement result as a ratio over its upper reference limit, adding the ratios of normetanephrine and metanephrine, and defining cut-off values of 1 or 2 for this sum. RESULTS: Applying a cut-off value of 1, plasma free and total metanephrines and urinary fractionated metanephrines had similar sensitivities of 96% (95% confidence interval, 86-99%), 95% (85-99%), and 95% (84-99%) along with similar specificities of 89% (83-94%), 91% (84-95%), and 86% (80-91%). A cut-off of 2 for the sum of ratios over reference limit improves the specificity, and it can be used for a confirmation test based on another biomarker taken among the three biomarkers. CONCLUSION: All three metanephrine-based tests perform equivalently for diagnosing pheochromocytoma in the absence of renal insufficiency, and can be conveniently associated two by two for confirming/excluding tumor.

Policy Diffusion: An Agent-Based Approach

Methods like Event History Analysis can show the existence of diffusion and part of its nature, but do not study the process itself. Nowadays, thanks to the increasing performance of computers, processes can be studied using computational modeling. This thesis presents an agent-based model of policy diffusion mainly inspired from the model developed by Braun and Gilardi (2006). I first start by developing a theoretical framework of policy diffusion that presents the main internal drivers of policy diffusion - such as the preference for the policy, the effectiveness of the policy, the institutional constraints, and the ideology - and its main mechanisms, namely learning, competition, emulation, and coercion. Therefore diffusion, expressed by these interdependencies, is a complex process that needs to be studied with computational agent-based modeling. In a second step, computational agent-based modeling is defined along with its most significant concepts: complexity and emergence. Using computational agent-based modeling implies the development of an algorithm and its programming. When this latter has been developed, we let the different agents interact. Consequently, a phenomenon of diffusion, derived from learning, emerges, meaning that the choice made by an agent is conditional to that made by its neighbors. As a result, learning follows an inverted S-curve, which leads to partial convergence - global divergence and local convergence - that triggers the emergence of political clusters; i.e. the creation of regions with the same policy. Furthermore, the average effectiveness in this computational world tends to follow a J-shaped curve, meaning that not only time is needed for a policy to deploy its effects, but that it also takes time for a country to find the best-suited policy. To conclude, diffusion is an emergent phenomenon from complex interactions and its outcomes as ensued from my model are in line with the theoretical expectations and the empirical evidence.Les méthodes d'analyse de biographie (event history analysis) permettent de mettre en évidence l'existence de phénomènes de diffusion et de les décrire, mais ne permettent pas d'en étudier le processus. Les simulations informatiques, grâce aux performances croissantes des ordinateurs, rendent possible l'étude des processus en tant que tels. Cette thèse, basée sur le modèle théorique développé par Braun et Gilardi (2006), présente une simulation centrée sur les agents des phénomènes de diffusion des politiques. Le point de départ de ce travail met en lumière, au niveau théorique, les principaux facteurs de changement internes à un pays : la préférence pour une politique donnée, l'efficacité de cette dernière, les contraintes institutionnelles, l'idéologie, et les principaux mécanismes de diffusion que sont l'apprentissage, la compétition, l'émulation et la coercition. La diffusion, définie par l'interdépendance des différents acteurs, est un système complexe dont l'étude est rendue possible par les simulations centrées sur les agents. Au niveau méthodologique, nous présenterons également les principaux concepts sous-jacents aux simulations, notamment la complexité et l'émergence. De plus, l'utilisation de simulations informatiques implique le développement d'un algorithme et sa programmation. Cette dernière réalisée, les agents peuvent interagir, avec comme résultat l'émergence d'un phénomène de diffusion, dérivé de l'apprentissage, où le choix d'un agent dépend en grande partie de ceux faits par ses voisins. De plus, ce phénomène suit une courbe en S caractéristique, poussant à la création de régions politiquement identiques, mais divergentes au niveau globale. Enfin, l'efficacité moyenne, dans ce monde simulé, suit une courbe en J, ce qui signifie qu'il faut du temps, non seulement pour que la politique montre ses effets, mais également pour qu'un pays introduise la politique la plus efficace. En conclusion, la diffusion est un phénomène émergent résultant d'interactions complexes dont les résultats du processus tel que développé dans ce modèle correspondent tant aux attentes théoriques qu'aux résultats pratiques.

Activité professionnelle des utilisateurs d'implant cochléaire [Professional occupation after cochlear implantation]

This study verifies whether cochlear implants helps deaf adults to maintain or develop their professional occupations. Sixty-seven patients received a questionnaire concerning their professional activities before and after implantation. At the time of implantation 34 were professionally active. After the implantation 29 remained active, 4 of them reporting positive developments in their careers. Five patients became inactive. The previously inactive patients remained inactive. There was no difference in auditory performances between professionally active or inactive patients. Cochlear implants enable most implanted adults to maintain and even progress in their professions. However, deafness still represents an obstacle to social integration as inactive patients who searched for a job were rejected after the job interviews.