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Interactions coopératives, processus développementaux et comportements psychopathologiques agis: une approche dynamique
No full textThis work deals with the different manifestations of cooperativity in pedopsychiatry in connection with severe disorders in adolescence such as suicide attempts and runaways, and developmental processes in early childhood. Our principal hypothesis is that cooperativity, nonlinearity and the resulting feedback loops underlie the appearance of suicidal peaks, the transitions between different mental states in a population of susceptible, suicidal and runaway individuals, or finally the selfish to egalitarian transition in young children. The principal methodology put forward is mathematical modeling, which allows one to identify the principal mechanisms present, to assess the role of the environmental constraints and to make predictions. This provides in turn insights on possible prevention, managemant and therapy strategies. Using this approach we have shown that suicide contagion can take an explosive form that is dramatically accelerated by the presence of virtual contacts as it happens, in particular, in communication via the Internet. Different scenarios have been explored, inspired by typical cases encountered in clinical practice when taking in charge adolescents in crisis. Regarding the population of susceptible, suicidal and runaways, a model has been developed whose analysis shows that depending on the parameter values and the size of the initial population the system can evolve toward states where the populations of the suicidal and of the runaways are negligible or, on the contrary, reach appreciable values. Finally, we have shown that in absence of interactions between individuals the selfish to egalitarian transition in children occurs gradually, whereas in the presence of cooperativity the transition is more abrupt. Our results suggest that when taking in charge adolescents in a state of risk contagion and transition between mental states must be recognized as additional iatrogenic risks, which can be minimized by privileging small non-mixed groups.Doctorat en Sciences médicales (Médecine)info:eu-repo/semantics/nonPublishe
Association of Neonatal Thyroid Stimulating Hormone Concentration with Intellectual, Psychomotor and Psychosocial Development of Preschool Children
No full textIodine is necessary for thyroid hormones synthesis which in turn are essential for brain development during fetal and early postnatal life. In these critical periods, severe iodine deficiency can induce irreversible brain damage in the fetus and the infant, resulting in retarded cognitive and/or psychomotor development. Despite the introduction of salt iodization programs such as national measures to control iodine deficiency, some European countries, including Belgium, are still affected by Mild Iodine Deficiency (MID) and MID during pregnancy may affect neurodevelopment of the offspring. Elevated thyroid stimulating hormone (TSH) concentration (>5mU/l) at birth has been used as an indicator of iodine deficiency during late pregnancy and at the population level. This doctoral research aimed to investigate the association between neonatal TSH level, used as a surrogate marker of MID during late pregnancy, and cognitive, psychomotor and psychosocial development of preschool children. It was hypothesized that elevation of TSH at birth is associated with impaired intellectual and psychomotor development and with behavioral problems at 4-5 years. As the use of TSH as an indicator of iodine deficiency has been criticized, we have also set out to assess the potential factors influencing neonatal TSH level measured through neonatal screening using a representative sample of TSH values between 0 and 15 mIU/L. Additionally, we aimed to reevaluate the neonatal TSH cut-off (5mIU/L) used to monitor iodine status in the population. The objective was to evaluate the cut-off point from which we can observe the impairment of children’s neurodevelopment. We hypothesized that this is a good way to establish the best cut-off value for identifying iodine deficiency.The study included 315 Belgian preschool children with a TSH concentration between 0 and 15 mU/L at screening. For each sex and TSH-interval (0-1 mU/L, 1-2 mU/L, 2-3 mU/L, 3-4 mU/L, 4-5 mU/L, 5-6 mU/L, 6-7 mU/L, 7-8 mU/L, 8-9 mU/L, 9-15 mU/L) 19 newborns were randomly selected after excluding infants with congenital hypothyroidism, low birth weight and premature infants. Neonatal TSH was measured in dried blood spots collected by heel stick 3 to 5 days after birth using the Autodelphia method. Cognitive abilities and psychomotor development were assessed using respectively the Wechsler Preschool and Primary Scale of Intelligence-III and the Charlop-Atwell scale of motor coordination. Psychosocial development was measured using the Child Behavior Check List for ages 1½-5 years. In addition, the mothers completed a self-administered questionnaire in order to account for confounding factors. No association between neonatal TSH within the range of 0 to 15 mIU/L - a surrogate marker for mild iodine deficiency during pregnancy and neurocognitive development was present in Belgian preschool children. The current level of iodine deficiency in Belgium is probably not severe enough to affect the neurodevelopment of children. In this study, we were able to identify several maternal and pregnancy related determinants of neonatal TSH levels. Higher TSH levels were associated with a lifetime (up to child birth) smoking behavior in the mother, a lower weight gain during pregnancy, a longer pregnancy duration. Higher TSH levels were found in spring and winter compared to summer and autumn. It is not advised to use elevated neonatal TSH levels at birth as an indicator of iodine deficiency during late pregnancy without taking potential covariates into account. Given the fact that no association was found between TSH and developmental scores in the children, we cannot evaluate the cut-off point from which we can observe the impairment of children’s neurodevelopment.Doctorat en Sciences psychologiques et de l'éducationinfo:eu-repo/semantics/nonPublishe
Symplectic Structure of Constrained Systems: Gribov Ambiguity and Classical Duals for 3D Gravity
No full textThe present thesis is divided into two parts. Part I is devoted to the study of Gribov ambiguity in gauge systems and its relation with the appearance of degeneracies in the symplectic structure of the corresponding reduced phase space after gauge fixation. Part II is concerned with classical dual field theories for three-dimensional Einstein gravity and the symplectic structure on coadjoint orbits of the corresponding asymptotic symmetry group.In Part I, the Gribov problem is studied in the context of finite temperature QCD and the structure of the gluon propagator is analyzed. The standard confined scenario is found for low temperatures, while for high enough temperatures deconfinement takes place and a free gluon propagator is obtained. Subsequently, the relation between Gribov ambiguity and degeneracies in the symplectic structure of gauge systems is analyzed. It is shown that, in finite-dimensional systems, the presence of Gribov ambiguities in regular constrained systems always leads to a degenerate symplectic form upon Dirac reduction. The implications for the Gribov-Zwanziger approach to QCD and the symplectic structure of the theory are discussed. In Part II, geometrical actions for three-dimensional Einstein gravity are constructed by studying the symplectic structure on coadjoint orbits of the asymptotic symmetry group. The geometrical action coming from the Kirillov-Kostant symplectic form on coadjoint orbits is analyzed thought Dirac's algorithm for constrained systems. By studying the case of centrally extended groups and semi-direct products, the symplectic structure on coadjoint orbits of the Virasoro and the BMS3 group are analyzed. This allows one to associate separate geometric actions to each coadjoint orbit of the solution space, leading to two-dimensional dual fiel theories for asymptotically AdS and asymptotically flat three-dimensional gravity respectively.Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe
Synthèse, caractérisation et modélisation de nanostructures photoniques bio-inspirées
No full textNatural photonic crystals (PCs) are responsible for the iridescent colors found in some species of butterflies and beetles. Besides the bright colors, some of these PCs display unexpected properties, such as optical sensitivity to gases (Morpho), polarization effects (Papilio blumei) and anti reflective coating (ARC, Greta oto). In this work, we have studied these properties in details and we have micro-fabricated artificial bio- inspired photonic crystals exhibiting the same behaviours. Three different kinds of applications were then highlighted: anti-counterfeiting surface, gaz sensor and ARC for solar cell. The technological potential of each application has been discussed.(FSA - Sciences de l'ingénieur) -- UCL, 2015Accès interdit11/12/2015(FSA - Sciences de l'ingénieur) -- UCL, 2015Anglai
(Sur)vivre et naviguer entre deux eaux :histoires de ruse, de résistance et de "par-être" chez les femmes téhéranaises
No full textThis dissertation is based on the observation of Tehrani women’s daily practices over a period of nine years, from 2006 to 2015. It also includes life narratives of women from two generations, pre- and post-revolutionary. This work explores women’s hopes and the obstacles that they encounter through different cycles of their lives (university, marriage, marital life and potential emigration). The study emphasizes the strategies that women use to survive within an environment that is socially and structurally dominated by men. More specifically, it shows the ways in which women use the body to survive or to climb in the social ladder. Part of this work also consists in deconstructing prejudices about the Tehrani context and revealing the local meanings of different institutions such as the university, marriage, and the family.Cette thèse porte sur l’observation de pratiques quotidiennes de femmes téhéranaises menée sur une période de neuf années allant de 2006 à 2015 ainsi que sur des récits de vie qui s’étendent sur deux générations de femmes pré- et postrévolutionnaires. A travers ces données, ce travail explore les espoirs et les obstacles liés aux différents cycles d’existence de ces femmes que sont les études, le mariage, la vie de couple et le départ éventuel vers l’étranger. Des étapes qui, dans un univers socialement et structurellement dominé par les hommes, sont systématiquement marquées par des désillusions et des difficultés que les femmes surmontent en faisant preuve de ruse ou de résistance, et en mettant en place diverses formes de stratégies. Plus spécifiquement, cette étude met en évidence l’usage qui est fait du corps par ces femmes et les transformations qui y sont apportées comme ultime moyen de survie et/ou d’ascension sociale. Une partie de ce travail consiste également à déconstruire les nombreuses idées reçues que l’on se fait du contexte téhéranais et à décortiquer différentes institutions, telles que l’université, le mariage et la famille, pour en dégager le sens et le fonctionnement local. Enfin, les différents sens que prennent les projets migratoires, les départs réels et imaginaires qui sont omniprésents dans la vie de ces femmes, y sont systématiquement abordés et analysés.(POLS - Sciences politiques et sociales) -- UCL, 2015Accès interdit11/12/2015(POLS - Sciences politiques et sociales) -- UCL, 2015Françai
Circuitos migratorios, jerarquías espaciales y modernidad periférica :Cañar y Loja, 1960-1990
No full textDuring the second half of the XXth century, important patterns of internal and international migration emerged and strengthened in southern Ecuador, involving increasingly large segments of the population. At the same time, during those decades crucial transformations took place in the country, brought by changes in political and economic regimes. My thesis aims to understand how development projects have intervened in the emergence of migration circuits in the southern provinces of Cañar and Loja between the decades of 1960 and 1990. Migration circuits are defined as a complex dynamic of connections and circulation encompassing people, objects, and symbols, and linking spaces, with enduring effects for social groups and territories involved (Rivera Sánchez, 2012). This definition intends to go beyond a conceptualization of migration as unidirectional movements across places, and not exclusively focusing on migrants, but on the socio-spatial process that unfolds on the long-term, thus displacing the focus from migration to mobility. The research consists of a study of two cases with a historical approach and a methodological strategy focused in the spatial and temporal dimensions of migration circuits. Drawing on archival and secondary literature research, combined with in-depth interviews, I have analyzed how governmental projects on territory and population implemented in Cañar and Loja have configured these provinces as peripheral to the nation. Drawing on in-depth and biographical interviews conducted in several localities of the Cañar and Loja provinces, as well as in other cities of Ecuador and in the New York metropolitan area, I have mapped the heterogeneous migratory and circulatory trajectories of three generations of people from Cañar and Loja. I argue that these trajectories are a part of larger mobility circuits related to historically constructed socio-spatial hierarchies. Drawing on these same data, I also analyze tensions between development projects and mobility projects emerging from these peripheral provinces. My work evidences that large population movements that have taken place in these provinces are linked to a more ample social context in which mobility is central, as evidenced in the transit of goods and commodities, means of transport, and people from different social backgrounds; and linked to them, narratives, ideas, ideologies and symbols related to spatial hierarchies. I argue that these intense forms of movement arise in response to development projects and social, economic and political structures that construct hierarchical orders of spaces, society and the nation. I aim to show how the circulation of social remittances within those provinces is related to conflicting projects of modernity. I also aim to delve into the specific ways in which migration becomes a possible and desirable alternative for people in those localities, regardless of social background or socio-economic position. In other words, my goal is to understand how mobility has become a part of local subjectivities and how development regimes shape the vital experiences of subjects.Esta tesis se propone estudiar la formación histórica de circuitos migratorios desde las provincias periféricas de Cañar y Loja, en el sur del Ecuador, como un proceso socioespacial de larga duración. El estudio aborda varios ámbitos poco trabajados por los estudios de la migración en el Ecuador, entre ellos, la dimensión histórica de la migración ecuatoriana, los vínculos entre migración interna y migración internacional y otras formas regionales de movilidad y la relación de estas migraciones con procesos de transformación de los regímenes de desarrollo en las escalas regional, nacional y global. Para abordar estas problemáticas, se ha conducido un estudio de dos casos con una estrategia metodológica centrada en las dimensiones espaciales y temporales de los circuitos migratorios. La orientación metodológica del estudio se basa en una perspectiva de larga duración histórica, y se emplean dos herramientas principales, la entrevista biográfica y la antropología de las políticas. El estudio de los procesos históricos de emigración en el sur del Ecuador a través del concepto de circuitos migratorios permite realizar dos contribuciones principales al campo de estudios de la migración, tanto en el caso del Ecuador como más allá de éste, en la región andina y en el contexto de las migraciones latinoamericanas. Una primera contribución es el planteamiento de que las formas de movilidad que han tenido lugar en Cañar y Loja desde la segunda mitad del siglo XX están insertas en un contexto marcado por jerarquías socioespaciales, donde la circulación es parte de prácticas de larga duración y no se limita a la migración, sino que también implica flujos materiales, así como de narrativas, ideas y símbolos relacionados con órdenes espaciales en construcción. Segundo, propongo que estas intensas formas de circulación han surgido en respuesta a proyectos de nación y de desarrollo, así como a estructuras sociales, económicas y políticas que pretenden establecer órdenes jerárquicos sobre los espacios, la sociedad y la nación. Esto conduce al planteamiento de que son las subjetividades ligadas a configuraciones socioespaciales particulares, y no únicamente factores económicos, políticas de Estado o redes sociales, entendidos como ámbitos separados entre sí, lo que explica la emergencia y sostenimiento de los circuitos migratorios que se han configurado en Cañar y Loja en los últimos cincuenta años.(POLS - Sciences politiques et sociales) -- UCL, 2015Accès restreint20/11/2015(POLS - Sciences politiques et sociales) -- UCL, 2015Espagno
Loss of MLH1 expression promotes the acquisition of oncogenic JAK1 and JAK3 mutations that cooperatively increase resistance to JAK inhibitors
No full textMalignant transformation evolves as the outcome of 2 connected processes operating within a population of competing cells: on the one hand, the continuous accumulation of random mutations by individual cells at a rate dictated by the degree of genetic instability and, on the other hand, the simultaneous natural selection acting on the resultant phenotypes. Successive rounds of environmental pressures lead to the emergence of cells that acquired diverse advantageous hallmarks such as growth factor-independent proliferation, mostly driven by constitutively activated signaling cascades to which neoplastic cells develop an addiction that can be therapeutically exploited. For instance, the JAK-STAT pathway is frequently hyperactivated in T-ALL and the use of JAK inhibitors in lymphoid malignancies is currently under pre-clinical investigations. In the present thesis, we took advantage of the TS1 cell line recapitulating in vitro JAK-STAT pathway-driven T-cell transformation in order to unravel the underlying genetic events and evaluate the efficacy of JAK inhibitors. In our first study, we found that growth factor-independent TS1 clones acquired an activating point mutation in JAK1 and/or JAK3, which function as partners in the signal transduction downstream of γc-sharing cytokine receptors. Furthermore, TS1 cells transformed by an activated mutant of JAK1 became resistant to JAK inhibitors by acquiring a secondary mutation in JAK3 and vice versa. We demonstrated that the presence of two inhibitor-sensitive JAK1 and JAK3 mutants cooperatively activate STAT3 and STAT5 factors thereby increasing the resistance to JAK inhibitors. In our second study, we focused on the molecular mechanism underlying the high rate of spontaneous mutagenesis in TS1 cells. We demonstrated that loss of MLH1 expression, a key component of the mismatch repair system, promotes the occurrence of oncogenic point mutations in JAK kinases driving transformation and acquired resistance to inhibitors. We confirmed the clinical relevance of our findings by showing that chronic myeloid leukemia cells from patients that relapsed upon ABL-targeted therapy have a lower expression of MLH1 messenger RNA than leukemic cells from patients at diagnosis. Moreover we identified a particular mutational signature present in our TS1 cell model and corresponding to the one described in primitive CD32+ cells from chronic myeloid leukaemia patients that might attest MLH1-deficiency. Taken together, our findings suggest that MLH1 status should be considered in order to predict response to targeted therapies.(BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2015Accès embargo05/10/2015(BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 2015Anglai
Randomized shortest paths and their applications
No full textIn graph analysis, the Shortest Path problem identifies the optimal, most cost effective, path between two nodes. This problem has been the object of many studies and extensions in heterogeneous domains such as: speech recognition, social network analysis, biological sequence alignment, path planning, or zero-sum games among others. Although the shortest path focuses on the optimal cost of reaching a destination node, it does not take into account other useful information contained on the graph, such as the degree of connectivity of two nodes. On the other hand, measures taking connectivity information into account have their own drawbacks, specially when graphs become large. A new family of distances which interpolates between both extremes is introduced by the Randomized Shortest Path (RSP) framework. By spreading randomization through a graph, the RSP leads to applications where some degree of randomness would be desired. Through this work, we try to investigate whether the RSP framework can be applied to different domains in which randomization is useful, and either solve an existing problem with a new approach, or prove to outperform existing methods.(FSA - Sciences de l'ingénieur) -- UCL, 2015Accès libre01/10/2015(FSA - Sciences de l'ingénieur) -- UCL, 2015Anglai
Towards side-channel secure block ciphers
No full textSince the late 90's side-channel attacks have been a threat for cryptographic implementations. They use observations of physical features of a device while it computes cryptographic algorithms. These leakages can give information about the key. A common countermeasure against such attacks is masking. The main idea of masking is to randomize the internal state. In consequence an adversary must combine of several leakages to mount the attack. Masking schemes have an impact on the efficiency of the implementations. In this thesis, we explore different solutions to improve the efficiency of masking implementations. Firstly, we explore solutions for masking implementations for the AES. We investigate the use of amortization technique to reduce the cost of polynomial masking. We also propose a new way to combine Boolean secure multiplications to reduce the cost of masking. Next, we focus on the assumptions used for proofs of masking. We show that the use of low entropy masking schemes can be risky. We also show how to convert proofs in the probing model into proofs in the transition based model. Then, we propose several easier-to-build strategies for masking block ciphers. We present three block ciphers. Finally, we focus on leakage resilience and compare the security that can be obtained by using either leakage-resilient construction, masking or their combination.(FSA - Sciences de l'ingénieur) -- UCL, 2015Accès libre08/12/2015(FSA - Sciences de l'ingénieur) -- UCL, 2015Anglai
Quel système de financement public des cultes et des organisations philosophiques non confessionnelles ?Analyse de constitutionnalité et de conventionnalité
No full textIn Belgium, the Constitution provides that the State finances the recognized religions (1831) and non-confessional organisations (1993). In that context, it is striking to see that current Belgian Law doesn’t formally impose any criteria or procedure of religions’ financing in a legal text. Those elements only come from unwritten rules. After a general overview of the constitutional and conventional principles surrounding the public funding of religions and non-confessional organisations, the doctoral research investigates two problematics. Firstly, it analyses the constitutionality and conventionality of a formal concretization of conditions of funding. Secondly, it focuses on the constitutionality of a creation of formal criteria to distribute the funds between the different recognized religions such as it exists in Spain and Italy.Après un retour sur les principes et fondements qui entourent le financement public tel qu’il existe en Belgique à l’égard des cultes depuis 1831 et à l’égard des organisations philosophiques non confessionnelles depuis 1993, la thèse étudie deux problématiques que soulève fondamentalement ce financement au regard des principes de droit constitutionnel, européen et international qui s’imposent à l’Etat belge, ainsi qu’eu égard à notre société de plus en plus multiconfessionnelle, pluraliste et sécularisée. La première difficulté résulte de l’absence, en droit belge, de critères de reconnaissance et de financement public des cultes et des organisations philosophiques non confessionnelles. Seule existe une « pratique administrative » du Ministre de la Justice, dont cinq critères ont été identifiés à l’occasion de réponses à des questions parlementaires et qui, n’étant inscrits dans aucun instrument formel, sont dépourvus de force juridique contraignante. Dans la thèse, ces cinq critères voient leur constitutionnalité et leur conventionnalité vérifiées au regard de la jurisprudence belge, européenne et internationale afin d’envisager s’ils pourraient un jour valablement se retrouvés inscrits dans la loi, voire dans la Constitution afin de conditionner l’obtention de la reconnaissance et du financement par l’Etat. A côté de ces cinq critères, est étudiée l’éventualité de consacrer un « sixième » critère de financement, lequel existe déjà à l’endroit de bon nombre de destinataires d’un financement public en droit belge (partis politiques, acteurs culturels, enseignement libre subventionné, etc.), à savoir le critère exigeant le respect des droits de l’homme et des principes démocratiques comme condition de financement. Par le biais d’une étude transversale de ce critère, il est proposé d’étendre le respect de ce dernier aux cultes et aux organisations philosophiques non confessionnelle et ce, dans le respect du principe de l’indépendance réciproque entre l’Etat et les communautés religieuses et philosophiques. La seconde difficulté que soulève actuellement le financement public des cultes et des organisations non confessionnelles en Belgique résulte de l’absence de critère de répartition entre les cultes et organisations philosophiques non confessionnelles qui sont reconnus et bénéficient donc dudit financement. La répartition continue à être effectuée suivant une pratique héritée du XIXème siècle qui présumait que l’entièreté de la population était catholique. Cette pratique se justifiait aisément à l’époque puisque le recensement de 1846 révéla que plus de 99% de la population belge était catholique. Pareille supposition n’est désormais plus défendable eu égard aux récents chiffres qui révèlent qu’aujourd’hui, seul un Belge sur deux serait catholique et près d’un tiers de la population ne se rattacherait à aucune confession. Pour pallier cette difficulté, un exercice de droit comparé est effectué entre la Belgique, l’Espagne et l’Italie afin de proposer que soit implémenté en droit belge un système semblable à celui de l’assignation fiscale espagnole ou italienne, lequel permet au contribuable de décider, par le biais de sa fiche d’impôt, de l’identité de la confession qu’il souhaite voir financée au moyen de fonds publics. Ce système permet également aux contribuables qui ne voudraient financer aucune confession d’opter pour des « fins d’utilités sociales » auxquelles le financement sera alors rétrocédé. Si les systèmes espagnol et italien restent – à l’instar de tout système juridique – perfectibles, ils montrent à tout le moins la possibilité de rendre l’allocation du financement plus égalitaire, plus démocratique et davantage en adéquation avec les réalités religieuses et sociétales. Au terme de cette analyse, la thèse invite l’Etat belge à un remaniement du système de financement des cultes et des organisations philosophiques non confessionnelles, en vue d’un meilleur respect des exigences de droit constitutionnel, européen et international qui s’imposent à la Belgique.(DROI - Sciences juridiques) -- UCL, 2015Accès restreint15/12/2015(DROI - Sciences juridiques) -- UCL, 2015Françai