999 resultados para Political selection


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This paper analyzes the different equilibria in rural-urban migrationsand political redistribution that result from the interaction betweenincreasing political returns, the distribution of land, and creditmarket imperfections. Governments that put a special weight on thewelfare of urban workers when setting agricultural prices generate apolitical externality in the urban sector, giving peasants anincentive to migrate in anticipation of policy determination. Ifcredit markets are imperfect, land ownership confers higherproductivity to peasants, who require large price changes to migrate.In this context, land inequality would lead to large migrations and tolarge policy change, while an egalitarian land distribution would leadto no migration and to a small policy change. This interaction shedslight on the contrasting experience of Latin America and East Asia atthe outset of World War II.

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As a result of the Europeanization of politics and the increasing role of the public sphere, political actors in Western Europe are currently facing a double strategic challenge. Based on data from seven West European countries and the European Union, the authors analyze how state actors, political parties, interest groups, and social movement organizations cope with this double challenge at both the national and the supranational level. Results indicate that the classic repertoire of inside strategies at the national level is still the most typical for all actors, but media-related strategies are also prominent at the national level. The Europeanization of repertoires is mainly determined by institutional factors and by the actors' power, whereas the public arena plays an equally important role for all types of actors, in all countries and at both the national and the EU level.

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We performed numerical simulations of DNA chains to understand how local geometry of juxtaposed segments in knotted DNA molecules can guide type II DNA topoisomerases to perform very efficient relaxation of DNA knots. We investigated how the various parameters defining the geometry of inter-segmental juxtapositions at sites of inter-segmental passage reactions mediated by type II DNA topoisomerases can affect the topological consequences of these reactions. We confirmed the hypothesis that by recognizing specific geometry of juxtaposed DNA segments in knotted DNA molecules, type II DNA topoisomerases can maintain the steady-state knotting level below the topological equilibrium. In addition, we revealed that a preference for a particular geometry of juxtaposed segments as sites of strand-passage reaction enables type II DNA topoisomerases to select the most efficient pathway of relaxation of complex DNA knots. The analysis of the best selection criteria for efficient relaxation of complex knots revealed that local structures in random configurations of a given knot type statistically behave as analogous local structures in ideal geometric configurations of the corresponding knot type.

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166 countries have some kind of public old age pension. What economic forcescreate and sustain old age Social Security as a public program? We document some of the internationally and historically common features of Social Security programs including explicit and implicit taxes on labor supply, pay-as-you-go features, intergenerational redistribution, benefits which areincreasing functions of lifetime earnings and not means-tested. We partition theories of Social Security into three groups: "political", "efficiency" and "narrative" theories. We explore three political theories in this paper: the majority rational voting model (with its two versions: "the elderly as the leaders of a winning coalition with the poor" and the "once and for all election" model), the "time-intensive model of political competition" and the "taxpayer protection model". Each of the explanations is compared with the international and historical facts. A companion paper explores the "efficiency" and "narrative" theories, and derives implicationsof all the theories for replacing the typical pay-as-you-go system with a forced savings plan.

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We analyze the channels by which an ill-functioning labor market changes the preferences of the people for public policy and therefore the decisions that are made. We not only discuss labour market reform but other important aspects of policy making such as the size and structure of government spending. Theclass of mechanisms that we highlight can be summarized as the very existence of unemployment generating political support for "sclerosis". This may help to explain the timid pace of reform, in particular the fact that any recovery sends them at the backfront of the political agenda, and the sometimes violent opposition generated by some measures, as we have seen mostly in France.

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This paper characterizes the relationship between entrepreneurial wealth and aggregate investmentunder adverse selection. Its main finding is that such a relationship need not bemonotonic. In particular, three results emerge from the analysis: (i) pooling equilibria, in whichinvestment is independent of entrepreneurial wealth, are more likely to arise when entrepreneurialwealth is relatively low; (ii) separating equilibria, in which investment is increasing inentrepreneurial wealth, are most likely to arise when entrepreneurial wealth is relatively highand; (iii) for a given interest rate, an increase in entrepreneurial wealth may generate a discontinuousfall in investment.

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We study model selection strategies based on penalized empirical loss minimization. We point out a tight relationship between error estimation and data-based complexity penalization: any good error estimate may be converted into a data-based penalty function and the performance of the estimate is governed by the quality of the error estimate. We consider several penalty functions, involving error estimates on independent test data, empirical {\sc vc} dimension, empirical {\sc vc} entropy, andmargin-based quantities. We also consider the maximal difference between the error on the first half of the training data and the second half, and the expected maximal discrepancy, a closely related capacity estimate that can be calculated by Monte Carlo integration. Maximal discrepancy penalty functions are appealing for pattern classification problems, since their computation is equivalent to empirical risk minimization over the training data with some labels flipped.

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We study elections in which one party (the strong party) controls a source of political unrest; e.g., this party could instigate riots if it lost the election. We show that the strong party is more likely to win the election when there is less information about its ability to cause unrest. This is because when theweak party is better informed, it can more reliably prevent political unrest by implementing a ``centrist'' policy. When there is uncertainty over the credibility of the threat, ``posturing'' by the strong party leads to platform divergence.

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Egg laying site selection by a host plant specialist leaf miner moth at two intra-plant levels in the northern Chilean Atacama Desert. The spatial distribution of the immature stages of the leaf miner Angelabella tecomae Vargas & Parra, 2005 was determined at two intra-plant levels (shoot and leaflet) on the shrub Tecoma fulva fulva (Cav.) D. Don (Bignoniaceae) in the Azapa valley, northern Chilean Atacama Desert. An aggregated spatial pattern was detected for all the immature stages along the shoot, with an age dependent relative position: eggs and first instar larvae were clumped at apex; second, third and fourth instar larvae were mostly found at intermediate positions; meanwhile the spinning larva and pupa were clumped at basis. This pattern suggests that the females select new, actively growing leaflets for egg laying. At the leaflet level, the immature stages were found more frequently at underside. Furthermore, survivorship was higher for larvae from underside mines. All these results highlight the importance of an accurate selection of egg laying site in the life history of this highly specialized leaf miner. By contrast, eventual wrong choices in the egg laying site selection may be associated with diminished larval survivorship. The importance of the continuous availability of new plant tissue in this highly human modified arid environment is discussed in relation with the observed patterns.

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El Servei d'Avaluació, Seguiment i Selecció de l'ISPC han elaborat un estudi sobre el perfil de personalitat dels aspirants al Curs de Formació bàsica per policies, que es va presentar a l'International Society for the Study of Individual Differences Meeting celebrat al CosmoCaixa de Barcelona i que organitzen conjuntament l’Associació Iberoamericana per a la recerca de les diferències individuals i la Universitat de Barcelona. L’estudi, titulat Revised NEO Personality Inventory Normative Data for Catalan police officer selection: A preliminary study, té com a objectiu comparar els perfils de personalitat d’una mostra d’aspirants de l’ISPC amb els resultats d’una mostra d’aspirants a policia dels EUA, publicada en una revista científica de prestigi el mes de febrer passat. Els resultats mostren que els aspirants catalans destaquen per obtenir millors puntuacions en les dimensions de responsabilitat i amabilitat, cosa que indicaria que aquest tret es valora especialment durant el procés de selecció de la policia de Catalunya; en altres característiques de la personalitat les dues mostres obtenen resultats similars. Els trets característics del perfil del policia català seria el de persones estables emocionalment, poc impulsives, amb capacitat per gestionar l’estrés, orientades a les persones, agradables, sociables, responsables, disciplinades i cauteloses. Enllaç a: International Society for the Study of Individual Differences Meeting :http://www.issid.org/conferences/ISSID2013/ISSIDconference2013.html

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Le répertoire cellulaire Τ a pour but d'être tolérant aux antigènes du soi afin d'éviter l'induction de maladies autoimmunes. C'est pourquoi les lymphocytes Τ autoréactifs sont éliminés dans le thymus lors de leur développement par le processus de sélection négative. La plupart des recherches étudient les lymphocytes Τ de haute avidité. Ces lymphocytes Τ de haute avidité sont très sensibles et réagissent fortement à un antigène du soi. En conséquence, ces cellules induisent le développement de maladies autoimmunes lorsqu'elles ciblent des organes exprimant l'antigène du soi. Plusieurs études ont montré que les lymphocytes Τ qui réagissent faiblement aux antigènes spécifiques à un tissu, nommé lymphocytes Τ de faible avidité, peuvent contourner les mécanismes de tolérance centrale et périphérique. J'ai utilisé des souris Rip-mOva qui expriment l'Ovalbumine comme antigène du soi spécifique à un tissu. Dans ces souris transgéniques Rip-mOva, les lymphocytes Τ de faible avidité survivent à la sélection négative. Une fois stimulés à la périphérie, ces lymphocytes Τ CD8+ de faible avidité ont la capacité d'infiltrer les organes qui expriment l'antigène du soi chez les souris Rip-mOva et peuvent induire une destruction tissulaire. L'objectif principal de mon projet de thèse était de comprendre les caractéristiques phénotypiques et fonctionnelles de ces lymphocytes Τ dans un état d'équilibre et dans un contexte infectieux. Pour étudier ces cellules dans un modèle murin bien défini, nous avons généré des souris exprimant un récepteur de cellule Τ transgénique appelé OT-3. Ces souris transgéniques OT-3 ont des lymphocytes Τ CD8+ de faible avidité spécifiques à l'épitope SIINFEKL de l'antigène Ovalbumine. Nous avons démontré qu'un grand nombre de lymphocytes Τ CD8+ OT-3 ne sont pas éliminés lors de la sélection négative dans le thymus après avoir rencontré l'antigène du soi. Par conséquent, les lymphocytes Τ OT-3 de faible avidité sont présents dans une fenêtre de sélection comprise entre la sélection positive et négative. Cette limite se définie comme le seuil d'affinité et est impliquée dans l'échappement de certains lymphocytes Τ OT- 3 autoréactifs. A la périphérie, ces cellules sont capables d'induire une autoimmunité après stimulation au cours d'une infection, ce qui nous permet de les définir comme étant non tolérante et non dans un état anergique à la périphérie. Nous avons également étudié le seuil d'activation des lymphocytes Τ OT-3 à faible avidité à la périphérie et avons constaté que des ligands peptidiques plus faibles que l'épitope natif SIINFEKL sont capables de les activer au cours d'une infection ainsi que de les différencier en lymphocytes Τ effecteurs et mémoires. Les données illustrent une déficience lors de la sélection négative dans le thymus de lymphocytes Τ CD8+ autoréactifs de faible avidité contre un antigène du soi spécifique à tissu et montrent que ces cellules sont entièrement compétentes lors d'une infection. - The diverse Τ cell repertoire needs to be tolerant to self-antigen to avoid the induction of autoimmunity. This is why autoreactive developing Τ cells are deleted in the thymus. The deletion of self-reactive Τ cells occurs through the process of negative selection. Most studies investigated high avidity Τ cells. These high avidity Τ cells are very sensitive and strongly react to a self-antigen. As a consequence, these cells induce the development of autoimmunity when they target organs which express the self-antigen. High avidity autoreactive CD8+ Τ cells are deleted in the thymus. However, several studies have shown Τ cells that weakly respond to tissue-restricted antigen, referred to as low avidity Τ cells, can bypass central and peripheral tolerance mechanisms. I used Rip-mOva mice that expressed Ovalbumin as a neo self-antigen in a tissue-restricted fashion. In these transgenic Rip-mOva mice low avidity CD8+ Τ cells survive negative selection. Upon stimulation in the periphery, these low avidity CD8+ Τ cells have the ability to infiltrate organs that express the self-antigen in the Rip-mOva mice and can also induce the destruction of the tissue. The major aim of my PhD project was to understand the phenotypic and functionality characteristics of these Τ cells in a steady-state condition and in a context of an infection. To study these cells in a well-defined mouse model, we generated OT-3 Τ cell receptor transgenic mice that express low avidity CD8+ Τ cells that are specific for the SIINFEKL epitope of the Ovalbumin antigen. We have been able to demonstrate that a large number of OT-3 CD8+ Τ cells survive negative selection in the thymus after encountering the self-antigen. Thus, low avidity OT-3 Τ cells are present in a window of selection comprised between positive and negative selection. This boundary defined as the affinity threshold is involved in the escape of some autoreactive low avidity OT-3 Τ cells. Once they circulate in the periphery, they are able to induce autoimmunity after stimulation during an infection, allowing us to allocate these cells as being non-tolerant and not in an anergic state in the periphery. We have also looked at the threshold of activation of low avidity OT-3 CD8+ Τ cells in the periphery and found that peptide ligands that are weaker than the native SIINFEKL epitope are able to activate OT-3 Τ cells during an infection and to differentiate them into effector and memory Τ cells. The data illustrate the impairment of negatively selecting low avidity autoreactive CD8+ Τ cells against a tissue-restricted antigen in the thymus and shows that these cells are fully competent upon an infection.

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Quelles sont les conditions pour l'émergence d'une mobilisation sociale en faveur du logement convenable dans la métropole de Bangalore (Inde)? Cette question, qui est au coeur de cette thèse, est particulièrement pertinente dans le contexte d'une ville où 1,7 million de personnes, soit un cinquième de la population, vit dans des bidonvilles. L'absence d'un mouvement mettant en cause l'échec des politiques publiques du logement est intéressante dans la mesure où l'Inde a hérité un système de gouvernance colonial et d'une tradition de mouvements sociaux. Pour répondre à ce questionnement, un cadre théorique issu de la littérature sur les mouvements sociaux est développé. Il s'articule autour des liens entre les opportunités politiques au niveau macro et les répertoires d'action des organisations de mouvement social (OMS) au niveau méso, de la tension entre la formalité de la loi et des politiques publiques et l'informalité des circuits d'échange, de la corruption et du clientélisme, et enfin, se focalise sur les systèmes de discours de caste et de la citoyenneté et de leur concrétisation dans des systèmes d'organisations et de réseaux sociaux. Ce cadre théorique permet d'étudier empiriquement la question à travers quatre OMS dans la ville de Bangalore. Les résultats mettent en avant l'existence de mécanismes complexes. Les opportunités politiques formelles n'étant ouvertes que sur le plan rhétorique, elles ne peuvent être véritablement utilisées que par des moyens légaux ou contentieux, ce qui nécessite des compétences sociales dont la plupart des habitants des bidonvilles sont dépourvus. L'inadéquation entre les ressources à disposition pour les logements sociaux et les besoins très importants des pauvres, donne un poids politique considérable aux acteurs en charge de l'attribution de ces ressources rares. Cet état de fait a des répercussions sur la politique électorale. Les habitants des bidonvilles représentant un poids électoral important, ils sont mobilisés à travers de pratiques clientélistes. La corruption et le clientélisme se nourrissent mutuellement pour maintenir une certaine dépendance des habitants. Les OMS qui développent un répertoire discursif remettant en cause le système de caste et qui encouragent une conscience citoyenne, se sont avérées les plus durables pour résister à la cooptation des forces politiques. Cette recherche empirique met en lumière l'inadéquation entre les prescriptions formelles dans le domaine de la gouvernance des besoins humains, tels que le logement, et les pratiques réelles sur le terrain. Cette recherche appelle à réfléchir au-delà de la diffusion du discours sur la « bonne gouvernance » vers des formes de « gouvernance vernaculaire » qui prendrait au sérieux l'informalité en développant une compréhension des avantages à court terme pour les personnes marginalisées dans la ville et les effets à long terme sur la pratique démocratique. - What are the conditions for the emergence of a social movement on the issue of adequate housing in the metropolitan city of Bangalore (India)? This question is at the heart of this dissertation and is particularly pertinent against the background that an estimated 1.7 million or about 20% of the city's population lives in slums. The absence of a movement addressing the failure of public housing policy despite India having inherited colonial systems of governance and traditions of movement is noteworthy. Answers are sought within a theoretical framework stemming from social movement theories that incorporates three linkages articulating around: Macro-level political opportunities and meso-level action repertoires of social movement organisations (SMOs), tensions between the formality of law, policy and the informality of exchange circuits of corruption and clientelism and finally around systems of discourses of caste and citizenship and their instantiation in concrete systems of social organisations and networks. This thesis is empirically investigated through a qualitative case study research design involving four sampled social movement organisations. The results bring complex mechanisms to the fore. Formal political opportunities are only rhetorically open and have to be cracked through legal weaponry or contentious escalation, which requires considerable social skills that slum-dwellers often lack. The inadequacy between the few housing resources and the vast number of slum-dwellers transform housing benefits and urban service provisions into political currency. Such a state of affairs has serious repercussions on conditions for mobilisation. They become imbricated with electoral logic, in which slum-dwellers represent large vote-banks and where corruption and clientelism feed each other to maintain a certain dependency of the poor. SMOs deploying a discursive repertoire that questioned the caste system and encouraged a pursuit of citizenship proved to be the most sustainable to resist co-option from political forces. This empirical investigation brings to light the mismatch between the formal prescriptions in the domain of the governance of basic human needs such as housing and the real practices on the ground. This research calls to reflect beyond the inadequacy of the diffused « good governance » discourse towards forms of « vernacular governance » that take informality seriously in understanding the short-term benefits for the marginalised in the city and the long-term effects on democratic practice.

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Thymic positive and negative selection of developing T lymphocytes confronts us with a paradox: How can a T-cell antigen receptor (TCR)-major histocompatibility complex (MHC)/peptide interaction in the former process lead to transduction of signals allowing for cell survival and in the latter induce programmed cell death or a hyporesponsive state known as anergy? One of the hypotheses put forward states that the outcome of a TCR-MHC/peptide interaction depends on the cell type presenting the selecting ligand to the developing thymocyte. Here we describe the development and lack of self-tolerance of CD8(+) T lymphocytes in transgenic mice expressing MHC class I molecules in the thymus exclusively on cortical epithelial cells. Despite the absence of MHC class I expression on professional antigen-presenting cells, normal numbers of CD8(+) cells were observed in the periphery. Upon specific activation, transgenic CD8(+) T cells efficiently lysed syngeneic MHC class I(+) targets in vitro and in vivo, indicating that thymic cortical epithelium (in contrast to medullary epithelium and antigen-presenting cells of hematopoietic origin) is incapable of tolerance induction. Thus, compartmentalization of the antigen-presenting cells involved in thymic positive selection and tolerance induction can (at least in part) explain the positive/negative selection paradox.