953 resultados para quasi-likelihood
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A counterpart of the Mackey–Arens Theorem for the class of locally quasi-convex topological Abelian groups (LQC-groups) was initiated in Chasco et al. (Stud Math 132(3):257–284, 1999). Several authors have been interested in the problems posed there and have done clarifying contributions, although the main question of that source remains open. Some differences between the Mackey Theory for locally convex spaces and for locally quasi-convex groups, stem from the following fact: The supremum of all compatible locally quasi-convex topologies for a topological abelian group G may not coincide with the topology of uniform convergence on the weak quasi-convex compact subsets of the dual groupG∧. Thus, a substantial part of the classical Mackey–Arens Theorem cannot be generalized to LQC-groups. Furthermore, the mentioned fact gives rise to a grading in the property of “being a Mackey group”, as defined and thoroughly studied in Díaz Nieto and Martín-Peinador (Proceedings in Mathematics and Statistics 80:119–144, 2014). At present it is not known—and this is the main open question—if the supremum of all the compatible locally quasi-convex topologies on a topological group is in fact a compatible topology. In the present paper we do a sort of historical review on the Mackey Theory, and we compare it in the two settings of locally convex spaces and of locally quasi-convex groups. We point out some general questions which are still open, under the name of Problems.
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Recently, mindfulness-based social-emotional learning (SEL) approaches have been taught to children in some schools. Due to deficient methodological consistency observed in most studies, their results should be interpreted with caution. Moreover, research on how mindfulness-based SEL approaches benefit teachers is scarce, and the majority of these studies have been conducted in English-speaking countries; therefore, it is uncertain whether these approaches are suited to other cultural backgrounds. The aim of the present study was to evaluate the efficacy of the MindUp curriculum, an SEL program through mindfulness practice for Portuguese students and teachers. Participants included 454 3rd and 4th grade students and 20 teachers from state schools. A quasiexperimental (pre- and post-test) study compared outcomes for an experimental group with a waitlist control group. Data were collected from teachers and children through self-report measures. Results showed that over 50 % of the children who participated in the MindUp program scored above the control group mean in their ability to regulate emotions, to experience more positive affect, and to be more self-compassionate, and over 50 % scored lower in negative affect. In the group of teachers, over 80 % scored above the control group mean in observing, in personal accomplishment, and in self-kindness. Our results contribute to the recent research on the potential added value of mindfulness practices to a SEL program and strengthen the importance for teachers and students of adding to the academic curriculum a SEL program through mindfulness practices.
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This article examines regulatory governance of the post-initial training market in The Netherlands. From an historical perspective on policy formation processes, it examines market formation in terms of social, economic, and cultural factors in the development of provision and demand for post-initial training; the roles of stakeholders in the longterm construction of regulatory governance of the market; regulation of and public providers; policy responses to market failure; and tripartite division of responsibilities between the state, social partners, commercial and publicly-funded providers. Historical description and analysis examine policy narratives of key stakeholders with reference to: a) influence of societal stakeholders on regulatory decision-making; b) state regulation of the post-initial training market; c) public intervention regulating the market to prevent market failure; d) market deregulation, competition, employability and individual responsibility; and, e) regulatory governance to prevent ‘allocative failure’ by the market in non-delivery of post-initial training to specific target groups, particularly the low-qualified. Dominant policy narratives have resulted in limited state regulation of the supply-side, a tripartite system of regulatory governance by the state, social partners and commercial providers as regulatory actors. Current policy discourses address interventions on the demand-side to redistribute structures of opportunity throughout the life courses of individuals. Further empirical research from a comparative historical perspective is required to deepen contemporary understandings of regulatory governance of markets and the commodification of adult learning in knowledge societies and information economies. (DIPF/Orig.)
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No estudo de séries temporais, os processos estocásticos usuais assumem que as distribuições marginais são contínuas e, em geral, não são adequados para modelar séries de contagem, pois as suas características não lineares colocam alguns problemas estatísticos, principalmente na estimação dos parâmetros. Assim, investigou-se metodologias apropriadas de análise e modelação de séries com distribuições marginais discretas. Neste contexto, Al-Osh and Alzaid (1987) e McKenzie (1988) introduziram na literatura a classe dos modelos autorregressivos com valores inteiros não negativos, os processos INAR. Estes modelos têm sido frequentemente tratados em artigos científicos ao longo das últimas décadas, pois a sua importância nas aplicações em diversas áreas do conhecimento tem despertado um grande interesse no seu estudo. Neste trabalho, após uma breve revisão sobre séries temporais e os métodos clássicos para a sua análise, apresentamos os modelos autorregressivos de valores inteiros não negativos de primeira ordem INAR (1) e a sua extensão para uma ordem p, as suas propriedades e alguns métodos de estimação dos parâmetros nomeadamente, o método de Yule-Walker, o método de Mínimos Quadrados Condicionais (MQC), o método de Máxima Verosimilhança Condicional (MVC) e o método de Quase Máxima Verosimilhança (QMV). Apresentamos também um critério automático de seleção de ordem para modelos INAR, baseado no Critério de Informação de Akaike Corrigido, AICC, um dos critérios usados para determinar a ordem em modelos autorregressivos, AR. Finalmente, apresenta-se uma aplicação da metodologia dos modelos INAR em dados reais de contagem relativos aos setores dos transportes marítimos e atividades de seguros de Cabo Verde.
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In this paper we show how to accurately perform a quasi-a priori estimation of the truncation error of steady-state solutions computed by a discontinuous Galerkin spectral element method. We estimate the spatial truncation error using the ?-estimation procedure. While most works in the literature rely on fully time-converged solutions on grids with different spacing to perform the estimation, we use non time-converged solutions on one grid with different polynomial orders. The quasi-a priori approach estimates the error while the residual of the time-iterative method is not negligible. Furthermore, the method permits one to decouple the surface and the volume contributions of the truncation error, and provides information about the anisotropy of the solution as well as its rate of convergence in polynomial order. First, we focus on the analysis of one dimensional scalar conservation laws to examine the accuracy of the estimate. Then, we extend the analysis to two dimensional problems. We demonstrate that this quasi-a priori approach yields a spectrally accurate estimate of the truncation error.
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Doutoramento em Gestão
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This thesis studies mobile robotic manipulators, where one or more robot manipulator arms are integrated with a mobile robotic base. The base could be a wheeled or tracked vehicle, or it might be a multi-limbed locomotor. As robots are increasingly deployed in complex and unstructured environments, the need for mobile manipulation increases. Mobile robotic assistants have the potential to revolutionize human lives in a large variety of settings including home, industrial and outdoor environments.
Mobile Manipulation is the use or study of such mobile robots as they interact with physical objects in their environment. As compared to fixed base manipulators, mobile manipulators can take advantage of the base mechanism’s added degrees of freedom in the task planning and execution process. But their use also poses new problems in the analysis and control of base system stability, and the planning of coordinated base and arm motions. For mobile manipulators to be successfully and efficiently used, a thorough understanding of their kinematics, stability, and capabilities is required. Moreover, because mobile manipulators typically possess a large number of actuators, new and efficient methods to coordinate their large numbers of degrees of freedom are needed to make them practically deployable. This thesis develops new kinematic and stability analyses of mobile manipulation, and new algorithms to efficiently plan their motions.
I first develop detailed and novel descriptions of the kinematics governing the operation of multi- limbed legged robots working in the presence of gravity, and whose limbs may also be simultaneously used for manipulation. The fundamental stance constraint that arises from simple assumptions about friction and the ground contact and feasible motions is derived. Thereafter, a local relationship between joint motions and motions of the robot abdomen and reaching limbs is developed. Baseeon these relationships, one can define and analyze local kinematic qualities including limberness, wrench resistance and local dexterity. While previous researchers have noted the similarity between multi- fingered grasping and quasi-static manipulation, this thesis makes explicit connections between these two problems.
The kinematic expressions form the basis for a local motion planning problem that that determines the joint motions to achieve several simultaneous objectives while maintaining stance stability in the presence of gravity. This problem is translated into a convex quadratic program entitled the balanced priority solution, whose existence and uniqueness properties are developed. This problem is related in spirit to the classical redundancy resoxlution and task-priority approaches. With some simple modifications, this local planning and optimization problem can be extended to handle a large variety of goals and constraints that arise in mobile-manipulation. This local planning problem applies readily to other mobile bases including wheeled and articulated bases. This thesis describes the use of the local planning techniques to generate global plans, as well as for use within a feedback loop. The work in this thesis is motivated in part by many practical tasks involving the Surrogate and RoboSimian robots at NASA/JPL, and a large number of examples involving the two robots, both real and simulated, are provided.
Finally, this thesis provides an analysis of simultaneous force and motion control for multi- limbed legged robots. Starting with a classical linear stiffness relationship, an analysis of this problem for multiple point contacts is described. The local velocity planning problem is extended to include generation of forces, as well as to maintain stability using force-feedback. This thesis also provides a concise, novel definition of static stability, and proves some conditions under which it is satisfied.
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This report reviews literature on the rate of convergence of maximum likelihood estimators and establishes a Central Limit Theorem, which yields an O(1/sqrt(n)) rate of convergence of the maximum likelihood estimator under somewhat relaxed smoothness conditions. These conditions include the existence of a one-sided derivative in θ of the pdf, compared to up to three that are classically required. A verification through simulation is included in the end of the report.
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This report discusses the calculation of analytic second-order bias techniques for the maximum likelihood estimates (for short, MLEs) of the unknown parameters of the distribution in quality and reliability analysis. It is well-known that the MLEs are widely used to estimate the unknown parameters of the probability distributions due to their various desirable properties; for example, the MLEs are asymptotically unbiased, consistent, and asymptotically normal. However, many of these properties depend on an extremely large sample sizes. Those properties, such as unbiasedness, may not be valid for small or even moderate sample sizes, which are more practical in real data applications. Therefore, some bias-corrected techniques for the MLEs are desired in practice, especially when the sample size is small. Two commonly used popular techniques to reduce the bias of the MLEs, are ‘preventive’ and ‘corrective’ approaches. They both can reduce the bias of the MLEs to order O(n−2), whereas the ‘preventive’ approach does not have an explicit closed form expression. Consequently, we mainly focus on the ‘corrective’ approach in this report. To illustrate the importance of the bias-correction in practice, we apply the bias-corrected method to two popular lifetime distributions: the inverse Lindley distribution and the weighted Lindley distribution. Numerical studies based on the two distributions show that the considered bias-corrected technique is highly recommended over other commonly used estimators without bias-correction. Therefore, special attention should be paid when we estimate the unknown parameters of the probability distributions under the scenario in which the sample size is small or moderate.
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La tesis presenta evidencia rigurosa de la efectividad de las políticas públicas utilizando metodologías experimentales y cuasi-experimentales. La tesis comienza con una introducción completa y una revisión rigurosa de las metodologías que se utilizarán en el análisis posterior de los datos. El primer capítulo, "Habilidades personales y habilidades técnicas en programas de formación de jóvenes. Evidencia Experimental de Largo Plazo de República Dominicana ", evalúa el impacto de un programa de empleo de los jóvenes en una serie de variables de interés. El programa ofrece capacitación en las habilidades vocacionales y en las habilidades no cognitivas a jóvenes en riesgo de exclusión social. Cabe destacar que la metodología utilizada para evaluar el programa es un ensayo controlado aleatorio, que proporciona evidencia robusta del efecto causal del programa. Mientras que estudios previos analizaron el impacto de los programas para jóvenes relacionados, ningún estudio anterior había evaluado los efectos de 4 años después de la implementación del programa. Esto representa una contribución importante debido a que las ganancias a corto plazo de varios programas de desarrollo han demostrado no ser sostenida en el tiempo. Esto es también lo que este estudio encuentra para los resultados del mercado de trabajo: mientras que el programa genera una mejora a corto plazo de los resultados de empleo para las mujeres, este efecto se disipa en el largo plazo. Sin embargo, el programa parece conducir a cambios persistentes en las expectativas del mercado de trabajo de las mujeres: las mujeres que asistieron al entrenamiento de informar una visión más optimista de las perspectivas del mercado de trabajo hasta 4 años después del programa...
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A number of laws in Canada which uphold rights are referred to as quasi-constitutional by the courts in recognition of their special importance. Quasi-constitutional statutes are enacted through the regular legislative process, although they are being interpreted and applied in a fashion which has become remarkably similar to constitutional law, and are therefore having an important affect over other legislation. Quasi-constitutionality has surprisingly received limited scholarly attention, and very few serious attempts at explaining its significance have been made. This dissertation undertakes a comprehensive study of quasi-constitutionality which considers its theoretical basis, its interpretation and legal significance, as well as its similarities to comparable forms of law in other Commonwealth jurisdictions. Part I examines the theoretical basis of quasi-constitutionality and its relationship to the Constitution. As a statutory and common law form of fundamental law, quasi-constitutionality is shown to signify an association with the Canadian Constitution and the foundational principles that underpin it. Part II proceeds to consider the special rules of interpretation applied to quasi-constitutional legislation, the basis of this interpretative approach, and the connection between the interpretation of similar provisions in quasi-constitutional legislation and the Constitution. As a statutory form of fundamental law, quasi-constitutional legislation is given a broad, liberal and purposive interpretation which significantly expands the rights which they protect. The theoretical basis of this approach is found in both the fundamental nature of the rights upheld by quasi-constitutional legislation as well as legislative intent. Part III explores how quasi-constitutional statutes affect the interpretation of regular legislation and how they are used for the purposes of judicial review. Quasi-constitutional legislation has a significant influence over regular statutes in the interpretative exercise, which in some instances results in conflicting statutes being declared inoperable. The basis of this form of judicial review is demonstrated to be rooted in statutory interpretation, and as such it provides an interesting model of rights protection and judicial review that is not conflated to constitutional and judicial supremacy.
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Numerical techniques such as the Boundary Element Method, Finite Element Method and Finite Difference Time Domain have been used widely to investigate plane and curved wave-front scattering by rough surfaces. For certain shapes of roughness elements (cylinders, semi-cylinders and ellipsoids) there are semi-analytical alternatives. Here, we present a theory for multiple scattering by cylinders on a hard surface to investigate effects due to different roughness shape, the effects of vacancies and variation of roughness element size on the excess attenuation due to a periodically rough surfaces.
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The objective of this work was to apply fuzzy majority multicriteria group decision?making to determine risk areas for foot?and?mouth disease (FMD) introduction along the border between Brazil and Paraguay. The study was conducted in three municipalities in the state of Mato Grosso do Sul, Brazil, located along the border with Paraguay. Four scenarios were built, applying the following linguistic quantifiers to describe risk factors: few, half, many, and most. The three criteria considered to be most likely to affect the vulnerability to introduction of FMD, according to experts? opinions, were: the introduction of animals in the farm, the distance from the border, and the type of property settlements. The resulting maps show a strong spatial heterogeneity in the risk of FMD introduction. The used methodology brings out a new approach that can be helpful to policy makers in the combat and eradication of FMD.