29 resultados para Spaces
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We extend the Weyl-Wigner transformation to those particular degrees of freedom described by a finite number of states using a technique of constructing operator bases developed by Schwinger. Discrete transformation kernels are presented instead of continuous coordinate-momentum pair system and systems such as the one-dimensional canonical continuous coordinate-momentum pair system and the two-dimensional rotation system are described by special limits. Expressions are explicitly given for the spin one-half case. © 1988.
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Using the flexibility and constructive definition of the Schwinger bases, we developed different mapping procedures to enhance different aspects of the dynamics and of the symmetries of an extended version of the two-level Lipkin model. The classical limits of the dynamics are discussed in connection with the different mappings. Discrete Wigner functions are also calculated. © 1995.
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In this paper, we consider a vector optimization problem where all functions involved are defined on Banach spaces. We obtain necessary and sufficient criteria for optimality in the form of Karush-Kuhn-Tucker conditions. We also introduce a nonsmooth dual problem and provide duality theorems.
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Group theoretical-based techniques and fundamental results from number theory are used in order to allow for the construction of exact projectors in finite-dimensional spaces. These operators are shown to make use only of discrete variables, which play the role of discrete generator coordinates, and their application in the number symmetry restoration is carried out in a nuclear BCS wave function which explicitly violates that symmetry. © 1999 Published by Elsevier Science B.V. All rights reserved.
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The quality of open urban spaces is very important for urban vitality. Nowadays urban designers have to face the great challenge of designing urban spaces able to respond to people's need for liveable spaces. The success of these spaces depends on various aspects and the microclimatic condition has been recognized as one of the most influential. However, studies on thermal comfort in open space have shown that the user's thermal sensation does not depend only on microclimate parameters but also on other local qualitative aspects. Thus, environmental quality evaluation of successful public spaces can contribute to understand this issue. This paper focuses on a case study regarding Queen Square's environmental quality, a public space of historical importance in Bath-UK. The first stage of the research, a study on local characteristics and people observations, allowed a preliminary evaluation of the space performance, their social aspects, while it characterized and quantified the hourly variation of the space use in different days and seasons. In the second stage, short microclimatic surveys were carried out simultaneously with a perception survey through a questionnaire. The results show the strong vitality of the square and socioenvironmental significance, not only for its location in the urban context, but also for its historical value. The environmental quality of the square contributes to the users' sensation of comfort even in adverse climatic conditions. This research is part of a project that aims to investigate the impact of the environmental stimuli in the use of open spaces and intend to develop design strategies that aim to maximise the use of open spaces in different weather conditions.
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Esthetic orthodontic appliances continue to appeal to more patients, which results in objections to extraction spaces that remain for several months during orthodontic therapy. This has led orthodontists to design temporary pontics that fill extraction sites and that can be reduced as the spaces close. This report describes a simple, efficient, and expeditious technique for making such pontics. © 2010 Quintessence Publishing Co, Inc.
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In the book Conceptual Spaces: the Geometry of Thought [2000] Peter Gärdenfors proposes a new framework for cognitive science. Complementary to symbolic and subsymbolic [connectionist] descriptions, conceptual spaces are semantic structures constructed from empirical data representing the universe of mental states. We argue that Gärdenfors' modeling can be used in consciousness research to describe the phenomenal conscious world, its elements and their intrinsic relations. The conceptual space approach affords the construction of a universal state space of human consciousness, where all possible kinds of human conscious states could be mapped. Starting from this approach, we discuss the inclusion of feelings and emotions in conceptual spaces, and their relation to perceptual and cognitive states. Current debate on integration of affect/emotion and perception/cognition allows three possible descriptive alternatives: emotion resulting from basic cognition; cognition resulting from basic emotion, and both as relatively independent functions integrated by brain mechanisms. Finding a solution for this issue is an important step in any attempt of successful modeling of natural or artificial consciousness. After making a brief review of proposals in this area, we summarize the essentials of a new model of consciousness based on neuro-astroglial interactions. © 2011 World Scientific Publishing Company.
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Increased urbanization typically leads to an increase in abundance of a few species and a reduction in bird species richness. Understanding the structure of biotic communities in urban areas will allow us to propose management techniques and to decrease conflicts between wild species and human beings. The objective of this study was to describe the structure of the bird community in an urban ecosystem. The study was carried out in the city of Taubaté in southeastern Brazil. Point-counts were established in areas with different levels of tree density ranging from urban green spaces to predominantly built-up areas. We looked for a correlation between the richness/abundance of birds and the size of the area surveyed, the number of houses, the number of tree species and the number of individual trees. The results of multiple regression showed that bird richness had a direct relationship with vegetation complexity. The abundance and diversity of tree species were better predictors of bird species than the number of houses and size of the area surveyed. We discuss implications of this study for conservation and management of bird diversity in urban areas, such as the need to increase green areas containing a large diversity of native plant species. © 2011 Springer Science+Business Media, LLC.
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In this paper, we show a local-in-time existence result for the 3D micropolar fluid system in the framework of Besov-Morrey spaces. The initial data class is larger than the previous ones and contains strongly singular functions and measures. © 2013 Springer Basel.
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Constrained intervals, intervals as a mapping from [0, 1] to polynomials of degree one (linear functions) with non-negative slopes, and arithmetic on constrained intervals generate a space that turns out to be a cancellative abelian monoid albeit with a richer set of properties than the usual (standard) space of interval arithmetic. This means that not only do we have the classical embedding as developed by H. Radström, S. Markov, and the extension of E. Kaucher but the properties of these polynomials. We study the geometry of the embedding of intervals into a quasilinear space and some of the properties of the mapping of constrained intervals into a space of polynomials. It is assumed that the reader is familiar with the basic notions of interval arithmetic and interval analysis. © 2013 Springer-Verlag Berlin Heidelberg.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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An extended Weyl-Wigner transformation which maps operators onto periodic discrete quantum phase space representatives is discussed in which a mod N invariance is explicitly implemented. The relevance of this invariance for the mapped expression of products of operators is discussed. © 1992.