959 resultados para Square lattices
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A new constructive family of asymptotically good lattices with respect to sphere packing density is presented. The family has a lattice in every dimension n >= 1. Each lattice is obtained from a conveniently chosen integral ideal in a subfield of the cyclotomic field Q(zeta(q)) where q is the smallest prime congruent to 1 modulo n.
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Vortex shedding phenomenon produced by a square cylinder placed close to a smooth flat plate is experimentally studied by means of flow visualization techniques and hot-film anemometry. Qualitative and quantitative information about the flow field has been obtained for Reynolds numbers up to 1,000. Vortex shedding images in several Reynolds number have been captured and the non dimensional vortex shedding frequency has been obtained as a function of the Reynolds number.
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With aging process, there is a natural biological decline that eventually may lead to a functional and cognitive decrease. It is important that older people preserve these functions so they can live an independent life. Some declines in old people who attend Geriatric Day-Care tend to be more severe and recurrent. The Square Stepping Exercise (SSE) is a program created by Shigematsu & Okura (2006), in order to improve the balance of its practitioners, thereby decreasing the risk of falls. It is also believed that the SSE stimulates cognition, and thus, executive functions. The present study, with a longitudinal design, evaluated the effects of SSE in balance performance and executive functions of elderly from the “Centro-Dia do Idoso Padre Casagrande” from Rio Claro – SP. A group of 15 people (GT, n = 15), which performed a four month SSE intervention, and a control group (GC; n = 17) answered the following evaluations.: Questionnaire Registration Data and Anamnesis, Questionnaire Baeck Modified for Elderly, Mini-Mental State Examination, Modified Card Sorting Test, Geriatric Depressive Scale, Questionnaire Pfeffer for Instrumental Activities, Berg Balance Scale and Time Up and Go Test. Although significant improvements have not been observed in GT, the results showed a decline in instrumental activities performance in GC, as well as maintenance in executive functions and balance, and also an improvement in depressive symptoms in GT. This way, Square Stepping Exercise can be considered an activity that helps maintaining functional capacity, among them balance, and executive function in elderly people.
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Many studies inform that with aging process there’s a drop, not only in the cognitive functions, but also in the functional fitness. This drop can damage the old people’s daily activities, making them lose their independence. These declines can be softened with the practice of physical exercises. So, the aim of this study is to develop a systematic review in the literature which is the quantity of lectures done using the Square Stepping Exercise, we use a follow keyword “Square Stepping Exercise”. We performed a search in the following databases: PUBMED, Portal de Periódicos CAPES, Google Acadêmico e Catálogo Athena (acervo da Biblioteca de todos os campus da UNESP). Those procedures were complemented for manual searches in the references of the found lectures, like the access to the curriculum vitae, plataforma Lattes. There were analyzed articles, in Portuguese and English. Language were selected 11 studies (2 monografies, 1 masters lecture, 1 experience relatorie, 1 book chapter and 6 articles). The references found had improvement in motor and cognitive aspects. With this review, it was concluded that the SSE showed itself as a useful method to get better and/or maintain the analyzed aspects. It’s also necessary new studies with different populations, tips of analyse, periods of time and other aspects
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In this paper, we present new constructions of ideal lattices for the Rayleigh fading channel in Euclidean spaces with full diversity. These constructions are through totally real subfields of cyclotomic fields, obtained by endowing their ring of integers. With this method we reproduce rotated versions of algebraic lattices where the performance in terms of minimum product distance is related with the field determinant.
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In this paper we introduce a type of Hypercomplex Fourier Series based on Quaternions, and discuss on a Hypercomplex version of the Square of the Error Theorem. Since their discovery by Hamilton (Sinegre [1]), quaternions have provided beautifully insights either on the structure of different areas of Mathematics or in the connections of Mathematics with other fields. For instance: I) Pauli spin matrices used in Physics can be easily explained through quaternions analysis (Lan [2]); II) Fundamental theorem of Algebra (Eilenberg [3]), which asserts that the polynomial analysis in quaternions maps into itself the four dimensional sphere of all real quaternions, with the point infinity added, and the degree of this map is n. Motivated on earlier works by two of us on Power Series (Pendeza et al. [4]), and in a recent paper on Liouville’s Theorem (Borges and Mar˜o [5]), we obtain an Hypercomplex version of the Fourier Series, which hopefully can be used for the treatment of hypergeometric partial differential equations such as the dumped harmonic oscillation.
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The focus of this paper is to address some classical results for a class of hypercomplex numbers. More specifically we present an extension of the Square of the Error Theorem and a Bessel inequality for octonions.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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In this paper we present a method for evaluating the center density of algebraic lattices from subfields of Q(xi n), where n is a positive integer. This method allows to reproduce rotated versions of dense lattices in some dimensions. Constellations on algebraic lattices with high packing density have been proposed for use in communications in Gaussian channels and also in Rayleigh fading channels in case they have high diversity.
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The temperature dependencies of specific heat and spin susceptibility of a coupled dx2-y2 + idxy superconductor in the presence of a weak dxy component are investigated in the tight-binding model (1) on square lattice and (2) on a lattice with orthorhombic distortion. As the temperature is lowered past the critical temperature Tc, first a less ordered dx2-y2 superconductor is created, which changes to a more ordered dx2-y2 + idxy superconductor at Tcl(< Tc). This manifests in two second order phase transitions identified by two jumps in specific heat at Tc and Tc1. The temperature dependencies of the superconducting observables exhibit a change from power-law to exponential behavior as temperature is lowered below Tc1 and confirm the new phase transition. © 1998 Published by Elsevier Science B.V. All rights reserved.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)