977 resultados para Decazes, Élie (1780-1860)


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We tagged a total of 14 yellowtail snapper (Ocyurus chrysurus Bloch 1790) and black grouper (Mycteroperca bonaci Poey 1860) inside the Conch Reef Research Only Area (a no-take marine reserve) in the northern Florida Keys National Marine Sanctuary in November 2001. Both species are heavily exploited in the region. Our objective was to characterize site fidelity and movement behavior along the reef tract to the north and south of the release point. Fishes were collected by baited hook and line from the surface, surgically-tagged with coded-acoustic transmitters, and returned to the reef by snorkelers. Tracking of fish movement behavior was conducted by five acoustic receivers deployed on the seafloor from Davis Reef in the south to Pickles Reef in the north. Fishes were tracked for up to eight months. Results indicated that the majority of signal detections for individual fish from both species were recorded at the two Conch Reef receivers. Limited movement from Conch Reef to Davis Reef was recorded, but no signal detections were recorded at the two sites to the north of Conch Reef. These results suggest that both species show site fidelity to Conch Reef. Future studies will seek to characterize this site fidelity with increased temporal and spatial resolution at Conch Reef. (PDF contains 25 pages.)

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Eterio Pajares, Raquel Merino y José Miguel Santamaría (eds.)

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This thesis is mainly concerned with the application of groups of transformations to differential equations and in particular with the connection between the group structure of a given equation and the existence of exact solutions and conservation laws. In this respect the Lie-Bäcklund groups of tangent transformations, particular cases of which are the Lie tangent and the Lie point groups, are extensively used.

In Chapter I we first review the classical results of Lie, Bäcklund and Bianchi as well as the more recent ones due mainly to Ovsjannikov. We then concentrate on the Lie-Bäcklund groups (or more precisely on the corresponding Lie-Bäcklund operators), as introduced by Ibragimov and Anderson, and prove some lemmas about them which are useful for the following chapters. Finally we introduce the concept of a conditionally admissible operator (as opposed to an admissible one) and show how this can be used to generate exact solutions.

In Chapter II we establish the group nature of all separable solutions and conserved quantities in classical mechanics by analyzing the group structure of the Hamilton-Jacobi equation. It is shown that consideration of only Lie point groups is insufficient. For this purpose a special type of Lie-Bäcklund groups, those equivalent to Lie tangent groups, is used. It is also shown how these generalized groups induce Lie point groups on Hamilton's equations. The generalization of the above results to any first order equation, where the dependent variable does not appear explicitly, is obvious. In the second part of this chapter we investigate admissible operators (or equivalently constants of motion) of the Hamilton-Jacobi equation with polynornial dependence on the momenta. The form of the most general constant of motion linear, quadratic and cubic in the momenta is explicitly found. Emphasis is given to the quadratic case, where the particular case of a fixed (say zero) energy state is also considered; it is shown that in the latter case additional symmetries may appear. Finally, some potentials of physical interest admitting higher symmetries are considered. These include potentials due to two centers and limiting cases thereof. The most general two-center potential admitting a quadratic constant of motion is obtained, as well as the corresponding invariant. Also some new cubic invariants are found.

In Chapter III we first establish the group nature of all separable solutions of any linear, homogeneous equation. We then concentrate on the Schrodinger equation and look for an algorithm which generates a quantum invariant from a classical one. The problem of an isomorphism between functions in classical observables and quantum observables is studied concretely and constructively. For functions at most quadratic in the momenta an isomorphism is possible which agrees with Weyl' s transform and which takes invariants into invariants. It is not possible to extend the isomorphism indefinitely. The requirement that an invariant goes into an invariant may necessitate variants of Weyl' s transform. This is illustrated for the case of cubic invariants. Finally, the case of a specific value of energy is considered; in this case Weyl's transform does not yield an isomorphism even for the quadratic case. However, for this case a correspondence mapping a classical invariant to a quantum orie is explicitly found.

Chapters IV and V are concerned with the general group structure of evolution equations. In Chapter IV we establish a one to one correspondence between admissible Lie-Bäcklund operators of evolution equations (derivable from a variational principle) and conservation laws of these equations. This correspondence takes the form of a simple algorithm.

In Chapter V we first establish the group nature of all Bäcklund transformations (BT) by proving that any solution generated by a BT is invariant under the action of some conditionally admissible operator. We then use an algorithm based on invariance criteria to rederive many known BT and to derive some new ones. Finally, we propose a generalization of BT which, among other advantages, clarifies the connection between the wave-train solution and a BT in the sense that, a BT may be thought of as a variation of parameters of some. special case of the wave-train solution (usually the solitary wave one). Some open problems are indicated.

Most of the material of Chapters II and III is contained in [I], [II], [III] and [IV] and the first part of Chapter V in [V].

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On October 24, 1871, a massacre of eighteen Chinese in Los Angeles brought the small southern California settlement into the national spotlight. Within a few days, news of this “night of horrors” was reported in newspapers across the country. This massacre has been cited in Asian American narratives as the first documented outbreak of ethnic violence against a Chinese community in the United States. This is ironic because Los Angeles’ small population has generally placed it on the periphery in historical studies of the California anti-Chinese movement. Because the massacre predated Los Angeles’ organized Chinese exclusion movements of the late 1870s, it has often been erroneously dismissed as an aberration in the history of the city.

The violence of 1871 was an outburst highlighting existing community tensions that would become part of public debate by decade’s close. The purpose of this study is to insert the massacre into a broader context of anti-Chinese sentiments, legal discrimination, and dehumanization in nineteenth century Los Angeles. While a second incident of widespread anti-Chinese violence never occurred, brutal attacks directed at Chinese small businessmen and others highlighted continued community conflict. Similarly, economic rivalries and concerns over Chinese prostitution that underlay the 1871 massacre were manifest in later campaigns of economic discrimination and vice suppression that sought to minimize Chinese influence within municipal limits. An analysis of the massacre in terms of anti-Chinese legal, social and economic strategies in nineteenth-century Los Angeles will elucidate these important continuities.

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A proposta deste estudo implicou explorar a hipótese de que eram múltiplas as forças que compunham o cenário de constituição das tradições escolares no século XIX e que a Igreja Católica figurava como uma delas. Nesta pesquisa buscou-se investigar sua presença no processo de escolarização Oitocentista, bem como as relações estabelecidas com o Estado Imperial. Reconhecendo a presença da instituição católica neste cenário, a proposta tencionou evidenciar aspectos das relações que a mesma procurou estabelecer com o poder público nos termos da gestão política e cultural. Entender a complexidade e historicidade desta força, a Igreja Católica, tornou-se primordial para refletir acerca de sua inscrição nos assuntos da educação, a partir de experiências relacionadas às escolas públicas e privadas no Oitocentos. Pretendeu igualmente, esquadrinhar experiências diversificadas de alguns sujeitos em relação ao projeto de instruir sob o signo católico, inquirir aspetos gerais do funcionamento de instituições criadas, mantidas, amparadas, autorizadas a fazer funcionar a engrenagem do ensino em nome do Estado Imperial e da Igreja Católica. Da mesma forma, tencionou interrogar a composição dos saberes nos planos de estudos dos estabelecimentos de ensino público e privado, observando nos termos da lei, a presença da doutrina cristã. Este conjunto de interesses será trabalhado a partir da proposição de quatro capítulos. Para tanto, trabalhou-se com uma massa documental composta por leis, reformas, ofícios, relatórios, artigos de jornais, propagandas, bulas papais, datados entre as décadas de 1860 e 1880

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Ao lado de uma forte influência cultural francesa verificada no Brasil Império, ao longo do século XIX, diversas fontes parecem indicar também uma forte presença francesa no domínio agrário, isto é, em projetos, ideias e até medidas concretas, relacionadas ao setor fundiário brasileiro, então marcado por um forte predomínio da grande propriedade rural e escravista, no quadro de uma agricultura voltada principalmente para a exportação. Nossa pesquisa, apoiando-se em documentos diversos (livros, diários, periódicos e relatórios ministeriais), procura apreender a presença de uma real influência francesa no discurso agrário formulado por políticos no Brasil da segunda metade do século XIX, em pleno contexto de gradual abolição da escravidão. Focalizamos desde personalidades famosas do liberalismo brasileiro, como André Rebouças, Tavares Bastos e Joaquim Nabuco, até membros da esfera administrativa imperial, especificamente do Ministério da Agricultura. O estudo aborda as referências intelectuais francesas dos personagens estudados, e examina alguns textos citados pelos brasileiros, no período compreendido entre 1860 e 1889. Com base em ampla consulta bibliográfica, junto à historiografia brasileira e à historiografia francesa, abordamos o contexto agrário dos dois países, desde fins do século XVIII até o final do século XIX e examinamos o impacto de medidas instituídas na França como o imposto territorial e da ação e pensamentos de homens como Mathieu de Dombasle, Michel Chevalier e Léonce Lavergne. Buscamos, assim, compreender em que medida a França teria contribuído para a disseminação de um discurso voltado para a modernização da agricultura brasileira, no contexto de transição do trabalho escravo para o trabalho livre no Brasil imperial, e para a formação de um ideário favorável ao estímulo à pequena propriedade fundiária.

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O presente trabalho pretende analisar as representações da cidade do Rio de Janeiro nas crônicas de José de Alencar e Joaquim Manuel de Macedo, publicadas, respectivamente, sob os títulos Ao Correr da Pena (1855-1856) e Labirinto (1860), tendo como objetivo mapear a cidade capital do império e as transformações pelas quais passou entre as décadas de 1850 e 1860. Tal proposta foi desenvolvida à luz do método cartográfico apresentado por Franco Moretti, em suas obras Atlas do Romance Europeu 1800-1900 e A Literatura Vista de Longe, nas quais o autor trata a criação de mapas como um instrumento intelectual que abriria caminho para novos questionamentos e novas conclusões no campo do imaginário. Ademais, ao utilizar obras literárias como fontes primárias para a análise da cidade do Rio de Janeiro do século XIX e suas especificidades no cenário brasileiro imperial, o presente trabalho dialoga com uma história cultural do urbano.

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We have developed a novel human facial tracking system that operates in real time at a video frame rate without needing any special hardware. The approach is based on the use of Lie algebra, and uses three-dimensional feature points on the targeted human face. It is assumed that the roughly estimated facial model (relative coordinates of the three-dimensional feature points) is known. First, the initial feature positions of the face are determined using a model fitting technique. Then, the tracking is operated by the following sequence: (1) capture the new video frame and render feature points to the image plane; (2) search for new positions of the feature points on the image plane; (3) get the Euclidean matrix from the moving vector and the three-dimensional information for the points; and (4) rotate and translate the feature points by using the Euclidean matrix, and render the new points on the image plane. The key algorithm of this tracker is to estimate the Euclidean matrix by using a least square technique based on Lie algebra. The resulting tracker performed very well on the task of tracking a human face.