La propagation des ondes ultrasonores à travers des cristaux phononiques CP à deux dimensions 2D constitués de diffuseurs solides dans des matrices solide et fluide est ici étudiée, ainsi que la caractérisation de ces milieux et leur application à l’imagerie acoustique. Les techniques expérimentales utilisées permettent une mesure complète des champs transmis à travers les cristaux. Les études sont menées dans des bandes fréquentielles autorisant les effets de réfraction négative indispensables à l’obtention d’une résolution inférieure à la limite de diffraction (super-résolution). De manière à compléter les analyses, différents outils théoriques sont exploités Décomposition en Ondes Planes et Eléments Finis, notamment.La première partie du document concerne la réalisation et la caractérisation de cristaux phononiques possédant des propriétés nécessaires à la réalisation de systèmes d’imagerie acoustique réfraction négative, contours équi-fréquences circulaires, accord d’indice, accord d’impédance. Cette première étude est menée sur un cristal à matrice solide, elle met en relief la possibilité de générer différents modes de Bloch au cours de la propagation. L’accord d’indice avec l’eau n’étant cependant pas obtenu, la seconde partie porte sur la réfraction négative et la focalisation des ondes à travers un CP à matrice fluide. Les propriétés du CP déterminées, le dernier chapitre s’attache à évaluer les performances des systèmes d’imagerie développés : dynamique et résolution. / This investigation deals with wave propagation in two dimensional phononic crystals (PC) made of solid scatterers embedded in solid or fluid matrices. After characterizing such composite materials, their application to acoustic imaging is brought to the forth. The ultrasonic techniques used in the experiments allow the complete measurement of the acoustic transmitted fields and the investigations concern frequency bandwidth able to exhibit negative refraction allowing Oie super-resolution effects. In order to complete the analysis, different theoretical tools are used: Plane Wave Expansion (PWE) and Finite Elements Method (FEM).The first part of this work deals with the realization and characterization of PC to be introduced into acoustic imaging devices (lenses) based on negative refraction. Special attention is given to characteristics such as circular equi-frequency contours, or index and impedance matching. However, during the acoustic wave propagation in a solid PC immersed in water, the presence of different Bloch modes contributing to the transmission of ultrasound is revealed and the index matching was not possible to obtain. Therefore the second part of the manuscript deals with negative refraction and waves focusing through a PC filled with a fluid. After determining the crystal properties, last chapter is devoted to the evaluation of the performances of acoustic imaging systems based on phononic lens.

Estudamos os efeitos não lineares em cristais dopados com Cr+3 como o Rubi (Al2O3: Cr+3) e o Aluminato de Gadolínio (GdAlO3: Cr+3), acrescentados através de um índice de refração dependente da intensidade de luz incidente, que caracteriza os meios tipo Kerr (n= n0+n2I, com n2= n2´+in2´). As propriedades não lineares desses cristais se devem à diferença de susceptibilidades do estado excitado e do estado fundamental dos íons de Cr+3. Este modelo é amplamente conhecido, e explica muito bem os efeitos não lineares do Rubi. Porém, para o GdAl O3: Cr+3 há um efeito que não pode ser explicado por esse modelo simplificado: a dependência da razão r= n2\"/n2\' com a intensidade, cuia observação experimental foi feita utilizando a técnica de Mistura de Duas Ondas (MDO). A explicação para esse efeito foi apresentada recentemente e propõe que seja devido à interação de pares de Cr, presente quando a concentração de íons de Cr no material é alta. Neste trabalho verificamos a dependência de r com a intensidade por MDO e utilizando uma nova técnica, a MDO transiente. Esta última possui a grande vantagem de fornecer a razão r de forma direta, enquanto que na MDO, r é obtido pelo ajuste de uma curva de ganho. Como resultado, observamos que a MDO transiente fornece uma dependência de r com a intensidade que está de acordo com a prevista pela interação de pares de Cr e é superior à obtida por MDO. Também apresentamos os parâmetros determinados via MDO (n2\', a intensidade de saturação do meio, r e o tempo de resposta do meio) para 488 nm no GdAlO3: Cr+3, cujos valores ainda não são conhecidos na literatura / We have studied the nonlinear properties of Chromium doped crystals such as ruby (Al2O3: Cr+3) and Gadolinium aluminate (GdAlO3: Cr+3), given by the intensity dependent refractive index characteristic of Kerr media, where n= n0+n2I and n2= n2´+in2´. The nonlinear properties of these crystals are due to the difference between the excited and the ground state susceptibilities. This model is widely used and explains the nonlinearity of ruby. However, GdAlO3: Cr+3 presents an effect that cannot be explained by that simplified approach: the intensity dependence of the parameter r=n2\"/n2\'. The experimental observation of such dependence was achieved using the Two Wave Mixing technique. An explanation for this effect was recently proposed using the interaction between Chromium ions that occurs when their concentration is high enough. In this work we observed the intensity dependence of r via two wave mixing and using a new technique, transient Two wave mixing. The last one gives the parameter r in a direct way, while the two waves mixing gives r by the fitting of a gain curve. As a result, we observed that transient two wave mixing shows greater intensity dependence than two wave mixing and agree with the interaction of Chromium ions. Also, we present the Two wave mixing parameters (n2\', the saturation intensity and response time of the medium) at 488nm, that were never reported before

O presente trabalho pretende demonstrar que a pseudotradução (compreendida como a apresentação de um texto ficcional original como se fosse uma tradução de um original que não existe) e a autorrefração (ou seja, a recriação, pelo próprio autor, de um texto seu em outro contexto, formato ou forma literária) são elementos centrais para a poderosa ilusão de profundidade cultural conjurada pela obra de J.R.R. Tolkien. Ao apresentar uma elaborada moldura metanarrativa, que postula a existência de manuscritos antigos, longas cadeias de transmissão e adaptação de textos e múltiplos idiomas nos quais essa transmissão se dá, Tolkien dá um passo crucial para aproximar sua obra das mitologias reais. / This dissertation aims to show that pseudotranslation (defined as the presentation of an original, fictional text as a translation of a foreign text that does not actually exist) and self-refraction (that is, the recreation, by the author himself, of one of his texts in a different cultural context, format or literary form) are key elements for the powerful illusion of cultural depth conjured up by the works of J.R.R. Tolkien. By presenting an elaborate metanarrative framework and postulating the existence of ancient manuscripts, long chains of cultural transmission and adaptation and multiple languages in which such transmission occurs, Tolkien takes a crucial step to bring his works to the same level of real mythologies.

Orientador: Edmea Rita Temporini Nastari / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-07T08:57:15Z (GMT). No. of bitstreams: 1 Bisneto_OtavioSiqueira_M.pdf: 1532415 bytes, checksum: 54c06aa08a8469404379be1a2f2c1a08 (MD5) Previous issue date: 2006 / Resumo: Objetivo: avaliar a relação entre aberrações de alta ordem, erros de refração e idade. Material e Método: realizou-se estudo retrospectivo analítico, de pacientes submetidos a exames de aberrometria. Foram incluídos neste estudo todos os sujeitos examinados no aberrômetro LADARWAVE® (Alcon, Fort Worth, Texas), no Hospital de Olhos do Paraná (Curitiba-Brasil) no período de abril de 2004 a abril de 2005, sendo o principal critério de inclusão acuidade visual corrigida ou não de 20/20 ou melhor e o principal critério de exclusão presença de cirurgia e/ou doença ocular prévia. Foram estudadas as seguintes variáveis: idade, grau de refração esféro-cilíndrica, medida do equivalente esférico, aberrações de alta ordem divididas em: coma, aberração esférica, outras e root mean square (rms) de alta ordem. Todas as variáveis foram obtidas através do exame de aberrometria realizado no aberrômetro LADARWAVE®, sob cicloplegia, considerando-se pupila de 6,5 mm. Foram avaliadas aberrações ópticas de alta ordem até a oitava ordem nos polinômios de Zernike. Os pacientes foram divididos em 6 grupos de acordo com o erro de refração e em 3 grupos de acordo com a idade. Resultados: foram avaliados 312 olhos dos quais 201 foram incluídos no estudo. A idade média desses pacientes foi de 33,9±10,1 anos variando de 7 a 62 anos. Após análise estatística, na comparação entre os grupos de acordo com o erro de refração, foi observado que os pacientes hipermétropes com astigmatismo inferior a -0,75 D (GRUPO 5) apresentaram maior quantidade de aberração esférica, e que os pacientes hipermétropes com astigmatismo superior a -0,75 D (GRUPO 6) apresentaram maior quantidade de aberrações denominadas "outras" e RMS de alta ordem. Na comparação geral entre os grupos de idade, em relação as variáveis estudadas, o grupo de pacientes com 45 ou mais anos (GRUPO C) apresentou maior quantidade de todas as aberrações estudadas. Conclusão: a) houve relação positiva, estatisticamente significativa, entre hipermetropia, com e sem astigmatismo, e aberração esférica e rms de alta ordem. b) houve relação positiva, estatisticamente significativa, entre idade e aberrações ópticas de alta ordem / Abstract: Purpose: to evaluate the relationship between high order aberrations and refraction errors, and between high order aberrations and age. Methods: an analytic retrospective study of patients that underwent aberrometry exam was done. All the subjects examined at LADARWAVE® aberrometer at Hospital de Olhos do Paraná from April 2004 to April 2005 were included in this study. The major inclusion criterion was 20/20 or better - corrected or not - visual acuity; and the major exclusion criterion, the presence of previous eye surgery or eye disease. The following variable were analyzed: age, refraction, spherical equivalent, and high order aberrations wich were: coma, spherical aberration, others, and high order root mean square (rms). All data were obtained from LADARWAVE® aberrometry exam, under ciclopegia, taking only 6.5 mm pupil results. High order aberrations up to eight order Zernike's coefficients were evaluated. Patients were divided in 6 groups according to refraction error and in 3 groups according to age. Results: out of 312 eyes, 201 were studied. The mean age of was 33.9 +- 10.1, varying from 7 to 62 years of age. After statistical analysis, it was observed that among the refraction error groups hyperopic patients with less than -0,75 D astigmatism (group 5) showed a higher amount of spherical aberration, and that hyperopic patients with more than -0,75 D astigmatism (group 6) showed a higher amount of other and high order rms aberrations. In the general comparison between the age groups, the 45 or older group (group C) showed a higher amount of all the aberrations analyzed. Conclusion: a) there was a statiscally significant positive relation between hyperopia - with or without astigmatism - and spherical aberration and high order rms. b) there was a statiscally significant positive relation between age and all aberrations analyzed. / Mestrado / Oftalmologia / Mestre em Ciências Médicas

M.Phil. (Optometry) / Different representations of dioptric power and their relative coordinate systems are summarised. The transition matrices required to switch from one coordinate system to another are provided. Three sets of data are analysed; a sample of 205 refractions, a sample of 205 keratometric readings and a sample of 790 autorefractive excesses of 790 autorefractions over 790 subjective refractions. Brief mention is made of emmetropisation. In the event that such a driving force exists, the possible effects on the distributional characteristics of refractive error are noted. Normality and the assessment thereof are discussed qualitatively and quantitatively. The univariate marginal and multivariate joint distributions .of the samples are examined using the coordinate system introduced by Deal and Toop (1993): their vector is represented by d=(d 1 d 2 d3)~ Departure from normality is determined in three ways; assessment of the linearity of the chi-square probability plots, measures of skewness and measures of kurtosis. Marginal normal probability plots are included for completeness. The statistical procedures and some of the theory involved in the implementation of these techniques are described briefly to assist in the interpretation of the distribution analysis. Marginal transformations are employed to improve the normality of the marginal distributions in an attempt to reduce the multivariate departure from normality. Power transformations and shifted power transformations are described and applied to the data.

Geophysical investigation of the subsurface through seismic refraction and reflection methods provides an efficient and non-invasive means towards addressing geologic problems across multiple scales. Both seismic techniques, in an active-source exploration setting, involve inducing acoustic waves into the subsurface and measuring their propagation velocities and amplitudes. These measurements have physically-based relationships with the properties of the underlying strata, thus allowing changes in the seismic measurements to be interpreted with respect to changes in the subsurface geology. Two applications of the seismic method are presented in this dissertation: (1) shallow seismic refraction acquisition and processing applied to the near-surface investigations of soil and regolith, which constitute the Critical Zone (CZ), beneath the upland hillslopes of the Valles Caldera, New Mexico; (2) interpretation of 2-D and 3-D marine seismic reflection data that image the upper 10-km of the crust beneath the Southern Guinea Plateau, offshore Guinea, West Africa. In both cases, the seismic data provide necessary constraints for the generation of accurate subsurface models that permit further geophysical modeling. The near-surface results, presented in Appendix A, provided a rich dataset of weathered thicknesses across hillslopes that supported an investigation of potential relationships between CZ geologic architecture and topographic attributes. Quantified relationships suggest that calibrated predictions based on the topography can provide first-order estimates of regolith thickness across upland landscapes. These results add to the ongoing CZ-science endeavor to understand proposed links between subsurface weathering processes and their surface expressions. In Appendix B, interpretations of high-resolution 3-D seismic data have illuminated deformational structures associated with Mesozoic rifting of the Southern Guinea Plateau. The interpretations were expanded onto regional 2-D seismic profiles, permitting a regional synthesis of the southern margin’s structural evolution. Additional tectonic subsidence and forward-gravity modeling highlight the influence of Jurassic rifting on the Southern Guinea Plateau prior to Early-Cretaceous rifting and separation, as well as crustal thickness estimates from the continental shelf out towards oceanic crust. Lastly, the Guinea-Demerara conjugate plateaus, and their associated deformations, were restored to 100 Ma, revealing an apparent upper-crustal asymmetry between the two margins. Appendix C presents two seismic-exploration methodologies based on 3-D seismic reflection data: (1) the calculation and interpretation of two co-rendered volumetric seismic attributes – most-positive curvature and semblance; (2) numerically modeling the tectonic subsidence of an entire 3-D seismic survey. Both techniques are used to address the inherent difficulty in interpreting the extent to which Jurassic rifting affected the Southern Guinea Plateau. Furthermore, the numerical model of subsidence provides a new exploration technique towards qualitatively and quantitatively assisting in the assessment of potential hydrocarbon-bearing basins.

M.Sc. (Optometry) / The difference between objective automatic and subjective clinical refraction is studied using new statistical techniques. The question, by how much the two refraction techniques differ, is investigated by subtracting the subjective refraction finding from the auto refractory finding and then examining the distribution of the difference or excess as it will be called here. Computerized procedures were developed to automate mathematical and statistical methods of analysis. The methods were applied to two different samples: one of patients visiting an ordinary optometric practice (the clinical sample) and the other of children refracted in a screening program (the sample of school children) . The clinical sample, consisting of mainly older patients, is examined first. The difference between the autorefractor and subjective findings is studied and described. This difference could be used to compare different types of auto refractors assuming that the subjective refraction is correct. For the purpose of this study, however, the results of eight autorefractors are grouped together, combining left and right eyes, to serve as basis for studying the older population. The study shows that on the average there is no clinically significant excess. This means that there is on average no clinically significant difference between the automatic and clinical refraction for this population.

This thesis proposes and tests an individually customizable model of the human crystalline lens. This model will be crucial in developing both research on the human eye and driving diagnostic tools to help plan and treat optical issues, such as those requiring refractive surgery. This thesis attempts to meet two goals: first, it will determine whether this new lens model can reproduce the major aberrations of real human eyes using a computational framework. Second, it will use clinical information to measure how well this model is able to predict post-operation results in refractive surgery, attempting to meet clinical standards of error. The model of the crystalline lens proposed within this thesis is shown to be valid, as it is able to both reproduce individual patient's optical information, and correctly predicts the optical results of a refractive surgery of an individual human eye within clinical standards of error.

In March of 1987, the Geologic Survey of Canada conducted a major seismic refraction experiment in the Mackenzie Delta-Southern Beaufort Sea-Northern Yukon area. This study involves the analysis of a portion of the resulting data set. A 2D velocity profile through the Richardson Mountains of the northern Yukon has been constructed using raytracing to model the travel-times and amplitudes. The line is approximately 320 km long, running from a shotpointon the Eagle Plains in the south to one 50 km offshore in Mackenzie Bay to the north, with an average receiver spacing of 3.5 km. An additional shotpoint is located at Shingle Point, on the shore of Mackenzie Bay. A series of four sedimentary basins separated by major structural highs produces a complex basement structure. Two distinct upper crustal layers were modelled, a 5.95 km/s layer overlying a 6.3 km/s layer, as well as a lower crustal layer with a velocity of 7.25 km/s. Crustal velocity gradients are low (≤ 0.005 s⁻¹). The 6.3 km/s layer pinches out beneath the Beaufort-Mackenzie Basin in the north, accompanied by a thinning of the lower crust from a thickness of 20 km in the south to less than 10 km beneath MB. This results in the crust as a whole thinning from a thickness of 50 km under the Richardson Mountains to only 40 km under the Beaufort-Mackenzie Basin. The velocity of the upper mantle is 7.95 km/s. The modelling of shear wave arrivals indicate Poisson's ratios of 0.23 ±0.02 in the upper crust and 0.25 + 0.02 in the lower crust. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The Main Ethiopian Rift is a part of the East African Rift, from where the African plate is being teared apart and separated from the Indian and the Arabian plate. Even though earthquakes in this area are relatively less frequent, the subsurface structure is a subject of big research interest, since information about the subsurface layers has considerable relevance when it comes to site amplication related to earthquakes. The aim of this project is to map and compare the subsurface structures of two sites located in the Ethiopian Rift, using seismic refraction technique. By looking at the first arrivals of artificial seismic waves on a designated site, the velocities as well as the thicknessof the subsurface layers can be obtained. The result showed that the both sites contained a low velocity structure which contained weathered material.