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Submitted by Daniella Sodre (daniella.sodre@ufpe.br) on 2015-04-15T17:06:16Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO ANA PAULA FIGUEIREDO.pdf: 11566036 bytes, checksum: c3fc3fe38a89915d87262f49d7d15674 (MD5) / Made available in DSpace on 2015-04-15T17:06:16Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO ANA PAULA FIGUEIREDO.pdf: 11566036 bytes, checksum: c3fc3fe38a89915d87262f49d7d15674 (MD5) Previous issue date: 2013-02-20 / Este trabalho é um estudo exploratório sobre o modo como alunos do ensino médio lidam com problemas sobre volume. Neste estudo, o conceito de volume é investigado sob a ótica da Teoria dos Campos Conceituais desenvolvida por Gérard Vergnaud e colaboradores. Adotamos como hipótese didática que volume deve ser considerado como grandeza. Tal hipótese é uma adaptação das pesquisas de Régine Douady e Marie-Jeanne Perrin-Glorian sobre área de figuras planas. Volume é, portanto, considerado como um dos constituintes do campo conceitual das grandezas geométricas e como conceito, na perspectiva proposta por Vergnaud, ou seja, como tripé de três conjuntos indissociáveis: o conjunto das situações que lhe dão sentido, o conjunto dos invariantes sobre os quais se apoia a operacionalidade dos esquemas e o conjunto das representações simbólicas em jogo na apresentação e resolução das tarefas relativas ao volume. A parte experimental deste trabalho consistiu na aplicação de teste de sondagem e de entrevistas com alunos do terceiro ano do ensino médio de três instituições de ensino das redes privada, pública federal e pública estadual. A análise dos resultados foi desenvolvida relacionando aspectos presentes na revisão de literatura e na fundamentação teórica. Podemos observar que o campo numérico predomina em relação ao campo geométrico e das grandezas, na maioria das situações de volume abordadas e que situações de medida são as mais compreendidas pelos sujeitos. Os aspectos abordados nesta pesquisa apontam para lacunas e entraves de natureza epistemológica, como aqueles cuja origem está na complexidade das relações entre volume e outras grandezas físicas e geométricas (como massa e área respectivamente), com os conceitos de dimensionalidade e capacidade. Mas, por outro lado, os dados apontam para uma possível origem didática para esses entraves e lacunas, reforçando a hipótese levantada em pesquisas anteriores de que a ênfase excessiva no uso de fórmulas e nas situações de medida não parece dar conta da atribuição de um significado mais amplo para volume.

Made available in DSpace on 2014-10-09T12:23:39Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:20Z (GMT). No. of bitstreams: 1 01047.pdf: 536137 bytes, checksum: 03a51eb43941329a5063f6f5a3acd271 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Biociencias, Universidade de Sao Paulo - IB/USP

Ce travail de thèse se veut une contribution à l’homogénéisation numérique des milieux élasto-plastiques hétérogènes aléatoires via des calculs sur des grands volumes. La thèse comporte deux parties principales. La première est dédiée à la réponse élasto-plastique macroscopique des composites, à distribution aléatoire de la seconde phase, sollicités en traction uniaxiale. La deuxième est focalisée sur la réponse macroscopique à la limite d’écoulement des milieux poreux aléatoires sur une large gamme de triaxialités. Dans la première partie, nous décrivons une méthode d’homogénéisation numérique pour estimer la réponse élasto-plastique macroscopique de milieux composites aléatoires à deux phases. La méthode est basée sur des simulations éléments finis utilisant des cellules cubiques tridimensionnelles de différentes tailles mais plus petites que le volume élémentaire représentatif de la microstructure. Dans une seconde partie, nous décrivons une étude d’homogénéisation numérique par éléments finis sur des cellules cubiques tridimensionnelles afin de prédire la surface d’écoulement macroscopique de milieux poreux aléatoires contenant une ou deux populations de vides. La représentativité des résultats est examinée en utilisant des cellules cubiques contenant des vides sphéroïdales, répartis et orientés aléatoirement. Les résultats numériques sont comparés à des critères d’écoulement existants de type Gurson. / This PhD dissertation deals with the numerical homogenization of heterogeneous elastic-plastic random media via large volume computations. The dissertation is presented in two main parts. The first part is dedicated to the effective elastic-plastic response of random two-phase composites stretched under uniaxial loading. The second part is focused on the effective yield response of random porous media over a wide range of stress triaxialities. In the first part, we describe a computational homogenization methodology to estimate the effective elastic-plastic response of random two-phase composite media. The method is based on finite element simulations using three-dimensional cubic cells of different size but smaller than the deterministic representative volume element of the microstructure. In the second part, we describe using the finite element method a computational homogenization study of three-dimensional cubic cells in order to estimate the effective yield surface of random porous media containing one or two populations of voids. The representativity of the overall yield surface estimates is examined using cubic cells containing randomly distributed and oriented spheroidal voids. The computational results are compared with some existing Gurson-type yield criteria.

A reflectance volume holographic imaging (VHI) endoscope has been designed for simultaneous in vivo imaging of surface and subsurface tissue structures. Prior utilization of VHI systems has been limited to ex vivo tissue imaging. The VHI system presented in this work is designed for laparoscopic use. It consists of a probe section that relays light from the tissue sample to a handheld unit that contains the VHI microscope. The probe section is constructed from gradient index (GRIN) lenses that form a 1: 1 relay for image collection. The probe has an outer diameter of 3.8 mm and is capable of achieving 228.1 lp/mm resolution with 660-nm Kohler illumination. The handheld optical section operates with a magnification of 13.9 and a field of view of 390 mu m x 244 mu m. System performance is assessed through imaging of 1951 USAF resolution targets and soft tissue samples. The system has also passed sterilization procedures required for surgical use and has been used in two laparoscopic surgical procedures. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)

Outlined is a new approach to the problem of surfacing particle-based fluid simulations. The key idea is to construct a surface that is as smooth as possible while remaining faithful to the particle locations. We describe a mesh-based algorithm that expresses the surface in terms of a constrained optimization problem. Our algorithm incorporates a secondary contribution in Marching Tiles, a generalization of the Marching Cubes isosurfacing algorithm. Marching Tiles provides guarantees on the minimum vertex valence, making the surface mesh more amenable to numerical operators such as the Bilaplacian. / Science, Faculty of / Computer Science, Department of / Graduate

The ability of oocytes and early cleavage-stage embryos to regulate their volume is essential to avoid developmental arrests at in vivo-osmolarities. This is accomplished primarily via GLYT1-mediated glycine transport into the cells. GLYT1 activity has previously been shown to be absent in freshly isolated oocytes but becomes activated ~3-4 hours after oocyte maturation has been initiated either by isolation from ovarian follicles in vitro or following an ovulatory stimulus in vivo. GLYT1 activity then persists until the 4-cell stage of preimplantation embryo development. GLYT1 has been shown to spontaneously activate in oocytes that are isolated from follicles either as denuded oocytes or as cumulus-oocyte complexes (COCs), this implies that GLYT1 activity is suppressed in intact follicles in the ovary. However, it is not known how GLYT1 activity is suppressed within the ovarian follicle or how initial GLYT1 activation occurs. The activation of independent cell volume regulation in oocytes first involves the release of the strong adhesion between the oocyte and zona pellucida (ZP) followed by secondary GLYT1 activation. These two processes have been shown to occur spontaneously in fully grown oocytes following isolation from ovarian follicles, however, it is not known whether small growing oocytes within ovarian follicles already possess the ability to detach from the ZP and activate GLYT1. An osmotic assay was used to determine when during oogenesis oocytes are first able to detach from the ZP while the ability to activate GLYT1 was determined by measuring [3H]-glycine uptake into oocytes. I found that oocytes acquire the ability to detach from the ZP when they are nearly fully grown and similarly, that high levels of GLYT1 activity first develop in isolated oocytes during the late stages of oogenesis. Furthermore, I showed that SLC6A9 protein (GLYT1 transporter protein) and Slc6a9a transcripts steadily increased during oogenesis with SLC6A9 protein becoming localized to the oocyte plasma membrane during oocyte growth with predominant membrane localization apparent in fully grown oocytes. Taken together, these results suggest that oocytes become able to detach from the ZP and fully activate GLYT1 towards the end of oogenesis but that these processes remain suppressed in the ovarian follicle. Intact and punctured antral follicles were used as a model to examine the potential mechanism(s) mediating GLYT1 suppression before ovulation is triggered. Using these models, I found that GLYT1 activity remains suppressed within preovulatory antral follicles in contrast to the spontaneous GLYT1 activation that occurred in isolated denuded oocytes or within COCs. Recently, the mechanism mediating oocyte maintenance of prophase I arrest within the ovarian follicle was elucidated and was shown to depend on the release of Natriuretic Peptide Precursor C (NPPC) from mural granulosa cells (MGCs) into follicular fluid which binds to NPR2 guanylate cyclases on cumulus cells stimulating the production of cyclic GMP (cGMP) within these cells. Diffusion of cGMP from cumulus granulosa cells to the oocyte via gap junctions is required to maintain meiotic arrest. Although GLYT1 activation and meiotic resumption are both suppressed in antral follicles prior to the ovulatory trigger and these two processes occur simultaneously following oocyte isolation from ovaries, I have shown here that GLYT1 suppression within the preovulatory antral follicle is mediated by a mechanism distinct from the gap junction-dependent NPPC-cGMP pathway controlling meiotic arrest. I also showed for the first time a direct requirement for meiotic arrest of both gap junctions between granulosa cells (composed of connexin-43) and between the inner layer of cumulus granulosa cells and the oocyte (composed of connexin-37). Since I showed that GLYT1 was suppressed in isolated antral follicles but not COCs, I hypothesized that MGCs are required to maintain low GLYT1 activity in antral follicles. I showed here that MGCs isolated from preovulatory antral follicles were sufficient to maintain GLYT1 suppression in co-cultured COCs, but not denuded oocytes. Furthermore, I found that GLYT1 activity was suppressed in COCs cultured in conditioned medium from MGC cultures. Thus, GLYT1 activity appears to be suppressed within the ovary prior to the ovulatory LH-stimulus likely by an unidentified inhibitory signal within the ovarian follicle originating from the MGCs and propagated by a gap junction-independent mechanism involving multiple cell types in the follicle.

Despite the major reproductive advances in the livestock industry, prenatal embryonic loss is still one of the major issues that causes substantial economic loss. While there are many tests available to determine pregnancy soon after maternal recognition of pregnancy, most of the prenatal losses are undetectable because it occurs before then. Based on previous research we hypothesized that increased plasma volume around the time of estrus will increase the survivability of the embryo at early stages of gestation. However, our findings indicate that hematocrit levels are not a consistent measurement in determining successful pregnancies.