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Uma das etapas mais críticas no processo de conformação de uma peça cerâmica é a etapa de secagem. Nela podem aparecer defeitos como trincas e empenamentos na peça. Uma forma de minimizar esses defeitos é diminuir a quantidade de água utilizada na formação do corpo cerâmico. No entanto esta ação interfere diretamente na etapa de conformação. Este trabalho tem como objetivo avaliar o comportamento mecânico de peças cerâmicas à verde, para que se possa entender a interação de misturas argila-ar-água, e como o corpo cerâmico úmido se comporta mediante a adição de pó de rocha e surfactante. Para isso foram realizados tanto ensaios de compressão uniaxial quanto de fluência e relaxação. Através das curvas tensão vs. deformação geradas no ensaio de compressão foi possível avaliar a variação do comportamento plástico da argila mediante a variação do teor de umidade e da introdução de pó de rocha. Foram produzidas curvas de trabalhabilidade através do produto das tensões limites de escoamento e das deformações máximas. Os ensaios mostraram que o pó de rocha foi capaz de reduzir a umidade de trabalhabilidade máxima de 18,0% para 13,7%. A variação das densidades de empacotamento do corpo verde em função da umidade de conformação se correlaciona diretamente com o comportamento à compressão, especificamente com a tensão limite de escoamento. Isso tornou possível quantificar a coesão dos corpos cerâmicos produzidos. A adição de pó de rocha na argila diminuiu a coesão do corpo cerâmico verde. Foi possível identificar a existência de diferentes estados de hidratação/saturação do corpo verde: o estado pendular, funicular com porosidade aberta, funicular com porosidade fechada e capilar. Os ensaios de fluência e relaxação mostraram que a argila apresenta um comportamento viscoelástico, independentemente do teor de água do corpo verde. Também foi mostrado que o uso de 1, 5% em massa de surfactante em relação a massa de argila pode reduzir o consumo de água de processamento sem afetar seu comportamento mecânico, pois é capaz de fazer com que uma argila com 18,3% de umidade flua da mesma forma que uma argila com aproximadamente 24,5% de umidade. / Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2016-08-29T13:36:45Z No. of bitstreams: 1 Dissertacao Licia da Silva Alves Schiavo.pdf: 4296423 bytes, checksum: 240b028f046bdd959b5e54aaeee6ae63 (MD5) / Made available in DSpace on 2016-08-29T13:36:45Z (GMT). No. of bitstreams: 1 Dissertacao Licia da Silva Alves Schiavo.pdf: 4296423 bytes, checksum: 240b028f046bdd959b5e54aaeee6ae63 (MD5) Previous issue date: 2016-08-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES. / Drying is one of the most critical forming steps in the ceramic tile production. Usually defects such as cracks and surface distortion are produced in this processing step. One way to minimize these defects is to reduce the amount of water used to shape the ceramic body. However this water reduction directly interferes in the forming process. This work aims to evaluate the mechanical behavior of ceramic green bodies in order to understand the interactions of clay-air-water mixtures, and how it behaves when rock powder and surfactant are added. For that, uniaxial compression and creep and relaxation tests were performed. They allowed, through the stress-strain curve, to assess the clay plastic response to the variation of moisture contents and rock powder addition. Workability curves were produced by the product of the yield stress and maximum deformation. The tests showed that the rock powder was able to reduce moisture of maximum workability of 18.0% to 13.7%. The green body packing density variation as a function of the forming moisture directly correlates with its compressive behavior, specifically with the yield stress. It turns possible to quantify the cohesion of the produced ceramic bodies. The addition of rock powder to the clay decreased the cohesion of the ceramic green body. The existence of different green body hydration/saturation states were identified namely the pendulous, funicular with open porosity, funicular with closed porosity and capillary states. Creep and relaxation tests were performed which showed that the clay body has a viscoelastic behavior, i.e. deformation is a function of time, independently of the green body water content. It was also shown that the use of surfactant can reduces the processing water consumption without affecting its mechanical behavior, because it can cause a clay with 18.3% moisture to flow in the same way that a clay with about 24.5% moisture.

Orientador: Li Li Min / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-10T03:39:21Z (GMT). No. of bitstreams: 1 Cannonieri_GiannaCarla_M.pdf: 2892396 bytes, checksum: 985d7c525864a8b128f7d574556ef6b9 (MD5) Previous issue date: 2007 / Resumo: Introdução: O treinamento prolongado de tarefas motoras está associado com a execução automática dos movimentos. A adaptação funcional induzida pelo treinando resulta em uma melhora do desempenho motor. Não se compreende ainda inteiramente se essa adaptação funcional é refletida em mudanças plásticas na estrutura do cérebro. Objetivo: Investigar a presença e o grau de plasticidade cerebral estrutural do cérebro induzida por um treino motor bimanual prolongado em digitadores experientes profissionais. Sujeitos/Métodos: Foram avaliados 17 digitadores profissionais. Através da técnica de Mofometria Baseada em Voxels (VBM), que utiliza imagens de ressonância magnética de alta resolução, correlacionamos o tempo de prática como digitador com o volume de substancia cinzenta cerebral (VSC). Utilizamos as regiões de interesse (ROI) disponibilizadas pela AAL (anatomical automatic labeling) library e o programa MARSBAR para o SPM2. Resultados: Encontramos uma regressão positiva significativa entre VSC e tempo de prática em seis regiões cerebrais: hemisfério cerebelar inferior medial esquerdo, hemisfério cerebelar inferior medial direito, região frontal orbital medial direita, lóbulo paracentral direito e o pólo temporal direito. Discussão: Nosso estudo sugere que a prática prolongada de digitação pode produzir mudanças macroscópicas estruturais no cérebro de adultos saudáveis. Uma atividade motora coordenada, bimanual e seqüencial dos dedos impõe uma demanda neural nas regiões corticais relacionadas à programação e execução da tarefa motora, incluindo a área motora suplementar, córtex pré-frontal e cerebelo. Conclusão: A plasticidade cerebral pode ocorrer am adultos. O treino motor prolongado pode aumentar o VSC em áreas específicas do córtex cerebral e cerebelo, relacionadas à coordenação e planejamento motor, importantes para a execução da atividade de digitação / Abstract: Background: Long-term training of specific motor tasks is associated with automatic execution of movements. Functional adaptation induced by training results in performance improvement. It is not yet fully understood whether functional adaptation is reflected by plasticity changes in brain structure. Objectives: We aimed to investigate the presence and degree of structural brain plasticity induced by long-term bimanual motor activity executed by professional typists. Subjects/Methods: We studied 17 right-handed professional typists. Using voxel-based morphometry (VBM), we correlated duration of practice and gray matter volume. Local regions of interest (ROI) -VBM was applied using predefined 116 previously segmented brain sites (from the anatomical automatic labeling library) and MARSBAR package. Results: We found a significant positive regression between GMV and duration of practice in six regions: left medial inferior cerebellar hemisphere, right medial inferior cerebellar hemisphere, right medial orbital region, right paracentral lobule and the right temporal pole. Discussion: Our study suggests that long-term typewriting practice may yield macroscopic changes in brain structures of healthy adults. Non-mirror sequential bimanual finger activity coordination creates a demand in cortical regions related to the programming of motor task, including the supplementary motor area, prefrontal cortices and cerebellum. Conclusion: Neural plasticity occurs in adult brain. Long-term bimanual training may increase GMV in specific brain areas of cerebral cortex and cerebellum. These regions are related to bimanual motor coordination and planning, which are important for typing / Mestrado / Neurociencias / Mestre em Fisiopatologia Médica

Uma das etapas mais críticas no processo de conformação de uma peça cerâmica é a etapa de secagem. Nela podem aparecer defeitos como trincas e empenamentos na peça. Uma forma de minimizar esses defeitos é diminuir a quantidade de água utilizada na formação do corpo cerâmico. No entanto esta ação interfere diretamente na etapa de conformação. Este trabalho tem como objetivo avaliar o comportamento mecânico de peças cerâmicas à verde, para que se possa entender a interação de misturas argila-ar-água, e como o corpo cerâmico úmido se comporta mediante a adição de pó de rocha e surfactante. Para isso foram realizados tanto ensaios de compressão uniaxial quanto de fluência e relaxação. Através das curvas tensão vs. deformação geradas no ensaio de compressão foi possível avaliar a variação do comportamento plástico da argila mediante a variação do teor de umidade e da introdução de pó de rocha. Foram produzidas curvas de trabalhabilidade através do produto das tensões limites de escoamento e das deformações máximas. Os ensaios mostraram que o pó de rocha foi capaz de reduzir a umidade de trabalhabilidade máxima de 18,0% para 13,7%. A variação das densidades de empacotamento do corpo verde em função da umidade de conformação se correlaciona diretamente com o comportamento à compressão, especificamente com a tensão limite de escoamento. Isso tornou possível quantificar a coesão dos corpos cerâmicos produzidos. A adição de pó de rocha na argila diminuiu a coesão do corpo cerâmico verde. Foi possível identificar a existência de diferentes estados de hidratação/saturação do corpo verde: o estado pendular, funicular com porosidade aberta, funicular com porosidade fechada e capilar. Os ensaios de fluência e relaxação mostraram que a argila apresenta um comportamento viscoelástico, independentemente do teor de água do corpo verde. Também foi mostrado que o uso de 1, 5% em massa de surfactante em relação a massa de argila pode reduzir o consumo de água de processamento sem afetar seu comportamento mecânico, pois é capaz de fazer com que uma argila com 18,3% de umidade flua da mesma forma que uma argila com aproximadamente 24,5% de umidade. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES. / Drying is one of the most critical forming steps in the ceramic tile production. Usually defects such as cracks and surface distortion are produced in this processing step. One way to minimize these defects is to reduce the amount of water used to shape the ceramic body. However this water reduction directly interferes in the forming process. This work aims to evaluate the mechanical behavior of ceramic green bodies in order to understand the interactions of clay-air-water mixtures, and how it behaves when rock powder and surfactant are added. For that, uniaxial compression and creep and relaxation tests were performed. They allowed, through the stress-strain curve, to assess the clay plastic response to the variation of moisture contents and rock powder addition. Workability curves were produced by the product of the yield stress and maximum deformation. The tests showed that the rock powder was able to reduce moisture of maximum workability of 18.0% to 13.7%. The green body packing density variation as a function of the forming moisture directly correlates with its compressive behavior, specifically with the yield stress. It turns possible to quantify the cohesion of the produced ceramic bodies. The addition of rock powder to the clay decreased the cohesion of the ceramic green body. The existence of different green body hydration/saturation states were identified namely the pendulous, funicular with open porosity, funicular with closed porosity and capillary states. Creep and relaxation tests were performed which showed that the clay body has a viscoelastic behavior, i.e. deformation is a function of time, independently of the green body water content. It was also shown that the use of surfactant can reduces the processing water consumption without affecting its mechanical behavior, because it can cause a clay with 18.3% moisture to flow in the same way that a clay with about 24.5% moisture.

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Abstract Plants have evolved various adaptive strategies for balancing the benefits and costs of having a high affinity for resources, plasticity of growth allocation and mycorrhizal symbiosis. The relative growth rates of mycorrhizal and non-mycorrhizal plants were modelled for stable and variable nutrient availability. Mycorrhizal plants had higher growth rates at low and non-mycorrhizal plants at high nutrient availability. Variation in nutrient availability reduced the growth rate of mycorrhizal plants due to a high affinity for nutrients. However, mycorrhizal plants may be able to buffer against external fluctuations and therefore experience less environmental variation than non-mycorrhizal plants. Non-mycorrhizal plants may even benefit from variation. The optimal allocation of growth between shoot and roots depends on the availability of energy and nutrients. The optimisation model predicted that the requirement for phenotypic plasticity of shoot/root allocation is greatest in environments with low resource availability. Plants with a high affinity for resources required more plasticity in order to tolerate variation than plants with a low affinity. The model predicted a trade-off between the ability to deplete resources and the ability to tolerate resource fluctuations. Changes in the availability and ratio of resources lead to changes in the structure and composition of vegetation during primary succession. The field study of the forested phases of the land uplift island Hailuoto showed a successional change in the vegetation from the dominance of bryophytes and deciduous dwarf shrubs to dominance by lichens and evergreen dwarf shrubs. The humus layer became thinner and the availability of nutrients declined, while the C/N ratio of soil organic matter increased during succession indicating a decline in the quality of organic matter. The increased soil respiration rate indicates a successional increase in the energetic costs of decomposing organic matter. Nutrients mediate both direct and indirect trophic interactions. Indirect interactions of nutrient cycling are not explicit in continuous time models. A transformation to a discrete time model was shown to make the indirect interactions explicit as transition probabilities and allowed their dynamic contribution to be evaluated with an elasticity analysis. The importance of indirect interactions was greater in tundra than temperate forest and increased with the rate of nutrient cycling.

Abstract Branches of adult Scots pine (Pinus sylvestris L.) trees were sampled from boreal dry pine forests to study needle longevity, its variation and its relation to other shoot characteristics. The stands studied were located along transects from two smelters and one city, e.g. along gradients of pollution impact. Constant needle age structures were assumed and static life-tables generated. Mean needle longevity was calculated as the sum of the proportions of living needle fascicles on the successive annual shoots. It fully incorporated the information of the static life-tables and was preferred to median or maximum ages because of its significantly lower variation. The first half of the shedding span, the duration of the period when the needle survival gradually dropped from 90 to 50 %, proved to validly reflect the changes in the needle age structure. Needle longevity decreased 15-40 % towards the pollution sources along the transects studied. Near the smelters, needle longevity decreased with the increasing needle Fe, or Fe, Ni and Cu concentration that represented the main constituents of the airborne particle emissions. Near the city, needle longevity decreased with the increasing needle N and P concentrations, annual needle mass and needle mass packing and decreasing needle area packing. In the urban forests, needle Mg, P and K concentrations decreased linearly with the decreasing needle survival from the second to the fourth needle age class. Concentrations in the living needles of the fourth age class stayed over 80 % of the average for all the age classes, though needle survival dropped below 50 %. A decreasing needle Mn concentration was detected towards all the emission sources. Leaching, especially from the soil, as a possible cause was discussed. Needle longevity had the lowest variation among the shoot characteristics, which increases its value as a tool in ecological monitoring. Low plasticity in needle longevity could be an acclimation to the ambient environmental conditions and length of the growing season and to maximise the carbon gain per time. Needle longevity decreased and annual needle mass and leaf mass per area increased upwards in the crowns of mature Scots pines, reflecting the acclimation to irradiance.

Evolution of adaptation requires both generation of novel phenotypic variation and retention of a locally beneficial subset of this variation. Such retention can be facilitated by genetic assimilation, the accumulation of genetic and molecular mechanisms that stabilize induced phenotypes and assume progressively greater control over their reliable production. A particularly strong inference into genetic assimilation as an evolutionary process requires a system where it is possible to directly evaluate the extent to which an induced phenotype is progressively incorporated into preexisting developmental pathways. Evolution of diet-dependent pigmentation in birds-where external carotenoids are coopted into internal metabolism to a variable degree before being integrated with a feather's developmental processes-provides such an opportunity. Here we combine a metabolic network view of carotenoid evolution with detailed empirical study of feather modifications to show that the effect of physical properties of carotenoids on feather structure depends on their metabolic modification, their environmental recurrence, and biochemical redundancy, as predicted by the genetic assimilation hypothesis. Metabolized carotenoids caused less stochastic variation in feather structure and were more closely integrated with feather growth than were dietary carotenoids of the same molecular weight. These patterns were driven by the recurrence of organism-carotenoid associations: commonly used dietary carotenoids and biochemically redundant derived carotenoids caused less stochastic variation in feather structure than did rarely used or biochemically unique compounds. We discuss implications of genetic assimilation processes for the evolutionary diversification of diet-dependent animal coloration.

Damage to motor areas of the brain, caused by stroke, can produce devastating motor deficits, including aberrant control of force. After stroke, reorganization of the brain’s motor system has been identified as one of the fundamental mechanisms involved in recovery of motor control after stroke. Yet, few studies have investigated how force production and modulation are encoded in the brain after stroke and how this relates to motor outcome. Thus, the purpose of this study was to (1) understand how past neuroimaging literature has contributed to establishing common patterns of brain reorganization during both relative and absolute force production after stroke, (2) examine how brain function is reorganized during force production and modulation in individuals with stroke, and (3) relate this task-related reorganization of brain function to the amount of paretic arm use after stroke. In the second chapter, we systematically reviewed all relevant literature examining brain activation during force production after stroke. The following chapters (chapters 3 and 4) applied functional magnetic resonance imaging (fMRI) to examine the neural correlates of force production and modulation after stroke. Chapter 2 supports differences in task-related brain activation dependent on features of stroke, such as severity and chronicity, as well as influence of rehabilitation. In addition, results suggest that activation of common motor areas of the brain during force production can be identified in relation to functional outcome after stroke. Results from the subsequent two chapters (3 and 4), demonstrate that brain function reorganizes in terms of absolute, and not relative force production after stroke. Specifically, stroke participants exhibit greater activation of motor areas than healthy controls when matched for absolute force production. Moreover, there is a relationship between paretic arm usage and brain activation, where stroke participants having less paretic arm use, as measured using wrist accelerometers, exhibit higher brain activation. Results of this thesis suggest that during absolute force production, brain activation may approach near maximal levels in stroke participants at lower forces than healthy controls. Furthermore, this effect may be amplified even further in subjects with less paretic arm usage, as increased activation in motor areas occurs in participants with less arm use after stroke. Ultimately, the results from this thesis will contribute to research relevant to brain reorganization in individuals with stroke and may lead to the development of new, beneficial therapeutic interventions that optimize brain reorganization and improve functional recovery after stroke. / Medicine, Faculty of / Graduate