A presente pesquisa for desenvolvida junto a pacientes hipertensos cadastrados em um Programa de Exercício Aeróbio de um Centro de Saúde do Município de Toluca - México, tendo por objetivo caracterizá-los de acordo com as variáveis do Modelo de Campo de Saúde de Lalonde: biologia humana, meio ambiente, estilo de vida e organização dos serviços de saúde e, analisar o sentir e o pensar destes pacientes sobre sua doença e os cuidados com a mesma. Participaram da pesquisa quarenta e oito pacientes, cujos dados foram obtido em duas fases; primeiramente obteve-se os dados referentes aos quatro elementos do Modelo de Campo de Saúde de Lalonde em seguida, por meio de cinco questões orientadoras foi possível identificar a experiência dos hipertensos com a doença, enfocando o pensar e o sentir destes pacientes, desde o diagnóstico até as mudanças e cuidados impostos pela doença; após a obtenção dos valores da PA, os pacientes, foram classificados em dois grupos: aqueles com PA controlada e aqueles de PA não controlada, de acordo com as recomendações do JNC-7 (2006). Entre os pacientes do grupo de PA controlada 77,08% eram mulheres: 54,16% tinham idade superior a 60 anos; 81,25% estavam com a PA controlada; 27,08% apresentavam sobrepeso e 68,75% possuíam RCQ maior que 90; 45,83% não sabiam indicar antecedentes familiares para a doença; 20,83% indicaram ser hipertensos há mais de dez anos; 72,91% faziam tratamento para a hipertensão arterial, 43,73% indicaram conhecer os valores de PA; 39,59% eram viúvos; 52,08% procediam do meio urbano; 68,75% possuíam nível de escolaridade baixo; 54,16% ocupavam-se dos afazeres domésticos; 70,83% indicaram realizar exercício físico, sendo a caminhada indicada por 66,67% deles; 75,0% não fumavam e 68,75% não consumiam bebida alcoólica; 66,67% indicaram apresentar estresse, sendo este mais freqüente em função de problemas familiares e no lar; 72,91% indicam fazer em média três refeições diárias e consumir alimentos com pouco sal (68,75%); 68,75% indicaram usar os serviços de saúde do sistema público, sendo que 54,16% indicaram procurar o serviço somente quando não se sentissem bem. Em relação ao que pensavam sobre sua doença e o cuidado, pode-se identificar que os hipertensos percebem como necessária a mudança de comportamento a partir da descoberta da doença, embora o início da doença não tenha gerado nenhuma mudança significativa. Os resultados deste estudo são importantes para o universo dos serviços de saúde do México, uma vez que demanda a necessidade de aprofundar estudos que gerem novos conhecimentos que possam contribuir para a melhoria do cuidado ao hipertenso. / This study was developed with hypertensive patients registered in an Aerobic Exercise Program in a Health Care Center in the city of Toluca-Mexico. The study objective is to characterize these individuals according to the Lalonde\'s Health Field Model variables: human biology, environment, life style, and health service organization. The study also aimed to analyze these patients\' feelings and considerations regarding their illness and their care towards it. Forty-eight patients took part in the study. Patient data was obtained in two phases: first, the data regarding the four Lalonde\'s Health Field Model elements were obtained, and, then, using five guiding questions, it was possible to identify the hypertensive patients\' experience with the illness, focusing on their thoughts and feelings from the moment of diagnosis to the changes imposed by the illness. After obtaining the patients\' blood pressure (BP) values, they were classified in two groups, according to JNC-7 (2006) recommendations: those with BP under control, and those with uncontrolled BP. Among patients in the controlled BP group, 77.08% were women, 54.16% were aged above 60 years, 81.25% did not have the BP under control, 27.08% were overweight, and 68.75% had a waist-hip ration (WHR) above 90. Among the hypertensive patients, 45.83% were unable to report any family history for the illness, 20.83% reported being hypertensive for over 10 years, 72.91% were under hypertension treatment, 43.73% reported knowing their BP values, 39.59% were widowed, 52.08% originated from the urban environment, 68.75% had a low educational level, 54.16% performed household chores, 70.83% reported doing physical exercises, with 66.67% reporting walking regularly, 75.0% are non-smokers, 68.75% do not drink alcoholic beverages, 66.67% reported having stress, which is rather often due to family problems, 72.91% reported eating at least three meals a day and eating foods with littlesalt (68.75%), 68,75% indicated using the public system\'s health care service, of which54.16% reported seeking the service only when they did not feel well. Regarding what the patients considerations about the illness and health care, is was possible to identify that they perceived that the change in behavior as something necessary for the change in behavior from as of the moment the illness is identified, regardless if the onset has not yet caused any significant change. The study results are important for the universe of health services in Mexico, since the requires the need for more profound studies that would generate new knowledge that could enhance the care offered to hypertensive individuals.

abstract: Miniaturization of microdevices comes at the cost of increased circuit complexity and operating current densities. At high current densities, the resulting electron wind imparts a large momentum to metal ions triggering electromigration which leads to degradation of interconnects and solder, ultimately resulting in circuit failure. Although electromigration-induced defects in electronic materials can manifest in several forms, the formation of voids is a common occurrence. This research aims at understanding the morphological evolution of voids under electromigration by formulating a diffuse interface approach that accounts for anisotropic mobility in the metallic interconnect. Based on an extensive parametric study, this study reports the conditions under which pancaking of voids or the novel void ‘swimming’ regimes are observed. Finally, inferences are drawn to formulate strategies using which the reliability of interconnects can be improved. / Dissertation/Thesis / Masters Thesis Materials Science and Engineering 2020

Many daily activities require the temporary maintenance and manipulation of information in working memory. A hallmark of this system is its limited capacity—research suggests that adults can actively maintain only about 3–4 items at once. A central question in working memory research is the source of such capacity limits. One approach to this question is to study the developmental origins of working memory capacity. Developmental research on working memory has documented a general increase in capacity throughout childhood and into adulthood. There have been few investigations, however, into the mechanisms behind these developmental changes, and proposals that have been put forth do not specify the processes underlying changes in capacity. One particularly puzzling finding that remains to be explained is an apparent decrease in visual working memory capacity over development, from an adult-like capacity of 3–4 items at 10 months to 1.5 items at 5 years. One probable source of this developmental discrepancy is that these two capacity estimates were derived from different tasks: preferential looking in infancy and change detection in later childhood. Although these tasks differ in many respects, existing theoretical explanations of the processes underlying performance in these tasks are underspecified, making it difficult to identify specify the origin of the regression in capacity over development. To investigate the developmental discrepancy across tasks, I developed a unified model to capture how capacity-limits arise in preferential looking and change detection. I used this model to generate three specific behavioral predictions: 1) in preferential looking, children and adults should show higher capacity estimates than infants; 2) capacity estimates should be higher in preferential looking than in change detection when tested in the same individuals; and 3) although capacity estimates differ, performance should be correlated across tasks because both rely on the same underlying working memory system. In addition, I proposed a fourth prediction regarding the unified model: developmental changes in both tasks should be captured by a specific developmental mechanism, the Spatial Precision Hypothesis. Results from three experiments and model simulations confirmed all four predictions, providing strong support for a new Dynamic Field Theory of visual working memory.

We introduce a continuous modeling approach which combines elastic response of the trabecular bone structure with the concentration of signaling molecules within the bone and a mechanism for concentration dependent local bone formation and resorption. In an abstract setting bone can be considered as a shape changing structure. For similar problems in materials science phase field approximations have been established as an efficient computational tool. We adapt such an approach for trabecular bone remodeling. It allows for a smooth representation of the trabecular bone structure and drastically reduces computational costs if compared with traditional micro finite element approaches. We demonstrate the advantage of the approach within a minimal model. We quantitatively compare the results with established micro finite element approaches on simple geometries and consider the bone morphology within a bone segment obtained from micro-CT data of a sheep vertebra with realistic parameters.

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第17924号 / 情博第506号 / 新制||情||89(附属図書館) / 30744 / 京都大学大学院情報学研究科数理工学専攻 / (主査)教授 梅野 健, 教授 中村 佳正, 教授 船越 満明 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19991号 / 工博第4235号 / 新制||工||1655(附属図書館) / 33087 / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 北村 隆行, 教授 田畑 修, 教授 鈴木 基史 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The diffuse-interface phase-field model is a powerful method to simulate and predict mesoscale microstructure evolution in materials using fundamental properties of thermodynamics and kinetics. The objective of this dissertation is to develop phase-field model for simulation and prediction of interdiffusion behavior and evolution of microstructure in multiphase binary and ternary systems under composition and/or temperature gradients. Simulations were carried out with emphasis on multicomponent diffusional interactions in single-phase system, and microstructure evolution in multiphase systems using thermodynamics and kinetics of real systems such as Ni-Al and Ni-Cr-Al. In addition, selected experimental studies were carried out to examine interdiffusion and microstructure evolution in Ni-Cr-Al and Fe-Ni-Al alloys at 1000°C. Based on Onsager’s formalism, a phase-field model was developed for the first time to simulate the diffusion process under an applied temperature gradient (i.e., thermotransport) in single- and two-phase binary alloys. Development of concentration profiles with uphill diffusion and the occurrence of zeroflux planes were studied in single-phase diffusion couples using a regular solution model for a hypothetical ternary system. Zero-flux plane for a component was observed to develop for diffusion couples at the composition that corresponds to the activity of that component in one of the terminal alloys. Morphological evolution of interphase boundary in solid-to-solid two-phase diffusion couples (fcc-γ vs. B2-β) was examined in Ni-Cr-Al system with actual thermodynamic data and concentration dependent chemical mobility. With the instability introduced as a small initial compositional fluctuation at the interphase boundary, the evolution of the interface morphology was found to vary largely as a function of terminal alloys and related composition-dependent chemical mobility. In a binary Ni-Al system, multiphase diffusion couples of fcc-γ vs. L12-γ′, γ vs. γ+γ′ and γ+γ′ vs. γ+γ′ were simulated with alloys of varying compositions and volume fractions of second phase (i.e., γ′). Chemical mobility as a function of composition was employed in the study with constant gradient energy coefficient, and their effects on the final interdiffusion microstructure was examined. Interdiffusion microstructure was characterized by the type of boundaries formed, i.e. Type 0, Type I, and Type II boundaries, following various experimental observations in literature and thermodynamic considerations. Volume fraction profiles of alloy phases present in the diffusion couples were measured to quantitatively analyze the formation or dissolution of phases across the boundaries. Kinetics of dissolution of γ′ phase was found to be a function of interdiffusion coefficients that can vary with composition and temperature. The evolution of interdiffusion microstructures in ternary Ni-Cr-Al solid-to-solid diffusion couples containing fcc-γ and γ+β (fcc+B2) alloys was studied using a 2D phase-field model. Alloys of varying compositions and volume fractions of the second phase (β) were used to simulate the dissolution kinetics of the β phase. Semi-implicit Fourier-spectral method was used to solve the governing equations with chemical mobility as a function of compositions. The simulation results showed that the rate of dissolution of the β phase (i.e., recession of β+γ twophase region) was dependent on the composition of the single-phase γ alloy and the volume fraction of the β phase in the two-phase alloy of the couple. Higher Cr and Al content in the γ alloy and higher volume fraction of β in the γ+β alloy lower the rate of dissolution. Simulated results were found to be in good agreement with the experimental observations in ternary Ni-CrAl solid-to-solid diffusion couples containing γ and γ+β alloys. For the first time, a phase-field model was developed to simulate the diffusion process under an applied temperature gradient (i.e., thermotransport) in multiphase binary alloys. Starting from the phenomenological description of Onsager’s formalism, the field kinetic equations are derived and applied to single-phase and two-phase binary system. Simulation results show that a concentration gradient develops due to preferential movement of atoms towards the cold and hot end of an initially homogeneous single-phase binary alloy subjected to a temperature gradient. The temperature gradient causes the redistribution of both constituents and phases in the two-phase binary alloy. The direction of movement of elements depends on their atomic mobility and heat of transport values.

No description available.

The continual research and development of nickel-based superalloys is driven by the global demand to improve efficiency and reduce emissions in the aerospace and power generation industries. Integrated Computational Material Engineering (ICME) is a valuable tool for reducing the cost, time, and resources necessary for the development and optimization of the mechanical properties of materials. In this work, an ICME approach for understanding the microstructure development and optimizing the mechanical properties in nickel-based superalloys is employed. Most nickel-based superalloys are precipitate strengthened by either the γ’ phase, γ” phase, or both. Therefore, understanding the precipitation kinetics and morphological evolution of these phases is critical for evaluating their hardening effects during heat treatment and degradation of the microstructure during high temperature service. To this end, a phase-field model has been developed to analyze the nucleation, growth and coarsening kinetics during isothermal and non-isothermal aging conditions. Utilizing the phase-field model, the γ” phase microstructure development and its coherency strengthening effect in Inconel 625 is studied. A novel multistage aging strategy to optimize the γ” phase strengthening effect and reduce aging times for Inconel 625 is proposed. Secondly, the coarsening kinetic and microstructure development of γ’ strengthening phase in nickel-based superalloys is studied, with the goal of understanding the effect of elastic inhomogeneity on the microstructure evolution at high volume fractions of the γ’ phase. The result shows deviation of the coarsening kinetics from the classical Lifshitz-Slyozov-Wagner (LSW) due to the effect of elastic inhomogeneity, highlighting the need for incorporating elastic energy into coarsening theories.

In this study, dynamic crack propagation in brittle materials has been studied using a regularized phase field approach.The phase field model used has been validated using specific experimental results of a dynamic in-plane fracture. The crack branching phenomena and existence of a limiting crack tip velocity has been validated using a mode I simulation set-up. A parametric study has also been performed so as to normalize the various numerical parameters that affect the velocity at the crack tip. Following the validation of the phase field model a stochastic analysis of a PBX microstructure has been performed. The microstructure has a high HMX volume fraction of 79\%. The energetic material is HMX and the binder used is Sylgard. Artificial defects are introduced in the system using phase field cracks. The analysis uses a finite element framework that accounts for various thermal-mechanical processes like deformation, heat generation, conduction, fracture and frictional heating at the crack surfaces. The effect on the temperature and damage field due to varying parameters like loading velocities and critical energy release rates is studied. Critical hotspot formation due to localized frictional heating is also studied. A concept of dirty binder is introduced to increase the grain volume fraction of the energetic in the composite. This amounts to a homogenized binder that accounts for the influence of the subsume particles that do not contribute to fracture but affect material properties of the binder.