The most-discussed pairing symmetry in Sr₂RuO₄ is chiral p-wave, pₓ ± p[sub]y, whose degeneracy is protected by the lattice symmetry. When the lattice symmetry is lowered by the application of a symmetry-breaking field, the degeneracy can be lifted, potentially leading to a splitting of the superconducting transition. To lift the degeneracy, the symmetry breaking field used in this study is uniaxial stress. Uniaxial stress generated by a piezo-electric actuator can continuously tune the electronic structure and in situ lower the tetragonal symmetry in Sr₂RuO₄. Previous studies of magnetic susceptibility and resistivity under uniaxial stress have revealed that there is a strong peak in T[sub]c when the stress is applied along the a-axis of Sr₂RuO₄. In addition, it has been proposed that the peak in T[sub]c coincides with a van Hove singularity in the band structure, and measurements of Hc₂ at the maximum T[sub]c indicate the possibility of an even parity condensate for Sr₂RuO₄ at the peak in Tc. In this thesis, the heat capacity approach is used to study the thermodynamic behavior of Sr₂RuO₄ under uniaxial stress applied along the crystallographic a-axis of Sr₂RuO₄. The first thermodynamic evidence for the peak in T[sub]c is obtained, proving that is a bulk property. However, the experimental data show no clear evidence for splitting of the superconducting transition; only one phase transition can be identified within the experimental resolution. The results impose strong constraints on the existence of a second phase transition, i.e. the size of the second heat capacity jump would be small or the second T[sub]c would have to be very close to the first transition. In addition to these results, I will present heat capacity data from the normal state of Sr₂RuO₄. The experimental results indicate that there is an enhancement of specific heat at the peak in T[sub]c, consistent with the existence of the van Hove singularity. The possibility of even parity superconductivity at the maximum T[sub]c has also been investigated. However, the heat capacity measurements are shown to be relatively insensitive to such a change, so it has not been possible to obtain strong and unambiguous evidence for whether it takes place or not.

Previous multi-strain mathematical models have elucidated that the degree of cross-protective responses between similar strains, acting as a form of immune selection, generates different behavioural states of the pathogen population. This thesis explores these multi-strain dynamic states, to examine their robustness and stability in the face of pathogenic intrinsic phenotypic variation, and the extrinsic force of immune selection. This is achieved in two main ways: Chapter 2 introduces phenotypic variation in pathogen transmissibility, testing the robustness of a stable pathogen population to the emergence of an introduced strain of higher transmission potential; and Chapter 3 introduces a new model with a possibility of immunity to both strain-specific and cross-strain (conserved) determinants, to investigate how heterogeneity in the specificity of a host immune response alters the pathogen population structure. A final investigation in Chapter 4 develops a method of reverse-pattern oriented modelling using a machine learning algorithm to determine which intrinsic properties of the pathogen, and their combinations, lead to particular disease-like population patterns. This research offers novel techniques to complement previous and ongoing work on multi-strain modelling, with direct applications to a range of infectious agents such as Plasmodium falciparum, influenza A, and rotavirus, but also with a wider potential for other multi-strain systems.

GaN is a monocrystalline material that can be grown using metallo-organic chemical vapour deposition (MOCVD), and has desirable mechanical and semiconducting properties for operating as a sensor. It has a Young’s modulus of 250 to 350 GPa, which shows little decrease with respect to temperature beyond 400°C. GaN also exhibits piezoelectric and piezoresistive effects, meaning that it will generate a charge and its electrical resistance will change when the material is strained respectively. In this PhD, GaN has been used as the base material for pressure sensors that potentially can be used in excess of 400°C and at a pressure in excess of 50 bar (5 MPa), with potential applications in aerospace and oil exploration. The pressure sensor is a circular diaphragm created from a GaN/sapphire wafer, and was designed and tested in order to determine if GaN can act as a sensing material in these environments. In addition to the diaphragm sensor, GaN templates that can potentially be used for sensors were grown using an epitaxial layer overgrowth (ELOG) method. These sensors are potentially more mechanically robust than similar templates etched out of GaN/sapphire wafers because they will have less inbuilt strain due to lower dislocation densities. It was possible to release beams and cantilevers from GaN ELOG templates. Mechanical probe tests were undertaken on these devices to see if they were fully released and robust. GaN single crystal growth requires a substrate material, such as (111) silicon or (0001) sapphire, meaning that the thermal properties of the substrate are important for a device operating in excess of 400°C. GaN high electron mobility transistors are heat sensitive, experiencing a decrease in current between the drain and source terminals as the temperature increases. Therefore a GaN-based sensor needs a substrate with the highest possible thermal conductivity to act as a heat sink, which means removing as much heat as possible from the GaN sensor. Diamond has superior thermal conductivity to both sapphire and silicon, so a novel silicon/polycrystalline diamond composite substrate has been developed as a potential GaN substrate. Polycrystalline diamond (PD) can be grown on 4 inch diameter wafers using hot filament chemical vapour deposition (CVD), on (111) silicon (Si) from which single crystal GaN epitaxy can also be grown. In order for the (111) Si/PD composite substrates to be useful heat sinks, the Si layer needs to be less than 2 m. PD was initially grown on 525 to 625 m thick Si wafers that required thinning to 2 m. Achieving this Si layer thickness is difficult due to the presence of tensile stress in the Si caused by a mismatch in the coefficients of thermal expansion (CTEs) between Si and PD. This stress causes the wafer to bow significantly and has been modelled using ANSYS FE software. The models show that the bow of the wafer increases when it is thinned, which will eventually cause the Si layer to delaminate at the Si/PD interface due to poor adhesion and a build up for shear stress. When the Si layer is mechanically thinned, the Si layer can crack due to clamping. The experimental wafer bow and micro-Raman measurements validate the model for when the silicon layer is thicker than 100 m and these results show that an alternative processing route is required.

Orientador: José Geraldo Trani Brandão / Banca: Celso Pinto Morais Pereira / Banca: Marcio Augusto Martin / Resumo: O objetivo deste trabalho foi estudar a distribuição das cargas no sistema cadeira plataforma de força (C-PF) e verificar se há correlação entre as forças medidas no assento e encosto, na postura sentada adequada. Participaram 38 voluntários, classificados pelo biótipo (32 mulheres e 6 homens): idade média de 43,92 anos, estatura média de 1,60 m e peso corporal médio de 65,10 kgf. Uma cadeira, com células de carga nas partes anterior e posterior do assento e no encosto, e uma plataforma de força mediram a distribuição do peso corporal. Estabeleceram-se várias correlações entre as variáveis (peso corporal, altura, idade, e índice de massa corporal) e as cargas medidas e entre as próprias forças adquiridas. Uma das correlações determinou uma relação entre a força total no assento e a força medida no encosto. A distribuição do peso corporal observada foi: 20,04% na plataforma de força; 45,33% e 30,43%, nas partes anterior e posterior do assento, respectivamente; e 4,20% no encosto. Não houve diferenças estatísticas significativas na comparação das médias dos valores da distribuição do peso corporal tanto entre os sexos como entre os biótipos. Porém, como há diferenças na forma corporal de acordo com os sexos e com os biótipos, houve certa diferença nos valores das forças medidas, no sistema C-PF. / Abstract: The aim of this study was to study the load distribution in chair-force plate system (CFP) and to verify if there is correlation between measured seat and backrest forces in the adequate sitting posture. 38 volunteers participated of the study, classifieds according to physical types (32 female and 6 male): mean age of 43,92 years old, mean height of 1,60 m and mean body weight of 65,10 kgf. An instrumented office chair with load cells in the anterior and posterior portions of the seat and backrest and a force plate were used to measure the forces and body weight distribution in C-FP system. This study was established many correlations among some variables (body weight, height, age and body mass index) and the measured loads and among the acquired forces. One of these correlations determined a relation among total force measured on seat and acquired force on lumbar backrest. The body weight distribution observed in the C-FP system was: 20,04% in the force plate, 45,33% and 30,43% in the anterior and posterior portions of the seat respectively, and 4,20% in the backrest. There were no statistics significant differences in comparison of values weight distribution averages as between gender as between physical patterns. But, there are some differences in the body shape according to gender and physical patterns, it there was some difference in the values of acquired forces in the C-FP system. / Mestre

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. / Microfiche copy available in Archives and Barker. / Bibliography: p.80-81. / M.S.

Orientador: Aparecido Antonio Camacho / Resumo: A cardiomiopatia arritmogênica do ventrículo direito (CAVD) é uma doença de origem genética, muito prevalente em cães da raça Boxer. Histologicamente ocorre atrofia dos cardiomiócitos do ventrículo direito (VD) e consequente infiltração fibroadiposa, levando ao aparecimento de arritmias ventriculares. Mesmo sendo as alterações miocárdicas microscópicas em sua maioria, estudos recentes têm identificado disfunção contrátil do ventrículo direito, mesmo em estágios iniciais da doença em humanos, tanto por técnicas convencionais de ecocardiografia quanto por técnicas mais avançadas, como no caso do speckle tracking. Por isso, o objetivo deste estudo foi avaliar se há disfunção miocárdica de VD detectável pela ecocardiografia convencional e pela técnica de speckle tracking bidimensional em cães da raça Boxer portadores da CAVD. Para tanto, utilizou-se cães da raça Boxer com idade superior a quatro anos, distribuídos em dois grupos de acordo com o resultado da avaliação Holter (GC: < 50 EVs/24h, n=11 e GD: > 100 EVs/24h, n=11). Os animais foram submetidos a ecocardiografia e avaliou-se diâmetro e comprimento interno do VD em sístole e diástole, encurtamento fracional da área do VD (FAC), excursão sistólica do plano anular da tricúspide (TAPSE), velocidade miocárdica sistólica do ânulo lateral da tricúspide derivada do Doppler tecidual (S’) e deformação (strain) e taxa de deformação (strain rate) longitudinal global da parede livre do VD, derivados da análise por speckle tracking. As... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic disease with a high prevalence in Boxer dogs. Histologically, right ventricle (RV) cardiomyocytes’ atrophy occurs, and thus fibrofatty infiltration, triggering ventricular arrhythmias. Although the myocardial changes are mostly microscopic, recent studies in human beings have identified right ventricular systolic dysfunction even in the early stages of ARVC, both by conventional echocardiographic techniques and advanced methods, such as speckle tracking. Therefore, the aim of this study was to investigate if RV myocardial dysfunction is present in Boxers affected by ARVC, evaluated by conventional echocardiography and bidimensional speckle tracking technique. For this purpose, Boxers older than four years were recruited, and based on 24-hour Holter recording were divided in groups: GC:< 50 VPC/24h (n=11), or GD: > 100 VPC/24h (n=11). The following echocardiographic parameters were analyzed: RV internal dimension during systole and diastole; RV fractional area change (FAC); tricuspid annular plane systolic excursion (TAPSE); myocardial systolic velocity of lateral tricuspid annulus (S’), and global longitudinal strain and strain rate. Groups were compared by Student’ t-test or Mann-Whitney test according distribution, and correlation between conventional and speckle tracking echocardiographic variables, as well as number and severity of the ventricular arrhythmias were accomplished by the Pearson test, assumin... (Complete abstract click electronic access below) / Mestre

Given the current United States prison population of 1.5 million persons, many states have begun to examine how to effectively reduce correctional expenditures, considering in 2011 healthcare related prison costs increased to approximately eight billion (The Pew Charitable Trusts, 2014). Recent research attributes much of this increase to the prevalence of disease and aging within the prison population (Williams et al., 2012; Dumont et al., 2012; Gallagher, 2001; Ahalt et al., 2013). Alternatively, little attention has been devoted to measuring the disparity in health among minority male inmates or the effects of identifying more cost effective health initiatives that address negative health outcomes. With incarceration and health expenditures rates steadily increasing within the United States, studies have highlighted the positive correlation between incarceration and the costs of inmate health, as well as the implications associated with physical illness and its overarching effects on the performance of correctional health care. This study represents an attempt at bridging the gap between preventative health care and criminal justice efforts within the literature in its examination of the demographics, history of incarceration, chronic illness, and current medical conditions of minority male inmates within the state correctional facilities.

Thesis advisor: Marcie Pitt-Catsouphes / The majority of family caregivers of older adults are also working for pay, and many experience work-family role conflict in managing both work and caregiving responsibilities. Work-family role conflict is associated with poorer psychological and physical health, which interferes with their ability to provide optimal care. Informed by role theory, this dissertation uses a randomized national sample of caregivers of older adults (N=465) to address the relationships between workplace characteristics, workplace flexibility, work-family role conflict, and caregiver stress. While much research has explored the work-family interface, few studies have investigated the workplace characteristics and work-family role conflict exclusively among caregivers of older adults. Additionally, the few studies exploring the relationship between workplace flexibility and stress among caregivers of older adults have yielded inconsistent findings. Results indicate that workplace characteristics associated with work-family role conflict among caregivers of older adults include supervisor support, work overload, work hours, and perceptions of a family-supportive work environment. A significant interaction effect between caregiving frequency (weekly vs. intermittent) indicates that while workplace flexibility is associated with decreased work-family conflict among those providing care intermittently, this association is not found for those providing care on a regular, weekly basis. A second set of analyses limited to regular, weekly caregivers (N=211) finds that work-family role conflict mediates the relationship between workplace flexibility and caregiver stress. This suggests that workplace flexibility may only benefit caregivers when work-family conflict is mitigated or reduced. Workplace flexibility is not associated with stress among caregivers in fair or poor health; caregivers struggling with their own health issues may need additional supports to manage work and family demands. These findings can inform the efforts of policymakers and practitioners working to promote the well-being of family caregivers of older adults. / Thesis (PhD) — Boston College, 2012. / Submitted to: Boston College. Graduate School of Social Work. / Discipline: Social Work.

Agnew's (1985, 1992) General Strain Theory (GST) proposed that strain, the presence of negative events in one's life, is related to an individual's level of delinquent behavior. In particular, strains elicit a negative emotional response (most notably anger), creating a pressure within the individual to react or cope. Additionally, GST suggests that individuals who lack more conventional means to cope with negative life stressors will turn to delinquent coping mechanisms, such as retaliatory or escape-avoidance behaviors, to reduce the stress. The primary aim of this work is to test whether a proposed pro-social coping mechanism, cognitive coping (Agnew 1992, 2001, 2006), influences the strain-delinquency relationship; particularly whether the ability to cognitively cope reduces the use of deviant coping mechanisms. Utilizing data from the base year of the Educational Longitudinal Study (ELS: 2002), this analysis will test whether encountering negative stimuli within the school setting is positively related to students' levels of delinquency. Further, it examines whether cognitive/problem-solving ability has a moderating effect on this relationship. Analysis indicate that when faced with similar levels of strain, individuals with higher cognitive coping abilities are less likely to resort to delinquent coping mechanisms. Arming students with tools to cognitively reinterpret the strains they encounter may lessen the occurrence of delinquent behaviors exhibited in schools (Pearlin 1989; Agnew 2006). Expanding knowledge of what factors negatively influence students, causing them to demonstrate delinquent behaviors in school, and avenues for handling these stressors may have widespread policy and curriculum implications.

The purposes of this study were twofold: (1) to compare rates of delinquency between Mexican American and European American adolescents, and (2) to test the application of a model of delinquency designed to be especially relevant to Mexican lll American adolescents. The study is one of the first attempts to advance knowledge about delinquency among Mexican American adolescents through the development and test of a comprehensive model of delinquency. The model constructed as part of this study-labeled the psychosocial strain model-was unique in that it integrated variables from different theoretical perspectives and its construction was guided by knowledge of cultural and demographic characteristics of Mexican Americans. The study used data from the National Longitudinal Study of Adolescent Health (Add Health), a large and nationally representative sample of adolescents. Analyses indicated that Mexican American adolescents engaged in a disproportionate amount of delinquency. Mexican American adolescents also tended to engage in delinquency at a greater and more serious level than European American adolescents. Results of path analysis used to test the psychosocial strain model revealed that the model explained a statistically significant amount of the variance in delinquency for both males and females. However, not all paths in the model were statistically significant. In addition, the results revealed important gender differences in the applicability of the model. Implications of the study findings and future research directions are discussed.