943 resultados para Kingston


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Background: Excess weight places a significant burden on health. Clinical practice guidelines advise healthcare professionals to provide weight management interventions to patients with overweight and obesity. Chiropractic practice may provide a unique opportunity to deliver weight management interventions to those with overweight and obesity. However, little has been done to address overweight and obesity within the chiropractic profession. Identifying the extent of this evidence-practice gap in chiropractic practice is the first step in addressing this issue. Objectives: This thesis was to assess the clinical practices of weight loss provided by chiropractors. The primary objectives were to 1) determine the prevalence of overweight and obesity in the adult patient population that sought chiropractic care, 2) describe the frequency and distribution of chiropractor directed weight management intervention, 3) identify associations between chiropractor directed weight management interventions and specific patient-level and chiropractor-level variables, and 4) examine the interaction between patient weight and comorbid conditions and whether chiropractors offered weight management interventions. Methods: Data from the Ontario Chiropractic Observational and Analysis Study was used (N = 42 chiropractors, N = 3523 patient encounters). Multilevel logistic regression was performed. Patient-level as well as chiropractor-level variables were investigated and associations with weight management provided by chiropractors were identified. Results: The majority of patients who sought chiropractic were overweight or obese (61.2%). Weight loss was provided to only 5.4% of patients. Chiropractors who graduated between 1995 and 2005 (OR: 0.02, 95% CI: 0.00 - 0.13) or prior to 1995 (OR: 0.08, 95% CI: 0.01 - 0.42) provided weight management significantly less than chiropractors who graduated between 2005 and 2014. No significant interaction was observed between patient adiposity and comorbid conditions with chiropractors directed weight loss. Conclusion: The majority of patients who seek chiropractic care are overweight and obese. Chiropractors are in a unique position to help improve patient health through offering weight management. However, this opportunity has not been fully realized by the chiropractic profession.

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Salmonella are Gram-negative, intracellular food-borne pathogens that cause pregnancy complications. In pregnant mice, Salmonella enterica serovar Typhimurium (S.Tm) infection results in placental bacterial replication, inflammation, necrosis, and fetal loss by unknown mechanisms. Necroptosis, or programmed necrosis mediated by RIPK3 (receptor-interacting protein kinase 3), an inflammatory cell death pathway, is implicated in the pathogenesis of S.Tm in non-pregnant mice. This goal of this thesis was to investigate the role of necroptosis in the pathogenesis of S.Tm infection during mouse pregnancy. I hypothesized that elimination of the key necroptotic cell death protein RIPK3 would decrease placental inflammation and trophoblast cell death, and increase conceptus survival compared to controls. Mice expressing a functional Slc11a1 (encodes the natural resistance-associated macrophage protein 1, NRAMP1) gene with or without RIPK3 function (Ripk3-/-Slc11a1+/+ compared to Slc11a1+/+) were infected with 103 S.Tm by tail vein injection on gestational day (GD) 12. Mice were euthanized on GD 14 (48h post-infection) or GD 15 (72h post-infection) and implantation sites (IS) and maternal serum were harvested for analyses. In nearly all challenged mice (except one outlier), S.Tm were detected in most IS within a litter but there was limited immune cell infiltration, placental damage or cell death in Slc11a1 competent mice regardless of Ripk3 gene deletion. Maternal serum cytokine analyses confirmed lack of maternal immune responses to S.Tm infection. IS amongst the litter of a single dam (Ripk3-/-Slc11a1+/+ at 72h postinfection) displayed heavy but not universal placental S.Tm infection of decidual tissues and spongiotrophoblast, associated with elevated maternal serum pro-inflammatory cytokines. S.Tm infection of the fetal yolk sac (YS) was observed in 54.5% of IS from this dam. YS infection was confirmed in archival samples in mice expressing Ripk3 with intact Slc11a1 and in mice lacking functional Slc11a1. In Slc11a1 incompetent mice, S.Tm were detected in placental labyrinthine trophoblast. Based on the available data, this thesis suggests that Ripk3 and necroptosis have no significant roles in either promotion or prevention of progressive Salmonella infection during mouse pregnancy. It also provides pilot data that NRAMP1 controls placental localization and lethality due to YS infection.

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Background: Excess weight places a significant burden on health. Clinical practice guidelines advise healthcare professionals to provide weight management interventions to patients with overweight and obesity. Chiropractic practice may provide a unique opportunity to deliver weight management interventions to those with overweight and obesity. However, little has been done to address overweight and obesity within the chiropractic profession. Identifying the extent of this evidence-practice gap in chiropractic practice is the first step in addressing this issue. Objectives: This thesis was to assess the clinical practices of weight loss provided by chiropractors. The primary objectives were to 1) determine the prevalence of overweight and obesity in the adult patient population that sought chiropractic care, 2) describe the frequency and distribution of chiropractor directed weight management intervention, 3) identify associations between chiropractor directed weight management interventions and specific patient-level and chiropractor-level variables, and 4) examine the interaction between patient weight and comorbid conditions and whether chiropractors offered weight management interventions. Methods: Data from the Ontario Chiropractic Observational and Analysis Study was used (N = 42 chiropractors, N = 3523 patient encounters). Multilevel logistic regression was performed. Patient-level as well as chiropractor-level variables were investigated and associations with weight management provided by chiropractors were identified. Results: The majority of patients who sought chiropractic were overweight or obese (61.2%). Weight loss was provided to only 5.4% of patients. Chiropractors who graduated between 1995 and 2005 (OR: 0.02, 95% CI: 0.00 - 0.13) or prior to 1995 (OR: 0.08, 95% CI: 0.01 - 0.42) provided weight management significantly less than chiropractors who graduated between 2005 and 2014. No significant interaction was observed between patient adiposity and comorbid conditions with chiropractors directed weight loss. Conclusion: The majority of patients who seek chiropractic care are overweight and obese. Chiropractors are in a unique position to help improve patient health through offering weight management. However, this opportunity has not been fully realized by the chiropractic profession.

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The application of 3D grain-based modelling techniques is investigated in both small and large scale 3DEC models, in order to simulate brittle fracture processes in low-porosity crystalline rock. Mesh dependency in 3D grain-based models (GBMs) is examined through a number of cases to compare Voronoi and tetrahedral grain assemblages. Various methods are used in the generation of tessellations, each with a number of issues and advantages. A number of comparative UCS test simulations capture the distinct failure mechanisms, strength profiles, and progressive damage development using various Voronoi and tetrahedral GBMs. Relative calibration requirements are outlined to generate similar macro-strength and damage profiles for all the models. The results confirmed a number of inherent model behaviors that arise due to mesh dependency. In Voronoi models, inherent tensile failure mechanisms are produced by internal wedging and rotation of Voronoi grains. This results in a combined dependence on frictional and cohesive strength. In tetrahedral models, increased kinematic freedom of grains and an abundance of straight, connected failure pathways causes a preference for shear failure. This results in an inability to develop significant normal stresses causing cohesional strength dependence. In general, Voronoi models require high relative contact tensile strength values, with lower contact stiffness and contact cohesional strength compared to tetrahedral tessellations. Upscaling of 3D GBMs is investigated for both Voronoi and tetrahedral tessellations using a case study from the AECL’s Mine-by-Experiment at the Underground Research Laboratory. An upscaled tetrahedral model was able to reasonably simulate damage development in the roof forming a notch geometry by adjusting the cohesive strength. An upscaled Voronoi model underestimated the damage development in the roof and floor, and overestimated the damage in the side-walls. This was attributed to the discretization resolution limitations.

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Recent developments have made researchers to reconsider Lagrangian measurement techniques as an alternative to their Eulerian counterpart when investigating non-stationary flows. This thesis advances the state-of-the-art of Lagrangian measurement techniques by pursuing three different objectives: (i) developing new Lagrangian measurement techniques for difficult-to-measure, in situ flow environments; (ii) developing new post-processing strategies designed for unstructured Lagrangian data, as well as providing guidelines towards their use; and (iii) presenting the advantages that the Lagrangian framework has over their Eulerian counterpart in various non-stationary flow problems. Towards the first objective, a large-scale particle tracking velocimetry apparatus is designed for atmospheric surface layer measurements. Towards the second objective, two techniques, one for identifying Lagrangian Coherent Structures (LCS) and the other for characterizing entrainment directly from unstructured Lagrangian data, are developed. Finally, towards the third objective, the advantages of Lagrangian-based measurements are showcased in two unsteady flow problems: the atmospheric surface layer, and entrainment in a non-stationary turbulent flow. Through developing new experimental and post-processing strategies for Lagrangian data, and through showcasing the advantages of Lagrangian data in various non-stationary flows, the thesis works to help investigators to more easily adopt Lagrangian-based measurement techniques.

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Sustained drug release systems provide many advantages over traditional delivery methods such as extending the time in which the drug is found to be within an effective concentration within the therapeutic window, which decreases the frequency of administration of the drug, and increases patient compliance. Research using polyacrylamide crosslinked by oligomers containing an aptamer sequence, has demonstrated a pulsatile release over 50 minutes triggered by a 2 mM target adenosine concentration. This thesis aims to build off this concept by designing a system that delivers in a sustained manner when triggered by micromolar target concentrations reflective of disease in vivo, using macromolecular targets. For example, the disease wet age related macular degeneration (wet AMD) is associated with increased concentrations of the protein vascular endothelial growth factor (VEGF-A) – a macromolecule. Patients with wet AMD would benefit from the implantation of devices or microspheres that release drugs in a sustained manner in response to local VEGF concentrations. In this thesis, we hypothesize that the protein lysozyme, used to demonstrate proof-of-concept, could trigger the increased release of drugs from oligomer-crosslinked alginate. The objectives are to (i) demonstrate sustained release from alginate, (ii) design oligomer crosslinked alginate that degrades in response to lysozyme, and then (iii) use these systems to control the release of FITC-dextran with and without lysozyme. A series of control experiments and analyses were used to optimize the crosslinking of alginate by annealed oligomers. The cumulative release of FITC-dextran (MW 20,000) from oligomer crosslinked alginate increased by 3.4 μg when lysozyme (3 μM) was introduced at 48 hours, as opposed to controls which released only 0.2 μg. FITC-loaded alginate microspheres coated by oligomer-crosslinked alginate released 15% more FITC-dextran over 120 hours when placed into 3 μM of lysozyme than without lysozyme. Controls of alginate crosslinked with PEG or control oligomers (without a lysozyme aptamer sequence) had no changes in release with lysozyme. The incorporation of a lysozyme aptamer onto oligomers used to crosslink alginate disks or alginate coatings on microspheres resulted in different diffusion and release of FITC-dextran into PBS with or without lysozyme. This approach could be adapted for the delivery of drugs to diseases with specific protein profiles such as wet AMD.

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In recent years, the 380V DC and 48V DC distribution systems have been extensively studied for the latest data centers. It is widely believed that the 380V DC system is a very promising candidate because of its lower cable cost compared to the 48V DC system. However, previous studies have not adequately addressed the low reliability issue with the 380V DC systems due to large amount of series connected batteries. In this thesis, a quantitative comparison for the two systems has been presented in terms of efficiency, reliability and cost. A new multi-port DC UPS with both high voltage output and low voltage output is proposed. When utility ac is available, it delivers power to the load through its high voltage output and charges the battery through its low voltage output. When utility ac is off, it boosts the low battery voltage and delivers power to the load form the battery. Thus, the advantages of both systems are combined and the disadvantages of them are avoided. High efficiency is also achieved as only one converter is working in either situation. Details about the design and analysis of the new UPS are presented. For the main AC-DC part of the new UPS, a novel bridgeless three-level single-stage AC-DC converter is proposed. It eliminates the auxiliary circuit for balancing the capacitor voltages and the two bridge rectifier diodes in previous topology. Zero voltage switching, high power factor, and low component stresses are achieved with this topology. Compared to previous topologies, the proposed converter has a lower cost, higher reliability, and higher efficiency. The steady state operation of the converter is analyzed and a decoupled model is proposed for the converter. For the battery side converter as a part of the new UPS, a ZVS bidirectional DC-DC converter based on self-sustained oscillation control is proposed. Frequency control is used to ensure the ZVS operation of all four switches and phase shift control is employed to regulate the converter output power. Detailed analysis of the steady state operation and design of the converter are presented. Theoretical, simulation, and experimental results are presented to verify the effectiveness of the proposed concepts.

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The main objective of blasting is to produce optimum fragmentation for downstream processing. Fragmentation is usually considered optimum when the average fragment size is minimum and the fragmentation distribution as uniform as possible. One of the parameters affecting blasting fragmentation is believed to be time delay between holes of the same row. Although one can find a significant number of studies in the literature, which examine the relationship between time delay and fragmentation, their results have been often controversial. The purpose of this work is to increase the level of understanding of how time delay between holes of the same row affects fragmentation. Two series of experiments were conducted for this purpose. The first series involved tests on small scale grout and granite blocks to determine the moment of burden detachment. The instrumentation used for these experiments consisted mainly of strain gauges and piezoelectric sensors. Some experiments were also recorded with a high speed camera. It was concluded that the time of detachment for this specific setup is between 300 and 600 μs. The second series of experiments involved blasting of a 2 meter high granite bench and its purpose was the determination of the hole-to-hole delay that provides optimum fragmentation. The fragmentation results were assessed with image analysis software. Moreover, vibration was measured close to the blast and the experiments were recorded with high speed cameras. The results suggest that fragmentation was optimum when delays between 4 and 6 ms were used for this specific setup. Also, it was found that the moment at which gases first appear to be venting from the face was consistently around 6 ms after detonation.

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Objetivo: determinar los niveles de actividad física (AF) de niños y adolescentes entre 10 y 17 años durante los periodos de recreo escolar en un colegio distrital de Bogotá. Método: estudio de corte transversal en un colegio distrital de la localidad de Puente Aranda en Bogotá. Fueron observados a través del sistema de observación de juego y de actividad en el tiempo libre en jóvenes (SOPLAY) los niveles y tipos de AF de niños y adolescentes en los periodos de recreo durante tres semanas, utilizando una condición de observación diferente para cada semana. Adicionalmente, las condiciones del contexto de las áreas recreo deportivas fueron evaluadas. Resultados: las prevalencias de escolares sedentarios fueron de 52,4 %, 77,3 % y 64,9 % durante la 1ª, 2ª y 3ª semana respectivamente. El sexo femenino fue más sedentario con el masculino (57 %, 82 % y 73 % vs 45 %, 70 % y 54 %) para cada semana observada. Se obtuvieron diferencias significativas (p<0,05) en los niveles de AF de los escolares. Conclusión: niños y adolescentes presentan elevadas prevalencias de sedentarismo siendo las actividades más frecuentes estar sentado, de pie o acostado durante los periodos de recreo. El sexo masculino mostró porcentajes superiores de participación en AF moderadas vigorosas. Las áreas recreo deportivas no contaban con condiciones del contexto relacionadas con disponibilidad de equipamiento para realizar AF ni existencia de actividades organizadas. Son necesarios programas e intervenciones eficaces que promuevan la AF en niños y adolescentes durante el recreo de la jornada escolar.

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¿Qué tienen por decir mujeres excombatientes de grupos insurgentes (guerrillas como las FARC y el EPL) y de las Autodefensas Unidas de Colombia acerca de su proceso de desmovilización y reintegración? Este reportaje busca responder esa pregunta por medio de la historia de vida de Camila, Valentina y Blanca, tres mujeres que pertenecieron a grupos armados ilegales y que ahora luchan por reconstruir su proyecto de vida y le apuestan a la construcción de la paz desde las luchas cotidianas que tiene que afrontar.

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Los eventos adversos (EA) están presentes en todos los niveles de atención en salud y deben ser evaluados de manera integral, tanto en los servicios hospitalarios como en el entorno de la Atención Primaria en Salud (APS). Los EA que se presentan en los servicios hospitalarios, son diferentes a los que se presentan en los servicios de Atención Primaria en Salud (APS) y por ello se debe dar un abordaje diferenciado. La seguridad del paciente debe ser una prioridad para todos los sistemas de salud. Desde esta perspectiva se deben identificar cuáles son las herramientas más adecuadas para el reporte, análisis, intervenciones y acciones de mejora, con las que deben contar los programas de seguridad del paciente y la apropiación de conceptos de gestión de riesgo, facilita la identificación y el manejo institucional de situaciones que ponen en peligro la integridad y la vida de los pacientes.

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El interés de esta monografía es evaluar la relación entre el orden institucional del Estado colombiano y las lógicas del control territorial de los paramilitares sobre el Urabá antioqueño durante el periodo 1997-2007. Se analiza y explica cómo los grupos paramilitares aprovecharon el contexto de debilidad institucional del Urabá antioqueño para consolidar estructuras paraestatales que instrumentalizaron y cooptaron la institucionalidad del Estado con la pretensión de reproducir las condiciones necesarias para su sostenimiento. Así como las consecuencias sobre la Institucionalidad regional a causa de la consolidación de un control político de corte autoritario y clientelista, la obstaculización de la afirmación del monopolio de la violencia estatal, y la protección de un modelo económico particular sustentado en la violencia. Para ello, como parámetros generales se siguen las funciones estatales descritas por Charles Tilly, la descripción de los estados entre estados de Kinsgton y Spears y la teoría de la cooptación del Estado de Jorge Garay.

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Objetivo: Estimar los niveles de actividad física (AF) de escolares de básica primaria durante el recreo, a través del uso del Sistema de Observación de Juego y Tiempo Libre en niños. Metodología: Estudio descriptivo transversal. Cinco instituciones educativas de la localidad de Engativá de Bogotá participaron en el presente estudio. Se contó con una muestra a conveniencia de 2.415 escolares (1.093 niñas y 1.322 niños), los cuales cursaban de 2º a 5º de primaria. Se realizaron 261 observaciones en 87 áreas determinadas. La muestra presentó una confiabilidad del 95%. Resultados: El tiempo de recreo fue de 30 minutos, los niños mostraron mayores porcentajes de AF con respecto a las niñas, sin embargo no se encontraron asociaciones estadísticamente significativas (p=0,506). Las áreas eran totalmente accesibles y utilizables, pero ausentes de actividades organizadas. Se encontró un bajo nivel de AF 9,5% en áreas supervisadas. De los escolares; el 22,5% para niñas, y el 20,6% para niños, tuvieron comportamientos sedentarios durante el recreo. Menos del 15% de los escolares realizaron AF vigorosa en el recreo y un mayor porcentaje 62,8% para niñas vs 64,6% para niños realizaron AF moderada. Conclusión: Los escolares acumularon una cantidad valiosa de AF moderada y vigorosa durante el recreo. Es probable que se aumente el nivel de AF, si el patio de la escuela está equipado y con actividades organizadas. Es esencial que las estrategias específicas se estudien y evalúen para determinar cómo y en qué medida se fomenta la AF entre los escolares.