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No description available.

Approximately 20% of congestive heart failure (CHF) patients are readmitted within 30 days of hospital discharge, a rate which may be affected by in-hospital and post-discharge care. Reducing this rate is important to hospitals, both to improve outcomes and to avoid reductions in Medicare reimbursement. Assessing outcomes within a short post-discharge window best measures the impact of the care, planning, and followup of that admission; but most research on the effects of changes in CHF care has measured outcomes over periods longer than 30 days, adding the unpredictable long-term course of CHF to the factors affecting the outcome. As well, almost no studies to date have included the appreciable effects of CHF comorbidities in their analyses. This study addresses these needs by measuring rates of 30-day all-cause readmission, and by adjusting for comorbidities and demographic factors in our analysis. We hypothesize that an improved CHF care protocol including both in-hospital and post-discharge components will reduce the risk of readmission, and may alter the rate of change of that risk. We have analyzed as an interrupted time series data on 2764 discharges of CHF patients from a hospital that implemented such a change to assess the effect of the new protocol on the readmission risk and on the trend in that risk, comparing outcomes in the 22 months preceding introduction of the new protocol to those in the first 31 months of full implementation. Using multiple logistic regression, we have tested for an association between the new protocol and both the unadjusted risk of readmission, and that risk in a model including comorbidities and demographic factors as covariates. Neither model found a statistically significant association between introduction of the protocol and log-odds of readmission (unadjusted p = 0.847, adjusted p = 0.755) or between introduction of the protocol and change in risk of readmission over time (unadjusted p = 0.437, adjusted p = 0.313). These results, in comparison with other published results, can clarify what changes to care protocols have been shown to be effective. Further, post hoc power analysis of this study can inform study design for further research.

The current study focuses on improving and testing the CTF thermalhydraulics computer code. CTF is a thermalhydraulic code used for subchannel analysis of nuclear power reactors developed as part of the US DOE CASL program and distributed by North Carolina State University. Subchannel analyses are used to predict the local fuel temperatures and coolant conditions inside a complex nuclear fuel assembly. Such calculations are used to improve designs of nuclear fuel, improve operating margins, or perform safety analysis. An important part of the code development process is the verification and validation for its intended use. In this work validation activities are performed using the RISO experiments are modeled in CTF for adiabatic and diabatic cases in annular flow regimes and a limited set of tests in CANDU geometries. The CTF predictions significantly overpredicted the pressure drop for cases involving annular flow conditions. Depending on the application, such overprediction can result in significant errors in the computation of fuel element dryout and other figures of merit. For example, an analysis using fixed pressure boundary conditions CTF predicts much lower subchannel flows and hence fuel element temperatures may be overestimated. On the other hand, for a scenario with mass flux and inlet pressure as boundary conditions, the impact of pressure drop discrepancies on dryout predictions may be lower. Therefore, there is a particular focus in this thesis on the two-phase pressure drop models and the RISO experiment specifically, since the RISO tests involve a range of annular flow conditions which is prototypical of many CANDU accident analysis conditions. In addition to the RISO experiments, 28-element CANDU full scale rod bundle experiments are modeled in CTF for single-phase and two-phase flow conditions. Cases are modeled for crept and uncrept conditions with different bearing pad heights i.e., 1.17 mm and 1.35mm. Pressure drop predictions are compared with the experimental results where single-phase comparisons are in good agreement while an overprediction of ~25% is observed for two-phase conditions. The effect of bearing pads on the subchannel local parameters, like mass flow rate, are also studied. Furthermore, the effect of turbulent mixing rate on subchannel enthalpy distribution in the bundle and CHF in different subchannels is also analyzed. Based on the comparison to the RISO and CANDU 28 element test databases, the overprediction of pressure drop in the annular flow regime needs improvement in the current version of CTF. This overprediction of the frictional pressure drop results from either wall drag or interfacial shear stress phenomena. In this study, it is demonstrated that the issue occurs mostly as a result of interfacial friction factor modelling this work examines several alternative approaches. The results show the Ju’s and Sun’s interfacial friction factor better predicts the results among all the other six correlations implemented in CTF. The major impediment in further testing of CTF is that it lacks the capability to simulate R-134a fluids. Given there is a large database of R-134a two-phase tests, another aspect of this thesis is to extend CTF for application and validation using refrigerants. The current CTF version only supports fluid properties for water and FLiBe salts. By adding R-134a fluid properties the testing and validation range of CTF is broadened for different experiments performed using R-134a fluids. CHF experiments are modeled in CTF and results are compared with experimental data. For local conditions correlation, 2006 water LUT are used to predict CHF and DNBR. The fluid-to-fluid scaling method is applied in CTF when using CTF with R-134a fluid properties for CHF and DNBR predictions to account for the difference in fluid properties between R-134a and the CHF look-up table. / Thesis / Master of Applied Science (MASc) / COBRA-TF (CTF) is a thermalhydraulic code, based on the historical code COBRA-TF, used for subchannel analysis of nuclear power reactors. Subchannel analysis can be used to predict the local fuel temperatures and coolant conditions inside a complex nuclear fuel assembly. CTF is a transient code that simultaneously solves conservation equations for mass, momentum, and energy for the three coolant phases present, i.e. vapor, continuous liquid, and entrained liquid droplet phases. The scope of the current study includes 1) testing the code for conditions relevant to CANDU accident analysis, 2) refinement of the models that are used in two-phase interfacial friction calculations, and 3) inclusion of alternate fluid properties. The testing of CTF is performed with different experimental databases covering CANDU thermalhydraulic conditions. The refinement is done by improving the pressure drop prediction in the annular flow regime by using different interfacial friction factor correlations from earlier studies in the literature. The current CTF version includes water and liquid salt properties (FLiBe) for coolant fluids. Freon (R-134a) fluid properties have been added in CTF in order to broaden the testing range of CTF for different experimental database using R-134a as working fluid.

Made available in DSpace on 2016-04-27T18:15:43Z (GMT). No. of bitstreams: 1 Jailton Aparecido Rodrigues.pdf: 3116283 bytes, checksum: 4260ef91c350721989553adad70faf3e (MD5) Previous issue date: 2013-10-21 / The purpose of this research was the Barueri-Santana de Parnaíba (São Paulo State) Alphaville, the first Closed Horizontal Condominium (CHF, in Portuguese) in Brazil. Alphaville was the theme for studying concepts related to spatial segregation to better understand the urban restructuring. This research also is addressed to school teachers and students and teachers of undergraduate courses in Geography to contribute to debate on teaching of discipline. This work was divided into two sections: the first was a review of theoretical literature on the subject; the second involved practical activities for elementary school students on the theme of CHF as an aid in understanding some fundamental concepts of Geography and concepts related to socio-spatial inequality, closely related to the subject / O objeto de estudo desta pesquisa foi o Alphaville de Barueri-Santana de Parnaíba (SP), primeiro Condomínio Horizontal Fechado (CHF) do país. O Alphaville foi o tema para estudar conceitos relacionados à segregação socioespacial para compreender melhor a reestruturação urbana. Esta pesquisa também se dirigiu a professores da educação básica e a alunos e professores dos cursos de licenciatura em Geografia para contribuir com o debate sobre o ensino da Disciplina. A obra dividiu-se em duas seções: a primeira que foi uma revisão bibliográfica teórica sobre o tema; a segunda envolveu atividades práticas para alunos do ensino básico sob o tema dos CHF como auxíliona compreensão de alguns conceitos fundamentais de Geografiae conceitosrelacionados à desigualdade socioespacial, intimamente ligadosao tema

Chronic Obstructive Pulmonary Disease (COPD) and Congestive Heart Failure (CHF) are conditions that represent significant and ongoing medical costs, including frequent emergency department (ED) visits, hospitalizations, work absences, and disability. This retrospective cross-sectional study, examined the effects of the frequent ED visits due to COPD and CHF on the beneficiaries of Medicare and Medicaid in Maryland. The goal was to identify the factors that led these patients to visit the ED, the impact of these visits on Medicare utilization and costs across Maryland, and preventative intervention strategies to control this population's costs of care. Secondary data were analyzed from 2010-2012 using the Administrative Claims Data in Chronic Condition Warehouse (CCW). The results for the first research question revealed that an increase in the number of primary care physicians was correlated with a decrease in ED visits; thus, persons living in areas with higher PCPs also had lower ED visits therefore the first null hypothesis was rejected (Ï?2 = 3.85, p=.05) . The results for the second research question revealed that ED visits had no significant relationship with death in a given year; thus, patients may be diverted to less expensive care sites to minimize cost and ED overcrowding, therefore the second null hypothesis was not rejected (Ï?2 = 0, p=.98). In both cases, the confounding variables of gender, age, and race had significant effects upon the relationship. Health Professionals and policy makers may use the findings to develop strategies to increase supply of PCPs, adapt patient centered interventions and modify existing chronic disease care strategies to minimize or prevent lifestyle and environmental factors that affect chronic disease outcomes. Such improvements could contribute to positive social change by eliminating or reducing the overcrowding that occurs in emergency departments in Maryland and other states.

No description available.

Cette thèse est motivée par le besoin de compléter les connaissances actuelles des phénomènes ayant lieu lors d’un renvoi d’eau dans un lit de débris radioactifs, opération appelée « renoyage » et qui intervient dans une séquence d’accident grave où un cœur de réacteur nucléaire est dégradé suite à une perte prolongée de refroidissement primaire. Notre étude, de nature expérimentale, vise à mieux caractériser la crise d’ébullition en convection forcée, dans un milieu poreux chauffant. Le cœur du dispositif expérimental est un milieu poreux modèle quasibidimensionnel, composé de 276 cylindres disposés entre deux plaques de céramique distantes de 3 mm, dont l’une, transparente, permet de visualiser les écoulements. Les cylindres, de 2 mm de diamètre, sont des sondes thermo-résistives qui ont une double fonction : elles sont utilisées comme éléments chauffants et comme capteurs de température. Une boucle fluide permet de contrôler le débit d’injection de liquide dans la section test, la température d’injection ainsi que la pression. La section test est placée verticalement, le liquide est injecté par le bas à une température proche de la saturation. Dans une première série d’expériences, la puissance thermique dissipée globalement par un ensemble de cylindres chauffants est augmentée de façon progressive jusqu’à atteindre l’assèchement d’une zone du milieu poreux. Les résultats montrent deux types de phénoménologies dans le déclenchement de la crise d’ébullition. Pour des débits d’injection faibles (densités de flux massique de l’ordre de 4 kg.m^-2.s^-1 maximum), l’atteinte de la puissance d’assèchement se traduit par un lent recul du front diphasique jusqu’à sa stabilisation en haut de la zone chauffée ; en aval de la zone chauffée, l’écoulement est monophasique vapeur. Pour des débits d’injection plus élevés, la crise d’ébullition apparaît autour d’un des éléments chauffants, conduisant à une ébullition en film localisée, tandis qu’un écoulement diphasique liquide-vapeur continue de parcourir l’aval de la section test. Les visualisations de ces expériences permettent d’identifier qualitativement la structure des écoulements. D’autres expériences consistent à mesurer le flux critique local autour d’un cylindre choisi, pour différentes configurations d’écoulements. Le débit d’injection est fixé. Une puissance de chauffe est imposée à une ligne horizontale de cylindres en amont du cylindre choisi. Les résultats montrent que le flux critique sur ce cylindre diminue en fonction de la puissance délivrée à la ligne chauffée. La distance du cylindre étudié à la ligne chauffée semble avoir peu d’influence sur le flux critique. Des visualisations expérimentales sont utilisées pour caractériser l’écoulement diphasique en aval de la ligne chauffée, dans le but de mettre en relation le flux critique local avec des paramètres hydrodynamiques (saturations, vitesses des phases). Les images obtenues sont difficiles à exploiter. Afin de calibrer les paramètres des algorithmes de traitement d’images, nous avons reproduit une cellule d’essai de géométrie identique à l’originale, mais où l’on injecte du gaz par une ligne de cylindres en amont de la section test dans une configuration d’écoulement diphasique isotherme. Dans ce dispositif, le débit d’injection de gaz est contrôlé et mesuré. Les visualisations obtenues servent alors de références auxquelles sont comparées les visualisations d’ébullition convective. / This work is motivated by the need to better understand the phenomena occurring while some water is injected into a heated porous debris bed. This reflooding operation is a part of the planned mitigation procedure used during a Loss Of Coolant Accident (LOCA) that may occur into a nuclear power plant and results into a severe core damage. Our experimental study aims to characterize the boiling crisis that can happen in a boiling flow taking place within a heatgenerating model porous medium. The test section is a two-dimensional model porous medium, composed of an array of 276 cylinders placed between two ceramic plates spaced from one another by 3 mm, one of which is transparent and allows visualizations of the flow. The 2 mm diameter cylinders are Pt100 resistance temperature detectors that perform a dual function: they act as heating elements (heated by Joule effect) and are also used as temperature probes. A fluid loop allows controlling the liquid injection flow rate, its inlet temperature as well as its pressure. The test section is held vertically, the liquid injected from bottom at a temperature close to the saturation temperature. In a first series of experiments, the thermal power applied to a bundle of heating cylinders is progressively increased until a dry zone is detected in the porous medium. Two kinds of phenomenology are observed during these “dryout experiments”. First, at low liquid injection rate (4 kg.m^-2.s^-1 maximum mass flux), reaching the dryout power results into a liquid front receding down to the upper limit of the heated zone, while downstream the heated zone, the porous medium is vapour-saturated. Second, at higher flow rate, the boiling crisis happens at the surface of a single heating element, resulting in a local film boiling, whereas a two-phase flow still go through the whole test section. High-speed visualizations allow characterizing the flow regimes. Other experiments focus on determining the local critical heat flux on a given cylinder, for different upstream flow configurations. The inlet liquid flow rate is fixed. A thermal power is uniformly applied to a line of heating cylinders, upstream the cylinder under study. Results show that the local critical heat flux decreases as the power applied to the heated line increases. The distance from the cylinder under study to the heated line seems not to have a significant effect on the critical heat flux. Visualizations are used to characterize the two-phase flow upstream the heated line, aiming at expressing the critical heat flux as a function of the hydrodynamic parameters (saturations, phase velocities). The image analysis is particularly challenging. In order to calibrate the image processing parameters, we use a second model porous medium with the same geometry as the heat generating one, but where an isothermal two-phase flow is obtained by injecting gas into the liquid flow rather than generated by boiling. The gas injection flow rate is controlled and measured. Isothermal two-phase flow visualizations provide a reference case and are compared to flow boiling visualizations.

End-stage conditions such as chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD) have shown some of the most dramatic increases in mortality in the developed world over the past 40 years. Both are therefore leading causes of morbidity and mortality worldwide and should be considered as a major economic and social burden that is both substantial and increasing. In these conditions, exercise therapy should play an integral part in maintaining the patient’s maximal level of independence and functioning, as well as slowing or possibly even stopping the progression of the condition. In this context the main objectives of these doctoral theses are: a. Proving the safety of different exercise modalities. b. Identifying the most effective exercise interventions in regards to clinical parameters. c. Proving the feasibility of outpatient rehabilitation programmes for these high risk populations. This work, therefore, combines three studies looking into the effects of non-pharmaceutical interventions – predominantly different exercise regimes in the two major conditions in the mortality statistics of CHF and COPD - both with a very poor prognosis. In conclusion it can be said that the results and experience of all three studies demonstrate the safe feasibility of different outpatient exercise interventions and suggest specific positive adaptations in patients with heart failure and COPD which also led to a lower hospitalisation rate. There are clear hints that the therapy spectrum could be supplemented significantly by specific training interventions. The financial implications for any health care system are also highly relevant.