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Sampson, Elizabeth Lesley. "Longitudinal studies in frontotemporal dementia." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406422.
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Matthews, Cory. "Longitudinal Diet Studies of Arctic Whales." Marine Biological Association of the United Kingdom, 2013. http://hdl.handle.net/1993/30149.
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An animal’s foraging ecology can vary over a range of temporal scales, mirroring seasonal and longer term changes in prey availability, as well as ontogenetic shifts in diet and distribution. Obtaining individual-based, longitudinal diet information through direct observation, however, is logistically challenging for marine mammals that pursue and consume prey underwater, and are often widely distributed. Isotopic profiling along continuously growing tissues like teeth and baleen, which archive dietary inputs at the time of growth in their stable isotope composition, allows for chronological dietary reconstructions over multi-year timespans. This thesis reports longitudinal diet studies of three Arctic whale species, killer whales (Orcinus orca), bowhead whales (Balaena mysticetus) and beluga whales (Delphinapterus leucas), derived from serial isotopic measurements along teeth and baleen. Study objectives varied by species, but general goals were to characterize seasonal, ontogenetic, and/or individual diet variation.
Results revealed similar trophic-level diet, but regional spatial separation, among eastern Canadian Arctic/Northwest Atlantic killer whales. However, isotope and tooth wear differences between two individuals and the rest of the sampled whales suggested potential specialisation on sharks, while the other whales likely had diets comprising marine mammals. Cyclic isotopic variation along Eastern Canada-West Greenland bowhead whale baleen was consistent with year-round foraging, although at a reduced rate during winter. Resting zooplankton could be an important food resource outside of periods of peak productivity, and accessibility likely drives winter habitat selection. Isotopic cycling did not differ between female and male bowheads, or among age classes, indicating similar seasonal foraging patterns despite reported spatial segregation throughout their summer range. Individual beluga whales from three eastern Canadian Arctic populations varied in timing of ontogenetic diet shifts (i.e. weaning age), as well as overall trophic position, which could reflect size-specific energetic requirements and foraging capabilities. Population-specific beluga whale diet trends over a period of several decades likely reflected climate-related expansions of southern forage fish. Collectively, findings of seasonal, ontogenetic, and/or individual diet variation contribute a greater understanding of intrapopulation variation in foraging ecology of these species, and of large-scale structuring of Arctic marine ecosystems.
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McFarland, Martha. "Full day kindergarten : a longitudinal perspective of perceived benefit." Virtual Press, 2007. http://liblink.bsu.edu/uhtbin/catkey/1364937.
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This study was designed to investigate the sustainable academic benefits of a full time kindergarten experience beyond the kindergarten year with additional consideration of the relationship between productive learning behaviors and ongoing academic advantage. The study was conducted across four elementary schools that housed both alternating full day and daily full day kindergarten programs. The initial sample consisted of 321 students enrolled in either daily full day or alternating full day kindergarten during the 2001-2002 school year, which decreased, through attrition, to a total of 198 students enrolled in fourth grade during the 2005-2006 school year. Student academic achievement was measured using a combination of criterion referenced skill assessments, standardized test measures, and a teacher-rated social behavior scale. Hypotheses were tested at the .05 level of significance using chi square analyses, multivariate and univariate analyses of variance, and correlation and regression analyses.The findings indicated that by the end of the kindergarten year, full day kindergarten students outperformed their alternating day peers in both reading and mathematics. However, as measured at the beginning of the second grade year, the academic gains realized during the kindergarten year had dissipated. By the beginning of the fourth grade year, there was no difference in achievement across program types in mathematics, while a significant achievement difference was found in English/language arts, with alternating full day students outperforming their daily full day peers. Further, during the third and fourth grade years, there was a significant interaction between gender and student achievement for the cohort, with significant differences by gender and the combined effect of gender/kindergarten type on social learning behaviors. While the data established a significant, positive relationship between competent social behavior and academic achievement regardless of gender for students from both program types, boys who attended daily full day kindergarten demonstrated significantly less productive social behavior than did boys from the alternating day program and girls from the daily full day program. For those who attended daily full day kindergarten, lower social behavior ratings predicted depressed academic achievement in English/language arts well beyond the kindergarten year.Department of Educational Leadership
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Read, Robert R. "Longitudinal studies relating to training dead time." Monterey, California. Naval Postgraduate School, 2001. http://hdl.handle.net/10945/24461.
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Glowinkowski, S. P. "Managerial stress : A longitudinal study." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373224.
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Roberts, Laura McCoy. "The Long-Term Effects of Bereavement: A Longitudinal Study." Thesis, University of North Texas, 1994. https://digital.library.unt.edu/ark:/67531/metadc278017/.
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The purpose of the present study was to examine the applicability of a model of bereavement to the long-term adjustment to loss. Based on Allen's (1990) model, it was predicted that the variables experienced competence, perceived resources, and the impact of the loss would contribute strongly to overall long-term bereavement adjustment. It was also predicted that time and multiple losses would impact adjustment to loss.
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Zhang, Li, and 张莉. "Preschool experience, school readiness, self-regulation, and academic achievement : a longitudinal study in rural China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/197139.
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Research indicates that preschool experience significantly influences child development and this study examined the influence of preschool learning experiences on children’s school readiness, self-regulation and academic achievement. Participants were 190 children from an impoverished county in Southwest China and their teachers. Classroom observations were conducted and children were assessed in individual and group sessions.
There were three different types of preschool programs (kindergartens, pre-primary classes; Grade 1) available in the county. A total of 18 teaching episodes provided in either the kindergarten or primary schools to 164 children were videotaped and analyzed. Results indicated marked variations in preschool quality and pedagogical practices to support children’s self-regulation across programs. Kindergartens had the best physical environments, the most resources and highly qualified teachers. The teachers provided children with meaningful learning opportunities, adequate instructions, clear structure and predictability, and diversified instructional formats. Pre-primary classes had limited resources and unqualified teachers who emphasized academic learning. Compared to kindergarten teachers, pre-primary class teachers prepared fewer activities and frequently required children to simply sit still and listen. Preschool age children who merely “sat in” Grade 1 classrooms were typically neglected by teachers and only received attention from the teacher when they were disruptive.
Grade 1 children (89 girls) who had attended kindergarten (n = 60), separate pre-primary classes (n = 55), merely “sat in” Grade 1 classes before being formally enrolled in school (n = 54) or had no preschool experience (n = 21) were assessed at the beginning of Grade 1 (Wave 1), at the end of Grade 1 (Wave 2), and at the end of Grade 2 (Wave 3). Their school readiness was assessed in Wave 1. Their self-regulation skills were assessed using the modified Head-Toes-Knees-Shoulders task in Waves 1 and 2, and seven cognitive regulation tests in Wave 3. Their literacy and mathematics achievement was evaluated using curriculum-based tests across the three waves. Results indicated that children with some form of preschool experience outperformed those with none in almost all the three outcomes across the three waves. Children from the kindergarten had better school readiness than the other three groups and better self-regulation than those attending separate pre-primary classes at the start of school. Children attending separate pre-primary classes had significantly better literacy and mathematics than those from the kindergarten at the start of school and literacy at the end of Grade 2. Children “sitting in” Grade 1 classes achieved lower scores than those from the kindergarten and pre-primary classes on almost all child outcome measures. The growth of self-regulation within the first primary school year was significant and Wave 1 behavioral regulation predicted Wave 3 cognitive regulation. School readiness and self-regulation significantly predicted academic achievement in all three waves and school readiness mediated the close relationship between self-regulation and academic achievement. Findings highlight the importance of (i) preschool experience for children from economically disadvantaged families in rural China; and (ii) self-regulation in school preparedness and early academic attainment. They also have implications for scaling up and enhancing the quality of preschool programs.published_or_final_version
Education
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Doctor of Philosophy
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Lu, Libo. "Approximate methods for joint models in longitudinal studies." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/27909.
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Longitudinal studies often contain several statistical issues, suchas longitudinal process and time-to-event process, the associationamong which requires joint modeling strategy.
We firstly review the recent researches on the joint modeling topic. After that, four popular inference methods are introduced for jointly analyzing longitudinal data and time-to-event data based on a combination of typical parametric models. However, some of them may suffer from non-ignorable bias of the estimators. Others may be computationally intensive or even lead to convergence problems.
In this thesis, we propose an approximate likelihood-based simultaneous inference method for jointly modeling longitudinal
process and time-to-event process with covariate measurement errors problem. By linearizing the joint model, we design a strategy for updating the random effects that connect the two processes, and propose two algorithm frameworks for different scenarios of joint likelihood function. Both frameworks approximate the multidimensional integral in the observed-data joint likelihood by analytic expressions, which greatly reduce the computational intensity of the complex joint modeling problem.
We apply this new method to a real dataset along with some available methods. The inference result provided by our new method agrees with those from other popular methods, and makes sensible biological interpretation. We also conduct a simulation study for comparing these methods. Our new method looks promising in terms of estimation precision, as well as computation efficiency, especially when more subjects are given. Conclusions and discussions for future research are listed in the end.
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Koscielniak, S. R. "Longitudinal beam dynamics studies on the ISIS synchrotron." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379845.
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Singleton, Michael David. "Nonlinear Hierarchical Models for Longitudinal Experimental Infection Studies." UKnowledge, 2015. http://uknowledge.uky.edu/epb_etds/7.
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Experimental infection (EI) studies, involving the intentional inoculation of animal or human subjects with an infectious agent under controlled conditions, have a long history in infectious disease research. Longitudinal infection response data often arise in EI studies designed to demonstrate vaccine efficacy, explore disease etiology, pathogenesis and transmission, or understand the host immune response to infection. Viral loads, antibody titers, symptom scores and body temperature are a few of the outcome variables commonly studied. Longitudinal EI data are inherently nonlinear, often with single-peaked response trajectories with a common pre- and post-infection baseline. Such data are frequently analyzed with statistical methods that are inefficient and arguably inappropriate, such as repeated measures analysis of variance (RM-ANOVA). Newer statistical approaches may offer substantial gains in accuracy and precision of parameter estimation and power. We propose an alternative approach to modeling single-peaked, longitudinal EI data that incorporates recent developments in nonlinear hierarchical models and Bayesian statistics. We begin by introducing a nonlinear mixed model (NLMM) for a symmetric infection response variable. We employ a standard NLMM assuming normally distributed errors and a Gaussian mean response function. The parameters of the model correspond directly to biologically meaningful properties of the infection response, including baseline, peak intensity, time to peak and spread. Through Monte Carlo simulation studies we demonstrate that the model outperforms RM-ANOVA on most measures of parameter estimation and power. Next we generalize the symmetric NLMM to allow modeling of variables with asymmetric time course. We implement the asymmetric model as a Bayesian nonlinear hierarchical model (NLHM) and discuss advantages of the Bayesian approach. Two illustrative applications are provided. Finally we consider modeling of viral load. For several reasons, a normal-errors model is not appropriate for viral load. We propose and illustrate a Bayesian NLHM with the individual responses at each time point modeled as a Poisson random variable with the means across time points related through a Tricube mean response function. We conclude with discussion of limitations and open questions, and a brief survey of broader applications of these models.
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Huntley, Selene J. "Longitudinal studies of intramammary infection in suckler ewes." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/57216/.
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Four longitudinal studies were conducted. The first study investigated the longitudinal pattern of udder half somatic cell count (HSCC) and intramammary infection (IMI) in 48 UK suckler ewes over the first 10 weeks of lactation. This was the first study to demonstrate that HSCC of suckler ewes followed a quadratic and cubic relationship with days in lactation over the first 10 weeks of lactation. Udder half somatic cell count was also explained by presence of bacteria. Ewes older than 6 years of age had significantly higher HSCC than younger ewes. The second study investigated the relationships between udder conformation, SCC and lamb weight. Whilst accounting for lamb age and birth weight, significantly lower lamb weight was associated with a ewe SCC of >400,000 cells/ml (-1.7 kg), a traumatic teat lesion (bite, tear or chapping) 2 weeks previously (-1.1 kg), and a ewe body condition score (BCS) of <2.5 before lambing (-1.3kg). Higher HSCCs were observed in ewes with a lower suspended udder, and older ewes in poorer body condition. The findings from this study make an important contribution to the knowledge of the impact of udder health of suckler ewes by demonstrating that udder conformation is associated with IMI and that IMI and teat damage are negatively associated with lamb weight. The third study investigated the effect of dry cow therapy (DCT) on subclinical mastitis in a lowland flock with a low incidence of clinical mastitis by recording HSCC and lamb weights in the following lactation. To the author’s knowledge, there are no published reports of the effect of broad spectrum DCT on subclinical mastitis in suckler ewes in the literature. No significant effect was found between the use of DCT and HSCC or lamb weight in the subsequent lactation. The fourth study was a randomised controlled trial to assess the effect of DCT on clinical mastitis in a suckler flock with a high level of clinical mastitis. Dry cow treatment significantly reduced the incidence of clinical mastitis over one year, with a 70% reduction of clinical mastitis in ewes that received treatment from 6.2% to 1.8%. This was the first field trial to investigate and demonstrate the clinical benefit of the use of a broad spectrum DCT in suckler ewes. These studies have enhanced our knowledge of longitudinal patterns of infection and demonstrated the importance of udder health for optimising production of suckler ewes. Factors to control for when using SCC as a tool to measure intramammary infection were described.
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Gao, Dexiang. "Analysis of clustered longitudinal count data /." Connect to full text via ProQuest. Limited to UCD Anschutz Medical Campus, 2007.
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Thesis (Ph.D. in Analytic Health Sciences, Department of Preventive Medicine and Biometrics) -- University of Colorado Denver, 2007.Typescript. Includes bibliographical references (leaves 75-77). Free to UCD affiliates. Online version available via ProQuest Digital Dissertations;
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Li, Xiaolian, and 李曉蓮. "Brand effects and brand dominance in transitional economies: a longitudinal study on brands in China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31226383.
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何定邦 and Ting-pong Ho. "The young adult outcome of hyperactive children and psychiatric controls: a 12-year follow-up study." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31981562.
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Wong, Andrew Carlton Edward. "Longitudinal studies on tooth replacement in the leopard gecko." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54273.
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The leopard gecko is an emerging reptilian model for the molecular basis of indefinite tooth replacement. Here we characterize the tooth replacement frequency and pattern of tooth loss in the normal adult gecko. We chose to perturb the system of tooth replacement by activating the Wingless signaling pathway (Wnt). Misregulation of Wnt leads to supernumerary teeth in mice and humans. We hypothesized by activating Wnt signaling with LiCl, tooth replacement frequency would increase. To measure the rate of tooth loss and replacement, weekly dental wax bites of 3 leopard geckos were taken over a 35-week period. The present/absent tooth positions were recorded. During the experimental period, the palate was injected bilaterally with NaCl (control) and then with LiCl. The geckos were to be biological replicates. Symmetry was analyzed with parametric tests (repeated measures ANOVA, Tukey’s post-hoc), while time for emergence and total absent teeth per week were analyzed with non-parametric tests (Kruskal-Wallis ANOVA, Mann-Whitney U post-hoc and Bonferroni Correction). The average replacement frequency was 6-7 weeks and posterior-to-anterior waves of replacement were formed. Right to left symmetry between individual tooth positions was high (>80%) when all teeth were included but dropped to 50% when only absent teeth were included. Two animals were followed for 14 weeks after NaCl injections and 14 weeks after LiCl injections. NaCl did not affect the replacement dentition but LiCl delayed and disrupted the pattern of replacement. The phenotypes were more severe for one animal including 1) increased time before emergence, 2) increased total number of absent teeth per week, 3) a greater effect on anterior teeth and 4) disruption of symmetry. The most affected period began 7 weeks post LiCl injection. At the end of the study, in vitro CT scans of both animals revealed normal patterns of unerupted teeth however there was bone loss in one animal. Gecko tooth replacement is rapid enough to be useful for longitudinal studies. Between-animal variation is high when studying individual teeth therefore each animal should be used as its own control. Future work includes increasing the biological replicates and detailed molecular studies to confirm the effect of LiCl.Dentistry, Faculty of
Graduate
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Falster, Kathleen Anne National Centre in HIV Epidemiology & Clinical Research Faculty of Medicine UNSW. "Longitudinal studies of HIV outcomes in the Asia-Pacific." Awarded by:University of New South Wales. National Centre in HIV Epidemiology & Clinical Research, 2009. http://handle.unsw.edu.au/1959.4/44599.
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This thesis presents a series of longitudinal studies of HIV-outcomes in Australia and the Asia-Pacific region since highly active antiretroviral therapy (HAART) became available. The primary source of data is the Australian HIV Observational Database (AHOD). AHOD is an observational cohort of more than 2000 patients with HIV recruited via hospitals, sexual health centres and general medical practices specialising in HIV medicine. Chapter five of this thesis addresses whether there were any differences in antiretroviral therapy use and virological response that might explain the different trends in new HIV diagnosis rates between state jurisdictions in Australia in recent years. Analysis of data from cohort studies of primary and chronic HIV infection, gay community surveys and national prescription data suggest that, for the most part, antiretroviral therapy use and virological response were similar in each jurisdiction during the first decade of HAART. Chapter six describes the prevalence of, and risk factors for, an incomplete immune response despite sustained viral suppression in patients on HAART in AHOD. The clinical relevance of this phenomenon is also explored in terms of AIDS and death during follow-up. Of those with sustained viral suppression, one third of patients did not achieve immune recovery greater than 350 cells/??l in the 12-24 months after starting their first or second HAART regimen, and this was associated with a lower CD4 cell count at baseline. Chapter seven describes cause-specific mortality in patients with HIV in the Asia-Pacific region. Immunodeficiency was associated with non-AIDS and AIDS mortality, and the risk of non-AIDS mortality increased with age. Less conclusive was the relationship between country-income level and risk of death from AIDS or non-AIDS causes because of the relatively high proportion of unknown causes of death in low-income settings. Chapter eight presents hospitalisation rates, risk factors and associated diagnoses in patients with HIV in Australia. Older, sicker individuals, as indicated by markers of advanced immunodeficiency or frequency of hospitalisation, were at greater risk of hospitalisation and death in the AHOD cohort. Despite effective antiretroviral therapy, patients with HIV are currently hospitalised at higher rates than people of similar age in the general population.
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Fong, Daniel Y. T. "State space models and filtering methods in longitudinal studies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq22201.pdf.
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Neville, Richard John. "Micromagnetic and structural studies of CoPtCr longitudinal recording media." Thesis, University of Glasgow, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337504.
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Phillips, Michael. "Identifying response to therapy in longitudinal PET imaging studies." Thesis, King's College London (University of London), 2014. http://kclpure.kcl.ac.uk/portal/en/theses/identifying-response-to-therapy-in-longitudinal-pet-imaging-studies(97fbec41-f7fd-4d39-89b5-3d806159cf1e).html.
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¹⁸F-FDG PET can predict response using both qualitative and quantitative measures. PET Therapy Response Assessor (PETTRA) software was developed to allow users to view and analyse pre- and post- therapy images and compute quantitative measures for predicting response to therapy. Additionally, registration methodology was developed to register pre- and post- therapy PET/CT images. The methodology registers pre- and post- therapy PET/CT scans by registering CT scans using customised rigid and non-rigid registration performed by the Image Registration Toolkit (IRTK). Registration success was assessed using qualitative visual analysis and quantitative landmark analysis on a cohort of 20 lymphoma patients. Landmark analysis results found average misalignment on IRTK of ~10mm for rigid registration and ~6.5mm for non-rigid registration, in comparison with ~40mm with no registration applied. The effect of both rigid and non-rigid registration on transformed images was assessed. While rigid registration transformation caused minimal changes on intensity and tumour volume (<2%), non-rigid transformations caused changes of 11% and 21% respectively. PETTRA software was used to analyse quantitative parameters in 14 patients with mesothelioma and 85 patients with diffuse large B-cell lymphoma (DLBCL). For the 14 patients with mesothelioma, a range of parameters were used to assess response including SUVmax, SUVpeak, tumour volume (TV), total lesion glycolysis (TLG) and intensity volume histogram (IVH) parameters. TV and TLG were obtained using 13 fixed and 9 adapative threshold segmentation methods. Pre-and post- therapy SUVmax, SUVpeak, TV and TLG all showed promise in predicting survival. The comparison between TV and TLG obtained using different segmentation methods was negligible. For the 85 patients with DLBCL, SUVmax, TV and TLG struggled to predict response in patients according to ROC curves.
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Pinal, Fernández Iago. "Transcriptome profiling and longitudinal cohort studies of myositis subsets." Doctoral thesis, Universitat Oberta de Catalunya, 2020. http://hdl.handle.net/10803/673293.
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Inflammatory myopathies are a heterogeneous family of rare autoimmune diseases affecting multiple organs and systems, including the skin, the lungs, the muscles and/or the joints. Accurately defining their pathogenesis and classifying them correctly are key for understanding and managing these diseases. In this doctoral thesis we explored specific autoantibody-defined myositis subsets and quantitatively compared the ability of autoantibodies to the 2017 EULAR/ACR classification standard to predict the phenotype of patients with myositis. We also performed RNA sequencing on 119 muscle biopsies of patients with different types of myositis and 20 controls. We studied the differential expression, performed pathway analysis and developed exploratory machine learning pipelines to define the specific expression profiles and pathogenic pathways in each disease subgroup. With these studies we determined that the autoantibodies outperform current clinical criteria to predict the phenotype of myositis patients and discovered unique expression profiles in the muscle tissue of patients with different types of myositis.Las miopatías inflamatorias son una familia heterogénea de enfermedades autoinmunes raras que afectan a múltiples órganos y sistemas, incluidos los músculos, la piel, los pulmones y/o las articulaciones. Definir con precisión su patogenia y clasificarlas correctamente es clave para comprender y manejar estas enfermedades. En esta tesis doctoral exploramos subconjuntos específicos de miositis definidas por autoanticuerpos y comparamos cuantitativamente la capacidad de los autoanticuerpos con la clasificación EULAR/ACR de 2017 para predecir el fenotipo de pacientes con miositis. Además, realizamos la secuenciación de ARN en 119 biopsias musculares de pacientes con diferentes tipos de miositis y 20 controles. Estudiamos la expresión diferencial, realizamos análisis de vías y desarrollamos procesos de aprendizaje automático exploratorios para definir los perfiles de expresión específicos y las vías patogénicas en cada subgrupo de enfermedades. Con estos estudios determinamos que los autoanticuerpos superan los criterios clínicos actuales para predecir el fenotipo de los pacientes con miositis y descubrimos perfiles de expresión únicos en el tejido muscular de pacientes con diferentes tipos de miositis.
Les miopaties inflamatòries són una família heterogènia de malalties autoimmunes rares que afecten múltiples òrgans i sistemes, inclosos els músculs, la pell, els pulmons i/o les articulacions. Definir-ne amb precisió la patogènia i classificar-les correctament és clau per comprendre i manejar aquestes malalties. En aquesta tesi doctoral explorem subconjunts específics de miositis definides per autoanticossos i comparem quantitativament la capacitat dels autoanticossos amb la classificació EULAR/ACR de 2017 per predir el fenotip de pacients amb miositis. A més, realitzem la seqüenciació d'ARN en 119 biòpsies musculars de pacients amb diferents tipus de miositis i 20 controls. Estudiem l'expressió diferencial, fem anàlisis de vies i desenvolupem processos d'aprenentatge automàtic exploratoris per definir els perfils específics d'expressió i les vies patogèniques a cada subgrup de malalties. Amb aquests estudis determinem que els autoanticossos superen els criteris clínics actuals per predir el fenotip dels pacients amb miositis i descobrim perfils d'expressió únics al teixit muscular de pacients amb diferents tipus de miositis.
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Azmi, Shazli. "Longitudinal studies in metabolic neuropathies : development of imaging biomarkers." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/longitudinal-studies-in-metabolic-neuropathies-development-of-imaging-biomarkers(6913e957-0e81-4af8-a544-f943f0105b8c).html.
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Corneal Confocal Microscopy (CCM) is a non-invasive imaging technique to quantify small nerve fibre structure in patients with diabetic somatic and autonomic neuropathy and increasingly other metabolic, hereditary, toxic and inflammatory peripheral neuropathies. This thesis establishes that CCM is indeed a powerful imaging technique which can identify early small fibre degeneration and regeneration in relation to the clinical phenotype of subjects with obesity, impaired glucose tolerance and Type1/2 diabetes. We demonstrate a precise relationship between small fibre neuropathy and erectile dysfunction in subjects with Type 1 diabetes. We also demonstrate the utility of CCM in demonstrating relative protection from small fibre damage in Type 1 patients with extreme duration diabetes (medallists) at baseline and over 3 years and repair in patients undergoing simultaneous pancreas and kidney transplantation. This thesis provides further evidence for the utility of CCM as a marker of early small fibre neuropathy by demonstrating nerve damage in subjects with morbid obesity with and without diabetes and explore the mechanisms underlying nerve damage at baseline and repair following bariatric surgery. We also show that CCM can track dynamic changes in small fibre degeneration and regeneration in subjects with impaired glucose tolerance in relation to change in glucose tolerance status and following continuous subcutaneous insulin infusion in subjects with Type 1 diabetes.
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Cheung, Ka-yan, and 張嘉茵. "Multilevel modeling for the analysis of longitudinal periodontal data." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46605496.
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Mariella, Anne M. "Longitudinal patterns of depressive symptoms in midlife women /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/7257.
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Rhodes, Anthony Ryan. "Attrition in Longitudinal Studies Using Older Adults: A Meta-Analysis." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4938/.
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Longitudinal methods have become an improved and essential means of measuring intra-individual change over time. Yet one of the greatest and most hazardous drawbacks studying participants over multiple sessions can be the loss of participants over time. This study attempts to illuminate the problem of attrition in longitudinal research by estimating the mean effect sizes for participant loss across 57 studies published in 13 prestigious journals which regularly use older participants. Results estimate overall attrition to be around 34% of the original sample. The subsequent break down of attrition into its subtypes yield mean effect sizes for attrition due to Refusal (8%), Loss of contact (10%), Illness (6%), and Death (14%) in studies sampling from adults 50 years or older. Analyses were then conducted via meta-analytic one-way ANOVA and weighted regression to identify possible moderators of overall attrition and their four subtypes.
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Zheng, Yingye. "Semiparametric methods for longitudinal diagnostic accuracy /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/9580.
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Williams, Oscar M. "Black youth in vocational education: further education, labor market, civic and political participation." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39902.
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Geasler, Margie J. Swindlehurst. "Marital equity among dual-career couples: a longitudinal perspective." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39897.
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Longitudinal data from 113 dual-career couples are used to explore the relationship between perceptions of marital equity and well-being and distress in marital, professional, and parental roles, how perceptions of equity change over time, and to examine efforts to restore equity. Differences in well-being and distress in roles are identified by gender and equity group. study results indicate that for both spouses, perceptions of inequity are associated with lower marital well-being and higher marital distress; however, under benefited wives reported higher professional well-being and under benefited husbands reported higher parental well-being. Couple perceptions of equity decreased between 1986 and 1990; under benefited husbands were more likely to use threats and bargaining to negotiate for relationship changes while wives sought counseling. Results demonstrate the importance of using multiple measures of well-being and distress and including gender and equity type in investigations of marital equity.Ph. D.
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Ledden, Lesley. "The dynamic nature of value : a longitudinal study." Thesis, Kingston University, 2009. http://eprints.kingston.ac.uk/20283/.
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Accepting the view that the marketing process is centred on exchange between two parties (Hunt, 2002), it follows that exchange will take place between two (or more) parties when each party trades something of value in return for something of greater value. Consequently the logical conclusion is that value is the cornerstone of marketing (see for example Eggert and Ulaga, 2002; Holbrook, 2005). Perceptions of value can vary over time and experience (Eggert and Ulaga, 2002; Woodall, 2003; Sánchez-Fernandez and Iniesta-Bonillo, 2007). However, even though the temporal nature of value is widely acknowledged, research in this area has been largely overlooked, and while there is limited investigation within the b2b domain (see Flint et al., 2002; Beverland and Lockshin, 2003; Eggert et al., 2006) a literature search has been unable to identify any research that examines actual changes in perceptions of value within consumer research. Consequently, the aim of this study is to empirically examine the temporal stability (i.e., the nature and strength) of the functional relationships between value and its antecedents and outcomes. In order to address the above aim a theoretically grounded model is proposed. Based on common acceptance among researchers (see review by Woodall, 2003) value is conceptualised as the result of a 'trade-off' between benefits (get) and sacrifices (give). However, instead of treating value as a composite higher order construct the behaviours of its two components (get and give) with the following constructs are examined separately: service quality and personal values (terminal and instrumental) are modelled as determinants while satisfaction and intention are the outcomes of value. In addition the impact of knowledge (cognitive; Woodruff, 1997) and emotions (affective; Richins, 1997) as direct determinants of value and additionally as moderators of the value to satisfaction relationship is tested. The research was-conducted within the Higher Education sector among consumers of postgraduate education at a London business school. To test the temporal stability and pattern of development of the functional relationships between the value components and their above defined nomologically related constructs, related data were collected longitudinally from two sample of cohorts at three points in time (i.e., the beginning, middle and end of their studies) via a personally (Times 1 and 2) and internet (Time 3) administrated questionnaire. A total of 34 and 45 usable responses were collected from Cohorts 1 and 2 respectively over the three time points. The data were analysed using Partial Least Squares. Analysis indicates that the give component of value should be separated into money, and time and effort (denoted in this study as give). There is support for knowledge and emotions as direct determinants of the now three value components rather than as moderators of the relationships between these components and satisfaction. Comparisons between the two cohorts reveal the existence of a number of significant differences in the relative strength of corresponding relationships. Finally, in terms of the focal interest of this study, there is substantial evidence of the temporal nature of the functional relationships of the value components. Four of the hypothesised relationships are supported only at a single time point, while a number of significant changes in the strength of the functional relationships between the three points in time are identified. The research is considered to make the following contributions to the subject matter. It confirms the idiosyncratic nature of the value components in terms of their functional relationship with antecedents and consequences. It highlights the need to consider the location of monetary sacrifice within the give component. The existence of a time lag before some determinants have a significant impact on the formation of value is identified. There is tentative evidence to suggest that as consumption progresses, value is formed by a larger number of determinants. For the get component, significant variations in the strength of its functional relationships over time are found to exist.
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Morris, Saul Sutkover. "The analysis of longitudinal studies of common diseases of childhood." Thesis, London School of Hygiene and Tropical Medicine (University of London), 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388264.
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Lundequist, Aiko. "Longitudinal studies of executive and cognitive development after preterm birth." Doctoral thesis, Stockholms universitet, Psykologiska institutionen, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-78946.
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Stockholm Neonatal Project is a longitudinal population-based study of children born prematurely in 1988-93, with a very low birth weight (<1500 g), who have been followed prospectively from birth through adolescence. A matched control group was recruited at age 5 ½ years. The overall aim was to investigate long-term developmental outcome, paying particular attention to executive functions (EF) in relation to degree of prematurity, birth weight and medical risks. Study I showed a disadvantage in visuo-motor development at 5 ½ years, especially among the preterm boys. Visuo-motor skills were highly related to IQ, and also to EF. In Study II, neuropsychological profiles typical of preterm children and term born children, respectively, were identified through cluster analysis. The general level of performance corresponded well with IQ, motor functions and parental education in both groups, but preterm children had overall lower results and exhibited greater variability across domains. Study III showed that extremely preterm birth (w. 23-27) per se poses a risk for cognitive outcome at age 18, particularly for EF, and that perinatal medical complications add to the risk. By contrast, adolescents born very preterm (w. 28-31) performed just as well as term-born controls in all cognitive domains. However, adolescents born moderately preterm (w. 32-36) and small for gestational age showed general cognitive deficits. Study IV found that cognitive development was stable over time, with parental education and EF at 5 ½ years as significant predictors for cognitive outcome at age 18. Among preterm children, perinatal medical risks and being small for gestational age had a continued negative impact on cognitive development from 5 ½ to 18 years. Study V demonstrated that neuropsychological scoring of Bender drawings, developed in study I, predicted cognitive outcome in adolescence, indicating that the method may be useful in developmental screening around school entry.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript. Paper 5: Submitted.
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Ding, Xiuhua. "MODELING DEMENTIA RISK, COGNITIVE CHANGE, PREDICTIVE RULES IN LONGITUDINAL STUDIES." UKnowledge, 2016. http://uknowledge.uky.edu/epb_etds/9.
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Dementia is increasing recognized as a major problem to public health worldwide. Prevention and treatment strategies are in critical need. Nowadays, research for dementia usually featured as complex longitudinal studies, which provide extensive information and also propose challenge to statistical methodology. The purpose of this dissertation research was to apply statistical methodology in the field of dementia to strengthen the understanding of dementia from three perspectives: 1) Application of statistical methodology to investigate the association between potential risk factors and incident dementia. 2) Application of statistical methodology to analyze changes over time, or trajectory, in cognitive tests and symptoms. 3) Application of statistical learning methods to predict development of dementia in the future.
Prevention of Alzheimer’s disease with Vitamin E and Selenium (PREADViSE) (7547 subjects included) and Alzheimer’s disease Neuroimaging Initiative (ADNI) (591 participants included) were used in this dissertation. The first study, “Self-reported sleep apnea and dementia risk: Findings from the PREADViSE Alzheimer’s disease prevention trial ”, shows that self-reported baseline history of sleep apnea was borderline significantly associated with risk of dementia after adjustment for confounding. Stratified analysis by APOE ε4 carrier status showed that baseline history of sleep apnea was associated with significantly increased risk of dementia in APOE ε4 non-carriers. The second study, “comparison of trajectories of episodic memory for over 10 years between baseline normal and MCI ADNI subjects,” shows that estimated 30% normal subjects at baseline assigned to group 3 and 6 stay stable for over 9 years, and normal subjects at baseline assigned to Group 1 (18.18%) and Group 5 (16.67%) were more likely to develop into dementia. In contrast to groups identified for normal subjects, all trajectory groups for MCI subjects at baseline showed the tendency to decline. The third study, “comparison between neural network and logistic regression in PREADViSE trial,” demonstrates that neural network has slightly better predictive performance than logistic regression, and also it can reveal complex relationships among covariates. In third study, the effect of years of education on response variable depends on years of age, status of APOE ɛ4 allele and memory change.
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Cheung, Siu-kau, and 張兆球. "Depressive experiences and perception of self: a longitudinal study on Chinese early adolescents." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31234719.
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Klopfer, Loretta Marie. "A longitudinal study of a family maintenance program." CSUSB ScholarWorks, 1994. https://scholarworks.lib.csusb.edu/etd-project/797.
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黎靜娜 and Ching-nor Shirley Lai. "Retrospective study of the periapical and clinical status of crowned teeth over 10 years." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B38628107.
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Li, Yuen-hung Angel, and 李婉紅. "Coping strategies and individual differences on adjustment and performance: a longitudinal analysis withHong Kong college students." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31238944.
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Tilley, Sara. "Ageing and mobility in Britain : past trends, present patterns and future implications." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/4471.
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Over the next decade the ‘Baby Boomer' cohort will increasingly contribute to the proportion of those aged 60 and over in Britain. The issue of how the mobility of older people has changed for different cohort groups has not been considered in a historical context. Ryder (1965) argued that cohort groups could be important in determining behaviour as have other social structural factors, such as socioeconomic status. This thesis merges the disciplines of transport geography and population studies using a novel approach of cohort analysis, which has not been used widely for studying mobility trends. Using National Travel Survey data from 1995-2008, the mobility trends of older people in Britain are explored by creating pseudo cohorts. Pseudo cohorts are artificially created datasets which are constructed from using repeated cross-sectional data (McIntosh, 2005, Uren, 2006). This technique can differentiate ‘age', ‘period' and ‘cohort' effects in mobility trends. Age effects are differences in behaviour between age groups i.e. changes in mobility associated with age itself. Period effects relate to changes in behaviour in all age groups over a period of time. Cohort effects are those associated with behaviour common to particular groups born around the same time (Glenn, 2005, Yang, 2007). The influence of the Scottish concessionary travel policy on the mobility of older people at the aggregate level is also considered using Scottish Household Survey data from 1999-2008. This policy is very blunt and based on assumptions about older age. As cohorts differ, these assumptions may no longer hold and therefore the policy may not be effective. This thesis argues, using a longitudinal demographic perspective, that structural effects shape mobility of cohorts differently over time. The findings reveal although mobility amongst older people is rising in general, there would actually be declining mobility were it not for the Boomer cohort. Amongst younger cohorts mobility is lower. The analysis also shows that women travel further than men, a fundamental break with the past, specific to this generation. This thesis illustrates the importance of cohort membership in explaining mobility change.
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Leung, Suet-fan Lydia, and 梁雪芬. "Lifestyle practices and perceived health in Hong Kong Chinese: a cross-sectional and a longitudinal studyfrom 1999 to 2001." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B39724190.
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Kurland, Brenda F. "Analysis of binary longitudinal data with dropout and death /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/9593.
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Petrik, Rebecca D. (Rebecca Diane). "Long-Term Effects of Quality Preschool for Disadvantaged Children." Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc500445/.
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The eleven studies which comprise the Consortium for Longitudinal Studies were described in order to determine long-term effects of preschool education on disadvantaged children. Research methods and results of the studies were evaluated and compared. An historical overview details the sociopolitical milieu from the time the eleven studies began in the 1960s to the present. Theories which impacted the preschool movement in the 1960s were also discussed, particularly those which concern the development of intelligence, the importance of early education and environmental impact on the development of intelligence. Demographic data were used to describe disadvantaged children's needs for quality early intervention programs. The results of the eleven Consortium studies indicate positive long-term effects for disadvantaged children enrolled in quality preschool programs.
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Sahlberg, Bo. "Indoor Environment in Dwellings and Sick Building Syndrome (SBS) : Longitudinal Studies." Doctoral thesis, Uppsala universitet, Arbets- och miljömedicin, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-172769.
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People spend most of their time indoors and mostly in the dwelling. It is therefore important to investigate associations between indoor exposure in dwellings and health. Symptoms that may be related to the indoor environment are sometimes referred to as the "sick building syndrome" (SBS). SBS involves symptoms such as eye, skin and upper airway irritation, headache and fatigue. Three longitudinal studies and one prevalence study on personal and environmental risk factors for SBS in adults were performed. The prevalence study included measurements of indoor exposures in the dwellings. The longitudinal studies, with 8-10 years follow-up time, showed that smoking and indoor paint emissions were risk factors for SBS. Moreover, building dampness and moulds in dwellings were risk factors for onset (incidence) of general symptoms, skin symptoms and mucosal symptoms. In addition subjects living in damp dwellings have a lower remission of general symptoms and skin symptoms. Hay fever was a risk factor for onset of skin symptoms and mucosal symptoms, and asthma was a risk factor for onset of general and mucosal symptoms. Biomarkers of allergy and inflammation (bronchial reactivity, total IgE, ECP and eosinophil count) were predictors of onset of SBS symptoms, in particular mucosal symptoms. In the prevalence study, any SBS-symptom was associated with some individual volatile organic compounds of possible microbial origin (MVOC) e.g. 2-pentanol, 2-hexanon, 2-pentylfuran and 1-octen-3ol. Moreover, there were associations between indoor levels of formaldehyde and the plasticizer Texanol and any SBS. The result from the study indicates that individual MVOC are better indicators of SBS than the total value of MVOC. A final conclusion is that smoking, dampness and moulds and emissions from indoor painting may increase the onset of SBS. The indoor environment in dwellings over time has improved, but there is still a need for further improvements of the indoor environment in dwellings. More longitudinal SBS studies are needed.
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Järvinen, J. (Janne). "Rationale for adopting activity-based costing in hospitals:three longitudinal case studies." Doctoral thesis, University of Oulu, 2005. http://urn.fi/urn:isbn:9514279484.
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Abstract In the 1990's, a large number of Finnish hospitals began implementing new cost accounting systems, which were aimed at pricing the hospital outputs at full cost. Often the method of choice was activity-based costing, which was in the process of being transferred from the manufacturing industry to health care service production. The aim of this study is to analyse the motivations and rationale of this phenomenon in the light of three longitudinal case studies. The first case study is archival, using documents produced between 1996 and 2002. In the second case study, the data consists mainly of research diaries and personal observation and covers a hospital district activity-based costing and pricing project of 2000–2001. The third case study covers budgeting and costing development in a private, non-profit hospital by analysing documents and field notes. Institutional theory is used to interpret the findings in the three case studies. The theoretical framework used in analysing the data draws on Roberts and Greenwood's (1997) ideas, according to which an organisation's rational and efficiency-seeking actions are constrained by both economic (bounded rationality) and institutional factors. The results indicate that different constraints imposed on efficiency-seeking behaviour such as activity-based costing implementation may lead to different solutions concerning implementation. It is noteworthy that while all three case organisations represent the health care sector, their approaches to activity-based costing have been quite dissimilar. While institutional theory leads us to believe that managerial accounting systems may be converging due to the institutional pressures, evidence from the case studies supports the notion that this convergence seems limited to the adoption of the systems – function of the systems seems to remain characteristically differentTiivistelmä Useat suomalaiset sairaalat aloittivat 1990-luvulla laajamittaisia kustannuslaskentaprojekteja, joissa tähdättiin täyskatteiseen hinnoitteluun. Usein valittuna menetelmänä oli toimintolaskenta, jota siirrettiin teollisesta toimintaympäristöstä terveydenhuollon palvelutuotantoon. Tutkimuksen tavoitteena on tarkastella tämän ilmiön syitä ja motiiveja kolmen tapaustutkimuksen valossa, joista kaksi on sairaanhoitopiirejä ja kolmas on voittoa tavoittelemattoman yhteisön omistama yksityinen sairaala. Ensimmäisessä tapaustutkimuksessa aineisto on dokumentteihin perustuvaa arkistomateriaalia vuosilta 1996–2002. Lisäksi kustannuslaskentamallien rakennetta on tarkasteltu käymällä läpi laskelmissa tehtyjä rakenteellisia ja teknisiä ratkaisuja sekä laskentasääntöjä. Toisessa tapaustutkimuksessa aineisto koostuu pääasiassa tutkijan päiväkirjoista ja havainnoista, ja sisältää sairaanhoitopiirin laajuisen kustannuslaskenta- ja hinnoitteluprojektin kuvauksen vuosilta 2000–2001. Kolmannessa tapaustutkimuksessa käydään läpi yksityisen sairaalan budjetoinnin ja kustannuslaskennan kehitystä dokumentteihin ja tutkijan muistiinpanoihin nojautuen. Teoreettisena viitekehyksenä aineiston tulkinnassa käytetään Robertsin ja Greenwoodin (1997) rajoitetun tehokkuuden mallia, jonka mukaan organisaation tehostamispyrkimyksiä rajoittavat sekä taloudelliseen rationaalisuuteen liittyvät tekijät (rajoitettu rationaalisuus) että institutionaaliset tekijät. Tutkimuksen tulokset osoittavat, että erityyppiset rajoittavat tekijät vaikuttavat organisaatioiden tehokkuuspyrkimyksiin (joihin toimintolaskentaprojektit on luettava) siten, että lopputuloksena on erilaisia sovelluksia toimintolaskennan käyttöönotosta. On huomionarvoista, että vaikka kaikki tutkimuksen kohteena olleet tapaukset ovat erikoissairaanhoidon organisaatiota, niiden tavat ottaa toimintolaskenta käyttöön ovat olleet toisistaan hyvin poikkeavia. Vaikka institutionaaliseen teoriaan perustuvasta tutkimuksesta voikin tehdä sellaisen johtopäätöksen, että ulkoiset paineet muovaavat organisaatioita samanlaisiksi, näiden tapaustutkimusten perusteella on mahdollista väittää, että samanlaisuuden paineet liittyvät laskentajärjestelmien käyttöönottoon järjestelmien toiminnan jäädessä varsin erityyppisiksi
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Kondo, Yumi. "Identification of worsening subjects and treatment responders in comparative longitudinal studies." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57447.
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This thesis discusses the problems of identifying worsening individuals in on-going clinical trials and treatment responders in completed trials.
We develop a new modelling approach to enhance a recently proposed method to detect increases of contrast enhancing lesions (CELs) on repeated magnetic resonance imaging, which have been used as an indicator for potential adverse events. The method signals patients with unusual increases in CEL activity by estimating the probability of observing CEL counts as large as those observed on a patient's recent scans conditional on the patient's CEL counts on previous scans. This index, computed based on a mixed effect negative binomial regression model, can vary substantially depending on the choice of distribution for the patient-specific random effects. Therefore, we relax this parametric assumption to model the random effects with an infinite mixture of beta distributions, using the Dirichlet process, which effectively allows any form of distribution. As our inference is in the Bayesian framework, we adopt a meta-analytic approach to develop an informative prior based on previous trials. This is particularly helpful at the early stages of a trial. We illustrate our enhanced method with 10 multiple sclerosis (MS) trial datasets, and assess it by simulation studies.
Identification of treatment responders is a challenge in comparative studies where a treatment efficacy is measured by various longitudinally-collected continuous and count outcomes. Existing procedures often identify responders based on only a single outcome. We propose to classify patients according to their posterior probability of being a responder estimated based on a multiple outcome mixture model. Our novel model assumes that, conditioning on a cluster label, each longitudinal outcome is from the generalized linear mixed effect model (GLMM), arguably the most popular longitudinal model. As GLMM is a rich class of models, our general procedure enables finding responders comprehensively defined by multiple outcomes from various distributions. We utilize the Monte Carlo expectation-maximization algorithm to obtain the maximum likelihood estimates of our high-dimensional model. We demonstrate the generality of our procedure on two MS trial datasets. Our simulation study shows that incorporating multiple outcomes improves the responder identification performance.Science, Faculty of
Statistics, Department of
Graduate
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FERREIRA, ISABELLA VIEIRA. "ASSESSING THE BUG-PRONENESS OF REFACTORED CODE: LONGITUDINAL MULTI-PROJECT STUDIES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=35428@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Os elementos de código geralmente mudam ao longo da evolução do sistema, o que implica em uma eventual degradação estrutural do código fonte. Sintomas recorrentes de tal degradação são chamados anomalias de código. Estudos sugerem que quanto mais anomalias de código afetam um sistema, mais alta se torna a propensão a bugs dos elementos de código. Para lidar com tal degradação da qualidade estrutural do código, desenvolvedores geralmente aplicam refatorações no código fonte. No entanto, aplicar refatorações pode não ser suficiente para reduzir a propensão a bugs dos elementos de código degradados. Um estudo recente sugere que refatorações induzem bugs frequentemente. No entanto, os autores não analisam se o código refatorado está, de fato, diretamente relacionado à introdução de bugs. Com isso, nesta dissertação, realizamos dois estudos longitudinais de múltiplos projetos para avaliar a propensão a bugs do código refatorado. Nossa metodologia teve como objetivo abordar várias limitações de estudos anteriores. Por exemplo, definimos duas propriedades complementares da propensão a bugs do código refatorado, sendo elas, frequência e distância. Enquanto a primeira propriedade quantifica a frequência com que um código refatorado está relacionado a bugs que emergiram no código fonte, a distância quantifica o quão próximo um bug surge depois que uma refatoração é aplicada. Nosso primeiro estudo tem como objetivo avaliar a propensão a bugs de refatorações isoladas. Primeiro, nossos resultados mostram que 80 porcento dos elementos degradados que se tornaram bugs não foram previamente refatorados. Este resultado implica que um código refatorado é menos propenso a bugs do que um código não refatorado. Em segundo lugar, em 75 porcento das vezes um bug surge depois de 7 mudanças feitas a partir da operação de refatoração, o que geralmente corresponde à 3 meses nos projetos analisados. Nosso segundo estudo tem como objetivo avaliar a propensão a bugs de refatorações em lote, ou seja, refatorações aplicadas em sequência. Nossos resultados mostram que, na maioria dos casos, o código refatorado em lotes é mais resiliente à introdução de bugs do que o código refatorado por meio de refatorações isoladas.
Programs often change along the system evolution, which implies an eventual code structure degradation. Recurring symptoms of such degradation are code smells. Studies suggest that the more frequently code smells affect a system, the higher becomes the bug-proneness of the code elements. To tackle code structural quality degradation, developers often apply refactorings on smelly program elements. However, applying refactorings might not suffice to reduce the bug-proneness of such degraded program elements. Previous empirical studies do not systematically analyze the bug-proneness of refactored code. Even though a recent study suggests that refactoring induces bugs frequently, the authors do not analyze to what extent refactored code is indeed closely related to the bug occurrence. Thus, in this dissertation, we conducted two longitudinal multi-project studies to assess the bugproneness of refactored code. Our methodology aimed to address various limitations of previous studies. For instance, we have defined two complementary properties of the bug-proneness of refactored code, i.e., frequency and distance. While the former quantifies how often a refactored code is related to emerging bugs, the latter quantifies how close a bug emerges after a refactoring has been applied. The quantitative analysis of such properties was complemented by a manual analysis of refactorings closely related to the bug occurrence. Our first study aims at assessing the bug-proneness of code refactored through isolated refactorings, i.e., a single refactoring operation not performed in conjunction with other refactoring operations. This study reveals that 80 per cent of the smelly elements that became buggy were not previously refactored. This result suggests the refactored code is much less bug-prone than non-refactored code. Moreover, in 75 per cent of the times, a bug emerges in 7 changes far from the refactoring operation; this amount of changes usually corresponds to 3 months in the analyzed projects. Our second study aims at assessing the bug-proneness of code elements refactored through batch refactorings, i.e., a sequence of inter-related refactoring operations. Our results show that code refactored through batches is often more resilient to the introduction of bugs as compared to code refactored through isolated refactorings.
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Zhai, Jing. "Efficient Exact Tests in Linear Mixed Models for Longitudinal Microbiome Studies." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/612412.
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Microbiome plays an important role in human health. The analysis of association between microbiome and clinical outcome has become an active direction in biostatistics research. Testing the microbiome effect on clinical phenotypes directly using operational taxonomic unit abundance data is a challenging problem due to the high dimensionality, non-normality and phylogenetic structure of the data. Most of the studies only focus on describing the change of microbe population that occur in patients who have the specific clinical condition. Instead, a statistical strategy utilizing distance-based or similarity-based non-parametric testing, in which a distance or similarity measure is defined between any two microbiome samples, is developed to assess association between microbiome composition and outcomes of interest. Despite the improvements, this test is still not easily interpretable and not able to adjust for potential covariates. A novel approach, kernel-based semi-parametric regression framework, is applied in evaluating the association while controlling the covariates. The framework utilizes a kernel function which is a measure of similarity between samples' microbiome compositions and characterizes the relationship between the microbiome and the outcome of interest. This kernel-based regression model, however, cannot be applied in longitudinal studies since it could not model the correlation between the repeated measurements. We proposed microbiome association exact tests (MAETs) in linear mixed model can deal with longitudinal microbiome data. MAETs can test not only the effect of overall microbiome but also the effect from specific cluster of the OTUs while controlling for others by introducing more random effects in the model. The current methods for multiple variance component testing are based on either asymptotic distribution or parametric bootstrap which require large sample size or high computational cost. The exact (R)LRT tests, an computational efficient and powerful testing methodology, was derived by Crainiceanu. Since the exact (R)LRT can only be used in testing one variance component, we proposed an approach that combines the recent development of exact (R)LRT and a strategy for simplifying linear mixed model with multiple variance components to a single case. The Monte Carlo simulation studies present correctly controlled type I error and provided superior power in testing association between microbiome and outcomes in longitudinal studies. Finally, the MAETs were applied to longitudinal pulmonary microbiome datasets to demonstrate that microbiome composition is associated with lung function and immunological outcomes. We also successfully found two interesting genera Prevotella and Veillonella which are associated with forced vital capacity.
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Yang, Lan, and 杨兰. "Enhancing academic self-concept and academic achievement of vocationalstudents: a longitudinal intervention studyin mainland China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48329873.
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While much is known about the achievement of high ability students, much less research has focused on their lower ability peers. In addition, although academic self-concept, locus of control and learning approaches have been demonstrated to be important personal variables that influence learning outcomes, less effort has been made to integrate these variables simultaneously to understand the complexity of low-achievement. The present research aimed to not only identify key causes of the low-achievement of academically disadvantaged students, but also provide appropriate and productive enhancement approaches to foster low-achieving students’ school success by conducting a pioneering longitudinal experimental study particularly in mainland China.
The participants were low-achieving junior secondary students who had recently enrolled in Secondary Vocational Education (SVE) in mainland China (total N = 724). It was found that compared with normal- and high-achieving students in mainstream secondary education, students in SVE were characterized with less achieving motives, less internal-oriented control beliefs and particularly lower academic self-concepts. In addition, the academic self-concept of SVE students was found to be the most significant predictor of their academic achievement (p＜ .001) compared with achieving approach (p＜ .05) and locus of control (p＞ .05). These findings, in light of the 3P learning model, revealed the likely major role of academic self-concept in affecting academic achievement among adolescent students in SVE. In particular, Study 2, a comparative study, confirmed that vocational students had the lowest English self-concept of the groups studied. Hence, the focus of Study 3 (a longitudinal intervention) was on English self-concept.
By incorporating recent advances in Western feedback enhancement approaches and the construct-validity approach to fully explore the intervention effects, Study 3 demonstrated that the researcher-administered treatments (performance feedback and combined feedback) in natural classroom settings successfully enhanced participants’ English self-concept, the targeted facet. Importantly, both the competence and affect components within the English self-concept of targeted students also gained statistically significant improvements from the two feedback treatments, compared with those of students who received no particular treatment. An interesting finding was that the two feedback treatments appeared similarly significant in changing the competence component of English self-concept. However, the internally-focused performance feedback was less effective in changing the affect component of English self-concept compared with the combined feedback. Non-significant transfer effects were found on untargeted facets of academic self-concept among participants receiving only the performance feedback. A slightly significant transfer effect was found on Chinese self-concept (one control facet) among participants receiving the combined feedback, indicating the power of the combined feedback to influence a facet that is closely related to the targeted facet. The present findings provided important cross-cultural empirical evidence to support sound within-network validity of the feedback intervention in a vocational setting. Impressively, the English achievements of students in both experimental classes also gained statistically significant improvements. Based on key research designs of the present intervention, future implications of the two feedback treatments to cultivate positive academic self-beliefs and enhance learning among vocational and non-vocational secondary school students are discussed.published_or_final_version
Education
Doctoral
Doctor of Philosophy
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Hare-Blye, Cynthia Lee. "Gender Differences in Slow Expressive Language Development." PDXScholar, 1994. https://pdxscholar.library.pdx.edu/open_access_etds/4854.
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The contemporary research suggests that some children who present with early language delays as toddlers outgrow their delays while others continue to develop long-term language difficulties. Several studies over the years have focused on factors that might aid in predicting the outcome of late talkers. This current study emphasized exploring gender as a possible predictive factor. The purpose of this study was to determine if significant differences exist in the rate of growth in language skills, as indexed by scores on the Developmental Sentence Scoring (DSS) procedure (Lee, 1974) of boys versus girls who are late to start talking as toddlers. The research hypothesis was that boys who present as LT toddlers would score significantly higher than LT girls at each age level tested. The DSS is a norm-referenced instrument that assesses age-appropriate morphological development and syntax. The LT subjects used were part of the Portland Language Development Project, a longitudinal study. Spontaneous speech samples were collected, transcribed, and analyzed using the DSS procedure once each year from the time they were approximately 3 years of age, until the age of 7. Late talking children in this present study were grouped by gender. A Chi Square test was used to determine if the proportion of males scoring above the 10th percentile on the DSS was significantly different than the proportion of females scoring above the 10th percentile at each age. Results from this analysis indicated that at the age of 3 years, more boys than girls scored above the 10th percentile on the DSS. There were no significant differences found at the ages of 4, 5, 6, and 7. At-test was used to compare average DSS scores between the two genders for each year of the study. This test revealed a significant difference between the LT girls' and LT boys' scores at the age of 3 years. No significant differences were found for the subsequent years. However, difference between boys' and girls' scores at age 7 approached significance, with boys again scoring higher.
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Bond, Jennifer. "Quality improvement in professional local government services : a longitudinal study." Thesis, Aston University, 2001. http://publications.aston.ac.uk/10751/.
Full textAbstract:
This sustained longitudinal study, carried out in a single local authority, investigates the implementation of a Total Quality Management (TQM) philosophy in professional local government services. At the start of this research, a large majority of what was written about TQM was polemical and based on limited empirical evidence. This thesis seeks to provide a significant and important piece of work, making a considerable contribution to the current state of knowledge in this area. Teams from four professional services within a single local authority participated in this research, providing the main evidence on how the quality management agenda in a local authority can be successfully implemented. To supplement this rich source of data, various other sources and methods of data collection have been used: 1) Interviews were carried out with senior managers from within the authority; 2) Customer focus groups and questionnaires were used; 3) Interviews were carried out with other organisations, all of which were proponents of a TQM philosophy. A number of tools have been developed to assist in gathering data: 1) The CSFs (critical success factors) benchmarking tool; 2) Five Stages of Quality Improvement Model. A Best Practice Quality Improvement Model, arising from an analysis of the literature and the researcher's own experience is proposed and tested. From the results a number of significant conclusions have been drawn relating to: 1) Triggers for change; 2) Resistance of local government professionals to change 3) Critical success factors and barriers to quality improvement in professional local government services; 4) The problems associated with participant observation and other methodological issues used.
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Stecksén-Blicks, Christina. "Epidemiological studies of dental caries in groups of Swedish children." Umeå : [s.n.], 1986. http://catalog.hathitrust.org/api/volumes/oclc/14125444.html.
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Bester, Dirk W. "Joint survival models : a Bayesian investigation of longitudinal volatility." Thesis, University of Oxford, 2014. https://ora.ox.ac.uk/objects/uuid:35db576b-10a7-4e49-a04d-dee99544227d.
Full textAbstract:
In this thesis, we investigate joint models of longitudinal and time-to-event data. We extend the current literature by developing a model that assigns subject-specific variance to the longitudinal process and links this variance to the survival outcome. During development we provide the theoretical definition of the model and its properties, and explore the practical implications for estimating the parameters. We use Markov Chain Monte Carlo (MCMC) methods, and compare the different samplers used in similar models in the literature with our custom MCMC algorithm, written in C++. We use the Deviance Information Criterion to perform model comparisons, and we formalise suggestions from the literature to use posterior predictive model checking to construct a goodness-of-fit test for our model. We use the model on two real-world datasets to investigate claims relating to the importance of blood pressure volatility on stroke risk, and examine the consequences of ignoring measurement error. We amend our model to accommodate competing risk, time-dependent baseline hazard rates, and bivariate longitudinal processes - at which point we update our MCMC samplers and identify the issues. Finally, we use our code in a separate, but related, collaboration with other researchers to analyse repeated counts data.
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Cardiel, Christopher Louis. "Are We Cool Yet?: A Longitudinal Content Analysis of Nerd and Geek Representations in Popular Television." PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/810.
Full textAbstract:
This study explores the representation of nerds and geeks in popular broadcast television programs over the course of the past twenty years. A content analysis of the five most popular scripted broadcast television programs for each year was conducted in order to assess the frequency of nerd characters, as well as the social competence, physical attractiveness, and demographic information of each such character. In addition, a supplemental survey design study was employed in order to collect public opinion data regarding perceptions of nerds in general and on television. The results of these studies indicated that while the per-year frequency of nerd portrayals has not varied significantly, nerds have been consistently portrayed as overwhelmingly white and male. Nerd characters in popular television programs have grown more physically attractive over the past twenty years. Furthermore, while technological or computer-related expertise remain significant predictors for the identification of television characters as nerds by audience members, the same is true for unattractiveness and low social competence. Considered through the theoretical framework provided by past mass media scholars, these findings suggest that nerds represent a group of individuals consistently portrayed as possessing technical aptitudes which are highly desirable in the current social context, but that such roles are portrayed as accessible only to white males.