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Jerabek, Jakub, Allessandra Keil, Jens Schoene, Rostislav Chudoba, Josef Hegger, and Michael Raupach. "Experimental and Numerical Analysis of Spalling Effect in TRC Specimens." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1244046893347-05461.
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The paper presents the study of spalling effect occurring under tensile loading in thin-walled TRC specimens. The experimentally observed failure patterns are first classified and the performed experiment design is explained and discussed. A parameter study of spalling effect with varied thickness of concrete cover and reinforcement configurations including both the textile fabrics and the yarns provided the basis for numerical analysis of the effect. The applied numerical model was designed in order to capture the initiation and propagation of longitudinal cracks leading to the separation of concrete blocks from the textile fabrics. A meso-scopic material resolution in a single crack bridge is used for the simulation exploiting the periodic structure of the crack bridges both in the lateral and in the longitudinal direction of the TRC specimens. The matrix was modeled using an anisotropic damage model falling in the microplane-category of material models. The bond between yarn and matrix follows a non-linear bond-law calibrated using pull-out tests. The epoxy-impregnated reinforcement is considered as a homogeneous bar.
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Littles, Jerrol W. Jr. "Scattering of longitudinal elastic waves from a distribution of cracks." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/19242.
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Rodriguez, Ripoll Manel. "Drawing of tungsten wires: microstructure, mechanical properties and longitudinal cracks /." Aachen : Shaker, 2009. http://d-nb.info/993546323/04.
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Cappelli, Marcus Domenic. "The Evolution of Multi-Site Small Cracks under Fatigue Loading." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14554.
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This thesis focuses on the growth of cracks which are small in relation to the material microstructure especially the situation of clusters of small cracks grown from smooth surfaces, termed micro-multi-site cracking, as is frequently the case for components in service. A proper understanding of this regime of crack growth will allow for less conservative maintenance schedules as well as the application of more sensitive health monitoring systems which are currently under development.
To address the problem a significant experimental investigation of micro-multi-site cracking was conducted on 7075-T7351 aluminum alloy. Using the resulting data a micro-structurally based transition crack length is defined to determine the point which separates small and long crack growth. This definition is based upon the observed evolution of scatter in the growth rates of growing small cracks. It is shown that this scatter falls with growth until the transition point is reached where it assumes a constant value for the growth of long cracks.
It is then shown that the total population of cracks within the clusters can be considered as bi-modal. One distribution consists of primary cracks which can grow and ultimately cause specimen failure. The second distribution consists of secondary cracks, the growth of which ultimately arrests. Several methods for experimentally separating the two distributions have been developed. The first method relies upon the defined transition point between small and long crack behavior. A second method based upon the second derivative of the crack length versus cycle count data has also been developed. Since the secondary cracks cannot lead to failure their data must be discarded prior to any analysis. It is then shown that failure to do so will lead to erroneous non-conservative predictions of crack growth.
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Rodríguez, Ripoll Manel [Verfasser]. "Drawing of Tungsten Wires: Microstructure, Mechanical Properties and Longitudinal Cracks / Manel Rodriguez Ripoll." Aachen : Shaker, 2009. http://d-nb.info/1126378704/34.
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Mirjana, Filipovic. "Evolution of artificial defects during shape rolling." Licentiate thesis, Högskolan Dalarna, Materialvetenskap, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:du-5215.
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Very often defects are present in rolled products. For wire rods, defects are very deleterious since the wire rods are generally used directly in various applications. For this reason, the market nowadays requires wire rods to be completely defect-free. Any wire with defects must be rejected as scrap which is very costly for the production mill. Thus, it is very important to study the formation and evolution of defects during wire rod rolling in order to better understand and minimize the problem, at the same time improving quality of the wire rods and reducing production costs. The present work is focused on the evolution of artificial defects during rolling. Longitudinal surface defects are studied during shape rolling of an AISI M2 high speed steel and a longitudinal central inner defect is studied in an AISI 304L austenitic stainless steel during ultra-high-speed wire rod rolling. Experimental studies are carried out by rolling short rods prepared with arteficial defects. The evolution of the defects is characterised and compared to numerical analyses. The comparison shows that surface defects generally reduce quicker in the experiments than predicted by the simulations whereas a good agreement is generally obtained for the central defect.
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Cassidy, Anthony John. "The cultural evolution of achievement motivation and subjective well-being : a longitudinal analysis." Thesis, University of Ulster, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329446.
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Stanzani, Maserati Michelangelo <1975>. "Longitudinal evolution of cognitive functions in patients with multiple system atrophy: a prospective study." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5325/.
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Introduction and Background: Multiple system atrophy (MSA) is a sporadic, adult-onset, progressive neurodegenerative disease characterized clinically by parkinsonism, cerebellar ataxia, and autonomic failure. We investigated cognitive functions longitudinally in a group of probable MSA patients, matching data with sleep parameters.
Patients and Methods: 10 patients (7m/3f) underwent a detailed interview, a general and neurological examination, laboratory exams, MRI scans, a cardiovascular reflexes study, a battery of neuropsychological tests, and video-polysomnographic recording (VPSG). Patients were revaluated (T1) a mean of 16±5 (range: 12-28) months after the initial evaluation (T0). At T1, the neuropsychological assessment and VPSG were repeated.
Results: The mean patient age was 57.8±6.4 years (range: 47-64) with a mean age at disease onset of 53.2±7.1 years (range: 43-61) and symptoms duration at T0 of 60±48 months (range: 12-144). At T0, 7 patients showed no cognitive deficits while 3 patients showed isolated cognitive deficits. At T1, 1 patient worsened developing multiple cognitive deficits from a normal condition. At T0 and T1, sleep efficiency was reduced, REM latency increased, NREM sleep stages 1-2 slightly increased. Comparisons between T1 and T0 showed a significant worsening in two tests of attention and no significant differences of VPSG parameters. No correlation was found between neuropsychological results and VPSG findings or RBD duration.
Discussion and Conclusions: The majority of our patients do not show any cognitive deficits at T0 and T1, while isolated cognitive deficits are present in the remaining patients. Attention is the cognitive function which significantly worsened. Our data confirm the previous findings concerning the prevalence, type and the evolution of cognitive deficits in MSA. Regarding the developing of a condition of dementia, our data did not show a clear-cut diagnosis of dementia. We confirm a mild alteration of sleep structure. RBD duration does not correlate with neuropsychological findings.
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Filipovic, Mirjana. "Evolution of artificial defects during shape rolling." Licentiate thesis, Stockholm : Division of Mechanical Metallurgy, Department of Material Science and Engineering, Industrial Engineering and Management, Royal Institute of Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4350.
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Dahlmann, Frederik. "Between inertia and adaptation : state and evolution of corporate environmental strategy." Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512335.
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Companies in the 21st century are exposed to a variety of pressures to respond to a plethora of environmental issues. Understanding how these issues impact companies over time is, therefore, important for corporate practitioners and policy makers alike. This thesis investigates the state and evolution of corporate environmental strategy with the help of a multi-study, longitudinal research design. Theoretically grounded in complexity theory, a conceptual framework is developed that portrays organisations as open systems within which agents interact and attempt to improve organisational fitness. By conceptualising the organisational metaphor of ‘rugged fitness landscapes’, firms are depicted as complex adaptive systems searching for peaks on a constantly changing fitness landscape in order to guarantee economic long-term profit and survival. While study one examines environmental responses among a stratified sample of UK companies through repeated interviews both in 2006 and 2008, the second study draws on KLD data from S&P500 corporations for the period 1991 to 2006 by distinguishing between changes at firm and at population level. The findings suggest that the state and evolution of corporate environmental strategy are effectively subordinated to contributing towards firms’ fitness, whereby firms mostly attempt to remain profitable and obtain social legitimacy. Even over longer periods of time this behaviour has not changed markedly, except that starting from around 2004 higher levels of oil prices and lower interest rates have spurred more proactive environmental changes among a number of firms. Equally, different motivations, individuals and contextual factors appear to influence the varying patterns of evolution. The thesis fills a gap in the existing literature with respect to the lack of conceptual and empirical contributions about the evolution of corporate environmental strategy by providing new insights into how firms are responding to environmental issues over time and by extending various strands of theory.
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Schoene, Jens, Uwe Reisgen, Markus Schleser, and Jakub Jeřábek. "Theoretische und experimentelle Untersuchung des spaltungsinduzierten Versagens von TRC Prüfkörpern." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-77814.
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Bewehrungen mit einer hochmoduligen Polymertränkung erreichen im Betonbauteil Textilspannungen von über 1200 N/mm². Ab diesem Niveau wurden in Dehnkörperversuchen Längsrisse und Betonabplatzungen beobachtet. Für die Eingrenzung und Identifikation der elementaren, verantwortlichen Mechanismen weisen großformatige Dehnkörper störende Einflüsse von Randeffekten und Imperfektionen auf. Daher wurde ein neuer Versuchsaufbau entwickelt, bestehend aus einem in einen Betonquader eingebetteten Einzelroving. Die simple Herstellung und die Verlässlichkeit dieser Kategorie von Experimenten in Bezug auf die Reproduzierbarkeit und der geringen Streuung der Resultate machen sie zu einer robusten Grundlage für experimentelle Untersuchungen des Verhaltens von TRC. Die experimentell ermittelten Bruchlasten werden zunächst bezüglich ihrer Leistung diskutiert und dann die beobachteten Bruchvorgänge kategorisiert hinsichtlich kompatibler mechanischer Hypothesen für die Initiierung von Längsrissen und des SpaltversagenReinforcements with a high-modulus, polymeric impregnation achieve textile tensions of 1200 N/mm² and more in concrete parts. Starting at this level longitudinal cracks and splitting were observed in tests. In order to isolate and identify the fundamental, responsible mechanisms large-scale specimen show an interfering impact of boundary effects and imperfections. Therefore a new test set-up was developed, consisting of a single roving embedded in a single concrete cuboid. The simplicity of production and reliability of this class of experiments in terms of repeatability and low scatter of results makes them a robust basis for experimental investigation of TRC behavior. The experimentally obtained strengths are discussed in terms of the performance, followed by the categorization of observed failure patterns with respect to the available mechanical hypotheses of the longitudinal crack initiation and splitting failure
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Yadav, Arvind. "A longitudinal study of competition and performance in the UK grocery retail industry." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/8110.
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The grocery retailing industry is a key sector of the UK economy, accounting for 16% of consumer expenditure. As such developments in this sector will have an important effect on UK economic and social welfare. Arguably, competition in the sector has intensified in the last two decades. Yet significant consolidation in the sector has put it under the spotlight of the UK competition authorities. Previous research analysing factors affecting the performance and positioning of UK grocery retailers has tended to be restricted to a limited time period and a small sample size. This study extends this research by investigating industry evolution and factors affecting performance and industry structure with longitudinal panel data, covering a two-decade time period. The sample used covers a wide variety of grocery retailers with a range of different attributes over a significant period in the development of the industry, running from 1985 through to 2003. Strategic group theory is employed to study industry evolution and examine the effects of strategic positioning on performance. Specifically, fixed-effect panel econometric models are estimated at different levels of aggregation to analyse firm, industry and strategic group effects on the performance of retailers. Also, stochastic frontier models, in the form of Cobb-Douglas and Transcendental Logarithmic functions, are estimated at different levels of aggregation to analyse the efficiency of retailers in the sector. The results from cluster analysis on strategic groups suggest that industry structure is likely to become more concentrated, and the size of retailers will be a significant mobility barrier in the industry. The profitability analysis finds industry level factors and strategic group composition to be crucial in explaining performance differences. The efficiency analysis finds large retailers exhibiting economies of scale through operating large store formats to be significantly better positioned from smaller-format retailers with fewer outlets. Consistent and significant time dummies demonstrate the favourable macro environment enjoyed by the retailers for much of the 1990s. The analysis reveals potentially useful insights for retail managers, especially concerning the importance of positioning in the industry and the choice of strategic orientation. More generally, the study opens up further possibilities for future studies of performance and efficiency measurement over an even longer time as the sector continues to develop and shape the way consumers shop in the UK.
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Oliveira, Marília Pilotto de. "Diálise peritoneal e qualidade de vida relacionada à saúde: um estudo longitudinal." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/22/22132/tde-19022015-183457/.
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Este estudo teve como objetivo geral analisar a evolução clínica e a QVRS de pacientes em Diálise Peritoneal (DP), dois anos após a primeira avaliação. Trata-se de uma pesquisa observacional, descritiva e analítica de delineamento longitudinal, realizada nos serviços de Diálise Peritoneal, no município de Ribeirão Preto, Estado de São Paulo, entre 2010 e 2012, tendo sido aprovada pelo Comitê de Ética em Pesquisa sob número 1451/201. A primeira e a segunda etapas de coleta de dados foram realizadas pela pesquisadora, por meio de entrevistas, utilizando os instrumentos: Miniexame do Estado Mental, questionário de caracterização sociodemográfica, econômica, clínica e laboratorial e o Kidney Disease and Quality of Life. Foi realizada a análise descritiva dos dados sociodemográficos, clínicos, laboratoriais e de QVRS. Na análise da evolução da QVRS, foi utilizado o teste t pareado. Na determinação das variáveis preditoras de QVRS, foram empregados o teste t de Student e o Mann-Whitney, bem como o coeficiente de Correlação de Pearson. Na análise de sobrevivência, foram calculados o risco relativo não ajustado e o seu intervalo de confiança. Para estimar o risco de óbito, foram obtidas, também, as curvas de sobrevida pelo método de Kaplan-Meier, e na análise multivadiada, foram determinados os preditores de óbito, utilizando o modelo de riscos proporcionais de Cox. O nível de significância adotado foi de 5%. Dos 82 participantes da primeira etapa do estudo em 2010, na etapa de 2012 houve perda de seguimento de sete pacientes, 18 foram excluídos da avaliação da QVRS, e 23 tiveram como desfecho o óbito. Portanto 34 pacientes tiveram a QVRS reavaliada, em 2012. A maioria era mulher 21; (61,8%), idosa 19 (55,9%), com cor da pele branca 25 (73,5%), morava com o companheiro 25 (73,5%), aposentada 25 (73,5%), hipertensa 33 (97,1%), estavam em Díalise Peritoneal Ambulatorial Contínua (DPAC) 18 (52,9%), apresentavam níveis de hemoglobina 25; (73,5%) e produto cálcio/fósforo 29 (85,3%) normais e de paratormônio 24 (70,6%) alterados. O número de comorbidades e de complicações aumentou de 2,8 e 4,3 para 3,2 e 5,1, respectivamente. No período, o número médio de peritonites foi de 1,0 episódio, e a média de internações foi de 1,6 vez. Em relação à QVRS, após dois anos da primeira avaliação, os pacientes que permaneceram em DP apresentaram piora, nos escores médios do Funcionamento físico e Dor e melhora no Bem-estar emocional. As variáveis preditoras de piora da QVRS no Funcionamento físico foram a idade avançada e os maiores números de comorbidades e de complicações; esta última também foi preditora de piora da QVRS na dimensão Dor, enquanto o menor número de peritonite foi preditor de melhora na dimensão Bem-estar emocional. Sobre a análise de sobrevivência, o risco aumentado para o desfecho óbito e/ou menor sobrevida se relacionou com ter diabetes, ter quatro comorbidades ou mais, estar em DPAC, ter escore de QVRS na dimensão Funcionamento físico menor que 50. Conclui-se que a QVRS piorou nas dimensões Funcionamento físico e Dor e melhorou para o Bem-estar emocional, dois anos após a primeira avaliação. A pior QVRS, especificamente na dimensão Funcionamento físico, pôde ser considerada preditora de óbitoThis study aimed to analyze the clinical evolution and HRQoL of patients under peritoneal dialysis (PD) two years after the first assessment. This is a longitudinal observational descriptive and analytical study performed in the Peritoneal Dialysis services in Ribeirão Preto, São Paulo state, between 2010 and 2012, previously approved by the Research Ethics Committee under number 1451/201. The first and second stages of data collection were performed by the researcher through interviews, using the following instruments: Mini Mental State Examination a questionnaire with sociodemographic, economic, clinical and laboratory data and the Kidney Disease and Quality of Life .A descriptive analysis of demographic, clinical, laboratory, and HRQoL data was performed. The paired t test was used for the analyzis of the HRQoL evolution. In order to determine the predictors of HRQoL, the Student\'s t test, the Mann-Whitney\'s test, and the Pearson\'s correlation coefficient were used. For the survival analysis, the unadjusted relative risk and its confidence interval were calculated. The risk of death was estimated through the Kaplan-Meier\'s survival curves. The predictors of death were determined by multivariate analysis through Cox proportional hazards model. The level of significance adopted was 5%. Out of the 82 participants in the first stage of the study in 2010, seven had been lost to follow in the 2012 step, 18 were excluded from the assessment of HRQoL and 23 had died. Therefore, 34 patients had HRQoL reassessed in 2012. Most were women 21 (61.8%), elderly 19 (55.9%), caucasian 25, (73.5%) lived with a partner 25, (73.5%), retired 25 (73.5%), hypertensive 33 (97.1%), under Continuous Ambulatory Peritoneal Dialysis (CAPD) 18 (52.9%), with normal hemoglobin 25 (73.5%) and calcium-P product levels 29 (85.3%) and altered parathyroid hormone levels 24 (70.6%). The number of comorbidities and complications increased from 2.8 and 4.3 to 3.2 and 5.1, respectively. During the follow-up period, the average number of peritonitis episodes was 1.0, and the average number of hospitalizations was 1.6. Regarding HRQoL, two years after initial assessment, patients who remained on PD had worse mean scores of Physical functioning and Pain and better Emotional well- being. The predictors of worsening HRQoL Physical functioning were older age and greater numbers of comorbidities and complications. A greater number of complications was also a predictor of worsening HRQoL Pain, whereas a lower number of peritonitis episodes was predictive of improvement in the Emotional well- being dimension. On the survival analysis, the increased risk for the outcome of death and/or shorter survival was associated with having diabetes, having four or more comorbidities, being under CAPD and having a HRQoL score smaller than 50 in the Physical functioning dimension. It was concluded that HRQoL was worse in the Physical functioning and Pain dimensions and improved in the Emotional well-being dimension two years after the first assessment. Worse HRQoL, specifically in the Physical functioning dimension, was a predictor of death
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Rekik, Islem. "Novel mathematical modeling approaches to assess ischemic stroke lesion evolution on medical imaging." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/10033.
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Stroke is a major cause of disability and death worldwide. Although different clinical studies and trials used Magnetic Resonance Imaging (MRI) to examine patterns of change in different imaging modalities (eg: perfusion and diffusion), we still lack a clear and definite answer to the question: “How does an acute ischemic stroke lesion grow?” The inability to distinguish viable and dead tissue in abnormal MR regions in stroke patients weakens the evidence accumulated to answer this question, and relying on static snapshots of patient scans to fill in the spatio-temporal gaps by “thinking/guessing” make it even harder to tackle. Different opposing observations undermine our understanding of ischemic stroke evolution, especially at the acute stage: viable tissue transiting into dead tissue may be clear and intuitive, however, “visibly” dead tissue restoring to full recovery is still unclear. In this thesis, we search for potential answers to these raised questions from a novel dynamic modelling perspective that would fill in some of the missing gaps in the mechanisms of stroke evolution. We divided our thesis into five parts. In the first part, we give a clinical and imaging background on stroke and state the objectives of this thesis. In the second part, we summarize and review the literature in stroke and medical imaging. We specifically spot gaps in the literature mainly related to medical image analysis methods applied to acute-subacute ischemic stroke. We emphasize studies that progressed the field and point out what major problems remain. Noticeably, we have discovered that macroscopic (imaging-based) dynamic models that simulate how stroke lesion evolves in space and time were completely overlooked: an untapped potential that may alter and hone our understanding of stroke evolution. Progress in the dynamic simulation of stroke was absent –if not inexistent. In the third part, we answer this new call and apply a novel current-based dynamic model âpreviously applied to compare the evolution of facial characteristics between Chimpanzees and Bonobos [Durrleman 2010] – to ischemic stroke. This sets a robust numerical framework and provides us with mathematical tools to fill in the missing gaps between MR acquisition time points and estimate a four-dimensional evolution scenario of perfusion and diffusion lesion surfaces. We then detect two characteristics of patterns of abnormal tissue boundary change: spatial, describing the direction of change –outward as tissue boundary expands or inward as it contracts–; and kinetic, describing the intensity (norm) of the speed of contracting and expanding ischemic regions. Then, we compare intra- and inter-patients estimated patterns of change in diffusion and perfusion data. Nevertheless, topology change limits this approach: it cannot handle shapes with different parts that vary in number over time (eg: fragmented stroke lesions, especially in diffusion scans, which are common). In the fourth part, we suggest a new mathematical dynamic model to increase rigor in the imaging-based dynamic modeling field as a whole by overcoming the topology-change hurdle. Metamorphosis. It morphs one source image into a target one [Trouvé 2005]. In this manuscript, we extend it into dealing with more than two time-indexed images. We propose a novel extension of image-to-image metamorphosis into longitudinal metamorphosis for estimating an evolution scenario of both scattered and solitary ischemic lesions visible on serial MR. It is worth noting that the spatio-temporal metamorphosis we developed is a generic model that can be used to examine intensity and shape changes in time-series imaging and study different brain diseases or disorders. In the fifth part, we discuss our main findings and investigate future directions to explore to sharpen our understanding of ischemia evolution patterns.
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Cadario, Alessandro. "Life prediction and mechanisms for the initiation and growth of short cracks under fretting fatigue loading." Doctoral thesis, KTH, Hållfasthetslära (Inst.), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4185.
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Fretting fatigue is a damage process that may arise in engineering applications where small cyclic relative displacements develop inside contacts leading to detrimental effects on the material fatigue properties. Fretting is located in regions not easily accessible, which makes it a dangerous phenomenon. It is therefore important to be able to make reliable predictions of the fretting fatigue lives. The work presented in this thesis has its focus on different aspects related to fretting fatigue in the titanium alloy Ti-17. A fretting experiment was developed which allowed for separate control of the three main fretting loads. Initially, the evolution of the coefficient of friction inside the slip region was investigated experimentally and analytically. Subsequently, 28 fretting tests were performed in which large fatigue cracks developed. The fretting tests were firstly evaluated with respect to fatigue crack initiation through five multiaxial fatigue criteria. The criteria predicted a too high fretting fatigue limit. A possible clue to the discrepancy was found in the fretting induced surface roughness with the asperity-pit interactions. The fatigue growth of the large fretting cracks was numerically modelled through a parametric crack growth procedure. The predicted lives were compared to the experimental outcome. The numerical simulations showed that linear elastic fracture mechanics was an appropriate tool for the prediction of fretting fatigue propagation lives in the long crack regime. Fatigue cracks spend most of their propagation life in the small crack regime. The possibility of modelling the small crack behaviour is therefore very important from the engineering point of view. The fatigue growth of through thickness short cracks was studied experimentally and numerically in the four-point bend configuration. It was found that linear elastic fracture mechanics and closure-free material growth data furnished conservative estimates for cracks longer than 50 μm. One method to improve fretting fatigue life is to shot peen the contact surfaces. Experimental results on fretting life with or without shot peening were simulated. The fatigue life enhancement in shot peened specimens could be explained by slower crack growth in the surface material layer with residual compressive stresses.QC 20100827
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Duda, Anna. "A longitudinal analysis of evolution in HIV-1 pol and gag genes in patients sampled fron acute to chronic infection." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504387.
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Brumbach, Barbara Hagenah. "Effects of Harsh and Unpredictable Environments in Adolescence on Development of Life History Strategies: A Longitudinal Test of an Evolutionary Model." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195336.
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The National Longitudinal Study of Adolescent Health was used to test predictions from life history theory. It was hypothesized that (1) in young adulthood an emerging life history strategy would exist as a common factor underlying many life history traits (e.g., health, relationship stability, and economic success), (2) both environmental harshness and unpredictability would account for unique variance in expression of adolescent and young adult life history strategies, and (3) adolescent life history traits would predict young adult life history strategy. These predictions were supported. The current findings suggest that the environmental parameters of harshness and unpredictability have concurrent effects on life history development in adolescence, as well as longitudinal effects into young adulthood. In addition, life history traits appear to be stable across developmental time from adolescence into young adulthood.
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McGann, Sean T. "Coping With the Unplanned: The Dynamics of Improvisation in Information Systems Evolution Within and Across Firm Boundaries." online version, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1099445579.
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Thesis (Ph. D.)--Case Western Reserve University, 2005.Department of Information Systems, Weatherhead School of Management. Includes bibliographical references. Available online via OhioLINK's ETD Center.
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Hanke, Hauke. "Rigorous derivation of two-scale and effective damage models based on microstructure evolution." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2014. http://dx.doi.org/10.18452/17031.
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Diese Dissertation beschäftigt sich mit der rigorosen Herleitung effektiver Modelle zur Beschreibung von Schädigungsprozessen. Diese effektiven Modelle werden für verschiedene raten-unabhängige Schädigungsmodelle linear elastischer Materialien hergeleitet. Den Ausgangspunkt stellt dabei ein unidirektionales Mikrostrukturevolutionsmodell dar, dessen Fundament eine Familie geordneter zulässiger Mikrostrukturen bildet. Jede Mikrostruktur dieser Familie besitzt die gleiche intrinsische Längenskala. Zur Herleitung eines effektiven Modells wird das asymptotische Verhalten dieser Längenskala mittels Techniken der Zwei-Skalen-Konvergenz untersucht. Um das Grenzmodell zu identifizieren, bedarf es einer Mikrostrukturregularisierung, die als diskreter Gradient für stückweise konstante Funktionen aufgefasst werden kann. Die Mikrostruktur des effektiven Modells ist punktweise durch ein Einheitszellenproblem gegeben, welches die Mikro- von der Makroskala trennt. Ausgehend vom Homogenisierungsresultat für die unidirektionale Mikrostrukturevolution werden effektive Modelle für Zwei-Phasen-Schädungsprozesse hergeleitet. Die aus zwei Phasen bestehende Mikrostruktur der mikroskopischen Modelle ermöglicht z.B. die Modellierung von Schädigung durch das Wachstum von Inklusionen aus geschädigtem Material verschiedener Form und Größe. Außerdem kann Schädigung durch das Wachstum mikroskopischer Hohlräume und Mikrorissen betrachtet werden. Die Größe der Defekte skaliert mit der intrinsischen Längenskala und die unidirektionale Mikrostrukturevolution verhindert, dass bei fixierter Längenskala die Defekte für fortlaufende Zeit schrumpfen. Das Material des Grenzmodells ist dann in jedem Punkt als Mischung von ungeschädigtem und geschädigtem Material durch das Einheitszellenproblem gegeben. Dabei liefert das Einheitszellenproblem nicht nur das Mischungsverhältnis sondern auch die genaue geometrische Mischungsverteilung, die dem effektiven Material des jeweiligen Materialpunktes zugrunde liegt.This dissertation at hand deals with the rigorous derivation of such effective models used to describe damage processes. For different rate-independent damage processes in linear elastic material these effective models are derived as the asymptotic limit of microscopic models. The starting point is represented by a unidirectional microstructure evolution model which is based on a family of ordered admissible microstructures. Each microstructure of that family possesses the same intrinsic length scale. To derive an effective model, the asymptotic behavior of this intrinsic length scale is investigated with the help of techniques of the two-scale convergence. For this purpose, a microstructure-regularizing term, which can be understood as a discrete gradient for piecewise constant functions, is needed to identify the limit model. The microstructure of the effective model is given pointwisely by a so-called unit cell problem which separates the microscopic scale from the macroscopic scale. Based on these homogenization results for unidirectional microstructure evolution models, effective models for brutal damage processes are provided. There, the microstructure consists of only two phases, namely undamaged material which comprises defects of damaged material with various sizes and shapes. In this way damage progression can be modeled by the growth of inclusions of weak material, the growth of voids, or the growth of microscopic cracks. The size of the defects is scaled by the intrinsic length scale and the unidirectional microstructure evolution prevents that, for a fixed length scale, the defects shrink for progressing time. According to the unit cell problem, the material of the limit model is then given as a mixture of damaged and undamaged material. In a specific material point of the limit model, that unit cell problem does not only define the mixture ratio but also the exact geometrical mixture distribution.
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Pessoa, Matilde da Conceição [UNESP]. "Estudo do valor adaptativo anual de fêmeas da raça Nelore utilizando modelos de regressão aleatória." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/92548.
Full textAbstract:
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O Objetivo deste trabalho foi avaliar o valor adaptativo anual para possível utilização como critério de seleção para a eficiência reprodutiva de fêmeas da raça Nelore. Foram estudadas medidas de valor adaptativo do 4º ao 13º ano de permanência no rebanho de 21.610 fêmeas. Os valores adaptativos anuais foram calculados com base na capacidade de sobrevivência e no número de crias deixado ano após ano. O modelo de melhor ajuste aos dados, segundo os critérios adotados, foi o de 5ª ordem para a tendência média da população, 5ª ordem para o efeito genético aditivo direto e 3ª ordem para efeito de ambiente permanente de animal. O modelo heterogêneo com 10 classes foi o mais adequado na modelagem da das variâncias residuais. As herdabilidades para valor adaptativo anual aumentaram com a idade dos animais (0,05 a 0,55). As correlações entre os valores adaptativos em diferentes idades foram baixas nas idades menores e altas entre as idades adultas. A tendência genética para valor adaptativo anual foi realizada com base nos valores genéticos preditos referentes às medidas adaptativas do 4º (Pti4), 8º(Pti8) e 13º(Pti13) ano de idade. Como critério de comparação foram utilizadas as características idade ao primeiro parto (Ipp) e stayability (Stay). As associações entre os valores genéticos preditos das características foram feitas utilizando a correlação de Pearson e porcentagem de touros coincidentes. Estimativas de herdabilidade para Ipp, Stay1 e Stay2 foram respectivamente 0,12, 0,33 e 0,40. As tendências genéticas indicaram que houve ganhos para Pti4 e Pti13 e, para Pti8 as médias dos valores genéticos se mantiveram quase que constantes com o passar dos anos. As associações entre os valores genéticos indicaram maior associação entre valores genéticos preditos para valor adaptativo medido no 4º ano e valores genéticos preditos para as características Ipp e Stay
The objective of this study was to evaluate the annual Fitness as selection criteria for reproductive performance of Nelore cows. We studied measures of fitness of the 4th to the 13th year of stayability of 21,610 females. The annual fitness was calculated based on survivability and the number of offspring left year after year. The most appropriate model, according to criteria adopted, was a 5th order for the average trend of the population, 5th order for the direct genetic effect and 3th order for the permanent environmental effect of animal. The heterogeneous model with 10 classes was the most appropriated in modeling of residual variances. Heritability estimates for annual fitness increased with age of animals (0.05 to 0.55). The correlations between fitness at ages different were lower in younger ages, and high among the adult ages. The genetic trend for annual fitness was based on predicted breeding values to adaptive measures relating to the 4th (Pti4), 8th (Pti8) and 13th (Pti13) years of age. As criterion for comparison were used the traits age at first calving (IPP) and stayability (Stay). The associations between predicted breeding values of traits were made using Pearson correlation and percentage of bulls coincide. Heritability estimates for Ipp, and Stay1 Stay2 were respectively 0.12, 0.33 and 0.40. The genetic trends indicated that there were gains for Pti4 and Pti13, however for Pti8, the average genetic values remained almost constant over the years. The associations between breeding values indicate greater association between breeding values for annual fitness measured in year 4th year and the breeding values for the traits Ipp and Stay
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Almonbhi, Ali O. "Effectiveness of Waterproofing Membranes for Precast Prestressed Concrete Adjacent Box-Beam Bridges." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1522880974567767.
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Krol, Agnieszka. "Consideration of multiple events for the analysis and prediction of a cancer evolution." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0329.
Full textAbstract:
Le nombre croissant d’essais cliniques pour le traitement du cancer a conduit à la standardisation de l’évaluation de la réponse tumorale. Dans les essais cliniques de phase III des cancers avancés, la survie sans progression est souvent appliquée comme un critère de substitution pour la survie globale. Pour les tumeurs solides, la progression est généralement définie par les critères RECIST qui utilisent l’information sur le changement de taille des lésions cibles et les progressions de la maladie non-cible. Malgré leurs limites, les critères RECIST restent l’outil standard pour l’évaluation des traitements. En particulier, la taille tumorale mesurée au cours de temps est utilisée comme variable ponctuelle catégorisée pour identifier l’état d’un patient. L’approche statistique de la modélisation conjointe permet une analyse plus précise des marqueurs de réponse tumorale et de la survie. En outre, les modèles conjoints sont utiles pour les prédictions dynamiques individuelles. Dans ce travail, nous avons proposé d’appliquer un modèle conjoint trivarié pour des données longitudinales (taille tumorale), des évènements récurrents (les progressions de la maladie non-cible) et la survie. En utilisant des mesures de capacité prédictive, nous avons comparé le modèle proposé avec un modèle pour les progressions tumorales, définies selon les critères standards et la survie. Pour un essai clinique randomisé porté sur le cancer colorectal, nous avons trouvé une meilleure capacité prédictive du modèle proposé. Dans la deuxième partie, nous avons développé un logiciel en libre accès pour l’application de l’approche de modélisation conjointe proposée et les prédictions. Enfin, nous avons étendu le modèle à une analyse plus sophistiquée de l’évolution tumorale à l’aide d’un modèle mécaniste. Une équation différentielle ordinaire a été mise en œuvre pour décrire la trajectoire du marqueur biologique en tenant compte les caractéristiques biologiques de la croissance tumorale. Cette nouvelle approche contribue à la recherche clinique sur l’évaluation d’un traitement dans les essais cliniques grâce à une meilleure compréhension de la relation entre la réponse tumorale et la survieThe increasing number of clinical trials for cancer treatments has led to standardization of guidelines for evaluation of tumor response. In phase III clinical trials of advanced cancer, progression-free survival is often applied as a surrogate endpoint for overall survival (OS). For solid tumors, progression is usually defined using the RECIST criteria that use information on the change of size of target lesions and progressions of non-target disease. The criteria remain the standard tool for treatment evaluation despite their limitations. In particular, repeatedly measured tumor size is used as a pointwise categorized variable to identify a patient’s status. Statistical approach of joint modeling allows for more accurate analysis of the tumor response markers and survival. Moreover, joint models are useful for individual dynamic predictions of death using patient’s history. In this work, we proposed to apply a trivariate joint model for a longitudinal outcome (tumor size), recurrent events (progressions of non-target disease) and survival. Using adapted measures of predictive accuracy we compared the proposed joint model with a model that considered tumor progressions defined within standard criteria and OS. For a randomized clinical trial for colorectal cancer patients, we found better predictive accuracy of the proposed joint model. In the second part, we developed freely available software for application of the proposed joint modeling and dynamic predictions approach. Finally, we extended the model to a more sophisticated analysis of tumor size evolution using a mechanistic model. An ordinary differential equation was implemented to describe the trajectory of the biomarker regarding the biological characteristics of tumor size under a treatment. This new approach contributes to clinical research on treatment evaluation in clinical trials by better understanding of the relationship between the markers of tumor response with OS
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Pessoa, Matilde da Conceição. "Estudo do valor adaptativo anual de fêmeas da raça Nelore utilizando modelos de regressão aleatória /." Jaboticabal : [s.n.], 2011. http://hdl.handle.net/11449/92548.
Full textAbstract:
Orientador: Henrique Nunes de OliveiraBanca: Marcilio Dias Silveira da Mota
Banca: Maria Eugênia Zerlotti Mercadante
Resumo: O Objetivo deste trabalho foi avaliar o valor adaptativo anual para possível utilização como critério de seleção para a eficiência reprodutiva de fêmeas da raça Nelore. Foram estudadas medidas de valor adaptativo do 4º ao 13º ano de permanência no rebanho de 21.610 fêmeas. Os valores adaptativos anuais foram calculados com base na capacidade de sobrevivência e no número de crias deixado ano após ano. O modelo de melhor ajuste aos dados, segundo os critérios adotados, foi o de 5ª ordem para a tendência média da população, 5ª ordem para o efeito genético aditivo direto e 3ª ordem para efeito de ambiente permanente de animal. O modelo heterogêneo com 10 classes foi o mais adequado na modelagem da das variâncias residuais. As herdabilidades para valor adaptativo anual aumentaram com a idade dos animais (0,05 a 0,55). As correlações entre os valores adaptativos em diferentes idades foram baixas nas idades menores e altas entre as idades adultas. A tendência genética para valor adaptativo anual foi realizada com base nos valores genéticos preditos referentes às medidas adaptativas do 4º (Pti4), 8º(Pti8) e 13º(Pti13) ano de idade. Como critério de comparação foram utilizadas as características idade ao primeiro parto (Ipp) e stayability (Stay). As associações entre os valores genéticos preditos das características foram feitas utilizando a correlação de Pearson e porcentagem de touros coincidentes. Estimativas de herdabilidade para Ipp, Stay1 e Stay2 foram respectivamente 0,12, 0,33 e 0,40. As tendências genéticas indicaram que houve ganhos para Pti4 e Pti13 e, para Pti8 as médias dos valores genéticos se mantiveram quase que constantes com o passar dos anos. As associações entre os valores genéticos indicaram maior associação entre valores genéticos preditos para valor adaptativo medido no 4º ano e valores genéticos preditos para as características Ipp e Stay
Abstract: The objective of this study was to evaluate the annual Fitness as selection criteria for reproductive performance of Nelore cows. We studied measures of fitness of the 4th to the 13th year of stayability of 21,610 females. The annual fitness was calculated based on survivability and the number of offspring left year after year. The most appropriate model, according to criteria adopted, was a 5th order for the average trend of the population, 5th order for the direct genetic effect and 3th order for the permanent environmental effect of animal. The heterogeneous model with 10 classes was the most appropriated in modeling of residual variances. Heritability estimates for annual fitness increased with age of animals (0.05 to 0.55). The correlations between fitness at ages different were lower in younger ages, and high among the adult ages. The genetic trend for annual fitness was based on predicted breeding values to adaptive measures relating to the 4th (Pti4), 8th (Pti8) and 13th (Pti13) years of age. As criterion for comparison were used the traits age at first calving (IPP) and stayability (Stay). The associations between predicted breeding values of traits were made using Pearson correlation and percentage of bulls coincide. Heritability estimates for Ipp, and Stay1 Stay2 were respectively 0.12, 0.33 and 0.40. The genetic trends indicated that there were gains for Pti4 and Pti13, however for Pti8, the average genetic values remained almost constant over the years. The associations between breeding values indicate greater association between breeding values for annual fitness measured in year 4th year and the breeding values for the traits Ipp and Stay
Mestre
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Simova, Jozefina. "Market structure and evolution of the clothing retail sector in the Czech Republic under the specific conditions of a transition economy : an empirical investigation of structural change issues of the sector using a longitudinal study between the years 19." Thesis, University of Huddersfield, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368308.
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Hagos, Bereket Abrha. "Microstructural and chemical behaviour of irradiated graphite waste under repository conditions." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/microstructural-and-chemical-behaviour-of-irradiated-graphite-waste-under-repository-conditions(45b519ef-2f67-4aca-9b92-94a975e12875).html.
Full textAbstract:
A procedure to evaluate the leaching properties of radionuclides from irradiated graphite waste has been developed by combining ANSI 16.1 (USA) and NEN 7345 (Netherlands) standardised diffusion leaching techniques. The ANSI 16.1 standard has been followed to the acquire the leachates and to determine the leach rate/ diffusion coefficient and NEN 7345 standard technique has been used to determine the diffusion mechanism of radionuclides. The investigation employs simulated Drigg groundwater as a leachant using semi-dynamic technique for the production of leachate specimens. From gamma spectroscopy analysis the principal radionuclides present in terms of activity were 60Co, 137Cs, 134Cs, 155Eu, 133Ba and 46Sc. The dominant radionuclides are 60Co, 134Cs and 133Ba which together account for about 91 % of the total activity. The 91 % can be broken down into 73.4 % 60Co, 9.1 % 134Cs and 8.1 % 133Ba. Analysis of total beta and total beta without tritium activity release from Magnox graphite was measured using liquid scintillating counting. Preliminary results show that there is an initial high release of activity and decreases when the leaching period increases. This may be due to the depletion of contaminants which were absorbed by the internal pore networks and the surface. During the leaching test approximately 275.33 ± 18.20 Bq of 3H and 106.26 ± 7.01 Bq of 14C was released into the leachant within 91 days. Irradiation induced damages to the nuclear graphite crystal structure have been shown to cause disruption of the bonding across the basal planes. Moreover, the closures of Mrozowski cracks have been observed in nuclear graphite, the bulk property are governed by the porosity, in particular, at the nanometre scale. Therefore, knowledge of the crystallite structure and porosity distribution is very important; as it will assist in understand the affects of irradiated damage and location and the mechanism of the leaching of radionuclides. The work reported herein contributed several key findings to the international work on graphite leaching to offer guidance leading toward obtaining leaching data in the future: (a) the effective diffusion coefficient for 14C from graphite waste has been determined. The diffusion process for 14C has two stages resulting two different values of diffusion coefficient, i.e., for the fast and slow components; (b) the controlling leaching mechanism for 3H radionuclide from graphite is shown to be surface wash–off; and for that of 14C radionuclide the initial controlling leaching mechanism is surface wash-off following by diffusion which is the major transport mechanism ; (c) The weight loss originates from the open pore structure which has been opened up by radiolytic oxidation; at the higher weight losses much of the closed porosity in the graphite has been opened. The investigation indicates that weigh loss has a major influence on the leaching of elements from the irradiated graphite; and (d) the analysis of the pores in nuclear graphite can be categorised into three types. These three types of pores are: (1) small pores narrow which are slit-shaped pores in the binder phase or matrix, (2) gas evolution pores or gas entrapment pores within the binder phase or matrix and (3) lenticular pores which are large cracks within the filler particles. It is shown in this thesis that by using tomography to study the morphology of the different pores coupled with the distribution of impurities an understanding of the role of porosity in leaching is possible.
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Chang, Yang-Hui, and 張揚揮. "Crack Shape Evolution of Three-Dimensional Fatigue Cracks." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/21726238203286417130.
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碩士國立暨南國際大學
土木工程學系
103
Fatigue is the main reason that causing heavy casualties in steel structures. In many cases of steel structure which have been fatigue failure, most of the fatigue crack initiate at the toe of weld. Because the irregular geometry of weld toe, small cracks will start from weld toe after the force loading of the members. The rate of crack growth will be faster after various cracks combined, also the crack shape will change drastically. This study use finite element method with the previous theory and establish a set of automated computer program to simulate the foregoing growth process. The result showed that whether the initial crack shape is semicircular or very shallow, the value of aspect ratio is between 0.6 and 0.8 in the last stage of growth. And the maximum length of crack growth, , model width, b and height, h, are insignificant on crack shape growth simulation. This study also discuss the crack shape evolution of two symmetrical coplanar semi-elliptical after crack combined. The simulation results show that the greater distance between the center of the semi-elliptical and plane of symmetry, the required distance of the leading edge of two cracks grows into a single smooth curve is also larger.
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Konishi, Junpei. "Modelling of the formation of longitudinal facial cracks in the continuous casting of steel slabs." Thesis, 1996. http://hdl.handle.net/2429/4508.
Full textAbstract:
Longitudinal facial cracks are a serious quality problem in the continuous casting
of steel slabs. Although numerous investigations have been conducted to eliminate this
kind of surface defect, and significant improvement has been achieved, there is still a
problem especially operating at high casting speeds. Thus, to improve both productivity
and quality, additional research is required.
The purpose of this study is to understand the mechanism of formation of
longitudinal facial cracks in the continuous casting process of peritectic steels and to
propose methods to eliminate the formation of these defects. To achieve this objective,
process modeling approach was applied.
Firstly, the delta-to-gamma transformation was modeled numerically assuming
carbon diffusion control. The moving boundary (delta/gamma interface) problem was
solved by employing a one-dimensional finite-difference method. The result of this
calculation shows considerably rapid transformation from delta to gamma due to the high
diffusivity of carbon in this temperature range.
Secondly, a heat transfer model of continuous casting of steel was developed and
was combined with the phase transformation model. Three heat flux conditions (i.e., low,
medium, and high) were obtained from literature data and applied as the thermal boundary
condition. Differences in the delta-to-gamma transformation rate were compared for the
heat flux conditions investigated. The results of the coupled model indicated that the
difference in the heat flux at the meniscus results in large variations of the transformation
rate in the meniscus region. The results of the coupled model were transformed to fictitious temperature by
using an steel shrinkage model and adopted to calculate the stresses in the solid shell
applying the commercial finite-element program, ABAQUS. Based on the results of the
calculations, it was concluded that, in order to generate a longitudinal crack on the solid
shell surface, not only the tensile stress caused by rapid transformation (i.e. rapid cooling)
but also the presence of hot spots is required.
The threshold values for the retardation of both heat removal at the meniscus and
shell growth required to generate longitudinal cracks were obtained; in the present work,
the values were approximately 10% and 16%, respectively.
Based on the findings of this study, uniform heat removal in the meniscus region is
of utmost important to eliminate the longitudinal cracks. If uniformity in the heat
extraction is achieved, even under high heat flux condition, the tensile stress at the shell
surface does not exceed the UTS of the shell surface and cracking will not occur.
However, as heat flux increases (i.e., cooling rate increases), the maximum
temperature fluctuation permissible before cracking occurs decreases. Thus, ironically, the
practical way to eliminate longitudinal cracks when casting at high speeds is to reduce the
heat flux in the meniscus region in conjunction with the elimination of non-uniform heat
extraction.
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"HIV Evolution: Biogeography and Intra-Individual Dynamics." Doctoral diss., 2013. http://hdl.handle.net/2286/R.I.18104.
Full textAbstract:
abstract: The entire history of HIV-1 is hidden in its ten thousand bases, where information regarding its evolutionary traversal through the human population can only be unlocked with fine-scale sequence analysis. Measurable footprints of mutation and recombination have imparted upon us a wealth of knowledge, from multiple chimpanzee-to-human transmissions to patterns of neutralizing antibody and drug resistance. Extracting maximum understanding from such diverse data can only be accomplished by analyzing the viral population from many angles. This body of work explores two primary aspects of HIV sequence evolution, point mutation and recombination, through cross-sectional (inter-individual) and longitudinal (intra-individual) investigations, respectively. Cross-sectional Analysis: The role of Haiti in the subtype B pandemic has been hotly debated for years; while there have been many studies, up to this point, no one has incorporated the well-known mechanism of retroviral recombination into their biological model. Prior to the use of recombination detection, multiple analyses produced trees where subtype B appears to have first entered Haiti, followed by a jump into the rest of the world. The results presented here contest the Haiti-first theory of the pandemic and instead suggest simultaneous entries of subtype B into Haiti and the rest of the world. Longitudinal Analysis: Potential N-linked glycosylation sites (PNGS) are the most evolutionarily dynamic component of one of the most evolutionarily dynamic proteins known to date. While the number of mutations associated with the increase or decrease of PNGS frequency over time is high, there are a set of relatively stable sites that persist within and between longitudinally sampled individuals. Here, I identify the most conserved stable PNGSs and suggest their potential roles in host-virus interplay. In addition, I have identified, for the first time, what may be a gp-120-based environmental preference for N-linked glycosylation sites.Dissertation/Thesis
Ph.D. Molecular and Cellular Biology 2013
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Munoz, Paul Renato Alulema, and Paul Renato Alulema Munoz. "The Evolution and Innovation of Taiwanese Computer Firms: A Longitudinal Study of Acer and Asus." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/46781104039801557573.
Full textAbstract:
碩士國立臺灣科技大學
管理學院MBA
102
The purpose of this study is to explore how the Taiwanese computer firms evolved and innovate to reach with the leading ones in the global market. During the last decades, Taiwanese firms have moved beyond imitation to produce innovative products and services. The transition from contract manufacturing to own brand manufacturing represents a crucial and important characteristic for the innovation of these firms. This paper uses the literature research methodology that incorporates a non-structured qualitative analysis, which is the best method for data collection and analyzing complex facts through a detailed understanding of the organizational process. Acer and Asus were chosen for the analysis, as the top two Taiwanese computer firms, they guarantee a good understanding of this industry. A comparison between both companies is made at the end of the study to analyze the similarities and differences in their evolution and innovation activities. Specifically, this paper aims to study (a) how a Taiwanese computer firm evolved over time and (b) how these firms managed their innovation by exploring and exploiting their assets of market and technology. The analysis about the development from exploration to exploitation of their market and technology can contribute to the ongoing research about the innovation literature in the developing countries.
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Pina, Deolinda Maria Pires. "Estudo longitudinal do grupo, equipa de atletismo do desporto escolar do agrupamento de escolas de Vilar Formoso." Master's thesis, 2010. http://hdl.handle.net/10400.6/2288.
Full textAbstract:
O Projecto do Desporto Escolar do Agrupamento de Escolas de Vilar
Formoso tem identificado o atletismo como uma modalidade prioritária no
desenvolvimento desportivo local, tendo como objectivo aumentar o número de
praticantes e criar condições para a melhoria das marcas obtidas.
Neste contexto, este trabalho analisa o impacto dos resultados obtidos na
modalidade e o aumento do número de praticantes do Grupo/Equipa do Clube de
Desporto Escolar do Agrupamento de Escolas de Vilar Formoso em jovens de
idade compreendida entre os 10 e os 15 anos, e avalia se as metodologias
aplicadas e os recursos existentes, serão os mais adequados para que os alunos
obtenham uma evolução positiva a nível do género?
Na metodologia utilizara-se tabelas e gráficos elaborados no programa
Excel para registo das marcas e análise dos resultados.
A amostra foi constituída por vinte e dois alunos, sendo cinco do sexo
masculino e dezassete do sexo feminino.
Os dados recolhidos referem-se aos resultados obtidos nas provas que
constituem do quadro competitivo do Atletismo do Desporto Escolar para os
escalões de Infantis e Iniciados, em dois momentos do quadro competitivo, em
cada ano escolar, nomeadamente, os anos lectivos de 2007/2008, 2008/2009 e
2009/2010.
Os resultados obtidos permitem evidenciar a influência no aumento do
número de praticantes de atletismo, dos seis alunos inscritos no ano de
2007/2008, verificou-se um aumento para vinte e dois, no ano lectivo de
2009/2010.
Houve uma evolução positiva, na maioria dos alunos, nas marcas
alcançadas do primeiro para o segundo momento de competição.
No escalão de iniciados femininos, registou-se uma melhoria bastante
significativa nas marcas alcançadas do primeiro para o sexto momento, em quase
todas as provas, encontrando-se em algumas delas, bastante próximas do
recorde distrital da Associação de Atletismo da Guarda.The Desporto Escolar Project from the Agrupamento de Escolas de Vilar Formoso has identified athletics as a priority discipline in local sports development, with the main objectives being the increase in the number of practitioners and to create conditions for improvement of the marks obtained. In this context, this work analyzes the impact of the results obtained in this discipline and the increasing number of practitioners of the Grupo/Equipa do Clube de Desporto Escolar do Agrupamento de Escolas de Vilar Formoso in young people aged between 10 and 15 years, and assesses if the methodologies applied and the existing resources are the most appropriate for students to obtain a positive development? The methodology applied in this work used Excel tables and graphs to register the marks obtained and analyze the results. The sample of individuals consisted of twenty two students, five males and seventeen females. The data collected refer to the results obtained in the competitions that constitute the competitive framework of the Atletismo do Desporto Escolar for Kids and Beginners, at two points of the competitive framework in each school year, specifically for the academic years of 2007/2008, 2008/2009 and 2009/2010. The results obtained showed an increase in the number of practitioners of athletics, as the number increased from six students enrolled in the academic year of 2007/2008 to twenty two students in the academic year of 2009/2010. There was a positive evolution in the marks obtained by most students, from the first to the second point of competition. In the female Kids level, a significant improvement was registered in the marks obtained from the first to the sixth point, in almost all of the events, with some of them being very close to the district record of the Associação de Atletismo da Guarda.
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Archary, Derseree. "Neutralizing antibody responses and viral evolution in a longitudinal cohort of HIV subtype C infected antiretroviral-naïve individuals." Thesis, 2011. http://hdl.handle.net/10413/8701.
Full textAbstract:
Background: HIV-1 envelope (Env) diversity is arguably the most significant challenge for the development of an efficacious vaccine. An ideal vaccine would elicit the production of broadly neutralizing antibodies (nAb), capable of retaining potent activity against a diverse panel of viral isolates. The evolutionary forces that shape the diversity of envelope and ensuing nAb responses are incompletely understood in HIV-1 subtype C infection, the dominant subtype globally. Therefore there is an urgent need to define the patterns of envelope diversity, determine the correlates of immune protection and to discover subtype C immunogens in order to develop a globally relevant vaccine.
Methods: We applied the single genome sequencing strategy to study plasma derived viruses from four slow progressors and four progressors over a median of 21 months between study entry and study exit. The participants‘ samples were from the Sinikithemba cohort of antiretroviral therapy-naïve chronically infected individuals and were termed slow progressors or progressors based on CD4 T-cell counts and viral loads over two years. We analyzed env sequence diversity, divergence patterns and envelope characteristics across the entire HIV-1 subtype C gp160. We studied the evolution of autologous nAb (AnAb) and heterologous nAb responses in order to test the hypothesis that slow disease progression is associated with more potent autologous or heterologous nAb responses. Furthermore, genotypic env characteristics were correlated to potency of neutralization in order to understand possible differences in nAb responses with divergent rates of disease progression and to describe genotypic differences associated with differential nAb potencies. In addition, the binding affinities of HIV-specific immunoglobulins (IgGs) and the affinities of the IgGs
to various Fcγ receptors (both activating- FcγRI, FcγRIIa, FcγRIIIa; inhibitory- FcγRIIb) were assessed. These binding affinities were used as a surrogate for the recruitment of effector functions of cells of the innate immune system e.g. macrophages or natural killer cells to initiate antibody-dependent cell-mediated cytotoxicity (ADCC) or antibody dependent cell-mediated viral inhibition (ADCVI) and these were correlated to markers of disease progression namely CD4 T-cell counts and viral loads.
Results: Intra-patient diversity was higher in slow progressors for regions C2 (p=0.0006), V3 (p=0.01) and C3 (p=0.005) compared to progressors. Consistent with this finding, slow progressors also had significantly increased amino acid length in V1-V4 with fewer potential N-linked glycosylation sites (PNGs) compared to progressors (p=0.009 and p=0.02 respectively). Similarly, in progressors, the gp41 region was significantly longer and had significantly fewer PNGs compared to slow progressors (p=0.02 for both parameters). Positive selection was prominent in regions V1, C3, V4, C4 and gp41 in slow progressors, whereas in progressors, it was prominent in gp41. Signature consensus sequence differences between the groups occurred mainly in gp41. Neutralizing antibodies (nAb) evolved over time in progressors, as evidenced by significantly higher nAb IC50 titers to baseline (study entry) viruses when tested against study exit time-point plasma compared to contemporaneous responses (p=0.003). In contrast, slow progressors‘ nAb titers did not differ significantly between study entry and study exit time points. nAb IC50 titers significantly correlated with amino acid lengths for C3-V5 (p=0.03) and V1-V5 (p=0.04) for slow progressors and V1-V2 for progressors (p=0.04). Slow progressors and progressors displayed preferential heterologous activity against the subtype C panel. There were no significant differences in breadth of responses between the groups for either subtype A or C. Neutralization breadth and titers to subtype B reference strains however, was significantly higher in progressors compared to slow progressors (both p<0.03) with increasing nAb
breadth from study entry to study exit in progressors. Progressors had cross-reactive neutralizing antibodies that targeted V2 and V3. Binding affinities of non-neutralizing antibodies to HIV-specific gp120, gp41 and p24 and to activating and inhibitory Fcγ receptors (FcγRs) were similar in both groups. However, in slow progressors, CD4 T-cell counts correlated inversely with antibody binding affinity for the activating FcγRIIa (p=0.005).
Conclusions: These data suggest that separate regions of Env are under differential selective forces, and the heterogeneity of env diversity and evolution differ with HIV-1 disease course. Single genome sequence analysis of circulating viruses in slow progressors and progressors indicate that diversity, length polymorphisms, sites under positive selection pressure, and PNGs consistently map to specific regions in Env. Cross-reactive neutralizing antibodies targeting epitopes in V2 and V3 indicate that nAb breadth may be dictated by a limited number of target Env epitopes. Certain key N-linked glycosylation sites were shown to be crucial for antibody neutralization. The potencies of autologous nAbs were directly affected by the amino acid lengths in certain regions of Env gp160 and by the numbers of PNGs. Target vaccine immunogens may have to be given over long periods of time and may have to include multiple subtype immunogens to elicit the production of potent, broad cross neutralizing antibodies with high binding affinity. Overall, the data suggest that neither nAbs nor non-neutralizing antibodies could be directly associated with disease attenuation in this cohort of chronically infected individuals. However, continuous evolution of nAbs was a potential marker of HIV-1 disease progression. Further studies on larger cohorts to identify people with potent nAbs and to identify specific targets of these antibodies are needed. Furthermore studies of non-neutralizing antibodies in HIV-1 infection using functional assays will be required in order to determine their role in HIV-1 pathogenesis.Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2011.
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Lampert, Curba Morris Ahuja Gautam Huber George P. "Learning and corporate evolution a longitudinal study of how product-market relatedness and environmental relatedness impact firm scope /." 2003. http://wwwlib.umi.com/cr/utexas/fullcit?p3116364.
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Lampert, Curba Morris. "Learning and corporate evolution : a longitudinal study of how product-market relatedness and environmental relatedness impact firm scope /." Thesis, 2003. http://wwwlib.umi.com/cr/utexas/fullcit?p3116364.
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[Verfasser], Tsigereda Biru Leulebirhan. "Characterization of the longitudinal HIV-1 quasispecies evolution in HIV-1 infected individuals co-infected with Mycobacterium tuberculosis / vorgelegt von Tsigereda Biru Leulebirhan." 2010. http://d-nb.info/1007737980/34.
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Zhao, Yufeng. "Stress-induced permeability evolution in coal: Laboratory testing and numerical simulations." 2020. https://tubaf.qucosa.de/id/qucosa%3A71758.
Full textAbstract:
Mining operations produce a multiscale network of fractures in the coal seams. Permeability evolution in rocks is important for coal bed methane (CBM) and shale gas exploitation as well as for greenhouse gas storage. Therefore, this work presents laboratory tests and a coupled model using PFC3D and FLAC3D to simulate the stress induced permeability evolution in coal samples. Basic mechanical properties are determined via lab testing. The spatial distributions of different components inside the reconstructed samples produce a significant heterogeneity based on CT technique. A newly developed experimental system is employed to perform 3-dimensional loading and to measure the flow rate simultaneously. The evolution process is described by 5 distinct phases in terms of permeability and deformation. Triaxial tests are simulated with PFC3D using a novel flexible wall boundary method. Gas seepage simulations are performed with FLAC3D. Relations between hydraulic properties and fracture data are established. Permeability and volumetric strain show good nonlinear exponential relation after a newly introduced expansion point. Piecewise relations fit the whole process, the expansion point can be treated as critical point. The structural characteristics of the samples influence this relation before and after the expansion point significantly.