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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Functional failure sequences in traffic accidents

Atalar, Deniz January 2018 (has links)
This thesis examines the interactions between road users and the factors that contribute to the occurrence of traffic accidents, and discusses the implications of these interactions with regards to driver behaviour and accident prevention measures. Traffic accident data is collected on a macroscopic level by local police authorities throughout the UK. This data provides a description of accident related factors on a macroscopic level which does not allow for a complete understanding of the interaction between the various road users or the influence of errors made by active road users. Traffic accident data collected on a microscopic level analysis of real world accident data, explaining why and how an accident occurred, can further contribute to a data driven approach to provide safety measures. This data allows for a better understanding of the interaction of factors for all road users within an accident that is not possible with other data collection methods. In the first part of the thesis, a literature review presents relevant research in traffic accident analysis and accident causation research, afterwards three accident causation models used to understand behaviour and factors leading to traffic accidents are introduced. A comparison study of these accident causation coding models that classify road user error was carried out to determine a model that would be best suited to code the accident data according to the thesis aims. Latent class cluster analyses were made of two separate datasets, the UK On the Spot (OTS) in-depth accident investigation study and the STATS19 national accident database. A comparison between microscopic (in-depth) accident data and macroscopic (national) accident data was carried out. This analysis allowed for the interactions between all relevant factors for the road users involved in the accident to be grouped into specific accident segmentations based on the cluster analysis results. First, all of the cases that were collected by the OTS team between the years 2000 to 2003 were analysed. Results suggested that for single vehicle accidents males and females typically made failures related to detection and execution issues, whereas male road users made diagnosis failures with speed as a particularly important factor. In terms of the multiple vehicle accidents the interactions between the first two road users and the subsequent accident sequence were demonstrated. A cluster analysis of all two vehicle accidents in Great Britain in the year 2005 and recorded within the STATS19 accident database was carried out as a comparison to the multiple vehicle accident OTS data. This analysis demonstrated the necessity of in-depth accident causation data in interpreting accident scenarios, as the resulting accident clusters did not provide significant differences between the groups to usefully segment the crash population. Relevant human factors were not coded for these cases and the level of detail in the accident cases did not allow for a discussion of countermeasure implications. An analysis of 428 Powered Two Wheeler accidents that were collected by the OTS team between the years 2000 to 2010 was carried out. Results identified 7 specific scenarios, the main types of which identified two particular looked but did not see accidents and two types of single vehicle PTW accidents. In cases where the PTW lost control, diagnosis failures were more common, for road users other than the PTW rider, detection issues were of particular relevance. In these cases the interaction between all relevant road users was interpreted in relation to one another. The subsequent study analysed 248 Pedestrian accidents that were collected by the OTS team between the years 2000 to 2010. Results identified scenarios related to pedestrians as being in a hurry and making detection errors, impairment due to alcohol, and young children playing in the roadside. For accidents that were initiated by the other road user s behaviour pedestrians were either struck after an accident had already occurred or due to the manoeuvre that a road user was making, older pedestrians were over-represented in this accident type. This thesis concludes by discussing how (1) microscopic in-depth accident data is needed to understand accident mechanisms, (2) a data mining approach using latent class clustering can benefit the understanding of failure mechanisms, (3) accident causation analysis is necessary to understand the types of failures that road users make and (4) accident scenario development helps quantify accidents and allows for accident countermeasure implication discussion. The original contribution to knowledge is the demonstration that when relevant data is available there is a possibility to understand the interactions that are occurring between road users before the crash, that is not possible otherwise. This contribution has been demonstrated by highlighting how latent class cluster analysis combined with accident causation data allows for relevant interactions between road users to be observed. Finally implications for this work and future considerations are outlined.
12

Segmentace trhu s využitím metod shlukové shlukové analýzy / The Market Segmentation with using Cluster Analysis Methods

MICHALOVÁ, Jitka January 2008 (has links)
This diploma work is called ``The Market Segmentation with using Cluster Analysis Methods``. This segmentation is made in the marketplace of tourism. The cluster analysis methods are classified into hierarchical and no hierarchical ones. The hierarchical methods are divided into the following methods: The nearest neighbour metod, The furthest neighbour metod, The weighted group metod. MacQueen K-means and Wishart methods are no hierarchical methods. In the work we can find the division of one informant into 5 groups according to two methods ( The furthest neighbour metod and MacQueen K-means). Each group has its own representative which consists of the most frequent answers. This information is exploited at sorting clients in turism.
13

Negotiating a path to professional efficacy: A narrative analysis of the experiences of four pre-service educators

Rogan, Ann I 06 June 2005 (has links)
Often studies examining the development of a sense of professional efficacy in pre-service educators are concerned with either the systemic viewpoint of teacher education programmes or the relationship between the perceptions of pre-service educators and what is “really” happening in the classroom. The intent of this study is to investigate the question “What do pre-service educators perceive that they know and that they need to know to develop a sense of professional efficacy? solely from the vantage point of the pre-service educator. The study encompasses two specific objectives: --- to identify through narrative analysis the circumstances of the construction of and the content of the knowledge created by the pre-service educators from their experiences --- to investigate and describe the relationship of the knowledge constructed by the pre-service educators to the development of a sense of professional efficacy. The study attempts to produce an in-depth qualitative description of the explicit and sometimes tacit perceptions of four pre-service educators as they prepared to begin professional careers. Four pre-service educators enrolled in a recently developed innovative Post Graduate Certificate of Education programme at a large urban university in South Africa participated in the study over a two year period. The perceptions of the pre-service educators are presented through an analysis of the narratives taken from interviews and reflective journal entries. The narratives are analyzed using a variety of narrative inquiry methods which were investigated and described as part of this study. The interpretation of the narratives is also informed by theoretical constructs such as professional efficacy and knowledge and private theory. Through the analysis and interpretation of the narratives the unique and individual nature of learning to become an educator as well as similarities of experience were revealed. Ultimately the broad aim of this study through the use of narrative inquiry methodology and methods is to add the “voices” of these pre-service educators to a larger dialogue and to the collective body of evidence of how one learns to become an educator with a sense of professional efficacy. / Thesis (PhD (Curriculum Studies))--University of Pretoria, 2006. / Curriculum Studies / unrestricted
14

Métodos lineares e não-lineares de análise de dados cronobiológicos de Melipona quadrifasciata (Hymenoptera, Meliponini) / Linear and nonlinear methods of chronobiological data analysis of Melipona quadrifasciata (Hymenoptera, Meliponini)

Sebrian, Talita de Cássia Glingani 11 October 2011 (has links)
A Cronobiologia estuda a origem e a manifestação de ritmos biológicos nos mais diversos táxons. A análise dos dados obtidos experimentalmente, contudo, é bastante complexa, haja vista a restrita gama de métodos disponíveis para tal. Os osciladores que determinam a existência dos ritmos biológicos são exemplos de sistemas dinâmicos não-lineares, os quais estão amplamente distribuídos nos seres vivos. Esses sistemas, por suas peculiaridades, são melhor analisados por métodos não-lineares. O objetivo deste trabalho é testar diferentes métodos de análise séries temporais, tanto alguns classicamente empregados na Cronobiologia quanto métodos não-lineares, verificando sua empregabilidade e funcionalidade para dados cronobiológicos, bem como as propriedades que permitem ou não seu uso. Para tanto, foram utilizados dados de ritmos de consumo de O2 obtidos para diferentes grupos etários de operárias de Melipona quadrifasciata (Hymenoptera, Meliponini). Tais dados foram submetidos às seguintes análises: Transformada Rápida de Fourier (TRF), Análise de Potência Espectral (PSA), Estatística Circular (teste de Rayleigh), Teste de Estacionariedade (Teste da Raiz Unitária de Dickey-Fuller Aumentado - ADF), Plot de Poincaré, Entropia Aproximada (ApEn) e Entropia Aproximada Volumétrica (vApEn). Os resultados obtidos demonstram que os métodos não-lineares de análise detectam a existência de ritmo metabólico, assim como os métodos lineares utilizados por Teixeira (2006) e Camargo (em andamento) indicam sua presença. Ressalta-se, contudo, que há certa dificuldade em distinguir se a variabilidade existente nas séries deve-se, possivelmente, a seu comportamento determinístico ou a ruídos externos a elas, cuja detecção não é possível. Outro importante fator limitante da aplicabilidade das análises não-lineares é o número de pontos das séries temporais em questão, que era bastante reduzido nesse estudo. Dessa maneira, conclui-se que alguns métodos não-lineares, e.g. TRF, também são eficazes na detecção de ritmos biológicos, devendo ser observada a restrição devido ao tamanho da série temporal. / Chronobiology is the study of the origin and manifestation of rhythmical phenomena in all sorts of taxons. The analysis of the experimental obtained data is, however, still very complex due to the lack of availability of methods and techniques. The oscillators that determine the existence of rhythmical biological phenomena are examples of non-linear dynamic systems, which are widely spread among organisms. This research intends to present the result of a sort of temporal series analysis methods, some already used for Chronobiology research, as non-linear methods, testing their use and functionality for chronobiological data as well as determining their gaps and limitations for this purpose. For this research, data regarding to rhythm of O2 consumption were obtained from different age groups of Melipona quadrifasciata (Hymenoptera, Meliponini) workers. Such data were submitted to the following analysis: Fast Fourier Transform (FFT), Power Spectrum Analysis (PSA), Circular Statistics (Rayleigh\'s test), Stationarity Test (Unit Root Augmented Dickey-Fuller Test - ADF), Poincaré Plot, Approximate Entropy (ApEn) e Volumetric Approximate Entropy (vApEn). The results indicate that nonlinear methods detect the presence of metabolic rhythm, such as previous researches where linear methods used by Teixeira (2006) and Camargo (ongoing research) indicate its presence. However, there is some difficulty in determining if the variability present in the series is possibly due to its deterministic behavior or to the external noise, from which the determination is still not possible. Another limiting factor is the number of points of analyzed temporal series, which was very small. We conclude that some nonlinear methods, e.g. FFT, are effective to detect biological rhythms, but the constraint to time series length must be observed.
15

Estudo comparativo de métodos de amostragem e análise de partículas em suspensão na atmosfera: uma análise crítica / Comparative study of sampling methods and analysis of suspended particles in the atmosphere: a critical analysis

Guimaraes, Fernando de Araujo 21 September 1977 (has links)
Vários métodos de amostragem e análise de partículas em suspensão na atmosfera foram discutidos. Os métodos mais utilizados, gravimétrico e refletância foram testados comparativamente e quanto à correlação entre seus resultados em dois locais distintos. Os fatores intervenientes nos resultados obtidos foram estudados quanto à sua influência. Os métodos gravimétrico e reflectância foram analisados quanto a exatidão dos resultados fornecidos e quanto ao seu significado higiênico em função da correlação existente entre concentração de partículas na atmosfera e danos à saúde. A presente investigação levou o autor a concluir por uma significante diferença entre os resultados fornecidos pelos métodos em estudo, por uma correlação estratificada e variável de local para local entre eles, e por inadequacidade dos valores fornecidos por cada um dos métodos em estudo quanto ao fato de não fornecerem os valores de concentração de partículas na atmosfera mais correlacionados com danos à saúde. O autor sugere o uso ou o desenvolvimento de um método que pelo menos separe as partículas nas frações respirável e não respirável e que permita uma análise posterior de cada uma das frações. Sugere ainda que concomitantemente sejam efetuados estudos epidemiológicos de correlação entre os valores obtidos e danos à saúde para determinação de novos padrões de qualidade do ar para partículas em suspensão na atmosfera. / Various methods to evaluate concentrations of suspended particulate matter were discussed. The two most commonly ueed methods, gravimetric high volume sampler and DECD reflectance method were tested to compare and correlate their results in two different places. The interfering factors were studied to deter mine their influence on the results. The hivol and reflectance methods were analysed according to the accuracy of the results and according to the hygienic significance as they correlate with health effects. This investigation brought the author to the conclusion that there is a significant statistical difference between the results of the two methods. There are correlations between the methods, which are stratified and vary from one place to the other. Finally, however the results are not the best estimate of the concentratios of suspended particulate matter that correlates with health effects. The author suggests the use or the development of a new method that at least can separate the particles sampled into two fractions, one respirable and another non-respirable. Both fractions must be collected in such a way and in such quantities that allow for adequate analysis afterwards. It is suggested also, that epidemiological studies to correlate the results with health effects must be carried on et the same time in arder to set new air quality standards for suspended particute matter.
16

Estudo comparativo de métodos de amostragem e análise de partículas em suspensão na atmosfera: uma análise crítica / Comparative study of sampling methods and analysis of suspended particles in the atmosphere: a critical analysis

Fernando de Araujo Guimaraes 21 September 1977 (has links)
Vários métodos de amostragem e análise de partículas em suspensão na atmosfera foram discutidos. Os métodos mais utilizados, gravimétrico e refletância foram testados comparativamente e quanto à correlação entre seus resultados em dois locais distintos. Os fatores intervenientes nos resultados obtidos foram estudados quanto à sua influência. Os métodos gravimétrico e reflectância foram analisados quanto a exatidão dos resultados fornecidos e quanto ao seu significado higiênico em função da correlação existente entre concentração de partículas na atmosfera e danos à saúde. A presente investigação levou o autor a concluir por uma significante diferença entre os resultados fornecidos pelos métodos em estudo, por uma correlação estratificada e variável de local para local entre eles, e por inadequacidade dos valores fornecidos por cada um dos métodos em estudo quanto ao fato de não fornecerem os valores de concentração de partículas na atmosfera mais correlacionados com danos à saúde. O autor sugere o uso ou o desenvolvimento de um método que pelo menos separe as partículas nas frações respirável e não respirável e que permita uma análise posterior de cada uma das frações. Sugere ainda que concomitantemente sejam efetuados estudos epidemiológicos de correlação entre os valores obtidos e danos à saúde para determinação de novos padrões de qualidade do ar para partículas em suspensão na atmosfera. / Various methods to evaluate concentrations of suspended particulate matter were discussed. The two most commonly ueed methods, gravimetric high volume sampler and DECD reflectance method were tested to compare and correlate their results in two different places. The interfering factors were studied to deter mine their influence on the results. The hivol and reflectance methods were analysed according to the accuracy of the results and according to the hygienic significance as they correlate with health effects. This investigation brought the author to the conclusion that there is a significant statistical difference between the results of the two methods. There are correlations between the methods, which are stratified and vary from one place to the other. Finally, however the results are not the best estimate of the concentratios of suspended particulate matter that correlates with health effects. The author suggests the use or the development of a new method that at least can separate the particles sampled into two fractions, one respirable and another non-respirable. Both fractions must be collected in such a way and in such quantities that allow for adequate analysis afterwards. It is suggested also, that epidemiological studies to correlate the results with health effects must be carried on et the same time in arder to set new air quality standards for suspended particute matter.
17

Functional characterisation of novel mast cell genes.

Sisavanh, Mary, Biotechnology & biomolecular sciences, UNSW January 2008 (has links)
The development of microarray technology has provided an unprecedented wealth of data on gene expression in various tissue and cell types. Few studies have, however, taken full advantage of these data by selecting and then extensively characterising the functions of particular genes chosen from these microarray datasets. In this study, after analysing differentially-regulated genes revealed by microarray analysis of human mast cells activated via Fc??RI cross-linking, we chose two promising gene candidates for further research, A20 and Gem. Our group??s extensive gene expression database of major leukocytes showed that both A20 and Gem were up-regulated in other leukocyte types, and yet neither of these genes has been extensively explored in mast cells or in the immune system prior to our study. In order to investigate the first of these genes selected for further study, A20, we utilised both A20-deficient mast cells and mast cells in which A20 was over-expressed. Our findings establish for the first time that A20 is an important regulator of mast cell inflammatory responses to both LPS and Fc??RI cross-linking, and that it plays a novel role in mast cell proliferation. Our study of the second gene chosen for investigation, Gem, was conducted in a Gemdeficient mouse model developed by our group. In this study, we investigated the effect of Gem deficiency in two key immune cell types, macrophages and T-cells, complementing the work of a previous group member who investigated Gem deficiency in mast cells. Our results clearly exclude a role for Gem in macrophage and T-cell effector responses, and further establish that Gem is dispensable for in vivo inflammatory responses in models of delayed-type hypersensitivity and allergic airway inflammation. In addition to these findings, and given that the physiological role of Gem was not yet understood prior to our study, we extended our investigation to explore a potential function for Gem in the metabolic system. Using Gem-deficient mice, we found that Gem is necessary for insulin secretion from pancreatic islets. These findings confirm the potential for microarray expression data to reveal excellent gene candidates for further research and functional characterisation.
18

Transcriptional and genetic profiling of human uveal melanoma from an immunosuppressed rabbit model

Marshall, Jean-Claude. January 2007 (has links)
Uveal melanoma is the most common primary intraocular malignant tumour in adults. Despite improvements in the diagnosis and treatment of the primary tumour, patients continue to have the same mortality rate as several decades ago, reflecting our poor understanding of the mechanisms behind the formation of metastases in this disease. The purpose of this study was therefore to characterize an animal model of uveal melanoma and use this model to study the transcriptional changes that cells undergo from culture to intraocular tumour, to circulation and finally to the formation of a metastatic nodule. / Using microarrays we identified 314 changes in transcript abundance between the intraocular tumour and metastatic lesions. Principal Components Analysis was used to cluster these transcripts into four distinct groups. A further 61 gene transcripts showed statistically significant changes between re-cultured cells isolated from the model, with the circulating malignant cells representing an intermediate step between cells isolated from intraocular tumours and metastatic lesions. We have produced a detailed analysis of the molecular changes that take place as human uveal melanoma cells evolve from a primary tumour to metastasis in an animal model, including the decrease in expression of specific melanoma markers. These changes were verified using quantitative real time polymerase chain reaction and three different functional assays. / In addition we sought to describe the genetic changes that are present in these cells. Using comparative genomic hybridization arrays we were able to successfully describe the deletions and amplifications that are present in genomic DNA extracted from paraffin embedded sections of the primary tumour. This represents the first time that archival tissue has successfully been used for this sort of analysis in uveal melanoma. We identified several genomic amplifications and deletions including an area of amplification of Wnt2, which is involved in beta-catenin regulation and C-Met, which plays a role in tumour cell homing to the liver in patients. / To the best of our knowledge, this is the first time that a detailed genetic analysis has been carried out on the progression of uveal melanoma from intraocular tumour, to circulation, to the formation of metastases.
19

Functional characterisation of novel mast cell genes.

Sisavanh, Mary, Biotechnology & biomolecular sciences, UNSW January 2008 (has links)
The development of microarray technology has provided an unprecedented wealth of data on gene expression in various tissue and cell types. Few studies have, however, taken full advantage of these data by selecting and then extensively characterising the functions of particular genes chosen from these microarray datasets. In this study, after analysing differentially-regulated genes revealed by microarray analysis of human mast cells activated via Fc??RI cross-linking, we chose two promising gene candidates for further research, A20 and Gem. Our group??s extensive gene expression database of major leukocytes showed that both A20 and Gem were up-regulated in other leukocyte types, and yet neither of these genes has been extensively explored in mast cells or in the immune system prior to our study. In order to investigate the first of these genes selected for further study, A20, we utilised both A20-deficient mast cells and mast cells in which A20 was over-expressed. Our findings establish for the first time that A20 is an important regulator of mast cell inflammatory responses to both LPS and Fc??RI cross-linking, and that it plays a novel role in mast cell proliferation. Our study of the second gene chosen for investigation, Gem, was conducted in a Gemdeficient mouse model developed by our group. In this study, we investigated the effect of Gem deficiency in two key immune cell types, macrophages and T-cells, complementing the work of a previous group member who investigated Gem deficiency in mast cells. Our results clearly exclude a role for Gem in macrophage and T-cell effector responses, and further establish that Gem is dispensable for in vivo inflammatory responses in models of delayed-type hypersensitivity and allergic airway inflammation. In addition to these findings, and given that the physiological role of Gem was not yet understood prior to our study, we extended our investigation to explore a potential function for Gem in the metabolic system. Using Gem-deficient mice, we found that Gem is necessary for insulin secretion from pancreatic islets. These findings confirm the potential for microarray expression data to reveal excellent gene candidates for further research and functional characterisation.
20

Verotoxinogenic Escherichia coli O157:H7 in Swedish cattle and pigs /

Eriksson, Erik, January 2010 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2010. / Härtill 5 uppsatser.

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