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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.
71

Strontium Isotopes-A Tracer for Dust and Flow Processes in an Alpine Catchment

Hale, Colin Andrus 01 July 2018 (has links)
Stream chemistry changes in response to snowmelt, but does not typically reflect thechemistry of the snowpack. This suggests that flow processes between snowmelt and streamsystem, such as interactions with the soil and bedrock, have an important control on waterchemistry and highlight the complex flow pathways from the snowpack to stream. To investigateflow processes in the upper Provo River watershed, northern Utah, we sampled three sites on theriver ~20 times per year during 2016 and 2017. The sites, from highest elevations to lowest wereSoapstone, Woodland, and Hailstone, corresponding to locations of active stream gauges. Toidentify possible water sources to the stream during snowmelt, water samples were taken forsnow, ephemeral streams, soil water, lake, and spring water. To investigate potential impacts ofmineralogy, samples were taken for dust, soil and bedrock. The upper Provo River showeddistinct temporal variation in filtered (<0.45 microns) stream water for 87Sr/86Sr, dissolvedorganic carbon (DOC), silica (Si), and Lead (Pb) during the snowmelt season. The watershed hasdistinct 87Sr/86Sr ratios for bedrock (0.7449)
72

Diagnóstico da raiva e das encefalites equinas do Leste e Oeste em equídeos pelo emprego da técnica de multiplex hemi-nested RT-PCR / Diagnosis of rabies and Eastern and Western Equine Viral Encephalitides in equids by multiplex hemi-nested RT-PCR technique

Iamamoto, Keila 10 October 2011 (has links)
Várias zoonoses virais acometem equídeos causando quadros neurológicos, entre as quais a raiva e as encefalites equinas do Leste (EEE) e Oeste (WEE). O diagnóstico clínico geralmente não é conclusivo, o que torna imprescindível o diagnóstico laboratorial. Dados do Laboratório de Diagnóstico de Raiva do Instituto Pasteur de São Paulo, entre os anos 2000 e 2010, mostram que aproximadamente 75% das amostras enviadas foram negativas para raiva, ressaltando a relevância da realização de um diagnóstico diferencial para as encefalites equinas causadas por alfavírus. Os objetivos do estudo foram testar a adequação do uso de multiplex hemi-nested RT-PCR para o diagnóstico de raiva, EEE e WEE em amostras de sistema nervoso central de equídeos e realizar uma análise de custo das reações de cada técnica. Foram utilizados os primers 21G, 304 e 504 dirigidos ao gene N do vírus da raiva, e os primers cM3W, M2W, nEEE e nWEE dirigidos ao gene NSP1 dos vírus da EEE e WEE. Procedeu-se a um estudo preliminar dos primers e de seu uso em uma hemi-nested RT-PCR, avaliando a temperatura ótima de anelamento, a sensibilidade e especificidade analíticas e a reprodutibilidade da técnica em amostras de campo positivas para raiva e para EEE. A partir do protocolo estabelecido na reação de hemi-nested RT-PCR, realizaram-se variações de concentração de reagentes no protocolo para a reação de multiplex hemi-nested RT-PCR. Após o estabelecimento do protocolo para esta reação, os mesmos testes para verificação da sensibilidade e especificidade analíticas e da reprodutibilidade foram realizados, comparando-se os resultados com os obtidos pela hemi-nested RT-PCR. No teste de limiar de detecção, a sensibilidade analítica foi semelhante para as duas técnicas, obtendo-se 10&#45;1,7 para os três vírus padrão CVS, EEEV e WEEV. No teste de limiar de detecção utilizando uma amostra com os três vírus verificou-se uma alta especificidade dos primers, sendo que na reação de multiplex hemi-nested RT-PCR foi possível detectar simultaneamente os três vírus padrão. Não houve diferença nas proporções de amostras detectadas como positivas para raiva obtidas pelas duas técnicas, analisando-se pelo teste exato de Fisher (P=1,0000). No entando, para amostras de campo positivas para EEE, a proporção de amostras detectadas como positivas pela hemi-nested RT-PCR foi maior do que a proporção obtida pela multiplex hemi-nested RT-PCR (P<0,0001). Apesar de não ter sido possível o uso de amostras de campo positivas para WEE nesse estudo, os resultados sugerem que seria possível a detecção pela multiplex hemi-nested RT-PCR. Estes dados sugerem que a técnica de multiplex hemi-nested RT-PCR poderia ser aplicada para detecção de raiva e WEE, mas com limitações para a detecção de EEE. Pela análise de custo dos reagentes, o valor de uma reação de multiplex hemi-nested RT-PCR é semelhante ao de uma hemi-nested RT-PCR, podendo representar uma economia de pelo menos 49,17%. / Several viral zoonoses affect the equids causing neurological diseases, including rabies and Eastern and Western equine encephalitides (EEE and WEE). Clinical diagnosis is often not conclusive, in a way that laboratory diagnosis is essential. Data from the Laboratory of Rabies Diagnosis at the Pasteur Institute of São Paulo, between 2000 and 2010, demonstrate that approximately 75% of submitted equid samples were negative for rabies, emphasizing the importance of achieving a differential diagnosis for equine encephalitis caused by alphaviruses. The aims of this study were to test the suitability of using multiplex hemi-nested RT-PCR for the diagnosis of rabies, EEE and WEE in equids central nervous system samples and to perform a cost analysis of the reactions of each technique. We used the primers 21G, 304 and 504 directed to the N gene of rabies virus, and the primers cM3W, M2W, nEEE and nWEE directed the NSP1 gene of WEE and EEE viruses. A preliminary study of the primers was carried out, as well as their use in a hemi-nested RT-PCR, evaluating the optimal annealing temperature, the analytical sensitivity and specificity and the reproducibility of the technique in positive field samples for rabies and EEE. From the protocol established for the hemi-nested RT-PCR, variations in reagents concentrations for the multiplex hemi-nested RT-PCR protocol were perfomed. After establishing the protocol for this reaction, the same tests to verify the analytical sensitivity and specificity and reproducibility were performed and the results compared to those obtained by hemi-nested RT-PCR. In the detection threshold test, the analytical sensitivity was similar for both techniques, resulting in 10&#45;1.7 for the three virus standard CVS, and EEEV WEEV. In the detection threshold test using a sample with the three viruses, a high specificity of the primers was verified and the multiplex hemi-nested RT-PCR was able to detect the three viruses simultaneously. There was no difference in the proportions of samples detected as positive for rabies obtained by both techniques, according to the Fisher exact test (P = 1.0000). However, for EEE positive field samples, the proportion of samples detected as positive by the hemi-nested RT-PCR was higher than the proportion obtained by multiplex hemi-nested RT-PCR (P <0.0001). Although it was not possible to use WEE positive field samples in this study, the results suggest that its detection would be possible by multiplex hemi-nested RT-PCR. Thus, data suggest that the multiplex hemi-nested RT-PCR technique could be applied to detect rabies and WEE, but with limitations for the EEE detection. For the analysis of reagent costs, the cost of one multiplex hemi-nested RT-PCR is similar to one hemi-nested RT-PCR, and may represent a saving of 49,17% at least.
73

Scottish primary school teachers' perspectives on multicultural and antiracist education

Byerly, Anna Katarzyna January 2016 (has links)
Primary school teachers’ commitment to social justice may be enshrined in various educational policies in Scotland and beyond, yet it stands in conflict with growing push for teacher accountability, value of education as a market place (Ball, 2006) and the persistence of the myth of meritocracy (Tomlinson, 2008; Oyler, 2012). At the level of practice, whether teachers actually engage in inclusive and critical multicultural education is not always clear; what we know for sure is that teachers find it difficult and shy away for any discussions which challenge power relations between groups (May and Sleeter, 2010). As student population continues to diversify, minority groups demand recognition in ways not seen before. Yet still, discrimination based on ethnicity, language, religion social class, disability, gender and sexual orientation is commonplace, and racism can often be an elephant in the (class)room, discussed in hushed voices only when an ‘isolated incident’ happens. Much more often, it remains unrecognised or is dealt with in a way which perpetuates white privilege (Arshad, 2008). Antiracism is oftentimes misunderstood or outright avoided, as teachers fear using any terminology that sounds negative or they are unsure of, and retreat to the language of all-encompassing, positive sounding, but fuzzy celebration of diversity and equality (Gaine, 2005). Multiculturalism, on the other hand, being blamed for failing integration and social cohesion of communities by the political right, remains in popular debates but occupies a weak position in education and public policy (Modood, 2007). This research set out to investigate what are primary school teachers’ perspectives on multicultural and antiracist education in the context of Scotland, where legislation and educational policies are in theory demanding educators to be proactive. The research followed a nested case study design, which involved observing and interviewing 9 class teachers in 4 primary schools, both rural and urban. I used the critical interpretive lens to find out what are their understandings of multicultural and antiracist education, both as concepts and principles and in terms of how they are being incorporated into their everyday teaching. Teachers were asked to define these terms, as they developed in the specific national context (Ball, 1990), and then consider the interplay of ideals behind ‘race’ equality policies with the realities of their school and classroom practice. This study was concerned with the personal, structural and institutional aspects of teachers’ work. The importance of the context of teachers’ work is stressed, that is their ‘organizational embeddedness’ (Holstein and Gubrium, 1994) and institutional thinking that teachers are thought to be immersed in. To get to know this context better, additional interviews with 4 Head teachers, 3 English as an Additional Language teachers and 5 other Key Informants were conducted. Finally, policy analysis was undertaken, using aspects of Critical Theory to find out how teachers’ attitudes correspond to the attitudes expressed in education policy, as well as what is the impact of educational policy on these attitudes. The findings suggest that there is no one definition of the study’s central concepts to which all teachers can ascribe. Whether or not teachers take up issues of discrimination and difference depends more on their own dispositions and characteristics rather than on any official policy, of which they are largely unaware. Teachers’ prior knowledge, attitudes to diversity and personal experiences of discrimination influenced their commitment for social justice and exercising agency in practice. Structural and institutional boundaries placed on teachers acted as either directions, limits, opportunities or enablers. These related to the leadership within the school more than from the local authority, and included the influence of various actors within the school context. Finally, the translation of policy ideals into everyday school life was seen as uncertain, as it depends on a number of actions and interpretations within any school context. This study concludes by comparing teacher’s perspectives on critical multicultural practice with policies on racial equality in Scotland, to demonstrate which areas need most bridge-building if policy and practice are to be more closely aligned.
74

Previsão de níveis fluviais em tempo atual com modelo de regressão adaptativo: aplicação na bacia do rio Uruguai

Moreira, Giuliana Chaves January 2016 (has links)
Este trabalho avaliou o potencial da aplicação da técnica recursiva dos mínimos quadrados (MQR) para o ajuste em tempo atual dos parâmetros de modelos autorregressivos com variáveis exógenas (ARX), as quais são constituídas pelos níveis de montante para melhorar o desempenho das previsões de níveis fluviais em tempo atual. Três aspectos foram estudados em conjunto: variação do alcance escolhido para a previsão, variação da proporção da área controlada em bacias a montante e variação da área da bacia da seção de previsão. A pesquisa foi realizada em três dimensões principais: a) metodológica (sem recursividade; com recursividade; com recursividade e fator de esquecimento); b) temporal (6 alcances diferentes: 10, 24, 34, 48, 58 e 72 horas); e c) espacial (variação da área controlada da bacia e da área da bacia definida pela seção de previsão). A área de estudo escolhida para essa pesquisa foi a bacia do rio Uruguai com exutório no posto fluviométrico de Uruguaiana (190.000 km²) e as suas sub-bacias embutidas de Itaqui (131.000 km²), Passo São Borja (125.000km²), Garruchos (116.000 km²), Porto Lucena (95.200 km²), Alto Uruguai (82.300 km²) e Iraí (61.900 km²). Os dados de níveis fluviométricos, com leituras diárias às 07:00 e às 17:00 horas, foram fornecidos pela Companhia de Pesquisa de Recursos Minerais (CPRM), sendo utilizados os dados de 1/1/1991 a 30/6/2015. Para a análise de desempenho dos modelos, foi aplicado como estatística de qualidade o coeficiente de Nash-Sutcliffe (NS) e o quantil 0,95 dos erros absolutos (EA(0,95): erro que não foi ultrapassado com a frequência de 0,95). Observou-se que os erros EA(0,95) dos melhores modelos obtidos para cada bacia sempre aumentam com a redução da área controlada, ou seja, a qualidade das previsões diminui com o deslocamento da seção de controle de jusante para montante. O ganho na qualidade das previsões com a utilização dos recursos adaptativos torna-se mais evidente, especialmente quando observam-se os valores de EA(0,95), pois esta estatística é mais sensível, com diferenças maiores em relação ao coeficiente NS. Além disso, este é mais representativo para os erros maiores, que ocorrem justamente durante os eventos de inundações. De modo geral, foi observado que, à medida que diminui a área da bacia, é possível obter previsões com alcances cada vez menores. Porém a influência do tamanho da área controlada de bacias a montante melhora o desempenho de bacias menores quando se observam principalmente os erros EA(0,95). Por outro lado, se a proporção da bacia controlada de montante já é bastante grande, como é o caso das alternativas 1 e 2 utilizadas para previsão em Itaqui (entre 88,5% e 95,4 %, respectivamente), os recursos adaptativos não fazem muita diferença na obtenção de melhores resultados. Todavia, quando se observam bacias com menores áreas de montante controladas, como é o caso de Porto Lucena para a alternativa 2 (65% de área controlada), o ganho no desempenho dos modelos com a utilização dos recursos adaptativos completos (MQR+f.e: mínimos quadrados recursivos com fator de esquecimento) torna-se relevante. / This study evaluated the potential of the application of the recursive least squares technique (RLS) to adjust in real time the model parameters of the autoregressive models with exogenous variables (ARX), which consists of the upstream levels, to improve the performance of the forecasts of river levels in real time. Three aspects were studied jointly: the variation of the lead time chosen for the forecast, the variation in the proportion of controlled area in upstream basins and variation in the area of forecasting section of the basin. The research was conducted in three main dimensions: a) methodological (without recursion; with recursion; with recursion and forgetting factor); b) temporal (6 different lead times: 10, 24, 34, 48, 58 and 72 hours); and c) spatial (variation in the controlled area of the basin and the area of the basin defined by the forecast section). The study area chosen for this research was the Uruguay River basin with its outflow at the river gage station of Uruguaiana (190,000 km²) and its entrenched sub-basins in Itaqui (131,000 km²), Passo São Borja (125,000 km²), Garruchos (116,000 km²), Porto Lucena (95,200 km²), Alto Uruguai (82,300 km²), and Iraí (61,900 km²). The river levels data, with daily readings at 7am and 5pm, were provided by the Company of Mineral Resources Research (CPRM), with the data used from January 1, 1991 to June 30, 2015. We applied the Nash-Sutcliffe coefficient (NS) and the quantile 0.95 of absolute errors (EA(0,95): error has not been exceeded at the rate of 0.95) for the analysis of models performances. We observed that the errors EA(0.95) of the best models obtained for each basin always increase with the reduction of the controlled area then the quality of the forecasts decreases with displacement of the downstream control section upstream. The gain in quality of the forecasts with the use of adaptive resources becomes more evident especially when the observed values of EA(0.95) as this statistic is more sensitive with greater differences in relation to the Nash-Sutcliffe Coefficient (NS). Moreover, this is most representative for larger errors which occur precisely during flooding events. In general, we observed that, as much as the area of the basin decreases, it is possible to obtain forecasts with smaller lead times, but the influence of the size of the area controlled upstream basins improves the performance of smaller basins when observing, especially the errors EA (0.95). However, if the proportion of the upstream of controlled basin is already quite large - as in the case of the alternatives 1 and 2 used for forecast in Itaqui (between 88.5% and 95.4%, respectively) - the adaptive resources do not differ too much in getting better results. However, when observing basins with smaller areas controlled upstream - as is the case of Porto Lucena to alternative 2 (65% controlled area) - the performance gain of the models with the use of the complete adaptive resources (MQR+f.e.) becomes relevant.
75

A influência da informação sobre segurança na demanda por automóveis: o caso do Latin NCAP no Brasil / The infuence of safety information on automobile\'s demand: the case of Latin NCAP in Brazil

Domingues, Marcelo Marini 29 June 2016 (has links)
O presente trabalho procura avaliar a relevância da informação sobre a segurança dos automóveis para os consumidores brasileiros estimando um modelo de demanda logit aninhado controlado pelas notas de zero a cinco estrelas obtidas nos crash tests do Latin NCAP, pesquisa até o momento única no Brasil. Os resultados indicam que a nota nos crash tests são relevantes para a utilidade média dos consumidores com os carros mais bem avaliados mostrando um nível de utilidade maior em relação aos veículos menos seguros. Resultados auxiliares apontam que não há diferença nos preços médios dos modelos avaliados pelo Latin NCAP com notas de uma a cinco estrelas sendo os modelos avaliados com zero estrelas os únicos a apresentarem preços estatisticamente diferentes e mais baratos. Outros resultados obtidos mostram que um aumento no número de automóveis testados de uma determinada montadora aumenta mais que proporcionalmente a probabilidade de um outro automóvel da mesma marca ser avaliado / The present work aims to evaluate how important is the information about car safety for consumers in brazilian market estimating a nested logit demand model using the Latin NCAP\'s grades from zero to five stars as independent variables, yet this research is unique in Brazil. The results obtained show that Latin NCAP\'s grades show some relevance for the consumer\'s mean utiliy as the higher grades exibit higher mean utility levels related to the lowest grades. Auxiliary results show that there is no statistic diference among the car\'s prices evaluated with one to five stars in the crash tests as the automobiles evaluated with zero stars appear as being the cheapest of all. Others results show that an increase in the number of tested vehicles from a given manufacturer raises more than proportionally the probability of a car from this same brand to be tested
76

Probabilistic Programming for Theory of Mind for Autonomous Decision Making

Seaman, Iris Rubi 01 June 2018 (has links)
As autonomous agents (such as unmanned aerial vehicles, or UAVs) become more ubiquitous, they are being used for increasingly complex tasks. Eventually, they will have to reason about the mental state of other agents, including those agents' beliefs, desires and goals – so-called Theory of Mind – and make decisions based on that reasoning. We describe increasingly complex theory of mind models of a UAV pursuing an intruder, and show that (1) there is a natural Bayesian formulation to reasoning about the uncertainty inherent in our estimate of another agent's mental state, and that (2) probabilistic programming is a natural way to describe models that involve one agent reasoning about another agent, where the target agent uses complex primitives such as path planners and saliency maps to make decisions. We propose a nested self-normalized importance sampling inference algorithm for probabilistic programs, and show that it can be used with planning-as-inference to simultaneously reason about other agents' plans and craft counter plans. We demonstrate that more complex models lead to improved performance, and that nested modeling manifests a wide variety of rational agent behavior.
77

A Tractable Cross-Nested Logit Model For Evaluating Two-Way Interconnection Competition With Multiple Network Subscription

Alexander, Roger Kirk 15 January 2004 (has links)
Degree awarded (2004): PhDEc, Economics, George Washington University / This research introduces a new theoretical framework for the analysis of access pricing (the prices that networks charge each other for the completion of calls) and the modeling of network interconnection competition. Prior work on two-way access by Armstrong (1998), Laffont, Rey and Tirole (1998), and Carter and Wright (1999), et al has been built on a two-network Hotelling (1929) differentiated competition model applied to network interconnection. The current research develops an alternative approach that is based on a cross-nested logit (CNL) discrete/continuous consumer choice model with a constant elasticity of substitution (CES) calling utility specification. A principal contribution of the new modeling framework is that in addition to being able to analyze interconnection competition among multiple networks, it is designed to incorporate the element of multiple network subscription where consumers may simultaneously subscribed to more than one type of access network. By introducing multiple-network subscription and usage substitution for users subscribed to multiple networks, the analysis allows more general assessments to be made of the impact of access pricing schemes on the degree of competition between interconnected networks. The model is also not restricted to assumptions of homogeneity in calling on the differentiated networks but can incorporate call differentiation according to network type. The model is applied to evaluate the effects of dual network subscription and asymmetric network competition and to assess multi-network competition in an environment served by two mobile networks and a fixed, wireline network. While confirming the results of prior single network subscription analysis, a central finding of the research based on the developed model is that while network competition is intensified when dual network subscription occurs, negotiated access charges between connected networks continue to serve as an instrument of collusion even in cases of non-linear (two-part) consumer tariffs. / Advisory Committee: John Kwoka, Christopher Snyder (Chair), Sumit Joshi
78

A Scalable Run-Time System for NestStep on Cluster Supercomputers

Sohl, Joar January 2006 (has links)
<p>NestStep is a collection of parallel extensions to existing programming languages. These extensions supports a shared memory model and nested parallelism. NestStep is based the Bulk-Synchronous Programming model. Most of the communication of data in NestStep takes place in a</p><p>combine/commit phase, which is essentially a reduction followed by a broadcast.</p><p>The primary aim of the project that this thesis is based on was to develop a runtime system for NestStep-C, the extensions for the C programming language. The secondary aim was to find which tree structure among a selected few is the best for communicating data in the combine/commit phase.</p><p>This thesis includes information about NestStep, how to interface with the NestStep runtime system, some example applications and benchmarks for determining the best tree structure. A binomial tree structure and trees similar to it was empirically found to yield the best performance.</p>
79

On-the-fly Race Detection for Programs with Recursive Spawn-Sync Parallelism

He, Yuxiong, Wang, Junqing 01 1900 (has links)
Detecting data race is very important for debugging shared-memory parallel programs, because data races result in unintended nondeterministic execution of the program. We propose a dynamic on-the-fly race detection mechanism called Parallel Nondeterminator to check for determinacy races during the parallel execution of a program with recursive spawn-sync parallelism. A modified version of Nested Region Labeling scheme is developed for the concurrency relationship test in the spawn-sync parallel structure. Through the identification of Least Common Ancestor in the spawn tree, the Parallel Nondeterminator only needs to keep two read access records and one write access record for each shared location. The work and critical path in the instrumented codes are analyzed as well as time complexity and space requirements. Let N denote the maximum depth of the recursion in the parallel program. The worst case time increased for each spawn and sync operation is O(N) and the time required to monitor any shared memory location is O(lgN). Moreover, Parallel Nondeterminator is able to execute the race detection code without loss of parallelism of the original program. In summary, the Parallel Non-determinator represents a provably efficient strategy for detecting data races for shared-memory parallel programs. / Singapore-MIT Alliance (SMA)
80

Damage and Failure Analysis of Co-Cured Fiber-Reinforced Composite Joints

Cao, Caihua 02 December 2003 (has links)
Joints represent a design challenge, especially for composite structures. Among the available joining methods, co-curing is an efficient way to integrate parts for some applications. Coates and Armanios have proposed a Single Nested Overlap (SNO) co-cured joint configuration, obtained from a single lap joint through the overlap/interleafing of the adjoining top/bottom adherend plies, respectively. Through a comparative investigation, they have demonstrated joint strength and fatigue life improvements over the single lap joint counterparts for unidirectional and quasi-isotropic adherend lay-ups. This research extends the comparative investigation of Coates and Armanios by focusing upon characterizing and differentiating the damage initiation and progression mechanisms under quasi-static loading. Six specimen configurations are manufactured and tested. It is confirmed that single nested overlap joints show 29.2% and 27.4% average improvement in strength over single lap counterparts for zero-degree unidirectional and quasi-isotropic lay-ups, respectively. Several nondestructive evaluation techniques are used to observe and analyze damage initiation, damage progression and failure modes of the studied specimens and to monitor their mechanical response. Using X-ray Radiography and Optical Microscopy techniques during quasi-static loading, a physical characterization of damage and failure mechanisms is obtained. The acoustic emission data acquired during monotonic loading could reveal the overall picture of AE activities produced by the damage initiation, development and accumulation mechanisms within the specimen via parametric analysis. Further AE analysis by a selected supervised clustering method is carried out and shown successful in differentiating and clustering the AE data. Correlation with physical observations from other techniques suggests that the resulting clusters may be associated to specific damage modes and failure mechanisms.

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