Dissertations / Theses on the topic 'CLUSTER VARIANCE'
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Akdemir, Deniz. "Components Of Response Variance For Cluster Samples." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1206044/index.pdf.
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Measures of data quality are important for the evaluation and
improvement of survey design and procedures. A detailed investigation of the
sources, magnitude and impact of errors is necessary to identify how survey
design and procedures may be improved and how resources allocated more
efficiently among various aspects of the survey operation. A major part of this
thesis is devoted to the overview of statistical theory and methods for
measuring the contribution of response variability to the overall error of a
survey.
A very common practice in surveys is to select groups (clusters) of
elements together instead of independent selection of elements. In practice cluster samples tend to produce higher sampling variance for statistics than
element samples of the same size. Their frequent use stems from the desirable
cost features that they have.
Most data collection and sample designs involve some overlapping
between interviewer workload and the sampling units (clusters). For those
cases, a proportion of the measurement variance, which is due to interviewers,
is reflected to some degree in the sampling variance calculations.
The prime purpose in this thesis is to determine a variance formula that
decomposes the total variance into sampling and measurement variance
components for two commonly used data collection and sample designs. Once
such a decomposition is obtained, determining an optimum allocation in
existence of measurement errors would be possible.
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You, Zhiying. "Power and sample size of cluster randomized trials." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2009r/you.pdf.
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Park, Misook. "Design and Analysis Methods for Cluster Randomized Trials with Pair-Matching on Baseline Outcome: Reduction of Treatment Effect Variance." VCU Scholars Compass, 2006. http://hdl.handle.net/10156/2195.
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Dunning, Allison. "Comparing Bootstrap and Jackknife Variance Estimation Methods for Area Under the ROC Curve Using One-Stage Cluster Survey Data." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1849.
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The purpose of this research is to examine the bootstrap and jackknife as methods for estimating the variance of the AUC from a study using a complex sampling design and to determine which characteristics of the sampling design effects this estimation. Data from a one-stage cluster sampling design of 10 clusters was examined. Factors included three true AUCs (.60, .75, and .90), three prevalence levels (50/50, 70/30, 90/10) (non-disease/disease), and finally three number of clusters sampled (2, 5, or 7). A simulated sample was constructed for each of the 27 combinations of AUC, prevalence and number of clusters. Estimates of the AUC obtained from both the bootstrap and jackknife methods provide unbiased estimates for the AUC. In general it was found that bootstrap variance estimation methods provided smaller variance estimates. For both the bootstrap and jackknife variance estimates, the rarer the disease in the population the higher the variance estimate. As the true area increased the variance estimate decreased for both the bootstrap and jackknife methods. For both the bootstrap and jackknife variance estimates, as number of clusters sampled increased the variance decreased, however the trend for the jackknife may be effected by outliers. The National Health and Nutrition Examination Survey (NHANES) conducted by the CDC is a complex survey which implements the use of the one-stage cluster sampling design. A subset of the 2001-2002 NHANES data was created looking only at adult women. A separate logistic regression analysis was conducted to determine if exposure to certain furans in the environment have an effect on abnormal levels of four hormones (FSH, LH, TSH, and T4) in women. Bootstrap and jackknife variance estimation techniques were applied to estimate the AUC and variances for the four logistic regressions. The AUC estimates provided by both the bootstrap and jackknife methods were similar, with the exception of LH. Unlike in the simulated study, the jackknife variance estimation method provided consistently smaller variance estimates than bootstrap. AUC estimates for all four hormones suggested that exposure to furans effects abnormal levels of hormones more than expected by chance. The bootstrap variance estimation technique provided better variance estimates for AUC when sampling many clusters. When only sampling a few clusters or as in the NHANES study where the entire population was treated as a single cluster, the jackknife variance estimation method provides smaller variance estimates for the AUC.
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Randriatsiferana, Rivo Sitraka A. "Optimisation énergétique des protocoles de communication des réseaux de capteurs sans fil." Thesis, La Réunion, 2014. http://www.theses.fr/2014LARE0019/document.
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Pour augmenter la durée de vie des réseaux de capteurs sans fil, une solution est d'améliorer l'efficacité énergétique des protocoles de communication. Le regroupement des nœuds du réseau de capteurs sans fil en cluster est l'une des meilleures méthodes. Cette thèse présente propose plusieurs améliorations en modifiant les paramètres du protocole de référence LEACH. Pour améliorer la distribution énergétique des "cluster-heads", nous proposons deux protocoles de clustering centralisés k-LEACH et sa version optimisée k-LEACH-VAR. Un algorithme distribué, appelé e-LEACH, est également proposé pour réduire l'échange d'information périodique entre les nœuds et la station de base lors de l'élection des "cluster-heads". Par ailleurs, le concept l'équilibrage énergétique est introduit dans les métriques d'élection pour éviter les surcharges des nœuds. Ensuite, nous présentons une version décentralisée de k-LEACH qui, en plus des objectifs précédents, intègre la consommation d'énergie globale du réseau. Ce protocole, appelé, k-LEACH-C2D, vise également à favoriser la scalabilité du réseau. Pour renforcer ce dernier et l'autonomie des réseaux, les deux protocoles de routage "multi-hop" probabiliste, dénotés FRSM et CB-RSM construisent des chemins élémentaires entre les "cluster-heads" et la station de base. Le protocole CB-RSM forme une hiérarchie des "cluster-heads" pendant la phase de formation des clusters, en mettant un accent sur l'auto-ordonnancement et l'auto-organisation entre les "cluster-heads" pour rendre les réseaux le plus "scalable". Ces différents protocoles reposent sur l'idée de base que les nœuds ayant l'énergie résiduelle la plus élevée et la plus faible variance de consommation de l'énergie deviennent "cluster-head". Nous constantans le rôle central de la consommation du nœud dans nos différentes propositions. Ce point fera l'objet de la dernière partie de cette thèse. Nous proposons une méthodologie pour caractériser expérimentalement la consommation d'un nœud. Les objectifs visent à mieux appréhender la consommation pour différentes séquences d'état du nœud. Enfin, nous proposons un modèle global de la consommation du nœudTo increase the lifetime of wireless sensor networks, a solution is to improve the energy efficiency of the communication's protocol. The grouping of nodes in the wireless sensor network clustering is one of the best methods. This thesis proposes several improvements by changing the settings of the reference protocol LEACH. To improve the energy distribution of "cluster-heads", we propose two centralized clustering protocols LEACH and k-optimized version k-LEACH-VAR. A distributed algorithm, called e-LEACH, is proposed to reduce the periodic exchange of information between the nodes and the base station during the election of "cluster-heads". Moreover, the concept of energy balance is introduced in metric election to avoid overloading nodes. Then we presented a decentralized version of k-LEACH, which in addition to the previous objectives, integrates the overall energy consumption of the network. This protocol, called k-LEACH-C2D, also aims to promote the scalability of the network. To reinforce the autonomy and networks, both routing protocols "multi-hop" probability, denoted CB-RSM and FRSM build elementary paths between the "cluster-heads" and elected the base station. The protocol, CB-RSM, forms a hierarchy of "cluster-heads" during the training phase clusters, with an emphasis on self-scheduling and self-organization between "cluster-heads" to make the networks more scalable. These protocols are based on the basic idea that the nodes have the highest residual energy and lower variance of energy consumption become "cluster-head". We see the central role of consumption of the node in our proposals. This point will be the last part of this thesis. We propose a methodology to characterize experimentally the consumption of a node. The objectives are to better understand the consumption for different sequences of the node status. In the end, we propose a global model of the consumption of the node
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Diaz, Acosta Beatriz. "Experiments in Image Segmentation for Automatic US License Plate Recognition." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/9988.
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License plate recognition/identification (LPR/I) applies image processing and character recognition technology to identify vehicles by automatically reading their license plates. In the United States, however, each state has its own standard-issue plates, plus several optional styles, which are referred to as special license plates or varieties. There is a clear
absence of standardization and multi-colored, complex backgrounds are becoming more frequent in license plates. Commercially available optical character recognition (OCR) systems generally fail when confronted with textured or poorly contrasted backgrounds,
therefore creating the need for proper image segmentation prior to classification. The image segmentation problem in LPR is examined in two stages: license plate region detection and license plate character extraction from background. Three different approaches for license plate detection in a scene are presented: region distance from eigenspace, border location by edge detection and the Hough transform, and text detection by spectral analysis. The experiments for character segmentation involve the RGB, HSV/HSI and 1976 CIE L*a*b* color spaces as well as their Karhunen-Loéve
transforms. The segmentation techniques applied include multivariate hierarchical agglomerative clustering and minimum-variance color quantization. The trade-off between accuracy and computational expense is used to select a final reliable algorithm
for license plate detection and character segmentation. The spectral analysis approach together with the K-L L*a*b* transformed color quantization are found experimentally as the best alternatives for the two identified image segmentation stages for US license plate recognition.Master of Science
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Piana, Clause Fátima de Brum. "Regionalização para o cultivo do feijão no Rio Grande do Sul com base na interação genótipo x ambiente." Universidade Federal de Pelotas, 2009. http://repositorio.ufpel.edu.br/handle/ri/2081.
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Previous issue date: 2009-03-13In Brazil, common bean (Phaseolus vulgaris L.) is cultivated in a range of ecologically differentiated environments. For being a culture highly influenced by the environment variation, its average productivity in the Country is unstable and low. An origin of this variation of productivity is the genotype x environment interaction, which has been one of the largest impediments for obtaining genotypes that maintain consistently high yield in the growing environments. The methods proposed for the exploration of the genotype x environment interaction are directed to the stability of the yield of the genotypes or to the regionalization of the growing locations. Most of the common bean genotypes registered for cultivation in Rio Grande do Sul evidences yield instability. The present research explored data from Rio Grande do Sul Common Bean State Trial ("Ensaio Estadual de Feijão" - EEF), executed at 24 locations in the period from 1987/88 to 1994/95, with considerable variation of genotypes and locations among those years. This research had two main objectives: (1) to evaluate the magnitude and the nature of the genotype x environment interaction and (2) to identify possible stratification of the growing region of common bean in the State in sub-regions inside of which the genotypes have stable relative performance. The inferences about the components of the interaction genotype x environment were proceeded by the joint analysis of each one of the eight years and the analyses of two subsets of four years and of the set of eight years. Because of the intent of obtaining a long time regionalization, general for the growing location of the Rio Grande do Sul and for any collection of beans genotypes, the factors year, location and genotype were considered random. The maximum likelihood and the generalized minimum squares methods were used. This approach allowed taking into account the incomplete and unbalanced structure of the data and the heterogeneity of variance of the experimental error. The results of the annual analyses revealed high significance of the component of the interaction genotype x location in all of the years, indicating that the relative performance of the genotypes varies among locations. This interaction was also revealed significant in the analysis of the eight years, but was not significant in the analyses of the two subsets four years. In these three joint analyses of years the triple interaction genotype x location x year was highly significant. The indication of heterogeneous performance of the genotypes among the locations and the possibility that the pattern of performance have some consistence along the years justified the attempt to the grouping of the locations. Cluster analyses were performed for each one of the eight years and for the set of eight years by the method of Sokal and Michener, that uses the Euclidean distance as similarity measure. The cluster analysis of the set of eight years constituted subregions that are generally incoherent with the sub-regions formed by the annual analyses that, by they turn, were inconsistent amongst themselves. This incoherence and inconsistency of groupings disabled the characterization of a division of the State for the regionalization of the indication of cultivars. It should be observed, however, that these evidences might have been influenced by the considerable alterations of the genotypes and of the locations of execution of the EEF among the years of the period from 1987/88 to 1994/95 in whose data they are based. They can also have resulted, partly, of flaws of the experimental techniques adopted in that period of execution of EEF, particularly of the accentuated variations of the sowing date and of the stand by plot.
No Brasil, o feijão (Phaseolus vulgaris L.) é cultivado em uma gama de ambientes ecologicamente diferenciados. Por ser uma cultura altamente influenciada pela variação de ambiente, sua produtividade média no país é instável e baixa. Uma origem da oscilação da produtividade é a interação genótipo x ambiente, a qual tem sido um dos maiores entraves para a obtenção de genótipos que mantenham rendimentos consistentemente elevados nos diversos ambientes de cultivo. Os métodos propostos para a exploração da interação genótipo x ambiente são direcionados para a estabilidade do rendimento dos genótipos ou para a regionalização dos locais de cultivo. A maioria dos genótipos de feijão registrados para cultivo no Rio Grande do Sul evidencia instabilidade de rendimento. A presente pesquisa explorou dados do Ensaio Estadual de Feijão (EEF) do Rio Grande do Sul, conduzido em 24 locais no período de 1987/88 a 1994/95, com variação considerável de genótipos e de locais entre esses anos. Essa pesquisa teve dois objetivos principais: (1) avaliar a magnitude e a natureza da interação genótipo x ambiente e (2) identificar possível estratificação da região de cultivo do feijão no Estado em sub-regiões dentro das quais os genótipos tenham desempenho relativo estável. As inferências sobre os componentes da interação genótipo x ambiente foram procedidas pela análise conjunta de cada um dos oito anos e as análises de dois subconjuntos de quatro anos e do conjunto dos oito anos. Em razão de se pretender lograr uma regionalização de longo prazo, geral para os locais de cultivo do Rio Grande do Sul e para qualquer coleção de genótipos de feijão, os fatores ano, local e genótipo foram considerados aleatórios. Foram utilizadas as metodologias de máxima verossimilhança e quadrados mínimos generalizados. Essa abordagem permitiu levar em conta a estrutura incompleta e não balanceada dos dados e a heterogeneidade da variância do erro experimental. Os resultados das análises anuais revelaram alta significância do componente da interação genótipo x local em todos os anos, indicando que o desempenho relativo dos genótipos se altera entre os locais. Essa interação também se revelou significativa na análise dos oito anos, mas não significativa nas análises dos dois subconjuntos de quatro anos. Nessas três análises conjuntas de anos a interação tripla genótipo x local x ano foi altamente significativa. A indicação de desempenho heterogêneo dos genótipos entre os locais e a possibilidade do padrão desse desempenho ter alguma consistência ao longo dos anos justificou a tentativa de agrupamento desses locais. Foram efetuadas análises de agrupamento para cada um dos oito anos e para o conjunto dos oito anos, pelo método de Sokal e Michener, que utiliza a distância euclidiana como medida de similaridade. A análise de agrupamento do conjunto dos oito anos constituiu sub-regiões incoerentes com as sub-regiões formadas pelas análises anuais que, por sua vez, foram inconsistentes entre si. Essa incoerência e inconsistência de agrupamentos impossibilitaram a caracterização de uma divisão do Estado para a regionalização da indicação de cultivares. Observe-se, entretanto, que essas evidências podem ter sido influenciadas pelas consideráveis alterações dos genótipos e dos locais de condução do EEF no período de 1987/88 a 1994/95 em cujos dados elas se baseiam. Também podem ter decorrido, em parte, de falhas das técnicas experimentais adotadas nesse período de execução do EEF, particularmente das acentuadas variações da data de semeadura e do estande por parcela.
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Sartorio, Simone Daniela. "Aplicações de técnicas de análise multivariada em experimentos agropecuários usando o software R." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/11/11134/tde-06082008-172655/.
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O uso das técnicas de análise multivariada está reservado aos grandes centros de pesquisa, µas grandes empresas e ao ambiente acad^emico. Essas técnicas s~ao muito interessantes porque utilizam simultaneamente todas as variáveis respostas na interpretação teórica do conjunto de dados, levando em conta as correlações existentes entre elas. Uma das principais barreiras para a utilização dessas técnicas é o seu desconhecimento pelos pesquisadores interessados na pesquisa quantitativa. A outra dificuldade é que a grande maioria de softwares que permitem esse tipo de análise (SAS, MINITAB, BMDP, STATISTICA, S-PLUS, SYSTAT, etc.) não são de domínio público. A disseminação do uso das técnicas multivariadas pode melhorar a qualidade das pesquisas, proporcionar uma economia relativa de tempo e de custo, e facilitar a interpretação das estruturas dos dados, diminuindo a perda de informação. Neste trabalho, foram confirmadas algumas vantagens das técnicas multivariadas sobre as univariadas na análise de dados de expe- rimentos agropecuários. As análises foram realizadas com o auxílio do software R, um software aberto, \"amigável\" e gratuito, com inúmeros recursos disponíveis.The use of the techniques of multivariate analysis is restricted to large centers of research, the higher companies and the academic environment. These techniques are very inte- resting because of the use of all answers variables simultaneously in theoretical interpretation of the data set, considering the correlations between them. One of the main obstacle to the usage of these techniques is that researchers interested in the quantitative research do not know them. The other di±culty is that most of the software that allow this type of analysis (SAS, MINITAB, BMDP, STATISTICA, S-PLUS, SYSTAT etc.) are not in public domain. Publishing the use of Multivariate techniques can improve the quality of the research, decrease the time spend and the cost, and make easy the interpretation of the structures of the data without cause damage of the information. In this report, were con¯rmed some advantages of the multivariate techniques in a univariate analysis for data of agricultural experiments. The analysis were taken with R software, a open software, \"friendly\" and free, with many statistical resources available.
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Dimitrakopoulou, Vasiliki. "Bayesian variable selection in cluster analysis." Thesis, University of Kent, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.594195.
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Statistical analysis of data sets of high-dimensionality has met great interest over the past years, with great applications on disciplines such as medicine, nellascience, pattern recognition, image analysis and many others. The vast number of available variables though, contrary to the limited sample size, often mask the cluster structure of the data. It is often that some variables do not help in distinguishing the different clusters in the data; patterns over the samp•.l ed observations are, thus, usually confined to a small subset of variables. We are therefore interested in identifying the variables that best discriminate the sample, simultaneously to recovering the actual cluster structure of the objects under study. With the Markov Chain Monte Carlo methodology being widely established, we investigate the performance of the combined tasks of variable selection and clustering procedure within the Bayesian framework. Motivated by the work of Tadesse et al. (2005), we identify the set of discriminating variables with the use of a latent vector and form the clustering procedure within the finite mixture models methodology. Using Markov chains we draw inference on, not just the set of selected variables and the cluster allocations, but also on the actual number of components: using the f:teversible Jump MCMC sampler (Green, 1995) and a variation of t he SAMS sampler of Dahl (2005). However, sensitivity t o the hyperparameters settings of the covariance structure of the suggested model motivated our interest in an Empirical Bayes procedure to pre-specify the crucial hyper parameters. Further on addressing the problem of II ~----. -- 1 hyperparameters' sensitivity, we suggest several different covariance structures for the mixture components. Developing MATLAB codes for all models introduced in this thesis, we apply and compare the various models suggested on a set of simulated data, as well as on three real data sets; the iris, the crabs and the arthritis data sets.
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Rastelli, Riccardo, and Nial Friel. "Optimal Bayesian estimators for latent variable cluster models." Springer Nature, 2018. http://dx.doi.org/10.1007/s11222-017-9786-y.
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In cluster analysis interest lies in probabilistically
capturing partitions of individuals, items or observations into groups, such that those belonging to the same group share similar attributes or relational profiles. Bayesian posterior samples for the latent allocation variables can be effectively obtained in a wide range of clustering models, including finite mixtures, infinite mixtures, hidden Markov models and block models for networks. However, due to the categorical nature of the clustering variables and the lack of scalable algorithms, summary tools that can interpret such samples are not available. We adopt a Bayesian decision theoretical approach to define an optimality criterion for clusterings and propose a fast and context-independent greedy algorithm to find the best allocations. One important facet of our approach is that the optimal number of groups is automatically selected, thereby solving the clustering and the model-choice problems at the same time. We consider several loss functions to compare partitions and show that our approach can accommodate a wide range of cases. Finally, we illustrate our approach on both artificial and real datasets for three different clustering models: Gaussian mixtures, stochastic block models and latent block models for networks.
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McClelland, Robyn L. "Regression based variable clustering for data reduction /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/9611.
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Orr, Anton D. "Improving cluster analysis with automatic variable selection based on trees." Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/44639.
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Approved for public release; distribution is unlimitedClustering is an algorithmic technique that aims to group similar objects together in order to give users better understanding of the underlying structure of their data. It can be thought of as a two-step process. The first step is to measure the distances among the objects to determine how dissimilar they are. The second, clustering, step takes the dissimilarity measurements and assigns each object to a cluster. We examine three distance measures proposed by Buttrey at the Joint Statistical Meeting in Seattle, August 2006 based on classification and regression trees to address problems with determining dissimilarity. Current algorithms do not simultaneously address the issues of automatic variable selection, independence from variable scaling, resistance to monotonic transformation and datasets of mixed variable types. These "tree distances" are compared with an existing dissimilarity algorithm and two newer methods using four well-known datasets. These datasets contain numeric, categorical and mixed variable types. In addition, noise variables are added to test the ability of each algorithm to automatically select important variables. The tree distances offer much improvement for the problems they aimed to address, performing well against competitors amongst numerical datasets, and outperforming in the cases of categorical and mixed variable type datasets.
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Olson, Christopher. "Entropy as a Criterion for Variable Reduction in Cluster Data." Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26760.
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Entropy is a measure of the randomness of a system state. This quantity gives us a measure of uncertainty that is associated with each particular observation belonging to a specific cluster. We examine this property and its potential use in analyzing high dimension datasets. Entropy proves most interesting in identifying possible dimensions that do not contribute meaningful classification to the clusters present. We can remove the dimension(s) found which are the least important and generalize this idea to a procedure. After identifying all the dimensions that should be eliminated from the dataset, we then compare its ability in recovering the true classification of the observations versus the estimated classification of the data. From the results obtained and shown in this paper, it is clear that entropy is a good candidate for a criterion in variable reduction.
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Call, Scott. "Long-Period Variable Stars in the Globular Cluster NGC 6553." Bowling Green State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1626973295690519.
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Hodder, Philip Jeremy Crichton. "A search for faint variable stars in the globular cluster M71." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/28830.
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A 67" x 104" area of the metal-rich globular cluster M71 was searched for variable stars using 73 CCD frames. Using mean B and V values a colour-magnitude diagram down to V ≈ 22 is constructed. Four variables were discovered, with two more stars classed as possible candidates for variability. Phase diagrams and real time light curves are presented for all variables. One variable blue straggler (or SX Phe star) has been discovered with a period of 0.d05181. Values for the mass depend on the pulsation mode assumed for this star - (0.90 ± 0.13)M. for the first overtone mode, and (1.57 ± 0.22)M. for the fundamental mode. A second variable, of similar period (0.d06053), but with a magnitude l.m75 below the main sequence turn off was also found but it may be a field star. Two candidate eclipsing binary systems were found. The most likely period of one is 0.d37244. This value, and the shape of the light curve, suggest it may be a W UMa type variable. Its position on the CMD suggests that it too may be a field star. No period was obtainable for the other candidate binary due to a lack of phase coverage. Further data is needed to confirm and strengthen these claims.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Weldrake, David Thomas Fredrick, and weldrake@mpia-hd mpg de. "Giant Planets and Variable Stars in Globular Clusters." The Australian National University. Research School of Astronomy and Astrophysics, 2005. http://thesis.anu.edu.au./public/adt-ANU20050616.191315.
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Over the last decade, 135 extrasolar planets have been discovered, the vast majority found by ongoing radial velocity searches. Of the stars sampled in these searches, 1% have `Hot Jupiter' planets associated with them. Having masses equivalent to Jupiter yet orbital periods of only a few days, this new class of planet is clearly unlike anything in our Solar System.¶
Hot Jupiters present us with an intriguing prospect. If the orientation of the planetary orbit is close to edge-on, the planet will periodically transit across the face of its star, resulting in a small drop in brightness. This transit phenomenon has been successfully used for planet detection over the last couple of years, allowing determination of the planetary radius and accurate mass estimates when coupled with radial velocity observations.¶
To aid understanding of the effect stellar environment plays on Hot Jupiter formation and survivability, this thesis presents the results of a wide-field search for transiting Hot Jupiters in the globular cluster 47 Tucanae. This cluster presents many thousands of stars in a moderate field of view and provides the perfect target for a search of this nature. One previous transit search has been made in the central core of 47 Tuc; using the HST for 8.3 continuous days, Gilliland et.al (2000) expected 17 transits yet found none. This null result suggests that either system metallicity or stellar density may be inhibiting Hot Jupiter formation or survivability in the cluster.¶
This thesis presents a search for transits with a field of view 250 times larger than the HST search and samples the uncrowded outer halo of the cluster (previously unsampled for transits), providing important constraints on the effect of environment on Hot Jupiter formation. If planets are found, then stellar density would seem responsible for the Gilliland et.al (2000) core null result. If no planets are found to a significant level, the survey would provide strong evidence that system metallicity is the dominant factor. Using the ANU 40'' (1m) telescope at Siding Spring Observatory, a 30.4 night observing run was executed and photometry was derived via differential imaging. The dataset numbers 109,000 cluster (and field) stars for photometric analysis, of which 22,000 are suitable for the transit search. With a custom-written transit detection algorithm and extensive Monte Carlo simulations to model the dataset, seven planets should be detectable if the occurrence rate of Hot Jupiters is the same in the cluster as in the Solar Neighbourhood.¶
Despite a detailed search, no transit signatures were identified. This result strongly indicates that the low metallicity of the cluster is the dominant factor inhibiting planet formation in 47 Tuc. Current results in the Solar Neighbourhood show that planet frequency is strongly biased towards stars of high metallicity. This thesis shows that the metallicity trend is likely a universal phenomenon, not only limited to the immediate Solar Neighbourhood and raises questions of whether planets were much rarer in the earlier Universe.¶
As a side result of the search, 100 variable stars were identified in the field, 69 of which are new discoveries. Subsequent analysis reveals a strong period segregation among the cluster eclipsing binaries, indicating previously unobserved dynamical effects in the cluster. Distance estimates for both 47 Tuc and the SMC are in agreement with previously published values and an independent identification of the binary period-colour relation was observed. Two binaries seem to have low-luminosity companions worthy of followup and one variable is likely a star in the early phases of planetary nebula formation. All of the results presented in this thesis have been published in three separately refereed research papers.
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Weldrake, David Thomas Frederick. "Giant planets and variable stars in globular clusters /." View thesis entry in Australian Digital Theses Program, 2005. http://thesis.anu.edu.au/public/adt-ANU20050616.191315/index.html.
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Smitka, Michael Thomas. "Analysis of the Halo Globular Cluster M30 and its Variable Stars." Bowling Green State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1182382804.
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Pellegrin, Kyle S. "Long Period Variable Stars in the Globular Cluster M5 (NGC 5904)." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1595605798891894.
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Cameli, Cinzia <1988>. "Investigation of genetic risk variants for nicotine dependence and cluster headache." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/8583/1/Cinzia_Cameli_PhD_Thesis.pdf.
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The main focus of my PhD has been the analysis of rare and common variants in genetic susceptibility to two complex traits: nicotine dependence (ND) and cluster headache (CH). Firstly, we conducted a genetic study to investigate the role of genetic variation at CHRNA7 and CHRFAM7A in smoking phenotypes, and to test the hypothesis that 7nAChR variation may modulate the efficacy of varenicline in smoking cessation. The study was performed on 408 regular tobacco smokers, recruited at smoking cessation centers, including 142 individuals treated with varenicline. We determined the CHRNA7 and CHRFAM7A copy number, the rs67158670 genotypes in CHRFAM7A and we resequenced the CHRNA7 proximal promoter. Our results point to a role for CHRNA7 promoter variants in tobacco addiction mechanisms; moreover, our study provides the first evidence that CHRFAM7A copy number variation could affect the response to varenicline treatment.
Secondly, In order to investigate the genetic background of CH we performed a genome-wide association analysis on 99 Italian CH patients and 359 controls, using the Infinium PsychArray (Illumina). SNPs genotyping data were used to conduct genome-wide single marker case-control association analysis using common SNPs. Even if no genome-wide significant loci were reported, this analysis led to the identification of a suggestive association with a common variant of the PACAP receptor gene (ADCYAP1R1). Furthermore, we performed a gene-based association analysis considering rare protein altering variants in 745 candidate genes with a possible role in CH. This analysis provided evidence of association for a rare potentially damaging missense variant in the MME gene. ADCYAP1R1 and MME both represent very interesting candidate genes for CH, as their gene products are known to have an important function in pain mechanisms; thus, our study provides the first evidence that genetic variation in genes related to pain processing might have a role in CH susceptibility.
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Abdel-Rasoul, Mahmoud Hisham. "A Variance Estimator for Cohen’s Kappa under a Clustered Sampling Design." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1308329295.
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Xue, Jianhong. "What drives a knowledge-based industry to cluster? : a latent variable analysis /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426116.
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Kager, Elisabeth. "Pulsation Properties of Long Period Variable Stars in Globular Cluster NGC 6553." Bowling Green State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1277148078.
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Cardona, Velasquez Gustavo Adolfo. "Properties of Bright Variable Stars in Unusual Metal Rich Cluster NGC 6388." Bowling Green State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1308577583.
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Al-Trad, Anas. "Optimized Composition of Parallel Components on a Linux Cluster." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-86204.
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We develop a novel framework for optimized composition of explicitly parallel software components with different implementation variants given the problem size, data distribution scheme and processor group size on a Linux cluster. We consider two approaches (or two cases of the framework). In the first approach, dispatch tables are built using measurement data obtained offline by executions for some (sample) points in the ranges of the context properties. Inter-/extrapolation is then used to do actual variant-selection for a given execution context at run-time. In the second approach, a cost function of each component variant is provided by the component writer for variant-selection. These cost functions can internally lookup measurements' tables built, either offline or at deployment time, for computation- and communication-specific primitives. In both approaches, the call to an explicitly parallel software component (with different implementation variants) is made via a dispatcher instead of calling a variant directly. As a case study, we apply both approaches on a parallel component for matrix multiplication with multiple implementation variants. We implemented our variants using Message Passing Interface (MPI). The results show the reduction in execution time for the optimally composed applications compared to applications with hard-coded composition. In addition, the results show the comparison of estimated and measured times for each variant using different data distributions, processor group and problem sizes.
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Abbas, Mohamad. "A search for Long-Period Variable Stars in the Globular Cluster NGC 6496." Bowling Green State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1308597257.
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Husband, Paul W. Jr. "Identification and Characterization of Long Period Variable Stars in the Globular Cluster M69." Bowling Green State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1499418711065308.
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Drury, Jason Andrew. "Observing variable stars and open clusters in the nominal Kepler superstamps." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/24143.
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Asteroseismology, the study of stellar interiors by measuring changes in the brightness of a star, has taken off over the last decade thanks to the unprecedented quantity and quality of photometric data from space telescopes such as Kepler and CoRoT. Open clusters are particularly important, providing ideal targets for understanding stellar evolution through ensemble analyses. These stars are believed to have common ages and metallicities, constraining the parameters affecting their evolution mainly to their mass.
This thesis presents an analysis of the open cluster members and the surrounding field stars for the four open clusters within the nominal Kepler field of view. Prior to conducting any ensemble analysis, we must first separate those stars that are cluster members from foreground and background contaminants. With the release of high precision proper motions of 1.6 billion stars from the Gaia space telescope, we can now determine this membership for large numbers of stars. We have used unsupervised machine learning algorithms including Gaussian mixture models on Gaia DR2 data to determine cluster membership scores for stars in these four open clusters. We present the results of this membership analysis, including databases of likely members, and use these membership determinations to investigate the red giant solar-like oscillators in NGC 6791 and NGC 6819 as an ensemble. We present global asteroseismic properties of all cluster red giants that have measurable oscillations, and include asteroseismic diagrams placing the cluster isochrones in the perspective of the full Kepler red giant sample for the first time. Our identification and classification of other variable stars within the fields of these clusters are also presented, including an in-depth analysis of a previously unknown α2CVn variable that is suitable for future investigations of Ap magnetic fields.
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Ibberson, Mark Robert. "Genomic organisation and polymorphism of the human T cell receptor variable alpha gene cluster." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321749.
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Lipkovich, Ilya A. "Bayesian Model Averaging and Variable Selection in Multivariate Ecological Models." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/11045.
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Bayesian Model Averaging (BMA) is a new area in modern applied statistics that provides data analysts with an efficient tool for discovering promising models and obtaining esti-mates of their posterior probabilities via Markov chain Monte Carlo (MCMC). These probabilities can be further used as weights for model averaged predictions and estimates of the parameters of interest. As a result, variance components due to model selection are estimated and accounted for, contrary to the practice of conventional data analysis (such as, for example, stepwise model selection). In addition, variable activation probabilities can be obtained for each variable of interest. This dissertation is aimed at connecting BMA and various ramifications of the multivari-ate technique called Reduced-Rank Regression (RRR). In particular, we are concerned with Canonical Correspondence Analysis (CCA) in ecological applications where the data are represented by a site by species abundance matrix with site-specific covariates. Our goal is to incorporate the multivariate techniques, such as Redundancy Analysis and Ca-nonical Correspondence Analysis into the general machinery of BMA, taking into account such complicating phenomena as outliers and clustering of observations within a single data-analysis strategy. Traditional implementations of model averaging are concerned with selection of variables. We extend the methodology of BMA to selection of subgroups of observations and im-plement several approaches to cluster and outlier analysis in the context of the multivari-ate regression model. The proposed algorithm of cluster analysis can accommodate re-strictions on the resulting partition of observations when some of them form sub-clusters that have to be preserved when larger clusters are formed.Ph. D.
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De, Marchi Fabrizio. "Variable stars and planetary transit search in super metal-rich open clusters." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3427100.
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This PhD thesis presents the analysis of a large sample of photometric data relative to the super metal-rich open clusters NGC6791 and NGC6253.
The main goal of the surveys was the search for extrasolar planets using the transits method.
I contributed to the extrasolar planet search by making numerical simulations in order to estimate the number of expected transiting planets. Moreover I analyzed the entire sample of light curves in order to find variable stars.
I discovered 260 new variable stars in the field of NGC6791 and 597 in the field of NGC6253.
The classification of all variables is presented and discussed in this work.
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Aljassim, Mohammad A. "A 6-Year Study of Long Period Variable Stars in the Globular Cluster NGC 6388." Bowling Green State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1499442952467274.
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Machin, Graham. "Cataclysmic variables in globular clusters and low mass X-ray binaries." Thesis, University of Oxford, 1990. http://ora.ox.ac.uk/objects/uuid:9cddbf39-034d-4d33-ad98-eecbe9bd60a7.
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Jacunov, Vít. "Využití vícekriteriálního hodnocení variant pro obnovu (zajištění) serverové infrastruktury ve vybraném podniku." Master's thesis, Vysoká škola ekonomická v Praze, 2016. http://www.nusl.cz/ntk/nusl-203820.
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The aim of this master's thesis is to select a suitable option to replace outdated hardware equipment of the company RR Donnelley Prague s.r.o.. In the theoretical part, terms 'virtualization', 'cloud' and their models are explained. Next, RR Donnelley Prague is described and the current situation in terms of hardware infrastructure and outsourced services is analysed. The practical part contains a recommendation of possible solutions of the situation described and, particularly, a selection of criteria assessed and a multi-criteria evaluation of proposed solutions. To estimate weights of the criteria, a scoring method and a paired comparison method is applied. The multi-criteria evaluation of options uses the weighted sum method and TOPSIS. In the end, results of the applied methods are compared and benefits of the thesis for the company and the author are quantified.
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Dean, Nema. "Variable selection and other extensions of the mixture model clustering framework /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8943.
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Asvany, Oskar. "Experiments with Ions and Clusters in a variable temperature 22-pole ion trap." Doctoral thesis, Universitätsbibliothek Chemnitz, 2004. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200400785.
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In this work, 22-pole ion trap machines have been applied to investigate protonated water clusters H+(H2O)n (n=4..10) and ionic hydrocarbons CHn+ (n=2..5) at low temperatures. Protonated water clusters H+(H2O)n play an important role in atmospheric chemistry and in interstellar space. The Taipei 22-pole ion trap machine has been applied to kinetic and spectroscopic investigations of these clusters produced from a supersonic expansion in a corona discharge source. Using low-pressure He buffer gas for collisional thermalization, refrigeration of the ion trap by liquid nitrogen allows a good control of the cluster temperature over the range 80K-350K. This method provides an accurate means of determining the dissociation energies of the cluster ions by measuring their dissociation rates as a function of temperature and calculating their internal energies from vibrational frequencies provided by density functional theory. Results of the thermochemical measurements at well-defined cluster temperatures have been given for H+(H2O)n, n=4..10. The feasibility of using the ion trap to acquire temperature-dependent infrared spectra is presented. The deuteration and abstraction reactions of small ionic hydrocarbons CHn+ (n=2..5) with H2, HD and D2 and the subsequent association processes have been explored at temperatures down to 15K in the Chemnitz 22-pole apparatus. The reactions of the investigated ionic species and their isotopic variants are important for understanding ion-molecule processes in the interstellar medium. One of the starting points of the research program was the question whether protonated methane, CH5+, is subject to H-D-exchange in collisions with HD at low temperatures. It turns out that the rate coefficient for this deuteration process is very small, whereas CH3+ deuterates with HD by three subsequent fast exchange reactions to CD3+ at a temperature of 15K. The latter process is very efficient and happens close to the collision limit. The methane cation, CH4+, on the other hand, shows also some interesting features in collisions with H2, HD and D2. It exhibits an inverse temperature dependence with the rate coefficient increasing at least one order of magnitude going from 300K to 15K. Furthermore, reacting with HD at the temperature of 15K, the reaction channel leading to CH5+ is preferred over the D-atom abstraction channel (isotope effect)Im Rahmen dieser Arbeit wurden zwei Apparaturen mit 22-Pol-Ionenfallen benutzt, um protonierte Wassercluster H+(H2O)n (n=4..10) und kleine ionische Kohlenwasserstoffe CHn+ (n=2..5) bei tiefen Temperaturen zu untersuchen. Die in einer Koronaentladungsquelle erzeugten Cluster H+(H2O)n wurden kinetisch und spektroskopisch untersucht. Dazu wurden sie in einem 22-Pol-Speicher mithilfe eines He-Puffergases auf einer Temperatur zwischen 80K und 350K thermalisiert. Die Bestimmung der Bindungsenergien fuer Cluster der Groesse n=4..10 wird ermoeglicht durch die Messung der temperaturabhaengigen Dissoziationsraten und durch die Ermittlung der inneren Energien mittels berechneter Schwingungsfrequenzen. Temperaturabhaengige IR-Spektren im Bereich der freien OH-Streckschwingung wurden aufgenommen. Die Austausch- und Abstreifreaktionen von ionischen Kohlenwasserstoffen CHn+ (n=2..5) mit H2, HD und D2 und die darauffolgenden Assoziationsprozesse wurden im Temperaturbereich 15K bis 300K untersucht. Es stellt sich z.B. heraus, dass der H-D-Austauschprozess zwischen CH5+ und HD bei 15K sehr langsam ist, wogegen CH3+ mit jeder Kollision einen Austausch ausfuehrt. In der Abstreifreaktion von CH4+ mit Wasserstoffmolekuelen beobachtet man eine inverse Temperaturabhaengigkeit. Dies wird vorlaeufig mit einer laengeren Komplexlebensdauer bei tiefen Temperaturen erklaert
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Barry, Amanda Nell. "Spectroscopic studies of the human copper chaperone for superoxide dismutase : probing the active cluster with selenocysteine variants." Full text open access at:, 2007. http://content.ohsu.edu/u?/etd,258.
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Colman, Isabel Lily. "Pixels, photometry, and population studies: variable stars across four years of Kepler data." Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/22429.
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In this thesis, we focus on studies of variable stars across four years of data from NASA's Kepler mission. We present an analysis of oscillating red giants from which exhibit anomalous peaks in their amplitude spectra. We use close analysis of Kepler pixel data to confirm the source of these anomalous peaks. By analysing the distribution of the population across the Kepler field of view, we find that we are observing two populations, of contamination by a line-of-sight background or foreground binary system, and of physical associations in potential triple systems. Using similar population analysis techniques, we study the distribution of Kepler Objects of Interest to draw conclusions about their designation as either planet hosts or false positives. We use detailed pixel analysis methods to study a rotating subgiant hosting a planet, potential doubly-oscillating red giant-delta Scuti binaries, red giants classified by a neural network. We also extend this work to TESS data, to study a sample of high frequency delta Scuti stars. Finally, we perform image subtraction photometry on the Kepler superstamps, large-scale pixel data covering the open clusters NGC 6791 and NGC 6819. Image subtraction photometry produces high-quality time series data which emphasises stellar variability. We outline the development of an image subtraction photometry pipeline, and present an overview of the results of our search for stellar variability in NGC 6791 and NGC 6819, including detections of stellar rotation, binary systems, and oscillating stars in both clusters.
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Peng, Wei. "Improving Nitrogen Management in Corn- Wheat-Soybean Rotations Using Site Specific Management in Eastern Virginia." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/29485.
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Nitrogen (N) is a key nutrient input to crops and one of the major pollutants to the environment from agriculture in the United States. Recent developments in site-specific management (SSM) technology have the potential to reduce both N overapplication and underapplication and increase farmers' net returns. In Virginia, due to the high variability of within-field yield-limiting factors such as soil physical properties and fertility, the adoption of SSM is hindered by high gridsampling cost. Many Virginia corn-wheat-soybean farms have practiced generating yield maps using yield monitors for several years even though few variable applications based on yield maps were reported. It is unknown if the information generated by yield monitors under actual production situations can be used to direct N management for increased net returns in this area.
The overall objective of the study is to analyze the economic and environmental impact of alternative management strategies for N in corn and wheat production based on site-specific information in eastern Virginia. Specifically, evaluations were made of three levels of site-specific information regarding crop N requirements combined with variable and uniform N application. The three levels of information are information about the yield potential of the predominant soil type within the field, information about yield potentials of all soils within the field (soil zones), information about yield potentials of smaller sub-field units which are aggregated into functional zones. Effects of information on expected net returns and net N (applied N that is not removed by the crop) were evaluated for corn-wheat-soybean fields in eastern Virginia. Ex post and ex ante evaluations of information were carried out.
Historical weather data and farm-level yield data were used to generate yield sequences for individual fields. A Markov chain model was used to describe both temporal and spatial yield variation. Soil maps were used to divide a field into several soil management units. Cluster analysis was used to group subfield units into functional zones based on yield monitor data. Yield monitor data were used to evaluate ex post information and variable application values for 1995-1999, and ex ante information and variable application values for 1999.
Ex post analysis results show that soil zone information increased N input but decreased net return, while functional zone information decreased N input and increased net returns. Variable application decreased N input compared with uniform application. Variable application based on soil zone information reduced net return due to cost of overapplication or underapplication. Variable application based on functional information increased net return.
Ex ante results show that information on spatial variability was not able to increase farmers?net return due to the cost of variable N application and information. Variable rate application decreases N input relative to uniform application. However, imprecision in the spatial predictor makes the variable application unprofitable due to an imbalance between costs of under- and over-application of N. Sensitivity analysis showed that value of information was positive when temporal uncertainty was eliminated.
The ex post results of this study suggest there is potential to improve efficiency of N use and farmers?net returns with site specific management techniques. The ex ante results suggest that site specific management improvements should be tested under conditions faced by farmers including imperfect information about temporal and spatial yield variability.Ph. D.
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Aigner, Johanna 1981. "Genetical, structural and functional characterization of the human BTNL gene cluster." Doctoral thesis, Universitat Pompeu Fabra, 2013. http://hdl.handle.net/10803/127222.
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La família B7 de proteïnes és àmpliament reconeguda per jugar un paper important en els processos inflamatoris mitjançant l'alteració de la capacitat de resposta de les cèl•lules T. La unió d’aquestes proteïnes als seus receptors situats a la superfície de cèl•lules T pot promoure (per exemple, B7-1, B7-2, ICOS- L) o inhibir (per exemple, PD-L1, PD-L2, B7-H3, B7x) l'activació, la proliferació, la maduració i la producció de citoquines en cèl•lules T . A més, s’ha identificat l’expressió de diversos membres d’aquesta família de proteïnes tant en diferents tipus de tumors com en el microambient tumoral. Degut a les capacitats immunosupressores de diversos membres de la família B7, es creu que l'expressió aberrant d'aquestes molècules a interferit negativament amb la resposta immune de l' hoste, el que porta a la progressió de la malaltia. En efecte, l'expressió de proteïnes de la família B7 en molts tumors hematològics malignes s'associa sovint amb un mal pronòstic i un comportament agressiu dels tumors. Actualment, diversos membres de la família B7, com CTLA-1 i PD-1 són usats per el tractament del càncer i, més recentment , el primer agent que focalitza la via de B7, el anti-CTLA-4 MAB (ipilimumab) ha estat aprovat per l'Administració d'Aliments i Medicaments (FDA) per al tractament del melanoma metastàsic. A més, els estudis en curs dirigits a membres recentment descrits de la família B7: B7-H3, B7x, B7-H6 són prometedors , però una major clarificació del seu paper patogènic en malalties hematològiques ajudarà a identificar el seu paper més actiu com a adjuvants immunes al tractament convencional.
Tot i els grans grans progressos en aquest camp , es coneix poc de les proteïnes homòlogues butyrophilin-like (BTNL). La família butyrophilin (BTN) comparteix homologia estructural amb membres de la família B7 i similars a les proteïnes B7. Gairebé tots els BTNS / BTNLs estudiats fins al moment han demostrat ser capaços d'esmorteir la resposta immune mitjançant la co-estimulació negativa en l’activació del les cèl•lules T, fent-les candidates importants en la immunitat antitumoral. Per tant, en aquest estudi, caracteritzem un clúster que conté tres gens BTNL, situats al cromosoma humà 5q35.3, a nivell genòmic, transcripcional i funcional per obtenir una visió més clara en la funció de les proteïnes BTNL.
En el primer capítol, presentem la identificació d’una deleció d’una variant en nombre de còpia (CNV en anglès) de 56 kb donant com a producte un nou gen quimèric (BTNL8*3). Aquesta deleció és responsable de la sobre-expressió del tercer gen del clúster, BTNL9. Posteriorment, es desenvolupà un assaig de genotipació i es va dur a terme un anàlisi poblacional d’aquesta variant en mostres de diferents poblacions pertanyents al HapMap i el panell de diversitat humana (HGDP-CEPH). Aquest assaig de genotipació ens va permetre identificar clares diferències en l’estratificació de l’aŀlel BTNL8_BTNL3-del entre grups continentals majors. A més, presentem tagging SNPs en diverses poblacions, facilitant una genotipació futura de la variant de deleció BTNL8-BTNL3. Finalment mostrem la influència de la deleció CNV en els nivells d’expressió de diferents gens involucrats en càncer i en la resposta immune, suggerint la involucració d’aquesta CNV en rutes biològiques específiques.
En el segon capítol d’aquesta tesi s’investiguen les conseqüències funcionals de la CNV trobant una sobre-expressió de BTNL9 en leucèmia limfoblàstica aguda (ALL en anglès) després del subministrament de glucocorticoides (GC). S’havia mostrat ja prèviament que uns nivells elevats de BTNL9 correlacionen amb un elevat risc en pacients de ALL amb reorganització de MLL-AF4. Per comprovar si aquesta observació és deguda a la implicació de BTNL9 en apoptosi induïda per GC, es varen analitzar diferents línies ceŀlulars pre-B ALL trobant-se una clara correlació entre els nivells d’expressió de BTNL9 i resistència a GC en ALL amb reorganització de MLL i nivells més baixos en MLL en ALL germinal. Aquests resultats suggereixen un paper completament nou i inesperat de la proteïna BTNL que podrien resultar en el desenvolupament de inhibidors específics de BTNL9 per millorar la prognosi de ALL amb reorganització de MLL.
En resum, en aquesta tesi proporcionem un anàlisi del clúster de gens humà BTNL. Identifiquem un nou gen de fusió BTNL8*3 amb implicacions potencials en rutes genètiques involucrades en la regulació i proliferació immune i mostrem una clara funció de BTNL9 en la resistència a GC el la leucèmia amb reorganització de MLL. Aquestes observacions proporcionen un nou coneixement sobre la família de gens BTNL i podria proporcionar la base per noves teràpies basades en BTNL9 en ALL amb reorganització de MLL.In this thesis, we undertook a broad genomic, evolutionary, transcriptomic and functional analysis of a cluster containing three BTNL genes, namely BTNL8, BTNL3 and BTNL9, located on human chromosome 5q35.3. In the first chapter we report the identification of a 56 kb deletion copy number variant (CNV), which results in the formation of a novel chimeric gene, BTNL8*3, and leads to an upregulation in the expression-level of the third gene in the cluster, BTNL9. Next, we developed a genotyping assay and undertook a population analysis of this variant in several Hap Map and human diversity panel (HGDP-CEPH) populations. With this genotyping assay we could identify clear differences in the stratification of the BTNL8_BTNL3-del allele amongst major continental ethnic groups. In addition we report tagging SNPs in several population, facilitating the genotyping process of the BTNL8-BTNL3 deletion variant in the future. Moreover, we show an influence of the deletion CNV in the expression-level of several genes involved in cancer and immune response, suggesting an involvement of this CNV in specific biological pathways. In the second chapter we look for functional consequences of this CNV and found an upregulation of BTNL9 in acute lymphoblastic leukemia (ALL) after glucocorticoid (GC) treatment. Previously, it was shown that high-level BTNL9 correlates with high-risk in MLL-AF4 rearranged acute lymphoblastic leukemia (ALL) patients. To check whether this might be due to in involvement of BTNL9 in GC-induced apoptosis, we analyzed several pre-B ALL cell-lines and found a clear correlation between BTNL9 expression-level and resistance to GC in MLL rearranged ALL and at a lower level in MLL germ-line ALL. These results suggest a completely new and unexpected role for a BTNL protein and may led to the development of specific BTNL9 inhibitors to improve outcome of MLL rearranged ALL. Overall, we provide a comprehensive analysis of a BTNL gene cluster. We identified a new BTNL8*3 fusion-gene with potential implication in genetic pathways involved in immune regulation and proliferation, and show a clear function for BTNL9 in GC-resistance in MLL rearranged leukemia. This knowledge sheds more light on the BTNL family and may provide the basis for novel approaches using BTNL9 in MLL rearranged ALL therapy.
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Hillwig, Todd C. "Analysis of the radial profile emissivity of accretion disks in cataclysmic variables." Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/941346.
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Lamertz, Larissa [Verfasser], and Jürgen [Gutachter] Scheller. "Klassisches, trans- und cluster-signaling durch HIL-6 und membrangebundene HIL-6 (mbHIL-6) Varianten und Identifizierung von neuen konstitutiven gp130 Varianten / Larissa Lamertz ; Gutachter: Jürgen Scheller." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2019. http://d-nb.info/1176806807/34.
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Milne, Peter. "The Variable Pronunciations of Word-final Consonant Clusters in a Force Aligned Corpus of Spoken French." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31139.
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This thesis project examined both schwa insertion and simplification following word-final consonant clusters in a large corpus of spoken French. Two main research questions were addressed. Can a system of forced alignment reliably reproduce pronunciation judgements that closely match those of a human researcher? How do variables, such as speech style, following context, motivation for simplification and speech rate, affect the variable pronunciations of word-final consonant clusters? This project describes the creation and testing of a novel system of forced alignment capable of segmenting recorded French speech. The results of comparing the pronunciation judgements between automatic and manual methods of recognition suggest that a system of forced alignment using speaker adapted acoustic models performed better than other acoustic models; produced results that are likely to be similar to the results produced by manual identification; and that the results of forced alignment are not likely to be affected by changes in speech style or speech rate. This project also described the application of forced alignment on a corpus of natural language spoken French. The results presented in this large sample corpus analysis suggest that the dialectal differences between Québec and France are not as simple as ``simplification in Québec, schwa insertion in France". While the results presented here suggest that the process of simplification following a word-final consonant cluster is similar in both dialects, the process of schwa insertion is likely to be different in each dialect. In both dialects, word-final consonant cluster simplification is more frequent in a preconsonantal context; is most likely in a spontaneous or less formal speech style and in that speech style is positively associated with higher speaking rates. Schwa insertion following a word-final consonant cluster displays much stronger dialectal differences. Schwa insertion in the dialect from France is strongly affected by following context and possibly speech style. Schwa insertion in the dialect from Québec is not affected by following context and is strongly predicted by a lack of consonant cluster simplification.
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Figuera, Jaimes Roberto Jose. "High-precision time-domain astrophysics in crowded star-fields with ground based telescopes : globular clusters and the mitigation of the atmospheric turbulence." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/13673.
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We carried out a three year (2013-2015) observational campaign at the Danish 1.54-m Telescope at the ESO observatory at La Silla in Chile in which we obtained ~1000 astronomical images in the field of 11 Galactic globular clusters. The selection of these stellar systems was focused mainly on the visibility of the targets and their relevant physical properties available in the catalogues, among them were considered the density, variable stars known, colour-magnitude diagrams, and luminosity. The telescope was equipped with an electron-multiplying CCD (EMCCD) with the aim of taking very short exposure-time images. The camera was configured to take 10 frames per second. Due to this, the brighter stars observed were not affected by saturation, it helped to give higher signal to noise ratio to the fainter stars and, importantly, it minimised the effects of the atmospheric turbulence such as blending between stars in the crowded fields. To produce normal-exposure-time images (minutes) we implemented the shift-and-add technique that also enabled us to produce images with better angular resolution than previously achieved with conventional CCDs on ground-based telescopes, and even enabled us to produce images with angular resolution close to that obtained with space telescopes. The detection of the stars in each of the globular clusters and the photometry was performed via difference image analysis by using the DanDIA pipeline whose procedures and mathematical techniques have been demonstrated to produce high-precision time-series photometry of very crowded stellar regions. We produced time-series photometry for ~15000 stars in the fields observed which were statistically analysed in order to automatically extract variable stars. Our aim is to complete, or improve, the census of the variable star population in the globular clusters. In NGC 6715, we found light curves for 17 previously known variable stars near the edges of our reference image (16 RR Lyrae and 1 semi-regular) and we discovered 67 new variables (30 RR Lyrae, 21 long-period irregular, 3 semi-regular, 1 W Virginis, 1 eclipsing binary, and 11 unclassified). This cluster was particularly interesting because apart from the results obtained, it shows the benefits of using the EMCCD cameras and the shift-and-add technique. It is a cluster studied several times including data obtained with the OGLE survey and also with the Hubble Space Telescope and our discoveries were still new. Our new RR Lyrae star discoveries help confirm that NGC 6715 is of intermediate Oosterhoff type. In the other 10 globular clusters, we obtained light curves for 31 previously known variable stars (3 L, 2 SR, 20 RR Lyrae, 1 SX Phe, 3 cataclysmic variables, 1 EW and 1 NC) and we discovered 30 new variables (16 L, 7 SR, 4 RR Lyrae, 1 SX Phe and 2 NC). In NGC 6093, we analysed the famous case of the 1860 Nova, for which no observations of the Nova in outburst have been made until the present study. Ephemerides and photometric measurements for the variable stars are available in electronic form through the Strasbourg Astronomical Data Centre.
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Johnson, Jay. "Identification of National Survey of Student Engagement (NSSE) socialization variable clusters that predict private midwestern college persistence." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5513.
Full textAbstract:
Thesis (Ed. D.)--University of Missouri-Columbia, 2008.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on July 27, 2009) Includes bibliographical references.
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Corradin, Olivia G. "Impact of DNA Variants in the Regulatory Circuitry of Gene Expression inHuman Disease." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1427988486.
Full text
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Gomes, Kátia Regina Maruyama. "Padrão de expressão gênica e localização tecidual no rato de um novo membro do Cluster gênico da enzima conversora da angiotensina I: variante-4." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/5/5131/tde-28012009-162314/.
Full textAbstract:
O sistema renina-angiotensina (SRA) é de fundamental importância para a manutenção da homeostasia cardiovascular. A enzima conversora de angiotensina I (ECA) é um elemento crítico na cascata de ativação das diversas substâncias ativas do SRA. Evidências obtidas em nosso laboratório por análise de genômica comparativa e confirmadas através de clonagem de segmentos de cDNA sugerem que esta família de proteínas está incompleta. Nossos dados apontam para existência de duas novas isoformas da ECA, que aqui denominaremos Variante-3 (Var-3) e Variante-4 (Var-4), localizadas no mesmo locus da ECA. Neste trabalho, analisamos simultaneamente o padrão de expressão das 4 Variantes da ECA e ECA2 em 30 tecidos do rato utilizando a técnica de qRT-PCR. A Variante 4, cuja ação ainda é desconhecida e está sendo investigada em nosso laboratório, apresenta predominantemente expressão no testículo e em quantidade relativamente baixa no ventrículo esquerdo. Utilizando a técnica de hibridização in situ no testículo, verificamos que a marcação positiva da Var- 4 pode ou não ser co-localizada com a Var-2 dependendo do estágio celular em que se encontra no túbulo seminífero. Verificou-se que as espermátides redondas são as células que expressam a Var-4 nos túbulos seminíferos. Em conjunto, estes dados mostram que as Variantes 1, 2, 3 e 4 da ECA apresentam expressão tecido-específica. O padrão de expressão da Var-4, principal objeto deste trabalho, é consistente com a idéia de que esta variante gênica pode estar envolvida com o controle da espermatogênese e em processos cardíacos, até então não caracterizadosThe renin-angiotensin system (RAS) is essential to maintain the cardiovascular homeostasis. The angiotensin-converting enzyme (ACE) is a critical point in the biochemical activation of several active substances, notably angiotensin II. Evidence obtained in our laboratory using comparative genomic analysis and confirmed by cDNA cloning suggests that this protein family is incomplete and point to the existence of two new isoforms of ACE that from now on are denominated Variant-3 (Var-3) and Variant-4 (Var-4), located within the same ACE locus. In the present work we simultaneously analyzed the expression pattern of the 4 ACE gene variants in 30 different tissues of rats. The variant 4, whose mechanism of action remains unknown and it is being presently investigated in our laboratory is mainly expressed in testis and in relatively low quantity in left ventricle. Using in situ hybridization technique in testis, we verified that positive labeling of Var-4 is distinct from Var-2, suggesting that they may play distinct functions during the spermatogenesis process. Taking together, we provide direct evidence that the ACE gene locus contain, 4 variants instead of 2 and they show a specific cell tissue pattern of expression. Mostly important, the Var-4 is primarily expressed in testis and the data suggest that it may be involved with spermatogenesis control, and in cardiac processes presently unknown
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Azevedo, Bárbara Brzezinski. "Agrupamento de trabalhadores com perfis semelhantes de aprendizado utilizando técnicas multivariadas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/96638.
Full textAbstract:
A manufatura de produtos customizados resulta em variedade de modelos, redução no tamanho de lotes e alternância frequente de tarefas executadas por trabalhadores. Neste contexto, tarefas manuais são especialmente afetadas por conta do processo de adaptação do trabalhador a novos modelos de produtos. Este processo de aprendizado pode ocorrer de maneira distinta dentro de um grupo de trabalhadores. Assim, busca-se o agrupamento dos trabalhadores com perfis similares de aprendizado, monitorando a formação de gargalos em linhas de produção constituídas por dissimilaridades de aprendizado em processos manuais. A presente dissertação apresenta abordagens para clusterização de trabalhadores baseadas nos parâmetros oriundos da modelagem de Curvas de Aprendizado. Tais parâmetros, os quais caracterizam o processo de adaptação de trabalhadores a tarefas, são transformados através da Análise de Componentes Principais e então utilizados como variáveis de clusterização. Na sequência, testam-se outras transformações nos parâmetros utilizando funções Kernel. Os trabalhadores são clusterizados através do método K-Means e Fuzzy C-Means e a qualidade dos agrupamentos formados é medida através do Silhouette Index. Por fim, sugere-se um índice de importância de variável baseado em parâmetros obtidos na Análise Componentes Principais com o objetivo de selecionar as variáveis mais relevantes para clusterização. As abordagens propostas são aplicadas em um processo da indústria calçadista, gerando resultados satisfatórios quando comparados a clusterizações realizadas sem a transformação prévia dos dados ou sem seleção das variáveis.Manufacturing of customized products relies on a large menu choice, reduced batch sizes and frequent alternation of tasks performed by workers. In this context, manual tasks are especially affected by workers’ adaptation to new product models. This learning process takes place in different paces within a group of workers. This thesis aims at grouping workers with similar learning process tailored to avoid bottlenecks in production lines due to learning dissimilarities among workers. For that matter, we present a method for clustering workers based on parameters derived from Learning Curve (LC) modeling. Such parameters are processed through Principal Component Analysis (PCA), and the PCA scores are used as clustering variables. Next, Kernel transformations are also used to improve clustering quality. The data is clustered using K-Means and Fuzzy C-Means techniques, and the quality of resulting clusters is measured by the Silhouette Index. Finally, we suggest a variable importance index based on parameters derived from PCA to select the most relevant variables for clustering. The proposed approaches are applied in a footwear process, yielding satisfactory results when compared to clustering on original data or without variable selection.
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Gay, Emilie. "Détection d'agrégats spatiaux dans le cas d'une variable continue : application à un indicateur de l'infection mammaire chez les bovins." Clermont-Ferrand 1, 2006. http://www.theses.fr/2006CLF1MM03.
Full textAbstract:
La détection des agrégats est une problématique d'importance en épidémiologie. Les méthodes de détection d'agrégats ont essentiellement été développées pour des maladies mesurées par des variables dichotomiques (cas/témoins). Or, dans le cas des infections mammaires des bovins, la maladie est évaluée par le score cellulaire, variable continue qui est une expression de la numération leucocytaire du lait. En conséquence, l'objectif de la thèse a consisté à développer des méthodes de détection d'agrégats spatiaux adaptées aux variables continues, afin d'analyser la répartition spatiale du score cellulaire dans les élevages bovins laitiers français. La 1ère approche qui a été développée, non paramétrique, est basée sur la distance d'Hellinger entre distributions spatiales. La mesure de la distance entre la distribution des élevages à différents niveaux de score cellulaire et la densité globale d'élevages a permis de mettre en évidence une concentration progressive dans certaines zones, et donc de détecter des agrégats. Une 2nde approche, paramétrique, utilise un modèle quantifiant la survie spatialisée, pour des niveaux de score croissants, en intégrant les facteurs de risque connus du score cellulaire et un " effet-foyers " de forme gaussienne. Les agrégats détectés par cette méthode ont été identiques à ceux obtenus avec la méthode basée sur la distance d'Hellinger. Les 2 méthodes constituent de nouveaux outils flexibles et génériques pour la détection d'agrégats spatiaux. Elles offrent en effet plusieurs avantages : 1) elles sont applicables à des maladies mesurées par une variable continue ou discrète, 2) elles prennent en compte les facteurs de risque connus de la maladie pour ne s'intéresser qu'aux agrégats inexpliqués, 3) elles tiennent compte de l'hétérogénéité spatiale de la population sous-jacenteCluster detection is an important field of investigation in epidemiology. Methods of cluster detection had mainly been developed for diseases described through dichotomic variables (case/control). But cattle intramammary infections are evaluated by the somatic cell score, a continuous variable expressing milk leukocyte count. Consequently, the thesis objective was to develop methods of spatial cluster detection, dealing with continuous variables, to analyse the spatial distribution of somatic cell score in French bovine dairy herds. The first approach developed, which is non parametric, is based on the Hellinger distance between spatial distributions. The measure of the distance between farm distribution, at different levels of somatic cell score, and the global farm density allowed to highlight a progressive concentration in some specific areas, and thus to detect clusters. The second approach, which is parametric, uses a model quantifying spatialised survival risk for increasing score levels. It integrates known risk factors for the cellular score, aswell as a "foci-effect" with a Gaussian form. The clusters detected with this method were the same as the ones highlighted by the method based on the Hellinger distance. The two methods are new flexible and generic tools for spatial cluster detection. They show several advantages : 1) they deal with diseases measured by continuous or discrete variables, 2) they account for known risk factors of the disease, and focus on unexplained clusters, and 3) they take into account the spatial heterogeneity of background population
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ANGINO, SIRIA. "The importance of being clustered." Doctoral thesis, Luiss Guido Carli, 2017. http://hdl.handle.net/11385/201133.
Full textAbstract:
(I A Few-Cluster-Robust Test for Weak Instruments) - ABSTRACT - In the usual IV regression models, the quality of estimation and inference dra-
matically depends on the relevance of the set of instruments. To test such condition,
most empiricists rely on the first-stage F-statistic as suggested by Stock and Yogo
(2005a). However, this method is not valid for clustered data, especially when there
are few clusters.
Recently, weak instrument-robust methods for inference have been proposed, but
none of them deals with the latter case. In this paper, we propose a simple method
to perform inference which is robust both to the presence of weak instruments and
few clusters in the case of a single endogenous regressor. (II Sharing or gambling over losses?) -
ABSTRACT - This paper investigates experimentally whether individuals prefer to share an
exogenous loss in a deterministic way or to gamble over it. In particular, in some
scenarios subjects face an equal allocation of the loss, in others a social lottery with
an equal chance to suffer it entirely. The loss is implemented after the endowment
is earned. We find that the loss domain does not affect subjects' behavior directly,
but it decreases their probability to play in a competitive way.