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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.
1

The Population Re-distribution and Transitional Trend of Urbanization Process in Kaohsiung Metropolitan Area

YANG, HUI-CHING 08 July 2009 (has links)
This study utilized historical population statistics data and related reports to investigate the population distribution and transition trend of Kaohsiung Main Urban Area. There were four purposes of this study; firstly to understand the current population distribution pattern of Kaohsiung Main Urban Area, secondly to investigate the change trend of Kaohsiung Main Urban Area in the past 36 years, thirdly using Kaohsiung Main Urban Area population data to verify the population density model and to examine the correspondence with the current society, and fourthly to explore the impact of the establishment of Kaohsiung Mass Rapid Transit System and Taiwan High Speed Rail to the transition and distribution of population in Kaohsiung Main Urban Area. This study employed the population statistical database from year 1972 to 2007, and divided the Kaohsiung metropolitan area into 32 sub-divisions. The population data was re-organized accordingly in order to perform the systematic analyses and exploration in making the understanding of the current population status and transition process. Furthermore, employing the population data of Kaohsiung metropolitan area, the validation of negative exponential model and quadratic exponential model, the population model proposed by Clark and Newling respectively 58 year ago, were performed to verify the applicability of the theories to modern society. In addition, this study also performed the exploration of population transition and distribution in Kaohsiung metropolitan area during the construction period of Kaohsiung Mass Rapid Transit System and Taiwan High Speed Rail and could be of reference to urban planning and development in the future. This study found that both Clark and Newling¡¦s population model still has high interpretation capability after 58 years later. The Kaohsiung metropolitan area population distribution model and trend forecast proposed by Ho in 1991 is still true. However, because of the slow down in overall development trend of Taiwan, the transition trend of Kaohsiung metropolitan also mitigated. Besides, due to the trend mitigation, the volcano peak phenomenon which was mentioned in the literature review will be postponed and expected to happen in year 2018.
2

Coarse Woody Debris in Industrially Managed Pinus taeda Plantations of the Southeastern United States

Pittman, Judd R. 25 August 2005 (has links)
Coarse woody debris (CWD) plays an influential role in forested ecosystems by adding organic matter to soils, stabilizing the soil environment, providing wildlife habitat, preventing soil erosion, providing seedling establishment habitat, and involvement in the nutrient cycle. Most CWD research has been conducted in old-growth and unmanaged, second-growth forests. However, less is understood about CWD in intensively managed ecosystems, such as industrialized southern pine plantations. The objectives of this study were to determine the climatic and ecological factors that affect the decomposition rate of CWD, to predict the decomposition rate, specific gravity, and time since death (TSD) using multiple linear regression in industrial loblolly pine (Pinus taeda L.) plantations in the southeastern United States. The study sites for this project were part of a long-term, loblolly pine thinning study maintained by the Loblolly Pine Growth and Yield Research Cooperative at Virginia Tech. Measurements included piece size, position, and decay class. Samples of CWD were collected and analyzed to determine their mass and density. Decomposition rate of CWD was significantly different across position classes and decay classes: disk decomposition rates were significantly negatively correlated with disk diameter, large and small end piece diameter, estimated disk height, and disk dry weight. Average annual precipitation and average annual temperature were not significantly correlated with CWD disk decomposition rate. / Master of Science
3

Analysis of Contingency Tables

Biundo, James Joseph 01 May 1969 (has links)
Two methods of analyzing multi-dimensional frequency data are detailed. The Second Order Exponential (SOE) model is applicable for dichotomous classifications. The distribution has two sets of parameters, ϴi's and ϴj's. The ϴi's are interpreted as the log of the odds of the marginal probabilities if no two factor relationships exist. Or if all ϴij are not zero, then the ϴi's are analogous to a main effect in a 2m factorial analysis, (m = number of factors or classifications). The ϴif's may be interpreted as a measure and direction of the two factor relationships. These ϴij are analogous to partial or adjusted phi-coefficients. The second method discussed assumes a multinomial distribution and the statistics are developed from an Information Theoretic Approach. Each hypothesis is tested using twice the minimum discrimination information statistic (m.d.i.s), 2I. From the null hypothesis it is possible to estimate unique cell probabilities by an iterative metod. Then 2 is equal to 2 (sample frequencies) log (sample frequencies) - 2 (expected frequencies) log (expected frequencies). (141 pages)
4

On two-sample data analysis by exponential model

Choi, Sujung 01 November 2005 (has links)
We discuss two-sample problems and the implementation of a new two-sample data analysis procedure. The proposed procedure is based on the concepts of mid-distribution, design of score functions, components, comparison distribution, comparison density and exponential model. Assume that we have a random sample X1, . . . ,Xm from a continuous distribution F(y) = P(Xi y), i = 1, . . . ,m and a random sample Y1, . . . ,Yn from a continuous distribution G(y) = P(Yi y), i = 1, . . . ,n. Also assume independence of the two samples. The two-sample problem tests homogeneity of two samples and formally can be stated as H0 : F = G. To solve the two-sample problem, a number of tests have been proposed by statisticians in various contexts. Two typical tests are the two-sample t?test and the Wilcoxon's rank sum test. However, since they are testing differences in locations, they do not extract more information from the data as well as a test of the homogeneity of the distribution functions. Even though the Kolmogorov-Smirnov test statistic or Anderson-Darling tests can be used for the test of H0 : F = G, those statistics give no indication of the actual relation of F to G when H0 : F = G is rejected. Our goal is to learn why it was rejected. Our approach gives an answer using graphical tools which is a main property of our approach. Our approach is functional in the sense that the parameters to be estimated are probability density functions. Compared with other statistical tools for two-sample problems such as the t-test or the Wilcoxon rank-sum test, density estimation makes us understand the data more fully, which is essential in data analysis. Our approach to density estimation works with small sample sizes, too. Also our methodology makes almost no assumptions on two continuous distributions F and G. In that sense, our approach is nonparametric. Our approach gives graphical elements in two-sample problem where exist not many graphical elements typically. Furthermore, our procedure will help researchers to make a conclusion as to why two populations are different when H0 is rejected and to give an explanation to describe the relation between F and G in a graphical way.
5

Comparison of prices of life insurances using different mortality rates models

Straß, Belinda January 2018 (has links)
Capturing mortality became a crucial modelling problem throughout the years due to the raising demand of life insurances and annuities. Fitting three models, namely, logistic, Heligman– Pollard HP4 and power–exponential model, to real life data shows that latter two models represent the actual data quite well. Pricing a term life insurance and a whole life annuity, implemented using the MATLAB software, based on these models ends in the result that the Heligmann–Pollard HP4 model is the less preferable model, in perspective of an insured, than the logistic or power–exponential ones.
6

Optimal Experimental Design for Poisson Impaired Reproduction Studies

Huffman, Jennifer Wade 19 October 1998 (has links)
Impaired reproduction studies with Poisson responses are among a growing class of toxicity studies in the biological and medical realm. In recent years, little effort has been focused on the development of efficient experimental designs for impaired reproduction studies. This research concentrates on two areas: 1) the use of Bayesian techniques to make single regressor designs robust to parameter misspecification and 2) the extension of design optimality methods to the k-regressor model. The standard Poisson model with log link is used. Bayesian designs with priors on the parameters are explored using both the D and F-optimality criteria for the single regressor Poisson exponential model. Since these designs are found via numeric optimization techniques, Bayesian equivalence theory functions are derived to verify the optimality of these designs. Efficient Bayesian designs which provide for lack-of-fit testing are discussed. Characterizations of D, D<sub>s</sub>, and interaction optimal designs which are factorial in nature are demonstrated for models involving interaction through k factors. The optimality of these designs is verified using equivalence theory. In addition, augmentations of these designs that result in desirable lack of fit properties are discussed. Also, a structure for fractional factorials is given in which specific points are added one at a time to the main effect design in order to gain estimability of the desired interactions. Robustness properties are addressed as well. Finally, this entire line of research is extended to industrial exponential models where different regressors work to increase and/or decrease a count data response produced by a process. / Ph. D.
7

LEAF LITTER DECOMPOSITION IN VERNAL POOLS OF A CENTRAL ONTARIO MIXEDWOOD FOREST

Otis, Kirsten Verity 12 September 2012 (has links)
Vernal pools are small, seasonally filling wetlands found throughout forests of north eastern North America. Vernal pools have been proposed as potential 'hot spots' of carbon cycling. A key component of the carbon cycle within vernal pools is the decomposition of leaf litter. I tested the hypothesis that leaf litter decomposition is more rapid within vernal pools than the adjacent upland. Leaf litter mass losses from litterbags incubated in situ within vernal pools and adjacent upland habitat were measured periodically over one year and then again after two years. The experiment was carried out at 24 separate vernal pools, over two replicate years. This is a novel degree of replication in studies of decomposition in temporary wetlands. Factors influencing decomposition, such as duration of flooding, water depth, pH, temperature, and dissolved oxygen were measured. Mass loss was greater within pools than adjacent upland after 6 months, equal after 12 months, and lower within pools than adjacent upland after 24 months. This evidence suggests that vernal pools of Central Ontario are 'hot spots' of decomposition up to 6 months, but not after 12 and 24 months. In the long term, vernal pools may reduce decomposition rates, compared to adjacent uplands.
8

Técnicas não-paramétricas e paramétricas usadas na análise de sobrevivência de Chrysoperla externa (Neuroptera: Chrysopidae) / Non-Parametric and Parametric Techniques used in the survival analysis of Chrysoperla externa (Neuroptera: Chrysopidae)

Miranda, Marconi Silva 13 March 2012 (has links)
Made available in DSpace on 2015-03-26T13:32:15Z (GMT). No. of bitstreams: 1 texto completo.pdf: 512216 bytes, checksum: fd4223913c0ad60bce75a563695255ec (MD5) Previous issue date: 2012-03-13 / In survival analysis, the response variable is the time of occurrence of an event of interest, denominated failure time. Another characteristic of the survival analysis is to incorporate to the study incomplete sample data, in which for a determined reason the occurrence of the event was not verified, being these data defined as censured. The objective of this paper was to compare the use of the parametric and non-parametric techniques to estimate the survival time of C. externa (Neuroptera: Chrysopidae), predator insect which feed on other insects as well as mite, under the effect of three commercial products nim-based: Neempro (10 g of azadirachtina L-1), Organic neem (3,3 g of Azadirachtina L-1) and Natuneem (1,5 g of azadirachtina L-1). With this objective the survival functions for the different concentrations of each product, through the non-parametric method of Kaplan-Meier were estimated and compared by the logrank test and by parametric techniques, using the Weibull and log-normal exponential tests. Besides that, a study in order to select the most parsimonious model was done, using for that the likelihood ratio test (LRT) as well as the Akaike information criterion (AIC). The estimates of the selected parametric model were used to determine the survival functions in the concentrations of the three products, with the purpose of comparing with the nonparametric estimator Kaplan-Meier. Once the best model was defined the median survival time of C. externa was calculated in the tested concentrations of the products. Taking into consideration the conditions described in this experiment, one can conclude that the concentrations of the nim-based products have influence in the survival of C. externa. The higher the concentration of the used products, the lower was the survival time and among the evaluated products, Neempro was the one which presented the least lethal to the natural predator. / Em análise de sobrevivência, a variável resposta é o tempo de ocorrência de um evento de interesse, denominado tempo de falha. Outra característica da análise de sobrevivência é incorporar ao estudo dados amostrais incompletos, que por algum motivo a ocorrência do evento não foi verificada, dados estes definidos como censurados. O objetivo deste trabalho foi comparar o uso das técnicas paramétricas e não-paramétricas para estimar o tempo de sobrevivência de C. externa (Neuroptera: Chrysopidae), inseto predador que se alimenta de outros insetos e ácaros, sob efeito de três produtos comerciais à base de nim: Neempro (10 g de azadirachtina L-1), Organic neem (3,3 g de Azadirachtina L-1) e Natuneem (1,5 g de azadiractina L-1). Com esse objetivo foram estimadas as funções de sobrevivência para as diferentes concentrações de cada produto, por meio do método não-paramétrico de Kaplan-Meier, e comparadas pelo teste logrank e por meio das técnicas paramétricas, utilizando os modelos exponencial, de Weibull e log-normal. Foi realizado ainda, um estudo com a finalidade de selecionar o modelo mais parcimonioso, utilizando para isto o teste da razão de verossimilhança (TRV) e o critério de informação de Akaike (AIC). As estimativas do modelo paramétrico selecionado foram usadas para determinar as funções de sobrevivência nas concentrações dos três produtos, com o objetivo de comparar com o estimador não-paramétrico de Kaplan-Meier. Definido o melhor modelo foi calculado o tempo mediano de sobrevivência do C. externa nas concentrações testadas dos produtos. Levando em consideração as condições descritas neste experimento, pode-se concluir que as concentrações dos produtos a base de nim possuem influencia na sobrevivência de C. externa. Quanto maior foi a concentração dos produtos utilizados, menor foi o tempo de sobrevivência e entre os produtos avaliados o Neempro foi o que apresentou ser o menos letal ao predador natural.
9

Encouraging Mothers : The effect of German regional childcare policies on maternal employment between 2006 and 2018

Schubert, Henrik-Alexander January 2020 (has links)
Childbearing is often associated with employment interruptions in women’s careers. Since 2005, the German federal government has implemented childcare reforms aiming at expanding the suitable infrastructure for children under the age of three, which should facilitate and accelerate the return to employment. The reforms have been a paradigm shift, because they show a shift from a traditional breadwinner family model to a dual earner-carer model. Despite federal leadership in childcare reforms, the characteristics of the care infrastructure in Germany vary by state and over time, which may contribute to different employment-interruption lengths. The study at hand evaluates Germany’s recent childcare reforms regarding the impact on maternal employment by examining relationships between childcare-characteristics -namely quality and availability- and mothers’ employment interruptions. A piecewise-constant exponential model is used to capture the cross-state and over time differences in childcare and their impact on the timing of women’s return to employment within the first three years after birth of their first child. The study uses individual data from the Pairfam 10.0 study and childcare indicators, which are collected by the federal and state’s statistical bureaus. The risk population includes 927 first-time mothers who gave birth between March 2006 and March 2018. Within this period, 525 first-time mothers return to employment within the first three years after childbirth.   A significant positive effect of the childcare reform on maternal employment is revealed. Both the availability expansion and the quality improvements are associated with earlier returns to employment, establishing both institutional and cultural effects of childcare policies. An educational gradient of the effect of childcare quality on maternal employment was tested, but the results were not significant.
10

Childbearing among Polish migrant women in Sweden : A country-of-origin and country-of-destination approach

Lindström, Jonathan January 2019 (has links)
This paper examines childbearing among Polish migrant women and their descendants in Sweden. While many studies have focused on immigrants' childbearing in relation to women in the destination country, this study uses a country-of-origin and a country-of-destination approach in order to more thoroughly examine the socialization, selection and adaptation hypotheses. Using a piecewise-exponential model, the transitions to first and second births are analyzed using Swedish register data and the Polish Generations and Gender survey (GGS). The results show that the Polish stayers and the first-generation have relatively similar fertility behavior in the transition to first birth but not in the transition to second birth. However, parts of the similarity in the transition to first birth can be attributed to marital status selection. By examining the 1.5-generation and the second-generation in relation to Swedish natives, it is possible to see fertility convergence across generations, both when it comes to timing and quantum. This study also shows that family migrants have higher risk of having a first child compared to migrants moving for other reasons. However, in the transition to second birth, there is no difference.

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