The Lower Mississippi Alluvial Basin (LMAB) faces significant environmental challenges due to phosphorus (P) runoff from agricultural lands, contributing to eutrophication and aquatic ecosystem degradation. Excess nutrient runoff, particularly P, threatens water quality and contributes to hypoxia in the Gulf of Mexico. The current Mississippi Phosphorus Index (P-Index), a tool for assessing P loss vulnerability from agricultural fields, has shown limitations in its applicability across the diverse conditions of the Mississippi Delta, a sub-region of the LMAB. This research presents a comprehensive revision of the P-Index by employing a suite of analytical techniques and diverse data sources, including geospatial analysis, rainfall simulations, and extensive data from soil tests, agricultural censuses, and expert evaluations. The aim was to enhance the model's sensitivity and accuracy in predicting P loss vulnerability, thereby enabling more precise nutrient management recommendations tailored to the Mississippi Delta's unique agricultural and environmental conditions. The study identified a critical lack of variability in the P-Index's recommendations for different agricultural scenarios within the region, highlighting its inadequacy in accurately reflecting the specific vulnerabilities to soil P loss. Through a detailed sensitivity analysis and recalibration of the model, incorporating updated parameters and data sources, significant improvements were achieved. The revised P-Index now better distinguishes between various agricultural practices set in the environmental conditions of the MS Delta, offering differentiated recommendations that align closely with the region's real-world complexities. Furthermore, the research underscores the necessity for ongoing investigations into the equivalencies between different soil test P methods (Lancaster and Mehlich-III) and the impact of P levels in irrigation water on nutrient cycling and loss. The recalibrated P-Index represents a significant step forward in regional nutrient management strategies, promising enhanced environmental protection and agricultural sustainability through more informed and targeted recommendations. This work emphasizes the critical need for adapting nutrient management tools like the P-Index to regional conditions, ensuring they accurately address the environmental challenges and agricultural practices specific to areas like the Mississippi Delta. Keywords: Nutrient management, Phosphorus Index, Mississippi Delta, Agricultural runoff, Soil test phosphorus, Environmental sustainability, Sensitivity analysis, Trend analysis.

The revolutionisation of international economies and monetary systems has been taking place since the early 1970s. This occurred due to the diminishing fixed exchange rate systems of, initially, the Gold Standard and subsequently the Bretton Woods System. The collapse of these systems, especially the Bretton Woods System, led to the almost free movement of exchange rates. The lack of restriction placed on the movement of currencies created volatile markets; which, in turn, gave rise to an innumerable amount of risks. In Correia, Holman and Jahreskog (2012) it was determined that an astonishing 74% of non-financial firms in South Africa hedge foreign exchange risk (the risk of currency movement). The 10% of firms which did not hedge any risks declared it was due to the lack of exposure to foreign exchange risks and that the cost of acquiring a hedging contract, in many cases, exceeded the contract’s benefits. In the aforementioned study it was also established that the extractive sector of South Africa is one of the industries referring from the use of hedges. The intention of this study is to improve the effectiveness of derivative instruments for companies in the extractive sector of South Africa exporting to the United States of America. South Africa is a large exporter and importer of goods, making it extremely important for market participants to determine the movement of the exchange rates. This estimates the amount of risk a company is willing to take and the amount of hedges they will use to protect themselves against inauspicious and adverse movements in the markets. Therefore, incorporated in this study is the use of risk management tools from the technical analysis to predict the exchange rates at which companies should have set their hedging contracts on specific dates. This analysis could enable companies to perform an internal control that is inexpensive and which reduces risks of foreign exporting. / MCom (Management Accountancy), North-West University, Potchefstroom Campus, 2014

The revolutionisation of international economies and monetary systems has been taking place since the early 1970s. This occurred due to the diminishing fixed exchange rate systems of, initially, the Gold Standard and subsequently the Bretton Woods System. The collapse of these systems, especially the Bretton Woods System, led to the almost free movement of exchange rates. The lack of restriction placed on the movement of currencies created volatile markets; which, in turn, gave rise to an innumerable amount of risks. In Correia, Holman and Jahreskog (2012) it was determined that an astonishing 74% of non-financial firms in South Africa hedge foreign exchange risk (the risk of currency movement). The 10% of firms which did not hedge any risks declared it was due to the lack of exposure to foreign exchange risks and that the cost of acquiring a hedging contract, in many cases, exceeded the contract’s benefits. In the aforementioned study it was also established that the extractive sector of South Africa is one of the industries referring from the use of hedges. The intention of this study is to improve the effectiveness of derivative instruments for companies in the extractive sector of South Africa exporting to the United States of America. South Africa is a large exporter and importer of goods, making it extremely important for market participants to determine the movement of the exchange rates. This estimates the amount of risk a company is willing to take and the amount of hedges they will use to protect themselves against inauspicious and adverse movements in the markets. Therefore, incorporated in this study is the use of risk management tools from the technical analysis to predict the exchange rates at which companies should have set their hedging contracts on specific dates. This analysis could enable companies to perform an internal control that is inexpensive and which reduces risks of foreign exporting. / MCom (Management Accountancy), North-West University, Potchefstroom Campus, 2014

No description available.

Work is aimed at the time-frequency decomposition of a signal application for monitoring the EKG trend progression. Goal is to create algorithm which would watch changes in the ST segment in EKG recording and its realization in the Matlab program. Analyzed is substance of the origin of EKG and its measuring. For trend calculations after reading the signal is necessary to preprocess the signal, it consists of filtration and detection of necessary points of EKG signal. For taking apart, also filtration and measuring the signal is used wavelet transformation. Source of the data is biomedicine database Physionet. As an outcome of the algorithm are drawn ST segment trends for three recordings from three different patients and its comparison with reference method of ST qualification. For qualification of the heart stability, as a system, where designed methods watching differences in position of the maximal value in two-zone spectrum and the Poincare mapping method. Realized method is attached to this thesis.

The objective of the Dissertation was to describe, quantify and interpret to which degree the shape and size of the facial skeleton of people living in the territory of today's Czech Republic in the period from the Early Middle Ages to the present day, i.e. in the course of the approx. last 1200 years, have changed. In this time period, morphological differences between populations, changes in the sexual dimorphism, modularity and allometry of the facial skeleton were examined. The evaluation was based on CT-images of skulls from three historical populations, specifically from the Early Middle Ages, High Middle Ages and the early modern period. The current population was represented by CT-images of living people. We studied the facial skeletons of a total of 329 individuals, of which 183 were men and 146 women. The CT- images were used as a base for the creation of virtual 3D surface models. The facial skeleton was divided into three morphological units, which were further examined. These were the skeleton of the upper face, lower jaw and palate. The statistical processing was carried out applying methods of geometric morphometrics allowing the separate studying of the shape and size variability of the examined units. When comparing the size and shape differences between studied populations it is...

In this dissertation, a new non-global regression model - the partial linear threshold regression model (PLTRM) - is proposed. Various issues related to the PLTRM are discussed. In the first main section of the dissertation (Chapter 2), we define what is meant by the term “non-global regression model”, and we provide a brief review of the current literature associated with such models. In particular, we focus on their advantages and disadvantages in terms of their statistical properties. Because there are some weaknesses in the existing non-global regression models, we propose the PLTRM. The PLTRM combines non-parametric modelling with the traditional threshold regression models (TRMs), and hence can be thought of as an extension of the later models. We verify the performance of the PLTRM through a series of Monte Carlo simulation experiments. These experiments use a simulated data set that exhibits partial linear and partial nonlinear characteristics, and the PLTRM out-performs several competing parametric and non-parametric models in terms of the Mean Squared Error (MSE) of the within-sample fit. In the second main section of this dissertation (Chapter 3), we propose a method of estimation for the PLTRM. This requires estimating the parameters of the parametric part of the model; estimating the threshold; and fitting the non-parametric component of the model. An “unbalanced penalized least squares” approach is used. This involves using restricted penalized regression spline and smoothing spline techniques for the non-parametric component of the model; the least squares method for the linear parametric part of the model; together with a search procedure to estimate the threshold value. This estimation procedure is discussed for three mutually exclusive situations, which are classified according to the way in which the two components of the PLTRM “join” at the threshold. Bootstrap sampling distributions of the estimators are provided using the parametric bootstrap technique. The various estimators appear to have good sampling properties in most of the situations that are considered. Inference issues such as hypothesis testing and confidence interval construction for the PLTRM are also investigated. In the third main section of the dissertation (Chapter 4), we illustrate the usefulness of the PLTRM, and the application of the proposed estimation methods, by modelling various real-world data sets. These examples demonstrate both the good statistical performance, and the great application potential, of the PLTRM. / Graduate

This dissertation is an empirical modeling investigation of the impact of forest harvesting, climate change and topography on stream nitrate fluxes in the Turkey Lakes Watershed (TLW), Ontario, Canada. Data used for this study include topography (DEM), climate (mean monthly temperature and total monthly precipitation), wet nitrogen deposition (total monthly nitrate-N and ammonium-N), nitrate water samples and streamflow in 13 headwater catchments within the TLW. First, a paired-watershed approach was used to examine the impact of forest harvesting intensity on stream water nitrate fluxes by developing transfer function noise (TFN) models that related monthly stream water nitrate fluxes of three treatment catchments to those of one control catchment. Second, TFN models were also developed to relate monthly stream nitrate fluxes in 13 catchments to the temperature, precipitation and wet nitrogen deposition to examine the spatially varying responses of stream nitrate fluxes to changes in climate and bulk deposition. Third, geographically weighted regression (GWR) was introduced to model the spatial and temporal relationships between topography and stream nitrate fluxes in 13 headwater catchments. The results showed that there existed a new phenomenon of clustered wave-up and wave-down of the stream nitrate increases caused by clearcut and selectioncut at the monthly scale, respectively. This phenomenon was never reported by previous studies because it was not possible to be identified with ordinary least squares (OLS) regression at an annual scale. There also existed significant responses of stream nitrate fluxes to wet nitrogen deposition in all catchments at the monthly scale over a long-term record between 1982 and 2003. These responses were previously thought to be lower and masked by the impact of climate variations. There further existed significant spatial and seasonal variability of the relationships between topography and stream nitrate fluxes across space and over time. This variability was largely ignored in previous studies with possibly misleading interpretation on the empirical relations. / Thesis (Ph.D, Geography) -- Queen's University, 2012-12-31 22:37:39.137

OBJECTIVES: To determine the pattern and predictors of use of antiplatelet agents and beta-blockers given in the emergency department (ED) to older adults with acute myocardial infarction (AMI) and its effects on in-hospital mortality and length of hospital stay (LOS) and to determine the effect of computerized ED guideline reminders on their utilization. METHODS: A cross-sectional study using the National Hospital Ambulatory Medical Care Survey (NHAMCS) ED data for years 1992 to 2010 was conducted. Patients were included if they had an admission diagnosis of AMI (ICD-9-CM code 410.xx) and were ≥55 years. Survey logistic regression was used to examine whether there was a trend in the use of antiplatelet agents and beta-blockers across the years and to explore the association between various predictor variables, including ED computerized guideline reminders, and their utilization rates. The chi-square test was used to see whether users of these drugs were different from non-users in their rates of in-hospital mortality. Survey linear regression was used to explore the effect of utilization of these drugs on LOS. All the visits were weighted to get national estimates. All of the analyses were carried out with SAS 9.3 statistical package. RESULTS: A total of 1,771 visits (weighted frequency = 6.1 million) were eligible for this study. Both antiplatelet agents and beta-blockers were shown to have a positive trend across the years. Age, sex, chest pain, triage, using an ambulance, and metropolitan region were all found to be significant predictors of either antiplatelet agent or beta-blocker utilization. Use of beta-blockers was associated with lower in-hospital mortality. Neither drug class had an effect on LOS. Finally, patients who were treated in EDs with computerized guideline reminders were twice as likely to get an antiplatelet agent, but this was not seen with beta-blockers. CONCLUSION: This study displayed a positive pattern across the years in the use of antiplatelet agents and beta-blockers given to older AMI patients. It also showed that age, sex, and other important variables were significant predictors of their utilization. The use of beta-blockers yielded lower in-hospital mortality. Finally, the use of ED reminders increased antiplatelet agent utilization.

Ce mémoire a pour but de déterminer des nouvelles méthodes de détection de rupture et/ou de tendance. Après une brève introduction théorique sur les splines, plusieurs méthodes de détection de rupture existant déjà dans la littérature seront présentées. Puis, de nouvelles méthodes de détection de rupture qui utilisent les splines et la statistique bayésienne seront présentées. De plus, afin de bien comprendre d’où provient la méthode utilisant la statistique bayésienne, une introduction sur la théorie bayésienne sera présentée. À l’aide de simulations, nous effectuerons une comparaison de la puissance de toutes ces méthodes. Toujours en utilisant des simulations, une analyse plus en profondeur de la nouvelle méthode la plus efficace sera effectuée. Ensuite, celle-ci sera appliquée sur des données réelles. Une brève conclusion fera une récapitulation de ce mémoire. / This thesis aims to identify new change-point detection methods and/or trend in temporal data. After a brief theoretical introduction on splines, several existing change-point detection already in the literature will be presented. Then, new change-point detection methods using splines and Bayesian statistics will be presented. Moreover, in order to understand the method using Bayesian statistics, an introduction to Bayesian theory will be presented. Using simulations, we will make a comparison of the power of all these methods. Still using simulations, an analysis of the new most effective method will be performed. Then, this method will be applied to real data. A brief conclusion will make a summary of this thesis.