This dissertation explores the adoption of Best Management Practices (BMPs) in the Kentucky River watershed. Through a survey of farmers in the Kentucky River watershed, chapter two investigates farmers’ current BMP adoption and their willingness to engage in additional adoption incentivized through a proposed Water Quality Trading (WQT) program. This chapter includes two parts: the first part is to investigate the factors influencing farmers’ current usage of BMPs; the second part is to estimate farmers’ willingness to implement BMPs given different levels of compensation specified in the survey. Farmers’ experiences about BMPs are more likely to persuade them to adopt additional BMPs. The activities of using riparian buffers, fencing off animals and building up waste storage facilities are found to be responsive to the levels of compensation offered. The third chapter discusses farmers’ expected economic benefits from BMP adoption, and addresses the missing data issue. In the survey, of those respondents who indicated that they accept the offered level of compensation, about 20% of them did not answer the follow-up question of how much they would adopt the practice, creating missing data. We compare three methods to handle the issue of missing data: deletion method, mean imputation, and multiple imputation method. Following these methods, we estimate factors affecting how much farmers may engage in BMPs using a Tobit or Poisson model. The results show that increasing the compensation for using BMPs is more likely to encourage farmers to adopt riparian buffers. Results obtained using the method of multivariate imputation by chained equation are more promising than using the deletion or mean imputation method. The fourth chapter examines whether wealth change and local community interaction may affect BMP adoption. Survey data on BMP adoption are combined with the local community data from publically available sources. Results show that the decrease in land values between 2007 and 2012 discouraged the adoption of riparian buffers; the equine inventory in local communities has positive impact on the adoption of animal fences and nutrient management; the more rural the local communities are, the less likely farmers would fence off livestock from water resources.

Missing data is one of the challenges we are facing today in modeling valid statistical models. It reduces the representativeness of the data samples. Hence, population estimates, and model parameters estimated from such data are likely to be biased. However, the missing data problem is an area under study, and alternative better statistical procedures have been presented to mitigate its shortcomings. In this paper, we review causes of missing data, and various methods of handling missing data. Our main focus is evaluating various multiple imputation (MI) methods from the multiple imputation of chained equation (MICE) package in the statistical software R. We assess how these MI methods perform with different percentages of missing data. A multiple regression model was fit on the imputed data sets and the complete data set. Statistical comparisons of the regression coefficients are made between the models using the imputed data and the complete data.

During the period of October 1974 to August 1976, a study was conducted to measure the effects of surface soil removal on plant production, plant transpiration rates, nitrate nitrogen mineralization rates, and selected hydrologic parameters (infiltration rates, potential sediment production, and chemical quality of runoff water). The treatments were incremental 7.6 centimeter soil layers to a depth of 30.5 centimeters. Plant production and transpiration ratios (or water use efficiencies) were measured in greenhouse studies using Agrogyron desertorum grown in the incremental 7.6 centimeter soil layers from five study sites throughout the state of Utah, (Blanding, Brush Creek, Milford, Huntington, and Dove Creek). Significant decreases in plant production and increases in transpiration ratios were measured for all sites at incremental depths beyond 7.6 centimeters. These changes in plant production and transpiration ratios were found to be linearly related to the nitrate nitrogen content of the soils as determined at the time the soils were collected for use in the greenhouse. Nitrogen mineralization rates for a 6 week period were measured under field conditions at Milford and Blanding for each of the 7.6 centimeter incremental soil layers. Nitrate nitrogen mineralization was linearly correlated to the organic carbon content of the soil. Decreased mineralization rates as measured in the field at both study sites were reflected in significant increases in plant water requirements and also decreases in production as measured in greenhouse studies. Hydrologic parameters were measured at each 7.6 centimeter incremental soil depth using a Rocky Mountain infiltrometer. With one exception, significant differences in infiltration capacities among treatment depths did not occur during either 1975 or 1976 at either the Blanding or Milford site. At the Blanding site a significant decrease in the infiltration capacity occurred beyond the 22.9 centimeter depth due to a hardpan development. A significant change in infiltration capacities was noted between the 1975 and 1976 field seasons as pooled over both treatment depths and study sites. There were no significant differences in potential sediment production between sites or among treatment depths within a site. In terms of runoff water quality, a significant change in phosphorus was observed only at the Blanding site between the 1975 and 1976 field seasons. Significant differences in potassium concentrations were found to exist between sites and among soil depths.

A statistician's job is to produce statistical models. When these models are precise and unbiased, we can relate them to new data appropriately. However, when data sets have missing values, assumptions to statistical methods are violated and produce biased results. The statistician's objective is to implement methods that produce unbiased and accurate results. Research in missing data is becoming popular as modern methods that produce unbiased and accurate results are emerging, such as MICE in R, a statistical software. Using real data, we compare four common imputation methods, in the MICE package in R, at different levels of missingness. The results were compared in terms of the regression coefficients and adjusted R^2 values using the complete data set. The CART and PMM methods consistently performed better than the OTF and RF methods. The procedures were repeated on a second sample of real data and the same conclusions were drawn.

Объект исследования – линейно-цепочечный углерод на подложке кремния. Цель работы – моделирование синтеза цепочечного углерода методом гибридной молекулярной динамики. Методы исследования: гибридная квантово-классическая молекулярная динамика. В ходе выполнения данной магистерской диссертации на языке Python были написаны программы, запускающие моделирование квантово-классической молекулярной динамики. В результате был разработан модуль для реализации электростатического подхода QM/MM вычислений. На основе данного модуля было произведено моделирование ионно-плазменного синтеза углеродной пленки. Анализа полученных структур показал, что содержание sp1, sp2, sp3 углерода в пленке максимально при энергиях аргона 40, 70, 90 эВ соответственно. / The object under study is linear-chained carbon on a silicon substrate. The aim of this work is linear-chained carbon synthesis simulation by the hybrid molecular dynamics. Research methods: hybrid quantum-classical molecular dynamics. In the course of this master's dissertation, Python programs were written. That programs run the simulation of quantum-classical molecular dynamics. As a result, a module was developed to implement the electrostatic approach of QM/MM calculations. On the basis of this module, modeling of the ion-beam plasma synthesis of a carbon film was carried out. The obtained structures analysis showed that the content of sp1, sp2, and sp3 carbon in the film is maximum at argon energies of 40, 70, and 90 eV, respectively.

Left heart disease often results in left heart failure and right ventricular dysfunction which is challenging to diagnose with traditional diagnostic approaches. To address this a novel empirical 4-point right ventricular dysfunction score was created at Sahlgrenska University Hospital to overcome the limitations of single variables for diagnosing right ventricular dysfunction. In this study, we used machine learning, more specifically XGBoost coupled with interactive machine learning to develop four different models for predicting death or receiving a left ventricular assist device in patients with left heart disease (n=486). Features were selected from the dataset using recursive feature elimination with the default number of features. The initial model with 29 features, called the baseline model served as the foundation of the three additional models, each adjusted based on feedback from a clinician. The first step of feedback included removing features due to high correlation, creating a modified model with 12 features, the second step was to use 12 well-known characteristics of left and right ventricular dysfunction creating an empirical model, and adjusting the prediction threshold from 50% to 60%. The third step was to reduce the number of features to 5 based on empirical grounds. The models were compared to the right ventricular dysfunction score using the metrics area under the curve, f1 score, positive likelihood ratio, and negative likelihood ratio. The predictive efficacy of the machine learning models was superior compared to the right ventricular dysfunction score. The results also indicated that the models did neither improve nor deteriorate when reducing the number of features. However, insufficient accuracy indicates that none of the machine learning models are clinically viable. These results show the potential of machine learning in enhancing prognostic stratification in patients with left heart disease although further refinement is necessary for clinical use. / Vänstersidig hjärtsjukdom resulterar ofta i vänstersidig hjärtsvikt och högerkammarsvikt vilket är utmanade att diagnostisera med traditionella diagnostiska metoder. För att komma undan med begränsningen med enskilda variabler för att diagnostisera högerkammarsvikt skapades ett 4 poängs högerkammarsvikt score vid Sahlgrenska Universitetssjukhuset. I denna studie användes en XGBoost-algoritm kombinerat med interaktiv maskininlärning för att utveckla fyra olika prediktions modeller för att förutsäga dödlighet eller risken att få en mekanisk hjärtpump för vänster kammare hos patienter med vänster hjärtsvikt (n=486). Variabler valdes från datamängden med hjälp av rekursiv funktionseliminering med ett standardantal variabler. Den initiala modellen med 29 variabler kallades baslinjemodellen och fungerade som grunden för de tre ytterligare modellerna som justerades baserat på klinikerns feedback. Det först steget inkluderade att ta bort variabler med inbördes hög korrelation och vi skapade en modifierad modell med 12 variabler. I det andra steget i den empiriska modellen använde vi 12 kända egenskaperna vid vänsterkammar- och högerkammarsvikt och för båda justerades tröskelvärdet för prediktion från 50% till 60%. I ett tredje steg skapade vi en förenklad modell med 5 variabler ut ifrån klinisk grund. Modellerna jämfördes med höger hjärtsvikts 4 poängskalan med hjälp av mätvariablerna area under kurvan, f1-poäng, positivt sannolikhets ratio och negativt sannolikhets ratio. Detta avslöjade att maskininlärnings modellerna hade bättre prediktiv förmåga än 4-poängs högerkammarsvikt score. Dessutom visade resultatet att modellerna inte försämrades eller förbättrades när variabler valdes bort eller när nya modeller skapades på klinisk grund. Dock hade maskininlärnings modellerna otillräcklig noggrannhet för klinisk användning.

In Norway there are plans of a ferry-free European road E39 with crossings of eight deep and wide fjords. A newly developed bridge concept that could be used for some of these fjord-crossings is a chained floating bridge. One of the challenges for the chained floating bridge is to create a convenient shipping-lane under the bridge, where one suggestion is to connect the chained floating bridge with a single pylon cable-stayed bridge. The aim of this thesis is to design and evaluate a cable-stayed bridge in connection with a chained floating bridge. The purpose is to evaluate the feasibility of such a design by conducting a case study of the crossing of Bjørnefjorden. A design of a bridge is created for the case based on a literature study of conventional cable-stayed bridges. The bridge design is modelled, analyzed and the structural integrity is evaluated with SOFiSTiK (a finite element software for structural design) according to Eurocode. The study concludes that the concept is feasible for Bjørnefjorden by providing a possible design of a cables-stayed bridge connected to a chained floating bridge with conventional cross sections. The analysis in the thesis confirms the structural integrity of the consept. The bridge design’s main span is 300m long, it has a 25m wide steel box girder where the cables (φ140mm) are placed in two planes with a spacing of 15m along the girder. It has a 184 m high A-shaped pylon with a concrete box section from the foundation up to the girder level (+50m), to the top is a steel box (3.5x3.5m). The bridge is designed with material properties according to Eurocode, where steel class S355 and concrete C45 are used. A parametric research also verifies the design’s feasibility for other geometries of chained floating bridges - where the horizontal reactions on the cable-stayed bridge vary in a range of 107MN-242MN. The parametric research confirms that both the utilization of the cross section and the stability increases with the horizontal reaction from the chained floating bridge. The parametric study also concludes that a width of 8m between the pylon legs decreases the effect on the lower part of the pylon and the support reaction at the pylon when compared with a 12m and a 18m width. However, the average utilization of the girder, cable and steel part of the pylon increases when the 8m width is compared with a 12m or a 18m wide pylon. A fan or radial cable arrangement compared to harp design is more efficient for the cables and the displacements of the girder in Z-direction. They are however, less efficient for the bottom part of the pylon than the harp arrangement. / I Norge planeras en färjefri Europaväg E39, där åtta djupa och breda fjordar ska förbindas med broar eller tunnlar. För att korsa några av fjordarna utvecklas bla. ett brokoncept med kedjeflytbro. En av utmaningarna i konceptet är att skapa en farled för fartyg under bron. Ett förslag är att koppla ihop kedjeflybron med en ”halv” snedkabelbro som har en pylon (inte två), där farleden går under huvud­spannet till snedkabelbron. Avsikten med detta examensarbete är att konstruera och utvärdera en snedkabelbro ihopkopplad med en kedjeflytbro. Syftet är att utvärdera om konceptet med snedkabelbro är genomförbart, med hjälp av en fallstudie av Bjørnefjordsförbindelsen. En konventionell design av en snedkabelbro upprättas efter fallets villkor med hjälp av en literaturstudie. Designen modelleras, analyseras och dimensioneras enligt Eurokod med analysverktyget SOFiSTiK. Slutsatsen är att konceptet med en snedkabelbro ihopkopplad med en kedjeflytbro är genomförbart då det är möjligt att designa en sådan med konventionella tvärsnitt. Analysen i rapporten bekräftar att designen har tillräcklig bärförmåga. I designen är huvudspannet 300m långt och består av en 25m bred brobalk upphängd av (φ140mm) kablar placerade i två plan var 15m. Bron har en 184m hög A-formad pylon med ett lådtvärsnitt i betong från fundament till brobalksnivån (+50m), därifrån till pylontoppen är tvärsnittet en stålbox (3.5x3.5m). Bron är dimensionerad med materialparameterar enligt Eurokod, där stålkvalitet S355 och Betong C45 har använts. En utförd parameterstudie bekräftar också konceptets genomförbarhet för andra geometrier av kedjeflytbron – där den horisontella reaktionen på snedkabelbron varierar mellan 107MN och 242MN. Parameterstudein bekräftar att både utnyttjandet av tvärsnittskapasiteten och stabiliteten ökar med den horisontella reaktionen från kedjeflytbron. Dessutom konkluderar parameterstudien att bredden 8m mellan pylonbenen minskar lasteffekten på den nedre delen av pylonen och stödreaktionen vid pylonen jämfört med bredden 12m och 18m. Däremot ökar medelutnyttjandet av tvärsnittaskapasiteten för brobalken, kablarna och ståldelen av pylonen för bredden 8m jämfört med 12m eller 18m. En radiell- eller solfjäderformad kabelkonfiguration jämfört med parallellformad design är mer effektiv för kablarna och nedböjning av brobalken. De gör däremot så att den den nedre delen av pylonen får större snittkrafter än för den parallellformade kabelkonfigurationen.

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