Monte Carlo radiation transfer provides an efficient modelling tool for probing the dusty local environment of young stars. Within this thesis, such theoretical models are used to study the disk structure of objects across the mass spectrum - young low mass Brown Dwarfs, solar mass T-Tauri stars, intermediate mass Herbig Ae stars, and candidate B-stars with massive disks. A Monte Carlo radiation transfer code is used to model images and photometric data in the UV - mm wavelength range. These models demonstrate how modelling techniques have been updated in an attempt to reduce the number of unknown parameters and extend the diversity of objects that can be studied.

In this thesis, graphene (i.e. monolayer carbon film) and carbon clusters supported on a transition metal surface are systematically studied by local probe techniques, with respect to their structures, electronic properties and formation mechanisms. The main tools used are low-temperature scanning tunnelling microscopy and spectroscopy (STM and STS), which are introduced in Chapter 2. The mechanism of the resonance tunnelling at electron energies higher than the work function of the surface is discussed in detail, and a qualitative explanation of the Gundlach oscillations in the corresponding spectroscopy is presented. Epitaxial graphene synthesised on the Rh(111) surface by ethylene dehydrogenation is investigated by STM in Chapter 4. Such carbon film exhibits a hexagonal Moiré pattern due to a lattice mismatch between graphene and the rhodium substrate. The periodicity and local registries of the graphene/Rh(111) superstructure are carefully analysed. Based on a thorough discussion about the “commensurate vs. incommensurate” nature of the Moiré pattern in surface science field, the graphene/Rh(111) system is identified to have a non-simple-commensurate superstructure. The surface electronic properties and geometric buckling of graphene/Rh(111) are investigated by resonance tunnelling spectroscopy (RTS) and density functional theory (DFT) calculations in Chapter 5. Spectroscopy measurements reveal a modulation of the electronic surface potential (or work function Φ) across the supercell of epitaxial graphene. Based on the microscopy/spectroscopy data and the extended DFT calculations, we examined the electronic coupling of the various local C-Rh registries, and identified both experimentally and theoretically the local atomic configurations of maximum and minimum chemical bonding between graphene and the rhodium substrate. We studied in Chapter 6 the growth mechanism of graphene on Rh(111) at elevated temperatures. This part starts by investigating the dehydrogenation of ethylene into ethylidyne. When the dehydrogenation process is complete, monodispersed carbon species, identified as 7C6, are found to dominate the cluster population on the rhodium terraces. A significant coalescence of the 7C6 clusters into graphene islands occurs at temperatures higher than 873 K. The structural and electronic properties of the 7C6 carbon clusters are examined by high-resolution STM and STS, and compared with coronene molecules, i.e. the hydrogenated analogues of 7C6. DFT calculations are further used to explain the stability of 7C6 supported on the Rh(111) surface, and also the structural characteristics of such magic-sized carbon clusters.

Integrated water resources management has been used for decades in various formats. The limited resources and the ever growing population keep imposing pressure on decision makers to better-, and reliably, manage the available waters. On the other hand, the continuous development in computing and modeling power has helped modelers and decision makers considerably. To use these models, assumptions have to be made to fill in the gaps of missing data and to approximate the current conditions. The type and amount of information available can also be used to help select the best model from the currently available models. Advances in data collection have not kept up to the pace of advances in model development and the need for more and reliable input parameter values. Hence, uncertainty in model input parameters also needs to be quantified and addressed. This research effort develops a spatially-based modeling framework to model watersheds from both water quantity and quality standpoints. In this research, Gridded Surface Sub-Surface Hydrologic Analysis (GSSHA) and CE-QUAL-W2 models are linked within the Watershed Modeling System (WMS); a GIS interface for hydrologic and hydraulic models, to better handle both models pre and post processing. In addition, stochastic analysis routines are developed and used to examine and address the uncertainty inherent in the modeling process of the interface between land and water in the designated watershed. The linkage routines are developed in WMS using C++. The two models are linked spatially and temporally with the general direction of data flow from GSSHA to CE-QUAL-W2. Pre-processing of the CE-QUAL-W2 model is performed first. Then stochastic parameters and their associated distributions are defined for stochastic analysis in GSSHA before a batch run is performed. GSSHA output is then aggregated by CE-QUAL-W2 segments to generate multiple CE-QUAL-W2 runs. WMS then reads the stochastic CE-QUAL-W2 runs upon successful completion for data analysis. Modelers need to generate a WMS Gage for each location where they want to examine the stochastic output. A Gage is defined by a segment and a layer in the CE-QUAl-W2 model. Once defined, modelers are able to view a computed credible interval with lower, upper bounds in addition to the mean time series of a pre-selected constituent. Decision makers can utilize this output to better manage watersheds by understanding and incorporating the spatio-temporal uncertainty for the land-water interface.

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No. of bitstreams: 2 Tese - Aline de Arvelos Salgado - 2018.pdf: 8292746 bytes, checksum: b28ed506e404b8c0b4373382d667712a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-06-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Shallow reservoirs, with large surface area and long hydraulic retention times, present conditions conducive to the development of cyanobacteria. Due to the potential risk that cyanobacteria can cause to public health, the importance of the management of water bodies to control the toxic blooms, especially in reservoirs destined to the public supply, is evident. Thus, there is a clear need to develop techniques that can help existing monitoring, with the possibility of extending the area of ​​coverage in monitoring programs. Thus, the present study aimed to combine several methods of data acquisition, mainly obtaining continuously, such as the use of sensors for in situ evaluation of phytoplankton, especially cyanobacteria, through the detection of chlorophyll-a and phycocyanin, as well as the use of remote sensing for phytoplankton monitoring and with this information to build water quality prediction scenarios through mathematical modeling. The procedure aimed to improve data acquisition, especially the spatialization of data. For this purpose, the dynamics and water quality of the João Leite reservoir was characterised over 30 months using physical, chemical and biological parameters and trophic status index, to know the seasonality of the quality of the of the water body and present the main parameters and factors of water quality change. A continuous and spatial phytoplankton monitoring method was proposed for mapping concentrations of chlorophyll- a and cyanobacteria from Sentinel-2 satellite images with in situ and inferential observations to evaluate the performance of these to provide information on cyanobacterial blooms. The CE-QUAL-W2 model was calibrated from field data to evaluate the water quality dynamics and hydrodynamics of the reservoir. As a result, João Leite reservoir presented characteristic and similar patterns of the variation of the parameters in hydrological periods, and the results showed that the use and the occupation of the soil reflect in the characteristics of the quality of the water. In the majority of the evaluated points and times, good oxygenation of the waters and low concentrations of nutrients were demonstrated, being proved by the trophic state indexes. Both chlorophyll-a and cyanobacteria showed correlation between data measured in situ and estimated. The results can considered satisfactory since with the data of reflectance it was possible to validate the atmospheric correction, and the maps of estimate of chlorophyll- a and cyanobacteria presented the places and the months more prone to the greater proliferation of cyanobacteria. Thus, these results demonstrate the importance of the use of remote sensing for the monitoring of water quality, since with the use of this tool there is greater possibility of point coverage, being able to have a synoptic visualisation of the studied environment, identifying the most subject areas to the proliferation of cyanobacteria. The results of the modeling indicate that the reservoir presents periodic stratification, and in the warmer months the stratification is more evident and that in the colder months a mixture of the water column is noticed, possibly due to in those months there are more incidental winds in the region. In general, the highest values ​​of algae and cyanobacteria occur in the warmer months, where there is a higher solar incidence and larger periods of thermal stratification occur. It was also presented that the amount of algae and cyanobacteria on the surface changes the amount of oxygen dissolved in the surface region while the demand for sediment oxygen may be associated with both the oxygen consumption in the sediments and can also be used as a way to simulate the consumption of oxygen by the submerged organic matter, which is visible in the shallower areas of the reservoir. The results of the CE-QUAL-W2 model provided a comprehensive understanding of the spatial and temporal dynamics of the parameters analyzed during the modeling periods. The application of this model with the integration of fluorometers and remote sensing for the evaluation of water quality, should be better suited to water resource managers, to help them better understand the dynamics of physicochemical and biological processes and to be used as a warning system in cases of cyanobacteria blooms and to propose the best mitigation strategies. / Reservatório de água lênticos, rasos, com grande área de superfície e longos tempos de retenção hidráulica apresentam condições propícias para o desenvolvimento de cianobactérias. Devido o potencial risco que cianobactérias podem causar a saúde pública, evidencia-se a importância do gerenciamento dos corpos hídricos a fim de controlar as florações tóxicas, principalmente em reservatórios destinados ao abastecimento público. Assim, há uma clara necessidade de desenvolver técnicas que possam auxiliar os monitoramentos existentes, com a possibilidade de estender a área de abrangência em programas de monitoramento. O objetivo geral dessa pesquisa é avaliar um método de monitoramento contínuo e espacial de fitoplâncton, especialmente quanto à presença de cianobactérias, por meio da ficocianina e clorofila “a”, de modo a se ter informações de qualidade da água, para efetuar a previsão de cenários da dinâmica de cianobactérias, empregando modelagem matemática. Para tanto, foi caracterizada a dinâmica e a qualidade das águas do reservatório João Leite, ao longo de 30 meses, por meio de análises dos parâmetros físicos, químicos e biológicos, e índice de estado trófico, a fim de conhecer a sazonalidade da qualidade da água do corpo hídrico e apresentar os principais parâmetros e fatores de alteração da qualidade das águas. Foi proposto um método de monitoramento contínuo e espacial de fitoplâncton, para confecção de mapas de concentrações de clorofila “a” e cianobactérias a partir de imagens do satélite Sentinel-2, com observações in situ e a partir de inferências, para avaliar o desempenho desses em fornecer informações sobre proliferações de cianobactérias. Por último, o modelo CE-QUAL-W2 foi calibrado a partir de dados obtidos em campo, para avaliar a dinâmica da qualidade da água e hidrodinâmica do reservatório. Como resultado, o reservatório João Leite apresentou padrões característicos e semelhantes da variação dos parâmetros em períodos hidrológicos e os resultados demonstraram que o uso e a ocupação do solo refletem nas características da qualidade da água. Na maior parte dos pontos e tempos avaliados, foram apresentadas boa oxigenação das águas e baixas concentrações de nutrientes, sendo comprovados pelos índices de estado trófico. Tanto a clorofila “a” quanto cianobactérias demonstraram correlações entre os dados medidos in situ e os estimados. Os resultados podem ser considerados satisfatórios, uma vez que com os dados de refletância foi possível validar a correção atmosférica e os mapas de estimativa de clorofila “a” e cianobactérias apresentaram os locais e os meses mais propensos à maior proliferação de cianobactérias. Assim, esses resultados demonstram a importância do uso do sensoriamento remoto para o monitoramento da qualidade das águas, uma vez que com o uso dessa ferramenta há maior possibilidade de abrangência de pontos, podendo ter uma visualização sinóptica do ambiente estudado, identificando as áreas mais sujeitas à proliferação de cianobactérias. Os resultados da modelagem indicam que o reservatório tem a tendência a se comportar com estratificação periódicas, sendo que nos meses mais quentes a estratificação é mais evidente e que nos meses mais frios uma mistura da coluna d’água é notada, possivelmente em função de que nesses meses há mais ventos incidentes na região. De um modo geral, os maiores valores de algas e cianobactérias ocorrem nos meses mais quentes, em que há maior incidência solar e ocorre maiores períodos de estratificação térmica. Foi ainda apresentado que a quantidade de algas e cianobactérias na superfície altera a quantidade de oxigênio dissolvido na região da superfície enquanto a demanda por oxigênio sedimentar, pode estar associado tanto ao consumo de oxigênio nos sedimentos quanto pode ser também usada como forma de simular o consumo de oxigênio pela matéria orgânica submersa, que é visível nas áreas mais rasas do reservatório. Dessa forma, foi apresentado que os resultados do modelo CE-QUAL-W2 forneceram uma compreensão abrangente da dinâmica espacial e temporal dos parâmetros analisados durante os períodos modelados. A aplicação deste modelo com a integração do uso de fluorômetros e sensoriamento remoto para a avaliação da qualidade da água, devem ser mais indicados aos gestores de recursos hídricos, para auxiliá-los a entender melhor a dinâmica dos processos físico- químicos e biológicos e principalmente para serem utilizados como um sistema de alertas em casos de florações de cianobactérias, para que possam propor as melhores estratégias de mitigação.

Water quality models in the Colorado River Basin have been developed for the basin, river, and individual reservoirs. They are used to support water quality programs within the basin. The models are periodically reviewed and updated to improve the accuracy of simulations. Improving the usefulness of the Lake Powell model, one of the key reservoirs in the basin, is the subject of this study. Lake Powell is simulated using a hydrodynamic and water quality model, CE-QUAL-W2. Previously the model has been used at Lake Powell to simulate hydrodynamics, temperature, and total dissolved solids with a reasonable degree of accuracy. An additional parameter, dissolved oxygen, will be added to the simulations and then calibrated with observed data to verify accuracy. Dissolved oxygen distributions in Lake Powell vary seasonally and change under different hydrologic cycles. They are a function of physical, biological, and chemical processes. Few measurements of these processes in Lake Powell exist. To compensate for the lack of data an empirical method of loading oxygen demand to the model is developed and tested. Observed limnological processes in the reservoir guide the development of the empirical methods. The methods are then tested in 16 year model simulations and compared with dissolved oxygen measurements from the 16 year period. By accurately reproducing the dissolved oxygen distributions the Lake Powell model will have improved accuracy and also broaden its usefulness.

The Capability Approach was initially developed by Nobel laureate Amartya Sen, with the first basic articulation presented in his 1979 ‘Equality of What?’ Tanner Lecture. Since then, the approach has gained a huge amount of attention as a conceptual framework which offers a clear and insightful way to measure well-being and development. Most recently, the approach has been refined and extended by Martha Nussbaum to issues of disability, nationality, and species membership in political philosophy. This project is about the foundations of the capability approach. More specifically, this project asks whether we can, and whether there are good reasons to, strengthen those foundations. The conclusions drawn here are that we ought to think seriously about the way that the capability approach develops as a theory that responds to real world challenges and change. More importantly, this project contends – in light of the challenges of future people and indigenous peoples – that there is good reason to think of new ways to ground the approach. This project takes up this challenge and grounds the approach in a modified version of Tim Mulgan’s approach to well-being. This project demonstrates that this alternative enriches the capability approach by providing us with a way of making sense of important problems, and with options for moving forward. Overall, this project asks important questions about how the capability approach could evolve based on challenges that remain relatively under-explored in the current literature. This project contributes to this literature by demonstrating that we can and ought to strengthen the capability approach and its ability to understand, take on board, and resolve these challenges.

Marine and coastal ecosystems are subject to diverse and increasingly intensive anthropogenic activities, making understanding cumulative effects critically important. However, accurately accounting for the cumulative effects of human impacts can be difficult, with the possibility of multiple stressors interacting and having greater impacts than expected, compounding direct and indirect effects on individuals, populations, communities and ecosystems. Assessment of multiple stressors therefore requires extensive scientific research that directly tests how single or multiple ecological components are affected by stressors, both singly and when combined, and as a consequence, cumulative effects assessments are now increasingly included in environmental assessments. Currently, there is a need to assess these at larger spatial scales, with additional research also urgently needed on the responses of ecological components, processes and functions to single and cumulative stressors. As cumulative environmental impacts could be better addressed by regional stressor effects assessments that combine methods for predicting multiple pressures on ecosystem recovery alongside degradation, this study used several separate approaches that can be used in parallel to give support for local management measures. I tested four completely different methods - a range of multi-metric indices, a food web model (Ecopath), a predictive model (Ecosim) and a Bayesian Belief Network model. Each approach was tested and compared in two shallow water estuarine systems, in Scotland and England, initially concerning the impact of nutrient enrichment and subsequent recovery and was followed by an investigation of how the addition of multiple stressors (nutrient levels, temperature and river-flow rates) would impact the future state of each system. The response to stressors was highly context dependent, varying between and within geographic locations. Overall, each of the four different approaches complemented each other and gave strong support for the need to make big reductions in the pressures and to consider trade-offs between impacting pressures. The models and tools also indicate that in order to reach an improved overall environmental state of each ecosystem, a focus on nutrient reductions are likely to be the most effective of the controls on stressors explored and that cumulative effects of the management of nutrient inputs and increased water temperatures and river-flow are likely to exist.

Presidents of the United States and other American policymakers have throughout history cited democracy promotion as one of the chief goals of American foreign policy, and the current administration of George W. Bush has been no exception. However, and notwithstanding the habitual endorsement of this objective by US administrations, the subject of democracy promotion has received relatively little academic attention. This study aims to correct this gap in the literature by considering two questions relating to United States democracy promotion. First, have the efforts of the US to spread democracy to other countries met with success? Second, is promoting democracy truly a priority of American policymakers, or is it rather window dressing cynically aimed at winning public and congressional support for foreign policy? I begin by defining the terms democracy and democracy promotion. I then use three recent case studies to answer the two questions outlined above, the first of which focuses on President Reagan’s policy towards Nicaragua. In the second case study I consider President Clinton’s policy towards Haiti, while the third deals with President George W. Bush’s policy towards Colombia. The evidence I present points to the conclusion that the United States has not been successful in its efforts to promote democracy in other countries, and that spreading democracy abroad is at best a secondary goal of American foreign policy. The evidence presented in the thesis also demonstrates the utility of foreign policy analysis-based approaches to the study of international relations.