Neste trabalho foi utilizada uma metodologia eletroanalítica para o estudo do comportamento dos pesticidas triazínicos, Atrazina e Ametrina em água e sedimentos do rio Mogi-Guaçu. Para isto utilizou-se a técnica de voltametria de onda quadrada (SWV) e o eletrodo de gota suspensa de mercúrio (HMDE). Inicialmente, os parâmetros experimentais (e voltamétricos) foram otimizados a fim de se obter a melhor resposta, em termos de intensidade de corrente de pico e definição do perfil voltamétrico. As melhores condições encontradas foram: eletrólito suporte CaCl2 0,01 mol L-1 em pH 3,0 e 2,3, para Ametrina e Atrazina, respectivamente, f = 100 s-1; a = 50 mV e DEs=2,0 e 10,0, para Ametrina e Atrazina respectivamente. Após a otimização, curvas de trabalho foram construídas para os dois pesticidas. Foram determinados os limites de detecção (LD) e quantificação (LQ), fatores de recuperação, repetibilidade, reprodutibilidade e sensibilidade da metodologia utilizada. Os resultados obtidos utilizando esta metodologia eletroanalítica foram comparados com os obtidos por HPLC-UV. Para Ametrina e Atrazina em eletrólito preparado com água do Milli-Q, os valores de LD encontrados foram de 2,12 ?g L-1 e 1,16 ?g L-1 e os de LQ foram de 7,06 ?g L-1 e 3,90 ?g L-1, respectivamente. Os valores de LD obtidos utilizando HPLC-UV para Ametrina e para a Atrazina foram de 2,69 ?g L-1 e 1,37 ?g L-1, enquanto aqueles para o LQ foram de 9,01 e 10,62 ?g L-1, respectivamente. Observou-se, desta maneira, que os resultados obtidos usando as duas técnicas são muito próximos e inferiores aos valores recomendados pela Comissão Nacional do Meio Ambiente (CONAMA) para águas residuais e efluentes industriais, 50 ?g L-1 para a Atrazina. Além disto, os valores reportados acima são tão baixos quanto os valores máximos aceitos pela Enviromental Protection Agency (EPA - USA) para águas potáveis, 3 ?g L-1 e pela Agência Nacional de Vigilância Sanitária (ANVISA), também para águas potáveis, 2 ?g L-1. A aplicação da mesma metodologia para águas naturais forneceu parâmetros importantes para verificar o comportamento destes pesticidas em águas, principalmente no que se refere à sua persistência. Foram determinados os limites de detecção (LD) e quantificação (LQ), assim como os fatores de recuperação para amostras de água do Rio Mogi-Guaçu, coletadas em três pontos diferentes, utilizando a técnica de SWV. Para Ametrina em eletrólito preparado com água do rio, os valores de LD variaram entre 15,41 e 29,54 ?g L-1 enquanto que os valores de LQ situaram-se entre 51,38 e 98,49 ?g L-1. Já para a Atrazina, os valores de LD variaram entre 4,90 e 6,19 ?g L-1 e os valores de LQ entre 16,36 e 20,65 ?g L-1 respectivamente. Os fatores de recuperação para Ametrina variaram entre 98,12 e 98,50% e para Atrazina entre 98,00 e 98,80%. As fotodegradações dos pesticidas foram estudadas com a exposição à radiação solar de soluções contendo os pesticidas e preparadas com água do Milli-Q, água de rio e água de rio contendo amostras de sedimentos. Os decaimentos da corrente de pico de redução da Ametrina e da Atrazina com o tempo de exposição à luz solar, variaram conforme o ponto de coleta da água do rio Mogi- Guaçu e a natureza do pesticida. Assim, para a Ametrina as porcentagens de decaimento de corrente após 32 horas de exposição foram de 19,10% (água do Milli-Q); 28,24% (ponto 1); 47,62% (ponto 2) e 30,92% (ponto 3). Já para a Atrazina, as respectivas porcentagens de decaimento das correntes de pico de redução foram de 37,50%; 45,90%; 46,10% e 36,53%. Para soluções contendo os sedimentos, a porcentagem de degradação ficou por volta de 30% para Ametrina enquanto que para a Atrazina a diferença foi marcante, ficando em torno de 86%. Os valores dos coeficientes das isotermas de adsorção de Freundlich obtidos indicaram uma dependência da adsorção com o teor de matéria orgânica e argila no sedimento para os três pontos de coleta do sedimento. De acordo com o critério adotado pelo IBAMA, os pesticidas Ametrina e Atrazina apresentam adsorção baixa, ficando pouco adsorvidos no sedimento. Os valores do 1/n da isoterma de Freundlich variaram entre 1,00 e 1,15 indicando uma característica de partição linear para todos os pontos. Os valores de matéria orgânica para os três pontos de coleta, variaram de 5,45 a 15,16%. A matéria orgânica encontra-se revestindo grande parte das frações minerais do solo e sedimento. Estas frações minerais variam de 15,7 a 20,8%, sendo os teores de silte de 12,3 a 16,3%. / An electroanalytical methodology was employed aiming to study the behaviour of the triazinic pesticides Atrazine and Ametrine in water and sediment collected from the Mogi-Guaçu River. The square wave voltammetry (SWV) and the hanging mercury drop electrode (HMDE) were employed. In a first step, the experimental (and voltammetric) parameters were optimized in order to yield the highest current signals as well as the most well defined voltammetric profiles. The best conditions were achieved as: 0.01 mol L-1 CaCl2 as the support electrolyte at pH 3.0 and 2.3 for Ametrine and Atrazine respectively, f = 100 s-1, a = 50 mV and ?Es = 2.0 and 10.0 for Ametrine and Atrazine respectively. After this initial step, analytical curves were obtained for both pesticides. The corresponding detection (LD) and determination (LQ) limits were calculated, as well as the recovering factors, repeatability, reproducibility and sensibility for the analytical methodology, which was compared with those, obtained using the HPLC-UV. For Ametrine and Atrazine, in pure electrolyte the LD values were 2.12 and 1.16 ?g L-1, while the LQ ones were 7.06 and 3.90 ?g L-1, respectively. The same parameters, obtained with HPLC-UV yielded LD values of 2.69 and 1.37 ?g L-1 for Ametrine and Atrazine, respectively, while the LQ ones were 9.01 and 10.62 ?g L-1, respectively. In this way, it is apparent that the results obtained in this work were very close for both techniques and lower than the minimum limit allowed by the Conselho Nacional do Meio Ambiente (CONAMA) for waste water or industrial effluents, 50 ?g L-1. Moreover, they are close to the maximum allowed value for drinking water postulated by the Environmental Protection Agency (EPA – USA), 3 ?g L-1 and the Agência Nacional de Vigilância Sanitária (ANVISA), 2 ?g L-1. The application of the same methodology for natural water samples yielded important parameters to establish the behaviour of pesticides, mainly concerning with its persistency. It were determined the detection and quantification limits and recovering factors by the SWV technique, for river water samples collected in three different points. For Ametrine, the LD values for electrolytes prepared with river waters, varied between 15.41 and 29.54 ?g L-1, while the values for LQ were between 51.38 and 98.49 ?g L-1. The same values for Atrazine were determined between 4.90 and 6.19 for LD and 16.36 and 20.65 for LQ. The recovering factors for Ametrine were found to be between 91.12 and 98.50% and for Atrazine between 98 and 98.8%. The photodegradations of pesticide molecules were studied by exposition to daylight of solutions containing the pesticides prepared with Milli-Q water, river water and river water containing sediments. The peak current decaying for Ametrine and Atrazine with exposition time varied accordingly the water collection point in the Mogi-Guaçu River and the nature of the pesticide. In this way, for Ametrine the percentage of decaying after 32 hours of exposition were 19.10% for Milli-Q water, 28.24% point 1, 47.62% point 2 and 30.92% point 3. For Atrazine, the respective decaying percentages of peak currents were 37.5%, 45.90%, 46.10% and 36.53% respectively. For solutions containing sediments (also collected in points 1, 2 and 3) the degradation percentage was around 30% for Ametrine, while for Atrazine the difference, around 86%. The coefficients from Freundlich adsorption isotherms presented values depending on the organic matter and clay present in the sediment samples. The pesticides presented low adsorption characteristic on the sediments. The 1/n values from Freundlich isotherm varied between 1.00 and 1.15, indicating a linear partition coefficient characteristic in all points. In this way, it is possible to associate the Kf values with the partition coefficients (Kd). The organic matter content for the three collection points varied between 5.45 and 15.15. The organic matter is found to be covering the mineral fractions of soils and sediments. These mineral fractions varied from 15.7 to 20.8%, while silt content were among 12.3 and 16.3%.

This paper investigates the effect of parameter selection for the decision feedback equalization (DFE) on communication performance through a dispersive underwater acoustic wireless channel (UAWC). A DFE based on minimum mean-square error (MMSE-DFE) criterion has been employed in the implementation for evaluation purposes. The output from the MMSE-DFE is input to the decoder to estimate the transmitted bit sequence. The main goal of this experimental simulation is to determine the best selection, such that the reduction in the computational overload is achieved without altering the performance of the system, where the computational complexity can be reduced by selecting an equalizer with a proper length. The system performance is tested for BPSK, QPSK, 8PSK and 16QAM modulation and a simulation for the system is carried out for Proakis channel A and real underwater wireless acoustic channel estimated during SPACE08 measurements to verify the selection.

Ingeniero Civil Industrial / La presente memoria se centra en desarrollar una metodología de evaluación de proyectos, para uso en generación eléctrica, que captura las dinámicas del valor de un proyecto de inversión. Esto en base a la evolución de la principal variable de mercado que afecta la rentabilidad usando las técnicas de valoración, llamados Least Square Monte Carlo y Árboles Trinomiales. Esto porque, los proyectos en este rubro son priorizados respecto a la tecnología de desarrollo más eficiente disponible usando un análisis de Valor Actual Neto (VAN) que no considera las dinámicas a las cuales están sujetos los valores de los proyectos. Como se prevé que las instalaciones de generación eléctrica se mantendrán en operación por un 50% más de su vida útil pronosticada, se vuelve más significativa la evaluación dinámica para el largo plazo incorporando incertidumbre. Para ello, se hace un análisis empírico del comportamiento de los precios de electricidad, en un nodo representativo del Sistema Interconectado Central, el principal mercado eléctrico en Chile. Con esto, se estiman los parámetros de un modelo que incorpora estas características, conocido como Mean Reverting Jump Diffusion en conjunto con un modelo de simulación de operación para la determinación de expectativas de largo plazo en precios de electricidad. Para la aplicación del análisis de opciones reales, se utilizan los procedimientos Least Square Monte Carlo y árboles trinomiales basados en los parámetros encontrados del proceso de precios para diseñar la estrategia óptima de inversión en el largo plazo en generación de tecnologías disponibles en Chile. Los resultados incluyen un análisis de las estrategias de inversión de diversas centrales disponibles para la expansión de la matriz energética de Chile dadas las condiciones actuales del mercado. En particular, el análisis de árboles sugiere invertir inmediatamente en centrales Hidroeléctricas, térmicas de Carbón y Diésel y no invertir en tecnología de ciclos combinados. Por otra parte, el algoritmo de Least Square Monte Carlo sugiere esperar en todos los casos, ya que estima que el valor de estos proyectos incrementará en el futuro respecto a sus valores estimados actuales. Por ello, el análisis comparativo entre los modelos sugiere de un sesgo relativo hacia arriba por parte del algoritmo de Least Square Monte Carlo. Este sesgo es analizado en mayor profundidad, arribando a la conclusión que a medida que se aumentan las simulaciones consideradas, este sesgo relativo va disminuyendo, pero de manera desacelerada. Para complementar, se incluye un análisis de sensibilidad de los resultados usando parámetros de cobertura de riesgo, conocidos coloquialmente como las griegas , calculados a partir de los Árboles trinomiales. Los resultados de estos análisis indican que el valor del precio de la electricidad, la volatilidad y la duración de la oportunidad de inversión impactan positivamente en el proyecto, lo que es consistente con la teoría de opciones reales que postula que a mayor volatilidad, más valor se puede generar en un proyecto al aprovechar las flexibilidades inherentes.

This work shows how legacy and novel radio Interferometry software packages and algorithms can be combined to produce high-quality reductions from modern telescopes, as well as end-to-end simulations for upcoming instruments such as the Square Kilometre Array (SKA) and its pathfinders. We first use a MeqTrees based simulations framework to quantify how artefacts due to direction-dependent effects accumulate with time, and the consequences of this accumulation when observing the same field multiple times in order to reach the survey depth. Our simulations suggest that a survey like LADUMA (Looking at the Distant Universe with MeerKAT Array), which aims to achieve its survey depth of 16 µJy/beam in a 72 kHz at 1.42 GHz by observing the same field for 1000 hours, will be able to reach its target depth in the presence of these artefacts. We also present stimela, a system agnostic scripting framework for simulating, processing and imaging radio interferometric data. This framework is then used to write an end-to-end simulation pipeline in order to quantify the resolution and sensitivity of the SKA1-MID telescope (the first phase of the SKA mid-frequency telescope) as a function of frequency, as well as the scale-dependent sensitivity of the telescope. Finally, a stimela-based reduction pipeline is used to process data of the field around the source 3C147, taken by the Karl G. Jansky Very Large Array (VLA). The reconstructed image from this reduction has a typical 1a noise level of 2.87 µJy/beam, and consequently a dynamic range of 8x106:1, given the 22.58 Jy/beam flux Density of the source 3C147.

The South African agricultural sector underwent a significant amount of institutional and structural changes during the past two decades, especially in the aftermath South Africa’s first democratic elections in 1994 and the deregulation of the agricultural marketing environment in 1996/97. These changes meant that South African agricultural economics scholars had to adapt to these changes. The increased need towards more quantified output in agricultural economic research has led agricultural economic scholars to “borrow” econometric models from their fellow scholars abroad to apply to South African research problems in order to fulfil the need for more quantified research output. However, the development of econometrics has over the years given rise to a disenchantment with the way in which econometrics have been applied in economic research. Consequently it is believed that a large body of literature has entered the public domain without being properly reviewed because South African agricultural economic scholars do not have the necessary insight and knowledge of the problems believed to be at the root of the disenchantment with the manner in which econometrics have been applied. The general objective of this dissertation is to investigate the disenchantment with the manner econometrics has been applied in economic and agricultural economic scholarship in order to identity the main drivers of this disenchantment, and to use this knowledge gained to evaluate the application of econometrics in South African agricultural economic scholarship as portrayed in Agrekon, one of South Africa’s agricultural economics peer review journals. The study is conducted by means of a review of the literature on the history of econometrics, the development of econometric methodologies and the disenchantment with econometrics in economics and agricultural economics. Applied econometrics portrayed in Agrekon is evaluated by means of a survey of papers published in this journal. The main findings of this study revealed that the key drivers of disenchantment can mainly be ascribed to the following: <ul> <li>The misuse of statistical significance tests in applied studies.</li> <li>Problems with data underlying econometric analyses.</li> <li>The problems associated with replication. <li>Data mining <li>The “Black box ideology” in applied econometrics and <li>Scholasticism and associated preference falsification.</li> </ul> A survey of papers published in Agrekon based on a sample of 65 papers, which were sampled by means of stratified random sampling, revealed that elements behind the disenchantment with econometrics are present in South African agricultural economic scholarship. It was also found that the data underlying econometric analyses are a major point of concern in South African agricultural economics and it seem as if South African agricultural economics scholars have adopted a lackadaisical attitude towards data. The study concludes with recommendations for future studies into to the application of econometrics in South African agricultural economics. / Dissertation (MCom(Agricultural Economics))--University of Pretoria, 2008. / Agricultural Economics, Extension and Rural Development / MCom / unrestricted

This report is the result of an empirical investigation of everyday life in Victory Square, Vancouver, British Columbia. Three months of intensive, scheduled observation and participant observation were planned in order to investigate the hypothesis that there was a regular and meaningful organization, both spatially and socially, to the use and control of park space. The exploration was guided theoretically and methodologically by the research of human spatial behaviour at other spatial scales, from the indoor built environment to the scale of urban communities. Both systematically retrieved demographic statistics and spatial habits of park users, and more subjective anecdotal accounts of people's perceptions and specific behavioural episodes were gathered. This provided a well rounded statistical and phenomenological data bank from which to generalize. An instrument for objective assessment and classification of park users as to life style affiliation, a systematic schedule of information retrieval, and a 'behavioural map' on which to record unobtrusively derived data were central to a research strategy that did not impinge upon the natural, real life setting. The park was found to host a number of socially marginal life style groups who, as powerless outcasts of wider affluent society, coexisted, as a separate social world, in social and spatial harmony. Through the behavioural processes of tolerance, non-involvement, and passive readjustment, a parochial moral order existed which was demonstrated in rituals of interaction and collective patterns of spatial dominance. This socio-spatial order accorded incompatible life style groups a means of peaceful coexistence in a place of limited space and resources. Spatial behaviour in micro-scale outdoor public space has not previously been intensively investigated. This exploration, as a case study of one such environment, supports the hypothesis that, at all levels of social encounter, and at all spatial scales, available space is organized, used and controlled in a regular, ordered, and meaningful way to accommodate and integrate the social gatherings it hosts. / Arts, Faculty of / Geography, Department of / Graduate

Le travail décrit d’abord le processus par lequel Aristote a mis les bases d’une logique qui est devenu la norme pour un raisonnement correct, ainsi que les raccourcis qu’il a pris pour faire de la logique une pratique inutile pour l’étude des arguments tels qu’ils apparaissent dans les arguments informels. Par la suite l’étude établit de nouveaux concepts sur lesquels le raisonnement et l’argumentation réelle sont fondées et introduit ce qui est étiqueté comme « carrés rationnel », une structure sur laquelle toute forme de discours peut être analysée. Afin de prouver la validité de la nouvelle théorie, il est appliqué à diverses formes de discours ou de dispositifs littéraires, puis au livre de l’Ecclésiaste, l’un des livres les plus déroutants de la Bible sur lequel aucune explication satisfaisante ou interprétation n’a pas été offerte auparavant. Et enfin, la nouvelle théorie est appliquée pour analyser des ouvrages savants concernant leur cohérence dans ce qu’ils disent ainsi que leur rapport au texte qu’ils prétendent interpréter correctement. / The work outlines first the process by which Aristotle laid the foundations for logic which has become the standard for correct reasoning, as well as the shortcuts which he took and has made logic virtually useless for the study of arguments as they occur in informal arguments. Then the work establishes new concepts on which actual reasoning and argumentation are based and introduces what is labeled as reasoning square, a structure on which any form of discourse can be analyzed. In order to prove the validity of the new theory, it is applied to various forms of discourse or literary devices, then to the book of Ecclesiastes, one of the most confusing books in the Bible for which no satisfactory explanation and interpretation has been offered before. And finally, the new theory is applied to analyzing scholarly works from the point of view of how consistent they are in what they say as well as their relation to the text whose meaning they claim to accurately expose.

An optical study of Mn and Mo isotopes has been performed in two contrasting regions of the nuclear chart. Collinear laser spectroscopic methods were employed using the Ion Guide Separator On-Line (IGISOL) at the University of Jyväskylä, Finland. Optical pumping in an ion-trap with the use of frequency quadrupled titanium sapphire lasers, greatly improved the efficiency of the spectroscopy performed.For the first time, the change in mean-square charge radius was determined for ground and isomeric states in 50-56Mn with a sharp shell closure seen across N = 28. Nuclear quadrupole moments in 50m,53,54,56Mn were also extracted, displaying trends similar to those of the charge radii. Newly extracted hyperfine structures and isotope shifts of 90-92,94-98,100,102-106,108Mo span the N = 50 shell closure and well-known N = 60 shape change. Unlike the Z = 38 - 41 isotopic chains, Mo exhibits a smooth increase in mean-square charge radius, with no sudden onset of deformation at N = 60. These measurements signify the end point of this strongly deformed A ~ 100 region in both Z and N. In the Z ~ 40 region, the charge radii follow the trends in the mass measurements near perfectly. However, in the Mn measurements a clear disparity between the mass and charge radii measurements is seen across the N = 28 magic shell closure. The absence of any shell effects in the Mn mass measurements show the importance of charge radii measurements, with pertinent implications for future investigations in the N = 40 region. Additionally, a portable data acquisition system for laser spectroscopy has been successfully tested. It is based on the LabJack system which will directly interface to a USB connection. It is able to register individual photons from amplified and converted photomultiplier tube signals (with bunched or continuous ion beams). The device drives a Cooknell voltage supply, which steps the voltage across the laser-ion interaction region. The introduction of an accurate 100 ms time window into the LabJack system has enabled a precise photon detection system for future off-line testing and on-line use. Further to this, a new method of locating hyperfine resonances has been introduced into our spectroscopy.

This research was conducted to identify whether South African 3 star and above hotels are interested in forming alliances. The objective of this study was to group South African independent 3 star and above hotels on the alliance framework continuum, namely; cooperation, collaboration, coordination and coadunation; and to identify whether South African independent 3 star and above hotels are interested to progress from one simple form of alliance to the next complex, formal type of alliance. Hypotheses were proposed to determine the significance of the differences in preference of South African 3 star and above independent hotels. Thus, this study is descriptive in nature, to test the proposed hypotheses. An extensive investigation into the relevant literature was done. An empirical study was also conducted and the measuring instrument consisted of a selfadministered questionnaire. The population selected consisted of managers of these South African 3 star and above independent hotels. The major findings included: South African independent 3 star and above hotels seem to prefer niche personality and potential non-financial relationship, while they try to avoid economic and cultural integration with a partner firm and not interested in shared management control with the partner firm. Besides, four factors confirmed the alliance continuum developed by Bailey and Koney (2000), namely; cooperation, coordination, collaboration and coadunation. Friedman’s test indicated that there is significant difference among the different dimensions of alliance formation, namely; cooperation, collaboration, coordination and coadunation and that South African independent 3 star and above hotels are interested to form cooperation form of alliances mostly, followed by coordination form of alliances. South African independent 3 star and above hotels are neutral on whether to form collaboration type of alliances and they are not interested to involve in the coadunation form of alliances. Chi-square test indicated that there is no significant difference on the opinion of the respondents on whether the hotel they work for needs to progress from simpler form of alliances into more formal and complex format of alliances. However, those who preferred that their hotel has to progress from simpler form of alliance are higher in number than those who did not prefer. It was, inter alia, recommended that as South African 3 star and above hotels choose lower form of alliance, value chains seem the most applicable form of alliance. Hotels could share a name, reservation information and some basic IT facilities (point of sale IT reservation equipment and back office IT equipments). Finally, the study concludes by recommending that South African independent 3 star and above hotels should take alliances as an option for growth and justification of expenditures and decide the level of alliance continuum they want to engage in. / Dissertation (MBA)--University of Pretoria, 2012. / Gordon Institute of Business Science (GIBS) / unrestricted

This dissertation focuses on the re-conceptualization of Pretoria Central Business District (CBD), grounding the hypothesis within Paul Kruger Street. The author aims to provide a newfound approach to this historical connection, transforming the interpretative experience of the urban environment as a stage from where the city operates as a place of fantasy, covet, and imagination. The project will demonstrate how the inception of a Virtual Landscape can renew perceptions of the city and pave the way towards a new paradigm. Grounding the Virtual Landscape within a real world scenario, the final phase of the dissertation aims to position this ideology of the imagined landscape within a real world context. The Virtual Landscape aims to inform the grounded design proposal, adding to the experience of place and time. The user’s understanding of place cannot be separated from time. The motivation behind the dissertation exists as a critique on the city of Pretoria, where the in situ experience of place is thin, and the experience is swiftly forgotten. The findings from the investigation of the Virtual Landscape constructed the hypothesis as a contributor to the thickening of the place that extends beyond the veneer. The research question originates from the theory of the Virtual Landscape, questioning whether this theory can be applied within contemporary landscape architecture design. The hypothesis is introduced on five sites in Pretoria on a framework level as representations of the Virtual Landscape. One site is selected and tested against the process of the Virtual Landscape from its influences, the Virtual Landscape, representations of the Virtual Landscape and the material landscape (design proposal). The final stage of the dissertation investigates the technical resolution of the design proposal. / Dissertaion ML(Prof)--University of Pretoria, 2012. / Architecture / ML(Prof) / Unrestricted