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Thesis (MSc)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

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Neste trabalho estudamos, experimental e teoricamente, as flutuações de campos eletromagnéticos após a interação com sistemas atómicos em configuração de dois níveis com degenerescências. Estes sistemas atómicos eram preparados em superposições coerentes de seus estados obtidas através dos fenômenos de Transparência e Absorção Eletromagneticamente Induzidas. O sistema físico foi considerado em dois modelos teóricos semiclássicos distintos: resposta atómica linear e difusão de fase. Estes modelos se baseiam no fato de que lasers de díodo possuem excesso de ruído na fase, que durante o processo de interação coerente com o sistema atómico é transferido ressonantemente para o ruído de intensidade. Em nossa análise, observamos resultados não triviais em relação aos sinais de ruído e correlação entre os campos medidos. Verificamos que, num vapor atómico, a largura Doppler associada à transição tem um papel fundamental na composição elo sinal ele ruído. Observamos que mesmo transições que, a priori, estariam não ressonante podem ter contribuição significativa para o sinal ele ruído. Os modelos teóricos desenvolvidos apresentaram um bom acordo qualitativo com parte dos dados experimentais e se mostraram uma ferramenta útil para a análise da influência dos efeitos coerentes nas flutuações elos campos, quando o laser possui excesso de ruído ele fase. / We present a theoretical and experimental investigation of the fluctuations of electromagnetic fields after the interaction with degenerate two-level atomic systems. These atomic systems were prepared in coherent superpositions of the states obtained through Electromagnetically Induced Transparency (EIT) and Absorption (EIA). The physical system was studied in two semi-classical models: linear atomic response and phase diffusion. These models are based on the fact that diode lasers have excess phase noise, which in the interaction process is transferred to intensity noise. We observed non trivial results about the noise signals and the correlations between the fields. We showed that, in atomic vapor, the Doppler width has a fundamental role in the origin of the noise signal. The theoretical models show good qualitative agreement with part of the experimental result features and are a powerful tool to analyze field fluctuations, when the laser has excess phase noise.

First-pass success is important for cost-effective Monolithic Microwave and Millimeter-wave Integrated Circuits (MMMICs) since additional iterations to the MMMIC design are costly and take months to complete. In order to meet these goals, new levels of capabilities in the design, test and comprehensive simulations are required. The MMMICs employ microstrip line as a component connecting transmission medium as well as a distributed matching element. In a circuit layout, any deviation from straight transmission lines causes the introduction of discontinuity parasitics which must also be modeled as accurately as possible in order to predict the circuit performance. These discontinuities should either be taken into account or compensated for at the final stage of the design. A comparative study of different circuit simulators is undertaken to characterize microstrip discontinuities. Several microstrip discontinuities, such as bends, steps, and tees are examined and optimum compensated models are determined. / Master of Science

This study compared models that used remote sensing to assess salinity in Whitewater Bay. The quantitative techniques in this research allow for a less costly and quicker assessment of salinity values. Field observations and Landsat 5 TM imagery from 2003-2006 were separated into wet and dry seasons and temporally matched. Interpolation models of Inverse Distance Weighting and Kriging were compared to empirical regression models (Ordinary Least Squares and Geographically Weighted Regression - GWR) via their Root Mean Square Error. The results showed that salinity analysis is more accurate in the dry season compared with the wet season. Univariate and multivariate analysis of the Landsat bands revealed the best band combination for salinity analysis in this local area. GWR is the most conducive model for estimating salinity because field observations are not required for future predictions once the local formula is established with available satellite imagery. / by Donna Selch. / Thesis (M.A.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

Thesis (MSc (Physics))--University of Stellenbosch, 2007. / A relativistic plane wave model is developed for electromagnetic production of unbound hyperons with free kaons from nuclei. The differential cross section is expressed as a contraction of leptonic and hadronic tensors. The leptonic tensor is constructed by using the helicity representation of a free Dirac spinor. A model for the corresponding elementary process is used to calculate the hadronic tensor, in which the hadronic current operator Jˆμ is written as a linear combination of six invariant amplitudes and six Lorentz and gauge invariant quantities. The kinematics for this process is assumed to be a quasi-free process i.e., the electron interacts with only one bound nucleon inside the nucleus. The bound state wavefunction of the bound nucleon is calculated within the framework of the relativistic mean-field approximation. The unpolarized differential cross section for the K+ electroproduction process, e + A −→ e + K+ + A + Aresidual is calculated as a function of the hyperon scattering angle.

Orientador: Carlos Ourivio Escobar / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-05T00:48:53Z (GMT). No. of bitstreams: 1 Gomes_RicardoAvelino_D.pdf: 22856845 bytes, checksum: ff49da476ee952e261dde1c21ce27f56 (MD5) Previous issue date: 2005 / Resumo: Apresentamos uma investigação sobre o decaimento semileptônico ?0??+µ - ?µ. Observamos este decaimento pela primeira vez com nove eventos identificados, utilizando para tal a linha de feixe e os detectores do experimento KTeV no Fermilab. O decaimento é normalizado pelo modo ?0??+e- ?e, resultando em uma razão das taxas de decaimento G(?0??+µ - ?µ)/G(?0??+e- ?e) igual a ( 1,8+0,7-0,5(estat.) ± 0,2(sist.) ) x 10-2 com 68,27% C.L., que se tomou a medida oficial da colaboração KTeV: Em uma análise independente, também utilizamos o decaimento dominante ?0? ?p0(???p-) como modo de normalização, o que corroborou o resultado principal. Realizamos ainda, uma nova medida da razão de ramificação do modo ?0??+e- ?e com base em 1139 eventos e normalizada pelo decaimento ?0??p0(???p-). Os resultados estão em pleno acordo com o modelo a quarks com simetria SU(3) de sabor / Abstract: We report an investigation of the semileptonic decay ?0??+µ - ?µ. This decay was observed for the first time with nine identified events using the KTeV beam line and detector at Fermilab. The decay is normalized to the ?0 beta decay mode and yields a value for the ratio of decayrates G(?0??+µ - ?µ)/G(?0??+e- ?e) igual a ( 1,8+0,7-0,5(stat.) ± 0,2(syst.) ) x 10-2 at the 68,27% confidence level, being the official measurement of KTeV Collaboration. We also used the dominant decay ?0? ?p0(???p-) as normalization mode in an independent analysis which corroborated with the main result. In addition, a new measurement of the ?0??+e- ?e branching ratio is presented, based on 1139 events and normalized to the ?0??p0(???p-) decay mode. The results are in agreement with the SU(3) flavor symmetric quark model / Doutorado / Física das Particulas Elementares e Campos / Doutor em Ciências