Dans le domaine du radar aéroporté, les enjeux industriels actuels sont nombreux et portent,entre autres, sur l'établissement de profils distance de cibles aériennes, terrestres et maritimes pour leur identification. Cela implique en particulier la mise en oeuvre de chaînes d'émission/réception pour des modes de fonctionnement haute résolution. Dans ce contexte, les problématiques à traiter comprennent alors la conception et l'analyse de performances de détecteurs pour des modèles de cibles étendues, la conception de formes d'ondes multi-résolutions et le développement des traitements associés, l'optimisation de formes d'onde robustes au fouillis, etc. Le travail de cette thèse, qui s'intègre dans ce cadre, se décompose en deux parties. Dans un premier temps, nous traitons la détection d'une cible dite "étendue", c'est-à-dire caractérisée par plusieurs réflecteurs élémentaires prépondérants répartis sur plusieurs cases distance non nécessairement consécutives. Ce modèle est notamment approprié lorsque la résolution en distance est suffisamment fine, et s'intègre dans les problématiques d'identification de cible. Dans ce cadre, nous étudions un test de détection fondé sur le rapport de vraisemblances généralisé (GLRT) intégrant la localisation inconnue des réflecteurs, et lorsque la perturbation est du bruit blanc gaussien. En utilisant des résultats issus des statistiques d'ordre, nous déduisons des approximations de la probabilité de fausse alarme et de la probabilité de détection. Des comparaisons numériques avec des détecteurs existants sont fournies. Dans un second temps, nous étudions une forme d'onde correspondant à un train d'impulsions contenant deux codes de phase, l'un intra impulsion et l'autre inter impulsion. Pour un modèle de cible ponctuelle et un fouillis gaussien, nous proposons de sélectionner ces codes en tenant compte de différents critères tels que la maximisation de la probabilité de détection ou encore la minimisation des lobes secondaires du signal reçu après traitement. Pour un type donné de fouillis modélisé par un processus autorégressif (AR), nous abordons le problème d'optimisation multi-objectifs en utilisant les fronts de Pareto. La modélisation AR permettant de considérer plusieurs types de fouillis à partir d'un nombre réduit de paramètres, nous étudions alors la robustesse des codes de phase optimaux à des variations de fouillis. / In the field of airborne radar, one of the current industrial stakes, among others, is the identification of a target, whether airborne, terrestrial or maritime, through the establishment of its range profile. This implies to set up a transmit/receive processing for high resolution modes. In this context, the issues to be addressed include the design and the performance analysis of detectors for extended target models, the design of multi-resolution waveforms and the associated processing, the optimization of waveforms that are robust to clutter, etc. Within this frame, the work of this thesis is twofold. The first part deals with the detection of a so-called "extended" target, i.e. which is characterized by a few main scatterers spread over several range gates not necessarily consecutive. This model is appropriate when the range resolution is thin enough and it is suited for target identification issues. In this context, we study a detection test based on the generalized likelihood test (GLRT) which includes the unknown locations of the scatterers, and when the disturbance is white Gaussian noise. By using ordered statistics, we deduce approximations of the probability of false alarm and the probability of detection. Numerical comparison with existing detectors are also provided. Secondly, we study a waveform based on a pulse train which contains two phase codes: the first one is intrapulse whereas the second one is interpulse. Assuming a point target and Gaussian clutter, we propose to select these codes taking into account several criteria such as the maximization of the probability of detection or the minimization of the sidelobes of the received signal after processing. For a given type of clutter modeled by an autoregressive (AR) process, we address this multi-objective optimization problem using the Pareto fronts. Since the AR modeling makes it possible to consider several types of clutter from a reduced number of parameters, we study the robustness of optimal phase codes to clutter variations.

Câmaras não métricas acopladas a Veículos Aéreos Não Tripulados (VANT) possibilitam coleta de imagens com alta resolução espacial e temporal. Além disso, o custo de operação e manutenção desses equipamentos são reduzidos. A classificação da cobertura da terra por meio dessas imagens são dificultadas devido à alta variabilidade espectral dos alvos e ao grande volume de dados gerados. Esses contratempos são contornados utilizando Análise de Imagens Baseada em Objetos (Object-Based Image Analysis – OBIA) e algoritmos de mineração de dados. Um algoritmo empregado na OBIA são as Árvores de Decisão (AD). Essa técnica possibilita tanto a seleção de atributos mais informativos quanto a classificação das regiões. Novas técnicas de AD foram desenvolvidas e, nessas inovações, foram inseridas funções para selecionar atributos e para melhorar a classificação. Um exemplo é o algoritmo C5.0, que possui uma função de redução de dados e uma de reforço. Nesse contexto, este trabalho tem como objetivo (i) avaliar o método de segmentação por crescimento de regiões em imagens com altíssima resolução espacial, (ii) determinar os atributos preditivos mais importantes na discriminação das classes e (iii) avaliar as classificações das regiões em relação aos parâmetros de seleção dos atributos (winnow) e de reforço (trial), que estão contidos no algoritmo C5.0. A segmentação da imagem foi efetuada no programa Spring, já as regiões geradas na segmentação foram classificadas pelo modelo de AD C5.0, que está disponível no programa R. Como resultado foi identificado que a segmentação crescimento de regiões possibilitou uma alta correspondência com regiões geradas pelo especialista, resultando em valores de Reference Bounded Segments Booster (RBSB) próximos a 0. Os atributos mais importantes na construção dos modelos por AD foram a razão entre a banda do verde com a azul (r_v_a) e o Modelo Digital de Elevação (MDE). Para o parâmetro de reforço (trial), não foi identificada melhora na acurácia da classificação ao aumentar seu valor. Já o parâmetro winnow possibilitou uma redução no número de atributos preditivos, sem perdas estatisticamente significativas na acurácia da classificação. A função de reforço (trial) não melhorou a classificação da cobertura da terra. Também não foram constatadas diferenças estatisticamente significativas quando winnow selecionado como verdadeiro, mas se encontrou o benefício desse último parâmetro reduzindo a dimensionalidade dos dados. Nesse sentido, este trabalho contribuiu para a classificação da cobertura da terra em imagens coletadas por VANT, uma vez que se desenvolveu algoritmos para automatizar os processos da OBIA e para avaliar a classificação das regiões em relação às funções de reforço (winnow) e de seleção do atributo (winnow) do classificador por árvore de decisão C5.0. / Non-metric cameras attached to Unmanned Aerial Vehicles (UAV) enable collection of images with high spatial and temporal resolution. In addition, the cost of operation and maintenance of equipment are reduced. The land cover classification through these images are hampered due to high spectral variability of the targets and the large volume of data generated. These setbacks are contoured using Image Analysis Based on Objects (OBIA) and data mining algorithms. An algorithm used in OBIA are Decision Trees (AD). This technique allows the selection of the most informative attributes as the classification of regions. New AD techniques have been developed and these innovations, were functions inserted to select attributes and to improve classification. One example is a C5.0 algorithm, which has a data reduction function and of boosting. In this context, this paper aims to (i) evaluate the segmentation method for growing regions in images with high spatial resolution, (ii) determine the most important predictive attributes in the discrimination of classes and (iii) evaluate the classifications of regions regarding the attributes selection parameters (winnow) and boosting (trial), which are contained in the C5.0 algorithm. The image segmentation was performed in Spring program, since the regions generated in segmentation were classified by model C5.0 , which is available in the program R. As a result it was identified that the segmentation by region growing provided a high correlation with regions generated by the expert, resulting in Reference Bounded Segments Booster values (RBSB) near 0. The most important features in the construction of models of decision tree are the ratio between the band of green with the blue (r_v_a) and the Digital Elevation Model (DEM). Was not identified improvement in classification accuracy when was increased value of trial parameter. Already winnow parameter enabled a reduction in the number of predictive attributes, with no statistically significant losses in the accuracy of the classification. The boosting function (trial) did not improve the classification of land cover. Also were not found statistically significant differences when winnow selected as true, but was found the benefit of the latter parameter to reducing the dimensionality of the data. Thus, this work contributed to the land cover classification in images collected by UAV, once that were developed algorithms to automate the processes of integration OBIA and decision tree (C5.0).

No description available.

Câmaras não métricas acopladas a Veículos Aéreos Não Tripulados (VANT) possibilitam coleta de imagens com alta resolução espacial e temporal. Além disso, o custo de operação e manutenção desses equipamentos são reduzidos. A classificação da cobertura da terra por meio dessas imagens são dificultadas devido à alta variabilidade espectral dos alvos e ao grande volume de dados gerados. Esses contratempos são contornados utilizando Análise de Imagens Baseada em Objetos (Object-Based Image Analysis – OBIA) e algoritmos de mineração de dados. Um algoritmo empregado na OBIA são as Árvores de Decisão (AD). Essa técnica possibilita tanto a seleção de atributos mais informativos quanto a classificação das regiões. Novas técnicas de AD foram desenvolvidas e, nessas inovações, foram inseridas funções para selecionar atributos e para melhorar a classificação. Um exemplo é o algoritmo C5.0, que possui uma função de redução de dados e uma de reforço. Nesse contexto, este trabalho tem como objetivo (i) avaliar o método de segmentação por crescimento de regiões em imagens com altíssima resolução espacial, (ii) determinar os atributos preditivos mais importantes na discriminação das classes e (iii) avaliar as classificações das regiões em relação aos parâmetros de seleção dos atributos (winnow) e de reforço (trial), que estão contidos no algoritmo C5.0. A segmentação da imagem foi efetuada no programa Spring, já as regiões geradas na segmentação foram classificadas pelo modelo de AD C5.0, que está disponível no programa R. Como resultado foi identificado que a segmentação crescimento de regiões possibilitou uma alta correspondência com regiões geradas pelo especialista, resultando em valores de Reference Bounded Segments Booster (RBSB) próximos a 0. Os atributos mais importantes na construção dos modelos por AD foram a razão entre a banda do verde com a azul (r_v_a) e o Modelo Digital de Elevação (MDE). Para o parâmetro de reforço (trial), não foi identificada melhora na acurácia da classificação ao aumentar seu valor. Já o parâmetro winnow possibilitou uma redução no número de atributos preditivos, sem perdas estatisticamente significativas na acurácia da classificação. A função de reforço (trial) não melhorou a classificação da cobertura da terra. Também não foram constatadas diferenças estatisticamente significativas quando winnow selecionado como verdadeiro, mas se encontrou o benefício desse último parâmetro reduzindo a dimensionalidade dos dados. Nesse sentido, este trabalho contribuiu para a classificação da cobertura da terra em imagens coletadas por VANT, uma vez que se desenvolveu algoritmos para automatizar os processos da OBIA e para avaliar a classificação das regiões em relação às funções de reforço (winnow) e de seleção do atributo (winnow) do classificador por árvore de decisão C5.0. / Non-metric cameras attached to Unmanned Aerial Vehicles (UAV) enable collection of images with high spatial and temporal resolution. In addition, the cost of operation and maintenance of equipment are reduced. The land cover classification through these images are hampered due to high spectral variability of the targets and the large volume of data generated. These setbacks are contoured using Image Analysis Based on Objects (OBIA) and data mining algorithms. An algorithm used in OBIA are Decision Trees (AD). This technique allows the selection of the most informative attributes as the classification of regions. New AD techniques have been developed and these innovations, were functions inserted to select attributes and to improve classification. One example is a C5.0 algorithm, which has a data reduction function and of boosting. In this context, this paper aims to (i) evaluate the segmentation method for growing regions in images with high spatial resolution, (ii) determine the most important predictive attributes in the discrimination of classes and (iii) evaluate the classifications of regions regarding the attributes selection parameters (winnow) and boosting (trial), which are contained in the C5.0 algorithm. The image segmentation was performed in Spring program, since the regions generated in segmentation were classified by model C5.0 , which is available in the program R. As a result it was identified that the segmentation by region growing provided a high correlation with regions generated by the expert, resulting in Reference Bounded Segments Booster values (RBSB) near 0. The most important features in the construction of models of decision tree are the ratio between the band of green with the blue (r_v_a) and the Digital Elevation Model (DEM). Was not identified improvement in classification accuracy when was increased value of trial parameter. Already winnow parameter enabled a reduction in the number of predictive attributes, with no statistically significant losses in the accuracy of the classification. The boosting function (trial) did not improve the classification of land cover. Also were not found statistically significant differences when winnow selected as true, but was found the benefit of the latter parameter to reducing the dimensionality of the data. Thus, this work contributed to the land cover classification in images collected by UAV, once that were developed algorithms to automate the processes of integration OBIA and decision tree (C5.0).

Submitted by Lúcia Brandão (lucia.elaine@live.com) on 2015-07-15T17:16:21Z No. of bitstreams: 1 Tese - Felicidad Santos Gimenez.pdf: 1802898 bytes, checksum: 245aa4c3338753c4ecf130b72b8adf62 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-07-20T17:47:12Z (GMT) No. of bitstreams: 1 Tese - Felicidad Santos Gimenez.pdf: 1802898 bytes, checksum: 245aa4c3338753c4ecf130b72b8adf62 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-07-20T17:50:36Z (GMT) No. of bitstreams: 1 Tese - Felicidad Santos Gimenez.pdf: 1802898 bytes, checksum: 245aa4c3338753c4ecf130b72b8adf62 (MD5) / Made available in DSpace on 2015-07-20T17:50:36Z (GMT). No. of bitstreams: 1 Tese - Felicidad Santos Gimenez.pdf: 1802898 bytes, checksum: 245aa4c3338753c4ecf130b72b8adf62 (MD5) Previous issue date: 2009-07-20 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / BACKGROUND: The anal cancer incidence, about 1,5% of malignant tumors of the gastrointestinal tract, has increased among men who have sex with men (MSM) which have contracted the human immunodeficiency virus (HIV+), to 70/100.000 people with the same behavior. The development of this cancer is a consequence of the interaction of several factors, among them, human papilomavirus (HPV) infection, immunodepression and anal sex practice. The similarities to the cervical cancer development (low and high grade precursor lesions, which can be early diagnosed) have inspired many studies performed in order to establish guidelines for the detection and treatment of precursor lesions of anal cancer, intending its prevention. The high-resolution anoscopy (HRA) is routinely used in this diagnosis; however, medical literature is even deficient concerning to the role of this diagnostic modality in the detection of precursor lesions of anal cancer. Taking these facts into account, this study has the intention of checking the validity of this test by comparing it to histopathology results of HIV+ patients of the Fundação de Medicina Tropical do Amazonas (FMT-AM). METHODS: The patients included (128) underwent a proctologic examination with the collection of anal channel cells, and using the Polimerase Chain Reaction (PCR) technique, it was researched the presence of HPV. Afterwards, HRA and topical anal application of Acetic Acid 3% during 2 minutes were performed. The acetowhite areas (AWA) detected were recorded concerning to their localization, classified by their color pattern, focal or coalescent aspect, relief, surface and vascular pattern. Facing the image characteristics of the observed lesions, these were classified into normal, low-grade squamous intraepithelial lesion (LSIL) or high-grade squamous intraepithelial lesion (HSIL) to the development of anal cancer. In addition, biopsies of the AWA were performed under local anesthesia, to undergo histopathologic analysis. RESULTS: Fro The HRA showed sensibility of 90%, specificity of 19,23%, positive predictive value of 41,66%, negative predictive value of 75%, and kappa coefficient of 0,076. Im the analyzed lesions it was found in the HSIL a more frequent visualization of 68% dense AWA, 61% flat, 61% smooth, 83% no-papillary and 70% normal vascular pattern, while in the LSIL they were 66% dense AWA, 68% flatraised or raised, 59% granular, 62% no-papillary and 53% normal vascular pattern. Gender, age, level of education and skin color did not represent associated factors to the development of AW lesions or to anal squamous intra-epithelial lesions (ASIL). The risk factors implied in the anal carcinogenesis were taking these factors into account, there was not statistic significance in the occurrence of AW lesions. Even though, to ASIL, it was demonstrated a relevance between anal sex adepts (p = 0,0493) and the presence of HPV infection (p = 0,006). CONCLUSIONS: The HRA has demonstrated to be sensible, but not specific in the detection of ASIL. In addition, it was not found association between HRA results histopathologic and the presence of HPV anal infection. The prevalence of HPV in the studied population was 79% and the prevalence of ASIL was 39,1%. Based on image data, the relief and surface pattern were able to distinguish between LSIL and HSIL, while the other characteristics did not show relevance. / INTRODUÇÃO: A incidência do câncer anal, cerca de 1,5% dos tumores malignos do trato digestório, vem aumentando em homens que fazem sexo com homens acometidos pelo vírus da imunodeficiência humana (HIV+), para até 70/100.000 pessoas com os mesmos hábitos. O desenvolvimento desse câncer é decorrente de vários fatores, dentre eles, a infecção pelo papilomavírus humano (HPV), a imunodepressão e a prática do sexo anal. As similitudes com o desenvolvimento do câncer cervical (presença de lesões precursoras de baixo e alto grau, que podem ser diagnosticadas precocemente) têm inspirado a realização de vários estudos para estabelecer rotinas de detecção e tratamento das lesões precursoras desse câncer, visando a sua prevenção. A anuscopia com magnificação de imagem (AMI) faz parte dessa rotina diagnóstica, porém a literatura médica ainda é escassa a respeito do papel desempenhado por essa modalidade. Este estudo pretende verificar a validade do exame comparando-o com o resultado da histopatologia, nos pacientes HIV+ atendidos na Fundação de Medicina Tropical do Amazonas (FMT-AM). MÉTODOS: Os 128 pacientes foram submetidos ao exame proctológico com coleta de células do canal anal e através da técnica da reação da cadeia de polimerase (PCR), pesquisou-se a presença do HPV. A seguir, realizou-se AMI com aplicação tópica anal de ácido acético 3% por 2 minutos. As lesões acetobrancas (ACB) detectadas foram anotadas quanto à sua localização, classificadas quanto à qualidade tintorial, ao aspecto focal ou coalescente, ao relevo, à superfície e ao padrão vascular. Diante das características imagenológicas das lesões observadas, essas foram classificadas em normais, lesões de baixo (LSIL) ou alto grau (HSIL) para o desenvolvimento do câncer anal. Foram feitas biópsias sob anestesia local das lesões ACB, para exame histopatológico. RESULTADOS: A AMI apresentou sensibilidade de 90%, especificidade de 19,23%, valor preditivo positivo de 41,66%, valor preditivo negativo de 75%, e coeficiente kappa de 0,076. Das lesões analisadas foi encontrado nas HSIL, uma visibilização mais freqüente de 68% ACB denso, 61% plano, 61% lisa, 83% não-papilar e 70% do padrão vascular normal, enquanto que as LSIL foram 66% ACB denso, 68% plano-elevado ou elevado, 59% granular, 62% não-papilar e 53% de padrão vascular normal. Gênero, idade, escolaridade e cor da pele não representaram fatores associados ao desenvolvimento de lesões ACB e lesões intraepiteliais escamosas anais (ASIL). Para os fatores de risco, implicados na carcinogênese anal e, em relação a esses fatores, não houve significância estatística na ocorrência de lesões ACB. No entanto, para as ASIL, demonstrou-se relevância entre os adeptos do sexo anal (p = 0,0493) e a presença de infecção pelo HPV (p = 0,006). CONCLUSÃO: A AMI demonstrouse sensível, porém não específica na detecção das ASIL. Não foi encontrada a associação entre os resultados histopatológicas da AMI e a presença de infecção anal pelo HPV. A prevalência de HPV na população estudada foi de 79% e a de ASIL foi de 39,1%. Baseado nos dados imagenológicos, o padrão de relevo e superfície puderam fazer distinção entre LSIL e HSIL, enquanto que as outras características não apresentaram relevância.

O biodiesel é quimicamente definido como ésteres monoalquílicos de ácidos graxos derivados de óleos vegetais, gorduras animais ou matérias graxas de descarte. O processo mais comumente empregado para a sua produção é a transesterificação catalisada por base. O controle de qualidade do biodiesel produzido é essencial para o aproveitamento deste como combustível. A Agência Nacional de Petróleo (ANP) estabelece diferentes métodos e especificações para a análise de biodiesel. A cromatografia gasosa é a técnica utilizada para a determinação de glicerol livre e ligado. Esta dissertação apresenta os resultados de dois processos de transesterificação para o óleo de soja: reação catalisada por ácido e reação catalisada por base. Os resultados foram avaliados por cromatografia gasosa de alta resolução, tendo sido demonstrado que a reação catalisada por base apresenta melhores resultados. Desenvolveu-se também nesta dissertação uma metodologia para análise de mono, di e triacilglicerídeos, como uma extensão da resolução ANP 42. A metodologia desenvolvida apresentou excelentes resultados para análises de glicerol ligado em amostra de óleos e biodiesel. / Biodiesel is chemically defined as fatty acid mono-alkyl esters derived of vegetable oils, animal fats or discarded greases. The process more commonly employed for biodiesel production is transesterification catalyzed by base. The quality control of the produced biodiesel is essential for its use as fuel. The National Agency of Petroleum (ANP) establishes different methods and specifications for the analysis of biodiesel. The proposed technique for determination of free and bonded glycerol is gas chromatography. This study presents the results of two reactions of transesterification of the soy oil: catalyzed by acid and catalyzed by base. The results were evaluated by high resolution gas chromatography, which demonstrated better results when basic catalysis was employed. A methodology for mono, di and triacylglicerides was also developed in this dissertation, as an extension of the resolution ANP 42. The developed methodology presented excellent results for bonded glycerol analyses in samples of oils and biodiesel.

Objetivos: Investigar possíveis alterações citogenéticas, através da técnica de bandamento de alta resolução, em indivíduos com anomalias craniofaciais associadas ao atraso no desenvolvimento neuropsicomotor e sem diagnóstico clínico-genético definido, com cariótipo (com bandas) prévio normal e estabelecer possível correlação entre o fenótipo dos indivíduos e as regiões cromossômicas alteradas. Local de execução: Laboratório de Citogenética Humana e Serviço de Genética Clínica, HRAC-USP, Bauru-SP. Indivíduos estudados e Resultados: O cariótipo de alta resolução de 16 indivíduos com anomalias craniofaciais associadas ao atraso no desenvolvimento neuropsicomotor pertencentes ao HRAC-USP, Bauru permitiu detectar alterações citogenéticas estruturais em 4 (25%) dos 16 indivíduos. Em 3 indivíduos detectou-se deleções em regiões subteloméricas (cromossomos 4p, 9p e 18q) e, em 1 indivíduo detectou-se adição de segmento cromossômico de origem desconhecida na região telomérica do cromossomo 12p. Conclusões: A frequência alta (25%) de alterações cromossômicas estruturais em regiões cromossômicas terminais (teloméricas e subteloméricas) mostra que a técnica de alta resolução é útil na identificação de alterações nessas regiões, portanto, indivíduos com anomalias craniofaciais e atraso mental, sem diagnóstico genético-clínico definido, cujo cariótipo convencional foi normal, devem ser, submetidos à análise dos cromossomos por meio do cariótipo de alta resolução antes do procedimento de CGHarray. / Objective: To investigate possible cytogenetic abnormalities through high resolution banding technique in individuals with craniofacial anomalies presenting previous normal karyotype, associated to neuropsychological development delay, without clinic-genetic diagnoses, and establish possible correlation between phenotype and possible candidate chromosomal regions. Local: Human Cytogenetic Laboratory and Clinical Genetic Service, HRAC-USP, Bauru, SP. Individuals and Results: High resolution karyotype of 16 individuals with craniofacial anomalies associated to neuropsychological development delay in follow-up at the HRAC-USP, Bauru allowed the detection of structural chromosomal abnormalities in 4 (25%) of them. Three individuals presented deletion in the subtelomeric region (chromosomes 4p, 9p, and 18q), and one individual presented an addition of an unknown chromosomal fragment in the telomeric region of chromosome 12p. Conclusions: The high frequency (25%) of structural chromosomal abnormalities in terminal region (telomeric and subtelomeric) shows that the high resolution technique is useful for identification of structural anomalies in these regions. Therefore, individuals with craniofacial anomalies associated to neuropsychological development delay without a definitive clinic-genetic diagnoses presenting a normal conventional karyotype, should be submitted to chromosomal analysis through high resolution karyotype before CGH-array procedure.

Inductively coupled plasma mass spectrometry is a well-established technique for the measurement of isotope ratios. Double focussing mass analysers enable increased resolution to be applied to separate spectroscopic interferences, or the use of multi-collector detection techniques for high precision isotope ratio determinations. For the Central Science Laboratory (CSL), trace elements team, methods were developed for Zn and Fe isotope ratio measurements in acid digested faecal samples from a human nutritional study. For Zn, a novel high resolutionlmulticollector combination was employed; for Fe a single collector, high resolution method was used. In both cases, samples from the nutritional study known to contain the analytes in natural isotopic abundance were used to correct for the mass bias. Two independent methods for determining Zn and Fe isotope ratios were used to validate the measurement strategies. The team at CSL are also involved in the authentication of food products. Isotope ratio and elemental concentration data were used to determine the geographical origin of rice samples, and to distinguish between traditional and modem Basmati rice grown in India and Pakistan. NERC Isotope Geosciences Laboratory are primarily concerned with the achievable accuracy and precision of an isotope ratio measurement. Use of a mass bias correction expression appropriate to the ICP-MS instrument is essential for high quality isotope ratio measurements. Cd and Sn were used to study the variation of the mass bias in a double focussing ICP-MS system with time, absolute mass and mass difference. It was proposed that mass bias should be considered as a result of the change in the instrument response with mass, and not a fundamental parameter in its own right. A method for determination of the best mass bias correction model for an individual instrument, through examination of the instrument response function was developed.

No description available.

This dissertation presents an investigation on the capabilities of Near-Field Microwave Microscopy (NFMM) for the characterization of surface and subsurface materials. Subsurface characterization refers to the detection, differentiation and imaging of dielectric, and metallic features that are coated with an insulating layer. The design, simulation and modeling, and testing of a dielectric resonator (DR)-based NFMM and a coaxial transmission line resonator-based NFMM are discussed in detail in this work. Additionally, materials differentiation and imaging capabilities of each microscope are examined using several bulk samples, liquids, GaAs MMIC circuits, and gold/glass testing patterns. The 5.7 GHz DR-based NFMM uses a microwave probe that consists of a commercial gold-coated probe tip coupled to a DR through a non-resonant microstrip line. The probe is enclosed in an aluminum cavity to preserve the quality factor of the probe (Q=986) and therefore to enhance its sensitivity. The development of a lumped-element model of this DR-based probe is discussed in this work. Characteristics of this design are its high Q and the ability to resolve differences in permittivity (E’r) of insulting bulk samples and liquids as small as ∆E’r =1.75 and ∆E’r =0.04, respectively. The imaging capabilities of this design were verified using a GaAs MMIC phase shifter. It was found that a 10 um wide microstrip line is successfully resolved and that the spatial resolution of the microscope is 50 um when using a tungsten tip with an apex radius of 25 um. Additionally, measurement of the electrical resistance of an additive manufactured resistor was measured using the DR-based NFMM without the need of contacts. The percent difference between the electrical resistance measured using the DR-based NFMM and a four-point probe is 9.6%. Furthermore, the DR-based NFMM allows simultaneous imaging of topography and RF electrical conductivity of rough thick films without the need of an additional distance sensor; this ability is demonstrated for a rough CB028 thick film. The 5GHz coaxial resonator transmission line-based NFMM employs a half-wavelength coaxial transmission line resonator terminated in a sharp tungsten tip as the microwave probe. A quartz-tuning fork based distance following feedback system is integrated with the microwave probe in order for the NFMM to operate in non-contact mode. The Q of the probe is degraded by 30% (Q=55) due to the presence of the quartz tuning fork. Despite the low Q, this NFMM is able to differentiate several insulating bulk samples (3.8 < E’r < 25) even if they are coated with an insulating layer of thickness similar to the apex radius of the tungsten tip. Finally, the coaxial resonator transmission line-based NFMM is able to image subsurface permittivity distribution of a flexible polymer-composite PDMS-Ba0.55Sr0.45TiO3 49% which is coated with 10 um thick parylene-C layer. Measurements performed at a tip-sample distance of 100 nm reveal that within an area of 50 um x 50 um, the relative permittivity of the polymer-composite is not constant but varies between 6.63 and 11.78.