Os exames de neuroimagem são essenciais na rotina pré-cirúrgica de pacientes com lesão encefálica. A ressonância magnética (RM) e a tomografia computadorizada (TC) são métodos consagrados que fornecem valiosas informações anatômicas das lesões e áreas adjacentes. A ressonância magnética funcional (RMf) é um método mais recente que pode dar suporte a neurocirurgia demonstrando as áreas que apresentam resposta hemodinâmica durante a realização de determinadas tarefas. Por outro lado, o neurocirurgião deve associar estas novas técnicas aos conhecimentos da anatomia empregados no ato cirúrgico. Ribas (2005) estabeleceu um sistema de pontos-chave aplicados à anatomia microcirúrgica, que representam relações entre a superfície do crânio e a superfície do cérebro e demonstra erros menores que 2 cm entre estes pontos e os sulcos e giros cerebrais num estudo em cadáveres. Entretanto, a metodologia não permitiu avaliar a relação com areas cerebrais que mostram atividade hemodinâmica durante a realização de tarefas somatossentivas e motoras. O objetivo desta dissertação foi de avaliar métodos de fusão de imagens geradas por TC, RM e RMf com intuito de verificar as relações craniométricas com os sulcos e giros, e a relação destes pontos com os aspectos funcionais das áreas motora e somatosensitiva. MÉTODOS: Foram realizados exames de RM e RMf com paradigmas motor e somatosensitivo em aparelho de três Tesla (3T) em dez sujeitos que realizaram TC de crânio prévia, (dois com lesão cerebral e oito sem alterações cerebrais visíveis a TC). Escolhemos quatro dos dez pontos-chave estudados por Ribas para avaliação neste trabalho: a intersecção entre os sulcos frontal inferior e pré-central; a intersecção entre os sulcos frontal superior e o précentral; o ponto rolândico superior; e a intersecção entre os sulcos intraparietal e o sulco pós-central devido às suas relações com areas classicamente relacionadas à função motora e somatossensitiva. Os dados de TC, RM e RMf foram analisados por diferentes programas e os resultados comparados. O processo final teve intuito de co-registrar espacialmente as três técnicas e permitir medidas de distâncias em imagens nas três dimensões (3D). RESULTADOS: determinamos um fluxograma de processos computacionais que permitiram mensurar a congruência espacial entre as técnicas de TC, RM, RMF. Não foi encontrada ferramenta computacional que, isoladamente, permitisse todo o conjunto de funcionalidades necessárias para atingir o objetivo. A implementação do processo de fusão das três modalidades mostrou-se viável com a utilização quatro softwares de acesso gratuito (Osirix, Register, Mricro e FSL). Em quatro voluntários foram determinadas as distâncias espaciais entre os pontos-chave na superfície cerebral e na superfície do crânio, a média das quais foi de 2,5cm (±0,6cm) - levando-se em que esta medida inclui as dimensões da tábua ossea e espaços liquóricos, este valor se encontra dentro do que foi demonstrado por Ribas. Porém, a média das distâncias entre pontos na superfície do crânio e pontos de maior resposta na RMf, e entre estes e pontos-chave da superfície do cérebro foi maior, respectivamente de 5,0cm (±1,7cm) e 3,6cm (±2,1cm). Estes achados mostram variabilidade funcional inter-individual, aparentemente maior que a anatômica. Os dados destes estudo mostram que a técnica é viável, e ampliação da casuística pode permitir a análise estatística, necessária para utilização deste método na prática clínica. / Neuroimaging studies have a pivotal role in pre-surgical assessment of patients with brain lesions. Magnetic Resonance Imaging (MRI) and Computerized Tomography (CT) are established techniques providing anatomic information of the lesion and surrounding areas. Functional MRI (fMRI) is a recent method applied to probe brain function via hemodynamic response of brain regions involved in certain tasks, and thus provide useful information to the neurosurgeon. On the other hand, these new techniques have to be added to the knowledge necessary to the neurosurgery act. Ribas (2005) have established a system based on key-points aimed to guide microsurgical interventions. The system consists of anatomical relationships between points in the surfaces of the skull and the cerebrum and is reported to have errors below 2 cm of the intended cerebral sulci and giri in a post-mortem study. Nevertheless, this method does not allow for studying the relationship of the cerebral regions showing hemodynamic response to somatosensory and motor tasks. Our aim was to evaluate image fusion techniques applicable to CT, MRI and fMRI in order to verify the craniometrical relations between skull surface, cerebral surface and areas with maximal hemodynamic response to somatosensory and motor tasks. METHODS: We performed MRI and fMRI studies in ten subjects who had a CT scan performed for other reasons (8 healthy volunteers and 2 patients with localized brain lesions) using somatosensory and motor paradigms in a 3T MRI system. We have selected four out of the ten key points determined by Ribas to perform this analysis: the intersection between the inferior frontal and pre-central sulci; the intersection between the superior frontal and precentral sulci; the superior rolandic point; and the intersection between the intraparietal and post-central sulci. This choice was based on the classical localization of brain regions associated with somatossensory and motor functions. CT, MRI and fMRI data were analysed using different software packages, and the results were compared. The final goal of the process was to spatially co-register the three techniques and distance measurements in three dimensions (3D). RESULTS: we have established a pipeline using different computational processes to measure the spatial anatomic congruency between the key points shown in CT, MRI and fMRI images. We did not find a single software package enabling all the functionalities necessary to accomplish our goals. The implementation of the three imaging modalities fusion process was feasible using four public domain softwares (Osirix, Register, Mricro e FSL). We have determined the distances between the key points in four subjects (e patient). The average distance between the skull surface and brain surface points was 2.5cm (±0.6cm) and taking into account the calvarium thickness and cerebro-spinal fluid dimensions, this value is within what was observed in Ribass study. The average distance between the key points in the skull surface and the fMRI maximum response point, and the average between the brain surface and the fMRI maximum response point was larger, respectively 5.0cm (±1, 7cm) and 3.6cm (±2,1cm). These findings show that the intersubject functional variability is apparently larger then the inter-subject anatomical variability. Our results show that image fusion between CT, MRI and fMRI is possible. We believe that an increased number of subjects and appropriate statistical analysis will help to guide the possible application of this method in clinical routine.

The introduction of the Enhanced Actinide Removal Plant (EARP) at Sellafield in 1994 was designed to decontaminate radioactive effluents produced during nuclear fuel reprocessing. Through the action of flocculation with iron, followed by filtration, the effluents are decontaminated before being discharging to sea. The plant has been in successful operation for the past 20 years, and has made a significant difference to the level of radioactivity of the waste. However, little is known about the formed flocs. Particular concern focuses around future changes to the effluent compositions to be processed through EARP. These future feeds will potentially contain significantly less iron, thus potentially impacting upon the flocculation process and the efficiency of the decontamination process. The effluents currently treated contain significant concentrations of iron, stemming from the Magnox fuel reprocessing plant, along with actinides, fission and corrosion products. The flocculation of these acidic radioactive ferric feeds results in the formation of solid iron hydroxide flocs with encapsulated radioactivity. The flocs are then filtered, encapsulated and stored. It is envisioned that by characterising the floc properties, both physically and chemically a greater understanding of EARP can be obtained, ultimately leading to a maintained process efficiency with alternative feed compositions. The effect of a reduction in iron concentration on the chemical and physical properties of the flocs has been studied. The presence of any iron in the mock effluents was found to beneficially increase the contaminant decontamination factors (DF). However, the efficacy of this increase varied between contaminates. The DFs of group I and II metals ranged from 7.10 to 1.19 while lead ranged from 4x105 to 1.60, dependent upon iron concentration. Transition metal and lanthanide contaminants were marginally affected. With the use of agar embedding, the 'liquid form' of the flocs has been retained for two and three dimensional observations. SEM/EDX analysis has allowed for the inspection and chemical characterisation of the flocs while 2D microscope image analysis has allowed for the study of floc size and shape. A range of diameters, 300 - 1500 micro metre were found. Three dimensional X-ray Computer Tomography (3D X-ray CT) conducted at the Manchester X-ray Imaging Facility (MXIF) has led to the physical characterisation and classification of the flocs. Further, by studying the 3D shape it has been possible to classify a floc as a granule, fibre, chip or blade according to the Zingg classification with the majority of formed flocs being classified as granules.

The problem of reconstructing an image from a set of tomographic data is not new, nor is it lacking attention. However there is still a distinct gap between the mathematicians and the experimental scientists working in the computed tomography (CT) imaging community. One of the aims in this thesis is to bridge this gap with mathematical reconstruction algorithms and analysis approaches applied to practical CT problems. The thesis begins with an extensive analysis for assessing the suitability of reconstruction algorithms for a given problem. The paper presented examines the idea of extracting physical information from a reconstructed sample and comparing against the known sample characteristics to determine the accuracy of a reconstructed volume. Various test cases are studied, which are relevant to both mathematicians and experimental scientists. These include the variance in quality of reconstructed volume as the dose is reduced or the implementation of the level set evolution method, used as part of a simultaneous reconstruction and segmentation technique. The work shows that the assessment of physical attributes results in more accurate conclusions. Furthermore, this approach allows for further analysis into interesting questions in CT. This theme is continued throughout the thesis. Recent results in compressive sensing (CS) gained attention in the CT community as they indicate the possibility of obtaining an accurate reconstruction of a sparse image from severely limited or reduced amount of measured data. Literature produced so far has not shown that CS directly guarantees a successful recovery in X-ray CT, and it is still unclear under which conditions a successful sparsity regularized reconstruction can be achieved. The work presented in the thesis aims to answer this question in a practical setting, and seeks to establish a direct connection between the success of sparsity regularization methods and the sparsity level of the image, which is similar to CS. Using this connection, one can determine the sufficient amount of measurements to collect from just the sparsity of an image. A link was found in a previous study using simulated data, and the work is repeated here with experimental data, where the sparsity level of the scanned object varies. The preliminary work presented here verifies the results from simulated data, showing an "almost-linear" relationship between the sparsity of the image and the sufficient amount of data for a successful sparsity regularized reconstruction. Several unexplained artefacts are noted in the literature as the `partial volume', the 'exponential edge gradient' or the 'penumbra' effect, with no clear explanation for their cause, or established techniques to remove them. The work presented in this paper shows that these artefacts are due to a non-linearity in the measured data, which comes from either the set up of the system, the scattering of rays or the dependency of linear attenuation on wavelength in the polychromatic case. However, even in monochromatic CT systems, the non-linearity effect can be detected. The paper shows that in some cases, the non-linearity effect is too large to ignore, and the reconstruction problem should be adapted to solve a non-linear problem. We derive this non-linear problem and solve it using a numerical optimization technique for both simulatedand real, gamma-ray data. When compared to reconstructions obtained using the standard linear model, the non-linear reconstructed images show clear improvements in that the non-linear effect is largely eliminated. The thesis is finished with a highlight article in the special issue of Solid Earth, named "Pore-scale tomography & imaging - applications, techniques and recommended practice". The paper presents a major technical advancement in a dynamic 3D CT data acquisition, where the latest hardware and optimal data acquisition plan are applied and as a result, ultra fast 3D volume acquisition was made possible. The experiment comprised of fast, free-falling water-saline drops traveling through a pack of rock grains with varying porosities. The imaging work was enhanced by the use of iterative methods and physical quantification analysis performed. The data acquisition and imaging work is the first in the field to capture a free falling drop and the imaging work clearly shows the fluid interaction with speed, gravity and more importantly, the inter- and intra-grain fluid transfers.

Three dimensional (3D) woven composites have attracted the interest of academia and industry thanks to their damage tolerance characteristics and automated fabric manufacturing. Although much research has been conducted to investigate their out-of-plane "through thickness" properties, still their in-plane properties are not fully understood and rely on extensive experimentation. The aim of this work is to study the electromechanical behaviour of three different fibre architectures of 3D woven composites "orthogonal (ORT), layer-to-layer (LTL) and angle interlock (AI)" loaded, in three different orientations "warp (0º), weft (90º) and off-axis (45º)", in quasi-static tension. Stress/strain response is captured as well as damage initiation and evolution up to final failure. The ORT architecture demonstrated a superior behaviour, in the off-axis direction, demonstrated by high strain to failure (~23%) and high translaminar energy absorption (~40 MJ/m3). The z-binder yarns in ORT suppress delamination and allow larger fibre rotation during the fibre "scissoring motion" that enables further strain to be sustained. In-situ electrical resistance variation is monitored using a four-probe technique to correlate the resistance variation with the level of damage induced while loading. Monotonic and cyclic "load/unload" tests are performed to investigate the effect of piezo-resistivity and residual plasticity on resistance variation while damage is captured by X-ray scanning during interrupted tests at predefined load levels. In addition, this study investigates the potential of using 3D woven composites in joint assemblies through open-hole tension and "single fastener double-lap joint" bearing strength tests. 3D woven composites in the off-axis orientation, especially ORT, demonstrate a potential for overcoming some of the major challenges for composite joints' applications which are the pseudo-ductility, stress redistribution away from the notch and notch insensitivity. Finally, the study proposes a micro-mechanics based damage model to simulate the response of 3D orthogonal woven composites loaded in tension. The proposed model differs from classical damage mechanics approaches in which the evolution law is obtained by retrofitting global experimental observations.

Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-11-24T17:32:52Z No. of bitstreams: 1 Isabela Leal Calado.pdf: 41101678 bytes, checksum: 5a357894da2705a51e04c67d9660b699 (MD5) / Made available in DSpace on 2017-11-24T17:32:52Z (GMT). No. of bitstreams: 1 Isabela Leal Calado.pdf: 41101678 bytes, checksum: 5a357894da2705a51e04c67d9660b699 (MD5) Previous issue date: 2016-05-03 / FAPEMA, CNPQ. / The prevalence of obesity has increased dramatically in developed and emerging countries. Simultaneously, it is observed the increase in the prevalence of diseases such as hypertension. In the black population, obesity is a chronic problem, and the prevalence of hypertension is twice as high as in whites. It is agreed that the risk for cardiovascular diseases are associated more to central obesity, than to total obesity. Computed tomography (CT) is the gold standard for assessment of body composition, but its high cost limits the use in clinical practice and in epidemiological studies. Anthropometric indicators of obesity (AIO) are alternatives for their safety, ease and correlation with visceral fat. However, the literature differs on what would be the best method to be used for this purpose. This study had two goals: to investigate association between AIO and hypertension in African descent and determine the AIO which shows greater relationship with visceral adipose tissue (VAT) in hypertensive African descent residing in Quilombo communities in Alcantara-MA. In the first article we evaluated 932 African descent aged <60 years, using the variables: blood pressure, body mass index (BMI), waist circumference (WC), waist-hip ratio (WHR), waist-to-height (WHtR), conicity index (C Index) and sagittal abdominal diameter (SAD). To evaluate the association between hypertension and AIO it was used the Poisson regression model with robust variance. The results showed that BMI was associated with hypertension in both sexes, but the AIO that remained as a risk factor for hypertension, was DAS for men and WC and WHtR for women. In the second article, we evaluated 143 hypertensive African descent aged ≥ 18 years. The following AIO were used: BMI, WC, WHR, WHtR and SAD. The TAV was evaluated by TC, for single volumetric cut at the level of L4-L5 vertebrae. To assess the relationship of the AIO with VAT, we used multiple linear regression analysis, initially adjusted for age and later by age, weight, height and hip circumference. BMI, WHtR and WHR were not included due to collinearity with the weight, height and hip circumference. The results showed that in men, 2 CC showed higher relationship with TAV (Coef = 7.37; p value <0.0001; R = 57.0%). For women, DAS was the AIO that was most associated with TAV (Coef = 0.60; p value <0.023; 2 R = 54.0%). This study concluded that BMI can be used as an anthropometric index of obesity to assess the risk of hypertension in African descent living in quilombola communities. Already in hypertensive African descent, WC was the AIO that was better related to the VAT in men, while the SAD with the VAT of hypertensive women. / A prevalência de obesidade tem aumentado dramaticamente nos países desenvolvidos e nos emergentes. Paralelamente, observa-se aumento na prevalência de doenças associadas como hipertensão. Na população negra, a obesidade é um problema crônico, e a prevalência de hipertensão se apresenta duas vezes maior do que em brancos. Concorda-se que o risco para doenças cardiovasculares está relacionado à obesidade central, mais do que à obesidade total. A tomografia computadorizada (TC) é padrão-ouro para avaliação da composição corporal, mas seu custo elevado limita o uso na prática clínica e em estudos epidemiológicos. Indicadores antropométricos de obesidade (IAO) são alternativas por sua inocuidade, facilidade e correlação com gordura visceral. Todavia, a literatura diverge sobre qual seria o melhor método a ser utilizado para esse fim. Esse estudo dispôs de dois objetivos: investigar associação entre IAO e hipertensão em afrodescendentes e determinar o IAO que apresenta maior relação com tecido adiposo visceral (TAV) em afrodescendentes hipertensos, residentes em comunidades quilombolas em Alcântara-MA. No primeiro artigo avaliou-se 932 afrodescendentes com idade ≥18 e <60 anos, utilizando-se as variáveis: pressão arterial, índice de massa corporal (IMC), circunferência da cintura (CC), relação cintura-quadril (RCQ), relação cintura-estatura (RCEst), índice de conicidade (Índice C) e diâmetro abdominal sagital (DAS). Para avaliar a associação entre IAO e hipertensão utilizou-se o modelo de regressão de Poisson com variância robusta. Os resultados demonstraram que o IMC se associou com hipertensão em ambos os sexos, porém, os IAO de obesidade que se mantiveram como fator de risco para hipertensão, foi DAS para os homens e CC e RCEst para mulheres. No segundo artigo, foram avaliados 143 afrodescendentes hipertensos com idade ≥ 18 anos. Foram utilizados os IAO: IMC, CC, relação RCQ, RCEst e DAS. O TAV foi avaliado por TC, por corte volumétrico único em nível das vértebras L-4-L5. Para avaliar a relação dos IAO com TAV, utilizou-se análise de regressão linear múltipla, inicialmente ajustada por idade e posteriormente por idade, peso, estatura e circunferência do quadril. Os indicadores IMC, RCEst e RCQ não foram incluídos devido a colinearidade com as variáveis peso, estatura e circunferência do quadril. Os resultados revelaram que, nos homens, CC 2 apresentou maior relação com TAV (Coef. = 7,37; p valor < 0,0001; R = 57,0%). Para as mulheres, DAS foi o IAO que mais se correlacionou com TAV (Coef. = 0,60; p valor <0,023; R = 54,0%). Este estudo concluiu que o IMC pode ser utilizado como indicador antropométrico de obesidade para avaliar risco de hipertensão em afrodescendentes residentes em comunidades quilombolas. Já em afrodescendentes hipertensos, a CC foi o IAO que melhor se relacionou com o TAV em homens, enquanto o DAS com o TAV de mulheres hipertensas.

O presente estudo destinou-se a realizar uma análise comparativa entre a osteoartrite de quadris e o posicionamento acetabular através de exames radiográficos e de tomografia computadorizada. Foram incluídos 13 pacientes portadores e oito não-portadores de osteoartrite primária do quadril, recrutados no Ambulatório do Instituto de Ortopedia e Traumatologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. Os exames foram submetidos à medição das seguintes variáveis: ângulos acetabulares, ângulo centro-borda, sinal do entrecruzamento, largura e profundidade do acetábulo no RX; anteversão e ângulos setoriais acetabulares nos tomogramas. Não se verificou diferença estatisticamente significatova na anteversão acetabular entre ambos os grupos, ao passo que o ângulo acetabular setorial posterior mostrou média inferior no grupo afetado / The present study intends to develop a comparative analysis between primary hip osteoarthritis and acetabular positioning through x-ray exams and computed tomographic scans. 13 affected and 8 non-affected patients by degenerative hip disease with no underline causes are recruited within the ambulatory care service of the Institute of Orthopedics and Traumatology of the Hospital of Clinics, São Paulo University Medical School. Their radiographic exams are studied for extracting some parameters named as: acetabular angles, center edge angle, crossover sign, acetabular width and acetabular depth. Tomographic films give information to measure acetabular ante version and acetabular setorial angles. Statistically, there is no significant relationship concerning acetabular ante version within the two groups, although, the posterior acetabular setorial angle shows a lower median value in the osteoarthritic group

O recente aumento da procura por implantes osseointegráveis consequentemente levou ao aumento dos procedimentos de enxertos ósseos. Com isso, novos materiais têm surgido para estes procedimentos. Um destes materiais é o osso bovino integral (OBIN), cujo diferencial é o seu método de processamento, que visa manter suas características o mais próximas possível ao osso in natura. Por se tratar de um material novo, ainda existem poucos estudos avaliando seu desempenho, sendo a maioria deles estudos pré-clínicos testando sua biocompatibilidade. Portanto, o objetivo deste trabalho foi avaliar o desempenho do OBIN na região maxilofacial através de um modelo experimental em animais. Foram criados defeitos ósseos na base da mandíbula de coelhos, onde foram enxertados blocos de OBIN nos grupos experimentais e deixados vazios nos grupos controle. Os animais foram sacrificados nos tempos 0 (imediatamente após a cirurgia), 3 e 6 meses após o procedimento cirúrgico. As mandíbulas foram analisadas através de tomografias computadorizadas de feixe cônico, onde foi analisada a regeneração óssea qualitativamente e quantitativamente. Na análise qualitativa observou-se que aos três e seis meses, nos animais do grupo controle, não houve regeneração total, restando um defeito côncavo na base da mandíbula, confirmando que o defeito criado possuía tamanho crítico. No grupo experimental, no tempo 0, observou-se grande variação de densidade entre os enxertos e esta variação pareceu influenciar seu desempenho, havendo mais regeneração óssea nos menos densos. No tempo 3, todos os enxertos haviam integrados, com perda de densidade, sugerindo uma reabsorção parcial. Aos seis meses, a reabsorção e regeneração pareciam mais avançadas do que aos três meses. Na análise quantitativa houve diferença estatisticamente significante nos grupos controles entre os tempos 0 e os tempos 3 e 6. Nos grupos experimentais não houve diferença entre os tempos e na comparação entre os grupos controles e experimentais houve diferença estatisticamente significante entre todos os tempos. Os resultados observados sugerem que o OBIN é um material indicado para a realização de procedimentos de enxerto na região maxilofacial, com aparente reabsorção e substituição por osso regenerado, ideal para a reabilitação com implantes ósseo integráveis. / The recent increase in the demand for dental implants consequently led to increased bone grafting procedures. Therefore, new materials have emerged for these procedures. One of these materials is integral bovine bone (IBB) whose differential is its processing, which aims to maintain its characteristics as close as possible to the raw bone. Because it is a new material, there are only a few studies evaluating its performance, with the majority of them constituted of preclinical studies testing its biocompatibility. For this reason, the aim of this study was to evaluate the performance of the IBB at the maxillofacial region through an experimental model in animals. Bone defects were created on the basis of the mandible of rabbits, which were grafted with blocks of IBB in the experimental groups, while control groups were left empty. The animals were sacrificed at time 0 (immediately after surgery), 3 and 6 months after surgery. The jaws were analyzed using cone beam computed tomography, where bone regeneration was analyzed qualitatively and quantitatively. Qualitative analysis showed that at three and six months, in the control group, there was not full regeneration, leaving a concave defect in the base of the mandible, confirming that the defect created had critical size. In the experimental group, at time 0, there was wide variation in density between the grafts and this variation appeared to influence their performance, seeming to be more bone regeneration in less dense ones. At time 3, all grafts were integrated, and a density loss, suggesting a partial resorption of the graft, was also observed. At six months, resorption and regeneration seemed more advanced than at three months. The quantitative analysis did not showed statistically significant difference in controls between time 0 and times 3 e 6. In experimental groups there was no difference between times and comparison between control and experimental groups were statistically significant different between all time. The data suggest that the IBB is a material suitable for the realization of grafting procedures in the maxillofacial region, with apparent resorption and replacement by regenerated bone, ideal for rehabilitation with dental implants.

Permeable friction course (PFC), or new generation open-graded friction course (OGFC) mixtures, are hot mix asphalt (HMA) characterized by high total air voids (AV) content (minimum 18 %) as compared to the most commonly used dense-graded HMA. The high AV content confers to PFC mixtures both high permeability and noise reduction effectiveness. These characteristics and the high values of surface friction exhibited by PFC mixtures, as compared to dense-graded HMA, lead to improvements in safety and the environment, which make PFC one of the safest, cleanest, and quietest alternatives currently available for surface paving. The main objective of this study was improving the current PFC mix design method and construction practices in terms of compaction control. Corresponding results were integrated in an improved mix design method that is based on the guidelines of the current mix design method used by the Texas Department of Transportation. The improved mix design included modified computation of the inputs required to determine mixture density (or corresponding total AV content). These changes led to a proposed modification of the density specification for mix design from 78-82 % to 76-80 %. In addition, the water-accessible AV content was proposed as a surrogate of the total AV content for mix design and evaluation. The improved mix design method also includes verification of drainability, durability, and stone-on-stone contact. Computation of the expected value of permeability (E[k]) and measurement of the water flow value were recommended, respectively, for verification of drainability in the laboratory (using specimens compacted in the Superpave Gyratory Compactor (SGC)) and in the field. The Cantabro loss test conducted in both dry- and wet-conditions was suggested for assessing mixture durability. Improved criteria were proposed for verification of stone-on-stone contact based on the evaluation of the AV content in the coarse aggregate fraction of the mixture. In addition, comparison of the internal structure of field-and laboratory-compacted mixtures supported recommendation of a field-compaction control. Recommendations to reduce the horizontal heterogeneity of AV encountered in PFC specimens included using road cores with a minimum 152.4 mm diameter and coring SGC specimens from 152.4 to 101.6 mm in diameter

Thesis--University of Oklahoma. / Bibliography: leaves 120-128.

The study of internal structure of materials has always been an essential issue in a variety of application fields, from the medical radiology to the materials science. X-ray computed microtomography (with both conventional and synchrotron radiation sources) has a great potential for these purposes because its three-dimensional and non destructive nature as well as the fact that it does not require any sample preparation and it allows to study samples under stress or after consecutive treatments. The recent developments of new X-ray sources with innovative imaging techniques, as well as novel high resolution detectors, allow moving forward the maximum achievable resolution of this technique to a few micrometers or even less. This contributed to increase its application in biomedical purposes, but also to raise the need for quantitative analysis of the reconstructed data. Indeed in most of the cases a quantitative characterization of the samples microstructures is needed to better understand their physical and chemical behavior, the effects of manufacturing process or the response to stress. Dedicated software packages have been developed to perform a geometrical and morphological characterization of the samples texture and to evaluate some typical parameters commonly used to classify porous media such as porosity, cell size distribution, connectivity and anisotropy. In this work two case studies have been considered for the application of a quantitative analysis approach to microtomography datasets: the first concerns the characterization of bone ingrowth within tissue engineering scaffolds, while the second is related to the extraction of morphological descriptors for the architecture of human skull bones. It will be shown how suitable image processing and analysis techniques are able to effectively quantify significant parameters such as the trabecular thickness of the skull bones as well as the porosity and the degree of connectivity of bone tissue engineering scaffolds. Similar quantitative analysis methods applied to microtomography images have to be considered as an effective methodology for a comprehensive characterization of other biomedical samples.