Överkäkshörntänderna erumperar normalt mellan 11 till 13 års ålder. Dessa kan dock bli retinerade och orsaka rotresorption på intilliggande incisiver. Konventionell röntgen upptäcker rotresorption i 12.5 procent av fallen, medan datortomografiundersökning (CT) upptäcker resorptioner i ungefär 50 procent av fallen. En huvudsaklig etiologisk faktor till resorptionerna är fysisk kontakt mellan den retinerade överkäkshörntanden och incisivens rot. Syftet med denna studie var att undersöka rotresorberade överkäksincisivers prognos efter förflyttning av intilliggande överkäkshörntänder. Studien inkluderade 22 patienter med totalt 31 rotresorberade överkäksincisiver. Alla patienter hade genomgått ortodontisk behandling för att förflytta de retinerade överkäkshörntänderna. Intraoral röntgen eller CT-undersökning genomfördes direkt efter avslutad behandling (T1). Uppföljning med CT genomfördes ett antal år efter avslutad behandling (T2). Alla röntgenologiska bilder från T2 jämfördes med bilderna från T1. Rotresorptionerna bedömdes avseende lokalisering och resorptionsgrad. Graden av resorption indelades i mild, måttlig och grav. Utvecklingen av resorptionerna mellan T1 och T2 bedömdes som antingen avstannad, progredierad eller minskad. Resultatet visar att 54.8 procent av resorptionerna var avstannade vid T2 jämfört med T1, 22.6 procent av resorptionerna hade progredierat, 6.5 procent av resorptionerna hade minskat och 16.1 procent av de rotresorberade incisiverna var extraherade vid T2. Alla extraherade incisiver var diagnostiserade med grav rotresorption. Sammanfattningsvis visar aktuella resultat att; (1) ungefär 50 procent av rotresorptionerna avstannade på lång sikt, (2) ungefär 20 procent av resorptionerna progredierade, (3) minskning var ovanlig och (4) incisiver med grava resorptioner direkt efter korrektion av de retinerade överkäkshörntänderna hade en dålig långtidsprognos i kombination med exempelvis trauma eller parodontit. / Maxillary canines normally erupt at the age of 11 to 13. These can however become impacted and cause root resorptions of adjacent incisors. Conventional radiography reveals root resorptions in 12.5 per cent of cases. Computed tomography (CT) reveals root resorptions in about 50 per cent of cases. A main etiological factor is physical contact between the impacted maxillary canine and the incisor root. The aim of the present study is to evaluate the prognosis of maxillary incisors with root resorptions after correction of adjacent maxillary canines. The present study includes 22 patients with a total of 31 root resorbed maxillary incisors. All patients had undergone orthodontic treatment in order to correct the impacted maxillary canines. Intraoral radiographs or CT investigations were taken immediately post treatment (T1). Follow-up examinations with CT were performed a number of years later (T2). All radiographs taken at T2 were compared with the radiographs taken at T1. The root resorptions were examined with respect to localization and degree of resorption. The degree of resorption was graded as slight, moderate and severe. The change of resorptions between T1 and T2 was evaluated as unchanged, increased or decreased. The results show that 54.8 per cent of the resorptions were unchanged at T2 compared to T1, 22.6 per cent of the resorptions increased, 6.5 per cent of the resorptions decreased and 16.1 per cent of the root resorbed incisors were extracted at T2. All extracted teeth were diagnosed having severe root resorption. In summery, the present results showed that; (1) about 50 per cent of the incisor root resorptions arrested in the long-term, (2) about 20 per cent of the resorptions increased, (3) decrease of the resorptions were rare and (4) the incisors with severe resorptions immediately after the correction of the impacted canines had a bad long-term prognosis if combined with eg. trauma or periodontitis.

X-ray computed tomography (CT) holds a critical role in current medical practice for the evaluation of patients, particularly in the emergency department and intensive care units. Expensive high resolution stationary scanners are available in radiology departments of most hospitals. In many situations however, a small, inexpensive, portable CT unit would be of significant value. Several mobile or miniature CT scanners are available, but none of these systems have the range, flexibility or overall physical characteristics of a truly portable device. The main challenge is the design of a geometry that optimally trades image quality for system size. The goal of this work has been to develop analysis tools to help simulate and evaluate novel system geometries. To test the tools we have developed, three geometries have been considered in the thesis, namely, parallel projections, clam-shell and parallel plate geometries. The parallel projections geometry is commonly used in reconstruction of images by filtered back projection technique. A clam-shell structure consists of two semi-cylindrical braces that fold together over the patient's body and connect at the top. A parallel plate structure uses two fixed flat or curved plates on either side of the patient's body and image from fixed sources/detectors that are gated on and off so as to step the X-ray field through the body. The parallel plate geometry has been found to be the least reliable of the three geometries investigated, with the parallel projections geometry being the most reliable. For the targeted application, the clam-shell geometry seems to be the solution with more chances to succeed in the short term. We implemented the Van Cittert iterative technique for the reconstruction of images from projections. The thesis discusses a number of variations on the algorithm, such as the use of the Conjugate Gradient Method, several choices for the initial guess, and the incorporation of a priori information to handle the reconstruction of images with metal inserts.

Computed tomography urography (CTU) is today the imaging method used to investigate patients with suspected urinary tract malignancy, replacing the old imaging method intravenous pyelography (IVP) about a decade ago. The downside of this shift was that the effective radiation dose to the examined patient was eight times higher for CTU compared to IVP. Based on four different studies, the present thesis focused on efforts to reduce the CTU radiation dose.   In study I, the number of cysts and solid lesions in the separate scan phases was evaluated in 57 patients undergoing four-phase CTU 1997-98. The number of scans was reduced from four to three when the nephrographic scan was abolished following study I. Study II registered the diameter of renal cell carcinoma (RCC) and the presenting symptoms in the total number of patients (n=232) diagnosed with RCC between 1997 and 2003. The results from study II showed that the critical size for RCCs to cause macroscopic hematuria was ≥ 4 cm. Study III was a dose-escalation study aimed to decide the minimal possible tube load in the unenhanced and excretory phase scans if the low dose images are reviewed together with normal dose corticomedullary phase images. Study III showed that it is possible to reduce the mean effective dose in three phase CTU from 16.2 mSv to 9.4 mSv with a combined low and normal dose CTU protocol. Study IV investigated the changes in the CTU protocol between 1997 and 2008, and the development of the effective radiation dose. Study IV clarified how the CTU protocol has changed between 1997 and 2008 and as a result the mean effective radiation dose to patients undergoing CTU in 2008 is only 39% of the effective dose in 1997.   In conclusion, the findings from the studies included in this thesis have contributed to a reduced radiation dose to patients undergoing CTU. The mean effective dose from CTU is at present only three times higher compared to that from the IVP.

Introdução: Pacientes com cardiopatia congênita submetidos ao procedimento de Fontan (PF) vêm atingindo a idade adulta com significativas consequências sistêmicas, particularmente hepáticas. Tais injúrias hepáticas podem resultar em fibrose, cirrose e nódulos hepáticos (NH), que podem ser benignos ou malignos. Porém, não há, até o momento, consenso na literatura quanto ao rastreamento desses nódulos, sobretudo acerca do início e da melhor modalidade para tal fim. Objetivo: Esse estudo objetivou (a) avaliar a frequência de NH em pacientes submetidos ao PF na ultrassonografia (USG), tomografia computadorizada (TC) e ressonância magnética (RM), assim como a concordância entre tais métodos; (b) investigar se há correlação entre a presença de NH e algumas variáveis clínicas e laboratoriais; (c) analisar se há diferença nos valores de rigidez hepática utilizando a elastografia por USG por meio da técnica acoustic radiation force impulse (ARFI) entre os pacientes com e sem NH. Métodos: Foram recrutados, prospectivamente, 49 pacientes submetidos ao PF entre agosto de 2014 e junho de 2016. Esses pacientes foram submetidos a rastreamento clínico e laboratorial de hepatopatia, e elastografia hepática por USG com ARFI, TC e RM. A concordância entre os testes foi acessada utilizando o kappa de Cohen. A correlação entre NH com as outras variáveis foi realizada com teste t de Student ou teste de Mann-Whitney para variáveis contínuas sem distribuição normal e teste qui-quadrado ou teste de Fisher para variáveis categóricas. Resultados: NH foram detectados em 3/49 (6%), 14/44 (31,8%) e 19/48 (39,6%) pacientes na USG, TC e RM, respectivamente. Houve uma concordância quase perfeita entre TC e RM na detecção de NH (kappa: 0,849, p < 0,001), porém a USG não demonstrou concordância com TC e RM (kappa: 0,006, p=0,095 e kappa: 0,083, p = 0,032, respectivamente). Nenhuma variável clínica ou laboratorial apresentou correlação significativa com a presença de NH, inclusive o tempo após o PF. Os valores de rigidez hepática no ARFI foram significativamente mais elevados nos pacientes com NH (2,64 ± 0,81 m/s vs. 1,94 ± 0,49 m/s; p=0,002) e foram um preditor significativo para NH (AUC: 0,767, p=0,002). Conclusão: Na nossa população, mais de um terço dos pacientes após o PF apresentou NH na TC ou RM, mas a USG não detectou a grande maioria dos nódulos. Nenhum dado clínico ou laboratorial apresentou correlação significativa com a presença de NH. A rigidez hepática no ARFI foi significativamente mais elevada nos pacientes com NH. Tais achados sugerem que a USG não é um método diagnóstico efetivo no rastreamento de NH, porém a elastografia por ARFI pode ser útil, orientando quais pacientes devem submetidos à TC ou RM / Background: Patients with congenital heart disease after Fontan procedure (FP) are reaching the adulthood with significant systemic consequences, particularly to the liver. Those hepatic injuries can cause liver fibrosis, cirrhosis and hepatic nodules (HN), which can be benign or malignant. Currently, there is no consensus in the literature regarding screening of HN in patients after FP concerning when to start and which is the best imaging modality indicated for it. Purpose: This study aimed (a) to evaluate the frequency of HN in patients after FP on ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI), as well as their inter-test agreement; (b) to investigate if there is any correlation between presence of HN and clinical or laboratorial variables; (c) to analyze if liver stiffness (LS) values using acoustic radiation force impulse (ARFI) on US elastography differ between patients with and without HN. Methods: We prospectively recruited 49 patients after FP from August 2014 to June 2016. These patients underwent clinical and laboratorial screening of hepatic disorders, ARFI elastography of the liver, abdominal US, CT and MRI. Intertest agreement was assessed by using weighted Cohen\'s kappa as statistics. The dependence of HN with the variables was performed using Student\'s t test or ANOVA for independent continuous variables without normal distribution; and chi-square test or Fisher\'s test for categorical variables. Results: HN were detected in 3/49 (6%), 14/44 (31.8%), and 19/48 (39.6%) patients on US, CT and MRI, respectively. There was an almost perfect agreement between CT and MRI in detecting HN (kappa: 0.849, p < 0.001); however, US had a non-significant correlation with CT and MRI (kappa: 0.006, p=0.095 and kappa: 0.083, p = 0.032, respectively). No clinical or laboratorial data had any significant correlation with the presence of HN, including time since FP. LS on ARFI was significantly higher in patients with HN (2.64 ± 0.81 m/s vs. 1.94 ± 0.49 m/s; p=0.002) and was a significant predictor of HN (AUC 0.767, p=0.002). Conclusion: In our study, more than one-third of patients after FP had HN on CT or MRI, but US did not detect the vast majority of them. No clinical or laboratorial data had any significant correlation with the presence of HN. LS on ARFI was significantly higher in patients with HN. These findings may suggest that US is not an effective imaging modality for screening of HN; however, ARFI elastography may help guiding which patients should be further imaged with CT or MRI

INTRODUÇÃO: Micose sistêmica mais importante da América do Sul e do Brasil, a Paracoccidioidomicose acomete difusamente os pulmões no seu principal modo de apresentação, a forma crônica. Os pacientes podem apresentar anormalidades respiratórias com repercussão clínica e na qualidade de vida relacionada à saúde mesmo após tratamento antifúngico adequado. Não há, todavia, estudos que avaliem as alterações pulmonares radiológicas e funcionais e sua real incidência e repercussão clínica e na qualidade de vida desses pacientes após o tratamento. MÉTODOS: Análise transversal de 50 pacientes através de tomografia computadorizada de tórax, prova de função pulmonar completa, teste cardiopulmonar de esforço, teste de caminhada de seis minutos (TC6M) e questionário de qualidade de vida relacionada à saúde e de índice de dispneia. Todos tiveram diagnóstico da forma crônica da paracoccidioidomicose e foram avaliados quando atingiram critérios de inatividade de doença. RESULTADOS: Os pacientes apresentaram anormalidades tomográficas em 98% dos casos, sendo distorção da arquitetura (90%), reticulado (88%), enfisema centrolobular e parasseptal (84%) e bandas parenquimatosas (74%) as mais frequentes. Os achados foram principalmente difusos, e foi predominante a combinação das localizações central e periférica (80%). Do ponto de vista funcional, apresentaram, em média, distúrbio obstrutivo leve sem resposta ao broncodilatador, com redução leve da difusão do CO. Ao teste de esforço cardiopulmonar, atingiram média de VO2 máx dentro da normalidade, e à caminhada de seis minutos atingiram distância média dentro da normalidade. O questionário de qualidade de vida relacionado à saúde mostrou um impacto baixo na qualidade de vida, e o índice de dispneia mostrou alteração leve (MRC 1). Quando divididos em dois grupos em relação à dessaturação no TC6M, o grupo mais grave apresentou valor de CIE inicial mais alto e mais enfisema na TCAR, porém não houve diferença na exposição tabágica, no número de alterações tomográficas cicatriciais encontradas, na capacidade aeróbica medida pelo TCPE e TC6M e tampouco no questionário de qualidade de vida relacionada à saúde ou índice de dispneia. CONCLUSÃO: Na forma crônica da paracoccidioidomicose, após tratamento antifúngico e atingidos critérios de inatividade de doença, os pacientes apresentam anormalidades tomográficas persistentes e disseminadas, porém sem determinar um comprometimento grave na função pulmonar, capacidade aeróbica ou qualidade de vida relacionada à saúde. Todavia, uma parcela da população tem acometimento funcional mais grave, com maior alteração da troca gasosa levando a maior dessaturação ao exercício. Ao ser estudado distintamente, esse grupo de indivíduos não se diferencia do restante em termos de exposição tabágica, capacidade aeróbica, impacto na qualidade de vida relacionada à saúde e índice de dispneia ou número de alterações radiológicas intersticiais cicatriciais encontradas na tomografia computadorizada de tórax, porém apresenta sorologia inicial (CIE) mais alta e enfisema mais proeminente na TCAR / BACKGROUND: Paracoccidioidomycosis (PCM), the most important systemic mycosis in Latin America and Brazil, can diffusely affect the lungs in its mains form of presentation, the chronic form. Even after adequate antifungal therapy, the patients may present residual respiratory abnormalities with potential clinical, functional and health-related quality of life impairment, due to fungus-induced lung fibrosis. METHODS: Cross-sectional analysis of 50 consecutive inactive chronic Paracoccidioidomycosis patients, through high resolution computed tomography (HRCT) reviewed by a chest radiologist and a pulmonologist, pulmonary function tests with diffusion capacity, ergoespirometry, six minute walk test (6MWT) and health-related quality of life questionnaire. All patients had achieved inactivity criteria when evaluation was performed. RESULTS: Radiological abnormalities were present in 98% of the cases, and the most frequent were architectural distortion (90%), reticulate and septum thickening (88%), centrolobular and parasseptal emphysema (84%) and parenchymal bands (74%). The findings were mainly diffuse, and predominantly with a combination of central and peripheral locations (80%). From the functional standpoint the patients presented, in average, a mild obstructive disorder without bronchodilator response, associated to a mild reduction in diffusion capacity. The ergoespirometry demonstrated a mean VO2 máx in the range of normality, and the patients achieved a mean normal distance in the 6MWT. The Saint-George Respiratory Questionnaire evaluation showed a low total impairment in health-related quality of life and the MRC questionnaire a low dyspnae index. When split in two groups in terms of exercise desaturation in the 6MWT, the more severely impaired group presented a higher initial serology (CIE) and more severe emphysema graded by HRCT, but there was no difference between the two groups in regards to interstitial fibrotic tomographic abnormalities, tobacco exposure, exercise capacity measured by ergoespirometry and 6MWT, nor in the health related quality of life and dyspnae index. CONCLUSIONS: In the chronic form of Paracoccidioidomycosis, after antifungal treatment, the patients show persistent and disseminated radiological abnormalities, but these findings appear to determine a short impairment in pulmonary function and low impact in aerobic capacity and health-related quality of life. However, in a minor subset of individuals the functional impairment can be severe. When this group is distinctly studied, the individuals present no difference in tobacco exposure, interstitial fibrotic radiological findings, exercise capacity nor health related quality of life and dyspnae index when compared to less severely afflicted patients, but do so in terms of higher initial serology (CIE) and severity of emphysema quantification by HRCT

INTRODUÇÃO: Micose sistêmica mais importante da América do Sul e do Brasil, a Paracoccidioidomicose acomete difusamente os pulmões no seu principal modo de apresentação, a forma crônica. Os pacientes podem apresentar anormalidades respiratórias com repercussão clínica e na qualidade de vida relacionada à saúde mesmo após tratamento antifúngico adequado. Não há, todavia, estudos que avaliem as alterações pulmonares radiológicas e funcionais e sua real incidência e repercussão clínica e na qualidade de vida desses pacientes após o tratamento. MÉTODOS: Análise transversal de 50 pacientes através de tomografia computadorizada de tórax, prova de função pulmonar completa, teste cardiopulmonar de esforço, teste de caminhada de seis minutos (TC6M) e questionário de qualidade de vida relacionada à saúde e de índice de dispneia. Todos tiveram diagnóstico da forma crônica da paracoccidioidomicose e foram avaliados quando atingiram critérios de inatividade de doença. RESULTADOS: Os pacientes apresentaram anormalidades tomográficas em 98% dos casos, sendo distorção da arquitetura (90%), reticulado (88%), enfisema centrolobular e parasseptal (84%) e bandas parenquimatosas (74%) as mais frequentes. Os achados foram principalmente difusos, e foi predominante a combinação das localizações central e periférica (80%). Do ponto de vista funcional, apresentaram, em média, distúrbio obstrutivo leve sem resposta ao broncodilatador, com redução leve da difusão do CO. Ao teste de esforço cardiopulmonar, atingiram média de VO2 máx dentro da normalidade, e à caminhada de seis minutos atingiram distância média dentro da normalidade. O questionário de qualidade de vida relacionado à saúde mostrou um impacto baixo na qualidade de vida, e o índice de dispneia mostrou alteração leve (MRC 1). Quando divididos em dois grupos em relação à dessaturação no TC6M, o grupo mais grave apresentou valor de CIE inicial mais alto e mais enfisema na TCAR, porém não houve diferença na exposição tabágica, no número de alterações tomográficas cicatriciais encontradas, na capacidade aeróbica medida pelo TCPE e TC6M e tampouco no questionário de qualidade de vida relacionada à saúde ou índice de dispneia. CONCLUSÃO: Na forma crônica da paracoccidioidomicose, após tratamento antifúngico e atingidos critérios de inatividade de doença, os pacientes apresentam anormalidades tomográficas persistentes e disseminadas, porém sem determinar um comprometimento grave na função pulmonar, capacidade aeróbica ou qualidade de vida relacionada à saúde. Todavia, uma parcela da população tem acometimento funcional mais grave, com maior alteração da troca gasosa levando a maior dessaturação ao exercício. Ao ser estudado distintamente, esse grupo de indivíduos não se diferencia do restante em termos de exposição tabágica, capacidade aeróbica, impacto na qualidade de vida relacionada à saúde e índice de dispneia ou número de alterações radiológicas intersticiais cicatriciais encontradas na tomografia computadorizada de tórax, porém apresenta sorologia inicial (CIE) mais alta e enfisema mais proeminente na TCAR / BACKGROUND: Paracoccidioidomycosis (PCM), the most important systemic mycosis in Latin America and Brazil, can diffusely affect the lungs in its mains form of presentation, the chronic form. Even after adequate antifungal therapy, the patients may present residual respiratory abnormalities with potential clinical, functional and health-related quality of life impairment, due to fungus-induced lung fibrosis. METHODS: Cross-sectional analysis of 50 consecutive inactive chronic Paracoccidioidomycosis patients, through high resolution computed tomography (HRCT) reviewed by a chest radiologist and a pulmonologist, pulmonary function tests with diffusion capacity, ergoespirometry, six minute walk test (6MWT) and health-related quality of life questionnaire. All patients had achieved inactivity criteria when evaluation was performed. RESULTS: Radiological abnormalities were present in 98% of the cases, and the most frequent were architectural distortion (90%), reticulate and septum thickening (88%), centrolobular and parasseptal emphysema (84%) and parenchymal bands (74%). The findings were mainly diffuse, and predominantly with a combination of central and peripheral locations (80%). From the functional standpoint the patients presented, in average, a mild obstructive disorder without bronchodilator response, associated to a mild reduction in diffusion capacity. The ergoespirometry demonstrated a mean VO2 máx in the range of normality, and the patients achieved a mean normal distance in the 6MWT. The Saint-George Respiratory Questionnaire evaluation showed a low total impairment in health-related quality of life and the MRC questionnaire a low dyspnae index. When split in two groups in terms of exercise desaturation in the 6MWT, the more severely impaired group presented a higher initial serology (CIE) and more severe emphysema graded by HRCT, but there was no difference between the two groups in regards to interstitial fibrotic tomographic abnormalities, tobacco exposure, exercise capacity measured by ergoespirometry and 6MWT, nor in the health related quality of life and dyspnae index. CONCLUSIONS: In the chronic form of Paracoccidioidomycosis, after antifungal treatment, the patients show persistent and disseminated radiological abnormalities, but these findings appear to determine a short impairment in pulmonary function and low impact in aerobic capacity and health-related quality of life. However, in a minor subset of individuals the functional impairment can be severe. When this group is distinctly studied, the individuals present no difference in tobacco exposure, interstitial fibrotic radiological findings, exercise capacity nor health related quality of life and dyspnae index when compared to less severely afflicted patients, but do so in terms of higher initial serology (CIE) and severity of emphysema quantification by HRCT

<p>Kompjuterizovana tomografija (CT) je u poslednje vreme ušla na velika vrata sa razvojem industrijskih CT sistema, usled njene primene u različitim oblastima, a uveliko ulazi i u polje koodinatne metrologije. Zbog karakterizacije objekata sačinjenih od različitih materijala (najčešće metala i plastike), javljaju se određeni problem u vidu nastanka artefakata kod rezultata dimenzionalnih merenja. Istraživanja koja su sprovedena u ovoj doktorskoj disertaciji se bave problemom redukcije uticaja tih artefakata i segmentacije 2D snimaka. Razvijen je novi model koji je baziran na primeni hibridne metode gde je izvršena kombinacija dve metode za obradu slike, a to su fazi klasterizacija i rast regiona. Aksenat je stavljen na primeni ove hibridne metode radi dobijanja tačnijih rezultata segmentacije, što direktno utiče i na rekonstrukciju dimenzionalno tačnijih 3D modela.</p> / <p>Computed tomography (CT) has recently entered a large door with the development of industrial CT systems, due to its application in many different areas, and it is already entering the field of coordinate metrology. Due to its ability to non-destructively characterize objects made of different materials (typicaly metals and plastics), a certain problem arises in the form of artefacts that are present in the results. Research carried out in this dissertation deals with the problem of reducing the impact of these artefacts and the 2D image segmentation. A new model was developed based on the application of the hybrid method where a combination of two methods for image processing was performed, which are fuzzy clustering and region growing. The accent is emphasized in the application of this hybrid method in order to obtain more accurate segmentation results, which directly affects the reconstruction of dimensionally more accurate 3D models.</p>

Moisture damage in asphalt mixes refers to the loss of serviceability due to the presence of moisture. The extent of moisture damage, also called moisture susceptibility, depends on internal and external factors. The internal factors relate to the properties of the materials and the microstructure distribution, while the external factors include the environmental conditions, production and construction practices, pavement design, and traffic level. The majority of the research on moisture damage is based on the hypothesis that infiltration of surface water is the main source of moisture. Of the two other principal mechanisms of water transport, permeation of water vapor and capillary rise of subsurface water, the latter has been least explored. A laboratory test and analysis methods based on X-ray computed tomography (CT) were established to assess the capillary rise of water. The amount and size of air voids filled with water were used in the capillary rise equation to estimate the distribution of the contact angles between the water and the mastic. The results were able to show the influence of air void size on capillary rise and contact angles. The relationship between air void structure and moisture susceptibility was evaluated using a fundamental fracture model based on dissipated energy of viscoelastic materials. Detailed description is provided in this dissertation on the deduction of the model equation, the selection of the model parameters, and the required testing protocols. The model parameters were obtained using mechanical tests and surface energy measurements. The microstructure of asphalt mixes prepared in the laboratory having different air void structures was captured using X-ray CT, and image analysis techniques were used to quantify the air void structure and air void connectivity. The air void structure was found to influence the mix resistance to moisture damage. To validate the fracture model, asphalt mixes with known field performance were tested. The results demonstrated that the fracture model is an effective tool to characterize moisture susceptibility. In addition, the model showed good correlation with the reported field performance of the asphalt mixes. The findings of this study will be useful to highway engineers to evaluate asphalt mixes with alternative mix designs and internal air void structures and to estimate the rate of moisture infiltration in order to maximize the resistance of asphalt mixes to moisture damage.

81f. / Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2013-04-23T16:52:09Z No. of bitstreams: 1 Dissertacao - Eduardo Gomes Ferraz.pdf: 6518404 bytes, checksum: 23aa21cb9faeb4f359532b341d12f69c (MD5) / Approved for entry into archive by Rodrigo Meirelles(rodrigomei@ufba.br) on 2013-05-08T12:05:54Z (GMT) No. of bitstreams: 1 Dissertacao - Eduardo Gomes Ferraz.pdf: 6518404 bytes, checksum: 23aa21cb9faeb4f359532b341d12f69c (MD5) / Made available in DSpace on 2013-05-08T12:05:55Z (GMT). No. of bitstreams: 1 Dissertacao - Eduardo Gomes Ferraz.pdf: 6518404 bytes, checksum: 23aa21cb9faeb4f359532b341d12f69c (MD5) Previous issue date: 2009 / O presente estudo teve como objetivo avaliar a acurácia de reconstruções tridimensionais virtuais de mandíbulas secas humanas, produzidas com diferentes protocolos de segmentação, suavização e refinamento superficial. Para isto foram construídas 80 imagens tridimensionais virtuais, provenientes do exame de tomografia computadorizada de dez mandíbulas secas, nas quais medidas lineares entre pontos anatômicos pré-determinados foram obtidas e comparadas, para uma probabilidade de erro de 5%. Os resultados obtidos demonstraram diferença significativa entre as medidas obtidas nas mandíbulas originais (padrão ouro) quando comparadas com as imagens confeccionadas a partir da segmentação outline (p<0,05) e all boundary (p<0,001) sem as ferramentas de suavização ou refinamento. Já após a utilização das diferentes formas de segmentação associadas às ferramentas de pós-processamento (suavização e refinamento), não houve diferença entre as medidas dos modelos apenas refinados ou apenas suavizados (p>0,05) com as do padrão ouro. Quando estas duas ferramentas foram aplicadas em conjunto, houve diferença estatística, quando comparadas ao padrão ouro, tanto para a segmentação outline (p<0,001), quanto para a all boundary (p<0,001). Foi avaliado também o erro dimensional dos modelos tridimensionais virtuais obtidos pelos diferentes protocolos utilizados no estudo. Esta análise demonstrou que os melhores resultados ocorreram nos modelos apenas suavizados pela segmentação outline (erro de 2,50 mm /6,52%) e os apenas refinados pela segmentação all boundary (erro de 2,37 mm /6,28%), enquanto que as maiores diferenças foram observadas nos modelos construídos sem pós-processamento, com a segmentação outline (erro de 2,50 mm /7,17%) e naqueles com as duas ferramentas de pósprocessamento a partir da segmentação all boundary (erro de 2,85 mm /7,12%). Avaliada ainda a variabilidade intra e inter-examinador constatou-se uma concordância extremamente forte em ambos os casos (p<0,05), o que demonstra a reprodutibilidade do método. / Salvador

The overall accuracy, efficiency and profitability of livestock improvement strategies can be greatly increased by incorporating quantitative genetics into livestock selection and breeding. Since the introduction of quantitative genetics, a range of traits describing the animal e.g. in terms of health, growth, fecundity, production, have been extensively evaluated in terms of genetics and are now commonly manipulated through breeding to achieve specific selection goals. An industry led enquiry as to the possibility of including spine traits in genetic selection to increase back length in sheep was the basis of the present thesis. Collecting information on spine traits (spine length, vertebrae length and vertebrae number) is of particular interest and use to the sheep breeding industry as there may be the potential to increase meat yield from the highly valuable longissimus thoracis et lumborum (LTL or loin), located parallel to the spine, with little associated change in production costs. The thesis focusses on the use of X-ray computed tomography (CT) scanning as a technique which would allow spine traits to be measured in vivo, hence being useful for genetic selection. The topogram scans produced from the CT scanning procedure were analysed to derive spine trait information for the thesis. The scans were from Scottish Blackface (maternal breed stock), Texel (terminal sire breed), Texel cross Mule and Poll Dorset cross Mule (three-way cross slaughter lambs) so as to represent the divergent genotypes found across the different levels of the United Kingdom’s (UK) three-tier crossbreeding structure of sheep. The present study explored as a first step intra- and inter-operator repeatability of assessment of spine traits from CT derived topograms, as a means to investigate the suitability of the approach for widespread uptake within industry where operators will vary. The results showed that there was high repeatability for intra- and inter-operator assessment of spine trait measurements verifying that the CT method could be accepted as a reliable alternative (to slaughter for example) to quantify spine traits. To determine whether spine traits are similar across the range of breeds representing the key genotypes and crosses in the UK sheep industry, numerous CT topograms were analysed. The results showed marked variation in spine traits within and between Scottish Blackface, Texel, Texel cross Mule and Poll Dorset cross Mule breeds and crosses. For example, the Texel breed was found to have the largest within-breed range for thoracolumbar vertebrae number (17 – 21; the majority possessing 19), but the spine length of these animals was, on average, significantly shorter than the other breed/cross groups. The present study concluded that the significant differences between the breeds and breed types for the particular spine traits were possibly indicative of a genetic control for these traits. Furthermore, investigation into the phenotypic correlations between spine and production traits revealed some directional associations which may prove beneficial for meat production. For example, Scottish Blackface lambs which had a longer length of a specific spine region had an associated decrease in the volume of carcass fat. Texel lambs which had a longer length of a specific spine region had a slightly larger loin muscle area, at a given weight. The present study also examined animals from a population of Texel lambs already heavily selected for increased muscling. The Texel muscling quantitative trait locus (TM-QTL), segregating in these animals and generally in the UK’s Texel sheep population, is expressed through a polar overdominance pattern of inheritance and its effect on the loin (localised muscle hypertrophy) is commonly utilised in the selection and breeding of Texel sheep to improve meat production. Examination of topograms from lambs bearing the whole range of TM-QTL genotypes showed little evidence to suggest that the change in loin shape/increased loin muscling, as a result of the TM-QTL and its inheritance, has led to any associated change in the underlying spine characteristics. This suggests that selection for increased muscling associated with the TM-QTL may be achieved independently of changes in the spine traits studied. The potential to breed for certain spine traits to increase vertebrae number and hence chops or loin yield can be enhanced by establishing the genetic parameters for the traits. The present study employed a collection of performance trait records from Texel lambs to provide the basis for genetic analysis. The results showed different levels of heritability for the different spine traits but also high standard errors. For example, heritability of vertebrae number was dependent on vertebra location: for thoracic vertebrae heritability was high (ℎ2 = 0.99; SE = 0.42), for lumbar vertebrae heritability was low (ℎ2 = 0.08; SE = 0.12), whereas in contrast, thoracolumbar vertebrae heritability was moderate (ℎ2 = 0.44; SE = 0.27). Phenotypic and genetic correlations between all combinations of traits were also obtained. Accurate predictions of the size and direction of response to selection can be achieved through such genetic analysis of traits. The more that is known of the genetic characteristics of traits and their genetic correlations with other economically important traits, the more efficiently it can be built into breeding programmes improving the overall performance of stock. The results of this study showed that providing spine measurements can contribute to the diversity of trait information available to breeders. The present study also suggests that there may be opportunities to select for increased spine length/vertebrae number which would benefit the sheep industry in terms of increased chop number/loin yield. Although more data are needed prior to implementation. Practical uptake of selection for spine traits would be enhanced due to the straightforward nature of the measurements and the high operator repeatability.