L'ordre des rongeurs (Rodentia) est le groupe de mammifères le plus riche en espèces, les muroïdes étant la superfamille la plus diversifiée. Comme ils occupent des niches écologiques arboricoles, semi-aquatiques, souterraines et terrestres, les rongeurs peuvent présenter des traits morphologiques reflétant leurs adaptations à des environnements aussi divers. Cette thèse porte sur la morphologie de l'endocrâne, de la bulle auditive et de la cochlée dans trois tribus (Otomyini, Taterillini et Gerbillini) représentant 10 espèces de rongeurs africains, en se concentrant sur la variabilité de ces traits, leur fonction et leur adaptabilité, à l'aide d'imagerie par micro-scanner et de méthodes de comparaison de formes tridimensionnelles. De plus, les variations de la taille du crâne ont également été étudiées en fonction du réchauffement climatique et des variables climatiques. Les changements / variations morphologiques sont liées à des différences environnementales. Par conséquent, chaque chapitre de cette étude détaille l'effet des changements environnementaux (dans l'espace et dans le temps) sur différents traits morphologiques, c'est-à-dire la taille générale du crâne (chapitre 2), la cochlée et les bulles auditives (chapitre 3), et la taille et la forme endocrânienne (chapitre 4). Le chapitre 2 traite spécifiquement du changement climatique au sens strict et les deux autres chapitres traitent de différents gradients environnementaux. Le chapitre 2 teste l'applicabilité de la "troisième réponse universelle au réchauffement" (c'est-à-dire de la diminution de la taille corporelle) et de la "règle des ressource" dans deux sous-familles de muridés, Murinae et Gerbillinae. L'étude montre que la troisième réponse n'est pas universelle puisqu'une seule espèce s'est conformée à ce type de réponse. De plus, il a été démontré que la disponibilité de nourriture (règle des ressources) était un facteur plus important que la règle de Bergmann pour expliquer les corrélations entre variations de l'environnement et celles de la taille des espèces de rongeurs.[...] / The order Rodentia is the most speciose group of mammals with muroids being the most diverse superfamily. Since they are represented in arboreal, semiaquatic, subterranean and terrestrial niches, rodents may exhibit morphological traits reflecting their adaptations to such diverse environments. This thesis focuses on the morphology of the endocranium, auditory bulla and cochlea in three tribes (Otomyini, Taterillini and Gerbillini) representing 10 species of African rodents, concentrating on their variability, function and adaptability, using micro-CT imaging and 3D shape comparative methods. Additionally, variations in cranial size were also studied in respective of global warming and climatic variables. Morphological changes/variations are a result of environmental change, therefore each chapter in this study details the effect of environmental change (in space and time) on different morphological traits i.e. general cranial size (chapter 2), cochlea and auditory bulla (chapter 3) and endocranial size and shape (chapter 4). With chapter 2 dealing specifically with climate change in its straict sense and the remaining two chapters looking at different environmental gradients. Chapter 2 tests the applicability of the "third universal response to warming" (i.e. declining body size) and the Resource Rule in two murid subfamilies, Murinae and Gerbillinae. The study shows that the third response is not as universal as only one species conformed to this response. Further, food availability (Resource Rule) was shown to be the more important factor correlated with body size variations in rodent species than Bergmann's Rule. [...]

Este estudo translacional avaliou o efeito da aplicação direta de materiais capeadores à base de óleo de copaíba sobre a polpa dentária de ratos. O biomaterial foi analisado de acordo com os processos inflamatórios, reparadores e regenerativos. Cavidades classe I foram preparadas na face oclusal dos molares superiores e inferiores de ratos da linhagem Wistar (n=120). Posteriormente, uma cavidade padronizada foi realizada com broca carbide esférica ¼. Exposições pulpares foram obtidas e após a hemostasia com algodão estéril e água destilada, foi realizado o capeamento pulpar com aplicação de biomateriais diretamente no tecido pulpar. Os biomateriais utilizados foram: COP (Óleo de Copaíba); Ca(OH)2 (hidróxido de cálcio), Ca(OH)2+COP; MTA (agregado trióxido mineral); MTA+COP; BIODENTINA (Biodentine®); BIODENTINA+COP. Todas as cavidades foram restauradas com cimento provisório. Os animais foram sacrificados após o período de 7, 14, 28 dias de acordo com os princípios de ética e experimentação animal. Vinte e um grupos foram criados a partir da combinação de tempos e materiais, cada grupo foi constituído de 5 animais. As peças foram preparadas e processadas pela técnica histológica e coradas pela HE (hemotoxilina e eosina) realizando cortes aleatórios, sendo analisados ao microscópio óptico em 100X de aumento por 2 examinadores. Os critérios avaliados foram: respostas inflamatória e degenerativa, organização tecidual, dentina reacional e reparativa. No último tempo experimental (28 dias) de todos os grupos foi analisado a superfície (mm2) e o volume (mm3) da ponte de dentina formada pela técnica da micro-CT (microtomografia computadorizada) de alta resolução. Os dados foram estatisticamente analisados utilizando o teste T pareado, determinando a superfície e volume da dentina reparadora formada entre os grupos experimentais. Nas análises histológicas foi utilizado o teste não-paramétrico de Mann-Whitney realizando comparações entre os grupos (?=5%). A BIODENTINA demonstrou uma tendência de acelerar o processo de regeneração pulpar, iniciando a deposição de dentina reparativa ao sétimo dia do capeamento. Este material apresentou uma dentina mais espessa em comparação com os outros biomateriais. O MTA também demonstrou uma eficiência na formação da ponte dentinária, entretanto em 20% das amostras não foi observada a presença de dentina reparadora. Ao acrescentar o COP nestes materiais, a formação da ponte dentinária apresentava heterogênea e incompleta, além disso esses grupos continham um processo inflamatório aumentado. A dentina reparadora do grupo de Ca(OH)2 demonstrou presença de túnel, com característica heterogênea. A adição do COP ao Ca(OH)2 aumentou a formação de dentina nas paredes ao redor da câmara pulpar em 80% das amostras, porém esta dentina não apresentava melhora na qualidade. Desta forma, o capeamento pulpar com COP isolado ou associado a Ca(OH)2, MTA e BIODENTINA não formou uma ponte de dentina completa e homogênea no local da exposição pulpar. / This translational study evaluated the effect of the direct application of copaiba oil based capping materials on the rat pulp. The biomaterial was analyzed according to inflammatory, repairing and regenerative processes. Class I cavities were prepared on the occlusal surface of the upper and lower molars of Wistar rats (n = 120). Subsequently, standardized cavities was performed with ¼ spherical carbide drill. Pulp exposures were obtained and after their hemostasis with sterile cotton and distilled water, pulp capping was done with application of biomaterials directly on the pulp tissue. The biomaterials used were: COP (Copaíba oil); Ca(OH)2 (calcium hydroxide), Ca(OH)2+COP; MTA (aggregate mineral trioxide); MTA+COP; BIODENTINE (Biodentine®); BIODENTINA+COP. All cavities were restored with temporary cement. The animals were sacrificed after the period of 7, 14, 28 days according to the principles of ethics and animal experimentation. Twenty-one groups were created from the combination of times and materials, each group consisted of 5 animals. The specimens were prepared and processed by histological technique and stained by HE (haemotoxin and eosin); randomized cuts were examined under optical microscope with 100X enlargement by two different examiners. The evaluated criteria were inflammatory and degenerative response, tissue organization, reactive and reparative dentin. In the last experimental period (28 days) of all groups, the surface (mm2) and the volume (mm3) of the reactive and reparative dentin formed were analyzed by the high-resolution micro-CT (computerized microtomography) technique. The data were statistically analyzed using the paired T-test, determining the surface and volume of the reparative dentin formed between the experimental groups. In the histological analyzes, the non-parametric Mann-Whitney test was used, comparing groups (? = 5%). BIODENTINE demonstrated a tendency to accelerate the process of pulpal regeneration, initiating the deposition of reparative dentin on the seventh day of the capping. This material had a thicker dentin compared to the other biomaterials. The MTA also demonstrated an efficiency in the formation of the dentin bridge; however, 20% of the samples did not observe the presence of reparative dentin. When adding the COP in these materials, the formation of the dentin bridge was heterogeneous and incomplete, in addition these groups contained an increased inflammatory process. The repair dentin of the Ca(OH)2 group showed a tunnel with a heterogeneous characteristic. The addition of COP to Ca(OH)2 increased dentin formation in the walls around the pulp chamber in 80% of the samples, but this dentin did not show improvement in quality. Thus, pulp cap with COP isolated or associated with Ca(OH)2, MTA and BIODENTINE did not form a complete and homogeneous dentin bridge at the site of pulp exposure.

The aim of this study was to evaluate the efficacy of heat-treated nickel-titanium reciprocating instruments and complementary techniques in retreatment of flattened canals. Material and methods: Twenty-six mandibular incisors were prepared up to size 25/.08 rotary file and filled using the single-cone technique. Subsequently, the teeth were divided into 3 groups (n=12) according to retreatment procedures: Reciproc Blue: R25 and R40; ProDesign R: PDR 25/.06 and PDR 35/.05; WaveOne Gold: WOG Primary and WOG Medium. The apically extruded material was collected in microtubes and the volume (mm³) was measured by Micro-CT. After this, the specimens received complementary cleaning with XP-Endo Shaper, PUI and 60° oscillatory instrumentation with #30 Hedströem file. Micro-CT scans were performed before and after removing filling material. After quantification of the volume of remaining filling material, the teeth were sectioned and scanning electron microscopy (SEM) images of the cervical, middle and apical thirds were obtained with a 700X magnification, and evaluated by scores based on the amount of filling material in the surface of dentine walls. Results: No reciprocating instrument promoted complete removal of filling material. All systems showed extrusion, however, WOG25 presented the higher extrusion of material (P<.05). XP-Endo Shaper significantly reduced the amount of filling material in the apical and middle thirds (P<.05). In the SEM analysis, there was no statistical difference among the cleaning methods (P> .05). Conclusions: The reciprocating instruments studied did not promote complete removal of root canal filling materials. XP-Endo Shaper, used as a complementary instrument in retreatment, improved removal of filling material. / O objetivo deste estudo foi avaliar a eficácia de instrumentos reciprocantes em níquel-titânio tratados termicamente e métodos complementares no retratamento de dentes com raízes achatadas. Materiais e métodos: Trinta e seis incisivos inferiores foram preparados com instrumentos rotatórios até o diâmetro 25./08 e obturados pela técnica do cone único. Em seguida, os dentes foram divididos em 3 grupos (n=12) de acordo com os sistemas utilizados para desobturação no retratamento: Reciproc Blue: R25 e R40; ProDesign R: PDR 25./06 e PDR 35/.05; WaveOne Gold: WOG Primary e WOG Medium. O material extruído apicalmente foi coletado em microtubos e o volume (mm³) foi mensurado com Micro-CT. Na sequência, os espécimes receberam limpeza complementar com XP-Endo Shaper ou com irrigação passiva ultrassônica (PUI) ou com instrumentação com lima #30 Hedströem em movimento oscilatório. Escaneamentos em Micro-CT foram realizados antes e após a remoção do material obturador. Após quantificação do volume de remanescente de material obturador, os dentes foram seccionados e imagens com microscópio eletrônico de varredura (MEV), dos terços cervical, médio e apical, foram obtidas com aumento de 700X, e avaliadas através de escores baseados na quantidade de material obturador remanescente nas paredes dentinárias. Resultados: Nenhum instrumento reciprocante promoveu remoção completa do material obturador. Todos os sistemas demonstraram extrusão, no entanto, WOG25 proporcionou maior extrusão (P<.05). XP-Endo Shaper reduziu significantemente a quantidade de material obturador nos terços médio e apical (P<.05). Na análise da limpeza das paredes dentinárias, em MEV, não houve diferença estatística entre os métodos de limpeza (P>.05). Os instrumentos reciprocantes estudados não promoveram a remoção completa do material obturador. XP-Shaper, utilizado como instrumento complementar no retratamento, aumentou a remoção de material obturador.

A utilização de aditivos incorporadores de ar em concretos é uma prática comum na construção civil e sua aplicação influencia significativamente diversas propriedades do concreto no estado fresco e endurecido. O objetivo deste estudo foi avaliar a influência do teor de ar incorporado, por meio de aditivo, no desempenho de concretos com diferentes teores de agregados. O programa experimental incluiu avaliação da eficiência de aditivos na incorporação de ar em pastas de cimento, análise microestrutural e ensaios para determinação de propriedades físicas, mecânicas e de durabilidade de concretos com diferentes teores de ar e agregados. No estado fresco, foram realizados ensaios para determinação do teor de ar, massa específica e abatimento. No estado endurecido foram realizados ensaios de massa específica, absorção, resistência à compressão, módulo de elasticidade, velocidade de propagação da onda ultrassônica, carbonatação acelerada e condutividade térmica. Utilizando Microtomografia Computadorizada de Raios-X (Micro-CT) foram dimensionados e quantificados os poros presentes nas amostras dos concretos, bem como determinadas suas porosidades. Os concretos com ar incorporado apresentaram redução na resistência mecânica. Os concretos com menores teores de agregados apresentaram menor resistência mecânica, menor velocidade da frente de carbonatação e menor condutividade térmica. De acordo com os resultados obtidos, pode-se concluir que o aditivo a base de resinas sintéticas foi mais eficiente na incorporação de ar; maiores teores de ar implicam em variabilidade nos resultados de ensaios de resistência à compressão e módulo de elasticidade; os concretos com maiores teores de agregados apresentaram maior velocidade da frente de carbonatação, para mesmos teores de ar incorporado; a condutividade térmica é inversamente proporcional ao teor de ar incorporado no concreto, e quanto menor o teor de agregados, menor a condutividade térmica; o aumento do teor de ar no concreto promove aumento no diâmetro equivalente dos poros e redução da incidência de poros esféricos. / The use of entraining air additives in concrete is a common practice in construction and its application influences several concrete properties in the fresh and hardened state. The aim of this study was evaluate the influence of air entrained content, by additive, in concrete performance with different aggregate contents. The experimental program included the evaluation of additives effectiveness of air entrainment in cement pastes, microstructural analysis and the concretes physical and mechanical properties and durability, with different levels of entrained air and aggregates. Tests were performed in fresh to determine the air content, density and slump. In hardened concrete, density, absorption, compressive strength, elastic modulus, ultrasonic pulse velocity, accelerated carbonation and thermal conductivity tests were performed. By computed X-ray microtomography, the pores present in the concrete samples were sized and quantified and determined the concretes porosities. The air entrained concrete presented decrease in mechanical strength. Concretes with lower aggregate levels presented lower mechanical strength, carbonation speed and thermal conductivity. According to the results, it can be concluded that the synthetic resins base additive was more efficient in air entrainment; larger air content implies variability in the results of the compressive strength and elastic modulus tests; concrete with higher aggregate levels presented higher carbonation speed, for the same entrained air content; thermal conductivity is inversely proportional to the air entrained content in concrete, and as lower was the aggregate content, lower was the thermal conductivity; the increase of air content in concrete promotes increase in the pores diameter and reduction of the incidence of spherical pores.

No description available.

Este estudo translacional avaliou o efeito da aplicação direta de materiais capeadores à base de óleo de copaíba sobre a polpa dentária de ratos. O biomaterial foi analisado de acordo com os processos inflamatórios, reparadores e regenerativos. Cavidades classe I foram preparadas na face oclusal dos molares superiores e inferiores de ratos da linhagem Wistar (n=120). Posteriormente, uma cavidade padronizada foi realizada com broca carbide esférica ¼. Exposições pulpares foram obtidas e após a hemostasia com algodão estéril e água destilada, foi realizado o capeamento pulpar com aplicação de biomateriais diretamente no tecido pulpar. Os biomateriais utilizados foram: COP (Óleo de Copaíba); Ca(OH)2 (hidróxido de cálcio), Ca(OH)2+COP; MTA (agregado trióxido mineral); MTA+COP; BIODENTINA (Biodentine®); BIODENTINA+COP. Todas as cavidades foram restauradas com cimento provisório. Os animais foram sacrificados após o período de 7, 14, 28 dias de acordo com os princípios de ética e experimentação animal. Vinte e um grupos foram criados a partir da combinação de tempos e materiais, cada grupo foi constituído de 5 animais. As peças foram preparadas e processadas pela técnica histológica e coradas pela HE (hemotoxilina e eosina) realizando cortes aleatórios, sendo analisados ao microscópio óptico em 100X de aumento por 2 examinadores. Os critérios avaliados foram: respostas inflamatória e degenerativa, organização tecidual, dentina reacional e reparativa. No último tempo experimental (28 dias) de todos os grupos foi analisado a superfície (mm2) e o volume (mm3) da ponte de dentina formada pela técnica da micro-CT (microtomografia computadorizada) de alta resolução. Os dados foram estatisticamente analisados utilizando o teste T pareado, determinando a superfície e volume da dentina reparadora formada entre os grupos experimentais. Nas análises histológicas foi utilizado o teste não-paramétrico de Mann-Whitney realizando comparações entre os grupos (?=5%). A BIODENTINA demonstrou uma tendência de acelerar o processo de regeneração pulpar, iniciando a deposição de dentina reparativa ao sétimo dia do capeamento. Este material apresentou uma dentina mais espessa em comparação com os outros biomateriais. O MTA também demonstrou uma eficiência na formação da ponte dentinária, entretanto em 20% das amostras não foi observada a presença de dentina reparadora. Ao acrescentar o COP nestes materiais, a formação da ponte dentinária apresentava heterogênea e incompleta, além disso esses grupos continham um processo inflamatório aumentado. A dentina reparadora do grupo de Ca(OH)2 demonstrou presença de túnel, com característica heterogênea. A adição do COP ao Ca(OH)2 aumentou a formação de dentina nas paredes ao redor da câmara pulpar em 80% das amostras, porém esta dentina não apresentava melhora na qualidade. Desta forma, o capeamento pulpar com COP isolado ou associado a Ca(OH)2, MTA e BIODENTINA não formou uma ponte de dentina completa e homogênea no local da exposição pulpar. / This translational study evaluated the effect of the direct application of copaiba oil based capping materials on the rat pulp. The biomaterial was analyzed according to inflammatory, repairing and regenerative processes. Class I cavities were prepared on the occlusal surface of the upper and lower molars of Wistar rats (n = 120). Subsequently, standardized cavities was performed with ¼ spherical carbide drill. Pulp exposures were obtained and after their hemostasis with sterile cotton and distilled water, pulp capping was done with application of biomaterials directly on the pulp tissue. The biomaterials used were: COP (Copaíba oil); Ca(OH)2 (calcium hydroxide), Ca(OH)2+COP; MTA (aggregate mineral trioxide); MTA+COP; BIODENTINE (Biodentine®); BIODENTINA+COP. All cavities were restored with temporary cement. The animals were sacrificed after the period of 7, 14, 28 days according to the principles of ethics and animal experimentation. Twenty-one groups were created from the combination of times and materials, each group consisted of 5 animals. The specimens were prepared and processed by histological technique and stained by HE (haemotoxin and eosin); randomized cuts were examined under optical microscope with 100X enlargement by two different examiners. The evaluated criteria were inflammatory and degenerative response, tissue organization, reactive and reparative dentin. In the last experimental period (28 days) of all groups, the surface (mm2) and the volume (mm3) of the reactive and reparative dentin formed were analyzed by the high-resolution micro-CT (computerized microtomography) technique. The data were statistically analyzed using the paired T-test, determining the surface and volume of the reparative dentin formed between the experimental groups. In the histological analyzes, the non-parametric Mann-Whitney test was used, comparing groups (? = 5%). BIODENTINE demonstrated a tendency to accelerate the process of pulpal regeneration, initiating the deposition of reparative dentin on the seventh day of the capping. This material had a thicker dentin compared to the other biomaterials. The MTA also demonstrated an efficiency in the formation of the dentin bridge; however, 20% of the samples did not observe the presence of reparative dentin. When adding the COP in these materials, the formation of the dentin bridge was heterogeneous and incomplete, in addition these groups contained an increased inflammatory process. The repair dentin of the Ca(OH)2 group showed a tunnel with a heterogeneous characteristic. The addition of COP to Ca(OH)2 increased dentin formation in the walls around the pulp chamber in 80% of the samples, but this dentin did not show improvement in quality. Thus, pulp cap with COP isolated or associated with Ca(OH)2, MTA and BIODENTINE did not form a complete and homogeneous dentin bridge at the site of pulp exposure.

A utilização de aditivos incorporadores de ar em concretos é uma prática comum na construção civil e sua aplicação influencia significativamente diversas propriedades do concreto no estado fresco e endurecido. O objetivo deste estudo foi avaliar a influência do teor de ar incorporado, por meio de aditivo, no desempenho de concretos com diferentes teores de agregados. O programa experimental incluiu avaliação da eficiência de aditivos na incorporação de ar em pastas de cimento, análise microestrutural e ensaios para determinação de propriedades físicas, mecânicas e de durabilidade de concretos com diferentes teores de ar e agregados. No estado fresco, foram realizados ensaios para determinação do teor de ar, massa específica e abatimento. No estado endurecido foram realizados ensaios de massa específica, absorção, resistência à compressão, módulo de elasticidade, velocidade de propagação da onda ultrassônica, carbonatação acelerada e condutividade térmica. Utilizando Microtomografia Computadorizada de Raios-X (Micro-CT) foram dimensionados e quantificados os poros presentes nas amostras dos concretos, bem como determinadas suas porosidades. Os concretos com ar incorporado apresentaram redução na resistência mecânica. Os concretos com menores teores de agregados apresentaram menor resistência mecânica, menor velocidade da frente de carbonatação e menor condutividade térmica. De acordo com os resultados obtidos, pode-se concluir que o aditivo a base de resinas sintéticas foi mais eficiente na incorporação de ar; maiores teores de ar implicam em variabilidade nos resultados de ensaios de resistência à compressão e módulo de elasticidade; os concretos com maiores teores de agregados apresentaram maior velocidade da frente de carbonatação, para mesmos teores de ar incorporado; a condutividade térmica é inversamente proporcional ao teor de ar incorporado no concreto, e quanto menor o teor de agregados, menor a condutividade térmica; o aumento do teor de ar no concreto promove aumento no diâmetro equivalente dos poros e redução da incidência de poros esféricos. / The use of entraining air additives in concrete is a common practice in construction and its application influences several concrete properties in the fresh and hardened state. The aim of this study was evaluate the influence of air entrained content, by additive, in concrete performance with different aggregate contents. The experimental program included the evaluation of additives effectiveness of air entrainment in cement pastes, microstructural analysis and the concretes physical and mechanical properties and durability, with different levels of entrained air and aggregates. Tests were performed in fresh to determine the air content, density and slump. In hardened concrete, density, absorption, compressive strength, elastic modulus, ultrasonic pulse velocity, accelerated carbonation and thermal conductivity tests were performed. By computed X-ray microtomography, the pores present in the concrete samples were sized and quantified and determined the concretes porosities. The air entrained concrete presented decrease in mechanical strength. Concretes with lower aggregate levels presented lower mechanical strength, carbonation speed and thermal conductivity. According to the results, it can be concluded that the synthetic resins base additive was more efficient in air entrainment; larger air content implies variability in the results of the compressive strength and elastic modulus tests; concrete with higher aggregate levels presented higher carbonation speed, for the same entrained air content; thermal conductivity is inversely proportional to the air entrained content in concrete, and as lower was the aggregate content, lower was the thermal conductivity; the increase of air content in concrete promotes increase in the pores diameter and reduction of the incidence of spherical pores.

Spectral x-ray computed tomography (CT) is an important nascent imaging modality with several exciting potential applications. The research presented in this thesis separates into two primary areas with the common underlying theme of spectral CT; the first area is Compton scatter estimation and the second is interior tomography. First, the research is framed and outputs are identified. Background on the concepts used in the thesis is offered, including x-ray imaging and computed tomography, CT scanner architecture, spectral imaging, interior tomography and x-ray scatter. The mathematical background of techniques for image reconstruction from x-ray transmission measurements are presented. Many of the tools used to perform the research, both hardware and software, are described. An algorithm is developed for estimating the intensity of Compton scattered photons within a spectral CT scan, and a major approximation used by the algorithm is analysed. One proposed interior reconstruction algorithm is briefly evaluated; while this is not directly linked to spectral CT, it is related to the work on a novel hybrid spectral interior micro-CT architecture. Conclusions are summarised and suggestions for future work are offered. Scatter is known to cause artefacts in CT reconstructions, and several methods exist to correct data that has been corrupted by scatter. Compton scatter affects the energy of photons, therefore spectral CT measurements offer the potential to correct for this phenomenon more accurately than conventional measurements. A Compton scatter algorithm is developed and is found to match very well to Monte Carlo validation simulations, with the constraints that the object be at the micro-CT scale and that electron-binding effects are omitted. Development of the algorithm uses an approximation of the post-scatter attenuation to simplify the estimation problem and enable implementation. The consequences of this approximation are analysed, and the error introduced is found to be less than 5% in most biomedical micro-CT situations. Interior tomography refers to the incomplete data situation caused by the truncation of some or all CT projections, and is an active research area. A recently proposed interior reconstruction algorithm is evaluated with regard to its sensitivity to input error, and is found to have mediocre performance in this respect. Published results are not found to be reproducible, suggesting some omission from the published algorithm. A novel hybrid spectral interior architecture is described, along with an iterative reconstruction algorithm for hybrid data sets. The system combines a full field of view conventional imaging chain and an interior field of view spectral imaging chain to enable spectral measurement of a region of interest, and addresses some important limitations of spectral x-ray detectors; promising results are shown. Spectral reconstructions from interior data are shown to have sufficient information to distinguish two k-edge contrast agents (iodine and gadolinium) not only within the interior field of view but also beyond it. The architecture is further explored in the context of radiation exposure reduction, including testing of an analytical hybrid reconstruction algorithm.

O sucesso do tratamento endodôntico está associado não só com a limpeza e a instrumentação do sistema de canais radiculares (SCR), mas com a capacidade de selamento do material obturador principalmente do terço apical. O objetivo do presente estudo in vitro foi analisar o volume de guta-percha e de cimento endodôntico no milímetro apical das obturações, utilizando diferentes cimentos e técnicas de condensação. Para tanto, 64 incisivos centrais superiores foram preparados com instrumentos rotatórios de NiTi até o diâmetro cirúrgico #60.02, e então distribuídos aleatoriamente em quatro grupos. Para cada um usou-se um cimento diferente, a saber: Endofill, Sealer 26, AH Plus e Sealapex. E para cada cimento utilizado, metade dos dentes foi obturada pela técnica de condensação lateral ativa (n=8), e a outra metade, pela técnica da condensação lateral passiva (n=8). Feitas as obturações, os dentes foram submetidos ao exame tomográfico com o uso do microtomógrafo SkyScan 1174 v2. As imagens foram reconstruídas pelo programa NRecon e em seguida foi avaliado o parâmetro tridimensional do volume de cimento e guta-percha no milímetro apical, por meio do programa CTan. A análise de variância a dois critérios para o volume de guta-percha demonstrou haver diferença estatisticamente significante para o fator de variação Cimento endodôntico (p>0,05). Por meio do teste Tukey, observou-se que o grupo obturado com o Sealer 26 apresentou maior volume de guta-percha no milímetro apical do comprimento de trabalho quando comparado ao Endofill que se apresentou com menor volume. Já a análise de variância para o volume de cimento endodôntico demonstrou haver diferença estatisticamente significante para o fator de variação Cimento endodôntico (p<0,05), Técnica obturadora (p<0,05) e pelas interações dos fatores (p<0,05). O teste Tukey para o fator de variação Cimento endodôntico demonstrou que o grupo obturado com o Sealapex apresentou menor volume de cimento no milímetro estudado quando comparado ao grupo obturado com AH Plus e Sealer 26, que evidenciaram maior volume de cimento. Em relação ao fator de variação Técnica obturadora, a condensação lateral ativa apresentou menor volume de cimento comparada técnica passiva. Pode-se concluir que o maior volume de guta-percha foi encontrado nos dentes obturados com o cimento endodôntico Sealer 26, semelhantes aos obturados com Sealapex e AH Plus, independentemente da técnica de condensação. O menor volume de cimento endodôntico foi encontrado no grupo obturado com Sealapex, semelhante ao grupo obturado com o Endofill. Em relação à técnica obturadora, a condensação lateral ativa apresentou menor volume de cimento quando comparada à passiva. / The success of endodontic treatment is associated not only with the cleaning and the instrumentation of the root canal system (RCS) but also with the sealing ability mainly in the apical third of the filling material. The aim of this in vitro study was to analyze the volume of gutta-percha and sealer in the apical millimeter of the fillings, using different obturation technique and sealers. For that purpose, 64 maxillary central incisors were prepared with NiTi rotary instruments until the surgical diameter of #60.02, and then divided randomly into four groups. For each group, different sealers were used, such as Endofill, Sealer 26, AH Plus and Sealapex. And for each sealer used, half the teeth were obturated using an active lateral condensation technique (n=8), and the other half by passive lateral condensation technique (n=8). After the fillings procedures, samples were examined by SkyScan 1174 v2 micro-CT. Images were reconstructed by NRecon software, and then the dimensional parameter of the volume of sealer and gutta-percha at the apical millimeter was evaluated through the CTan program. The ANOVA Two-Way results for the analysis of the volume of guttapercha showed a statistically significant difference for endodontic sealer factor (p>0,05). The Tukey test showed that the group filled with Sealer 26 had higher volume of gutta-percha at the apical millimeter of working length when compared to that of the Endofill, which presented lower volumes. However, the ANOVA Two-Way analysis for the volume of sealer, showed a statistically significant difference for the endodontic sealer factor (p<0.05), obturation technique (p<0.05) and between the interactions of the factors (p<0.05). The Tukey test for the Sealer endodontic variation factor showed that the group filled with Sealapex had the lowest volume of sealer in the studied millimeter when compared to the group filled by AH Plus and Sealer 26, which had the highest volume of sealer. Regarding the filling technique variation factor, the active lateral condensation technique showed lower sealer volume than passive. It can be concluded that the higher volume of gutta-percha was found in teeth filled with sealer Sealer 26, similar to Sealapex and AH Plus, regardless of the technique of condensation. The lowest volume of sealer was found in the group filled with Sealapex, similar to the group filled with Endofill. Regarding the obturation technique, the active lateral condensation technique showed lowest volume of sealer than the passive.

OBJECTIVE: Breast cancer represents a significant risk in women's health, affecting many women worldwide. Current treatment options in the U.S involve a multidisciplinary approach, most often beginning with surgery to remove cancerous tissue. Evaluation of margins for cancer on excised tissue is an important part of surgery, an important predictor of survival. As a result, there has been a great deal of research interest in intraoperative margin assessment, with a focus on fast and accurate results. Micro-computed Tomography (micro-CT) has emerged as a promising avenue to this end. We hypothesize that micro-CT scans will show a statistically significant difference in radiodensity between cancerous and non-cancerous tissue at intraoperative scan times. METHODS: 15 breast lumpectomy specimens were collected from patients undergoing surgery at Massachusetts General Hospital (MGH). Lumpectomies were scanned with a Nikon XTH225 Micro-CT scanner. Corresponding histology slides were scanned with a whole slide scanner, and matched with micro-CT scans. Representative areas of cancerous and non-cancerous tissues were segmented from micro-CT scans, and their respective radiodensity differences were tested for statistical significance. RESULTS: 9 of 15 lumpectomy cases were successfully matched with histology sections. Of the 9 cases matched, 8 showed a statistically significant difference in mean radiodensity. CONCLUSION: Due to potential confounds in the study, the results are difficult to deem conclusive. However, micro-CT remains a promising tool in margin assessment, and could be fit for clinical use with further study.