Masters of Science / Sometimes, dental impressions need to be transported to distant laboratories. It has been reported that the temperature in a vehicle can reach up to 66C when the outdoor temperature is 38C. These temperatures may be reached during South African summers. The objective of this in vitro study was to investigate the effect of temperature and time on the dimensional stability of two elastomeric impression materials. Methodology: Specimens consisted of impressions made of an ISO-specified test-block featuring a pattern of grooves. Materials used were polyether (Impregum Penta) and polyvinylsiloxane (Affinis Precious regular body). Using an SLR camera and standardized technique, the specimens were photographed at 2 different temperatures (21°C and 66°C) and 3 time intervals (30min, 8hrs and 14 days). This resulted in a total of 12 groups (n=10) to be compared. Digital images of the impressions were calibrated and measured using digital analyzing software. These distances were used to evaluate the mean % dimensional change (%DC) for each group. VEPAC module of Statistica 10 was used for the statistical analysis. To analyze exactly where the differences lied, a Fisher LSD correction was applied to correct for multiple pair wise comparisons. Results: Comparing polyether with silicone, there was no difference in the mean %DC for specimens kept at 21°C for 8hrs (polyether=0.364; silicone=0.237). Neither was there a difference between polyether and silicone when heated to 66°C, cooled off, and measured after 8hrs (polyether=0.306; silicone=0.297) or after 14 days (polyether=-0.272; silicone=-0.093). For both polyether and silicone, the mean %DC of the groups exposed to 66°C, cooled off and measured after 8hrs (polyether=0.306; silicone=0.297) differed significantly when compared to the group measured after 14 days (polyether=-0.2723; silicone=-0.092) (P<0.0001 and P=0.0029 resp). For both polyether and silicone, the mean %DC of the groups exposed to 66°C, cooled off and measured after 8hrs (polyether=0.306; silicone=0.297) did not differ when compared to the 21°C (polyether=0.364; silicone=0.237). Conclusions: Within limitations of this study, both materials were heat-sensitive. It is recommended that materials return to 21°C before casting. Despite statistical differences, all results were within ISO specifications of maximum 1.5%DC.

Thresholding algorithms and filters are of great importance when utilizing OCR to extract information from text documents such as invoices. Invoice documents vary greatly and since the performance of image processing methods when applied to those documents will vary accordingly, selecting appropriate methods is critical if a high recognition rate is to be obtained. This paper aims to determine if a document recognition system that automatically selects optimal processing methods, based on the characteristics of input images, will yield a higher recognition rate than what can be achieved by a manual choice. Such a recognition system, including a learning framework for selecting optimal thresholding algorithms and filters, was developed and evaluated. It was established that an automatic selection will ensure a high recognition rate when applied to a set of arbitrary invoice images by successfully adapting and avoiding the methods that yield poor recognition rates.

No description available.

INTRODUCTION: Ebola virus (EBOV) is a highly infectious and often lethal filovirus that causes hemorrhagic fever, with a reported case fatality rate of 40-90%. There are currently no Food and Drug Administration (FDA) approved medical countermeasures (MCMs) for EBOV. Non-human primates (NHPs) remain the gold standard animal model for EBOV research as they most accurately recapitulate human disease. OBJECTIVE: This study aimed to characterize the temporal viral pathogenesis of EBOV in the liver of infected rhesus macaques using routine histopathology, multiplex immunohistochemistry (mIHC) and multiplex fluorescent In Situ Hybridization (mFISH), refined by digital pathology (DP) and image analysis (DIA). METHODS: 21 FFPE liver sections from EBOV-infected rhesus macaques were examined microscopically (Uninfected controls n=3; 3 DPE n=3; 4 DPE n=3; 5 DPE n=3; 6 DPE n=3; Terminal n=6). Tissues were stained with H&E and PTAH for histopathological scoring. Three serial sections were fluorescently immunolabeled or hybridized under three independent conditions (1.EBOV VP35, Tissue Factor, CD68; 2.EBOV VP35, Heppar, Myeloperoxidase (MPO); 3.EBOV VP35, IL-6, ISG-15). Slides were digitized by a Vectra PolarisTM fluorescent whole slide scanner and DIA was conducted using HaloTM image analysis software. Statistical analysis was conducted using GraphPad PrismTM 8.0. RESULTS: Comparing peracute (3-4 DPE) to acute (5-6 DPE) and terminal (6-8 DPE) EBOV infection, there is a statistically significant (p < 0.05) increase in hepatic inflammation and fibrin thrombi, correlating with an absolute increase in macrophages (CD68), neutrophils (MPO), and total % of Tissue Factor in the liver. There is also a significant increase in the severity of necrosis, which correlates with a decrease in Heppar. While there was significant colocalization of VP35 and CD68 starting at 4 DPE, there was only rare colocalization of VP35 with Heppar, even in terminal animals. Similar to mIHC, progressive and statistically significant differences were observed in gene expression when comparing peracute to acute and terminal EBOV infection. IL-6 predominated within periportal fibrovascular compartments, but also colocalized within cells concurrently expressing EBOV VP35. EBOV VP35 expression was observed within histiocytes, endothelial cells, and less commonly hepatocytes. ISG-15 expression was observed in periportal regions and in proximity to cells expressing EBOV VP35, but colocalization within EBOV VP35 expressing cells was an extremely rare event. CONCLUSION: Qualitative tools are well suited for confirming virulence and viral tissue tropism, but do little to build on our current understanding of disease. Using DIA in partnership with mIHC and mFISH, this study quantified statistically significant temporal changes in the immunoreactivity and hybridization of host and viral biomarkers that have previously been linked to the pathogenesis of EBOV. Taken together, these tools have enabled us to characterize minute changes that reflect magnitudes of biological variability simply not feasible to detect with the human eye. Furthermore, spatial context has refined our current understanding of differential gene expression of EBOV, which has the potential to aid in development of host-directed therapies. The establishment of these benchmarks will serve as a guide for the validation of cross-institutional EBOV animal models.

No description available.

Fluidized bed technology is used for thermal conversion of solid fuels (combustion and gasification) and is especially suitable for conversion of low-rank fuels such as biomass and waste. The performance of fluidized bed units depends on the fuel mixing and fuel-gas contact. Thus, it is important to understand these two phenomena in order to develop models for reliable design and scale up of fluidized bed units. This work investigates, under conditions representative for industrial fluidized bed units, the lateral fuel mixing (in a unit with a cross section of 1.44 m2 both at hot and cold conditions) and the bubble flow distribution (in a 1.2 m-wide 2-dimensional unit). The work confirms previous findings on the formation of preferred bubble paths and shows that these bubble paths are enhanced by lowering the fluidization velocity, increasing the dense bed height and reducing the pressure drop across the gas distributor. From the fuel mixing experiments, an estimation of the lateral effective dispersion coefficient to values in the order of 10-3 m2/s is obtained under both hot and cold conditions. The experiments under cold conditions give additional qualitative information on the fuel mixing patterns such as flotsam/jetsam tendencies. The camera probe developed for fuel tracking under hot conditions enables to study the fuel dispersion under real operation at relevant industrial scales. Based on the characteristics of the bubble path flow, a model for the horizontal fuel dispersion on a macroscopic scale is formulated and shown to be able to give a good description of the experimental data. As opposed to the commonly applied diffusion-type modeling of the lateral solids dispersion, the proposed model facilitates integration with models of the bubble flow. Thus, the present modeling work is a first step to provide a modeling of the fuel dispersion, which uses as inputs only the main operational parameters of the fluidized bed.

Materiais cerâmicos obtidos a partir de pós nanocristalinos permitem a obtenção de excelentes propriedades após sinterização, devido à possibilidade de redução da temperatura final de sinterização com conseqüente refinamento microestrutural e excelente densificação. Nesse contexto, a zircônia tetragonal (ZrO2 (t)) tem um importante papel, pois suas características intrínsecas, tais como a transformação martensítica (ZrO2 (t-m)), permitem o desenvolvimento de excelentes propriedades, destacando-se a elevada tenacidade à fratura e resistência a flexão, tornando-a um material diferenciado visando aplicações nobres onde propriedades mecânicas e confiabilidade sejam pré-requisitos. Visando otimizar estas aplicações, se faz necessário conhecer as correlações entre as propriedades mecânicas e a microestrutura. Sendo assim, é de extrema importância promover a revelação microestrutural desses materiais, de forma padronizada e com representatividade estatística, o que exige cuidados nas técnicas de preparação ceramográfica. Nesse trabalho pretende-se caracterizar microestruturalmente cerâmicas a base de ZrO2(Y2O3) nanométrica, visando estudar os efeitos da temperatura e do tempo de sinterização na cinética de crescimento de grão. Foi definida uma rota de preparação e análise ceramográfica propondo seqüência de lixas e panos de polimento, assim como cargas e tempos em cada etapa. As amostras foram atacadas termicamente e micrografias foram obtidas. As micrografias foram processadas por rotinas de análise digital de imagens, visando definir padronizações para determinação de parâmetros microestruturais de interesse, tais como distribuição de tamanhos de grãos, densidade de grãos por unidade de área, razão de aspecto, etc. Foi estudado o efeito das condições de sinterização (temperatura final e tempo de isoterma) no crescimento de grãos. / Ceramic materials obtained from nanocrystalline powders enable the obtaining of excellent properties after sintering, due to the possibility of reducing the final sintering temperature with consequent microstructural refinement and excellent densification. In this context, tetragonal zirconia (ZrO2 (t)) has an important role, since their intrinsic characteristics, such as the martensitic transformation (ZrO2 (t-m)), allow the development of excellent properties, highlighting the high tenacity to fracture and resistance to bending, making it a differentiated material aiming noble applications where mechanical properties and reliability are prerequirements. In order to optimize these applications, it is necessary to know the correlations between the mechanical properties and microstructure. Thus, it is extremely important to promote the microstructural disclosure of these materials, in a standardized manner and with statistical representativeness, which requires care with the ceramographic preparation techniques. This work aims to microstructurally characterize ceramics based on nanometric ZrO2(Y2O3), looking for the study of the effects of the sintering temperature and time on the graingrowth kinetics. It was defined a route for ceramographic preparation and analysis proposing a sequence of sandpapers and polishing cloths, as well as loads and times at each stage. The samples were thermally etched and micrographs were obtained. The micrographs were processed through routines of digital image analysis, aiming the definition of standards for the determination of microstructural parameters of interest, such as distribution of grain sizes, density of grains per unit of area, aspect ration, and others. It was studied the effects of the sintering conditions (final temperature and time of isotherm) on the grain growth.

Materiais cerâmicos obtidos a partir de pós nanocristalinos permitem a obtenção de excelentes propriedades após sinterização, devido à possibilidade de redução da temperatura final de sinterização com conseqüente refinamento microestrutural e excelente densificação. Nesse contexto, a zircônia tetragonal (ZrO2 (t)) tem um importante papel, pois suas características intrínsecas, tais como a transformação martensítica (ZrO2 (t-m)), permitem o desenvolvimento de excelentes propriedades, destacando-se a elevada tenacidade à fratura e resistência a flexão, tornando-a um material diferenciado visando aplicações nobres onde propriedades mecânicas e confiabilidade sejam pré-requisitos. Visando otimizar estas aplicações, se faz necessário conhecer as correlações entre as propriedades mecânicas e a microestrutura. Sendo assim, é de extrema importância promover a revelação microestrutural desses materiais, de forma padronizada e com representatividade estatística, o que exige cuidados nas técnicas de preparação ceramográfica. Nesse trabalho pretende-se caracterizar microestruturalmente cerâmicas a base de ZrO2(Y2O3) nanométrica, visando estudar os efeitos da temperatura e do tempo de sinterização na cinética de crescimento de grão. Foi definida uma rota de preparação e análise ceramográfica propondo seqüência de lixas e panos de polimento, assim como cargas e tempos em cada etapa. As amostras foram atacadas termicamente e micrografias foram obtidas. As micrografias foram processadas por rotinas de análise digital de imagens, visando definir padronizações para determinação de parâmetros microestruturais de interesse, tais como distribuição de tamanhos de grãos, densidade de grãos por unidade de área, razão de aspecto, etc. Foi estudado o efeito das condições de sinterização (temperatura final e tempo de isoterma) no crescimento de grãos. / Ceramic materials obtained from nanocrystalline powders enable the obtaining of excellent properties after sintering, due to the possibility of reducing the final sintering temperature with consequent microstructural refinement and excellent densification. In this context, tetragonal zirconia (ZrO2 (t)) has an important role, since their intrinsic characteristics, such as the martensitic transformation (ZrO2 (t-m)), allow the development of excellent properties, highlighting the high tenacity to fracture and resistance to bending, making it a differentiated material aiming noble applications where mechanical properties and reliability are prerequirements. In order to optimize these applications, it is necessary to know the correlations between the mechanical properties and microstructure. Thus, it is extremely important to promote the microstructural disclosure of these materials, in a standardized manner and with statistical representativeness, which requires care with the ceramographic preparation techniques. This work aims to microstructurally characterize ceramics based on nanometric ZrO2(Y2O3), looking for the study of the effects of the sintering temperature and time on the graingrowth kinetics. It was defined a route for ceramographic preparation and analysis proposing a sequence of sandpapers and polishing cloths, as well as loads and times at each stage. The samples were thermally etched and micrographs were obtained. The micrographs were processed through routines of digital image analysis, aiming the definition of standards for the determination of microstructural parameters of interest, such as distribution of grain sizes, density of grains per unit of area, aspect ration, and others. It was studied the effects of the sintering conditions (final temperature and time of isotherm) on the grain growth.

The subject of digital image analysis deals with extracting relevant information from image data, stored in digital form in a computer. A fundamental problem in image analysis is image segmentation, i.e., the identification and separation of relevant objects and structures in an image. Accurate segmentation of objects of interest is often required before further processing and analysis can be performed. Despite years of active research, fully automatic segmentation of arbitrary images remains an unsolved problem. Interactive, or semi-automatic, segmentation methods use human expert knowledge as additional input, thereby making the segmentation problem more tractable. The goal of interactive segmentation methods is to minimize the required user interaction time, while maintaining tight user control to guarantee the correctness of the results. Methods for interactive segmentation typically operate under one of two paradigms for user guidance: (1) Specification of pieces of the boundary of the desired object(s). (2) Specification of correct segmentation labels for a small subset of the image elements. These types of user input are referred to as boundary constraints and regional constraints, respectively. This thesis concerns the development of methods for interactive segmentation, using a graph-theoretic approach. We view an image as an edge weighted graph, whose vertex set is the set of image elements, and whose edges are given by an adjacency relation among the image elements. Due to its discrete nature and mathematical simplicity, this graph based image representation lends itself well to the development of efficient, and provably correct, methods. The contributions in this thesis may be summarized as follows: Existing graph-based methods for interactive segmentation are modified to improve their performance on images with noisy or missing data, while maintaining a low computational cost. Fuzzy techniques are utilized to obtain segmentations from which feature measurements can be made with increased precision. A new paradigm for user guidance, that unifies and generalizes regional and boundary constraints, is proposed. The practical utility of the proposed methods is illustrated with examples from the medical field.

Filtering is a key step in digital image processing and analysis. It is mainly used for amplification or attenuation of some frequencies depending on the nature of the application. Filtering can either be performed in the spatial domain or in a transformed domain. The selection of the filtering method, filtering domain, and the filter parameters are often driven by the properties of the underlying image. This thesis presents three different kinds of biomedical image filtering applications, where the filter parameters are automatically determined from the underlying images. Filtering can be used for image enhancement. We present a robust image dependent filtering method for intensity inhomogeneity correction of biomedical images. In the presented filtering method, the filter parameters are automatically determined from the grey-weighted distance transform of the magnitude spectrum. An evaluation shows that the filter provides an accurate estimate of intensity inhomogeneity. Filtering can also be used for analysis. The thesis presents a filtering method for heart localization and robust signal detection from video recordings of rat embryos. It presents a strategy to decouple motion artifacts produced by the non-rigid embryonic boundary from the heart. The method also filters out noise and the trend term with the help of empirical mode decomposition. Again, all the filter parameters are determined automatically based on the underlying signal. Transforming the geometry of one image to fit that of another one, so called image registration, can be seen as a filtering operation of the image geometry. To assess the progression of eye disorder, registration between temporal images is often required to determine the movement and development of the blood vessels in the eye. We present a robust method for retinal image registration. The method is based on particle swarm optimization, where the swarm searches for optimal registration parameters based on the direction of its cognitive and social components. An evaluation of the proposed method shows that the method is less susceptible to becoming trapped in local minima than previous methods. With these thesis contributions, we have augmented the filter toolbox for image analysis with methods that adjust to the data at hand.