Parmi les outils de réduction de dose d’exposition en scanner, le plus récent est l’emploi des Reconstructions Itératives (RI). Ces nouveaux algorithmes permettent de corriger de façon répétée les données d’acquisition par modélisation, rendant envisageable la compensation sur les images reconstruites, du bruit engendré par une acquisition scanographique à basse dose. Ce travail a eu pour but d’évaluer, à travers 5 études originales, la performance des RI en scanner thoracique, en particulier leur potentiel de réduction de dose et leurs applications cliniques. La 1ère étude a permis de valider la réduction de bruit sans perte d’information diagnostique sur 32 scanners thoraciques grâce à un algorithme de RI de 1ère génération (IRIS). L’évaluation initiale de cette technique a permis de l’intégrer en pratique clinique donnant lieu à la 2e étude évaluant IRIS chez 80 patients ayant bénéficié de 2 scanners thoraciques successifs dans le cadre d’un suivi. Malgré une réduction de dose de 35% par réduction du milliampérage, IRIS a permis de maintenir une qualité image similaire à celle du scanner initial. L’évaluation d’un algorithme de RI de 2e génération (SAFIRE) a ensuite été réalisée sur des examens acquis à dose encore plus réduite : (a) chez 80 patients étudiés par angioscanner à bas kilovoltage avec 50% de réduction de dose ; et (b) chez 50 patients étudiés en scanner double source avec acquisition simultanée d’images pleine dose et d’images à dose réduite de 60%. Enfin, SAFIRE a été évalué dans une situation clinique particulière, l’embolie pulmonaire, permettant une réduction de dose de 60% sans perte de performance diagnostique. / Among the different tools available to save dose in CT, the most recent option is the use of Iterative Reconstructions (IR) instead of Filtered Back Projection. These new algorithms can correct repeatedly the acquisition by modeling data, making possible the compensation of the noise generated in reconstructed images by a low-dose CT acquisition. The purpose of the present work was to evaluate, through 5 original studies, the performance of IR in chest CT, especially their potential for dose reduction and clinical applications.Based on 32 chest CT examinations, the first study validated the level of noise reduction achievable with a first-generation IR algorithm (IRIS). This initial evaluation allowed us to investigate the performance of IRIS in clinical practice, giving rise to the second IRIS study; the latter evaluated 80 patients who underwent two successive chest CT examinations for monitoring. Despite a 35% dose reduction achieved by reduction of the tube current, IRIS provided a similar image quality in comparison with that of the initial examination. A second-generation IR algorithm (SAFIRE) was then evaluated on examinations obtained at lower dose levels in (a) 80 patients who had undergone low-kilovoltage chest CT angiography with a 50% dose reduction; and (b) 50 patients studied with a dual source CT system providing simultaneously full-dose and low- dose (reduction of 60%) images. Lastly, SAFIRE has been evaluated in the specific context of acute pulmonary embolism where the diagnostic performance of low-dose SAFIRE images was found to be similar to that of full-dose FBP images.

Women diagnosed with breast cancer and who have the disease surgically treated by mastectomy experience a health crisis. This thesis focused on the behaviours, feelings and attitudes of women during their breast cancer and mastectomy experiences. The overall purpose was to identify therapeutic factors that can be used by health professionals to improve the psychological and physiological well-being of women with this disease. The conceptual scaffolding for the thesis was drawn from the fields of perceptual psychology and decision-making. The thesis was supported by a study that examined specific areas concerning the breast cancer and mastectomy experience. These areas were self-perceptions, the psychological milieu resulting from a breast cancer diagnosis, and post-mastectomy breast restoration decision-making. The population included: a prosthesis group of 64 women who had mastectomies and wore external breast prostheses, a reconstruction group of 31 women who had mastectomies and underwent breast reconstructions, a control A group of 75 women who had not experienced mastectomy, and a control B group of 65 women who also had not experienced mastectomy. Self-perceptions: The perceptions of the prosthesis, reconstruction and control A groups regarding their body-image, self-concept, total self-image, and self-esteem were compared by using Polivy's (1977) Body-Image Scale and Rosenberg's (1965) Self-Esteem Scale. The body-image, total self-image, and self-esteem mean scores indicated that the prosthesis and reconstruction groups had more positive feelings regarding their bodies than did the control group. There were no significant differences in self-concept among the three groups. These findings challenge a common assumption that mastectomy automatically results in psychiatric morbidity caused by an altered body-image and suggest that health professionals should not make assumptions about how a woman will psychologically respond to mastectomy. Quality of life perceptions were compared among the prosthesis, reconstruction and control B groups using the Ferrans and Powers (1985) Quality of Life Index. The mean scores of the prosthesis and reconstruction groups were higher than the control group's scores, with higher scores indicating more positive quality of life perceptions. The findings suggest that the women in the mastectomy samples had found ways to cope with their health crises. Over time, they learned not to define all existence in terms of a cancer diagnosis and had gained or maintained a positive perspective on life. Post-mastectomy attitudes in the prosthesis and the reconstruction groups were compared. Using the Mastectomy Attitude Scale the results indicated that both groups were satisfied with their bodies, had a positive outlook towards their lives, implied that sexuality entailed more than having breasts, and felt that mastectomy treatment was necessary to save their lives. Neither group concealed that they had a mastectomy, nor were the women prone to discuss their mastectomy experiences. The findings from the study indicate that the women post-mastectomy already had or developed positive attitudes towards themselves and life in general and the method chosen for breast restoration had no apparent impact on these attitudes. The self-perception data indicated that women do adjust and cope with breast cancer surgically treated by mastectomy. These women should be encouraged by health professionals to develop a helping relationship with other women who are newly diagnosed with the disease. This alliance could engender hope in those women who are beginning their journey along a similar road to survival. More hope for these women and less fatalism would decrease their sense of crisis and facilitate their abilities to take an active part in the decision-making processes relating to their treatment. Psychological Milieu: The women in the prosthesis and the reconstruction groups were interviewed about their breast cancer and mastectomy experiences. The findings supported the premise that receiving a diagnosis of breast cancer plunged the women into a health crisis and caused an instant disruption to their lives. The women found that they had to suddenly deal with several complex issues all at the same time, such as what must be done in the immediate future to treat the cancer, as well as the more frightening issues of the meaning of the illness on their ultimate life expectancy. All of this turmoil played havoc with their ability to make informed decisions regarding their breast cancer treatment alternatives. This finding suggests the need for more individualised interventions and support for women when they are making decisions during this stressful period. Health professionals need to keep in mind that simply hearing the word "cancer" often prevents a person from assimilating the complete diagnosis, indicated treatments, and possible prognosis. Therefore, care-givers must be prepared to repeat and elaborate upon information previously given to the affected individual and the family. Breast Restoration Decision-Making: To evaluate the prosthesis and the reconstruction groups' abilities to undertake competent breast restoration decision-making, a 5 Stage process was devised, modelled after Janis and Mann's (1977) seven criteria for competent decision-making. Analysis of the data revealed that both groups displayed passive information seeking behaviour in relation to breast restoration alternatives. They had either no knowledge or limited knowledge regarding the alternatives. Their lack of knowledge was due either to (1) anxiety about their disease, or (2) deficiencies in the interpersonal skills of individuals presenting information to them, or (3) the perceptions that they had insufficient time to gather information, or (4) a combination of these factors. Because the prosthesis and the reconstruction groups were under stress they used coping styles to accomplish decision-making. To measure their coping styles five categories were defined, based on Janis and Mann's (1977) conflict model of emergency decisionmaking and Simon's (1957) notion of "bounded rationality". Two styles emerged. The prosthesis group used the "Sideliner" style that allowed the women to make a quick, conflict-free decision. They were not aware of alternative choices resulting in their decision-making experience being uncomplicated and effortless. The reconstruction group used the "Contented" style that also allowed them an uncomplicated and effortless decision-making experience. The women decided that breast reconstruction was their only viable option. Many of them did not even think that they had made a decision about an alternative because of the strong salience towards breast reconstruction. A breast restoration decision-making model has been developed and proposed for women to use when considering their alternatives. This model offers to health professionals and women a realistic and useable decision-making process that can be implemented when individuals are experiencing a health crisis. The model can be modified and used for numerous situations that require decisions regarding treatment alternatives. This inquiry has demonstrated that there is a need for a specific health professional to assist women newly diagnosed with breast cancer. This individual would assume several roles that include one of advocacy for the women, and the important role of ensuring that these individuals have the information and knowledge to make competent decisions regarding their breast cancer treatments.

Steps on surfaces have long been explored for their own sake, and exploited as growth mediators. However, another type of linear surface defect - the domain boundary - has been largely neglected. Here we introduce domain boundaries of the 5x5 dimer-adatom-stacking fault reconstruction, explore their properties and demonstrate that they too can be used to mediate growth in a useful manner. When a thin layer of Ge is grown on Si(111) lattice strain induces the overlayer to reconstruct as Ge5x5. Using solid phase epitaxy, many domains of 5x5 can be grown. The domain interiors have excellent order, and with careful annealing, the boundaries that separate them are straight and uniform. Well-ordered boundaries propagate along the two high symmetry directions <1 -1> or <1 1> and are called A-type or B-type respectively. Boundaries of the second type are unique to Ge5x5. Registration with the substrate restricts the misfit between domains to discrete possibilities which are labeled according to a modified version of the system used for domain boundaries of Si(111)7x7. The distribution of observed boundary types is strongly peaked and reflects the relative energies of boundaries of different character. The expanded labeling scheme can be used to sketch the kinetic processes which lead to the distribution peaks. The dominant boundary by far is the one known as B[-2 2], which accounts for almost half of all observed boundaries. The atomic structure for this type of boundary has been established as a truncated 7x7 unit cell. Thus, these boundaries are linear arrays of quasi-7x7 embedded in a sea of 5x5. On the Si(111)7x7 surface the Group 13 elements, when deposited at sub-ML coverages and low temperatures, form magic clusters. The perfect uniformity and precise registration that earns them the moniker ‘magic’ make these clusters unusual among self-organized atomic scale objects. The clusters that form on 5x5 lack the uniformity of their counterparts on 7x7. However, with many domains, deposited In or Ga segregate to the quasi-7x7 B[-2 2] boundaries and there form magic clusters. The boundary thus acts as a template for growing straight lines of precisely spaced, atomically identical, nanoscale clusters. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-07-29 08:50:16.874

Accurate forecasts of tropical cyclone surface wind fields are essential for decisions involving evacuation preparation and damage potential. Towards addressing these actions, a comparison of the CFAN tropical cyclone surface wind field model with the H*Wind wind field reanalyzes is done to assess the accuracy of the CFAN algorithm and to determine potential limitations of its use. 16 tropical cyclones were assessed through correlation coefficient, mean bias, and root mean square error. The resolution of initial conditions to be ingested into the model was also analyzed, along with storm type and whether or not wind shear was a limiting factor. Results suggest that the CFAN wind model accurately predicts the H*Wind analyses in most regions of the TC. The center of circulation has the highest error due to the CFAN wind model treating the center of circulation as a point rather than having finite lateral extent. Results from the sensitivity analysis based on input resolution show that the minimum input resolution for the CFAN wind model to produce fine spatial resolutions with high fidelity is 0.25°. It is shown that the reproductions of weaker tropical cyclones have lower accuracy due to wind field asymmetries within these systems, while stronger TCs are better reproduced, as these systems are usually better organized. Finally, through the wind shear analysis, it is shown that the accuracy of reconstruction is not dependent on the magnitude of vertical wind shear.

Concussions are a problem in competitive sports with growing concern over the acute and long-term consequences of repetitive head trauma. Participation in sport increases risk of concussion, particularly contact sports including rugby, hockey and football (Harmon et al., 2013). In rugby league, there are between 8.0-17.5 concussions/1000 player hours, representing roughly 10-15% of all injuries in the sport (Gardner et al., 2015). Shoulder, head, hip and knee are reported to be the most common regions that impact the head and are responsible for the greatest number of concussive injuries in rugby (Cusimano et al., 2013; Fuller et al., 2010; Gardner et al., 2014; Toth, Mcneil, & Feasby, 2005). In each of the common injury events reported in elite men’s rugby, there are unique combinations of impact conditions which include effective mass, compliance, velocity and location of impact. The head-to-head event represents a low mass, low compliance event, whereby the hip and shoulder-to-head collisions represents high mass, high compliance events. Scientists have conducted research in an effort to describe incidence and mechanisms of concussive injury in rugby, however, little is known about the biomechanics of head injury in the sport (Fréchède & Mcintosh, 2009; Fréchède & McIntosh, 2007; McIntosh et al., 2000). The purpose of this thesis is to characterize dynamic response and brain tissue deformation for (1) hip-to-head, (2) shoulder-to-head, (3) knee-to-head, and (4) head-to-head concussion events in men’s rugby. Twenty-nine (29) impact videos of diagnosed concussive injuries associated with the four common injury events were reconstructed in the Neurotrauma Impact Science Lab. Head-to-head impacts were reconstructed in this study using a pendulum system, while hip, shoulder and knee to head impacts were reconstructed using the pneumatic linear impactor. Results of this study demonstrate that the common injury events resulting in concussion in elite men’s rugby have different dynamic response characteristics. Head-to-head events produced significantly greater peak linear and peak rotational acceleration, however no significant differences in maximum principal strain between the injury events. Results of this study can be useful in reducing rates and severity of concussive injury in rugby.

The spatial and temporal distribution of modern diatom assemblages in surface sediments, on the most dominant macrophytes, and in the water column at 96 locations in Florida Bay, Biscayne Bay and adjacent regions were examined in order to develop paleoenvironmental prediction models for this region. Analyses of these distributions revealed distinct temporal and spatial differences in assemblages among the locations. The differences among diatom assemblages living on subaquatic vegetation and sediments, and in the water column were significant. Because concentrations of salts, total phosphorus (WTP), total nitrogen (WTN) and total organic carbon (WTOC) are partly controlled by water management in this region, diatom-based models were produced to assess these variables. Discriminant function analyses showed that diatoms can also be successfully used to reconstruct changes in the abundance of diatom assemblages typical for different habitats and life habits. To interpret paleoenvironmental changes, changes in salinity, WTN, WTP and WTOC were inferred from diatoms preserved in sediment cores collected along environmental gradients in Florida Bay (4 cores) and from nearshore and offshore locations in Biscayne Bay (3 cores). The reconstructions showed that water quality conditions in these estuaries have been fluctuating for thousands of years due to natural processes and sea-level changes, but almost synchronized shifts in diatom assemblages occurred in the mid-1960’s at all coring locations (except Ninemile Bank and Bob Allen Bank in Florida Bay). These alterations correspond to the major construction of numerous water management structures on the mainland. Additionally, all the coring sites (except Card Sound Bank, Biscayne Bay and Trout Cove, Florida Bay) showed decreasing salinity and fluctuations in nutrient levels in the last two decades that correspond to increased rainfall in the 1990’s and increased freshwater discharge to the bays, a result of increased freshwater deliveries to the Everglades by South Florida Water Management District in the 1980’s and 1990’s. Reconstructions of the abundance of diatom assemblages typical for different habitats and life habits revealed multiple sources of diatoms to the coring locations and that epiphytic assemblages in both bays increased in abundance since the early 1990’s.

This thesis describes reconstruction of scene which is scan trough two cameras. There are described methods of calibration of cameras system, methods for finding the corners and methods for finding correspondences. Corners are searched by FAST detector and for search correspondences are used normalized cross correlation. In the framework of 3D reconstruction is implemented rectification. The final shape is saved to VRML format. In the thesis are described parallelization options. The calculation of the correlation is optimized for multiprocessors CPU and there are designed implementations of algorithm to GPU and FPGA too.

This thesis deals with 3D reconstruction using stereo cameras. This work is to show the usefulness of GPU acceleration for sophisticated algorithm

No description available.

<p>This thesis documents the development and application of a unique database orientated software package, BugsCEP, for environmental and climatic reconstruction from fossil beetle (Coleoptera) assemblages. The software tools are described, and the incorporated statistical methods discussed and evaluated with respect to both published modern and fossil data, as well as the author’s own investigations.</p><p>BugsCEP consists of a reference database of ecology and distribution data for over 5 800 taxa, and includes temperature tolerance data for 436 species. It also contains abundance and summary data for almost 700 sites - the majority of the known Quaternary fossil coleopteran record of Europe. Sample based dating evidence is stored for a large number of these sites, and the data are supported by a bibliography of over 3 300 sources. Through the use of built in statistical methods, employing a specially developed habitat classification system (Bugs EcoCodes), semi-quantitative environmental reconstructions can be undertaken, and output graphically, to aid in the interpretation of sites. A number of built in searching and reporting functions also increase the efficiency with which analyses can be undertaken, including the facility to list the fossil record of species found by searching the ecology and distribution data. The existing Mutual Climatic Range (MCR) climate reconstruction method is implemented and improved upon in BugsCEP, as BugsMCR, which includes predictive modelling and the output of graphs and climate space maps.</p><p>The evaluation of the software demonstrates good performance when compared to existing interpretations. The standardization method employed in habitat reconstructions, designed to enable the inter-comparison of samples and sites without the interference of differing numbers of species and individuals, also appears to be robust and effective. Quantitative climate reconstructions can be easily undertaken from within the software, as well as an amount of predictive modelling. The use of jackknifing variants as an aid to the interpretation of climate reconstructions is discussed, and suggested as a potential indicator of reliability. The combination of the BugStats statistical system with an enhanced MCR facility could be extremely useful in increasing our understanding of not only past environmental and climate change, but also the biogeography and ecology of insect populations in general.</p><p>BugsCEP is the only available software package integrating modern and fossil coleopteran data, and the included reconstruction and analysis tools provide a powerful resource for research and teaching in palaeo-environmental science. The use of modern reference data also makes the package potentially useful in the study of present day insect faunas, and the effects of climate and environmental change on their distributions. The reconstruction methods could thus be inverted, and used as predictive tools in the study of biodiversity and the implications of sustainable development policies on present day habitats.</p><p>BugsCEP can be downloaded from http://www.bugscep.com</p>