Concerns arise in radiation therapy for head and neck cancers when dental prostheses are involved. These prostheses are high-density materials that induce image artifacts in computed tomography (CT) scans used for dose calculation. Two approaches are utilized in mitigating the impact of these artifacts on the accuracy of dose calculation. First, metal artifact reduction (MAR) algorithms or dual-energy CT scans are used to recover image quality. Second, a planning protocol is adopted whereby residual artifacts are manually contoured and assigned appropriate densities. This study evaluated the current planning process using a holistic approach. In this work, an axial section of a head phantom containing dental implants at the level of the oral cavity was constructed and scanned using various protocols on two different commercial scanners; Philips and Siemens, to assess the appearance of artifacts. An MVCT image set was merged with the corresponding kVCT image to improve visualization of the dental implants for use in density overrides. Three ion chamber measurement points in the simulated mouth facilitated the determination of measured dose which was compared to calculated dose at various single beam irradiation geometries. The influence of density override values on agreement between calculation and measurement was investigated for each geometry and imaging modality. Percent error was computed, and initial results compared to results manipulated by use of; a CT density table (Head); density overrides of walls and wax; and density overrides of walls, wax, and effective density of saturation regions. The study established that normal tissue doses are not significantly affected by metal artifact reduction (MAR) algorithms, and improvements in dose calculation compared to uncorrected CT images are small. Furthermore, the inclusion of a MVCT image set improved implant visualization reducing the treatment planning time while providing more information. Evidence led to the deduction that manual overrides of effective density for clipped OMAR CT pixels reduce dose calculation errors. When the phantom was configured with amalgam and Co-Cr-Mo alloy dental implants the effective density of these implants was found to be 4.5 g/cm3. When the phantom was configured with implants containing amalgam and gold, the effective density of amalgam in the presence of gold was 5.5 g/cm3 while gold had an effective density of 6.5 g/cm3. The median and maximum range of errors for the uncorrected images were ± 0.6 % and 7.4% respectively for the phantom configured with amalgam and Co-Cr-Mo (tray one) and ± 0.5 % and 18.1 % respectively for the phantom containing amalgam and gold (tray two). The median and maximum range of errors for the corrected images after applying overrides of effective densities were ± 0.5 % and 4.7% respectively for tray one and ± 0.3 % and 7.7 % respectively for tray two. In conclusion, introduction of density overrides of walls, wax and effective density of high-density materials can reduce the errors induced by metal artifacts and improve the accuracy of dose calculations in treatment planning systems to deliver the relevant dose to a target organ. / Thesis / Master of Science (MSc)

Usually, image compression techniques that use only one transform exhibit some poor properties. For instance, the Discrete Cosine Transform (DCT) cannot efficiently represent high frequency components, resulting in blurred images. The Multiple Bases Representation (MBR) compression technique, which uses two or more transforms, is found to be superior to the single transform techniques in terms of representation efficiency. However, some bits in the MBR representation are needed to track the basis information. The MBR image quality is deteriorated by discontinuities at block boundaries, as is the standard DCT transform. In this thesis, test images are distorted by MBR compression using a Recursive Residual Projection algorithm. This algorithm is a sub-optimal method to find the best basis vector subset for representing images based on multiple orthogonal bases. The MBR distorted images are reconstructed by the iterative method of Projection onto Convex Sets (POCS). Many constraints that form convex sets are reviewed and examined. Due to the high distortion at the block boundaries, some constraints are introduced particularly to reduce artifacts at the boundaries. Some constraints add energy to the reconstructed images while others remove energy. Thus, the initial vectors play a key role in the performance of the POCS method for better MBR reconstruction. This thesis also determines the most appropriate initial vector for each constraint. Finally, the composite projections associated with the sign, minimum decreasing and norm-of-slope constraints are used to improve the reconstruction of the MBR distorted images and the effect of ordering of the projections is investigated. / Master of Science

As the world population ages, hospital discharges of geriatric patients to nursing homes have increased. Patients with peripherally inserted central catheters (PICCs) are routinely discharged with the catheters in place. PICCs, only capable of being tracked through x-ray imaging, will routinely experience complications due to thrombosis or accidental dislodgement from poor at-home care. Routinely, elderly patients will be forced to revisit the hospital to have the catheter replaced using x-ray imaging, exposing them to hospital borne illness. Catheters with the capability to be tracked without the need of x-ray imaging would greatly benefit the ill and elderly, providing decreased stress to the patients and increase nursing home capabilities. This project seeks to develop the field of real-time ultrasound tracking of polymeric medical devices, through fabrication of ultrasound responsive polymer-glass composites. Optimal composition will be researched through three complimentary approaches. The first approach seeks to develop a polyurethane-glass microparticle composite to understand the relationship between microparticle loading and ultrasound imaging. In the second approach, manufacturing and end-use complications will be simulated to evaluate the effects on mechanical and ultrasonic properties. Furthermore, impacts from in-vitro long term catheterization to the sample mechanical and ultrasound morphologies would be analyzed. In the third approach, optimization from the previous approaches would assist in the replacement of medical grade polyurethane with medical grade thermoset silicone in hopes to prove the ability for the research to be transferable to other medical polymeric devices. The stated approaches will be useful for setting a path towards the development of ultrasonic imaging as the standard for medical device tracking. / Doctor of Philosophy / As the world population ages, hospital discharges of geriatric patients to nursing homes have increased. Patients with peripherally inserted central catheters (PICCs) are routinely discharged with the catheters in place. PICCs, only capable of being tracked through x-ray imaging, will routinely experience complications due to poor at-home care. Routinely, elderly patients will be forced to revisit the hospital to have the catheter replaced using x-ray imaging, exposing them to hospital borne illness. Catheters with the capability to be tracked without the need of x-ray imaging would greatly benefit the ill and elderly, providing decreased stress to the patients and increase nursing home capabilities. We hope to develop the field of real-time ultrasound tracking of plastic medical devices, through production of ultrasound activated plastic devices.

The aims of this dissertation study are 1) to examine how the interplay of motivation, artifacts, and task interconnectedness affect users' flow experience, 2) to understand users' multitasking patterns by analyzing approaches and strategies in multitasking environments through a participatory design session, and 3) to come up with design insights and implications for desired multitasking environments based on findings from the quantitative and qualitative data analysis and synthesis. This dissertation employed the PAT (Person-Artifact-Task) model to examine factors that affect users' flow experience in computer-mediated multitasking environments. Particularly, this study focused on users' flow experience - sense of control, focused attention, curiosity, intrinsic interest and interactivity - in the context of multitasking. The dissertation begins with perspectives on human multitasking research from various disciplines. Emphasis is placed on how researchers have defined the term multitasking and the scope of previous multitasking research. In addition, this study provides definitions of the term task switching, which also has been used to describe human multitasking. The second section of this dissertation focuses on the literature, which characterizes factors and theoretical frameworks of human multitasking research. In this section, human multitasking factors were classified into internal and external factors to analyze factors from the micro to the macro perspective. More detailed definitions and comparisons are also addressed. To summarize and conclude the literature review, this study provides a synthesis framework of internal and external factors of human multitasking contexts. In section III, this dissertation introduces theoretical frameworks that include the constructs of the PAT (Person-Artifact-Task) model and flow model. The next three sections present the research design and two research methods - the experiment and participatory design. The results and discussion section includes the implications of interpreting people's flow experience with motivation, artifact (technology affordance type), and task interconnectedness through the PAT model. The study findings and implications should extend our understanding of multitasking behaviors and contexts and how the interplay of person, artifact, and task factors affects humans' flow experience. A concluding chapter explores future work and design implications on how researchers and designers can take contextual factors into consideration to identify the most effective multitasking in computer-mediated environments. / text

The aim of the submitted thesis is a comparison of symbolism of a double in Georges Rodenbach's Bruges-la-Morte and Romány tří mágů of Jiří Karásek ze Lvovic. We will focus maily on death as a key motif of literature at the fin de siècle and a motif that is, in works we are examining, closely linked with the existence of a double. We will inspect motif of a double in the context of psychological states of mind. The choice of compared texts was motivated by the process of self disintegration. The process of self disintegration is closely connected with the process of depersonalisation which appears when a subject makes contact with a soulful space or a object. Cities (Bruges, Venice, Prague) which are the scene of this self disintegration take a special place in the literature of symbolism as a urban space of art and death at once. Despite mutual relation of life and art, the strange tension, and the phenomenon of annihilation, is still present within this relation.

The thesis is an investigation of global exploitation of nature, use of productive landscapes and itsremaining structures as the cultural historical environment. The further aim has been to seek analternative approach against a large-scale utilization of the environment through an elaborativeprocess of an architectural intervention, combining public space and local production. The thesisbackground is exploring the human activities and outcomes in exploited landscapes and is departingfrom the issue of an anthropocentric approach toward the environment. Further on, it analyzesdifferent mindset on natural resources in relation to the building of civilization and society, the ruralcontra the urban. Against the background of a linear withdrawal of resources and in the long-termlandscape productive decline, the aim is to prototype a productive infrastructure that works in acyclical manner, re-using energy and being less dependent on resources at a large-scale. Departingfrom the regional environment in Umeå and its traditional agricultural and former industrial use ofthe landscape, the intervention is tested by considering the principles of sustained life by theimmediate landscape. The aim has been to analyze and translate principles at the scale of landscape,farm and unit into a reproducible, productive infrastructure that harvest energy from recreation,cultivation, production and the condition of the topography.

<p>My dissertation, <&ldquo;>Transcending Borders: The Transnational Construction of Mexicanness, 1920-1935,<&rdquo;> examines the conflicting attitudes towards "Mexicanness" or <italic>mexicanidad</italic> both in Mexico and the United States, an area that, Jos<&eacute;> Lim<&oacute;>n, conceptualizes as "Greater Mexico." Beginning with an analysis of the Mexican postrevolutionary state's construction of nationalist culture, I argue that the transnational invention of Mexicanness through the circulation of the Aztec artifact reveals the possibilities for people of Mexican descent to reclaim public space and cultural citizenship on both sides of the U.S.-Mexico border. I examine the construction of Mexicanness through an analysis of the limitations of Mexican post-revolutionary literary production in generating a clear vision of Mexican nationhood as well as the possibilities for nation building offered by public spaces such as the museum and the monument (an outdoor museum). Tracing the cultural manifestations of Mexican nationhood as expressed by the state and by people of Mexican descent is essential to understanding how the nation is practiced and thus intimately intertwined with the practice of citizenship. Through an interdisciplinary analysis of the Aztec artifact's various incarnations as an archaeological artifact, created artifact, and spurious artifact, I contend that the artifact represents an alternative text for the study of nationalism in its ability to narrate a national identity ultimately shaped beyond Mexico's geographical borders.</p> / Dissertation

Since the Software Engineering Institute published the Capability Maturity Method Integration (CMMI) in 2003, many software firms have implemented it to enhance its software quality assurance and international collaboration. Analysis and design phases are two important phases for the software development. The artifacts of these two phases mainly represented using the structured technique or the object-oriented technique. This study proposed a methodology which provides guidelines to compare the artifacts of these two techniques for an embedded system. The research methodology is articulated using the design science research methodology. A usability valuation with a real-world embedded system case is performed to demonstrate its applicability. The results provide evidences to enhance our understanding about the strength and weakness of these two nalysis and design techniques.

The goal of this thesis is to improve Usability and functionality of a tool for artifact management, which applies taxonomic paths for categorizing artifacts. The main issues of using the taxonomic paths are used for categorization and should improve the precision when retrieving documents. The results show the improvements in functionality and usability of the artifact manager. This thesis explains about Usability, re-engineering, and necessary infrastructure to improve the performance of the artifact manager tool.At the end of the thesis necessary modifications has been done to improve usability and functionality of artifact manager

While collaborative engineering in outsourcing projects presents potential benefits to the partners, it involves some risks and reasonable concerns. First, a poor mechanism of data exchange and data communication can lead to loss of effectiveness and efficiency of the project. Second, collaborative engineering requires partners to adapt a common business process, which often means moving away from a familiar way of working. Thus, it is crucial to find an optimal way a collaboration can be achieved with the lowest waste due to changes in communication practices, and losses in efficiency due to asynchronous processes or big amount of exchange data. The main goal of this thesis is to connect two aspects in a collaboration: data-exchange and process-based execution. The main reason to do so is to resolve a problem with a weak control over information needed for successful project execution. Three research methods are used in this work: a case study to analyze how collaboration is performed in the industry and which problems exist; a literature review to understand how existing collaboration tools can be adapted to help solving the identified problems; and a prototypical implementation to show how automated versioning of engineering knowledge can be added to the union of data exchange and process-based aspects. The case study was performed and a list of business requirements was presented. Based on the list of requirements, solutions within the literature were searched. A process-based artifact-centric concept was applied to the case study scenario. Objectives are achieved, however, the problem was shown on an example of one company, which presents a limitation, as generalization has not been proved.