The daily uncertainty concerning tumor localization is one of the major problems during the course of radiation therapy. Image guided-radiation therapy (IGRT) can be used to improve the localization and adjustment of the planning target volume. The aim of this work was to evaluate both the IGRT technique used for prostate cancer patients at the department of the Karolinska University Hospital and an alternative on-line adaptive radiation therapy (ART) method with an On-Board Imager (OBI). In the first part of the thesis 2D and 3D image registration with an OBI were compared. Ten prostate cancer patients were involved in the analyses. Two different statistical tests were used to determine significant systematic deviations between the two methods. The second part concerns daily dose verifications and dose plan reoptimization of one intensity modulated radiation therapy (IMRT) prostate cancer patient treated with IGRT. The study was based on cone-beam computed tomography (CBCT) images acquired at 6 different treatment fractions. The risk of developing late rectal and bladder toxicity was quantified using normal tissue complication probability (NTCP) calculations. Additional measurements on an Alderson phantom were performed to verify the accuracy of using the CBCT images for dose calculations. A statistically significant difference between the 2D-2D and the 3D-3D match applications could be observed in lateral and longitudinal direction. However, the effect differed among the patients. The phantom measurements showed small dose deviations between the CT and CBCT image, with a mean dose increase to the prostate and seminal vesicles (SV) of 2.5 %. The daily dose to the prostate and SV of the IMRT patient showed to be satisfactory. The daily dose to the rectum did not exceed the prescribed rectal dose except at one treatment fraction and the highest risk of developing late rectal toxicity was about 10.4 %. Large daily bladder dose variations were observed and at two treatment fractions the bladder dose restrictions were exceeded. With a reoptimization process of the dose plan, the dose to the bladder could be reduced while conserving the dose to the target. This work shows that for these specific patient cases appropriate doses to the prostate and SV can be delivered with IGRT. However, introducing a suitable ART method could lead to a reduction of inter-fractional rectal and bladder dose variations.

The seismic cone penetration test (SCPTu) is the most efficient means for geotechnical site characterization and the evaluation of seismic ground hazards. In this thesis, software systems including ShearPro, ClusterPro, and InSituData, are developed to automate post processing of these SCPTu data. ShearPro is developed to automate the post-processing of the shear wave signals. ClusterPro uses the proposed three-dimensional cluster analysis approach for soil stratification. InSituData facilitates the post processing of penetration data for seismic ground hazards analysis. A new three-dimensional soil classification chart is also proposed in this thesis to help discern soil layers that may be subject to seismic ground hazards, such as loose liquefied sands and silty sands. These methods are then applied to SCPTu data collected at previously-identifed paleoliquefaction sites located in the New Madrid Seismic Zone (NMSZ). For liquefaction evaluation, the cyclic stress ratio (CSR) is computed using site response analysis by DeepSoil and a measured profile of shear waves derived from the 30-m SCPTU soundings and deep suspension loggings in AR and TN. The natural resistance of the soil to liquefaction, termed the cyclic resistance ratios (CRRs), is evaluated based on both deterministic procedures and probabilistic procedures. Based on liquefaction evaluation results at selected paleoliquefaction sites, regional CRR criteria for liquefaction are developed for the NMSZ. As even the latest major earthquakes in NMSZ occurred nearly 200 years ago, aging effects might be an important factor to consider in utilizing the liquefaction criteria to assess the seismic parameters associated with the previous earthquakes. The aging effects in the NMSZ were investigated through large scale blast-induced liquefaction tests conducted in the NMSZ. Then a procedure to estimate seismic parameters associated with previous earthquakes is proposed. It utilizes both the liquefaction criteria based on SCPTu tests and the empirical attenuation relations developed for the corresponding regions. The approach is validated through data evaluation related to the 1989 Loma Prieta earthquakes in California and then applied to previous historic earthquakes in the NMSZ.

This research study developed basic dynamic models that can be used to accurately predict the response behavior of a near-shore wind turbine structure with monopile, suction caisson, or gravity-based foundation systems. The marine soil conditions were modeled using apparent fixity level, Randolph elastic continuum, and modified cone models. The offshore wind turbine structures were developed using a finite element formulation. A two-bladed 3.0 megawatt (MW) and a three-bladed 1.5 MW capacity wind turbine were studied using a variety of design load, and soil conditions scenarios. Aerodynamic thrust loads were estimated using the FAST Software developed by the U.S Department of Energy’s National Renewable Energy Laboratory (NREL). Hydrodynamic loads were estimated using Morison’s equation and the more recent Faltinsen Newman Vinje (FNV) theory. This research study addressed two of the important design constraints, specifically, the angle of the support structure at seafloor and the horizontal displacement at the hub elevation during dynamic loading. The simulation results show that the modified cone model is stiffer than the apparent fixity level and Randolph elastic continuum models. The effect of the blade pitch failure on the offshore wind turbine structure decreases with increasing water depth, but increases with increasing hub height of the offshore wind turbine structure.

This thesis presents a geometry design method to generate the surfaces of the globoidal cam with the conical roller follower. Based on the trace of the rigid body and the theory of differential geometry, the conjugate surfaces can be the offset surfaces of the ruled surface. With different roller¡¦s axial height, its radius and the meshing vector also be changed. For this reason, the contact points on the outward roller are hard to find. To overcome this problem, we propose the triangular graph with meshing angle, it can present the vector quantity caused from the motion angle. We replace it into the procedures of the rigid body transformation method to derive the cam surfaces with the conical roller follower. Furthermore, two models with modified sine and constant velocity motion curves are generated and analyzed.

Take the Quadrangular-Pyramid-Shaped Fiber Endface(QPSFE) and the Conical-Wedge-Shaped Fiber Endface(CWSFE) for example, the present procedure of grinding asymmetric optical fiber endface demands three to four steps. These steps take time and are lack of repeatability and high yield. Aim at the shortcomings, this study develops a set of mechanism to attach to the original optical fiber grinding machine. The mechanism makes the normal pressure between the endface and the grinding plate change periodically to modify the removing rate of the material, thus enables the clipped flat endface of the optical fiber be ground into an elliptic-cone-shaped in a single grinding step, and then becomes a lens after its tip being fused by the arc. This mechanism reduces the fabricating time and cost, and consequently improve the economic benefits as well by simplifying the complicated manufacturing processes that represented before. Besides, for its single-step grinding characteristic, the offset between the center of the fiber and the elliptic-cone can thus be slashed to promote the yield. This study reviews the anterior references, including the papers and the patents, to begin, and then proposes the current means to compare with. Its contents involve the development of the forming principle, which proposes how the variation of the normal pressure takes influence on the removing rate of the material, and the required mechanism for the design procedure. The mechanism, the research result, and those needed to be ameliorated will be demonstrated in the conclusion and discussion part, so as to offer the investigating direction in the future.

A new scheme of asymmetric elliptic-cone-shaped microlens (AECSM) employing a single-step fabrication technique for efficient coupling between the high-power 980nm laser diodes and the single-mode fibers is proposed. The asymmetric elliptic-cone-shaped fiber endface (AECSFE) was fabricated by a single-step grinding and polishing a cleaved fiber by applying a periodically variable torque on the fiber ferrule to change the grinding pressure. The periodically variable torque was made by an eccentric mass with a constant rotation speed double that of the fiber. After the AECSFE was formed, an AECSM was obtained by heating the fiber tip in a fusing splicer. In comparison with the previous works on asymmetric fiber microlenses fabricated by the multi-step processes with complicated fabrication, the advantages of the AECSM structure for achieving high coupling are a single-step fabrication, a reproducible process, and a high-yield output. In this study, we demonstrated that the average grinding offset of the AECSM structure for 30 measurements was about 0.4 £gm, the average coupling efficiency was 71%, and the maximum of the measured coupling efficiency was 83%. The yield of the AECSM for coupling efficiency over 70% was 47%, for coupling efficiency over 60% was almost 100%.

In this thesis, new effective and efficient implementation structures of three-dimensional (3D) spatio-temporal (ST) Finite Impulse Response (FIR) uniform and non-uniform cone and frustum filters using well-known filter banks are investigated. The performance of the proposed implementation structures for 3D ST FIR uniform and non-uniform cone and frustum filters are investigated for 3D broadband beamforming in radio astronomy applications. First, implementations of two 3D ST uniform FIR cone filters are investigated. The 3D cone filters are designed by cascading either the well-known uniform quadrature mirror – cosine-modulated (QM-CM) filter bank or directly designed filter banks (DDFBs), with 2D low-pass circularly-symmetric spatial filters. In addition, two 3D ST uniform FIR frustum filters are derived from the cone filters by implementing partial bands of the filter banks with corresponding 2D spatial filters. The performance of the proposed implementation structures for 3D ST uniform QM-CM and DDFBs cone and frustum filters are evaluated using broadband beamforming signals in radio astronomy applications. The performance of the QM-CM and DDFBs cone and frustum filters shows improvement in terms of Signal-to-Interference-plus-Noise ratio (SINRs) over existing 3D ST cone and frustum filters. In addition to their effective performance, these cone and frustum filters can be efficiently implemented with equivalent or less computational complexity compared to existing methods. Second, implementations of two 3D ST non-uniform cone and frustum filters are explored. These cone and frustum filters are obtained by cascading either QM-CM or DDFBs non-uniform filter banks, with 2D low-pass circularly-symmetric spatial filters. The motivation for the 3D ST non-uniform cone and frustum filters is to achieve better approximation at low temporal frequencies than using the uniform ones. The performance of the 3D ST non-uniform cone and frustum filters is evaluated and compared with the performance of the uniform 3D ST cone and frustum filters. Results indicate that the performance of the proposed 3D ST non-uniform QM-CM and DDFBs cone filters shows some improvement in selective filtering compared to the performance of 3D ST uniform cone filters. / Graduate / 0544 / hussamss@uvic.ca

Throughout neuronal development, bouts of spontaneous electrical activity are critical for the proper wiring of neuronal connections. Alterations in firing activity can affect growth cones, which tip developing and regenerating neurites and are responsible for the integration of extracellular guidance cues into pathfinding behaviors. While growing evidence implicates gaseous signaling molecules, nitric oxide (NO) and carbon monoxide (CO), as modulators of neuronal firing activity, less is understood about how they affect growth cone motility. Therefore, in this dissertation, I focus on how NO and CO affect electrical activity of developing and regenerating neurons and how these effects translate into changes at the growth cone level. The specific goals of this dissertation were to investigate 1) the neuron-type-specific effects of NO on growth cone motility; 2) the role of CO in the regulation of neuronal firing activity and excitability; and 3) the role CO plays in the regulation of growth cone motility. Using the well-established developmental model, Helisoma trivolvis, neurons were isolated in single-cell culture allowing for the maximal control over environmental conditions for the direct characterization of NO and CO. In the study of NO, differences in B5 and B19 growth cone responses to NO were due to neuron-type-specific differences in action potential duration. Moreover, the non-responsive B19 growth cones could be made responsive to NO treatment upon the pharmacological broadening of its action potentials. While NO has been found to increase firing activity, the study of CO revealed that CO had the opposite effect on electrical activity, silencing spontaneous firing activity and decreasing neuronal excitability. The study of CO on growth cone motility showed that CO increased growth cone filopodial length through a soluble guanylyl cyclase/protein kinase G/ryanodine receptor mediated pathway without inducing robust increases in growth cone calcium concentration. Taken together, this dissertation reveals new insight into how NO and CO regulate electrical activity and growth cone motility, providing evidence for these gases as important signaling messengers during for the development and regeneration of nervous system.

Landscapes evolve through a number of processes in response to a wide range of forcing mechanisms. Many of the processes that drive landscape evolution occur at the interface between fluid and sediment. Sediment transport leads to changes in topography that, in turn, influence fluid flow. Feedback mechanisms between topography and fluid flow can lead to the formation of patterns, such as sand ripples, dune fields, parallel channel networks, and periodically spaced valleys. In many cases, the development and evolution of patterns within landscapes are heavily influenced by environmental conditions. Therefore, given relationships between landform features and the underlying processes, present-day landscapes have the potential to be used to infer a record of climatic conditions over the course of their development. An inability to make direct observations over geologically relevant timescales makes it difficult to study the processes that influence landscape evolution. Mathematical models provide a means of quantitatively linking natural patterns and landscape features with physical processes. Patterns in landscapes also provide a simple means of testing quantitative representations of geomorphic processes. In this work, we develop landscape evolution models to study the development of debris-flow-dominated hillslopes, rill networks, and cinder cones. Through a combination of theoretical modeling, analysis of experimental data, and remote sensing data, we attempt to better understand each of these three systems. While each system is interesting in isolation, these and similar studies add to our knowledge of the mathematical representations of processes that are used more generally within the study of landscape evolution.

3d αναπαράσταση με παράλληλη επεξεργασία μέσω Matlab / 3D cone beam representation using Matlab