Graduation date: 1993

We describe a method to solve the stereo correspondence using controlled eye (or camera) movements. These eye movements essentially supply additional image frames which can be used to constrain the stereo matching. Because the eye movements are small, traditional methods of stereo with multiple frames will not work. We develop an alternative approach using a systematic analysis to define a probability distribution for the errors. Our matching strategy then matches the most probable points first, thereby reducing the ambiguity for the remaining matches. We demonstrate this algorithm with several examples.

Background: Stories may be an effective tool to communicate with and influence patients because of their ability to engage the reader. Objectives: To develop story booklets and evaluate their effectiveness compared to standard information sheets for parents of children attending the emergency department (ED) with a child with croup. Methods: A systematic process was followed to develop and pilot-test the story booklets. Parents were randomized to receive story booklets or standard information sheets during their ED visit. The primary outcome of change in anxiety during the ED visit was assessed using the State Trait Anxiety Inventory, which was completed upon recruitment and at discharge. Follow-up telephone interviews were conducted at 1 and 3 days post-ED visit to gather information on secondary outcomes: symptoms, expected anxiety for future croup, satisfaction, regret, knowledge, return for medical care, and resource use. Telephone interviews were conducted every other day until symptoms resolved or until day 9. Outcomes were compared using independent-groups t-tests, Mann Whitney tests, or Chi-square tests. Results: There was no significant difference in the primary outcome of change in parental anxiety between recruitment and ED discharge. The story group (n=129) showed significantly greater decision regret regarding their decision to go to the ED than the comparison group (n=126) (p<0.001). The story group reported quicker resolution of symptoms: median days to no symptoms 3 versus 5; the survival distributions were significantly different (p=0.032). There were no differences for the remaining outcomes. Conclusions: This study provides preliminary evidence regarding the use of stories in the ED for an acute, self-limiting condition and contributes to a growing evidence matrix identifying when, where, and for whom storytelling may be most effective. Reasons for lack of significance for the primary and other outcomes may relate to choice of outcome, timing of outcome assessment, or disconnect between the intervention and needs of the end-user. Further research is needed to corroborate the significant findings and examine their underlying mechanism. An examination of risk of bias in a sample of pediatric trials demonstrates that there is room for improvement in the design, conduct, and reporting of research related to child health and provides direction for future research.

Thesis (Ph.D.)--York University, 2004. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 191-208). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ99226

The purpose of this work is to evaluate the performance of a specific ac drive topology that is of current interest in industry. With the increasing pressure for compliance with IEEE-519 and other international harmonic standards, many ac drive manufacturing companies are seeking innovative and cost effective solutions for controlling the amount of harmonics produced at the point of common coupling (PCC). The proposed topology is a potential alternative to the three-phase diode bridge which is the conventional rectifier topology for non-regenerative applications. The work of this thesis explains the theory of operation, control algorithms, and potential improvement strategies for the proposed "half-controlled" boost rectifier topology. The entire ac drive system with load is then modeled and the results verified using the Simulink simulation package. It is shown that the proposed topology has several distinct advantages over a traditional diode rectifier such as improved total harmonic distortion (THD) of the current waveforms, dc bus voltage regulation, and power factor control. In addition, these advantages are created at a price point which is significantly lower than that of a conventional fully-controlled pulse-width modulated (PWM) rectifier. The main disadvantage is that the current waveforms in the utility contain even harmonics which may cause significant problems in the power system.

The purpose of this work is to evaluate the performance of a specific ac drive topology that is of current interest in industry. With the increasing pressure for compliance with IEEE–519 and other international harmonic standards, many ac drive manufacturing companies are seeking innovative and cost effective solutions for controlling the amount of harmonics produced at the point of common coupling (PCC). The proposed topology is a potential alternative to the three-phase diode bridge which is the conventional rectifier topology for non-regenerative applications. The work of this thesis explains the theory of operation, control algorithms, and potential improvement strategies for the proposed “half-controlled” boost rectifier topology. The entire ac drive system with load is then modeled and the results verified using the Simulink simulation package. It is shown that the proposed topology has several distinct advantages over a traditional diode rectifier such as improved total harmonic distortion (THD) of the current waveforms, dc bus voltage regulation, and power factor control. In addition, these advantages are created at a price point which is significantly lower than that of a conventional fully-controlled pulse-width modulated (PWM) rectifier. The main disadvantage is that the current waveforms in the utility contain even harmonics which may cause significant problems in the power system.

Controlled Source Tensor Magnetotelluric (CSTMT) ground measurements were executed on the Hallandsåsen horst where a major tunnel is under construction. The instrument system EnviroMT are used for this purpose. The major research aspect of this thesis has been to form an opinion of the effectiveness of the method by comparing the results from the CSTMT survey with a prior investigation performed with the DC resistivity method. Another important part of this thesis has been to compile the basic and fundamental CSTMT and RMT theory, in a way that people outside the EM community easily can be introduced to the subject. When comparing the different inversion models from the CSTMT and DC resistivity surveys one can see differences in the depth at which the conductors are resolved. In the CSTMT inversion models (TE+TM) there are two conductors that possibly can reach the depth of the tunnel in construction. These conductors are not resolved at the deeper structures in the DC resistivity models. Whether the conductors in the CSTMT inversions (TE+TM) truly extend to the depth at which they are modeled, or if they in deeper parts are artificial effects of regularisation in the inversion cannot be said for sure. Accounting for the low frequencies utilised in the TE mode, one has very strong arguments that the deep conductors seen in the CSTMT model are true. The TE-mode models have shown to be much less affected by the complex problems of near field effects in comparison with the TM-mode models. The evidence of the near field effects is very prominent in the TM-mode phase, but in the phase of the TE-mode one can not see any such tendencies. However, one can see a discontinuity in the same part of three profile lines which shows that the data is disturbed but not nearly as much as in the TM-mode. The apparent resistivity seems to be over all less affected by the near field effects. In the apparent resistivity of the TE-mode, one can not discern any near field effects at all. In the TM-mode, the apparent resistivity shows higher apparent resistivity than the real apparent resistivity in the near field. To receive more information about the deeper structures, lower controlled source frequencies were allowed in the TE-mode than in the TM-mode inversion models. The RMS in the TE-mode inversions has not been deteriorated, which is an another indication that the TE mode is not very disturbed by the near field effects. The RMT inversion models are shown to be heavily biased in the deeper parts to which the RMT data are insensitive and regularization determining the outcome of the inversion. One can also see that regularisation is influencing the whole inversion model. In the shallow subsurface the inversion models should be same for CSTMT and RMT, but one can see differences in resistivity between the models. The real induction arrows show features that are not as clearly displayed in either the phase or apparent resistivity. It seems that the real induction arrows are better at detecting lateral differences in conductivity in a more resistive media, than the phase and apparent resistivity.

Six experiments were conducted to examine the factors modulating the size of age differences in recollection. The research presented in the current thesis was guided by the notions of self-initiated processing and environmental support. Older and younger adults’ performance in recollection was measured by Jacoby’s (1990) process dissociation procedure (PDP); the age differences as a function of self-initiated processing demands of the task and the amount of support provided to the participants were assessed by manipulating the encoding (Experiments 2.1, 2.2, and 2.3) and retrieval (Experiments 3.1, 3.2, and 3.3) contexts. Experiments 2.1, 2.2, and 2.3 examined interactions of aging and encoding contexts. Recollection under baseline conditions (i.e. visually presented words) was contrasted with recollection of items encoded under contexts that are assumed to enhance memory. The results showed differential age-related patterns of benefits from encoding conditions: Presenting pictures with words benefited older adults more than younger adults; word generation benefited both groups equally; and presenting sound effects with visual words benefited younger more than older adults. Experiments 3.1, 3.2, and 3.3 investigated age-related changes in retrieval processes and their interactions with retrieval contexts. In each of the three experiments, some of the test lists were constructed so that participants had to recollect specific aspects of the encoding event to differentiate between the to-be-included and to-be-excluded items, whereas other test lists were constructed so that they only had to recollect general aspects. Older adults showed reduced levels of recollection than younger adults for the high-specificity test lists only (Experiment 3.1). Encoding manipulations improved (Experiment 3.2) or reduced (Experiment 3.3) recollection performance but the effects did not interact with test, whereas DA at retrieval (Experiment 3.3) in younger adults partly mimicked aging. In summary, the six experiments showed that older adults have greater difficulties in spontaneously carrying out distinctive and integrative processes at encoding, and in accessing specific information at retrieval compared to their younger counterparts. These age-related changes further interact with the processing demanded or afforded by the encoding and retrieval conditions.

The use of polysaccharides as building blocks in the development of drugs and contrast agents delivery systems is rapidly growing. This can be attributed to the outstanding virtues of polysaccharides such as biocompatibility, biodegradability, upgradability, multiple reacting groups and low cost. The focus of this thesis was to develop and characterize novel starch based hydrogels and nanoparticles for delivery of drugs and imaging agents. To this end, two different systems were developed. The first system includes polymer and nanoparticles prepared by graft polymerization of polymethacrylic acid and polysorbate 80 onto starch. This starch based platform nanotechnology was developed using the design principles based on the pathophysiology of breast cancer, with applications in both medical imaging and breast cancer chemotherapy. The nanoparticles exhibited a high degree of doxorubicin loading as well as sustained pH dependent release of the drug. The drug loaded nanoparticles were significantly more effective against multidrug resistant human breast cancer cells compared to free doxorubicin. Systemic administration of the starch based nanoparticles co-loaded with doxorubicin and a near infrared fluorescent probe allowed for non-invasive real time monitoring of the nanoparticles biodistribution, tumor accumulation, and clearance. Systemic administration of the clinically relevant doses of the drug loaded particles to a mouse model of breast cancer significantly enhanced therapeutic efficacy while minimizing side effects compared to free doxorubicin. A novel, starch based magnetic resonance imaging (MRI) contrast agent with good in vitro and in vivo tolerability was formulated which exhibited superior signal enhancement in tumor and vasculature. The second system is a co-polymeric hydrogel of starch and xanthan gum with adjustable swelling and permeation properties. The hydrogels exhibited excellent film forming capability, and appeared to be particularly useful in controlled delivery applications of larger molecular size compounds. The starch based hydrogels, polymers and nanoparticles developed in this work have shown great potentials for controlled drug delivery and biomedical imaging applications.

Thalassemia, a genetic blood disorder, occurs as a result of deformations of hemoglobin structures. Patients with thalassemia develop iron overload from chronic blood transfusions and require regular iron chelation to prevent potentially fatal iron-related complications. Deferiprone is a commercially available drug used as iron chelator for the treatment of thalassemia but the very long-term effectiveness is not clearly known yet. Therefore, some studies were carried out to find effective alternative drugs or delivery methods for treatment of thalassemia. Controlled delivery, which offers safer, more convenient, and more effective means of administering actives, seems promising with this respect. Chitosan, a natural biopolymer produced from deacetylation of chitin, has a variety of promising pharmaceutical uses and is presently considered as a novel carrier material in drug delivery systems. In this study, chitosan microspheres having different degree of deacetylation (DDA) and containing Deferiprone were prepared by oil/water emulsion method and by crosslinking with gluteraldehyde. Particle size, SEM, and in vitro drug release analysis were performed. The average sizes of the prepared microspheres increased with increasing degree of deacetylation of chitosan and with decreasing crosslinking degree. In vitro drug release studies showed that, the release rate of Deferiprone increased as the crosslinking degree increased, contrary to the expectations. This is explained by the crystalline structure of lightly crosslinked chitosan which have ordered and dense structure causing slower release rate for Deferiprone compare to highly crosslinked structures. In the second stage of the study, chitosan films hardened with gluteraldehyde were prepared by film casting method. IR, DSC and mechanical analysis were performed. For the films with various crosslinking degrees, it was found that UTS values differed from 50.6 MPa to 102.7 MPa, mean elastic modulus values differed from 3328.7 MPa to 3790.1 MPa and SAB values differed from 2.06% to 4.29%.