2024-03-28T12:56:24Z
http://ir.lib.uwo.ca/do/oai/
oai:ir.lib.uwo.ca:etd-4944
2016-04-07T12:34:13Z
publication:earth
publication:geology-etd
publication:faculties
publication:etd
Reflectance and Emission Spectroscopy: Curve Fitting Methods with Application to Impact Glasses and the Varying Grain Size of Planetary Analogue Minerals
Craig, Michael A
Spectroscopy, i.e., the measurement of electromagnetic radiation as a function of wavelength, is arguably the technique most responsible for the majority of what is collectively known about the composition of stars, the distances to galaxies, the age of the universe and so on. Spectroscopy is also the tool most used to discern the mineralogy of planetary bodies remotely. Measuring the speed at which a star is receding and its composition, or the composition of an interstellar cloud of gas are well understood uses of spectroscopy. When it comes to spectroscopies use to discern mineralogy, the scientific literature on the subject of the application of spectroscopy to the solid surfaces of asteroids and the nearby planets would lead one to conclude it too is as robust a measure as that of stellar composition or Doppler shift, although it is not. A number of properties of the target under investigation, namely, mineralogy, grain size, packing (i.e., loose grains versus consolidated rock), phase angle and temperature strongly affect the reflectance and emission spectrum of the common minerals encountered when interrogating planetary surfaces. These effects can be profound and significantly complicate our ability to robustly identify mineralogy when the properties of the surface are not known. The works herein address some of these issues, by firstly, providing a set of methods/functions and a set of guidelines for empirically curve fitting spectra in a robust and repeatable manner. Chapter 2 and its appendices were conceived in an effort to provide the spectroscopic community with a set of curve fitting tools, to be put freely in the hands of spectroscopists in the hopes that the community can see its way to providing fit metrics of spectra presented in the literature with transparency so the metrics can be widely understood and applied. Secondly, the methods presented in Chapter 2 were applied in Chapters 3 and 4 to the spectra of impact glasses and hydrothermal silicate evaporates to aid in their robust identification, and to the effects of significant grain size variation on the most common planetary surficial analogue materials pyroxene, olivine and basalt.
2015-10-22T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/3404
https://ir.lib.uwo.ca/context/etd/article/4944/viewcontent/PhD_Thesis_MCraig.pdf
https://ir.lib.uwo.ca/context/etd/article/4944/filename/0/type/additional/viewcontent/Appendix_2A_MCraig.xlsx
https://ir.lib.uwo.ca/context/etd/article/4944/filename/1/type/additional/viewcontent/Appendix_3A_MCraig.xlsx
https://ir.lib.uwo.ca/context/etd/article/4944/filename/2/type/additional/viewcontent/Appendix_3B_MCraig.xlsx
https://ir.lib.uwo.ca/context/etd/article/4944/filename/3/type/additional/viewcontent/Appendix_3C_MCraig.xlsx
https://ir.lib.uwo.ca/context/etd/article/4944/filename/4/type/additional/viewcontent/Appendix_4A_MCraig.xlsx
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Spectroscopy
Curve Fitting
Impact Glasses
Grain Size
Mars
Asteroids
Geology
oai:ir.lib.uwo.ca:etd-7318
2018-08-02T01:00:32Z
publication:etdlac
publication:biology-etd
publication:biology
publication:faculties
publication:etd
Defective ABA-mediated sugar signalling pathway in an established Arabidopsis thaliana cell suspension culture explains its stay-green phenotype at high sugar concentrations
McCarthy, Avery
An unusual sugar insensitive phenotype was identified in an established cell suspension culture of Arabidopsis thaliana. We characterized the physiology, biochemistry and genetics of the sugar insensitive cell culture, in order to identify factors contributing to the phenotype. Chlorophyll levels of the cell suspension culture were insensitive to high sucrose (6-15% w/v) and maintained a green phenotype. Immunoblotting indicated that levels of key photosynthetic proteins (PsaA, Lhcb2 and Rubisco) increased as a function of external sucrose concentration. The green cell culture was photosynthetically competent based on light-dependent, CO2-saturated rates of O2 evolution as well as Fv/Fm and P700 oxidation. Transcript profiling indicated that key sugar signalling transcripts ABI3 and ABI4 were not detectable in the cell suspension culture, and this was confirmed by qPCR. Because the transcription factors ABI3 and ABI4 are essential for WT sugar signalling, the lack of these transcripts resulted in a sugar insensitive phenotype that mimicked the phenotype of abi3 and abi4 mutant seedlings. Addition of ABA to the external medium failed to rescue the suspension cells from its sucrose insensitivity. We sequenced the genome at over 300-fold coverage, and identified three hundred thousand genetic variants unique to the cell culture, not present in the genomes of twenty-seven Arabidopsis thaliana ecotypes with WT sugar sensitivity. Despite widespread genetic changes in the genome, there were no variations in the promoter regions or regulatory regions of ABI3 or ABI4 that could explain the lack of expression of these transcription factors. We conclude that the genetic change has impacted an unknown regulator of ABI3 or ABI4 impairing their expression resulting in a sugar insensitive phenotype. Because of the genetic variation that has occurred, and because of the unusual sugar and photosynthetic responses, caution must be exercised in the interpretation of physiological and biochemical data obtained from experimental use of this culture in any comparison with wild-type Arabidopsis seedlings.
2018-06-13T21:30:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/5467
https://ir.lib.uwo.ca/context/etd/article/7318/viewcontent/Defective_ABA_mediated_sugar_signalling_pathway_in_an_established_Arabidopsis_thaliana_cell_suspension_culture_explains_its_stay_green_phenotype_at_high_sugar.pdf
https://ir.lib.uwo.ca/context/etd/article/7318/filename/0/type/additional/viewcontent/Table_S1.1.docx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/1/type/additional/viewcontent/Table_S1.2.docx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/2/type/additional/viewcontent/Table_S2.1.docx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/3/type/additional/viewcontent/Table_S2.2.docx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/4/type/additional/viewcontent/Figure_S2.1.doc
https://ir.lib.uwo.ca/context/etd/article/7318/filename/5/type/additional/viewcontent/Figure_S2.2.docx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/6/type/additional/viewcontent/Table_S3.1.xlsx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/7/type/additional/viewcontent/Table_S3.2.xlsx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/8/type/additional/viewcontent/Table_S3.3.xlsx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/9/type/additional/viewcontent/Table_S3.4.xlsx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/10/type/additional/viewcontent/Table_S3.5.xlsx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/11/type/additional/viewcontent/Table_S3.6.xlsx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/12/type/additional/viewcontent/Table_S4.1.docx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/13/type/additional/viewcontent/Table_S4.2.docx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/14/type/additional/viewcontent/Table_S4.3.xlsx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/15/type/additional/viewcontent/Table_S4.4.xlsx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/16/type/additional/viewcontent/Table_S4.5.xlsx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/17/type/additional/viewcontent/Table_S4.6.xlsx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/18/type/additional/viewcontent/Table_S4.7.xlsx
https://ir.lib.uwo.ca/context/etd/article/7318/filename/19/type/additional/viewcontent/Appendix_4.1.docx
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Sugar signalling
Arabidopsis thaliana
Cell suspension culture
Sugar insensitive
ABA Insensitive 4 (ABI4)
ABA Insensitive 3 (ABI3)
RNA-Seq
Whole genome
Biochemistry
Cellular and Molecular Physiology
Genomics
Molecular Biology
Plant Biology
oai:ir.lib.uwo.ca:etd-8517
2021-03-24T17:41:23Z
publication:etdlac
publication:anatomy
publication:faculties
publication:anatomy-etd
publication:etd
Anaplastic Thyroid Cancer: Identification of Candidate Therapeutics and Mechanisms of Disease Progression
Pinto, Nicole
Malignancies derived from follicular cells of the thyroid can be divided into well-differentiated thyroid cancer (WDTC), poorly differentiated thyroid cancer and anaplastic (undifferentiated) thyroid cancer (ATC). While the majority of thyroid cancers are well-differentiated in nature and have an excellent prognosis, ATC is rare, nonresponsive to conventional therapies, and is nearly universally fatal. In this study, I employed high-throughput screening of kinase inhibitors to identify candidate drugs to control ATC and expanded these studies to include a focus on studying the underlying progression from WDTC to ATC. Two compounds, lestaurtinib (JAK2 inhibitor) and flavopiridol (pan-CDK inhibitor) were selected from the high-throughput screen for follow-up studies. Our first study showed that lestaurtinib demonstrated a potent antiproliferative effect and impeded cell migration and colony formation in addition to causing cell cycle arrest following drug treatment. Ex vivo, we used the chick chorioallantoic membrane model to demonstrate that lestaurtinib resulted in a significant decrease in endpoint tumour volume and tumour vascularity, together highlighting an antiproliferative and potentially antiangiogenic effect. In our second study, we found that flavopiridol treatment in vitrohad an antiproliferative effect and induced cell cycle arrest. In vivo, flavopiridol decreased tumour volume and tumour growth over time using a patient-derived xenograft model of ATC. Finally, we sought to determine whether the introduction of a canonical PIK3CA (E545K) mutation, characteristically found at a higher mutation frequency in ATC, would contribute to disease progression when expressed in a BRAF-mutant WDTC cell line. In vitro, we demonstrated that the PIK3CA mutation resulted in an increase in cell proliferation and the ability of cells to form colonies and migrate. When we compared both cell lines for their tumourigenic capabilities in vivo using a patient-derived xenograft model, we found that while the average tumour volume was higher in the PIK3CA group, the difference was not significant. Collectively, this thesis identified two candidate therapeutic agents with potential to improve patient outcomes and identified PIK3CA as a driver of thyroid cancer progression.
2019-05-29T18:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/6333
https://ir.lib.uwo.ca/context/etd/article/8517/viewcontent/NP_FullThesis_Aug2019_v12.pdf
https://ir.lib.uwo.ca/context/etd/article/8517/filename/0/type/additional/viewcontent/SupplementaryTable6.1_SampleSummary.xlsx
https://ir.lib.uwo.ca/context/etd/article/8517/filename/1/type/additional/viewcontent/SupplementaryTable6.2_RNA_abundance_TPM.xlsx
https://ir.lib.uwo.ca/context/etd/article/8517/filename/2/type/additional/viewcontent/SupplementaryTable6.3_StudyComparison_SNVs.xlsx
https://ir.lib.uwo.ca/context/etd/article/8517/filename/3/type/additional/viewcontent/SupplementaryTable6.4_GermlineSNVs_DriverGenes.xlsx
https://ir.lib.uwo.ca/context/etd/article/8517/filename/4/type/additional/viewcontent/SupplementaryTable6.5_STRprofiling_ATC_celllines.xlsx
https://ir.lib.uwo.ca/context/etd/article/8517/filename/5/type/additional/viewcontent/SupplementaryTable6.6_CNA_SurvivalAssociations.xlsx
https://ir.lib.uwo.ca/context/etd/article/8517/filename/6/type/additional/viewcontent/SupplementaryTable6.7_SNV_SurvivalAssociations.xlsx
https://ir.lib.uwo.ca/context/etd/article/8517/filename/7/type/additional/viewcontent/SupplementaryTable6.8_StudyComparison_CNAs.xlsx
https://ir.lib.uwo.ca/context/etd/article/8517/filename/8/type/additional/viewcontent/SupplementaryTable6.9_SNVOverlap.xlsx
https://ir.lib.uwo.ca/context/etd/article/8517/filename/9/type/additional/viewcontent/SupplementaryTable6.10_CNAOverlap.xlsx
https://ir.lib.uwo.ca/context/etd/article/8517/filename/10/type/additional/viewcontent/SupplementaryTable6.11_RNA_fusions.xlsx
https://ir.lib.uwo.ca/context/etd/article/8517/filename/11/type/additional/viewcontent/SupplementaryTable6.12_siRNA_screen.xlsx
https://ir.lib.uwo.ca/context/etd/article/8517/filename/12/type/additional/viewcontent/SupplementaryTable6.13_Kinase_inhibitor_drug_screen.xlsx
http://creativecommons.org/licenses/by-nc-nd/4.0/
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Anaplastic thyroid cancer
papillary thyroid cancer
targeted therapy
disease progression
high-throughput screening
small molecule inhibitors
Medicine and Health Sciences
Translational Medical Research
oai:ir.lib.uwo.ca:etd-1039
2011-11-15T18:56:57Z
publication:math
publication:etdlac
publication:math-etd
publication:faculties
publication:etd
Holomorphic k-differentials and holomorphic approximation on open Riemann surfaces
Askaripour, Nadya
This thesis is of two parts: At the first part (Chapters 1 and 2) we study some spaces of holomorphic k-differentials on open Riemann surfaces, and obtain some observations about these spaces, then we obtain two main theorems about the kernel of Poincar\'e series map. In the second part (Chapters 3 and 4), we study holomorphic approximation on closed subsets of non-compact Riemann surfaces. We add a condition to the Extension Theorem and fixing its proof. Extension Theorem was first stated and proved by G. Schmieder, but there are few examples, where the theorem fails. That is slightly effecting a class of closed sets (which is called weakly of infinite genus).
2010-08-19T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/9
https://ir.lib.uwo.ca/context/etd/article/1039/viewcontent/final_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Riemann surface
k-differential
Poincare series
holomorphic approximation
Extension Theorem
Analysis
oai:ir.lib.uwo.ca:etd-1040
2011-11-15T18:59:56Z
publication:ivey
publication:ivey-etd
publication:faculties
publication:etd
Options Under Uncertainty: An Empirical Investigation of Patterns of Commitment in Display Technologies in the Flat Panel TV Set Industry
Lehmberg, Derek
This dissertation considers fundamental questions about real options reasoning and its application in the face of uncertainty: do firms behave as real options reasoning predicts, and are there performance benefits from its application? The concept of uncertainty is further developed by considering two primary types: technological uncertainty and market needs uncertainty. A qualitative industry level historical case study is performed on the flat panel TV industry, chosen because it exhibits high technological uncertainty and low market needs uncertainty. Real options logic predicts, in such an industry, that firms will develop and maintain technology options until uncertainty is resolved. Firm level case studies for major incumbent Japanese TV set manufacturers and other relevant firms are performed. Comparison across the cases, and between several specific firms is conducted to test and further develop theory. The firms studied are found to generally behave as predicted by real options logic. Evidence from the study does not present a clear relation between options-related behavior and performance. Although this study identifies evidence not holding options can have large negative performance results, firms holding options as predicted by theory did not realize lasting performance improvements. With one exception, firms attempting to leverage technological capabilities into improved market positions were unable to realize durable improvements in their positions. The development and release of flat panel TV coincided with changes in performance for many firms in the industry; however, these performance changes were short lived. By the end of the study period, industry players had generally returned to the trajectories they were previously on. Between-case analysis of several outlying firms in the sample provides a rich and nuanced view of requirements for firms to dramatically improve performance in the face of high technological uncertainty in a market with very large size potential and relatively well-understood customer needs. This research contributes to the empirical literature on real options and is novel amongst academic research in its coverage of the flat panel display history using Japanese sources. Finally, this dissertation includes managerial implications regarding the usefulness of real options reasoning as well as practical issues in its implementation.
2010-04-10T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/1
https://ir.lib.uwo.ca/context/etd/article/1040/viewcontent/Lehmberg_Derek_201010_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
real options
uncertainty
strategic commitment
flat panel display industry
television set industry
Strategic Management Policy
oai:ir.lib.uwo.ca:etd-1042
2011-11-15T19:06:19Z
publication:civil
publication:faculties
publication:etd
publication:civil-etd
Response of a Two-Story Residential House Under Realistic Fluctuating Wind Loads
Morrison, Murray J
Severe wind storms such as tropical cyclones, tornados, downbursts etc. can cause significant damage to infrastructure. Damage surveys following these events have shown that the roofs of residential, wood-frame construction are particularly vulnerable to failures. While damage surveys provide detail information of what components fail, they cannot provide the loads at which these failures occurred or how they initiated. Wind tunnel pressure models provide detailed information of the wind loads on buildings, however, they are not able to predict failures or how these loads are transferred through the structure. In order to better understand the response of wood framed houses when subjected to high wind loads, realistic fluctuating wind loads were applied to a full scale two-story wood frame house. In addition, individual component tests were conducted on toe-nailed roof-to-wall connections to examine their behaviour to fluctuating wind loads. The testing of individual toe-nail connections under realistic fluctuating wind loading has found that the nails are incrementally withdrawn at peak loads. However, the maximum load applied during the fluctuating load tests matches well with the failure capacity determined from ramp loading experiments, even though damage to the connections initiates at much lower loads. Tests performed on the roof of a house have shown that the uplift capacity of the roof is significantly higher than that predicted using the individual connection results. The higher uplift capacity of the entire roof is attributed to significant load sharing between adjacent connections so that failures likely initiate at multiple connections up to the entire roof and the effective tributary area of the roof-to-wall connections is substantially larger than that of a single truss. Since toe-nailed roof-to-wall connections are partially withdrawn during peak wind gusts, how the loads are transferred through the structural system, to the connections, changes as the connections become increasingly damaged. This implies that while static testing is suitable to determine the capacity of individual toe-nail connections, testing of the full structure must be conducted using realistic fluctuating wind loads. Despite the significant damage accumulated at the toe-nail roof-to-wall connections, there was little evidence of damage to the interior of the house, indicating that there may be significant undocumented damage to homes following tropical cyclones.
2010-09-14T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/13
https://ir.lib.uwo.ca/context/etd/article/1042/viewcontent/Phdthesis_Morrison_FINAL_16092010.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
wind loads
low-rise building
structural failures
roof-to-wall connections
full scale testing
structural response
Civil Engineering
Structural Engineering
oai:ir.lib.uwo.ca:etd-1044
2017-09-11T16:00:47Z
publication:hrs
publication:hrs-etd
publication:faculties
publication:etd
Physical Function During Performance-Based Tasks and Throughout Daily Life. Is It Different Across Levels of Frailty?
Theou, Olga
The overall aim of this thesis was to provide a more focused understanding about the physical function of older women across levels of frailty. The specific aims were: 1) Examine the physical function of older women across levels of frailty during performance-based tasks and throughout their normal daily life; and 2) Review the effectiveness of current exercise interventions for the management of frailty. To answer these aims an observational study of community-dwelling older women (63-100 years) from rural Greece and a comprehensive systematic review on the impact of exercise on frail older adults were conducted. The performance-based measures that had the strongest association with frailty were ambulatory mobility, lower body muscular endurance, and non-dominant handgrip strength. Walking at a preferred pace was more related to frailty than walking at maximal pace and grip strength of the non-dominant hand had a stronger association with frailty compared to the dominant hand. In addition, accelerometers showed good agreement with the other physical activity tools, had the strongest association with frailty, and could be used to dissociate levels of frailty. This thesis showed that multiple methods can be used to accurately determine the duration and intensity of physical activity in older adults across levels of frailty since each method examined in this thesis had limitations but provided useful information about different aspects of physical activity. Muscle activity and quiescence, as measured with portable electromyography, may add insight to the dissociation of frailty since they differ across levels of frailty and may also be used to indicate differences between the upper and lower body muscles. Finally, the systematic review indicated that structured exercise training can have a positive effect on frail older adults and thus can be helpful for the management of frailty. Multicomponent training interventions, of long duration (≥ 5 months), performed three times per week, for 30-45 minutes per session, generally had superior outcomes than other exercise programs. The findings from this thesis indicated that the criteria selected to define frailty and the measurement protocols for these criteria are important. Future investigations will help classify the potential role of these measures in preventing further functional decline.
2010-04-11T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/2
https://ir.lib.uwo.ca/context/etd/article/1044/viewcontent/THEOU_thesis_after_defense.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
frail
aging
women
physical activity
exercise
accelerometer
Rehabilitation and Therapy
oai:ir.lib.uwo.ca:etd-1047
2011-11-15T19:12:30Z
publication:electrical
publication:electrical-etd
publication:faculties
publication:etd
Ontological View-driven Semantic Integration in Open Environments
Xue, Yunjiao
In an open computing environment, such as the World Wide Web or an enterprise Intranet, various information systems are expected to work together to support information exchange, processing, and integration. However, information systems are usually built by different people, at different times, to fulfil different requirements and goals. Consequently, in the absence of an architectural framework for information integration geared toward semantic integration, there are widely varying viewpoints and assumptions regarding what is essentially the same subject. Therefore, communication among the components supporting various applications is not possible without at least some translation. This problem, however, is much more than a simple agreement on tags or mappings between roughly equivalent sets of tags in related standards. Industry-wide initiatives and academic studies have shown that complex representation issues can arise. To deal with these issues, a deep understanding and appropriate treatment of semantic integration is needed. Ontology is an important and widely accepted approach for semantic integration. However, usually there are no explicit ontologies with information systems. Rather, the associated semantics are implied within the supporting information model. It reflects a specific view of the conceptualization that is implicitly defining an ontological view. This research proposes to adopt ontological views to facilitate semantic integration for information systems in open environments. It proposes a theoretical foundation of ontological views, practical assumptions, and related solutions for research issues. The proposed solutions mainly focus on three aspects: the architecture of a semantic integration enabled environment, ontological view modeling and representation, and semantic equivalence relationship discovery. The solutions are applied to the collaborative intelligence project for the collaborative promotion / advertisement domain. Various quality aspects of the solutions are evaluated and future directions of the research are discussed.
2010-09-20T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/16
https://ir.lib.uwo.ca/context/etd/article/1047/viewcontent/Xue_Yunjiao_201010_PhD_Thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Semantic Integration
Ontology
Ontological View
Frame
Semantic Relationship Discovery
Computer Engineering
oai:ir.lib.uwo.ca:etd-1048
2010-08-17T18:12:54Z
publication:philosophy-etd
publication:philosophy
publication:faculties
publication:etd
Kant and the Fact of Reason
Chung, Kenneth KH
It is often thought that Kant abandoned his argument for the justification of morality in the Groundwork of the Metaphysics of Morals for a radically different argument in the Critique of Practical Reason. In the Groundwork, Kant appears to try to justify our commitment to the moral law on the basis of our freedom, but in the Critique, he tries to justify that commitment on the basis of what he calls the fact of reason. I assess and reject influential interpretations of both arguments as being philosophically unsound, and I propose, what I take to be, a novel and promising account of the fact of reason.
2010-08-26T19:19:02Z
text
application/pdf
https://ir.lib.uwo.ca/etd/5
https://ir.lib.uwo.ca/context/etd/article/1048/viewcontent/Chung_Kenneth_KH_201008_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Kantian ethics
kant
moral philosophy
ethics
morality
fact of reason
Ethics and Political Philosophy
oai:ir.lib.uwo.ca:etd-1049
2010-11-29T16:12:42Z
publication:fims
publication:fims_etds
publication:faculties
publication:etd
publication:lis-etd
The Information Practices of People Living with Depression: Constructing Credibility and Authority
Oliphant, Tami
Depressive episodes and chronic depression often provide the impetus for both online and offline everyday life information-seeking and sharing and the seeking of support. While allopathic medication, psychiatric, and other biomedical services are the standard treatments for depression, people often use complementary and alternative medicine (CAM) to supplement or supplant biomedical treatments. Depression is a nebulous disorder with varying causes, illness trajectories, and a wide variety of potentially effective treatments. Often, treating and managing depression forms a project for life (Wikgren, 2001) where the need for information is continuous.
In the present study, I have used a constructionist, discourse analytic approach as outlined by Potter (1996) and Wooffitt (1992) to analyze the messages posted to three online newsgroups devoted to depression, CAM, and the practices of biomedicine and to analyze the transcripts from 10 semi-structured interviews with participants who self-identified as currently having depression or who have suffered from depression in the past. I have sought to understand how people justify using, or not using, CAM to treat depression. Specifically, I have investigated how people with depression use information in discourse to justify healthcare decisions and to create credible and authoritative accounts; how people with depression conceptualize CAM therapies, mainstream medicine, and depression and how these conceptualizations are represented in the discursive constructions of individuals as competent information-seekers and users; and I have investigated the information practices (e.g., everyday life information-seeking, sharing, and use) of people living with depression.
My findings show that while expert, biomedical information sources and knowledge are most often drawn upon and referred to by newsgroup posters and interviewees to warrant claims, people used a variety of discursive strategies and regular speech patterns to create credible and authoritative accounts, to portray themselves as competent information-seekers and users, to support their claims for either using or foregoing a certain treatment, and to counter the authoritative knowledge of biomedicine.
In addition, my findings emphasize the importance of orienting information discussed in Savolainen’s (1995) everyday life information-seeking (ELIS) model. For many people with depression, information was used to maintain a sense of coherence (related to “mastery of life” within the ELIS model) and to create meaning in addition to solving practical problems. My findings suggest that an additional information-seeking principle to those outlined by Harris and Dewdney (1994) deserves further research attention: people seek information that is congruent with their worldview and values.
2010-11-10T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/35
https://ir.lib.uwo.ca/context/etd/article/1049/viewcontent/Oliphant_Tami_201011_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
complementary and alternative medicine
depression
discourse analysis
information practices
experiential
expert
and authoritative knowledge
cognitive authority
and credibility
Library and Information Science
oai:ir.lib.uwo.ca:etd-1051
2010-10-12T20:06:50Z
publication:philosophy-etd
publication:philosophy
publication:faculties
publication:etd
Feeling, Impulse and Changeability: The Role of Emotion in Hume's Theory of the Passions
Paxman, Katharina A.
Hume’s “impressions of reflection” is a category made up of all our non-sensory feelings, including “the passions and other emotions.” These two terms for affective mental states, ‘passion’ and ‘emotion’, are both used frequently in Hume’s work, and often treated by scholars as synonymous. I argue that Hume’s use of both ‘passion’ and ‘emotion’ in his discussions of affectivity reflects a conceptual distinction implicit in his work between what I label ‘attending emotions’ and ‘fully established passions.’ The former are the transient, changeable, valenced feelings that flow between perceptions and constitute their felt nature and impulse. The latter are the particular passions fully realized, with characteristic valence, and analyzed by Hume in terms of their particular belief structures and relations between ideas and impressions understood to be constituent of particular passions. The term ‘emotion’ for Hume generally denotes either the attending feeling, sometimes distinct from the passion (particularly as ‘passion’ is being used to include the associated beliefs, causes and objects), or as a synonym for a particular passion, typically when Hume is primarily referring to the felt nature of the passion. Generally speaking, ‘passion’ is a more cognitive category of affective mental state, while ‘emotion’ is more sensationalist. I will further argue that when we grant Hume the emotion/passion distinction, he can accommodate both highly sensationalist and highly cognitivist understandings of affective mental states. I finish with the application of my distinction to two key topics in Hume studies: his sympathy mechanism, and his theory of belief and motivation.
2010-09-17T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/14
https://ir.lib.uwo.ca/context/etd/article/1051/viewcontent/Paxman_Dissertation_WITH_CONTENT_EDITS.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
David Hume
passion
emotion
history of theories of emotion
feeling
History of Philosophy
Philosophy
Philosophy of Mind
oai:ir.lib.uwo.ca:etd-1052
2010-11-04T12:07:26Z
publication:etdlac
publication:theorycrit
publication:theorycrit-etd
publication:institutes
publication:etd
Outlawry and the Experience of the (Im)possible: Deconstructing Biopolitics
Bunch, Mary J
Outlawry is a legal penalty that banishes wrongdoers from the community; it refers to a refusal to obey the law and a withdrawal of legal rights. Although outlawry is obsolete in western criminal law, Giorgio Agamben links it to modern biopolitics. As outlawry is appropriated to preserve the law, and as the law takes life as its object, the subject of politics disappears. Yet biopolitics also occurs alongside a threat to sovereignty posed by outlawry, and a shift away from the subject as a site of emancipatory politics, toward a politics of difference. Taking a post-structural approach, this project examines outlawry as a deconstructive concept. Outlawry exposes the law’s inability to be at one with itself, its undecidability, and its dependence on fiction and force to come into being and to maintain itself. Staging outlawry in the terms of Carl Schmitt, Walter Benjamin, and Jacques Derrida, the first chapter develops outlawry as deconstructive concept with an undecidable relationship to justice. Chapter two looks to Judith Butler’s performative subject and Louis Althusser’s theory of subject interpellation to re-think the relations between subject and law in light of outlawry. Chapter three examines the overlap between sovereignty, outlawry and the beast (la bête) discussed by Agamben and Derrida, and considers political concepts that might deter the conserving power of outlawry in favor of its deconstructive force. Finally, I turn to Levinasian ethics and Deleuze and Guattari’s concept of becoming-minoritarian to sketch a politics of outlawry that revises the law according to an ethical responsibility to the Other, the political agency of those who are excluded from the law, and their demand that structures of power be altered. Outlawry need not result in sheer abjection; for both the subject, and the anarchic demos, it can be a source of political vitality and social transformation. Yet as the atrocities of modernity bear witness, from the Shoah to Guantanamo Bay, outlawry can lead to ‘the worst.’ Outlawry marks the fault line between justice and injustice; if we are to achieve an ethical future, we must remain politically vigilant, self-critical and open to alterity.
2010-10-15T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/26
https://ir.lib.uwo.ca/context/etd/article/1052/viewcontent/Mary_Bunch_J_201102_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Outlawry
deconstruction
biopolitics
becoming minoritarian
Derrida
Deleuze
Political Theory
oai:ir.lib.uwo.ca:etd-1053
2011-11-15T19:17:01Z
publication:pharmtox-etd
publication:physpharm
publication:faculties
publication:etd
Regulation of DNA Damage Processing by Covalent Modification of Thymine DNA Glycosylase
Mohan, Ryan D.
Thymine DNA glycosylase (TDG) is an essential DNA repair enzyme mediating excision of uracil and thymine mispaired with guanine within CpG contexts. Unrepaired, these lesions result in G:C to A:T transitions which are major contributors to genome instability. Interestingly, TDG interacts functionally with transcriptional regulators and participates in directed cytosine demethylation at promoters. TDG is subject to multiple post-translational modifications (PTM) and we undertook an analysis of how these regulate TDG function. Initially, we examined TDG regulation by small ubiquitin-like modifier (SUMO) and identified a novel SUMO binding motif (SBM1, residues 144-148). We hypothesized that SBM1, along with SBM2 (319-322), would facilitate non-covalent SUMO interactions upon conjugation of SUMO (sumoylation) to lysine 341, altering TDG conformation and function. Biochemical and cell based analyses supported our hypothesis, showing SUMO interactions allosterically regulate TDG protein-protein and substrate interactions, altering TDG subnuclear localization and enzymatic function. Furthermore, sumoylation drastically reduced acetylation of TDG occurring at lysines 70, 94, 95, and 98. Secondly, we examined TDG regulation by phosphorylation and demonstrated that serines 96 and 99 are phosphorylated by protein kinase C α in vivo. Biochemical analysis of covalently modified recombinant TDG showed that acetylation and phosphorylation of TDG are mutually exclusive and both are suppressed by TDG-DNA interactions. Furthermore, acetylated TDG did not interact stably with DNA or efficiently excise thymine from G:T mispairs, while phosphorylated TDG was indistinguishable from unmodified protein. Lastly, we examined TDG regulation in aging cells. Immunostaining showed TDG redistributed from nucleus to cytoplasm in aged cells. Interestingly, treatment with histone deacetylase inhibitors resulted in similar redistribution and immunoblotting indicated that an increase in TDG modification consistent with sumoylation or monoubiquitination had occurred. Similar results were obtained by exposing cells to oxidative stress. Analysis of a sumoylation-minus mutant of TDG identified sumoylation as an important regulator of TDG localization. Interestingly, we found extensive colocalization of TDG with sites of active transcription which was reduced by phorbol ester treatments which surprisingly promoted entry into heterochromatic regions from which TDG is generally excluded. Together, these findings suggest that TDG function may be regulated by PTM, consequently affecting genome stability and expression.
2010-05-14T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/3
https://ir.lib.uwo.ca/context/etd/article/1053/viewcontent/Mohan_Ryan_D_201008_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Thymine DNA glycosylase (TDG)
DNA base excision repair (BER)
Epigenetic modification
Acetylation
Phosphorylation
Sumoylation
Cancer Biology
oai:ir.lib.uwo.ca:etd-1054
2011-01-06T16:07:26Z
publication:ivey
publication:ivey-etd
publication:faculties
publication:etd
Credit Default Swaps - Essays on Model and Market Efficiency
Farooqi, Muhammad F
Essay 1 tests the ability of a commercial structural credit default swap pricing model to predict market spreads. Consistent with several previous studies testing other models, we find our model unable to price credit risk precisely and observe an illiquidity premium reflecting a credit risk component which should be incorporated into future pricing models. We also identify macroeconomic and stock market factors that help explain movements in CDS spreads beyond the levels suggested by the model.
Essay 2 looks at bid and ask spreads to find evidence of quote shading where dealers manipulate their quotes in order to attract sell orders. This is something not yet studied in CDS literature and we draw on studies on the foreign exchange markets for theoretical support. We find that dealers are more likely to indulge in quote shading when firm risk increases but not close to weekends or holidays. We also look at price discovery with and without quote shading but our results are inconclusive. Using the put-call ratio as a risk level indicator, we find that price discovery in the CDS market decreases as firm risk increases.
Essay 3 looks at the quality of the CDS market in the backdrop of the recent financial crisis. Previous studies have found that CDS markets lead price discovery only in the case of high risk firms and this paper tests if price discovery dynamics have shifted in favour of the CDS market since overall firm risk levels have increased. Using Granger-causality tests, we compare stock and CDS markets before and since the crisis and finds that despite an overall increase in risk levels, the stock market continues to lead the CDS market in all risk categories. We also test the CDS market for mis-reaction using Variance Ratios and find that while there was evidence of over-reaction before the crisis, CDS market is under-reacting since the crisis.
2010-10-01T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/76
https://ir.lib.uwo.ca/context/etd/article/1054/viewcontent/Farooqi_Muhammad_F_201009_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Credit Default Swaps
CreditGrades
CDS Implied Volatility
Liquidity
Price Discovery
Quote Shading
Day-of-Week Effect
Post-Crisis Analysis
Over-reaction
Under-reaction
Finance and Financial Management
oai:ir.lib.uwo.ca:etd-1055
2010-08-26T03:14:12Z
publication:biomedeng-etd
publication:biomedeng
publication:faculties
publication:etd
Virtual and Augmented Reality Techniques for Minimally Invasive Cardiac Interventions: Concept, Design, Evaluation and Pre-clinical Implementation
Linte, Cristian A
While less invasive techniques have been employed for some procedures, most intracardiac interventions are still performed under cardiopulmonary bypass, on the drained, arrested heart. The progress toward off-pump intracardiac interventions has been hampered by the lack of adequate visualization inside the beating heart.
This thesis describes the development, assessment, and pre-clinical implementation of a mixed reality environment that integrates pre-operative imaging and modeling with surgical tracking technologies and real-time ultrasound imaging. The intra-operative echo images are augmented with pre-operative representations of the cardiac anatomy and virtual models of the delivery instruments tracked in real time using magnetic tracking technologies. As a result, the otherwise context-less images can now be interpreted within the anatomical context provided by the anatomical models. The virtual models assist the user with the tool-to-target navigation, while real-time ultrasound ensures accurate positioning of the tool on target, providing the surgeon with sufficient information to ``see'' and manipulate instruments in absence of direct vision.
Several pre-clinical acute evaluation studies have been conducted in vivo on swine models to assess the feasibility of the proposed environment in a clinical context. Following direct access inside the beating heart using the UCI, the proposed mixed reality environment was used to provide the necessary visualization and navigation to position a prosthetic mitral valve on the the native annulus, or to place a repair patch on a created septal defect in vivo in porcine models.
Following further development and seamless integration into the clinical workflow, we hope that the proposed mixed reality guidance environment may become a significant milestone toward enabling minimally invasive therapy on the beating heart.
2010-08-26T14:30:34Z
text
application/pdf
https://ir.lib.uwo.ca/etd/4
https://ir.lib.uwo.ca/context/etd/article/1055/viewcontent/Linte_Cristian_A_201008_PhD_Thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
image-guided cardiac surgery; mixed reality environments; pre-operative planning; intra-operative guidance; surgical tracking; in vivo clinical translation
Bioimaging and Biomedical Optics
oai:ir.lib.uwo.ca:etd-1056
2010-08-26T22:02:03Z
publication:kin
publication:kin-etd
publication:faculties
publication:etd
The Development and Validation of an Expertise Development Model for Sport Coaches
Wiman, Melissa L
The objective of this dissertation was to develop and validate a model for coaching expertise development using semi-structured interviews. The aim of Study One was twofold: first, to examine how coaching expertise is defined and second, to investigate how this expertise develops over time. Interviews were completed with elite athletes and elite coaches and were done in the tradition of grounded theory. Results suggested that there is a need to go beyond identifying a coach as an expert based on the performance of his/her athletes. Some of the additional criteria suggested included: be recognized by peers (other coaches) as experts; be recognized by athletes as experts, and have successful athletes/teams at any level of competition. The intention of Study Two was to describe, in more detail, mechanisms for coaching expertise development identified in a previous study (Wiman, Salmoni & Hall, 2010). Seven varsity coaches were interviewed. It was found that open-mindedness seemed to be an essential learned characteristic in supporting the development of expertise. Coaches discussed using both internal and external feedback mechanisms and indicated a variety of ways in which they used this feedback to continually better themselves. Central to this process, coaches assessed the needs of athletes as a basis for their evaluation of their own strengths and weaknesses as a coach. A major source of information used to develop expertise is introspection. Coaches reported using introspection primarily for self-evaluation and to gain self-awareness. Mentoring other coaches and being mentored were also discussed. Finally, a model to place these ideas into a developmental process was proposed. The aim of the third and final study was to validate a model for the development of coaching expertise presented by Wiman, Salmoni and Hall in studies one and two. Five novice and five elite rowing coaches were interviewed. Results indicated that the model was supported both implicitly and explicitly by the interviewees. Feedback provided by the participants suggested that motivation needed to be added as an explicit component within the model. Some other suggestions on how to facilitate the self-adaptation process described by the model as it relates to coaching education were included.
2010-08-31T13:20:46Z
text
application/pdf
https://ir.lib.uwo.ca/etd/8
https://ir.lib.uwo.ca/context/etd/article/1056/viewcontent/auto_convert.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Coaching Development
Expertise
Learning
Expert Coaching
Self-Adaptation
Other Psychology
oai:ir.lib.uwo.ca:etd-1057
2010-08-27T13:53:37Z
publication:biomedeng-etd
publication:biomedeng
publication:faculties
publication:etd
Controlled Delivery of Serp-1 Protein from Poly(vinyl alcohol) Hydrogel
Kennedy, Karen L
Poly(vinyl alcohol) (PVA) was selected and evaluated as a controlled drug delivery matrix for Serp-1, a potential new therapeutic with anti-inflammatory properties for control of restenosis. PVA hydrogels, containing a high water content, can be formed by physical crosslinking via a process involving freezing and thawing the material in multiple cycles. PVA, being a well known biomaterial, is suited for biomedical applications and the high water content and hydrophilicity provides a friendly environment for the delivery of large protein based drugs. Using bovine serum albumin (BSA) as a model protein, the controlled release properties of PVA were investigated. Release profiles demonstrated diffusion controlled release and adjusting the number of freeze-thaw cycles resulted in a change in release rate. It was also determined that fabricating a reservoir-type system by adding an additional layer of protein-free PVA as an outer barrier provides a method of changing the release kinetics. From a one-layer matrix-type PVA/BSA system the release kinetics follow diffusion controlled release, while from a two-layer reservoir-type system the release kinetics are zero-order. The thickness of the outer barrier controlled the rate of BSA release. Using BSA as a model protein again, its release from PVA hydrogel into phosphate buffered saline (PBS) solutions of varying ionic strength was explored. The amount of BSA released was shown to be influenced by the ionic strength of PBS used as the release medium. Increasing the ionic strength of the release medium caused a reduction in mesh space of the hydrogel and increase in apparent PVA concentration, leading to a reduction in BSA release. These results are important to consider for applications in the physiological environment where salts are unavoidable.
The release of Serp-1 from PVA hydrogel was systematically investigated by considering the effect of the PVA processing parameters. A decrease in release rate was observed when the number of freeze-thaw cycles was increased, the PVA solution concentration was increased, or the freezing and thawing rates were decreased. By manipulating the different processing parameters studied, the diffusive properties of Serp-1 from PVA hydrogel could be controlled over a 30-fold range. In contrast to the PVA/BSA system where virtually all the protein is released, the amount of Serp-1 released from an equivalent system was found to be only approximately 50 % with the remaining protein trapped in the PVA matrix. This is likely due to a combination of factors including the possible stronger interaction of Serp-1 and PVA, as well as shrinkage of the hydrogel structure.
A therapeutic level of Serp-1 release was achieved by increasing the initial protein loading and with only two freeze-thaw cycles the release was extended over a period of approximately 100 hours. A promising PVA/Serp-1 controlled drug delivery system with tunable properties has been demonstrated. The use of such a controlled release system would offer an improvement over the current Serp-1 delivery method of infusion by gradually releasing Serp-1 over time at the local site of arterial injury. The system can be tuned to adjust the release rate of Serp-1 one by selecting the appropriate combination of processing conditions. The release kinetics can also be adjusted by selecting a one-layer matrix-type system or two-layer reservoir-type system. Therefore, there are many options to tune the PVA/Serp-1 system to meet therapeutic requirements once they are known following clinical trials of the new therapeutic agent.
2010-08-30T15:51:27Z
text
application/pdf
https://ir.lib.uwo.ca/etd/7
https://ir.lib.uwo.ca/context/etd/article/1057/viewcontent/Kennedy_Karen_L_201008_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Hydrogel
poly(vinyl alcohol)
bovine serum albumin
Serp-1
controlled release
diffusion
freeze-thaw cycles
physical crosslinking
Biomaterials
oai:ir.lib.uwo.ca:etd-1059
2010-08-30T14:15:20Z
publication:earth
publication:geology-etd
publication:faculties
publication:etd
The Holocene Paleolimnology of Lake Superior
Hyodo, Ayumi
This study describes contributions of glacial meltwater to Lake Superior over the last ~11,000 cal BP (calibrated years before 1950 AD). This research has been motivated by a desire to understand whether glacial meltwater discharge via the Great Lakes into the North Atlantic played a role in Holocene cooling events, such as the Younger Dryas. Rhythmites (interpreted as varves), lithological, mineralogical and grain-size variations, and radiocarbon dating were used to establish chronostratigraphic correlation among four sediment cores from Lake Superior (Duluth, Caribou and Ile Parisienne basins, Thunder Bay Trough). Glacial sediments were deposited between ~10,850 and ~8,800 cal BP. The δ18O values of ostracodes record the presence of glacial meltwater (δ18O of ~ –25 ‰) in ancient Lake Superior as the Laurentide Ice Sheet waxed and waned. Glacial meltwater was increasingly dominant between ~10,850 and ~9,250 cal BP, particularly as thick varves formed in northern portions of the Lake Superior Basin (~10,400-10,200, ~9,900 and ~9,300-9,200 cal BP). Glacial meltwater supply was reduced in the Thunder Bay Trough between ~9,250 and ~8,950 cal BP, but returned from ~8,950 to ~8,800 cal BP. Glacial meltwater flow from the Lake Superior Basin bypassed the Huron Basin several times during this period. Final termination of glacial meltwater supply occurred at ~8,800 cal BP – coincident with cessation of varve formation and inception of ancient Lakes Agassiz-Ojibway and Houghton. Primary productivity was very low and algal growth occurred under conditions of extreme nitrogen deficiency – as determined using TOC, TN and C/N ratios – until glacial meltwater supply to the Basin was ended. The postglacial sediments are non-calcareous. The diatom silica proxy record shows that water δ18O values rapidly increased after glacial meltwater termination, reaching ~ –10 ‰ during the Holocene Thermal Maximum. Water δ18O values decreased at ~3,000 cal BP in response to the Holocene Neoglacial Interval before gradually rising to Lake Superior’s modern value of –8.7 ‰. Aquatic primary productivity, inferred using TOC, TN, and δ13C and δ15N, has increased gradually since ~8,800 cal BP. Primary δD and δ18O values are not preserved by porewater; they instead reflect mixing between ancient and modern lake water.
2010-08-30T15:32:45Z
text
application/pdf
https://ir.lib.uwo.ca/etd/6
https://ir.lib.uwo.ca/context/etd/article/1059/viewcontent/Hyodo_thesis_Final.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Lake Superior
glacial meltwater
stable isotopes
Lake Agassiz
Holocene
Geology
oai:ir.lib.uwo.ca:etd-1060
2010-12-13T21:49:03Z
publication:ivey
publication:etdlac
publication:ivey-etd
publication:faculties
publication:etd
Cross-Sector Models of Collaboration for Social Innovation
Le Ber, Marlene J
This dissertation consists of three studies that collectively examine the genesis and dynamics of collaborative cross-sector partnerships between nonprofit and for-profit organizations. The overarching question that frames the papers is how cross-sector partnerships organize across sectoral interfaces to advance social innovation. This thesis makes three contributions: 1) the standpoint of the beneficiaries needs to be explicitly discussed when exploring social innovation in cross-sector partnerships; 2) neither success nor failure are absolute but rather cross-sector partners deliberately and iteratively adjust their roles to sustain momentum towards success or rebound from temporary failure in pursuit of social innovation; and 3) despite largely non-overlapping sectoral frames, social innovation is possible when partners learn how to negotiate and fuse their value frames.
In the first paper, we develop a critical theory of social innovation in cross-sector partnerships by recasting value creation from the standpoint of the beneficiary. We review and contrast the principles, relations and relational processes underpinning the Marxist, pragmatist and Frankfurt schools of thought to unpack the role the beneficiary may (or may not play) in value creation. Such critical theorizing enriches the conceptual foundation of the Resource Based View by reinstating the beneficiary as an essential contributor to value creation through voice-receiving, voice-making and/or voice-taking. This paper concludes that beneficiaries are essential to social innovation in cross-sector partnerships: they create and sustain generative tensions within each value creation cycle.
In the second study, we explore the relational processes that underpin social innovation within cross-sector partnerships. Using four longitudinal narratives in healthcare, we explain how partners navigate the duality of success and failure: deliberate role (re)calibrations help the partners sustain the momentum for success and overcome temporary failure or crossover from failure to success. Three factors moderate the relationship between role recalibrations and the momentum for success or failure: relational attachment, partner complacency, and partner disillusionment.
The third and last study uses the same four longitudinal narratives to explore how cross-sector partners come to recognize and reconcile their divergent value creation frames in order to co-construct social innovation. We argue and find that partners initially contrast their sector-embedded diagnostic frames and then work together to deliberately develop partnership-specific prognostic frames. The study develops a four-stage grounded model of frame negotiation, elasticity, plasticity and fusion which unpacks the relational process of value creation in cross sector partnerships.
Taken together, the three studies advance the cross-sector partnership project by fleshing out the (largely neglected) role of relational processes in social innovation.
2010-08-23T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/10
https://ir.lib.uwo.ca/context/etd/article/1060/viewcontent/Le_Ber_Marlene_J_201010_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
social innovation
cross-sector partnerships
value creation
voice
relational processes
framing processes
Strategic Management Policy
oai:ir.lib.uwo.ca:etd-1061
2013-11-19T17:21:39Z
publication:etdlac
publication:history-etd
publication:history
publication:faculties
publication:etd
Asbestos, Quebec: The Town, the Mineral, and the Local-Global Balance Between the Two
van Horssen, Jessica J
From the late 19th to the late 20th century, the cities and industries of the world became increasingly reliant on fireproof materials made from asbestos. As asbestos was used more and more in building materials and household appliances, its harmful effect on human health, such as asbestosis, lung cancer and mesothelioma, became apparent. The dangers surrounding the mineral led to the collapse of the industry in the 1980s. While the market demand and medical rejection of asbestos were international, they were also experienced in the mining and processing communities at the core of the global industry. In the town of Asbestos, Quebec, home of the largest chrysotile asbestos mine in the world, we can see how this process of market boom and bust shaped a fierce local cultural identity. This dissertation examines the global asbestos industry from a local perspective, showing how the people of Asbestos, Quebec had international reach through the work they did and the industry they continue to support today. This thesis explores how the boundaries between humans and the environment were blurred in Asbestos as a strong cultural identity was created through the interaction between people and the natural world. This work advances our understanding of the interdependence of the local-global relationship between resource industries and international trade networks, illustrating the ways it shapes communities and how communities shape it. Bringing bodies of land, human bodies, and the body politic of Asbestos, Quebec into the history of the global asbestos trade helps demonstrate how this local cultural identity grew to influence national policy and global debates on commodity flows, occupational health, and environmental justice.
2010-01-01T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/11
https://ir.lib.uwo.ca/context/etd/article/1061/viewcontent/auto_convert.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Asbestos (Quebec)
asbestos
Johns-Manville
occupational health
strikes
mining
Cultural History
History of Science, Technology, and Medicine
oai:ir.lib.uwo.ca:etd-1064
2010-08-31T19:03:33Z
publication:electrical
publication:electrical-etd
publication:faculties
publication:etd
Addressing Computational Complexity of Electromagnetic Systems Using Parameterized Model Order Reduction
Ahmadloo, Majid
As operating frequencies increase, full wave numerical techniques such as the finite element method (FEM) become necessary for the analysis of high-frequency and microwave circuit structures. However, the FEM formulation of microwave circuits often results in very large systems of equations which are computationally expensive to solve. The objective of this thesis is to develop new parameterized model order eduction (MOR) techniques to minimize the computational complexity of microwave circuits. MOR techniques provide a mechanism to generate reduced order models from the detailed description of the original FEM formulation. The following contributions are made in this thesis:
1. The first project deals with developing a parameterized model order reduction to solve eigenvalue equations of electromagnetic structures that are discretized by using FEM. The proposed algorithm uses a multidimensional subspace method based on modified perturbation theory and singular-value decomposition to perform reduction directly on the finite element eigenvalue equations. This procedure generates parametric reduced order models that are valid over the desired parameter range without the need to redo the reduction when design parameters are changed. This provides significant computational savings when compared to previous eigenvalue MOR techniques, since a new reduced order model is not required each time a design parameter is changed.
2. Implicit moment match techniques such as the Arnoldi algorithm are often used to improve the accuracy of the reduced order model. However, the traditional Arnoldi algorithm is only applicable to first order linear systems and can not directly include arbitrary functions of frequency due to material and boundary conditions. In this work, an efficient algorithm to create parametric reduced order models of distributed electromagnetic systems that have arbitrary functions of frequency (due to material properties, boundary conditions, and delay elements) and design parameters. The proposed method is based on a multi-order Arnoldi algorithm used to implicitly calculate the moments with respect to frequency and design parameters, as well as the cross-moments. This procedure generates parametric reduced order models that are valid over the desired parameter range without the need to redo the reduction when design parameters are changed and provides more accurate reduced order systems when compared with traditional approaches such as Modified Gram Schmidt.
3. This project develops an efficient technique to calculate sensitivities of microwave structures with respect to network design parameters. The proposed algorithm uses a parametric reduced order model to solve the original network and an adjoint variable method to calculate sensitivities. Important features of the proposed method are 1) that the solution of the original network as well as sensitivities with respect to any parameter is obtained from the solution of the reduced order model, and 2) a new reduced order model is not required each time design parameters are varied.
2010-08-31T19:30:12Z
text
application/pdf
https://ir.lib.uwo.ca/etd/12
https://ir.lib.uwo.ca/context/etd/article/1064/viewcontent/Ahmadloo_Majid_201008_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
model order reduction
finite element method
microwave
sensitivity analysis
multi-order Arnoldi
Electromagnetics and Photonics
VLSI and Circuits, Embedded and Hardware Systems
oai:ir.lib.uwo.ca:etd-1065
2010-12-13T16:35:50Z
publication:ivey
publication:ivey-etd
publication:faculties
publication:etd
Object and Relations Uncertainty: Two Components of Perceived Environmental Uncertainty
Francolini, Anthony
I contend that perceived environmental uncertainty should be divided into a new pair of uncertainty components, which I label object and relations uncertainty. Object uncertainty is defined as an actor’s inability to predict the future accurately due to a lack of information about object items (i.e., tangible, reducible, asocial items). Relations uncertainty is defined as an actor’s inability to predict the future accurately due to a lack of information about relations items (abstract, reduction-resistant, social items).
I contend that the object-relations uncertainty component-set is supported by uncertainty research and categorization theory. First, these two components are supported by the works of a variety of prominent organizational and decision-making theorists who portray uncertainty with both object-like and relations-like qualities. Second, this component-set is supported by categorization theory, which identifies the object and relations categories as a fundamental pair of superordinate categories that individuals activate as they make sense of their certain and uncertain environments.
To validate this new component-set I conducted two studies on two different samples. In the first, respondents compared multiple uncertainty statements that expressed different degrees of object and relations uncertainty. I found that respondents perceived object and relations uncertainty as distinct. Without any priming, respondents rated uncertainties from the same component (i.e., object-to-object or relations-to-relations comparisons) as similar, while they rated uncertainties from different components (i.e., object-to-relations comparisons) as dissimilar. Moreover, these respondents ordered the uncertainties along an axis based on the degree of object or relations component they perceived.
In the second study, respondents were presented either an object or relations uncertainty and asked to rate the appropriateness of a variety of uncertainty responses. I found that respondents who perceived object uncertainty preferred different responses than respondents who perceived relations uncertainty. For instance, respondents presented with object uncertainty preferred augmenting the gathering and processing of information, while respondents presented with relations uncertainty preferred to alter the coordination metrics that guided their relationship with transactors.
In summary, I find that object and relations uncertainty are perceived as a set of uncertainty components, and account for actor-response variance that is not otherwise accounted for by the more traditional explanatory variable ‘degree of uncertainty’.
2010-11-10T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/42
https://ir.lib.uwo.ca/context/etd/article/1065/viewcontent/Dissertation_Final_Francolini.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Object Uncertainty
Relations Uncertainty
Perceived Environmental Uncertainty
PEU
Components of Uncertainty
Types of Uncertainty
Business Administration, Management, and Operations
Organizational Behavior and Theory
oai:ir.lib.uwo.ca:etd-1066
2010-12-14T04:22:23Z
publication:apmaths-etd
publication:apmaths
publication:faculties
publication:etd
Simulation-based Valuation and Counterparty Exposure Estimation of American Options
Kan, Kin Hung
Valuing American options is a central problem in option pricing since the early-exercise feature is very common among financial or insurance derivatives products. For high-dimensional American options, Monte Carlo simulation is generally regarded as the only viable approach to price them, and this is the focus of our work. We propose a new regression-based Monte Carlo algorithm for pricing American options. This method typically generates an upper bound of the option value. It is computationally efficient and generates accurate price estimates.
To improve the convergence rate, we apply a bias reduction technique to the least-squares Monte Carlo estimators of American option value. It works by subtracting a bias approximation from the original option value estimators at each exercise opportunity. The bias approximation is derived using large sample properties of the least-squares regression estimators. The resulting expression is easy to evaluate, and is applicable to any payoff structures and underlying processes. Numerical results show that this technique can significantly reduce the bias. However, it introduces non-negligible computational costs, thus careful treatment is required when it is adopted in practice.
Finally, we extend the least-squares Monte Carlo algorithm to estimate the counterparty exposures of American options. The new algorithm is termed optimized least-squares Monte Carlo (OLSM), which is combined with variance reduction techniques, initial state dispersion and multiple bucketing to enhance its performance. The biggest advantage of OLSM is that it avoids nested simulations, allowing for the computation of risk measures on various time horizons under a reasonable computational budget.
2010-10-28T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/52
https://ir.lib.uwo.ca/context/etd/article/1066/viewcontent/Felix_PhD_revised.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
American options
multidimensional
Monte Carlo simulation
regression
bias reduction
counterparty exposure
Management Sciences and Quantitative Methods
oai:ir.lib.uwo.ca:etd-1067
2010-11-03T15:06:44Z
publication:etdlac
publication:biochem-etd
publication:biochem
publication:faculties
publication:etd
Mitotic Regulation of Protein Kinase CK2
St. Denis, Nicole A
Protein kinase CK2 is a serine/threonine kinase with a multitude of substrates and roles in many cellular processes, including mitosis. CK2 is constitutively active, yet we hypothesize that CK2 is indeed regulated in mitosis through subtle means, enabling CK2 to perform its functions unique to cell division. Our aims were to examine the roles of mitotic phosphorylation, subcellular localization, and interplay with mitotic kinases in the regulation of CK2 activity.
We first examined the role of four highly conserved mitotic phosphorylation sites located in the unique C-terminus of CK2α. Phosphospecific antibodies generated against the sites show that CK2α phosphorylation is temporally regulated and occurs during prophase and metaphase during normal mitotic progression. Proper phosphorylation of CK2α is required for proper mitotic progression, as stable cell lines expressing phosphorylation site mutants of CK2α display severe mitotic defects.
We next examined the impact of these phosphorylation events on the subcellular localization of CK2. We show that CK2α, but not CK2α’, localizes to the mitotic spindle. Localization of CK2α to the mitotic spindle is phosphodependent, and requires the peptidyl-prolyl isomerase Pin1. These results are a rare example of functional divergence between the two catalytic isoforms of CK2, and suggest that the role of CK2α phosphorylation during mitosis is to promote localization of CK2 to the mitotic spindle. Finally, we examined the possibility that CK2 activity during mitosis is regulated through hierarchal phosphorylation events, wherein CK2 would phosphorylate proteins only after priming phosphorylation events catalyzed by other mitotic kinases, particularly Cdk1. As this phenomenon has never been systematically investigated, we have investigated the consensus requirements for CK2 primed phosphorylation, and in particular Cdk/CK2 hierarchical phosphorylation. A genome-wide search for potential mitotic substrates matching the consensus sequence suggests that Cdk1/CK2 hierarchical phosphorylation may indeed contribute to mitotic signaling, particularly on the mitotic spindle.
Taken together, our results confirm the importance of CK2 in mitotic cell division, and highlight several examples of subtle regulation of CK2, through phosphorylation, subcellular localization, and interplay with other protein kinases. This helps explain how CK2, a constitutively active kinase, can participate in tightly regulated cellular processes like mitosis.
2010-10-28T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/25
https://ir.lib.uwo.ca/context/etd/article/1067/viewcontent/Nicole_St_Denis_112010_PhD_Thesis.pdf
https://ir.lib.uwo.ca/context/etd/article/1067/filename/0/type/additional/viewcontent/St_Denis_Nicole_A_101010_PhD_Appendix_B.xlsx
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
protein kinase CK2
mitosis
phosphorylation
Pin1
Cdk1
Mitotic spindle
Biochemistry
oai:ir.lib.uwo.ca:etd-1068
2012-10-02T17:47:23Z
publication:french
publication:french-etd
publication:faculties
publication:etd
Mutations et glissements du roman francais au roman africain francophone.
Diallo, Ibrahima Bano
Résumé et mots-clés. Notre travail s’articule autour de trois grands axes. L’analyse des trois parties de notre thèse a cherché à montrer comment s’opère ce que nous avons nommé mutations et glissements du roman français au roman africain francophone au fur et à mesure que les auteurs de notre corpus se démarquent des normes d’écriture imposées. La première partie révèle comment les écrivains francophones africains tirent profit de leur héritage culturel tant traditionnel qu’occidental pour mettre en œuvre une esthétique d’écriture tout à fait originale. Cette nouvelle forme d’écriture, qui tranche d’avec ce qui est érigé comme préceptes à la fois esthétiques et éthiques à suivre par les autorités académiques, constitue un moyen efficace pour les auteurs de notre corpus dans leur projet de société. Car la subversion syntaxique et parfois phonétique leur permet de « nommer les choses par leur nom », de s’approprier la langue française et de tourner en dérision le pouvoir aussi bien politique que religieux pour mieux éclairer la société et la faire prendre conscience de sa responsabilité face aux défis quotidiens. Animés par cette volonté de dénoncer les abus politiques et religieux et le besoin impérieux d’extirper les superstitions de la mentalité des gens afin de fonder une nouvelle société apte à prendre son destin en main, les idées disséminées dans ces romans francophones font écho aux concepts du siècle des Lumières. En effet, comme les penseurs du 18e siècle qui ont vulgarisé des idées nouvelles ayant abouti à une transformation radicale de la société, ces auteurs francophones africains de notre corpus portent un regard critique sur la société ainsi que sur les nouveaux dirigeants africains bien des décennies après les Indépendances. Les auteurs du siècle des Lumières comme ceux d’aujourd’hui ne sont pas exempts de poursuites ni de menaces judiciaires et économiques. Non seulement, les écrivains ont-ils à s’inquiéter des autorités, mais ils peuvent être ennemis les uns des autres aussi. Et c’est ce qui a attiré notre attention dans la deuxième partie du travail sur la confrontation sans merci entre les écrivains et le Pouvoir. Enfin, dans la troisième partie, il s’agit du traitement de la transgression éthico-religieuse. L’intention de ces auteurs est de dévoiler l’hypocrisie, la corruption et la dépravation de ceux qui prétendent incarner la morale, la pureté, mais en même temps inviter leurs lecteurs à bien profiter du moment présent pour bâtir l’avenir. Mots-clés : écriture, esthétique, éthique, idéologie, subversion, normes, religion, pouvoir, savoir, superstition, préjugé, tradition, modernité, langue, langage, convergence.
2010-11-12T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/37
https://ir.lib.uwo.ca/context/etd/article/1068/viewcontent/auto_convert.pdf
Electronic Thesis and Dissertation Repository
French
Scholarship@Western
ecriture
esthetique
ethique
ideologie
subversion
normes
religion
pouvoir
ideologie
superstition
tradition
modernite
langue
langage
convergence.
Arts and Humanities
French and Francophone Language and Literature
oai:ir.lib.uwo.ca:etd-1069
2010-12-13T21:42:25Z
publication:hrs
publication:hrs-etd
publication:faculties
publication:etd
Fall-Related Stigma in Older Adulthood: A Mixed Methods Approach to Understanding the Influence of Stigma on Older Adults' Reported Attitudes and Behaviours Regarding Falls
Hanson, Heather M
Falls during older adulthood present a major threat to the health and wellbeing of older adults and a challenge to society. While effective fall prevention strategies have been developed to address risk factors for falls, older adults commonly resist participation in such programming and dissociate from the topic of falls in general. After reviewing research findings and the theoretical literature, support was found for approaching falls as a stigmatizing topic for older adults. Three mixed methods experiments were completed to test the influence of stigma on older adults‟ attitudes, opinions, and behaviours. Experiments 1 and 2 tested the labelling aspect of fall-related stigma on older adults‟ attitudes and reported behaviours. Experiment 1 randomly assigned participants to receive an exercise program described as either an “exercise class for older adults” or a “fall prevention exercise class for older adults”. Experiment 2 modified the study design of Experiment 1 and presented each participant with a two-alternative, forced-choice response between the two exercise program descriptions. When given the opportunity to participate in either the non-labelled exercise class or the labelled, fall prevention exercise class, the majority of participants (79%) preferred the non-labelled exercise program option. However, a subgroup of older adults identified with the fall prevention label, selected it as their preferred program, and provided a logical rationale for doing so. Analyses were conducted to investigate whether other survey responses could be used to better understand participants‟ choices. The key factors related to participants‟ perceptions of falls and stigma were identified by the predictors uncovered. Experiment 3 then used the factors from Experiment 2 to determine whether an informational message addressing the key constructs could mitigate the negative fall prevention label. After reading a randomly assigned vignette addressing the key statements, participants were asked to make a two-alternative, forced-choice response for their preferred exercise program. The results indicated that the informational vignette was effective in de-stigmatizing the fall prevention label, with 41% of respondents selecting it as their preferred program. The findings of these experiments indicate that while falls are a stigmatizing topic for older adults, it appears to be amenable to attenuation.
2010-10-26T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/22
https://ir.lib.uwo.ca/context/etd/article/1069/viewcontent/hanson_heather_m_201010_PhD_thesis_final.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
accidental falls
stigmatization
aged
injury prevention and control
health promotion
psychosocial factors
Medicine and Health
Other Social and Behavioral Sciences
Social Psychology
Sociology
oai:ir.lib.uwo.ca:etd-1070
2011-11-15T19:22:45Z
publication:ivey
publication:etdlac
publication:ivey-etd
publication:faculties
publication:etd
Employment of Returnees and the Performance of Multinational Subsidairies in China
Wang, Huanglin
Returnees, those who went overseas for higher education and then returned to their home countries, represent a unique group of employees for multinational enterprises (MNEs). However, they have been ignored in the MNE staffing literature which has developed a staffing typology based on nationality, specifically parent country nationals (PCNs), host country nationals (HCNs), and third country nationals (TCNs). We propose that cultural understanding is a more appropriate criterion than nationality in categorizing staff in MNEs and compare returnees with the existing categorizations of MNE staff. Returnees may be closer to the ‘balanced individuals’ that MNEs need compared with either expatriates or locals. Therefore, they may be a good staffing choice for MNE subsidiaries in China. This study was conducted in two stages. The first stage was qualitative. Ten top executives from multinational subsidiaries in China were interviewed in order to identify and delineate the unique characteristics of returnees. They suggested that returnees understand multiple cultures, possess cross-cultural communication skills, and a global perspective; and act as a “bridge” between expatriates and locals, between a subsidiary and the other units of the MNE (including headquarters and the other subsidiaries), as well as between the MNE and the local environment. The second stage was quantitative. We first developed a theoretical model from an organizational learning perspective. We hypothesized that a subsidiary’s degree of geocentrism, ownership status, top executive background, and subsidiary age may have an impact on the employment of returnees. We further hypothesized that the ratio of returnees in a management team may have a positive impact on subsidiary performance, and that socialization and geocentrism may moderate this relationship. A survey was used to collect the primary data for hypotheses testing. Questionnaires were sent to top executives in multinational subsidiaries in mainland China. We found that joint ventures employ fewer returnees than wholly owned subsidiaries, and that returnee and expatriate top executives are more likely to hire returnees than local top executives. In addition, the relationship between subsidiary age and employment of returnees takes a downward sloping U-shape, which is similar to the relationship between subsidiary age and employment of expatriates in the literature. On the other hand, joint ventures are more likely than wholly owned subsidiaries to have a returnee as the top executive, and subsidiary age has a negative impact on the possibility of a returnee being the top executive. We also found that employment of expatriates negatively impacts employment of returnees. We did not observe any relationship between returnees and subsidiary performance. This study contributes to the literature by proposing a new criterion for staffing categorization in MNEs, by studying a new type of staff – returnees, by focusing on the subsidiary level, and by combining qualitative and quantitative data. It directs us to a promising direction in MNE staffing research and has the potential to help managers develop more effective overseas staffing strategies.
2010-11-29T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/66
https://ir.lib.uwo.ca/context/etd/article/1070/viewcontent/thesis_final.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
MNE staffing
returnees
sea turtles
ex-host country nationals
expatriate
subsidiary performance
International Business
oai:ir.lib.uwo.ca:etd-1071
2010-11-01T21:39:20Z
publication:etdlac
publication:faculties
publication:chem
publication:chem-etd
publication:etd
Surface Modifications of Poly(dimethylsiloxane) for Biological Application of Microfluidic Devices
Dechene, Jessica M
The spatial control of cellular adhesion is fundamental to the development of studies of cell interaction, cellular microarrays, and cell based biosensors. The ability to pattern cell adhesion on flat substrates and in microfluidic channels is important for locating cell near microdetectors in cell based biosensor devices. Cell adhesion can be controlled by patterning a material's wettability, as cells are able to adhere to hydrophilic surface and will generally avoid hydrophobic materials.
This thesis focuses on patterning the surface wettability of poly(dimethylsilox-ane) (PDMS) in order to spatially control cell adhesion. The polymer is selectively modifed by the deposition of aluminum through a stencil mask in a magnetron sputtering system. After etching away the aluminum layer, a hydrophilic oxygen rich silica-like layer is exposed. This technique permits the creation of hydrophilic dots which are surrounded by the hydrophobic native PDMS. A second technique involving the use of photolithography results in a surface that can undergo hydrophobic recovery. By contrast, the selected areas covered by aluminum are protected against hydrophobic recovery. Finally, photolithography is used to selectively react a methyl terminated alkyl silane with the modified surface.
Each surface modification was characterized by X-ray photoelectron spectros-copy, atomic force microscopy, contact angle measurements, force distance curves, cell attachment and viability tests; the effectiveness of the techniques to pattern wettability and cell adhesion was assessed. The relative adsorption of fibronectin and fibrinogen was visualized on the patterned surface. Further, the relative availability of the cell binding sites were also visualized on the surface through immunofluorescent labeling.
While all patterning methods were effective at controlling surface wettability, cells did not show any selectivity on the surfaces patterned for hydrophobic recovery. The use of an alkyl silane proved more effective, as cell attachment did show some selectivity. However, cells were able to adhere and grow on the hydrophobic silanized regions. The stencil mask patterned surfaces showed cell selectivity, with cells almost completely avoiding the native hydrophobic PDMS background.
Overall, the stencil mask patterning technique proved to be the most effective at controlling cell adhesion. Thus this surface patterning technique was integrated into reversibly and irreversible sealed microfluidic channels.
2010-10-29T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/24
https://ir.lib.uwo.ca/context/etd/article/1071/viewcontent/Dechene_Jessica_M_201010_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
cell adhesion
magnetron sputtering
microfluidic
micropatterning
poly(dimethylsiloxane)
surface modification
Materials Chemistry
oai:ir.lib.uwo.ca:etd-1073
2011-11-15T19:23:39Z
publication:csd
publication:csd-etd
publication:faculties
publication:etd
Characterizing and Diagnosing Architectural Degeneration of Software Systems from Defect Perspective
Li, Zude
The architecture of a software system is known to degrade as the system evolves over time due to change upon change, a phenomenon that is termed architectural degeneration. Previous research has focused largely on structural "deviations" of an architecture from its baseline. However, another angle to observe architectural degeneration is software defects, especially those that are architecturally related. Such an angle has not been scientifically explored until now. Here, we ask two relevant questions: (1) What do defects indicate about architectural degeneration? and (2) How can architectural degeneration be diagnosed from the defect perspective? To answer question (1), we conducted an exploratory case study analyzing defect data over six releases of a large legacy system (of size approximately 20 million source lines of code and age over 20 years). The relevant defects here are those that span multiple components in the system (called multiple-component defects - MCDs). This case study found that MCDs require more changes to fix and are more persistent across development phases and releases than other types of defects. To answer question (2), we developed an approach (called Diagnosing Architectural Degeneration - DAD) from the defect perspective, and validated it in another, confirmatory, case study involving three releases of a commercial system (of size over 1.5 million source lines of code and age over 13 years). This case study found that components of the system tend to persistently have an impact on architectural degeneration over releases. Especially, such impact of a few components is substantially greater than that of other components. These results are new and they add to the current knowledge on architectural degeneration. The key conclusions from these results are: (i) analysis of MCDs is a viable approach to characterizing architectural degeneration; and (ii) a method such as DAD can be developed for diagnosing architectural degeneration.
2010-10-29T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/30
https://ir.lib.uwo.ca/context/etd/article/1073/viewcontent/Li_Zude_201011_PhD_Thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
architectural degeneration
software architecture
software defect
software change
software maintenance
case study
tool technology
Software Engineering
oai:ir.lib.uwo.ca:etd-1075
2010-09-24T18:05:00Z
publication:physiology-etd
publication:physpharm
publication:faculties
publication:etd
The roles of nitric oxide synthases (NOS) in endochondral bone formation
Yan, Qian
Longitudinal growth of endochondral bones is controlled by the cartilage growth plate. Chondrocyte proliferation and hypertrophy, vascular invasion, formation of ossification centers and cartilage replacement by bone tissue are all important processes required for normal growth. These biological processes have to be tightly regulated or disturbances will lead to skeletal diseases. A large number of genes, growth factors and hormones have been implicated in the regulation of growth plate biology, however, less is known about the intracellular signaling pathways involved. Nitric oxide (NO) has been identified as a regulator of cellular proliferation, differentiation, migration, survival and metabolism in multiple cell types. In bone biology, it has been implicated in bone remodeling and the pathogenesis of osteoarthritis, but the roles of specific nitric oxide synthase (NOS) enzymes in chondrocyte physiology and cartilage development are unclear. The goal of this thesis was to analyze the roles of NOS/NO signaling in specific stages of endochondral bone formation. We had shown recently that chondrocyte-specific deletion of the Rac1 gene results in severe dwarfism due to reduced chondrocyte proliferation in mice, but the molecular pathways involved remained unknown. Employing a Rac1-deficient monolayer chondrocyte culture, we showed that loss of Rac1 results in severely reduced levels of inducible nitric oxide synthase (iNOS) protein and NO production. Additionally, reduced iNOS expression was found in Rac1-decifient mice in vivo. Using a tibia organ culture system, we showed that NO donors rescued the antiproliferative effects of Rac1 inhibition. Examination of the growth plate of iNOS-deficient mice revealed reduced chondrocyte proliferation and decreased expression of cyclin D1, while ATF3, a suppressor of cyclin D1 transcription, showed increased expression. Thus, we identified iNOS/NO as a novel mediator of Rac1 signaling and ATF3 as a link between iNOS and chondrocyte cell cycle. Doe to the skeletal phenotypes we observed in iNOS-deficient mice, my next study investigated effects of inactivation of endothelial nitric oxide synthase (eNOS) on cartilage development in mice. eNOS-deficient mice showed increased lethality and reduced bone growth, delayed ossification and a marked reduction in the number of proliferating chondrocytes. The mechanisms leading to these bone phenotypes appear to be caused by decreased cyclin D1 and increased p57 expressions in mutants, resulting in slower cell cycle progression and earlier cell cycle exit. Additionally, expression of early chondrocyte markers such as Sox9 was reduced and prehypertrophic markers were upregulated in mutant mice. Because my studies had shown upregulation of nNOS in eNOS-null cartilage, next I analyzed the skeletal phenotype of nNOS-deficient mice. Transient growth retardation, reduced length of long bones, less trabecular bone and decreased mineralization were shown in nNOS KO mice. Reduced proliferating chondrocyte numbers in mutants may in part be due to premature cell cycle exit, shown by reduced cyclin D1 and upregulated p57 expressions. Similar to the other two mutant strains, ATF3 was a link between nNOS and reduced cyclin D1 expression. In addition, I demonstrated increased apoptosis, reduced early chondrocyte markers such as Sox genes and increased prehypertrophic markers RORα and c-Fos in mutant mice. Together, these data suggest that NOS/NO presents a core signaling pathway to regulate chondrocyte proliferation and differentiation through control of cell cycle protein.
2010-09-24T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/15
https://ir.lib.uwo.ca/context/etd/article/1075/viewcontent/QYan_PhD_thesis_sept24_2010.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
cartilage development; chondrocyte; NO; NOS; cell-cycle control;
Cell Biology
Cellular and Molecular Physiology
Developmental Biology
oai:ir.lib.uwo.ca:etd-1076
2011-11-15T19:25:27Z
publication:biology-etd
publication:biology
publication:faculties
publication:etd
The Lotus japonicus cytokinin receptor gene family and its role in nitrogen-fixing symbiosis
Held, Mark A.
Nitrogen is the most abundant element in our atmosphere, yet has become increasingly limited in agricultural lands. Legume plants offer a possible solution to this problem due to their innate ability to symbiotically interact with nitrogen-fixing bacteria called rhizobia. In particular, a histidine kinase cytokinin receptor from the model legume Lotus japonicus (LHK1) has been clearly placed at the core of these interactions. Loss-of-function mutants in LHK1 fail to initiate timely cortical cell divisions in response to abundant bacterial infection, and gain-of-function mutations in the same locus cause L. japonicus plants to form spontaneous nodules in the absence of rhizobia, thus indicating that this receptor is required and sufficient for nodule organogenesis. However, nodulation events do still occur in lhk1-1 mutants. Therefore, this study has sought to address how nodule organogenesis persists in the lhk1-1 mutant background; is this achieved through cytokinin-independent signaling or perhaps redundancy in function with other members of the LHK family? To that end, the present study has identified three new Lhk loci from L. japonicus (described herein as Lhk1A, Lhk2, and Lhk3) and provides a detailed characterization of their roles during the NFS. Furthermore, we highlight the pivotal role of LHK1 signalling during the NFS, but also clearly indicate that the role of this receptor is not entirely unique. Indeed, other LHK family members share promoter localization profiles with LHK1 and can complement for loss-of-function mutations in LHK1. The results have allowed for the refinement of current models involving the cytokinin signalling network, which highlight a possible role for other receptors during LHK1-independent signalling events in the root cortex.
2010-11-02T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/27
https://ir.lib.uwo.ca/context/etd/article/1076/viewcontent/Thesis_Draft_FINAL_11_05_2010.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Lotus japonicus
nitrogen-fixing symbiosis
rhizobia
mycorrhizal fungus
cytokinin
histidine kinase
Biology
oai:ir.lib.uwo.ca:etd-1077
2011-11-15T19:26:19Z
publication:biology-etd
publication:biology
publication:faculties
publication:etd
Stopover biology of migratory landbirds in a heavily urbanized landscape, the New York metropolitan area
Seewagen, Chad L
Migration routes of many Nearctic-Neotropical landbirds pass through the most urbanized regions of North America. Migrants use urban habitat fragments as stopover sites and commonly occur in cities at exceptional density. Yet, knowledge of migrant stopover biology and refueling opportunities in such places is severely limited. This dissertation examined several aspects of migrant stopover biology in the New York metropolitan area to gain a more holistic understanding of how migratory landbirds utilize urban stopover sites, and ultimately to assess the quality of urban habitats as stopover sites. I first generated morphometric predictive models using salvaged bird specimens to allow me in subsequent studies to noninvasively measure the energetic condition (fat mass) of migrants in New York City (NYC). Next I compared the refueling performance of migrants in NYC to that of conspecifics in less-disturbed forests outside of the city. Blood plasma metabolite profiles indicated that refueling conditions for migrants were no poorer in NYC than in the non-urban habitats. Further, migrant refueling rates were comparable to, and in some cases higher than, those reported in the literature for birds at various non-urban stopover sites. Measures of arthropod biomass suggested food abundance for insectivorous migrants was also similar within and outside NYC. I then showed that stopover refueling in NYC often involved substantial increases in lean mass. This finding carries implications for stopover habitat management practices, as migrants using these sites will require high-protein foods in addition to the lipid- and carbohydrate-rich foods that maximize fattening rates. Next, radio-telemetry data from a small pilot study provided one of the first descriptions of migrant stopover durations within a city. Stopover durations ranged 1-14 days and were negatively related to fat mass, but not lean body mass, upon arrival. A larger-scale telemetry study revealed that migrant spatial behaviour in NYC was in many ways similar to what has been observed in passerine migrants in non-urban areas. Movement patterns were indicative of an ability to search for, locate, and occupy suitable microhabitat, and temporary home ranges suggested forest size was more than sufficient to meet their area requirements. Collectively, these studies provide a comprehensive assessment of the quality of urban habitats as migratory bird stopover sites. Findings indicated that the sites examined are functioning in the same fashion as less-disturbed, larger forest tracts elsewhere. No evidence was found to suggest that stopover refueling conditions within one of the world’s most urbanized landscapes are inadequate for migrating landbirds.
2010-11-16T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/31
https://ir.lib.uwo.ca/context/etd/article/1077/viewcontent/Seewagen__Chad_L_201011_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Urban habitat
stopover site quality
refueling rate
plasma metabolites
Behavior and Ethology
Terrestrial and Aquatic Ecology
oai:ir.lib.uwo.ca:etd-1078
2010-12-13T21:43:28Z
publication:faculties
publication:chem
publication:chem-etd
publication:etd
Part I: Synthesis of Pyrrolo[1,2-A]Indoles Part II: Studies Towards Arboflorine
Johansen, Michael B.
Part one of this thesis focuses on the synthesis of pyrrolo[1,2-a]indoles from nitrones and 1,1-cyclopropanediesters, by way of tetrahydro-1,2-oxazines. A five step synthetic sequence through tetrahydro-1,2-oxazine synthesis, intramolecular Heck reaction, Krapcho dealkoxycarbonylation, reductive N-O bond cleavage, and acid catalyzed transannular alcohol displacement, is developed to access the desired pyrrolo[1,2-a]indoles. Part two of this thesis details the functionalization of indoles by installation of a malonate moiety, by means of copper catalyzed carbenoid reactivity. A wide range of malonyl indoles with varying substitution patterns is shown to be accessible through the developed method. The final chapter focuses on the application of this reaction in a biomimetic approach towards the total synthesis of the indole alkaloid arboflorine. This reaction provided access to an advanced intermediate which allowed for the study of a key Mannich ring closure step that was proposed in the postulated biogenesis of the natural product. The current synthetic sequence includes the copper catalyzed malonyl carbenoid insertion, reduction of a pyridinium salt, reductive ammination, and a Polonovski-Potier reaction to install and mask an iminium motif. As of yet, the proposed Mannich reaction has been unsuccessful in securing the required azepane ring.
2010-11-18T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/33
https://ir.lib.uwo.ca/context/etd/article/1078/viewcontent/Johansen_Michael_B_201011_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Pyrrolo[1
2-a]indole
Indole
Cyclopropane
Carbene
Arboflorine
Biomimetic.
Organic Chemistry
oai:ir.lib.uwo.ca:etd-1079
2010-12-22T04:10:09Z
publication:english
publication:english-etd
publication:faculties
publication:etd
Graphomania: Composing Subjects in Late-Victorian Gothic Fiction and Technology
Brophy, Gregory D
This dissertation explores the varied phenomena of “automatic writing” in Victorian Gothic fiction, reading the genre’s fascination with the irrepressible signifying practices of the body in light of the medical, criminological and scientific discourses that underwrite the “scriptural economy” of the late nineteenth century with their own arsenal of automatic writing machines. I have titled the project "Graphomania," and I consider the term a keyword of late-Victorian culture—one that names a distinctly Victorian pathology of compulsive writing, but that alludes also to the widespread epistemic hope that writing could render objectively the internal and subjective experiences of individuals.
In a chapter devoted to Victorian graphomania and the three studies that follow (graphology in Jekyll and Hyde, retinal photography in The Beetle, and phonography in Dracula), the project is particularly interested in convergences and correspondences between graphical machines and human bodies. In this study, Victorian technology and Gothic literature emerge as twin registers of the divided self, joined in their shared strategy of externalizing conflicts traditionally understood as invisible processes, but also in the consequent tendency of each uncanny text to expose its ghostly remainders and excesses in the process of trying to contain them.
2010-11-16T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/63
https://ir.lib.uwo.ca/context/etd/article/1079/viewcontent/FGS_Dissertation.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Victorian
Gothic
Technology
Media
Automatic Writing
Embodiment
English Language and Literature
Literature in English, British Isles
oai:ir.lib.uwo.ca:etd-1080
2012-10-02T17:46:26Z
publication:edu
publication:faculties
publication:edu-etd
publication:etd
Cambodian National Education Policy: Global Wants and/or Local Needs?
Crowley, Kelly T, Dr.
This thesis is broadly concerned with the impact of globalization on education policy making in Cambodia, a post-conflict, developing country. Cambodia’s education system was almost entirely wiped out by the 1990’s because of various military and social conflicts that had plagued the country. As such, Cambodia provides an excellent case of post-conflict educational reconstruction. The thesis will explore how multinational financial organizations such as the World Bank and Asian Development Bank are influencing the direction of national education policy in Cambodia, using a globalization theoretical perspective. The focus will be on a policy analysis of several key policy documents and directives from the multinational organizations and Cambodian government. Through this analysis three themes become apparent. These include the marketization of education, partnerships, and the purpose of education in Cambodia. These themes present a complex picture of an education system in transition under the influence of national and international needs and desires.
2010-10-05T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/17
https://ir.lib.uwo.ca/context/etd/article/1080/viewcontent/auto_convert.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
globalization
post-conflict
Southeast Asia
policy analysis
national education policy
multinational organizations
International and Comparative Education
oai:ir.lib.uwo.ca:etd-1081
2010-12-13T19:21:12Z
publication:epidem
publication:epidem-etd
publication:faculties
publication:etd
The Health of Ontario’s Transgender Communities: Prevalence of and Risk Factors for Depression, "Do-It-Yourself" Transitions, and Health Effects of Cross-Sex Hormones and Surgeries
Khobzi, Nooshin
The purpose of this dissertation was to develop an understanding of, and draw attention to, the health and service access issues faced by trans (transgender, transsexual, or transitioned) Ontarians. This thesis is based on the Trans PULSE Project, a community-based research (CBR) initiative whose goal is to improve the health of trans people. Data collection was carried out between May 2009 and April 2010 using a quantitative survey. Trans participants were recruited through respondent-driven sampling (RDS), a network-based sampling method developed for the recruitment of hidden populations. Weighted prevalence estimates and 95% confidence intervals were calculated for all variables of interest using methods that compensate for non-random recruitment patterns. The first manuscript outlines the lessons learned from doing participatory doctoral research, and provides a guide for students in the form of key recommendations. The second manuscript assessed the prevalence of and risk factors for depression among male-to-female (MTF) and female-to-male (FTM) Ontarians. Our findings indicate that depression is widespread among MTFs and FTMs. Furthermore, multivariable regression analyses revealed that the risk factors associated with depression varied between MTFs and FTMs in Ontario. This research is a first step in understanding the complex mental health issues of a highly marginalized community.
The third manuscript characterized and examined the extent of “do-it-yourself” transitions among trans people in Ontario. While self-performed surgeries and current use of non-prescribed hormones were uncommon, this study indicates that trans people’s experiences with providers may have played a role in their willingness to seek hormones from non-medical sources. Lastly, the fourth manuscript explored the long-term positive and adverse health effects associated with hormone use and SRS. We found no evidence that hormone use among MTF and FTM people in Ontario conferred negative effects on health. While some conditions were relatively common (sleep apnea, high cholesterol, and hypertension), almost all other outcomes were rare. These results are informative and may provide health care providers with the knowledge to make more informed treatment and screening decisions. More specifically, our findings show that the fear of “doing harm” by prescribing hormones to trans people is likely unfounded.
2010-11-17T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/41
https://ir.lib.uwo.ca/context/etd/article/1081/viewcontent/Khobzi_Nooshin_201011_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
transsexual
transgender
community-based research
respondent-driven sampling
depression
hormone use
Epidemiology
oai:ir.lib.uwo.ca:etd-1083
2011-11-15T19:29:17Z
publication:edu
publication:faculties
publication:edu-etd
publication:etd
The Professional Master's Occupational Therapist: Developing an Emerging Professional Identity
Jung, Bonny F
The purpose of this study is to explore the emerging professional identity of the professional master’s entry-level occupational therapist. The questions are: 1) What does it mean to be a professional as an occupational therapist? 2) How do professional identities emerge for the professional master’s entry-level occupational therapist? From a professional perspective as an occupational therapist and educator, helping clients and students find meaning in their occupations is an integral part of my ontology of practice. To conduct this study, I used a constructivist paradigm within qualitative research as my primary lens and constructivist grounded theory as my methodology to organize, analyse and present the findings. From a personal perspective, I am also influenced by my cultural beliefs and understandings. Constructivism, which focuses on how individuals construct meaning in their situations, has a parallel to the philosophy of Feng Shui which is a long and well-established practice in Chinese society that specifies the relationship between people and their environment. I used the concepts from Feng Shui which emerged later in my study as my second conceptual lens to frame and explain my findings. The primary data source was through semi-structured interviews in a group, in pairs and individually with 11 participants. Several secondary sources of data were utilized including the University Exit Survey from the 2003 graduates, researcher field notes, and literature review. The concept of occupational therapy as a profession was explored to help inform the study purpose. The experiences of participants reflected their ability to provide an important function and service to society, to practice in a way that respects and honours the client-therapist relationship, to advance the stance of the profession to others and, to develop and maintain personal learning competencies that can sustain them over time within their careers. Reflection is the threaded skill that participants used to help make sense of their clinical experiences. These factors related to being a professional contributed to their understanding of their professional identity. Although some of the findings are supported and reflected in the literature on occupational therapy, health sciences or education, new findings are suggested specific to professional master’s entry-level occupational therapists. These new findings are related to dissonance in identities, client-centred focus, access to higher education, power in practice and, potential career and educational paths of applicants. Implications for OT education and practice are suggested that involve actions from stakeholders including individual occupational therapists, educational programs, regulatory bodies, professional associations, and employers. Limitations to the study and future research directions are suggested. The overarching findings as a result of this study are: • Professional identity is a complex construct that involves the integration and negotiation of multiple identities. • Reflection is the threaded skill that helps novice occupational therapists make sense of their experiences within their multiple identities—from a Feng Shui perspective and from a praxis perspective.
2010-03-12T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/18
https://ir.lib.uwo.ca/context/etd/article/1083/viewcontent/auto_convert.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
occupational therapy
graduate education
profession
professional identity
Curriculum and Social Inquiry
oai:ir.lib.uwo.ca:etd-1084
2010-10-05T22:56:43Z
publication:mechanical-etd
publication:faculties
publication:mechanical
publication:etd
Atomic Force Microscopy for Better Probing Surface Properties at Nanoscale: Calibration, Design and Application
Liu, Yu
To measure force by AFM with high resolution requires accurate calibration of optic – lever detection sensitivity and spring constant. On biological AFM force mode, the coupling effects of the liquid environment, spot size of laser beam and laser spot location on AFM cantilever backside, must be considered to correlate the static sensitivities from force curves in air and in liquid for calibration. An effective model has been developed first and experimentally elucidated to calibrate the static sensitivity in liquid. The proposed model eliminates inconvenience of static sensitivity calibration in liquid with possible contamination sources.
The static sensitivity based on force curve can not be directly applied on dynamic modes. The second part of our work analyzed optimization of the dynamic sensitivity of an AFM vibrating at different flexural modes. We have proposed a calibration method to determine the dynamic sensitivity by the force curve, and further developed amplitude sensitivity as the dynamic sensitivity at tapping frequency to calibrate the spring constant of the cantilever by the thermal method.
In contrast to the calibration at normal direction, there are main difficulties for the lateral sensitivity and spring constant of a cantilever. A new friction mode is developed in the third part to bypass the difficulties and directly measure friction force or friction coefficient instead, by applying a special T–shape cantilever. An effective method has been proposed to minimize possible errors with this friction mode. We also demonstrate the validation of the mode to distinguish hydrophobic and hydrophilic groups at nanoscale.
2010-10-28T13:21:39Z
text
application/pdf
https://ir.lib.uwo.ca/etd/21
https://ir.lib.uwo.ca/context/etd/article/1084/viewcontent/Liu_Yu_201009_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Atomic Force Microscopy
Optical Lever Detection Sensitivity
Higher-order Flexural Mode
Tip - Sample Interaction
Lateral Friction Force
Force Modulation
Applied Mechanics
Nanoscience and Nanotechnology
Tribology
oai:ir.lib.uwo.ca:etd-1085
2010-12-10T18:57:13Z
publication:psychology-etd
publication:psychology
publication:faculties
publication:etd
Mental Blocks: The behavioural effects and neural encoding of obstacles when reaching and grasping
Chapman, Craig S
The ability to adeptly interact with a cluttered and dynamic world requires that the brain simultaneously encode multiple objects. Theoretical frameworks of selective visuomotor attention provide evidence for parallel encoding (Baldauf & Deubel, 2010; Cisek & Kalaska, 2010; Duncan, 2006) where concurrent object processing results in neural competition. Since the end goal of object representation is usually action, these frameworks argue that the competitive activity is best characterized as the development of visuomotor biases. While some behavioural and neural evidence has been accumulated in favour of this explanation, one of the most striking, yet deceptively common, demonstrations of this capacity is often overlooked; the movement of the arm away from an obstacle while reaching for a target object is definitive proof that both objects are encoded and affect behaviour. In the current thesis, I discuss three experiments exploring obstacle avoidance.
While some previous studies have shown how visuomotor biases develop prior to movement onset, the dynamics of the bias during movement remains largely unexplored. In the first experiment I use the availability and predictability of vision during movement as a means of exploring whether obstacle representations might change during a reach (Chapter 2, Chapman & Goodale, 2010b). While the visuomotor system seems optimized to use vision, I found no difference between reaching with and without vision, providing no evidence that obstacle representations were altered. To more directly test this question, in the second experiment participants made reaches to a target that sometimes changed position during the reach (Chapter 3, Chapman & Goodale, 2010a). The automatic online corrections to the new target location were sometimes interfered with by an obstacle. Using this more direct approach we found definitive evidence that obstacle representations were accessed or updated during movement.
In the third experiment, I directly tested the neural encoding of obstacles using functional magnetic resonance imaging (Chapter 4, Chapman, Gallivan, Culham, & Goodale, 2010). When participants planned a grasp movement that was interfered with by an obstacle versus when the grasp was not interfered with, one area in the left posterior intraparietal sulcus was activated. This activity was concurrent with a suppression of early visual areas that were responsive to the position of the obstacle. This study confirmed that the PPC was involved with the encoding of obstacles, and demonstrated that one effect of interference was the suppression of the visual cortical signal associated with the obstacle.
These findings extend our understanding of competitive visuomotor biases. Critically, in a world filled with potential action targets, the selection of one target necessarily means all other objects in the workspace are potential obstacles. My results indicate that the visuomotor biasing signal to inhibit obstacle activity is putatively provided by the PPC, which in turn causes the visual cortical representation of the obstacle to be suppressed. The behavioural result of biasing the visual input is the propagation of this suppression to the motor output - ultimately resulting in a reach which intelligently deviates away from potential obstacles.
2010-11-26T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/39
https://ir.lib.uwo.ca/context/etd/article/1085/viewcontent/Chapman_Craig_S_201012_PhD_Thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
obstacle avoidance
human reaching and grasping
selective visuomotor attention
visual feedback
online correction
fMRI
Cognition and Perception
Cognitive Neuroscience
Motor Control
Psychology of Movement
oai:ir.lib.uwo.ca:etd-1086
2011-11-15T19:30:21Z
publication:mechanical-etd
publication:faculties
publication:mechanical
publication:etd
Collision Detection and Merging of Deformable B-Spline Surfaces in Virtual Reality Environment
Pungotra, Harish
This thesis presents a computational framework for representing, manipulating and merging rigid and deformable freeform objects in virtual reality (VR) environment. The core algorithms for collision detection, merging, and physics-based modeling used within this framework assume that all 3D deformable objects are B-spline surfaces. The interactive design tool can be represented as a B-spline surface, an implicit surface or a point, to allow the user a variety of rigid or deformable tools. The collision detection system utilizes the fact that the blending matrices used to discretize the B-spline surface are independent of the position of the control points and, therefore, can be pre-calculated. Complex B-spline surfaces can be generated by merging various B-spline surface patches using the B-spline surface patches merging algorithm presented in this thesis. Finally, the physics-based modeling system uses the mass-spring representation to determine the deformation and the reaction force values provided to the user. This helps to simulate realistic material behaviour of the model and assist the user in validating the design before performing extensive product detailing or finite element analysis using commercially available CAD software. The novelty of the proposed method stems from the pre-calculated blending matrices used to generate the points for graphical rendering, collision detection, merging of B-spline patches, and nodes for the mass spring system. This approach reduces computational time by avoiding the need to solve complex equations for blending functions of B-splines and perform the inversion of large matrices. This alternative approach to the mechanical concept design will also help to do away with the need to build prototypes for conceptualization and preliminary validation of the idea thereby reducing the time and cost of concept design phase and the wastage of resources.
2010-11-12T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/32
https://ir.lib.uwo.ca/context/etd/article/1086/viewcontent/Pungotra_Harish_201011_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
collision detection; merging B-spline surfaces; virtual reality; concept design; modeling and simulation; deformable object; B-spline surface.
Computer-Aided Engineering and Design
oai:ir.lib.uwo.ca:etd-1087
2011-11-15T19:31:10Z
publication:stats
publication:faculties
publication:stats-etd
publication:etd
Survival Analysis of Microarray Data With Microarray Measurement Subject to Measurement Error
Xiong, Juan
Microarray technology is essentially a measurement tool for measuring expressions of genes, and this measurement is subject to measurement error. Gene expressions could be employed as predictors for patient survival, and the measurement error involved in the gene expression is often ignored in the analysis of microarray data in the literature. Efforts are needed to establish statistical method for analyzing microarray data without ignoring the error in gene expression. A typical microarray data set has a large number of genes far exceeding the sample size. Proper selection of survival relevant genes contributes to an accurate prediction model. We study the effect of the measurement error on survival relevant gene selection under the accelerated failure time (AFT) model setting by regularizing weighted least square estimator with adaptive LASSO penalty. The simulation results and real data analysis show that ignoring measurement error will affect survival relevant gene selection. Simulation-Extrapolation (SIMEX) method is investigated to adjust the impact of measurement error to gene selection. The resulting model after adjustment is more accurate than the model selected by ignoring measurement error. Microarray experiments are often performed over a long period of time, and samples can be prepared and collected under different conditions. Moreover, different protocols or methodology may be applied in the experiment. All these factors contribute to a possibility of heteroscedastic measurement error associated with microarray data set. It is of practical importance to combine microarray data from different labs or platforms. We construct a prediction AFT model using data with heterogeneous covariate measurement error. Two variations of the SIMEX algorithm are investigated to adjust the effect of the mis-measured covariates. Simulation results show that the proposed method can achieve better prediction accuracy than the naive method. In this dissertation, the SIMEX method is used to adjust for the effects of covariate measurement error. This method is superior to other conventional methods in that it is not only more robust to distributional assumptions for error prone covariates, it also offers marked simplicity and flexibility for practical use. To implement this method, we developed an R package for general users.
2010-11-22T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/34
https://ir.lib.uwo.ca/context/etd/article/1087/viewcontent/Xiong_Juan_201011_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Accelerated failure time model
Measurement error
Microarray
Predction
Simulation and extrapolation method
Variable selection.
Biostatistics
Microarrays
Survival Analysis
oai:ir.lib.uwo.ca:etd-1088
2010-10-13T04:04:13Z
publication:civil
publication:faculties
publication:etd
publication:civil-etd
Numerical Assessment of Roof Panel Uplift Capacity under Wind Load
He, Weixian
ABSTRACT
The integrity of the roof system is essential for ensuring the safety of inhabitants and preventing excessive damage to light-frame wood structures. The uplift capacity of fastened roof panels has been investigated using experimental tests and numerical models, where monotonic uniform static pressures are often applied to the roof panel models. The verification is needed for the adequacy of using static uniformly distributed pressure representing the wind load. Moreover, the uncertainty of nail withdrawal behaviour has not been included in existing numerical models, and the effect due to construction errors has not been addressed rationally.
A nonlinear Finite Element model is developed in this study to incorporate the nail withdrawal uncertainty in terms of maximum withdrawal force, initial stiffness, proportional limit, and the displacement at maximum force of the nail withdrawal behaviour. This model is used to investigate the statistical characteristics of the panel uplift capacity. The effect of spatial varying wind load is discussed by using the pressure coefficient obtained from wind tunnel model test at the Boundary Layer Wind Tunnel at the University of Western Ontario.
Furthermore, the impact of construction error is investigated, in terms of missing nail effects, with first-hand survey information. The detailed survey was carried out at the IRLBH (The Insurance Research Lab for Better Homes) facility to inspect the quality of construction, specifically for the statistical information of missing nails on roof panels. Finally, the evaluated statistical characterization of panel uplift capacity is used for the reliability analysis of a typical panel considering or ignoring the missing nail effects.
Both code specified pressure-gust coefficient from NBCC (2005) and the peak pressure coefficients obtained from wind tunnel test are used. Results suggested that the nonlinear pushover analysis using the proposed nonlinear Finite Element model is adequate for estimating the panel uplift capacity. A more stringent fastening schedule with a spacing of 150 mm for the edges and intermediate supports is suggested for the construction of light frame wood houses.
2010-10-13T15:06:30Z
text
application/pdf
https://ir.lib.uwo.ca/etd/19
https://ir.lib.uwo.ca/context/etd/article/1088/viewcontent/Thesis_He.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Uplift capacity
roof panel
wind pressure
spatial varying
nail spacing
Civil Engineering
Structural Engineering
oai:ir.lib.uwo.ca:etd-1089
2010-12-17T20:59:58Z
publication:stats
publication:etdlac
publication:faculties
publication:stats-etd
publication:etd
Model Selection with Information Criteria
Xu, Changjiang
This thesis is on model selection using information criteria. The information criteria include generalized information criterion and a family of Bayesian information criteria. The properties and improvement of the information criteria are investigated.
We analyze nonasymptotic and asymptotic properties of the information criteria for linear models, probabilistic models, and high dimensional models, respectively. We give probability of selecting a model and compute the probability by Monte Carlo methods. We derive the conditions under which the criteria are consistent, underfitting, or overfitting.
We further propose new model selection procedures to improve the information criteria. The procedures combine the information criteria with the probability of selecting a model and overfitting level, respectively.
In addition, we develop model selection software packages in R and examine applications to real data.
2010-10-29T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/46
https://ir.lib.uwo.ca/context/etd/article/1089/viewcontent/Xu_Changjiang_201011_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Statistical modeling
model selection
variable selection
penalized likelihood
model selection criterion
information criteria
Statistics and Probability
oai:ir.lib.uwo.ca:etd-1090
2010-12-12T18:21:05Z
publication:stats
publication:faculties
publication:stats-etd
publication:etd
Cost-efficient Variable Selection Using Branching LARS
Yue, Li Hua
Variable selection is a difficult problem in statistical model building. Identification of cost efficient diagnostic factors is very important to health researchers, but most variable selection methods do not take into account the cost of collecting data for the predictors. The trade off between statistical significance and cost of collecting data for the statistical model is our focus. A Branching LARS (BLARS) procedure has been developed that can select and estimate the important predictors to build a model not only good at prediction but also cost efficient. BLARS method is an extension of the LARS variable selection method to incorporate various costs of factors, where branch and bound search method is employed to accelerate the search process. Both additive and non-additive costs will be addressed. The R package branchLars which implements BLARS will be described. We will show that a "cheaper" model could be selected by sacrificing a user selected amount of model accuracy.
2010-11-25T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/43
https://ir.lib.uwo.ca/context/etd/article/1090/viewcontent/Yue_Lihua_201012_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Variable selection
Cost efficient
BLARS
LARS
Lasso
Branch and bound
Biostatistics
oai:ir.lib.uwo.ca:etd-1091
2010-12-13T23:30:47Z
publication:etdlac
publication:electrical
publication:electrical-etd
publication:faculties
publication:etd
A New Signal Processing Approach to Study Action Potential Content in Sympathetic Neural Signals
Salmanpour, Aryan
Sympathetic nerve activity plays an essential role in the normal regulation of blood pressure in humans and in the etiology and progression of many chronic diseases. Sympathetic nerve recordings associated with blood pressure regulation can be recorded directly using microneurography. A general characteristic of this signal is spontaneous burst activity of spikes (action potentials) separated by silent periods against a background of considerable gaussian noise. During measurement with electrodes, the raw muscle sympathetic nerve activity (MSNA) signal is amplified, band-pass filtered, rectified and integrated. This integration process removes important information regarding action potential content and their discharge properties.
The first objective of this thesis was to propose a new method for detecting action potentials from the raw MSNA signal to enable investigation of post-ganglionic neural discharge properties. The new method is based on the design of a mother wavelet that is matched to an actual mean action potential template extracted from a raw MSNA signal and applying it to the raw MSNA signal using a continues wavelet transform (CWT) for spike detection. The performance of the proposed method versus two previous wavelet-based approaches was evaluated using 1) MSNA recorded from seven healthy participants and, 2) simulated MSNA. The results show that the new matched wavelet performs better than the previous wavelet-based methods that use a non-matched wavelet in detecting action potentials in the MSNA signal.
The second objective of this thesis was to employ the proposed action potential detection and classification technique to study the relationship between the recruitment of sympathetic action potentials (i.e., neurons) and the size of integrated sympathetic bursts in human MSNA signal. While in other neural systems (e.g. the skeletal motor system) there is a well understood pattern of neural recruitment during activation, our understanding of how sympathetic neurons are coordinated during baseline and baroreceptor unloading are very limited. We demonstrate that there exists a hierarchical pattern of recruitment of additional faster conducting neurons of larger amplitude as the sympathetic bursts become stronger. This information has important implications for how blood pressure is controlled, and the malleability of sympathetic activation in health and disease.
2010-11-29T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/44
https://ir.lib.uwo.ca/context/etd/article/1091/viewcontent/Salmanpour_Aryan_201011_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Muscle sympathetic nerve activity
Action potential detection and classification
Microneurography
Wavelet analysis
Electrical and Computer Engineering
oai:ir.lib.uwo.ca:etd-1092
2010-12-17T21:18:27Z
publication:etdlac
publication:anatomy
publication:faculties
publication:anatomy-etd
publication:etd
Regulation of Akt and Wnt signalling by the dopamine D2 receptor and metabotropic glutamate receptor 2/3
Sutton, Laurie P
Akt and the Wnt pathway, two cascades that regulate GSK-3, have been implicated in schizophrenia and antipsychotic drug action. Although it is known that antipsychotic drugs alleviate psychosis by blocking the dopamine D2 receptor (D2DR) and that metabotropic glutamate receptor 2/3 (mGluR2/3) agonists may improve some of the symptoms of schizophrenia, it is unclear if both classes of drugs exert their effects through Akt, GSK-3 and/or the Wnt pathway or if changes in these pathways are mediated through the D2DR and mGluR2/3 respectively. In addition to antipsychotics, mood stabilizers and antidepressants also target GSK-3, suggesting that there must be something unique in the way GSK-3 is targeted by antipsychotics since neither mood stabilizers nor antidepressants alleviate psychosis. The current study examined whether Akt and the Wnt pathway are regulated by the D2DR and mGluR2/3 and investigated the role of Akt and Dvl-3, a key activator in the Wnt pathway, in regulating GSK-3 in the rat brain. The study also compared the effects of antipsychotic, mood stabilizers and antidepressants on Akt and Wnt pathway proteins to determine if antipsychotics have unique effects on these signalling proteins. Results showed that raclopride (D2DR antagonist) regulated Akt and the Wnt pathway via Dvl-3 and the response was identical to antipsychotic treatment. Administration of the mGluR2/3 agonist, LY379268 also targeted Akt and the Wnt pathway and induced a similar response as antipsychotics. In addition, repeated amphetamine treatment, an established animal model for the positive symptoms of schizophrenia, quinpirole (D2DR agonist) and LY341495 (mGluR2/3 antagonist) induced similar changes in Akt and Wnt signalling that parallel alterations reported in schizophrenia. Furthermore, systemic inhibition of GSK-3 was able to attenuate the increase in locomotion induced by LY341495, a behavioural measure that models the positive symptoms of schizophrenia. The study also showed that clozapine and haloperidol (antipsychotics) induced a common Wnt response that was not mimicked by the mood stabilizers or antidepressants tested but that all neuropsychiatric drugs tested induced changes in Akt. Collectively the data shows that the Wnt pathway is regulated specifically by drugs with antipsychotic properties and may represent a novel target for pharmaceutical intervention.
2010-12-07T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/47
https://ir.lib.uwo.ca/context/etd/article/1092/viewcontent/Sutton_Laurie_P_201012_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Antipsychotic drugs
Schizophrenia
Dopamine D2 receptor
Metabotropic glutamate receptor 2/3
Wnt pathway
Akt pathway
Molecular and Cellular Neuroscience
Neuroscience and Neurobiology
oai:ir.lib.uwo.ca:etd-1093
2012-11-06T20:41:50Z
publication:etdlac
publication:electrical
publication:electrical-etd
publication:faculties
publication:etd
Motion Coordination of Aerial Vehicles
Abdessameud, Abdelkader
The coordinated motion control of multiple vehicles has emerged as a field of major interest in the control community. This thesis addresses two topics related to the control of a group of aerial vehicles: the output feedback attitude synchronization of rigid bodies and the formation control of Unmanned Aerial Vehicles (UAVs) capable of Vertical Take-Off and Landing (VTOL). The information flow between members of the team is assumed fixed and undirected. The first part of this thesis is devoted to the attitude synchronization of a group of spacecraft. In this context, we propose control schemes for the synchronization of a group of spacecraft to a predefined attitude trajectory without angular velocity measurements. We also propose some velocity-free consensus-seeking schemes allowing a group of spacecraft to align their attitudes, without reference trajectory specification. The second part of this thesis is devoted to the control of a group of VTOL-UAVs in the Special Euclidian group SE(3), i.e., position and orientation. In this context, we propose a few position coordination schemes without linear-velocity measurements. We also propose some solutions to the same problem in the presence of communication time-delays between aircraft. To solve the above mentioned problems, several new technical tools have been introduced in this thesis to overcome the deficiencies of the existing techniques in this field.
2010-11-19T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/40
https://ir.lib.uwo.ca/context/etd/article/1093/viewcontent/Abdelkader_Abdessameud_PhD_thesis_final.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
motion coordination
Aerial vehicle
VTOL
attitude synchronization
formation control
output feedback control
Controls and Control Theory
oai:ir.lib.uwo.ca:etd-1094
2011-11-15T19:33:10Z
publication:etdlac
publication:modlang
publication:faculties
publication:hispanstudies-etd
publication:etd
La Crónica De Potosí Y Sus Milagros: Complejidad Cultural Y Modelación De Relaciones Simbólicas
Vasquez Cordoba, Shiddarta
This thesis focuses on an analysis of the religious world of colonial Potosí through the study of the rituals and miracles described in the History of the Imperial City of Potosi written by Bartolome Arzans de Orsua y Vela in the first half of the eighteenth century. After a detailed reading of the text, this works proposes a schema to understand the basic but repetitive ritualistic cycles that organize the life in the city and uses tools such as Topic Maps and the modelling system called NetLogo to visualize the social and cultural networks that give life to the narration. The objective is to represent part of the cultural system of Potosí through these cycles of rituals and miracles, unearth the supporting social networks and question the assumed idea about this chronicle as being a clear representative of the new "criollo" subject. As shown in the conclusions, the history of Potosí is to a great extent the history of a varied set of social and ethnic groups, who are part of a permanent process of pro-sociality in which rituals and virgins play the role of linking the different groups.
2010-10-19T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/23
https://ir.lib.uwo.ca/context/etd/article/1094/viewcontent/auto_convert.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Potosi chronicles
cultural complexity
rituals
miracles
network modelling
Latin American Literature
oai:ir.lib.uwo.ca:etd-1095
2010-12-13T21:35:58Z
publication:civil
publication:faculties
publication:etd
publication:civil-etd
Spatial and Temporal Risk Assessment for Water Resources Decision Making
Ahmad, Shohan S
Water resources systems are vulnerable to natural disasters such as floods, wind storms, earthquakes, and various meteorological events. Flooding is the most frequent natural hazard that can cause damage to human life and property. A new methodology presented in this thesis is capable of flood risk management by: (a) addressing various uncertainties caused by variability and ambiguity; (b) integrating objective and subjective flood risk; and (c) assisting the flood risk management based on better understanding of spatial and temporal variability of risk. The new methodology is based on the use of fuzzy reliability theory. A new definition of risk is used and described using three performance indices (i) a combined fuzzy reliability-vulnerability, (ii) fuzzy robustness and (iii) fuzzy resiliency. The traditional flood risk management relies on either temporal or spatial variability, but not both. However, there is a need to understand the dynamic characteristics of flood risk and its spatial variability. The two-dimensional (2-D) fuzzy set that relates the universe of discourse and its membership degree, is not sufficient to address both, spatial and temporal, variations of flood risk. The theoretical contribution of this study is based on the development of a three dimensional (3-D) fuzzy set.
The spatial and temporal variability of fuzzy performance indices – (i) combined reliability-vulnerability, (ii) robustness, and (iii) resiliency – have been implemented to (i) river flood risk analysis and (ii) urban flood risk analysis. The river flood risk analysis is illustrated using the Red River flood of 1997 (Manitoba, Canada) as a case study. The urban flood risk analysis is illustrated using the residential community of Cedar Hollow (London, Ontario, Canada) as a case study. The final results of the fuzzy flood reliability analysis are presented using maps that show the spatial and temporal variation of reliability-vulnerability, robustness and resiliency indices. Maps of fuzzy reliability indices provide additional decision support for (a) land use planning, (b) selection of appropriate flood mitigation strategies, (c) planning emergency management measures, (d) selecting an appropriate construction technology for flood prone areas, and (e) flood insurance.
2010-09-15T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/20
https://ir.lib.uwo.ca/context/etd/article/1095/viewcontent/Ahmad_Shohan_S_201009_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Water resources
flood risk analysis
flood management
uncertainty analysis
fuzzy sets
spatial and temporal fuzzy performance indices
floodplain mapping
storm sewer modeling
disaster mitigation
Geographic Information System (GIS)
oai:ir.lib.uwo.ca:etd-1096
2010-12-22T14:04:05Z
publication:sociology-etd
publication:sociology
publication:faculties
publication:etd
Social Determinants of Mental Health and Well-Being among Aboriginal Peoples in Canada
Wingert, Susan
The articles in this volume address the question: How do social determinants structure the health and well-being of the Aboriginal population in Canada? The first article uses bivariate statistical tests to assess whether First Nations residents’ subjective assessments of personal and community well-being correspond to scores from the Community Well-Being (CWB) Index, which is a measure of socioeconomic conditions in the community. The second article uses path analysis to test the extent to which the stress process model explains the social distribution of psychological distress and well-being in the off-reserve Aboriginal population. Specifically, it investigates whether stress, mastery, and social support mediate the pathways between social status and mental health outcomes. The results of these two chapters suggest that education is an important determinant of well-being. The final two chapters explore potential barriers to higher educational attainment. The third article uses multinomial logistic regression to assess whether intergenerational exposure to residential schools patterns educational attainment across three cohorts of First Nations adults. The fourth chapter uses churn theory to examine whether mobility patterns affect educational attainment among Aboriginal adolescents and young adults living off-reserve.
Collectively, the articles presented here support the contention that the health and well-being of the Aboriginal population is tied to, although not solely determined by, their social and economic positions. CWB scores were significantly associated with residents’ perceptions of their own and community’s well-being. Stress, mastery, and social support are mediators between social status and mental health; however, it appears that specific social statuses are more strongly associated with specific mediators. In terms of educational attainment, there was no clear patterning based on intergenerational proximity or density of residenial school exposure. The results suggest that exposure alone is a poor predictor. Patterns of migration were associated with educational attainment in both cohorts. Generally, it appears that frequent moves are associated with higher odds of dropping out or falling behind in high school. However, having never moved is associated with lower odds of attending post-secondary.
2010-12-06T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/61
https://ir.lib.uwo.ca/context/etd/article/1096/viewcontent/auto_convert.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Aboriginal
First Nations
mental health
distress
well-being
residential school
educational attainment
migration
stress process model
churn theory
Sociology
oai:ir.lib.uwo.ca:etd-1097
2010-12-21T19:50:57Z
publication:chemeng-etd
publication:chemeng
publication:faculties
publication:etd
A Step towards Continuous Production of NaY Zeolite in Amorphous Silica Particles using a Dry Process
Zaidi, Syed Sameen Ali
This thesis is focused on the synthesis of nano-size (50-100nm) NaY zeolite crystals inside the micro/meso pores of preshaped amorphous silica particles of size 50 micrometer using a dry process, which reduced several operational steps and the zeolite synthesis time that are generally required for current in-practice processes. Three types of reactors namely; polypropylene bottles, a stainless steel tubular reactor, and a novel vibrated baffles fluidized bed (VBFB) reactor coupled with infrared radiation emitters were used to evaluate the effects of different operating parameters on the synthesis of NaY zeolite. The synthesis process took place without using any structure directing agent and, due to using a dry synthesis technique, no significant chemical waste was generated. A parametric study revealed that an silica/alumina ratios above 6.6 did not produce any appreciable zeolite within the time frame of 24 h at 100C. The optimal silica/alumina ratio was found to be 6.1 for 16 h of synthesis at 100C in polypropylene bottles. The use of a stainless steel tubular reactor reduced the synthesis time to 8 h owing to its higher thermal conductivity as compared to polypropylene. Synthesis in the stainless steel tubular reactor reduced the synthesis time to 15 min while operating at 170C without any zeolite phase transformation. An operating temperature beyond 170C was not recommended due to NaY zeolite phase transformation to analcime. The effects of different concentrations of NaOH revealed that concentrations below 20wt% retarded the synthesis process whereas higher concentrations up to 32wt%, not only accelerated the synthesis but also resulted in the production of smaller crystals, less than 50nm in size. An NaOH concentration beyond 32wt% was not recommended due to dissolution and loss of structure of silica particles. The novel VBFB reactor produced single crystals in the size range of 300-600nm at 100C in 5 min. Using IR radiation for fast heat transfer accelerated the surface integration mechanism and led to the growth of crystals in 5 min. The synthesized NaY zeolite was tested for FCC reaction in a riser simulator after an ion-exchange with ammonium nitrate. A high conversion of 1,3,5-tri-isopropylbenzene in the range of 55-65% was obtained with a loss in conversion by 10% after regeneration. The as-synthesized NaY zeolite within silica particles was also tested for desulfurization of model hydrocarbons containing thiophene. The desulfurization through adsorption was achieved by removing thiophene from 500 ppmw to less than 15 ppmw in hexanes and a mixture of p-xylene in hexanes. The removal of 500 ppmw thiophene could not be achieved below 300 ppmw while using the mixture of toluene in hexanes. The as-synthesized NaY zeolite performed better for thiophene removal as compared to other adsorbents like silica, commercial NaX and NaY pellets, and commercial NaY fine powder.
2010-12-14T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/58
https://ir.lib.uwo.ca/context/etd/article/1097/viewcontent/Thesis_Final_submission_Dec20_2010.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
NaY zeolite
nano-size
synthesis
dry process
stainless steel tubular reactor
polypropylene
vibrated baffles fluidized bed reactor
IR radiation
operating parameters
FCC reaction
Riser Simulator
desulfurization
thiophene
hexanes
p-xylene
toluene
Chemical Engineering
oai:ir.lib.uwo.ca:etd-1098
2012-12-10T21:46:39Z
publication:etdlac
publication:edu
publication:faculties
publication:edu-etd
publication:etd
This Tract of Land: North Buxton, Ontario, 1873-1914
Bonner, Claudine Y.
Acknowledging the continued concerns and calls for the education system to improve how it addresses the changing face of Canada in terms of race, gender, class, language and culture, this thesis focuses on the history and narratives of a single African-Canadian community as a starting point for educators who wish to learn about and make use of marginalized histories in their classroom practice. The information would also prove helpful to those educators who often have difficulty in finding material relating to African-Canadian history and as a result fail to add the stories of black Canadians to the national narrative shared in their classrooms. There is a wealth of knowledge that can be drawn from the material in each section of the thesis, beginning with an exploration of the theoretical frame, which introduces readers to the concepts underlying African-Canadian studies, and provides them with a means of better comprehending the lived experiences of people of African descent in the New World Diaspora. The study also provides a concise history of the first and second generations of the Buxton community, providing access to the evolution of the community from that of a planned refugee settlement, to becoming an active Canadian community. Additionally, the study explores the American South that awaited those who chose to return “home” after the American Civil War. The narratives and the process of restorying provide teachers with concrete examples of how to access and work with historical documents, or take single lives and events and discover connections, as they make sense of the experiences.
2010-12-03T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/49
https://ir.lib.uwo.ca/context/etd/article/1098/viewcontent/This_Tract_of_Land___Final_Revisions.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
multicultural education
African-Canadian
African Diaspora
community studies
black community
critical race theory
Education
oai:ir.lib.uwo.ca:etd-1099
2011-11-15T19:34:41Z
publication:philosophy-etd
publication:philosophy
publication:faculties
publication:etd
The Problem of Katholou (Universals) in Aristotle
Sirkel, Riin
My dissertation focuses on what I call Aristotle’s “problem of katholou ” in order to distinguish it from the “problem of universals” which is traditionally framed as the problem about the ontological status of universals. Aristotle coins the term katholou (traditionally translated as “universal”) and defines it as “that which is by nature predicated of many things". Yet, the traditional focus on the ontological status of universals is not Aristotle’s. His positive remarks about universals remain neutral with regard to their ontological status and escape the standard divide of realism and nominalism. I start with Aristotle’s neutrality and focus on the problem he is concerned with, namely, the problem of katholou.
This problem is to explain how what is most real can also be most knowable. It is generated by two of Aristotle’s philosophical commitments: (i) particulars are most real and (ii) universals are most knowable (since knowledge is of the universal). These commitments are supposed to lead to what is traditionally called a discrepancy between the real and the knowable, and many authors think that it constitutes the most serious, perhaps insoluble, problem in Aristotle's philosophy. I believe it is soluble, but I do not assume that there must be only one solution. My main task is to show that Aristotle’s writings reveal three related solutions to the problem: one that appeals to the ontological interdependence between universals and particulars; one that appeals to the corresponding epistemological interdependence (and to notions of potentiality and actuality); and one that invokes the concept of form. In the last chapter of the dissertation, I show that Aristotle’s commentator, Alexander of Aphrodisias, adopted primarily the last solution, which appeals to forms. I suggest that Alexander deeply influenced the future direction of the discussions of both Aristotle’s problem of katholou" and the traditional problem of universals.
2010-12-09T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/62
https://ir.lib.uwo.ca/context/etd/article/1099/viewcontent/Sirkel_Riin_201012_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Aristotle
universals
particulars
essentialism
Alexander of Aphrodisias
the problem of universals
Arts and Humanities
oai:ir.lib.uwo.ca:etd-1100
2011-10-21T18:58:19Z
publication:etdlac
publication:biochem-etd
publication:biochem
publication:faculties
publication:etd
Structural insights into DNA replication and lesion bypass by Y family DNA polymerases
Kirouac, Kevin N
Y family DNA polymerases are specialized enzymes for replication through sites of DNA damage in the genome. Although the DNA damage bypass activity of these enzymes is important for genome maintenance and integrity, it is also responsible for DNA mutagenesis due to the error-prone nature of the Y family. Understanding how these enzymes select incoming nucleotides during DNA replication will give insight into their role in cancer formation, aging, and evolution. This work attempts to mechanistically explain, primarily through X-ray crystallography and enzymatic activity assays, how Y family polymerases select incoming nucleotides in various DNA replication contexts. Initially, we sought to determine how the model Y family polymerase Dpo4 differentiates between ribo and deoxyribonucleotides. Crystal structures were solved of a mutant Dpo4 enzyme (Y12A) deficient in ribonucleotide discrimination, incorporating either deoxy-adenine (dA) or ribo-adenine (rA) nucleotides opposite template thymine DNA. It was revealed that the Dpo4 Y12A mutant allowed rA incorporation by accommodating the 2’-OH group of the ribose sugar. Thus Y family polymerases block ribonucleotide incorporation during DNA replication by clashing with the 2’-OH group of ribose sugars. Next, we examined how human DNA polymerase iota (polɩ) prefers to incorporate mis-matched nucleotides opposite an undamaged thymine base. Crystal structures of polɩ in complex with template thymine DNA incorporating either correct adenine (A) or mis-matched thymine (T) or guanine (G) revealed the structural basis of error-prone replication. Correct A was destabilized by a narrow polɩ active site and mis-matched G was preferred by hydrogen bonding with glutamine59 from the finger domain. Domain swapping experiments confirmed the role of the polɩ finger domain in nucleotide selection opposite T. We then investigated how polɩ selects the correct cytosine (C) nucleotide opposite the mutagenic oxidative lesion 8-oxo-guanine. Crystal structures of polɩ in complex with 8-oxo-guanine DNA incorporating correct C or mis-matched A, T, or G revealed the structural basis of error-free replication. The narrow polɩ active site destabilizes A and G purine bases while selecting correct C due to the greatest hydrogen bonding potential with the 8-oxo-guanine Hoogsteen edge. We also show how Glu59 from the finger domain is involved in nucleotide selection and bypass activity through site-directed mutagenesis. Lastly, we examined how polɩ replicates opposite a bulky lesion produced form environmental pollution: N-[deoxyguanosin-8-yl]-1-amino-pyrene (APG). Crystal structures of polɩ in complex with APG DNA incorporating correct C or mis-matched A reveal the structural mechanism of APG replication. Correct C is preferred opposite the lesion due to Watson-Crick base pairing while mis-matched A is incorporated by base stacking above the lesion. We also demonstrate using the model Y family polymerase Dpo4, that the hydrophobic lesion interacts with protein side chains from the little finger domain, which inhibits DNA replication past the lesion site. Taken together, these results further our understanding of how Y family polymerases select incoming nucleotides and how this selection can result in error-free or error-prone replication depending on the chemical nature of the template base.
2010-12-09T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/59
https://ir.lib.uwo.ca/context/etd/article/1100/viewcontent/Kirouac_Kevin_N_201012_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Y family DNA polymerase
DNA polymerase iota
mutagenesis
cancer
oxidative DNA damage
polcyclic aromatic hydrocarbons
Biochemistry, Biophysics, and Structural Biology
Pharmacology, Toxicology and Environmental Health
oai:ir.lib.uwo.ca:etd-1104
2010-12-17T19:33:34Z
publication:etdlac
publication:chemeng-etd
publication:chemeng
publication:faculties
publication:etd
Nickel-based Catalysts for Gasification of Glucose in Supercritical Water
Chowdhury, Muhammad Badrul Islam
Gasification of waste biomass to form hydrogen, H2, is a promising new source of green energy; while providing the additional benefit of treating challenging and hazardous waste streams that pollute the environment. Gasification of biomass in supercritical water (SCW) offers an attractive alternative to avoid the energy intensive drying process. In this approach, biomass is hydrolyzed by water into smaller molecules in the presence of a suitable catalyst. This study was aimed at developing an alumina supported nickel based non-noble metal catalyst suitable for biomass gasification in SCW. A lack of detailed characterization on fresh and spent catalysts in SCW has held back progress in this field and is critical due to the highly unusual properties of SCW at high pressure and temperature compared to ambient water. Typically hydrogen rich gaseous product from gasification of biomass in SCW requires temperatures higher than 700 °C, while low temperature processes (300-500 °C) produce methane rich gases. Use of suitable catalysts can lower the activation energy of the reaction, and hydrogen rich gaseous products can be achieved at low temperatures thus lower the operating cost. Use of suitable catalysts also can reduce the formation of chars and tars formed during the gasification process in SCW. Moreover, non-noble catalysts could be beneficial in terms of availability and cost. A kinetic study of SCW gasification is still under development due to the numerous intermediate and final products and complex reaction pathways.
In this research, supercritical water gasification (SCWG) and partial oxidation (SCWPO) of a model biomass compound was studied to produce hydrogen rich syngas at lower temperatures (400-500 °C). In this respect non-noble nickel catalysts were synthesized, evaluated and characterized (fresh and spent) to study the catalyst role in SCWG. The catalysts studied were synthesized via incipient wetness impregnation of metal salts on synthesized θ-alumina nanofibers and commercial gamma alumina (converted to theta) pellets (3mm average diameter) as catalyst supports. To synthesize nano structured catalyst supports (alumina nanofibers); a one-pot sol-gel route in scCO2 was adopted without using any hazardous organic solvents, surfactants or other additives for the first time. Aerogel nano catalysts were also directly synthesized via a sol-gel technique using isopropanol as solvent and supercritical carbon dioxide (scCO2) as the drying agent.
In this research, it was found that introduction of oxidant after gasification is beneficial in terms of gaseous products and reducing the chemical oxygen demand (COD) in the liquid effluents. Another finding is that nickel (Ni) loading on alumina above 11 wt% consumed carbon dioxide with a simultaneous increase in methane attributed to hydrogen consumption by the methanation reaction. However, lanthanum (La) modified Ni/θ-Al2O3 enhanced production of hydrogen by retarding the methanation reaction and promoting the water gas shift (WGS) reaction. In addition, adsorption of CO2, one of the main products, by La was attributed to shifting the reaction equilibrium to the products and thus contributed to enhance hydrogen production.
Nano catalysts showed higher activity towards hydrogen production, carbon gasification efficiency and total organic carbon (TOC) destruction in the liquid effluent compared to coarser heterogeneous catalysts. However, hydrogen production using aerogel catalysts where metals were loaded directly through sol-gel reaction was found comparatively less than nanofiber catalysts where metals were impregnated on the nano support. This phenomenon was attributed to the formation of Ni-La-Al-O nano structure complex by direct addition of metals during sol-gel reaction. Unlike impregnated catalysts, incorporation of La to the main structure of the sol-gel derived catalysts could not contribute to enhance the WGS reaction.
The fresh and spent catalysts were characterized using different physicochemical techniques which revealed that the catalysts were active in SCW even though the metallic sites of nickel agglomerated when exposed to SCW conditions, oxidized and reacted with the support alumina. It was found that lanthanum retards the formation of graphitic coke, and adsorbed carbon dioxide during supercritical water gasification.
To our knowledge, hydrogen yield, total organic carbon destruction and gasification efficiency were significantly higher using La modified Ni/θ-Al2O3 nano catalyst fibers than that of any other reported results of SCWG of any biomass compound at moderate temperatures (~500 °C) and pressures (~28 MPa). However, exposing the nanofiber catalysts to the SCW environment led to disintegration of the fibrous structure.
A global kinetic model for TOC destruction in supercritical water was developed using non-linear regression, which convincingly fit with the experimental results.
2010-12-10T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/48
https://ir.lib.uwo.ca/context/etd/article/1104/viewcontent/Chowdhury_Muhammad_B.I._201012_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Catalysis
Hydrogen Production
Supercritical Fluid
Nanomaterials
Characterization
Kinetics
Catalysis and Reaction Engineering
oai:ir.lib.uwo.ca:etd-1102
2017-09-11T16:02:10Z
publication:electrical
publication:electrical-etd
publication:faculties
publication:etd
A Usability Maturity Model for Open Source Software
Raza, Arif
User satisfaction has always been a major factor in the success of software, regardless of whether the software is closed proprietary or open source software (OSS). Although user-centered designs are gaining recognition among the OSS community, many design scenarios still do not incorporate usability as one of their primary goals. Accordingly, many individuals believe that if OSS was more usable, its popularity would increase tremendously. Although there are strong examples of usable open source software, there is still potential to improve the usability of OSS. The usability assessment of open source projects is an area where relatively little research has been conducted, and, accordingly, the main contribution of this work is a methodology that evaluates the usability maturity of an OSS project. Consequently, we present a usability maturity model that is aimed at usability-related issues for open source projects. The model has been developed in response to a need for measuring the extent to which open source software projects support usability. Specifically, it is intended for assessing and improving the usability aspect in open source software development. The proposed model examines the relationship between open source projects and their usability aspects. The measuring instrument for the model contains factors that have been selected from four of our empirical studies, which examine the perspectives of OSS users, developers, contributors and the industry. In addition to presenting the usability maturity model, this thesis discusses assessment questionnaires, a rating methodology and two case studies.
2011-01-13T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/79
https://ir.lib.uwo.ca/context/etd/article/1102/viewcontent/auto_convert.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Open Source Software
Usability
Users
Developers
Contributors
Industry
Maturity Model
Empirical Analysis.
Other Electrical and Computer Engineering
oai:ir.lib.uwo.ca:etd-1105
2011-11-15T19:36:41Z
publication:etdlac
publication:faculties
publication:chem
publication:chem-etd
publication:etd
New Synthetic Methodologies Directed toward Pharmacologically Active Compounds as well as Silole Based Chromophores for Analytical and Optoelectronic Applications
Moustafa, Mahmoud M. Abd Rabo
The development of new and efficient synthetic methodologies to prepare heterocyclic compounds has received great attention over the years due to their importance in the pharmaceuticals and fine chemicals industries. Described herein are several novel syntheses of a variety of heterocycles including siloles, azaindoles, piperideines, piperidines and tetrahydropyrans.
A one-pot, two-step methodology involving Tamao’s reductive cyclization followed by Negishi cross coupling was utilized to synthesize several new series of silole-based chromophores. The property studies revealed new electropolymerized poly(thienyl-silole)s with enhanced photoefficiency for all-polymer solar cells. In addition, a new procedure is developed for the synthesis of the first dissymmetric silole tethered to amine functionality. The synthesized compounds hold great promise in the arena of biosensors and solar cell applications.
Furthermore, a novel and practical two step sequence for the preparation of C2 substituted 5-azaindoles has been reported. The synthetic sequence features a [3+2] dipolar cycloaddition between nitriles and a 3,4-cyclopropanopiperidine followed by SeO2 oxidation.
Finally, the annulation reaction between 2-alkoxy-1,1-cyclobutane diesters and imines or aldehydes gave access to highly functionalized piperidines and tetrahydropyrans, respectively. Both the synthesis of those donor-acceptor cyclobutanes and their subsequent annulations are catalyzed by catalytic Yb(OTf)3. Although known for more than two decades, this is the first use of 2-alkoxy-1,1-cyclobutane diesters in dipolar cycloadditions.
The new reactions are done under mild conditions providing the target compounds in high yields and excellent selectivity. The divergent nature and cost effectiveness of these methods make them very suitable for combinatorial applications in the pharmaceutical industry.
2011-02-25T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/93
https://ir.lib.uwo.ca/context/etd/article/1105/viewcontent/Moustafa_Mahmoud_M_20114_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Cycloaddition
Cyclopropanes
Cyclobutanes
Azaindoles
Piperidines
Tetrahydropyrans
Siloles
Electrochemiluminescence
Organic Chemistry
oai:ir.lib.uwo.ca:etd-1106
2010-12-21T18:49:35Z
publication:etdlac
publication:biochem-etd
publication:biochem
publication:faculties
publication:etd
The role of the Mcm2 subunit in regulating the activities of the Mcm2-7 helicase
Stead, Brent E
The transmission of genetic information from parental to daughter cells requires the faithful duplication of an organism’s genome. Uncontrolled DNA replication can result in proliferative diseases, such as cancer. DNA replication requires a single-stranded DNA template to be produced from duplex DNA. In eukaryotes, DNA unwinding for replication is performed by the heterohexameric replicative helicase complex comprised of the minichromosome maintenance proteins 2 through 7.
Each of the Mcm2-7 subunits likely has a unique role in DNA binding and unwinding by the Mcm2-7 complex. The present study examines the role of the Saccharomyces cerevisiae Mcm2 subunit in regulating the activities of Mcm complexes. Using in vitro assays for DNA unwinding and DNA binding with E. coli-purified Mcm subunits, this work demonstrates that Mcm2 requires nucleotide to actively regulate DNA binding and unwinding by Mcm complexes. These studies define Mcm2 as an active regulatory subunit within the Mcm2-7 complex.
Mcm2-7 is also targeted by various kinases that presumably modulate its activities. The Dbf4-dependent kinase (DDK) comprised of the Cdc7 catalytic subunit and Dbf4 regulatory subunit is one such kinase. Here, the residues of Mcm2 targeted for phosphorylation by DDK were mapped using recombinant proteins and verified in cells. The effects of phosphomimetic substitutions at these positions on the activities of the Mcm2-7 complex were examined. Interestingly, the ATPase activity of Mcm2 of the phosphomimetic Mcm2 is lower compared to wild type. A version of Mcm2-7 containing the phopshomimetic mutant of Mcm2 had a higher affinity for DNA, which in turn inhibited DNA unwinding by the complex. The biological function of phosphorylation of Mcm2 by DDK in budding yeast was also examined using cells containing a version of mcm2 that cannot be phosphorylated by DDK. This mutation rendered the cells sensitive to agents that cause DNA base damage. Additionally, the mutant allele interacted with genes involved in the DNA damage checkpoint as determined by synthetic genetic array analysis. In sum, a model in which DDK-dependent phosphorylation of Mcm2 regulates its ATPase activity to slow replication forks in the cell’s response to DNA damage is proposed.
2010-12-14T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/55
https://ir.lib.uwo.ca/context/etd/article/1106/viewcontent/Stead_Brent_E_201012_PhD_thesis_revisions.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Mcm2
Mcm2-7
helicase
Cdc7
Dbf4
DDK
Biochemistry
oai:ir.lib.uwo.ca:etd-1107
2011-01-04T21:58:24Z
publication:kin
publication:kin-etd
publication:faculties
publication:etd
Effects of acute synchronous whole-body vibration exercise
Hazell, Tom J
Recently, whole-body vibration (WBV) exercise has been gaining interest in the health/fitness community for its reported beneficial outcomes. However, most of these have not been evaluated scientifically leading to some reservation in promoting this new exercise modality. The purpose of this dissertation was to assess the viability of WBV exercise to enhance several selected indices of health.
Study 1 demonstrated that the addition of WBV to an isometric semi-squat in young healthy men (n = 8, 25±2.6 y, 177±7.0 cm, 84±12.1 kg) resulted in increases in femoral artery blood flow and leg skin temperature vs the same exercise without vibration (NoV). These increases were seen without concomitant elevations in heart rate and mean arterial pressure suggesting WBV exercise may be a viable training modality for many, perhaps even those with compromised cardiovascular function.
Study 2 demonstrated WBV exercise resulted in a greater oxygen consumption both during and following (8 and 24 h) the exercise bout compared to NoV in young healthy men (n = 8, during - 26±2.3 y, 180±8.2 cm, 84±10.1 kg and 5 of the same and 3 others following - 26±3.0 y, 179±8.3 cm, 85±7.3 kg). These increases in oxygen consumed suggest WBV exercise could be a viable training method to induce positive body composition changes with chronic exposure.
Study 3 demonstrated that neither an acute bout of WBV nor NoV exercise caused a significant effect on muscle function, soreness, or inflammation in young healthy men (n = 10, 25±3.5 y, 179±7.2 cm, 81±7.9 kg). These data suggest WBV has no significant deleterious effects on muscle.
Study 4 demonstrated that both the WBV and NoV exercise sessions improved insulin sensitivity in young healthy men (n=8, 27±2.4 y, 179±7.7 cm, 83±10.6 kg). These results suggest WBV may be an effective exercise mode for individuals with impaired glucose tolerance or even diabetes.
Together these studies demonstrate significant potential health benefit of acute synchronous whole-body vibration exercise and illustrate a need for future mechanistic work determining how exposure to these high frequency low amplitude oscillations produce these benefits.
2010-12-10T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/74
https://ir.lib.uwo.ca/context/etd/article/1107/viewcontent/Hazell_Tom_J_201012_PhD_revisions.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
vertical vibration
acute exercise
cardiovascular
metabolism
Kinesiology
oai:ir.lib.uwo.ca:etd-1108
2010-12-20T19:21:35Z
publication:geography-etd
publication:geography
publication:faculties
publication:etd
The Evolution of the Retail Landscape
Novak, Mathew
If the city is a theatre of social interaction (Mumford 1996), then one of the principle stage sets is the retail landscape. Retail districts are generally where people congregate, making places of shopping among the liveliest areas the city. In addition to being social settings, retail areas are also where a large component of the city’s economy is transacted, and they are implicated in the political dramas of the city, particularly those dealing with issues of growth and development. Retail shops are highly visible elements of the urban landscape, lining principle arteries and clustering at major transit nodes. Retailing is woven throughout the economic, social, political, and built fabrics of the city. The evolution of the retail landscape was studied throughout the development of London, Ontario, a typical mid-sized North American city. The functional and spatial composition of the retail sector was documented from the first settlement, thru the era of rapid industrialization, to today’s consumption-based city. Over time, the retail landscape exhibited much dynamism, reflecting changing socio-economic conditions, as well as technological innovation. Both the retailers themselves, and the environments in which their businesses were conducted, have evolved. From the primitive general store, thru the grand emporia lining ‘mainstreet’, to the contemporary planned shopping centres. Comparisons were made between the physical characteristics of the built environments constructed in various eras which make up the retail landscape. Drawing from the urban morphology literature (notably Conzen 1960), analysis was conducted of the town-plan, building forms, and land-uses of the various retail environments. In addition to documenting the general changes in these town-scape elements over time, further analysis was conducted on the form and function of the archetypical retail environments, the traditional ‘mainstreet’ district and contemporary shopping centres. Although they differ in many ways, a common logic was found in all retail landscapes, united through the drive for profit maximization by the retailers who shape their environments in striving towards this goal. Theoretical advancements to the field of urban morphology are presented, arguing that it is necessary to consider all elements of the town-scape in unison when describing the character of urban environments. A trialectic is proposed, taking into account how each of these elements simultaneously shapes and is shaped by the other two.
2010-12-06T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/53
https://ir.lib.uwo.ca/context/etd/article/1108/viewcontent/Novak_Mathew_J_201012_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Urban Geography
Urban History
GIS
Human Geography
oai:ir.lib.uwo.ca:etd-1109
2012-10-02T17:44:40Z
publication:anthro
publication:etdlac
publication:anthro-etd
publication:faculties
publication:etd
Cross-sectional Morphology and Mechanical Loading in Plio-Pleistocene Hominins: Implications for Locomotion and Taxonomy
Bleuze, Michele M, Ms.
This study explores locomotion and locomotor variability in Plio-Pleistocene hominins by examining cross-sectional properties and mechanical loading patterns in the proximal and midshaft femur of Paranthropus, fossil Homo sp. and H. erectus. Modern human and Pan models are used for comparative purposes. Cross-sectional properties in the proximal and midshaft femur of fossil hominins are examined to test the hypothesis that members of the same genus should exhibit similar locomotor behavior. In the proximal femur, fossil Homo sp. cluster with modern humans to the exclusion of Paranthropus, and East and South African Paranthropus cluster together. Group differences are primarily due to differences in average bending and torsional strength. KNM-ER 738, which has been allocated to both Paranthropus and Homo, is more similar to paranthropine samples than to modern and fossil Homo. In the midshaft femur, fossil Homo sp. and H. erectus cluster with modern humans. OH 62 (H. habilis), however, forms a cluster by itself. It is unclear if this indicates a non-Homo status or if locomotor behavior was highly variable in early Homo. KNM-ER 1592, which is generally attributed to Paranthropus, clusters with modern and fossil Homo. This either suggests that mechanical loading is comparable between Paranthropus and Homo or that KNM-ER 1592 is misclassified as Paranthropus. KNM-ER 736 and KNM-ER 1807, which have been allocated to both Paranthropus and Homo, cluster with modern and fossil Homo, and therefore cannot be excluded from this genus. Group differences in the midshaft femur are largely due to differences in average bending and torsional strength. Relationships between cross-sectional properties in the proximal and midshaft femur are examined to investigate if mechanical loading patterns in fossil hominin femora suggest human-like locomotion, Pan-like locomotion or intermediate locomotor behavior. The relative amount of cortical bone is elevated in modern humans compared to Pan, and in fossil hominins compared to modern humans. Axial strength is greater relative to average bending and torsional strength in modern humans compared to Pan. Fossil Homo sp. and H. erectus are most similar to modern humans in this regard. OH 62, however, displays the Pan-like pattern. Mechanical loading patterns in Paranthropus are more similar to patterns in modern humans than to patterns in Pan. The relationship between bending strength in the medio-lateral plane relative to bending strength in the antero-posterior plane of the proximal and midshaft femur is not significantly different between modern humans and Pan. Thus, different mechanical demands could potentially yield similarities in diaphyseal shape.
2010-12-13T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/64
https://ir.lib.uwo.ca/context/etd/article/1109/viewcontent/Bleuze_Michele_M_201012_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
cross-sectional morphology
biomechanics
locomotion
Paranthropus
early Homo
femur
Biological and Physical Anthropology
oai:ir.lib.uwo.ca:etd-1110
2011-02-01T14:31:30Z
publication:earth
publication:geology-etd
publication:faculties
publication:etd
The Impact of Climate and Transport on the Compositions and Textures of Heavy Minerals in Modern Rivers of New Zealand
Aubin, Alexandre
The types, abundances and textures of heavy minerals in the 63-125 μm fraction of modern river sands were investigated in order to assess the controls of climate, tectonic setting, source composition, recycling, transport and diagenesis on the nature of sedimentary systems. Two rivers on the South Island of New Zealand were selected for detailed study; the Haast is a high-flow river located in the high precipitation region near the west coast, whereas the Ahuriri River has lower flow rates and is located in a drier region in the central South Island. In both river systems, the Zircon-Tourmaline-Rutile (ZTR) index increases downstream, illustrating that chemical and mechanical weathering gradually degraded the more unstable mineral species relative to ultrastable zircon. Point counting of the light mineral fractions indicates a downstream increase in quartz compared with feldspar, further suggesting chemical and mechanical weathering processes. Although the Chemical Index of Alteration (CIA) values are not high (average 55 for each river system), the heavy and light mineral data, combined with major element results illustrating an increase in SiO2 with decreasing Al2O3, MgO and Fe2O3 downstream, all indicate a weathering signal. Highly fluctuating patterns in mineralogical and geochemical data suggest bar-to-bar variations consistent with mixing from tributary input.
Four heavy mineral types were chosen for textural investigations and include garnet, zircon, titanite and tourmaline. Roundness and etching values for each mineral produced no downstream trends. This discrepancy is attributed to the recycled nature of the source rocks, which are schistose and wacke deposits, as well as input of new source material downstream via tributaries, alluvial fans and erosion of Quaternary and Tertiary deposits. Detailed investigations of sediment sampled from a longitudinal bar in the Haast River show that surface samples have lower roundness and etching values than sediment 10 cm below the surface. This result suggests that mineral alteration takes place within the water-laden bar through diagenetic processes rather than from subaerial chemical weathering.
2011-01-24T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/81
https://ir.lib.uwo.ca/context/etd/article/1110/viewcontent/Aubin_Alexandre_201106_PhD_thesis.pdf
https://ir.lib.uwo.ca/context/etd/article/1110/filename/0/type/additional/viewcontent/Aubin_Alexandre_201106_PhD_appendix2.zip
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Haast
Ahuriri-Waitaki
weathering
etching
roundness
surface textures
Geology
oai:ir.lib.uwo.ca:etd-1111
2010-12-17T21:27:02Z
publication:neuroscience-etd
publication:neuroscience
publication:faculties
publication:etd
Perception meets action: fMRI and behavioural investigations of human tool use
Valyear, Kenneth F
Tool use is essential and culturally universal to human life, common to hunter-gatherer and modern advanced societies alike. Although the neuroscience of simpler visuomotor behaviors like reaching and grasping have been studied extensively, relatively little is known about the brain mechanisms underlying learned tool use.
With learned tool use, stored knowledge of object function and use supervene requirements for action programming based on physical object properties. Contemporary models of tool use based primarily on evidence from the study of brain damaged individuals implicate a set of specialized brain areas underlying the planning and control of learned actions with objects, distinct from areas devoted to more basic aspects of visuomotor control. The findings from the current thesis build on these existing theoretical models and provide new insights into the neural and behavioural mechanisms of learned tool use.
In Project 1, I used fMRI to visualize brain activity in response to viewing tool use grasping. Grasping actions typical of how tools are normally grasped during use were found to preferentially activate occipitotemporal areas, including areas specialized for visual object recognition. The findings revealed sensitivity within this network to learned contextual associations tied to stored knowledge of tool-specific actions. The effects were seen to arise implicitly, in the absence of concurrent effects in visuomotor areas of parietofrontal cortex. These findings were taken to reflect the tuning of higher-order visual areas of occipitotemporal cortex to learned statistical regularities of the visual world, including the way in which tools are typically seen to be grasped and used. These areas are likely to represent an important source of inputs to visuomotor areas as to learned conceptual knowledge of tool use.
In Project 2, behavioural priming and the kinematics of real tool use grasping was explored. Behavioural priming provides an index into the planning stages of actions. Participants grasped tools to either move them, grasp-to-move (GTM), or to demonstrate their common use, grasp-to-use (GTU), and grasping actions were preceded by a visual preview (prime) of either the same (congruent) or different (incongruent) tool as that which was then acted with. Behavioural priming was revealed as a reaction time advantage for congruent trial types, thought to reflect the triggering of learned use-based motor plans by the viewing of tools at prime events. The findings from two separate experiments revealed differential sensitivity to priming according to task and task setting. When GTU and GTM tasks were presented separately, priming was specific to the GTU task. In contrast, when GTU and GTM tasks were presented in the same block of trials, in a mixed task setting, priming was evident for both tasks. Together the findings indicate the importance of both task and task setting in shaping effects of action priming, likely driven by differences in the allocation of attentional resources. Differences in attention to particular object features, in this case tool identity, modulate affordances driven by those features which in turn determines priming. Beyond the physical properties of objects, knowledge and intention of use provide a mechanism for which affordances and the priming of actions may operate.
Project 3 comprised a neuroimaging variant of the behavioural priming paradigm used in Project 2, with tools and tool use actions specially tailored for the fMRI environment. Preceding tool use with a visual preview of the tool to be used gave rise to reliable neural priming, measured as reduced BOLD activity. Neural priming of tool use was taken to reflect increased metabolic efficiency in the retrieval and implementation of stored tool use plans. To demonstrate specificity of priming for familiar tool use, a control task was used whereby actions with tools were determined not by tool identity but by arbitrarily learned associations with handle color. The findings revealed specificity for familiar tool-use priming in four distinct parietofrontal areas, including left inferior parietal cortex previously implicated in the storage of learned tool use plans. Specificity of priming for tool-action and not color-action associations provides compelling evidence for tool-use-experience-dependent plasticity within parietofrontal areas.
2010-12-10T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/45
https://ir.lib.uwo.ca/context/etd/article/1111/viewcontent/Valyear_Ken_F_201012_PhD_revisedThesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
tool use
action priming
affordances
grasping
action planning
fMRI
visuomotor control
inferior parietal cortex
ventral and dorsal visual streams
Cognitive Neuroscience
oai:ir.lib.uwo.ca:etd-1113
2010-12-21T05:30:31Z
publication:physiology-etd
publication:etdlac
publication:physpharm
publication:faculties
publication:etd
Cardiac Adaptation To Chronic Blockade Of Voltage-Gated, L-Type Calcium Channels In The Sarcolemma
Zhou, Ji
L-type Ca2+ channels (dihydropyridine receptors, DHPRs) in the sarcolemma are essential to cardiac excitation-contraction (E-C) coupling. Thus, Ca2+ influx through DHPRs upon cardiomyocyte excitation triggers Ca2+ release from the sarcoplasmic reticulum (SR) through ryanodine receptors (RyRs) to initiate myofilament activation and muscle contraction. Muscle relaxation occurs upon sequestration of Ca2+ back into the SR lumen by sarco/endoplasmic reticulum calcium-ATPase (SERCA) in the SR. As a treatment option for hypertension, long-term use of DHPR blockers is associated with increased risk of heart failure; underlying mechanisms are unknown. This research used male Wistar rats treated with verapamil (subcutaneously, 625 µg/h/kg for 4 weeks) to determine the impact of chronic DHPR blockade in vivo, on E-C coupling events and heart function at all levels ranging from molecules to whole organism. The results presented in chapter 2 demonstrate that chronic DHPR blockade caused functional remodeling of RyRs and spatio-temporal dyssynchrony of E-C coupling events, resulting in systolic dysfunction and enhanced susceptibility to arrhythmia. Findings in chapter 3 reveal that chronic DHPR blockade was accompanied by depressed SERCA function, abnormal cardiomyocyte Ca2+ handling, and diastolic dysfunction. Results in chapter 4 reveal adaptational changes in protein phosphorylation-dependent regulation of SR/cardiomyocyte Ca2+ cycling due to chronic DHPR blockade. These include over-expression of Ca2+/calmodulin-dependent protein kinases II (CaMKII), hyper-phosphorylation of SR Ca2+ cycling proteins by CaMKII and cAMP-dependent protein kinase (PKA), paradoxically diminished SR Ca2+ content and contractile reserve, and blunted inotropic response to beta-adrenergic stimulation. The above adaptations to chronic DHPR blockade occurred in the absence of cardiac hypertrophy or fibrosis. Thus, molecular remodeling may invoke cardiac pathology and heart failure without microscopic structural changes in cardiomyocytes. The findings from this thesis reveal, for the first time, integrated mechanisms underlying the increased risk of heart failure associated with chronic DHPR blockade. In addition to urging caution in the conventional clinical use of DHPR blockers, the novel mechanistic events and molecular remodeling revealed here imply that manipulation of the stoichiometry of molecular players in E-C coupling demand critical attention and careful scrutiny in the design and deployment of therapeutic approaches for heart diseases.
2010-12-02T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/54
https://ir.lib.uwo.ca/context/etd/article/1113/viewcontent/Ji_Zhou_201012_PhD_thesis.pdf
https://ir.lib.uwo.ca/context/etd/article/1113/filename/0/type/additional/viewcontent/Ji_Zhou_201011_PhD_Appendix_C.avi
https://ir.lib.uwo.ca/context/etd/article/1113/filename/1/type/additional/viewcontent/Ji_Zhou_201011_PhD_Appendix_D.avi
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
sarcoplasmic reticulum; excitation-contraction coupling; verapamil; calcium channel blockers; Ca2+ sparks; Ca2+-ATPase; ryanodine receptors; dihydropyridine receptor; Ca2+ transient; fura-2; Ca2+/calmodulin-dependent protein kinase II; cAMP-dependent protein kinase; cardiac functional reserve; protein phosphorylation
Cellular and Molecular Physiology
Other Physiology
Physiology
oai:ir.lib.uwo.ca:etd-1112
2011-11-15T19:38:45Z
publication:hrs
publication:hrs-etd
publication:faculties
publication:etd
A Stakeholder Generated Conceptualization for Successful Return to Work Outcome Evaluation: A Concept Mapping Approach
Leyshon, Rhysa
Measurement of return to work (RTW) lacks attention to outcomes of relevance to all stakeholders. The objective of this thesis was to define what constitutes a successful RTW outcome from a stakeholder perspective and determine how to best measure it. A concept mapping method was used to create a conceptualization of successful RTW outcome based on indicators of interest and importance to various stakeholders. RTW researchers were questioned and the literature was searched for measures that mapped to the conceptualization and concepts. Stakeholders, made up of RTW consumers and providers, generated 48 indicators of successful RTW which were subsequently grouped into six concepts. Stakeholders also rated the importance of each of the indicators. In preparation for creating a final conceptualization the stakeholder-generated concepts and rating data were presented to a researcher group who were invited to comment and provide further input. The researcher group confirmed the inclusiveness of the generated concepts and discussed various aspects of the resulting conceptualization. Names of measures that appeared to evaluate various concepts were also offered. The final conceptualization was constructed in an attempt to reflect both practice and research realities. The stakeholder-generated data, discussion points from RTW researcher focus groups and the investigator’s intimate knowledge of both practical RTW issues and RTW literature were used in the creation of a logic model. Final concepts were support and collaboration, stakeholder perspectives, rights, respect and dignity, maintenance of well-being, worker job function and worker job satisfaction. The logic model was developed to illustrate temporal aspects and the relationships among the concepts of this RTW outcome evaluation theory. This project is the first that identifies shared and clear goals of RTW program outcomes. Results suggest that there are measures that fully capture some concepts but aspects of other concepts will likely need development of new measures. Further study is needed to determine the ability of the model to differentiate between successful and unsuccessful RTW outcomes and to develop an outcome measure that targets the concepts of the model explicitly.
2010-12-17T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/67
https://ir.lib.uwo.ca/context/etd/article/1112/viewcontent/Leyshon_Rhysa_201012_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Return to work
outcome measures
program theory
concept mapping
logic model
stakeholder perspectives
Occupational Therapy
Other Rehabilitation and Therapy
Rehabilitation and Therapy
Vocational Rehabilitation Counseling
oai:ir.lib.uwo.ca:etd-1114
2011-11-15T19:39:36Z
publication:etdlac
publication:history-etd
publication:history
publication:faculties
publication:etd
Toronto the Green: Pollution Probe and the Rise of the Canadian Environmental Movement
O'Connor, Ryan Ernest
This dissertation utilizes the first fifteen years of Pollution Probe’s history (1969-1984) as a prism for examining the origins and development of environmental activism in Canada. The organization was pivotal in the evolution of environmentalist discourse and activism in Toronto, both through its own activities and its role in institution-building. Rooted in Toronto, Pollution Probe provides insight into the early history of the Canadian environmental movement, demonstrating the many ways that this movement differed from the one that took shape in the United States. As will be demonstrated, Pollution Probe was representative of the first wave of Canadian environmental non-governmental organizations [ENGOs] that were formed in the late 1960s and early 1970s. Unlike their American contemporaries, which evolved over a period of decades out of existing conservation organizations, Canadian ENGOs such as Pollution Probe appeared on the scene almost instantaneously. Furthermore, the Canadian organizations tended to be highly localized, in contrast to the larger, national ENGOs found in the United States. While the early Canadian ENGOs originally excelled by virtue of their focus on local pollution problems, the shift to more abstract, underlying problems was met with varying success. Ultimately, they were ill-equipped to address the larger, transnational issues that came to dominate the environmental agenda in the 1980s and 1990s.
2010-12-15T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/57
https://ir.lib.uwo.ca/context/etd/article/1114/viewcontent/full_dissertation.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Pollution Probe; Environmental History; Environmental Movement
History
oai:ir.lib.uwo.ca:etd-1115
2011-02-10T19:36:57Z
publication:neuroscience-etd
publication:neuroscience
publication:faculties
publication:etd
Sexual Differentiation in the Auditory System: An Investigation into Prenatal and Adult Sex Steroid Influences on Otoacoustic Emissions
Snihur, Adrian W.K.
Otoacoustic emissions (OAEs) are a naturally occurring by-product of the outer hair cells in the cochlea of the inner ear. A sexual dimorphism in OAE production favouring females has been reported in both human and non-human species. The broad objective of the present set of studies is to explore how the sexual dimorphism originates and the degree to which it reflects the organizational and activational influences of sex steroid hormones.
Most previous studies of sex differences in OAEs have been based on neonatal, infant, or broad adult samples, Study 1 of the present work was done to verify the reported sex difference, both in spontaneously produced OAEs (spontaneous OAEs or SOAEs) and in OAEs produced in response to acoustic stimuli (click-evoked OAEs or CEOAEs), in a sample of non-hearing impaired young adults. Ear differences in OAE production also have been reported, and this study investigated whether hand preference moderates the observed ear asymmetry in OAE production. Although a robust sex difference was documented in the numbers and powers of SOAEs produced, and in CEOAE response amplitude, there was no evidence to support a reduced ear asymmetry in left-handers.
The major theory purporting to explain the sex difference in OAE production proposes that prenatal androgen exposure in the male fetus dampens the cochlear mechanisms responsible for OAE production and is responsible for the observed sex difference in this trait. In order to test the proposed organizational influence on OAE production, the relationship between OAEs and the ratio of the lengths of the 2nd to 4th digits (the 2D:4D ratio), a marker of individual variations in prenatal androgen exposure, was examined in Study 2. A significant correlation between OAE production and 2D:4D digit-ratios was not found. Fundamental differences in the prenatal development of these characteristics, however, may explain the lack of correlation and do not preclude a prenatal hormonal influence on OAE production.
Another source of variation that may contribute to the sex difference in OAE production is circulating levels of adult steroids. Evidence supporting this possibility is limited. Studies 3 and 4 provided a novel test of the hypothesized activational influence of sex steroids in women and men. Oral contraceptive use in women, which reliably decreases circulating sex steroids, was shown to be associated with reduced OAE production compared to normally-cycling women (Study 3). In Study 4, a negative correlation was found between CEOAE response amplitude and circulating testosterone levels in men. Thus, it appears in men that elevations in circulating testosterone diminish OAE production in a manner similar to that hypothesized prenatally, whereas the results in women suggest that estradiol may influence OAE production in adulthood. These are the first systematic studies to support an activational effect of circulating steroids on OAE production in humans.
2011-01-28T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/85
https://ir.lib.uwo.ca/context/etd/article/1115/viewcontent/Snihur_Adrian_WK_201106_PhD_thesis_final.pdf
https://ir.lib.uwo.ca/context/etd/article/1115/filename/0/type/additional/viewcontent/Snihur_Adrian_WK_201106_PhD_thesis_revised.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
otoacoustic emissions
auditory
prenatal
organizational
activational
hormones
sex steroids
testosterone
estrogens
sex difference
Other Psychology
oai:ir.lib.uwo.ca:etd-1116
2011-02-15T20:49:21Z
publication:csd
publication:csd-etd
publication:faculties
publication:etd
Architecture Supporting Computational Trust Formation
Yew, Chern Har
Trust is a concept that has been used in computing to support better decision making. For example, trust can be used in access control. Trust can also be used to support service selection. Although certain elements of trust such as reputation has gained widespread acceptance, a general model of trust has so far not seen widespread usage. This is due to the challenges of implementing a general trust model. In this thesis, a middleware based approach is proposed to address the implementation challenges.
The thesis proposes a general trust model known as computational trust. Computational trust is based on research in social psychology. An individual’s computational trust is formed with the support of the proposed computational trust architecture. The architecture consists of a middleware and middleware clients. The middleware can be viewed as a representation of the individual that shares its knowledge with all the middleware clients. Each application uses its own middleware client to form computational trust for its decision making needs. Computational trust formation can be adapted to changing circumstances. The thesis also proposed algorithms for computational trust formation. Experiments, evaluations and scenarios are also presented to demonstrate the feasibility of the middleware based approach to computational trust formation.
2011-02-02T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/86
https://ir.lib.uwo.ca/context/etd/article/1116/viewcontent/Yew_ChernHar_201011_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
trust
experience
recommendation
reputation
belief
architecture
Systems Architecture
oai:ir.lib.uwo.ca:etd-1117
2011-11-15T19:40:49Z
publication:biophysics
publication:biophysicsetd
publication:faculties
publication:etd
Improvements in Cardiac Spect/CT for the Purpose of Tracking Transplanted Cells
Sabondjian, Eric
Regenerative therapy via stem cell transplantation has received increased attention to help treat the myocardial injury associated with heart disease. Currently, the hybridisation of SPECT with X-ray CT is expanding the utility of SPECT. This thesis compared two SPECT/CT systems for attenuation correction using slow or fast-CT attenuation maps (mu-maps). We then developed a method to localize transplanted cells in relation to compromised blood flow in the myocardium following a myocardial infarction using SPECT/CT. Finally, a method to correct for image truncation was studied for a new SPECT/CT design that incorporated small field-of-view (FOV) detectors. Computer simulations compared gated-SPECT reconstructions using slow-CT and fast-CT mu-maps with gated-CT mu-maps. Using fast-CT mu-maps improved the Root Mean Squared (RMS) error from 4.2% to 4.0%. Three canine experiments were performed comparing SPECT/CT reconstruction using the Infinia/Hawkeye-4 (slow-CT) and Symbia T6 (fast-CT). Canines were euthanized prior to imaging, and then ventilated. The results showed improvements in both RMS errors and correlation coefficients for all canines. A first-pass contrast CT imaging technique can identify regions of myocardial infarction and can be fused with SPECT. Ten canines underwent surgical ligation of the left-anterior-descending artery. Cells were labeled with 111In-tropolone and transplanted into the myocardium. SPECT/CT was performed on day of transplantation, 4, and 10 days post-transplantation. For each imaging session first-pass perfusion CT was performed and successfully delineated the infarct zone. Delayed-enhanced MRI was performed and correlated well with first-pass CT. Contrast-to-noise ratios were calculated for 111In-SPECT and suggested that cells can be followed for 11 effective half-lives. We evaluated a modified SPECT/CT acquisition and reconstruction method for truncated SPECT. Cardiac SPECT/CT scans were acquired in 14 patients. The original projections were truncated to simulate a small FOV acquisition. Data was reconstructed in three ways: non-truncated and standard reconstruction (NTOSEM), which was our gold-standard; truncated and standard reconstruction (TOSEM); and truncated and a modified reconstruction (TMOSEM). Compared with NTOSEM, small FOV imaging incurred an average cardiac count ratio error greater than 100% using TOSEM and 8.9% using TMOSEM. When we plotted NTOSEM against TOSEM and TMOSEM the correlation coefficient was 0.734 and 0.996 respectively.
2010-12-16T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/69
https://ir.lib.uwo.ca/context/etd/article/1117/viewcontent/Sabondjian_Eric_201012_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
SPECT/CT
attenuation maps
stem cell imaging
first-pass perfusion CT
cell localization
projection truncation
Medical Biophysics
oai:ir.lib.uwo.ca:etd-1118
2010-12-22T19:32:23Z
publication:philosophy-etd
publication:philosophy
publication:faculties
publication:etd
The Ethics of Humanitarian Intervention
Porter, Amanda J.
This thesis investigates ethical debates that surround the definition, the conduct, and the occasions for humanitarian military intervention. I argue that properly-called humanitarian interventions must be directed by partly-altruistic intentions, and just war theorists should resist the emerging trend that discards right intention as a central requirement in favour of a more consequentialist analysis. I argue that interventions must be conducted in a manner that is consistent with the humanitarian purpose and would be accepted by the innocent non-combatants who are themselves risked by the rescue effort. This morally requires that interveners weigh harm to non-combatants particularly heavily in their proportionality assessments, even if that harm is merely an unintended side-effect of otherwise permissible acts, or even if that harm is primarily attributable to an aggressor’s anticipated unjust reprisal to intervention. The extraordinary justice of an intervener’s cause cannot license mass killing, and defenders of intervention should resist the urge to privilege abstract principles above policies that might better protect the most basic interests of innocent persons. In the end, I contend that the justified occasions for full-scale intervention will tend to be restricted to cases of mass-atrocities.
2010-12-15T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/70
https://ir.lib.uwo.ca/context/etd/article/1118/viewcontent/auto_convert.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Humanitarian intervention
just war tradition
right intention
pacifism
proportionality.
Ethics and Political Philosophy
oai:ir.lib.uwo.ca:etd-1119
2013-01-09T20:53:00Z
publication:civil
publication:faculties
publication:etd
publication:civil-etd
Wake Dynamics and Passive Flow Control of a Blunt Trailing Edge Profiled Body
Doddipatla, Lakshmana Sampat
Wake flows behind two-dimensional bodies are dominated mainly by two types of coherent structures, namely, the Karman Benard vortices and the streamwise vortices, also referred to as rolls and ribs respectively. The three-dimensional wake instabilities lead to distinct instability modes (mode-A, mode-B and mode-C or mode S) depending on the flow Reynolds number and geometric shape. The present investigation explores the mechanism by which the flow transitions take place to three-dimensionality in the near wake of a profiled leading edge and blunt trailing edge body. Experiments consisting of a combination of Planar Laser Induced Fluorescence visualizations and Particle Image Velocimetry measurements are conducted for Reynolds numbers ranging from 250 to 46000. The results indicate that three instability modes, denoted by mode-A, mode-B and mode-C, appear in the wake transition to three-dimensionality, but their order of appearance does not occur through the traditional route as observed in circular cylinder flows. It is found that mode-C instability with a spanwise spacing varying between 1.2 to 2.8D (D being the trailing edge thickness) dominates the near wake development. This result is explored further with the aim to devise a simple passive control method to mitigate vortex shedding for blunt trailing edge bodies. The effect of a trailing edge spanwise sinusoidal perturbation (SSP) is investigated for a range of Reynolds numbers (ReD) spanning the transition range from ReD = 550 up to 46000. PIV measurements at different vertical and horizontal locations are performed to study changes in the streamwise and spanwise vortices. The base drag and strength of vortex shedding decrease with wavy trailing edge compared to the straight trailing edge. Proper Orthogonal Decomposition (POD) of the obtained PIV data indicates that the spanwise sinusoidal perturbation redistributes the relative energy, enhancing the streamwise vortices and, as a result, suppressing the Karman Benard rolls.
2010-12-15T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/71
https://ir.lib.uwo.ca/context/etd/article/1119/viewcontent/Doddipatla_Lakshmana_S_201011_PhD_Thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Blunt Trailing-Edge-Profiled Body
Wake Instabilities
Passive Flow Control
Particle Image Velocimetry (PIV)
Planar Laser Induced Fluorescence (PLIF)
Proper Orthogonal Decomposition (POD)
Civil and Environmental Engineering
oai:ir.lib.uwo.ca:etd-1121
2011-01-19T20:55:22Z
publication:physics
publication:physics-etd
publication:faculties
publication:etd
Magnetic Excitations in Cylindrical Multilayered Nanostructures
Das, Tushar K
The fabrication of magnetic nanowires and nanotubes, along with experimental studies, have motivated a theory of spin waves (SW) in ferromagnetic and antiferromagnetic cylindrical systems. The calculations are applied to situations where the external magnetic field is parallel to the cylindrical axis and the structures have a large length-to-diameter aspect ratio. A macroscopic theory is developed for the bulk and surface SW for various regimes of wavevectors.
First, a theory is given for magnetostatic modes, where the dipole-dipole interactions dominate in the SW dynamics. The magnetostatic form of Maxwell's equations and electromagnetic boundary conditions are used to derive the SW dispersion relations in nanotubes. A transfer matrix formalism is subsequently used to generalize these calculations to cylindrical multilayers. Next, the theory in magnetic cylindrical tubes is extended to the magnetic polaritons that arise at smaller wavevectors from the coupling between electromagnetic waves and the dipolar SW excitations. This involves solving for the dynamical response using the full form of Maxwell's equations with retardation effects. Another extension is to the dipole-exchange SW in magnetic nanotubes. This is applicable at larger wavevectors, where the dipole-dipole and exchange interactions are both important in the magnetization dynamics. A formalism is also developed for the linear response functions (Green's functions) in magnetic nanotubes, taking the wavevector regime of the magnetostatic modes. This enables us to calculate the spectral intensities of the modes. Numerical applications are presented for ferromagnets, such as Ni, Permalloy, and EuS, and for antiferromagnets, such as GdAlO3 and MnF2.
2011-01-14T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/78
https://ir.lib.uwo.ca/context/etd/article/1121/viewcontent/DAS_PhD_Thesis___FINAL.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Spin waves
magnetostatic modes
polaritons
dipole-exchange modes
nanotubes
cylindrical geometries.
oai:ir.lib.uwo.ca:etd-1120
2013-04-03T13:08:52Z
publication:anthro
publication:etdlac
publication:anthro-etd
publication:faculties
publication:etd
Exemplary Practice: Inscribing Conduct Along Upper Canada's Early Frontier
Bisha, Tim
This dissertation studies exemplary conduct along Upper Canada's early frontier. Presuming that exemplars reproduce core ideas of conduct for those who construct them, it is no surprise that exemplars by which authorities sought to make Upper Canada in Britain‟s image appeared in multiple arenas including legal discourse, newspaper publication, writings on conduct, informal notions of gender and domesticity, and travel writing. At the overlap of these different spaces, through special attention to an early burglary trial, the private dwelling house emerges in this dissertation as the moral core of Upper Canada. This claim interprets British legal definitions of human rights and duties, and a specific orientation to intention that these definitions entail, as supporting an intense emphasis on appearances that manifested as notions of conduct. I suggest that the articulation of absolute and relative rights, and their respective duties, creates a gap between individuals as elements unto themselves and individuals defined in terms of social relationships. This gap was reconciled by taking observable acts, including evidence of proper conduct, as measures of elements that were beyond direct observation, intention most crucially, which in turn measured the value of the act. As a consequence, observation—a web of relations involving acts, people observing them, who themselves are observed by others, and so on—got infused with a moral force it would not require if one could read intentions directly. Legal discourse thus put an emphasis on proper conduct that went beyond the letter of laws, whose formal expression had only limited influence on how conduct appeared in casual publications. My theoretical baseline is the practice approach of Ortner (1989), which views action, embodied in individuals, as emergent in analytic tensions between public institutions, particular situations, patterns in history and experience, and unpredictable, extra-systemic input. Since conduct is based in observation, and because the immanent structuring forces of practice entail relationships, I add to Ortner's model the necessary presence of multiple actors who are present to each other. This model helps unpack the concrete bodies, relations, moments, and constraints in which exemplars emerge, and also emphasizes their conservative tendency.
2011-04-15T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/138
https://ir.lib.uwo.ca/context/etd/article/1120/viewcontent/final_final.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Exemplar
Frontier
Practice theory
Ortner
Upper Canada
Conduct
Crime
Burglary
Dwelling House
Domesticity
Gender
Female
Anthropology
oai:ir.lib.uwo.ca:etd-1122
2010-12-22T20:45:38Z
publication:biomedeng-etd
publication:biomedeng
publication:faculties
publication:etd
Mapping the Flip Angle in Magnetic Resonance Imaging Using the Accelerated 3D Look-Locker Sequence
Wade, Trevor P
In the ongoing quest to extract more information from MRI images, there has arisen a need to rapidly map the flip angle. This has been primarily driven by the shift to stronger main field strengths, which bring with them improved SNR, but also new difficulties. In particular, the radio frequency field used to excite the magnetization can no longer be assumed uniform at field strengths of 3 Tesla and above. New rapid quantitative imaging techniques, such as DESPOT1 and DESPOT2, rely on accurate knowledge of the flip angle, and while this could safely be assumed to be the prescribed value at 1.5 Tesla, the same can no longer be said at 3 Tesla and above.
In this thesis, a new technique for mapping the flip angle in 3D will be introduced. This technique is based on a highly time efficient T1 mapping technique, known as Look-Locker, which was adapted to map the flip angle using either a double angle (DALL) or dual repetition time (DτLL) approach. The technique introduced is capable of producing 3D maps of the flip angle in less than one minute.
As part of the development of this flip angle mapping technique, a theoretical framework was developed to allow the optimization of the imaging parameters to achieve the best possible measurement of the flip angle. This framework also made it possible to compare the performance of the Look-Locker approaches to other techniques currently in use, which confirmed that, for imaging times less than one minute, the Look-Locker approach was optimal.
This fast imaging led to the development of a new approach to spoiling. While conventional spoiling approaches are optimized for imaging in the steady state, they can lead to significant errors and artefacts if used when sampling the transients of the Look-Locker method, especially with the short repetition times and large flip angles used. A newly developed spoiling technique using randomized RF phase and gradient crusher amplitudes was shown to significantly reduce the deviations from ideally spoiled transients, and thereby reduce the errors associated with the quantitative values derived from them.
2010-12-15T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/73
https://ir.lib.uwo.ca/context/etd/article/1122/viewcontent/twthesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
magnetic resonance imaging
B1+ mapping
flip angle
high field imaging
RF spoiling
efficiency
Analytical, Diagnostic and Therapeutic Techniques and Equipment
Biomedical Engineering and Bioengineering
oai:ir.lib.uwo.ca:etd-1123
2011-01-31T18:27:05Z
publication:csd
publication:csd-etd
publication:faculties
publication:etd
Algorithmic Contributions to the Theory of Regular Chains
Pan, Wei
Regular chains, introduced about twenty years ago, have emerged as one of the major
tools for solving polynomial systems symbolically. In this thesis, we focus on different
algorithmic aspects of the theory of regular chains, from theoretical questions to high-
performance implementation issues.
The inclusion test for saturated ideals is a fundamental problem in this theory.
By studying the primitivity of regular chains, we show that a regular chain generates
its saturated ideal if and only if it is primitive. As a result, a family of inclusion tests
can be detected very efficiently.
The algorithm to compute the regular GCDs of two polynomials modulo a regular
chain is one of the key routines in the various triangular decomposition algorithms. By
revisiting relations between subresultants and GCDs, we proposed a novel bottom-up
algorithm for this task, which improves the previous algorithm in a significant manner
and creates opportunities for parallel execution.
This thesis also discusses the accelerations towards fast Fourier transform (FFT)
over finite fields and FFT based subresultant chain constructions in the context of
massively parallel GPU architectures, which speedup our algorithms by several orders
of magnitude.
2011-01-25T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/80
https://ir.lib.uwo.ca/context/etd/article/1123/viewcontent/Pan_Wei_201101_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
symbolic computation
regular chain
regular GCD
subresultant
fast Fourier transform
GPU computing
Other Computer Sciences
Theory and Algorithms
oai:ir.lib.uwo.ca:etd-1124
2011-11-15T19:45:17Z
publication:csd
publication:csd-etd
publication:faculties
publication:etd
Advanced Topics on State Complexity of Combined Operations
Gao, Yuan
State complexity is a fundamental topic in formal languages and automata theory. The study of state complexity is also strongly motivated by applications of finite automata in software engineering, programming languages, natural language and speech processing and other practical areas. Since many of these applications use automata of large sizes, it is important to know the number of states of the automata. In this thesis, we firstly discuss the state complexities of individual operations on regular languages, including union, intersection, star, catenation, reversal and so on. The state complexity of an operation on unary languages is usually different from that of the same operation on languages over a larger alphabet. Both kinds of state complexities are reviewed in the thesis. Secondly, we study the exact state complexities of twelve combined operations on regular languages. The state complexities of most of these combined operations are not equal to the compositions of the state complexities of the individual operations which make up these combined operations. We also explore the reason for this difference. Finally, we introduce the concept of estimation and approximation of state complexity. We show close estimates and approximations of the state complexities of six combined operations on regular languages which are good enough to use in practice.
2010-12-16T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/65
https://ir.lib.uwo.ca/context/etd/article/1124/viewcontent/thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
state complexity
regular languages
combined operations
deterministic finite automata
estimation of state complexity
approximation of state complexity
Theory and Algorithms
oai:ir.lib.uwo.ca:etd-1125
2011-11-15T19:45:59Z
publication:math
publication:math-etd
publication:faculties
publication:etd
Descending Central Series of Free Pro-p-Groups
Combariza, German A
In this thesis, we study the first three cohomology groups of the quotients of the descending central series of a free pro-p-group. We analyse the Lyndon-Hochschild- Serre spectral sequence up to degree three and develop what we believe is a new technique to compute the third cohomology group. Using Fox-Calculus we express the cocycles of a finite p-group G with coefficients on a certain module M as the kernel of a matrix composed by the derivatives of the relations of a minimal presentation for G. We also show a relation between free groups and finite fields, this is a new exiting recent development. We do this by showing the explicit bijection between basic commutators and the irreducible polynomials over a certain finite field.
2010-12-15T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/68
https://ir.lib.uwo.ca/context/etd/article/1125/viewcontent/thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
cohomology
spectral sequences
Fox calculus
irreducible polynomials
basic commutators.
Algebra
oai:ir.lib.uwo.ca:etd-1126
2011-11-15T19:46:39Z
publication:electrical
publication:electrical-etd
publication:faculties
publication:etd
Arithmetic Units for the Elliptic Curve Cryptography with Concurrent Error Detection Capability
Hariri, Arash
The elliptic curve cryptography is an important branch in public-key cryptography. In this thesis, we consider the elliptic curve cryptography over binary extension fields from two different points of view. First, we investigate the underlying arithmetic operations in the elliptic curve cryptography. The main arithmetic operation is the scalar multiplication. This operation is based on two elliptic curve operations, known as the point addition and point doubling. Implementing these two elliptic curve operations requires finite field arithmetic, specifically, finite field addition, multiplication, squaring, and inversion. We focus on two finite field operations, namely finite field multiplication and squaring. For the finite field multiplication, we consider Montgomery multiplication algorithm and shifted polynomial basis to design bit-serial, digit-serial, bit-parallel, semi-systolic and systolic multipliers. In case of finite field squaring, we use the Montgomery multiplication algorithm for squaring using special type of irreducible pentanomials. We also investigate the finite field multiplication from the concurrent error detection point of view. This is due the fact that fault attacks have become a serious concern in cryptographic applications. In this regard, we design concurrent error detection schemes for different Montgomery multipliers. Our comparison results show that our proposed arithmetic units and concurrent error detection scheme provide improvements over their existing counterparts.
2010-12-16T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/75
https://ir.lib.uwo.ca/context/etd/article/1126/viewcontent/Thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Finite Field Arithmetic
Elliptic Curve Cryptography
Montgomery Multiplication
VLSI and Circuits, Embedded and Hardware Systems
oai:ir.lib.uwo.ca:etd-1127
2010-12-18T04:01:31Z
publication:ivey
publication:ivey-etd
publication:faculties
publication:etd
Incentives for Optimal Allocation of HIV Prevention Resources
Malvankar, Monali M
The thesis consists of three main chapters on optimal incentives for a multi-level allocation process of HIV/AIDS prevention funds. HIV/AIDS prevention funds often traverse several levels of distribution. At each level, equity-based heuristics are often used by decision-makers that may lead to sub-optimal allocation. Mathematical programming models may help to allocate prevention funds optimally. Thus, incentives could be given to decision-makers to encourage optimal allocation.
Chapter 4 investigates the impact of incentives by developing a model in which an upper-level decision-maker (UD) allocates funds to a single lower-level decision-maker (LD) who then distributes funds to local programs. The UD makes use of an incentive scheme to encourage a LD to allocate optimally. The results demonstrate that under certain conditions an incentive may help the upper-level to encourage optimal allocation at the lower-level.
Chapter 5 extends the model developed in Chapter 4 to incorporate information asymmetry. The information about the total infections prevented per dollar and preferences of the LD regarding equity-based allocation is known at the lower-level, but unknown at the upper-level. We examine conditions when loss of efficiency is higher or zero at the upper-level.
Chapter 6 evaluates the impact of two types of incentives between and within the two LDs. The UD sets the level of incentives and then the two LDs sets the fraction of the funds to be reserved for proportional allocation and the amounts allocated to the lower-level programs. We analyze each decision-makers’ behaviour at the equilibrium when either or both incentive schemes are incorporated.
2010-12-14T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/50
https://ir.lib.uwo.ca/context/etd/article/1127/viewcontent/Malvankar_Monali_M_201012_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
HIV/AIDS
resource allocation
incentives
optimization
Management Sciences and Quantitative Methods
oai:ir.lib.uwo.ca:etd-1128
2011-11-15T19:47:27Z
publication:psychology-etd
publication:psychology
publication:faculties
publication:etd
Parenting at Midnight: Measuring Parents' Thoughts and Strategies to Help Young Children Sleep Through the Night
Coulombe, Aimee J
Throughout the night, brief periods of arousal are common and not necessarily indicative of problematic sleep. Awakening without an easy return to sleep (“night-waking”), however, can be problematic for parents and children alike. Approximately 30% of preschool-aged children wake at least once per night and require parental intervention (“help or assistance”). Although parents’ responses to children’s night-waking (i.e., parents’ night-waking strategies) can determine the course of night-waking over time, very little is known about night-waking strategy use among parents of preschool-aged children. The purpose of the present dissertation was to lay the foundation upon which a better understanding of the relationship of parenting to night-waking among preschool-aged children can be built. In order to accomplish this goal, four measures were created: the Children’s Night-waking Behaviour Scale (CNBS), the Night-waking Vignettes Scale (NVS), the Parents’ Night-waking Thoughts and Affect Questionnaire (PNTQ), and the Night-waking Strategies Scale (NSS). Rigorous measurement development protocols were followed. These measures, as well as parent-report measures of children’s night-waking and questionnaires used to assess construct validity, were completed by a sample of 203 mothers (M age = 32.4 years, SD =5.1) of preschool-aged children (M age = 3.4 years, SD = 1.0). All four measures displayed adequate to good reliability and promising evidence of convergent validity was observed. Significant associations between the measures and children’s night-waking were also observed. Following measurement development and validation, a series of multiple regressions were conducted to explore associations among the measures and identify areas for further research. In these regressions, mothers’ night-waking strategies (as measured by the NSS) were significantly predicted by children’s behaviour during night-wakings (as measured by the CNBS), mothers’ agreement with night-waking strategies (as measured by the NVS), and mothers’ thoughts and affect during night-waking episodes (as measured by the PNTQ). Clinical and research implications of these findings are discussed.
2010-12-14T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/56
https://ir.lib.uwo.ca/context/etd/article/1128/viewcontent/Coulombe_J_Aimee_201102_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Sleep
parenting
preschool-aged children
night-waking
questionnaire development
Clinical Psychology
oai:ir.lib.uwo.ca:etd-1129
2011-11-25T15:43:24Z
publication:electrical
publication:electrical-etd
publication:faculties
publication:etd
Control and Power Supply for Resistance Spot Welding (RSW)
Salem, Meranda
In the automobile industry, Resistance Spot Welding (RSW) is widely used for its low cost, high speed, simple mechanism and applicability for automation. RSW has become the predominant means of auto body assembly, resulting in two to six thousands spot welds performed on each manufactured car. In the North American automobile industry there are approximately 100 billion spot welds, which are done every year.
RSW is the joining of two or more metal parts together in a localized area by resistive heating and pressure. Small Scale RSW (SSRSW) is commonly used for medical devices and electronic components, because the welded parts are thinner and smaller compared to common RSW applications, such as automotive applications.
According to a study of Edison Welding Institute, 20% of the welding quality issues are the weld schedule or power supply related. Therefore, to contribute to weld quality improvement, the study of different weld schedules or power supplies and control schemes needs to be improved by doing further studies in this area. Thus a novel power supply, which can provide a testing bench for these studies, was designed and developed in 2005 by L. J. Brown and J. Lin. This research study will focus on studying and improving weld power supplies, weld schedules and control modes. One of the goals for this research is to improve the consistency of weld nugget size and strength by using different control parameters, which will be weighted geometric averages of voltage and current. These control parameters are fed back to a Proportional Integral Derivative (PID) controller that is designed to control the Direct Current (DC) power supply for the RSW to come up with the best control parameters that will improve the consistency of the RSW spot welds.
Another goal for this research is it to further develop the existing DC power supply that was designed for SSRSW by L. J. Brown, to include tip voltage measurements, and Large Scale Resistance Spot Welding (LSRSW). This goal will lead to build additional weld modules to construct a 6000A welder in the future.
2011-04-11T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/130
https://ir.lib.uwo.ca/context/etd/article/1129/viewcontent/Meranda_Salem_A_201106_PhD_Thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Resistance Spot Welding (RSW)
Small Scale RSW
Large Scale RSW
DC power Supply
PID controller
Buck Converter
Controls and Control Theory
oai:ir.lib.uwo.ca:etd-1130
2011-04-12T18:46:55Z
publication:biochem-etd
publication:biochem
publication:faculties
publication:etd
Identification of Regions Responsible for the Open Conformation of S100A10 Using Chimaeric S100A11/S100A10 Proteins
Santamaria-Kisiel, Liliana
S100A11 is a dimeric, EF-hand calcium-binding protein. Calcium binding to S100A11 results in a large conformational change that uncovers a broad hydrophobic surface used to interact with phospholipid-binding proteins (annexins A1 and A2), and facilitate membrane vesiculation events. In contrast to other S100 proteins, S100A10 is unable to bind calcium due to deletion and substitution of calcium-ligating residues. Despite this, calcium-free S100A10 assumes an “open” conformation that is very similar to S100A11 in its calcium-bound state (Ca2+-S100A11). To understand how S100A10 is able to adopt an open conformation in the absence of calcium, seven chimeric proteins were constructed where regions from calcium-binding sites I and II, and helices II-IV in S100A11 were replaced with the corresponding regions of S100A10. The chimeric proteins having substitutions in calcium-binding site II displayed increased hydrophobic surface exposure as assessed by ANS fluorescence and phenyl Sepharose binding in the absence of calcium. This response is similar to that observed for Ca2+-S100A11 and calcium-free S100A10. Further, this substitution resulted in calcium-insensitive binding to annexin A2 for one chimeric protein. The results indicate that residues within site II are important in stabilizing the open conformation of S100A10 and presentation of its target-binding site. In contrast, S100A11 chimeric proteins with helical substitutions displayed poorer hydrophobic surface exposure and consequently, unobservable annexin A2 binding. This work represents a first attempt to systematically understand the molecular basis for the calcium-insensitive open conformation of S100A10.
2010-12-10T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/105
https://ir.lib.uwo.ca/context/etd/article/1130/viewcontent/Santamaria_Kisiel_Liliana_L_201106_PhD_Thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
EF-hand
calcium-binding protein
hydrophobicity
conformational change
fluorescence
NMR spectroscopy
Protein design
Biochemistry
Molecular Biology
Other Biochemistry, Biophysics, and Structural Biology
Structural Biology
oai:ir.lib.uwo.ca:etd-1131
2010-11-16T14:34:33Z
publication:pharmtox-etd
publication:physpharm
publication:faculties
publication:etd
Pharmacokinetics and Therapeutic Uses of Mesna
Cutler, Murray J
In the early 1980s, significant advancement in the safety of ifosfamide therapy was achieved by co-administrating mesna (sodium 2-mercaptoethane sulfonate) to prevent dose-limiting hemorrhagic cystitis. Mesna exerts its protective effect within the urine, where its free sulfhydryl group is able to conjugate cytotoxic metabolites. Within the circulation, however, mesna exists primarily as its inactive disulfide, dimesna. Dimesna is currently undergoing clinical development as a prodrug (BNP7787) to treat cisplatin-induced nephrotoxicity. Remarkably, chemoprotection is achieved without attenuation of efficacy of co-administered anti-cancer agents. This is widely attributed to the kidney-specific disposition and stability of dimesna.
We sought to evaluate the role of drug transporters in the disposition of dimesna. In vitro screens of uptake and efflux transporters identified putative mechanisms of apical and basolateral uptake of dimesna and subsequent secretion of mesna into renal tubules. Administration of the renal drug transporter inhibitor probenecid to healthy subjects significantly increased combined mesna and dimesna plasma exposure while decreasing the renal clearance due to secretion and steady-state volume of distribution.
Chemical reduction of dimesna to mesna is essential for the mitigation of ifosfamide- and cisplatin-induced toxicities. In vitro, reduction of dimesna was facilitated by redox enzymes of the thioredoxin and glutaredoxin systems and also by non-enzymatic thiol-disulfide exchange with cysteine and glutathione. These findings supported the further investigation of mesna as a thiol exchange agent to lower the toxic endogenous thiol amino acid homocysteine (Hcy).
Increased plasma total homocysteine (tHcy) is a graded, independent risk factor for the development of atherosclerosis and thrombosis. Over 90% of patients with end-stage renal disease (ESRD) have elevated plasma tHcy. Previous studies have expanded the use of mesna to exchange with albumin-bound Hcy, thereby enhancing its dialytic clearance. Although an initial pilot study of 12 mg/kg intravenous mesna administered predialysis caused a significant decrease in plasma tHcy compared to placebo, prolonged treatment had no effect on plasma tHcy.
Successful therapeutic uses of mesna and dimesna are likely due to their unique disposition by renal drug transporters and thiol-disulfide redox equilibrium. Loss of renal transporter function due to disease, drug-drug interactions, or genetic variability may decrease their therapeutic efficacy.
2010-11-16T14:39:13Z
text
application/pdf
https://ir.lib.uwo.ca/etd/28
https://ir.lib.uwo.ca/context/etd/article/1131/viewcontent/Cutler_Murray_J_201011_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Mesna
Dimesna
Transporters
Thiol-disulfide exchange
Homocysteine
End-Stage Renal Disease
Pharmacokinetics
Pharmacology
oai:ir.lib.uwo.ca:etd-1132
2010-11-16T16:57:49Z
publication:psychology-etd
publication:psychology
publication:faculties
publication:etd
Causality and Similarity in Autobiographical Event Structure: An Investigation Using Event Cueing and Latent Semantic Analysis
O'Connor, Christopher M
The influence of similarity- and causally-based relations on the organization of autobiographical events was investigated using extended strings of related event memories. These strings were elicited using an event cueing paradigm in which participants generated descriptions of memories from their life, which were then presented as cues to subsequent event memories. In Experiment 1, similarity between generated events was investigated using participants’ similarity ratings, Latent Semantic Analysis, and experimenter judgements of shared event properties. For events close together in a string, event owners’ similarity ratings were higher than non-owners’, and non-owners’ ratings were comparable to similarity calculated using LSA. In Experiment 2, the influence of causal connectivity of events on perceived event similarity was investigated using causality ratings by event owners and non-owners. Results indicated that many events cued other events based on causal relations, owners’ causal ratings were highly consistent, and the ownership advantage in Experiment 1 could in part be explained by causal connections among events. It is concluded that both event similarity and causality are important aspects of the organization of autobiographical memory.
2010-11-16T20:12:25Z
text
application/pdf
https://ir.lib.uwo.ca/etd/29
https://ir.lib.uwo.ca/context/etd/article/1132/viewcontent/O_Connor_Christopher_M_201011_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Autobiographical memory
event memory
autobiographical
memory
event
cueing
event cueing
LSA
Latent Semantic Analysis
similar
similarity
causal
causality
Cognitive Psychology
oai:ir.lib.uwo.ca:etd-1135
2011-11-15T19:49:15Z
publication:ivey
publication:ivey-etd
publication:faculties
publication:etd
Occasioning Dialogic Spaces of Innovation: The pan-Canadian EHR, Infoway and the Re-Scripting of Healthcare
Saeed, Akbar M
The Canadian public healthcare system appears to currently be under considerable strain. Escalating costs, dwindling budgets and growing patient dissatisfaction are just a few of the systemic pressures that have called into question our current ways of delivering healthcare. As a consequence, there is a growing recognition that renewal is needed, and that this renewal, to be successful, should meet the needs of a wide array of stakeholders, hence calling for unprecedented levels of collaboration among increasingly fragmented interests. In order to bring about this renewal, the federal government seems to be intent on implementing a pan-Canadian electronic health record (EHR) system. To that end, in 2001, Canada Health Infoway was born out of a novel collaboration between federal and jurisdictional health ministries with the specific mandate to accelerate the implementation of EHRs across Canada. In this thesis, I use material-semiotic and dialogic approaches to gain a more nuanced understanding of how the pan-Canadian EHR system is unfolding and in what ways Infoway is trying to accelerate that unfolding. I conclude by suggesting that a more dialogic approach to innovating, in which the innovator focuses on finding various ways to occasion dialogic spaces, may better foster the creation of new meanings of the innovation and therefore result in a more, and not less, harmonious change process. Furthermore, through these dialogic spaces, it is not just multiple meanings of the innovation that are being occasioned, but the innovation itself seems to become more meaningful.
2010-12-17T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/72
https://ir.lib.uwo.ca/context/etd/article/1135/viewcontent/auto_convert.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
collaborative change
cultivation
dialogic spaces
electronic health records
technology-based innovation
Technology and Innovation
oai:ir.lib.uwo.ca:etd-1140
2011-03-03T03:29:28Z
publication:nursing-etd
publication:nursing
publication:faculties
publication:etd
Effects of Work Environments on Nursing and Patient Outcomes
Purdy, Nancy M
Nurses are leaving the profession due to high levels of job dissatisfaction arising from current working conditions characterized by heavy workloads, limited participation in decision making and lack of development opportunities (Canadian Health Services Research Foundation [CHSRF], 2006a). To gain organizational support for workplace improvements and thereby improve nursing retention, evidence is needed to demonstrate the impact of the work environment on patient care. The purpose of this study was to determine the relationship between nurses' perceptions of their work environment and the quality and risk outcomes for both the patient and the nurse. Kanter's (1977, 1993) theory of structural empowerment guided the study. Empowering work environments for nurses were hypothesized to impact group processes and thereby work effectiveness as reflected in patient outcomes (patient satisfaction, therapeutic self care, falls and nurse-assessed risks). Empowering workplaces were also hypothesized to enhance the nurse's psychological empowerment and, in turn, engagement in empowering behaviours that lead to quality care and job satisfaction. A multi-level cross-sectional design was used to test the study model. Self-report surveys were used for a sample of nurses (n=679) and discharged patients (n=1005) affiliated with medical and surgical units from 21 hospitals in Ontario. Unit characteristics and falls data were obtained from existing hospital databases. Using multilevel structural equation modeling, the hypothesized model fit well with the data (χ2=21.074, df=10, CFI=.985, TLI=.921, RMSEA=.041, SRMR .002[within] and .054[between]). Empowering workplaces had positive effects on nurse-assessed quality of care and predicted fewer falls and nurse-assessed risks as mediated through group processes. These conditions positively impacted individual psychological empowerment which, in turn, had significant direct effects on empowered behaviour, job satisfaction and care quality. Theoretically, evidence supported the further evolution of structural empowerment theory to include group processes and empowered behaviour as mediators to various nurse and patient outcomes. The evidence from this study also reinforced the critical need to invest in improving nursing work environments for the benefit of patients and nurses. Theory-informed strategies for changes to the workplace have the potential to mitigate against projected nursing shortages and ensure a sustainable workforce to meet future demands for care.
2011-01-20T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/92
https://ir.lib.uwo.ca/context/etd/article/1140/viewcontent/Purdy_Nancy_M_201106_PhD_thesis_revised_FINAL_Feb_28__2011.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
work envirnoments
empowerment
teamwork
patient outcomes
nursing job satisfaction
quality of care
Nursing Administration
oai:ir.lib.uwo.ca:etd-1142
2011-03-25T21:12:25Z
publication:etdlac
publication:biophysics
publication:biophysicsetd
publication:faculties
publication:etd
Hemodynamics in the Stenosed Carotid Bifurcation with Plaque Ulceration
Wong, Emily Y
The presence of irregular plaque surface morphology or ulceration of the atherosclerotic lesion has been identified as an independent risk factor for ischemic stroke. Doppler ultrasound (DUS) is the most commonly performed non-invasive technique used to assess patients suspected of having carotid artery disease, but currently does not incorporate the diagnosis of plaque ulceration. Advanced Doppler analyses incorporating quantitative estimates of flow disturbances may result in diagnostic indices that identify plaque ulcerative conditions. A technique for the fabrication of DUS-compatible flow phantoms was developed, using a direct-machining method that is amenable to comprehensive DUS investigations. In vitro flow studies in an ensemble of matched model vessel geometries determined that ulceration as small as 2 mm can generate significant disturbances in the downstream flow field in a moderately stenosed carotid artery, which are detectable using the DUS velocity-derived parameter turbulence intensity (TI) measured with a clinical system. Further experimental results showed that distal TI was significantly elevated (P < 0.001) due to proximal plaque ulceration in the mild and moderately stenosed carotid bifurcation (30%, 50%, 60% diameter reduction), and also increased with stenosis severity. Pulsatile computational fluid dynamics (CFD) models, with simulated particle tracking, demonstrated enhanced flow disruption of the stenotic jet and slight elevations in path-dependent shear exposure parameters in a stenosed carotid bifurcation model with ulceration. In addition, CFD models were used to evaluate the DUS index TI using finite volume sampling.
2011-02-22T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/94
https://ir.lib.uwo.ca/context/etd/article/1142/viewcontent/Emily_Wong_Y_201105_PhD.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
atherosclerosis
carotid artery
plaque ulceration
flow disturbances
Doppler ultrasound
computational fluid dynamics
Diagnosis
Fluid Dynamics
Medical Biophysics
oai:ir.lib.uwo.ca:etd-1144
2011-02-09T21:25:02Z
publication:edu
publication:faculties
publication:edu-etd
publication:etd
International Chinese and Canadian Students' Experiences of Internationalization at a Canadian University
Weber, Linda J
Internationalization, as a response to globalization, is one of the key drivers and shapers of the fundamental changes transforming the world of higher education. There is a need to understand internationalization within higher education from the vantage point of the domestic and international students who are currently being educated because their experiences testify to the provision of quality education. Using a Case Study approach this research explores ways that the internationalization of higher education impacts students’ intercultural relations, identities, intercultural sensitivity, critical understandings, notions of citizenship and futures. A postcolonial perspective is used to explore how students perceive the influences of globalization. Contemporary ideological constructions of globalization are seen in historical and cultural contexts and not as naturalized and reified economic processes. Various themes were identified in international Chinese and domestic students’ accounts of their experiences of internationalization at a Canadian university including: education and marketization, academic pressure and performance, language, intercultural connections and barriers, and cultural hybridity. Results indicated that students are impacted by internationalization in complex and contradictory ways. The Intercultural Development Inventory (IDI) was used as a tool to demonstrate growth in students’ intercultural sensitivity. The intercultural experiences students discussed in interviews were difficult to compare with the inventory results. The IDI did not, in the space of one academic year, capture the finer nuances and changes in students’ intercultural growth and sensitivity. Students’ intercultural sensitivity did not necessarily progress or improve with increased intercultural contact and in some cases, it decreased.
2011-01-27T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/82
https://ir.lib.uwo.ca/context/etd/article/1144/viewcontent/THESIS_2.pdf
https://ir.lib.uwo.ca/context/etd/article/1144/filename/0/type/additional/viewcontent/Thesis___first_pages__Dec._2.docx
https://ir.lib.uwo.ca/context/etd/article/1144/filename/1/type/additional/viewcontent/Thesis_first_pages_Feb.2011.docx
https://ir.lib.uwo.ca/context/etd/article/1144/filename/2/type/additional/viewcontent/February_final_2011.docx
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
internationalization of higher education
international students
domestic students
intercultural learning
cultural identity
citizenship
International and Comparative Education
oai:ir.lib.uwo.ca:etd-1145
2011-11-15T19:55:00Z
publication:english
publication:english-etd
publication:faculties
publication:etd
The Burdens of Body's Beauty: Pre-Raphaelite Representations of the Body in William Morris's the Defence of Guenevere and Other Poems (1858) and Algernon Swinburne's Poems
Steffler, Thomas A
This dissertation studies representations of the body in the first two published volumes of Pre-Raphaelite poetry, William Morris’s The Defence of Guenevere, and Other Poems (1858) and Algernon Charles Swinburne’s Poems and Ballads, First Series (1866). These two volumes (along with Dante Gabriel Rossetti’s 1870 Poems) were disparaged as the work of the “Fleshly School of Poetry” by the critic Robert Buchanan in 1871, and this dissertation seeks to understand through close reading how the depiction of the body in the poetry of Morris and Swinburne so perturbed their contemporaries and why it continues to elude modern readers. Particularly, this study considers how representations of the body and its demands in these two works constitute a Pre-Raphaelite challenge to social, scientific, and aesthetic theories that involve sexuality, gender, and identity in relation to the body. The first chapter of the dissertation explains the development of an aesthetic of the flesh for the early Pre-Raphaelite Brotherhood, which directly affects the way in which Morris and Swinburne would approach the problem of the body and perception in their poetry. This chapter also explains how Maurice Merleau-Ponty’s ideas on phenomenology inform the analysis of the Pre-Raphaelite body’s direct and active engagement with the world in poems of Morris and Swinburne. The second chapter focuses on Morris’s The Defence of Guenevere, and Other Poems and its depiction of the experiences of the body as they strike the perceiving subject, particularly in moments when the body comes under a sexual strain that complicates its standing with the soul. The third chapter focuses on Swinburne’s Poems and Ballads, First Series as a wide-ranging experiment in eroticism, and considers the volume’s treatment of desire and sexuality in the performance of identity through gender and memory. The final chapter summarizes and synthesizes the readings of Morris’s and Swinburne’s “fleshly” poems to place them within a continuum of changing attitudes towards the body and identity in the nineteenth century.
2010-03-13T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/38
https://ir.lib.uwo.ca/context/etd/article/1145/viewcontent/Complete1.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
William Morris
Defence of Guenevere
Algernon Swinburne
Poems and Ballads
representations of the body
sexuality
identity
Literature in English, British Isles
oai:ir.lib.uwo.ca:etd-1148
2015-11-05T12:42:06Z
publication:sociology-etd
publication:etdlac
publication:sociology
publication:faculties
publication:etd
Constructing Categories, Imagining a Nation: A Critical Qualitative Analysis of Canadian Immigration Discourse
Flynn, Andrea R
Immigration and population diversity are hot topics in Canadian society. Canadian immigration discourses include widespread debates over the value of immigration to Canada, the structure of the immigration program, and the impact of immigrants with ‘non-Canadian’ traditions and practices on Canadian society. Representations deployed in these discourses operate to socially construct the Canadian nation, and symbolically define immigrants’ place in Canada’s national imagined community. The present thesis elaborates on theoretical understandings of the social construction of the Canadian national community in the contemporary era of international migration by providing a qualitative critical discourse analysis of three types of Canadian immigration discourses: (1) media discourse (focusing on news media coverage of marriage immigrants); (2) policy discourse (addressing materials produced by Citizenship and Immigration Canada); and (3) official measurement of immigrants (in the form of the Longitudinal Survey of Immigrants to Canada and its accompanying analytical reports). The thesis reveals that these dominant immigration discourses serve to co-construct immigrants, Canadians, and the Canadian state in the imagining of the Canadian national community. These representations reveal that contemporary immigration to Canada is a major source of tension and uncertainty. This ambivalence manifests as inconsistent representations of immigrants (in general, and different groups of immigrants, in particular), involving co-existing, contradictory discourses of inclusion, marginalization, and exclusion. These representations inconsistently gender and racialize immigrants, often in the context of immigration categories of admission. These varied representations are interpreted in the thesis in terms of the convergence of historical patterns of discrimination, the growth in immigration from non-European source countries, contemporary national and international concerns (e.g., economic stability; terrorism), and rhetorical pride in Canada as a multicultural nation. Overall, the present study contributes to theoretical work on Canadian immigration and imagined communities by furthering understandings of the various ways in which immigration discourses operate as conceptual spaces wherein what it means to be Canadian is articulated, and the place of immigrants in the Canadian nation is defined and contested.
2011-01-10T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/77
https://ir.lib.uwo.ca/context/etd/article/1148/viewcontent/Flynn_Andrea_R_201106_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Canada
immigration
imagined community
imagined futures
critical discourse analysis
Sociology
oai:ir.lib.uwo.ca:etd-1152
2011-02-17T20:33:55Z
publication:english
publication:english-etd
publication:faculties
publication:etd
Re-forging the smith: an interdisciplinary study of smithing motifs in Völuspá and Völundarkviða
Einarson, Leif
This project examines smithing motifs in the Old Norse poems Völuspá and Völundarkviða. The purpose of this research is to develop an understanding of these motifs in the contexts in which these poems were composed and transmitted.
The first chapter examines stanza seven of Völuspá and the role of the aflar, “forges/furnaces”, that the Æsir establish as part of their first settlement. I examine the significance of these aflar from literary, linguistic and archaeological perspectives and in relation to metallurgical functions and communal structures. I present a definition of afl and I conclude with a summary of the significance of the aflar in Völuspá stanza seven.
The second chapter examines stanza forty of Völuspá and the role of the toponym Járnviðr, “Iron-wood”, in both the mythological and socio-historical landscape. I analyze the derivatives and morphological parallels of this toponym. I conclude that this toponym exhibits a geographical concept of resources related to bog iron smelting.
The third chapter examines artisanal motifs in Völundarkviða in comparison to early Germanic customs and possible literary and historical analogues. I study the poem as a performance of spatial, networked relations between artisans and the aristocratic elite. I examine the significance of Völundr’s artisanal revenge as a subversion of early Germanic customs.
Whereas smithing motifs and smithing figures have regularly been approached through archetypal and comparative methodologies, this thesis attempts to broaden our understanding of these motifs in relation to specific literary, social and technical features of metalworking in early medieval Scandinavia.
2011-01-31T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/88
https://ir.lib.uwo.ca/context/etd/article/1152/viewcontent/Einarson_2011___Re_forging_the_Smith.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
afl
rauði
bog iron
Járnviðr
Völundr
central-place complex
Medieval Studies
oai:ir.lib.uwo.ca:etd-1153
2011-02-18T17:40:45Z
publication:civil
publication:faculties
publication:etd
publication:civil-etd
Numerical Simulation of Tornado-like Vortices
Natarajan, Diwakar
The thesis investigates by numerical simulation the flow characteristics of tornado like vortices produced by three types of vortex generators, namely, Ward-type Tornado Vortex Chamber (TVC), WinDEEE Dome and Atmospheric Vortex Engine (AVE).
Laboratory scale (Ward-type TVC) tornado-like vortices were simulated for swirl ratios 0.1 to 2.0 using the CFD code Fluent 6.3. The simulations with Reynolds stress model compare well with past experimental results. Multiple vortices were observed for high swirl ratios in LES simulation. These simulations have generated a comprehensive benchmark data for future modelers and experimenters.
The effects of translation and surface roughness on laboratory scale tornado-like vortices have been investigated. The simulated results show that the effect of translation is not uniform over the range of swirl ratios. For lower swirl ratios the translation reduces the maximum mean tangential velocity and for high swirl ratios it causes a slight increase in the maximum mean tangential velocity. The introduction of roughness reduces the mean tangential velocity at all swirl ratios, in other words the roughness causes an effect similar to reducing the swirl ratio.
Numerical simulations for the WindEEE dome, a novel hexagonal wind tunnel, were performed. Suitable inlet and outlet configurations were identified. The study shows the feasibility for generating axi-symmetric (tornado-like and downburst-like) and straight flow wind profiles in the dome. Also presented are the results of numerical simulation of Atmospheric Vortex Engine (AVE), which is intended to generate a tornado-like vortex to capture the mechanical energy produced during upward heat convection. The results show that the prototype design of AVE is capable of generating a vortex flow in the atmosphere much above the AVE and the vortex acts as a physical chimney limiting the mixing of surrounding air into the rising plume of hot air. The geometrical parameters considered in the simulations provide a good starting point for future designs.
2011-01-25T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/89
https://ir.lib.uwo.ca/context/etd/article/1153/viewcontent/Natarajan_Diwakar_201102_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Tornado
Swirl ratio
Surface roughness
Vortex translation
WinDEEE dome
Atmospheric Vortex Engine
Other Civil and Environmental Engineering
oai:ir.lib.uwo.ca:etd-1156
2011-11-15T19:56:41Z
publication:etdlac
publication:chemeng-etd
publication:chemeng
publication:faculties
publication:etd
Catalytic Steam Gasification of Biomass Surrogates: A Thermodynamic and Kinetic Approach
Salaices, Enrique
Gasification of biomass is an environmentally important technology that offers an alternative to the direct use of fossil fuel energy. Steam gasification is getting increased attention as a potential source of renewable energy since it produces a gaseous fuel suitable for industrial applications in highly efficiently power/heat energy production, transport fuel, and as a feedstock for chemical synthesis. Furthermore, catalytic steam gasification has other advantages hence (i) it produces a gas with higher heating value; (ii) it reduces the diluting effect of N2 from air; (iii) it eliminates the need of cleaning, upgrading and/or conditioning the product gas for certain applications; and (iv) it eliminates the need for an expensive oxygen plant when both air and oxygen are used as gasification mediums. Catalytic steam gasification of biomass in fluidized beds is a promising approach given its rapid biomass heating, its effective heat and mass transfer between reacting phases, and its uniform reaction temperature. Moreover, fluidized beds tolerate wide variations in fuel quality as well as broad particle-size distributions. However, catalytic steam gasification is a more complex process resulting from: (i) the heat necessary to sustain the process is directly supplied by the partial combustion of the feedstock during the process, as it happens when air or oxygen is used, (ii) the rapid catalyst deactivation that occurs due to heavy coking, and (iii) tar formed during the process. This Ph.D. dissertation reports a research study on the steam gasification of biomass over a Ni/-alumina catalyst using model compounds. This research allows elucidating the factors inherent to this process such as thermodynamic restrictions and mechanistic reaction steps. The ultimate aim is to establish the chemical reaction engineering tools that will allow the design and operation of large scale fluidized bed units for biomass steam catalytic gasification. On this basis, a thermodynamic equilibrium model based on evaluations involving C, H and O elemental balances and various product species (up to C6 hydrocarbons) was developed. This model establishes the effect of biomass composition, temperature, and steam on the various gas product molar fractions. Based on the proposed equilibrium model and using glucose, as a model biomass species, an optimum gasification temperature close to 800°C and a steam/biomass ratio between 0.5 and 0.7 g/g is established. Experiments were carried out in the CREC fluidized Riser Simulator under gasification conditions using a) glucose as a model compound for the cellulose contained in biomass, and b) 2-methoxy-4-methyphenol as a model compound for the lignin that is found in biomass. The experimental data show that for reaction times longer than 30 seconds, chemical species are essentially equilibrated and that the proposed thermodynamic model does provide an adequate description of various product fractions. Data obtained also demonstrate the shortcomings of equilibrium models for gasifiers with reaction times shorter than 10 seconds and the need for non-equilibrium models to describe gasifier performance at such conditions. Taking the above into consideration, a reaction network and a kinetic model for biomass catalytic steam gasification were proposed. This kinetic model was developed using a coherent reaction engineering approach where reaction rates for various species are the result of the algebraic addition of the dominant reactions. It is also demonstrated that using an experimental-modeling procedure, where intrinsic kinetic parameters and adsorption constants are decoupled in their evaluation in the CREC Riser Simulator eliminates overparametrization with successfully parameter correlation. Numerical regression of the experimental data leads to kinetic parameters with narrow spans suggesting that the proposed kinetic model satisfactorily describe the catalytic conversion of glucose and 2-methoxy-4-methyphenol under gasification conditions.
2010-03-14T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/51
https://ir.lib.uwo.ca/context/etd/article/1156/viewcontent/Salaices_Enrique_201012_PhD_Thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Steam Gasification
Biomass
Ni/a-Al2O3 catalyst
Tars
Thermodynamic equilibrium
Kinetics
Catalysis and Reaction Engineering
Chemical Engineering
oai:ir.lib.uwo.ca:etd-1160
2011-02-22T21:36:57Z
publication:epidem
publication:epidem-etd
publication:faculties
publication:etd
Ethical Challenges in Cluster Randomized Trials
McRae, Andrew
Research Questions: This dissertation examines how ethical challenges in CRTs are addressed in practice. This dissertation also provides guidance as to who must be considered a research subject in a CRT, and when consent must be sought from research subjects.
Methods: The association between consent practices in healthcare CRTs and particular trial features were examined using multivariable logistic regression modelling. Information on ethical challenges encountered by CRT researchers in practice was obtained by analyzing semi-structured interviews with experienced CRT investigators. Two normative questions, “Who is the research subject in CRTs?” and “When is consent required in CRTs?” were also addressed.
Results: Consent in CRTs is associated with smaller cluster sizes, and the use of individual-level experimental and data collection interventions. CRT researchers are most concerned with issues around informed consent, and less concerned with issues related to the analysis of harms and benefits in CRTs.
Research subjects are individuals who are intervened upon by investigators; who interact with investigators; or who contribute identifiable private information. Consent must be sought for CRT participation from research subjects. Consent is not required from cluster members who are not research subjects. Consent after randomization of clusters is permissible if necessary. Some CRTs may meet criteria for a waiver of informed consent.
Conclusions: This dissertation describes the state of the art of ethics practices in CRTs, and presents guidance around consent issues in CRTs that will inform the development of international ethics guidelines for CRTs.
2011-01-31T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/91
https://ir.lib.uwo.ca/context/etd/article/1160/viewcontent/Ethical_Challenges_in_Cluster_Randomized_Trials_22.2.11.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Research Ethics
Cluster Randomized Trials
Informed Consent
Health Services Research
Quality Improvement
Knowledge Translation.
Bioethics and Medical Ethics
oai:ir.lib.uwo.ca:etd-1167
2011-11-16T19:21:04Z
publication:etdlac
publication:chemeng-etd
publication:chemeng
publication:faculties
publication:etd
The Effect of Particle Size on Hydrolysis and Modeling of Anaerobic Digestion
Aldin, Saad
Batch experiments were performed to investigate the effect of particulate protein particle size on the hydrolysis of casein in anaerobic degradation. While particle size did not affect the ultimate protein degradation efficiency, the hydrolysis rate coefficient increased from 0.034 to 0.298 d-1 with the change in specific surface area from 0.01 to 0.192 m2/g. The maximum methane production rate was affected by the particle size change, although the ultimate amount of methane produced was approximately the same despite the change in specific surface area. A mathematical relationship between the hydrolysis rate coefficient and specific surface area was developed and a new hydrolysis equation was proposed and verified. Ultrasound treatment of wastewater sludges prior to anaerobic digestion disrupts the flocs and causes lysis of the bacterial cells releasing both inter and intracellular materials. Primary (PS) and waste activated sludge (WAS) were treated with different ultrasonic intensities, varying sonication time and amplitude at a constant frequency. Results showed that gas production, volatile fatty acids, ratio of soluble chemical oxygen demand to total chemical oxygen demand and soluble protein increased, while particulate protein and particle size of the sludge decreased with sonication time. An empirical model was developed to determine the economic viability of ultrasound based on electrical energy input and energy obtained from enhanced methane production. Ultrasonic pretreatment is only economically viable for primary sludge at low sonication doses. The Anaerobic Digestion Model # 1 (ADM1) was applied to the batch anaerobic digestion for sonicated and non-sonicated sludge. The model successfully simulated the experimental trends. The efficiency of ultrasound as a pretreatment method for hog manure prior to anaerobic digestion was also evaluated at specific energies of 250 to 30,000 kJ/kg total solids (TS). This study confirmed that CODsolubilisation from particulates correlated well with the more labor and time intensive degree of disintegration test. The particle size distribution for hog manure was bimodal (0.6 - 2500 mu m), while ultrasound primarily impacting particles in the 0.6-60 mu m range. Hog manure is more amenable to ultrasound than waste activated sludge, as it took only 3000 kJ/kgTS to cause 15% more solubilization as compared to 25000 kJ/kg TS for waste activated sludge. Bound protein degradation during sonication was 13.5% at 5000 kJ/kg TS and remained constant thereafter for higher energy input. Biomass cell rupture occurred at specific energy of 500 kJ/kg TS. An economic evaluation indicated that only a specific energy of 500 kJ/kg TS was economical, with a net energy output valued at $ 4.1/ton of dry solids, due to a 28% increase in methane production. Degradation of odorous compounds in sludge during anaerobic digestion was systematically studied and simulated using the Anaerobic Digestion Model # 1 (ADM1). The degradation of various protein fractions (particulate, soluble and bound), VFAs, lipids and amino acids of PS and WAS were monitored during anaerobic digestion. Degradation kinetics of the odorous compounds namely, protein, amino acids, lipid and volatile fatty acids (VFAs) were determined. Relationships between protein fractions and volatile suspended solid were established. A strong relationship between bound protein, a major odors precursor, and volatile suspended solid degradation was found, while no statistically significant difference in bound protein reduction was observed between PS and WAS. ADM1 successfully simulated the lab scale continuous anaerobic digestion; model results with optimized parameters showed good agreement with the experimental data for methane production and all other sludge parameters including odor precursors such as lipids, VFAs and proteins.
2010-05-12T07:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/60
https://ir.lib.uwo.ca/context/etd/article/1167/viewcontent/Aldin_Saad_201012_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Particle size
casein
anaerobic digestion
hydrolysis kinetics
specific surface area. Pretreatment; Bound protein; Degree of disintegration; Ultrasound; hog manure
sludge pretreatment
gas production.
odors precursors
cell protein
bound protein
ADM1 model.
Biochemical and Biomolecular Engineering
Environmental Engineering
oai:ir.lib.uwo.ca:etd-1168
2011-11-16T19:23:54Z
publication:biomedeng-etd
publication:biomedeng
publication:faculties
publication:etd
Development of an Active Elbow Motion Simulator and Coordinate Systems to Evaluate Kinematics in Multiple Positions
Ferreira, Louis M
Elbow disorders are common as a consequence of both traumatic and degenerative conditions. Relative to disorders of the lower limb, there is comparatively little evidence to direct the treatment of many elbow disorders. Biomechanical studies are required to develop and validate the optimal treatment of elbow disorders prior to their application in patients. Clinically relevant simulation of elbow motion in the laboratory can be a powerful tool to advance our knowledge of elbow disorders. This work was undertaken with the rationale that simulation and quantification of elbow motion could be improved significantly. This treatise includes the development and evaluation of an in-vitro elbow motion simulator which, with the humerus horizontally positioned, is the first to achieve active flexion and extension in a vertical plane. Additionally, it is capable of operating in the vertical, varus and valgus positions, and while maintaining full forearm pronation or supination. The simulator controller employs a Cascade PID configuration with feedforward transfer functions, which achieves unified control of flexion angle and muscle tension for multiple muscles. Feedback of the elbow joint angle and muscle tension is utilized to achieve closed-loop control. A performance evaluation in a full series of specimens clearly demonstrated that the actual joint angle is not more than 5 degrees removed from the desired setpoint during flexion or extension in any position. Also, a new method for creating upper extremity bone segment coordinate systems which are derived from elbow flexion and forearm rotation was developed and tested. This produced joint kinematics with significantly less inter-subject variability than traditional anatomy-derived coordinate systems. This minimally-invasive method also provides increased statistical power for laboratory based studies and may prove useful for clinical applications. The new simulation techniques developed herein were applied to an in-vitro investigation of olecranon fracture repair with clinical significance. This study revealed valuable insights into a common repair procedure. This was made possible by the previously unattainable measurements that these new techniques now provide. These developments will assist surgeons and other investigators in the design and evaluation of treatments for elbow disorders, and contribute to the betterment of patient care.
2011-01-26T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/84
https://ir.lib.uwo.ca/context/etd/article/1168/viewcontent/Ferreira_Louis_M_201106_PhD_Thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
elbow motion
active simulation
biomechanics
kinematics
coordinate systems
Biomedical Devices and Instrumentation
oai:ir.lib.uwo.ca:etd-1171
2011-02-09T20:19:19Z
publication:mechanical-etd
publication:faculties
publication:mechanical
publication:etd
Synthesis of One-Dimensional And Two-Dimensional Carbon Based Nanomaterials
Ionescu, Mihnea Ioan
Particular physical and chemical properties of carbon based nanomaterials (CBNs) have promised and exhibited great applications in manufacturing various nanodevices such as electron field emitters, sensors, one-dimensional conductors, supercapacitors, reinforcing fibres, hydrogen storage devices, and catalyst support for fuel cells electrodes. Despite these amazing technical progresses, many challenges still remain in the development of synthesis methods suitable for commercial applications and fabricating novel functional nanostructures with complex architecture.
In this Ph.D. thesis, one-dimensional (1D), two-dimensional (2D) carbon nanostructures, and 1D/2D hybrid of carbon nanostructures have been synthesized using various chemical vapour deposition (CVD) methods. The objective of this work is to explore the potential of various CVD methods, including specially-designed CVD techniques, such as modified spray pyrolysis, plasma enhanced CVD, and magnetron sputtering deposition. By making use of these innovative methods, high density regular and nitrogen-doped nanotubes, graphite nanosheets and assemblies have been successfully obtained on conducting and semiconducting substrates. For the modified spray pyrolysis method, systematic investigation of regular carbon nanotubes (CNTs) was conducted in terms of optimizing various experimental parameters such as hydrocarbon source, temperature, and catalyst in order to control the quality and structure of CBNs. Doping of nitrogen into carbon nanotubes was also systematically studied to enhance their electrical and mechanical properties. Interestingly, a novel structure of multi-branched nitrogen doped CNTs has been achieved by this modified spray pyrolysis method. By employing the plasma assisted CVD/sputtering hybrid system, selective growth of single and few walled CNTs have been realized. The device has also been able to produce 2D carbon nanostructures of nanosheets and a hybrid of nanosheets suspended on vertical aligned CNTs. Based on the magnetron sputtering deposition method, carbon nanowalls have been synthesized without any catalyst addition. Morphology, microstructure, and vibration properties of the CBNs were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy.
Carbon nanomaterials, grown in high densities on conducting and semiconducting substrates, promise great potential in building various nanodevices with different electron conducting requirements. In addition, CBNs provide a very high surface area for the support of platinum particles for use in hydrogen fuel cell electrodes.
2011-02-07T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/83
https://ir.lib.uwo.ca/context/etd/article/1171/viewcontent/Ionescu_Mihnea_I_201102_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Carbon Based Nanomaterials
Carbon Nanotubes
Branched Nanotubes
Graphite Sheets
Nanowalls
Chemical Vapor Deposition
Materials Science and Engineering
Nanoscience and Nanotechnology
oai:ir.lib.uwo.ca:etd-1172
2011-11-16T19:24:48Z
publication:civil
publication:faculties
publication:etd
publication:civil-etd
The Behaviour of Cement Stabilized Clay At High Water Contents
Sasanian, Saeed
Artificial cementation of soft clays has been used for several years for different ground improvement projects. Although considerable work has been done to develop advanced machinery and techniques for the implementation of artificial cementation, less knowledge is available on the mechanisms involving the formation of the artificial structure and the resulting mechanical behaviour. The primary objectives of the present work were to investigate the formation of microstructure in artificially cemented material with Portland cement, find the relationships between cementitious bonding and clay mineralogy, and create constitutive frameworks for predicting the mechanical behaviour of cement-treated clays.
Qualitative and quantitative microstructural characterisation of reconstituted and cemented material has been performed using scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). The results confirmed the transformation of the void microstructure from a bimodal, dispersed material into a unimodal, flocculated material due to artificial cementation. The addition of cement was found to reduce the amount of macro-pores within the cemented material, resulting in a significant reduction in hydraulic conductivity.
A further parametric study was conducted on data obtained in the laboratory by the author combined with those found in the literature, to investigate the effect of clay mineralogy on artificial cementation. The results indicated the major influence of the activity of the clay, along with the cement and water content, on the results of the cement treatment. The observed variations in the mechanical behaviour with respect to mineralogy and the important effect of curing time have been explained in terms of the pozzolanic reactions, and the limitations of applying Abrams’ law to cement-admixed clays are discussed.
In addition, an experimental study has been conducted to investigate the yielding and stress-strain behaviour of artificially cemented Ottawa clay and to compare it with the behaviour of the same soil in its naturally structured state. The results indicate that although the natural clay exhibits a meta-stable structure, resulting in an abrupt post-yield loss of strength, the artificially cemented material undergoes a more gradual breakage of the cementitious bonds. This allows for the use of the critical state concept, along with a pseudo-normal compression line, to develop a constitutive model for the artificially cemented material.
2011-03-02T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/110
https://ir.lib.uwo.ca/context/etd/article/1172/viewcontent/Final_version_of_the_PhD_thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
reconstituted clay
artificially cemented clay
microstructure
inter-aggregate
intra-aggregate
activity; cement-water ratio; hydration reactions
pozzolanic reactions
critical state
yield locus
elastic and plastic deformations
stiffness
Civil and Environmental Engineering
Geotechnical Engineering
oai:ir.lib.uwo.ca:etd-1173
2011-02-22T15:14:33Z
publication:electrical
publication:electrical-etd
publication:faculties
publication:etd
Advances In Internal Model Principle Control Theory
Lu, Jin
In this thesis, two advanced implementations of the internal model principle (IMP) are presented. The first is the identification of exponentially damped sinusoidal (EDS) signals with unknown parameters which are widely used to model audio signals. This application is developed in discrete time as a signal processing problem. An IMP based adaptive algorithm is developed for estimating two EDS parameters, the damping factor and frequency. The stability and convergence of this adaptive algorithm is analyzed based on a discrete time two time scale averaging theory. Simulation results demonstrate the identification performance of the proposed algorithm and verify its stability.
The second advanced implementation of the IMP control theory is the rejection of disturbances consisting of both predictable and unpredictable components. An IMP controller is used for rejecting predictable disturbances. But the phase lag introduced by the IMP controller limits the rejection capability of the wideband disturbance controller, which is used for attenuating unpredictable disturbance, such as white noise. A combination of open and closed-loop control strategy is presented. In the closed-loop mode, both controllers are active. Once the tracking error is insignificant, the input to the IMP controller is disconnected while its output control action is maintained. In the open loop mode, the wideband disturbance controller is made more aggressive for attenuating white noise. Depending on the level of the tracking error, the input to the IMP controller is connected intermittently. Thus the system switches between open and closed-loop modes.
A state feedback controller is designed as the wideband disturbance controller in this application. Two types of predictable disturbances are considered, constant and periodic. For a constant disturbance, an integral controller, the simplest IMP controller, is used. For a periodic disturbance with unknown frequencies, adaptive IMP controllers are used to estimate the frequencies before cancelling the disturbances. An extended multiple Lyapunov functions (MLF) theorem is developed for the stability analysis of this intermittent control strategy. Simulation results justify the optimal rejection performance of this switched control by comparing with two other traditional controllers.
2011-02-11T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/90
https://ir.lib.uwo.ca/context/etd/article/1173/viewcontent/Jin_Lu_201102_PhD_Thesis.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
Internal model principle
exponentially damped sinusoid
intermittent control
disturbance cancellation
switched systems
multiple Lyapunov functions
Controls and Control Theory
oai:ir.lib.uwo.ca:etd-1174
2011-04-23T18:50:19Z
publication:psychology-etd
publication:psychology
publication:faculties
publication:etd
Does Anyone Really Like Horror Movies? Personality and Automatic Affective Reactions to Frightening Films
Battista, Michael E
I sought to explain why many people willingly expose themselves to apparently unpleasant media, such as horror movies. Participants (N = 133) completed a modified version of the Affect Misattribution Procedure (AMP; Payne et al., 2005), which assessed initial affective reactions to screenshots from movies that were either frightening or neutral. The time between exposure to the screenshots and assessment of affect was either short (100 ms) or long (1000 ms). Explicit attitudes about the movies and about the horror genre were also assessed, in addition to the following personality variables: The Big Five, Machiavellianism (from the Supernumerary Personality Inventory), Sensation Seeking, and Psychopathy. There was little evidence for a direct connection between implicit reactions and explicit attitudes, but I found overall support for an aftermath- based model of horror enjoyment, in which affect gets increasingly positive after a horrific stimulus has been removed from the screen. However, this relief-like pattern was moderated by Agreeableness and Sensation Seeking. Personality correlates of horror liking (both explicit and implicit) were examined. Furthermore, gender differences supported a gender socialization theory of reactions to frightening media. Theoretical implications and practical applications are discussed.
2011-02-16T08:00:00Z
text
application/pdf
https://ir.lib.uwo.ca/etd/116
https://ir.lib.uwo.ca/context/etd/article/1174/viewcontent/Battista_Michael_E_201106_PhD_thesis_V4.pdf
Electronic Thesis and Dissertation Repository
English
Scholarship@Western
attitudes
implicit attitudes
affect
horror
media
personality
Personality and Social Contexts
686929/oai_dc/100//