VictorJuiz/thesis huggingface dataset:
Nonlinear Stability Analysis and Shimmy Mitigation of Aircraft Nose Landing Gears
Keywords: design
dynamics
landing gears
nonlinear analysis
nonlinear vibrations
shimmy

Landing gear stability is crucial for aviation safety. Yet, it can be challenged through emergence of self-induced rotational-lateral oscillations designated as shimmy. The challenge of shimmy is more common in nose landing gears and is mostly addressed by addition of shimmy dampers. This presents two challenges and opportunities for improvement that are addressed in this thesis. Firstly, the gap between shimmy prediction from numerical simulations and physical tests can be narrowed by including more of the nonlinear phenomena. In this work, a representative nose landing gear model is constructed by accounting for chief degrees of freedom and major nonlinearities. Specifically, Coulomb friction in the shock absorber is modeled as a state-dependent resistive torque which varies with shock absorber compression and shimmy velocity. The effect of torque link freeplay nonlinearity is also investigated simultaneously with the Coulomb friction using the representative nonlinear model. Time domain numerical solution based on multi-body dynamics approach is used to obtain stability plots in a representative parameter space. Qualitative and quantitative effects of these nonlinearities are discussed. Coulomb friction is found to increase stability and switch the shimmy mode from rotational to lateral while freeplay diminishes stability and leads to more severe rotational vibrations. The second challenge addressed deals with shimmy damper performance analysis and designing an improved shimmy damper. Using the representative nose landing gear dynamic model and a generic damper sub-model, global trends offered by passive shimmy dampers are depicted and explained. Based on these trends and analyzing existing shimmy dampers, a novel shimmy damper concept is proposed which integrates the damping elements into the design of the torque links, offering a multifunctional torque link system with symmetrical load distribution and simpler maintenance. Designated as Symmetric Torque Link Damper (STLD), this shimmy damper is studied parametrically and optimized for an existing nose landing gear as a proof of concept. Using topology optimization and iterative studies, a prototype of STLD is sized and fabricated for experimental characterization and validation. Along with the analysis, the experimental results confirm the stability benefits offered by this novel shimmy damper design.
An Exploration of Implicit Attitudes toward Indigenous Peoples in Canada and Managing Settler Biases through Mindfulness
Keywords: Cultural Safety
Healthcare
Implicit attitudes
Indigenous Peoples
Mindfulness
Racism

The consequences of colonization and racism continue to impact the lives of Indigenous Peoples in Canada, notably within the healthcare system. The two studies forming this dissertation turned the research lens onto Settler peoples in Canada. The overarching goals were to develop a tool that could be used to identify levels of implicit bias toward Indigenous Peoples, examine the relationships between mindfulness, self-compassion, emotions, and measures of racial/ethnic bias, and investigate differences in reactions, feelings of warmth toward Indigenous Peoples, and intentions for change associated with administering a brief mindfulness intervention after receiving implicit bias feedback. Study 1 developed the Indigenous Peoples in Canada Implicit Association Test (IPC-IAT), an adaptation of the well-known Implicit Association Test (IAT; Greenwald, McGee, Schwartz, 1998). Data was collected from 306 White self-identified individuals from the general Canadian population. Analyses identified moderate levels of implicit negative bias toward Indigenous Peoples in Canada and found that the IPC-IAT showed expected relationships to other measures and established correlates of racial/ethnic bias. Few significant correlations between measures of racial/ethnic bias, mindfulness, self-compassion, and emotions were revealed. Study 2 explored the acceptability of the IPC-IAT and whether a brief self-compassion intervention administered after the IPC-IAT lessened negative reactions, improved feelings of warmth toward Indigenous Peoples, and led to greater intentions for change. Both healthcare professionals (n = 13) and those from the general population found the IPC-IAT to be an acceptable component of an assessment of, and brief intervention for, racial/ethnic biases. A group of 95 individuals randomly assigned to receive the brief self-compassion intervention was compared to a control group (n = 89) that completed unrelated reading and writing tasks following IPC-IAT feedback. Intervention did not promote the expected changes in state-mindfulness and those assigned to the intervention group did not have fewer negative reactions, greater feelings of warmth, or more intentions for change compared to the control group. Post-exploratory analyses showed that positive reactions were correlated with greater feelings of warmth and intentions for change. Implications and limitations of both studies are discussed and future directions for addressing Indigenous-specific racism are considered.
Integrin-targeted Polymer-lipid Nanoparticles Encapsulating Synergistic Drug Combinations for Therapy of Triple Negative Breast Cancer Metastasis
Keywords: breast cancer
integrin
metastasis
nanoparticle
RGD
synergistic drug combination

Triple-negative breast cancer (TNBC), an aggressive subtype, is associated with a high risk of distal metastases which are the major cause of death in breast cancer patients. The most common sites of metastases are lungs (40%) and brain (30%). Additionally, the lack of effective targeted therapies also contributes to the poor prognosis of TNBC patients. Based on our previous research on polymer-lipid hybrid nanoparticle (PLN) systems delivering combination drugs and Arg-Gly-Asp (RGD) peptide-conjugated nanoparticles targeting TNBC, this thesis aims to develop and evaluate three integrin-targeted PLN formulations encapsulating synergistic drug combinations for treatment of 1) lung metastases and 2) brain metastases as well as 3) for prevention of spontaneous metastases of TNBC. The first PLN formulation, conjugated with RGD and co-loaded with synergistic doxorubicin (DOX) and mitomycin C (MMC), significantly inhibited the progression of lung metastases of TNBC and prolonged the host survival compared to non-targeted drug-loaded PLN and free drug combinations in a lung metastasis murine model. The enhanced efficacy is attributable to the dual-targetability of the RGD-conjugated system to the αv integrin-overexpressing tumor vasculature and tumor cells. The second formulation, a polysorbate 80-containing, internalizing RGD (iRGD)-conjugated terpolymer-lipid hybrid nanoparticle (TPLN) system carrying a synergistic DOX and MMC combination, was designed to first undergo synchronized blood-brain barrier (BBB)-crossing and then actively target TNBC cells and tumor-associated macropahges in micro-lesions of brain metastases. The TPLN drug delivery system significantly reduced brain metastatic burden and increased host median survival compared to a TPLN system without iRGD conjugation or free DOX/MMC treatments in a brain metastasis murine model. The third integrin-targeted formulation, an iRGD-modified DOX and oligomeric hyaluronic acid (oHA) co-loaded PLN system effectively prevented spontaneous metastases to lymph nodes and lungs ascribable to the anti-migration/invasion effect of nanoparticle-delivered oHA and their inhibition of a pro-metastasis signaling pathway and biomarkers. Simultaneously, the system enhanced apoptosis and demonstrated strong growth inhibition in a primary breast tumor via the synergistic cytotoxic action of the co-encapsulated DOX and oHA. The research finding of integrin-targeted PLN systems delivering synergistic drug combinations presents promising multi-targeted drug delivery strategies for the treatment of integrin-overexpressing lung metastases and brain metastases of TNBC as well as their metastatic prevention.
A Framework for Informal Creativity
Keywords: Creativity
Governance
Innovation
Intellectual Property
Law and Social Norms

This thesis explores a puzzling phenomenon that defies common intellectual property (IP) wisdom: creative industries that produce high volumes of creativity, without the use of IP law. It addresses two key questions: What are the factors that sustain high levels of creative production and effectual social order in these creative industries? and what does this tell us about IP law and theory? It proposes an explanatory framework that accounts for successful creative production and social order, how obstacles are overcome, and how different actors contribute to creative production, thus developing new taxonomies and models for IP and ‘order without law’ scholarship. This thesis breaks new methodological ground by systematically synthesising and analysing multiple studies of such creative industries in conjunction, using legal, sociological, and economics scholarship, as well as narratives in popular culture such as social media and books. Based on a set of original questions, it locates different variables that affect creative production and social order. From these, it refines a set of five common features that explain the success of these creative industries: community – a distinct, organised group with shared goals, ethos, or interests; effective information networks; clear norms with effective compliance mechanisms and means for dispute resolution; law or legal institutions play an important role; and, that there are institutions for giving credit and attribution. Looking at these common features, this thesis also exposes that external players, such as suppliers, reviewers, bloggers, consumers, and fans, have a key role, alongside creators, in sustaining creative production and social order. It demonstrates the extent and magnitude of external players’ impact, by illustrating their roles in all of the five common features. For example, they monitor and enforce norms, disseminate information, and provide essential infrastructure for social interaction. Reflecting on this explanatory framework – the set of common features sustained by creators and various external players – I highlight several important implications: suggesting new taxonomies for self-governance by adding flexibility to current definitions of certain social institutions; a synergetic approach to the relationship between law and social norms; adding certain exceptions to IP law; and giving wider consideration to attribution rights.
Students at the Margins: Contesting the Ruling Relations of Student Codes of Conduct
Keywords: Black Indigenous anti-racist feminism
freedom of expression
institutional ethnography
student activism
student movement
university corporatization

This dissertation draws on Dorothy Smith’s (1987, 1990a, 1999, 2005) method of institutional ethnography (IE) to critically examine recent revisions to student codes of conduct in Ontario’s universities through an institutional ethnographic study of York University in the province of Ontario, Canada. Starting from the standpoint of marginalized student activists, my empirical research shows how these policy changes have been informed by a new rights and responsibilities discourse designed to reduce political conflict on campuses. Couched in terms of promoting student inclusion, fairness, and campus safety, this discourse works with managerial technologies to increase the surveillance and regulation of marginalized student political advocacy work. I describe how these changes to student codes of conduct obfuscate the ways in which client-service sector relations operate to depoliticize student dissent and silence marginalized student voices, especially voices that raise controversial issues of oppression and challenge the status quo. By examining the textually mediated forms of managerial discourses that university administrator’s use to guide, monitor, and discipline potential student non-academic conduct, I further show how marginalized student political advocacy work that addresses diverse issues of race, class, gender, sexuality, ability, and indigeneity are increasingly socially organized to uphold a depoliticized regime of corporate social relations that are operating in Canadian universities today. In examining informant interviews, I also discuss the contradictory and uneven ways that marginalized student advocates respond to these discourses and examine the effects of this new regime on the social organization and social relations of marginalized students’ political advocacy work.
Enhanced Rainbow Trapping in Width-graded Chirped MIM Nano-gratings for High-sensitivity Multiwavelength Bio-molecular Detection
Keywords: Nanograting
Plasmonics
Rainbow Trapping
Single Molecule Sensing
Surface Enhanced Raman Scattering
Surface Plasmon Polariton

In this dissertation, we undertake theoretical and experimental investigations of plasmonic width-graded nano-gratings vis-à-vis a nanophotonic sensing platform amenable for integration within a Lab-on-a-Chip Point-of-Care system. Theoretically, we delineate the four principal surface plasmon polariton coupling and its interaction mechanisms in subwavelength gratings, thus showing their significant role in shaping the optical response of a plasmonic grating. Within the framework of width-graded metal-insulator-metal (MIM) nano-gratings, mode confinement and waveguiding result in multiwavelength light localization provided conditions for adiabatic mode transformation are satisfied. Maximal field enhancement is attained by ensuring adiabatic mode transformation among the grooves through parametric optimization of groove width and groove-to-groove separation. Experimentally, we fabricate nano-gratings using electron beam lithography with a minimum groove width of 40 nm at the center of the grating. Upon illumination, maximal enhanced electromagnetic field is generated at the center because of plasmonic light trapping and waveguiding; this is observed through near-field scanning optical microscopy, Raman spectroscopy, fluorescence spectroscopy, and corroborated via numerical simulations. Further, we compare near-field optical response of two types of plasmonic width-graded nano-gratings: Silicon-Metal-Insulator-Metal-Silicon (SMIMS) nano-gratings and MIM nano-gratings in rectangular and bull’s eye geometries. Through integration of the SMIMS width-graded nano-grating within a microfluidic device, we demonstrate that SERS enhancement factors of 106–107 are possible for detection of 1mM aqueous phospholipid solution at 532 nm, 638 nm, and 785 nm laser illumination. The highly intense multiwavelength characteristic of these nano-grating facilitates access to weak Raman modes. We employ MIM width-graded nano-gratings as a SERS platform for the detection of propylene glycol. We show detection down to the attomolar concentration level for this small molecule at three wavelengths of 532 nm, 638 nm, and 785 nm. The robust multiwavelength SERS measurements enable us to obtain quantitative analysis for various vibrational modes at concentration levels spanning 15 orders of magnitude from millimole to attomole per litre. These sub-wavelength width-graded nano-gratings offer rainbow trapping and highly robust plasmonic field enhancement which can be tuned to cover broad wavelength ranges within the visible and near-infrared regimes. These nano-gratings provide a viable platform for static and dynamic characterization of low concentration species.
Evaluation of Cathepsin-K Activation by Endotoxin and the Effect of Specific Protease Inhibitors on Dentin Matrix
Keywords: Cysteine cathepsins
Endotoxins
MMPs
Restorative Dentistry

Host-derived proteases have been shown to be associated with degradation of imperfectly impregnated collagen at the dentin-resin interface. Cathepsins (CTs) have been recently detected in human dentin. CTs can be activated in mild acidic environments that may further activate matrix-metalloproteinases (MMPs). Therapeutic strategies to inhibit dentinal protease activity by MMPs and CTs and subsequently prevent matrix degradation have been gaining importance recently. Chlorhexidine (CHX) (Broad-spectrum antiproteolytic) have been mostly studied. The study aims to evaluate specific CT-K inhibitor in dentin collagen degradation with/without endotoxins. This study specifically aims to (1) Develop demineralized dentin model to assess effectiveness of CT inhibitors, (2) Evaluate effect of specific CT-K inhibitor on dentin collagen properties (3) Evaluate effect of specific CT-K inhibitor on dentin collagen treated with endotoxins. To develop study model, dentin disks with 0.5mm thickness prepared from human molars were completely demineralized in 10%H3PO4. Pulverized dentin powder challenged in 1mL lactic acid (LA) (0.1M, pH5.5). Aliquots of dentin powder were then immersed in 1mL of CHX, E-64 or Odanacatib (ODN) (specific CT-K inhibitor). To evaluate endotoxins effect, dentin powder obtained were challenged with 500EU LPS. Degradation of dentin collagen was determined by sub-product release of C- and N-telopeptides in incubation media. Dentin matrix properties were measured by gravimetric change and ultimate tensile strength. Dentin microstructure was analyzed by scanning electron microscopy (SEM) or atomic force microscopy (AFM). This study showed that LA can activate endogenous CT-K in dentin, this model has potential application for further investigations on activity and possible inhibitors of CT-K in dentin. Specific CTs inhibitors (E-64, ODN) significantly inhibited CT-K activity. Therefore, Dentin therapies targeting enzymes (e.g. CT-K) by specific inhibitors may provide superior pharmacokinetics and optimum efficacy due to precise protein binding, consequently limiting collagen degradation directly or indirectly by enzyme-related pathways. CT-K activity increased within an infected demineralized dentin model. Increased CT-K activity was verified not only by release of C-telopeptides, but for the first time by the increase release of N-telopeptides of type I collagen. The findings from this study suggests that specific CT-K inhibitor (ODN) has the potential to be used in restorative dentistry.
Allah’s Caliph and Christ’s Apostle: The Early Abbasid Rulers in Syriac and Syro-Arabic Sources
Keywords: Abbasid Caliphate History
Christian-Muslim Relations
Early Medieval Islamic History
Middle Eastern (Syriac) Christianity
Syriac Historiography
Syriac Language Literature

This dissertation examines narratives and portrayals of early Abbasid rulers (750-861 CE) in Medieval Syriac and Syro-Arabic Christian sources. It is concerned with how the available sources depicted the caliphate and caliphs. It investigates and sheds light on the caliphate’s socio-economic and religio-political policies and measures, the conditions and experiences of the Christian communities within the Islamic milieu, and the Christian-Muslim relations at the highest echelons of the society. Further, the dissertation examines and sheds light on the sources and their authors who offered a plethora of rich historical information and colourful literary images of the Muslim rulers. It investigates the historicity of these accounts and portrayals, contrasting them with those found in Medieval Islamic sources. It strives to discern and bring to light the historical and literary reasons, motives and functions of these accounts and depictions. Driven by such an agenda, this project deals first with the historical information provided in these sources on Islamic history, Christian history, and Christian-Muslim Relations. It undertakes this task through examining the role and impact of early Abbasid rulers in four themes in its first four chapters: First, Christians’ economic, social and religious conditions and experiences; Second, Christian ecclesiastical affairs and status; Third, Christian-Muslim interreligious dialogues; Fourth, early Abbasid internal and external political history. Then, the dissertation turns its attention to investigate Syriac and Syro-Arabic authors in the fifth and final chapter. This dissertation argues that Christian narratives and depictions of Muslim caliphs are rich literary treasures to the history of the early Abbasid milieu. It asserts that the Christian sources are invaluable for what they add to the historical picture and reveal about their authors who often were contemporary eyewitnesses of events. Medieval Christian sources offer alterative and additional evidence and accounts from chronologically and sometimes geographically close proximity authors, which often can revise, enrich and/or solidify historical pictures drawn previously only from Medieval Islamic sources.
Criminalization and Care: The Limits of a Public Health Approach to Addressing Drug Use
Keywords: Criminalization
Drug Use
Harm Reduction
Medicalization
Overdose
Structural vulnerability

The attempt by public health programs to reduce harm from illicit drug use faces several barriers, particularly structural barriers stemming from the ongoing criminalization of drug use. The ways in which structural barriers impact the uptake and implementation of key harm reduction programs is an ongoing area of concern, particularly as Canada faces a devastating opioid overdose crisis. Using ethnographic observation and qualitative interviews, this dissertation examines a harm reduction intervention where the homes of people who use drugs become ‘satellite’ harm reduction programs – the Satellite Sites. This program uses well-known community members as harm reduction workers to provide harm reduction education and equipment directly in the community settings where people gather to buy, use, and sell drugs. The Satellite Sites straddle two worlds: they are sites of illicit and stigmatized activities, while also being sites of public health intervention. Satellite Sites are partially medicalized due to their association with the community health centre running the program. However, the continued criminalization of drug possession and distribution negatively impacts the uptake and effectiveness of public health recommendations within the Satellite Sites. Overdose education and naloxone distribution campaigns provide an example of how criminalization negatively impacts on uptake of public health recommendations. These campaigns aim to prevent morbidity and mortality from opioid overdose, and findings show that naloxone access is lifesaving. However, these programs may inadvertently exacerbate structural vulnerabilities among people who use drugs, including vulnerability to housing loss and negative emotional impacts from responding to multiple overdoses. This dissertation also explores practices of care among a criminalized group: people who sell drugs. The Satellite Site program employs people who sometimes sell drugs as harm reduction workers, rendering their practices of care visible. The integration of people who sell drugs into harm reduction programming remains underexplored, and may hold promise in addressing high overdose death rates. While the Satellite Sites extend harm reduction into the spaces in the community where people gather to use drugs, criminalization exacerbates existing structural vulnerabilities among people who use drugs, and impedes the attempt of public health programming to intervene to reduce drug-related harms.