Theses

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  • U.S. immigration and media bias surrounding the reporting of the Deferred Action for Childhood Arrivals (DACA) and Deferred Action for Parents of Americans and Lawful Permanent Residents (DAPA) immigration policies
    U.S. immigration and media bias surrounding the reporting of the Deferred Action for Childhood Arrivals (DACA) and Deferred Action for Parents of Americans and Lawful Permanent Residents (DAPA) immigration policies
    In 2012, President Barack Obama used his executive power to bypass Congress and unilaterally pass a controversial immigration policy called the Deferred Action for Childhood Arrivals (DACA) program and two years later its successor, the Deferred Action for Parents of Americans and Lawful Permanent Residents immigration policy. This MRP explores whether a media slant is salient in the editorial reporting surrounding these policies from two major U.S. political networks‐‐ The FOX News Channel (FOX) and the Cable News Network (CNN). Previous academic research (Iyengar & Hahn, 2009; Stroud, 2007) has indicated that CNN’s audience tends to be left-leaning favoring the Democratic Party, while rightleaning conservative Republicans tune into FOX for their political information (Gil de Zúñiga, Correa and Valenzuela, 2012). Keeping this in consideration, would the political networks tailor its digital editorial content to mimic its audiences’ political preference? Borrowing from Benson and Wood’s (2015) media frames surrounding undocumented immigration, a framing analysis and a textual content analysis were employed on the digital editorial content published by FOX and CNN from July 2014 and February 2015. The findings revealed that both networks published messaging aligned with its audiences’ political affiliation. The FOX News Channel emphasized how undocumented immigrants were a problem for society and authorities and published content which contained anti‐Democrat rhetoric and was acutely critical of President Obama. Conversely, the framing analysis revealed the Cable News Network was more likely to accentuate the problems for immigrants and defend President Obama and his unilateral exercises of constitutional powers.
    Uber vs. Pubic transit friend or foe? : an empirical study of ridership trends across Uber cities in the USA
    Uber vs. Pubic transit friend or foe? : an empirical study of ridership trends across Uber cities in the USA
    Uber is a disruptive transportation network company (TNC) that is affecting the way people move in cities. While its effects on the taxi industry are increasingly clear, little research has been conducted to study its effect on public transit ridership. This study uses descriptive statistics to establish demographic and socio-economic profiles of cities that Uber has targeted, and a quasi difference-in-difference analysis to explore Uber's effect on transit ridership levels in order to determine whether the service is acting as a complement or substitute to public transit. The results from this high-level study suggest that Uber my be more of a complement to transit over time, and in large dense regions with highly-educated, affluent, productive labour markets that already have very high transit ridership. Finally, recommendations informed by these findings are offered for transit agencies, policy makers, and municipal governments as they continue to determine how to regulate Uber and similar ride sourcing services
    Ultra-high frequency acoustic impedance imaging of cancer cells
    Ultra-high frequency acoustic impedance imaging of cancer cells
    Acoustic impedance maps of cells can be used to gain insight into its microstructures and physiological state. Information about the cell’s microstructures can be acquired from the acoustic impedance map fluctuations. The maps can also help identify the dominant scattering source in cells. Furthermore, the cell’s physiological state can be inferred from the average acoustic impedance values as many physiological changes in the cell are linked to the alteration in the mechanical properties. A method called acoustic impedance imaging has been used to measure the impedance of biological tissues. We used an acoustic microscope attached to a transducer with a center frequency of 375MHz to acquire acoustic impedance images of breast cancer cells. The generated images suggest that the nucleus has an acoustic impedance similar to the surrounding cytoplasm. Fluorescence and confocal microscopy were used to correlate acoustic impedance images with the cell microstructure (the nucleus). Simulation results demonstrate the system’s capability in detecting cell microstructures close to the substrate. The average acoustic impedance were used to differentiate between single-live, clustered-live and clustered-fixed cancer cells with a measured values of 1.60±0.01 MRayl, 1.61±0.02 MRayl and 1.55±0.02 MRayl respectively.
    Ultrasonic Spot Welding of Similar and Dissimilar Alloys for Automotive Applications
    Ultrasonic Spot Welding of Similar and Dissimilar Alloys for Automotive Applications
    Lightweighting has been regarded as a key strategy in the automotive industry to improve fuel efficiency and reduce anthropogenic environment-damaging, climate-changing, and costly emissions. Magnesium (Mg) alloys and Aluminum (Al) alloys are progressively more used in the transportation industries to reduce the weight of vehicles due to their high strength-to-weight ratio. Similarly, high strength low alloy (HSLA) steel is widely used to reduce gauge thickness and still maintain the same strength, and thereby reduce vehicle weight as well. A multi-material design of automotive structures and parts inevitably involve similar Mg-to-Mg and dissimilar Mg-to-Al, Al-to-steel, and Mg-to-Cu joints. Ultrasonic spot welding (USW) – a solid-state joining technique has recently received significant attention due to its higher efficiency in comparison with conventional fusion welding techniques. In this study, USW was used to generate similar joints of low rare-earth containing ZEK100 Mg alloy sheets and dissimilar ZEK100-to-Al5754, Al6111-to-HSLA steel, and Mg-to-Cu joints at different levels of welding energy or welding time. To optimize welding process and identify key factors affecting the weld strength, microstructural evolution, microhardness test, tensile lap shear test, fatigue test, and fracture analysis were performed on similar and dissimilar ultrasonic spot welded (USWed) joints. Dynamic recrystallization and grain coarsening were observed during Mg-to-Mg similar welding while rapid formation and growth of interface diffusion layer were observed in all dissimilar joints in the present study. It was due to significantly high strain rate (~103 s-1) and high temperature generated via frictional heating during USW. The interface diffusion layer was analyzed by SEM, EDS and XRD phase identification techniques which showed the presence of eutectic structure containing intermetallic compounds (IMCs). As a result, brittleness at the interface increased. The Zn coating in dissimilar USWed Al-to-steel joints eliminated the formation of brittle IMCs of Al-F, which were replaced by relatively ductile AlZn eutectic. The optimum welding energy or welding time during similar and dissimilar USW of lightweight alloys with a sheet thickness of 1-2 mm was in the range of ~500 J to 2000 J (~0.25 s to 1 s).
    Ultrasonic spot welding of lightweight alloys
    Ultrasonic spot welding of lightweight alloys
    Automotive and aerospace sectors have a pressing need for structural components that are lighter and stronger, aiming to improve energy efficiencies and reduce anthropogenic environment. Steel has already a wide variety of structural applications in the transportation industry due to its excellent properties. To further reduce CO2 emissions, lightweight magnesium (Mg) and aluminum (Al) alloys have increasingly been used in the vehicle fabrication due to their lower density, higher specific strength and stiffness, excellent size stability and process ability. The structural application of these alloys inevitably involves welding and joining of similar Mg-to-Mg and Al-to-Al, and dissimilar Mg-to-Al, Mg-to-steel and Al-to-steel. Resistance spot welding produces coarse grains, large defects and thick brittle intermetallic compounds (IMCs) in the weld metal. Alternative solid-state welding processes are being considered such as ultrasonic spot welding (USW), which produces coalescence through the simultaneous application of localized high-frequency vibratory energy and moderate clamping forces. In this study, USW was successfully carried out on similar Mg alloy and dissimilar Mg-to-Al, Mg-to-steel and Al-to-steel alloys. The overall objective of this work is to gain a better understanding of the dominant factors determining the joint performance, with particular emphasis on the microstructural evolution, crystallographic texture, micro-hardness, lap shear strength, fatigue resistance, fatigue life prediction model and fracture analysis of similar and dissimilar USWed joints. Overall, USWed Mg-to-Mg is stronger and more consistent in terms of weldability than the dissimilar USWed Mg-to-Al, Mg-to-steel and Al-to-steel. This was attributed to the large volume of thick brittle IMCs and significantly higher welds center hardness in dissimilar metals welding, which is the main cause of joint failure. The IMCs were confirmed by XRD, EDS and micro-hardness measurement tests.. Therefore, another objective of this study is to minimize the presence of brittle IMCs and engineer an acceptable intermetallic layer to produce sound joints between Mg-to-Al, Mg-to-steel and Al-to-steel. A third material (tin foil or zinc coating) was placed in-between the work pieces. With this procedure, the lap shear strength of the welded samples was increased. The detailed microstructural characterization and mechanical properties of welded joints with an interlayer are presented.
    Ultrasound mediated study of the electrokinetic effects in biological tissues and phantoms
    Ultrasound mediated study of the electrokinetic effects in biological tissues and phantoms
    Traditional ultrasound imaging monitors the backscattering properties of the object being imaged. Many hybrid imaging techniques such as photo-acoustic imaging, electro-acoustic imaging etc. have been developed to enhance the contrast in imaging. The main objective of this study was to monitor the electrically induced mechanical changes (EIMC) in ultrasound phantoms. Changes in time shifting of the signals and amplitude changes were investigated. Images were formed using a linear array ultrasound probe based on the time-delay estimates and the amplitude changes occurring in the tissue/phantom structure. EIMC in phantoms were found to depend on the applied electric field, gelling agent concentration, and salt concentration. The dependence of EIMC on the various parameters can be explained by the stiffness and fixed charge densities (FCD) of the phantoms. Knowledge gained from experimental results and its future extensions might culminate to form a method to image tissues based on their electrokinetic properties.
    Unbalanced Growth in Downtown Toronto: Maintaining Employment Uses in Toronto’s Downtown Core
    Unbalanced Growth in Downtown Toronto: Maintaining Employment Uses in Toronto’s Downtown Core
    Downtown Toronto is experiencing a significant increase in residential development. It attracts people and investment due to its mixture of land uses, transit, and vibrant urban environment. As an employment node, downtown plays an important role in the economic stability of the city. The King-Spadina case study is used to argue that unbalanced growth is occurring within a significant employment area and if left unmitigated, will seriously undermine the future employment growth opportunities that will be necessary to the continued success of the city. This study found that: 1) King- Spadina is a significant employment area, 2) King-Spadina is experiencing rapid population growth, 3) King-Spadina contains a significant amount of developable land, and 4) Residential development is displacing non-residential uses and consuming remaining soft sites at a significant pace. Recommendations are made to address the nature of growth happening in the area and to better protect long-term employment growth opportunities.
    Unbinding of contextual information: age differences and cultural effects
    Unbinding of contextual information: age differences and cultural effects
    Age and cultural effects on memory for complex pictures were examined under an unbinding condition. Young and older Canadians and Chinese were tested in Toronto and Beijing respectively. At encoding, participants viewed semantically congruent or incongruent pictures. At recognition, they were asked to recognize the objects and backgrounds of these pictures in isolation. The results revealed effects of both age and culture on recognition performance. Older adults recognized more objects than young adults, whereas Canadians were better than Chinese in background recognition. There was also a trend for Canadian older adults to recognize more objects and backgrounds than the other groups of participants. Age and cultural differences in memory under unbinding were possibly due to group differences in information binding during encoding. Finally, it was found that images from congruent pictures were better recognized than those from incongruent pictures, suggesting that semantic relatedness of information improves recognition under unbinding.
    Uncertainty and sensitivity analysis of GIS based continuous hydrological modelling
    Uncertainty and sensitivity analysis of GIS based continuous hydrological modelling
    The impact of uncertainty in spatial and a-spatial lumped model parameters for a continuous rainfall-runoff model is evaluated with respect to model prediction. The model uses a modified SCS-Curve Number approach that is loosely coupled with a geographic information system (GIS). The rainfall-runoff model uses daily average inputs and is calibrated using a daily average streamflow record for the study site. A Monte Carlo analysis is used to identify total model uncertainty while sensitivity analysis is applied using both a one-at-a-time (OAT) approach as well as through application of the extended Fourier Amplitude Sensitivity Technique (FAST). Conclusions suggest that the model is highly followed by model inputs and finally the Curve Number. While the model does not indicate a high degree of sensitivity to the Curve Number at present conditions, uncertainties in Curve Number estimation can potentially be the cause of high predictive errors when future development scenarios are evaluated.
    Uncloaking the anxiety behind professional dress.
    Uncloaking the anxiety behind professional dress.
    Graduating from university is one of life’s greatest milestones. Students expect their stress to subside upon graduation; however, the transition from student life to career track entails a new set of stressful circumstances, including how to dress professionally. Using a mixed methods approach, this study examined how recent graduates prepare their clothing for the professional workplace. Participants included 15 recent, professionally employed, postsecondary female graduates who completed a demographic questionnaire, a modified version of a standardized anxiety scale, and a phone interview. In order to determine best wardrobe practices, research included interviews with 5 fashion advisors. Although results revealed recent graduates did not experience any quantitatively significant anxiety, interview responses demonstrated both concern and uncertainty. This research provides insight into the lived experience of recent female graduates. Findings may be used to assist retailers, create guides, and develop workshops for new graduates entering the professional realm.