VictorJuiz/thesis huggingface dataset:
Compact Antennas and Superlenses Using Transmission-line Metamaterials
Keywords: Antennas
Metamaterials

One goal of this thesis is to address several challenging compact antenna design issues by using transmission-line metamaterials. In particular, we demonstrate the design of a compact antenna with an extended bandwidth, multiband/multifunction compact/small antennas, and mutual-coupling reduction for two closely-spaced small antennas. The proposed compact transmission-line metamaterial antenna employs the concept of zeroth- index resonance and a wideband characteristic is enabled by detuning the resonance of each constituent metamaterial unit cell at a slightly different frequency, thus creating a multi-resonant return-loss passband. Furthermore, a single-cell transmission-line metamaterial loading scheme is applied to regular printed monopole antennas in order to introduce additional resonances at the low band and create multiband small antennas that meet the specifications for WiFi and WiMAX applications. Lastly, a simple ap- proach for reducing the mutual coupling in two closely-spaced small antennas is also presented, based on the idea of self-cancelation of the induced currents. The other important goal of this thesis is to develop volumetric negative-refractive- index transmission-line (NRI-TL) metamaterials. A volumetric NRI-TL slab is created by stacking 2D NRI transmission-line grids in the shunt-node configuration. This is done in a simple manner through images induced in a parallel-plate environment. Additional vias are strategically placed to suppress the parasitic parallel-plate mode. Moreover, multiconductor transmission-line theory is used to model the volumetric metamaterial slab. A fully-printed volumetric Veselago-Pendry transmission-line lens is designed and matched to free space. Using this proposed lens, it has been experimentally verified that the diffraction limit can be overcome.
Development and Use of Polarized Light Methods to Assess Structure and Composition of Biological Tissue
Keywords: Polarized Light
Tissue

The use of polarized light for characterization of biological tissues has received increased attention in recent years due to the wealth of information available in the interactions of polarized light with tissue and the noninvasive nature of optical radiation. While the depolarizing effects of multiple scattering complicate the use of polarimetry in tissue, many biological constituents affect the polarization of light such as collagen, muscle fibers, and glucose. Thus, if the effects of scattering can be accounted for⎯or utilized in the analysis⎯polarized light can potentially be used as a probe of tissue status. This thesis presents advancements in the techniques for the simulation of polarized light in tissue-simulating media, and explores two biomedical applications. Previous Monte Carlo models for simulation of polarized light propagation in tissue-simulating media do not include the effects of birefringence and optical activity, two polarizing effects of useful diagnostic potential. To overcome this limitation, our model was extended to include both these effects simultaneously, and then experimentally validated using a novel polarization phantom system. The use of polarized light for characterization of the myocardium, and specifically towards monitoring stem cell regenerative treatments of myocardial infarction, was investigated experimentally as a novel application for polarimetry. The potential for this technique is based on the changes in myocardial structure that occur with infarction and subsequent regeneration, and the associated changes in tissue birefringence. The use of polarized light for noninvasive tissue analyte monitoring, particularly glucose, was also investigated based on the optical activity exhibited by many tissue analytes due to their chiral structure. In this study, a novel combined optical polarization and intensity approach was developed and tested on Monte Carlo simulated data. The studies presented in thesis introduce new methods for polarization simulation and analysis in biological tissue and demonstrate potential for polarimetry in monitoring myocardial regeneration and noninvasive measurements of tissue analytes.
Role of R-spondin-1 in the Regulation of β-cell Behaviour
Keywords: R-spondin-1
β-cell
Proliferation
Apoptosis
Insulin secretion
Islet

R-spondin-1 (Rspo1) is an intestinal growth factor known to exert its effects through activation of the canonical Wnt (cWnt) pathway, but its function in the β-cell had not been explored. In Chapter 2, Rspo1 mRNA was found to be expressed in murine islets and the murine MIN6 and βTC β-cell lines, and Rspo1 protein was detected in MIN6 β-cells. Rspo1 activated cWnt signaling and induced insulin mRNA expression in MIN6 β-cells. Analysis of MIN6 and mouse β-cell proliferation revealed that Rspo1 stimulated cell growth and significantly abolished cytokine-induced cellular apoptosis. Rspo1 also stimulated insulin secretion in a glucose-independent fashion. Chapter 2 further demonstrated that the glucagon-like peptide-1 receptor agonist, exendin-4 (EX4), stimulated Rspo1 mRNA transcript levels in MIN6 cells in a glucose-, time-, dose- and PI3-kinase-dependent fashion. Together, these studies demonstrate that Rspo1 is a novel β-cell growth factor and insulin secretagogue that is regulated by EX4. In Chapter 3, the role of Rspo1 in β-cells in vivo was explored using Rspo1 knock-out (Rspo1-/-) mice. Rspo1-/- mice had normal fasting glycemia but an improved glycemic control after an oral glucose challenge compared to Rspo1+/+ mice, with no difference in insulin sensitivity but an enhanced insulin response over 30 min; glucagon responses were normal. Rspo1 deficiency also resulted in an increase in β-cell mass in association with an increase in Ki67-positive β-cells, a marker of proliferation, relative to Rspo1+/+ mice. Rspo1-/- pancreatic tissues also demonstrated a significant increase in the number of insulin-positive ductal cells, suggestive of β-cell neogenesis. Rspo1-/- islets displayed no changes in glucose-induced insulin secretion but showed a complete absence of glucose-induced suppression glucagon secretion. Treatment of Rspo1-/- mice for 2 wk with EX4 resulted in a similar glycemic profile to EX4-treated Rspo1+/+ mice after an oral glucose challenge, with no changes in insulin sensitivity. Interestingly, EX4 administration to Rspo1-/- normalized β-cell mass to a level comparable to that in Rspo1+/+ mice. Although further studies are required, the findings in this thesis reveal a novel role for Rspo1 as a regulator of β-cell behaviour in vivo, and suggest novel roles for Rspo1 in both a- and ductal-cells.
Being-doing-becoming Manly Men: A Bourdieusian Exploration of the Construction of Masculine Identities and Sexual Practices of Young Men
Keywords: masculinities
Bourdieu
homosociality
sexual practices
young men
heterosexual
Toronto, Canada

Dominant discourses on youth sexual health construct young people as at-risk subjects who engage in risky behaviours due to ignorance or poor decision-making. This dissertation challenges the prevailing assumption embedded in these discourses that young people’s sexual behaviours are based on individual rational choices. Drawing on Pierre Bourdieu’s theory of practice and R. W. Connell’s notion of hegemonic masculinity, this dissertation uses an interpretive approach to analyze the narratives and resonant texts of 24 young men in Toronto. It explores how young men construct and perform their masculine identities in the context of their socio-spatial environment; it also examines the strategies that young men use to compete for cultural capital and dominant positions in the homosocial and (hetero)erotic fields. The analysis yields a number of findings. First, it shows that gender identity is a state of being-doing-becoming. Guided by their gender-class-race habituses, young men engage in an unceasing process of defining, affirming, declaring, and validating not only their sense of who they are (self-identity) and where they belong (collective identity), but also the boundary that differentiates the ‘Self’ from the ‘Other’. Second, there is a dialectical relationship between the young men’s masculine habituses and their sexual practices. While all the young men engaged in hegemonic masculine practices to gain ‘respect’ from their peers, their practices varied according to their classes and ethnoracial backgrounds. At the same time, their (hetero)erotic practices are intricately intertwined with their homosocial practices, whereby the intra-group masculine expectations coupled with the broad hegemonic masculine discourses assert significant influences on their interactions with both young women and other young men. Finally, hetero-guy-talk constitutes an important everyday social interaction in which young men actively engage in the (re)production and/or resistance of hegemonic masculine discourses and practices. These results suggest that effective sexual health promotion (SHP) must go beyond the focus on individual sexual behaviours to address the historical, cultural, economic, and political contexts that shape the collective sexual health practices of young men. Furthermore, it may be useful to explore ‘hetero-guy-talk’ as an important ‘third’ space where young men are invited to interrogate and resist misogynist, masculinist, and homophobic practices and be supported to engage in humanizing sexual practices.
Spectroscopic Studies of CdSe Nanocrystal Fine Structure and Electronic Coherences in Cryptophyte Algae
Keywords: physical chemistry
non-linear spectroscopy

The studies presented in this thesis explore energy transfer and relaxation in excitonic systems using two types of third-order non-linear spectroscopy, transient grating (TG) and two-dimensional photon echo (2DPE). Two major excitonic systems are studied, colloidal CdSe nanocrystals and a photosynthetic system, the light harvesting antenna protein PE545 isolated from cryptophyte algae Rhodomonas CS24. The inhomogeneous broadening present in colloidal samples has long been an obstacle to the study of the fine structure of CdSe nanocrystals. This thesis will present two studies, each using a different spectroscopy to overcome this problem and gain insight into the fine structure of the ground state exciton and biexciton. In both cases, polarization dependent measurements are used to isolate particular types of pathways through the fine structure. Polarization dependent TG measurements and a detailed kinetic model have allowed us to identify major pathways for excitonic relaxation within the fine structure of the ground state exciton, despite the inhomogeneous broadening present in the sample. Conclusions from this work include an analogy to the internal conversion and intersystem crossing transitions in molecules, concepts which are familiar to most chemists. Polarization dependent 2DPE experiments and a simulation of the resulting spectra have allowed for the direct observation of the ground state biexcitonic fine structure. The high density of states in the spectral region of the biexciton obscures these states in most spectroscopies, but the combination of polarization dependence and the use of a two-dimensional technique have revealed these elusive fine structure states. This 2DPE technique is then used to inspect light harvesting antenna protein PE545, a system of eight chromophores covalently bonded to a protein scaffold. The 2DPE measurement is capable of identifying oscillatory components of the signal which are signatures of coherent energy sharing. Using this technique, coherent energy sharing is observed throughout the spectrum of the protein at ambient temperatures, and control experiments suggest that the observed coherences are electronic, not vibrational. A short study is also presented which compares the utility of two approximations for calculations of electronic coupling and energy transfer in elongated excitonic systems.
Research Use and the Impact in Secondary Schools
Keywords: research use
knowledge mobilization

The purpose of this research was to learn more about the ways that school and system leaders, access, engage with, share, and use research in their work. This research began with a framework developed by Levin (2004) and similar framing by Nutley et al (2007) suggesting that knowledge and use of research in schools depends on characteristics of the research itself (such as accessibility and perceived quality), characteristics of the educators and context (research background, interest level, supporting processes and structures) and the role of third party facilitators (such as professional media, experts, professional development providers) as distributors of knowledge. This study is meant to add to our understanding of the way research is taken up in secondary schools and districts by replicating and extending the recent work by Levin et al (2009) in a research study conducted with the Canadian Education Association (CEA) and the Ontario Institute for Studies in Education (OISE) entitled, “Research Use and its Impact in Secondary Education”. In general, educators, like other professionals, have relatively limited direct knowledge of current research and rely on versions of research findings that they encounter in their daily work or from colleagues (Levin et al, 2009). This study examined the processes and practices in place within secondary schools and across a district school board to determine the facilitators and barriers to research use. The study addressed the following research questions: 1. How do secondary school leaders access and use relevant research findings? 2. What are the main perceived barriers to the use of research by secondary school leaders? 3. In what ways does the school district support or hinder the use of research? These questions were designed to focus on the dynamics at the district level and the organizational capacity for knowledge mobilization. Data were collected through an online anonymous survey and semi-structured interviews. The online survey suggests that educators have a high regard for research in their professional practice, and that there is an array of opportunities for teachers and school administrators to engage with research. And, according to the respondents, the greatest challenge is finding the time to access the research. The findings also reveal that the although there is a high regard for research, research is generally not a priority in secondary schools and practice is based more on knowledge gained from colleagues or personal experience than from evidence-based research. The thesis concluded that there are many factors that both enable and hinder engagement with research and research use. Findings include the importance of culture and context of the school, the relationship between leaders’ actions and expectations and practice, relevancy of research to practice, the role of facilitation, the use of technology, and starting small to build a critical mass of teachers engaging with and using research in their practice.
A Randomized Controlled Trial of an Individualized Education Intervention for Symptom Management Following Total Knee Arthroplasty
Keywords: total knee arthroplasty
preoperative educaion
pain
nausea

Total knee arthroplasty (TKA) is a common surgical procedure for the treatment of patients with pain and immobility as a result of osteoarthritis or rheumatoid arthritis. Pain-related interference, pain and nausea are recovery-limiting in these patients in the immediate postoperative period. Preoperative educational interventions that include pain communication and management information have been shown to decrease pain in joint replacement patients (McDonald & Molony, 2004). This randomized controlled trial compared usual preoperative education to an individually delivered preoperative education program. Participants (N=143) were randomized to intervention or usual care groups during routine preadmission testing. The usual care group received the usual preoperative teaching. The treatment group received the usual care teaching, a booklet containing content specific to symptom management after TKA, an individual teaching session during the preadmission testing visit and a telephone follow-up support call during the week before surgery. The primary outcome for this study was pain-related interference with activity and was measured using the Brief Pain Inventory Interference subscale (BPI-I) (Cleeland et al., 1994) on postoperative day three. Secondary outcomes were pain, nausea and expected postoperative activity and were measured on postoperative days one, two and three. There were no differences between groups in any of the outcomes for this study. BPI-I total scores were 24.4±14.4 in the intervention group and 22.4±15.1 in the usual care group (P=0.5) on the third postoperative day. Overall results demonstrated that although TKA patients had severe postoperative pain and severe nausea, they received inadequate doses of analgesia and anti-emetics. Available evidenced based protocols and practices in the health care environment were not followed Individualizing education content was not sufficient to produce a change in postoperative symptoms for these patients. Further research involving the modification of environmental and system factors affecting the provision of symptom management interventions is warranted.
Boundless Explorations: Global Spaces and Travel in the Literature of William Wordsworth, Percy Shelley, and Mary Shelley
Keywords: Romanticism
Travel
William Wordsworth
Percy Shelley
Mary Shelley

This dissertation focuses on a Romanticism that was profoundly global in scope, and examines the boundary-crossing literary techniques of William Wordsworth, Percy Shelley and Mary Shelley. These authors saw identity as delimited by artificial borders, and we witness in their work competitions between local and global, immediate and infinite, home and away – all formulated in spatial terms. This thesis argues that by using motifs and philosophies associated with “borderless” global travel, these authors radically destabilized definitions of nature, history, and the home. Wordsworth and the Shelleys saw the act of travel as essentially cosmopolitan, and frequently depicted spaces outside of familiar boundaries as being rich in imaginative vitality. Their fiction and poetry abounds with examples of North American primitivism, radical modes of transportation, and unknown territories sought by passionate explorers. Importantly, they often used such examples of foreignness to rejuvenate familiar spaces and knowledge – these were individuals determined to retain a certain amount of local integrity, or connection with the reluctant minds who feared alien contexts. As such, they were each aware of the fragility of embedded minds, and the connection of these minds to bordered historical contexts. Aware of the dangers posed by uninhibited imaginative movements, they depicted travel as an artistically seductive activity. Their impulse as authors was thus to use global experiences as a tool of literary expression, while refraining from a total abandonment of local responsibility. This dissertation therefore argues that the imaginative experience of space in the Romantic period was profoundly split, tethered on the one hand to custom and familiarity, and on the other aspiring to boundless global freedoms.
Enabling Power Wheelchair Mobility with Long-term Care Home Residents with Cognitive Impairments
Keywords: older adult
nursing home
power mobility
wheelchair
long-term care home
cognitive impairment
mobility
dementia
safety
assistive technology
technology design

For older adults, functional independent mobility is essential to well-being. Many care home residents have physical and cognitive impairments and use wheelchairs. Residents with difficulty self-propelling manual wheelchairs may benefit from power mobility; however, those with cognitive impairments may be precluded because of the potential for injury. My research goals were to apply novel power wheelchair technology to enable safe, independent mobility. Technology was developed to examine the value and implications of power mobility for residents with restricted mobility and mild or moderate cognitive impairments. The first study tested a prototype anti-collision wheelchair with a contact sensor skirt. Six single subject studies were completed. Distances travelled in manual and anti-collision wheelchairs were compared. Observational and interview data were collected. Focus groups (37 staff) and interviews (18 staff, six other residents, one spouse) were performed. Three of six residents were able or had potential to operate the prototype. One resident chose to use it beyond the study, and his mobility and well-being improved. Case analyses showed factors limiting prototype acceptance. Residents were unsatisfied with the appearance and slow speed, and found the interface frustrating to operate because of inadequate feedback. Social isolation and reduced autonomy restricted independence achievable with technology. Socialization and affective benefits of mobility were demonstrated in one case where prototype use was continually assisted. Residents and staff supported the anti-collision concept. On observation, the prototype compensated for absent or delayed responses of residents to obstacles below sensors and decreased injury risk. However, full sensor coverage of the environment was needed. The second study addressed acceptance and interface usability issues. A simulated collision-avoidance wheelchair with a multimodal feedback interface was evaluated. The interface provided audio, visual and haptic feedback to guide navigation away from obstacles. Through observations, interviews and questionnaires, five residents evaluated the device. High device acceptance and usability were found. The device was easy to use and assisted with performance of indoor mobility goals. Further research is necessary before power wheelchairs with new features are available for users; however, these results could play a fundamental role in shaping technology development and mobility interventions for this neglected population.
Molecular and Functional Characterizations of Protein-protein Interactions in Central Nervous System
Keywords: dopamine receptor
glutamate
schizophrenia
depression
stroke
protein-protein interaction

Many pathological processes are associated with excessive neurotransmitter release that leads to the over-stimulation of post-synaptic neurotransmitter receptors. Examples include excessive activation of glutamate receptors in ischemic stroke and hyper-dopaminergic state in schizophrenia and drug addiction. Thus, it would seem that simply antagonizing the involved receptors should be able to correct the pathological condition. In some instances, this strategy has been somewhat effective, such as with the use of dopamine D2 receptor antagonists as antipsychotics in the treatment of positive symptoms of schizophrenia despite severe side effect. However, clinical application of drugs antagonizing glutamate receptor in the treatment of stoke, although attracting intensive research effort, has been restricted by serious side effects caused by suppressing postsynaptic responses that are needed for normal brain function. As a consequence, it is important to develop novel therapeutics aiming at specific targets with minimized side effects. Numerous studies have suggested that the pathophysiology of neuropsychiatric disorders, drug addictions and stroke involves multiple neurotransmitter receptor systems such as the dopamine and glutamate systems. The activation or inhibition of one receptor can have cross-functional effect that will be better understood by investigating the functional and structural relationship between receptor systems. Thus, the present study has focused on characterizing receptor-receptor interactions associated with dopamine receptors and glutamate receptors, and to elucidate the physiological and pathological consequence of altered receptor interactions in schizophrenia, depression and ischemic stroke.