VictorJuiz/thesis huggingface dataset:
Disentangling the Roles of Pollination and Seed Dispersal on the Demography of a Tropical Understory Herb (Heliconia Tortuosa) in a Fragmented Landscape
Keywords: Climate change
Forest fragmentation
Forest loss
Heliconia tortuosa
Plant demography
Seed dispersal

Forest loss and fragmentation can affect plant populations directly by altering their demographic vital rates or indirectly by altering the movement behavior, abundance, and diversity of animals, which can affect pollen and seed flow. Most studies assess how forest loss and fragmentation affects plant population dynamics, pollination or seed dispersal independently, but little is known about how these processes are jointly affected for the same plant species. My thesis assesses the relative importance of forest loss and fragmentation for pollination, seed dispersal and plant demographic vital rates of the tropical understory herb Heliconia tortuosa Griggs. In Chapter 2, I found that, contrary to previous research on pollinators of H. tortuosa, the community of seed dispersers and Turdus grayi (one of the main seed dispersers of H. tortuosa) were not significantly affected by forest loss and fragmentation. Furthermore, I found high intraspecific variation in T. grayi habitat preference that was independent of patch size and proportion of forest in a 1 km radius. In Chapter 3, using a movement behavior model developed from radio-tracked individuals and an experimental assessment of seed passage time of H. tortuosa seeds by T. grayi individuals, I found that the probability of seeds landing in the same forest patch, in the matrix or in a new forest patch were mainly driven by habitat preference and patch size, while seed dispersal distance depended on step length. Lastly, in Chapter 4, demographic models obtained by following H. tortuosa individuals during 2013-2015 and 2015-2017 showed that pollination and seed dispersal had a low effect on population growth rate (λ), while survival, probability of reproduction and growth had larger effects. I found that the high mortality during 2013 - 2015 coincided with an unusually dry and warm wet season of 2015. Such unfavorable conditions are predicted to occur more frequently due to global warming. Overall, the results from my thesis suggest that, at least in the short term, inter-annual variation in meteorological conditions may have a stronger effect on H. tortuosa populations in the remaining forest habitat than direct and indirect effects of forest loss and fragmentation.
Medicinal Chemistry of Cannabis and Cannabinoids
Keywords: Analytical chemistry
Cannabinoids
Medical cannabis
Medicinal chemistry
Natural products
Synthetic chemistry

As societal attitudes towards cannabis evolve along with our understanding of the endocannabinoid system, medical cannabis is poised to re-enter the mainstream pharmacopeia, especially in North America. Presently, significant gaps in knowledge exist regarding the true chemical composition of medical cannabis as well as the pharmacodynamics of cannabinoids and cannabis extracts. As such, deconvoluting the chemical complexity of cannabis is essential for maximizing its therapeutic benefits and reducing adverse effects in the clinic. Accordingly, this thesis presents a comprehensive investigation of cannabis and cannabinoids at the pre-clinical level, drawing on core aspects of medicinal chemistry and applying developed techniques under large study settings. Through pilot experiments, extraction protocols for the optimal recovery of cannabinoids from different types of cannabis plant material were investigated and the diverse phytochemistry of cannabis was revealed through extensive chemical profiling, reiterating the need for standardization and consistency in therapeutic-grade cannabis extracts. Meanwhile, receptor profiling at CB1 and CB2 receptors confirmed the importance of decarboxylation for the optimal biological activity of cannabinoids and cannabis extracts, demonstrating the suitability of microwave-assisted extraction for producing pharmacologically active cannabis extracts. Following this, high-level chemoinformatic analyses of receptor responses versus cannabinoid concentrations of cannabis extracts generated meaningful prediction models for CB1R and CB2R agonism, predicting the cannabinoid receptor activities of individual phytocannabinoids with reasonable accuracy and revealing differences in cannabinoid receptor responses between pure cannabinoids and cannabis extracts. Finally, the total synthesis and characterization of two pharmaceutically novel cis stereoisomers of CBD was undertaken, resulting in the first unambiguous identification of cis-CBD species and the isolation of a hitherto undescribed cis-Δ9-THC species. Through this thesis, we report significant real-world evidence for the case that cannabis and cannabis extracts behave as complex mixtures of physiologically active molecules, whereby their effects on receptors vary significantly with chemotype and in turn reflects their chemical compositions. Several first-in-kind studies detailed in this thesis pave the way for further investigations of cannabinoids into their chemical structures, mechanism(s) of receptor binding, as well as synergistic and antagonistic effects during co-administration that together bring about the unique and medically important effects of cannabis.
Design and Investigation of Clean Energy Materials: From Stable Perovskites to Economical Catalysts for Oxygen Evolution Reaction
Keywords: Clean Energy
Green Hydrogen
Light Emitting Diodes
Oxygen evolution reaction
Perovskite
Solar Cell

As we strive to find sustainable and economical materials for green technologies, developing next-generation materials that are efficient, durable, and affordable is crucial. In this thesis, I present my research on improving phase and bandgap stability in lead halide perovskites and explore nanostructuring and non-precious metal alloys as a route to economical catalysts for oxygen evolution reaction (OER) in an acidic medium.In the first section of the thesis, I discuss my work on perovskites. I start with a density functional theory (DFT) study of a dual-dopant strategy to increase the structural stability of the black phase CsPbI3 (chapter 4). The DFT studies revealed the importance of stereoelectronic effects in dopant-induced phase stabilization and found that the combination of Ca and Mn-doped CsPbI3 is the most effective in stabilization. The synthesized dual-doped thin films retained the black phase for up to 16 days at 40-60% relative humidity, while the non-doped controls degraded on the order of seconds. I also used DFT to evaluate additive-based design principles to improve the bandgap stability of lead halide perovskites and aid in elucidating the structure of the smallest CdSe magic-sized cluster. My work reveals the ability of chelating agents to modulate the quantum-well distribution of CsPbBr3 to achieve bandgap stability. My computational work also highlighted the importance of surface coverage in mitigating the phase segregation that plagues mixed-halide perovskites. The results are supported via experimental validation, producing spectrally stable blue and red PeLEDs. In the second part of the thesis, I discuss my work on economical catalysts for OER in an acidic medium. I demonstrate the use of a metal-organic framework (MOF) structure to bolster the performance of Mn, a non-precious metal catalyst, in this application. The Mn MOF outperformed the classical bulk MnO2 under the same conditions. I also demonstrate the OER capability of a commercially available FeAlCr alloy (Kanthal) as an affordable catalyst in an acidic medium. I conclude by offering my perspective on the future directions of the outlined work, thereby delivering the desired efficient, durable, and affordable next-generation materials.
Foreign Relations? A Comparative Study of Foreign Policy and the Media in Britain and America, 1939-1941
Keywords: 1930s
Anglo-American comparison
Foreign policy
Media
World War II

How do a people experience their country’s foreign policy statements? This thesis explores the projection of publicly stated foreign policy and how it is constructed by the media. The existing research literature rarely covers in any depth this fundamental aspect of modern foreign policy. That said, analysing the relationships between governments, media, and peoples in a comparative context offers essential insights into the way these connections work. Choosing Britain and America, both liberal democracies facing similar challenges in the international landscape, provides the lens to explore the intricate processes of policy projection.The approach of this thesis falls within the methodological ambit of International History with its emphasis on insights gained from comparative studies and its liking for ‘borderlands’ and suggestive conclusions. The thesis has two parts. Part 1 is thematic and contextual in approach. It explores three determinants - national political structures and belief systems, the importance of the personal assumptions of policy makers, and role of the media - looking at foreign policy between 1929 and 1938 for illustrative material. Part 2, using the years 1939, 1940 and 1941, examines how these three determinants buttressed government and public reactions to the expanding war. The voices in this thesis are the human voices of the players of the time not the voices of later historical judgement. They are found in speeches, diaries, letters, and commentary in the media. These are the broad questions asked of the research: How resistant were underlying beliefs and assumptions - the determinants of Part 1 - to the stresses of wartime events? How deliberate were policy makers in organising statements for the media? Did public reaction influence policy? The analysis shows the strong persistence of established structures and assumptions as the context for the projection of wartime foreign policy in both countries. It shows media commentators consciously adjusting to perceptions of their own country’s national needs and constraints as they reported the war. As far as changing stated foreign policy, the reception in the media seemed only to influence timing and strategies for implementation as events unfolded rather than policy itself.
Sport for Development Side-lined Youth: An Empowering Intervention or Socializing Agent?
Keywords: athletes
critical race theory
marginalized youth
positive youth development
social change
sport for development

Faith in the positive outcomes of sport has led to its mobilization to fulfill several ‘developmental’ goals for youth in under-resourced communities (e.g., improved life skills, improved academics, etc.) under the name sport for development (SFD). The dominant narrative that sport is effective in the development of youth has been challenged by many scholars who illustrate that such a perspective is rooted in colonial practices that socialize participants to maintain power imbalances rather than empower participants and lead to social change. Hartmann and Kwauk (2011) term this the dominant vision approach. Within it, participants are not made aware of the institutions that play a role in their marginalization rendering them powerless in advocating for real change, growth, and development. This doctoral research program aimed to critically explore the dominant narrative that SFD programming is developmental for side-lined youth. Community-based participatory research (CBPR) strategies were used to engage young adults from marginalized communities as co-researchers by way of a young adult advisory board (YAAB). The YAAB co-designed data collection strategies deployed in two studies that captured the voices of side-lined youth and program facilitators. Life history interviews were used to capture the counter stories of side-lined youth which were analyzed to yield five narratives that illustrate a range of developmental gaps SFD programs have the potential to address. Semi-structured interviews were used to capture program facilitators’ intentions for side-lined youth who participated in their programs. The YAAB took part in thematic analysis that revealed alignment between youth narratives and program facilitator intentions, as well as differences in developmental approaches between program facilitators with lived experience in comparison to those without (i.e., learned experience). In addition, the CBPR process was evaluated to produce a systematic method for meaningful engagement of side-lined youth in the research process. Overall, this doctoral research program discusses the role of power in SFD programming and research, while providing theoretical and practical considerations for researchers and practitioners in this field. Furthermore, it explores the socioeconomic challenges that side-lined youth face, and demonstrates how sport can be used to address those gaps in a useful and realistic way.
Parent Involvement in the Lives of College Students in Ontario
Keywords: college students
colleges in Ontario
family involvement
parent engagement
parent involvement
supporter involvement

When working at a community college in Ontario, my colleagues and I frequently interacted with students and their parents. However, limited institutional resources supported such interactions and much of our work with parents was performed off the sides of our desks. As both an administrator and academic researcher, I was conflicted by how scholarly descriptions of parent involvement differed from my professional encounters with parents of students. I was inspired to synergize the support students receive in their college journeys: both the familial and institutional. Thus, the purpose of my doctoral research became to explore the involvement of parents in their students’ education journeys at four public Ontario Colleges. I grounded my research in Bronfenbrenner's (1977) & Bronfenbrenner & Morris' (2006) bioecological model. I used the bioecological model to conceptualize influences (including parents) on human (student) development. Through website content analysis, telephone interviews, and surveys, I sought to elucidate the nature of parent involvement in the context of college in Ontario. I used the parallel-databases variant of convergent design to collect and analyze data on the involvement of parents in the lives of college students, through three distinct research strands: (i) interviews with college employees,(ii) surveys of college employees, students, and parents, and (iii) college website content analysis. My study yielded novel contributions to the literature, including that the involvement of parents impacted both students and college employees. My research documented that parents (& other family members) were involved in a myriad of ways and that their involvement both positively and negatively affected students. My findings also highlighted a range of perspectives in regards to how parents were foreseen as involved in students’ college related experiences. In particular, I found institutional and college employees’ perceptions of the home-school relationship, often conflicted with student expectations and the involvement practices of parents (especially for families from marginalized backgrounds). Overall, I concluded that, in Ontario, parents are involved throughout students’ college journeys, from recruitment through to graduation, and beyond. Ultimately, I hope that my dissertation may inform professional practices seeking to support the involvement of parents in students’ college journeys in Ontario.
Molecular Recognition and Catalysis – Amino Acids, Epoxide and Carbon Dioxide
Keywords: amino acids
biotin-dependent carboxylase
epoxidation
mechanism
molecular recognition

Molecular recognition and catalysis are fundamental areas of research in chemistry. Stereoselective recognition of amino acids, catalytic asymmetric epoxidation, and CO2 fixation were investigated combining experimental and computational methods. Chapter 1 focuses on the stereoselective recognition of amino acids by imino boronate complexes. The origin of stereoselectivity is explained in terms of covalent, steric, and cation-π interactions. Conflicting reports on the stereoselectivity of this system is addressed. Moreover, proline derivatives were synthesized diastereoselectively from the amino acid boronate complexes. In Chapter 2, stereoselective recognition of (2R,3S)-2-phenyl-3-methylaziridine with diaminocyclohexane (DACH)-based Co-salen complexes was investigated where experimentally observed stereoselectivities and structures were reproduced with DFT calculations. Computation also shows that substituting the metal from Co to Mn and aziridines to corresponding epoxides does not significantly change the position of the coordinated substrates or their stereoselectivity of recognition. In Chapter 3, the origin of stereoselectivity for the Jacobsen-Katsuki epoxidation was examined by computation based on the lowest energy transition state structures. Through computation, we found a new origin of stereoselectivity that has not been previously reported. The enantioselectivity can be explained for the first time in terms of a unified transition state for different catalysts and substrates. In Chapter 4, the electronic effect on enantioselectivity of Jacobsen-Katsuki epoxidation is investigated by computation and analyzed using Hammond postulate, Reactivity-Selectivity principle, and Marcus equation. This study shows that Marcus’ intrinsic barrier is sensitive to the electronic effect, which results in greater stereoselectivity. In Chapter 5, we show that the electrophilicity of CO2 matches that of diaryl carbonates with the leaving group phenol pKa of around 7.6 and 5.4 when the nucleophiles are water and thiomethyl acetate, respectively. Enthalpic activation of CO2 can be achieved towards all nucleophiles by conversion to carbonates or carbamates with good leaving groups. A novel mechanism of biotin-dependent carboxylases is proposed based on computation, which considers N-phosphocarboxybiotin as the carboxylating agent rather than the conventionally proposed carboxybiotin. Each step of the new catalytic cycle was shown to be chemically reasonable and thermodynamically downhill by DFT computation. With the new mechanism, enthalpic activation of CO2 can be achieved unlike with carboxybiotin.
Theoretically Informed Design and Acceptability Evaluation of a Communication Bundle for Adult Intensive Care Unit Patients with an Advanced Airway during Pandemic Conditions
Keywords: Communication
COVID-19
Critical Care

Background. Communication difficulty is associated with adverse physical and psychological sequelae for intensive care unit (ICU) patients managed with an advanced airway for mechanical ventilation. Supportive communication tools exist; however, few are integrated into practice. COVID-19 pandemic (2020-22) infection prevention and control (IPAC) conditions contribute new barriers to communication warranting solutions. Objectives. To use a theoretically informed study design to create and evaluate the acceptability of a co-designed bundled COmmunication intervention for adult patients with an advanced airway during the COVID-19 PandEmic (COPE) from the perspective of diverse health care professionals (HCP), patients, and family in the adult ICU IPAC context. Design. A sequential multiple study design including a scoping review, an interview study, co-design methods, and a convergent mixed-method acceptability evaluation study in a single adult medical-surgical ICU in Toronto, Canada (January 2020 – March 2021). Methods. The Theoretical Framework of Acceptability was used to consecutively analyze reported barriers to and facilitators for: communication tool use in the adult ICU in the scoping review; and stakeholder support of patient communication in the pandemic ICU context in qualitative interviews. The results from these two studies informed the co-design of the COPE intervention. Finally, the acceptability, appropriateness, and feasibility of COPE were evaluated using mixed-methods. Results. The COPE intervention included 1. Stocked IPAC approved physical communication tool cart, and electronic tool cart, 2. Education modules for HCP, and 3. Information for patient-family connection. COPE was rated and described to be acceptable, appropriate, and feasible. Integration of data sets revealed additional recommendations for COPE including enhanced access to tools and training; leadership support of the physical, cognitive, and emotional impact of communication work; and use of a theoretically informed implementation framework. Conclusion. A theoretical understanding of acceptability of communication interventions such as COPE from the perspective of key stakeholders can inform intervention design, improve acceptability, and potentially advance utilization of communication supportive tools in practice. Relevance to practice. Implications include the availability of an acceptable communication intervention for use and further evaluation, a call to action for communication training, and need for leadership support for ICU HCP and communication work.
Theory and Application of Refracting Metasurfaces for Phased-Array Angular Scan Extension
Keywords: 5G Antennas
Antenna Arrays
Huygens
Lenses
Scattering

Most of this thesis discusses metasurface lenses and their application to enhancing the angular scan range of phased antenna arrays -- an application of particular interest for 5G. Theoretical aspects of the problem are first discussed, and we are able to say that most, if not all, lens-based scan enhancers degrade the directivity of the source. This degradation is proportional to the enhancement of the device. To validate some of the theory and test various refracting devices a simulation tool was written to perform quick simulations of 2D scenarios. The simulation tool is discussed in detail as well, and it turns out that the vague metasurface definition (defined via the phase it incurs upon the incident fields) leads to quantifiable "errors." Simulation rigor is improved and the rest of the theory is validated via full-field simulations. In these simulations the lenses are defined according to the theory of ZYK boundary surfaces (a.k.a. omega bi-anisotropic Huygens metasurfaces). This definition performs as an ideal lens in the context of Gaussian beams, and we argue that this definition extends the concept of an ideal lens to electromagnetics. The topic is concluded by experimental verification of some of the theoretical claims. Finally, the theory of cotangent ZY boundary surfaces (a.k.a. Huygen's refracting metasurface, a.k.a.tangent sigma-tau boundary) is revisited. In a somewhat educational manner, we build up the theory of "ideal" refraction and claim that existing treatments of the topic leave the problem somewhat incomplete -- no "general" scattering solution is known. We then proceed to analytically solve for the general scattering of a tangent-like sigma-tau boundary subject to TE illumination. The obtained solution is studied extensively, and new functionalities of cotangent ZY boundaries are discovered -- namely, refraction without specular reflection and oblique absorption.