PhD Dissertations
http://library2.smu.ca/xmlui/handle/01/9004
2024-03-29T13:51:33ZComputational biochemical study of the prebiotic selection of nucleic acids
http://library2.smu.ca/xmlui/handle/01/31893
Computational biochemical study of the prebiotic selection of nucleic acids
This thesis addresses fundamental questions related to the prebiotic evolutionary selection of the building blocks of nucleic acids. The structural tendencies and propensities in today’s nucleic acids are rationalized based on thermodynamics as a principal driver of evolutionary selection. The free energies of the possible reaction paths available to prebiotic Nature are calculated from quantum chemistry. As one example (of many), the β-anomers of the nucleosides(tides) - predominant in modern nucleic acids - are found to be slightly more stable than their αcounterparts. This small thermodynamic advantage operating over millennia may have contributed to the observed dominance of today’s canonical forms. Calculations also suggest the possibility that non-canonical N-(2-aminoethyl)glycine (AEG) and glycerol nucleosides(tides) may have assisted in the synthesis of today’s nucleosides(tides) if the prebiotic environment has been aqueous. Energetic comparisons of ancestral nucleic acids containing arsenate instead of phosphate indicate no thermodynamic advantage for the phosphate, raising an important open question as to the reason for Nature’s selection of the latter. It is also found, computationally, that barbituric acid may have well been a prebiotic precursor of today’s nucleobases reinforcing earlier proposals. A more fundamental question may be about the choice of nucleic acids as the carriers of genetic information, in the first place, instead of other contenders such as proteins. A partial answer is formulated by proposing a quantitative account of the “value” of information as a new dimension to be added to the traditional “amount” (bits) in Shannon’s information theory. Thus, the thesis addresses certain aspects of evolutionary biochemistry from the standpoint of thermodynamics
under differing conditions of solvation. Meanwhile, the rates (kinetics) were not considered in this work since the synthetic and mechanistic steps from reactants to products of most of the proposed reactions remain largely unknown. Several other potential factors have not been considered but, with these variables being constant, our results remain valid and so are the questions they open for future investigations.
2024-01-31T00:00:00ZTwo-eyed critical sensemaking : an integrative approach for studying post-TRC organizational change
http://library2.smu.ca/xmlui/handle/01/31860
Two-eyed critical sensemaking : an integrative approach for studying post-TRC organizational change
The research method, Two-Eyed Critical Sensemaking, is a novel integrative approach for
studying the relationship between policy documents and enactments of respectful reconciliation focused organizational change. Drawing from the guiding principle of <i>Etuaptmumk</i>/Two Eyed Seeing, I define six iterative methodological steps that weave together two qualitative critical research approaches - Culturally Relevant Gender-Based Analysis (CRGBA), an Indigenous-led view of applied policy studies, and Critical Sensemaking, a Canadian-led view of management and organization studies. I use the Truth and Reconciliation Commission (TRC) of Canada as a case study to demonstrate the function of the Two-Eyed Critical Sensemaking method. The TRC sparked public concern regarding Canada-Indigenous reconciliation and a discursive shift that
transformed reconciliation into a defining political issue in Canada. But, the meaning of
reconciliation is inconsistently used in practice. I propose the TRC presents a model for
reconciliation-oriented organizational change for Canadian administrators responding to the Commission’s Calls to Action.
1 online resource (195 pages) : charts; Includes abstract and appendices.; Includes bibliographical references (pages 163-182).
2023-09-27T00:00:00ZCorporate social responsibility, diversity, and corporate communication : natural language processing and machine learning approaches
http://library2.smu.ca/xmlui/handle/01/31800
Corporate social responsibility, diversity, and corporate communication : natural language processing and machine learning approaches
In the second chapter, we rely on collaborative intelligence, which combines human and artificial intelligence (i.e., supervised machine learning), to construct a textual feature that measures firmlevel gender diversity talk (GDT), as reflected in the share of gender diversity discussion in the narrative of quarterly earnings conference calls. We show that the MeToo movement, an unequivocal social movement shock, led to a significant increase in GDT. We however document positive short-term stock market reaction to GDT during the first post-MeToo quarter, indicating that GDT is, on average, perceived by investors as value-relevant. We also show that post-MeToo, high-GDT firms engage in less substantive female-friendly initiatives, indicating that firms do not walk the talk of gender diversity.<br> In the third chapter, using industry-relevant documents and the most-cited CSR/ESG papers to develop a new CSR dictionary, we show that the COVID-19 incentivized firms to engage in overselling of their CSR. We find that more CSR talk during COVID translates into value depression, indicating that investors, on average, do not perceive CSR overselling as value-relevant. Our evidence suggests that firms do not walk their CSR talk and that CSR Talk is positively (negatively) associated with the use of positive (negative) words. Our evidence suggests that ‘cheap talk is not cheap’.<br>
In the fourth chapter, we use Natural Language Processing to measure supply chain risk
(SCR) faced by US firms, as expressed in narratives of quarterly earnings conference calls. We show that exposure to SCR reached unprecedented levels during COVID-19. The effect of COVID-19 on SCR is more pronounced in firms with a greater dispersion of analyst forecasts, increased complexity, and more financial constraints. We document a negative effect of SCR on conference call short-term returns and future profitability. High-SCR firms are also associated with longer cash conversion cycles and more ESG overselling.
1 online resource (226 pages) : graphs; Includes abstract and appendices.; Includes bibliographical references (pages 27-36, 73-81, 128-136, 185-189, 226).
2023-06-28T00:00:00ZDiscourse and intersectionality over time in leadership composition
http://library2.smu.ca/xmlui/handle/01/31799
Discourse and intersectionality over time in leadership composition
Using British Airways (BA) PLC as the case study, I undertake a critical discourse
analysis of the lack of diversity in top management teams. Organization leadership is important for several reasons including its role in organization performance and success. As operating environments become progressively complex, understanding who the leaders are, and how that leadership composition comes about, is critical. Despite globalization and increased access to diverse ways of thinking, ultimate authority resides in the top management teams whose configuration remains homogenous. I explore how the discourse of leadership precludes greater diversity in the composition of the highest levels of management. Results highlight three key factors that affect the discourse of leadership. They are history, the organization intersectionality experience, and influence from the external operating environment.
1 online resource (193 pages); Includes abstract.; Includes bibliographical references (pages 174-193).
2023-06-13T00:00:00ZMicrosporidia-host interactions in beneficial lady beetles : factors that influence chronic disease
http://library2.smu.ca/xmlui/handle/01/31740
Microsporidia-host interactions in beneficial lady beetles : factors that influence chronic disease
Lady beetles produce species-specific defensive compounds (alkaloids) that are toxic to some predators and deters others with their foul taste. Some lady beetle alkaloids, such as harmonine from <em>Harmonia axyridis</em>, exhibit antimicrobial activity and may provide the beetle protection against pathogens. Convergine and hippodamine are the major and minor alkaloids produced by the convergent lady beetle, <em>Hippodamia convergens</em>. Adaline and adalinine are produced by the two-spotted lady beetle, <em>Adalia bipunctata</em>. Although the defensive chemistry of these lady beetles has received some attention, the role of their alkaloids with respect to pathogen virulence is poorly understood. Microsporidia, intracellular spore-forming parasites, have been reported in several coccinellid species, including <em>Tubulinosema hippodamiae</em> from <em>H. convergens</em> and <em>Vairimorpha (Nosema) adaliae</em> from <em>A. bipunctata</em>. These pathogens delay larval development but have no other observable effect on the host. However, previous studies were performed under optimal laboratory conditions and did not take into consideration challenges (stress factors) beetles would face in the natural environment. The objective of this study is to determine the relationship between alkaloids and microsporidiosis in <em>H. convergens</em> and <em>A. bipunctata</em>, and to examine the effects of different stress factors (limited food availability, rearing temperatures above optimal, and physical agitation) on the development of microsporidiosis and production of alkaloids in these beetles. During all three research trials, larval development was delayed for microsporidia-infected beetles when compared to uninfected beetles. In Chapter Two, limited food availability for microsporidia-infected <em>A. bipunctata</em> further delayed larval development compared to uninfected beetles, increased pathogen load and reduced adaline content. An irregular, unpredictable food supply acts as a stressor to further amplify the negative effects of microsporidiosis for <em>A. bipunctata</em>. No further development delays were observed for <em>H. convergens</em> when provided an irregular diet and no conclusions could be made regarding <em>H. convergens</em> alkaloid content. In Chapter Three, rearing <em>A. bipunctata</em> at temperatures above 25°C shortened development, decreased pathogen load, and increased adaline content. Temperatures above 25°C mitigate the microsporidian infection. In the final chapter, adaline content increased as <em>A. bipunctata</em> development progressed, uninfected adults produced more adaline than infected beetles when exposed to physical agitation on alternate days, and spore counts were highest when beetles were exposed to daily shaking. As with limited food availability, physical agitation further amplified the negative effects of microsporidiosis in<em> A. bipunctata</em> and had an influence on alkaloid production. Many plants produce antimicrobial secondary metabolites (phytoalexins) that can inhibit the germination and/or growth of bacteria and fungi. Alkaloids present in lady beetles may act as the animal equivalent of phytoalexins and play a larger role in the coccinellid immune system than previously thought. These findings provide some preliminary insight into the relationship between adaline, <em>V. adaliae</em> and <em>A.bipunctata</em>, including certain factors that influence this relationship. However, adalinine, hippodamine and convergine, alkaloids not examined in this study, may also influence infection and could be the focus of future studies.
1 online resource (vii, 97 pages) : colour illustrations, charts, graphs; Includes abstract and appendix.; Includes bibliographical references (pages 82-91).
2023-04-27T00:00:00ZAdvanced forecasting algorithms for renewable power systems
http://library2.smu.ca/xmlui/handle/01/31660
Advanced forecasting algorithms for renewable power systems
Wind and solar power prediction is a challenging but important area of research. The thesis you described explores various statistical models and deep learning methods to improve the accuracy of wind speed and solar radiation predictions. The use of autoregressive integrated moving average (ARIMA) models, long short-term memory (LSTM) based recurrent neural network (RNN) models, and multilayer perceptron (MLP) neural networks were studied to predict future wind speed values and the performance of a photovoltaic (PV) system. The results showed that the proposed models can effectively improve the accuracy of wind speed and solar radiation prediction and that the LSTM network outperformed the MLP network in predicting solar radiation and energy for different time periods. It is important to note that the performance of the models may
vary depending on the specific dataset used, the hyperparameters, and the model architecture. Therefore, it is essential to carefully tune these parameters to achieve the best possible performance. Accurately predicting the performance of a PV system at short time intervals is particularly important in the context of renewable energy sources, as it can help optimize the usage of these resources and improve overall efficiency. This research can contribute to the development of more accurate and reliable prediction models, which can lead to more efficient use of wind and solar power, reduce costs, and promote the adoption of renewable energy sources.
1 online resource (x, 112 pages) : illustrations (some colour), charts (some colour), graphs (some colour); Includes abstract.; Includes bibliographical references (pages 100-112).
2023-04-14T00:00:00ZDetermination of point proton radii of neutron-rich carbon isotopes
http://library2.smu.ca/xmlui/handle/01/31163
Determination of point proton radii of neutron-rich carbon isotopes
Exotic features like the halo and the (dis)appearance of the magic numbers were revealed by investigating the nuclei towards the neutron-rich region that have a large neutron/proton asymmetry. Investigating the evolution of proton radii together with the matter radii along an isotopic chain will allow us to characterize the halo formation, neutron skin thickness, and shell evolution around the neutron drip-line. The first determination of the point proton radii of neutron-rich carbon isotopes <sup>20,22</sup>C is presented in this work. The proton radii of these neutron-rich carbon isotopes were determined from a measurement of the charge-changing cross-section σ<sub>cc</sub>, defined as the sum of cross sections of reactions that changes the atomic-number (<em>Z</em>). The experiment was performed at the BigRIPS facility at RIKEN Nishina Center in Japan, at a relativistic beam energy around ∼ 200<em>A</em> MeV with a carbon target. The proton radii were extracted from the measured σ<sub>cc</sub> using the nite range Glauber model framework. The proton radii increase for <sup>20</sup>C and <sup>22</sup>C compared to the previously measured carbon isotopes <sup>12−19</sup>C, showing signatures of the disappearance of shell closures at <em>N</em> =14 and <em>N</em> = 16 along this isotopic chain. The neutron skin thickness (∆<em>R</em><sub>np</sub>) of these neutron-rich carbon isotopes (<sup>20,<em>22</em></sup>C) is reported for the rst time in this thesis using the proton radii determined in this work and measured matter radii available from the literature. ∆<em>R</em><sub>np</sub> of 1.23 (20) fm is determined for the two-neutron halo, <sup>22</sup>C affirming the presence of a halo. The halo radius of 6.6 ± 1.1 fm in <sup>22</sup>C is found to be as large as <sup>11</sup>Li. The proton radii are compared to the predictions reported for these neutron-rich carbon isotopes. The experimental proton radii have challenged these predictions.
1 online resource (xvi, 125 pages) : colour illustrations, charts (some colour), graphs (some colour); Includes abstract.; Includes bibliographical references (pages 114-125).
2022-10-20T00:00:00ZDignity at work
http://library2.smu.ca/xmlui/handle/01/31003
Dignity at work
Workplace dignity has been an emerging topic in psychology in the last decade and is theoretically tied to employee well-being (Khademi et al., 2012; Utriainen & Kyngäs, 2011).
However, dignity at work has been difficult to assess due to the lack of a clear definition and the
fact that no measure of workplace dignity is available (Lucas et al., 2013). The purpose of this
study was to develop and validate a measure of workplace dignity, demonstrate that it is a unique
construct, and examine its relationships to pre-established organizational constructs. Based on
the current definitions and theorized aspects of dignity at work, a more extensive definition of
workplace dignity was offered: Dignity at work involves both self-respect and respect from
others, a feeling of worth and value, and a sense of autonomy and control over one’s own
behaviour. Study 1 produced a 12-item, four-factor scale where each factor demonstrated
satisfactory internal consistency (control; work and value; respect from others; self-respect).
Study 2 found that the factor structure roughly held up in a sample of working students and that
it predicted employee engagement above and beyond other workplace constructs. Study 3 found
that psychological safety longitudinally predicted three of dignity’s dimensions over time (two
time lags). Study 4 found that the scale’s factor structure held up over time (three time lags) in a
retail sample. Each study examined antecedents (e.g., workload, leadership) and outcomes (e.g.,
stress) of workplace dignity. Implications for theory and practice are discussed.
1 online resource (168 pages); Includes abstract and appendices.; Includes bibliographical references (pages 117-130).
2022-08-02T00:00:00ZDesigning power scheduling algorithms for electric vehicles and energy storage systems in bi-directional markets using mixed-integer programming
http://library2.smu.ca/xmlui/handle/01/30959
Designing power scheduling algorithms for electric vehicles and energy storage systems in bi-directional markets using mixed-integer programming
Optimal battery scheduling for electric vehicles and energy storage systems when cooperating with renewable energy generation in behind-the-meter applications is studied in this thesis in the framework of Mixed-Integer Programming (MIP). High capability in obtaining global optima in optimization problems has made MIP a popular tool in smart grid research and particularly for battery scheduling problems. One important issue with regards to the battery cycling, is the battery degradation which could complicate the Unit Commitment (UC) models. This is because the battery wear model can be nonlinear and difficult to be incorporated into a UC problem. To address the existing research gap, in this thesis a battery degradation model has been introduced to be incorporated into a short-term MIP battery scheduling model to estimate the capacity loss of a Liion battery caused by irregular charging and discharging events.
Hence, a MIP UC model is developed in this work which incorporates the introduced battery wear model. Based on that, the UC problem for a home-based microgrid is investigated and different UC strategies have been presented to minimize the operation cost as well as the capacity loss of batteries and the carbon footprint for a home equipped with a smart residential microgrid. The impact of the resolution of a home UC model on the capacity loss of batteries is another studied subject in this work, where hourly and intra-hourly granularities are compared in terms of the battery aging. A Controller-Hardware-in-the-Loop (C-HIL) setup is developed to measure the performance of the
UC strategies as well as the battery degradation rates. Optimal battery scheduling in applications with multiple beneficiaries such as workplaces with electric vehicle (EV) charging stations is also investigated in this work by studying different UC strategies that take into account the interests of system operators and EV users to different extents. The results of this work show that the presented MIP UC models, that incorporate the introduced battery wear model, can be solved for real optimums in different smart grid applications.
1 online resource (xv, 201 pages) : colour illustrations, colour charts, graphs (some colour); Includes abstract.; Includes bibliographical references (pages 189-201).
2022-05-27T00:00:00ZToward intersectional history
http://library2.smu.ca/xmlui/handle/01/30933
Toward intersectional history
In this thesis, I introduce a theoretical approach called Intersectional History (IH).
IH is theorized by bringing together a critical approach to intersectionality with a
postmodern approach to the study of the past. The purpose of bringing these two domains
together is to provide a theoretically-informed way to focus on revealing intersectional based privilege and marginalization in historical accounts of organizations. A primary focus of IH is to consider how categories of identity are constructed and reproduced
within organizational materials from the past, over time. In particular, IH is concerned
with the ways that those powerful constructions of categories of identity overlap and
reinforce systems of oppression, such as racism, sexism, and colonialism, within
organizational contexts. Another key purpose of IH is to reveal the stories of those at the
intersection of overlapping, marginalized categories of identity and re-centre their
experiences and contributions in organizations. I demonstrate the potential of IH through
an analysis of the Australian Airline, Qantas, with a specific focus on how women and
Aboriginal Australians are constructed within the organizational material, over time.
1 online resource (241 pages) : colour charts; Includes abstract and appendix.; Includes bibliographical references (pages 196-235).
2022-04-20T00:00:00Z