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    Sustainability Practices and Financial Performance in Low-Cost Airlines: A Panel Analysis Using a Sustainability Disclosure Index
    (University of Waterloo, 2026-05-06) Goyal, Siddhant
    The aviation industry faces growing pressure to address its environmental and social impacts as climate regulations tighten and stakeholders, including investors, regulators, and civil society, demand greater transparency from firms operating in emissions-intensive sectors. Although sustainability disclosure has expanded significantly across industries, its financial implications remain contested, particularly in sectors where competitive advantage depends on cost efficiency. Low-cost carriers provide a distinct context for examining this relationship because their business models prioritize cost leadership, high aircraft utilization, and lean operational structures. In such settings, firms face institutional pressure to communicate sustainability commitments while operating under structural constraints that limit discretionary investment. Drawing on stakeholder theory, and specifically the salience framework developed by Mitchell et al. (1997), this study conceptualizes sustainability disclosure as a selective organizational response to differentiated stakeholder demands, where the depth and structure of disclosure reflect which stakeholder pressures are most financially proximate and most compatible with the operating logic of the low-cost business model. Using sustainability and annual reports from 20 global low-cost carriers between 2015 and 2024, the study develops a Sustainability Disclosure Index (SDI) to measure the depth of Environmental, Social, and Governance (ESG) disclosure. The SDI is constructed through systematic content analysis of corporate reports, applying a structured coding framework aligned with Sustainability Accounting Standards Board (SASB) sustainability topics. The resulting dataset is used to examine whether sustainability disclosure depth is associated with financial performance through panel regression analysis. The findings indicate that while sustainability disclosure depth among low-cost carriers has increased steadily over the study period, greater overall disclosure depth is not associated with improved financial performance. Disaggregated analysis reveals that environmental disclosure is positively associated with return on assets, consistent with the interpretation that investor and regulatory demands converge most directly on the environmental dimension and that the underlying practices overlap with the operating economics of the low-cost model. Social disclosure is associated with a negative short-run relationship with profitability in the full sample, a pattern concentrated in financially distressed airline-years rather than representing a general feature of the LCC segment. Governance disclosure shows no statistically significant association with financial performance, consistent with its threshold-driven nature and limited cross-firm variation. The results suggest that the financial relevance of sustainability disclosure in the low-cost airline industry is conditional on which stakeholder demands the underlying practices address and how closely those demands are connected to the operating economics of the business model.
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    Probabilistic Verification of Quantum Devices Under Finite Measurement Resolution and Adversarial Disturbances
    (University of Waterloo, 2026-05-06) Rosas-Bustos, Jose
    The development of practical quantum devices is transitioning from laboratory-scale demonstrations to engineered systems intended for integration, deployment, and sustained operation. As quantum hardware increases in complexity and scale, establishing reliable verification procedures under realistic operating conditions becomes a central engineering challenge. Real quantum devices operate under finite measurement resolution, estimator tolerances, drift, hardware constraints, and limited data, all of which fundamentally restrict what can be inferred from experimental observations. Consequently, verification strategies based on static thresholds, ideal measurements, or full microscopic reconstruction are often insufficient for deployment-grade systems. This thesis develops an engineering-oriented probabilistic framework for modelling and verifying quantum devices under finite measurement resolution and adversarial disturbances. Rather than treating verification as a binary decision, the work reframes it as a system-level inference problem governed by uncertainty, tolerances, and acceptance criteria. Across five manuscript-based studies, the thesis identifies fundamental verification vulnerabilities, introduces probabilistic modelling approaches, and develops practical mitigation, scaling, and governance-oriented strategies compatible with real hardware. First, the thesis shows that finite measurement resolution can create regions of operational indistinguishability in which conventional quantum integrity checks become statistically non-discriminating, even when the underlying theoretical assumptions remain valid. Building on this result, a probabilistic verification framework is introduced to model acceptance outcomes under uncertainty and to quantify confidence levels rather than rely on fixed thresholds alone. The thesis then develops an operational threat-modelling framework for adversarial disturbances in continuous-variable quantum communication, classifying structured interference into reconnaissance, exploratory, and denial-of-service regimes on the basis of receiver-observable statistics and finite-sample detectability. In response to such disturbances, phase-first modulation strategies are developed to show that static operating points can be inadequate under structured stress and that lightweight, hardware-compatible adaptations can improve resilience. To address scalability in large quantum systems, the Effective Mode Approximation is introduced as a reduced-order probabilistic verification framework for collective Hamiltonian behaviour, enabling system-level assessment without full mode-resolved reconstruction. Finally, a probabilistic forecasting framework is developed to model time-dependent cryptographic security degradation under evolving classical and quantum threat capabilities, extending verification concepts to strategic risk assessment and transition planning. Taken together, these contributions establish a unified probabilistic verification perspective grounded in robustness, scalability, and operational realism. The proposed methods align with established principles from control, signal processing, and system identification, and they provide practical tools for assessing trust, performance, and readiness of quantum hardware as it moves toward real-world deployment.
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    Towards Socket Testing Standardization: Advancing Mock Residual Limbs for Transtibial Prosthetic Socket Testing Through 6DOF Gait Simulation
    (University of Waterloo, 2026-05-06) Rossi, Erica
    The transtibial prosthetic socket is a key component in below-knee prostheses. While technology used to create and augment sockets have been evolving, testing methods have not kept pace. The criterion standard for the testing of transtibial prostheses, ISO 10328, does not specify testing for the socket as a stand-alone unit beyond static compression testing to simulate heel-strike and toe-off components of gait. Additionally, the limb dummies or Mock Residual Limbs (MRLs) used in these testing methods to interface with, and impart loading on, the socket are poorly defined and typically made of non-compliant plaster or polyurethane. This lack of standardization, specifically socket testing, has been identified by the American Orthotics and Prosthetics Association Socket Guidance Workgroup as a major limitation and motivated this thesis. This research aimed to develop a mechanical cyclic gait testing setup utilizing a novel compliant MRL. Ten (10) MRL variations were developed, comprising of an aluminum threaded rod to simulate the tibia and a single or dual-layer of silicone to simulate the skin and soft tissues of the residuum. EcoFlex 00-30 and VytaFlex 30A silicones were selected as the MRL materials to replicate skin and tissue material properties and mechanical behaviour. Three novel 3D printed Spider structures were also developed (50 mm, 70 mm diameter, and Equidistant) and integrated with the tibia rod to promote material adhesion between the rod and the silicone and support load transfer by creating a mechanical interlock with the silicone. Affixed to the VIVO™ Joint Simulator, MRLs were seated into a transtibial prosthetic socket for uniaxial and multiaxial mechanical testing. The VIVO™ enabled custom cyclic gait waveforms representing realistic amputee knee joint forces and moments. These loads were imparted on the socket and enabled the evaluation of MRL mechanical properties. Uniaxial and multiaxial cyclic gait testing of the MRLs and socket system highlighted the ability of the Spider to increase the MRLs response to loading. The 50 mm Spider saw an improved moment loading response, and the 70 mm Spider improved force loading response when integrated with the MRLs. Additionally, increased stiffness of the single layer VytaFlex 30A silicone (compared to the single layer EcoFlex 00-30) allowed for an improved moment loading response of the MRL. The dual-layer (60:40) MRL of VytaFlex 30A and EcoFlex 00-30 further improved MRL force loading response. The top two performing MRLs recommended for further research are the VytaFlex 30A Core, and EcoFlex 00-30 Outer Shell 50 mm Spider MRL and the VytaFlex 30A 50 mm Spider MRL. By leveraging the ability of dynamic mechanical testing this research can act as a bridge between rudimentary bench testing and resource intensive clinical trials – revolutionizing the way socket testing is viewed and promoting more efficient technology development.
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    Role of e-cigarettes and pharmacotherapy during attempts to quit cigarette smoking: The PATH Study 2013-16
    (Public Library of Science, 2020-09-02) Pierce, John P.; Benmarhnia, Tarik; Chen, Ruifeng; White, Martha; Abrams, David B.; Ambrose, Bridget K.; Blanco, Carlos; Borek, Nicolette; Choi, Kelvin; Coleman, Blair; Compton, Wilson M.; Cummings, K. Michael; Delnevo, Cristine D.; Elton-Marshall, Tara; Goniewicz, Maciej L.; Gravely, Shannon; Fong, Geoffrey T.; Hatsukami, Dorothy; Henrie, James; Kasza, Karin A.; Kealey, Sheila; Kimmel, Heather L.; Limpert, Jean; Niaura, Raymond S.; Ramoa, Carolina; Sharma, Eve; Silveira, Marushka L.; Stanton, Cassandra A.; Steinberg, Michael B.; Taylor, Ethel; Bansal-Travers, Maansi; Trinidad, Dennis R.; Gardner, Lisa D.; Hyland, Andrew; Soneji, Samir; Messer, Karen
    Background More smokers report using e-cigarettes to help them quit than FDA-approved pharmacotherapy. Objective To assess the association of e-cigarettes with future abstinence from cigarette and tobacco use. Design Cohort study of US sample, with annual follow-up. Participants US adult (ages 18+) daily cigarette smokers identified at Wave 1 (W1; 2013-14) of the PATH Study, who reported a quit attempt before W2 and completed W3 (n=2443). Exposures Use of e-cigarettes, pharmacotherapy (including nicotine replacement therapy), or no product for last quit attempt (LQA), and current daily e-cigarette use at W2. Analysis Propensity score matching (PSM) of groups using different methods to quit. Outcome measures 12+ months abstinence at W3 from cigarettes and from all tobacco (including e-cigarettes). 30+ days abstinence at W3 was a secondary outcome. Results Among daily smokers with an LQA, 23.5% used e-cigarettes, 19.3% used pharmacotherapy only (including NRT) and 57.2% used no product. Cigarette abstinence for 12+ months at W3 was ~10% in each group. Half of the cigarette abstainers in the e-cigarette group were using e-cigarettes at W3. Different methods to help quitting had statistically comparable 12+ month cigarette abstinence at W3 (e-cigarettes vs no product: Risk Difference (RD) = 0.01, 95% Cl: -0.04 to 0.06; e-cigarettes vs pharmacotherapy: RD = 0.02, 95% Cl: -0.04 to 0.09). Likewise, daily e-cigarette users at W2 did not show a cessation benefit over comparable no-e-cigarette users and this finding was robust to sensitivity analyses. Abstinence for 30+ days at W3 was also similar across products. Limitations The frequency of e-cigarette use during the LQA was not assessed, nor was it possible to assess continuous abstinence from the LQA. Conclusion Among US daily smokers who quit cigarettes in 2014-15, use of e-cigarettes in that attempt compared to approved cessation aids or no products showed similar abstinence rates 1-2 year later.
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    Experimental investigation of the effects of water content on the anisotropy of mode I fracture toughness of bedded mudstones
    (Public Library of Science, 2020-08-27) Yang, Jianfeng; Li, Li; Lian, Haojie
    The influence of water content on mode I fracture toughness (KIc) of mudstones has been studied using semi-circular bend (SCB) specimens subject to three-point bendings. And the mudstone SCB specimens are divided into three types, including Type-A, Type-B and Type-C, corresponding to the three configurations of the bedding planes, including divider direction, arrester direction, and transverse direction, respectively. The test results show that the values of KIc for the three types of specimens are different due to the bedding structure, the Type-A specimens have the largest value of KIc for the same soak period, while the Type-C specimens possess the smallest value. As the soak period increases, the KIc of the three kinds of mudstone specimens decreases, and the fracture mechanisms of the specimens change gradually from the brittle failure form to the ductile failure form. Moreover, the standard deviation was used to quantify the anisotropy degree of the KIc of the mudstone samples. As the water content increases, the standard deviation increases from 0.057 to 0.139, which indicates a significant increase in anisotropy of the KIc of the mudstone specimens. In addition, the acoustic emission (AE) system was used to detect the AE events associated with the fracture initiation and propagation in the mudstone specimens for the different water content, with the raising water content, the cumulative AE events decrease, and the standard deviation of AE events increases, representing that the anisotropy of the AE events of the three types of specimens becomes more prominent. Further, the relationship between the tensile strength (σt) and the KIc of the three types of mudstone specimens for different water contents has been proved to be the linear relation.