About MacSphere

MacSphere is McMaster University's Institutional Repository (IR). The purpose of an IR is to bring together all of a University's research under one umbrella, with an aim to preserve and provide access to that research. The research and scholarly output included in MacSphere has been selected and deposited by the individual university departments and centres on campus.

To contribute to McMaster's Institutional Repository, please sign on to MacSphere with your MAC ID.

If you have any questions, please contact the MacSphere Support Team.

Students wishing to deposit their PhD or Masters thesis, please follow the instructions outlined by the School of Graduate Studies.

Communities in MacSphere

Select a community to browse its collections.

Now showing 1 - 5 of 5

Recent Submissions

PATIENT-PHYSICIAN GENDER MATCH AND THE PROMOTION OF PATIENT ENGAGEMENT STRATEGIES IN PRIMARY CARE
(McMaster University, 2025-04) Rojoub, Dalia; Acai, Anita; Psychology
Effective patient-physician collaboration enhances patient experience and improves treatment outcomes. Engagement strategies, such as shared decision making, can be implemented into healthcare settings to facilitate active involvement of patients in their care. However, patient gender, physician gender, and the interaction of the two may impact the effectiveness of these strategies. The aim of this study was to examine the effects of patient and physician gender on the perceived promotion of patient engagement strategies in primary care. An online questionnaire was administered to 708 McMaster University undergraduate students to assess their general engagement, shared decision making, and satisfaction with care. Participants were grouped based on their identified gender (man, woman, or gender minority) and their physician's identified gender (man or woman). A Kruskal-Wallis H test was then run to assess between-group differences. While overall engagement scores did not differ significantly, it was found that man patients with woman physicians scored significantly higher for shared decision-making and satisfaction as compared to their woman patient counterparts, regardless of physician gender. Additionally, the gender minority patients with woman physicians scored significantly lower than other groups for satisfaction with care. These findings challenge prior research suggesting that gender concordance improves engagement and highlight the need for more inclusive healthcare research and education that considers diverse gender identities.
Sulphur Isotope Effects in Chemical and Biological Processes
(1957-10) Ford, Richard; Thode, H. G.; Chemistry
The sulphur isotope effect in the oxidation of aqueous sodium sulphite with molecular oxygen has been measured under a variety of conditions. The observed effect is compared with theoretical calculations based on the reaction mechanism. The uncatalysed and enzyme catalyzed sulphur isotope exchange between sulphate and sulphite has been examined. The oxidation of sulphide to internally-stored sulphur and the subsequent oxidation of the sulphur to sulphate by Chromatium have been studied. Sulphur isotope fractionation in mixed cultures of Chromatium and Desulphovibrio desulphuricans has also been examined. The results are discussed in relation to the natural variations in sulphur isotope abundance.
A Study of the Thermal Performance of Short-Term Thermal Storage Using Phase Change Materials in Integrated Community Energy and Harvesting Systems
(2026) Hassan, Mohamed Safy Mostafa; Cotton, James; Lightstone, Marilyn; Mechanical Engineering
Thermal energy storage systems are essential for bridging mismatches between energy supply and demand, with sensible storage in water tanks being the most common storage medium. In large community systems, however, the size of these tanks becomes a major limitation. Integrating phase change materials (PCMs) into water tanks has emerged as a promising solution to overcome this challenge, as PCMs can significantly increase storage density by utilizing latent heat. The benefit of the latent heat energy storage is, however, hindered by the low specific heat of PCMs relative to water. Moreover, PCMs typically have low thermal conductivity, which influences heat transfer performance. As such, careful design of hybrid water-PCM tanks is required to ensure that the full latent heat capacity is utilized and that high energy density (relative to water alone) is achieved. The design of hybrid water-PCM tanks requires a systems context since the energy storage within the tank is determined by the operating temperature variations of the system. For example, because of the relatively low specific heat of PCMs, the benefit of a hybrid tank is enhanced when the operating temperature variation is low. In addition, due to the low conductivity of the PCMs, careful design of the PCM module is necessary to ensure that the PCM fully melts (or solidifies) within the available charging (or discharging) time. There is thus a need for mathematical models that can accurately predict the heat transfer and phase change characteristics of PCM modules while maintaining computational efficiency to allow for their incorporation into system analysis computer codes. The application of PCMs in long-term simulations, such as in community heating networks coupled with borehole fields, has been hindered by the computational cost of existing models which remain too expensive for simulations spanning months or years. This research addresses that gap by developing a reduced hybrid PCM–water tank model that is both accurate and computationally efficient, enabling the integration of PCM modules in community-scale energy systems to be studied in realistic, long-duration scenarios. This thesis presents a new reduced-order PCM model for spherical encapsulations. The model builds on the quasi-stationary approximation but introduces an effective-latent-heat formulation that captures both sensible and latent contributions. This modification significantly improves accuracy while reducing computational demand by up to two orders of magnitude compared to enthalpy-based models. The reduced PCM model was verified against a detailed benchmark conduction-dominated enthalpy model that is validated with experimental data from the literature. It was then integrated into a stratified tank framework, producing a reduced hybrid water-PCM tank model that is accurate, efficient, and suitable for long-duration simulations. To facilitate practical use, the model was implemented into the commercial code TRNSYS as a new component, Type 250, and applied in the context of integrated community energy systems to investigate the impact of adding PCM spheres to the water tank integrated with a borehole field thermal storage system. Parametric studies were performed on a hybrid water tank, revealing that its performance is strongly dependent on design and operating conditions. Higher mass flow rates shortened charging and discharging times but did not alter the total stored energy. Smaller spheres improved the melting rate, while larger capsules slowed it down. Lower temperature differences enhanced the PCM's latent heat contribution, increasing storage density but also extending charging times. Doubling the tank volume doubled the storage capacity, but it required higher flow rates to achieve a similar charging time. To guide system designers, a dimensionless contour map of PCM energy gain was developed, providing a simple tool for estimating the impact of capsule size, flow rate, and operating temperatures on the utilization of PCM. The reduced hybrid tank model was also applied to a community-scale Integrated Community Energy system with combined heat and power (CHP) units, short-term storage tanks, and a borehole field seasonal thermal storage. The results showed that PCM integration increased both the energy transferred to the borehole and the useful energy recovered from the CHP, especially at low CHP supply temperatures (i.e., 50°C). At higher CHP supply temperatures, the benefit of PCM diminished because most of the stored energy was in the form of sensible heat rather than latent heat. Notably, a 2 m³ tank with 50% PCM achieved higher energy density than a 4 m³ water-only tank, demonstrating the clear advantage of PCM integration in reducing the required tank volume. PCM also improved borehole performance by raising the average storage temperature, which enhanced the coefficient of performance of heat pumps and reduced compressor work during discharge. In summary, the contributions of this work include a new reduced PCM model that captures both sensible and latent heat while remaining highly computationally efficient; the development of a hybrid PCM–water tank model suitable for annual system simulations at low computational cost; the implementation of a new TRNSYS component (Type 250) to integrate the model into a widely used simulation platform; and the creation of a dimensionless contour map as a design tool for quickly estimating PCM performance under varying conditions. Finally, through a system-level case study, it demonstrated the tangible benefits of PCM integration in terms of tank storage density, CHP utilization, and borehole field performance, effectively overcoming the major barrier of high computational cost in detailed PCM models and enabling realistic deployment of PCM-enhanced hybrid tanks in community-scale energy systems.
Infant’s Motor System Responses to Temporal Structure in Music Beats
(2025) Vinod, Anagha; Xiao, Naiqi; Psychology
Beat perception reflects the brain’s ability to extract a regular pulse in auditory rhythms, an ability crucial for early language, social, and cognitive development. Studies in newborns and infants suggest an innate sensitivity to rhythmic structure, but the brain regions involved in infant beat-perception remain unknown. In adults, motor regions¬¬—including the supplementary motor area (SMA) and preSMA— are involved in beat perception. My study aimed to localize the brain regions involved in beat perception in infants. Particularly, I am interested in the motor system responses to rhythmic (Beat) and non-rhythmic stimuli (NonBeat). Using functional near-infrared spectroscopy, I measured localized changes in cortical brain activity in 53 infants aged 203.7– 456-days while they listened to Beat and NonBeat stimuli. A post-hoc median split on age was implemented, dividing participants into Younger (203.7-273.6 days) and Older (273.6-456 days) age groups. A paired t-test revealed a significantly greater motor region activation in response to Beat compared to NonBeat condition in the Younger group. In the Older group, a non-significant reduction in motor activity was observed in response to Beat stimuli compared to NonBeat stimuli, suggesting a trend towards suppression. By manipulating the stimuli loudness, the specificity of the motor system responses to beat stimuli was measured. No difference in motor system response to stimuli loudness was observed, showing the specificity of motor responses to beat processing. These results reveal notable differences in the motor system responses to rhythmic and non-rhythmic stimuli in Younger (203.7-273.6 days) and older (273.6-456 days) infants, suggesting developmental changes in motor system engagement with rhythmic stimuli across infancy.
Sedimentation of Fine SiC Particles During Liquid Processing of Al/SiC Composites
(1994-04) Owusu-Boahen, Kwame; Irons, G. A.; Materials Engineering
The settling of fine SiC particles (2.5 - 20 vol%) during liquid processing of Al/SiC composites has been studied by an electrical resistance technique. Settling rate data show that the settling of fine SiC in aluminum does not obey Richardson-Zaki relation, characteristic ofnon-flocculated systems. Rather the data reveal two distinct settling regimes, a (non-linear) rapidly decreasing settling rate regime (of higher than Richardson-Zaki predicted rates) and a linear(below Richardson-Zaki predicted rates) regime. The final settled bed in the aluminum-fine SiC with a concentration ofonly 0.28 volume fraction SiC, lacks the compactness ofrandomclose-packed arrangement (0.62 volume fraction), characteristic of non-flocculated systems. The system, in essence, cannot be non-flocculating and the suspicion is that there is an appreciable level of flocculation or clustering among these fine particles. At low SiC volume fractions (where settling rates are higher than predictions of the Richardson-Zaki relation) the flocs/aggregates probably settle individually. At high volume fractions of SiC (where settling is slower than expected), it is most probable that the aggregates settle together as a coherent network structure.

About MacSphere

Discover

Communities in MacSphere

Recent Submissions