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.

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

Communities in MacSphere

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Recent Submissions

A Hybrid Computer Simulation of the U-Tube Dynamics in Two-Phase Control Absorbers for Nuclear Reactors
(1975-09) Kwok, K.K.
This report presents the development of a mathematical model describing the dynamic behaviour of a two-phase (gas and liquid) control absorber. This new type of absorber, invented in Italy, is being developed at the Reactor Control Branch of the Chalk River Nuclear Laboratories, Atomic Energy of Canada Ltd., for possible use in future CANDU nuclear reactors. The purpose of the mathematical model is: (1) to provide a tool for evaluating experimental data from a two-phase absorber test rig. (2) for use in larger simulations to investigate the controllability of future CANDU power plants. The mathematical model of the two-phase absorber presented here includes the U-tube dynamics, return line dynamics, gas line dynamics and liquid line dynamics. However, only the U-tube model has been implemented on the Hybrid Simulator. It is based on the conservation laws (mass, energy and momentum) using cross sectional averaged variables. A continuous space discrete time scheme is used to solve the void propagation equation. The U-tube model has been tested with perturbations in both time and frequency domains. However, the remainder of the simulation needs to be implemented on a hybrid computer to provide the parameters for direct comparisons with experimental data from the two-phase absorber test rig.
Sex Differences in the Innate Immune Response to Pneumococcal Pneumonia
(2025) Zhao, Kevin
Men are more likely to acquire and die from pneumonia compared to women, however the mechanism underlying this phenomenon is not yet fully understood. Thus, we explored sex differences in the innate immune system and immune response to Streptococcus pneumoniae infection (the most common bacterial cause of pneumonia). Female mice had greater survival compared to males after low- but not high-dose S. pneumoniae infection. RNAseq analysis of their lungs 6 hrs post infection (p.i.) revealed that chemokine signaling was differentially expressed during infection by sex. Using flow cytometry, we found that female mice had a stronger monocytic response while males had a neutrophilic response. Females had greater bone marrow monocyte progenitor counts at 18 hrs p.i. while males had more bone marrow neutrophils. Female bone marrow monocytes also had higher CCR2 expression at this time. Female mice recruited more monocytes to their lungs and had higher interstitial macrophage levels after infection, while males had more rapid neutrophil recruitment. Female lungs also had higher local inflammation after infection, but that males had higher persistent systemic inflammation after infection. Female monocytes and macrophages produced more tumor necrosis factor (TNF) after low- but not high-dose pneumococcal stimulation. Although male monocytes and macrophages had higher TNFR and TLR2 expression, male macrophages also had higher levels of NF-κB negative regulator expression (A20, Otulin, Cyld, Cezanne), perhaps explaining their depressed cytokine production. Monocyte depletion during infection diminished the female survival advantage, suggesting that monocyte recruitment is protective during infection. During aging, we highlighted how female mice appear to exhibit more dramatic changes in peripheral monocyte counts, bone marrow progenitor frequencies, bone marrow monocyte CCR2 expression. Furthermore, aging may increase baseline lung inflammation and monocyte TNF production after pathogenic stimulus in females but not males. Our findings highlight how biological sex impacts the murine immune system, and especially on monocytes.
Video-guided Speech Inpainting
(2025) Kadkhodaei Elyaderani, Mahsa
The scoring economy: Reputation management in the age of algorithms
(2020) Berry, Pauline
We live in an algorithmic age, an age where algorithms influence our smallest, most miniscule choices to our largest, most life-defining decisions. The proliferation of algorithms and mounting public concern present challenges for not only individuals, but also organizations. The purpose of this study is to understand how and to what extent algorithms impact corporate reputation management. This research is quite novel in that it attempts to marry two fields that have yet to be united; notably, algorithms and organizational reputation management. Current research explores these topics independent of one another. This study intends to expand current research by highlighting the impact search engine and automated journalism algorithms have on organizational reputation management in hopes that it helps organizations better understand how to build and maintain their reputations – on and offline. The practical and social implications of this study are both educational and directional for both communications practitioners and organizations. The results of this research have the potential to alter the practice of reputation management altogether. The practical intent of this study is to provide communicators with a guide of how to mitigate and manage reputational issues that might arise from our new scoring economy.
The van der Waerden Simplicial Complex and the Lefschetz Properties
(2026) Ragunathan, Naveena
In this thesis, we examine the van der Waerden simplicial complexes, defined on two parameters n and k, and the Artinian rings we can form by modding out the squares of the variables from the Stanley-Reisner ring of the van der Waerden complex. We begin by providing a thorough background on all the necessary background, from abstract algebra, graph theory, and linear algebra. The main question investigated in this thesis is when the Artinian rings constructed from the van der Waerden complexes have either the Weak or Strong Lefschetz property. We examine for what values of n and k do these Artinian rings have the Weak, and in some instances Strong, Lefschetz Property. We focus on the smallest possible values of k, namely k = 1 and k = 2; and the largest possible value k can take, which is n − 1. We also focus on the case where k = 3, as the first instance of the failure of the Weak Lefschetz Property occurs here. We also investigate in what degrees the Artinian ring always has the Weak Lefschetz Property. We then give a characterization of when these simplicial complexes are pseudo- manifolds, which provides some further insight on what degrees the associated Artinian ring has the Weak Lefschetz Property. We conclude by providing some conjectures on both Lefschetz Properties, as well as further areas of possible future research. A Macaulay2 package on the van der Waerden simplicial complexes is also provided.

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