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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Communities in MacSphere

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Recent Submissions

An Economic Impact Analysis of the 2025 St. George Apple Fest in Brant County
(Prepared by the McMaster Research Shop for St. George Apple Fest, 2026-01) Cheetu, Shruti; Koptev, Egor; Mahajan, Arnav; Monkman, Eliott; Johnson, Sonia
The St. George Apple Fest is an annual event that attracts thousands of visitors and contributes to Brant County’s economy. This report evaluates the 2025 festival’s economic impact to provide organizers with reliable data to support funding, sponsorships, and municipal reporting.
INVESTIGATING THE NEURAL MECHANISMS AND THERAPEUTIC EFFECTS OF FMRI- AND EEG-BASED NEUROFEEDBACK IN POST-TRAUMATIC STRESS DISORDER
(2026) Jonathan Lieberman
Post-traumatic stress disorder (PTSD) is a prevalent and debilitating condition that often develops following trauma. Concerningly, many individuals struggle to tolerate or fully respond to existing first-line treatments. Although PTSD is associated with widespread disruptions in brain function—including hyperactivity and altered connectivity in regions such as the amygdala and posterior cingulate cortex (PCC) during both rest and trauma-related processing—this rapidly expanding neurobiological understanding has yet to be fully translated into clinical care. This dissertation investigates neurofeedback, a non-invasive method that provides real-time information about neural activity to support targeted self-regulation, as a neurobiologically informed adjunctive intervention for PTSD. Across a series of studies, it examines the therapeutic effects and underlying neural mechanisms of both functional magnetic resonance imaging (fMRI)- and electroencephalography (EEG)-based neurofeedback, the two predominant neurofeedback modalities. The findings demonstrate that individuals can learn to modulate PTSD-associated neural alterations and achieve meaningful reductions in symptoms following neurofeedback training. In addition, this work delineates the neural mechanisms associated with several distinct neurofeedback protocols and evaluates key methodological factors that shape both neural and therapeutic outcomes. Together, these studies advance a mechanistic understanding of how neurofeedback exerts its therapeutic effects in PTSD and provide empirical support for its use as a promising adjunctive treatment.
TRABECULAR BONE TEXTURE IN RADIOGRAPHS OF THE KNEE
(2005) Patrick Emond
Tibio-femoral osteoarthritis (OA) accelerates the degeneration of cartilage which alters the biomechanical environment surrounding the joint. As stresses applied to the proximal tibia increase, subchondral cancellous bone remodels itself in response to biomechanical changes. In order to detect the changes in subchondral trabecular bone, radiographic texture in regions of interest (ROI) in the medial and lateral compartment of the proximal tibia were examined. Dominant knees of 151 subjects were radiographed using the fixed flexion technique. Two radiologists independently graded each radiograph accord ing to Kellgren-Lawrence (KL) scoring. Two ROIs were selected to contain a representative sample of the trabecular pattern in the tibia. Run-length and trabecular strut analysis were applied to measure several indices of ra diographic texture. Aggregate reproducibility of the indices were assessed by analysing duplicate radiographs of 12 patients acquired 1-week apart. In general the reproducibility of the run-length indices were < 5% compared to those derives from strut analysis (< 10%). There was strong evidence of structural change in trabecular bone pattern in groups of subjects with differing Kellgren-Lawrence (KL) scores. For example, the difference in bone surface (p<0.05), bone volume (p<0.0001), trabecular spacing (p<0.005) and connectivity index (p<0.05) were statistically significant between subjects with KL scores of 4 and <1. In subjects with moderate osteoarthritis (KL=2,3), there was a non-significant trend to have greater apparent bone surface and bone volume, reduced trabecular spacing and greater connectivity as identified by strut analysis. It was found that structural change in trabecular bone can be identified by computer-aided analysis of radiographs of osteoarthritic knees. However, this change could not be identified in non-severe OA without greater statistical power.
FLOW AND HEAT TRANSFER PHENOMENA IN A 90° BEND
(1964-11) William Schneider
This paper deals with the overall performance of a two-dimensional, 90°, potential flow bend having a contract ion ratio of 2:1 and using air as the working fluid. It deals as well with the effect on the boundary layer and the heat transfer rate at the inner bend surface due to the cooling and curvature of the inner wall. The overall characteristics of the bend are reported for four inlet velocities from 60 to 175 ft./sec. Static pressure distributions for the inner and outer walls of the bend and velocity and turbulence profiles at the bend inlet, mid-bend, and bond outlet are given. Both the pressure dis tributions and the velocity profiles are compared to those predicted by ideal potential flow and neglecting the velocity decay at the walls due to the boundary layer, agreement is very good. The characteristics of the boundary layer formed at the inner surface of the bend arc reported for the four in- let velocities. Velocity profiles are plotted for isother mal flow conditions in dimensional form, universal velocity profile form, and logarithmic form. The effects on the velocity profiles due to varying inlet velocities and temp erature differences between the wall and the flow’ of up to 60°F are shown to be small. The temperature profiles for all the variations of speed and temperature difference are shown and as the temp erature difference increases the temperature boundary layer thickens slightly. The convective heat transfer coefficient is reported for a point on the inner surface at raid-bend. Evaluations by the accepted heat transfer correlation and from shear stress results agree but actual measurements using a heat flow transducer show that the heat transfer rate is substan tially reduced due to the effect of curvature. These re ductions in heat transfer occur in a region where the accel eration which the flow experiences due to turning is from 730 to 3,3'30 times the acceleration duo to gravity.
THE DETERMINATION OF PORE SIZE DISTRIBUTION AND SURFACE AREA FROM ADSORPTION ISOTHERMS
(1954-10) Eva Voigt
Theoretical isotherms have been developed which when com pared to experimental isotherms showing hysteresis, allow the calculation of pore size, pore size distribution and surface area of the sorbent. Interpretation of some experimental iso therms obtained with porous vycor glass shows that this system can best be represented by the ’’ink bottle” pore model with a Gaussian distribution of pore sizes. The mean pore radius of the porous glass is about two thirds of the Kelvin radius, and the surface area about twice that obtained from the B.E.T. theory. The Kelvin radius is interpreted as a weighted aver age, but the B.E.T. surface area appears more fundamentally different. As a consequence of the present theory multilayer adsorption, as opposed to capillary condensation^seems highly improbable on porous glass

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