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The influence of sex, body composition and training status on neuromuscular measures of the bicep brachii
No full textThe purpose of the study was to determine how sex, body composition, and chronic resistance training influence corticospinal excitability (CSE) of the biceps brachii. Fifty participants including 15 male resistance trained (male RT), 15 non-resistance trained (male non-RT), 10 female RT, and 10 female non-RT participated in this study. Anthropometry, body composition, and biceps brachii subcutaneous fat and muscle thicknesses were recorded. Participants were then asked to performed maximum voluntary contractions (MVC) of the dominant elbow flexors (3×5s). Following the MVCs, peak twitch force (via motor point stimulation at rest) and maximal compound action potential (Mmax, via Erb's point stimulation) (during 10% MVC) were assessed. Next, participants received transcranial magnetic stimulation (TMS) to determine resting motor threshold (RMT) and active motor threshold (AMT) of the biceps brachii. After 3 min rest, participants performed the interpolated twitch technique (ITT) to determine voluntary activation (VA). Five minutes following the ITT participants performed 14, 5s contractions at 10% MVC. During the 10% MVC participants received TMS or an Erb's point stimulation at 2.5 seconds. A main effect of training demonstrated that RT participants exhibited significantly greater muscle thickness (28%), motor evoked potential (MEP) amplitude (81%), and Mmax amplitude (79%), alongside shorter half relaxation time (½RT) (19%) and MEP latency (9%) compared to non-RT participants (all p<0.05). RT participants also demonstrated lower body fat percentage (38%), fat mass (45%), and subcutaneous fat thickness (48%). A significant main effect of sex demonstrated that males exhibited greater muscle thickness (64%) but lower body fat percentage (24%) compared to females. Regression analyses revealed that training status was the strongest positive predictor of both MEP and Mmax amplitudes, while higher fat indices were negatively associated. Notably, muscle thickness increased MEP only in trained individuals, with effects differing by sex. This study highlights the sex-specific neuromuscular and corticospinal adaptations, with body composition playing a key role in modulating excitability. These findings highlight the importance of considering central and peripheral factors, and interpreting normalized excitability measures cautiously, when assessing training effects
Characterizing the role of creatine precursors, methionine and guanidinoacetic acid, on gut creatine transport and uptake in skeletal muscle cells using in vitro models
No full textWhile creatine supplementation has become increasingly popular, solubility is low, making supplementation costly. Studies have proven that GAA, a direct precursor of creatine, is a suitable alternative to improve creatine stores in the body and that supplementing GAA with creatine also enhances creatine and GAA levels in the body. Meanwhile, recent studies from our lab reported that methionine, another precursor of creatine, enhances GAA uptake in the body, consequently increasing creatine stores. However, we do not know if supplementing GAA and methionine together will maximize creatine transport. The rationale behind this study was to use in vitro models to elucidate the underlying transport mechanisms of creatine under these conditions. We hypothesized that combining methionine and GAA would further enhance the transport of creatine. Given their similarity in function to gut epithelial cells, Caco-2 cells served as a suitable model to study gut transport. We incubated the cells with radiolabeled isotopes and measured transport across cells. The results showed that GAA did not affect the rate of creatine appearance in the serosal chamber. Further experiments also showed that pairing methionine and GAA did not significantly impact the rate of creatine transport in the gut or uptake by skeletal muscle cells. Interestingly, we found that high systemic creatine significantly enhanced GAA appearance in the serosal chamber when serosal creatine was three times the concentration of luminal GAA. We concluded from these findings that while methionine and GAA did not enhance overall creatine transport, the serosal concentration of creatine can influence the transport of the creatine precursor GAA in the gut. In addition, we concluded that the basolateral membrane is the principal site of GAA transport regulation in the gut
Effects of dysfunctional career beliefs and university’s environment and support system on university students’ entrepreneurial intention
No full textThis thesis investigates the effect of dysfunctional career beliefs (DCB) and a university’s environment and support system (ESS) on entrepreneurial intentions (EI) among students at Memorial University of Newfoundland. The analysis is divided into two components: a cross-sectional study investigating how DCB influence EI and their effect on the relationship between ESS and EI; and a longitudinal study assessing ESS’s impact on EI and its antecedents over time. The study is grounded in the Theory of Planned Behavior, a well-established psychological theory that predicts human behavior, and employs Partial Least Squares Structural Equation Modeling (PLS-SEM) to analyze data, with longitudinal data spanning 2020 to 2024, capturing changes in ESS influence amid economic fluctuations. Findings reveal that students with high decision-criticality DCB tend to perceive entrepreneurship more favorably, indicating that such beliefs may frame entrepreneurship as a purposeful career choice. DCB in professional help also shapes ESS effectiveness, underscoring mentorship’s role in university support systems. The longitudinal analysis shows that ESS’s influence on EI varies with economic conditions but consistently supports ATB and PBC. This research advances the understanding of how psychological barriers and support systems intersect to shape entrepreneurial paths in higher education. It discusses practical implications for universities, career counselors, and policymakers, such as the need for adaptable ESS frameworks, targeted interventions for dysfunctional beliefs, and expanded mentorship networks. These recommendations are based on the findings of this study and can be directly applied to improve entrepreneurial education. Future research directions include further exploration of DCBs, cross-cultural studies, and developing ESS models resilient to economic fluctuations
Characterizing the coastal benthic ecology of two regions of Inuit Nunangat using machine learning
No full textUnderstanding the benthic ecology in Canada's Northern coastal areas allows for informed decision-making in their use as the Arctic undergoes rapid changes. Two regions of Inuit Nunangat (Inuit Homelands) were studied: Nunavut and Nunatsiavut. Multibeam sonar provided continuous-coverage geomorphology data, while video ground-truthing enabled us to validate sediment characteristics and benthic community distribution in the estuaries studied. Random Forest Modelling (RF) and Species Distribution Model (SDM) were employed to better understand and visualize environment-benthos relationships across the study areas. Key findings reveal that positioning within the fjord, terrain curvature, and estuary orientation to oceanographic forces are primary factors influencing benthic distribution across all study sites. The findings support the recent negotiations for the establishment of an Inuit Protected Area in Nunatsiavut and provide valuable ecological data for future marine management plans in the Canadian Arctic.Includes bibliographical references (pages 50-60
Maternal omega-3 polyunsaturated fatty acids alter the fatty acid profile and schizophrenia-like deficits of a C57BL/6 MIA mouse model and their offspring
No full textSchizophrenia (SCZ) is a complex neurodevelopment disorder linked to pre-natal and post-natal brain development. Maternal immune activation (MIA) and nutrition, particularly omega (n)-3 polyunsaturated fatty acids (PUFA), influence fetal brain development. This study investigates maternal n-3 PUFA intake during the third trimester and lactation in a C57BL/6 MIA mouse model, focusing on red blood cells (RBC) and brain cortex tissue fatty acid profile (for dams and adult offspring), along with SCZ-like behaviour changes (for dams, juvenile, and adult offspring). Pregnant C57BL/6 mice received lipopolysaccharides (0.1mg/kg) or saline on gestation day 14.5 and were fed a high or low (5.5%, or 1% of total fatty acids) n-3 PUFA diet (20%w/w fat) until post-natal day (PND) 21. All mice were then switched to standard chow diet. Behaviour tests were conducted after PND 21 and dams were sacrificed. Offspring continued on a chow diet, underwent behavioural testing after PND 60, and were then sacrificed. For the first time, I report MIA dams on a high n-3 PUFA diet had elevated RBC and brain n-3 PUFA levels, while adult offspring RBC and brain DHA remained unchanged. Maternal n-3 PUFA intake did not prevent SCZ-like behavioural deficits. Diminished adult effects of diet in dams underscore the need to maintain n-3 PUFA intake post-weaning
A day in the life: exploring exposure to unhealthy food marketing in youth living in Newfoundland and Labrador through a novel mobile application
No full textChildren are exposed to food marketing in multiple settings, influencing their food attitudes
and behaviours. This thesis aimed to test the feasibility of a mobile application to assess food
marketing among youth aged 13-17 years (Manuscript 1) and explore youth perspectives and
experiences with food messaging (Manuscript 2). Twenty-three participants took photos of
food marketing they saw over three days. Each completed a feedback survey on feasibility
(ease of use, convenience, responsiveness, navigation, training resources, and willingness to
use again) and a focus group sharing their experiences with the app and food messaging.
Thematic analyses, descriptive analyses, app-derived feasibility metrics and Fisher’s exact test
were conducted in Manuscript 1. Results showed high response and completion rates (85.2%
and 92%). It also showed high usability and acceptability of the application. Focus groups
showed satisfaction with the application’s interface and functionality. Photo content analysis
and focus group thematic analysis were conducted in Manuscript 2. Focus groups showed that
deals, celebrities and characters influenced product purchases. Price-based promotions were
the most common marketing indicator in participants’ photos (34%). This thesis found that the
mobile application has potential for monitoring food marketing across multiple settings and
showed how marketing messages encourage unhealthy food intake.Includes bibliographical references (pages 99-118
A swing in the forest
No full textThis young adult novel investigates girlhood and coming-of-age through a supernatural
lens. The novel follows an anxious preteen protagonist named Paul (short for Paulina).
Paul’s parents sign her up for a summer-long arts camp where she develops an unhealthy
obsession with one of her counsellors, Gabriel. When her best friend, Nora, joins her at
the camp, Nora thrives with the artsy kids while Paul remains isolated and can’t seem to
fit in, causing a rift between the two girls. Paul notices strange behaviour from Gabriel
and begins to suspect that he might not be who he says he is. She gathers evidence to
figure out what’s really going on with him and to win her best friend back—she needs
Nora and their friendship to solve this. Lycanthropy is used to explore themes of
communication, isolation, mental health, liminal spaces, gender and queerness, domestic
violence, the climate crisis, feminism, and the uncomfortable transformation of puberty
Investigating the response of small-diameter buried steel pipes to axial ground movements
No full textSmall-diameter steel pipes are widely used for energy transportation to domestic supplies across Canada. These distribution pipelines often encounter ground movement, leading to pipe distress and failures. This research focuses on the responses of distribution pipes to axial ground movement using full-scale tests and numerical modeling. In the full-scale laboratory tests, a soil box was moved axially at a constant speed while a steel pipe buried in the soil box was restrained at one end, simulating the axial ground movement. Three different pipe diameters (26.7 mm, 60.3 mm, and 114.3 mm) were studied. Two compaction techniques, namely, hand tamper compaction and vibratory plate compaction, were used to examine the effects of different backfill compaction methods. The soil box was moved at three constant speeds (0.5 mm/min, 1.0 mm/min, and 2.0 mm/min) to observe the impact of varying ground displacement rates. Strain at the pipe’s restrained end and pipe elongation were also measured. The test results for the 114.3 mm pipe at a pulling rate of 0.5 mm/min were simulated using finite element (FE) analysis to examine the soil-pipe interaction numerically, which could not be measured during experiments. The effect of interface dilation was found to be negligible in the numerical simulation, indicating that the increase in axial soil resistance on the pipe under dense sand conditions was most likely due to compaction-induced ground stresses and the surface roughness of the pipe. Three different approaches were employed to simulate the compaction-induced ground stresses and the resulting peak axial soil forces for the 114.3 mm diameter pipe. The effect of pipeline misalignment on the results was also studied using FE analysis.Includes bibliographical reference
Analysis of Protein Kinase D1’s role during reactive oxygen species-mediated signaling
No full textProtein Kinase D1 (PKD1) is a critical component of cellular responses to reactive oxygen
species (ROS)-mediated apoptosis. Previous studies demonstrated that upon oxidative stress,
PKD1 is activated through a signaling pathway mediated by the Src/Abl non-receptor
tyrosine kinases. Subsequently, PKD1’s translocation to different cellular compartments can
regulate gene expression and promote cell survival through the NF-kB signaling pathway.
Additionally, PKD1 deficiency increases ROS sensitivity in mouse embryonic fibroblasts
(MEFs), leading to mitochondrial membrane depolarization and apoptosis when exposed to
oxidative stress. Our study examined PKD1’s protective role against oxidative stress-induced
apoptosis and its impact on gene expression. Using wild-type (WT) and PKD1-deficient
(PKD1-/-) MEFs, we found that the absence of PKD1 significantly increases oxidative stressinduced
apoptosis, as evidenced by H₂O₂ stimulation and serum starvation experiments. To
better understand the molecular mechanisms underlying PKD1's protective function, RNASeq
analysis was performed, comparing gene expression levels between WT and PKD1-/-
MEFs. RNA-Seq analysis revealed differentially expressed genes (DEGs) between WT and
PKD1-/- genotypes, with 383 DEGs in primary and 1705 DEGs in immortalized MEFs.
Notably, BCL2L11 (BIM), a pro-apoptotic protein, was more than two-fold down-regulated
in both primary and immortalized PKD1-/- MEFs, suggesting its interaction with PKD1 on
the mitochondrial outer membrane through the mitochondrial apoptosis pathway. In addition,
KEGG pathway analysis highlighted enriched differentially expressed pathways, including
those associated with apoptosis, cell survival, and response to oxidative stress. This study
sheds light on how PKD1 defends against oxidative stress and influences gene expression,
potentially contributing to the development of treatments for oxidative stress-linked diseases.Includes bibliographical references (pages 101-116
Deep learning studies on molecular properties prediction
No full textThe use of deep learning in fundamental sciences has increased significantly. This
suggests that it may replace some traditional methods in computational chemistry,
biology, and related fields. In Quantum Mechanical (QM) methods, calculating the
total energy of molecules requires considerable computational effort. One must solve
the Hartree-Fock (or Kohn-Sham in the case of Density Functional Theory (DFT))
equations; the time required depends on the number of nuclei, electrons, and a number
of basis functions, scaling exponentially. However, Machine Learning (ML) methods
might be used instead of QM methods, which have less computational time and
reasonable accuracy. Machine learning has been proven to be computationally cheaper
than methods such as DFT.
Recently, many studies utilized deep learning techniques for prediction in QM
functional theory energies, drug discovery, material properties, etc. To perform predictions
of molecular properties, we should start with some raw data such as Cartesian
coordinates of atoms and the charges. However, machine learning models cannot be
directly fed with these features. The predictor property should be invariant toward
rotation, translation, and permutation.
This thesis investigates Deep Neural Networks (DNN) to predict Hartree-Fock
energies utilizing an interactive computational chemistry repository platform called
Retrievium, which consists of chemical structures of different sizes computed by
Gaussian software. Different models have been investigated in this study, such as
a matrix-based descriptor model, which utilizes both Convolutional Neural Network
(CNN) and Multilayer Perceptrons (MLP) networks; ReMLP-NET, which employs
MLP network, and a Transformer-Potential utilizing a Transformer Encoder architecture.
These methods are all compared to each other, and we have discussed their
pros and cons. They also have been compared with one of the well-known models,
ANI, and the results show that our models perform appropriately in the employed
datasets