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Transverse Relaxation Mapping of Deep Grey Matter in Mild Cognitive Impairment and Alzheimer's Disease
No full textAlzheimer’s disease (AD) is a progressive neurodegenerative disorder and the most common type of dementia. It impacts cognitive function, memory, and daily activities. The prevalence of AD is increasing worldwide due to aging populations, putting a burden on healthcare systems, caregivers, and society. Despite extensive research, early detection and effective intervention remain major challenges, as tissue damage from the disease begins years before noticeable symptoms emerge. Mild Cognitive Impairment (MCI) is considered an intermediate stage between normal aging and AD, marked by a measurable cognitive decline that does not yet disrupt daily activities. However, not all individuals with MCI progress to AD, highlighting the need for reliable biomarkers to predict disease progression.
Magnetic Resonance Imaging (MRI) has become a crucial tool in the study of AD and MCI, providing structural and functional insights into brain changes. Among different MRI techniques, transverse relaxation (T2) mapping has emerged as a valuable method for assessing microstructural changes in brain tissue, particularly in the hippocampus, a key region affected in early AD. Traditional MRI studies have largely focused on volumetric analyses, identifying hippocampal atrophy as a hallmark of AD progression. However, volumetric decline alone may not show the subtle early changes happening in brain tissue. T2 relaxometry offers additional insights into pathological changes such as neuroinflammation, iron deposition, and demyelination.
This thesis explores the application of T2 mapping in understanding the progression of AD and MCI, focusing on the hippocampus and other subcortical structures. The study uses longitudinal MRI data to track T2 and volume changes over 24 months, aiming to provide a more comprehensive view of disease progression. A key methodological aspect of this research is the use of an improved T2 fitting model that accounts for stimulated echoes and B1+ inhomogeneities, addressing limitations associated with conventional exponential fitting approaches. By integrating volumetric and T2 relaxometry analyses, this study seeks to enhance the understanding of microstructural alterations in AD and MCI.
A significant aspect of this research is its longitudinal design, which allows for tracking individual disease progression patterns over time. Most prior studies have relied on cross-sectional data, which offer only a snapshot of disease states. By analyzing MRI scans at multiple time points, this study aims to identify early indicators of AD progression. Furthermore, using advanced statistical methods, such as Analysis of Covariance (ANCOVA), enables a more precise evaluation of the effect of age and disease status on brain changes.
Identifying subtle microstructural changes in the hippocampus and other brain regions may help differentiate individuals at higher risk of progressing from MCI to AD. Additionally, the methodological advancements presented in this research contribute to improving the accuracy and reliability of T2 mapping as a quantitative MRI tool in neurodegenerative disease studies.
This study showed several key findings related to T2 mapping in Alzheimer's disease and Mild Cognitive Impairment. Our results confirmed that hippocampal T2 values exhibit significant changes in AD and MCI, with increased heterogeneity reflecting disease progression. In addition to hippocampal changes, we observed T2 changes in other deep grey matter structures, such as the thalamus and caudate, indicating broader neurodegenerative involvement beyond the hippocampus. Furthermore, using an advanced T2 fitting model improved the accuracy of T2 measurements, reducing systematic errors caused by stimulated echoes and B1 inhomogeneity. These findings indicate the potential of T2 relaxometry as a biomarker for early detection and disease monitoring in AD and MCI.
In summary, this thesis investigates the role of T2 mapping in AD and MCI, emphasizing its potential as a biomarker for early disease detection and progression monitoring. By combining volumetric analysis with advanced T2 relaxometry techniques, this study provides a more detailed characterization of neurodegenerative changes in the hippocampus and related brain structures
Understanding and Analyzing Effective Ad Design and Impact in the 2023 Alberta Provincial Election
No full textPolitical parties in Canada invest heavily in advertising to influence voter behavior, yet the effectiveness of these ads remains challenging to quantify. The introduction of the MetaTM Ad Library in 2019 has provided new insights into ad spending and targeting strategies for researchers, offering data on ad impressions, audience size, and expenditure. This study examines the impact of political advertisements during the 2023 Alberta provincial election, focusing on the use of advertisements on the MetaTM Ad Library.
My research in this project aims to evaluate the effectiveness of ad design and impact by analyzing data from the MetaTM Ad Library, specifically focusing on ad frequency, message repetition, framing, and design characteristics. The study applies principles from existing literature on ad effectiveness to assess the strategies employed by Alberta's New Democratic Party (NDP) and the United Conservative Party of Alberta (UCP) during the election period and what can be learned from it.
Key findings indicate that ad frequency, emotional framing, and video utilization significantly influence voter recall and ad performance outcomes. The study highlights the importance of message repetition and effective design elements, such as video length and text captions, in enhancing ad impact. The research concludes with recommendations for political advertisers to focus on these elements when designing future campaigns to maximize effectiveness and voter engagement
Sociocultural Determinants of Children’s Oral Health Among Immigrants: Developing and Testing a Conceptual Model
No full textAbstract
Background: The Canadian Collaboration for Immigration and Refugee Health highlights oral health diseases among the top 11 health challenges for immigrants and refugees. Foreign-born individuals face higher vulnerability due to migration-related disruptions and limited dental access. Cultural shifts, known as "acculturation," impact immigrants' health, varying in degree. Understanding this requires considering post-migration socio-cultural context. Social connections change post-migration, affecting oral health, well-being, and quality of life. Recognizing these shifts is crucial for stakeholders: dentists, community workers, and researchers. Social support is vital for new immigrants, aiding adaptation, and healthcare access. Both parental acculturation and support shape children's oral health. Their combined impact on oral health remains underexplored in existing literature.
Objective: The overarching objective of this research was to construct and assess a conceptual model aimed at predicting oral health behaviors and caries experience of immigrants’ children. The goal was to develop a model that explains the sociocultural factors influencing children’s oral health among immigrants, using Structural Equation Modeling (SEM).
Methods: This study unfolded in three phases, beginning with ethics approval from the University of Alberta Research Ethics Board (Protocol # Pro00072345). The first phase encompassed two systematic reviews: one focused on acculturation's impact on oral health among immigrants and ethnic minorities, while the other explored social support's influence on oral health in these groups. The second phase, a cross-sectional study, investigated how parental acculturation and perceived social support affected their children's oral health behaviors and caries experience. Participants included first-generation immigrant parents residing in Canada for two or more years, with children aged 2–12 years. Data collection took place in convenient community settings through multilingual community workers using non-probability snowball sampling. Parents provided demographic, perceived social support, acculturation, and children's oral health behavior data. Trained dentists conducted dental exams and used the DMFT/dmft index to assess caries experience. Oral health behaviors were measured with an eight-item questionnaire. The main independent variables were parents' perceived social support (PSS),
measured using the validated Personal Resource Questionnaire (PRQ2000) and parents' acculturation and strategies were evaluated with the Asian American Multidimensional Acculturation Scale (AAMAS). The data collected in the second phase informed the creation of a conceptual model in the third phase, aimed at predicting immigrant children’s oral health behaviors and caries experience through Structural Equation Modeling (SEM), examining parental acculturation and perceived social support's influences.
Results: A total of 336 parent/child pairs participated in the study. The average parental acculturation level was 10.46, and the average perceived social support (PSS) score was 63.27. Factors like length of residency, parents' education, and household income significantly predicted acculturation level. Parents with higher Canadian cultural knowledge reported more frequent children's toothbrushing. Parents of children consuming >1 sugary item/day had higher acculturation levels, English language proficiency, and Canadian food adoption. Parents of recent dental visitors reported higher assimilation and lower separation scores, while those visiting due to problems had higher marginalization scores. Parental acculturation wasn't significantly linked to children's dental decay (DMFT/dmft). Household income predicted parental PSS (B = -5.69). Children of parents with higher PSS brushed teeth ≥2/day. Parental education predicted social integration and nurturance; income predicted social integration, worth, and assistance. Parents with more intimacy and social integration were more aware of children's oral health. Parental social integration scores were higher when children consumed ≥1 sugary snack/day. All domain scores were higher when children brushed teeth ≥2/day. Structural Equation Modeling (SEM) indicated 77% of DMFT/dmft variance was explained by parental PSS, acculturation, predisposing/enabling factors, and children's oral health (OH) behaviors. Parental PSS had a direct effect on reduced dental caries and sugar consumption. Parental acculturation mediated by positive OH behaviors increased caries risk.
Conclusions: The SEM analysis found significant variance in immigrants’ children's caries experience. Findings highlight parental acculturation and PSS levels predicting oral health behaviors and caries. Recognizing sociocultural factors is vital for stakeholders—dentists, community workers, and researchers.
Immigrants' vulnerability to oral health issues underscores the need for deeper exploration and expanding the model
Update on the state of practice for energy measurements in the Standard Penetration Test
No full textThe Standard Penetration Test (SPT) is an in
situ test widely used to provide information o n soil
geotechnical properties. The SPT N value obtained from the test is commonly employed in various
geotechnical design correlations, particularly for soil characterization and foundation design. Although
the development and adoption of other in situ te sting techniques, such as the C one Penetration Tests
(C PTu and a variety of sensors available for deployment, SPT testing has continued to be a standard
part of geotechnical practice, especially due to its simplicity, ability to collect soil samples and l ow cost.
However, d
espite its simplicity and cost effectiveness, the SPT faces challenges in reliability due to
variability introduced by factors such as equipment calibration, operator inconsistencies, soil
heterogeneity, drilling disturbances, and impact energy transfer. Among these, the amount of hammer
energy delivered into the drill rods to the soil sampler is a critical factor affecting the SPT N value.
Research has shown that discrepancies in SPT N
values can be minimized through accurate energy
mea surements, obtained using specialized instruments such as strain gauges and accelerometers
mounted on the drill rods or anvil. These devices record force and velocity during the hammer's impact
to the anvil, allowing for the calculation of transferred ener gy through methods like force velocity
integration. By combining these measurements, engineers can determine the energy that reaches the
rods and compare it to the theoretical potential energy of the hammer's free fall. The ratio of measured
energy to theo retical energy, known as the Energy Transfer Ratio (ETR), provides insights into the
system's efficiency and highlights energy losses due to factors like friction, misalignment, or equipment
variability.
This study provides a comprehensive review of resear
ch and advancements in hammer energy
measurement techniques for the SPT, emphasizing their critical role in achieving more reliable N
values , and provides example estimates of the influence of this variability on the calibrated SPT N
value and interpretati on of geotechnical parameters from it . By addressing energy variability and promoting standardized measurement practices, the findings contribute to enhancing the accuracy of
geotechnical investigations and reducing uncertainties in engineering application s.
T
he work in this thesis then focuses on SPT tests with ener g y measurements in the field, under
controlled conditions to evaluate the efficiency of automatic hammers in SPT This is done by
comparing their performance with Pile Driving Analyzers (PDAs) under two testing methodologies:
continuous and resetting at every 18 inches. Data collected at varying depths examined the influence of
rod length and operational methodology on energy transfer dynamics. Results indicate that automatic
hammers consistently achieve efficiency values exceeding 80%, with variations influenced by testing
methods and depth.
The study underscores the need for continued innovation and standardization in SPT practices to
enhance geotechnical ana lyses and design outcomes globally , as well as the importance of energy
measurements to properly calibrate SPT N values and reduce the uncertainty in interpreted material
parameters from SPT tests
