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Dietary vitamin B6 and the pathophysiology of non-alcoholic fatty liver disease
No full textNon-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver condition often linked to metabolic disorders such as obesity, type 2 diabetes, and dyslipidemia. NAFLD can progress to more severe conditions like non-alcoholic steatohepatitis (NASH), cirrhosis, and hepatocellular carcinoma. While lifestyle changes are currently the main therapeutic strategy, emerging evidence suggests that dietary micronutrients, such as vitamin B6, could play an important role in the development and progression of NAFLD through their involvement in one-carbon (1C) metabolism. This study aimed to explore the impact of dietary vitamin B6 deficiency on NAFLD progression using a high-fat high-sugar (HFHS) diet-induced mouse model. Thirty-two male C57Bl/6J mice were randomly assigned to four dietary groups with varying levels of vitamin B6. The study evaluated physical parameters, clinical markers, liver and fecal metabolites, and gut morphology after eight weeks of dietary intervention. Our findings demonstrated that vitamin B6 deficiency significantly influenced liver B6 levels, lipid accumulation, and key metabolites in the 1C metabolic pathway. Notably, animals in the vitamin B6 deficiency group exhibited reduced plasma triglyceride levels, elevated liver triglyceride content, and alterations in homocysteine and glycine levels, indicating disruptions in both lipid and 1C metabolism. Interestingly, fecal tryptophan metabolism was also impaired in these animals. These findings suggest that dietary vitamin B6 plays a crucial role in regulating NAFLD progression, particularly in the context of diet-induced NAFLD, providing insights into potential dietary interventions for disease management.Includes bibliographical references (pages 73-84
Enhancing the structure of design principles to support their reuse
No full textDesign principles aim to convey reusable prescriptive knowledge, supporting more rigorous
and transferable outcomes in design science research. However, many design principles are not
reused in practice. This study proposes a revised structure for design principles to enhance both
their perceived reusability and actual reuse. The new structure addresses two commonly cited
limitations: (1) unaddressed conflicts and (2) a lack of actionable detail. Results indicate that the
revised structure improves perceived reusability. Since perception alone does not guarantee use, I
also analyzed how participants applied the given principles in their final designs. Additionally, I
examined whether perceived reusability predicts actual reuse and whether adherence to the
principles improves design quality. The findings suggest that designers tend to reuse principles
when following the proposed structure, even if some principles make the final design more
complex. This study contributes to the literature on design knowledge formulation by providing
empirical evidence on how information design affects the reuse of prescriptive knowledge in
practice
Descriptive analysis of movement data based on multivariate movement patterns
No full textDescriptive analysis of data is an essential practice as it unravels the complexities
of data into human knowledge. One type of data can be the object of descriptive
analysis is movement data. Descriptive analysis of movement data when it involves
multivariate movement patterns suffers from certain shortcomings. For example, in its
current state, it is ineffective in the presence of many movement variables regardless of
the data being labeled or unlabeled. On a separate note, although the interpretation
of predictive models can produce patterns in form of interaction between variables,
no technique is available in cases where data is unlabeled. Finally, model interpretation
on movement data itself calls for improvement in three departments. First,
the current model interpretation tools are ineffective in higher dimensions. Second,
movement variables can be hard to interpret. Finally, predictive models are ineffective
in revealing weak and shared (between classes) patterns. Resorting to a number of
tools, in particular Feature Engineering, Outlier Detection, Topological Data Analysis,
and Association Rule Mining, this thesis introduces a collection of novel pipelines
to resolve the mentioned shortcomings. Various experiments with datasets of diverse
nature demonstrate that the introduced pipelines are effective in resolving the target
shortcomings. In particular, this thesis was able to identify the difference of behavior
in ship classes; find multivariate interaction patterns among ships, cyclones, foxes,
and soccer players; and find movement patterns in the mentioned datasets for the
majority of data instances when the datasets are high-dimensional
Populist rhetoric and contentious actions
No full textThis thesis examines whether populist rhetoric (often focused on dividing people) is associated
with people taking part in violent contentious actions (VCAs). To explore this question, a mixedmethods
approach was utilized. Firstly, using 2019's data from Global Party Survey, a proxy
variable for the usage of populist rhetoric was created for 140 countries. This variable was then
tested against the number of VCAs recorded in those countries using regression analyses and
ANOVA. Overall, no statistically significant relationships were found between the level of
populism and the number of VCAs, though we found a statistically significant interacting effect
for political stability on the relationship between populist rhetoric and the number of VCAs -i.e.
the more politically unstable a country was, the more populist rhetoric affected the number of
VCAs in a given country. Secondly, a media analysis was conducted in three countries showing
different levels of populism (Belize, Pakistan, and Nigeria) to cover government discourse
surrounding local VCAs. This underlined the importance of opportunity structure when analysing
the sources of violent conflict. Finally, the study also identifies key limitations, such as differences
in party popularity, funding, and number of political actors, which could all affect public exposure
to populist rhetoric and offer promising directions for future research
Enforcing physical constraints in physics-informed DeepONets: a conservative approach to approximating solution operators of differential equations
No full textDifferential equations are fundamental to modeling real-world phenomena across science
and engineering, but solving them analytically is often infeasible, necessitating
effective numerical approximations. Traditional methods devised for this purpose,
such as finite differences and spectral methods, often face challenges like high computational
cost and scalability issues, especially in high-dimensional settings. Recently,
machine learning approaches such as Physics-Informed Neural Networks (PINNs) and
Deep Operator Networks (DeepONets) have emerged as promising alternatives, with
DeepONets being capable of learning the solution operators of differential systems.
However, standard DeepONets often require large datasets during training, and may
produce solutions that violate physical constraints. To address these limitations,
we consider Physics-Informed DeepONets (PI-DeepONets), which incorporate the
underlying physics of the system to eliminate data dependency. The main contributions
of this thesis are twofold. First, we propose a modification to the standard
PI-DeepONet architecture by integrating known conserved quantities into the model,
enhancing training efficiency and reducing prediction errors. Second, we introduce a
dedicated conservative layer within the PI-DeepONet framework in order to enforce
conservation laws during the training process, and to ensure physically consistent
solutions. We demonstrate the effectiveness of this approach on several systems of
ordinary differential equations, showcasing its ability to produce accurate, efficient,
and physically meaningful approximations
Development of an ultra-wideband timestamp-based scalable passive indoor localization system
No full textThe overall objective of this thesis is to develop a scalable passive UWB localization
system for GPS-denied indoor environments. This work aims to overcome the inherent
drift in odometry-based systems while providing absolute position measurements. The
system is intended for deployment in large indoor environments such as warehouses,
shopping malls, and transportation hubs, where it can support a range of applications,
from smart location services, assisting pedestrian navigation, to enabling autonomous
robot navigation.
The novel design is based on tightly coupled dynamics of the reception timestamps
and the location, and addresses the scalability problems in existing ultra wideband
UWB systems while exploring the limits of connectivity, transmission interval, and
connection interruptions with the network.
As the first step towards scalable passive localization, the network synchronization
problem is addressed. An improved version of the gradient clock synchronization
(GCS) algorithm is used here due to its significant advantages from the fully
distributed ad-hoc nature. The proposed asymptotic GCS algorithm resulted in improved
accuracy and robustness by achieving asymptotic stability in clock rate error
states.
Passive localization methods using the messages from a synchronized UWB network
are then explored. This involves extracting range information from timestamps,
and usually achieved by calculating the time difference of arrival (TDOA) measurements.
However, TDOA methods can suffer from subpar geometric constraints as well as errors caused by clock dynamics. Throughout this thesis, three different localization
algorithms are evaluated and compared against each other.
The first method uses traditional TDOA measurements with a novel clock rate
correction framework. The decoupled 3-state clock tracking filter enables to track the
clock rates for longer time durations, enabling longer network transmission intervals
and improved accuracy. The clock phase tracked by this filter is not accurate enough
to obtain one-way time of flight measurements. Yet, the clock rate tracked by the
filter is well capable of providing rate corrections to TDOA measurements even when
the transmission gaps are in the order of milliseconds.
The second method is a novel one-way time-of-flight-based passive UWB inertial
navigation solution using a tightly coupled error state Kalman filter. This solution
utilizes spherical constraints provided by one-way TOF measurements, which are more
profound when compared to TDOA measurements, resulting in improved localization
precision from the same data. The proposed tightly coupled time of arrival (TCTOA)
approach achieves passive synchronization by keeping track of the local clock
and its derivatives as states. Using these states and position estimates, the reception
timestamps of the network messages are predicted. The errors in these predicted
timestamps are then used to update both clock states and the position states through
accurate modeling of coupled interactions.
The third method investigated here is an optimization-based solution utilizing the
same tightly coupled model as in the second method. This solution is expected to
have improved robustness and consistency among temporary unobservable windows
due to connection loss over the filter-based method. IMU preintegration is being
used to minimize the computational overhead of the system. This optimization-based
solution resulted in improved robustness and accuracy when compared to the filterbased
solution, although the computational cost is relatively high
Evaluation of heterogeneity of electromagnetic (E-M) properties of quartz and mafic formations
No full textGround Penetrating Radar (GPR) is a near surface Electro-magnetic (E-M) imaging method used
for a wide range of applications in environmental, geotechnical, and mining engineering. In the
emerging practice of GPR for mineral exploration, techniques similar in principle to the seismic
reflection method are used except that it is based on the propagation and reflection of E-M waves
rather than elastic waves. With an adapted borehole GPR configuration, the technique exploits the
contrast in E-M properties at the near-borehole whereby the delineation of physical boundaries
such as the change in geological composition can be acquired with appropriate data acquisition
and processing. Signals corresponding to GPR signature depend on a multitude of E-M properties
such as dielectric permittivity (ε), electrical conductivity (σ) and magnetic permeability(μ),
which influence the velocity, attenuation, reflection, refraction and transmission of radar waves.
Accurate analysis of GPR survey data, including reliable identification of geological formations
and precise placement of geological interfaces, requires accurate values of these electrical and
magnetic properties. However, many common assumptions are made in acquiring, processing,
modeling and interpreting GPR data. Each assumption has limitations with consequences that can
lead to misinterpretation of the data. Magnetic properties, for example, are often assumed to be
those of a vacuum or free space and oftentimes the relationship between transmitter output
frequency (Hz) and the magnitude of E-M properties is misrepresented. A similar
misrepresentation is also observed in the literature when considering rock core bench scale or insitu
test for individual E-M properties, in particular with the frequency of measurements and the
level of structural and mineralogical heterogeneity in the specimens.
In this investigation, an array of testing methods was utilized to measure the E-M properties of 34
NQ core intervals from a mafic (host rock) and a felsic (source rock) geologic zone (low lossy)
from a narrow gold vain type deposit. Where appropriate, testing at multiple frequencies was done.
A comprehensive statistical analysis of the testing data was conducted. E-M property magnitudes
were determined and compared to that of literature taking into consideration the GPR testing
frequency used under field conditions (~ 500 MHz). Results from the data analysis indicated that
laboratory scale measurements can be influenced by the type of sensors used, the signal frequency
and the levels of sample heterogeneity
Understanding oil refinery corrosion by naphthenic acid: a chemical approach
No full textNaphthenic acid (NA) causes significant financial losses in the petrochemical industry.
NA is generally found in crude oil. The infrastructure of the petroleum industry is
commonly made up of carbon steel and 316L steel. This study examines physical
changes, chemical changes, and corrosion rates caused due to NA.
The study of physical changes reveal a blackish color observed in NA, as the corrosion
process progressed. The carbon steel’s structural damage was observed through
microscopic study. SEM analysis shows that cavity corrosion occurred, and 316L steel
shows metastable pitting corrosion on the steel surface. XRD analysis indicates higher
structural phase changes in the carbon steel lattice and expansion in the FCC lattice
is observed in 316L steel, at elevated temperatures. ATR-FTIR spectroscopy shows
the formation of unidentate, bidentate bridging, and bidentate chelate complexes. At
higher temperatures, NA shows increased formation of bidentate chelate complexes
compared to unidentate complexes. Thermal impacts show a change in NA and the
formation of esters, acid anhydrides, multimers, or dimers. The asymmetric Fe-NA
CO stretching shows a shift toward lower wave numbers compared to Ni-NA. The corrosion
behavior indicates that Fe powder corroded faster than carbon steel; however,
316L steel shows greater resistance at room temperature. Over time, carbon steel
corroded by NA shows an increase in the formation of bidentate chelate complexes
compared to Fe powder corroded NA at room temperature.
This research provides a deep understanding of NA corrosion and provides valuable
information for corrosion examination and mitigation in oil refineries
Parents' and guardians' experiences in accessing autism spectrum disorder diagnostic services for children
No full textBackground: Since 1990, there has been a global increase in the incidence of Autism Spectrum Disorder (ASD). As a result, there are additional demands for assessment, diagnostic, and treatment services, already identified as being inadequate in many jurisdictions. Early identification and diagnosis of ASD is a priority because the best chance of improving symptoms occurs through early and intensive interventions. A definitive diagnosis is often a prerequisite for children to access publicly funded healthcare services when available. Yet obtaining a diagnosis in itself can be stressful, frustrating, and time-consuming for many parents. It is important to understand parents’ experiences and the barriers they face in the process of accessing autism spectrum disorder diagnostic services for their children.
Aim: To examine parents’ experiences in accessing autism spectrum disorder diagnostic services for their children and the barriers they face in that process.
Methods: Qualitative research methodologies were used that included: grounded theory, descriptive exploratory methods, and the Joanna Briggs Institute methodology for systematic reviews of qualitative evidence. Analysis of interview data included constant comparative analysis, reflexive thematic analysis, and systematic data synthesis. A total of 32 parents and caregivers of children and youth diagnosed with ASD participated in in-depth, semi-structured interviews. The systematic review included 36 studies that varied in qualitative research designs with high methodological quality.
Results: Parents’ experiences in accessing timely autism spectrum diagnostic services are impacted by factors that include: parents’ skills and capacity to advocate on their child’s behalf, severity of the disorder, time commitments involved in parenting a child with the disorder, perceived stigma related to their child’s diagnosis, delays in accessing diagnosis and supportive
services, lack of information provided to them by healthcare practitioners, lack of availability of diagnostic services, encountering healthcare professionals with a lack of specialized knowledge, experienced confusion surrounding inaccurate or mixed diagnosis relating to co-morbidities, and socioeconomic and cultural disparities.
Conclusions: There is a need to address wait times for services, and provide education and support services to parents and healthcare providers. These support services should focus on improving self-advocacy skills and reducing contextual and systemic barriers to accessing autism spectrum disorder diagnostic services including socioeconomic and cultural disparities. Study findings indicate further recommendations for policy, practice and research.Includes bibliographical reference
Experiential learning and work placement impact for high school students: the need for high school cooperative placements
No full textThis thesis explores the role of experiential learning in helping high school students understand
their individual talents, interests, and purposes, with a particular focus on cooperative
placements. The sections of this study investigate the direct effects these placements have on
students' engagement and practical understanding of their chosen fields, highlighting the ways in
which hands-on experiences contribute to more meaningful connections with their academic and
career goals and discusses how these experiences facilitate a clearer understanding of individual
abilities helping students with their career planning and individual decision-making.
Furthermore, this study explores how real-world experiences shape students' choices in their high
school courses and explores their readiness for post-secondary education and career pathways.
An exploration of methodological approaches are presented throughout this investigation,
addressing a different aspect of experiential learning and its impact on high school students. The
thesis aims to contribute to a deeper understanding of how experiential learning can enhance
educational outcomes by aligning students' academic experiences with their personal and
professional aspirations, personalizing education for each student.Includes bibliographical references (pages 93-103