title: Multi-scale characterization of biomaterials using complementary X-ray and electron imaging techniques

contributor:
Grandfield, Kathryn
Materials Science and Engineering

subject:
biomaterials
x-ray
electron
imaging
microscopy
bone
collagen
gold nanoparticles
three dimensional
micro-CT
SEM
TEM
dental implant
scaffold
titanium
osseointegration
porosity

abstract:
Biomaterials may be any class of material that aids in the regeneration, replacement, or augmentation of damaged tissues. The design of biomaterials is becoming increasingly sophisticated as new technologies enable the manufacture and incorporation of smaller components and structural features. Thus, a demand for equally sophisticated tools and methods to study biomaterials are necessary. Two such tools are X-ray micro-computed tomography (micro-CT) and electron microscopy. Micro-CT has the advantage of imaging materials in 3D and non-destructively, but cannot reach the same resolving power as electron microscopy. However, electron microscopy has limited application with biomaterials due to destructive sample preparation requirements. The advantages and limitations of each imaging technique presents a complementary relationship between the two. This thesis aims to develop and apply a complementary workflow using X-ray and electron microscopy to investigate two diverse biomaterials: a titanium dental implant, and collagen tissue scaffold.
In a pilot study, a 3D printed titanium dental implant with a novel dual-stemmed design was investigated for its biocompatibility in vivo. Dual-stemmed and conventional conical implants were inserted into the tibia of New Zealand White rabbits for 3 and 12 weeks, then retrieved with surrounding bone. The implants were analyzed using micro-CT, electron microscopy, and histology. Active bone growth and remodelling around the dual-stemmed implant at both time points was observed. Comparative bone-implant contact indicated the dual-stemmed implants supported bone-implant integration, and demonstrates the comparable biocompatibility of these 3D printed stemmed implants in rabbits up to 12 weeks.
In a separate study, a gold functionalized collagen scaffold for tissue engineering applications has been developed. This scaffold design is intended for improved detection of scaffold degradation behaviour in vivo using X-ray CT. In this thesis, micro-CT and electron microscopy were used to analyze the resultant scaffold structure after fabrication, as it is important for understanding the outcomes of in vivo experiments. Imaging revealed a highly heterogeneous structure at both the micron and nanometer length scales. Interconnected pores from 50 – 400 μm made up 80% of the scaffold volume, while gold nanoparticles and agglomerates ranging from 16 – 1000 nm were non-uniformly dispersed at the nanoscale throughout the collagen matrix.
This work highlights how complementary X-ray and electron microscopy can be applied to characterize diverse biomaterials during developmental and pre-clinical phases.

abstract: Thesis

abstract: Master of Applied Science (MASc)

abstract: The continued development of next generation biomedical materials, otherwise known as biomaterials, is in part dependant on the resources and technology that exist to drive manufacturing, characterization, and testing. Biomaterials are being designed and controlled at length scales smaller than the diameter of a single hair, and therefore specialized tools are required to accurately investigate and characterize these new designs. Two such tools are X-ray and electron microscopy, which can be used to image and understand three-dimensional biomaterials non-destructively, and with high resolution, respectively. However, both imaging techniques struggle to provide both. This thesis aims to develop and apply a complementary workflow using X-ray and electron microscopy to investigate two diverse biomaterials: a titanium dental implant, and collagen tissue scaffold, with high resolution, and in three dimensions.


title: Physical Activity and Multiple Sclerosis

title: The Effect of Physical Activity Participation on Overall Health in Adults with Multiple Sclerosis

contributor:
Hicks, Audrey L.
Kinesiology

subject:
Multiple Sclerosis
Exercise

abstract:
Multiple Sclerosis (MS) is an autoimmune disease characterized by demyelination and axon degeneration of the central nervous system that is accompanied by a wide range of symptoms. It is well established that physical activity is associated with a wide variety of health benefits, including improving fitness, MS-related symptoms and function in the MS population. However, despite the potential benefits associated with physical activity participation, most people living with MS remain physically inactive. In 2012, new evidence-based physical activity guidelines (PAGs) for adults with MS were released. The PAGs suggest that for health benefits, adults aged 18-64 years with mild to moderate disability need at least 30 minutes of moderate intensity aerobic physical activity two days per week and strength training for major muscle groups two times per week. The purpose of this dissertation was to determine the association between physical activity and health and to explore physical activity as a potential disease-modifying therapy in the MS population. This was completed through a series of three projects focusing on the PAGs for adults with MS.
The focus of the first study of this dissertation was on the implementation of the PAGs. The results from this study revealed that direct referral to physical activity from a physician is twice as effective as simply providing information about physical activity with respect to adhering to the PAG recommendations in people with MS (65.2 % vs. 32.8 % for direct referral and control groups, respectively). Further, the results revealed that a high self-efficacy for exercise at baseline may be an additional predictor to PAG adherence.
The purpose of the second study of this dissertation was to validate the PAGs for people with MS within a community-based intervention, and to affirm that following the PAGs for 16 weeks would result in improvements in fitness, mobility, fatigue symptoms and quality of life.
The results from the second study confirm the effectiveness of the PAGs for people with MS for improving health, as significant improvements were observed in VO2 peak (+32 %), strength (+8-20 %), mobility (+14 %), fatigue symptoms (-40 %) and quality of life (+10-24 %).
The purpose of the third and final study was to determine the effect of exercise on brain function and cognition in a sample of adults living with MS. Following the PAGs for 16 weeks led to significant improvements in processing speed and memory in adults living with MS.
	Overall, the results from this dissertation are extremely promising and highlight the importance of physical activity with respect to improving aspects of health and the effect it can have on MS-related symptoms and cognition in the MS population. Novel findings in this dissertation present convincing evidence that physicians should refer patients with MS to participate in exercise to improve MS-related symptoms and overall well-being.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Genotypic and phenotypic analyses of two model strains of Cryptococcus neoformans

contributor:
Xu, Jianping
Biology

subject:
Cryptococcus neoformans
phenotype
Single nucleotide polymorphism

abstract: The human pathogenic Cryptococcus neoformans species complex are agents of a common AIDS-defining disease, which causes about 181,000 deaths each year. There are several specific features distinguishing this species from other fungi, including the presence of a polysaccharide capsule and melanin pigment production, both of which contribute to its virulence. A large number of studies about this pathogen used two model strains JEC20 and JEC21. In these studies, these two strains are assumed to be “isogenic”, differ only at the mating type region. Consequently, their phenotypic differences, including virulence, have been attributed to this region. Here, we applied second-generation sequencing and bioinformatics tools to identify sequence polymorphisms between the two genomes.  Beside the Mating Type locus, two other regions were found to contain high frequencies of SNPs. To further understand the effects of these loci on the phenotypic differences, four phenotyping assays (mating ability, melanin pigment production, capsule formation, and high temperature growth ability) were conducted on the recombinant progeny obtained from the cross between JEC20 and JEC21. In addition, genomic sequences of these progeny were obtained to identify the complete distributions of other SNPs among the strains. Finally, we identified several novel SNPs contributing to virulence-related traits in this species, which suggest that caution should be placed in attributing phenotypic differences to specific genomic regions in “isogenic” strains derived from classical breeding experiments.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Cryptococcosis is a globally distributed infection that is prevalent among immune-compromised individuals, such as HIV/AIDS patients. This disease can be attributed to a group of opportunistic fungal pathogens – Cryptococcus neoformans species complex. During the past century, significant resources have been put in an effort to understand its ecology, evolution, life cycle, pathogenesis and virulence factors, and molecular and cellular processes. Most of the laboratory-based studies have relied on two model strains assumed to differ only at the mating type locus. My thesis investigated this assumption and found there are several additional significant genetic differences between these two strains and that such differences contribute to the observed phenotypic differences between them. My results highlight the complexity of genotype-phenotype relationships and the continued evolution of strains even in lab environments in C. neoformans.


title: Maternal characteristics associated with cardiometabolic status in early pregnancy

contributor:
Atkinson, Stephanie
Medical Sciences

subject:
pregnancy
cardiometabolic markers
adiposity

abstract:
Rationale & Background: During pregnancy, cardiometabolic adaptations occur to
sustain fetal growth. Disruptions in maternal cardiometabolic status may arise related to maternal adiposity, dietary deficiencies or excesses, or sedentary behaviours in pregnancy. Clinically, maternal cardiometabolic dysfunction is associated with adverse health outcomes in both mothers and their offspring. We aimed to determine: 1) the contribution of maternal adiposity, diet and physical activity to maternal cardiometabolic status in early pregnancy using biomarkers of lipid and glucose profiles; 2) whether maternal adiposity measured by 4-site sum of skinfold thickness (SFT) or bioelectrical impedance analysis (BIA) yielded similar strength of association with cardiometabolic status.
Study Design: Maternal blood samples, anthropometric and body adiposity, dietary and physical activity measures were collected from a subset of pregnant women in early pregnancy (12-17 wk gestation) prior to randomization to the Be Healthy in Pregnancy RCT. Blood samples were analyzed for fasting glucose, insulin, triglycerides, leptin, adiponectin, and C-reactive protein (CRP). Maternal adiposity was assessed by pre- pregnancy body mass index (pBMI) and two indirect quantitative measures of % body fat (BIA and 4-site SFT).
Results: Of the 91 subjects (mean age= 31 ± 4 y), 46.2% were overweight/obese by pBMI. For both SFT and BIA, % body fat was positively associated with fasting glucose, insulin, triglyceride, leptin, and CRP concentrations, and negatively associated with adiponectin concentration, although the strength of the associations was greater for SFT than BIA. After adjustment for confounders, maternal adiposity remained significantly associated with all cardiometabolic biomarkers, except for adiponectin and CRP. Dietary polyunsaturated: saturated fat ratio, energy expenditure, high activity level, age, ethnicity and parity were significantly associated with some of the biomarkers.
Conclusion: Maternal adiposity was predominantly associated with leptin, insulin, and glucose status in early pregnancy although dietary fat, energy, activity level, age, ethnicity and parity were also significantly associated with some biomarkers. Body fat estimated by SFT or BIA are generally comparable for use as a screening tool for cardiometabolic dysfunction in early pregnancy. In the clinical setting, BIA may be more easily adopted as it is faster and requires fewer technical skills by the operator than SFT measures.

abstract: Thesis

abstract: Master of Science (MSc)


title: Cellulose Nanocrystal Aerogels: Processing Techniques and Bone Scaffolding Applications

contributor:
Grandfield, Kathryn
Cranston, Emily
Materials Science and Engineering

subject: Cellulose Nanocrystals, Aerogel, Bone Tissue Scaffold, Tissue Engineering

abstract:
This thesis investigates new processing methods and bone tissue engineering applications of cross-linked cellulose nanocrystal (CNC) aerogels. Aerogels are highly porous, low-density materials that have been praised for their high surface area and interconnected pores, but criticized for their brittleness. This prompted a search for new aerogel “building blocks” to produce more flexible materials; CNCs meet this need and chemically cross-linked CNC aerogels have good compressive strength and shape recovery properties in air and liquid environments.
CNCs are high aspect ratio, non-toxic and renewably-sourced nanoparticles. Literature has demonstrated CNC aerogel production using cryo-templating with controlled drying. In this work, we produce aerogels using a new scalable process called pressurized gas expansion (PGX) and compare them to conventional cryo-templated aerogels. PGX aerogels were found to have more expanded fibrillar morphology, a range of mesopore sizes and smaller macropores, in contrast to cryo-templated aerogels that had a sheet-like morphology surrounding larger macropores. Additionally, PGX aerogels had higher specific surface area and porosity, but lower compressive strength due to a lower cross-link density. While neither CNC aerogel type dispersed in water, PGX aerogels partially shrank whereas cryo-templated aerogels did not; this is attributed to their morphological differences. This work shows that new aerogel processing methods can introduce new properties and thus broaden the potential applications of CNC aerogels.
One specific biomedical application was evaluated for CNC aerogels – their use as bone tissue scaffolds. Cryo-templated aerogels comprised of CNCs with different surface chemistries, either sulfate or phosphate groups, were found to have attractive chemical, physical and mechanical properties for bone tissue engineering. This work shows that both types of CNC aerogels can facilitate cell proliferation, favorable differentiation, and can nucleate uniform hydroxyapatite growth. These positive in vitro results and the bimodal pore morphology of CNC aerogels make them promising bone scaffolds for in vivo studies.

abstract: Thesis

abstract: Master of Applied Science (MASc)

abstract: Aerogels are light, porous, sponge-like materials that are essentially 99% air by volume. In this work, the aerogels are made from non-toxic plant-based nanoparticles called cellulose nanocrystals (CNCs). This thesis investigates: 1) new ways to control CNC aerogel properties and pore size through different processing methods and 2) the use of CNC aerogels to aid in the repair of damaged bones. High-resolution microscopy and nano-characterization tools show that CNC aerogels have tunable properties, which may extend their possible applications. The internal structure, sponge-like mechanical properties and biocompatibility of CNC aerogels allowed them to be successfully utilized to support bone cells and grow bone-like mineral.


title: Impacts of Ionizing Radiation on Life History and Immunity in the Cricket, Acheta domesticus L.

contributor:
Rollo, C. David
Biology

subject:
Radiation
Immunity
Life History
Insect
Hormesis
LNT
Dose-Response

abstract: Oxidative stress from high-dose ionizing radiation can contribute to accumulating cellular damage, affecting various fitness related traits. However, studies on low-dose ionizing radiation (LDIR) have shown hormetic effects on growth, longevity, and immunity. Comprehensive lifetime studies assessing LDIR effects and studies investigating LDIR immune stimulation in insects are limited. We utilized 137Cs gamma radiation with a dose rate of 0.25 Gy/min. We examined the impacts of early-life exposure (doses: 0, 0.2, 0.5, 1, 2, 4, 7, and 10 Gy) on life history and immunity in Acheta domesticus. Moderate doses (above 4 Gy) increased mean longevity but decreased growth rate, adult body mass and innate immunity. We also performed a time course study in male A. domesticus to assess the acute effects of radiation (doses: 0, 0.2, 0.5, 0.75, 1, 5, and 15 Gy) on innate immunity and redox status. LDIR (below 1 Gy) generally achieved immune stimulation and improved the encapsulation response but effects were time dependent. Benefits could extend to improved immune responses and protection against infection. Our results provide evidence of immune stimulation with LDIR in insects but with potential trade- offs with life history traits when assessing early-life exposure. With increasing concern of radiation exposure in the environment, more comprehensive studies utilizing a multi- discipline approach will help to elucidate the full mechanism of hormesis.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: High-dose ionizing radiation can have inhibitory effects on cellular systems while low doses can have lasting stimulatory effects. The latter phenomenon, known as hormesis, can act on growth, longevity, and immunity. We investigated the effects of early life gamma radiation exposure on life history traits and measures of innate immunity in the cricket (Acheta domesticus). We observed trade-offs between survival, growth, and immunity. We also tested late life radiation exposure to assess potential hormetic effects on innate immunity and redox status. Our results show immune stimulation with low doses but effects are complex and dependent on dose, type of immunity measured, and time of assessment.


title: Understanding the response of the shoulder complex to the demands of repetitive work

contributor:
Keir, Peter
Kinesiology

subject: Shoulder, Fatigue, Electromyography, Repetitive Work

abstract: Repetitive work is common in the workplace and can lead to the development of muscle fatigue.  The purpose of this thesis was to improve our understanding of muscular and kinematic adaptation strategies of the shoulder complex throughout the process of fatigue and recovery.  To achieve this I completed 6 studies, three studies investigating various aspects of repetitive work and fatigue and three methodological studies that were needed to interpret results.  The muscular and kinematic effects of repetitive work were first investigated by incorporating a fatigue protocol between pre- and post-fatigue, simulated, repetitive work (Chapter 2).  Fatigue is a complex process and how fatigue develops has been shown to influence its effects.  To address this, Chapter 6 and 7 respectively, investigated the response to dynamic and static, fatiguing, repetitive work performed until participants reached termination criteria. Electromyography (EMG) was used throughout this thesis to assess muscle activity, which presented challenges because of its time consuming MVE protocols, the effects of myoelectric fatigue on its interpretation and between participants, fatigue developed in different muscles and at different rates, making comparisons between individuals challenging.  For more efficient data collection, a method was developed  to reduce the number of maximum voluntary exertions (MVE) required to elicit repeatable, maximum shoulder muscle activity, without eliciting muscle fatigue (Chapter 3).  Methods were developed (Chapters 4 and 5) to mitigate the effects of myoelectric fatigue on EMG data and to calculate a multi-muscle fatigue score.  This improved interpretation of how prolonged repetitive work impacted load sharing in the shoulder muscles and allowed the calculation of a multi-muscle fatigue score.  Overall, this thesis found that the response to repetitive work is complex, multi-faceted and varies between individuals.  Repetitive work impacts kinematics, muscle activity, muscle fatigue, strength, affective valence and perceived mental and physical fatigue in both static and dynamic work tasks (Chapters 2, 6, 7).  Participants utilized the degrees of freedom in the shoulder complex and use coordinated compensation strategies to maintain their task performance, both following muscle fatigue (Chapter 2) and while developing muscle fatigue (Chapter 6, 7).  These responses changed over time, as different muscles fatigued and recovered and were variable between individuals (Chapters 2, 6, 7).  Removing fatigue artifacts from the EMG showed that muscle activity changes observed are due to load sharing between the musculature of the shoulder complex (Chapter 6, 7).  Participants can adapt to the challenge of fatiguing, repetitive work and individuals will use different, coordinated strategies to maintain task performance.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: "Ethics is part of that as well": Navigating the landscape of humanitarian healthcare policy

contributor:
Schwartz, Lisa
Health Policy

abstract: In the past decade, there has been a rise in the need for global humanitarian assistance with natural disasters and complex emergencies increasing in severity. Ethical tensions are extensive in humanitarian situations, as aid workers find themselves in unfamiliar and unstable contexts making difficult decisions about right and wrong courses of action. These ethical tensions have repercussions for the people targeted for care and result in moral distress of aid workers. In this dissertation, I seek to highlight new ways of understanding how aid agency policies and agendas contribute to these ethical tensions and clarify their development, implementation, and evaluation in humanitarian settings. In order to understand the policy landscape and provide greater conceptual clarity, the first study in this dissertation identifies and explores the characteristics of policy. The analysis uncovers multiple interpretations of policy and related concepts such as code, guideline, and strategy. In the second study, through a series of semi-structured interviews with individuals working within international humanitarian healthcare organizations (organizational members), a qualitative descriptive analysis reveals how policy is developed, implemented, and evaluated. Findings demonstrate that the realities of humanitarian aid work can differ from the expectations that inform policy, with various social and political factors affecting the policy process. The third study unpacks the ethical tensions arising from policies through an interpretive descriptive approach, with three main themes identified: tensions related to institutional memory loss; clashing departmental priorities; and, social norms and expectations. Results from all three studies help establish a common policy language; identify influences shaping policy development, implementation, and evaluation; and, shed light on the ethical tensions shaped by policy. Together, these findings may be used to help identify new ways to improve policy processes and resolve or better anticipate some of the ethical tensions aid workers may encounter in the course of their work, thereby diminishing moral distress and ultimately benefiting communities that are targeted for care.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Poly(ethylene glycol) Hydrogels Crosslinked via the Strain-Promoted Alkyne-Azide Cycloaddition

contributor:
Adronov, Alex
Chemistry

subject: Hydrogel PEG SPAAC

abstract:
Hydrogels are promising materials for a number of biomedical applications, including tissue engineering, controlled drug delivery, and wound healing. Due to the semi-permeable nature of the water-swollen crosslinked polymer network, hydrogels have the unique ability to encapsulate materials, while allowing passage of any necessary resources, such as the import of oxygen or nutrients and the export of waste or therapeutic agents. Hydrogel properties vary greatly depending on the polymer material and crosslinking chemistry chosen, all of which can be tuned for a particular application. Current hydrogel systems typically involve either natural or synthetic polymers. Synthetic polymers afford more structural control to the resulting hydrogel, however the employed crosslinking chemistry is often non-ideal, due to the high temperatures required or the presence of cytotoxic catalysts. Click chemistry, particularly the strain-promoted alkyne-azide cycloaddition (SPAAC), is ideal for hydrogel crosslinking as it is fast at physiological temperatures, bio-orthogonal, doesn’t produce any byproducts, and doesn’t require a catalyst or external stimuli. For the hydrogel material, synthetic poly(ethylene glycol) (PEG) is most appealing since it is non-toxic, easy to functionalize, and physiologically stable. At the time of this thesis, there were few examples of PEG hydrogels prepared via SPAAC, with limited characterization of the physical properties of these gels and the parameters that dictate their gelation behavior.
The work presented in this thesis involved the optimized synthesis of a cyclooctyne derivative, aza-dibenzocyclooctyne (DIBAC), which was subsequently used for the preparation and characterization of a series of PEG hydrogels crosslinked via SPAAC. We showed that the PEG chain length and number of crosslinking groups had a significant effect on the swelling, degradation time and stiffness of the resulting hydrogels. Additionally, there was very little protein adsorption on the surface of the hydrogels, and the polymer components proved non-cytotoxic.
A second objective of this work was to investigate reproducible hydrogels. We created novel, SPAAC crosslinked PEG hydrogels that contained well-defined dendritic crosslinking groups, making them more reproducible than the previous linear analogs. These hydrogels have short gelation times at low polymer concentration, minimal swelling at physiological temperatures, and kept human mesenchymal stem cells (hMSCs) viable for over 15 days.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Topics in Copular Clauses

contributor:
Kučerová, Ivona
Cognitive Science of Language

subject:
copular clauses
agreement
inversion
scrambling

abstract:
This dissertation investigates syntax and semantics of copular clauses containing two NPs.
Since Higgins (1973) four semantically distinct types of copular clauses have been recognized
in the literature, i.e. predicational, equative, specificational, and identificational
clauses. There are many proposals aiming to reduce the number of copular clause types via
collapsing certain types into others. This dissertation contributes to the debate by providing
novel evidence from Czech that identificational clauses are predicational and specificational
clauses are inverted predicational or equative clauses. Czech provides an excellent
tool to investigate copular clauses for three reasons: (i) rich phi-feature agreement, (ii) case
alternation, (iii) analytical verbal morphology. Using the three properties Czech offers, I
argue that specificational clauses are derived via scrambling of a structurally lower NP over
a structurally higher NP. Consequently, I support the inversion analysis of specificational
clauses (Moro, 1997; Den Dikken, 2006; Mikkelsen, 2006; Heycock, 2012, a.o.). I also
argue that specificational clauses may be derived from both, predicational and equative
clauses. In contrast, identificational clauses, despite their initial resemblance to specificational
clauses, are argued not to involve inversion, therefore providing empirical support
for Heller and Wolter (2008). I also present novel empirical data from Czech that show
that the interpretation of the pronoun in identificational clauses is restricted by the copular
agreement. In order to account for the restriction, I argue that both NPs in identificational clauses Agree with the copula via a Multiple-Agree chain (see Hiraiwa (2005)).

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The Investigation and Development of Novel Molecules, Models and Tools for the Treatment and Study of Schizophrenia

contributor:
Mishra, Ram K.
Neuroscience

subject:
neuroscience
schizophrenia
drug development
animal model
brain imaging
allosteric
rat
cellular
neuropharmacology
antipsychotic
PAOPA
translational

abstract: Schizophrenia is a severe mental disorder that can manifest in various ways and is often characterized by the appearance of positive symptoms (hallucinations, delusions), negative symptoms (social and attention impairment) and cognitive dysfunction (thought disorders, memory and executive function impairments). Traditional treatment methodologies involve blocking the dopamine receptor by binding to the same site as dopamine. These treatments are largely inadequate and lead to an array of adverse side effects. Side effects include weight gain, diabetes, and movement disorders; which critically limit the therapeutic value of antipsychotic drug treatment. Limited symptom control and severe adverse effects have led to poor drug adherence and a deprived quality of life for patients suffering from schizophrenia. The complex etiology of schizophrenia combined with a lack of effective translational models and tests to represent and assess the illness have hindered drug development. Evidently, there is a strong demand for a new generation of pharmaceuticals and an improved translational pipeline for the treatment of schizophrenia. The collection of studies presented here contribute to the advancement of translational tools for drug discovery, the establishment of pre-clinical models to embody the various symptoms, and the development of a novel drug candidate for schizophrenia. Allosteric modulation of G-protein coupled receptors is evolving as a new wave of therapy with promising implications for various CNS disorders. Allosteric compounds regulate binding without blocking the receptor. PAOPA, a dopamine D2 receptor allosteric modulator, prevents and treats schizophrenia-like symptoms in pre-clinical animal models of schizophrenia with no apparent adverse effects. The studies outlined in this thesis further categorize PAOPA as a novel therapeutic candidate for schizophrenia. Moreover, the findings presented here provide further insight into the potential therapeutic mechanism of action of PAOPA and set the foundation for the development of a new generation of antipsychotic drugs. These studies constitute an innovative approach to expanding research in the field of drug development for schizophrenia.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: OKWIRE’SHON:’A, THE FIRST STORYTELLERS: RECOVERING LANDED CONSCIOUSNESS IN READINGS OF TREES & TEXTS

contributor:
Monture, Richard
English

subject: Indigenous Studies, Indigenous Literature, Ecocriticism, Landed Pedagogy, Indigenous Methodologies, Rotinonhsonni, Haudenosaunee, Trees

abstract: Okwire’shon:’a, or trees of the forest, guide the methodology and epistemology of my doctoral research. The Rotinonhsonni creation history tells us that all life is made from the clay of the earth (Mother Earth or First Woman), and therefore everything in Creation shares an origin in and a connection to the earth. Thus, Rotinonhsonni thoughtways understand trees to be part of an interconnected network of land-based knowledge that spans from time immemorial to the present. As extensions of First Woman, trees are literally my relations, my ancestors. While onkwehonwe (original peoples) have long been able to tap into the knowledge of the land (and many still do), colonialism has significantly disrupted our landed and place-based relationships and consequently our ability to read the land. This, in turn, disrupts the ability of onkwehonwe to live within the principles of Kayanerekowa. My dissertation explores, through juxtapositions of Rotinonhsonni oral histories, contemporary Indigenous literature, and a series of trees, the possibility of (re)learning to read and communicate with the land. Using a trans-Indigenous methodology, my project examines three branches of land-centered philosophy within Indigenous literature: enacting creation stories; spirit agency; and internalized ecological holism. By reading different Indigenous texts across from Rotinonhsonni epic teachings, my trans-Indigenous methodology affirms Indigenous alliances with the environment and with each other, their long-standing presence on and stewardship of the land, and the value and validity of knowledge that is ancestral, adaptive, and alive. I argue that by carrying forward land-centered knowledge contemporary Indigenous literature stimulates an awareness of the land and nonhuman societies as cognizant and in communication with us. Renewing relations and modes of relationality to the land in this way re-energizes Kayanerekowa, and has the potential to strengthen Indigenous efforts for self-determination, knowledge resurgence, land reclamation, and nation-to-nation alliances.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: This project demonstrates a cyclical process of reading between a small selection of contemporary Indigenous literatures, Indigenous oral histories and cosmologies, and a series of trees indigenous to Turtle Island. Tree-readings are attempted through three methods: aesthetic (metaphoric) interpretation; analysis through Indigenous oral histories; and, listening to the thoughts of the trees themselves. Each tree’s teachings are then bundled together as a framework for reading a work of Indigenous narrative art that demonstrates similar principles and emphases. The overall aim of this work is to model how landed processes of coming to know develop an awareness of the land and all nonhuman societies as alive, thinking, and possessing agency. In a Rotinonhsonni (Six Nations) context, this renewal of landed consciousness strengthens the principles of righteousness, reason, and power, which sustain the Kayanerekowa (Great Law of Peace).


title: Landlords in the Private Rental Market in Hamilton, Ontario

contributor:
Harris, Richard
Geography

subject:
landlords
rental market
Hamilton

abstract: While several researchers have explored the private rental sector from the tenants’ perspective very little is known about landlords and their experiences. The purpose of this study was to understand more in-depth the nature, motives, and challenges of landlords. A case study of landlords in Hamilton, Ontario, is based on survey research, involving the administration of an online questionnaire and then follow-up face-to-face interviews. A local association of landlords, Hamilton and District Apartment Association, assisted in advertising and promoting this research through their registered email list and on their website. The results of the study show that Hamilton’s landlords are a diverse group with mixed motives. They find many aspects of the job rewarding, including good landlord-tenant relations, opportunities for profit/investment, and the flexibility of the work involved, among other things. In contrast, they reported many concerns regarding responsibilities, tenants, the government, and the negative perceptions of them that are held by tenants, councillors and the general public.

abstract: Thesis

abstract: Master of Arts (MA)


title: NOVEL STOCHASTIC PROGRAMMING FORMULATIONS FOR ASSEMBLE-TO-ORDER SYSTEMS

contributor:
DEZA, ANTOINE
Computing and Software

subject:
Assemble-To-Order
component commonality
stochastic programming
inventory  replenishment
component allocation

abstract:
We study a periodic review assemble-to-order (ATO) system introduced by Akcay
and Xu (2004) which jointly optimizes the base stock levels and the component allocation
with an independent base stock policy and a  first-come- first-served allocation
rule. The formulation is a non-smooth and thus theoretically and computationally
challenging. In their computational experiments, Akcay and Xu (2004) modified the
right hand side of the inventory availability constraints by substituting linear functions
for piece-wise linear ones. This modification may have a significant impact on
low budget levels. The optimal solutions obtained via the original formulation, i.e.,
the formulation without modification, include zero base stock levels for some components
and thus indicate a bias against component commonality. We study the impact
of component commonality on periodic review ATO systems. We show that lowering
component commonality may yield a higher type-II service level. The lower degree of
component commonality is achieved via separating inventories of the same component
for different products. We substantiate this property via computational and theoretical
approaches. We show that for low budget levels the use of separate inventories
of the same component for different products can achieve a higher reward than with
shared inventories. Finally, considering a simple ATO system with one component
shared by two products, we characterize the budget ranges such that either separate
or shared inventory component (i.e., component commonality) is beneficial.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: The combined effects of thermal and radiological stress on the embryonic development of lake whitefish (Coregonus clupeaformis)

contributor:
Wilson, Joanna
Biology

subject:
Embryonic development
Lake whitefish
Ionizing radiation
Adaptive response
Heat shock response

abstract: Lake whitefish (Coregonus clupeaformis; LWF) are a cold-adapted freshwater species that are of both economic and cultural value. These fish spawn in lake areas where their embryos are exposed to thermal power plant effluents that may contain low levels of thermal, radiological and chemical stressors. Many studies on LWF embryonic development have looked at the individual effects of these stressors, but few have looked at the potential for combined effects. The combined effects of thermal and radiological stress were of interest due to growing evidence that mild thermal stress can produce an adaptive response, through the induction of the heat shock response (HSR), when followed with subsequent ionizing radiation stress. This thesis examined the combined impacts of thermal and radiological stress during LWF embryogenesis. LWF embryos were exposed to mild heat shocks (HS; Δ3 or 9°C) prior to a high dose of acute 137Cs gamma rays at 2, 6 and 24 hours post heat shock during the gastrulation or eyed stage. Heat shocked embryos were collected at each developmental stage and assessed for induction of heat shock protein (Hsp) genes. Following exposure, embryos were raised until hatch where mortality, morphometry, and embryo weight were measured.  Mild HS induced Hsp70 mRNA expression at gastrulation, but not at the eyed stage. Embryos at hatch were not impacted by thermal or radiological exposure at the gastrulation stage. During the eyed stage, acute radiation treatment increased mortality and decreased body size at hatch. Mild HS prior to radiation did not provide protective effects and no adaptive response was observed. This thesis better defines the combined effects of thermal and radiological stress on the embryonic development of LWF. It also suggests that the ontogeny aspects of heat shock responses and radiosensitivity are important to consider for future adaptive response studies.

abstract: Thesis

abstract: Master of Science (MSc)


title: ELUCIDATING THE PATHOPHYSIOLOGY OF BIPOLAR DISORDER

title: BLOOD BRAIN BARRIER DISRUPTION AND MYC-ASSOCIATED FACTOR X (Max) GENE EXPRESSION IN THE PATHOPHYSIOLOGY OF BIPOLAR DISORDER

contributor:
Mishra, Ram
Neuroscience

subject:
Neuroscience
Bipolar disorder

abstract:
Bipolar Disorder (BD) is a debilitating mental illness that presents as mood alterations between manic and depressive states. There remain large gaps in the knowledge surrounding the disease, due to three main issues in understanding the illness. First is a lack of an appropriate animal model that mimics both manic and depressive symptoms. Second is a lack of knowledge on the biological cause of the disease. Finally, a lack of knowledge on the precise mechanism of action of lithium (Li), the main treatment for BD prevents more progressive research into the disease.
	Inflammation and a subsequent disruption of the blood-brain barrier (BBB) have recently been demonstrated in other psychiatric conditions, such as Alzheimer’s Disease (AD) and Schizophrenia (SZ). This mechanism remains to be fully investigated in BD. This thesis presents an inflammatory model of BBB disruption in rodents.
	A study examining gene expression in discordant sibling pairs with SZ or BD discovered that the Max gene was elevated two-fold in bipolar patients as compared to their non-BD siblings. We aim to elucidate on these findings and examine the effect of common BD treatments on Max gene expression.
	The first study utilized lipopolysaccharides (LPS) to induce an inflammatory response in the BBB, and sodium fluoroscein (NaF) to measure the levels of resulting disruption. It was shown that Li is unable to attenuate disruption of the BBB, and an LPS administration with Li pretreatment causes higher disruption than either substance alone in several brain regions.
	The second study examined Max gene expression levels in naïve rats as a result of Li or valproate (VPA) treatment. VPA was shown to significantly downregulate the expression of Max in a rodent model.
	These studies may provide insight into understanding the pathophysiology of BD, leading to better, more accurate animal models and more targeted therapies for the disorder.

abstract: Thesis

abstract: Master of Science (MSc)


title: Love’s Weakness: Simone Weil and the Truthful Encountering of Others

contributor:
Kroeker, P. Travis
Religious Studies

subject: Simone Weil, Jean Vanier, Christian theology, theology of weakness, love, others and otherness, truthfulness, ethics, epistemology, vulnerability, embodiment, neighbour love, friendship, compassion

abstract: This thesis provides a presentation and analysis of Simone Weil’s articulation of the weakness of love vis-à-vis our encounters with others. It does so both as a way to better examine Christian theological claims about the importance of weakness and as a way of accessing the tensional depths of Simone Weil’s work from an often neglected angle. To achieve this engagement, I read Weil alongside Jean Vanier, whose life and work share with Weil a profound emphasis on the centrality of weakness for meeting others truthfully and lovingly. In Chapter One I draw on both Weil and Vanier to present their shared critique of relationships that are reduced to a pursuit of power and influence over others. I call such relationships “territorial” because they posit human beings as competitors for two-dimensional territory and therefore envision human relationships in essentially competitive terms. Chapter Two is a detailed presentation of Weil’s constructive work on the weakness of love that emphasizes her account of the impersonal, non-egoistic, and unattached relationships we ought to pursue with others. Weil claims that we experience the fullness of reality through an uncompromising embrace of all things, which we can only accomplish through the removal of ourselves in the face of others. We get concrete development of these themes in Weil’s presentation of neighbour love and friendship, which she understands as a total openness to another’s position, circumstance, and being. In the third chapter, I use the theme of communion in Vanier’s work to call into question the way Weil demands our total surrender to the other. I suggest that an absent self cannot be truly weak and vulnerable before others. The central problem, I suggest, is a conception in which any sort of positive presence is necessarily an obstacle and any imposition of oneself necessarily competitive.

abstract: Thesis

abstract: Master of Arts (MA)

abstract: In this thesis, I present and examine Simone Weil’s understanding of how we might avoid doing violence to other people and instead treat other people with love and compassion. The first chapter reads Weil together with Jean Vanier to examine the various ways that power and the attempt to dominate others dictates our relationships with others. In the second chapter I systematically present Weil’s understanding of how we might, through a certain kind of personal death, transport ourselves wholly into the perspectives of other people and thereby practice true compassion towards them. In the third  and concluding chapter I use Vanier’s compelling presentation of human flourishing as consisting of heart-to-heart interdependent relationships to critique the refusal of being dependent on others that is both implicit and explicit in Weil’s account of compassion.


title: Prenatal Ionizing Radiation Exposure Effects on Cardiovascular Health and Disease in C57Bl Mice

subject:
Ionizing radiation
Mouse
Blood pressure
Fetal programming
Developmental programming
Cardiovascular
Maternal stress
Transportation stress

abstract: Ionizing radiation exposure during pregnancy raises concerns of potentially harmful effects for both the mother and the unborn child. Fetal programming involves permanent changes in offspring phenotype due to stress experienced in-utero. This phenomenon has been well characterized in cardiometabolic disorders such as hypertension. The effects of prenatal ionizing radiation exposure on offspring cardiovascular endpoints following birth were studied in a mouse model. Pregnant wildtype C57Bl/6J mice were irradiated on day 15 of pregnancy with whole-body 137Cs gamma radiation at nominal doses of 5, 10, 50, 100, 300 or 1000 mGy. Post-natal measurements of offspring weight and blood pressure were completed. In female pups, blood pressure was significantly increased at 300 mGy and heart rate significantly decreased at 1000 mGy. Female pups were growth restricted over the study period at 50, 100 and 1000 mGy. Growth restriction in male pups was only observed at the highest dose of 1000 mGy. Unintended effects on the study measures caused by transportation of pregnant mothers to the irradiation facility were most evident in male offspring with increased blood pressure and heart rate and decreased body size. These unintended effects caused by transportation may have been attenuated with the 10 mGy in-utero exposure. Overall, these results suggest that prenatal radiation effects in mice are both dose- and gender-dependent, with even fairly low doses demonstrating (potentially adaptive) effects. There is a need for further study to better characterize the mechanism of this response.

abstract: Thesis

abstract: Master of Science (MSc)


title: Red Misfits in the Sloan Digital Sky Survey: Properties of Star-Forming Red Galaxies

contributor:
Parker, Laura
Physics and Astronomy

subject:
Astronomy
Galaxies
Galaxy Evolution

abstract: Galaxies in the Universe are primarily blue and star-forming or red and passively evolving. Here we study an outlier population of red, star-forming galaxies in the local Universe which we call Red Misfits. These galaxies are classified based on inclination-corrected optical colours and specific star formation rates derived from the Sloan Digital Sky Survey Data Release 7. We find that $\sim$11 per cent of galaxies at all stellar masses are classified as red in colour yet actively star-forming. Using the wealth of information provided by the SDSS and related products we explore a number of properties of these galaxies and demonstrate that Red Misfits are a distinct population of galaxies in the Universe and not simply blue star-forming galaxies whose colours are reddened by intrinsic dust extinction. Red Misfit galaxies exhibit intermediate, bulge-dominated disk morphologies, intermediate stellar ages, slightly enhanced dust extinction and gas-phase metallicities, and an enhanced likelihood of hosting an active galactic nucleus. The proportion of Red Misfits in galaxy groups remains constant irrespective of group halo mass or projected distance to the group centre. We conclude that Red Misfits are a transition population being gradually quenched on their way to the red sequence and that this quenching is dominated by internal mechanisms rather than environmentally-driven processes.

abstract: Thesis

abstract: Master of Science (MSc)


title: TRANSCRIPTIONAL REGULATION OF PLURIPOTENCY AND CELL FATE

contributor:
Draper, Jonathan
Biochemistry

abstract:
Embryonic stem cells are pluripotent in nature, in that they can self-renew indefinitely, while maintaining the capability to give rise to all adult cell types. This characteristic makes them an attractive avenue for various therapeutic purposes. Therefore, many studies have been devoted to understanding the fundamental nature of these cells and the processes that govern and maintain their pluripotent cell fate. We hypothesized that cell fate is intrinsically regulated by the underlying chromatin and transcriptional machinery of the cells. To test this, we first studied the heterogeneity that exists within pluripotent cell cultures. We showed that pluripotent sub-populations demarcated by expression of REX1, a pluripotency transcription factor, have distinct differentiation propensities. Additionally, we found that chromatin modification via DNA methylation was the underlying cause of this heterogeneity, providing evidence for the major roles that chromatin and transcription play in regulating cell fate.
We next studied a fate maintaining mechanism, mitotic bookmarking, as a method of cell fate preservation. During cell division, chromatin structure undergoes significant remodeling, various proteins uncouple from the DNA, and there is a temporary hiatus in transcription. Despite this restructuring the transcriptional memory of the parent cell is faithfully transmitted to daughter cells. We hypothesized that, in ES cells, several chromatin bound factors would be retained on the mitotic chromatin and would act as bookmarks preserving the underlying pluripotent chromatin structure. Using a global unbiased approach, we found that a large number of chromatin regulators are indeed bound to the mitotic chromatin. Additionally, a chromatin accessibility assay revealed that a large number of accessible promoter sites are preserved during mitosis and into G1 of daughter cells. The mitotic chromatin bound factors likely play a role in the maintenance of these protected DNA sites.  Our data suggest that, preservation of these sites by various chromatin regulators during mitosis underlies the faithful transmission of cell identity from parent to daughter cells, ergo maintaining the cell’s fate.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: DOPAMINE RECEPTOR TARGETING IN HUMAN ACUTE MYELOID LEUKEMIA

contributor:
Bhatia, Mickie
Biochemistry

abstract:
Standard of care chemotherapy for acute myeloid leukemia (AML) has remained unchanged for decades and is associated with therapy failure and unsatisfactory survival rates. While several theories have been put forth to explain the issue of therapy failure in AML, their clinical relevance remains ambiguous and they have yet to advance therapy decisions. To date, the underlying basis of therapy failure remains unresolved, partly due to a lack of reliable surrogate models that authentically reflect the biology of human AML.
To dissect the unique biological basis of therapy failure in a clinically-relevant system, we developed a unique patient-derived xenograft model that simulated chemotherapy regimens in vivo. Using this model, we characterized residual leukemia populations immediately after chemotherapy exposure, and monitored their longitudinal growth kinetics towards relapse. Despite the prevailing hypothesis of therapy resistance that involves leukemia stem cells (LSCs), we found that LSC pools were profoundly depleted shortly after chemotherapy, as determined by a lack of LSC-related functional and transcriptional properties. Instead, the residual leukemia cells displayed a unique transcriptional profile that emerged prior to the unrestrained regeneration phase that led to overt relapse. With the goal of identifying novel therapeutic targets, we searched for druggable gene products within the unique transcriptional signature of these leukemia regenerating cells (LRCs), which revealed a member of the dopamine receptor (DRD) family. Functionally, AML recurrence was prevented in mice treated with DRD antagonist thioridazine (TDZ) in combination with chemotherapy. Mechanistically, DRD modulation by small molecules and immunotargeting resulted in suppression of neoplastic self-renewal towards cellular maturation, exclusively in leukemia progenitor cells with no adverse impact on healthy hematopoietic cell function. These findings provided proof-of-concept for our targeting approach and defined a novel role for the DRD pathway in human AML biology.
These pre-clinical observations motivated a phase I clinical trial to evaluate the safety and efficacy of DRD antagonist TDZ in AML patients. In a cohort of older patients with relapsed/refractory AML, treatment with TDZ resulted in a reduction of leukemic blasts, predominantly in the peripheral blood. The suppressive effect of TDZ was selective to leukemia cells and was associated with patient-specific DRD expression levels. Collectively, the data presented in this thesis offer a novel perspective on human AML biology with a focus on targetable vulnerabilities of leukemia, derived from sophisticated xenograft systems and validated with clinical level data. Our findings describe a novel role for DRDs in regulating leukemic hematopoiesis and propose DRDs as a cancer-selective therapy target for AML.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Multimode Fabry-Perot Laser Diodes: Modeling and Simulation of Mode Partitioning Noise in Fibre-Optic Communication Links

contributor:
Huang, Weiping
Electrical and Computer Engineering

subject: multimode, Fabry-Perot, laser diodes, mode partitioning, noise, fibre-optic communications, simulation

abstract:
The FP multimode semiconductor laser has lightened up a new field of optical communication technology in the past two decades. Numerical modeling of its physical behaviours and transient response has been discussed previously in literature, mostly by constructing the multimode rate equations. Rate equations are very helpful in studying and predicting the average photon and carrier transient response and relaxation oscillation. However, their deficiency in statistical photon fluctuation limits the function of describing stochastic power shifted from main mode to other side modes. Therefore, a noise driven model with conjunction of optical fibre and photodiode is built to form an optical communication system in the simulation scope. The multimode nature of FP lasers causes several problems such as mode partitioning noise (MPN), intersymbol interference (ISI), and frequency chirping, among which mode partitioning noise is the most serious of the concern in this discussion. The stereotype analytical measurement of MPN power penalty is based on several assumptions on the received waveform shape and power distribution spectrum, which limits its fields of application and accuracy. This work develops a numerical
solution to power penalty due to MPN, and it can be employed to any multimode laser diode models regardless of the received signal shape and power distribution spectrum. In conclusion, the MPN power penalty is a significant profile of evaluating system perform in fibre-optic communication links. It highly depends on shape of power distribution spectrum, number of modes, length of fibre, and pattern of signal waveform.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: BMI1 REDUCES ATM AND ATR ACTIVATION DURING DNA DAMAGE RESPONSE THROUGH BINDING TO NBS1 AND TOPBP1

contributor:
TANG, DAMU
Medical Sciences

subject:
BMI1
DNA damage response
ATM and ATR
checkpoint activation
Microvesicles

abstract:
DNA damage response (DDR) maintains genome integrity through checkpoint activation and lesion repair. While ATM and ATR are essential in DDR, mechanisms regulating their activation remain unclear. BMI1 is a component of the polycomb repressive complex 1 (PRC1), and contributes to PRC1’s E3 ubiquitin (E3-Ub) ligase activity though binding the catalytic subunit RING2. BMI1 binds RING2 through its ring finger (RF) domain. The E3-Ub ligase activity contributes to BMI1-deirved facilitation of the homologous recombination-based repair of DNA double-stranded breaks (DSBs).
        My research demonstrates that BMI1 reduces ATM and ATR activation during DDR. DSBs and single-strand DNA (ssDNA) lesions respectively activate ATM and ATR. ATM subsequently phosphorylates CHK2 at threonine 68 (CHK2pT68) and induces G2/M arrest. ATR produces CHK1pS345 and S-phase arrest. Both kinases phosphorylate histone H2AX at serine 139 (γH2AX) to prepare for lesion repair. Hydroxyurea initiates DDR via producing ssDNA lesions, and increases ATR activation (phosphorylation of T1989/ATR pT1989), CHK1pS345, γH2AX, and S-phase arrest. These events were significantly reduced and enhanced following the respective BMI1 overexpression and BMI1 knockdown in MCF7 and DU145 cells. BMI1 also displays similar effects towards ATM during DDR induced by etoposide-caused DSBs.
        Activation of ATM and ATR requires the formation of the ATM-NBS1 and ATR-TOPBP1 complexes. We observed that BMI1 interacted with NBS1 or TOPBP1. Deletion of the RF domain from BMI1 did not affect the associations and also had no effects on BMI1’s activity in reducing ATM activation and ATR-mediated CHK1 pS345. Collectively, our research suggests that BMI1 attenuates ATM and ATR signaling independently of the E3-Ub ligase activity.
        Genotoxic treatments elicit DDR in cells that are directly exposed and also in cells that are not exposed, a phenomenon known as bystander effect (BE). However, it remains unclear what mediates the BE. Microvesicles are small membrane-enclosed sacks that are shed from donor cells and communicate specific messages to recipient cells. We demonstrated that microvesicles isolated from cells treated with etoposide and ultraviolet induced BE in recipient cells. Neutralization of microvesicles through annexin V reduced the microvesicles-associated BE.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Grind Hardening of AISI 1045 and AISI 52100 Steels

contributor:
Koshy, Philip
Hamed, Mohamed
Mechanical Engineering

subject: grind hardening, steels, AISI 1045, AISI 52100, martensitic phase transformation, alloy, Vickers hardness tester

abstract:
 Case hardening of steels is extensively used throughout general engineering to produce components with a hardened layer whilst retaining a tough core. This is usually accomplished using different sources of energy, e.g. flame and induction being the most common. In recent years, a new case hardening technology, named 'Grind-Hardening' has surfaced. In this method, the heat dissipated during grinding is utilized to induce martensitic phase transformation in the surface layer of a component. Therefore it is possible to incorporate grinding and surface hardening into a single operation to develop a cost-effective production method. The grinding process then becomes an integrated heat treatment process.

 In the present study on 'grind hardening', a numerical thermal model has been developed to compute the temperature distribution beneath the ground surface to predict the extent of surface hardening and the case depth. Grinding experiments were conducted in order to examine the influence of various process variables such as wheel depth of cut, feed speed, and wheel preparation. AISI 52100 and 1045 steels were used in this study to evaluate the behavior of plain and alloy steels during grind hardening. Effective case depth was measured using a Vickers hardness tester and was found to be over 0.5 mm for a target hardness of 513 Hv. Microstructure was analyzed using optical and scanning electron microscopes. The microstructure was observed to have fine martensitic laths which give rise to remarkable high hardness.

abstract: Thesis

abstract: Master of Applied Science (MASc)


title: The effects of exercise on hematopoiesis and the development of the hematopoietic stem cell niche

contributor:
Parise, Gianni
Kinesiology

subject: hematopoiesis exercise bone muscle

abstract: Exercise has been shown to influence nearly every tissue type in the body, including the hematopoietic system. The means by and the extent to which exercise is able to do this is unknown. Here, we investigated the effects of skeletal muscle and exercise on several components of hematopoiesis. Firstly, we investigated exercise induced changes in skeletal muscle endocrine signalling. We demonstrated that exercise increased skeletal muscle hypoxia, leading to HIF1α and HIF2α stability, resulting in increased expression of erythropoietin. As well, myoblasts in culture were shown to express and release erythropoietin in response to hypoxia. Secondly, we measured mobilization of hematopoietic cells during exercise. We demonstrated that exercise greatly increased the number of hematopoietic stem cells in circulation. The quantity of mobilization was dependent on exercise intensity, did not depend on fitness levels, and was at peak immediately post exercise. Thirdly, we measured levels of extramedullary hematopoiesis following exercise. Exercise increased spleen hematopoietic stem cell content. Furthermore, expression of genes associated with hematopoietic homing, adhesion, quiescence, and growth were all increased in the spleen following exercise. Finally, we examined bone marrow in the appendicular and axial skeleton of aged animals. Here, exercise increased bone marrow cellularity and reduced bone marrow adiposity in the appendicular skeleton of aged mice. However, lumbar vertebral marrow cellularity and skeletal muscle expression of hematopoietic cytokines in these mice was unaffected by exercise. Taken together, these results demonstrate that exercise is a potent mediator of hematopoietic homeostasis. Several themes recurrent in these and other studies lead to insight in how exercise is able to exert influence on hematopoiesis, namely: tissue specific changes in hematopoietic growth and homing factor expression, the ability of mechanical forces felt during exercise to alter the bone marrow niche microenvironment, and increased flux of hematopoietic stem cells through their various bodily niches.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Exercise affects many different tissue types throughout the body. The hematopoietic system, through which the body produces blood cells, is no exception. How exercise as a stimulus is able to influence this system is poorly understood. Here, we demonstrate that exercise is able to stimulate skeletal muscle to produce erythropoietin, a potent hematopoietic growth factor. As well, we demonstrate that exercise is capable of mobilizing hematopoietic stem cells from the bone marrow to the blood. We then describe how exercise is able to increase hematopoietic activity outside the bone marrow. Finally, we show that exercise affects marrow in only certain bone marrow cavities. Our findings demonstrate that exercise is able to influence hematopoiesis in a myriad of ways. As well, our findings highlight potential commonalities in the means by which exercise exerts these influences.


title: INFLUENCE OF THE TRANSITION FROM ACUTE TO CHRONIC HYPOXIA ON PYRUVATE DEHYDROGENASE KINASE 1 AND LACTATE ACCUMULATION IN C2C12 CELLS

contributor:
McClelland, Grant
Biology

abstract: For decades researchers have observed a reduction in exercise-induced blood lactate accumulation transitioning from acute to chronic hypoxia (the ‘lactate paradox’). Hypoxia inducible factor (HIF1-α) has been hypothesized to direct these metabolic changes during hypoxia through the induction of pyruvate dehydrogenase kinase 1 (PDK1). Activation of PDK1 inhibits aerobic glucose metabolism through pyruvate dehydrogenase, and promotes lactate production. Previous work in our lab revealed HIF1-α and PDK1 protein expression correlates to changes in lactate production with the transition from acute to chronic hypoxia in CD-1 mice, revealing a putative mechanism explaining the paradoxical reduction in lactate. We exposed differentiated C2C12 cells to 1% O2 for 4h, 24h, 96h and compared them to time-matched controls in 21% O2. In addition, we used 1 mM of the HIF-agonist DMOG at 20.95% O2 and 25 µM of the HIF antagonist PX-478 in 1% O2. We found that C2C12 myotubes decreased the rate of lactate accumulation and release with long-term hypoxia, similar to observations in vivo. This also corresponds to changes in LDH enzyme activity and PDK1 protein expression. However, DMOG-induced PDK1 expression does not match changes in lactate accumulation. Our findings confirm the existence of the lactate paradox at the cellular level and suggest a role for HIF signaling in the decline of lactate with chronic hypoxia.

abstract: Thesis

abstract: Master of Science (MSc)


title: Simulating Self-Assembly of Organic Molecules & Classifying Intermolecular Dispersion

contributor:
Turak, Ayse
Engineering Physics

subject:
Organic Molecules
Simulation
Classify Dispersion
Monte Carlo
2D materials
Morphology
Order Metrics
Particle Shape

abstract:
Mechanisms for charge transport in organic electronics allows them to perform with disordered internal morphology, something which is not possible for traditional crystalline semiconductors.
Improvements to performance can occur when the materials change their relative positions to each other, resulting as a different spatial dispersion with lower electrical loss over the device area.

A numerical method has been developed using interaction models for molecules from colloidal self-assembly.
Colloids are rigid particles with a volume which is embodied by their shape and their collective behaviour depends on its density.
The self-assembly mechanism used is condensation, which increases the density by removing the spaces between molecules while they lose thermal energy due to the increasing steric interactions with neighbours.
The molecular chemical structure determines the spatial probability of electron orbitals that (for a given energy) outlines their geometric shape.
Because these shapes are localized onto the molecule, their intermolecular positions determine how close these orbitals can be to each other which is important for electron charge transport.

During operation, the organic active layer may have thermal energy to cause molecular reorganization before cooling, which increases the probability to find disordered states within the device.
A comprehensive suite of tools has been developed which can classify disorder in the physical characteristics of morphology; such as density, internal spacing, and angular orientation symmetry.
These tools where used to optimize the experimental preparations for depositing nanoparticle dispersions on surfaces within organic electronic devices.
These have also been used to quantify the statistical variations in structure between configurations produced from our Monte Carlo method and a similar molecular dynamics approach.
Simulated self-assembly within highly confined areas showed repeatedly sampled microstates, suggesting that at thermodynamic equilibrium confined particles have quantized density states.
We conclude with morphologies resulting from non-circular shapes and systems of donor-acceptor type molecules.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Design Considerations for High Surface-Speed and High-Load Switched Reluctance Machines

contributor:
Emadi, Ali
Schofield, Nigel
Mechanical Engineering

subject:
design
switched reluctance machine
rotordynamics
electromagnetics
thermodynamics
noise vibration and harshness

abstract:
This thesis investigates and determines the design considerations to be addressed when designing switched reluctance machines (SRMs) operating at high surface-speeds and high-loads.  A new method is introduced to the traditional machine design procedure that captures all of the mechanical, thermal and electro-magnetic considerations for such electric machines.
This method is applicable to any motor design; however, is most suitable for machines with rotors that sustain mechanical stresses near the rotor core material limits.
The method begins by using common application specifications to identify the maximum diameter and length of a rotor through a series of structural analyses.
Maximizing rotor diameter and axial length enables designers to evaluate a machine's theoretical mechanical and electro-magnetic performance limits.
The design method is structured such that the designer must use theoretical limits as a constraint for assessing future design decisions which ultimately influence machine cost and performance.

The proposed design method is applied to a case study example typical of a large electric vehicle traction machine, a 22,000rpm, 150 kW switched reluctance machine, while attempting to adhere with design practices commensurate with automotive mass manufacturing.
To achieve this, a parallel connected 12/8 pole topology was finally developed.
The thesis research suggest that a 440 MPa yield strength, 0.27mm thickness lamination with 30 turn stator coils is sufficient to meet the specification requirements within a prescribed power electronic converter voltage and current constraints, while satisfying material mechanical and thermal considerations.
Detailed analysis of AC effects, performance characteristics, thermodynamics, noise and vibration is presented to simultaneously demonstrate and validate the proposed machine design and design method.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)


title: Characterizing the diversity and complexity of the human gut microbiome through the combination of culture and culture-independent methods

contributor:
Surette, Michael G.
Biochemistry

subject:
gut microbiome
culture

abstract:
The human gut microbiome is the collection of all organisms and their genetic content
that inhabit the gastrointestinal tract. An overwhelming number of studies have associated
the gut microbiota with health and disease, but with little consensus on which specific
bacterial groups are important for causing or maintaining either state. A majority of
microbiome studies only identify associations between the gut microbiome and health
status, and determining causation requires the isolation and growth of bacterial isolates
for further experiments. The goal of this thesis is to demonstrate that the combination of
culture-based and culture-independent methods describes greater complexity and
diversity in the human gut microbiota than observed by either approach alone. In the first
study, a method of culture-enriched molecular profiling could capture the majority of
bacterial groups found in fecal samples. Additionally, when compared to culture-independent
16S rRNA gene sequencing, culture detected more bacterial taxa. This
method was applied to the targeted culture of the commensal Lachnospiraceae family.
The second study explored the diversity in the isolated Lachnospiraceae strains, and
compared the genetic diversity of the strains to reference genomes, revealing functional
and genetic heterogeneity within the bacterial family. The third study characterized the
intra-species phenotypic and genetic diversity in Escherichia coli. E. coli diversity was
extensive between individuals, but also within-individuals, in both the phenotypes and
genetic profiles. Lastly, a method of culture-enriched metagenomics was applied to a
murine IBS microbiota transfer model to identify bacterial members of the microbiota and
their functional pathways that may be responsible for the development of gastrointestinal and behavioural IBS phenotypes, although no bacterial groups could be conclusively
associated with symptoms. Together, the work described demonstrates that culture and
culture-independent methods are complementary, and provides more resolution into the
structure and diversity of the human gut microbiome than either approach in isolation.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract:
Bacteria that inhabit the human intestine are important for health, and are involved
in several diseases; therefore, it is critical to determine the roles of specific bacteria. I
describe a method that results in the growth and recovery of most bacteria in stool, which
allows them to be studied in detail. The differences, both in behaviour and in DNA
sequences, found within two different bacterial groups were characterized, and extensive
variability was observed between closely related bacteria. I studied which bacteria and
their functions might be important in Irritable Bowel Syndrome (IBS) by using our
method for growing stool bacteria combined with sequencing of all DNA in the stool, but
could not find strong support for specific bacteria causing IBS symptoms. This work
shows how the ability to grow and isolate bacteria, combined with studying their DNA,
allows for better understanding of their functions in the human intestine.


title: IMMOBILIZATION AND CHARACTERIZATION OF FLEXIBLE DNAzyme-BASED BIOSENSORS FOR ON-THE SHELF FOOD MONITORING

contributor:
D. M. Filipe, Carlos
F. Didar, Tohid
Chemical Engineering

subject:
DNAzyme
Biosensors
Surface Immobilization
Epoxy
Amine
NHS
DNA
E.Coli
Bacteria Detection
Food Monitoring
Packaging Biosensors

abstract:
While the Canadian food supply is among the healthiest in the world, almost 4 million (1
in 8) Canadians are affected by food-borne illnesses, resulting in 11,600 hospitalizations
and 238 deaths per year. Microbial pathogens are one of the major causes of foodborne
sicknesses that can grow in food before or following packaging. Food distribution is an
important part of the food processing chain, in which food supplies are at a higher risk of
contamination due to lack of proper monitoring. Among myriad of research around
biosensors, current devices focusing on packaged food monitoring, such as leakage
indicators or time temperature sensors are not efficient for real-time food monitoring
without separating the sample from the stock. Packaged food such as meat and juice are
directly in touch with the surface of their containers or covers. Therefore, real-time sensing
mechanisms, installed inside the food packaging and capable of tracing the presence of
pathogens, are of great interest to ensure food safety. This work involves developing thin,
transparent, flexible and durable sensing surfaces using DNA biosensors, which report the
presence of a target bacterium in food or water samples by generating a fluorescence signal
that can be detected by simple fluorescence detecting devices. The covalently-attached
DNA probes generate the signal upon contact with the target bacteria with as low as 103
CFU/mL of Escherichia coli in meat and apple juice. The fabricated sensing surfaces
remained stable up to several days under varying pH conditions (pH 5 to 9). In addition to
detecting pathogens on packaged food or drinking bottles, these surfaces have the potential
to be used for a variety of other applications in health care settings, environmental
monitoring, food production chain, and biomaterials like wound dressing.

abstract: Thesis

abstract: Master of Science (MSc)

abstract:
Microbial pathogens can grow in food following packaging and preceding consumption.
Current biosensors are not efficient for post-packaging real-time food monitoring without
separating the sample from the stock. Packaged food such as meat and juice are directly in
touch with the surface of their containers or covers. Therefore, real-time sensing
mechanisms, installed inside the food packaging, tracing the presence of pathogens, are
much useful to ensure the food safety. Here we report on developing thin, transparent,
flexible and durable sensing surfaces using DNA biosensors, which generate a fluorescence
signal in the presence of a target bacterium in food or water samples. The covalentlyattached
DNA probes can detect as low as 103 CFU/mL of Escherichia coli in meat, sliced
apple and apple juice. The fabricated sensing surfaces remained stable up to several days
under varying pH conditions (pH 5 to 9). In addition to pathogen monitoring in packaged
food or drinking bottles, these surfaces are promising for a variety of other applications in
health care settings, environmental monitoring, and biomaterials like wound dressing.


title: THE RELATIONSHIP BETWEEN CAPILLARIES AND MUSCLE STEM CELLS: CONSEQUENCES FOR ADAPTATION, REPAIR AND AGING

subject:
muscle stem cells
muscle capillaries
satellite cells
muscle aging
muscle repair

abstract: Skeletal muscle possesses a remarkable plasticity, able to repair, remodel and adapt to various stressors. A population of resident muscle stem cells, commonly referred to as satellite cells (SC), are largely responsible for skeletal muscle plasticity. The loss of muscle mass and plasticity typically observed in aging has been attributed to the deterioration of SC function. SC reside in a quiescent state, but following stimuli they become active, proliferate and eventually differentiate, fusing to existing muscle fibres. The progression of SC through this process, termed the myogenic program, is orchestrated by a complex network of transcription factors, termed myogenic regulatory factors. SC function is regulated by various growth factors and/or cytokines. The delivery of these signalling factors to SC is, in part, dependent on their proximity and exposure to local microvascular blood flow. The purpose of this thesis was to examine the relationship between skeletal muscle capillaries and muscle SC. We examined the effect of age on the spatial relationship between SC and muscle fiber capillaries, and observed that type II muscle fiber SC were located at a greater distance from the nearest capillary in older men as compared to their younger counterparts. We then examined the changes in SC activation status following a single bout of resistance exercise, prior to and following a 16wk progressive resistance training (RT) program. We observed that following RT, there was an enhanced SC activation in response to a single bout of resistance exercise. This enhanced response was accompanied by an increase in muscle capillarization following training. Furthermore, we investigated the impact of muscle fiber capillarization on the expansion and activation status of SC in acute response to muscle damaging exercise in healthy young men. We observed that muscle capillarization was positively related to SC pool activation and expansion. Taken together, we demonstrate that muscle capillarization may be related to the SC response following acute resistance exercise or exercise-induced injury, and may be implicated in adaptation to RT. Furthermore, the spatial relationship between muscle capillaries and SC is negatively altered by aging.

abstract: Thesis

abstract: Doctor of Philosophy (PhD)

abstract: Skeletal muscle health is, in part, maintained by a population of stem cells associated with individual muscle fibres. When muscle is damaged or stressed, these cells become activated, aid in muscle repair, and help drive adaptations to exercise. The central purpose of this thesis was to examine the relationship between muscle capillaries and muscle stem cells, and determine how that relationship impacts muscle stem cell function. We demonstrated that muscle stem cells and capillaries exist in close proximity to each other in skeletal muscle. We observed that a greater muscle capillarization is linked to improved muscle stem cell function during muscle repair. However, we also report that the distance between muscle capillaries and muscle stem cells becomes greater in aging, and may be a root cause of impaired muscle stem cell function in aging.


title: "If they fund people with good food, maybe they don't end up on the medical end of things...": Food Insecurity and Type 2 Diabetes among People Receiving Food Assistance in Halton Region, Ontario

contributor:
Moffat, Tina
Anthropology

subject:
food insecurity
type 2 diabetes
syndemics
syndemic theory
social determinants of health

abstract: The present study investigates the self-care and health maintenance strategies undertaken by individuals from Halton Region, Ontario living with type 2 diabetes and receiving assistance from food acquisition services such as community food re-distribution centres and food banks. This qualitative research project pulls narrative and thematic interview data from 18 semi-structured one-on-one interviews analyzed with syndemic theory and social determinants of health frameworks to demonstrate how clustering non-communicable diseases and social conditions disproportionately affect those in the lowest income category, and interact with each other to exacerbate the negative health effects of each condition alone. The contributions of this study are theoretical and applied. Theoretical contributions augment existing evidence for the study of non-communicable diseases using a syndemic model. The study participants demonstrated syndemic clustering of five conditions: type 2 diabetes, food insecurity, low income, poor mental health, and activity limitation. Further, this study suggests an applied element to the syndemic model through an approach to health and diabetes care that incorporates the whole person as opposed to a single disease as a unit of care. As suggested through the findings of research participant testimony, a diabetes health care centre, in addition to traditional diabetes care, would ideally screen and offer care for the other common clustered conditions listed in the syndemic elements above. Thus, the centre would provide nutrition, physical activity, mental health, and social supports to patients. As well, it is recommended that future research contributes to prevention and treatment of non-communicable diseases through social, political, and economic in form of increasing government and healthcare supports for people living with low-income and food insecurity.

abstract: Thesis

abstract: Master of Arts (MA)

abstract: This study looks at how individuals from Halton Region, Ontario maintain their health while living with type 2 diabetes and reduced access to healthy, fresh food. The project uses interview data from 18 one-on-one interviews to demonstrate how people with low income suffer from poorer overall health. Specifically, five conditions affected the study participants’ health: type 2 diabetes, reduced access to healthy food, low income, poor mental health, and reduced financial or physical access to exercise or activities of daily living (activity limitation). To combat these conditions, this study suggests an approach to health and diabetes care that looks at the whole person. Evidence and participant suggestions indicate a diabetes health care centre that screens and offers care for other common conditions that occur such as the elements listed above, and also provides nutrition care, physical activity, and social support to patients.


title: The Role of SCFAs in 5HT Mediated Colonic Motility

contributor: Medical Sciences (Division of Physiology/Pharmacology)

subject:
short-chain fatty acids
serotonin
motility
enterochromaffin cell

abstract: Introduction: The role of short-chain fatty acids (SCFAs) in colonic motility is controversial. Germ free (GF) mice are unable to produce SCFAs and serve as a model to study how their absence affects colonic motility. GF transit is slower than controls and colonization of these mice improves gastrointestinal (GI) transit and serotonin (5-HT) levels. Our aim was to determine the role SCFAs play in improving transit, and whether this is dependent on mucosal 5-HT signaling. Methods: Motility was assessed in GF mice via spatiotemporal mapping with intraluminal perfusion of either PBS or SCFA cocktail. Outflow from the colon was recorded to quantify propulsive contractions. Motility was then assessed in TPH1-KO mice with PBS, butyrate and then propionate. GPR43 and 5-HT staining was performed in control and GF colons. Mice were then given chow diet or high sugar diet (HSD) and motility was recorded. Fecal pellets were taken at baseline and just prior to motility experiments and SCFA levels were measured with mass spectrometry. Results: GF mice exhibit significantly lower proportion of propulsive contractions, lower volume of outflow per contraction and slower velocity of contractions compared to controls. SCFAs changed the motility patterns to that of the controls in all parameters. Butyrate administration significantly increased the proportion of propulsive contractions in controls, yet failed to in TPH1 KO mice. Propionate significantly inhibited propulsive contractions in both mice. HSD-fed mice were not different from chow-fed mice in any parameter. No SCFA was significantly reduced, but the change in butyrate concentration was significantly associated with LDC frequency. Conclusions: Our results reveal significant abnormalities in the propulsive nature of colon motor patterns in GF mice, explaining the decreased transit time in in vivo studies. We show that butyrate, not propionate, activates propulsive motility and that this requires mucosal 5-HT, possibly released by ECs.

abstract: Thesis

abstract: Master of Science (MSc)


title: Evolutionary and plastic responses of Drosophila under predation risk

contributor:
Dworkin, Ian
Biology

subject:
Drosophila melanogaster
Genetics
Experimental Evolution
Mating Behaviour
Locomotor Activity
Genomic Evolution

abstract: The “risk allocation hypothesis” can predict how prey species will respond to predation risk, balancing vigilance with potentially risky behaviours. In order to maximize fitness, an optimal behavioural repertoire can evolve to respond to predation threat to allow for both survival and future fitness gains. High locomotor activity and time spent engaging in mating behaviours are expected to put Drosophila melanogaster at a greater risk to predation. With direct predator exposure, Drosophila are predicted to reduce activity and mating, which over years of exposure, will be reflected in evolved behavioural traits and evolved changes in the genome. Predation as a selective force shows alterations in flies genomes of experimentally evolved populations. Locomotor activity was found to be reduced in the presence of zebra jumping spiders (Salticus scenicus), presumably due to these spiders as visual hunters, using movement to detect prey. This behaviour is reflected in populations of Drosophila that have been constantly under selection by predators. Flies evolved with spider predators or mantid predators (Tenodera aridifolia sinensis) showed reduced locomotor activity when no predators are present. Interestingly, while alterations are seen for locomotory activity, the presumed risky behaviours of courtship and mating did not show an evolved response. Wild caught populations under threat from spiders, as well as the evolved populations when no predators were present showed no alterations in courtship or copulation behaviour. It appears that although there may be potential risks associated with mating behaviours,  the benefits to future fitness when mating outweigh the potential costs from predation risks in Drosophila.

abstract: Thesis

abstract: Master of Science (MSc)

abstract: Predation is a profound selective force, with many anti-predator adaptations seen throughout the diversity of life. Antipredatory behavioural adaptations must balance immediate and future fitness effects, to maximize overall fitness. In Drosophila melanogaster, research into  natural ecology and role of predation is generally lacking for behavioural & evolutionary studies. I will discuss research on the influence of predator exposure on Drosophila behaviours, as well as the evolution of Drosophila behaviours and genomes through experimentally evolved populations of Drosophila. While predation risk has resulted in changes in Drosophila locomotory activity, predation has not altered mating behaviours.


title: Meals in Motion: Ceramic and Botanical Investigations of Foodways in the Late Formative and Tiwanaku IV/V, Lake Titicaca Basin, Bolivia

contributor:
Roddick, Andrew
Anthropology

subject: Foodways; paleoethnobotany; ceramics; Titicaca Basin; archaeology

abstract:
In Andean South America, archaeological research demonstrates that rituals surrounding the consumption of food and drink have long played an important part in building relationships between individuals, families, and communities. This thesis focuses on foodways in the Late Formative (200BC-AD475) and Tiwanaku (475-1000AD) phases of the Lake Titicaca basin in highland Bolivia. I pair ceramic and botanical datasets from three assemblages: Late Formative contexts from Kala Uyuni (southern Titicaca Basin) and Challapata (eastern Titicaca Basin), and a Tiwanaku phase burial at Chiripa (southern Titicaca Basin). The goals of this thesis are to: identify microbotanical plant remains of foods associated with ceramic vessels, consider how these inform archaeological understandings of Titicaca Basin foodways, and evaluate whether studying plant residues from ceramic vessels is an effective method to study foodways.
	Phytoliths and starch grains recovered from Challapata and Chiripa included remains of both local and non-local plants, while the Chiripa ceramic assemblage included non-local ceramic styles. These results offer new evidence for exchange between highland and lowland sites. Both local and non-local plant remains were recovered in public spaces where ceremonies may have taken place. While non-local goods may have been desirable and special because they were difficult to obtain, results of this thesis suggest that local plants may have been just as symbolically important. Overall, results indicate that pairing ceramic and botanical datasets can enable a richer understanding of foodways.

abstract: Thesis

abstract: Master of Arts (MA)


title: Mixtec Foodways in Achiutla: Continuity Through Time. A Paleoethnobotanical Study Comparing the Postclassic and Early Colonial Diet

contributor:
Morell-Hart, Shanti
Anthropology

subject: Foodways, paleoethnobotany, archaeology, Mixtecs, Oaxaca, Colonial Period

abstract:
Numerous historical reports written by Spaniards in the Americas during the Early Colonial Period describe public life. However, less is known about quotidian lives during this period. In the Mexican state of Oaxaca, a region encompassing dozens of cultural groups, little is known about the everyday life of Mixtecs and how they reacted towards the newly established Spanish authority in their households. When they arrived at Achiutla, one of the biggest religious centres of ancient Oaxaca (Byland 2008), the Spaniards imposed their power on the public sphere, using religion and economy amongst others (Terraciano 2001:294, 340). My objective is to study the Mixtecs’ reaction to the arrival of Spaniards in the region by using paleoethnobotany to study foodways and how Achiutla’s inhabitants negotiated the arrival of new food items and to what level they accepted, incorporated, and resisted them.
This study presents the traditional Mixtec and Spanish foodways and the important role they played in their beliefs, traditions, and identities. I present elements supporting the claim that certain Spaniards might have tried to modify Indigenous foodways in the Americas, while others believed it was preferable for Spaniards and Indigenous people to eat different foods. This study also presents other results obtained in Colonial foodways studies made in the Americas and in the Mixteca Alta region.
This study includes the analysis of 27 paleoethnobotanical samples, 22 of them being macrobotanical remains obtained from light fractions and 5 of them coming from microbotanical residues extracted from artifacts. All these samples were collected by Jamie Forde in 2013 at San Miguel Achiutla in the course of the PASMA archaeological project and come mainly from two terraces (10 and 13) likely occupied by Mixtec nobility. By combining samples coming from the Postclassic and the Early Colonial Periods, this study establishes the Mixtec diet prior to the arrival of Europeans in the region, enabling a better comparison between the two. This study supports the idea that the Mixtec diet likely remained the same at Terraces 10 and 13 during the Postclassic and the Early Colonial Periods. Two genera dominate the paleoethnobotanical assemblage: Chenopodium sp. (pazote, apazote) and Amaranthus sp. (huisquelite or quelite), the presence of which demonstrates continuity through times. I assess different scenarios that might explain the absence of European introduced plant species at Achiutla, cautiously presenting a hypothesis linked to Mixtec colonial resistance.

abstract: Thesis

abstract: Master of Arts (MA)


title: Adrenal chromaffin cell function in high-altitude deer mice (Peromyscus maniculatus)

contributor:
Scott, Graham
Nurse, Colin
Biology

subject:
High-altitude adaptation
Nicotinic Acetylcholine Receptors
Calcium Signalling
Catecholamine Storage
Adrenaline

abstract: The deer mouse (Peromyscus maniculatus) inhabits a broad altitudinal range from sea level to over 4300m, where they experience continuous hypoxia.  Typically hypoxia activates the sympathetic nervous system; however this could become maladaptive in high-altitude residents if it is maintained over chronic periods. We hypothesized that high-altitude deer mice might have altered the physiology of adrenaomedullary chromaffin cells (AMC) in the adrenal gland to avoid chronic activation of the sympathetic response.  Highland mice had lower plasma adrenaline levels compared to lowland populations of Peromyscus mice, both before and after acclimation to hypobaric hypoxia. This did not correspond to any apparent changes in AMC Ca2+-signalling dynamics.  Instead a profound blunting of catecholamine storage was found in highland AMCs that appeared to underlie the reduction in adrenaline release

abstract: Thesis

abstract: Master of Science (MSc)