Student Theses

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A pathogenic examination of virulent and avirulent aerococcus viridans var homari
The American lobster (Homarus americanus) is the most successful commercial fishery in Canada. The industry creates 7800 jobs in the Atlantic region, making it a pivotal part of the local economy in rural Atlantic Canada. When lobsters are harvested, they are either sent directly to market, or kept in storage to ensure there is a supply of live lobster available for consumers year-round. The lobster fishery experiences periodic post-harvest loss due to an infection called gaffkemia. Gaffkemia is caused by the bacterium Aerococcus viridans var. homari. Large live lobster storage facilities have A. viridans screening procedures in place to limit post-harvest loss, but they are not sensitive enough to differentiate between naturally occurring virulent and avirulent strains. When a shipment tests positive for the bacterium, this creates a financial burden on the facility as they must treat the shipment and it must be sold at a lower value. This project hopes to characterize genomes of virulent and avirulent strains of A. viridans var. homari to identify the factors responsible for virulence in this bacterium. This project uses genomic approaches to identify variations in the genomes of virulent and avirulent strains of A. viridans var. homari. Genomic polymorphisms were compared between the phenotypes and putative virulence factors and impacted metabolic pathways were identified. No pathways had a significantly different number of polymorphisms between the phenotypes. However, the results of this study do indicate that particular regions of the genome are more prone to mutation than others.
Developing a memory representation: Do we visualize or do we "verbalize" objects as we explore them?
Participants typically perform better when testing conditions match learning conditions, a phenomenon labeled encoding specificity. Interestingly, recent findings in visuo-haptic object identification violate this principle: participants who learn to recognize objects haptically perform just as well when asked to identify objects by sight as by touch. One possible explanation is that participants who explore objects haptically visualize the objects they explore, creating a multisensory memory trace equally accessible to vision and touch. I evaluated this possibility by asking healthy undergraduate participants to learn to recognize novel objects either by sight or by touch. Participants completed sequences of learning trials where they explore each object, and test trials where they recall the name of each object. During learning trials, some participants were presented with a visual distractor (half of participants viewed letters and the other half viewed nonverbal characters) they had to recognize later, while other participants completed a distractor-less control condition. Consistent with past findings, my results violated encoding specificity for participants who learned to recognize objects haptically. Interestingly however, only the verbal distractors interfered with learning. These results suggest that the creation of memory representation for novel objects is mediated by a verbal code rather than through visualization.
Electrochemical mechanisms of hydrogen incorporation in electroless copper films
Hydrogen incorporation in electroless copper films is a well-known source of void formation and embrittlement, which reduces the ductility of copper films and can lead to circuit failure. A non-invasive method for measuring hydrogen incorporation in electroless Cu films was utilized, and a method for driving the surface potential of the substrate is implemented. Films with rougher substrate surfaces incorporate more hydrogen, and take significantly longer to release it, than smoother surfaces of the same substrate. The stabilizer system is the fundamental driver of hydrogen incorporation into electroless Cu films. Additionally, a method for investigating the mechanism by which nickel lowers hydrogen incorporation is put forward.
Endocannabinoids and nitric oxide effect on high-fat food consumption in young rats
Childhood obesity has become an increasingly prevalent disease worldwide, predisposing children and adolescents to physiological and psychological health complications, extending into adult years. Generally, weight gain is a result of a prolonged imbalance of food intake and energy expenditure. Further investigation of pathways affecting appetite regulation is required to develop safer, effective treatments for obesity. Two signals of interest are endocannabinoids (eCBs) and nitric oxide (NO), which have been shown to regulate food intake in adult animals. Research in young animals is limited, but it has been suggested that these neurotransmitters have different age-dependent effects on appetite in rats fed a standard diet. The current investigation was undertaken in fasted and non-fasted rats fed a high-fat diet, to gain insight into the effect of inhibiting or exciting eCB and NO pathways on palatable food consumption. In the first condition, young Sprague-Dawley rats were fasted for 24 hours, assigned randomly to a drug treatment or control group, and were refed for a 2-hour period, after which they were sacrificed and perfused. Food consumption data and accompanying body weight data were collected from each trial. In fasted animals, inhibiting the production of nitric oxide was shown to significantly reduce food intake and body weight, and blocking cannabinoid receptors also resulted in a significant decrease in food consumption compared to a control group receiving saline injections. In subsequent trials in non-fasted animals, blocking cannabinoid receptors resulted in a significant decrease in body weight compared to control animals. Results demonstrated that the manipulation of eCB and NO pathways in young rats fed a high-fat diet differed in their effects when compared to standard diet fed animals. These results confirm that further investigation is needed in non-fasted animals, as well as animals chronically exposed to a high-fat diet, to understand the physiological response of these pathways to drug interference.
Good spellers make good readers but not vice versa: Reading speed and spelling ability
Reading and spelling are two fundamental skills that are clearly linked, but that are also distinct; many individuals can read words that they cannot spell. Recent research has found that reading speed tends to be higher when one knows how to spell the word, but the precise explanation for this observation is not clear. To address this, 51 undergraduate students were tested on their reading speed and spelling accuracy to confirm the association between these abilities and to examine the effect of the location of spelling errors within a word on reading speed as an explanation for this relationship. At present, it is uncertain how error location may affect reading, as different theories lead to different predictions in this respect: some theories suggest that errors in the middle of a word may be more detrimental to reading speed than errors at the beginning, and others propose the reverse. Participants were tested on 25 words, each presented three times. Reading speed was measured using SuperLab 5.0 and spelling accuracy was measured using handwritten spelling tests. A within participant analysis confirmed that words that were spelled correctly all three times were read faster than words that were never spelled correctly. Analysis of spelling error location failed to find any significant effect of error location on reading speed. The connection between spelling accuracy and reading speed is in line with previous research on the lexical quality hypothesis, yet further research is required to explain the impact of specific spelling errors on reading.
Harnessing innovation through work and organizational structure: A study of the forest fire fighting sector in New Brunswick, Canada
This thesis conceptualises the conditions that facilitate innovative and extra-role responsive work behaviour in the context of organizational structure and job design. It explores the idea that innovative work behaviour is largely a result of the facilitation of responsiveness and adaptation to internal and external influences acting on the organization and institutional actors. This study examines the intersection and overlap of proceduralism and innovation and investigates the dichotomy of structure and adaptability. This research considers innovation as the intentional creation, introduction and application of new ideas for the purpose of problem solving and increasing the efficiency of means to ends decision making. The study comprises an in-depth investigation into New Brunswick forest fire management to better understand opportunities to harness innovation. Ten semi-structured interviews of experts and stakeholders were conducted throughout New Brunswick’s forest fire management network to determine the extent that organizational arrangements support innovative work behaviour amongst the responders. These interviews targeted publicly employed managers and Forest Rangers, volunteer fire fighters and private forestry industry partners. This research argues that facilitating adaptation through flexibility, open communication and joint initiatives, can increase the likelihood of responders deciding to exhibit discretionary effort and extra role innovative behaviours. Through practices like inter-organizational training initiatives and joint after action reviews, innovation can be promoted at an individual level for the benefit of the entire organization and the forest fire fighting network. Conceptually, this research contributes to an under-researched region of Canadian forest fire management, and provides a conceptual base for future comparative projects amongst Canadian provinces to better understand network working within and between provinces.
Molecular testing of Lyme Disease
Lyme disease is a tick-vectored multisystemic illness caused by the bacteria Borrelia burgdorferi sensu lato contracted throughout North America and Eurasia. Although Lyme disease is the most common tick-vectored illness in North America, many questions about the disease such as pathophysiology and organ involvement remained unresolved. Additionally, persistence of the Borrelia bacteria after antibiotic treatment is controversial and the role of antibiotic tolerant bacteria in causing chronic Lyme disease symptoms is even less well understood. The reliance on serological testing in Lyme disease leaves many questions unanswered and accurate diagnosis of Lyme disease in certain situations is challenging. To address some of these outstanding questions, direct detection of Borrelia from biopsy and autopsy tissue and culturing of Borrelia from patients showing persistent Lyme disease symptoms can be valuable. In this study, I investigated autopsy tissues using the DNA-based detection methods of nested PCR and Fluorescent in situ hybridization (FISH) and the protein-based technique of immunohistology from seropositive, seronegative, and serologically untested individuals. This study showed that Borrelia was widely distributed in different organs in both seropositive and seronegative participants. These techniques were then extended to biopsy tissue samples. My findings showed that B. burgdorferi is pleiomorphic, with FISH and immunohistology showing predominantly round body and biofilm forms with fewer in the spirochetal form. Finally, I showed that culture of viable Borrelia is possible from different body fluids from participants with persistent Lyme disease symptoms. This finding strengthens the evidence that chronic Lyme disease is associated with an active and long-standing Borrelia infection. Findings from this study could be extended to investigation of other tick-vectored diseases and reinforce the potential for the use of direct molecular methods in disease diagnosis.
Nanotoxicology: The impacts of 5 nm silver nanoparticles on protein synthesis of rainbow trout (oncorhynchus mykiss)
Silver nanoparticles (nAg) are becoming increasingly prevalent in consumer products due to their unique physicochemical properties. This excessive usage is causing nanoparticulate waste to end up in the water column with the potential to affect aquatic organisms. Previous research has shown damaging effects of engineered nanomaterials (ENMs) on various fish species with the current study aimed to identify the impacts of polyvinyl pyrrolidone (PVP) capped 5 nm silver nanoparticles on biochemical stress indicators and rates of protein synthesis in rainbow trout (Oncorhynchus mykiss). Fish were exposed to 100 μg L-1 nAg or 0.22 μg L-1 AgNO3 for 48 hours and tissue samples taken. Biological endpoints analyzed included hematocrit, gill sodium potassium ATPase, heart acetylcholinesterase, and cortisol and malondialdehyde content. Fractional rates of protein synthesis were determined by flooding dose method modified to use a stable phenylalanine isotope tracer. No significant differences were observed between treatment groups for any of the biologically relevant endpoints nor protein synthesis rates, although a decreasing trend was observed for sodium potassium ATPase activity in nAg-exposed fish. Results suggest that rainbow trout exposed to silver ENMs for 48 hours at the environmentally relevant point-source exposure concentration tested are not expressing signs of significant damage nor exhibiting impaired metabolism indicating that under short term conditions 5 nm PVP-capped nAg at 100 μg L-1 is not acutely toxic. These findings are disputable as previous research has demonstrated the toxic effects of ENMs on fish physiology, including on the endpoints analyzed in this study. These results should encourage further research into longer exposure durations and investigating other potential sublethal effects.
Neutron scalar polarizabilities
The known values for the scalar polarizabilities of the neutron have a relatively large experimental error compared to that of the proton. Previously these values were found by analyzing the results of Compton scattering with a deuterium target, but this method has many causes for uncertainty. The A2 collaboration at the Institut fur Kernphysik at Johannes Gutenberg Universitat in Mainz, Germany, plans to measure the neutron polarizabilities in a new way. Now, similar Compton scattering based experiments will be carried out with a new active target filled with high-pressure 3He gas. This active target will allow previously unmeasured quantities of the reaction to be analyzed, thus reducing the background noise of the data, and therefore lowering the experimental error. But to do this software has to be used to reconstruct the events within the active target. The new active target and the software used to reconstruct it are still in development; in particular, I will be aiding in the development of the software.
Pairwise completely false matrices with applications in Quantum Information Theory
This thesis introduces a generalization of the set of completely positive matrices that we call “pairwise completely positive” (PCP) matrices. PCP matrix pairs are defined so that one matrix in the pair is necessarily positive semidefinite while the other is necessarily entrywise non-negative. After PCP matrices are defined we explore their basic properties and establish numerous necessary and sufficient conditions that can help test whether or not a pair meets our definition of PCP. We then relate these matrix pairs to the separability of conjugate local diagonal unitary invariant (CLDUI) quantum states. In particular, we show that determining whether or not a pair of matrices is pairwise completely positive is equivalent to determining whether or not a corresponding CLDUI state is separable.

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