identifier: Collins, Sydney M. <https://research.library.mun.ca/view/creator_az/Collins=3ASydney_M=2E=3A=3A.html>   (2021) Terrestrial and marine risks for leach's storm-petrels during the breeding season.  Masters thesis, Memorial University of Newfoundland.

abstract: Globally, seabirds are in decline, so comprehensive efforts are needed to understand risks facing these species. Leach’s Storm-Petrels are globally identified as ‘Threatened’, and my thesis addresses two factors which pose risk during the breeding season for the population breeding at Gull Island, Newfoundland: predation and light attraction. Chapter 2 investigates activity associations between breeding storm-petrels and nearby predatory Herring Gulls to gauge predation risk. Herring Gull activity was negatively associated with, and was the most important predictor of, Leach’s Storm-Petrel activity, suggesting that storm-petrels modify their colony activity in response to their top predator. Chapter 3 examines foraging tracks of parental storm-petrels to assess risk from light attraction to offshore oil platforms. This population of storm-petrels was consistent in foraging trip duration, distance, behaviour, and location. They transited past oil platforms during the day, thereby minimising risk. Breeding season risks from predation and light attraction are minimised by existing constraints on behaviour, so future research should focus on other risks to adults along with the juvenile and immature phases of the life cycle. Overall, I demonstrate that a comprehensive examination of risks facing seabirds throughout their life cycle is vital for informing effective mitigation efforts.


identifier: Montero Vega, Sheyla <https://research.library.mun.ca/view/creator_az/Montero_Vega=3ASheyla=3A=3A.html>   (2021) Interaction between antimicrobial peptides and non-lipid components in the bacterial outer envelope.  Masters thesis, Memorial University of Newfoundland.

type: Thesis NonPeerReviewed

abstract: Antimicrobial peptides (AMPs) offer advantages over conventional antibiotics; for example, bacteria develop resistance to a lesser extent to AMPs than to small-molecule antibiotics. The interaction of the AMPs with the liposaccharide (LPS) layer of the gram-negative bacteria cell envelope is not well understood. I constructed a MARTINI model of a gram-negative bacterial outer membrane interacting with the AMP Magainin 2. In a 20 μs MD simulation, the AMP diffused to the LPS layer of the cell envelope and remained there, suggesting interactions between the Magainin 2 and the LPS layer causing the AMP to concentrate at that position. Furthermore, the free energy profile for the insertion of the Magainin 2 into the membrane was calculated using umbrella sampling, which showed that the AMP positioned such that the cationic sidechains of the AMP coordinated to the negatively charged phosphate groups of the LPS layer. These simulations indicate that AMPs partition into the LPS layer of a bacterial membrane.


identifier: Tran, Trung Tien <https://research.library.mun.ca/view/creator_az/Tran=3ATrung_Tien=3A=3A.html>   (2021) Multi-objective route selection for ice-class vessels using reinforcement learning and graph-based approaches.  Masters thesis, Memorial University of Newfoundland.

abstract: Route selection for ships in ice is a complicated problem in marine navigation. The navigators have to optimize many economic and environmental factors of the routes while adhering to all maritime regulations to ensure safety. The International Maritime Organization has introduced the Polar Operational Limit Assessment Risk Indexing System (POLARIS) as guidelines for all vessels operating in the Arctic Ocean. This research investigates a framework for finding an optimal route for different ice-class vessels using two methods: graph-based approaches and reinforcement learning. The system uses ice charts from the Canadian Ice Service to explore possible routes in a grid world. Reward and cost functions are formulated to achieve operational objectives, such as optimizing the distance travelled, voyage time, and fuel consumption while complying with POLARIS regulation. The graph-based method surpasses the Q-learning in deterministic cases. Despite the shortcoming of not handling the non-deterministic environment, it also shows similar routes compared to Q-learning in a stochastic context. The trial results show that the framework provides a means to identify an optimal route for vessels navigating through ice-covered waters.


identifier: Zhai, Tianren <https://research.library.mun.ca/view/creator_az/Zhai=3ATianren=3A=3A.html>   (2021) Global dynamics of two population models with spatial heterogeneity.  Masters thesis, Memorial University of Newfoundland.

abstract:
Mathematical models provide powerful tools to explain and predict population dynamics.
A central problem is to study the long-term behavior of modeling systems.
The patch models and reaction-diffusion models are widely applied to describe spatial
heterogeneity and habitat connectivity.
Basic reproduction number R₀ plays an important role in mathematical biology.
In epidemiology, R₀ stands for the expected number of secondary cases produced in
a completely susceptible population by a typical infective individual. The value of
R₀ can determines the persistence or extinction of population. Nowadays, characterizing
the basic reproduction number due to the effects of parameters becomes very
significant for predicting and controlling disease transmission.
This thesis consists of three chapters. In Chapter 1, we investigate the effect
of spatial heterogeneity on the basic reproduction number for an SIS epidemic patch
model, and compute R₀ numerically to show the influence of the spatial heterogeneity
and movement. Chapter 2 is devoted to the study of the global dynamics of a reaction diffusion model arising from the dynamics of a kind of mosquitos named A. aegypti in
Brazil. We first prove the global existence and boundedness of the solutions. Secondly,
we establish the threshold type dynamics in terms of the basic reproduction ratio R₀.
In Chapter 3, we briefly summarize the main results and present some future works.


identifier: Baliyarsingh, Utkal Kumar <https://research.library.mun.ca/view/creator_az/Baliyarsingh=3AUtkal_Kumar=3A=3A.html>   (2021) A systematic review of CEO duality and firm performance in different organizational contexts.  Masters thesis, Memorial University of Newfoundland.

abstract: CEO duality is a situation that emerges when the Chief Executive Officer (CEO) also serves as the Chair of the Board of Directors. In absence of CEO duality, the board is considered independent. CEO duality as an issue is of utmost importance in the field of corporate governance and corporate strategy. From its scholarly inception in the early 1990s this phenomenon has become more complex with contradicting and mixed results, which is evident from the extant literature. The inconclusive nature of the debate prompts researchers to look beyond a direct link between CEO duality and Firm performance. To understand the nature of this phenomenon, a systematic literature review was conducted uncovering 62 research articles over a period of almost two decades. First of all, the review suggests that given its broad and multidisciplinary relevance, the current form of literature on CEO duality needs more organization. Second, the study identifies key research areas in which CEO duality was studied. Findings show that, although, CEO duality does not, on its own, improve or reduce firm performance, the performance implications of CEO duality could be dependent on various other firm specific parameters, which corporate boards need to acknowledge. Finally, this study discusses identified themes and highlights the need for a multi-level analysis followed by future research directions, management implications, and a limitation section.


identifier: Kelly, Liam P. <https://research.library.mun.ca/view/creator_az/Kelly=3ALiam_P=2E=3A=3A.html>   (2021) Designing aerobic exercise interventions for stroke rehabilitation.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
More than 405,000 Canadians are currently living with the life-altering effects of
stroke. Cardiorespiratory fitness is characteristically low after stroke and has negative
consequences for functional recovery, cardiovascular risk, and quality of life in this
population. Although scientific evidence supports incorporating moderate-intensity
aerobic exercise during stroke recovery, these findings have not translated into clinical care
where patients are very sedentary and cardiorespiratory fitness levels remain in the “very
poor” category. Among the challenges to incorporating aerobic exercise include a lack of
access to the specialized equipment needed to accommodate stroke-related impairments.
Also, hemiparesis can limit stroke survivors’ ability to sustain the workloads needed to
reach moderate levels of aerobic intensity. Accordingly, the current thesis aimed to develop
exercise strategies that can overcome these barriers.
The first study investigated whether incorporating task-oriented activities typically
offered during stroke rehabilitation into circuits that pair more metabolically demanding
tasks with less demanding ones is an acceptable method to sustain moderate-intensity
aerobic workloads over a single session. The second study evaluated the feasibility and
preliminary effects of the task-oriented circuit-training protocol compared to treadmill
aerobic exercise over a 10-week intervention period among 40 chronic hemiparetic stroke
survivors. The final study investigated the safety and feasibility of pairing treadmill
walking exercise with moderate normobaric hypoxia as a means to increase the
cardiovascular strain of submaximal exercise among stroke survivors.
The task-oriented circuit training protocol was associated with at least moderateintensity
aerobic workloads over a single session and, compared to treadmill aerobic
exercise, similar proportions of participants were able to maintain the exercise criteria over
a 10-week intervention period. One participant reported mild symptoms of nausea during
treadmill walking under conditions of moderate normobaric hypoxia. No other adverse
events were observed, and participants maintained constant absolute workloads during
exercise in normobaric hypoxia, which was associated with a 10% increase in relative
effort.
The task-oriented circuit training protocol is a promising strategy to provide
moderate-intensity aerobic exercise training stimulus without specialized equipment.
Initial data also supports simulated altitude exposure as a safe and feasible method to
increase the cardiovascular stress of submaximal exercise among chronic hemiparetic
stroke survivors.


identifier: Flores, Katherine <https://research.library.mun.ca/view/creator_az/Flores=3AKatherine=3A=3A.html>   (2021) Gastropod grazing of epiphytic lichens in Western Newfoundland.  Masters thesis, Memorial University of Newfoundland.

abstract: Overgrazing by introduced gastropods has been identified as a potential threat to some rare or threatened epiphytic foliose lichens; however, gastropod grazing severity has not been evaluated within Newfoundland. Lobaria pulmonaria is locally abundant in Newfoundland but considered rare and threatened in parts of the U.S.A and Europe. To evaluate gastropod grazing severity and describe the tree-climbing gastropod community we conducted lichen diversity and lichenivory surveys and used two methods of gastropod sampling. To determine how lichen species diversity affects lichen grazing of L. pulmonaria, we conducted cafeteria feeding experiments using native and introduced snail species and common lichen species from our study area. We found that within the study area, some lichens including L. pulmonaria were severely overgrazed, and that tree-climbing gastropod abundance increased with greater grazing severity. We found that lichenivory severity was driven by tree-level factors and identified the most common tree-climbing slugs within the study area. Feeding experiment results showed that snails consumed greater lichen biomass with greater species diversity; however, distinct preferences for specific lichen species were apparent. Grazing severity of L. pulmonaria decreased with greater lichen species diversity, which suggests that L. pulmonaria may be more resistant to gastropod grazing in forests with higher foliose lichen species diversity.


identifier: Critch, Lucas <https://research.library.mun.ca/view/creator_az/Critch=3ALucas=3A=3A.html>   (2021) Using influence maps with heuristic search to craft sneak-attacks in Starcraft.  Masters thesis, Memorial University of Newfoundland.

abstract:
Real-Time Strategy (RTS) games have consistently been popular among AI researchers over
the past couple of decades due to their complexity and difficulty to play for both humans and
AI. A popular strategy in RTS games is a “Sneak-Attack,” where one player tries to maneuver
some of their units into the base of their enemy without being seen for as long as possible
to surprise their enemy and deal massive damage to their economy. This thesis introduces
a novel method for finding Sneak-Attack paths in StarCraft: Brood War by combining
influence maps with heuristic search. The combined system creates paths that can guide
units effectively - and automatically - into the enemy’s base, by avoiding enemy unit vision
and minimizing both travel distance and unit damage. For StarCraft, this involves guiding
a loaded transport ship to the enemy’s base to drop off units for attack. Our results show
that the new system performs better than direct paths across a variety of maps in terms of
total transport deaths, total damage taken, as well as the total time spent by the transport
within enemy vision. We then utilize this new system to demonstrate an alternate use: a
proof of concept for calculating building placements to defend against enemy sneak-attacks.


identifier: Bagheri, Mohammad <https://research.library.mun.ca/view/creator_az/Bagheri=3AMohammad=3A=3A.html>   (2021) EEG-based classification of visual and auditory monitoring tasks.  Masters thesis, Memorial University of Newfoundland.

abstract: Using EEG signals for mental workload detection has received particular attention in passive BCI research aimed at increasing safety and performance in high-risk and safety-critical occupations, like pilots and air traffic controllers. Along with detecting the level of mental workload, it has been suggested that being able to automatically detect the type of mental workload (e.g., auditory, visual, motor, cognitive) would also be useful. In this work, a novel experimental protocol was developed in which subjects performed a task involving one of two different types of mental workload (specifically, auditory and visual), each under two different levels of task demand (easy and difficult). The tasks were designed to be nearly identical in terms of visual and auditory stimuli, and differed only in the type of stimuli the subject was monitoring/attending to. EEG power spectral features were extracted and used to train linear and non-linear classifiers. Preliminary results on six subjects suggested that the auditory and visual tasks could be distinguished from one another, and individually from a baseline condition (which also contained nearly identical stimuli that the subject did not need to attend to at all), with accuracy significantly exceeding chance. This was true when classification was done within a workload level, and when data from the two workload levels were combined. Preliminary results also showed that tasks with easy and difficult trials could be distinguished from one another, each within a sensory domain (auditory and visual) as well as with both domains combined. Though further investigation is required, these preliminary results are promising, and suggest the feasibility of a passive BCI for detecting both type and level of mental workload.


identifier: MacMillan, Molly <https://research.library.mun.ca/view/creator_az/MacMillan=3AMolly=3A=3A.html>   (2021) The list length effect in short-term memory.  Masters thesis, Memorial University of Newfoundland.

abstract:
In free recall, the list length effect (LLE) refers to the finding that the proportion of
correctly recalled items decreases as set-size increases but at the same time the total number of
recalled items continues to increase with set-size (Murdock, 1962). Oberauer et al. (2018)
proposed that a decrease in memory accuracy as a function of increasing set-size was fundamental to conceptualizations of short-term and working memory. Evidence of a LLE in
short-term/working memory would contradict this benchmark. Beaman (2006) observed a LLE in serial recall whereas Unsworth and Engle (2006) observed no such effect in either serial recall or complex span. In the current research, we sought to reconcile these conflicting results. Six
experiments were conducted, examining the relationship between the number and proportion of
words recalled in both serial recall and complex span. No LLE was observed in either task.
Instead, the proportion of words recalled decreased as a function of list length, while the number
of words recalled initially increased, before either reaching a plateau or decreasing. The results suggest that recall accuracy decreases as a function of increasing list length due to increased
interference and decreased positional and temporal distinctiveness in longer lists.


identifier: Shabbir, Md Nasmus Sakib Khan <https://research.library.mun.ca/view/creator_az/Shabbir=3AMd_Nasmus_Sakib_Khan=3A=3A.html>   (2021) Advanced control schemes for wind power plants and renewable energy-based islanded microgrids.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
Renewable energy sources are increasingly integrated in power grids, creating significant challenges for control and system operation. Among various renewable energy sources, wind power is one of the dominant forms, mainly generated from large-scale transmission-connected wind power plants (WPPs). The grid-connected WPPs are required to follow grid codes to maintain a predefined power factor range under normal operation and supply required reactive power under faulty conditions. To meet grid code requirements, a WPP control architecture is developed in this thesis. The control system consists of a central WPP controller and a local wind turbine generator (WTG) controller, both operate in the voltage control mode. Therefore, the controller can respond faster and is robust to communication failures. Under normal operating conditions, the proposed controller regulates the WPP’s operation within its steady-state reactive power capability and meets the power factor limits. Under faulty conditions, the controller forces the WPP to its maximum capability to contribute more reactive power support to the grid. Two mathematical models representing the steady-state and maximum reactive power capability of the WPP are developed through regression and analytic approaches, respectively.
In the second part of the thesis, a model predictive control (MPC)-based distributed generation (DG) controller is proposed to regulate the voltage and frequency at the point of common coupling (PCC) in an islanded microgrid. A data-driven input-output Box-Jenkins polynomial predictive model for DG control is developed using the Gauss-Newton-based nonlinear least square method with the prediction optimization focus. The model inputs are direct- and quadrature-axis components of the control signal, and the model outputs are deviations of the voltage and frequency from their nominal values at the PCC. The proposed MPC controller operates using the
PCC data and does not require the microgrid’s central controllers or DG-to-DG communication networks. It can effectively compensate voltage and frequency deviations at the PCC and ensure proportional reactive power sharing among DGs without a secondary controller and a virtual impedance loop. The integrated Kalman filter in the MPC structure enables a robust controller design when subjected to impedance variations and measurement noises.


identifier: Omidali, Mahdi <https://research.library.mun.ca/view/creator_az/Omidali=3AMahdi=3A=3A.html>   (2021) Structural performance of non-ice class ships in sliding collision with ice.  Masters thesis, Memorial University of Newfoundland.

abstract:
Stiffened structures have a high load-bearing capacity beyond the elastic region that can be used in structural design. Collision and grounding scenarios are among the accidental limit states that threaten the structural integrity of marine structures. Collision with ice is one of the scenarios that can occur in Canadian Arctic waters. It is a high priority to understand the structural performance of ships in probable collision cases. As for ice-class ships, the load-carrying capacity is apparent on some level for designers and navigators. For non-ice class ships, however, the reserve strength after yield is not evident in collision with ice. It is crucial for both structural reasons and damage stability of the vessel.
International Maritime Organization (IMO) defines damage length requirements for various types of ships in various conventions and codes. It is necessary to study the damage extent in collision scenarios to realize whether amendments are necessary for vessels that might navigate in polar water. In this research, the structural performance of various merchant ships and offshore support vessels has been investigated under collision with ice. Finite element simulation with complex fracture models was implemented in this study.
The simulations indicated that the collision with bergy bits causes severe damage to the structure on non-ice class ships. Parameters such as ice shape in the high-pressure zone, ice geometry (mass distribution), and impact angle dramatically affect the results.
It was concluded that for the merchant vessels investigated, the damage stability requirements specified in MARPOL are conservative (except for tankers whose length does
not exceed 150m), and there is no need to include any additional damage case scenario. For offshore supply vessels, results indicate that the damage cases are not as conservative as they should be, and amendments to the current IMO regulations are necessary. In addition, it is shown that the empirical formulas available in the literature can estimate the steady-state fracture phase in the sliding collision. This finding could be used to construct the probability distribution function for damage extent in collision with ice.


identifier: Miah, Md. Ruyel <https://research.library.mun.ca/view/creator_az/Miah=3AMd=2E_Ruyel=3A=3A.html>   (2021) Access to markets for small-scale fisheries: challenges and opportunities during and after the COVID-19 pandemic.  Masters thesis, Memorial University of Newfoundland.

abstract:
This study views markets as social institutions and examines whether they enable or hinder access for small-scale fisheries, especially in the context of the COVID-19 pandemic at a global and a national scale (Bangladesh), with a local case study in the Bangladesh Sundarbans. On a global scale, the study reveals that the COVID-19 pandemic has disrupted the supply chains of fish and fisheries products worldwide, with serious consequences for small-scale fishers’ livelihoods and socio-economic conditions. However, the pandemic has also brought new opportunities for small-scale fisheries, including product and income diversification, alternative market arrangements, and flexibility in direct sales. At a country level in Bangladesh, similar effects are found in the production, distribution and supply, processing, markets, and food and nutritional security for small-scale fisheries. Finally, a case study was conducted in the Bangladesh Sundarbans to investigate the market structure and the governance of access to markets for the small-scale mud crab (Scylla serrata) fishery. The findings show that local traders or depo owners are the main actors governing both the domestic and the export mud crab supply chains, while small-scale fishers are invisible due to weak market arrangements and the absence of government policy to support them. The study recommends modifying the market governance structure based on the social dynamics of the stakeholders, institutional capacity, and interactions between the key actors to enhance the small-scale fisheries’ access to markets. Overall, the COVID-19 pandemic has created an opportunity for countries around the world, especially for developing countries like Bangladesh, to
build back the market structure better and stronger, also by addressing the pre-pandemic distortions made by the powerful players in the supply chains. Governing bodies and the stakeholders of the fisheries supply chains around the world could also learn from the present situation and use it as a basis for building viable and resilient small-scale fisheries when facing future crises.


identifier: Greene, Aaron <https://research.library.mun.ca/view/creator_az/Greene=3AAaron=3A=3A.html>   (2021) Reliability-based development of torsional strength equations for the CSA S16 Standard.  Masters thesis, Memorial University of Newfoundland.

abstract:
Steel structures are designed to specific governing design codes which have incorporated reliability parameters that predetermine the required target reliability and margin of safety depending on which country the structure is engineered.
The approved steel design codes ensure each structure is designed with the same quality, recommended loading conditions and safety standards for the design life of the structure. In Canada steel structures are governed by the Canadian Standards Association (CSA) and designed to CAN/CSA S16-19 – Design of Steel Structures [1].
The current Canadian steel design standard (CSA S16-19) gives no specific guidance on methodology with respect to torsional design. This thesis proposes a reliability-based method that, subject to further research and approval by experts in the field, could allow the adoption of strength formulas from other sources for use alongside the CSA S16 Standard while maintaining the desired target reliability.
A series of reliability analyses are performed first to verify the target reliabilities of both the CSA S16 Standard and the AISC 360 specification. Then, an iterative reliability-based approach is used to calibrate the proposed strength formulas in accordance with the desired target reliability of the CSA S16 standard.
Updated resistance factors are then recommended for use with the AISC 360 torsional strength formula for round and rectangular HSS sections so that they can be adopted for use by the CSA S16 standard while maintain the appropriate target reliability index.


identifier: Adofo, Naana Frimpomaa <https://research.library.mun.ca/view/creator_az/Adofo=3ANaana_Frimpomaa=3A=3A.html>   (2021) An assessment of gendered mediation in daily graphic newspapers: the case of the 2020 general elections in Ghana.  Masters thesis, Memorial University of Newfoundland.

abstract:
This thesis explores female political underrepresentation in Ghana via a gendered assessment of political news reporting. Firstly, the study (1) gives an overview of female political representation globally and locally; secondly, (2) it describes the role of the media in female political representation globally and locally, and thirdly, (3) it analyzes data obtained from news articles to assess how the portrayal and political coverage of men and women in politics by the Daily Graphic newspaper in Ghana.
The data reveals that women in politics in Ghana are generally underrepresented. The news articles analyzed also reveal that women in politics are generally positively covered by the Daily Graphic in terms of story tone and picture enhancement, and equally in terms of shared volume of their representation. However, elements of gendered mediation were identified. From the data, women in politics are disadvantaged in quality of coverage, that is, story size and story content. This thesis gives an in-depth assessment of the various elements of gendered coverage by the Daily Graphic.
This study contributes to the broader field of literature on female political representation and gendered mediation.


identifier: Yang, Pei <https://research.library.mun.ca/view/creator_az/Yang=3APei=3A=3A.html>   (2021) Investigating the tectonic evolution of the NE Newfoundland-Porcupine Atlantic conjugate margins using new seismic reflection data and deformable plate modelling.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
In recent years, there has been an improved understanding of the multi-episodic extensional processes that were active along the NE Newfoundland-Porcupine Atlantic conjugate margins during the Mesozoic. However, there are still unresolved key issues about this rift system, including unclear structural styles and crustal architecture due to lacking seismic data constraints, uncertainties about the effects of structural inheritance and rift segmentation on margin development, skepticism about the role of extension obliquity, and increased scrutiny about the conjugate relationship between the Flemish Cap and Goban Spur.
In this thesis, an integrated geophysical study, based on newly acquired seismic reflection data, seismic refraction data, borehole data, and potential field data along the rift system, is undertaken to define the crustal architecture. The faults, sedimentary layers, and basement features display distinct 3D characteristics and the crustal architecture is highly variable along the margin. Along-strike variability is associated with changes in extension rates, rift obliquity, and the effect of reactivation of inherited Caledonian and Variscan basement fabrics, indicative of segmentation of the rift system.
In conjunction with constraints from newly acquired seismic data, this study improves upon published deformable plate models in GPlates by introducing segmentation of the Porcupine Bank and transfer faults on the continental crust of the Goban Spur, generating a better fit compared with previous plate reconstruction models. The updated deformable plate model allows us to visualize the crustal thickness evolution through time and further quantify the amount, orientation, and timing of extension events between the NE Newfoundland, Iberia, and
Irish Atlantic margins. This model shows that the NE Newfoundland-Porcupine Atlantic margin pair is highly segmented and obliquely hyperextended. The model also demonstrates the significant role played by continental ribbons/microplates in controlling crustal thickness within the deformable region. The thesis results reshape our understanding of the complex kinematic evolution of the NE Newfoundland-Porcupine Atlantic rift system and of rift compartmentalization across the southern North Atlantic. The conjugate relationships between the Goban Spur, Porcupine Bank, and Flemish Cap are also renewed, which is beneficial to derisk petroleum exploration in the underexplored conjugate margin basins. Finally, these results can potentially offer insights into the evolution of other rifted margins (e.g., the Red Sea) on the Earth.


identifier: Silva Jimenez, René Alberto <https://research.library.mun.ca/view/creator_az/Silva_Jimenez=3ARen=E9_Alberto=3A=3A.html>   (2021) Iron nickel separation at high concentration solutions using ion exchange.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
Separation of iron from nickel and other base metals is an indispensable step of leach liquor purification in hydrometallurgy. Currently, the removal of Fe³⁺ is carried out by precipitation increasing pH of leach liquor to the limits of iron solubility. Depending on the process conditions Fe³⁺ precipitates into jarosite, hematite, goethite, or magnetite. Mechanical filtration processes separate the Fe-precipitates from nickel leach solutions. The disposal of precipitate requires strict measures of waste management to reduce the potential of pollution. Iron removal through precipitation is a resource intensive process. Therefore, the pursuit of alternative processes for iron removal signify an opportunity for overall process improvements.
Ion exchange is a potential alternative for Fe removal. Hydrometallurgy currently uses ion exchange resin at industrial scale for removal and purification of non-ferrous metals. However, the industry remains reluctant in applying ion exchange for iron removal. Partly due to relatively simplicity of Fe precipitation processes and the lack of environmental regulation related to waste disposal. Previous research on Fe removal by ion exchange focuses on systems at low concentrations (>0.1 M) and research related to Fe removal from electrolytes at high metal concentration is scarce. At large, most of the work is unavailable. It is protected by intellectual properties and company secrecy. Although selectivity of resins is stablished at low concentration systems, theory suggest that
selectivity trends and adsorption potential change as metal concentration increases. Therefore, there is a need for investigation to confirm resins technical feasibility at electrolytes of high metal concentration.
In this work, the adsorption capabilities and selectivity for Fe³⁺ over Ni²⁺ were evaluated using 30 commercial ion exchange resins of cross-linked polystyrene with divinylbenzene body with 16 different functional groups. The selected resins were classified into strong cationic exchangers (i.e., sulfonic resins), weak cationic exchangers (i.e., carboxylic resins), chelating resins (i.e., N-methyl-glucamine, amidoxime, iminodiacetic, bis-picolylamine, phosphinic, phosphoric, thiol, thiourea and isothiouronium, aminophosphonic, and combination of sulfonic and phosphonic resins), and mixed bed resin (i.e., combination of sulfonic and quaternary ammonium groups). Additionally, resin containing strong anion exchange characteristics (i.e., quaternary ammonium resins) acted as control experiments while non-functionalized resin acted as blank experiments. The potential for Fe³⁺ adsorption and selectivity was evaluated in bimetallic (Fe:Ni) and polymetallic (Fe:Ni:Co:Cu) systems. The bimetallic systems contained equimolar concentration of Fe³⁺ and Ni²⁺ satisfying rough averages of common concentration found in Ni-bearing sulfide and laterite ore leach liquors. The polymetallic systems contained excess of Ni²⁺ to represent leach liquors obtained from Ni-bearing sulfide ores.
Among the resins tested, resins containing aminophosphonic acid groups (up to 94% removal), a combination of phosphonic and sulfonic (93%), iminodiacetic acid (92%), methylglucamine (91%), carboxylic acid (78%), quaternary ammonium (62%), amidoxime
(67%), phosphoric acid (92%), and phosphinic acid (84%) were the best performing resins obtaining satisfactory results for the selective adsorption of Fe³⁺ from bimetallic and polymetallic systems. The best performing resins underwent systematic studies of single factor optimization to elucidate the parameters that most affect the efficiency of Fe³⁺ separations. Metal concentrations above 20 g/L and solution pH between 1.0 and 2.3 were dominant solution factors affecting the adsorption trends. Adsorption selectivity changed in time. Adsorption of Fe³⁺ increased with time up to a maximum of 120 min. Thereafter, the adsorption of Fe³⁺ was negligible. In periods under 10 min, resins obtained significant co-adsorption of base metals. After that, the co-adsorption of base metal decreased suggesting a base metal displacement by Fe³⁺. Conversely, temperature had little effect on the metal adsorption trends suggesting that ion exchange do perform appropriately at temperatures ranging from 20°C to 90°C.
Not all best performing resins sustained Fe³⁺ adsorption selectivity after modification of process variables. Among the best performers, the resins sustaining Fe³⁺ adsorption selectivity were resins with a combination of phosphonic and sulfonic groups, resins with aminophosphonic acid, with carboxylic acid, iminodiacetic acid, phosphoric acid, quaternary ammonium, and methylglucamine. These best performing resins underwent a series of elution studies in H₂SO₄ and HCl solutions of 0.2, 0.5, 1, 5, and 10% v/v. Resins with a combination of phosphonic and sulfonic group showed the best elution performance amidst the resins analyzed and underwent a systematic analysis to determine the best conditions to enhance metal elution. A combination of primary and secondary
elution using solutions of H₂SO₄ 5% v/v and EDTA 5% w/w resulted in almost 100% elution of Fe³⁺ and Ni²⁺.
The thermodynamic characteristics of the metal adsorption on ion exchange resins with a combination of phosphonic and sulfonic groups confirmed preference for Fe³⁺ over Ni²⁺. The calculation of heat of adsorption, entropy, and the degree of spontaneity of the adsorption reaction was difficult due to the high metal concentration in electrolyte. However, the results showed that the adsorption of Fe³⁺ in ion exchange resins was favourable with exothermic and exergonic characteristics and positive changes in entropy. Conversely, Ni²⁺ adsorption was not favourable having negative changes in entropy while the change in Gibbs energy was positive. These observations confirmed the low adsorption percentages of Ni²⁺ compared to that of Fe³⁺. None of the kinetic models employed described satisfactory the adsorption rate of Fe³⁺ as they failed to achieve correlations above 90%. This suggest that the adsorption rate of Fe³⁺ on resins with a combination of phosphonic and sulfonic groups may be governed by unknown transport phenomena not accounted on the kinetic models used.
Overall, the results obtained suggest ion exchange can potentially be an alternative to iron precipitation as an iron removal process in nickel purification. However, economic studies are still required to determine the cost benefit of ion exchange resins against precipitation.


identifier: Behbahani, Razyeh <https://research.library.mun.ca/view/creator_az/Behbahani=3ARazyeh=3A=3A.html>   (2021) Modeling magnetic nanoparticles: application to hyperthermia.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
Using the Landau-Lifshitz-Gilbert (LLG) equation in micromagnetic simulations, we
model magnetic nanoparticles composed of nanorods for application in magnetic
nanoparticle hyperthermia, a developing cancer treatment. We use a scaling approach
based on the renormalization group (RG) to calculate magnetization-field hysteresis
loops that are invariant with simulation cell size, with the objective of decreasing the
simulation time at clinically relevant field parameters. In addition, we introduce a
time scaling approach that involves the sweep rate of the oscillating external field and
the damping constant α in the LLG equation, which allows for up to three orders
of magnitude faster simulations. Equipped with the RG and time scaling tools, we
explore a macrospin model in which a complex nanoparticle is represented by a single
magnetization vector with appropriate effective magnetic parameters. To evaluate
this model, we calculate loops for single particles and particles interacting in pairs,
chains and triangles of three particles, and in a cluster of thirteen nanoparticles. Motivated
by recent experimental studies that reported successful hyperthermia treatment
in the absence of perceptible heating of tissue, we report on local hysteresis loops of
individual nanoparticles within clusters, highlighting the role of magnetostatic interactions
between nanoparticles in the complex heating and magnetization dynamics of
groups of nanoparticles.


identifier: Collins, Rebecca C. <https://research.library.mun.ca/view/creator_az/Collins=3ARebecca_C=2E=3A=3A.html>   (2021) Generalized anxiety disorder and psychological distress in a Canadian adult sample: exploring the role of social support.  Masters thesis, Memorial University of Newfoundland.

abstract:
In the literature, there have been limited studies examining the relationship between
social support and psychological distress in individuals with generalized anxiety disorder (GAD).
Utilizing a sample of 1956, 25 to 64 year-old respondents from the Canadian Community Health
Survey – Mental Health (CCHS-MH, 2012) who self-reported GAD diagnosed by a health care
provider, the present study examined levels of social support (as measured by the Social
Provisions Scale (SPS)), and psychological distress (as indicated by the Kessler Psychological
Distress Scale (K10)), and explored the degree to which SPS subtypes predicted psychological
distress in those with GAD overall, and men and women separately.
When compared with the general CCHS-MH sample, adults with GAD had significantly
higher levels of psychological distress, and lower SPS levels overall, as well as for each subtype
(i.e., guidance, reliable alliance, reassurance of worth, attachment, and social integration).
Interestingly, comparisons between men and women with GAD revealed that while there was no
difference in psychological distress, men scored significantly lower in overall SPS scores, as
well as for each subtype.
When SPS subtypes were regressed onto psychological distress, social integration and
income were both inversely associated for both men and women reporting GAD. Reassurance of
worth predicted lower distress and reliable alliance predicted higher for men, while guidance
predicted lower distress for women. Future directions and implications of the current findings are
discussed.


identifier: Zier-Vogel, Ryan <https://research.library.mun.ca/view/creator_az/Zier-Vogel=3ARyan=3A=3A.html>   (2021) TopAffy: predicting transcription factors DNA-binding specificities using a general topological method.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
Transcription factors (TFs) recognize and bind to specific DNA sequences. Knowing
the binding specificity of TFs is crucial to understand gene regulation and how
genetic differences in the DNA sequence of TF binding sites affect TF DNA binding
activity. However, the transcription factor binding preferences of only 1% of all
eukaryotic TFs are known. Computational prediction of TF binding preferences is
an affordable and efficient way to increase the number of known binding preferences.
Most bioinformatic tools for predicting the binding preferences of TFs require as input
the binding preferences of related TFs. However, there are TF families for which
very little experimental data is available. In this work, we present TopAffy, a new
approach for predicting TF 8-mer binding profiles. TopAffy constructs a stochastic
topological representation of DNA-binding domain sequences and learns a numerical
representation of the binding preferences of neighbouring amino acid pairs. TopAffy's
main contribution is to construct a family-independent model which can be used to
predict the 8-mer binding profile for TF families for which no experimental data is
yet available. TopAffy's predictive performance is comparable to the performance of
state-of-the-art family-specific approaches. Our results demonstrate that it is possible
to learn a general model of binding specificities suitable for predicting binding
preferences for a number of TF families.


identifier: Kuehn, Sarah <https://research.library.mun.ca/view/creator_az/Kuehn=3ASarah=3A=3A.html>   (2021) Dual-bivalve proxy analysis of shellfish harvest intensity, and palaeotemperture in Powell River, British Columbia.  Masters thesis, Memorial University of Newfoundland.

abstract:
This thesis investigated the seasonality and intensity of shellfish harvesting and past sea surface temperature in Powell River, British Columbia, in the traditional territory of the Tla’amin First Nation. This is the first study to use two species of bivalve Saxidomus gigantea and Leukoma staminea as proxies for past cultural practices and environment. This is also the first study to use high-resolution stable oxygen isotope sclerochronological analysis for interpreting past subsistence and settlement patterns in the Powell River region.
Seven archaeological shell midden sites were examined to interpret shellfish harvest intensity using sclerochronological measurements of 644 shells from seven shell middens. The results showed that overall, there a consistent, and intense pattern of shellfish harvesting for both species. The only notable site-level difference is at the village site DlSd-11, where the S. gigantea shells examined showed a higher relative harvest intensity whereas the L. staminea shells showed a lower relative harvest intensity.
High-resolution stable oxygen isotope sclerochronological analysis was used to examine three live-collected L. staminea shells from the Sechelt Inlet in Sechelt, British Columbia. The results showed that the species L. staminea can be used to interpret the season of capture, although palaeotemperature calculations are affected by changes in salinity. The calculated temperature of the live-collected L. staminea shells had a range of 5.1-18.9℃ whereas the measured temperature was 5.7-20.4℃. Five S. gigantea and five L. staminea shells from the defensive lookout site DlSd-1 in Powell River, British Columbia were analyzed for seasonality. The results showed a difference between species for the interpreted season of collection. All five of the S. gigantea were collected during the spring. Two of the L. staminea shells indicated collection in the spring, one shell indicated either spring or summer collection, one shell indicated summer collection, and the last shell indicated an autumn or winter collection. The combination of ẟ18Oshell data, with other lines of archaeological evidence, and ethnohistorical records indicate that the site was inhabited during the spring and likely used throughout the year by the ancestral Tla’amin.
The dual proxy analysis showed that the use of two provides insight into the overall history of shellfish harvesting. In this case, the use of two species shifts the interpretation from a single season of site use to year-round by looking at both species of bivalves. Further, the growth increment analysis affirmed a consistent pattern of intensive shellfish harvest in this region.


identifier: Holloway, Spencer J. <https://research.library.mun.ca/view/creator_az/Holloway=3ASpencer_J=2E=3A=3A.html>   (2021) Analysis of an ice cone impact with a hull structure through the use of large pendulum impacts and finite element analyses.  Masters thesis, Memorial University of Newfoundland.

abstract: When considering hull structure impacts with large ice pieces, there is still much left to understand. As well, there is a lack of information available when considering the development of finite element models of these impact types. This thesis analyzes a grillage from the ex-HMCS IROQUOIS Royal Canadian Navy destroyer, which had a service life of nearly 45 years. Through a large double-pendulum apparatus, the grillage was impacted by an ice cone indenter. The study then continues by replicating the grillage as accurately as possible through the use of newly procured steel. This copy grillage was then also impacted by a large ice cone indenter. Both experiments were then replicated through finite element analysis. The study focuses on the capabilities of hull structures through comparing aged and new steel, as well as comparing the experimental data to respective finite element analyses. The capabilities of the original and copy grillages were shown and the overall study was developed as a benchmarking tool when considering the development of finite element models with respect to real-world ice impact experiments.


identifier: Walker, Sarah-Kay <https://research.library.mun.ca/view/creator_az/Walker=3ASarah-Kay=3A=3A.html>   (2021) Personal and university online social support helping students during the COVID-19 pandemic: a moderation analysis.  Masters thesis, Memorial University of Newfoundland.

abstract: Social supports can provide physical and/or emotional support, in which the student receiving the support will benefit from it. Using the stressor-strain model and the Negativity Buffer Theory I answer: does perceived online social support (university offered and personal use) moderate the relationship between financial and illness threat (stressors) and well-being and anxiety (strains) specifically in the context of the COVID-19 pandemic? Using survey methodology, 167 participants were asked about perceived social support, stressors, anxiety, and well-being. Results indicate personal and university online social support moderated the relationship between perceived financial threat and well-being, however not in the way hypothesized. These results were replicated with anxiety. Results also showed that online social support (personal and university-provided) did not moderate the relationships between illness threat and both well-being and anxiety. I discuss potential recommendations to universities regarding what resources students are finding useful and where additional efforts could be beneficial.


identifier: Odeh, Francis Onuoha <https://research.library.mun.ca/view/creator_az/Odeh=3AFrancis_Onuoha=3A=3A.html>   (2022) Machine learning method for leak detection in water mains using acoustic data.  Masters thesis, Memorial University of Newfoundland.

abstract:
The global demand for potable water rises each year as a result of the continuous increase in the global population. Hence, there is a need to expand water distribution networks and maintain existing ones continually. However, the current state of the existing water distribution is a significant source of concern for many municipal water agencies since they are more prone to leakages attributable to age, corrosion, external loads, excessive water pressure, etc. These leakages, when they occur, usually go unnoticed for a while due to poor labor-intensive reactive leak detection techniques employed by many municipal water agencies. The delayed detection of any leakages often results in economic losses to water agencies, collateral damage to nearby infrastructures, and health issues due to the percolation of harmful substances through the broken water pipes.
To this end, researchers have developed several leak detection methods such as infrared radiometric pipeline testing, fiber-optic detectors, acoustic emission detectors, and monitoring for fluid pressure, flow, and temperature. However, each technique has its limitations. The acoustic emission method stands out due to its higher sensitivity, leak detection accuracy, more extended detection range, and ease of use. Nonetheless, the results obtained when using the acoustic emission method in the field are still subject to human interpretation and, as such, pose challenges concerning the final decision to excavate for the leakages or not, especially at instances when the detection metrics are close to the leak thresholds. In such instances, the delay in decision-making or misinterpretation of the results due to human error could negatively impact early detection, remediation, and the volume of water loss.
Consequently, as a case study, this research applied the machine learning technique to the real-life acoustic data obtained from the field investigations carried out by the city of Mount Pearl municipality to develop models for detecting leakages within the water distribution network. The developed models would analyze and interpret the results of the acoustic emission method, thereby tackling the challenges mentioned above. The Python programming language was employed for the data preprocessing and the development of binary classification models to identify leaky and non-leaky pipes within the network. Four classification models for leak detection prediction were built: the K Nearest Neighbor (KNN), Random Forest (RF), Artificial Neutral Network (ANN), and the Support Vector Machine (SVM).
The performance evaluation showed that the RF model is the best model for leakage detection using acoustic data. The RF model has the lowest error rate, highest accuracy, precision, F1-score, specificity, recall, and Area Under the Receiver Operating Characteristic Curve (AUC-ROC).


identifier: Jalali Nodoushan, Mohammadhadi <https://research.library.mun.ca/view/creator_az/Jalali_Nodoushan=3AMohammadhadi=3A=3A.html>   (2021) Development of a vibration-based non-destructive testing method for in-service utility poles.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
Wooden utility poles for electric networks are widely used, with approximately two million poles in North America. A reliable and cost-effective non-destructive testing (NDT) method is necessary for strength evaluation during the life span of the poles. To improve an emerging modal testing-based NDT method, this thesis develops a novel method to measure natural frequencies and damping ratios of poles even though they are connected to conductors. This thesis makes contributions to the wood pole NDT state of the art in two major areas – analytical and numerical modeling of pole-cable systems, and frequency-domain decoupling methods to identify pole properties despite their connection to cables.
Improved analytical models of the “cable-beam” system were developed in order to understand the coupled vibration behavior of the system. Bending stiffness and sag of the cable were considered in the modeling and the effects of them on vibration behavior of the system was studied. Two-dimensional and three-dimensional dynamic models using bond graph method were developed for vibration of stranded cables and vibration of the cable-beam system. The models were verified by experiments in free and forced vibration.
The second contribution area is the development of substructure decoupling-related methods to decouple the beam frequency response function (FRF) from the assembled cable-beam system. The FRF of the beam was obtained as an independent substructure after decoupling analysis and the FRF was compared to the directly measured FRF from modal testing of the beam substructure. A good agreement showed that the substructure decoupling method can be used to filter out the effects of cables from the assembled system in cabled structures, assuming that all points in the system are accessible for measurement.
An FRF-based finite element model updating was then developed to overcome the practical limitation of accessing some measurement points in the field. The FRFs of accessible points were used as a basis for updating the FE model and then the FRFs of inaccessible points were obtained from the updated (optimized) FE model.
A substructural damage detection was also developed for the systems that consist of a few substructures but only the main (target) substructure is susceptible to damage. In the developed method, FRF of the main substructure is first obtained using the substructure decoupling method and then FRF-based finite element model updating is used for damage detection, localization and quantification. The method was successfully able to identify location and magnitude of damage, which was modeled as a localized reduced stiffness due to material degradation or cracking.
Finally, in support of the larger ongoing NDT research project, full-scale pole modal testing was done in the field. In-ground pole FRF’s with and without cables were generated, for future use in model validation. In-ground poles without cables were subjected to modal testing, and then brought to the lab for modal and destructive testing. The differences in the resulting FRF’s allow future simulation-based prediction of the foundation properties, and the destructive tests have added to the research group’s database for correlation of modal properties and pole strength.


identifier: Doyle, Emily <https://research.library.mun.ca/view/creator_az/Doyle=3AEmily=3A=3A.html>   (2021) Understanding school food in Newfoundland and Labrador through a systems framework.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
Using systems thinking, I address the question of how to improve school food in the
province of Newfoundland and Labrador (NL). Chapter Two provides an interdisciplinary
review of school food literature. This review establishes the rationale for adopting systems
thinking as a conceptual and analytic tool. The systems methodology used in this dissertation is
described in Chapter Three. In Chapter Four I review what is known about school food in the NL
context and describe the gap to be filled by using multi-method research to answer the following
questions: What school food programs and policies exist in NL? What knowledge and attitudes
exist about the current school food system? How do knowledge and programs interact to
facilitate or inhibit development of a more healthy and sustainable school food system? Next,
three research-based chapters contribute to new understanding. Chapter Five is a case study
about a school greenhouse. The case study took place earlier in my PhD program and helped lead
to the adoption of the systems methodology applied throughout this dissertation. Chapter Six is
based on a survey of 68 principals. The results of the survey highlight the persistence of
variability as a key defining feature of school food in the province and the need for more
responsive and collaborative tools to assess and enhance school food systems across the
province. Chapter Seven discusses findings from 34 key informant interviews of stakeholders
throughout the system of school food in NL. An analysis of these interviews shows how school
food system innovators drive systems change by responding to system weaknesses as a source
for strategic collaboration and learning. Taken together, the findings provide a deeper
understanding of how persistent and substantial barriers make interventions ineffective. Future
areas for learning and collaboration are identified. I suggest that collaborative and critical
knowledge about the NL school food system is essential for future transformation.


identifier: Liao, Yifu <https://research.library.mun.ca/view/creator_az/Liao=3AYifu=3A=3A.html>   (2021) Parental consent for newborn screening: a discrete choice experiment.  Masters thesis, Memorial University of Newfoundland.

abstract:
Background: Parental consent is very commonly assumed for newborn bloodspot screening (NBS)
in most Canadian provincial screening programs. This falls short of usual norms, and evidence
suggests that some parents would prefer an explicit process. This study was designed to inform
improvements in NBS consent processes.
Objectives: (1) To examine parents’ past experiences with, and attitudes towards, NBS consent
processes in Canada. (2) To quantify parents’ preferences towards specific attributes of the NBS
consent process, and identify characteristics of subgroups with different preference patterns.
Method: A cross-sectional survey that included a discrete choice experiment (DCE) was
conducted to capture information on participants’ past experiences with and preferences for NBS
consent processes. DCE data were analyzed using conditional logit and latent class (LC) regression
models.
Results: The sample comprised 715 participants. As an overall group, respondents preferred to
have NBS information provided late in pregnancy, for consent not to be assumed by providers, and
for the consent decision to always be recorded. Three classes of participants with different
underlying preference patterns were identified in the sample.
Conclusion: If NBS programs wish to better meet parents’ preferenes, the results indicate specific
aspects of the consent process that could be targeted for further examination..


identifier: Lahey, Shae-Lynn <https://research.library.mun.ca/view/creator_az/Lahey=3AShae-Lynn=3A=3A.html>   (2021) Simulating protein-ligand binding with neural network potentials.  Masters thesis, Memorial University of Newfoundland.

abstract:
Computational methods have been developed to predict the structures and energetics
of protein-ligands complexes. However these methods are limited by the accuracy
and transferability of the molecular mechanical (MM) models used to calculate the
potential energy. Neural network potentials (NNPs) eliminate the need for parameterization
and avoid many of the limiting assumptions of MM models. We evaluated
the accuracy of ANI-type NNP models for predicting the potential energy surface of
biaryl torsions. The ANI-2X and ANI-1ccX NNPs were found to be more accurate
and reliable than popular molecular mechanical models. We then developed a new
method where the NNP is used to describe the intramolecular terms of a ligand while
a conventional MM model is used to describe the environment. This method was
found to be effective for predicting the binding pose of ligands bound to proteins and
could be used to calculate the conformational component of the binding energy. We
also show that these methods can be used to re�ne low-resolution cryo-EM structures
of protein-ligand complexes.


identifier: Abbott, Stephanie M. <https://research.library.mun.ca/view/creator_az/Abbott=3AStephanie_M=2E=3A=3A.html>   (2021) A geophysical study of the Valentine Gold Project, West-Central Newfoundland.  Masters thesis, Memorial University of Newfoundland.

abstract: The Valentine Lake Property is located in the west-central region of the island of Newfoundland and comprises five significant structurally controlled, orogenic gold deposits. These deposits, which have proven challenging targets for geophysics, occur proximal to a major thrust faulted contact between the Precambrian Valentine Lake Intrusive Complex (VLIC), which houses the majority of gold mineralization, and the Silurian Rogerson Lake Conglomerate (RLC). Hosted within the silicic quartz-eye porphyry and trondhjemite phases of the VLIC, the gold concentrations are associated with extensional and shear parallel quartz-tourmaline-pyrite (QTP) veining. While geophysical techniques, such as induced polarization (IP), magnetics and seismic, are commonly used to detect mineral prospects, their ability to delineate the ore zone at the Valentine Gold Project (VGP) has been largely unsuccessful, primarily because the gold is scattered throughout veins within the resistive, silicic host rocks. Consequently, to date the most successful methods for locating the ore have been prospecting, soil sampling and drilling. This study employs two fresh geophysical techniques, gravity and ground-penetrating radar (GPR), supplemented by sonar surveys, in an effort to map the subsurface extent of the gold-bearing alteration zone and assess the depth of overburden and water reserves for future mine development. Throughout 2019 and 2020, a 22 line-kilometre broad-scale gravity survey, comprising 252 stations was completed, targeting the slightly less dense altered host rock. GPR data acquired over 8 priority bogs and small ponds helped define the irregular overburden to aid in gravity corrections. Combined GPR and sonar bathymetry surveys of Valentine and Victoria Lakes covering 10 and 32 square kilometres, respectively, were completed to further assist with the gravity corrections and to ascertain water resources for mining. The resulting residual Bouguer gravity map revealed a -1.7 mGal thin linear anomaly corresponding partially to the alteration zone and the bog hypsometry maps yielded overburden thicknesses up to 4.8 metres.


identifier: Virk, Seerat <https://research.library.mun.ca/view/creator_az/Virk=3ASeerat=3A=3A.html>   (2021) Organocatalytic asymmetric Michael, Mannich and aza-Michael reactions in the synthesis of selected quinolizidines, indolizidines and piperidines.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
Quinolizidines, indolizidines and substituted piperidines are ubiquitous structural motifs present in several naturally occurring alkaloids, pharmaceuticals and other compounds which exhibit a broad range of biological activities. Though many methods have been reported for their construction, there is still a need for novel approaches, especially in terms of high efficiency, good modularity and excellent stereoselectivity. A general introduction to the research work described in this thesis has been provided in Chapter 1. An enantioselective, biomimetic organocatalytic synthesis of 4-arylquinolizidin-2-ones, key intermediates in the synthesis of several Lythraceae alkaloids, was developed. The methodology features S-proline-mediated Mannich/aza-Michael reactions of readily available arylideneacetones and Δ¹-piperideine. The total syntheses of (−)-lasubine II and (+)-subcosine II as well as the formal syntheses of structurally related Lythraceae alkaloids were achieved. The use of Δ¹-pyrroline in the Mannich/aza-Michael reaction provides enantiomerically enriched 5-arylindolizidin-7-ones, which are precursors to nonopiate antinociceptive agents. Details of these studies are described in Chapter 2.
An organocatalytic, enantioselective Mannich reaction of α,β unsaturated β´-ketoesters with N-carbamoyl imines was developed. The Mannich reaction uses an aminothiourea catalyst (S,S-Takemoto catalyst), and this was followed by a Pd(0) mediated deallylative decarboxylation, to provide enantiomerically enriched β-amino ketones. The conversion of these β-amino ketones to 2,6-diaryl substituted piperidinones was achieved. These results are described in Chapter 3.
The diarylindolizidine alkaloids (-)-fistulopsine A and (+)-fistulopsine B, isolated from the bark and the leaves of Ficus fistulosa, have potent in vitro antiproliferative activity against breast
(MCF7) and colon (HCT 116) carcinoma cell lines. Several 2-Indolinone-based analogues of (+)-fistulopsine B, with structural variation in the diaryl substitution, were prepared and examined for their biological activity. The synthesis of the analogues, by employing an organocatalytic Michael addition as a key step, and the biological activity studies are described in Chapter 4.


identifier: Chen, Xinwei <https://research.library.mun.ca/view/creator_az/Chen=3AXinwei=3A=3A.html>   (2021) Sea surface wind and wave parameter estimation from X-band marine radar images with rain detection and mitigation.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
In this research, the application of X-band marine radar backscatter images for sea surface
wind and wave parameter estimation with rain detection and mitigation is investigated.
In the presence of rain, the rain echoes in the radar image blur the wave signatures
and negatively affect estimation accuracy. Hence, in order to improve estimation accuracy,
it is meaningful to detect the presence of those rain echoes and mitigate their influence on
estimation results. Since rain alters radar backscatter intensity distribution, features are extracted
from the normalized histogram of each radar image. Then, a support vector machine
(SVM)-based rain detection model is proposed to classify radar images obtained between
rainless and rainy conditions. The classification accuracy shows significant improvement
compared to the existing threshold-based method. By further observing images obtained
under rainy conditions, it is found that many of them are only partially contaminated by rain
echoes. Therefore, in order to segment between rain-contaminated regions and those that
are less or unaffected by rain, two types of methods are developed based on unsupervised
learning techniques and convolutional neural network (CNN), respectively. Specifically, for
the unsupervised learning-based method, texture features are first extracted from each pixel
and then trained using a self organizing map (SOM)-based clustering model, which is able
to conduct pixel-based identification of rain-contaminated regions. As for the CNN-based
method, a SegNet-based semantic segmentation CNN is �rst designed and then trained using
images with manually annotated labels. Both shipborne and shore-based marine radar
data are used to train and validate the proposed methods and high classification accuracies
of around 90% are obtained.
Due to the similarities between how haze affects terrestrial images and how rain affects
marine radar images, a type of CNN for image dehazing purposes, i.e., DehazeNet, is
applied to rain-contaminated regions in radar images for correcting the in
uence of rain,
which reduces the estimation error of wind direction significantly. Besides, after extracting
histogram and texture features from rain-corrected radar images, a support vector regression
(SVR)-based model, which achieves high estimation accuracy, is trained for wind speed
estimation. Finally, a convolutional gated recurrent unit (CGRU) network is designed and
trained for significant wave height (SWH) estimation. As an end-to-end system, the proposed
network is able to generate estimation results directly from radar image sequences
by extracting multi-scale spatial and temporal features in radar image sequences automatically.
Compared to the classic signal-to-noise (SNR)-based method, the CGRU-based model
shows significant improvement in both estimation accuracy (under both rainless and rainy
conditions) and computational efficiency.


identifier: Zamanlou, Mohammad <https://research.library.mun.ca/view/creator_az/Zamanlou=3AMohammad=3A=3A.html>   (2021) Design and analysis of solar water pumping for drip irrigation in Iran.  Masters thesis, Memorial University of Newfoundland.

abstract:
In this thesis, a solar water pumping system is designed and studied for drip irrigation of a 14.7 hectare grape garden in Iran. Firstly, two kinds of solar-powered water pump systems were designed and studied. The difference between the systems is the storage type. One system uses a battery bank, and the other is with a water tank storage. The first system is designed using Lorentz compass3 software and includes a 6-inch 18.5 KW submersible pump. HOMER Pro software was used to model the second system and resulted in a 6-inch 11 KW submersible pump, and 44.4kw PV modules rated capacity and 144 KWh Battery Bank size. This research indicates using a storage system allows constant water flow for irrigation in solar water pumping and comparing the results, the research shows that using a battery bank is more economical than a water tank storage system.
Secondly, a cost-effective IoT-based SCADA system for a solar water pumping system was developed. The IoT-based SCADA is comprised of a raspberry pi zero W, Arduino nano, camera, SIM 5320A 3G module, voltage, current, and light sensors. We used Node-RED to design a graphical user interface and published it securely to the worldwide internet. This allows a user to connect to the server via an IP address and monitor and control the system. The implementation of the project resulted in an open-source server and cost around CAD$162.38.


identifier: Dang, Thi Tra My <https://research.library.mun.ca/view/creator_az/Dang=3AThi_Tra_My=3A=3A.html>   (2021) Larvae and juvenile lumpfish (Cyclopterus lumpus) Immune response to oral immunization against Vibrio anguillarum.  Masters thesis, Memorial University of Newfoundland.

abstract:
Vibrio anguillarum is a common marine pathogen that causes the disease vibriosis in several finfish species, including lumpfish (Cyclopterus lumpus). The lumpfish is utilized as a cleaner fish to control sea lice in the Atlantic salmon (Salmo salar) aquaculture industry in the North Atlantic region. Lumpfish have the ability to visualize and prey upon the ectoparasite sea lice (Lepeophtheirus salmonis) found on Atlantic salmon skin. Lumpfish immunity is critical for their optimal performance and sea lice removal as they are able to significantly reduce sea lice infestations up to 93–97% on Atlantic salmon in sea pens.
Oral vaccine delivery at a young age is the desired method for fish immunization. Oral vaccines are easy to use, reduce fish stress during immunization, and can be applied on a large scale while the fish are at a young age. However, the efficacy of orally delivered inactivated vaccines is controversial.
In this study, I evaluated the effectiveness of a bacterin preparation against V. anguillarum orally delivered to cultured lumpfish and contrasted it to an intraperitoneal (i.p.) boost delivery. I bio-encapsulated V. anguillarum bacterin in Artemia salina (live feed) and orally immunized lumpfish larvae. The innate and adaptive immune responses of lumpfish larvae were evaluated by using real-time quantitative polymerase chain reaction (qPCR) analyses. Although the oral V. anguillarum vaccine delivered in A. salina live feed reached the lumpfish gut, real-time quantitative polymerase chain reaction (qPCR) analyses of immune-relevant transcript expression levels revealed that it only modestly immune-stimulated the lumpfish larvae. Nine months later, lumpfish were either orally, or
orally and i.p boosted with the vaccine and two months later they were challenged with V. anguillarum (7.8x10⁵ CFU dose⁻¹). Oral immunization of lumpfish delayed mortality but did not confer protective immunity against the V. anguillarum challenge, which is in contrast to the i.p. vaccination which was protective.


identifier: Ahmed, Nadia <https://research.library.mun.ca/view/creator_az/Ahmed=3ANadia=3A=3A.html>   (2021) Pharmacotherapies for treatment of opioid use disorder: a narrative review and cost-effectiveness analysis.  Masters thesis, Memorial University of Newfoundland.

abstract:
Opioid use disorder (OUD) has become a global concern with the rapid increase in the use of illicit and prescription opioids. North America is in the midst of the opioid crisis, which requires effective (both clinically and economically) treatment interventions. Several evidence-based treatment options are available for the treatment of OUD. However, little is known about patients’ perspectives on the pharmacotherapies used for OUD treatment. Additionally, with the advent of novel and more expensive treatment options, an economic evaluation against conventional treatment is warranted.
The aim of this thesis is two-fold: first, to conduct a narrative review of patients’ perceptions and experiences with OUD pharmacotherapies and second, to compare the cost-effectiveness of the newer pharmacotherapies with conventional treatments. The thesis follows a manuscript style with the following chapters: Chapter 1 provides an introduction; Chapter 2 provides a narrative review of patients’ perceptions and experiences with the pharmacotherapies for OUD treatment; Chapter 3 is the cost-effectiveness analysis of the newer pharmacotherapies compared against the usual treatment; and, Chapter 4 concludes.
In the narrative review, we conducted a systematic search of relevant literature on patients’ perceptions and experiences with OUD pharmacotherapies. The data are coded to develop overarching themes. The findings are narratively described under these themes for the outcomes of perceptions and experiences. We critically appraised the included studies to assess their quality. We found evidence of both patient-reported positive and negative aspects of the treatments. Other key findings of this review study are lack of patient knowledge on the available treatment options, many patients seeking harm reduction treatment strategy with opioid agonist treatment (OAT), while others seeking abstinence-based treatment interventions, and the role of patient inclusive treatment decisions to optimize treatment outcomes.
In the cost-effectiveness study, we compared five treatment strategies using the US healthcare perspective: 1) methadone-lofexidine for detoxification and buprenorphine-naloxone for maintenance; 2) methadone-lofexidine for detoxification and extended-release naltrexone for maintenance; 3) buprenorphine-naloxone for detoxification and extended-release buprenorphine for maintenance; 4) buprenorphine-naloxone for detoxification and maintenance (i.e., usual treatment); and, 5) no treatment. Effectiveness outcomes are presented in quality-adjusted life-years (QALYs), treatment retention and opioid-free days. Detoxification with methadone-lofexidine and subsequent buprenorphine-naloxone maintenance yield greater effectiveness than usual treatment but are not cost-effective at the willingness-to-pay threshold of US$100,000 per QALY gained due to the high cost of lofexidine. Usual treatment with buprenorphine-naloxone is found to be cost-effective at the conventional willingness-to-pay threshold.


identifier: Strong, Vanessa Dawn <https://research.library.mun.ca/view/creator_az/Strong=3AVanessa_Dawn=3A=3A.html>   (2021) The effect of mindfulness-based stress reduction on biological markers of stress, immune function and cellular aging among breast cancer survivors with chronic neuropathic pain.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
Background: Chronic neuropathic pain (CNP) is a common sequalae among breast cancer
survivors. Nonpharmacological adjuvants are being increasingly recommended as first-line
adjunct treatments for the management of CNP conditions which is consistent with a
multidisciplinary biopsychological approach to optimize pain management. Mindfulness-based
stress reduction (MBSR) is one of the most commonly applied mindfulness interventions in the
treatment of CNP and has been shown to have preferential improvements in pain and overall
health-related quality of life. Although mindfulness interventions have shown promise in the
treatment of chronic illness and disease, it has yet to be studied in breast cancer survivors living
with CNP after medical optimization. Thus, the effect of MBSR on CNP in this highly
heterogenous and complex clinical population is unknown. Biological markers are objective
measures of biological systems that can be used to gain insight into the mechanisms through which
psychological interventions exert their effects. The aim of the first study was to use an
interdisciplinary treatment approach to CNP in breast cancer survivors by exploring the effects of
MBSR on pain, and biological markers of stress, immune function and cellular aging among breast
cancer survivors with CNP after guideline-based medical optimization. A second study was
conducted to explore the potential mediating role of mindfulness, and the individual facets, in this
change process. Methods: A double-blind randomized waitlist control trial was conducted using
a sample of 98 breast cancer survivors diagnosed with CNP. Women were randomized to receive
an 8-week MBSR intervention or waitlist control condition after undergoing medical optimization.
Biological samples and self-report measures of pain, physical function and emotional function
were collected at baseline, two-weeks post-intervention and at 3-month follow-up. Separate
analyses were performed using intention-to-treat and per-protocol principles. Results: MBSR was delivered with fidelity and women randomized to MBSR demonstrated a significant increase in
mindfulness relative to control. The MBSR intervention did not produce the anticipated stress
reducing effects typically associated with mindfulness-based interventions. No differential
changes in biomarker expression were observed between groups during the trial. Significant
improvements in pain severity (intention-to-treat analysis) and pain-related interference (perprotocol
analysis) were observed among women randomized to MBSR relative to control. Change
in pain-related interference, but not pain severity, was found to be partially mediated by
concomitant change in total mindfulness scores among women randomized to MBSR.
Conclusions: Mindfulness interventions have gained significant traction in the treatment of
chronic pain conditions. Despite this increase in popularity, our understanding of the association
between mindfulness and pain is still evolving. Null findings can be used to help inform our
understanding of adjuvant interventions in complex clinical patient populations, and identify what
works for who, when and why. Mindfulness-based interventions are not homogenous, nor are they
a panacea for disease and illness.


identifier: Carpenter, Wendy <https://research.library.mun.ca/view/creator_az/Carpenter=3AWendy=3A=3A.html>   (2021) Challenges older women face re-entering the workforce: expanding career opportunities.  Masters thesis, Memorial University of Newfoundland.

abstract: Older women face many employment barriers when looking to re-enter the labour market at a later stage in their life. These barriers can significantly challenge their economic and social independence. In some cases, they can be at risk for poverty and isolation. Their career trajectories move downward as they face decreasing salary scales, less mobility and lower status. In order to understand some of the impacts to this group, this research takes place in Ontario the largest provincial employer of full time workers in Canada. The research problem explored the employment barriers older women face and specifically focused on what could be done to assist these women as they transition in and out of the labour market. The research literature available does not pay sufficient attention to women of this age group and it is unclear as to how the individual, government, education sectors and the businesses could leverage career development initiatives to mitigate the risks for all stakeholders‟ but particularly the older women. It is, therefore, important to investigate what can be done to help older women in work transition. The purpose of this research was to determine challenges, if any, that older women (after the age of 50) face when re-entering the workforce and to explore what knowledge, skills and tools are needed to help them overcome barriers to employment. To investigate the problem, an interpretative qualitative study was undertaken using unstructured interviews with Career Coaches and Re-employment Consultants familiar with helping older women find work. It was important to obtain candid and open perspectives from career development professionals to inform practice. Unstructured interviews allowed for in-depth responses and examples to enrich the outcomes. The research questions include: Do older women face challenges when looking to re-enter the workforce? What skills and knowledge can support older women looking for work? What tools or training are challenging for older women to access or find? What tools or training can be enhanced or created to help older women look for or find work? These research questions are critical to uncovering specific challenges along with possible opportunities for support, such as coaching and/or job searching tools that can be enhanced or created to expand skills and knowledge related to older women finding work and being successful in their career trajectories. This thesis supports the findings in the research literature that older women face employment barriers and can benefit from career support and guidance. The outcomes draw our attention to the success of holistic and differentiated career support initiatives. Specific areas of focus for career planning practice should include confidence building, development of social capital and networking skills along with cost and time effective training on job finding skills and job skills training, if needed. These findings are relevant to women for their own research on career planning, as well as for coaching programs, employment hiring practices along with government policy and relevant legislation. These practice implications will help women navigate later life re-employment and guide them to achieve successful career trajectories.


identifier: Shoker, Yasmeen <https://research.library.mun.ca/view/creator_az/Shoker=3AYasmeen=3A=3A.html>   (2021) Finite element modeling of the elastoplastic behavior of multilayer metallic composites.  Masters thesis, Memorial University of Newfoundland.

abstract:
The aerospace industry has long favored lightweight materials to optimize fuel efficiency.
The use of lightweight materials poses stringent requirements on enhancing aircraft
structures in harsh environmental conditions. This in turn prompted many investigations
on using cladded and multilayer materials as a potential solution for corrosive
environments. Recent interest has been garnered in cladding for its adequate corrosion
resistance without significantly compromising cost and performance. To date, the
evaluation of these multilayer composite structures is normally established through
laboratory testing of small-scale specimens. However, understanding the structural
performance of cladded composites can be better accomplished using numerical
simulations via finite element analysis (FEA). Utilizing FEA simulation enables the
application of the derived knowledge of material properties and elastoplastic behavior to
larger-scale structures. This study employs FEA to predict the behavior of cladded
materials in the elastic-plastic region. In particular, ABAQUS commercial FEA software
is used to model these metals’ elastoplastic behavior. Increased precision is achieved by
calibrating and comparing the generated stress-strain data obtained from these simulations
with experimental measurements. A mesh convergence study is employed to determine
the adequate mesh size. Ultimately, the FEA models for individual metals are used to
predict the mechanical response of multilayer materials in the elastoplastic region.
Simulation results are in close agreement with their corresponding experimental
counterparts, further confirming the model's accuracy and effectiveness. The Ramberg-
Osgood (R-O) relationship is employed to reveal closely matching curves that are within close proximity of the experimental and modeled responses at several heat-treated
temperatures. Additionally, a parametric study that investigates different cladding
scenarios and how they can potentially yield enhanced tensile strength and ductility by
optimizing their required cladding thickness is completed. The viability of optimizing a
bilayer composite's elastoplastic behavior based on exploring varying combinations of
bilayer composites, materials, and thicknesses is also discussed. This research is
significant for two reasons: it yields a profound understanding of multilayer materials
mechanical performance, and it introduces a FEA simulation technique that enables
structural and design optimization of larger-scale structures to effectively fulfill design
requirements.


identifier: Burke, Chantelle M. <https://research.library.mun.ca/view/creator_az/Burke=3AChantelle_M=2E=3A=3A.html>   (2021) Sex-specific foraging behaviour by a low-arctic, diving seabird over the annual cycle.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
This thesis examines the seasonal foraging ecology of the Common Murre (Uria aalge), a circumpolar seabird with physiological adaptations for efficient pursuit-diving and a specialized reproductive strategy (male-biased parental care). The primary research objectives are to assess the behavioural strategies drawn upon by adult murres to survive a seasonally dynamic, Arctic-influenced marine environment, and to investigate how seasonal differences in parental care roles influence sex-specific foraging and survival strategies. To engage this question, I use bird-borne data loggers that collect behavioural observations relating to the distribution, diving and daily activity patterns of individual murres over eight months (July - February) in their annual cycle. Behavioural metrics are integrated with analyses of stable isotope ratios from a variety of tissues that provide corresponding information on seasonal trophic position and dietary niche breadth.
Murres exhibited flexibility in their foraging behaviour over the annual cycle. This was evident in a switch from increased foraging effort with a specialized, high trophic level diet during periods of peak energy demand (summer chick-rearing and late winter) to significantly reduced foraging effort and a generalized, low trophic level diet during the less demanding post-breeding period. Energy savings during moult-induced flightlessness and a flexible moult schedule facilitated by a resident, over-wintering strategy resulted in low energy demands during the post-breeding wing moult. I hypothesise that the post-breeding period represents a buffer event in the annual cycle of adult murres, and may be a key component of survival for a seabird with an otherwise costly pace of life.
Single-parenting males spent twice as much time foraging (self and offspring provisioning) relative to independent females (self provisioning only) and occupied relatively poor quality habitat over the estimated 63 days of paternal care at sea. Despite this, there was no evidence of an energy constraint as single-parenting males consumed the same low trophic-level diet as independent females and allocated equivalent time to self-feeding. Nonetheless, adult males could face time constraints to rear their offspring to independence and complete post-breeding wing moult before the onset of winter if energy limitations during poor-food years are resolved by the extension of either (or both) fitness-related activities.
During late winter, murres experienced a significant increase in estimated daily energy expenditures (DEE), driven in part by high thermoregulatory costs during prolonged exposure to cold water. Murres were able to overcome this energetic challenge by pushing the limits of their diving capabilities but regardless, late winter appears to be an extremely challenging time in their annual cycle.
Overall, this thesis demonstrates remarkable behavioural plasticity by murres over their annual cycle, characterized by highly plastic foraging tactics, dietary strategies and flexibility in the scheduling of wing moult, which may allow them to mediate some of the environmental disruptions predicted to occur with climate change. Yet, persistent declines in the biomass and condition of capelin Mallotus villosus, the keystone forage species in the NW Atlantic food web and the primary prey of breeding murres (and their offspring) could challenge this resiliency.


identifier: Alkasasbeh, Ahmad <https://research.library.mun.ca/view/creator_az/Alkasasbeh=3AAhmad=3A=3A.html>   (2021) Graceful labellings of new families of windmill and snake graphs.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
A function ƒ is a graceful labelling of a graph G = (V,E) with m edges if ƒ is an
injection ƒ : V (G) → {0, 1, 2, . . . ,m} such that each edge uv ∈ E is assigned the
label |ƒ(u) − ƒ(v)| ∈ {1, 2, . . . ,m}, and no two edge labels are the same. If a graph
G has a graceful labelling, we say that G itself is graceful. A variant is a near graceful
labelling, which is similar, except the co-domain of f is {0, 1, 2, . . . ,m + 1} and the
set of edge labels are either {1, 2, . . . ,m − 1,m} or {1, 2, . . . ,m − 1,m + 1}.
In this thesis, we prove any Dutch windmill with three pendant triangles is (near)
graceful, which settles Rosa’s conjecture for a new family of triangular cacti. Further,
we introduce graceful and near graceful labellings of several families of windmills.
In particular, we use Skolem-type sequences to prove (near) graceful labellings exist
for windmills with C₃ and C₄ vanes, and infinite families of 3,5-windmills and 3,6-windmills. Furthermore, we offer a new solution showing that the graph obtained
from the union of t 5-cycles with one vertex in common (Ct₅
) is graceful if and only if
t ≡ 0,3 (mod 4) and near graceful when t ≡ 1, 2 (mod 4).
Also, we present a new sufficiency condition to obtain a graceful labelling for every
kC₄ₙ snake and use this condition to label every such snake for n = 1, 2, . . . , 6. Then,
we extend this result to cyclic snakes where the cycles lengths vary. Also, we obtain
new results on the (near) graceful labelling of cyclic snakes based on cycles of lengths
n = 6, 10, 14, completely solving the case n = 6.


identifier: Gaviria Salazar, Christian Javier <https://research.library.mun.ca/view/creator_az/Gaviria_Salazar=3AChristian_Javier=3A=3A.html>   (2021) Developing a method for continuously monitoring dissolved organic carbon concentration in boreal forest headwater streams.  Masters thesis, Memorial University of Newfoundland.

abstract:
Headwater streams are an important medium through which carbon from the landscape
is transported into aquatic ecosystems in the form of dissolved organic carbon (DOC), an
ecologically significant and, until the last decade, underestimated pool of mobile carbon. Boreal
forests contain a great fraction of the worlds terrestrial carbon and are considered a large carbon
sink. However, they are vulnerable to climate change and can easily become sources of
atmospheric carbon. To better understand how our landscapes are responding to climate change
we can monitor DOC within headwater streams which integrate and quickly respond to changes
of the surrounding landscape. However, continuous monitoring for DOC is difficult and must be
monitored via proxy-measurements. This thesis demonstrates an approach to develop and
monitor the performance of a model developed to estimate DOC from UV-VIS absorbance and
other data from in-situ probes.


identifier: Swain, Makayla <https://research.library.mun.ca/view/creator_az/Swain=3AMakayla=3A=3A.html>   (2021) Indirect impacts of a non-native ungulate browser on soil ecosystem function is variable across soil horizons in the boreal forests of Newfoundland, Canada.  Masters thesis, Memorial University of Newfoundland.

abstract: Herbivores are key players in ecosystem function and connect nutrient cycling across animal and plant trophic levels. Herbivore impacts on ecosystems can be direct or indirect and it is necessary to study both paths to understand herbivore impacts on above-ground and below-ground ecosystem functioning. We conducted an experiment to test the hypothesis that non-native moose on the island of Newfoundland have negative impacts on plant communities, nutrient cycling, soil composition, and soil organism communities. We collected data on plant and invertebrate communities, climate, and soils in 11 paired exclosure-control plots in eastern and central Newfoundland that provide insight into 22-25 years of moose herbivory. Structural equations models revealed that moose had direct negative impacts on palatable tree height and abundance and an indirect negative impact on soil microbial C:N ratios. We found that moose had a direct negative impact on soil horizon depth and plant material and a positive impact on soil temperature and moisture, particularly in the first soil horizon. We detected no significant impact of moose on soil total C and N, net nitrogen mineralization, or macro-invertebrate communities. Overall, we unearthed evidence of indirect cascading impacts of moose on soil functions although these impacts are relatively weak.


identifier: Mintu, Md. Shafiul Azam <https://research.library.mun.ca/view/creator_az/Mintu=3AMd=2E_Shafiul_Azam=3A=3A.html>   (2021) Theoretical and numerical methods for predicting ship-wave impact generated sea spray.  Doctoral (PhD) thesis, Memorial University of Newfoundland.

abstract:
Spray generated by ships traveling in cold oceans often leads to topside ice accretion, which can be dangerous to vessels. To develop a full methodology of goal based design for ice accretion there are two critical knowledge gaps, both of which are complex to close, and require new methods and techniques. One is a comparison of ice accretion rates for different structures in the same icing conditions. The second knowledge gap is validation data that compares predicted ice growth rates for all types of ship and offshore structures against observed values.
Estimation of the spray flux is a first step in predicting icing accumulation. The amount of spray water, the duration of exposure to the spray, and the frequency at which the spray is generated are all important parameters in estimating the spray flux. Most existing spray flux formulae are based on field observations from small fishing vessels. They consider meteorological and oceanographic parameters but neglect the vessel behavior. Ship heave and pitch motions, together with ship speed and heading relative to the waves, determine the frequency of spray events. Thus the existing formulae are not generally applicable to different sizes and types of vessels. The current study develops simple methods to quantify spray properties in terms that can be applied to vessels of any size or type, which consequently addresses the first knowledge gap. Formulae to estimate water content and spray duration are derived based on principles of energy conservation and dimensional analysis.
To estimate spray frequency considering ship motions, a theoretical model is proposed. The model inputs are restricted to ship’s principal particulars, operating conditions, and environmental conditions. Wave-induced motions are estimated using semi-empirical analytical
expressions. A novel spray threshold is developed to separate deck wetness frequency from spray frequency. Spray flux estimates are validated against full-scale field measurements available in the open literature and reasonable agreement was obtained.
The complex interaction between the structure and a multi-phase fluid, including spray are not fully understood. Limitations of field measurements and model experiments encourage the use of numerical simulation to understand the formation of such spray. In this study, full-scale simulation models of wave-generated sea spray are also developed by implementing a smooth particle hydrodynamics (SPH) method. A three-dimensional (3D) numerical wave tank equipped with a flap-type wave maker and a wave absorber is created to produce regular waves of various heights and steepness. A full-scale medium-size fishing vessel (MFV) is modeled to impact waves in head sea conditions at various forward speeds. Moving ship dynamics with three degree-of-freedom (3-DOF) in waves are resolved instead of mimicking a relative ship speed. The resultant spray water amount is measured using a numerical collection box and compared against field measurements and the theoretical model, where a reasonable agreement is found. The model is able to distinguish between green water and spray water. A multi-phase two-dimensional (2D) simulation is also performed that demonstrates the role of wind in the fragmentation of water sheets into droplets and their distributions over the deck. The simulation results indicate energy released from a surging ship significantly contributes to the generation of spray.
An investigation was also performed to explore means to speed up the computationally intensive SPH simulations. A comparison with a traditional CPU (central processing unit) clusters with GPU
(graphics processing unit) was performed where GPUs demonstrated faster executions. All the SPH simulations were run on GPUs.