Mesocarnivores occupy critical functional roles in regulating ecosystems and maintaining biodiversity. In the Canadian Rocky Mountains, mustelid species depend heavily on carrion as an important dietary contribution, particularly in winter when resources are scarce. In diverse mesocarnivore communities such as this, sympatric species must balance energetic resource acquisitions through scavenging with avoidance of costly competition dynamics, in a manner that optimizes energetic gain through risk aversion. We examined the nature of spatial-temporal interactions between wolverine (Gulo gulo), American marten (Martes Americana), and short-tailed weasel (Mustela erminea) in the Willmore Wilderness Park in western Alberta. Data were collected from camera traps (n = 59) baited with a simulated scavenging opportunity during winter months between 2006 to 2008. The spatial-temporal dimensions of intraguild competition were evaluated using a multi-model approach. Zero-inflated negative binomial (ZINB) or zero-inflated Poisson (ZIP) regression models were used to identify the competitive and environmental factors that affected (1) species presence/absence and (2) how intensely a species would spatiotemporally optimize a carrion site. A time-to-event analysis was used to quantify the directionality of fine-scale (hourly) reactionary behavioural responses of species to potential sources of competition. An extension of this group of models, the Cox proportional hazard (CPH) model was used to further reveal the relative influence of external environmental variables (i.e. diel period, landcover, and snow depth) on temporal spacing. Pairing CPH and ZINB/ZIP models enables us to recognize the relative contribution of fine-scale spatial and temporal behavioural responses to competitors in shaping coexistence strategies. Our results suggest that facultative scavengers adopt different coexistence mechanisms based on the interspecific competitor and environmental conditions they encounter at carrion sites. We found that carrion use was impacted for all species by competition and snow depth. Marten scavenging behaviours were additionally impacted by habitat character. We also found evidence of fine-scale temporal attraction between marten and wolverine, thought to indicate a shared net-energetic gain at scavenging sites. Our results suggest that mesocarnivore scavengers are likely to adopt spatiotemporal mechanisms to facilitate carrion resource partitioning and adapt to conditions specific to carcass placement in a spatially complex environment. Given their vital ecological roles, it is important that we recognize the ability of individual mustelid species to exploit scavenging opportunities and identify the external factors that influence coexistence. Understanding the factors that drive access to these ephemeral resources will provide valuable information for anticipating impacts of climate change on facultative scavengers in the boreal forests of western Canada. / Graduate / 2022-08-23

This research examined the behavior of avian scavenger bone dispersal in a New England environment. The furthest distance that avian species can carry bone elements can be used by search investigators by providing possible distances maximum dispersal. The sizes of bones dispersed by avian species provides context on how bone elements differing in size are transported from the initial site of deposition. The project utilized two locations with elements of varying sizes (large, intermediate, and small) with tracking tags attached to determine the distance and pattern of scavenger displacement. Scavenging was also recorded with motion-sensing game cameras that allowed for differentiation between which species scavenged on which elements, allowing for the distance carried to be associated with individual species. The most common avian scavengers were the northern cardinal (Cardinalis cardinalis), downy woodpecker (Dryobates pubescens), and blue jay (Cyanocitta cristata). The furthest element that was displaced and recovered was a pig rib approximately 62 meters from its initial placement location and it was moved by a crow (Corvus brachyrhynchos). The second furthest element displaced was a pig rib moved approximately 41.5 meters by a Cooper’s hawk (Accipiter cooperii). In addition, six other elements were removed from the platform by birds and not recovered due to possible displacement outside of the search radius and tracking application radius. Overall, 55.0% of elements were recovered within 1 meter of their initial placement location. For elements dispersed under 1 m, Rayleigh z-statistical tests (z =1.328; α = 0.05) for the site location in a wooded area indicated that directionality was not statistically significant, while the location in the wetlands was determined to be statistically significant (z = 20.656; α = 0.05). In addition, a Watson’s U2 Two-Sample Test of Homogeneity (U2 = 0.374) revealed the two groups of average directions are significantly different at α = 0.05. This indicates a difference in direction of displacement between the platforms. For Platform 1 (forested location), the results of the Mann-Whitney U-Test (z = -2.638) indicated that the distances of displacement between the spring and summer seasons are significantly different between the two seasons at α = 0.05. For Platform 2 (wetland location), the results of the Mann-Whitney U-Test (z = -0.859) indicate the distances of displacement between the two seasons were not significantly different between the two seasons at the α = 0.05 value. In addition, Kruskal-Wallis H tests revealed that there was no statistically significant difference between the platform location and the number of site visits for the majority of species. Only two species, cardinals (z = -2.04; α = 0.05) and song sparrows (z = -2.208; α = 0.05), were determined to have a statistically significant difference between the location and the number of site visits.

Depth profiles of S(IV) and S(VI) in snow exposed to 20-140 ppbv SO₂ for 6 to 12 hours have been determined in 48 laboratory experiments. Surface deposition velocity (v(d)) averaged 0.06 cm s⁻¹. Well-metamorphosed snow, longer run times, higher SO₂ concentrations and colder snow were associated with lower values of v(d), and vice versa. Melting followed by draining increased v(d) greatly (0.14 cm s⁻¹. Any effect of ozone on SO₂ v(d) was undetectable. Most sulfur in the snow was as S(VI), even without added ozone, indicating the presence of other oxidants, especially in new snow. Four NO₂ deposition experiments (average v(d) = 0.007 cm s⁻¹), and one combined SO₂-NO₂ deposition experiment were conducted. Ozone, sunlight and SO₂ did not enhance NO₂ deposition; NO₂ and sunlight did not enhance SO₂ deposition. The deposition of SO₂ into a snowpack is modelled as an aqueous system, where the liquid water is considered to be present on snow grain surfaces. Gas transport into the snow, air-water partitioning, and aqueous-phase reactions are explicitly considered. Three oxidants (Fe- or Mn-catalyzed O₂, O₂, and H₂O₂) act to convert S(IV) to S(VI), acidify the film, and inhibit further S(IV) uptake. Model calculations illustrate the primary importance of liquid-water mass fraction (X(m)) and the secondary importance of oxidative reactions on SO₂ v(d) to snow. Model and experimental results are similar for assumed X(m) on the order of one percent. Experiments were also conducted on the incorporation of SO₂ into ice depositing from the vapor at -7 and -15°C. Remarkably, SO₂ is captured in deposited ice at concentrations comparable to Henry's Law equilibrium with water at 0°C. Ozone and HCHO appear to inhibit, not enhance, SO₂ capture. An aqueous-film model accounting for the capture of SO₂ by depositing ice was developed. S(IV) concentrations may be enhanced in the liquid-like layer on growing ice surfaces due to solute exclusion from the bulk ice and greatly-retarded diffusional transport from the ice/film interface, leading to significant incorporation into the ice despite low distribution coefficients. SO₂ snow scavenging ratios may be comparable to sulfate scavenging ratios in the remote troposphere.

Age-model derived sediment mass accumulation rates (MARs) are consistently higher than 230Th-normalized MARs in the Equatorial Pacific Ocean during the past 25 ka. The offset, being highest in the Panama Basin, suggests sediment redistribution in this region is prominent. I test the hypothesis that downslope transport of sediments from topographically highs that surround the Panama Basin is the cause of higher-than-expected xs230Th inventories in the deeper parts of the basin. There is little difference in xs230Th inventories between the highest and lowest reaches of the basin suggesting that the topographic highs did not serve as a source of xs230Th. A spatial analysis suggests that there may be an enhanced scavenging of xs230Th closest to the equator in productive waters. To examine whether lateral mixing of productive equatorial waters with adjacent waters delivers xs230Th to the Panama Basin, I measured dissolved 230Th in eight deep-water casts within the Guatemala, Panama, and Peru Basins along a meridional transect at ~86°W. Below 1000 m, the Panama Basin shows the highest deficit (~50%) of 230Th in deep waters assuming a reversible exchange of 230Th between dissolved and sinking particulate matter. Peru Basin waters have a larger range of dissolved 230Th concentrations (7.9-16.5 fg/kg) than that within Panama Basin waters (5.7-7.1 fg/kg). There is a progressive decrease, suggesting advection, in average dissolved deep-water (>1000 m) 230Th concentrations from the southernmost sites in the Peru Basin toward the Panama Basin. My calculations suggest that advected 230Th is between 15-30% of the total 230Th being produced within waters of the Panama Basin itself. In the Panama Basin, the averaged biogenic barium and opal MARs suggest that productivity was greater during the Holocene (0-13000 years) than that during the last glacial (13000-25000 years) suggesting higher productivity during the Holocene. Uauth, however, is higher in sediments deposited during the last glacial than in those deposited during the Holocene, suggesting that low bottom water oxygen contents rather than respiration of organic matter drives Uauth enrichment. This oxygen depletion during the last glacial suggests that bottom waters were enriched in respired carbon, which, in turn, could be a driver of lower glacial atmosphere pCO2 values.

Contemporary postcolonial critique poses questions about the impact of colonization on the construction of the political. Beginning with David Scott’s account of the limits and even hopeless condition of anticolonial resistance and postcolonial theory, this thesis explores one way in which the political might be reconstructed under postcolonial conditions. The analysis is primarily theoretical in character. I work through texts by Immanuel Kant, Mary Douglas and Partha Chatterjee to recount the narrative of modern politics and its affect upon postcolonial societies. On this basis, I recognize the sovereign state as the key point of contention in accounts of the continuing reproduction of social exclusions. I then identify the imposition of colonial Enlightenment to have refigured authentic modes of self-representation for the colonized; colonial Enlightenment I suggest, conflated cultural difference with the value of right, and has thereby largely depoliticized practices of exclusion. Shifting to consider how postcolonial political space might be reconstructed, I draw on Warren Magnusson’s understanding of urban politics. By challenging the ontological positioning of the sovereign state, the city may be understood as a dynamic political actor that does not erase cultural difference. Then by examining practices of scavenging in Brazil and Argentina, I compare one case in which the sovereign state has effectively perpetuated conditions of social exclusion with a case in which a municipality has been able to address these conditions. I conclude that the contemporary condition of postcolonial critique can indeed be taken in more optimistic directions through challenges to the ontological primacy of the sovereign state so that the value of difference can be recognized and emancipation rethought. / Graduate / 0615 / kerstin@uvic.ca

Masters Research - Master of Philosophy (MPhil) / The growing need of creating a network of sensors in critical environment to monitor, sense and alert an operator about the environment gives rise to the research work carried out in the area of power supply to these sensors. Wireless sensors are usually designed to run on batteries. However, as the number of sensors increases and the devices decrease in size, there is clearly a need to explore alternatives to battery power for wireless sensors. Reliable, efficient and environmentally friendly energy harvesting methods could be adopted to design and build a new electronic device that could be used to replace or supplement batteries in wireless sensors. This thesis focuses on potential ambient sources of power that can be harvested to run low power wireless sensors in mining environments. It discusses several techniques for converting energy from such sources into useful electrical power. In particular, piezoelectric power conversion technique is described in detail. Drilling is a crucial component in both underground and surface mining. Water jet assisted drilling is an example of a new drilling technology employing wireless sensors. There are various forms of energy that could potentially be used to power wireless electronic sensors provided the waste energy can be tapped in an intrinsically safe way. In this particular project, the required power to run sensors could be generated by converting mechanical vibration produced from water jet assisted drilling into electrical energy with an intrinsically safe circuit. Various power scavenging methods were researched, but vibration-to-electricity conversion using piezo-ceramic material was selected as the most promising method for this project. Piezo-based energy conversion is not normally good for mining applications because of intrinsic safety issues. In the case of water jet assisted drilling, however, the environment is much more suitable for piezo-electric conversion. A detailed computer model for this type of power conversion has been developed. The mechanical model of the vibration spectrum is based on test data from the Contents 2 CRC-Mining group. A power conversion circuit has been built, detailed circuit simulations studied and the experimental results are demonstrated. An example vibration scenario consisting of (20x10^-6)rms strain is considered. Based on this, and a detailed model of a 70mmx25mm PZT piezoelectric patch with 0:2mm thickness, our computer simulation studies and experiments demonstrate the ability to harvest up to 210mW of power.

Bubbles are ubiquitous influencing a multitude of biological processes in natural and industrial environments; this influence is especially relevant during and after bubble rupture. Indeed, the influence of a bubble can extend well beyond its lifetime via the droplets produced when it ruptures. These droplets are known to effectively transport nearby particulates including bacteria and viruses into the surroundings, which in addition to affecting human health can influence global climate by acting as cloud condensation nuclei. Further, the bubble's rupture is a violent event that has been linked to decreased cell viability in bioreactors. However, in all these applications many of the studies have taken an empirical approach, making the results difficult to generalize. Here we combine theory and experiment to investigate the static and dynamic interactions between bubbles and the surrounding microorganisms at a free interface. Our first study focuses on the equilibrium shape a bubble forms after reaching the surface of a liquid. Existing literature is limited to a bubble resting on a flat interface; for example, the surface of a pool or calm lake. However, there are instances where this assumption no longer applies -- a bubble bursting on a raindrop, for example. By relaxing this assumption, we show how a curved boundary alters the final shape of the bubble. Our next study focuses on the enrichment of particulates in the cap of a bursting bubble. As a bubble rises to a free surface, particulates in the bulk liquid are frequently transported to the surface by attaching to the bubble's interface. When the bubble ruptures, a fraction of these particulates are often ejected into the surroundings in film droplets with particulate concentrations higher than the liquid from which originate. However, the precise mechanisms responsible for this enrichment are unclear. By simultaneously recording the drainage and rupture events with high-speed and standard photography, we directly measure the concentrations in a thin bubble film. Based on our results, we develop a physical model and provide evidence that the enrichment is due to a combination of scavenging and film drainage. Our next study focuses on the conditions necessary for a jet droplet to be produced. Past research shows that droplet production is halted when either gravitational or viscous effects are significant. Through systematic experimentation we uncover an intermediate region where both effects are significant, leading to an early end of droplet production. By numerically decoupling the gravitational effects into before and after rupture, we find that the equilibrium shape is responsible for the existence of this intermediate region. Our last study focuses on quantifying the localized stresses produced during spontaneous bubble bursting. Directly simulating each bubble and its effect on the suspended cells in a bioreactor is currently infeasible. Here we illustrate how the results of past works, which disagree by several orders of magnitude for similarly sized bubbles, are primarily a result of the chosen numerical mesh, not the underlying physics. By implementing a particle tracking method, we eliminate this mesh dependence and quantify the extent or volume effected by a single bubble bursting event. Based on our results, we develop a generalizable framework that could be integrated into existing models as a parameterization, removing the need to simulate both phases. / 2019-07-09T00:00:00Z

The thesis deals with scavenging on invertebrate cadavers. The goal was to estimate the dynamics of revelation and consumption of the cadavers by scavengers and to evaluate different effects influencing the dynamics in two agricultural habitats meadow and arable field.

Deep geological repository has been investigated as a solution for long term storage of spent nuclear fuel in Sweden for more than 40 years now. The Swedish nuclear fuel and waste management company (SKB) are commissioning the deep repository and they must ensure that nuclear waste is isolated from the environment for thousands of years. During this time the containment must withstand physical stress and corrosion. It is important for a safety analysis to determine the different reactions that could occur during this time. If the physical barriers break down, radiolysis of water will occur. Hydrogen peroxide formed during the radiolysis can oxidize the exposed surface of the fuel, which increases the dissolution of radiotoxic products. Hydrogen peroxide can also catalytically decompose on the surfaces of the fuel. This project set out to figure out the selectivity for catalytic decomposition of hydrogen peroxide. This was to be done analytically with coumarin as a scavenger for detecting hydroxyl radicals formed when hydrogen peroxide decomposes. This produces the fluorescent 7-hydroxycoumarin that with high precision could be measured using spectrofluorometry. The results were giving approximately 0.16% ratio between •OH-production and hydrogen peroxide consumption. Similar experiments were done with ZrO2 for comparison, but the results were largely inconclusive. The effect of bicarbonate (a groundwater constituent) was also investigated. Adding bicarbonate increased the reproducibility of the experiments and increased the dissolution of uranium. Both the uranium and the bicarbonate increased the screening effects which minimized the fluorescent signal output by the 7-hydroxycoumarin. / Geologiskt djupförvar av förbrukat kärnbränsle har undersökts som lösning i Sverige i över 40 år nu. Svensk kärnbränslehantering (SKB) driftsätter det geologiska djupförvaret och måste säkerställa att det förbrukade kärnbränslet hålls isolerat från omgivningen i tusentals år. Under denna tid måste förseglingen stå emot fysikalisk stress och korrosion. Det är därför viktigt för en säkerhetsanalys att undersöka de olika reaktioner som kommer ske. Om förseglingen bryts ned kommer kärnbränslet i kontakt med vattnet i berggrunden vilket leder till radiolys av vatten. Väteperoxid som skapas under radiolysen kan sedan oxidera den exponerade ytan av kärnbränslet, detta ökar upplösningen av radiotoxiska produkter. Väteperoxiden kan även katalytisk sönderdelas på kärnbränslets yta. Syftet med arbetet var att få fram selektiviteten för katalytisk sönderdelning av väteperoxid. Detta skulle uppnås analytiskt med kumarin som avskiljare för detektion av hydroxylradikaler som bildas när väteperoxid sönderdelas. Detta producerade det fluorescerande 7-hydroxykumarinet som med hög precision kunde mätas spektrofluorometriskt. Resultaten gav en ca 0,16% förhållande mellan •OH-produktion och väteperoxidkonsumtion. Likartade experiment gjordes med ZrO2 för jämförelse men resultaten var ofullständiga. Effekten av bikarbonat (en beståndsdel i grundvatten) undersöktes också. Genom addition av bikarbonat ökade experimentens reproducerbarhet och ökade även upplösningen av uran. Både uranet och bikarbonaten minskade den utgående fluorescerande signalen från 7-hydroxykumarinet.

The purpose of this thesis is the development and analysis of applications for ionic polymers as energy harvesting devices. The specific need is a self-contained energy harvester to supply renewable power harvested from ambient vibrations to a wireless sensor. Ionic polymers were investigated as mechanical to electrical energy transducers. An ionic polymer device was designed to harvest energy from vibrations and supply power for a wireless structural health monitoring sensor.The ionic polymer energy harvester is tested to ascertain whether the idea is feasible. Transfer functions are constructed for both the open-circuit voltage and the closed-circuit current. The impedance of the device is also quantified. Using the voltage transfer function and the current transfer function it is possible to calculate the power being produced by the device.Power generation is not the only energy harvesting application of ionic polymers, energy storage is another possibility. The ionic polymer device is tested to characterize its charge and discharge capabilities. It is charged with both DC and AC currents. An energy storage comparison is performed between the ionic polymers and capacitors. While the polymers performed well, the electrolytic capacitors are able to store more energy. However, the ionic polymers show potential as capacitors and have the possibility of improved performance as energy storage devices. Current is measured across resistive loads and the supplied power is calculated. Although the power is small, the ionic polymers are able to discharge energy across a load proving that they are capable of supplying power. / Master of Science