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The creation of novel methodologies to examine the effects of phosphorus amendments on petroleum hydrocarbon bioremediation
No full textThe abstract of this item is unavailable due to an embargo
ECOHYDROLOGICAL MODELING OF BEAVER DAMS
Get PDFBeavers (Castor canadensis and C. fiber) are expanding in their native range in North America and Eurasia and are expanding their range into urban environments and the Arctic tundra. Outside their natural range, they are also in Southern Patagonia because of historic releases in the fur industry. Given the broad geographical span of this expansion, it is critical to understand and predict the hydrology of beaver-dominated landscapes. Beavers build dams that modify the water balance and modulate streamflow through different flow states, which might result in drought and flood mitigation. To date, four published hydrological models have been developed to predict these impacts; however, these models were unable to represent dam variability and dynamics. In this study, a model specific to beaver dams was developed to predict the impacts of beaver dams on hydrology by including the flow state dynamics and the heterogeneity of dams and ponds. First, through the instrumentation of the montane peatland of Sibbald Fen in the Canadian Rocky Mountains, I determined that flow state changes of beaver dams are dynamic on a much shorter scale than previously documented. The shifts from one flow state to another happen regularly, have limited synchronicity within dam sequences, and can be predicted. In Sibbald, 66% to 80% of the flow state changes coincided with rainfall-runoff triggers and no changes were associated with biota using the dams. Following this flow state dynamic, I then developed an open-source model called BeaverPy in Python to simulate key features of dams and their impact on hydrology. Five single flow states and mixed combinations were included to identify their dynamics using a vector-based modeling approach, which accounted for changes in dam structures. Simulating individual and in-sequence dams from Sibbald Fen demonstrated that BeaverPy successfully models streamflow modulation by beaver dams, water storage in ponds, and flow state changes. Metrics for simulated vs. measured behavior for streamflow showed a good agreement in root mean squared error (g in beaver-dominated environments, thereby enhancing the understanding of how to incorporate beaver dams into flood mitigation and stream restoration projects and climate change initiatives
URANYL DEPOSITION IN UNCONFORMITY-RELATED DEPOSITS IN THE ATHABASCA BASIN: EVIDENCE FROM URANIUM SPECIATION IN HEMATITE AND GOETHITE
Get PDFWith the exception of the recently discovered stable U4+ chloride complex at high temperatures under reduced conditions, genetic models for the formation of uranium deposits had almost invariably invoked the pivotal roles of soluble U6+ species for the transport of uranium-bearing fluids and their reduction to sparingly soluble U4+ as the deposition mechanism. However, the questions of when and how this reduction in most uranium deposits such as those in the Athabasca basin (Canada) occurred are often not clear. The unconformity-related uranium deposits in the Athabasca basin are commonly accompanied by extensive and intensive hematite-rich alteration halos. Previous U L3-edge XANES studies of uranium-bearing fluid inclusions and thermodynamic modeling demonstrated uranium transport as uranyl (UO22+) species in hypersaline fluids in the Athabasca basin. Electron microprobe analyses reveal that hematite inclusions in two early generations of secondary quartz overgrowth, as well as some disseminated hematite in clay mineral (illite-chlorite) matrices, in both orebodies and associated alteration haloes from five uranium deposits (Arrow, Cigar Lake, Key Lake, McArthur River, and Phoenix) in the Athabasca basin, contain anomalously high contents of uranium (up to 2.16 wt.% UO3). Synchrotron U L3-edge X-ray absorption spectroscopy (XAS) and U 4f X-ray photoelectron spectroscopy (XPS) analyses show that uranium in hematite occurs dominantly as the uranyl species, providing unambiguous evidence for direct uranyl deposition in the Athabasca basin. This mechanism of direct uranyl deposition with hematite and other minerals such as quartz (or their amorphous or microcrystalline precursors) during a single episode of hydrothermal alteration can account for low-grade uranium mineralization, but high-grade uranium deposits in the Athabasca basin required multiple episodes of hydrothermal alteration and reduction-induced deposition mechanisms. In addition, synchrotron U L3-edge XAS analyses show that uraniferous goethite associated with boltwoodite in late alteration assemblages of mineralized metapelites at the Eagle Point deposit is also dominated by the uranyl species, supporting its roles in late uranium remobilization
An Efficient Adversarial Self-Supervised Representation Learning Model for Classification of Anomalies in Wireless Capsule Endoscopy Images
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Fragments
Get PDFThis thesis exhibition explores synesthetic experiences of everyday life. As a multidisciplinary artist, I seek to find a language that transcends cultural barriers. Making sense of the world begins by experiencing it through our senses. I design sensory experiences by employing light, shadows, sound, and silence to embrace the act of pure sensation. My works discuss the ideas of nostalgia, pre-linguistic communication, solitude, identity, displacement, intergenerational trauma, and public and private spaces based on my childhood memories and synesthetic experiences of everyday life as fragments of reality
On the viscoelastic properties of alginate/nHA composite hydrogels for potential bone tissue engineering
No full textViscoelastic properties of biomaterials in tissue engineering have been recognized recently
important. In bone tissue engineering, alginate/nano-hydroxyapatite (nHA) composite materials
have been drawn considerable attention; however, their viscoelastic properties have not been well
discovered and documented in the literature. As inspired, this thesis is to perform an experimental
study on the viscoelastic properties of alginate/nHA composite hydrogels with the focus on
identifying the effect of nHA reinforcement under varying concentrations of calcium chloride
dihydrate (CaCl2) crosslinking solution.
In this study, 12 sets or groups of composite hydrogel samples were designed and prepared by
changing the percentage of nHA from 0 to 6 (with an increment of 2% w/v) and using three
different crosslinking CaCl2 concentrations (50, 75 and 100 mM). The viscoelastic properties of
alginate/nHA composite hydrogel was examined with the help of sinusoidal cyclic compression
test conducted at the physiological frequency of 1 Hz. The viscoelastic properties of composite
hydrogels were determined in terms of loss, storage and complex moduli along with the loss
tangent, percentages of energy released and hysteresis loss.
The results from this study demonstrated that the viscoelastic properties in the case of 100 mM
CaCl2 concentration increased with nHA, and that the loss tangent values increased nHA and
reached a maximal value the case of 75 mM CaCl2 concentration, whereas, with increasing
concentration of CaCl2, 4% nHA composite showed the maximal loss tangent value. The combined
effect of % nHA and CaCl2 concentration on different viscoelastic properties was also examined
with the help of multilinear regression analysis. It has been observed through multilinear
regression that the viscoelastic properties of composite hydrogel can be improved by increasing
the nHA. The effect of crosslinking concentration on moduli values was found to be negative,
whereas, the effect of CaCl2 on loss tangent and hysteresis loss was observed to be insignificant.
Combined together, this study has demonstrated that the viscoelastic properties of composite
alginate/nHA hydrogels could be significantly affected by the concentration of nHA and
crosslinking solution. The composite hydrogels examined in this study show promise or potential
in bone tissue engineering scaffolds, particularly to mimic the bone viscoelastic properties
Cross-section Measurement and Thick Target Production of Terbium Radioisotopes by Enriched Gadolinium Targets
No full textIntroduction Short-lived radioisotopes of the terbium (Tb) family show great prospects in theranostics: the 149Tb can be used for alpha therapy, the 152Tb, as a positron emitter, can be applied for the positron emission tomography (PET), the 155Tb can be used for the single photon emission tomography (SPECT) and for Auger therapy, and finally, the 161Tb can be an alternative to 177Lu for β-therapy. Nevertheless, the applications of Terbium are limited at the moment due to its insufficient production and high cost: except for 161Tb, the other radionuclides are produced by nuclear spallation reactions. The use of enriched Gadolinium (Gd) targets can help to increase their availability according to the following production reactions: 152Gd(p,4n)149Tb 1, 152Gd(p,n)152Tb 1, 155Gd(p,n)155Tb 2 and 155Gd(d,2n)155Tb 3. In this work, the 155Tb is taken as a case study, and Gd2O3 enriched in 155Gd is used. Objectives of this work are on the one hand to measure the cross section of the 155Gd(d,2n)155Tb nuclear reaction induced by deuteron, and on the other hand to irradiate enriched Gd2O3 targets for thick target production with deuteron. Description of the Work or Project For the cross section measurement, thin targets (10-20 µm) are required while thicker targets are preferred for production. Therefore, two types of Gd targets with different thicknesses have been developed through two different techniques. Thin targets were manufactured via the electrochemical co-deposition technique. Uniform Ni/Gd2O3 composite targets with a thickness of 10-20 µm containing about 2 mg of enriched Gd were obtained after 35 min of deposition. These targets were irradiated at GIP ARRONAX cyclotron with deuteron beams. Cross sections of 155Tb and other Tb radionuclides (153Tb, 154Tb and 156Tb) were measured from 8 MeV to 30 MeV. These measurements give the first experimental results for the reaction 155Gd(d,x)Tb. From these results, the thick target yield and the purity of 155Tb were estimated. The irradiation parameters for thick target production were also determined from the simulation. Thicker targets were manufactured through the pelletizing technique. A uniform and compact target with a thickness of 390 µm was obtained using 0.6 g of enriched Gd2O3 powder. This target was irradiated by deuteron beams with an incident energy of 15.1 MeV and a beam intensity of 368 nA for 1 h. The production yield of 155Tb was 10.2 MBq/µAh and the purity was 89% after 14 days of decay. These results are consistent with the estimation obtained by the measured cross sections. Conclusions This work shows the possibility of using enriched gadolinium targets to produce terbium radioisotopes via biomedical cyclotrons. Cross sections of deuteron-induced reactions on enriched Gd were measured and a test of thick target production was carried out. As for large batch production, higher intensity and longer irradiation time will be necessary. To this end, specific encapsulation and cooling systems will also be designed and in addition, pure metal Gd targets with better thermal conductivity will be developed
Streptococcus equi subsp. zooepidemicus infection in pigs: vaccine evaluation and environmental survival studies
No full textStreptococcus equi subsp. zooepidemicus (Strep. zoo) in swine has been a concern in North
America after its initial detection in 2019, where it was associated with increased mortality and
high abortion rates. Historically, the ST-194 strain was associated with the death of more than
300,000 pigs during the 1970s in China. There is no approved vaccine for this disease and
limited information about the disease in swine operations. Overall, our objective was to assess
the efficacy of a novel live attenuated vaccine in preventing this disease and determine the
viability of the bacteria in different farm-like conditions.
First, a live attenuated vaccine was evaluated. Thirty-nine, 5-week-old pigs were allocated to
three groups: live vaccinated (20), killed vaccinated (10) and placebo (n = 9). Four pigs were
euthanized a week after vaccination to assess the safety of the vaccine. The other pigs were given
two doses of the vaccine 23 days apart. Pigs were challenged with a virulent strain 42 days after
the initial dose. No mortalities were observed in H1 vaccinated while 100% mortality and 66%
mortality occurred in pigs receiving the killed vaccine and placebo, respectively.
A second experiment evaluated the survival time of Strep. zoo under farm conditions. Strep. zoo
was spread on the surface of rubber, plastic, wood, and concrete. Samples were incubated under
ideal culture conditions (37°C, 5% CO2) or farm-like conditions (20°C, air), in the presence of
absence of feces. In a farm setting, the bacterium can survive up to 17 days under ideal
conditions without feces, and up to 3 days under farm conditions with feces.
This work described a novel live attenuated vaccine which can be used to prevent clinical sign
and deaths in pigs. The oral or nasal route of vaccination ensures that mass vaccination can be
easily achieved. Similarly, the results on viability time of Strep. zoo under different conditions
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and the different surfaces provided valuable information to develop elimination plans from
operations affected with Strep. zoo pathogen during the outbreak
Immigrant CEOs and Firm Performance
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Introducing the Catholic Archive: Revisiting the Reception of Thomas Aquinas and the Modernist Crisis (1850-1917)
No full textThis thesis introduces the concept of the ‘Catholic archive.’ Influenced by Derridean and Foucauldian philosophy, the Catholic archive is attentive to how notions of orthodoxy and heterodoxy are discursively constituted, and how knowledge is consequently privileged or marginalized within Catholic contexts. It also notes the vanishing point between the Catholic Church’s theology and politics, especially as they pertain to ecclesial governance and discipline. This thesis then analyzes the Catholic archive from 1850-1917 to trace how the theologian Thomas Aquinas became the standard for orthodoxy during this period.
As a response to social and political instability in the nineteenth century, Pius IX and Vatican I consolidated power within the ecclesial hierarchy. What the hierarchy lacked, however, was the archival capacity to reliably determine orthodox from heterodox knowledge. Leo XIII provided this capacity, notably in his encyclical Aeterni patris (1879), by making Aquinas an unassailable standard of orthodoxy. This transformation influenced Pius X’s suppression of the Catholic Modernists, who rejected Thomism and were influenced by Enlightenment thought and the historical-critical method. In Pascendi dominici gregis (1907), Pius X uses Aquinas as a theological litmus test to identify and discipline Modernists. The theological renewal of Leo XIII’s papacy became a reign of terror in Pius X’s, in which the hierarchy’s interpretation of Aquinas legitimated archival violence: censorship, excommunication, and career sabotage.
This thesis shines light on hitherto unacknowledged Thomistic discursive formations and their theo-political significance. It also contributes to the Religion and Culture scholarship by reframing Catholic theo-politics as an expression of the dominant interpretations of Aquinas within the Catholic archive. These interpretations have not only limited the institutional acceptance of alternative philosophies or worldviews but provided the theological justification to suppress potentially nourishing alternatives