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Effective Medium Approximation for Infrared Surface-Enhancing Substrates
Get PDFSurface-enhanced infrared absorption spectroscopy (SEIRAS) is an increasingly popular analytical technique for studying molecular adsorption, finding applications in catalysis, biosensing and battery research. Crucial to its operation is a textured metal film, which can be produced by physical vapour deposition, galvanic electroless deposition and more recently, electrochemical reduction onto a conductive metal oxide layer. All methods suffer from poorly defined substrates which are difficult to reproduce with a consistent response. A model which predicts the optical response of a SEIRAS film could guide the development of better deposition procedures. This work aims to implement a model utilizing the Bruggeman effective medium approximation (EMA) and the Fresnel equations to calculate SEIRAS spectra for a range of morphologies and validate the calculations with experimental spectra.
The developed model reproduces the asymmetric line shapes seen in experimental measurements, which arise from the Fresnel equations and a small change in the refractive index upon molecular adsorption onto a moderately reflective substrate. The Bruggeman model demonstrates that composite metal-dielectric films can acquire a permittivity function yielding moderate reflection under the conditions of a SEIRAS experiment. The angle-dependent behaviour is explained well by electric field strength calculations. The Bruggeman EMA also successfully explains the general trends observed in SEIRAS films and appears to be a useful tool to optimize the surface morphology for maximal enhancement without yielding bimodal spectra. Further work incorporating percolation theory as well as nucleation and growth models may be able to link the crucial fill-factor parameter to an experimentally accessible variable
Use of Landmarks to Improve Spatial Learning and Revisitation in Computer Interfaces
Get PDFEfficient spatial location learning and remembering are just as important for two-dimensional Graphical User Interfaces (GUI) as they are for real environments where locations are revisited multiple times. Rapid spatial memory development in GUIs, however, can be difficult because these interfaces often lack adequate landmarks that have been predominantly used by people to learn and recall real-life locations. In the absence of sufficient landmarks in GUIs, artificially created visual objects (i.e., artificial landmarks) could be used as landmarks to support spatial memory development of spatial locations. In order to understand how spatial memory development occurs in GUIs and explore ways to assist users’ efficient location learning and recalling in GUIs, I carried out five studies exploring the use of landmarks in GUIs – one study that investigated interfaces of four standard desktop applications: Microsoft Word, Facebook, Adobe Photoshop, and Adobe Reader, and other four that tested artificial landmarks augmented two prototype desktop GUIs against non-landmarked versions: command selection interfaces and linear document viewers; in addition, I tested landmarks’ use in variants of these interfaces that varied in the number of command sets (small, medium, and large) and types of linear documents (textual and video). Results indicate that GUIs’ existing features and design elements can be reliable landmarks in GUIs that provide spatial benefits similar to real environments. I also show that artificial landmarks can significantly improve spatial memory development of GUIs, allowing support for rapid spatial location learning and remembering in GUIs. Overall, this dissertation reveals that landmarks can be a valuable addition to graphical systems to improve the memorability and usability of GUIs
The use of solid-state fermentation to improve the protein quality, functionality and flavour of pulse protein isolates
Get PDFThe aim of this research was to investigate the effect of solid-state fermentation (SSF) by Aspergillus oryzae NRRL 5590 on pea (PPI) and navy bean protein isolate (NBPI) to improve the functional properties, protein quality and flavour profiles. In study 1, proximate composition, physicochemical, functionality properties, and protein quality were evaluated. It was found that degree of hydrolysis of fermented PPI after 48 h was 9.3 and for fermented NBPI after 72 h was 3.6. Regarding to proximate composition, protein content of PPI increased from 82.0 to 83.9% and protein content of NBPI (82.7%) was similar in all fermentation times. Based on surface properties results, the surface charge increased for PPI ranged from -34.1 to -38.8 mV over fermentation time. Surface hydrophobicity increased from 19.3 to 33.2 a.u. (arbitrary units) for PPI and from 11.6 to 17.7 a.u for NBPI. According to functional properties, the nitrogen solubility was found to significantly increase with fermentation time from 8.7 to 34.2 % for PPI (p≤0.05). The emulsion stability (ES) of PPI was found to decline over fermentation time (0-48 h) from 81.1 to 61.35. Whereas foaming capacity and stability increased from 155 to 175% and 33 to 69%, respectively. The solubility, ES, foaming properties were found to remain relatively constant over fermentation time (0-72 h) for NBPI. In vitro protein digestibility (IVPD) showed a reduction during fermentation of PPI from 88.2 to 75.2%. The methionine and cysteine were limiting amino acids for both PPI and NBPI. In summary, fermentation may be used to improve the solubility and foaming properties of PPI and WHC of NBPI for potential use as a food ingredient. In study 2, the effect of fermentation on the presence of volatile compounds in PPI and NBPI were evaluated. Gas chromatography-mass spectrometry (GC) results showed that the flavor compounds in NBPI did not change significantly with fermentation time. However, SSF enhanced new desirable flavour compounds in PPI. These findings suggest that SSF of PPI could potentially improve flavour through the masking undesirable flavour compounds. Together, SSF is an efficient method for improving the solubility, foaming properties, and flavour in PPI
Assessing and Mitigating Ice-Jam Flood Hazards and Risks: A European Perspective
No full text© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).John Pomeroy, director of the Global Water Futures program at the University of Saskatchewan, drone-related fragments of the manuscript are supported by the National Science Centre of Poland through the research project no. 2020/38/E/ST10/00295—carried out by Tomasz Niedzielski, Matylda Witek, Joanna Remisz, Michał Halicki, and Grzegorz Walusiak—within the Sonata BIS programmePeer ReviewedThe assessment and mapping of riverine flood hazards and risks is recognized by many countries as an important tool for characterizing floods and developing flood management plans. Often, however, these management plans give attention primarily to open-water floods, with ice-jam floods being mostly an afterthought once these plans have been drafted. In some Nordic regions, ice-jam floods can be more severe than open-water floods, with floodwater levels of ice-jam floods often exceeding levels of open-water floods for the same return periods. Hence, it is imperative that flooding due to river ice processes be considered in flood management plans. This also pertains to European member states who are required to submit renewed flood management plans every six years to the European governance authorities. On 19 and 20 October 2022, a workshop entitled “Assessing and mitigating ice-jam flood hazard and risk” was hosted in Pozna´ n, Poland to explore the necessity of incorporating ice-jam flood hazard and risk assessments in the European Union’s Flood Directive. The presentations given at the workshop provided a good overview of flood risk assessments in Europe and how they may change due to the climate in the future. Perspectives from Norway, Sweden, Finland, Germany, and Poland were presented. Mitigation measures, particularly the artificial breakage of river ice covers and ice-jam flood forecasting, were shared. Advances in ice processes were also presented at the workshop, including state-of-the-art developments in tracking ice-floe velocities using particle tracking velocimetry, characterizing hanging dam ice, designing new ice-control structures, detecting, and monitoring river ice covers using composite imagery from both radar and optical satellite sensors, and calculating ice-jam flood hazards using a stochastic modelling approach
Harris Lines as Indicators of Physiological Stress in the Middle Holocene Cis-Baikal
Get PDFHarris lines (HL) are thought to represent osteological indicators of physiological stress during early life but are often critiqued by scholars. Recent research, including this study, continues to challenge critiques such as a lack of standardized observational methods, loss of HL due to natural bone remodeling processes, and unclear relationships between physiological stress and HL formation. Including only individuals aged 0–25 years at time of death, this study examined differences in HL presence and frequency across three mortuary populations from the Middle Holocene Cis-Baikal (Russia). Of the three populations, two date to the Early Neolithic (EN) and one to the Late Neolithic (LN). Previous research demonstrates that EN individuals experienced more frequent and repetitive stress events, likely reflecting reduced access to or availability of resources. In order to test the effect of radiographic orientation on HL visibility, X-rays for this study were captured in both the standard clinical view (anterior-posterior; A-P) as well as an alternative view (medial-lateral; M-L) suggested to result in the identification of more HL. In total, radiographs were collected from 104 individuals (Shamanka II, n=52; Lokomotiv, n=23; Ust’-Ida I, n=29). However, 22 individuals were removed from the sample size prior to final statistical analyses due to misidentification by burial number or cultural period (i.e., some individuals from Ust’-Ida I belonged to the Early Bronze Age instead of the targeted LN). Lastly, the subsequent analyses showed two outliers from Ust’-Ida I that impacted the final data set and were thus removed for retesting and final interpretations (final n=80 individuals; Shamanka II, n=34; Lokomotiv, n=22; Ust’-Ida I, n=24).
With the two hypotheses that 1) EN individuals will display higher prevalence and frequency of HL than LN individuals, and 2) images captured in the M-L orientation will display a higher number of visible HL, this study compared HL prevalence both from an inter-site perspective across the three cemeteries as well as from an intra-site perspective with consideration for age at death and sex. Findings from this study indicate a significantly higher number of visible HL in the M-L view but no statistically significant differences in HL prevalence across mortuary populations. Instead, the results of age category comparison found that 6–12-year-olds show the highest count of HL regardless of which mortuary site they originate from. There was also no statistically significant result when HL counts were compared between males and females, with respect to age or site. Given the limited final sample size (n=80), and the indeterminate sex of most younger individuals, the results nonetheless advocate for an age-centered approach when examining HL in conjunction with known indicators of physiological stress. Thus, this study approaches critiques regarding HL validity while actively contributing to understandings of overall stress experiences in the Middle Holocene Cis-Baikal
Wildlife reservoirs and sentinels for vector-borne zoonoses in northern Canada
Get PDFWarming temperatures continue to impact arthropod diversity, density, and distribution in the Canadian Arctic. Consequently, arboviruses and other pathogens that rely on vector transmission have become a growing wildlife and public health concern. As the western Arctic is the most rapidly warming region of Canada and indeed the globe (along with Antarctica), it is imperative to obtain baselines and detect changes in the distribution of vector-borne pathogens, potential reservoirs, and pathogenesis in wildlife hosts. In this thesis, we characterize the prevalence of three groups of vector-borne pathogens in northern Canadian wildlife (California serogroup viruses (CSV), Bartonella spp. and Francisella tularensis bacteria). We also reveal aspects of the disease ecology for these viruses and bacteria, including potential reservoirs and transmission mechanisms. First, we completed a large-scale survey of wildlife in northern Canada for exposure to CSV. Antibodies were detected in all large mammals, including caribou (63%), arctic fox (4%), red fox (12%), and polar bear (28%), and associations with climate and biological factors were identified for polar bears. Both summer air temperatures and sex were significantly correlated with CSV exposure, indicating that climate warming and movement from sea ice onto land increased exposure to CSV in polar bears. Seroprevalence identified in caribou herds from Nunavut (80%) and Northwest Territories (83%) raised questions about their role as a potential reservoir species for Jamestown Canyon virus (JCV), the CSV that is established in cervids in temperate regions of North America. This led to work with captive reindeer (Rangifer tarandus) at the University of Alaska Fairbanks. We determined that reindeer in this herd (housed outdoors) are exposed to CSV under natural conditions, with almost all animals naturally exposed after 2 summers of life. Experimental exposure of naïve and low titre reindeer to JCV demonstrated that they become viremic for up to five days with no observable symptoms, thus serving as reservoirs for JCV and potentially suitable amplifying hosts for mosquitoes. Second, we characterized the diversity of Bartonella communities in rodent reservoirs and revealed a complex web of Bartonella transmission between arctic foxes and their prey species, including rodents and migratory Ross’s and lesser snow geese in the central Canadian Arctic. Most importantly, we found that Bartonella transmission to foxes may occur via nest fleas during nest predation, emphasizing the role of migratory birds as transporters of invertebrate vectors and their pathogens. During this project, we also observed, for the first time, abnormal fur loss on arctic foxes in this population and identified a novel cryptic species of lice that carry an uncharacterized species of Baronella. Finally, we determined exposure of resident arctic foxes at Karrak Lake, Nunavut over the past decade to Francisella tularensis. Antibodies to F. tularensis were correlated with rodent abundance and climate factors associated with rodent survival (spring temperatures, spring snow cover and average summer precipitation), indicating that rodents play an important role in transmission in northern Canada and that young foxes are ideal sentinels for annual transmission risk due to their role as scavengers and predators. The Arctic is not generally considered a hotbed of vector-borne disease, and our work on CSV demonstrates that this is a naïve assumption, with caribou serving as a heavily exposed and potentially asymptomatic reservoir, and that exposure of polar bears may be increasing as they spend more time on land. Our work on Bartonella demonstrates the importance of massive seasonal migrations of birds in introducing temperate species of these intracellular bacteria into transmission of endemic species between rodents (their normal reservoirs) and arctic fox. Our reporting that a newly documented species of fox lice (not a recent introduction of dog lice) is causing fur loss and pelt damage to arctic fox has significance for management and for better understanding the phylogenetic relationships of these highly host specific ectoparasites. And finally, our work on tularemia demonstrates the utility of long-term wildlife health monitoring to better understand the role of native Arctic species in the transmission dynamics of these zoonotic pathogens above the tree line. Together, this thesis reveals a narrative of disease ecology current with climatic changes in one of the most dynamic and remote regions on Earth, where close relationships with wildlife and the land are ecologically and culturally significant
Techno – Economic analysis of activated carbon production from spent coffee grounds: Comparative evaluation of different production routes
Get PDF2590-1745/© 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/).Natural Sciences and Engineering Research Council of Canada (NSERC), BioFuel Net, and Canada
Research Chair (CRC)Peer ReviewedActivated carbon (AC) has gained immense popularity owing to its excellent physicochemical properties and its ability to remove carbon dioxide (CO2) from flue gas stream. This study examines the potential of spent coffee grounds (SCG) as a precursor for activated carbon (AC) production via prominent thermochemical conversion technologies. Different production routes, such as slow pyrolysis, activation, and deep eutectic solvent (DES) functionalization were compared in terms of their economic viability. Three scenarios (Scenario 1–3) involving combinations of the technologies and production routes were evaluated. Scenario 1 comprises of slow pyrolysis, CO2 activation and flue gas recycling for activation. Scenario 2 includes flue gas combustion while the third scenario comprise of flue gas combustion and DES impregnation. All processes were simulated with Aspen plus, while a detailed cash flow analysis was used to estimate the profitability parameters. The price of AC was found to be the most crucial determinant of an AC production plant’s viability and feasibility. The minimum selling price (MSP) of AC samples produced from scenarios 1,2 and 3 are U.S 0.21/kg, 0.45/kg)
A process-based sensitivity guided calibration of the VIC model
No full textCanada First Research Excellence FundNon-Peer ReviewedApplication of Land surface models over large domains relies on calibration of parameters assumed to be consistently sensitive, although parameter sensitivity can vary spatially and by hydrologic process. In this study, the sensitivity of 44 parameters of the VIC model were evaluated over 5 basins with distinct hydroclimatic characteristics. The model is calibrated using a multi-objective framework with 5 objective functions evaluating streamflow, ET and snow cover area (SCA)
Estimating diagnostic test performance and examining effective testing strategies for the control of Johne's disease in western Canadian cow-calf herds
No full textJohne’s disease is the clinical manifestation of persistent infection with the bacterium Mycobacterium avium subspecies paratuberculosis in cattle. Clinical signs include severe diarrhea and gradual weight loss with maintained appetite until the point of emaciation. Infected animals remain in a subclinical state either indefinitely or until clinical signs emerge after a period of 2-6 years. During subclinical infection, animals are capable of transmitting disease by shedding Mycobacterium avium subspecies paratuberculosis (MAP) in their feces on a continuous or intermittent basis. Currently, there is no effective treatment or vaccine for Johne’s disease, therefore control methods are limited to testing and removing infected animals from the herd. Presently, most of the research on the control of Johne’s disease has been focused on dairy cattle, due to the higher disease prevalence and therefore greater perceived threat of the disease within the dairy industry. However, Johne’s disease is of increasing importance to the beef cow-calf sector due to the ongoing consolidation of cow-calf herds in western Canada resulting in greater risk of infectious disease transmission. This thesis aims to address a gap in the current literature related to the performance of diagnostic tests for detecting MAP in Canadian beef herds and effective test and cull strategies for reducing disease prevalence in western Canadian cow-calf herds.
In Chapter 2, the performance of three commonly used diagnostic testing methods was estimated along with the true prevalence of MAP infection in Canadian cow-calf herds. Blood and fecal samples were collected from 3171 cows on 159 cow-calf operations. All blood samples were analyzed with serum ELISA and all fecal samples were analyzed in pools of 5 samples with PCR. A subset of 913 samples from positive and negative herds were also tested individually with PCR. Bayesian latent class models were used to estimate the sensitivity and specificity of each testing method and the true prevalence of MAP. Multivariable regression analysis was used to determine associations between Johne’s disease risk factors and animal and herd positivity status. Results from this study found that the prevalence of MAP was higher in eastern Canadian herds compared to western Canadian herds at both the animal and herd level. Bayesian latent class model analysis yielded a sensitivity and specificity of 96% and 98% respectively for individual PCR at the animal level followed by pooled PCR (Se=54%, Sp=100%) and then ELISA (Se=36%, Sp=98%). Based on analysis of 20 samples per herd, ELISA had a higher sensitivity (Se=79%, Sp=90%) compared to pooled PCR (Se=43%, Sp=99%) for identifying herds with at least one positive sample. Cows from herds with dairy cattle on-farm and cows from herds that had animals show symptoms of Johne’s disease in the previous three years were more likely to test positive for MAP. Herds with animals demonstrating symptoms of Johne’s disease in the previous three years and with a higher number of breeding females were more likely to be MAP positive.
In the third chapter, an agent-based simulation model was developed to study potential options for the control of Johne’s disease in cow-calf herds under typical management practices in western Canada. The diagnostic test sensitivity and specificity values generated in Chapter 1 were included in the model as well as the disease prevalence estimates. Two baseline, non-testing scenarios and 26 testing scenarios consisting of different testing methods, frequencies and combinations of animals targeted for testing were compared using the model. The testing scenarios were ranked based on the within-herd prevalence after a 10-year testing period. The cost of each testing scenario was also calculated to determine the most effective and least-cost testing scenarios. The results of this study found that after a 10-year period, 7 testing scenarios reduced the within herd prevalence below 2% and 4 testing scenarios reduced the within-herd disease prevalence to 1% or lower. Individual PCR testing scenarios were the most effective at reducing disease prevalence after 10-years followed by pooled PCR and then ELISA. Increasing the testing frequency and the number of animals tested had a positive impact on reducing the within-herd disease prevalence after 10 years. Scenarios that were both effective at reducing the prevalence from the initial starting point and were lower in cost included testing a random subset of 50% of the herd with individual PCR every 12 months, restricted testing of cows with less than 4 negative tests every 12 months with individual PCR and whole herd testing with individual PCR every 12 months. A more detailed investigation of the economics associated with testing versus herd infection is needed to determine if testing and culling is a financially attractive option for commercial cow-calf operations