30921 research outputs found
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Effect of ozonation on dissolved organic matter: an insight into operation of biologically active filters in municipal water treatment
No full textThe application of ozone and biologically active filters (BAFs) for dissolved organic carbon (DOC) removal and trihalomethane (THM) control has proven challenging in high-DOC surface waters. This dissertation investigates DOC removal and transformation across various treatment processes, including coagulation/softening, ozonation, and BAFs. This research addresses the limitations of current DOC fractionation methods, developing a novel fractionation method using two solid phase extraction cartridges to assess major DOC fractions of hydrophilic neutral (HPIN), total acidic (TA), and hydrophobic neutral (HPON) without requiring the recovery of sorbed compounds.
Applying this method to a full-scale coagulation/softening plant revealed that while HPON decreased, the remaining HPIN exhibited lower specific UV254 absorbance (SUVA), higher specific THM formation potential (STHMFP), and a shift towards lower molecular weights below 1 kDa. The results did not confirm the exclusive removal of any DOC fraction and highlighted the importance of characterizing changes in DOC quality beyond simple quantification, as the contribution of HPIN to SUVA and STHMFP in treated water was higher than that of HPON.
Further investigation in a full-scale plant revealed that the typical ozone dose (0.4 mg O₃/mg-C) applied to coagulated/softened water with predominantly hydrophilic DOC (72%) did not affect DOC biodegradability or STHMFP. However, increasing the ozone dose to 1 mg O₃/mg-C in lab-scale experiments enhanced biodegradability from 6.3 to 26%, transformed all DOC to hydrophilic, and reduced STHMFP from 69.4 to 11.2 µg/mg-C. Subsequent 28-day batch biodegradation offset the lower STHMFP achieved by the higher ozone dose, increasing it to 60 µg/mg-C due to the formation of low-molecular-weight byproducts.
Finally, the performance of full-scale anthracite/silica sand (BAS) and granular activated carbon (BAC) filters was assessed across summer and winter, considering temperature, empty bed contact time, and backwashing effects. BAC filters achieved greater DOC and BDOC removal during summer, particularly post-backwashing. A specific ATP level of 13×10⁻⁶ ng per bacterial 16S rRNA gene copy number corresponded to this maximum DOC removal. This research provides critical insights into DOC removal and transformation throughout various treatment processes and highlights the complex interplay between operational parameters and BAF performance.February 202
Volatility estimation in agricultural futures markets: a microstructure approach
No full textAgricultural markets are known to be more volatile than the other markets. Understanding volatility movements is important to improve both risk management strategies and market forecasts. In an order-driven electronic trading system, the Limit Order Book (LOB) contains trading information based on market participants expectations. Such information may help explain volatility and utilised to make forecasts. In agricultural market, most previous studies have used daily information to predict volatility. This research uses intraday data to forecast volatility in both lean hog and corn markets. Two models are considered, the well-known GARCH (1,1) and the GARCH-X model which includes LOB information. Intraday forecasts coming from GARCH and GARCH-X are compared with intraday realized volatility (RV). Our findings suggest that GARCH and GARCH-X model forecasts are more in line with each other than with RV, and that GARCH-X forecasts do not outperform GARCH (1,1) forecasts. Reasons associated with these findings, limitations of this study, and future work are outlined.February 202
Distributed six-port reflectometer based vector network analyzer with multiple measurement techniques and applications for microwave imaging
No full textThis thesis presents the design and measurement of a distributed six-port reflectometer-based vector network analyzer. The design has been proven to operate with two independent RF power sources. This novel approach makes our system the first-of-its-kind in the world having the capability for accurate phase measurements of distant antennas and other devices which previously required long coaxial cables incurring high-cost and loss of accuracy due to resulting long cable losses. The specific distributed network analyzer reported on herein has a bandwidth of 0.6-1.2 GHz. The study also evaluates three characterization-based measurement techniques, and two calibration-based measurement techniques reported in the literature and draws a comparison based on their performance when used with the current hardware. A test case has been proven for applications of the current hardware to measure the path characteristics in Microwave Imaging applications. A novel approach for determining the reflection and transmission coefficients of the device under test (DUT) has been introduced and validated, utilizing two characterization-based techniques based on non-linear optimization and a geometrical solution. The results were confirmed using a simulation software (ADS) as well as full experimental results using a custom-built measurement hardware. The novel approach allows accurate S-parameter measurements while increasing computational efficiency and using a lesser number of calibration loads as compared to many previously proposed techniques. Although measurement techniques requiring the full S-parameters of the six-port circuit as well as those not requiring the full S-parameters have been tested, our study found that the characterization-based techniques using S-parameters to be more accurate when performed using our custom measurement hardware.May 202
Living on the margins of society: exploring the traumatic experiences of deportee migrants in Ghana within the contexts of community cohesion, political stability, social exclusion and mental health
No full textWhile the deportation of migrants from around the world to Ghana is a common phenomenon, its socio-economic and political impact has not received considerable attention in policy and research. It is for this purpose that I set out to explore the traumatic experiences of deportee migrants within the contexts of community cohesion, social exclusion, mental health and political stability in Ghana. I adopted the constructivist paradigm in addition to critical race, structural social work and structuration theories to guide the study. The research used a qualitative research design. The study was carried out in the Ashanti, Bono and Greater Accra regions of Ghana. To recruit forty-one (41) participants, I used snowball sampling technique. The findings were collected through semi-structured interviews and analyzed using phenomenological hermeneutic method. Overall, this study shows that reasons for migration, family and community expectations, process of deportation and reception upon arrival in country of origin characterize how deportee migrants name and explain deportation. It further reveals the factors that influence social inclusion or exclusion of deportee migrants in their receiving communities. The results indicate that deportation influences the mental health of deportees during the process of deportation and attempt to participate in normal life in their receiving communities. The findings also show that the family, social networks and nongovernmental organizations remain the largest social support system for deportees. The discussion draws out points of convergences and disagreements between the results, literature review and the theoretical frameworks. This study contributes to the gaps in the literature on deportation and offers a significant contribution that helps in the development of policy initiative on return migration and influences social work education and practice in Ghana.May 202
Effects of chickpea milling and pretreatment on the physical and microstructural characteristics of enriched bread and pasta
No full textChickpeas, with their rich nutritional profile, present a promising ingredient for food enrichment. However, their incorporation into staple foods such as pasta and bread requires understanding the effects of milling and pretreatment of chickpeas on their microstructural behaviour in chickpea-wheat blend formulation. This research investigates the impact of milling and pretreatment methods on the microstructure and physicochemical properties of chickpea-enriched wheat staple products using X-ray microcomputed tomography (X-ray µCT).
Chickpeas were milled using a multi-stage roller mill and a single-stage (Ferkar) mill, yielding five flour types: four flours were obtained from the roller mill (viz., high-protein flour, low-protein flour, reconstituted whole flour, straight-grade flour), and one flour from Ferkar mill (Ferkar-milled flour). These flours were blended with durum wheat semolina in equal amounts for pasta production. The effects of three pretreatment methods - germination, micronization, and roasting - were also studied before milling the chickpeas into straight-grade flour and blending it (in a 20:80 ratio) with wheat flour for bread production.
Physicochemical analysis revealed significant differences (p < 0.05) among pasta samples, with high-protein flour pasta exhibiting lower optimum cooking time, reduced cooking loss, and higher protein and ash contents. Microstructural analysis showed that the high-protein blend resulted in low porosity with closed pores and increased structural thickness, contributing to enhanced firmness and texture. Similarly, the physicochemical properties of chickpea-enriched bread were influenced by roasting and micronizion pretreatment methods, with significant (p < 0.05) effects on loaf volume, colour, and protein content. The microstructural evaluation demonstrated that bread made from germinated chickpeas exhibited superior pore structure, leading to improved overall quality.
In conclusion, this study provides valuable insights into optimizing chickpea milling and pretreatment methods for integration into staple foods such as pasta and bread. Given the rising demand for alternative protein sources, incorporating chickpea flour with minimal microstructural impact presents opportunities for innovation and sustainability within the food industry.October 202
Hollow cone dark field imaging: automatic acquisition, and its contrast for magnesium
Get PDFHollow Cone Dark Field (HCDF) imaging is a powerful technique, yet it remains under-used for contrast-orientation studies—particularly when rapid, well-timed illumination adjustments are required and, up to the present time of authoring this thesis, no dedicated simulation protocols exist.
The key obstacle is software fragmentation: conical-illumination simulation, beam-tilt control, automatic acquisition, and quantitative validation reside in separate programs. Researchers must therefore stitch together ad-hoc scripts and file conversions, hampering usability, reproducibility, and high-throughput studies.
This study addresses the challenge by presenting a single, automated framework that unifies the entire HCDF workflow. A common scripting layer (i) generates orientation grids and supercells, (ii) performs multi-slice simulations, (iii) drives the microscope through continuous hollow-cone tilts while capturing images autonomously, and (iv) overlays experimental and simulated patterns with full parameter logging—eliminating manual data hand-offs at every stage.
Demonstrated on magnesium crystals, the system simulates several hundred HCDF images, with experimental contrast matching simulation closely enough to validate both model and instrument settings. By fusing simulation, real-time acquisition, and validation into one cohesive environment, the framework transforms HCDF from a specialist method into a practical, high-throughput technique helpful for routine orientation mapping and in-situ deformation studies in both academic and industrial contexts.October 202
An ecohealth perspective of non-communicable diseases in Bangladesh: a population-based study of risk factors
Get PDFThe present study focused on food habits, lifestyle, residential location or place (from an ecosystem perspective) and their roles in human health, particularly in influencing non-communicable diseases in Bangladesh. Specifically, it investigated the patterns in hypertension and diabetes prevalence and their risk factors, from an Ecohealth (i.e., interdisciplinary) perspective. The three specific objectives of this study were to: (i) determine the prevalence of hypertension and diabetes among adult population in Bangladesh; (ii) examine the distribution of hypertension and diabetes by age, gender, socioeconomic status, and place of residence; and (iii) identify and analyze the relationship between hypertension as well as diabetes and their risk factors in the country. Secondary data, collected by an IDRC-sponsored project from participants residing in eight districts across Bangladesh, in various spectrums of urbanicity, including metropolitan areas, peri-urban areas (contiguous to the cities), semi-urban areas, and rural areas, were used. Both descriptive and inferential statistical techniques, applying a quantitative approach, were followed to analyze the data.
The results revealed that individuals from higher SES groups exhibited healthier dietary habits, such as consuming more fruits and vegetables. Age, Body Mass Index (BMI), tobacco consumption and fruit and vegetable intake significantly influenced the likelihood of hypertension, highlighting the need for targeted interventions and preventative measures. The findings indicated that 10.7% of the population aged 18 years and above had diabetes, and that aging was a significant determinant of diabetes among Bangladeshi adults. A greater proportion of the participants with diabetes were overweight and/or obese. Among other factors, a higher level of education, likely to be associated with sedentary-oriented occupation and lifestyle, was found to be a significant risk factor for increased odds of diabetes. In addition, an ascending gradient of diabetes from rural to Upazila headquarters (semi-urban) to peri-urban and urban areas was seen. It is recommended that health policies in the country should establish standards and protocols for NCD services at all levels of healthcare. A consideration of the importance of NCD-related public education campaign regarding the ill-effects of urbanism is needed in national policy formulation -- which would help to attain Bangladesh’s commitment to the 2030 UN Sustainable Development Goals.October 202
Obstacles to Diversification: Lived Experiences of Visible Minority Applicants and Faculty Members in Psychology
Get PDFThe profession of psychology demonstrably lacks diversity, with inequitably low numbers of visible minorities represented in the field. Although equity, diversity, and inclusion as a social advocacy movement has received increasing attention within the profession and at the university level, changes are thus far too small to be noticeable. Little is known about the lived experiences of minority applicants applying to professional psychology graduate programs nor the experiences of faculty members involved in student selection processes. We interviewed eight unsuccessful minority applicants, and eight faculty members affiliated with Canadian professional training programs to identify obstacles in diversifying the profession. Thematic analysis of interview data revealed that obstacles were multifaceted, ranging from unsuccessful minority applicants reporting lack of support during the application process and feeling worried about the impact of their identities to faculty members expressing insufficient resources to provide mentorship experiences to minority undergraduate students. We discuss the practical implications of the obstacles identified in relation to how to dismantle those systemic barriers
Detection of lake sturgeon (Acipenser fulvescens) in the Winnipeg River using environmental DNA (eDNA)
Get PDFLake Sturgeon (Acipenser fulvescens), a species of ecological and cultural significance in North America, face population declines due to habitat loss, overharvesting, and environmental changes. Effective monitoring tools are essential for conserving and managing their populations. This thesis explores the utility of environmental DNA (eDNA) as a non-invasive tool for detecting the presence and absence of Lake Sturgeon in the Winnipeg River system and its potential to identify spawning events.
The spatial and temporal distribution of Lake Sturgeon was examined using mitochondrial (Cyt-b) eDNA, revealing seasonal patterns that aligned with previously documented behaviours, such as spawning, foraging, and overwintering. Fifteen sites were sampled once a month from May through to October in both 2021 and 2022. A total of 55/78 samples (70.5%) amplified Lake Sturgeon DNA in 2021 and 45/65 samples (69.2%) in 2022. The relative location of the collection site to the hydroelectric generating stations was found to be a significant influence on the presence of eDNA.
The application of nuclear and mitochondrial eDNA for detecting Lake Sturgeon spawning events using a newly developed ITS-1 assay was found to be successful in a field setting. The nuclear assay only amplified Lake Sturgeon DNA in 14/57 samples (24.6%), all during the suspected spawning period when compared to ideal spawning conditions, successfully detecting the presence of reproductive adults during peak spawning periods. The eDNA results corresponded closely with conventional field observations, including egg deposition and adult sampling. The assay is sturgeon-specific but not species-specific, suggesting its broader applicability for monitoring other North American sturgeon species, though further validation across diverse environmental contexts is required.
The findings of this research underscore the versatility and promise of eDNA as a non-invasive tool for Lake Sturgeon conservation. By identifying critical habitats and reproductive events, eDNA provides an efficient and scalable approach to monitor sturgeon populations and inform targeted conservation strategies. This work lays a foundation for further research into refining eDNA techniques and integrating them into long-term monitoring programs to address ongoing challenges in freshwater species conservation.May 202
Atomistic exploration of deformation mechanisms in metallic nanowires. ABC as a promising approach to overcome timescale limitations of molecular dynamics
Get PDFThis thesis provides an atomistic exploration of deformation mechanisms in single-crystal metallic nanowires subjected to bending and shear stresses. A significant aspect of the work involves evaluating the ABC method as a promising computational approach to overcome the inherent timescale limitations of Molecular Dynamics (MD) simulations. Through comparative analyses, distinct deformation mechanisms such as dislocation nucleation and propagation, twinning, detwinning, twin-boundary migration, and five-fold twin (FFT) boundary formation were systematically identified. While MD simulations were constrained by short simulation timescales, ABC successfully captured slow, time-dependent plastic deformation phenomena such as gradual twin-boundary migrations and stacking fault formations. Additionally, both methods revealed the formation of FFT boundaries, occurring rapidly in MD and gradually in ABC simulations, highlighting ABC’s capability to mimic long-term deformation behaviors. This work emphasizes the directional dependence of deformation modes and underscores ABC’s potential to significantly extend computational capabilities. Ultimately, these findings provide critical insights into nanowire deformation mechanisms, laying the groundwork for future research focused on optimizing nanomaterial reliability and performance.October 202