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Anthropogenic forcing leads to an abrupt shift to phytoplankton-dominance in a shallow eutrophic lake
No full textThis is the peer reviewed version of the following article: King, L., Devey, M., Leavitt, P. R., Power, M. J., Brothers, S., & Brahney, J. (2024). Anthropogenic forcing leads to an abrupt shift to phytoplankton dominance in a shallow eutrophic lake. Freshwater Biology, 69, 335–350. https://doi.org/10.1111/fwb.14214, which has been published in final form at https://onlinelibrary.wiley.com/doi/full/10.1111/fwb.14214. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.Abstract
1. The timing and causes of lake eutrophication are often obscured when multiple anthropogenic disturbances coincide in space and time. This issue is particularly problematic for shallow lakes in arid regions that experience strong climatic forc-ing which alters lake hydrology and water levels, and further conflates causal drivers.
2. We used Utah Lake (Utah, U.S.A.) as a model system to examine how natural hydrological variability and anthropogenic forcing influence ecosystem structure of large shallow lakes in arid climates. Paleolimnological analyses of sedimentary biogeochemistry, pigments, DNA, and morphological fossils were used to iden-tify shifts in primary production and evaluate the relative influence of regional climate-driven hydrological variability and of humans on ecosystem structure.
3. Sediment cores revealed that the phase prior to non-indigenous settlement in-cluded numerous macrophyte and gastropod remains, sedimentary DNA from plants, low organic matter, and low algal production. An abrupt transition oc-curred in the late 19th century concomitant with agricultural and urban expan-sion and the introduction of common carp, which was characterised by a loss of macrophytes and an increase in phytoplankton abundance as indicated by sedimentary DNA and pigment concentrations. A further shift to increased cy-anobacteria occurred c. 1950 when exponential population growth increased wastewater influx, as recorded by sedimentary δ15N values.
4. Taken together, our data demonstrate that the current eutrophic state of Utah Lake is a function of anthropogenic forcing rather than natural climate-driven hy-drological fluctuations. Furthermore, large lakes in arid regions can exhibit similar patterns of abrupt ecosystem change between alternate states as those observed in northern temperate/boreal and subtropical ecosystems.Utah Department of Water Quality; Utah State University; Natural Sciences and Engineering Research Council of Canada; Canada Research Chairs; Canada Foundation for Innovation; University of Regina; Continental Scientific Drilling Facility; Central Utah Water Conservancy Distric
Application of density functional theory and machine learning in the prediction of efficient catalysts for the oxidative coupling of methane with reduced CO2 production at low temperature
No full textA Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Process Systems Engineering, University of Regina. xxvii, 294 p.The oxidative coupling of methane (OCM) remains a promising means for the production of ethylene. Though high temperatures of 900 oC and above lead to increased conversion of methane, at higher temperatures, the OCM reaction tends to favour a competing reaction that leads to the production of COx product. This thesis focuses on the generation of catalyst component electronic properties via density functional theory (DFT) and the analysis via machine learning (ML) techniques of the combination of the DFT-computed electronic properties and high-throughput experimental data comprising 12708 data points. The DFT data includes the catalyst components' bandgap, Fermi energy and magnetic moment. Variations of a dataset comprising experimental conditions, experiment performance and electronic catalyst properties were used to build a dataset for data modelling and analysis as well as ML analysis for the prediction of CO2 yield, C2H4 yield C2H6 yield, and CH4 conversion. With the aid of multi-linear regression models, Rh, Pt, Ru and Ir were found to be new catalyst promoters that enhance catalyst performance in OCM, particularly with improved methane conversion. A minimum of 58 new bimetallic combinations and 2784 unique catalytic materials with minimum CH4 conversion at 700 oC of 38.5% were identified and proposed as effective catalysts for OCM reaction, an improvement on the 36% CH4 conversion limit from previous studies. The Rh-Li3VO4/SBA15 and Ru-BaZrO3/SBA15 have been proposed as efficient catalysts for the OCM reaction with a predicted C2y of 30% and 29%, respectively.
In comparing predictive model using a dataset containing a combination of catalyst electronic properties, deep neural networks (DNN) configured as deep feed-forward networks with back-propagation, along with random forest regression (RFR), support vector regression (SVR) and extreme gradient boost regression (XGBR), were compared on the basis on their mean-absolute-error, mean-squared-error and coefficient of determination for the prediction of reaction outcomes
including ethane yield, ethylene yield, carbon dioxide yield and methane conversion (C2H4y, C2H6y, CO2y, CH4_conv, respectively) and C2y (a combination of C2H4y and C2H6y). The inclusion of electronic properties of the catalyst components into the dataset improved the performance of the models by approximately 10% compared to a dataset with only reaction conditions. RFR models had better accuracy compared to other modeling techniques, with an average R2 of 0.98 for the predictive models of all five reaction outcomes. The mean squared error and mean absolute error of the RFR models were from 0.12 to 9.03 for MSE and 0.21 to 2.02, respectively. The order of performance of the modeling techniques was RFR > XGBR > SVR > DNN. The order of data fit for the labels for the given modeling techniques was C2H6y > C2H4y > C2y > CO2y > CH4_conv. In the analysis of model feature impacts to identify descriptors for catalytic activity in OCM reactions, it was observed that the Fermi energies of the catalyst promoter, its atomic number and the bandgaps of the bimetallic oxide and the catalyst support emerged as effective descriptors. Specifically, in relation to the C2y predictive model, C2y increases with an increase in dataset features, including the number of moles of the alkali/alkali-earth in the metallic oxide, atomic number of the catalyst promoter and Fermi energy of the promoter and just relatively in the case of temperature, suggesting a highly non-linear relationship between C2y and temperature. It, however, reduces with an increase in the bandgap of the active metal oxide and the methane-to-oxygen ratio. Using the RFR, the Fermi energy of the promoter had a 4.31% impact on the model, while its atomic number had 6.24%, the number of moles of the alkali/alkali-earth in the metallic oxide was 13.69%, and temperature was 33.70% on the C2y predictive model. catalysts with active metal oxides with lower bandgap energy and promoters with magnetic moments may not be as effective as OCM reaction catalysts with less ferromagnetic properties and higher bandgap energy.Studentye
Royal Canadian Mounted Police cadets’ exposure to potentially psychologically traumatic events during the Cadet Training Program
No full textLifetime exposures to potentially psychologically traumatic events (PPTEs) among Royal Canadian Mounted Police (RCMP) cadets starting the Cadet Training Program (CTP) appear lower than exposures reported by serving RCMP, but the prevalence of PPTE exposures during the CTP remains unknown. The current study assessed PPTE exposures during the CTP and examined associations with mental disorders among RCMP cadets. Participants were cadets (n = 449, 24.7% women) from the larger RCMP Longitudinal Study who self-reported critical incidents, PPTE exposures, and mental health disorder symptoms at pretraining and predeployment. Most participants reported no exposures to a PPTE (n = 374, 83.3%) during the CTP. Participants who reported any PPTE exposure (n = 75, 16.7%; i.e., direct or indirect) most commonly reported serious transport accidents, physical assault, and sudden accidental death. The most common direct PPTEs (i.e., “happened to me”) during the CTP were physical assault (n = 13), other unwanted or uncomfortable sexual experience (n = 11), and serious transportation accident (n = 8). The total number of PPTE types reported at predeployment was associated with increased odds of screening positive for any mental health disorder, aOR = 1.22, 95% CI [1.01, 1.49], p = .049, and positively associated with mental health disorder symptoms, ps < .001. These results provide the first assessment of PPTE exposure among RCMP cadets during the CTP, indicating that 16.7% of cadets experience PPTEs directly or indirectly. The PPTEs reported by cadets may help inform additional opportunities to further increase safety during training.Government of Canada; Royal Canadian
Mounted Police; Ministry of Public Safety
and Emergency Preparednes
Counselling at the Youth Resource Centre
No full textA Practicum Report Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Social Work, University of Regina. vi, 51 p.This report details my clinical experience as well as my learnings and insights such as how theory and practice were integrated throughout my field practicum. The practicum was completed at the Youth Resource Centre (YRC) with Mental Health and Addictions Services (MHAS) in Saskatoon within the Saskatchewan Health Authority (SHA). The first sections of this report focus on my learning goals, practicum tasks, and my overall experiences in this setting. I then discuss the three therapeutic frameworks I used: Motivational Interviewing, Cognitive Behavioural Therapy (CBT), and Trauma-Informed Care (TIC). Furthermore, I shared my reflection on how I engaged with the assessment process that this setting provides. I discuss further how the relevant literature and theories are applicable in working with the population receiving services from this Centre. In conclusion, I address the ethical dilemma and social work values that I prominently encounter. I conclude with my final reflection summary.Studentye
How Municipal Actors Leverage Evidence to Support Urban Planning: Perspectives from the City of Regina
No full textDespite growing calls for evidence-informed policy-making, policy- and decision-makers in municipal governments often face barriers to the integration of evidence into their work. These barriers may be especially prominent in small-to-medium-sized cities, which are often comparatively resource-strained relative to the larger cities that are the focus of much of the existing literature. We interviewed 30 municipal actors involved in urban planning at the City of Regina—the municipal government representing the medium-sized city of Regina located in western Canada. Our study revealed that evidence was often positioned differently among policy- and decision-makers. Interviewees had different definitions of evidence, accessed various sources of evidence, placed differing levels of trust in certain forms of evidence, and experienced different barriers to the integration of evidence into their day-to-day work. This article contributes to a better understanding of the role of evidence among urban planners and has important lessons on how to bridge the gap between urban planning policy- and decision-makers and producers of evidence.SHR
Source nutrients identification and management for Lake Diefenbaker irrigation canals
No full textA Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Applied Science in Environmental Systems Engineering, University of Regina. xi, 117 p.Lake Diefenbaker Irrigation Canals are an essential part of the agriculture industry in Saskatchewan, Canada, as they provide irrigated water to the downstream farmers. However, filamentous algal blooms occur throughout canals every summer. These algae are not toxic but a nuisance. They block water intakes within the irrigation canals. At present, the approach for controlling algal blooms in Lake Diefenbaker’s M1 canal is manual cleaning of intake screens and periodic application of the algaecide Magnacide H, which is expensive (approximately one million dollars per year) and may be detrimental to the aquatic ecosystem and canal water quality if it is not handled properly. Therefore, there is a demonstrable need to develop cost-effective and environmentally friendly filamentous algal prevention and control technologies. Successful management of algal blooms in the M1 canal requires understanding nutrient dynamics in the canal, as nutrients are one of the critical factors that cause algal blooms. To date, there are no historical data on the characteristics of the M1 canal water and nutrient level in the periphyton. This study collected and analyzed water and periphyton samples from 18 Lake Diefenbaker M1 canal locations collected during nine field trips from June 2022 to October 2023. The results show that nutrient levels in the canal water were low, some below the detection limits. However, the nutrient levels in periphyton samples were much higher than that in the canal water. The results of the periphyton sample proved quantitatively that the internal source of nutrients is the main contributor to algal blooms in the M1 canal. In addition, site-specific nutrient prevention practices have also been developed to prevent the nutrients from outside the canals, such as from agricultural runoff.
Keywords: Algal Blooms; Filamentous Algae; Internal Nutrient Loading; Lake Diefenbaker Irrigation Canals; Nutrient Dynamics; Nutrient RecyclingStudentye
Development of scintillator-based components for the photosensor system for the Intermediate Water Cherenkov Detector of the Hyper-K experiment and for the time of flight system of the Water Cherenkov Test Experiment
No full textA Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Physics, University of Regina. xxxiii, 240 p.The existence of the neutrino flavour oscillation phenomenon carries a potential CP-violation
phase, CP, that might be the answer to the matter-antimatter asymmetry question in the
Universe. With a new far detector and upgraded components of the successful Tokai-to-
Kamioka (T2K) experiment, the long-baseline aspect of the Hyper-Kamiokande (Hyper-K)
experiment will utilize an upgraded neutrino beam from the Japan Proton Accelerator
Research Complex (J-PARC). The measurement of CP from and ¯ disappearance
modes will be dominated by systematic uncertainties. To reduce these uncertainties to
discovery-level precision, an Intermediate Water Cherenkov Detector (IWCD) is introduced
at a distance of 1 km from the beam source to intercept the neutrino beam at a span of
off-axis angles and energies. This detector will feature high granularity, directionality, and
time response through the use of a multi-photomultiplier tube (mPMT) photo-detection
system. In this thesis I discuss the research and development (R&D) of scintillator-based
detectors for the mPMT system on two main fronts: an internal hit detector for the mPMT
system and a time-of-flight detector for particle monitoring and identification in tests of an
IWCD prototype, the Water Cherenkov Test Experiment. Both detectors aim to contribute to
the reduction of systematic uncertainties in Hyper-K’s attempt to discover CP in the lepton
sector of the Standard Model..
Keywords: Neutrino oscillation, Hyper-Kamiokande, Intermediate Water Cherenkov Detector,
multiPMT, leptonic CP-violation phase, scintillator, time-of-flight detector.Studentye
Joint survival and longitudinal modelling for combined cohorts
No full textA Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Science in Statistics, University of Regina. x, 100 p.A primary goal of survival analysis is modelling the time from an initial event to a failure
event and the factors which affect the hazard rate. In this thesis, we consider data drawn
from an incident cohort study with follow-up and a prevalent cohort study with follow-up,
yielding right-censored failure time data and left-truncated right-censored failure time data,
respectively. In addition to the failure/censoring times, we assume the survival data include
other measured covariates, for example, longitudinal measurements collected throughout
the failure/censoring time durations. In this thesis, we review the methods of estimation
for the proportional hazards model, the linear mixed effects model, and the joint model, to
determine the association between the survival and the longitudinal processes. We introduce
novel estimation methods for the joint model when incident and prevalent cohort data are
combined. Using simulated data, we compare the various individual and combined cohort
estimation procedures. We also apply the combined cohort joint model to examine the
relationship between the mortality of mature female baboons based on their longitudinally
measured glucocorticoid levels.Studentye
Culturally relevant/responsive pedagogy in an EFL context: College English education in China
No full textA Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Education, University of Regina. xvi, 266 p.In China, College English, a core course in many university-level foreign language education, is a requirement for most non-English majors at the undergraduate level in China. In
this doctoral research study, Ladson Billings’ (2014) culturally relevant pedagogy and Gay’s (2010) culturally responsive teaching was adapted for use in a college English course to develop
student’s English language ability while enhancing intercultural awareness and competence.
Guided by sociocultural theory (Vygotsky, 1986), this study employed action research
methodology (Lewin, 1946; Stringer, 2014).
The study took place at a comprehensive university in southwestern China. Participants consisted of 39 first-year students enrolled in the Chinese Language and Literature degree program. Data collection included the principal investigator’s self-reflective research journals, a critical friend’s classroom observations and interviews, student participant questionnaires,
interviews and portfolios. After coding and thematic analysis (Norton, 2009; Saldana, 2016), the initial findings demonstrate that culturally relevant/responsive pedagogy increases student motivation, engagement, in-class participation, and interest in learning English because they
found the content relatable to their own culture and therefore more meaningful. Additionally,
most students indicated that they gained a deeper understanding of their own culture and
cultivated cultural confidence, their English language skills improved, and their knowledge of
the target language culture increased.
In conclusion, an adapted culturally relevant/responsive pedagogy in college English
education has the potential to respond to Chinese foreign language education policies and
requirements and is worthy of in-depth exploration and active application.
CRP IN AN EFL CONTEXT
Key words: Culturally relevant/responsive pedagogy, English as a foreign language, College English.Studentye