HARVEST
University of Saskatchewan's Repository for Research, Scholarship, and Artistic Work
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Sex differences in exploratory behavior of rats successfully performing the object-in-place recognition memory test
(Behavioural Brain Research, 2024-10) McElroy, Dan L.; Howland, John
Male and female rodents display unique search strategies when exploring new and familiar environments. Sex differences are well-documented in the literature and may be observed in tasks that rely on spontaneous exploration (e.g., recognition memory tests). Therefore, we assessed patterns of male and female rat behavior in the object-in-place (OiP) test, a common recognition memory paradigm involving object-location associations. Twelve male and 12 female adult Long Evans rats were tested four times in the 1-h OiP test and exploratory behaviors were compared during habituation, sample, and test phases. Results revealed that females moved faster and farther than males, showed increased immobility frequency and reduced immobility duration, reduced outer zone mobility duration, and increased inner zone entrances, compared to males during habituations. During sample phases, female rats moved faster than males, displayed reduced immobility frequency in the inner zone, and demonstrated consistent distance travelled across repeated sessions; conversely, male rats moved less in later sessions and exhibited increased mobility frequency in the outer zone. Analyses comparing test phase behavior revealed females continued to move faster than males; however, no other sex differences were observed. These findings are consistent with previous literature highlighting unique sex differences in explorative behaviors during recognition testing. Sex differences in locomotion and mobility state behaviors may be more indicative of individual motivation and search strategy between the sexes and less indicative of recognition memory.
Trade-offs and synergies for urban Production-Living-Ecological spatial Patterns-Comparison study between Fuzhou, China, and Saskatoon, Canada
(Ecological Indicators, 2024-11) Wang, Xi; li, Xiaomei; Sha, Jinming; Zhang, Hao; Shifaw, Eshetu; Guo, Xulin; Lai, Shuhui; Wang, Jinliang
Rapid industrialization and urbanization have significantly changed urban spatial patterns, resulting in the urban ecosystem degradation and urban spatial conflicts. The challenge requires the urban spatial planning more sophisticated for developing eco-city models in the perspective of urban land multifunctionality. The ProductionLiving-Ecological(PLE) spatial pattern is proposed for effective eco-city planning in Chinese urban cases. Given the differing climatic and cultural contexts, are the PLE spatial patterns comparable between cities from different continents? This study aims to compare the characteristics of PLE spatial patterns and the trade-offs & synergies of PLE spaces between Fuzhou city, China and Saskatoon, Canada for developing the eco-city models. First, the paper identified the PLE spaces by integrating multi-source data, then analyzed the PLE spatial agglomeration characteristics by using the average nearest neighbor and kernel density analysis, finally detected the trade-offs and synergies between functional spaces by Spearman correlation and bivariate spatial autocorrelation. The results showed the distinctly different PLE spatial patterns and the trade-offs & synergies of PLE spaces between the two eco-cities in Fuzhou, China and Saskatoon, Canada in 2022. (1) For the PLE space composition, the percentages of ecological space in Fuzhou and Saskatoon were 64.6% and 36.4%, respectively, while the pro portions of the most suitable residential space in two cities from POI data were 2.4% and 4.1%, respectively. (2) For PLE spatial agglomeration, ecological space in Fuzhou was characterized with a random distribution with the average nearest neighbor index of 1.19, and scattered as small patches in urban hilly area covered with evergreen broadleaf trees, while in Saskatoon the index was less than 1.00 with a clustered distribution in numerous city parks covered with grass and shrubs; Fuzhou’s multifunctional spaces were clustered in the central urban area surrounded by ring roads and in Changle District, while Saskatoon’s were dispersed with large patches. (3) For the trade-offs & synergies of PLE space, the ecological spaces in two cities were suppressed. In Fuzhou, the trade-off area ratio of the ecological space to other fuctional spaces was ranged 50% to 58%, while in Saskatoon, it was 40% to 47%. (4) The PLE spatial pattern can clearly sketch the different eco-city frameworks in different continents. Fuzhou’s eco-city model was characterized by “high ecological space/compacted living space/strong trade-off between ES and other spaces” and Saskatoon’s was featured with “low ecological space/spacious residential space with high livability/ weak trade-off between ES and other spaces”. Therefore, Fuzhou faced more challenges of intense spatial competition in the context of dense population. Our findings reveals the practical requirements for optimizing urban space and functions in terms of economic, ecological, and livability considerations. Additionally, they would provide valuable insights for long-term urban spatial planning and development strategies.
Ionization Chamber Measurements of High Energy Radiation
(1953-03) Cormack, Douglas Villy
This thesis reports some of the results of the research conducted by the writer concerning the physical problems involved in the biological use of high energy radiation. The investigation of ionisation chamber response herein reported has led to the study of a number of allied problems, the results of which have been already published and therefore have not been included in the body of the thesis. Reprints of the papers, however, have been attached in Appendix G.
In developing a theoretical expression for the current produced in an ionisation chamber it appeared useful to know the energy distribution of electrons crossing the air volume of the chamber. A method of determining this energy distribution was developed, involving the determination of the initial energy distribution of photo-. Compton and pair electrons produced by a spectrum of radiation. In addition to the
electron distributions, it is possible to derive the distribution of ion densities of the electron tracks produced in water. These ion density distributions provide a physical basis for comparing the biological effectiveness of radiations of various energies. This determination of electron energies and ion densities is given in the paper by Cormack and Johns, a copy of which will be found in Appendix C.
In order to determine these ion density distributions, a thorough study was made by the use of the Klein-Nishina formula of the initial energy and angular distributions of Compton electrons. Values of the differential cross sections were calculated for a large number of photon energies and are given in the paper by Johns, Cormack, Denesuk, and Whitmore (26).
During 1951, the writer was involved in the physical measurements made during the installation of the Saskatchewan 1000-curie Co60 therapy unit. These results have been reported in several journals, but most completely in the article by Johns, Epp, Cormack, and Fedoruk (25). Several theoretical problems dealing with the cobalt unit mere also undertaken. These included the calculation of the percentage depth dose in water of the cobalt radiation and the calculation of the once-scattered radiation from the treatment head of the unit. This work has not yet been published.
Selenium toxicity in fishes: A current perspective
(Chemosphere, 2024-09) Uddin, Md Helal; Ritu, Jinnath Rehana; Putnala, Sravan Kumar; Rachamalla, Mahesh; Chivers, Douglas P; Niyogi, Som
Anthropogenic activities have led to increased levels of contaminants that pose significant threats to aquatic organisms, particularly fishes. One such contaminant is Selenium (Se), a metalloid which is released by various industrial activities including mining and fossil fuel combustion. Selenium is crucial for various physiological functions, however it can bioaccumulate and become toxic at elevated concentrations. Given that fishes are key predators in aquatic ecosystems and a major protein source for humans, Se accumulation raises considerable ecological and food safety concerns. Selenium induces toxicity at the cellular level by disrupting the balance between reactive oxygen species (ROS) production and antioxidant capacity leading to oxidative damage. Chronic exposure to elevated Se impairs a wide range of critical physiological functions including metabolism, growth and reproduction. Selenium is also a potent teratogen and induces various types of adverse developmental effects in fishes, mainly due to its maternal transfer to the eggs. Moreover, that can persist across generations. Furthermore, Se-induced oxidative stress in the brain is a major driver of its neurotoxicity, which leads to impairment of several ecologically important behaviours in fishes including cognition and memory functions, social preference and interactions, and anxiety response. Our review provides an up-to-date and in-depth analysis of the various adverse physiological effects of Se in fishes, while identifying knowledge gaps that need to be addressed in future research for greater insights into the impact of Se in aquatic ecosystems.
A review of the neurobehavioural, physiological, and reproductive toxicity of microplastics in fishes
(Ecotoxicology and Environmental Safety, 2024-09) Hasan, AKM Munzurul; Hamed, Mohamed; Hasan, Jabed; Martyniuk, Christopher J.; Niyogi, Som; Chivers, Douglas P.
Microplastics (MPs) have emerged as widespread environmental pollutants, causing significant threats to aquatic ecosystems and organisms. This review examines the toxic effects of MPs on fishes, with a focus on neurobehavioural, physiological, and reproductive impacts, as well as the underlying mechanisms of toxicity. Evidence indicates that MPs induce a range of neurobehavioural abnormalities in fishes, affecting social interactions and cognitive functions. Altered neurotransmitter levels are identified as a key mechanism driving behavioural alterations following MP exposure. Physiological abnormalities in fishes exposed to MPs are also reported, including neurotoxicity, immunotoxicity, and oxidative stress. These physiological disruptions can compromise the individual health of aquatic organisms. Furthermore, reproductive abnormalities linked to MP exposure are discussed, with a particular emphasis on disruptions in endocrine signaling pathways. These disruptions can impair reproductive success in fish species, impacting population numbers. Here we explore the critical role of endocrine disruptions in mediating reproductive effects after exposure to MPs, focusing primarily on the hypothalamic-pituitary-gonadal axis. Our review highlights the urgent need for interdisciplinary research efforts aimed at elucidating the full extent of MP toxicity and its implications for aquatic ecosystems. Lastly, we identify knowledge gaps for future research, including investigations into the transgenerational impacts, if any, of MP exposure and quantifying synergetic/antagonistic effects of MPs with other environmental pollutants. This expanded knowledge regarding the potential risks of MPs to aquatic wildlife is expected to aid policymakers in developing mitigation strategies to protect aquatic species.
Effects of Modulating Hepatic Nrf1 and Nrf2 Activity on Obesity-linked Metabolic Associated Steatohepatitis
(2024-12-04) Akl, May G; Widenmaier, Scott B; Unniappan, Suraj; Campanucci, Veronica; Bekar, Lane; Xiao, Changting; Schertzer, Jonathan D
Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most prevalent chronic
liver disease. MASLD’s early steatotic asymptomatic stage is liable to progress to a more severe
form known as metabolic dysfunction-associated steatohepatitis (MASH), with advanced
complications such as cirrhosis and cancer. Such detrimental outcomes, besides a lack of effective
therapeutic options, necessitate an adequate understanding of the mechanisms underpinning
disease development and progression.
Hepatocyte lipotoxicity, oxidative damage, and organelle dysfunction are main events when it
comes to MASH progression. The stress defense transcription factors, nuclear factor erythroid 2
related factor-1 (Nrf1) and 2 (Nrf2) are two homologous transcription factors known for their
cytoprotective role. They can also influence cholesterol, triglyceride, and glucose metabolism.
Altogether, this led us to postulate that hepatocyte Nrf1 and Nrf2 exert a potential role in MASH
development and progression and that enhancing their functions can be protective.
In the current thesis, we found that Nrf1 and Nrf2 complementarily regulate genes regulating bile
acid and cholesterol homeostasis. Their combined hepatocyte-specific deficiency accelerated
MASH development after short-term MASH-promoting diet intake. Short-term hepatocyte Nrf1
deficiency was associated with mild steatosis and led to lower fasting and postprandial glycemia,
while hepatocyte Nrf2 deficiency did not induce any evident effects. On the other hand, enhancing
Nrf2 functions for 1-8 weeks, by injecting bardoxolone, effectively reduced lipid accumulation,
inflammation, and fibrosis in MASH and in fibrosis mouse models. Combining Nrf2 induction
with hepatocyte-specific overexpression of NRF1 augmented these effects to some extent.
Moreover, long-term Nrf1 deficiency was accompanied by enhanced incidence of MASH-related
hepatocarcinogenesis, and neither combined Nrf1 & Nrf2 nor Nrf2 deficiency alone showed
similar effect.
In summary, evidence in this thesis reveals that Nrf1 and Nrf2 are two stress defenders
safeguarding against cell stress during MASH development. Both factors’ distinct and synergistic
functions guard against MASH, liver fibrosis, and tumorigenesis. Nrf1 has another distinct
regulatory role over glycemic homeostasis, requiring in-depth exploration. Importantly, these
defense factors may be a beneficial therapeutic target in preventing MASH development and
progression.
Development of a chest X-ray machine learning convolutional neural network model on a budget and using artificial intelligence explainability techniques to analyze patterns of machine learning inference
(JAMIA Open, 2024-07) Stephen, Lee
Objective
Machine learning (ML) will have a large impact on medicine and accessibility is important. This study’s model was used to explore various concepts including how varying features of a model impacted behavior.
Materials and Methods
This study built an ML model that classified chest X-rays as normal or abnormal by using ResNet50 as a base with transfer learning. A contrast enhancement mechanism was implemented to improve performance. After training with a dataset of publicly available chest radiographs, performance metrics were determined with a test set. The ResNet50 base was substituted with deeper architectures (ResNet101/152) and visualization methods used to help determine patterns of inference.
Results
Performance metrics were an accuracy of 79%, recall 69%, precision 96%, and area under the curve of 0.9023. Accuracy improved to 82% and recall to 74% with contrast enhancement. When visualization methods were applied and the ratio of pixels used for inference measured, deeper architectures resulted in the model using larger portions of the image for inference as compared to ResNet50.
Discussion
The model performed on par with many existing models despite consumer-grade hardware and smaller datasets. Individual models vary thus a single model’s explainability may not be generalizable. Therefore, this study varied architecture and studied patterns of inference. With deeper ResNet architectures, the machine used larger portions of the image to make decisions.
Conclusion
An example using a custom model showed that AI (Artificial Intelligence) can be accessible on consumer-grade hardware, and it also demonstrated an example of studying themes of ML explainability by varying ResNet architectures.
The Calgary Declaration: A Different Kind of Unity Initiative
(2000) Sykes, Stuart Jay; Smith, David; Spafford, Duff; Story, Don
The Calgary Declaration is a unity initiative created by the nine English-speaking premiers and two territorial leaders on September 14, 1997. In contrast to both the Meech Lake and Charlottetown accords, little study has been completed on this document, despite the fact that it was the last attempt by Canada's first ministers to deal with the national unity issue in the twentieth century. Study of this initiative is required to identify the status of the national unity debate at the start of the new millennium and to contribute to a better understanding of Canadian
federalism.
The unsettling results of the Quebec referendum of 1995 caused the attitudes of Canadians outside of Quebec to harden. Within Quebec, separatists were prepared to depict a lack of action as an insult. Canadian federalist leaders had to put forward a goodwill overture before the next Quebec provincial election or face the prospect that the "two-solitudes" would become further estranged. However, when the meeting in Calgary finally took place, historic provincial and regional disputes re-emerged. The premiers were only able to agree upon a list of descriptive statements about Canada and a vague public consultation process. Unlike its controversial predecessors, the Declaration focuses upon the principle of federalism instead of institutions. When this fact is combined with its focus on public consultations, the Declaration becomes a document concerned more about reforming Canadian attitudes than institutions.
The response of Canadians to the Declaration's contents, both inside and outside of Quebec, indicates that the federal principle remains firmly embedded in the Canadian identity despite the traumatic results of the Quebec referendum of 1995. Canada's federalist leaders should continue the discussions started by the Calgary process to ensure that when institutional reform is again discussed Canadians will be prepared.
The distribution of Babesia odocoilei in Ixodes species ticks in Canada: Implications for one health surveillance
(Ticks and Tick-borne Diseases, 2024-11) Guillot, Camille; Pelletier, Jerome; Aenishaenslin, Cécile; Coatsworth, Heather; Dibernardo, Antonia; Koffi, Jules K.; Kulkarni, Manisha; Rocheleau, Jean-Philippe; Wilson, Christy; Russell, Curtis; Nelder, Mark; Badcock, Jacqueline; Carr, Justin; Checkley, Sylvia; Clow, Katie M; Cooper, Stephanie; Cork, Susan; Dumas, Ariane; Dergousoff, Shaun; Faraone, Nicoletta; Fraser, Erin; Graham-Derham, Scott; irace cima, alejandra; Iwasawa, Stefan; Jenkins, Emily; Leighton, Patrick; McKay, Roman; Morshed, Muhammad; Pelletier, Roxane; Ripoche, Marion; Rochon, Kateryn; Thivierge, Karine; Voordouw, Maarten; Ogden, Nicholas H; Bouchard, Catherine
Ixodes scapularis and Ixodes pacificus are vectors of a range of pathogens of public health significance in North America. These ticks transmit pathogens to and from wild animal reservoir host species, but also bite humans and expose them to the pathogens. We describe the geographical and temporal distribution of the pathogen Babesia odocoilei, the causative agent of cervid babesiosis. Ixodes spp. ticks collected through active and passive surveillance were submitted to the National Microbiology Laboratory of the Public Health Agency of Canada for analysis of the presence of B. odocoilei from 2018 to 2021. Generalized linear models were constructed to evaluate the temporal change of B. odocoilei prevalence across Canada. Babesia odocoilei-positive I. scapularis are widespread across south-central and eastern regions of Canada, with an overall prevalence of 12.0 % in both nymphs (CI 95 % : 11.4–12.6) and adults (CI 95 % : 11.9–12.1) collected in passive surveillance and 13.2 % (CI 95 % : 12.9–13.5) and 10.0 % (CI 95 % : 9.8–10.2) in nymphs and adult, respectively, collected in active surveillance. A single I. pacificus tick tested positive in active surveillance out of 29 ticks collected in British Columbia, while no B odocoilei-positive I. scapularis were found in passive surveillance among the 11 adult ticks tested. Although B. odocoilei infection prevalence of adult I. scapularis was significantly higher in 2019 (14.1 %) than in 2018 (7.4 %), it remained stable from 2019 to 2021, suggesting that this pathogen may already be well established in endemic tick populations. The results provided in this article represent, to date, the most comprehensive picture of B. odocoilei distribution and prevalence in ticks in Canada and highlight the interest of maintaining One Health surveillance approaches to give added insight into disease transmission cycles for less well-characterized microorganisms.
RIS-Assisted Receive Generalized Space Shift Keying and Receive Generalized Spatial Modulation
(2024-11-28) Marin Flores, Porfirio Ameth; Bedeer Mohamed , Ebrahim; Hanif, Muhammad; Berscheid , Brian; Liang, Xiaodong
The introduction of the 5th-generation (5G) wireless communication standards has brought new applications and services that demand improved technologies to support growing traffic. To meet these demands, researchers have been exploring advanced 5G and future-oriented 6th-generation (6G) technologies. These envisioned technologies indicate the necessity for innovative communication paradigm shifts, especially at the physical layer. Consequently, there has been a growing interest in controlling the propagation channel, leading to the popularity of reconfigurable intelligent surfaces (RIS) as a potential approach for future wireless communications.
Recently, RIS has garnered attention as a potential solution to improve spectrum utilization and energy efficiency (EE). A typical standard RIS model consists of a two-dimensional metasurface of metallic or dielectric materials, equipped with a large array of subwavelength resonators. Software-defined manipulation of these elements modifies electromagnetic (EM) properties, enhancing the reflection of incident radio frequency (RF) signals. Another paradigm that is gaining interest in advancing communication systems is index modulation (IM). With IM schemes, the transmission of information bits occurs by activating or deactivating transmission/reception entities such as transmit antennas, receive antennas, and/or subcarriers. This introduces new dimensions for efficient information conveyance, potentially enhancing the spectral efficiency (SE). %Since IM can exploit the deactivated transmission/reception entities to transmit information bits, it can potentially improve EE.
Hence, in this thesis, we focus on the combination of RIS-assisted systems with IM to further enhance the performance of future wireless communication systems.
In the first main contribution of the thesis, we enhance the performance of wireless communication systems by utilizing RIS and IM. In particular, we introduce two schemes: RIS-assisted receive generalized space shift keying (RIS-RGSSK) and RIS-assisted receive generalized spatial modulation (RIS-RGSM). In the RIS-RGSSK scheme, information bits are conveyed through selection of multiple receive antennas. The RIS-RGSM scheme takes RIS-RGSSK a step further by conveying information bits not only through the selection of multiple receive antennas but also through embedding information bits in the phase of the received signals using $M$-ary phase shift keying (PSK) modulation. We also present simple yet efficient greedy detectors (GDs) for non-coherent detection of both schemes. Simulation results demonstrate the advantages of our proposed methods over existing schemes such as the RIS-assisted receive quadrature space-shift keying (RIS-RQSSK).
In the second main contribution of this thesis, we analyze the performance of the RIS-RGSSK and the RIS-RGSM. Specifically, we find closed-form expressions of the pairwise error probabilities (PEPs) of the RIS-RGSSK and the RIS-RGSM schemes when two antennas are activated at the receiver. Finally, we present comparisons of our analytical results with simulated-based results.