University of Saskatchewan Research Archive
Not a member yet
14369 research outputs found
Sort by
Cerebral sympatholysis: experiments on in vivo cerebrovascular regulation and ex vivo cerebral vasomotor control
Get PDFWhether cerebral sympathetic-mediated vasomotor control can be modulated by local brain metabolism remains unknown. This study tested the hypothesis that application or removal of a cognitive task during a cold pressor test (CPT) would attenuate and restore rises in cerebrovascular resistance (CVR), respectively. Middle cerebral artery blood velocity (transcranial Doppler) and mean arterial pressure (finger photoplethysmography) were examined in healthy adults (n=16; 8 F and 8 M) who completed a control CPT, followed by a CPT coupled with a cognitive task administered either A) at the onset of the CPT and terminated 30 s prior to the end of the CPT or B) 30 s after the onset of the CPT and for the duration of the CPT (condition order was counterbalanced). The major finding was that the CPT increased the index of CVR, and such increases were abolished when a cognitive task was completed concurrently and restored when the cognitive task was removed. As a secondary experiment, vasomotor interactions between sympathetic transduction pathways (α1 adrenergic and Y1 peptidergic) and compounds implicated in functional sympatholysis (adenosine (ADO), and adenosine triphosphate (ATP)) were explored in isolated porcine cerebral arteries (wire myography). The data reveal α1 receptor agonism potentiated vasorelaxation modestly in response to ADO but not ATP. Pre-exposure to ATP attenuated contractile responses to α1 agonism. Overall, the data suggest a cognitive task attenuates increases in CVR during sympatho-excitation, possibly related to an interaction between purinergic and α1-adrenergic signaling pathways
THE LINKS BETWEEN CIRCADIAN CLOCK DISRUPTION AND LIFESTYLE TRAITS IN RHEUMATOID ARTHRITIS
No full textThe abstract of this item is unavailable due to an embargo
Building a Blockchain-based API Access Control System
Get PDFAPI providers can expose their service and data via APIs. However, there must be an access control mechanism in place to control which client can access the APIs. Blockchain technology holds significant potential for this use case. While blockchain may introduce latency, it also offers inherent features including decentralization, data immutability, scalability, and traceability.
This thesis explores implementing a blockchain-based access control system and conducts performance evaluations. The proposed comprehensive solution features a straightforward architecture and a user-friendly web interface. It has been deployed in a cloud environment for development, testing, and performance assessments. Extensive experiments have been conducted to analyze latency and determine the system's breaking point. It can withstand 14000 client apps loading it simultaneously within the cloud environment where it was deployed
POPULATION GENOMICS OF THE GALAPAGOS ISLAND MOCKINGBIRDS AND IMPLICATION FOR CONSERVATION
Get PDFIslands are considered as natural laboratories for the understanding of the evolutionary process of speciation. The very first muses of Darwin’s insights into evolution by natural selection were the Galapagos mockingbirds (Mimus spp.), a monophyletic group of four endemic species. Three species are restricted to a single island each whereas the fourth species occurs on (almost) all the other islands of the archipelago. These birds, known for their limited long-distance flying capabilities, are considered terrestrial species and serve as a clear example of allopatric evolution occurring on islands. The aim of my PhD research has been to unveil the evolutionary history of the Galapagos mockingbird species and its conservation implications using a whole-genome approach. Therefore, my research focused on generating a de novo reference genome within this monophyletic group in order to establish an adequate framework for subsequent genome-wide analyses (Chapter 2), and with it unveil the natural history of contrasting Galapagos mockingbird populations along the archipelago (Chapter 3). My findings have revealed that after the common ancestor of these species diverged, there was a systematic and directional spread of these species to the islands, which is directly related to the age of the islands. The geological history of the islands and anthropogenic factors have had different impacts on the demography and genetic variability of these species. Typically, smaller populations are more inbred and have higher rates of non-synonymous mutations becoming fixed. However, despite their extremely small sizes, the populations on Darwin, Wolf, and Floreana islands have maintained stable population sizes over many generations, indicating that the accumulation of these mutations has not had any impact on the fitness of these populations
Meat-pulse bars: A novel dried meat snack with added pulse flour and its physicochemical, storage, and sensory properties
No full textThe abstract of this item is unavailable due to an embargo
Attacking and Defending Android Browsers
Get PDFAndroid permission is a system of safeguards designed to restrict access to potentially sensitive data
and privileged components. While third-party applications are restricted from accessing privileged resources
without appropriate permissions, mobile browsers are treated by Android OS differently. Android mobile
browsers are the privileged applications that have access to sensitive data based on the permissions implicitly
granted to them.
In this research, we present a novel attack approach that allows a zero-permission app to access sensitive
data and privileged resources using mobile browsers as a proxy with the aid of toast overlay. We demonstrate
the effectiveness of our proxy attack on 8 mobile browsers across 12 Android devices ranging from Android 8.1
to Android 13. Our findings show that all current versions of Android mobile browsers are susceptible to this
attack. Despite Android touch prevention mechanisms for external apps, internal apps and those sharing the
same userID remain susceptible. Contrary to Android’s claims, devices continue to exhibit background toasts
opening an opportunity window for these overlay attacks and posing a threat to browser apps and webview
activities within the same app. We propose a detection approach that leverages a blend of static detection
and activity behavior analysis. Our detection approach enhances Android device security by addressing
overlay vulnerabilities and their potential impact on user privacy and data security. Overall, the findings of
this study highlight the need for improved security measures in Android browsers to protect against privilege
escalation and privacy leakag
Crop water use efficiency from eddy covariance methods in cold
No full textCanada First Research Excellence FundPeer ReviewedCrop–water interactions define productivity in water-limited dryland agricultural production systems in cold regions. Despite the agronomic and economic importance of this relationship there are challenges in quantifying crop water use efficiency (WUE). To understand dynamics driving crop water use and agricultural productivity in these environments, observations of evapotranspiration, carbon assimilation, meteorology, and crop growth were collected over 17 site-years at 5 agricultural sites in the sub-humid continental Canadian Prairies. Eddy-covariance (EC) derived water and carbon fluxes provided a means to comprehensively assess the WUE of current agricultural practices by both physiological (WUEP: g C kg−1 H2O) and agronomic (WUEY): kg yield mm H2O−1 hectare−1) approaches. Mean field scale WUEY for grain yields were 10.4 (Barley), 10.2 (Wheat), 6.0 (Canola), 19.3 (Peas), 12.2 (Lentils) and for silage/forage crops were 23.0 (Barley), 11.9 (Forage), and 20.7 (Corn) (kg yield mm H2O−1 hectare−1). An assessment of environmental factors and their covariance with WUE, utilising a conditional inference tree approach, demonstrated that WUE decreased when crops were under greater evapotranspiration demands. EC-based areal WUE approaches, measuring fluxes over footprints of hundreds of square metres, were compared with more commonly reported point-scale water balance residual approaches (WUEWB) and demonstrated consistently smaller magnitudes. WUEWB was greater than EC-estimated WUEY by an average of 52% and 65% for grain and forage/silage crops respectively. WUEWB also had greater variability than EC estimates, with standard deviations 188% and 128% greater than Barley and Wheat crops, respectively. This comparison highlights the scale dependency of WUE estimation methods, demonstrates considerable uncertainty in point scale water balance approaches due to spatial variability in crop–water interactions, and shows how this variability can be accounted for by EC observations. This improves the understanding of WUE and quantifies its variability in cold continental water-limited climates and provides a means to diagnose improved agricultural water management
ASSOCIATION BETWEEN IMPAIRED SLEEP AND FOUR DOMAINS OF HEALTH BASED ON AN INDIGENOUS MEDICINE WHEEL: FINDINGS FROM TWO FIRST NATIONS COMMUNITIES IN SASKATCHEWAN
No full textThe abstract of this item is unavailable due to an embargo
ANTIMICROBIAL RESISTANCE AND GENOMIC CHARACTERIZATION OF NORTH AMERICAN MELISSOCOCCUS PLUTONIUS ISOLATES
No full textThe abstract of this item is unavailable due to an embargo
Numerical Comparison: Different Methods of Handling Zeros in Microbiome Data Analysis
No full textWith the advancement of sequencing methods, investigators now have more opportunities to understand the microbial community’s role in human and plant health. For instance, studying the biological network among microbial taxa can offer researchers insights into plant breeding. Also, studying the human microbiome can help us to understand functions and illnesses. However, analyzing microbiome data presents significant challenges due to the structure of the data. A critical issue in microbiome data analysis is the presence of a large number of zeros. Although many methods for microbiome data analysis have been published in the current literature, it remains challenging for investigators to select the appropriate method. Therefore, our work focuses on exploring recent methods for handling zeros in microbiome data analysis and provides a detailed numerical comparison. First, we introduce four recent methods: the Bayesian-multiplicative replacement model, the gamma-normal mixture model, the zero-inflated Dirichlet tree multinomial model, and the zero-inflated probabilistic PCA model, detailing their advantages and limitations. Second, we design and implement simulation studies using our novel data generator, the zero-inflated logistic normal multinomial model, which makes use of phylogenetic tree distance. To the best of our knowledge, this is the first zero-inflated model that employs the phylogenetic tree distance. Finally, we evaluated these four methods using the Frobenius norm error, mean squared error for Simpson’s Index, and Wasserstein distance error in this thesis. The simulation results suggest that the Zero-Inflated Dirichlet Tree Multinomial model (with pseudo counts of 0.5 used as the smoothing method) outperforms other methods with the smallest Frobenius norm error and mean squared error for Simpson’s Index. Additionally, the Square Root Multiplicative Treatment model displays notable performance, evidenced by a minimal Wasserstein distance error and efficient running time in our simulation study. Conversely, the zero-inflated probabilistic PCA model does not perform as expected due to issues with parameter estimation convergence