30921 research outputs found
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Evolution of shear-zone fractures presages the disintegration of Thwaites Eastern Ice Shelf
No full textThwaites Eastern Ice Shelf is the remaining floating extension of Thwaites Glacier, anchored by an offshore pinning point at its northern terminus. Over the past two decades, TEIS has experienced progressive fracturing around a prominent shear zone upstream of its pinning point. Our study analyzes the shear zone fracture evolution from 2002 - 2022 and its control on the flow dynamics of the ice shelf, using remote sensing and in-situ GPS observations. We outlined three areas of interest within TEIS: the pinning-point shear zone, the mid-shelf region, and the region upstream of the pinning point. Then we compiled multi-year shear-zone fracture length and orientation statistics from Landsat and Sentinel-1 imagery and assessed their changes against evolving flow dynamics and shear strain rates. We found that the emergence of the shear zone fractures is dynamically linked with the shelf’s interaction with its neighbouring Thwaites Western Ice Tongue (TWIT) in different phases. These phases include the TWIT-driven acceleration phase (2002-2006), TEIS/TWIT shear-margin disintegration phase (2007-2012), TWIT disintegration phase (2012-2017) and TEIS mid-shelf acceleration phase (2017-2022). Post-2010, we observed the emergence of new rifts from the western part of the shear zone, which localized strain and expanded eastwards in the subsequent years. By 2016-17, the shearing-induced fractures rapidly grew, penetrating the entire shelf width. Subsequently, the mid-shelf ice accelerated eastward, while the ice upstream of the pinning point exhibited deceleration. In the austral winter of 2020, an upstream shift of the line of shearing caused an increase in the mid-shelf ice acceleration, as revealed by in-situ GPS observation. Our findings underscore two insights. First, the ongoing disintegration driven by shearing against the pinning point occurred in a two-stage process: growth of large shearing fractures, externally controlled by the flow of the neighboring TWIT earlier in the record, followed by an internally controlled dense fracturing process resulting from high tensile and shearing stresses. Finally, we show that the shear-zone fracturing process is propelled by a positive feedback mechanism between shearing-induced fracturing and the acceleration of upstream ice, which further amplifies fracturing and exacerbates the shelf's disintegration.Canada Excellence Research Chair in Arctic Ice, Freshwater Marine Coupling and Climate Change
https://doi.org/10.13039/501100000038October 202
The role of Nix in calcium signaling, gene expression, and oxidative phenotype of skeletal muscle
No full textMitochondrial quality control is an essential component of muscle biology, with multiple muscular diseases/pathologies associated with dysregulation of this process (e.g., sarcopenia, cachexia, mitochondrial myopathies, and the remodeling associated with obesity and insulin resistance). The protein Nix serves an important role as a mitophagy receptor protein that mediates removal of dysfunctional fragments of mitochondria through the autophagic process. Human genome-wide association studies have connected polymorphisms in the Nix gene with development of mitochondrially-dependent disorders such as schizophrenia and cognitive decline. In muscle, Nix expression has been connected with aging and has been implicated in starvation-induced muscle atrophy. Additionally, Nix has also been implicated as an important factor in models of lipid-induced insulin resistance of muscle, as well as a potential mediator of calcium signaling within the cell. Together this demonstrates the complex, but important, biology of Nix. However, a model to study Nix in skeletal muscle is lacking.
To advance our understanding of Nix in physiologically healthy muscle, we generated and characterised a mouse line harbouring a muscle-specific deletion of Nix. I found evidence of compensated mitochondrial myopathy within muscle that manifests as reduced metabolic rate and capacity for aerobic exercise. Intriguingly, I found that Nix also regulates calcium signaling within muscle to produce a shift towards expression fast fiber types when Nix is deleted in muscle. Previously in cell culture experiments, pharmacological inhibition of Nix was found to restore insulin sensitivity following lipotoxicity-induced insulin resistance. With muscle knockout of Nix, I found heightened sensitivity to insulin that was associated with an mTOR/S6K mechanism described previously in cells. Given the variety of roles described for Nix in muscle, I took the first steps towards uncovering muscle-specific regulation of Nix expression through in vitro studies. To this end, I found that Nix is a direct target of the transcription factors MEF2D of the myogenic program. In summary, I found that deletion of Nix has multiple possible protective effects including protecting metabolism from lipid overload while also directing muscle oxidative phenotype. I have characterized a model to study the biology of Nix, which in addition to novel findings related to calcium and myostatin signaling, provides the basis to study Nix in diseases of muscle or diseases that etiologically involve muscle.October 202
Referral pathway and competency profiles of primary care physiotherapists and kinesiologists for physical activity interventions for diabetes: a modified Delphi study
No full textAbstract Background High quality diabetes care is an essential service in primary care settings since the prevalence and associated complications of diabetes is increasing. Physical activity is effective for the prevention and management of diabetes yet is underutilized in diabetes care. Exercise professionals have specialized skills to deliver physical activity interventions, but effective interprofessional collaboration for diabetes care requires role clarity. This study established the competencies of entry-level physiotherapists and kinesiologists for physical activity interventions for diabetes care in primary care settings and used these competencies to develop clinical tools to promote role clarity in interprofessional care teams. Methods We used a modified Delphi process. Eleven physiotherapy and three kinesiology subject matter experts participated in two rounds of Delphi surveys to develop discipline and context specific competencies. These competencies were used to draft competency profiles and a referral pathway tool. Eleven of the participants then participated in a focus group for member-checking of the tools. Descriptive statistics and content analysis were used to analyze quantitative and qualitative data respectively. Results The modified Delphi process resulted in 38 physiotherapy and 27 kinesiology competencies that identify the distinct roles of physiotherapists and kinesiologists in delivering physical activity interventions for diabetes care. The physiotherapy competencies describes their unique role in supporting people with all types of diabetes to engage in physical activity despite complex medical or physical barriers. The kinesiology competencies indicate where these professionals may require additional training, especially when working with people living with type 1 diabetes or who are pregnant. All developed tools had good face validity and were seen to be potentially useful tools by the subject matter experts. Conclusions The findings highlight that both physiotherapists and kinesiologists have fundamental skills and abilities to deliver physical activity interventions to people living with diabetes, but that different exercise professionals may be needed depending on the complexity of the clinical profile. The developed clinical tools support improved interprofessional collaboration by clarifying physiotherapy and kinesiology roles in delivering physical activity interventions for diabetes care and highlighting how the two distinct professions can contribute to addressing the growing diabetes epidemic in primary care
Development of conductive sodium alginate-polyacrylamide hydrogels for biomedical applications
No full textHydrogels, known for their 3D crosslinked networks that retain significant water, have garnered substantial attention due to their potential in various biomedical fields including tissue engineering, wound dressings, and wearable electronics. To enhance the functionality of hydrogels with both robust mechanical property and excellent conductivity, this work investigates the development of novel conductive hydrogels composed of sodium alginate (SA), polyacrylamide (PAM), and polypyrrole (Ppy). The developed hydrogels are promising for at biomedical applications such as biosensors and drug delivery. The primary focus of this study is to enhance the mechanical robustness and electrical conductivity of these hydrogels to suit potential applications in non-invasive biosensing devices for continuous health monitoring.
The work explores the synergistic effects of integrating conductive polymers and double-network structures, where SA and PAM create a robust matrix through chemical and physical crosslinks, CaCl2 (Ca2+) creates ionic bonds with SA. The Ppy is also incorporated for its conductivity and biocompatibility. Fourier Transform Infrared Spectroscopy (FTIR) confirmed successful synthesis with key functional groups indicating robust formation. Mechanical testing across weight ratios of 1:10, 1:15, and 1:20 for SA-PAM with CaCl2 concentrations of 5wt%, 10wt%, and 20wt% demonstrated the optimal mechanical strength at a 1:10 (weight) ratio with 10wt% CaCl2 with modulus of 385 KPa and peak stress of 61.5 KPa. Similarly, conductivity tests revealed peak conductivity levels of 0.2847 S/cm for positive currents and 0.2748 S/cm for negative currents at the same hydrogel composition (1:10 PAM-SA, 10wt% CaCl2), suggesting excellent potential for biosensor devices designed for continuous health monitoring. The integration of Ppy not only enhanced the conductivity but also contributed to the hydrogels’ biocompatibility and mechanical resilience, making them promising candidates for next-generation medical devices. In addition, rheological studies affirmed the structural integrity under dynamic stresses, indicating the hydrogels’ potential in various biomedical fields including tissue engineering, drug delivery, and wearable electronics. Enhanced crosslinking within the hydrogel matrix ensures improved mechanical properties, enabling broader applications in medical diagnostics and therapeutics, and paving the way for more effective and adaptable hydrogel-based systems in the medical field.October 202
En attendant le céleste héritage: frameworks and methodologies for the archival preservation of Franco-Manitoban folklore
No full textFolklore occupies an interesting space within archives. It can be difficult to capture, and yet it is so culturally important that not doing so seems like an oversight. Archivists have explored in detail the concepts of collective memory and archives as places of memory, yet folklore remains an under-examined topic. This thesis seeks to address some of these gaps where they relate specifically to the Franco-Manitoban community. Using existing scholarship surrounding community archives and collective memory, it delves into the ways in which Franco-Manitoban folklore is currently represented within local archives and the challenges these archives face in making this folklore accessible. It argues that while the challenges may be significant, there is equally significant value in overcoming these challenges. To do this, I use the holdings at the Centre du patrimoine as a case study in the presence of folklore, folk culture and oral history in heritage institutions as it stands today. Throughout this exploration, I apply archival theory in order to examine how community archives can overcome some of the most pressing issues they are facing in regard to folklore-related records and highlight the efforts already being made towards this end. This thesis also attempts identify Franco-Manitoban representation within the larger sphere of online folklore. I discuss the difficulties of defining archives within the vast realm of cyberspace, as well as the advent of Internet-born folklore. Reflecting on the limitations of search engines and online archives, I examine the scattered and sparse nature of Franco-Manitoban folklore on the Internet, observing that there is still much work to be done in this respect.University of Manitoba - Martin Kavanaugh-Gaulthier LaVérendrye FellowshipFebruary 202
Combined magnetic nanoparticle - microwave breast imaging
No full textBackground: Microwave Imaging (MWI) provides a method for imaging and quantitative reconstruction of permittivity and permeability using antennas and electromagnetic waves. MWI has been used for breast-cancer detection amongst many other applications. A possible way of enhancing MWI with a contrast agent is through the use of Magnetic Nanoparticles (MNPs). MNPs will change their permeability with the application of an external DC magnetic field, and thus placing an MWI chamber inside of an electromagnet allows us to generate differential scattered fields by turning the magnet ON and OFF.
Objective: This thesis focuses on collecting the raw data from, and experimentally imaging MNP in an MWI system.
Methods: Using a pre-existing MWI system based on quasi-resonant flat faceted imaging chamber, 24 monopole antennas were used to create a system capable of both detecting MNP and imaging the resulting data. The MWI system was placed in the bore of an electromagnet and experimental data using breast phantoms with MNP tumors (spheres filled with MNP and carrier fluid) was collected. The system at various frequencies was simulated using a Discontinuous Galerkin forward solver, and the collected data was calibrated with the forward solver output and inverted using the Contrast Source Inversion method, showing successful inversion of the expected permeability changes at the frequencies of interest.
Results: Experimental signal from the magnetic contrast of the MNPs was observed at and around 2GHz when the MNP tumors were in the breast phantom (for various positions and concentrations of the MNP). Quantitative 3D imaging of the permeability was attempted for various frequencies where the MNP signal was strong. While some images showed the permeability expected from the MNP, most did not. First, we showed successful image reconstruction of permittivity at several other frequencies than achievable before. An analysis of our data and inversion processes showed that:(1) The raw MNP signal is occurring where there is a resonance in the MWI faceted chamber, and (2) precisely at this resonance, the computational model of the chamber is no longer accurate, likely due to the fact that the computational model ignores the presence of the monopole antennas.
Conclusion: Given that MNP signal was detected experimentally around 2 GHz, and that simulated data was successfully inverted at similar frequencies, the reason that experimental imaging did not succeed is the break down of the accuracy of the forward solver at the chamber resonance. The accuracy of the forward solver at the resonant frequencies of the MWI chamber must be improved for successful microwave imaging using MNP contrast.October 202
Direct numerical simulation of turbulent flow and heat transfer within a wavy-channel
No full textIn this thesis, the effects of varying amplitude-to-period ratio (A/P=0.15, 0.2 and 0.4) on turbulent flow and heat transfer in a wavy-channel at a fixed nominal Reynolds number Reb,nom=5600 have been studied by means of direct numerical simulation (DNS). The results of these flows are further compared with those of a plane-channel flow at a similar Reynolds number. The impact of the wavy wall on the turbulent transport of momentum and thermal energy has been thoroughly investigated through the analyses of the first- through fourth-order statistical moments of the velocity and temperature fields, joint probability density function (JPDF) of the velocity and temperature fluctuations, budget balance of both the turbulence kinetic energy (TKE) and turbulence scalar energy (TSE) transport equations, swirling strength iso-surfaces, 2-D spatial two-point cross- and auto-correlation coefficients of the velocity and temperature fluctuations, and pre-multiplied energy spectra of the velocity fluctuations. A separation region is observed in the wave troughs, resulting in a mean flow recirculation bubble where the convective heat transfer is greatly impacted. It is also observed that the wavy wall induces a strong shear layer at the wave peak that envelope the recirculation bubble and further enhances the transport of turbulence kinetic and scalar energy between the high-momentum hot outer flow and low-momentum cold near-wall flow. Furthermore, it is interesting to observe that as the wave steepness increases, the characteristic length scales of turbulence structures become increasingly shortened in the streamwise direction while aligning more prominently in the vertical direction. Analysis of key performance parameters such as the Nusselt number and total drag coefficient reveal that the thermohydraulic efficiency decreases as the value of A/P increases.February 202
‘There is no such place as away’: residential deconstruction as a method for waste diversion in Canada’s built environment
No full textWaste diversion and reduction continues to be a prominent discussion among Canadian municipalities as we collectively recognize the impact that waste production has on the environment and our future, especially in the context of climate change. Much of the focus in this regard has been on individual waste generation and reduction and the “zero-waste” movement, with less focus on construction, renovation, and demolition (CRD) waste. Research shows that CRD waste contributes between 27% and 40% of total municipal solid waste in Canada and it is estimated that the CRD sector is responsible for 40% of raw material consumption in North America. With an estimated potential of 95% of CRD materials being available for salvage, reuse, repurposing, and recycling, there is a lot of opportunity for growth in responsible CRD waste management. My research shows that deconstruction, rather than demolition of buildings, is an important next step in waste diversion for Canadian municipalities and the waste generated from CRD presents an opportunity to recover a significant amount of resources. This research explores the barriers for deconstruction programs and policies for large, Canadian municipalities, how to overcome those barriers, and establishes a framework for moving forward in a municipal setting, working with the City of Edmonton for a real-world application. The results show that deconstruction has a small foothold in Canada and the US, but there are some leading-edge and developing examples. My framework builds on these and offers a path for actioning residential building deconstruction that can have a significant impact on reducing CRD waste going to landfills.Social Sciences and Humanities Research Council of Canada
https://doi.org/10.13039/501100000155
SSHRC Insight with Dr. John Sinclair
Award Number: 435-2017-0409
https://www.sshrc-crsh.gc.ca/home-accueil-eng.aspx
MITACS
http://doi.org/10.13039/501100004489
MITACS Accelerate and City of Edmonton for half of the funding.
Award Number: IT32613
https://www.mitacs.ca/our-programs/accelerate-core-students-postdocs/
University of Manitoba
https://doi.org/10.13039/100010318
Clayton H. Riddell Faculty of Environment, Earth, and Resources Graduate Entrance
Scholarship
Award Number: 45525
University of Manitoba
https://doi.org/10.13039/100010318
GSA / UMSU Graduate Bursary
Award Number: 44830
https://umanitoba.ca/environment-earth-resources/student-experience/funding-and-awards
University of Manitoba
https://doi.org/10.13039/100010318
MSBI Bursary Fund
Award Number: 27251
https://umanitoba.ca/financial-aid-and-awards/bursaries
University of Manitoba
https://doi.org/10.13039/100010318
Stephen and Alison Philips Bursary in Environmental Studies
Award Number: 44702
https://umanitoba.ca/financial-aid-and-awards/bursaries
University of Manitoba
https://doi.org/10.13039/100010318
MSBI Bursary Fund
Award Number: 27251
https://umanitoba.ca/financial-aid-and-awards/bursariesMay 202
Investigations into the behavior, detection, and mitigation of oil in a sea ice environment
No full textThe Arctic is warming at a rate of three times the global average, and projections warn that the average surface Arctic Ocean temperature may increase by 3 °C by 2100. Due to this Arctic warming, there have been steady decreases in sea ice extent and thickness. In particular, the Arctic has lost much of its multi-year ice (MYI) (i.e., ice that survives multiple summers) and is dominated by first-year ice (FYI) (i.e., ice that grows in the winter but melts in the summer). FYI is more saline than MYI and therefore has a lower albedo, thereby increasing the input of solar radiation into the ice-ocean system by 50%. Further Arctic amplification is caused by the thinning and reduction of snow cover and the occurrence of a longer open water season. A direct consequence of this Arctic warming is an increased interest in oil exploration, extraction, and transport, owing to the greater feasibility, which increases the likelihood of a potential oil spill in the marine environment. Notably, spillage by either an oil tanker or an underwater pipeline poses the biggest threat to the Arctic environment and its inhabitants.
In order to combat this threat, the establishment of viable oil detection and mitigation techniques suitable for Arctic environments are currently in development. This urgency has led to the conduction of several oil-in-ice experiments to study various aspects of oil spill preparedness. The research herein aims to build on past work with a focus on oil behavior (i.e., migration tendencies, encapsulation potential, partitioning within sea ice, evaporation, dissolution, photooxidation, biodegradation), detection (i.e., radar), and mitigation (i.e., bioremediation) in sea-ice environments. This research consists of data collected from two artificial oil-in-ice mesocosm experiments in which microbial analyses (community composition), physical analyses (X-ray, temperature, salinity, brine volume), chemical analyses (oil dielectrics, infrared spectroscopy, gas chromatography–mass spectrometry), and modeling/simulations (computational chemistry, sea ice dielectrics, and normalized radar cross-section) were undergone. This study helps to discern how oil influences the physical properties of sea ice and how, in turn, sea ice influences the chemical (and, therefore, the physical) properties of oil.May 202
Decoration of nano-spikes on polymeric surfaces with quaternized N- chloramines for enhanced antibacterial activity
No full textContact active antibacterial surfaces have wide acceptance to prevent bacteria-related infection. Contact active antibacterial surfaces by the physical killing method are mostly used as implants in the human body and contact active antibacterial surfaces by the chemical killing method are extensively used in devices in hospital areas, the food industry, high touch surfaces, etc. In this study, we have engineered a novel polymeric surface that combines chemical and physical antibacterial strategies. This is achieved by integrating chemical-killing contact active biocides, specifically azido quaternized N-chloramine, with a physical killing approach inspired by the natural antibacterial properties of insect wings. Our fabrication process successfully replicates the nano-scale features of these natural surfaces on a polymer, incorporating nano spikes that are functionalized with an alkynyl handle. This handle facilitates a click chemistry reaction with the antibacterial agent N-chloramine.
The efficacy of the resulting surfaces, denoted as PnCl, was evaluated against Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus (MRSA). Compared to the control surfaces Pn and PCl, PnCl demonstrated superior antibacterial activity. Notably, it achieved a 100% reduction in E. coli populations within 15 minutes of contact and a complete eradication of MRSA within 60 minutes. This study underscores the potential of combining chemical and physical antibacterial strategies on a single surface, offering a promising avenue for developing advanced antimicrobial materials.UofM GET grant (GRADUATE ENHANCEMENT OF TRI-AGENCY STIPENDS (GETS) PROGRAM)
Natural Sciences and Engineering Research Council of Canada
Price graduate women in engineering scholarshipMay 202