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Now showing 1 - 10 of 38418
  • ItemOpen Access
    Subjective and objective spatial memory and navigation abilities in aging and amnesia
    (2024-03-16) Pishdadian, Sara; Rosenbaum, R. Shayna
    Compared to the extensive research on how older adults evaluate their memory abilities, the evaluation of subjective spatial navigation abilities is understudied. This dissertation was guided by four research objectives: 1) Investigate the psychometric properties of a subjective spatial navigation questionnaire to assess the nature and extent of self-reported changes to spatial navigation in neurotypical aging; 2) Determine the relationship among subjective assessments of spatial navigation and of memory and how they relate to psychological distress and objective memory performance; 3) Understand the impact of hippocampal damage on subjective awareness of areas of spared and impaired episodic and spatial memory; and 4) Identify more precisely the conditions in which spatial memory and navigation depend on hippocampal integrity. In study 1, multidimensional item response theory was used to evaluate the factor structure and item reliability of the novel Changes in Navigation Questionnaire (CNQ) in a community sample of older adults. Results showed that the CNQ has a reliable factor structure, with items falling under typical and atypical changes. In study 2, the relationship between subjective spatial navigation and metamemory in aging was investigated using structural equation modeling. Findings showed that the subjective spatial navigation and metamemory constructs had a positive, weak correlation. Objective episodic memory performance did not load onto metamemory, and allocentric spatial memory performance had a weak loading onto spatial navigation abilities. Psychological distress symptoms had stronger loadings on metamemory than spatial navigation abilities. In study 3, two individuals with hippocampal amnesia completed questionnaires assessing metamemory and spatial navigation abilities and were compared to age-, gender-, and education-matched controls. The individuals with amnesia reported sound awareness of metamemory and spatial navigation difficulties. Lastly, in study 4, these individuals’ performance on a videogame wayfinding measure was compared with that of thousands of well-matched controls. The individuals showed distinct patterns of impairment and preservation on the tasks. These dissertation results show that subjective spatial navigation abilities can be reliably captured with questionnaires, are weakly related to metamemory, and that accurate self-evaluation is not contingent on intact episodic memory. The findings also highlight specific aspects of navigation that are hippocampal dependent.
  • ItemOpen Access
    A Numerical Modelling Approach to Study the Impact of Ventilation Configurations on Airborne Transmission in Indoor Environments
    (2024-03-16) Khan, Arma Mantissa; Freire-Gormaly, Marina
    The airborne transmission of COVID-19 has been a topic of significant controversy since the pandemic began. Research was needed to demonstrate the importance of airborne transmission and develop tools to recommend appropriate control measures. This study aimed to analyze the factors that impact airborne transmission, find techniques for infection risk minimization, and develop methods to compare different control measures on infection risk. Computational Fluid Dynamics (CFD) studies were conducted to analyze the impact of ventilation layout and infection source location in indoor spaces. A novel spatio-temporal risk model was further developed to quantify the risk in indoor spaces based on different control measures. Conclusions have been made that the ventilation layout and infection source locations can significantly impact the risk of airborne transmitted infection. Further research into building design and airborne transmission minimization techniques is urgently needed to prepare for airborne infectious diseases that may emerge in the future.
  • ItemOpen Access
    Design of Intermittently Operated Reverse Osmosis System and Membrane Coatings for Enhanced Fouling Mitigation
    (2024-03-16) Truong, Brandon; Freire-Gormaly, Marina
    Access to potable water is becoming an increasingly important issue, especially in communities residing in remote, off-grid locations. The use of solar powered reverse osmosis systems has been shown to be a viable solution to delivering clean drinking water. There is a need to improve the fouling resistance of the membranes to reduce costs, maintain water quality, and keep water output reliable. Membrane coatings have been shown to enhance antifouling properties, but more research is required. A lab-scale reverse osmosis (RO) system is developed to enable testing and monitoring of intermittent water treatment processes. Multiple sensors used to measure water quality and permeate flow were incorporated inline to gather data in real time. Membrane coating technology used to improve treatment performance through enhanced antifouling properties was studied. Several coating possibilities were considered for criteria such as: cost, antifouling & anti-scaling properties, and water output quality.
  • ItemOpen Access
    Laser-Induced Graphene Electrodes for Organic Electrochemical Transistors (OECTs)
    (2024-03-16) Nazeri, Mohammad; Grau, Gerd
    Organic electrochemical transistors (OECTs) have drawn a lot of interest because of their low cost, biocompatibility, and ease of fabrication, allowing them to be utilized in various applications including flexible displays, electrochemical sensing, and biosensing. Key components of OECTs are the gate, source, and drain electrodes. Here, OECTs with laser-induced graphene (LIG) electrodes are presented. The electrode patterns for the source, drain, and gate are created by lasing the polymer substrate polyimide (PI). The entire process is simple and inexpensive without complicated chemical synthesis routines or expensive materials such as gold. Patterns can be customized quickly and digitally. Different laser parameters play an important role in changing the conductivity and porosity of the graphene leading to its use in different applications. The low-cost and porous LIG electrodes with low contact resistance, good electrical stability, and adhesion to the polymeric substrate play an essential role in device performance. Due to the flexibility of the laser process, source, drain, and gate can potentially have different properties even though they are fabricated together in a co-planar architecture. The minimum sheet resistance achieved with this laser method for the square patterned electrodes is 7.86 Ω/sq. The LIG-based OECTs demonstrate good electrical modulation and high on-current. The LIG-based OECT shows low OFF current in the order of 0.035 mA.
  • ItemOpen Access
    Vulnerability Assessment of Power Transformers and Power Systems to Geomagnetic Disturbances
    (2024-03-16) Ariannik, Mohamadreza; Rezaei Zare, Afshin
    Powerful solar storms emit plasma that may travel towards the earth. Interactions between the plasma and the earth magnetic field cause geomagnetic disturbances (GMDs), which in turn induce quasi-dc voltage along long conductors in power systems. Assessing the power system resiliency against GMDs requires accurately calculating the induced electric fields and the resultant geomagnetically induced currents (GICs). Offline and online wide-area geomagnetic field monitoring systems are established in this research to estimate GIC flows in power systems accurately. The proposed monitoring systems process the magnetic field signals that are measured at several observatories worldwide. In the offline monitoring system, the magnetic field signals are denoised, and spikes are detected and replaced. The time derivative of the signal is taken by a continuous wavelet transform to prevent amplification of the noises. GICs in a modified IEEE 118-bus benchmark power system are calculated concerning a realistic geomagnetic storm to demonstrate the effectiveness of the proposed signal processing methods. A sliding window is applied in the online monitoring system, and its size is optimized to lower processing time while increasing the signal-to-noise ratio. High amplitude GICs can cause a sharp increase in the hottest-spot temperature of the power transformers. The high temperature allows the formation of gaseous bubbles in the oil-paper insulation and endangers the integrity of the transformer's insulation system. The bubbles include mainly water vapor and emerge in the cavities on the surface of the paper insulation. In the experimental phase of this research, a test setup is created to detect bubbling inception temperature (BIT) for Kraft and thermally upgraded papers (TUPs). The paper samples are dried, prepared at six different moisture levels, and immersed in synthetic ester oil for the experiments. The paper strips are wound around a cartridge heater, and a controller unit raises its temperature at 3 ÂşC/min and 20 ÂşC/min rates to detect BIT. The BITs are considered the operational limit on the hottest-spot temperature of the transformers.
  • ItemOpen Access
    Investigating the function of TRAF1 in NF-ÎşB activation
    (2024-03-16) Tang, Yitian; Abdul-Sater, Ali
    Tumour necrosis factor receptor-associated factor (TRAF) proteins play an important role in mediating the activation of NF-ÎşB. Dysregulation of NF-ÎşB may be one of the potential causes of chronic inflammatory diseases. One member of the TRAF family, TRAF1, has been shown to increase the risk of rheumatoid arthritis (RA). However, TRAF1 plays opposing roles in the activation of NF-ÎşB downstream of the tumour necrosis factor receptors (TNFR) and toll-like receptors (TLR) signalling pathways. In the TNFR pathway, TRAF1 recruits c-IAP2 to promote NF-ÎşB activation and cell proliferation. In contrast, in TLR pathways, TRAF1 negatively regulates NF-ÎşB by sequestering the linear ubiquitin assembly complex (LUBAC). Because of the complex role of TRAF1 in NF-ÎşB activation, it is important to isolate and study the role of TRAF1 in each of these pathways. To better understand TRAF1 and its role in NF-ÎşB activation, our laboratory has identified the same interaction site between TRAF1 and c-IAP2 and created a mutant TRAF1V203A that significantly reduces the interaction with c-IAP2. This study creates a working functional assay to test the effect of these mutants on NF-ÎşB activation. We have generated TRAF1V203A knock-in monocyte THP-1 cells and demonstrated how this mutant alters signalling downstream of TLR and TNFR in monocytes. This study also shows that the production of pro-inflammatory cytokines is reduced in TRAF1V203A mutant monocytes. This study helps us to isolate effects on NF-ÎşB activation and provides an excellent model to study the role of TRAF1 in vivo.
  • ItemOpen Access
    Development of a Kinetically Engineered Microbial Community for Nitrite Shunt as a B-Stage Process Using Different Aeration Strategies
    (2024-03-16) Soliman, Moomen Mahmoud Moharram Abdallah; Eldyasti, Ahmed K.
    Nowadays, depleted energy resources, increasing worldwide energy demand and global climate change has been witnessed. In accordance, wastewater treatment plants (WWTPs) have prioritized minimizing its energy use, maximizing resources recovery, while efficiently treating the received wastewater. Shortcut BNR (SBNR) has been proposed as an energy-efficient nutrients removal process towards lowering the energy use of the current WWTPs. Nonetheless, full-scale implementation of SBNR in mainstream conditions has been hindered by the major challenge of nitrite oxidizing bacteria (NOB out-selection. To address such a key bottleneck, this dissertation proposes, for the first time, a novel kinetic-adaptation based strategy to engineer the microbial community to maintain NOB out-selection at mainstream conditions. The successful implementation of such a strategy and its underlying mechanisms was demonstrated and investigated for more than 400 days. In result, an ammonia removal efficiency of 99.4±0.4% and nitrite accumulation rate of 87.4±0.6% under low DO levels of 0.1–0.2 mg/L was reached. Afterwards, the potential to employ the developed strategy to perform mainstream nitrite shunt was investigated considering the limited carbon availability in the A-stage effluent, its fractionation, and the applied aeration strategy. At carbon to nitrogen (C:N) ratio as low as 6.0, ammonia, COD and total inorganic nitrogen (TIN) removal efficiencies of 99.2±0.7, 94.0±0.1 and 93.2±1.6% were successfully achieved under continuous low DO aeration strategy. Investigations revealed that maintaining NOB suppression played a key role in achieving high TIN without the need for external carbon addition. Two more aeration strategies were investigated, low DO intermittent aeration and high DO intermittent aeration. At C:N ratio as low as 6, higher TIN removal of 95.8±0.9% was achieved at low DO compared to high DO which achieved a TIN removal of 73.8±1.7%. Therefore, it was concluded that the developed kinetic-adaptation strategy can be utilized along with different aeration strategies with slight advantage to low DO intermittent aeration for its higher TIN removal with limited carbon. The findings of this dissertation present a novel strategy that blaze a trail to overcome the major bottleneck of NOB out-selection to implement nitrite shunt at mainstream as energy and resources efficient B-stage process.
  • ItemOpen Access
    A Role for p107 in Muscle Satellite Cell Self-Renewal
    (2024-03-16) Shah, Vicky; Scime, Anthony
    It is well established that skeletal muscle homeostasis is dependent on the activity of the muscle resident stem cells termed satellite cells (SCs). Many neuromuscular dystrophies and complications brought on from ageing are associated with decline to the SC population. Thus, there is a critical need to investigate the control mechanisms that dictate SC fate decisions for self-renewal that are crucial to maintain the SC population. A fundamental regulator of SC fate decisions is mitochondrial metabolism and thereby mitochondrial ATP generation via oxidative phosphorylation (OXPHOS). In our study we uncover a potential novel role for the transcriptional co-repressor retinoblastoma susceptibility protein like 1(Rbl1 or p107) in manipulating the self-renewal capacity of SCs through its mitochondrial localization under the control of the NAD+/NADH ratio. An investigation of this role for p107 function establishes a new mechanism to target SC decline and improve muscle regeneration that is required in muscular dystrophies and ageing.
  • ItemOpen Access
    THE B-CATENIN INTERACTOME IN MYOGENIC CELLS
    (2024-03-16) Fatima Farhat; John Charles McDermott
    Beta-catenin is a versatile protein implicated in a wide range of cellular processes including cell fate determination, proliferation, differentiation, adhesion, and cell survival. Beta-catenin performs its cellular functions through protein-protein interactions since it lacks the ability to interact directly with DNA. Our group has characterized the beta-catenin protein interactome in myogenic cells using a GFP-Nanotrap based affinity purification approach followed LC-MS/MS analysis which produced a comprehensive list of established and potential beta-catenin interactors. The objective of this study was to investigate the beta-catenin interactome dataset to better understand the molecular mechanisms underlying the function of beta-catenin in myogenic cells. To address this objective, we have used bioinformatic and biochemical approaches directed at identifying one potential beta-catenin binding partner and investigating its effect on beta-catenin’s function.
  • ItemOpen Access
    The association of physical activity with prediabetes/type 2 diabetes and cardiac autonomic function
    (2024-03-16) Rubin Kaur Pooni; Jennifer Kuk
    Three separate studies were conducted to assess the association of physical activity with prediabetes/type 2 diabetes (pre/T2D) and cardiac autonomic function. The purpose of study 1 was to examine whether using both objectively (accelerometer) and subjectively (questionnaire) measured moderate- to vigorous-intensity physical activity (MVPA) and sedentary time (SED) improves the prediction of pre/T2D using data from the Framingham Heart Study (n=4200). Logistic regression was used to examine the odds ratio of pre/T2D in groups cross-classified by subjective and objective MVPA and SED. The findings demonstrated that low objectively measured MVPA appears more closely associated with pre/T2D risk compared to subjective measures, and there does not appear to be an additive effect of SED on pre/T2D risk after accounting for MVPA. The purpose of study 2 was to examine the effects of 3-6 months of aerobic, resistance, and combined aerobic and resistance exercise training on heart rate recovery (HRR) from three previously reported randomized trials (n=147). A repeated measures ANCOVA was used to examine differences in 1-, 2-, 3-, 4-, and 5-min HRR from pre- to post-intervention and compared to control adjusting for sex, Tanner stage, ethnicity, and training duration. The findings suggest that aerobic exercise training may be a more effective strategy for improving HRR in adolescents with overweight or obesity. The purpose of study 3 was to examine the association of MVPA or SED and pre/T2D with heart rate variability (HRV) in Hispanic adults using data from the Hispanic Community Health Study / Study of Latinos (n=11 209). Multiple linear regression models were used to examine differences in RMSSD and SDNN in groups cross-classified by MVPA or SED with pre/T2D, adjusting for age, body mass index, sex, education, nutrition, smoking status, alcohol use, cardiovascular disease, and MVPA or SED where appropriate. Having pre/T2D, regardless of MVPA or SED, was associated with lower RMSSD and SDNN. There was an association of high HRV with high MVPA in individuals without pre/T2D, but it did not translate to individuals with pre/T2D. The association of MVPA and SED with HRV in individuals with pre/T2D requires further investigation.