MacEwan Open Journals (MacEwan University)
Not a member yet
2252 research outputs found
Sort by
Localization of Moving Sound Sources In Virtual Reality Technology
No full textTo localize sounds, the brain uses differences in sound phase and amplitude between the ears; however these cues can lead to ambiguity in localization. In 1940, Hans Wallach discovered an illusion in which a sound source appears stationary when it moves at twice the angular velocity of head rotation.
Recent advances in virtual-reality (VR) technology have allowed us to recreate this illusion using headphones and a VR headset. We are using this system to investigate how the brain handles ambiguity in perception of dynamic auditory scenes. We can also investigate practical problems that may arise when simulating moving sound sources in virtual or augmented reality situations.
* Indicates faculty mento
The quantification of the distribution of proteins Kir, GLT-1, and mGluR5 in murine astrocytes
No full textAstrocytes, a type of glial cell found within the central nervous system, are morphologically complex, and their processes are not well defined structurally or functionally. It is unknown how these processes accommodate regional demands. Small morphological and functional regions, that are highly specialized for homeostasis or synaptic signaling, may be located along the lengths of astrocyte processes. Previous research has begun to identify the distribution of proteins within astrocytes. In this study the processes, and the distribution of clusters of proteins or “puncta”, on seven previously imaged astrocytes, were analyzed using 3-D rendered surfaces generated in ImarisTM, a confocal analysis imaging software. The patterns for three proteins: mGluR5, a metabotropic glutamate receptor (n=30), GLT-1, a glutamate transporter (n=30), and Kir 4.1, an inward rectifying potassium channel (n=10) were examined along the lengths of individual processes. mGluR5 is a protein involved in synaptic signaling, and both GLT-1 and Kir 4.1 are considered more homeostatic. This study suggests that clustered regions of GLT-1 and Kir 4.1 are present within astrocytic processes, but that mGluR5 is more homogenously distributed, indicating that there may be subdomains for specialized functions within astrocytes.
* Indicates faculty mentor
Discovering antimicrobial properties from Ganoderma applanatum & Lentinula edodes
No full textThis project involves the exploration of antimicrobial effects for the fungi Ganoderma applanatum and Lentinula edodes against the Gram-negative bacteria, Pseudomonas aeruginosa. Under stress, the cell wall of this bacteria is stabilized by the polycationic amine spermidine. The synthesis of spermidine is regulated by the PA3553 and PA4774 genes, both of which are controlled by two distinct pathways. Previously prepared PA3553::lux and PA4774::lux mutant strains of P. aeruginosa, which were programmed to illuminate upon gene activation via cell wall damage, were used for this study. Gene expression (determined via luminescence) and growth (optical density) was recorded weekly on the Wallace Victor luminescence plate reader for eight weeks to determine the period of greatest cell wall damage by the fungi. Data suggested highest amount of damage at week four and week eight for G. applanatum and L. edodes, respectively. In comparison to the control, G. applanatum showed a 22 fold PA3553::lux induction and a five fold PA4774::lux induction at a 20%v/v concentration during week four. Similarly, on week eight of growth L. edodes induced the PA3553 pathway 116 times more than the control when it was added at a 20%v/v concentration. Additionally, the fungal supernatants were also treated with trypsin. Significant reduction in gene induction was observed for both species after the trypsin digestion, suggesting the role of peptides as potential antimicrobial agents in G. applanatum and L. edodes. Future experiments will involve supernatant fractionation via column chromatography, followed by more screenings with the mutants to specify the antimicrobial compounds.
* Indicates faculty mentor
The effects of heavy water on 8-Anilino-1-naphthalenesulfonic acid binding to bovine serum albumin
No full textThe binding of 8-Anilino-1-naphthalenesulfonic acid (ANS) to bovine serum albumin (BSA) is mediated by hydrophobic interactions. This interaction results from the entropically unfavorable structuring of water near hydrophobic surfaces. How this effect changes as regular light water (H2O) is substituted for heavy water (D2O) is largely unexplored. To investigate this question, we are examining the binding behavior of ANS with BSA in heavy and light water as measured by fluorescent spectroscopy. To date, we have observed that ANS quantum yield is increased in the presence of D2O versus H2O. Understanding this alteration in ANS binding in these solvents will improve our understanding regarding hydrophobicity and may have implications for improving protein stability.
* Indicates faculty mentor
Examining the effects of crowding on the pre-steady state and the steady state of α-chymotrypsin
No full textEnzymes catalyze many important chemical reactions in biological systems by lowering their activation energy. Studying how enzymes kinetics are affected by concentrated solute molecules and other environmental conditions is crucially important for furthering our understanding of how these bimolecular function in vivo. The cell is a crowded place where the concentration of protein and nucleic acid content is approximately 200-400 g/L (Ellis, 2001). In this project, we sought to study the changes in both pre-steady state and steady state kinetics of α-chymotrypsin as a function of crowding using solutes such as sucrose, betaine and polyethylene glycol (PEG). Examining the pre-steady state kinetics using stopped-flow methods enables us to observe of the effects of crowding on chymotrypsin’s acylation and deacylation steps. The pre-steady state is characterized by a “Burst” that has a different shape and rate than the steady state. We hypothesize that using sucrose or PEG will exhibit uncompetitive inhibition on Chymotrypsin kinetics. We also hypothesize that the Burst phase will have a different rate under crowding conditions. References Ellis, R. J. (2001). Macromolecular crowding: obvious but underappreciated. Trends Biochem. Sci. 26, 597–604.
* Indicates faculty mentor
Quantification of Escherichia Coli via Analysis of β-glucuronidase Enzyme Concentrations
No full textConcentration of Escherichia coli can be quantified based on a digestive enzyme produced by 97% of E. coli strains called β-glucuronidase (β-GUS). When in contact with a β-glucuronide (β-GLU) molecule, the enzyme cleaves the β-GLU segment off the molecule, leaving the remaining fragment untouched. The remaining fragment can serve as a marker for the presence of the enzyme and can be quantifiably calibrated to determine the concentration of the E. coli in each sample. For a colourimetric method approach, 4-nitrophenol-β-D-glucuronide (4-NβDg) can be used as a dye for the enzyme. The remainder of the molecule after enzymatic cleavage is a 4-nitrophenol, which is blue in colour. The change in colour can be quantified based on a calibration curve. For an electrochemical method approach, 4-NβDg can also be used because 4-nitrophenol gives a characteristic cyclic voltammogram on a potentiostat. The change in resistance of 4-nitrophenol can be determined and calibrated to show the concentration of the E. coli in each sample. This research is ongoing and does not have the finalized results on the outcome of the work described above.
Discipline: Chemistry
Faculty Mentor: Dr. Sam Mug
Music, Interpersonal Synchrony, and Social Affiliation
No full textResearch suggests that moving synchronously with others increases social affiliation as it blurs the boundary between “self” and “other” and allows group members to focus on a shared goal. In the real world, few synchronous movement behaviours are performed without the backdrop of a musical beat to support them (i.e., tribal rituals, soldiers marching, dancing during concerts). However, to our knowledge, only one previous study examined the role of music in the association between synchronous movement and social affiliation. To examine this question, we had participants watch a 3-minute dance video in groups of 3-4. They either mimicked the dance moves in the video (moving synchronously) or simply observed the movements while seated, and music was either present or absent. As such, there were four conditions: 1) move with music, 2) move without music, 3) observe with music, 4) observe without music. Participants then completed a series of questionnaires; our dependent measures focused on social affiliation (i.e., entitativity, inclusion of other in self, trustworthiness) and prosocial behaviours (i.e., helping). We hypothesize that 1) the movement groups will show greater social affiliation and prosocial behaviour than the observation groups, and 2) the group moving to music will show the strongest effect. If hypothesis 2) is supported, we suspect that it will result from an increased mood and/or a higher degree of synchronization compared to the other group(s). Because even simple synchronous movements (e.g., finger tapping) generate feelings of community and bonding, the addition of music may enhance or exaggerate this effect.
Discipline: Psychology Honours
Faculty Mentor: Dr. Kathleen Corrigall
 
Is Background Music Distracting?
No full textMany students listen to music while studying, but are these conditions optimal for cognitive performance? Previous research has revealed inconsistent findings because the effect depends on several factors (e.g., type of music, type of task, individual differences). The current study examined the effect of background music on reading comprehension, a task that is most similar to studying, to explore three questions: 1) Is music with lyrics more distracting than instrumental music? 2) Does the emotional valence of the music (e.g., happy, sad) contribute to distraction? and 3) Do individual differences in personality, working memory, and empathy influence distractibility? Although several studies have examined the effect of lyrics and extraversion, few have explored our other factors of interest. We first conducted a pilot study (N = 60) to select popular songs that were unambiguously happy or sad, and to select three reading comprehension tasks that were equally difficult. In the main experiment, each participant completed reading comprehension tasks in three conditions, 1) while listening to original pop songs with lyrics, 2) while listening to instrumental versions of different pop songs, and 3) while sitting in silence. Half of the participants listened to happy-sounding music in the music conditions, and half listened to sad-sounding music. Participants then completed self-report measures of personality, working memory, and empathy. We expect that individuals who are least distracted by background music will be those who 1) are high in extraversion, 2) are low in empathy, and 3) have high working memory capacities.
Discipline: Psychology Honours
Faculty Mentor: Dr. Kathleen Corrigal
Biomarkers as Sea Ice Tracers for the Western Canadian Arctic
No full textThis project aims to retrace the glacial evolution of the Western Canadian Arctic by quantifying biomarkers in sediment cores. Biomarkers serve as a proxy to derive the amount of sea ice from the sediment record. This project involves the delicate chemical extraction of ice cover biomarker IP-25 and ice free biomarker Brassicasterol to generate a ratio, PIP-25 (percent of IP-25 to Brassicasterol), approximating sea ice cover within a certain time period. This groundbreaking research is the first of its kind in the Canadian Arctic, and the sediment core recovered this past August is the first ever from the region (M\u27Clure Strait). MacEwan University has exclusive access to this sediment core. This project is important to international research, as the M\u27Clure Strait has never been examined geologically. This research can elucidate the ice sheet development of the region, which connects the Arctic Ocean with the Atlantic through the Northwest Passage, crucial to oceanography research.
Discipline: Earth and Planetary Sciences
Faculty Mentor: Dr. Mark Furz
Characterization of neuron development in GDF11 zebrafish mutants
No full textThe zebrafish (Danio rerio) has become an excellent model organism for studying vertebrate development and disease. More than 1000 zebrafish mutants have been identified, where changes in specific genes have correlated with human defects. Many of these mutations occur in genes with orthologues in humans, leading to the creation of animal models that resemble human disease types. Examples of this are demonstrated by mutations seen in bone morphogenetic protein (BMP) family members in both humans and zebrafish. This project investigated whether mutations in the BMP growth differentiation factor 11 (GDF11) gene result in deficits during zebrafish neuron development. Neuronal development was characterized using in situ hybridization and immunofluorescence techniques. Changes in neuronal development were examined using probes recognizing neurons, including RMO44 and acetylated tubulin. Experimental results from this preliminary characterization contribute to the on-going characterization of phenotypes seen in GDF11 mutants.
Discipline: Biology
Faculty Mentor: Dr. Lisa Prichar