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Action strategies of young adults during an attentionally demanding collision avoidance task in virtual reality
No full textWalking and navigating through cluttered environments is a task that people do almost automatically while completing multiple cognitive and motor tasks simultaneously. Vision plays an essential role in adaptive locomotion as it allows individuals to make anticipatory actions (i.e., alter trajectory and/or gait speed) to successfully avoid oncoming collisions (Cinelli et al., 2008; Patla, 1997). To initiate a behaviour change at the appropriate time, humans rely on optical variables such as time-to-contact (TTC) (Cinelli & Patla, 2007). After determining when to initiate an avoidance behaviour, it is thought that humans maintain a protective zone (i.e., safety margin) by controlling the minimum clearance distance between them and an approaching obstacle or person (Gérin-Lajoie et al., 2005). Although it has been demonstrated that there are significant cognitive demands to performing various locomotor tasks, more research is required to fully understand the effects of complex tasks (similar to everyday life) on human collision avoidance behaviours. As such, the purpose of this thesis was to examine the action strategies employed by young adults (with and without athletic training) while avoiding a virtual pedestrian (VP) approaching on a 45º under attentionally demanding conditions. Avoidance behaviours of young adults from the general student population were observed to gain a fundamental understanding of young adults’ collision avoidance behaviours during a complex task (Study 1). Then, using the same paradigm, young adults from the general student population (controls) were compared to collision sport athletes to examine whether sport-specific training influences one’s collision avoidance strategies (Study 2). Controls (N=21, 22.9±1.9 yrs, 11 males) and specifically trained athletes (N=18, 20±1.5 yrs, 7 males) were immersed in a virtual environment using the HTC VIVE Pro2 headset and were instructed to walk along a 7.5m path towards a goal located along the midline. Two virtual pedestrians (VP) positioned 2.83m to the left and right of the midline approached participants on a 45º angle at one of three speeds, 0.8x, 1.0x, and 1.2x each participants\u27 average walking speed. Participants were instructed to walk to a goal without colliding with the VP. Participants performed a secondary task, where they reported whether a shape changed above the VPs\u27 heads. Using the position of the VP and the participant, avoidance behaviours of time to first avoidance behaviour and minimum clearance were examined. Further, the percentage of correct responses on the secondary task were recorded. Results from both studies revealed that young adults (regardless of training) did not modulate their time of avoidance to the VP approach characteristics (i.e., avoided at the same time regardless of condition), however, both groups controlled minimum clearance to maintain a consistent margin of safety after a behaviour was initiated. Interestingly, it was found that sport-specific training did not influence minimum clearance, suggesting that training does not impact one’s personal space. Despite having similar action strategies, athletes were more variable in their behaviours and performed significantly better on the secondary task which suggests that athletes may be more adaptive and may perform better on attention tasks compared to controls. Similarities in the avoidance behaviours between the two groups may be a result of the task lacking sport-specificity or due to the predictability of the task
Collision avoidance strategies of middle-aged children and young adults in a virtual environment
No full textThe ability to perceive and react to visual information is critical for avoiding a collision with an approaching obstacle. The perception-action system undergoes a prolonged period of development and as a result, children make more last-minute locomotor adjustments than adults when avoiding stationary obstacles. The purpose of this thesis was to compare the avoidance behaviours of middle-aged children (10-12 years old) to young adults (YA) during a head-on collision course with an approaching virtual pedestrian (VP). Children (N=16, 10.8 0.75 years; 8 males) and YA (N=16, 22.94 2.08 years; 7 males) were immersed in a virtual environment using the HTC Vive Pro 2 head-mounted display. Participants were instructed to walk along an 8m pathway, towards a goal, while avoiding a collision with a VP who approached at one of three speeds: 0.8x, 1.0x, or 1.2x the participant’s average walking speed. During each trial, the VP would approach along the midline and steer to the left, right, or continue walking straight. Results revealed a significant difference in the onset of deviation between groups, with children (1.65 ± 0.17s) deviating later than YA (1.52 ± 0.10s). Additionally, children were more variable in their onset of deviation and time-to-contact. Findings from this study demonstrate children have similar avoidance behaviours to YA, as both groups successfully used perceptual information to determine how to avoid a collision. However, children had a later onset of deviation and greater variability in their avoidance behaviours than adults. These results suggest that although middle-aged children are able to successfully avoid collisions, they employ different avoidance strategies than adults. Therefore, by 10-12 years of age, children appear to not have fully developed adult-like perceptual-motor skills
Functional Residues of CjpatA
Get PDFAntibiotic resistance in pathogenic bacteria continues to challenge clinicians and threaten the lives of infected individuals. For this reason, new classes of antibiotics or new targets for antibiotic therapy are needed to circumvent this global health crisis. In Gram-negative bacteria, the enzymes peptidoglycan O-acetyltransferase A and B (PatA and PatB), are responsible for adding acetyl groups to the C-6 hydroxyl group of N-acetyl muramic acid (MurNAc) in peptidoglycan (PG). These acetyl groups are responsible for inhibiting the activity of lysozyme from host organisms that hydrolyze the β1-4 glycosidic linkage between MurNAc and N-acetylglucosamine (GlcNAc). The acetyl groups also regulate the rate of autolysis by precluding the activity of lytic transglycosylases, that contribute to this process. PatB from several sources has been experimentally characterized, but PatA still lacks the same amount of characterization due to difficulties with its expression and purification. Here, initial attempts to express and purify Proteus mirabilis and Campylobacter jejuni PatA are presented. Efforts to characterize functional residues of CjPatA were made by utilizing in situ assays developed to compare the resistance to lysozyme and the rates of autolysis in nutrient-deprived environments of C. jejuni strains with patA mutations. Point mutations to CjpatA were engineered for the site-specific replacements of S122, R164, H275, R283, and H315 to test the significance of these proposed catalytic residues. A preliminary application of this autolysis assay, suggested S122, H275, R283, and H315 do act as functional residues because their populations did not decrease as much as their progenitor strain, an oap operon knockout with a patA and patB complementation. O-acetylation data from the respective strains could not be generated to verify these findings
One Day I Will Destroy This Place
Get PDFMy personal narrative reveals the complex and often ineffable journey that I experience from academia to home and from home to academia. I speak to the different modes of walking that such a journey necessitates: walking back home, into a sea of whiteness, and out of academia. As I make my way from Toronto to Montréal, from my residence in academia to where I call home, I carry with me the cruel optimism of education, weighing down the steps that I take, I attempt to grapple with spatial negotiations. It often feels like an arduous and never-ending passage. Still, my back-and-forth travel from the interior of academic life to the place I call home brings me to a significant provocation: the geography of driftwork
Surrender No. 40
Get PDFIn June 2016, I made an improvised pilgrimage on foot through the Haldimand Tract in southwestern Ontario, the territory deeded to the Haudensaunee in 1784 and mostly stolen back by settlers since then. I grew up in Brantford, a city in the Haldimand Tract, ignorant of the history of the area. When I learned about that history, I decided to walk through the Tract as a way of understanding, physically, the scale of the land theft that had occurred, a theft that, as a settler, I had benefitted from. “Surrender No. 40” is an account of that pilgrimage
Reflections From a Maternity Leave: The Complex History of Beaver Dam Flats and Refinery Park
Get PDFA personal essay reflecting on my relationship with Refinery Park and Beaver Dam Flats in light of its complex history
Review of Civilians at the Sharp End: First Canadian Army Civil Affairs in Northwest Europe by David A. Borys
Get PDFReview of Civilians at the Sharp End: First Canadian Army Civil Affairs in Northwest Europe by David A. Bory
Navigating Waters: Experiences of Filipino Canadian Identity Making in the Diaspora
Get PDFResearch states that while Filipino Canadians are the largest growing migrant population in Canada, they are the least represented and understudied subjects in the academy. The primary purpose of this qualitative study is to better understand the experiences of Filipino Canadians and how they create their identities in the diaspora. Since few studies take on a social work lens to explore these important stories, I attempt to unearth these experiences using these guiding questions: (1) How do Filipino Canadians integrate their cultural identity in the diaspora? (2) What are the sociopolitical and historical conditions that inform these identities? Following Charmaz’s Constructivist Grounded Theory, data were generated from ten (10) Filipino Canadians across Vancouver, British Columbia and analyzed using codes, categories and turning them into themes. Six themes were found. Findings indicate that Filipino Canadians yearn to construct, deconstruct, and reconstructing identities that bring them back to their cultural and ancestral roots. Implications for social work practice and lessons are discussed
Exploring Graduated Court Diversion Clients\u27 Experience of Psychotherapy in Their Community Reintegration
Get PDFCourt Diversion Program (CDP) seeks to reduce the criminalization and reoffending among people living with mental illness to ensure their community reintegration (Schneider, 2010). The complex nature of achieving this goal calls for a comprehensive strategy, which requires a collaborative effort of legal, health care, and allied professionals including psychotherapists. However, because most CDP clients frequently receive medication treatment, not much is known about how CDP clients find psychotherapy services even though psychotherapy is effective for addressing mental illnesses and offending behaviors (Feingold & Fox, 2018; Feucht & Holt, 2016), To gain more insight into the issue, this study applied the postmodern framework and adopted a comparative case study design to explore the experiences of 5 CDP clients who received psychotherapy as part of their treatment with other 5 CDP clients who received pharmacotherapy treatment. Specifically, this research investigated why the clients chose their preferred treatment, how they experienced their participation in this form of treatment, and the role their treatment modality played in their community reintegration after encountering the criminal justice system. The researcher used qualitative interview techniques to collect data from the 10 participants who were living in the City of Toronto. Data were analyzed for patterns that revealed group differences in the experience and outcomes of these treatments
Review of War Memories: Commemoration, Recollections and Writings on War edited by Stephanie A.H. Bélanger and Renée Dickason
Get PDFReview of War Memories: Commemoration, Recollections and Writings on War edited by Stephanie A.H. Bélanger and Renée Dickaso