Collison avoidance with another individual: the influence of person-specific characteristics

Collision avoidance during locomotion is an important skill that people must master to successfully navigate through dynamically changing environments. Environments are cluttered with objects that are either goals (attraction points) or obstacles (repulsion points), such that locomotion must be guided towards goals and away from obstacles. While navigating towards a goal, individuals maintain an elliptically shaped ‘personal space’ between their own body and that of the obstacle(s). The size of personal space (degree of repulsion) is modulated depending on the specific situation. Collision avoidance research has typically utilized inanimate objects such as poles, however recent findings suggest that the amount of personal space required with inanimate objects is distinct from that used to avoid another person. Historically, person-to-person collision avoidance research has examined avoidance behaviours during different situation-specific scenarios, such as mutual or joint-task avoidance, passing through apertures, and interacting on various angles. Person-person research has not, however, fully taken person-specific characteristics into consideration as factors that may contribute to different avoidance behaviours. It is unknown whether humans perceive all humans the same way or if certain external-characteristics (i.e., one’s perception of others) dictate how collisions are strategically avoided with another human. Furthermore, it is unknown if behaviours are robust across all individuals or if there are certain internal-characteristics (i.e., one’s perception of self) that influence collision avoidance behaviours. The overarching goal of my PhD was to identify the person-specific characteristics that mediate changes in avoidance behaviours, in a young adult population. To address this, five collision avoidance studies were conducted in the real world or virtual reality. The first study (conducted at Wilfrid Laurier University) examined collision avoidance behaviours when circumventing two physically different sized individuals. Results from Study 1 revealed that individuals circumvent people with a larger body size with more space at the time of crossing from the center of mass compared to a person with a smaller body size. The second study (conducted at Wilfrid Laurier University) was a follow-up focused on avoidance behaviours when circumventing an individual whose body size was artificially increased using shoulder pads. Study 2 demonstrated that when an artificial extension (shoulder pads) is added to a stationary person, avoidance behaviours are unchanged. Instead, results determined a side-bias where clearance was smaller for left-side avoidance. The third study (conducted at University Rennes II, FR), focused on determining the influence of a virtual human’s age-related (older vs younger) appearance and gait characteristics on collision avoidance strategies. Study 3 found that young adults circumvent with a larger clearance when interacting with a virtual pedestrian who possesses older adult-like characteristics. Study 4 (conducted at Université Laval) determined differences in the avoidance and gaze behaviours of athletes and non-athletes during an avoidance task with a virtual pedestrian who unpredictably steered to a new direction. Avoidance and gaze behaviours were different between athletes and non-athletes during early planning, but similar during late planning. Unpredictable steering behaviours of an approaching pedestrian led to a larger clearance at the time of crossing. Study 5 (conducted at Wilfrid Laurier University) was aimed at determining if an acute nociceptive stimulus (via topical capsaicin cream) alters avoidance behaviours. Cutaneous discomfort on the lateral aspect of the arm did not alter young adults’ avoidance behaviours. However, a learning effect was observed as avoidance was different during the first trial. Together, these studies suggest that additional perceptual factors are considered when avoiding collisions with other people. The results of this dissertation demonstrate that during obstacle avoidance tasks, one’s personal space is influenced by, 1) the external-characteristics of an opposing pedestrian, and 2) the internal-characteristics of oneself. Understanding the typical behaviours for circumventing pedestrians and knowing how specific external- and internal-factors influence personal space provides the necessary groundwork for understanding how these behaviours are altered with age or disease. Furthermore, this work provides valuable information about human inter-personal distances (i.e., proxemics), which may be applicable to re-designing the simulation models of interactions between pedestrians used by engineers to expand crowd simulations, to develop architectural plans for urban centers, design robots to safely navigate unfamiliar environments, or properly plan exit routes in buildings

143 Wing (RCAF) Typhoons Over Normandy: Some Operational, Geographical and Archaeological Perspectives

This article presents the first attempt to conduct a geographical analysis of every air-to-ground attack conducted by a tactical fighter-bomber wing over the period 1 May–31 August 1944 in support of Operation Overlord. Ninety-five per cent of the 606 attacks made by 143 Wing Typhoons on single or multiple targets can be resolved to a map reference or place name, and their chronology and distribution reveal new insights into the Wing’s operational history. Commemorative and heritage perspectives are also highlighted for attacks on targets in woodland settings where archaeological survey of bomb craters can be linked to specific raids

Synthesis and Biophysical Analysis of Modified Cell-Penetrating Peptides

Cell-penetrating peptides (CPPs) are a family of peptides that have the ability to penetrate biological membranes. They were discovered in the late 1980s and have been the topic of many studies. Much of the interest in CPPs has been due to their ability to translocate biological membranes, and the possibility that they could offer a novel drug delivery method by conjugation to biologically active molecules. Linear CPPs can be modified to form cyclic structures. This change in structure has been observed to enhance the stability and penetrative ability of the CPPs which have been studied. The current thesis focuses on the biophysical properties of CPPs modified to allow for cyclization. Penetratin (primary sequence: RQIKIWFQNRRMKWKK) and the Tat peptide (primary sequence: YGRKKRRQRRR) are two examples of linear CPPs that interact with and translocate across biological membranes. Fmoc based solid-phase peptide synthesis (SPPS) was used to synthesize cyclizable analogs of these two peptides by adding glycine and cysteine residues to the peptides’ termini. Reversed-phase high performance liquid chromatography (RP-HPLC) was used to purify and analyze the homogeneity of the protected linear analogs of the Tat peptide and penetratin (pTatL and pPenL, respectively). Fluorescence emission spectroscopy and circular dichroism (CD) spectroscopy were used to observe the conformational differences between the cyclizable analogs, and their original peptide constructs in different (aqueous, organic solvent and lipidic) environments. Dithiothreitol was required to measure the fluorescence and CD spectra of the peptides in the presence of lipid vesicles, to prevent the precipitation which might occur in the absence of the reducing agent. The CD and fluorescence spectra of pPenL were similar to the previously reported spectra of the native penetratin peptide; it displayed an unordered conformation in aqueous environments and α-helical conformations in organic solvents hexafluoroisopropanol and lipidic phosphatidylcholine/phosphatidylglycerol and phosphatidylethanolamine/phosphatidylglycerol (PC/PG and PE/PG) environments. The Tat peptide has been reported to maintain an unordered secondary structure in all environments and when conjugated to biologically active molecules. The spectra of pTatL in aqueous buffer agreed with the previous reports, but the spectra in HFIP displayed partial α-helical conformations, likely due to the modifications made to the sequence to enable cyclization

Self-Exciting Point Processes in Real Estate

This thesis introduces a novel approach to analyzing residential property sales through the lens of stochastic processes by employing point processes. Herein, property sales are treated as point patterns, using self-exciting point process models and a variety of statistical tools to uncover underlying patterns in the data. Key findings include the identification and explanation of clustering in both space and time, and the efficacy of a temporal Hawkes process with a sinusoidal background in predicting home sale occurrences. The temporal analysis starts by employing the state of art techniques for time series data like regression, autoregressive, and autoregressive integrated moving average (ARIMA) models, extending into more sophisticated point process models with self-excitation features. Spatial analysis delves into clustering and dispersion patterns within specific geographic boundaries, utilizing homogeneous and inhomogeneous processes with covariate analysis to describe these patterns. Further, the spatiotemporal exploration sets a precedent for future comprehensive models in this domain. This exploratory research establishes a foundation for further investigation into the dynamic field of real estate analytics under the framework of point processes

Exploring Cultural, Health, and Technology Intersections: A Focus on Migrant Experiences

Despite the plethora of theories and frameworks addressing culture, health, and technology adoption, there remains a notable absence of a unifying theory that comprehensively encompasses all three aspects, particularly concerning newcomers. The Health Belief Model, for example, underscores individual perceptions and attitudes toward health yet fails to consider the intricate interplay between cultural factors and technology adoption among immigrant populations. The Healthy Immigrant Effect, which posits that immigrants often exhibit better health outcomes than native-born individuals, does not mention the role of technology on health outcomes. Acculturation theories, while shedding light on the adaptation process, often fall short of explaining how cultural nuances shape health behaviors and the embrace of technological advancements. The Technology Adoption Model, primarily developed in Western contexts, may not adequately capture the unique cultural considerations influencing immigrants\u27 engagement with health-related technologies. Other models, though insightful, face the same shortcomings. Hence, there is a compelling need for a comprehensive and culturally sensitive framework that offers a more holistic understanding of the intersection of culture, health, and technology adoption for newcomers and immigrants

World Class Supply Chain 2024: Thriving in Volatile Times

The Eighth Annual World Class Supply Chain Summit was convened on May 1st, 2024 under the theme of Thriving in volatile times. The theme, which embodies the expressed interests of attendees in last year’s post-summit survey, underscored the supply chain community’s focus on how to succeed in a supply chain world that is volatile, uncertain, complex, and ambiguous (VUCA). The summit’s deliberations on the theme featured two keynote addresses (one each by an industry executive and a research scholar), an industry panel, a student panel, and an intergenerational fireside chat by a panel comprising individuals with experiences ranging from a few months of internships through to several decades in the supply chain field. In these deliberations, a pervasive message was that supply chain professionals must accept that VUCA is a more likely future reality than the normalcy that might have existed in the past. Therefore, VUCA must be embraced as an opportunity for success instead of a reason for despair. In addition to this central message, attendees reported gaining valuable insights on: (i) Sustainability (ii) Operational agility (iii) Equity, diversity, inclusivity (EDI) (iv) Ongoing professional development (v) Best practices from various industries (vi) Youth engagement, talent acquisition, and retention (vii) The role of clean energy in SCM and logistics management The audience’s diversity fueled rich and multifaceted dialogue with the speakers to probe the insights listed above. Figure 1 below portrays the diversity: attendees represented organizations that make, sell, and move the supply chain’s products (manufacturers, retailers, transportation companies, warehouses, etc.) and organizations that support supply chains with services such as education and consulting

The Atiyah-Hitchin-Singer Theorem and an 8-dimensional generalization

The Atiyah-Hitchin-Singer theorem states that the twistor almost complex structure on a certain S2 bundle over an oriented Riemannian 4-manifold (M, g) is integrable if and only if the Weyl curvature tensor of g is self-dual. These ideas were developed by Roger Penrose connecting 4-dimensional Riemannian geometry with complex geometry. We present a new approach to the Atiyah-Hitchin-Singer theorem using horizontal lifts and their respective flows, cross products and the quaternions to show that the Nijenhuis tensor vanishes if and only if the Weyl curvature tensor of g is anti-self-dual. An eight dimensional generalization is presented when the manifold is R8