An athletic approach to studying perception-action integration: Does sport-specific training, and the impact of injury, influence how individuals visually guide navigation?

The objective of this thesis was to investigate perception-action integration capabilities of individuals during a choice navigation task. This task assessed navigation strategies in open space while individuals avoided colliding with two vertical obstacles that created a body-scaled, horizontal gap, at three varying obstacle distances from the starting location (3m, 5m, 7m). The two studies completed in this thesis employed the same paradigm to assess the hypothesized group differences. Gaze behaviours and kinematics of navigation strategies were compared between: 1) athletes specifically trained in navigating in open space versus non-athletes; and 2) athletes with post-concussion syndrome (PCS) versus non-concussed, specifically trained athletes. Specifically trained athletes have been identified as demonstrating more successful perception-action integration in discrete motor tasks related to their sport (Mann et al., 2007; Vickers, 2007). However, whether these abilities translate to the continuous motor task of obstacle avoidance in open space was unknown. The purpose of Study 1 was to identify the influence of sport-specific training on navigating in open space (i.e. navigational strategies of large field sport athletes) compared to age-matched, non-athletes. It was hypothesized that specifically-trained athletes would demonstrate fewer, longer fixations, suggesting a more successful perception-action integration strategy (as defined by Mann et al., 2007), and would employ more sport-specific navigation strategies than non-athletes by maintaining their straight trajectory toward the goal (Fajen & Warren, 2003). Athletes were found to make fewer, longer fixations than non-athletes. However, no differences were observed between navigation strategies of the two groups, nor were any kinematic measures found to differ between groups. It can be concluded that athletes and non-athletes differentially obtain visual information to perform the same actions, suggesting that athletes and non-athletes differentially perform perception-action integration when navigating in open space. Future studies are required to identify sport-specific nuances of navigation (moving obstacles, running) to better identify athletic-related navigation strategies. Although athletic training can enhance perception-action integration strategies, sport-related injuries can hinder this process. Following a concussion, individuals experience deficits of perception-action integration that persist well beyond 30 days of recovery, post-concussion (Baker and Cinelli, 2014; Slobounov et al., 2006). These perception-action integration deficits may also exist in individual with postconcussion syndrome (PCS). The purpose of the Study 2 was to identify whether perception-action integration deficits persist with the persistent physical symptoms of concussion characteristic of PCS. The current study revealed that athletes with PCS did not differ from non-concussed athletes on any measure of visual fixation strategy, nor were they found to differ on any kinematic measure assessed. These findings suggest that in the context of the current paradigm, athletes with PCS have no perception-action integration deficit. In that, athletes with PCS may have adapted perception-action integration strategies to navigate with equal efficiency as a specifically-trained group of athletes or that the paradigm was not sensitive enough to identify these differences. Such findings suggest that more research is required to assess what, if any, perception-action integration deficits persist with persisting physical symptoms of PCS to better benefit rehabilitative procedures and outcomes for these individuals. Together, these studies add to what was previously known about perception-action integration, as it relates to navigation. Both studies assessed perception-action integration in unique populations that add to understanding of behavioural dynamics in the sport setting. Study 1 builds on a line of research assessing affordance theory and behavioural dynamics in sport (Fajen, Riley, & Turvey, 2008). The findings of this study suggest that although navigation strategies did not differ between specifically trained athletes and non-athletes, visual search strategies employed in task did. Such findings add to the understanding that sport-specific training influences perception-action integration, through our understanding of how athletes obtain visual information to perform actions. This thesis did not identify perception-action integration deficits in athletes with PCS. These findings suggest that the individuals in the present study likely adapted to their injury as they demonstrated equal ability in gaze and navigation strategies to specifically-trained athletes. As such, further research is required to assess the cognitive, motor, and sensory-motor deficits that may persist with the persisting physical symptoms of PCS. As individuals with PCS do not demonstrate similar visuomotor integration deficits as individuals with acute concussions (Baker & Cinelli, 2014), such individuals must be assessed and researched as a separate population

Photovoltaic array: Power conditioner interface characteristics

The electrical output (power, current, and voltage) of flat plate solar arrays changes constantly, due primarily to changes in cell temperature and irradiance level. As a result, array loads such as dc-to-ac power conditioners must be capable of accommodating widely varying input levels while maintaining operation at or near the maximum power point of the array. The array operating characteristics and extreme output limits necessary for the systematic design of array load interfaces under a wide variety of climatic conditions are studied. A number of interface parameters are examined, including optimum operating voltage, voltage energy, maximum power and current limits, and maximum open circuit voltage. The effect of array degradation and I-V curve fill factor or the array power conditioner interface is also discussed. Results are presented as normalized ratios of power conditioner parameters to array parameters, making the results universally applicable to a wide variety of system sizes, sites, and operating modes

zCap: a zero configuration adaptive paging and mobility management mechanism

Today, cellular networks rely on fixed collections of cells (tracking areas) for user equipment localisation. Locating users within these areas involves broadcast search (paging), which consumes radio bandwidth but reduces the user equipment signalling required for mobility management. Tracking areas are today manually configured, hard to adapt to local mobility and influence the load on several key resources in the network. We propose a decentralised and self-adaptive approach to mobility management based on a probabilistic model of local mobility. By estimating the parameters of this model from observations of user mobility collected online, we obtain a dynamic model from which we construct local neighbourhoods of cells where we are most likely to locate user equipment. We propose to replace the static tracking areas of current systems with neighbourhoods local to each cell. The model is also used to derive a multi-phase paging scheme, where the division of neighbourhood cells into consecutive phases balances response times and paging cost. The complete mechanism requires no manual tracking area configuration and performs localisation efficiently in terms of signalling and response times. Detailed simulations show that significant potential gains in localisation effi- ciency are possible while eliminating manual configuration of mobility management parameters. Variants of the proposal can be implemented within current (LTE) standards

A survey on pseudonym changing strategies for Vehicular Ad-Hoc Networks

The initial phase of the deployment of Vehicular Ad-Hoc Networks (VANETs) has begun and many research challenges still need to be addressed. Location privacy continues to be in the top of these challenges. Indeed, both of academia and industry agreed to apply the pseudonym changing approach as a solution to protect the location privacy of VANETs'users. However, due to the pseudonyms linking attack, a simple changing of pseudonym shown to be inefficient to provide the required protection. For this reason, many pseudonym changing strategies have been suggested to provide an effective pseudonym changing. Unfortunately, the development of an effective pseudonym changing strategy for VANETs is still an open issue. In this paper, we present a comprehensive survey and classification of pseudonym changing strategies. We then discuss and compare them with respect to some relevant criteria. Finally, we highlight some current researches, and open issues and give some future directions

Triggering at High Luminosity Colliders

This article discusses the techniques used to select online promising events at high energy and high luminosity colliders. After a brief introduction, explaining some general aspects of triggering, the more specific implementation options for well established machines like the Tevatron and Large Hadron Collider are presented. An outlook on what difficulties need to be met is given when designing trigger systems at the Super Large Hadron Collider, or at the International Linear ColliderComment: Accepted for publication in New Journal of Physic

A Fault-Tolerant Scheme for Mobility Management in PCS Networks

[[abstract]]One of the most important and challenging issues in the design of personal communication service (PCS) systems is the management of location information. In this paper, we propose a new fault-tolerant location management scheme, which is based on the cellular quorum system. Due to quorum's salient set property, our scheme can tolerate the failures of one or more location server(s) without adding or changing the hardware of the systems in the two-tier networks. Meanwhile, with a region-based approach, our scheme stores/retrieves the MH location information in the location servers of a quorum set of the local region as much as possible to avoid long delays caused by the possible long-distance of VLR and HLR. Thus, it yields better connection establishment and update delay.

Human Resource Information Systems for Competitive Advantage: Interviews with Ten Leaders

[Excerpt] Increasingly, today\u27s organizations use computer technology to manage human resources (HR). Surveys confirm this trend (Richards-Carpenter, 1989; Grossman and Magnus, 1988; Human Resource Systems Professionals 1988; KPMGPeat Marwick, 1988). HR professionals and managers routinely have Personnel Computers (PCs) or computer terminals on their desks or in their departments. HR computer applications, once confined to payroll and benefit domains, now encompass incentive compensation, staffing, succession planning, and training. Five years ago, we had but a handful of PC-based software applications for HR management. Today, we find a burgeoning market of products spanning a broad spectrum of price, sophistication, and quality (Personnel Journal, 1990). Top universities now consider computer literacy a basic requirement for students of HR, and many consulting firms and universities offer classes designed to help seasoned HR professionals use computers in their work (Boudreau, 1990). Changes in computer technology offer expanding potential for HR management (Business Week, 1990; Laudon and Laudon, 1988)