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Latency of Saccades during Smooth Pursuit Eye Movement in Man : directional asymmetries. / ヒト滑動性眼球運動の最中の視覚誘導性サッカードの潜時変化Tanaka, Masaki 25 March 1998 (has links)
共著者あり。共著者名:Yoshida Toshikazu, Fukushima Kikuro. / Hokkaido University (北海道大学) / 博士 / 医学
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The use of extraretinal information to compensate for self-movementBlohm, Gunnar 19 October 2004 (has links)
It is essential for the brain to keep track of self-movement in order to establish a stable percept of the environment. The major source of information about self-movement is vision. However, non visual (extraretinal) information can also contribute to the sense of motion. This thesis investigated the role of extraretinal signals to account for self-generated motion in the case of eye movements. The interaction of two types of eye movements, i.e. smooth pursuit and saccades, was used to investigate the system's capacity to keep track of self-motion. This work focused in particular on the ability of the saccadic system to account for smooth pursuit eye movements in darkness. A detailed analysis of the saccade metrics allowed the identification of a novel neural mechanism for smooth eye movement integration. As a result, the saccadic system could compensate for smooth eye displacements and thus was able to ensure space constancy across different eye movements. In addition to the experimental approach of this thesis, a mathematical model was developed that described all current findings.
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An Exploration of the Relationships Among Individual and Interpersonal Goal Pursuit and Hedonic and Eudaimonic Well-beingProcacci, Erin Nicole 30 September 2008 (has links)
Studies in the areas of goal pursuit and well-being suggest that the goals people work toward in their daily lives are important contributors of well-being. However, research to date has focused primarily on aspects of the individual in goal pursuit even though goals are not pursued in isolation. In fact, there is evidence that this emphasis on the individual, particularly salient in Western cultures, has negative consequences at both the individual and community levels. With regard to well-being, data have indicated that it is best represented as two dimensional, including hedonic and eudaimonic well-being. However, the research on personal goals has primarily focused on hedonic well-being of the individual. Overall, hedonic well-being appears to be more related to affective experience, whereas eudaimonic well-being appears to be more comprehensive and related to topics like purpose in life, self-acceptance, and positive relations with others. The theoretical framework of Virtue Ethics posits that social affiliations are essential for human beings to flourish and experience eudaimonia, and this study examines that premise. A two-step approach to structural equation modeling was used to contribute to the extant literature on goal pursuit and well-being by 1) exploring the individual and interpersonal dimensions of goal pursuit and their relationships to hedonic and eudaimonic well-being and 2) exploring the interpersonal dimensions of goal pursuit as a mediator of the relationship between individual dimensions of goal pursuit and eudaimonic well-being. The retained structural model from the two-step approach included Efficacy (an Individual Dimension of Goal Pursuit) and Generativity (an Interpersonal Dimension of Goal Pursuit). Results demonstrated that Efficacy and Generativity were both significantly related to Hedonic and Eudaimonic Well-being; however, Generativity was more strongly related to Eudaimonic than Hedonic Well-being. These findings were consistent with the premise of Virtue theory, that those engaged in goal pursuit with or on behalf of others are more likely to experience higher levels of eudaimonic well-being. Future research should include further exploration of the Interpersonal Dimensions of Goal Pursuit and well-being specifically by focusing on improving measurement for the Interpersonal Dimensions of Goal Pursuit, Hedonic, and Eudaimonic Well-being. Read more
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The use of extraretinal information to compensate for self-movementBlohm, Gunnar 19 October 2004 (has links)
It is essential for the brain to keep track of self-movement in order to establish a stable percept of the environment. The major source of information about self-movement is vision. However, non visual (extraretinal) information can also contribute to the sense of motion. This thesis investigated the role of extraretinal signals to account for self-generated motion in the case of eye movements. The interaction of two types of eye movements, i.e. smooth pursuit and saccades, was used to investigate the system's capacity to keep track of self-motion. This work focused in particular on the ability of the saccadic system to account for smooth pursuit eye movements in darkness. A detailed analysis of the saccade metrics allowed the identification of a novel neural mechanism for smooth eye movement integration. As a result, the saccadic system could compensate for smooth eye displacements and thus was able to ensure space constancy across different eye movements. In addition to the experimental approach of this thesis, a mathematical model was developed that described all current findings.
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Roadmap-Based Techniques for Modeling Group Behaviors in Multi-Agent SystemsRodriguez, Samuel Oscar 2012 May 1900 (has links)
Simulating large numbers of agents, performing complex behaviors in realistic environments is a difficult problem with applications in robotics, computer graphics and animation. A multi-agent system can be a useful tool for studying a range of situations in simulation in order to plan and train for actual events. Systems supporting such simulations can be used to study and train for emergency or disaster scenarios including search and rescue, civilian crowd control, evacuation of a building, and many other training situations.
This work describes our approach to multi-agent systems which integrates a roadmap-based approach with agent-based systems for groups of agents performing a wide range of behaviors. The system that we have developed is highly customizable and allows us to study a variety of behaviors and scenarios. The system is tunable in the kinds of agents that can exist and parameters that describe the agents. The agents can have any number of behaviors which dictate how they react throughout a simulation. Aspects that are unique to our approach to multi-agent group behavior are the environmental encoding that the agents use when navigating and the extensive usage of the roadmap in our behavioral framework. Our roadmap-based approach can be utilized to encode both basic and very complex environments which include multi- level buildings, terrains and stadiums.
In this work, we develop techniques to improve the simulation of multi-agent systems. The movement strategies we have developed can be used to validate agent movement in a simulated environment and evaluate building designs by varying portions of the environment to see the effect on pedestrian flow. The strategies we develop for searching and tracking improve the ability of agents within our roadmap-based framework to clear areas and track agents in realistic environments.
The application focus of this work is on pursuit-evasion and evacuation planning. In pursuit-evasion, one group of agents, the pursuers, attempts to find and capture another set of agents, the evaders. The evaders have a goal of avoiding the pursuers. In evacuation planning, the evacuating agents attempt to find valid paths through potentially complex environments to a safe goal location determined by their environmental knowledge. Another group of agents, the directors may attempt to guide the evacuating agents. These applications require the behaviors created to be tunable to a range of scenarios so they can reflect real-world reactions by agents. They also potentially require interaction and coordination between agents in order to improve the realism of the scenario being studied. These applications illustrate the scalability of our system in terms of the number of agents that can be supported, the kinds of realistic environments that can be handled, and behaviors that can be simulated. Read more
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The Role of Goal Congruence in Relationship Quality and Subjective Well-beingGere, Judith 11 December 2012 (has links)
The goal of this dissertation was to examine how people pursue their personal goals in the context of an intimate relationship. Two studies were conducted; a daily diary study of dating partners’ joint activities and a longitudinal study of newly dating couples. In the daily diary study, people reported on their daily joint activities with their dating partners regarding whether their goals were met and how they were feeling during the given activity. The results showed that when people’s goals were met in an activity, their partners were able to accurately perceive that their goals were being met. However, when their goals were not met in the activity, their partners’ accuracy regarding their goals was only at chance levels. The partners’ overall levels of goal congruence did not predict the proportion of goal-congruent activities the partners participated in. However, the partners’ level of goal congruence predicted increases in life satisfaction, relationship commitment, and relationship satisfaction, as well as decreases in negative affect over time. In the longitudinal study, newly dating couples filled out measures of their goals, well-being, and relationship quality during their initial session. Three months later, the couples filled out measures of these same constructs again and answered questions about the goals that they reported pursuing during their initial session. Results showed that concurrently, the partners’ levels of goal congruence were associated with greater ability to make goal progress and higher relationship satisfaction, both of which, in turn, were associated with higher subjective well-being. Longitudinally, initial levels of goal congruence did not predict changes in goal progress and relationship quality over time. However, analysis of the individual goals indicated that people adjusted their goal pursuits based on the level of goal conflict between their own goals and their partners’ goals, such that people were more likely to stop pursuing or devalue goals that conflicted with their partners’ goals over time. Furthermore, the tendency to adjust goals over time was associated with increasing relationship commitment. The results of these studies show that conflict between relationship partners’ goals has important consequences for their relationship, goal progress, and personal well-being. Read more
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Cops and Robber Game with a Fast RobberMehrabian, Abbas January 2011 (has links)
Graph searching problems are described as games played on graphs, between a set of searchers and a fugitive. Variants of the game restrict the abilities of the searchers and the fugitive and the corresponding search number (the least number of searchers that have a winning strategy) is related to several well-known parameters in graph theory. One popular variant is called the Cops and Robber game, where the searchers (cops) and the fugitive (robber) move in rounds, and in each round they move to an adjacent vertex. This game, defined in late 1970's, has been studied intensively. The most famous open problem is Meyniel's conjecture, which states that the cop number
(the minimum number of cops that can always capture the robber) of a connected graph
on n vertices is O(sqrt n).
We consider a version of the Cops and Robber game, where the robber is faster than the cops, but is not allowed to jump over the cops. This version was first studied in 2008.
We show that when the robber has speed s,
the cop number of a connected n-vertex graph can be as large as Omega(n^(s/s+1)). This improves the Omega(n^(s-3/s-2)) lower bound of Frieze, Krivelevich, and Loh (Variations on Cops and Robbers, J. Graph Theory, to appear). We also conjecture a general upper bound O(n^(s/s+1)) for the cop number,
generalizing Meyniel's conjecture.
Then we focus on the version where the robber is infinitely fast, but is again not allowed to jump over the cops. We give a mathematical characterization for graphs with cop number one. For a graph with treewidth tw and maximum degree Delta,
we prove the cop number is between (tw+1)/(Delta+1) and tw+1. Using this we show that the cop number of the m-dimensional hypercube is
between c1 n / m sqrt(m) and c2 n / m for some constants c1 and c2. If G is a connected interval graph on n vertices, then we give a polynomial time 3-approximation algorithm for finding the cop number of G, and prove that the cop number is O(sqrt(n)).
We prove that given n, there exists a connected chordal graph on n vertices
with cop number Omega(n/log n). We show a lower bound for the cop numbers of expander graphs, and use this to prove that the random G(n,p) that is not very sparse,
asymptotically almost surely has cop number between d1 / p and d2 log (np) / p for suitable constants d1 and d2. Moreover, we prove that a fixed-degree regular random graph with n vertices asymptotically almost surely has cop number Theta(n). Read more
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Pursuit and evasion games: semi-direct and cooperative control methodsParish III, Allen S. 15 May 2009 (has links)
Pursuit and evasion games have garnered much research attention since the
class of problems was first posed over a half century ago. With wide applicability to
both civilian and military problems, the study of pursuit and evasion games showed
much early promise. Early work generally focused on analytical solutions to games
involving a single pursuer and a single evader. These solutions generally assumed simple system dynamics to facilitate convergence to a solution. More recently, numerical
techniques have been utilized to solve more difficult problems. While many sophisticated numerical tools exist for standard optimization and optimal control problems,
developing a more complete set of numerical tools for pursuit and evasion games is
still a developing topic of research.
This thesis extends the current body of numeric solution tools in two ways.
First, an existing approach that modifies sophisticated optimization tools to solve
two player pursuer and evasion games is extended to incorporate a class of state
inequality constraints. Several classical problems are solved to illustrate the e±cacy
of the new approach. Second, a new cooperation metric is introduced into the system
objective function for multi-player pursuit and evasion games. This new cooperation
metric encourages multiple pursuers to surround and then proceed to capture an
evader. Several examples are provided to demonstrate this new cooperation metric. Read more
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Licensing in the Eating Domain: Implications for Effective Self-Control MaintenanceIsherwood, Jennifer Camille January 2015 (has links)
<p>The current study assessed the relationship between licensing and self-control maintenance. Previous research on licensing has found mixed results for the effect of perceived progress on goal pursuit. Some studies find evidence that progress increases commitment and motivation to a goal, making licensing less likely, whereas other studies have found that progress leads to coasting and feelings of earned licensing. Previous work on managing food consumption has demonstrated that using a mental budget in tandem with a salient avoidance goal is an effective means of monitoring and limiting overindulgence. The current study used a mixed event-contingent and fixed-interval experience sampling design to examine the role of licensing in the eating domain and its effect on goal pursuit. Participants in the experimental condition were prompted with personalized commitment devices each day to assess if they promoted goal pursuit and appropriate licensing. We found that licensing occurs infrequently, but when it does occur, goal progress and goal commitment increase. The use of commitment device has little impact on licensing or goal pursuit.</p> / Dissertation
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Stable and Efficient Sparse Recovery for Machine Learning and Wireless CommunicationLin, Tsung-Han 06 June 2014 (has links)
Recent theoretical study shows that the sparsest solution to an underdetermined linear system is unique, provided the solution vector is sufficiently sparse, and the operator matrix has sufficiently incoherent column vectors. In addition, efficient algorithms have been discovered to find such solutions. This intriguing result opens a new door for many potential applications. In this thesis, we study the design of a class of greedy algorithms that are extremely efficient, e.g., Orthogonal Matching Pursuit (OMP). These greedy algorithms suffer from a stability issue that the greedy selection approach always make locally optimal decisions, thereby easily biasing and mistaking the solutions in particular under data noise. We propose a solution approach that in designing greedy algorithms, new constraints can be devised by leveraging application-specific insights and incorporated into the algorithms. Given that sparse recovery problems by definition are underdetermined, introducing additional constraints can significantly improve the stability of greedy algorithms, yet retain their efficiency. / Engineering and Applied Sciences
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