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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Integration of Sensory Feedback When Adapting to Novel Visuomotor Environments

Hinder, Mark Unknown Date (has links)
The aim of the research described in this thesis is to improve our understanding of how the central nervous system (CNS) integrates feedback information from different sensory modalities to permit skill acquisition, and the subsequent consolidation of that skill, when exposed to a novel visuomotor environment. Indeed, such adaptation must be consolidated and recalled when appropriate such that we do not have to continually relearn skills we once possessed. By manipulating the sensory feedback available from the visual and proprioceptive systems during learning, it is possible to determine those facets of the sensory feedback that are essential for adaptation to occur. The thesis consists of seven chapters. The first and last provide a conceptual basis for, and an overall discussion of, the research. Chapter 2 reviews current visuomotor adaptation research, with particular focus on the manner in which information about novel tasks is stored within the CNS as we adapt, and the sensory information that is necessary to allow this adaptation to occur. Furthermore, this chapter serves to introduce many of the experimental techniques that are used to investigate motor learning in humans. Chapter 3 is a report of an investigation of the issues of interference and consolidation in an isometric target acquisition task. Exposure to a 30° counter-clockwise (CCW) rotation was followed by a period of rest, trials with no rotation, or trials with a 60° clockwise (CW) rotation. Retention of the initial adaptation was assessed 5 hours later. Full interference was manifested in circumstances in which either counter-rotated or non-rotated trials were encountered following the initial learning period. These results are consistent with the view that the observed interference is anterograde in nature, and highlight differences in the mechanisms employed by the CNS when compensating for novel kinematics (e.g. visuomotor rotations) compared with adapting to novel dynamics (e.g. external forces). Chapter 4 is a report of an investigation of the role of visual feedback in adapting to novel visuomotor environments in an isometric target acquisition task. Following trials with no rotation, participants adapted to a 60° CCW visuomotor rotation before returning to the non-rotated condition. Separate groups received either continuous visual feedback (CF) of cursor position during task execution or post-trial visual feedback (PF), both indicating task performance. One CF group were instructed to make any (feedback) modifications necessary during the task to reduce errors and acquire the target, while another CF group were instructed to make uncorrected, ballistic movements. Colour cues permitted the identification of the task environment (nonrotated/ rotated) on every trial. The results indicate that an automatic recalibration of the visuomotor mapping occurs when CF is provided, and suggest that performance improvements with PF may occur via the adoption of a cognitively mediated strategy. Furthermore, execution of feedback motor commands to correct errors did not enhance the adaptation that occurred when CF was provided, indicating that the perception of sensory errors (and not feedback commands that may be applied to reduce those errors) drives feedforward visuomotor adaptation. To investigate whether additional proprioceptive feedback associated with movement altered the adaptation patterns observed in chapter 4, a study similar to that reported in chapter 4 was undertaken, and is reported in chapter 5. In this instance a discrete, goaldirected, movement task replaced the isometric task. Subjects were deprived of vision of their arm, but were provided with PF or CF indicating task performance. The patterns of adaptation noted in the isometric task were also exhibited in this dynamic task, indicating that the timing of the visual feedback of task performance has a profound effect on how performance improvements in a novel visuomotor rotation occur. The experiment reported in Chapter 6 assessed the ability to adapt to two conflicting visuomotor rotations interleaved within the same training period, when each task variant (rotation) could be identified by contextual (colour) cues. While full dual adaptation was not observed, the results suggest that the colour cues may have been utilised to explicitly select distinct motor commands for each task rotation.
122

Optimal Experience in Physical Activity: Examining the Multidimensionality of Flow Across Cultures

Kawabata, Masato Unknown Date (has links)
Applying the lens of experience, a good life is deemed to be characterized by full absorption in what one does (Nakamura & Csikszentmihalyi, 2002). In addition, experiencing flow is linked with personal growth (Seligman & Csikszentmihalyi, 2000). Therefore, it is not surprising that understanding the optimal experience of flow is considered important. Nonetheless, it is never easy to clearly explain this complex but positive subjective experience. Thus, the present investigation was conducted to provide a clearer conceptualization of flow based on theoretical and empirical grounds to foster understanding of this optimal experience. In order to pursue this primary purpose, the following 3 studies were conducted. The purpose of Study 1 was to develop multidimensional measurement instruments for use with Japanese adults to assess flow experience in physical activity. To this end, the Flow State Scale-2 and Dispositional Flow Scale-2 (FSS-2 and DFS-2) were adapted (translated) from English to Japanese, following the guidelines for test adaptation proposed by Duda and Hayashi (1998) and Tanzer and Sim (1999). Employing a 9-factor 1st-order model, the factorial validity of the Japanese versions of the FSS-2 and DFS-2 (JFSS-2 and JDFS-2) was tested and cross-validated with confirmatory factor analysis (CFA). Through a multi-staged approach, a series of CFAs were conducted on data from large Japanese samples (preliminary samples: n = 578; calibration samples: n = 975; validation samples: n = 970). In addition to internal consistency reliability for both scales, stability was assessed over a 4- week time period for the JDFS-2. Furthermore, measurement equivalence was examined across Japanese independent samples as well as 2 cultural samples. The findings from this study provided strong support for the validity and reliability of the JFSS-2 and JDFS-2 in assessing flow experiences in physical activity for Japanese adults, and indicated that the Japanese versions of the flow scales are useful instruments for cross-cultural research. The purpose of Study 2 was to examine the internal structure of flow as part of an ongoing process of construct validation of flow responses. A total of 4,175 respondents (Japanese: n = 2,041; English-speaking: n = 2,134) completed one of the Japanese and English versions of the FSS-2 or DFS-2. For the Japanese respondents, data from calibration and validation samples in Study 1 were used. Alternative representations of flow responses were cross-culturally examined by testing 11 alternative 1st- and higher-order CFA models. The CFA findings cross-culturally supported and extended Marsh and Jackson’s (1999) argument that the situational and dispositional flow responses were best represented by the multidimensional 1st-order representation rather than the higher-order representation. Confirming clear support for the 1st-order representation of flow, structural equation models (i.e., a priori and post hoc models) were tested to examine the hypothesis that flow experience is an attentional process of absorption in the task at hand, which generates intrinsically rewarding feelings. Results of both models clearly supported the hypothesis across the 2 large cultural samples. The purposes of Study 3 were to examine the utility of multi-group comparisons with the JFSS-2 and JDFS-2 and to further examine the construct validity of the Japanese flow responses. Data used in Study 3 were identical to the Japanese samples in Study 2 (N = 2,041). Factorial invariance in a 9-factor measurement model was tested for both flow scales for 5 key variables: the quality of physical activity experience, participation level, types of physical activity, gender, and age. Given an adequate level of measurement invariance, factor means were compared across groups for each variable. Furthermore, correlations between a continuous measure of the complexity of flow and the JFSS-2 factors were examined. Invariance of factor loadings and intercepts was achieved for all the key variables. Through factor mean comparisons for the quality of physical activity experience and participation level, the flow group consistently showed higher scores on most situational factors compared with the other groups (i.e., non-flow conditions), and the competitive groups had higher scores on most factors than the recreational groups for both the JFSS-2 and JDFS-2. Moreover, the continuous flow measure was most highly correlated with the situational Challenge-Skill Balance factor, and the pattern of the size of correlations between this continuous flow measure and other situational factors were similar to those between the Challenge-Skill Balance and other JFSS-2 factors. The findings from this study provided evidence that meaningful multi-group comparisons can be made for the key variables examined with the Japanese flow scales, and also further support for the construct validity of the Japanese flow responses. In conclusion, the general conceptualization of flow as an attentional process of absorption in the task at hand, which generates intrinsically rewarding feelings, fosters further understanding of flow experience in physical activity. Furthermore, systematic cross-cultural studies with different adapted versions of the flow scales aid understanding of cultural similarities and differences in flow experience and contribute to further development of flow theory and its application.
123

American Football : A Markovian Approach / Amerikansk fotboll med Markovkedjor

Larsson, Joakim, Sjökvist, Henrik January 2016 (has links)
This bachelor's thesis in applied mathematics & industrial economics is an attempt to model drives in American football using Markov chains. The transition matrix is obtained through logit regression analysis on historical data from the NFL. Different outcomes of drives are modelled as separate absorbing states in the Markov chain. Absorption probabilities are calculated representing the probabilities of each outcome. Results are tested against a Markov chain with the transition matrix based on frequency analysis. Three scoring rules unanimously declare the regression based model to be superior. The application of the model pertains to live sports betting. With the insight provided by the Markovian model, a bettor should be able to make statistically informed betting decisions. The prospect of creating a start-up based on the Markovian betting model is discussed. / Denna kandidatuppsats i tillämpad matematik & industriell ekonomi är ett försök till att modellera drives i amerikansk fotboll med hjälp av Markovkedjor. Övergångsmatrisen fås genom logit-regressionsanalys av historisk data från NFL. Olika utfall av drives modelleras som separata absorberande tillstånd i Markovkedjan. Absorptionssannolikheter beräknas, vilka representerar sannolikheterna för de olika utfallen. Resultaten testas mot en Markovkedja där övergångsmatrisen fås genom frekvensanalys. Tre olika poängregler föredrar enhälligt den regressionsbaserade modellen. Modellens tillämpning berör sportbetting. Med hjälp av Markovmodellen bör en spelare kunna ta statistiskt underbyggda beslut i deras betting. Möjligheterna att skapa ett företag baserat på Markovmodellen diskuteras.
124

Development of a functional neuromuscular stimulation (FNS) muscle training program to prepare paraplegics for standing

Schafer, Carol Linda 21 April 2017 (has links)
Wheelchair-bound paraplegics are in an unnatural, almost all-day sitting position. This is physiologically disadvantageous as it may cause increased abdominal pressure, renal dysfunction, pressure sores, muscle atrophy and osteoporosis. Thus it would be beneficial, physiologically and psychologically, for a paraplegic to be able to stand for temporary periods of time. As a result of the muscle atrophy and functional degeneration that follows a spinal cord injury, it is essential for paraplegics to undergo a muscle restrengthening program, using Functional Neuromuscular Stimulation (FNS), before standing up under FNS control can be attempted. Six healthy spinal cord injured subjects with spinal lesions between CS and T9 (two tetraplegics and four paraplegics) exercised their quadriceps muscles at home using a portable two-channel FNS muscle stimulator. The muscles were exercised against an increasing load to maximise the training effect. Inclined standing exercise, under FNS control, was performed in the Inclistand. The subjects' general state of health and fitness were assessed, namely their responses during a maximal arm ergometry exercise test, arm muscle function, lung function, blood biochemistry and their dietary habits. Subjects have shown improvement in quadriceps muscle strength, fatigue resistance and muscle bulk to varying degrees - according to their individual circumstances. The tetraplegics responded in a different manner to that of the paraplegics. The muscle strength increased significantly by a mean (+SD) of 97,8 + 59,6% and 171,2 + 118,1% for the four paraplegics, left and right leg respectively. There was a mean improvement of 16% in fatigue resistance in the left leg (p=0,08), while the mean response of the right leg varied. Quadriceps muscle bulk increased by 4,43 + 3,4% (left) and 2,7 + 2,1% (right) (0,05<p<0,l). The amount of subcutaneous fat around the mid-thigh decreased significantly by 4,73 + 1,4% (left) and 3,43 + 1,1% (right leg). The group was in a state of general well-being, with the exception of one subject whose serum cholesterol concentration fell within the high risk category. This study therefore showed that the FNS was sucessful in improving the quadriceps muscle strength, bulk and fatigue response of the SCI people in our research group. The valuable experience gained from this FNS study will be used to improve the present program.
125

Eye and Head Movements in Novice Baseball Players versus Intercollegiate Baseball Players

Kuntzsch, Erik C. 31 October 2017 (has links)
No description available.
126

Fachtagung Schulsport und Schulsportforschung 2011: Tagungsband ; 1. Dezember 2011

Hummel, Albrecht 14 December 2012 (has links)
Systematische Forschungen zum Schulsport bei Nutzung und Verknüpfung unterschiedlicher disziplinärer Zugänge sind durchaus möglich wenn bestimmte Rahmenbedingungen von den zuständigen Landesministerien geschaffen werden und die Wissenschaftler – in der Regel Sportwissenschaftler aus verschiedenen sportwissenschaftlichen Teildisziplinen – problemgeleitet, anwendungsorientiert und berufsfeldbezogen mit den Vertretern der Schulsportpraxis und den Schulverwaltungen zusammenarbeiten. Auf diesem Wege ist eine forschungsbasierte und wissenschaftlich begleitete Schulsportentwicklung effektiv und zielführend realisierbar. Der vorliegende Tagungsband der am 01. Dezember 2011 in Dresden durchgeführten Fachtagung enthält Beiträge von 21 Autoren, die sich u. a. mit der übergreifenden Schulentwicklung und der fachlich konkreten Schulsportentwicklung im Kontext der Qualitätsdebatte, der motorischen Entwicklung und der motorischen Leistungsfähigkeit von Kindern unter Beachtung der verschiedenen schulischen Bedingungen und außerschulischer Einflussfaktoren sowie mit der hochaktuellen Debatte zur schulpolitischen und schulpraktischen Umsetzung von Integrations- und Inklusionsmaßnahmen im Rahmen einer zeitgemäßen Schul- und Schulsportentwicklung auseinandersetzen.
127

Wahrnehmung und Vorstellung von Bewegungen - Studien im Kontext des Erwerbs sportlicher Fertigkeiten in der Kindheit / Perception and imagery of movements – studies in context of motor learning in childhood

Salb, Sandra 07 May 2014 (has links)
Diese Dissertation untersucht motorische und kognitive Leistungen in der Kindheit am Beispiel des Erlernens einer sportlichen Fertigkeit. Dafür wurde eine Methode zur Messung mentaler Vorstellungen von Bewegungen bei Vorschulkindern entwickelt. Diese basiert auf dem Prinzip räumlicher Verdeckung. Es wurden damit sowohl verschiedene kognitive Leistungen wie die Wahrnehmung und Vorstellung von Bewegungen miteinander verglichen als auch in Beziehung zum Bewegungslernen gesetzt. Außerdem wurde in einer quasi-experimentellen Studie u.a. der Einfluss von Erfahrung, Geschlecht und Versuchsbedingung auf Wahrnehmungs- und Vorstellungsleistungen per Experten-Novizen-Paradigma untersucht. Es wurde geschlussfolgert, dass die Methode hinsichtlich des Geschlechts auch in jungen Jahren differenziert. Das bedeutet, dass Mädchen und Jungen im Vorschulalter möglicherweise unterschiedlich bei der Lösung der Aufgaben vorgehen. Damit kann die Methode - im Gegensatz zur Methode der Mentalen Rotation - auch für die Diagnostik von Vorstellungen von Bewegungen ab einem Alter von 4 Jahren eingesetzt werden.

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