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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.
41

Musculoskeletal and perceptual responses of batsmen comparing high- and moderate-volume sprints between the wickets

Sheppard, Bronwyn Jane January 2012 (has links)
Background: Literature has associated repeated eccentric muscle actions with increased muscle damage of the muscles involved. Eccentric actions are typical in sports which are ‘stop-start’ in nature requiring rapid acceleration and deceleration, typical of a batting activity in cricket. Ultra-structural damage of the skeletal muscle as a consequence of repeated decelerating activities is associated with performance decrements, particularly muscle strength and sprinting speeds. This suggests that eccentric strength decrements may provide an indication for the development of muscle strain injuries during these activities. Despite these findings, limited research has identified the specific musculoskeletal demands placed on cricket batsmen, particularly with reference to various match intensities. Objective: The present study, therefore, sought to determine the specific musculoskeletal, physiological and perceptual demands placed on specialised batsmen during two work bouts of different intensities; one representing a highintensity work bout and the other a moderate-intensity work bout. The dependent variables of interest were muscle activation, isokinetic strength changes, heart rate, ‘central’ and ‘local’ ratings of perceived exertion (RPE), body discomfort and performance. Methods: The two experimental conditions, representative of a high- (HVR) and moderate-volume running (MVR) batting protocol, required players to perform a simulated batting work bout of either twelve or six runs an over, within a laboratory setting. Selected physiological, perceptual and performance measures were collected at specific time intervals throughout the work bout while the biophysical measures were collected prior to, and following both protocols. Results: Of the variables measured, heart rate, ‘central’ and ‘local’ RPE values were observed to increase significantly (p<0.05) over time. This increase was greater as a consequence of the HVR in comparison to the MVR. No change in sprint times was documented during the MVR, in contrast, significant (p<0.05) increases over time were observed during the HVR, further highlighting the elevated demands associated with this condition. In addition, an ‘end spurt’ was observed particularly following the HVR condition, suggesting athletes were conserving themselves through the adoption of a pacing strategy. Reductions in biceps femoris and semitendinosus muscle activation levels were observed following the HVR. This was further supported by the significantly greater levels of semitendinosus activation following the MVR when compared to the HVR. Peak concentric and eccentric knee extensor (EXT) (-17.17% and -16.07% respectively) and eccentric flexor (FLEX) (- 17.49%) values decreased significantly (p<0.05) following the HVR at 60°.s-1. In addition, concentric and eccentric total work produced by the flexors and eccentric extensors resulted in significantly (p<0.05) lower values due to the HVR. Conclusion: The intermittent high-volume batting work bout elicited elevated mean heart rates, perceived ratings of cardiovascular and muscular effort and sprint times. Furthermore, hamstring activation levels and muscle strength, particularly concentric strength of the dominant lower limb were negatively affected by the HVR condition. These results suggest elevated demands were placed on the hamstring musculature as a consequence of the HVR condition, indicating a greater degree of musculoskeletal strain and increased injury risk associated with running between the wickets at this intensity, representative of an aggressive batting scenario.
42

Integer optimization for the selection of a twenty20 cricket team

Lourens, Mark January 2008 (has links)
During the last few years, much effort has been devoted to measuring the ability of sport teams, as well as that of the individual players. Much research has been on the game of cricket, and the comparison, or ranking, of players according to their abilities. This study continues preceding research using an optimization approach, namely, a binary integer programme, to select an SA domestic Pro20 cricket team.
43

Motor neurons and motor patterns underlying phonotaxis during flight of the cricket, Teleogryllus oceanicus

Wang, Hsien-Yi Sabrina January 1988 (has links)
No description available.
44

Measuring team performance and modelling the home advantage effect in cricket

Allsopp, Paul, n/a January 2005 (has links)
Cricket differs from many team sports in that it is not generally played within easily definable constraints. Thus, it is difficult to compare and contrast team performances. By employing a range of linear and logistic modelling techniques this thesis quantifies the extent to which team quality effects and a range of associated factors such as home advantage have shaped team performance in Test, ODI and domestic cricket. With regards to the latter, the thesis established that, in all forms of cricket, a team?s scoring potential and its capacity to win were both significantly amplified when it played at its home ground. The thesis proposes a method to estimate a projected score for the team batting second in ODI cricket. The method scales up the team?s actual winning scores in proportion to its unused run scoring resources. This creates a projected victory margin when it wins with unused run scoring resources at its disposal and provides a more realistic measure of its relative superiority at the point of victory than the current wickets-in-hand method. Accordingly, the thesis recommends a revised scheme for recording victories in ODI cricket which is consistent across innings and provides a mechanism for all victories to be compared and ranked on an equal footing. The thesis employs linear modelling methods that account for the size of a victory in ODI cricket and the magnitude of the first innings lead in Test and domestic cricket to compute team ratings. The ratings are calculated independently of effects such as home advantage and quantify overall team performance relative to the average rating. They provide a robust measure of team quality and are not sensitive to the extraneous effects that may disproportionately impact on team performance. As a consequence, the thesis recommends that new methods be investigated to officially rate and rank teams in international cricket competitions. The team ratings also form the basis of a proposed outcome prediction model that can be instituted in Test cricket. The thesis established that a surprising trend has emerged in Test cricket, which confirmed that the team batting second, in general, has enjoyed a distinct winning advantage over its opposition. Accordingly, the thesis ascertained that relative strength during the final rather than penultimate innings significantly affected match outcomes and recommends that teams, when winning the coin toss, expose their strongest asset, whether this be batting or bowling, in the final innings.
45

The natural history and possible extirpation of Blanchard's Cricket Frog, Acris crepitans. blanchardi, in West Virginia

Dickson, Nancy J. January 2002 (has links)
Thesis (M.S.)--Marshall University, 2002. / Title from document title page. Document formatted into pages; contains ix, 115 p. with maps and illustrations. Includes vita. Includes bibliographical references (p. 34-40).
46

Frequency-dependent temporal processing in the peripheral auditory system of Teleogryllus oceanicus

Sabourin, Patrick. January 2008 (has links)
The detection of specific temporal patterns in communication signals may be of vital importance for certain organisms. In crickets, for instance, a female will move towards a singing male only if she can recognize the appropriate pulse rate characteristic to its own species' song. Additionally, in order to evade predatory insectivorous bats, flying crickets must be able to track the predator's ultrasonic echolocation signals, which are emitted at a variety of pulse rates. In this thesis, the temporal processing, or the integration of stimulus through time, in the peripheral1 auditory system of the cricket will be investigated. / The ON1 interneuron temporal processing was first examined and compared at high (bat-like) and low carrier (cricket-like) frequencies in three different experimental paradigms. First, integration time, which corresponds to the time it takes for a neuron to reach threshold when stimulated at the minimum effective intensity, was found to be significantly shorter at high carrier frequency than at low carrier frequency. Second, phase locking to sinusoidally amplitude modulated (SAM) signals was more efficient at high frequency, especially at high modulation rates and low modulation depths. Finally, we examined the efficiency with which ON1 detects gaps in a constant tone. As reflected by the decrease in firing rate in the vicinity of the gap, ON1 is better at detecting gaps at low carrier frequency. Following a gap, firing rate increases beyond the pre-gap level. This "rebound" phenomenon is similar for low and high carrier frequencies. / To determine the source of this differential temporal processing, the sensory afferents making synapses with ON1 were investigated. Low frequency (MT-type) and ultrasound auditory receptors were compared on the basis of latency, maximum firing rate, adaptation, information transmission, bursting and feature detection. Ultrasound receptors (HFs) were found to have a shorter latency, a higher maximum firing rate and stronger adaptation than low-frequency receptors (LFs). Individual HFs transmitted more linear (lower-bound) information than LFs. However, HFs' responses were more correlated than LFs' (i.e. they had larger mutual information), so that when superposing the spike trains of LFs, information transmission in the lowest amplitude modulation rates was greatly improved, and, in some cases, reached the level of HFs. Feature detection by spike in HFs was better than in LFs. Feature detection by bursts was better than for spikes, but equivalent in both types of receptors. The level of bursting in HFs, however, was much higher than in LFs, making them better feature detectors in general. / 1Because it lies in the prothoracic ganglion, ON1 is technically part of the central nervous system. For the purpose of this thesis, however, because ON1 receives direct input from the receptors, it will be considered to be part of the peripheral auditory systems.
47

Temporal coding and auditory processing in the prothoracic ganglion of crickets

Marsat, Gary. January 2006 (has links)
We used the auditory system of crickets as a model system to examine the importance of temporal coding in sensory processing. The bilaterally paired Ascending Neurons 1 and 2 (AN1 and AN2) of crickets receive inputs from the auditory receptors on one side and carry the information to the brain. We used stimuli with either conspecific-like or predator-like (i.e. bats) carrier frequency to quantify the accuracy with which the interneurons code the information contained within the amplitude modulation (AM) envelope of the stimulus. AN1, which is tuned to the dominant carrier frequency of cricket songs, selectively codes the limited range of amplitude-modulation frequencies that occur in these signals. AN2, which is most sensitive to ultrasound, serves as a "bat-detector" and codes a broader range of AM frequencies, as occur in bat calls. / A striking characteristic in AN2's responses to ultrasound is the presence of bursts of high-frequency spiking separated by relatively sparse spikes. We examined the relative importance of isolated spikes and bursts in the processing of ultrasound. We showed that bursts reliably signal the occurrence of salient amplitude increases. Furthermore, we showed that burst, but not isolated spikes, reliably predict behavioural responses. We suggest AN2 encodes behaviourally important information with bursts. / The Omega Neuron 1 (ON1) responds to conspecific signals and to the ultrasonic echolocation sounds. ON1's temporal coding properties vary with carrier frequency, allowing it to encode both of these behaviourally important signals. Furthermore, the temporal coding properties of ON1 in response to cricket-like sound and bat-like sound match those of AN1 and AN2 respectively. / ON1 is a source of contralateral inhibition to AN1 and AN2, enhancing binaural contrast and facilitating sound localization. We used dichotic stimulation to examine the importance of the temporal structure of contralateral inhibition for enhancing binaural contrast. Contralateral inhibition degrades the accuracy with which amplitude modulation is encoded by AN 1 and AN2, but only if the temporal pattern of inhibitory input matches that of excitation. Our results show that the CF-specific coding properties of ON1 allow this single neuron to enhance localization cues most effectively for both cricket-like and bat-like acoustic signals.
48

The travelling female athlete : cricket, migration and globalisation.

Perry, Elizabeth Cecelia January 2014 (has links)
This study explores the experiences of female athletes from New Zealand and Australia who migrate temporarily to play cricket in England. It locates the migration network of female cricket within the modern global sport space and challenges the overall perception of what the typical global athlete is today. The game of cricket has long been regarded as the ‘gentleman’s’ game and originated in England as an aristocratic sport, a symbol of wealth and hierarchy among the British elite. It has diffused into many Commonwealth countries and has developed into a game that is played by both sexes. This study is situated within the anthropology of sport and includes aspects of culture, identity, and gender in the globalised world we live in today. It offers a unique perspective because the research is conducted by a migrant female cricketer in the field and combines ethnographic and auto-ethnographic material. Attention to the migration of female athletes has been minimal but research into this area of the sporting world raises a number of broader questions relating to sporting migration, personal/national identity, transnationalism, cosmopolitanism, diaspora, the gender divide in sport and globalisation. This study summarises some of the key literature relating to globalisation, sports migration, identity and gender, applying it anthropologically to the experiences of the migrant female cricketer. The main finding is the movement of female cricketers from country to country is not influenced by the commodification of modern sport; instead the athletes are motivated by social and personal factors, as opposed to the material (monetary) ones that now apparently dominates contemporary sport. Movement reflects a basic migratory network that has developed between New Zealand, Australia and England, influenced by seasonal migration, and the social, cultural and historical connections between the countries. The research offers a contrasting perspective on current sporting migration literature by sharing the experiences of female athletes who migrate for sport and locating the findings within larger analytical concepts.
49

Evidence for the putative roles of GABAergic, cholinergic and octopaminergic pharmacology in the auditory system of the cricket Teleogryllus oceanicus

Naraine, Kim. January 2005 (has links)
In the field cricket, Teleogryllus oceanicus, two types of auditory interneurons, AN2 and ON1, have been studied. AN2 responds best to ultrasound frequencies (&ge;20kHz) produced by echolocating bats and initiates negative phonotaxis by the cricket. ON1 responds to both low (4-5kHz) and high frequency sounds and encodes the temporal information present in sounds of both frequencies. ON1 also provides lateral inhibition to contralateral interneurons, such as AN2, thereby enhancing binaural contrast. The pharmacology associated with these two interneurons is investigated here. ON1's response to 4.5kHz sound is increased following picrotoxin application, while it's ability to encode temporal information present in low and high frequency sounds is reduced. An increase in spiking response and a decrease in response latency to low frequency sound is produced by the addition of atropine, while d-tubocurarine application increased ON1's response latency to both 4.5kHz and 30kHz sound. The neuromodulator octopamine reduced AN2's response to ultrasound.
50

Determining the biomechanical response of a filiform hair array a low Reynolds number fluid-structure model /

Cummins, Breschine. January 2009 (has links) (PDF)
Thesis (PhD)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Tomas Gedeon. Includes bibliographical references (leaves 183-190).

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