3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item The effect of physiotherapy in a group on the motor function of children with developmental coordination disorder(2009-10-20T08:34:02Z) Brenner, JulieChildren with Developmental Coordination Disorder (DCD) are a heterogeneous group who have a marked impairment in the performance of functional motor skills. DCD affects 5-8 % of children in the mainstream educational system, with twice as many boys than girls being affected. DCD often co-occurs with other developmental disorders such as Attention Deficit Hyperactivity Disorder (ADHD), Attention Deficit (ADD), severe learning disabilities and reading disabilities and is often associated with educational, social and emotional problems that often persist beyond adolescence. Current research has shown that children with DCD do not outgrow their motor problems and without intervention they do not improve (Zoia et al, 2006; Barnhart et al, 2003; Peters and Wright, 1999). The aim of this study was to investigate the effect of an eight week group gross motor intervention programme on 26 children with Developmental Coordination Disorder (DCD) at Forest Town School, which is a special-needs school for children with learning disabilities. The intervention programme consisted of gross motor activities commonly used by the physiotherapists at the school for their DCD groups. The children attended a thirty-minute physiotherapy session a week, in groups of up to 6, for eight weeks. The children’s motor performance was assessed using the Bruininks-Oseretsky Test for Motor Proficiency (BOTMP) pre- intervention, post- intervention and then eight weeks after the intervention had ceased. The children were used as their own controls. The results of the statistical analysis revealed that the mean group gross motor and fine motor scores significantly improved after the intervention. It was found that the gross motor scores improved by a larger percentage than the fine motor, which may be because the intervention consisted purely of gross motor activities. The fine motor scores also significantly improved, implying that there was a transfer or generalisation of skills to the fine motor tasks. The improvement in the motor performance was found to be maintained eight weeks after the intervention was stopped. It was concluded in the study that the eight week group physiotherapy programme at Forest Town School improved the motor skills of children with DCD and learning difficulties. Physiotherapy in a small group may therefore be a cost effective solution for the treatment of children with DCD in government-funded schools and hospitals that have a limited number of physiotherapists available to treat these children.Item Theoretical investigation of the Optical Kerr effect and Third-Harmonic Generation in AU-VO2 thin-films.(2006-03-22) Nkulu, Mulunda FranlyThe theoretical investigation of the Optical Kerr Effect (OKE) and Third- Harmonic Generation (THG) of Au-VO2 nanocomposite thin-films undertaken in this project is motivated by the potential use of the Au-VO2 nanocomposite in nonlinear optical (NLO) devices. NLO devices are a driving force in today fs high technology industry. In this thesis the OKE is estimated and computed and will be compared later to the measured OKE using the Z-scan interferometric laser technique [47]. This is a simple yet highly sensitive single-beam experimental technique used to determine the real part of the dielectric susceptibility. The study of the OKE in these composites has shown that it has a high value, comparable to that found in Au-SiO2, Au-TiO2 and Au-Al2O3 thin-films [29, 33]. This is despite the fact that the Au volumetric concentration in the Au-VO2 composites considered here is 10 percent at most, whereas in the other above mentioned composite thin-films the volumetric concentration range was between 5 − 60 percent. Moreover, it has been demonstrated that the OKE is thermally tunable in the Au-VO2 thin-films, owing to the thermally tunable optical properties of the VO2 [8, 38]. It is found that the magnitude of the OKE is of the order of 10−6 esu when the composite is below 68 0C and it is of the order of 10−7 esu when the nanocomposite thin-film is above 68 0C. The large enhancement of the OKE is due to the surface plasmon resonance (SPR) of the nanogold particles. Its fast response, which is of the order of few picoseconds [4, 6, 7], makes the Au-VO2 nanocomposite a good candidate as a fast thermally tunable optical switch or modulator. The modelling here of high-order harmonic generation in strongly absorbing media, as regards the amplitude of the primary beam, takes into account pump attenuation only, due to the absorption of light by the media. It is not concerned with pump depletion which is a consequence of the transfer of energy to the harmonics and which is small by comparison with attenuation in absorbing media. The modelling is applied to the so-called transmission and reflection configurations. The former refers to the case in which the high-order harmonic wave is monitored in the same direction as the input fundamental wave, whereas the latter describes the situation in which the fundamental wave is in the opposite direction to the high-order harmonic one. To analyse high-order harmonic generation one has to relate the high-order harmonic intensity to the fundamental intensity [1, 9, 10, 34-36]. In so doing, a general formula for analysing high-order harmonic generation is obtained and reduced to the particular case pertaining to THG in strongly absorbing media. The ratio of the third-harmonic intensity to the fundamental intensity is termed the conversion coefficient or the conversion efficiency, and it is denoted by ƒÅ [23, 34]. It is useful in the sense that it expresses quantitatively the amount of input light of frequency ƒÖ converted into light of frequency nƒÖ, where n is the order of nonlinear polarisation [1]. It is found that the THG conversion coefficient is higher the higher the laser intensity. It is thus advantageous to use a pulsed laser, which achieved very high intensities for short periods, separated by long off periods. The net harmonic output in this case is much higher than one would obtain with a continous laser of the same average output. It is found here that ƒÅ is greater in the reflection configuration compared to the transmission one above and below Tt in the photon energy range 1.0 − 3.0 eV, see Fig. 5.1 to 5.8. However, the conversion efficiency for THG in the Au-VO2 nanocomposites for the picoseconds laser illumination we have considered, is still extremely low, and it is difficult to see a potential use for this system as a tunable frequency converter. The situation would become more favorable with the use of femtosecond laser pulses, where for the same pulse energy the intensity is much greater. The laser pulse energy must be limited to avoid excessive heating of the thin-film. The heat generated as a consequence of the illumination of the thin-film by the laser [23] may be controlled by using a simple cooling device which consists of a substrate on which the thin-film is deposited. The choice of such a substrate depends on whether THG is monitored in the transmission or reflection configuration. In the former a transparent substrate must be used (for example diamond) whereas in the latter an opaque substrate may be used (for example Ag). Calculations pertaining to the removal of heat from the illuminated film are reported, and show that thermal control is manageable but only within limits. To avoid a temperature rise of more than 5 0K the peak laser intensity we found must not exceed 7.4 ~105Wcm−2 with a pulse duration of 5 ps.