Ingeniero Civil Electricista / En las redes de datos cada día se desarrollan nuevos servicios y topologías más complejas, con más usuarios y restricciones diferenciadas para los diversos servicios. De esta forma, la estimación de parámetros de red, como por ejemplo, delay, backlog, tasas máximas de transferencia de datos, factores de ocupación, etc. son de interés para el dimensionamiento de los nodos a utilizar en las redes. Los flujos de tráfico que atraviesan las redes de computadores están sujetos a restricciones impuestos por los componentes del sistema. Estas restricciones pueden ser expresadas y analizadas con Network Calculus, lo que permite entender las propiedades de los distintos servicios entregados por las redes convergentes, para planificar y dimensionar los parámetros de las redes. El objetivo de este trabajo es aplicar Network Calculus en redes de datos y comparar la estimación de parámetros con mediciones reales y cálculos algebraicos. Se utilizan herramientas Open Source para la implementación de escenarios de red que simulan el servicio de video streaming. De los resultados que se obtienen de las mediciones de delay y pérdidas de paquetes del tráfico generado, se comparan con las estimaciones que resulta de aplicar Network Calculus a las curvas de servicio y llegada. Network Calculus resulta ser una herramienta que permite hacer estimaciones del peor caso, es por esto que el delay que se obtiene al ser aplicado Network Calculus es superior al delay medido. No se obtienen pérdidas de paquetes para ver si las estimaciones de backlog, que entrega el Network Calculus, son las correctas. Esto se debe principalmente a la gran capacidad de transmisión que tienen los routers. Como posibles futuros trabajos tenemos: realizar escenarios de pruebas más complejos; aplicar Network Calculus a otros tipos de tráficos; utilizar diversas políticas de encolamiento en los routers y una mejora en la estimación en la curva de servicio de los routers.

This thesis describes an optical fibre network that uses a bus topology and Code Division Multiple Access (CDMA). Various potential configurations are analysed and compared and it is shown that a serious limitation of optical CDMA schemes using incoherent correlators is the effect of optical beating due to the presence of multiple incoherent optical signals at the receiver photodiode. The network proposed and analysed in this thesis avoids beating between multiple optical fields because it only uses a single, shared, optical source. It does this through the SLIM (Single Light-source with In-line Modulation) configuration in which there is a continuously-operating light source at the head-end of a folded bus, and modulators at the nodes to impose signals on the optical field in the form of pulses of darkness which propagate along the otherwise continuously bright bus. Optical CDMA can use optical-fibre delay-line correlators as matched filters, and these may be operated either coherently or incoherently.Coherent operation is significantly more complex than incoherent operation, but incoherent correlators introduce further beating even in a SLIM network. A new design of optical delay-line correlator, the hybrid correlator, is therefore proposed, analysed and demonstrated. It is shown to eliminate beating. A model of a complete network predicts that a SLIMbus using optical CDMA with hybrid correlators can be operated at TeraBaud rates with the number of simultaneous users limited by multiple access interference (MAI), determined only by the combinatorics of the code set.

In this thesis we consider the traditional Van der Pol Oscillator with a forcing dependent on a delay in feedback. The delay is taken to be a nonlinear function of both position and velocity which gives rise to many different types of bifurcations. In particular, we study the Zero-Hopf bifurcation that takes place at certain parameter values using methods of centre manifold reduction of DDEs and normal form theory. We present numerical simulations that have been accurately predicted by the phase portraits in the Zero-Hopf bifurcation to confirm our numerical results and provide a physical understanding of the oscillator with the delay in feedback.

Background: Over 50% of HIV-infected children in South Africa have developmental delays. Early identification of affected children will lead to early intervention and favourable long-term outcome. Screening for developmental delay is not yet routine by many primary healthcare providers due to lack of locally available, rapid and sensitive screening tool s in busy Paediatric HIV clinics. A new screening tool was developed at the Red Cross War Memorial Children's Hospital (RCWMCH) for detecting moderate to severe global developmental delay among very young HIV infected children. The diagnostic accuracy and usefulness of the new tool was evaluated in this study. Objective: to validate the new RCWMCH developmental screening too l among HIV - infected South African children. Method: Forty-seven HIV-infected children in the age category 9-36 months attending the Infectious Disease Clinic (IDC) of the RCWMCH were screened using the new tool. Full developmental assessments of same children were performed using the Bayley Scale of Infant Development (BSID - III). Developmental Delay (global) was defined as composite scores 2 standard deviations below the mean in two or more developmental domains. Results: The sensitivity of the RCWMCH tool was 78.5%, specificity 54.6%, positive predictive value was 42.6%, and negative predictive value was 85. 7 %. Discussion: The RCWMCH screening tool was found to have sensitivity within the acceptable levels recommended for developmental screening tools. Its high negative predictive value will reduce unnecessary referrals for full developmental assessments in asymptomatic infants and toddlers. It is therefore recommended for screening for developmental delay among HIV-infected children from the age of 9 months to 3 years.

Audio perception latency can influence the performance ability of a musician. A phenomenographic study is conducted to discuss the issue of perception latency and determine the amount of latency musicians can tolerate. Potential contributing factors such as their musical training, studio experience, and ability to perform with a metronomic aid were taken into account. Upon completion of the performance aspect of the study, the researcher then conducted a semi-structured interview with each individual participant in which a series of questions were asked about the experiment. It is found that musicians employ various techniques to compensate for perception latency and that there is a maximum amount of latency that musicians can tolerate during a musical performance. Keywords: perception latency, reception latency, response latency, maximum latency, delay, optimal performance, tolerable performance. / Mini Dissertation (MMus)--University of Pretoria, 2016. / Music / MMus / Unrestricted

TITLE: DELAY DISCOUNTING AND CAMPUS SPEEDING BEHAVIORMAJOR PROFESSOR: Dr. Ryan Redner Speeding, as defined by exceeding the speed limit posted in a designated area, is a problem that has a direct negative effect on a majority of America, college campuses not being exempt. A minimal amount of research has been conducted on specifically dangerous driving such as speeding on university campuses; this paper looks to expand upon the existing research. In addition, this study serves the purpose of attempting to correlate speeding and impulsivity. This was achieved by utilizing a survey in conjunction with delay discounting scenarios embedded within. Participants (n = 89) took a survey that involved questions about demographic information and past driving. The survey also included two hypothetical scenarios that encouraged participants to answer whether they would speed in the presented scenarios and at what point. To complete the survey the MCQ (Monetary Choice Questionnaire) was placed at the end. To assess the results the 89 participants were split into two groups two different times to be analyzed. One group was split into an impulsive group and non-impulsive group while the other group was split into speeders and non-speeders. As expected, both the impulsive and speeders were more likely to discount speed at a faster rate; this shown at higher rates in the penalty hypothetical scenario. The implications of this study include that those with that display higher impulsivity, shown through k-values, may have a higher tendency to engage in dangerous driving such as speeding, as well as understanding that penalty conditions, such as point loss, show a correlation with speeding.

The purpose of the current study is to evaluate the relationship between discounting immediate and former life statuses prior to death related to quality of life across the lifespan. A discounting survey was completed by 83 participants in which they were asked to make hypothetical choices regarding returning back to an age they preferred or remaining at their current age prior to dying. In addition, participants completed surveys measuring quality of life, death depression, and death anxiety. Results indicated that participants who reported low quality of life and experienced high depression and anxiety towards death responded more impulsively to the discounting survey, engaging in steeper discounting. Additionally, results indicated that a positive correlation between participants aged 30 to 50 years old and AUC exists, indicating that as age increases, impulsivity decreases. However, this same trend was not evident in participants over the age of 65, yielding no correlation. Strengths and limitations, implications of the current study’s findings, and opportunities for future research are discussed.

M.Sc. (Occupational Therapy), Faculty of Health Sciences, University of the Witwatersrand, 2009 / A uniform taxonomy within occupational therapy has become a recent focus of discussion and concern in the literature. This study investigated inconsistency in the literature and how South African occupational therapists use and understand terms related to motor performance in children with developmental motor delay. A three stage Delphi Technique was used to gain consensus on the association of characteristics of movement to six motor component terms. The results yielded both quantitative and qualitative data, which revealed that while there was strong consensus among the occupational therapists on some aspects of motor terminology, there is still ambiguity and overlap of understanding. This is reflected in a worrying inconsistency of the description of these terms in the literature and how occupational therapists use the terms in clinical practice. A Framework of Uniform Motor Terminology was developed based on the results of the Delphi Technique.

The relationship between play gesture performance and language milestones was examined for 6 children with cleft lip and/or palate at 20, 24, and 30 months of age. Standardized measures of language development, language samples, and a play gesture protocol were administered and analyzed at each assessment. Results showed language delays for several of the children with cleft palate and displayed a complex relationship between play and language development. The results show parallels between single object use and vocabulary development as well as sequential play gestures and structural aspects of language use. Data from this study demonstrated slow play gesture and language development for children with cleft palate only.

The purpose of this study was to determine if a relationship existed between arrival time in coming to take the ACT test and academic achievement. The individuals who met the general criteria were used in this study numbered 129; 46 of these met the additional criteria of arriving early and they composed the early group. The early and late groups were compared on ACT composite score and cumulative grade point average. Significant differences between the means could not be found, by analysis of variance; between the early and late groups using either ACT composite score or cumulative grade point average.