This thesis is concerned with the dynamical evolution of globular star clusters modelled as the classical gravitational N-body problem. The models in this thesis are idealised in order to allow the detailed study of particular dynamical aspects of the cluster evolution. Examples of properties which tend to be omitted are stellar evolution, primordial binaries and the effect of an external tidal gravitational field. The methods used in this thesis are gas models, N-body models and physical arguments. One of the main topics in this thesis is gravothermal oscillations in multicomponent star clusters. The evolution of one-component globular clusters, systems with equal particle masses, is quite well understood. However, the evolution of more realistic globular clusters, with a range of particle masses, is a much more complicated matter. The condition for the on-set of gravothermal oscillations in a one-component system is simply that the number of stars is greater than a certain number ( ≈7000). In a multi-component system the relationship between the number of stars at which the gravothermal oscillations first appear and the stellar mass distribution of a cluster is a complex one. In order to investigate this phenomenon two different types of multi-component systems were studied: two-component systems (the simplest approximation of a mass spectrum, Chapter 2) and ten-component systems (which were realisations of continuous power law IMFs, Chapter 3). In both cases the critical number of stars at which gravothermal oscillations first appear are found empirically for a range of stellar mass distributions. The nature of the oscillations themselves are investigated and it is shown that the oscillations can be understood by focusing on the behaviour of the heavier stars within the cluster. A parameter Nef (de nined Mtot/mmax where Mtot is the total mass and mmax is the maximum stellar mass) acts as an approximate stability boundary for multicomponent systems.The stability boundary was found to be at Nef ~- 12000. In this Chapter 4, globular star clusters which contain a sub-system of stellar-mass black holes (BH) are investigated. This is done by considering two-component models, as these are the simplest approximation of more realistic multi-mass systems, where one component represents the BH population and the other represents all the other stars. These systems are found to undergo a long phase of evolution where the centre of the system is dominated by a BH sub-system. After mass segregation has driven most of the BH into a compact sub-system, the evolution of the BH sub-system is found to be in uenced by the cluster in which it is contained. The BH sub-system evolves in such a way as to satisfy the energy demands of the whole cluster, just as the core of a one component system must satisfies the energy demands of the whole cluster. The BH sub-system is found to exist for a significant amount of time. It takes approximately 10trh;i, where trh;i is the initial half-mass relaxation time, from the formation of the compact BH sub-system up until the time when 90% of the sub-system total mass is lost (which is of order 103 times the half-mass relaxation time of the BH sub-system at its time of formation). Based on theoretical arguments the rate of mass loss from the BH sub-system (M2) is predicted to be (βζM)/(αtrh): where M is the total mass, trh is the half-mass relaxation time, and α, β, ζ are three dimensionless parameters. (see Section 4.3 for details). An interesting consequence of this is that the rate of mass loss from the BH sub-system is approximately independent of the stellar mass ratio (m2/m1) and the total mass ratio (M2/M1) (in the range m2/m1 ≥ 10 and M2/M1 ≈ 10-2, where m1, m2 are the masses of individual low-mass and high-mass particles respectively, and M1, M2 are the corresponding total mass). The theory is found to be in reasonable agreement with most of the results of a series of N-body simulations, and all of the models if the value of ζ is suitable adjusted. Predictions based on theoretical arguments are also made about the structure of BH sub-systems. Other aspects of the evolution are also considered such as the conditions for the onset of gravothermal oscillation. The final chapter (Chapter 5) of the thesis contains some concluding comments as well as a discussion on some possible future projects, for which the results in this thesis would be useful.

This study investigates the degree to which the cumulative risk index predicted school readiness in a Head Start population. In general, the reviewed studies indicated the cumulative risk model was efficacious in predicting adverse developmental outcomes. This study built on this literature by investigating how child, parent, and family risk factors predicted school readiness in Head Start children using two statistical models. Specific aims of this study included identifying 1) to what degree multiple predictors contributed to school readiness and 2) to what degree the cumulative risk index contributed to school readiness. Participants included 176 Head Start children ages 3 to 5 years. Data were analyzed using multivariate regression to determine if the cumulative risk model was a stronger predictor of school readiness than any risk factor in isolation. Hierarchical regression was also utilized to determine if individual risk factors contributed anything above and beyond the sum, the cumulative risk index. Multiple regression analysis revealed that older age and previous enrollment in Head Start predicted higher scores, while low income predicted lower scores, as did taking the test in Spanish. Analysis also revealed that higher scores on the cumulative risk index predicted lower test scores. The analysis revealed that the individual risk factors did not contribute to the model above and beyond the cumulative risk index. Adding the individual risk factors did not account for more variance than using gender, age, and the cumulative risk index as the only predictors. Similarly, the cumulative risk index did not account for more variance than using age and gender as the only predictors. The current study adds empirical support to the continued use of the cumulative risk model in predicting adverse developmental outcomes.

This study investigates the degree to which the cumulative risk index predicted school readiness in a Head Start population. In general, the reviewed studies indicated the cumulative risk model was efficacious in predicting adverse developmental outcomes. This study built on this literature by investigating how child, parent, and family risk factors predicted school readiness in Head Start children using two statistical models. Specific aims of this study included identifying 1) to what degree multiple predictors contributed to school readiness and 2) to what degree the cumulative risk index contributed to school readiness. Participants included 176 Head Start children ages 3 to 5 years. Data were analyzed using multivariate regression to determine if the cumulative risk model was a stronger predictor of school readiness than any risk factor in isolation. Hierarchical regression was also utilized to determine if individual risk factors contributed anything above and beyond the sum, the cumulative risk index. Multiple regression analysis revealed that older age and previous enrollment in Head Start predicted higher scores, while low income predicted lower scores, as did taking the test in Spanish. Analysis also revealed that higher scores on the cumulative risk index predicted lower test scores. The analysis revealed that the individual risk factors did not contribute to the model above and beyond the cumulative risk index. Adding the individual risk factors did not account for more variance than using gender, age, and the cumulative risk index as the only predictors. Similarly, the cumulative risk index did not account for more variance than using age and gender as the only predictors. The current study adds empirical support to the continued use of the cumulative risk model in predicting adverse developmental outcomes.

Social-emotional development in preschoolers often functions as a gateway into more advanced social and academic behaviors; social-emotional experiences during the preschool years may enhance or diminish a child’s later adjustment and academic outcome. With the current focus on promoting pre-academic skills in preschool programs, the importance of social-emotional development has been left behind. The U.S. Department of Health and Human Services requires initial and follow-up screening of academic readiness skills for the Head Start programs. At the same time, much of the research that relates social-emotional development to academic outcome was completed 20 to 30 years ago. This study examined the relation between academic skills and social-emotional development in the beginning and end of one school year. Approximately 150 children ages 3 to 5 years old were assessed in six Head Start centers in different cities in rural Texas. Each student participated in an academic screening within the first 45 days of school and again at the end of the school year. A parent and teacher also completed a rating scale on each student’s social and emotional skills at the beginning of school. The purpose of this study was to contribute to a better understanding of the impact social-emotional development has on the academic progress for preschool-aged children. The overall goal of this study was to determine the extent to which socialemotional development can predict school readiness in Head Start children. The central hypothesis of this study was that social-emotional development can facilitate or impede children’s academic progress. This project was a prospective, repeated measures, singlesample design. The Head Start children who participated in this study were assessed at the beginning and end of the school year. Gain scores were used to measure the growth in academic skills over one school year and compared to initial social-emotional skill level. Results suggest a relationship between adaptive skills and academic gains in one year is evident in Head Start children, which indicates the importance of continuing to provide services and funding for services that go beyond the basic academic tasks. This study found that social-emotional development influences many vital attributes in a child’s growth, including academic success.

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1973. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Zugl.: Clausthal, Techn. Univ., Diss., 2009

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Sept. 18, 2008). PDF text: iv, 127 p. : ill. ; 573 K. UMI publication number: AAT 3303505. Includes bibliographical references. Also available in microfilm and microfiche formats.

Most studies of multinational organisations (MNE’s) have been focused on large mature corporations. Traditional literature explains that firms internationalise after a certain level of domestic maturity and wield a significant amount of economic power to withstand the threat of international competition (Oviatt, McDougall, 1993, p. 29)However, this premise has changed in recent years with the adoption of new legislation and technologies that allow firms to become established MNE’s much sooner, with many of these pursuing rapid internationalisation strategies.If the traditional notions of staged theory no longer hold true and new behavioural aspects are driving small businesses to internationalise, it is essential for researchers to gain insights into new firm development, survival and growth in the South African context. Firm growth is of particular interest where globalised SME’s are concerned. / Dissertation (MBA)--University of Pretoria, 2012. / Gordon Institute of Business Science (GIBS) / unrestricted