Abstract Peer-to-Peer (P2P) networking changes the way of people utilizing Internet, for example, sharing and consuming digital content, from the ground up. It continues to show its power and strength when it is combined with other emerging technologies, such as Web Services. This thesis contributes to the research and development of P2P networks from four aspects. Firstly, a P2P and Web Services converged multiple-tier system architecture is proposed. The architecture proposed enables providing Web Services in the context of heterogeneous access networks in an efficient way by utilizing P2P paradigm. A lightweight middleware architecture is introduced to fit the diversified mobile terminals. A theoretical analysis is given to provide a comparative study with the conventional centralized architecture. Secondly, a General Truncated Pyramid Peer-to-Peer (GTPP) architecture is presented to analyze the performance of hierarchical architecture compared with flat architecture. The motivation behind the GTPP architecture is to see whether an added tier can bring with it added value and functionality. A detailed mathematical analysis is provided which takes into consideration various performance metrics, including the lookup hopcount, lookup latency, maintenance traffic from a single peer point of view, and maintenance traffic from the whole system point of view. Furthermore, simulation results with respect to the lookup hopcount are also provided. Through mathematical analysis and simulation results, an optimal value regarding the number of tiers of the GTPP architecture is found, showing that 2~3 tiers are appropriate for most of situations. A specialized model is also proposed to improve the performance of hierarchical architecture. Thirdly, the performance evaluation of a communication-oriented Kademlia-based P2P system is provided in detail. NetHawk EAST-based simulation models and a prototype are both utilized to evaluate the performance. Simulation results from NetHawk EAST-based simulation models demonstrate the optimal design choices regarding the resource lookup parallelism degree and resource replication degree, and show the unnecessary existence of the messages used to detect the liveness of peers in a DHT overlay. Measurements from the prototype show the feasibility of mobile nodes acting as fully fledged overlay nodes from three different perspectives, namely CPU processing load, network traffic load, and battery consumption. The optimal size of packets which consumes battery in the most efficient way is also found through battery consumption measurements. Fourthly, the effects of different churn models on the performance of structured P2P networks are analyzed. Specifically, three typical churn models are analyzed to provide a comparative result. The simulation results show that the difference among the effects of different churn models on the performance of structured P2P networks is quantitative rather than qualitative. This provides some guidance for the selection of different churn models for the contemporary researchers.

Esta pesquisa tem por objetivo analisar e propor uma metodologia para o ensino de história. Tal metodologia considera duas características específicas das sociedades tecnológicas na inter-relação com as práticas escolares: a cultura midiática que o aluno e o professor carregam em seu interior para o interior da escola, e os processos de formação continuada do professor. Visa-se com tal metodologia colaborar com um ensino de história significativo para alunos e professores, e que a história seja instrumento de compreensão da vida cotidiana e processo contínuo de formação. A pesquisa possibilitou a elaboração de uma proposta teórico-metodológica denominada como atividade de ensino de história. Os referenciais teóricos que sustentam esta proposta são: a teoria da atividade de Aléxis Leontiev que se insere no conjunto da corrente histórico-cultural em psicologia; os pressupostos da pedagogia da comunicação que traz em seu interior o princípio didático do agir comunicacional; as pesquisas que analisam os conceitos de professor reflexivo-investigativo e o professor pesquisador; a historiografia que se identifica com a análise da cultura em diferentes temporalidades. Os referenciais teórico-metodológicos foram utilizados para analisar um conjunto de quatro atividades de ensino de história realizadas entre os anos de 1997-2000 em escolas da rede pública e particular de ensino da cidade de São Paulo. Os dados deste conjunto de aulas foram coletados pelo pesquisador que se serviu dos princípios metodológicos da pesquisa-ação. A análise dos dados à luz da fundamentação teórico-metodológica assumida possibilitou a explicitação de princípios orientadores da construção de atividades de ensino de história. Concluiu-se pela viabilidade de tal proposta e de sua inclusão nos debates sobre ensino de história. / The main goal of this research is to analyze and to propose a methodology for history teaching. Such methodology takes into account two specific characteristics of technological societies in the interrelationship with school practices: the media culture that both student and teacher bring along to school, and teachers continuing education process. Such methodology is intended to contribute towards a more meaningful teaching of History for both parties involved teachers and students in such a way that History becomes a more comprehensive tool in interpreting day-to-day events as well as a continuing education process. The research made it possible to elaborate a theoretical-methodological approach we called History teaching activity. The theoretical milestones upon which such approach is based are: Aléxis Leontiev´s theory of activity, which is part of the historic-cultural approach in psychology; the fundamentals of communication pedagogy and its didactic principle of a communication-oriented attitude; the research which analyzes the concepts of the investigative teacher and the researcher teacher; historiography which identifies itself with culture analysis in different periods in time. The theoretical-methodological references were used to analyze a set of four History teaching activities that took place along the years 1997 to 2000, in public and private schools in the city of São Paulo. The data of these classes were gathered by the researcher who then used the research-action methodological principles. The analysis of the data in the light of such theoretical-methodological principles made it possible for the researcher to show the principles that oriented the construction of History teaching activities. Such proposal was believed to be valid as well as its inclusion in the debate about history teaching.

Esta pesquisa tem por objetivo analisar e propor uma metodologia para o ensino de história. Tal metodologia considera duas características específicas das sociedades tecnológicas na inter-relação com as práticas escolares: a cultura midiática que o aluno e o professor carregam em seu interior para o interior da escola, e os processos de formação continuada do professor. Visa-se com tal metodologia colaborar com um ensino de história significativo para alunos e professores, e que a história seja instrumento de compreensão da vida cotidiana e processo contínuo de formação. A pesquisa possibilitou a elaboração de uma proposta teórico-metodológica denominada como atividade de ensino de história. Os referenciais teóricos que sustentam esta proposta são: a teoria da atividade de Aléxis Leontiev que se insere no conjunto da corrente histórico-cultural em psicologia; os pressupostos da pedagogia da comunicação que traz em seu interior o princípio didático do agir comunicacional; as pesquisas que analisam os conceitos de professor reflexivo-investigativo e o professor pesquisador; a historiografia que se identifica com a análise da cultura em diferentes temporalidades. Os referenciais teórico-metodológicos foram utilizados para analisar um conjunto de quatro atividades de ensino de história realizadas entre os anos de 1997-2000 em escolas da rede pública e particular de ensino da cidade de São Paulo. Os dados deste conjunto de aulas foram coletados pelo pesquisador que se serviu dos princípios metodológicos da pesquisa-ação. A análise dos dados à luz da fundamentação teórico-metodológica assumida possibilitou a explicitação de princípios orientadores da construção de atividades de ensino de história. Concluiu-se pela viabilidade de tal proposta e de sua inclusão nos debates sobre ensino de história. / The main goal of this research is to analyze and to propose a methodology for history teaching. Such methodology takes into account two specific characteristics of technological societies in the interrelationship with school practices: the media culture that both student and teacher bring along to school, and teachers continuing education process. Such methodology is intended to contribute towards a more meaningful teaching of History for both parties involved teachers and students in such a way that History becomes a more comprehensive tool in interpreting day-to-day events as well as a continuing education process. The research made it possible to elaborate a theoretical-methodological approach we called History teaching activity. The theoretical milestones upon which such approach is based are: Aléxis Leontiev´s theory of activity, which is part of the historic-cultural approach in psychology; the fundamentals of communication pedagogy and its didactic principle of a communication-oriented attitude; the research which analyzes the concepts of the investigative teacher and the researcher teacher; historiography which identifies itself with culture analysis in different periods in time. The theoretical-methodological references were used to analyze a set of four History teaching activities that took place along the years 1997 to 2000, in public and private schools in the city of São Paulo. The data of these classes were gathered by the researcher who then used the research-action methodological principles. The analysis of the data in the light of such theoretical-methodological principles made it possible for the researcher to show the principles that oriented the construction of History teaching activities. Such proposal was believed to be valid as well as its inclusion in the debate about history teaching.

Since the publication of Dr. Johnson’s first English dictionary in 1755, there have been rapid changes in the development of dictionaries in other parts of the world. However, the advances are perceived more in other languages of the world such as the European languages while in Africa, the changes have been very slow. The majority of dictionaries utilised by most Africans are bilingual and were produced by the missionaries. These dictionaries were aimed at serving the needs of the missionaries, but more recently African scholars have been trying to create dictionaries that are intended to meet the needs of the native speakers particularly because the existing dictionaries contain many words which are archaic or going out of use. This means that the currently produced dictionaries should reflect the changes that have occurred in languages and society. The two dictionaries under scrutiny, Sesuto-English Dictionary and Sethantšo sa Sesotho, share similar content as if they were both targeting the same generation even though the former was written by missionaries in the 19th century while the latter was created by a Sesotho native speaker in the 21st century. This study aimed to establish whether the two dictionaries are the same or not, or whether Sethantšo sa Sesotho had been derived from Sesuto-English Dictionary as well as whether the two dictionaries meet the needs of the contemporary users. The study employed adaptation theory in order to discover the originality of Sethantšo sa Sesotho. User-perspective approach and communication-oriented function were utilised to judge the effectiveness of the two dictionaries in reading and writing and to analyse users’ views. The study established that Sethantšo sa Sesotho has adapted 69% lexical items from Sesuto-English Dictionary; words are arranged in a similar order in both dictionaries with slight differences here and there; most definitions and illustrative phrases/sentences are the same even though the author of Sethantšo sa Sesotho did not acknowledge using any written source of information, thus violating the principles of adaptation; use of these dictionaries during reading and writing was found to be beneficial to users; and both dictionaries lack current words which users encounter daily. / African Languages / D. Litt. et Phil.(African Languages)

Research on self-efficacy has been a productive field and abundant research has shown that teachers’ self-efficacy beliefs influence teachers’ actions and performances and thus affect students’ learning outcomes. However, there is a lack of literature on EFL teachers’ self-efficacy beliefs and even less research was set in Chinese EFL contexts. On the one hand, this study was conducted to provide a general picture of the current status of EFL teachers’ perceived English proficiency, self-rated self-efficacy beliefs and self-reported teaching practices in terms of some demographic perspectives; On the other hand, it aimed to explore the correlations among Chinese primary EFL teachers’ perceived English proficiency, self-efficacy beliefs and teaching practices. The quantitative study surveyed 217 in-service primary EFL teachers. The descriptive results showed that: (1) EFL teachers varied in perceived English proficiency in terms of age, years of teaching experience and college major; (2) age and teaching experience did while college major didn’t make a difference for EFL teachers’ self-efficacy beliefs; (3) the surveyed EFL teachers, in general, had a greater preference to communication-oriented language teaching (COLT) than form-oriented language teaching (FOLT). The results from the correlational statistics showed that: (1) perceived English proficiency (PEP), on the whole, had a significant predictive effect on self-efficacy beliefs (SEB). It was striking that among the four skills (listening, speaking, reading, and writing) of English language, speaking had the most significant predictive effect on self-efficacy beliefs; (2) EFL teachers’ self-efficacy beliefs (SEB) had a predictive effect on COLT practices whereas not on FOLT practices; (3) The mediation model of showing the causal impacts of PEP (through SEB) on COLT was tested. i.e. Chinese primary EFL teachers’ self-efficacy beliefs played a complete mediating role between perceived English proficiency and communication-oriented language teaching. The findings of the present study added on the compelling evidence that self-efficacy beliefs matter in the realm of primary EFL teaching in China. In light of these findings, implications were generated to primary EFL teacher education and in-service EFL teacher training programs, such as courses related to improving English proficiency, especially speaking skills, should be offered for non-English major EFL teachers; training courses related to improving self-efficacy beliefs, especially on classroom management strategies, and the recommended communicative-oriented language teaching practices should be offered to pre-service and inexperienced in-service EFL teachers.