Este trabalho apresenta um sistema de conferência multiponto centralizada com controle de posse da palavra, que oferece comunicação por voz e por texto, desenvolvido para dar suporte a ferramentas de educação a distância baseadas em tecnologia web. Além do sistema de conferência multiponto, este trabalho introduz, também, conceitos de voz sobre IP (VoIP), codecs de áudio, tráfego de tempo real sobre redes IP, mecanismos de distribuição de pacotes em redes IP, conferências multimídia sobre redes IP, criação e controle de conferências e mecanismos para se controlar a transmissão de pacotes de voz em conferências multiponto, como detecção de atividade de voz (VAD) e controle de posse da palavra. O controle de posse da palavra ou moderação é uma metodologia para coordenar o acesso a recursos de mídia contínua, como os canais de áudio e vídeo em conferências, resolvendo eventuais conflitos e condições de corrida e garantindo o uso exclusivo dos mesmos por um participante da conferência. O controle de posse da palavra é apropriado para a dinâmica de uma sala de aula, onde na maioria das vezes, o professor exerce o papel de um moderador e de principal interlocutor. Além de regular o fluxo de informação na sala de aula virtual, o controle de posse da palavra também ajuda a reduzir a utilização dos recursos da rede. Como principal resultado deste trabalho, uma arquitetura para o sistema de conferência multiponto foi proposta, implementada e testada. Verificou-se que o sistema é escalável e que o controle de posse da palavra reduz o grau de interatividade entre os participantes da conferência, mas funciona eficazmente como mecanismo para reduzir a utilização dos recursos de rede. A comunicação adicional por texto ajuda a reduzir o impacto do controle de posse da palavra no grau de interatividade. Neste trabalho, o uso de uma topologia centralizada para a realização de conferências multiponto mostrou-se bastante vantajoso, principalmente porque o tráfego multicast não era suportado. / This work presents a centralized multipoint conference system with floor control, which offers voice and text communication capability, developed to support distance learning tools based on web technology. This work also brings concepts about voice over IP (VoIP), audio codecs, real-time traffic over IP networks, packet distribution mechanisms in IP networks, multimedia conferences over IP networks, establishment and control of conferences and mechanisms to control voice packets transmission in multipoint conferences, as Voice Activity Detection (VAD) and floor control. Floor control is a suitable methodology for coordinating access to continuous media resources, such as audio and video channels in conferences, solving resource conflicts and race conditions and guaranteeing their mutually exclusive use by one participant of the conference. Floor control is appropriate for the classroom’s dynamics, where the teacher, mostly, has the role of a moderator and main talker. Besides regulating the information flow in the virtual classroom, floor control helps reducing the need for network resources. As main result, an architecture for the multipoint conference system was proposed, implemented and tested. It was found that the system is scalable and that floor control reduces the interactivity among the conference’s participants, but works efficiently as a mechanism for reducing the need for network resources. Text communications help lowering the impact of floor control on interactivity. In this work, the deployment of a centralized topology for multipoint conferences showed to be very advantageous, mainly because multicast traffic was not supported.

Este trabalho apresenta um sistema de conferência multiponto centralizada com controle de posse da palavra, que oferece comunicação por voz e por texto, desenvolvido para dar suporte a ferramentas de educação a distância baseadas em tecnologia web. Além do sistema de conferência multiponto, este trabalho introduz, também, conceitos de voz sobre IP (VoIP), codecs de áudio, tráfego de tempo real sobre redes IP, mecanismos de distribuição de pacotes em redes IP, conferências multimídia sobre redes IP, criação e controle de conferências e mecanismos para se controlar a transmissão de pacotes de voz em conferências multiponto, como detecção de atividade de voz (VAD) e controle de posse da palavra. O controle de posse da palavra ou moderação é uma metodologia para coordenar o acesso a recursos de mídia contínua, como os canais de áudio e vídeo em conferências, resolvendo eventuais conflitos e condições de corrida e garantindo o uso exclusivo dos mesmos por um participante da conferência. O controle de posse da palavra é apropriado para a dinâmica de uma sala de aula, onde na maioria das vezes, o professor exerce o papel de um moderador e de principal interlocutor. Além de regular o fluxo de informação na sala de aula virtual, o controle de posse da palavra também ajuda a reduzir a utilização dos recursos da rede. Como principal resultado deste trabalho, uma arquitetura para o sistema de conferência multiponto foi proposta, implementada e testada. Verificou-se que o sistema é escalável e que o controle de posse da palavra reduz o grau de interatividade entre os participantes da conferência, mas funciona eficazmente como mecanismo para reduzir a utilização dos recursos de rede. A comunicação adicional por texto ajuda a reduzir o impacto do controle de posse da palavra no grau de interatividade. Neste trabalho, o uso de uma topologia centralizada para a realização de conferências multiponto mostrou-se bastante vantajoso, principalmente porque o tráfego multicast não era suportado. / This work presents a centralized multipoint conference system with floor control, which offers voice and text communication capability, developed to support distance learning tools based on web technology. This work also brings concepts about voice over IP (VoIP), audio codecs, real-time traffic over IP networks, packet distribution mechanisms in IP networks, multimedia conferences over IP networks, establishment and control of conferences and mechanisms to control voice packets transmission in multipoint conferences, as Voice Activity Detection (VAD) and floor control. Floor control is a suitable methodology for coordinating access to continuous media resources, such as audio and video channels in conferences, solving resource conflicts and race conditions and guaranteeing their mutually exclusive use by one participant of the conference. Floor control is appropriate for the classroom’s dynamics, where the teacher, mostly, has the role of a moderator and main talker. Besides regulating the information flow in the virtual classroom, floor control helps reducing the need for network resources. As main result, an architecture for the multipoint conference system was proposed, implemented and tested. It was found that the system is scalable and that floor control reduces the interactivity among the conference’s participants, but works efficiently as a mechanism for reducing the need for network resources. Text communications help lowering the impact of floor control on interactivity. In this work, the deployment of a centralized topology for multipoint conferences showed to be very advantageous, mainly because multicast traffic was not supported.

Thesis (Ph.D. (Industrial Psychology))--North-West University, Vaal Triangle Campus, 2006.

No description available.

Cette étude visait principalement à examiner si le Contrôle (« Conscientiousness ») modère la relation prédictive entre différents facteurs de risque et le décrochage chez les adolescents. Les données de l’étude Stratégie d’Intervention Agir Autrement (SIAA) ont été employées. L’échantillon compte 1864 adolescents âgés de 15 ans provenant de 62 écoles secondaires québécoises. Des analyses de régression logistique ont confirmé le pouvoir prédictif de certains facteurs de risque connus du décrochage (indiscipline scolaire, statut socioéconomique faible, engagement scolaire faible, rendement scolaire faible, retard scolaire, désengagement scolaire des amis et des relations conflictuelles avec les enseignants). Les analyses ont aussi révélé que le Contrôle modère la relation entre les relations conflictuelles avec les enseignants et le décrochage et s’avère donc un facteur de vulnérabilité. En effet, un adolescent qui a un niveau élevé de Contrôle est plus à risque de décrocher lorsqu’il a des relations conflictuelles avec les enseignants. / This study’s main goal is to determine if Conscientiousness moderates the relation between risk factors and dropping out of high school. This project is a secondary analysis of the data from the “Stratégie d’Intervention Agir Autrement” (SIAA) study. The sample includes 1864 15 years old adolescents who go to 62 different high schools in Quebec. Logistic regression analyses confirmed the importance of different risk factors in high school dropping out such as disobedience in school, socioeconomic status, commitment to school, performance in school, grade retention, friends’ lack of school commitment, and conflicting relationships with teachers. Moreover, it was revealed that Conscientiousness moderated the relation between conflicting relationships with teachers and dropping out and was therefore a vulnerability factor. Indeed, an adolescent who has a high level of Conscientiousness is more at risk of dropping out when s/he has conflicting relationships with his or her teachers.

The information technology industry is considered to be one of the most demanding industries, with significant social, physical and psychological consequences for the wellbeing of the information technology professional. Work wellness and general psychological well-being plays an important role in the well-being of the information technology professional. The measurement of work-related wellness requires valid, reliable and culturally fair measuring instruments. However research on work wellness and occupational well-being in South Africa is lacking, especially in the information technology context. A lack of norms for work-related wellness in South Africa makes the identification of work-related wellness in the information technology industry difficult. Consequently, investigating the reliability, validity, equivalence and bias of work-related well-being measuring instruments would result in the standardisation of work wellness (consisting of burnout and engagement) and occupational well-being, suitable for use in the multicultural information technology industry setting. Moreover, the operationalisation of work wellness, as well as an inclusive model regarding the work-related wellness of information technology professionals that includes work wellness and occupational wellbeing are lacking in the South African literature. The objectives of this research were to standardise the measurement of work wellness for information technology professionals in South Africa, to develop and test a model of occupational well-being for information technology professionals in South Africa, to develop and test a comprehensive model of work-related wellness for information technology professionals in South Africa (consisting of work wellness and occupational well-being), and to test for moderating effects of affectivity in the experience of mark related well-being of information technology professionals in South Africa. The research consists of three separate articles, each consisting of a brief literature overview and an empirical study. A cross-sectional survey design with a snowball sample (n = 214) of information technology professionals in South Africa was used. Adapted versions of the Maslach Burnout Inventory - General Survey (MBI-GS) and Gtrecht Work Engagement Scale (UWES), as well as the Satisfaction with Life Scale (SWLS), Affectometer 2 (AFM-2), Life Orientation Test - Revised (LOT-R), Organisational Commitment Questionnaire (OC-Q), Information Technology Job Characteristics Inventory (ITJCI), as well as the Health scale of the Organisational Screening Evaluation Tool (ASSET) and a biographical questionnaire were used. Descriptive statistics, analysis of variance, correlations, exploratory factor analysis and structural equation modeling were used. Exploratory factor analysis confirmed a two-factor model for the MBI-GS consisting of a combined Burnout factor and Professional Efficacy, while a one-factor model was found for the UWES, namely Engagement, with acceptable internal consistencies. Exploratory second-order factor analysis confirmed a two-factor, culturally fair model of work wellness for information technology professionals in South Africa, consisting of burnout and work engagement. Item bias analysis revealed no evidence of bias for the MBI-GS, while uniform bias was found for two items (Items 7 and 12) of the UWES. Construct equivalence in terms of work wellness was obtained for the different language groups in the sample. The results confirmed a four-factor model of occupational well-being for information technology professionals in South Africa, namely negative and positive work wellness, organisational commitment and general psychological well-being. The model of occupational well-being was found to be equivalent across language groups, except for general psychological well-being, which seemed to differ for the non-mother-tongue English language speakers. In terms of work-related wellness, a model consisting of work wellness and occupational well-being was constructed and uccessfully tested. Structural equation analysis confirmed main effects for negative affectivity in terms of burnout and engagement, while main effects were confirmed for burnout, ill-health and engagement in terms of positive affectivity. Interaction effects for affectivity were not confirmed in the model of work-related wellness of information technology professionals in South Africa. Recommendations for the organisation and future research were made / Thesis (Ph.D. (Industrial Psychology))--North-West University, Vaal Triangle Campus, 2006.

The information technology industry is considered to be one of the most demanding industries, with significant social, physical and psychological consequences for the wellbeing of the information technology professional. Work wellness and general psychological well-being plays an important role in the well-being of the information technology professional. The measurement of work-related wellness requires valid, reliable and culturally fair measuring instruments. However research on work wellness and occupational well-being in South Africa is lacking, especially in the information technology context. A lack of norms for work-related wellness in South Africa makes the identification of work-related wellness in the information technology industry difficult. Consequently, investigating the reliability, validity, equivalence and bias of work-related well-being measuring instruments would result in the standardisation of work wellness (consisting of burnout and engagement) and occupational well-being, suitable for use in the multicultural information technology industry setting. Moreover, the operationalisation of work wellness, as well as an inclusive model regarding the work-related wellness of information technology professionals that includes work wellness and occupational wellbeing are lacking in the South African literature. The objectives of this research were to standardise the measurement of work wellness for information technology professionals in South Africa, to develop and test a model of occupational well-being for information technology professionals in South Africa, to develop and test a comprehensive model of work-related wellness for information technology professionals in South Africa (consisting of work wellness and occupational well-being), and to test for moderating effects of affectivity in the experience of mark related well-being of information technology professionals in South Africa. The research consists of three separate articles, each consisting of a brief literature overview and an empirical study. A cross-sectional survey design with a snowball sample (n = 214) of information technology professionals in South Africa was used. Adapted versions of the Maslach Burnout Inventory - General Survey (MBI-GS) and Gtrecht Work Engagement Scale (UWES), as well as the Satisfaction with Life Scale (SWLS), Affectometer 2 (AFM-2), Life Orientation Test - Revised (LOT-R), Organisational Commitment Questionnaire (OC-Q), Information Technology Job Characteristics Inventory (ITJCI), as well as the Health scale of the Organisational Screening Evaluation Tool (ASSET) and a biographical questionnaire were used. Descriptive statistics, analysis of variance, correlations, exploratory factor analysis and structural equation modeling were used. Exploratory factor analysis confirmed a two-factor model for the MBI-GS consisting of a combined Burnout factor and Professional Efficacy, while a one-factor model was found for the UWES, namely Engagement, with acceptable internal consistencies. Exploratory second-order factor analysis confirmed a two-factor, culturally fair model of work wellness for information technology professionals in South Africa, consisting of burnout and work engagement. Item bias analysis revealed no evidence of bias for the MBI-GS, while uniform bias was found for two items (Items 7 and 12) of the UWES. Construct equivalence in terms of work wellness was obtained for the different language groups in the sample. The results confirmed a four-factor model of occupational well-being for information technology professionals in South Africa, namely negative and positive work wellness, organisational commitment and general psychological well-being. The model of occupational well-being was found to be equivalent across language groups, except for general psychological well-being, which seemed to differ for the non-mother-tongue English language speakers. In terms of work-related wellness, a model consisting of work wellness and occupational well-being was constructed and uccessfully tested. Structural equation analysis confirmed main effects for negative affectivity in terms of burnout and engagement, while main effects were confirmed for burnout, ill-health and engagement in terms of positive affectivity. Interaction effects for affectivity were not confirmed in the model of work-related wellness of information technology professionals in South Africa. Recommendations for the organisation and future research were made / Thesis (Ph.D. (Industrial Psychology))--North-West University, Vaal Triangle Campus, 2006.

No description available.

Text in Afrikaans / Dr. J D Vorster het gedurende sy bedieningstyd in die N.G.Kerk [1935-1978] ontwikkel en gegroei tot 'n invloedryke kerkleier. Die faktore en omstanighede wat tot sy vorming bygedra het is die onderwerp van hierdie studie. Die f eit dat hy in die Stormberge gebore en getoe is asook .karaktereienskappe wat hy van sy voorsate geerf het, was belangrike komponente in sy vorming. Boustene soos godsdiens en volksliefde het in sy ouerhuis die grondslag gele vir sy teologiese beskouings wat op universiteit ontwikkel het. Sedert 1935 is hy in die bediening verder gevorm deur pastorale werk, kerklike vergaderings en briefwisselings. Kulturele en politieke betrokkenheid asook gevangenisstraf het horn bekend gemaak en gebrei. 'n Doktorsgraad in die Kerkreg was verder die regte skoling vir die amp va.n Aktuarius - 'n pos wat met soveel deeglikheid uitgevoer is dat hy later as kerkleier erken is met sy verkiesing as Moderator. / During his ministry in the D.R.Church, dr.J D Vorster developed and grew to become an influential church leader. The subject of this study is the factors and circumstances which contributed to his forming. The fact that he was born and bred in the Stormberge as well as the characteristics he inherited from his ancestors were important components in his forming. Building stones such as religion and nationalism in his parents home laid the .foundation of his theological views which developed at university. He was further formed in his ministry through pastoral work, church meetings and correspondence. Cultural and political participation as well as imprisonment made him well-known and tough. His doctorate in church law put him on the right track for the post of Actuary - an off ice which he filled with so much efficiency that his leadership in the church was recognised with his election as Moderator. / Christian Spirituality, Church History and Missiology / Th. M. (Church History)

This thesis aimed at examining the impact of decorative pictures, defined as pictures which make an instructional material aesthetically appealing rather than conveying information for learning. In research, the use of decorative pictures was considered to be detrimental for learning for a long time. In contrast, recent research revealed that the impact of these pictures is moderated by a number of variables. In a series of experiments which were based on cognitive-affective theories of learning with media, a selected number of theoretically derived moderators were examined in a series of experiments. A first experiment (N1 = 82) investigat-ed the effectiveness of different levels of emotional charge (positive vs. negative) and the impact of different contexts (learning context vs. leisure time context) shown in decorative pictures. Results showed that learning performance was higher for positive than negative pictures, while the measured pleasure of students mediated this effect. Decorative pictures showing a learning context were also found to enhance learning while the students’ assessments of arousal and dominance were raised for these pictures. In a second experiment (N2 = 81), design features of anthropomorphism, defined as features which elicit the tendency to attribute human characteristics to non-human objects, were implemented in decorative pictures. Based on a two-factorial design with the inclusion of human faces (present vs. absent) and personalized labels (present vs. absent), both human faces and personalized labels were found to foster learning. In comparison to a control group without decorative pictures (experiment 3; N3 = 102), the inclusion of both mentioned anthropomorphic features in decorative pictures led to a higher learning performance. In contrast, decorative pictures without anthropomorphic features decreased learning. Both features additionally enhanced the mental effort and intrinsic motivation of students, although a task-irrelevant cognitive load was increased by the inclusion of decorative pictures. The emotional charge (positive vs. negative) and the degree of text-picture connectedness (weakly vs. strongly) of decorative pictures were additionally examined in three other experiments (N4 = 108, N5 = 86, N6 = 162). Moreover, these groups were compared with an additional control group without decorative pictures. All three experiments revealed that decorative pictures with a strong connection to the learning topic of a text and a positive charge increased learning. In comparison with the control group, positive, strongly connected pictures mainly enhanced and negative, weakly connected pictures mainly impaired learning. Results can be explained by significant differences among the assessment of cognitive processes of learners. In conclusion, decorative pictures may be used in order to enrich an instructional material if boundary conditions like the context-relatedness, the degree of anthropomorphism, the text-picture connectedness, and the emotional charge are taken into account.:Zusammenfassung 4 Summary 6 1 Introduction 8 2 Theories of Learning with Text and Pictures 8 2.1 Cognitive Load Theory 8 2.2 Cognitive Theory of Multimedia Learning 9 2.3 Integrated Model of Text and Picture Comprehension 11 2.4 Cognitive-Affective Theories of Learning with Text and Pictures 12 3 The Role of (Decorative) Pictures in Learning with Media 15 3.1 Picture Taxonomies and the Function of Decoration 16 3.2 Decorative Pictures and Learning 18 3.3 Moderators of Decorative Pictures in Learning 18 3.4 Main Hypotheses 20 4. Methods 22 4.1 Participants and Experimental Designs 22 4.2 Pre-Studies and Instructional Materials 24 4.3 Learning Measures and Further Questionnaires 24 5 Results 26 5.1 Learning Results 26 5.2 Additional Results 28 6 General Discussion 29 6.1 Implications 30 6.2 Limitations and Future Directions 31 7 References 32 Article 1: „Decorative pictures and emotional design in multimedia learning” 38 Article 2: „Anthropomorphism in decorative pictures: Benefit or harm for learning?” 48 Article 3: “How affective charge and text-picture connectedness moderate the impact ….. of decorative pictures on multimedia learning” 64 Curriculum Vitae 116 Danksagung 119 Selbstständigkeitserklärung 120 / Die vorliegende Dissertation untersucht den Einfluss dekorativer Bilder, welche per Definition ein Lernmaterial eher ästhetisch schmücken als lernrelevante Informationen zu vermitteln. In der Forschung wurden solche Bilder bisher vorrangig als lernhinderlich betrachtet. Neuere Befunde weisen jedoch darauf hin, dass der Einfluss dieser Bilder einer Reihe von moderierenden Einflüssen unterliegt. Auf der Grundlage von verschiedenen Experimenten, welche auf kognitiv-affektiven Theorien des Lernens mit Medien beruhen, wurde eine ausgewählte Anzahl theoretisch abgeleiteter Moderatoren näher untersucht. In einem ersten Experiment (N1 = 82) wurden Einflüsse der emotionalen Ladung (positiv vs. negativ) sowie des dargestellten Lernkontexts (Lernkontext vs. Freizeitkontext) von dekorativen Bildern analysiert. Die Ergebnisse zeigen, dass sich das Lernergebnis durch positive Bilder im Kontrast zu negativen Bildern verbesserte, während dieser Effekt durch die Zufriedenheit der Studenten mediiert wurde. Auch dekorative Bilder mit einem Lernkontext erhöhten die Lernleistungen, während Lernende durch diese Bilder eine höhere Aktivierung sowie Dominanz angaben. Ein zweites Experiment (N2 = 81) bestimmte den Einfluss anthropomorphisierter Bestandteile von dekorativen Bildern, welche die Tendenz zur Attribution menschlicher Charakteristiken auf nicht-menschliche Objekte auslösen können. Auf der Grundlage eines zwei-faktoriellen Untersuchungsdesigns, gekennzeichnet durch die Einbettung von menschlichen Gesichtern (vorhanden vs. nicht-vorhanden) und personalisierter Beschriftungen (vorhanden vs. nicht-vorhanden), konnten menschliche Gesichter und personalisierte Beschriftungen die Lernleistungen erhöhen. Im Kontrast zu einer Kontrollgruppe ohne dekorative Bilder (Experiment 3, N3 = 102), erwies sich der Einsatz anthropomorphisierter Bilder als lernförderlich, wohingegen dekorative Bilder ohne anthropomorphisierte Bestandteile lernhinderlich waren. Beide Bestandteile erhöhten außerdem die wahrgenommene mentale Anstrengung sowie intrinsische Motivation der Lernenden, obwohl sich die lernirrelevante Belastung durch die Hinzunahme dekorativer Bilder erhöhte. Die emotionale Ladung (positiv vs. negativ) sowie der textliche Bezug (gering vs. hoch) von dekorativen Bildern wurden in drei weiteren Experimenten (N4 = 108, N5 = 86, N6 = 162) zusammen mit einer zusätzlichen Kontrollgruppe ohne dekorative Bilder untersucht. Jedes der drei Experimente ist ein Beleg für den lernförderlichen Einfluss dekorativer Bilder mit positiver Ladung und hohem Textbezug. Im Vergleich zur Kontrollgruppe, erweisen sich dekorative Bilder mit positiver Ladung und hohem Textbezug als lernförderlich, wobei dekorative Bilder mit geringem Textbezug und negativer Ladung also lernhinderlich nachgewiesen wurden. Einen Erklärungsansatz liefern zusätzlich gemessene kognitive Variablen. Zusammenfassend zeigt sich, dass dekorative Bilder durchaus lernförderlich beim Design von Lernmaterialien eingesetzt werden können, wenn moderierende Einflüsse, wie der dargestellte Lernkontext, der Grad der ausgelösten Anthropomorphisierung, der Textbezug, sowie die emotionale Ladung dekorativer Bilder beachtet werden.:Zusammenfassung 4 Summary 6 1 Introduction 8 2 Theories of Learning with Text and Pictures 8 2.1 Cognitive Load Theory 8 2.2 Cognitive Theory of Multimedia Learning 9 2.3 Integrated Model of Text and Picture Comprehension 11 2.4 Cognitive-Affective Theories of Learning with Text and Pictures 12 3 The Role of (Decorative) Pictures in Learning with Media 15 3.1 Picture Taxonomies and the Function of Decoration 16 3.2 Decorative Pictures and Learning 18 3.3 Moderators of Decorative Pictures in Learning 18 3.4 Main Hypotheses 20 4. Methods 22 4.1 Participants and Experimental Designs 22 4.2 Pre-Studies and Instructional Materials 24 4.3 Learning Measures and Further Questionnaires 24 5 Results 26 5.1 Learning Results 26 5.2 Additional Results 28 6 General Discussion 29 6.1 Implications 30 6.2 Limitations and Future Directions 31 7 References 32 Article 1: „Decorative pictures and emotional design in multimedia learning” 38 Article 2: „Anthropomorphism in decorative pictures: Benefit or harm for learning?” 48 Article 3: “How affective charge and text-picture connectedness moderate the impact ….. of decorative pictures on multimedia learning” 64 Curriculum Vitae 116 Danksagung 119 Selbstständigkeitserklärung 120