Hoy en día existen varias tecnologías que coexisten en una misma zona formando un sistema heterogéneo. Además, este hecho se espera que se vuelva más acentuado con todas las nuevas tecnologías que se están estandarizando actualmente. Hasta ahora, generalmente son los usuarios los que eligen la tecnología a la que se van a conectar, ya sea configurando sus terminales o usando terminales distintos. Sin embargo, esta solución es incapaz de aprovechar al máximo todos los recursos. Para ello es necesario un nuevo conjunto de estrategias. Estas estrategias deben gestionar los recursos radioeléctricos conjuntamente y asegurar la satisfacción de la calidad de servicio de los usuarios. Siguiendo esta idea, esta Tesis propone dos nuevos algoritmos. El primero es un algoritmo de asignación dinámica de recusos conjunto (JDRA) capaz de asignar recursos a usuarios y de distribuir usuarios entre tecnologías al mismo tiempo. El algoritmo está formulado en términos de un problema de optimización multi-objetivo que se resuelve usando redes neuronales de Hopfield (HNNs). Las HNNs son interesantes ya que se supone que pueden alcanzar soluciones sub-óptimas en cortos periodos de tiempo. Sin embargo, implementaciones reales de las HNNs en ordenadores pierden esta rápida respuesta. Por ello, en esta Tesis se analizan las causas y se estudian posibles mejoras. El segundo algoritmo es un algoritmo de control de admisión conjunto (JCAC) que admite y rechaza usuarios teniendo en cuenta todas las tecnologías al mismo tiempo. La principal diferencia con otros algorimos propuestos es que éstos últimos toman las dicisiones de admisión en cada tecnología por separado. Por ello, se necesita de algún mecanismo para seleccionar la tecnología a la que los usuarios se van a conectar. Por el contrario, la técnica propuesta en esta Tesis es capaz de tomar decisiones en todo el sistema heterogéneo. Por lo tanto, los usuarios no se enlazan con ninguna tecnología antes de ser admitidos. / Calabuig Soler, D. (2010). Common Radio Resource Management Strategies for Quality of Service Support in Heterogeneous Wireless Networks [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/7348

Cette thèse apporte une lumière sur divers aspects du financement par émission d’obligations convertibles sur le marché ouest européen entre 1994 et 2016. La première étude analyse la réaction du marché à l’annonce d’obligations convertibles en période de crise. Nos résultats montrent une réaction significativement plus négative en période de crise qu’en période normale. L’étude des déterminants de cette réaction indique que les investisseurs intègrent le potentiel des obligations convertibles à réduire les coûts de financement externes. Cependant, la réaction négative du marché est au moins partiellement due à la suspicion d’une possible surévaluation de l’émetteur et cette suspicion est exacerbée en périodes de crise financière. Par ailleurs, nous montrons qu’une part de la réaction négative enregistrée à l’annonce des convertibles est probablement due aux ventes à découvert opérées par les arbitragistes. La deuxième étude de cette thèse teste la théorie du financement séquentiel de Mayers (1998) qui prédit que le recours aux obligations convertibles permet de financer de façon optimale des investissements séquentiels. Nous évaluons l’importance du call émetteur dans la mise en œuvre optimale du financement séquentiel en comparant les activités de financement et d’investissement des firmes ayant rappelées par anticipation leurs obligations convertibles à celles d'entreprises du même secteur les ayant remboursées normalement à leur échéance. Nos résultats indiquent que la clause de rachat anticipé permet aux émetteurs de minimiser les coûts d’émissions et signale une stratégie de financement séquentiel sous sa forme « forte ». De plus, le modèle des doubles différences indique que les firmes ayant rappelées leurs convertibles par anticipation investissent plus que les entreprises les ayant remboursées normalement aux dates de rappel et ce en considérant les effets temporels et autres variables de contrôle. Le dernier chapitre de cette thèse traite de la politique de remboursement anticipé des obligations convertibles. Nous montrons à l’instar des études précédentes que les firmes retardent le rappel de leurs convertibles par rapport au point optimal de rappel préconisé par Ingersoll (1977). L’analyse des différentes théories justifiant le rappel tardif des obligations convertibles débouche sur des résultats cohérents avec l’hypothèse de détresse financière mais rejette celles liées à l’existence de la période de notification. / This thesis focuses on three aspects of convertible bonds financing using a Western European sample between 1994 and 2016. The first study of this thesis is related to the shareholder wealth effects at the announcement of the convertible bonds issuance during financial crises. We find that the market reaction is more negative during crises’ periods compared to that in normal periods. Analysis of the determinant of this reaction indicates that the market recognizes the potential of convertible bonds to reduce agency and adverse selection costs. However, we also find that the signal of overvaluation sent by the issuance mitigates the investors’ optimism about the ability of the convertible bonds to alleviate external financing costs and this bad signal is exacerbated during the financial crises. Furthermore, we find that firms that are short-sale constrained incur less negative market reaction. The second study tests the sequential financing theory of Mayers (1998) which supports that firms issue callable convertible bonds in order to implement optimal sequential financing strategy. We point out in this study the importance of the call provision by comparing the investment and financing activities of Western European firms that early called their convertible bonds to those in the same industry that redeemed their bonds at maturity. We find that the inclusion of such provision allows firms (callable convertible bonds issuers) to better control issuance costs and signals a “strong” sequential financing strategy. We also find that the calling firms invest more than the non-calling firms at the call date and the difference-in-differences model shows that this difference is due to the call decision, after controlling for time fixed effects and other control variables. The last chapter of this thesis addresses the issue of convertible bonds call delay. As previous studies, we find that the companies do not call their bond at the optimum point identified by Ingersoll (1977). Unlike previous researches in the same area, our study considers the main theoretical rationales for convertible bonds call delay. We find strong evidence for the financial distress hypothesis, little evidence for cash flow advantage and signaling theories but no evidence for the notice period justification.

Portable languages and distributed paradigms have driven a wave of new applications and processing models. One of the most promising, certainly from its early marketing, but disappointing (from its limited uptake)is the mobile agent execution and data processing model. Mobile agents are autonomous programs which can move around a heterogeneous network such as the Internet, crossing through a number of different security domains, and perform some work at each visited destination as partial completion of a mission for their agent user. Despite their promise as a technology and paradigm to drive global electronic services (i.e.any Internet-driven-and-delivered service, not solely e-commerce related activities), their up take on the Internet has been very limited. Chief among the reasons for the paradigm's practical under-achievement is there is no ubiquitous frame work for using Internet mobile agents, and non-trivial security concerns abound for the two major stake holders (mobile agent users and mobile agent platform owners). While both stake holders have security concerns with the dangers of the mobile agent processing model, most investigators in the field are of the opinion that protecting mobile agents from malicious agent platforms is more problematic than protecting agent platforms from malicious mobile agents. Traditional cryptographic mechanisms are not well-suited to counter the bulk of the threats associated with the mobile agent paradigm due to the untrusted hosting of an agent and its intended autonomous, flexible movement and processing. In our investigation, we identified that the large majority of the research undertaken on mobile agent security to date has taken a micro-level perspective. By this we mean research focused solely on either of the two major stakeholders, and even then often only on improving measures to address one security issue dear to the stake holder - for example mobile agent privacy (for agent users) or access control to platform resources (for mobile agent platform owners). We decided to take a more encompassing, higher-level approach in tackling mobile agent security issues. In this endeavour, we developed the beginnings of an infrastructural-approach to not only reduce the security concerns of both major stakeholders, but bring them transparently to a working relationship. Strategic utilisation of both existing distributed system trusted-third parties (TTPs) and novel mobile agent paradigm-specific TTPs are fundamental in the infrastructural framework we have devised. Besides designing an application and language independent frame work for supporting a large-scale Internet mobile agent network, our Mobile Agent Secure Hub Infrastructure (MASHIn) proposal encompasses support for flexible access control to agent platform resources. A reliable means to track the location and processing times of autonomous Internet mobile agents is discussed, withfault-tolerant handling support to work around unexpected processing delays. Secure,highly-effective (incomparison to existing mechanisms) strategies for providing mobile agent privacy, execution integrity, and stake holder confidence scores were devised - all which fit comfortably within the MASHIn framework. We have deliberately considered the interests - withoutbias -of both stake holders when designing our solutions. In relation to mobile agent execution integrity, we devised a new criteria for assessing the robustness of existing execution integrity schemes. Whilst none of the existing schemes analysed met a large number of our desired properties for a robust scheme, we identified that the objectives of Hohl's reference states scheme were most admirable - particularly real - time in - mission execution integrity checking. Subsequently, we revised Hohl's reference states protocols to fit in the MASHIn framework, and were able to overcome not only the two major limitations identified in his scheme, but also meet all of our desired properties for a robust execution integrity scheme (given an acceptable decrease in processing effiency). The MASHIn offers a promising new perspective for future mobile agent security research and indeed a new frame work for enabling safe and autonomous Internet mobile agents. Just as an economy cannot thrive without diligent care given to micro and macro-level issues, we do not see the security prospects of mobile agents (and ultimately the prospects of the mobile agent paradigm) advancing without diligent research on both levels.

Text in German and English / This MTh dissertation is about the meaning and change of the pastoral position and role as it is reflected in pastoral theological literature of the last thirty years. For this purpose different concepts of work satisfaction are described and applied to the pastoral context. Furthermore, results of empirical investigations among ministers in German speaking and various other countries are discussed and aspects of job satisfaction of pastors are presented. This is followed by an investigation of changing expectations regarding the pastoral role which affect the job satisfaction of a minister. A comparison of two church orders (1991 and 2003) from Chrischona Switzerland demonstrates the changing job descriptions of pastors within a freechurch denomination. The final chapter is a discussion of some pastoral theological consequences of the relation between changing job descriptions and job satisfaction. / Practical Theology / M.Th. (Practical Theology)

The context of this research is the coping and wellness of call centre agents in a characteristically high-stress work environment. The purpose of the study was to construct a psychological coping profile by investigating the relationship between individuals‘ wellness-related dispositional attributes and their resiliency-related behavioural capacities which has been under researched in a call centre work environment. A quantitative cross-sectional survey approach was followed. The population comprised predominantly of a non –probability sample of (N=409) predominantly early career permanently employed black females employed in call centres in Africa. Correlation and multivariate statistics highlighted cognitive (cynicism and hardy-control), affective (managing own emotions) and conative (hardy-commitment) behavioural elements that should be considered in the psychological coping profile of call centre agents. Age and gender were also shown to be significant moderators of the relationship between the wellness-related attributes and the resiliency-related capacities. The main findings are reported and interpreted in terms of an empirically derived psychological coping profile. The findings may provide valuable pointers for the design of wellness intervention practices which add to the body of knowledge concerned with employee wellness in call centres / Industrial & Organisational Psychology / D.Litt. et Phil. (Industrial and Organisational Psychology)

Thesis (MPhil (Modern Foreign Languages))--University of Stellenbosch, 2006. / Currently new teaching and learning paradigms are being called for in response to the ever increasing importance of the electronic media and information technologies, such as computers, in our daily lives and in education. In Language Teaching the reading of literary texts has received a lack of attention. The application developed for this study is an attempt to address this shortcoming. The application contains a reading programme which focuses on a German youth novel, Als aus Janusz Jan wurde by Herbert Somplatski, as well additional supporting texts, both literary and non-literary, and background information. By integrating this reading material into an interactive multimedia web-based computer application, it is hoped that it can be shown how reading can be made more attractive and effective in FLA (Foreign Language Acquisition). The application was designed against the background of current and planned South African syllabi for Second Additional Languages and by taking into account modern cognitive-constructivist learning theories, current requirements for multimedia design and CALL (Computer Assisted Language Learning) as well as various reading models and strategies. All these aspects regarding the design of the application and how they affect reading in FLA are discussed in this thesis. In addition a few prognostic suggestions are proposed.

Thesis (MPhil (Modern Foreign Languages))--University of Stellenbosch, 2008. / The continuing decline in Matriculation pass rates is a matter of concern for government, educators, parents and students in South African schools. According to official statistics, only 8% of South Africans are mother-tongue English speakers, yet English is the chief language of learning and teaching in South African schools. Researchers relate the poor pass rate to inadequate proficiency in English of both English First Additional Language learners and some of their teachers. Research has further revealed a significant positive correlation between reading comprehension and academic achievement. Consensus exists among researchers about the necessity of a basic vocabulary (variously estimated at 2000 to 3000 words and more) for developing the necessary reading comprehension. Theories and approaches regarding the development of vocabulary, however, are sometimes diametrically opposed to one another. Among the most conflicting theories are those which advocate the acquisition of vocabulary by guessing the meanings of words from the context as opposed to those favouring conscious and deliberate vocabulary teaching, which may include lists of words. The current study briefly investigates underlying problems, theories, methods and approaches to enhancing learners’ vocabularies. Conclusions are applied to the development of an interactive, multimedia program for improving learners’ functional vocabularies. The content of the program is based on authentic texts and simulations of situations which call for language interaction. This is supplemented with extracts from classical literary works and poetry and entertaining verses which present possibilities for use in vocabulary building.

Thesis (MPhil)--Stellenbosch University / ENGLISH ABSTRACT: The current level of literacy in South Africa is cause for concern. The Annual National Assessment of Literacy and Numeracy, conducted nationally by the National Department of Education of South Africa, shows that only 28% of Grade 3 learners and 35% of Grade 6 learners passed these tests in 2011 (Department of Basic Education (a), 2011). According to the policy on progression and promotion issued by the National Department of Education, learners may only be retained once in a phase, which means that these learners may lack essential academic literacy skills when they reach high school. The main concern addressed in this thesis is whether high school teachers can help improve academic literacy by using reading comprehension software, like Reading Rocket, as an intervention tool to help learners who struggle with reading comprehension, and whether Reading Rocket is in fact an effective program to use for such purposes. This study was conducted by using data from one school within the Western Cape which has been using Reading Rocket for the past three years. Use of the program forms part of their timetable, and Grade 8 and 9 learners spend twice per cycle working with the program. Learners are first tested on entering Grade 8 and group reports are retrieved from the program each term to monitor their progress. These reports give a summary of the reading level, the percentage gained in the reading exercises, reading speed in w.p.m and a spelling score in percentage. This data was used to compile a summary of the results obtained over six terms Term 1 2010 until Term 3 2011. These results were compared with quarterly classroom (paper‐based) comprehension and language tests in order to determine is a correlation between the program data and the paper‐based test data. There is no control group for this study as all the Grade 8 and 9 learners use the program. There is no conclusive evidence that the program is an effective intervention tool, but findings show a positive correlation between program data and paper‐based test data which indicates that the program may be used as a tool to determine on what grade level learners read. Given the numerous responsibilities and duties of teachers, it is essential that they are given an effective measuring tool for literacy and because computer software is essentially objective and time‐effective in provide results, using computer technology for such purposes may be part of a solution to improve literacy in South Africa. / AFRIKAANSE OPSOMMING: Die huidige toestand van geletterdheid in Suid‐Afrika is kommerwekkend. Resultate in 2011 van die jaarlikse nasionale assesseringstoetse vir geletterdheid en gesyferdheid wat nasionaal deur die Nasionale Onderwysdepartement gedoen word, wys dat net 28% van Graad 3‐leerders en 35% van Graad 6‐leerders hierdie toetse slaag (Department of Basic Education (a), 2011). Volgens die beleid van progressie en promosie van die Nasionale Onderwysdepartement mag leerders net eenkeer in ‚n schoolfase agtergehou word wat beteken dat bogenoemde leerders dalk nie die geleentheid het om voldoende te verbeter voordat hulle die hoërskoolfases betree nie. Die hoofkwessie wat in hierdie tesis aangespreek word is of hoërskoolonderwysers rekenaar sagteware soos Reading Rocket as ʼn intervensie metode kan gebruik om leerders se akademiese leesbegrip te verbeter, en of Reading Rocket wel ʼn effektiewe intervensiemiddel is. ʼn Studie is gedoen deur die data van een skool in die Wes‐Kaap te gebruik wat Reading Rocket al vir die afgelope drie jaar gebruik. Dit vorm deel van hulle skoolrooster en graad 8 en 9‐leerders spandeer twee keer per siklus aan die program. Groepverslae wat deur die program opgedateer word elke kwartaal getrek om progressie te monitor. Die verslae bevat ʼn opsomming van die leerders se leesvlak, leesbegrip in persentasie, leesspoed in w.p.m en ʼn persentasie vir spelling. Hierdie data is gebruik om ‘n opsomming saam te stel van die resultate oor ses kwartale (kwartaal 1 2010 tot kwartaal 3 2011). Die programresultate is vergelyk met resultate van klaskamer (papiergebaseerde) begripstoetse en eksamens wat hulle vir dieselfde kwartale geskryf het. Omdat al die graad 8 en 9‐leerders aan die program blootgestel word, is daar nie ʼn kontrolegroep vir die studie nie. Daar is nie konkrete bewys dat die program ʼn effektiewe intervensiemiddel is nie, maar statistieke wys wel dat daar ʼn positiewe korrelasie tussen die programdata en die papiergebasseerde data is en daarom word die gevolgtrekking gemaak dat die program wel as ʼn instrument kan gebruik word om die leerders se leesbegrip op enige stadium van die jaar te toets. Weens vele verantwoordelikhede is dit essensieel dat onderwysers ʼn effektiewe metingsinstrument vir leesbegrip tot hulle beskikking het. Omdat rekenaarsagteware soos Reading Rocket tydbesparend en objektief in die voorsiening van resultate is, mag die gebruik van sulke tegnologie deel van ʼn plan vorm om geletterdheidsvlakke in Suid‐Afrika te verbeter.

Thesis (MPhil (Modern Foreign Languages))--University of Stellenbosch, 2009. / The evaluation and selection of software is a complex undertaking best performed by those with applicable specialised skills and knowledge. When it comes to a field like CALL, which draws on the theory and best practice of a variety related disciplines, language teachers in the South African FET sector are unlikely to possess those specialised skills and knowledge beyond language learning content. In an effort to make the evaluation and selection of CALL software a more productive process, the literature pertaining to the components that constitute CALL and the South African FET context was reviewed. Based on this an evaluation framework was developed incorporating all the crucial contextual elements. The choice of a framework as opposed to a checklist was motivated by a need to reflect context at a variety of levels, combined with the flexibility allowing customisation for use in a variety of language learning settings.

This thesis investigates drivers willingness to engage with a mobile phone while driving. Many studies have looked into the effects on driving performance that can result from phone usage, but few studies have directly considered what can encourage or inhibit phone engagement behaviours in the first place. An initial exploratory study (Study 1) was conducted, for which a photo elicitation interview (N=20) was designed and implemented. This aimed to find the extent to which factors influencing phone use transferred from out of the car to the driving environment. In particular, the study aimed to explore whether the driving environment could be considered unique. The results indicated that the high demands placed on the driver by the road environment clearly distinguished it from the other environments and the reported propensity to use a phone seemed to reflect this. Only factors which either changed the level of attention required by the task, such as a change in task demand as a result of changes in the traffic environment, had any substantial influence on willingness to engage. Driving may not be unique in terms of the overall factors influencing phone use but it is unique in the extent to which this particular factor seems to have such a strong bearing on interaction. Building on findings from Study 1, that the demand and attention required seemed to influence willingness to engage, it was noted that Fuller s (2005) Task Capability Interface model would serve as a useful framework for the remainder of the thesis. This model suggests that driver behaviour is dictated by the level of task difficulty perceived; an interaction between task demand and capability. Therefore, the effects these two elements might have on willingness to engage with mobile phones while driving were tested separately in the two remaining studies. Previous research suggested that task demand should comprise a combination of roadway demand and the intended phoning task. Study 2, therefore, experimentally tested the extent to which road demand and phone function intended to be used influenced drivers decisions to engage with their phone. Participants (N=20) viewed video clips of real road environments of varying demand. Rating scales were used by participants to rate their willingness to engage with various phone functions according to the scenario they had just viewed. It was found both roadway demand and phone functionality affected willingness to engage with a mobile phone whilst driving. There was a higher propensity to engage in phone use in road environments perceived to have a lower demand and lower propensity to engage in phone use in the highest demand scenarios. Answering a call was the most likely function to be engaged with by the participants and sending a text message was the least likely. The final study investigated how capability (comprising both phone and driving capability) influenced willingness to engage. Participants (N=40) were required to drive in a simulator under two conditions, simulated low and high road demand. Their willingness to interact with their phones, when faced with a number of phone tasks, was then observed. It was found that driving capability had an effect on willingness to engage in high demand scenarios with the less capable, novice, drivers having a higher propensity to engage with placing a call, sending a text message and reading a text message than the more experienced drivers. Novice drivers were willing to engage with some functions on their phone at possibly inappropriate times. It was further found that, in the simulated low demand road environment, phone capability influenced willingness to engage, with those who were more capable at placing a call and sending a text message found to be more willing to engage with these functions. The research reported in this thesis represents the first attempt in the literature to study, in depth, the factors which can influence phone engagement behaviour while driving. Novel contributions include investigating if factors influencing phone use transferred from out of the car to the driving environment. Further novel contributions included whether the phone function and road demand interact to influence willingness to engage and whether capability can affect phone engagement behaviour while driving. Extending the model developed by Fuller, the thesis offers an original model that describes the factors affecting phone engagement behaviour while driving. Suggestions are proposed for how the findings presented in this thesis can effectively be used and how future work should build on these initial foundations.