[pt] O ensino remoto estabelecido emergencialmente em função da pandemia de Covid-19 trouxe grandes desafios a educadores, que precisaram adequar as rotinas de ensino rapidamente para conduzir as aulas. No ensino em design, a experimentação material realizada em ambientes de laboratório de design é primordial para formação de estudantes de design de produtos que, por intermédio das construções físicas, exploram criativamente suas ideias ou as colocam em testes para a validação de conceitos e soluções de design, em um ambiente de ensino compartilhado por alunos, professores e profissionais técnicos. Esta dissertação apresenta o relato da experiência da autora na elaboração e implementação de alternativas de trabalho que permitiram a continuidade das práticas de experimentação material, por meio de representações físicas, em disciplinas amparadas pelo Laboratório de Modelos e Protótipos, pertencente ao curso de graduação em design de produtos, da PUC-Rio, no decorrer do isolamento social. O referencial teórico que sustenta a dissertação inclui autores como Donald Shön, Nigel Cross e Antônio Santoni Rugiu e por meio de metodologia participativa, utilizando pesquisa bibliográfica e documental, busca-se observar e refletir o lugar da experimentação em laboratórios de design e sobre os ensino aprendizados ocorridos nestes espaços, destacando-se a importância das representações físicas no desenvolvimento de projeto de produtos. Por fim, apresenta-se as propostas que foram implementadas em um contexto de ensino remoto emergencial, como forma de possibilitar que a rotina de trabalho dos alunos, em suas residências. / [en] The remote teaching established on an emergency basis due to the Covid-19 pandemic brought great challenges to educators, who needed to adapt teaching routines quickly to conduct classes. In design education, material experimentation carried out in design laboratory environments is essential for training students to design products that, through physical constructions, creatively explore their ideas or put them to tests for the validation of design concepts and solutions, in a teaching environment shared by students, teachers and technical professionals. This dissertation presents the report of the author s experience in the elaboration and implementation of work alternatives that allowed the continuity of the practices of material experimentation, through physical representations, in disciplines supported by the Laboratory of Models and Prototypes, belonging to the graduation course in design of products, from PUC-Rio, during social isolation. The theoretical framework that supports the dissertation includes authors such as Donald Shön, Nigel Cross and Antônio Santoni Rugiu and through participatory methodology, using bibliographical and documentary research, we seek to observe and reflect on the place of experimentation in design laboratories and on teaching -learning that took place in these spaces, highlighting the importance of physical representations in the development of product design. Finally, the proposals that were implemented in an emergency remote teaching context are presented, as a way to enable the students work routine, in their homes.

Argumentieren ist zentraler Bestandteil naturwissenschaftlicher Erkenntnisgewinnung. Dennoch gibt es bisher nur wenige Arbeiten, die untersuchen, wie Lernende auf der Grundlage selbstständig durchgeführter Experimente für bzw. gegen eine eigene Hypothese argumentieren. Vor diesem Hintergrund untersucht diese Arbeit, welchen Einfluss personale Faktoren (u. a. das Fachwissen und das situationale Interesse) und die Art der Lernumgebung (Realexperiment vs. Computersimulation) darauf nehmen, welche Typen von Argumenten verwendet werden. Ferner wird in dieser Arbeit untersucht, inwiefern die Verwendung dieser Argumentkategorien den Lernerfolg beeinflusst. Auf der Basis von Interviewdaten konnten zunächst für die vorgebrachten Argumente beim Wechseln bzw. Beibehalten eigener Hypothesen beim Experimentieren zehn Kategorien identifiziert werden (u. a. „Intuition“, „Expertenwissen“, „Messunsicherheiten“ sowie „Daten als Evidenz“). Zur quantitativen Erfassung wurde dann für die vier o. g. Argumentkategorien ein Likert-skaliertes Instrument entwickelt. Die aufgeführten Fragestellungen wurden schließlich in einer randomisierten Studie mit 938 Schülerinnen und Schülern untersucht. Bei der Untersuchung des Einflusses personaler Faktoren zeigt sich u. a., dass Lernende in einer Argumentation umso eher Daten als Evidenz heranziehen, je höher das fachliche Vorwissen ist. Die Verwendung dieser Argumentkategorie erhöht wiederum die Wahrscheinlichkeit dafür, dass Lernende nach dem Experimentieren eine fachlich adäquate Hypothese aufstellen. Dies impliziert, dass der Umgang mit experimentellen Daten und Beobachtungen im Physikunterricht stärker als bisher berücksichtigt werden muss, z. B. durch eine explizitere Förderung von Fähigkeiten zum Umgang mit experimentellen Daten. Bis auf einen gut erklärbaren Unterschied können grundlegende Unterschiede beim Experimentieren zwischen Gruppen, die mit einem Real- bzw. Computerexperiment gearbeitet haben, nicht belegt werden. / Argumentation from data and evidence evaluation is widely seen as a scientific core practice. One approach to engage students in a meaningful argumentation practice is to provide lab work situations where they can construct hypotheses on the basis of their own prior knowledge and consequently evaluate these hypotheses in light of self-collected data. However, until recently, only little research has analyzed students' argumentation from data. Against this backdrop this research seeks to identify: a) the influences of personal factors (such as content knowledge and situational interest); b) the type of learning environment as a situational factor (real vs. virtual experiment) on the use of different categories of argument (such as Intuition, Appeal to Authority, Measurement Uncertainties (explicit) and Data as Evidence); c) the influence of argumentation on learning outcomes through experimentation in school labs. First, an interview-study was used to identify the different types of arguments used by students. Analyses focused on the nature of justification in argument and revealed ten different categories students use while arguing for or against hypotheses. As a next step, four out of ten categories were operationalized by means of a Likert-scaled instrument to assess the use of different types of argument in a valid and reliable manner. The findings from a randomized study among 938 secondary school students in a lab work setting indicate, among others, that content knowledge is positively related to the use of data as evidence. Again, the use of data as evidence increases the probability of stating a correct hypothesis after conducting the experiment. This implies that the ability to deal with data and measurement uncertainties should be better fostered in physics classes. Besides one explicable difference, no evidence was found, which supports the hypothesis that students' argumentation would differ while working with hands-on materials vs. computer simulations.

Die Besonderheit der drahtlosen Kommunikation gegenüber den drahtgebundenen Netzwerken liegt im drahtlosen Übertragungsmedium. Aufgrund der Broadcast-Eigenschaft des Übertragungsmediums werden Nachrichten potentiell von allen Netzwerkstationen empfangen, welche sich in der Übertragungsreichweite des Senders aufhalten. Als Konsequenz können bei einem unsynchronisierten Medienzugriff mehrere Nachrichten beim Empfänger kollidieren und nicht korrekt empfangen werden. Dieses Phänomen wird auch als Interferenz bezeichnet. Um solche Interferenzen zu vermeiden, wurden spezielle Protokolle für den Medienzugriff in drahtlosen Netzen entwickelt. Ein solcher Ansatz für drahtlose Maschennetze ist die verteilte Kanalzuweisung. Bei der verteilten Kanalzuweisung werden sich nicht-überlappende Kanäle im verfügbaren Frequenzspektrum für Übertragungen verwendet, die auf dem gleichen Kanal Interferenzen erzeugen würden. Dieser Ansatz ist möglich, da die verwendeten Funktechnologien, wie zum Beispiel IEEE 802.11 (WLAN), mehrere nicht-überlappende Kanäle bereitstellen. Aufgrund der großen Verbreitung von IEEE 802.11, ist eine hohe Dichte von privaten wie kommerziellen Netzen im urbanen Raum die Norm. Diese räumlich überlappenden Netze konkurrieren um den Medienzugriff. Daher ist es für die Leistung von Kanalzuweisungsalgorithmen von großer Bedeutung, die Aktivität der externen Netze mit einzubeziehen. Die Leistung der vorgelegten Arbeit umfasst das Design, die Implementierung und Validierung von Modellen und Algorithmen zur Reduzierung von Interferenzen in drahtlosen Maschennetzen. Die Arbeit beinhaltet die Entwicklung eines Messungs-basierten Interferenzmodells, mit dem Interferenzabhängigkeiten der Maschenrouter untereinander effizient bestimmt werden können. Weiterhin wurde ein Algorithmus für die verteilte Kanalzuweisung entwickelt, der die Aktivität von externen Netzen berücksichtigt. Die Gesamtlösung wurde in einem großen drahtlosen Maschennetz experimentell validiert. / Due to the broadcast nature of the shared medium, wireless transmissions are potentially received by all network stations in the communication range of the sender. With an unsynchronized medium access, multiple transmissions may be active at the same time and thus interfere with each other. In consequence, multiple transmissions may collide at the receiver side and cannot be properly decoded. For this reason, protocols have been developed on the MAC layer to synchronize the medium access and thus reduce interference effects. One of these approaches in wireless mesh networks is channel assignment. The idea of channel assignment is to minimize the network-wide interference by utilizing non-overlapping channels for otherwise interfering wireless transmissions. This is feasible, since wireless mesh routers are usually equipped with multiple radios and commonly used wireless network technologies, such as IEEE 802.11, provide multiple non-overlapping channels. Since IEEE 802.11 operates in the unlicensed frequency spectrum, the dense distribution of private and commercial network deployments of WLANs in urban areas poses a new challenge. Co-located networks compete for the wireless medium, thus decreasing the achievable network performance in terms of throughput and latency. Therefore, an important issue for efficient channel assignment is to also address external interference The contributions of this dissertation comprise the design, implementation, and validation of models and algorithms to enable wireless multi-hop networks to become interference-aware. This includes a measurement-based interference model suitable for large-scale network deployments. A distributed channel assignment algorithm has been developed that considers external sources of interference. The overall solution has been experimentally validated in a large-scale wireless multi-hop multi-radio testbed and has significantly increased the network performance with regard to the network capacity.

The advent of 6th Generation (6G) wireless systems and the increasing demand for spectrum to accommodate a growing number of users and diverse services have necessitated novel ap- proaches to spectrum sharing. Among these approaches, distributed spectrum sharing offers the most flexibility by allowing real-time spectrum use based on user demand and network con- straints. However, this approach presents significant challenges due to the probabilistic nature of system dynamics and the autonomous behavior of each incumbent, which require advanced strategies to predict and manage spectrum usage effectively. Listen-Before-Talk (LBT) is the most widely adopted method for distributed spectrum sharing in unlicensed bands. While LBT has been extensively studied in the context of Wireless Fidelity (Wi-Fi), providing key insights into its performance under various conditions, its application in synchronized, slot-scheduled sys- tems like New Radio (NR) Unlicensed (NR-U) remains underexplored. This gap exists primarily due to the lack of hardware testbeds and system-level simulation platforms that are essential for evaluating the effectiveness of LBT in NR-U and for developing improved methods for operating in shared spectrums with deterministic worst-case delays. This thesis addresses the existing gap by proposing a reference architecture for spectrum sharing based on 5th Generation (5G) NR-U to facilitate further research and experimentation in distributed spectrum sharing. The approach taken in this thesis is threefold: (i) the establishment of a system architecture for an end-to-end 5G NR-U system based on existing work in hardware and simulation models; (ii) the realization of this system model on the Network Simulator 3 (ns-3) discrete-event simulator by leveraging developments from the 5G Long-Term Evolution (LTE) Enhanced Packet Core (EPC) Network Simulator (LENA) (5G-LENA) system architecture; and (iii) the conceptual design for implement- ing the Physical (PHY) layer of a 5G NR-U system using Software-Defined Radios (SDRs) and the OpenAirInterface (OAI) 5G software platform. A key novelty of this reference architecture is the proposed mitigation of LBT latency in split architectures with SDRs and General-Purpose Processors (GPPs). The LBT block is designed for implementation within the Field Program- ming Gate Array (FPGA) of Universal Software Radio Peripheral (USRP) SDRs, thereby enabling heterogeneous coexistence experimentation with Common Off-the-Shelf (COTS) Wi-Fi Access Points (APs). The thesis presents a simulation-based experiment that optimizes traffic manage- ment to improve the ability to serve delay-critical traffic in NR-U systems operating under ho- mogeneous coexistence conditions. The thesis then outlines a reference design for exploring heterogeneous coexistence between Wi-Fi and NR-U in the sub-7 GHz spectrum. This concep- tual framework leverages a proposed hardware experimentation platform with SDRs. The in- frastructure supporting these simulations and proposed hardware experiments is envisioned as virtualized resources over the Commonwealth Cyber Initiative (CCI) xG Testbed, with potential extensions for advanced spectrum sharing use cases across indoor and outdoor testbed sites. The thesis outlines potential enhancements to this testbed, specifically toward spectrum sharing with scheduled-access systems. / Master of Science / As wireless communication demand grows with the development of 6G, finding efficient ways to share the limited available spectrum has become increasingly important. One promising ap- proach is distributed spectrum sharing, which allows dynamic use of the spectrum based on real-time demands. However, this method faces challenges due to the unpredictable behavior of different users and devices, requiring sophisticated strategies to manage spectrum usage effec- tively. Currently, the most common method for distributed spectrum sharing is LBT, widely used in Wi-Fi networks. Although LBT has been well-studied in these environments, its use in systems like NR-U – a variant of 5G designed for unlicensed spectrum—has not been thoroughly explored. This gap exists mainly because there are few hardware testbeds and simulation platforms avail- able to study how LBT and other methods might work in real-world systems. This thesis aims to address this gap by developing a standardized platform for testing and experimenting with 5G NR-U technologies. The work involves three key steps: (i) designing a comprehensive system architecture for 5G NR-U; (ii) implementing this system in a simulation environment to study its performance; and (iii) proposing a design for key components using SDR and open-source soft- ware, creating a foundation for future hardware-based testing. To demonstrate the capabilities of this new platform, we conducted a simulation-based experiment focused on optimizing traffic management in NR-U systems to better handle delay-sensitive communications. Although no hardware experiments were conducted, the thesis provides a conceptual framework for future studies exploring how Wi-Fi and NR-U could coexist in the same frequency bands using the pro- posed hardware platform. The thesis concludes with suggestions for future improvements to the testbed, particularly in advancing spectrum sharing techniques with scheduled-access systems.

This dissertation examines the legal position relating to the participation of children in research, especially in HIV preventive clinical research in South Africa. HIV/AIDS presents a real threat to humanity and particularly to the welfare of children. The participation of children in this type of trials is therefore vital. Children, as vulnerable participants, must also be protected from harm resulting from research. The study also considers the nature of HIV preventive clinical research, pointing to the inconsistencies in the legislation governing children’s participation in HIV preventive vaccine trials. The dissertation concludes that the question of the participation of children in HIV preventive clinical research poses many challenges, as the position in the South African law and relevant ethical guidelines are inconsistent and contradictory. The study recommends in the final instance that the relevant statutory provisions and ethical guidelines be harmonised in order to clear up the inconsistencies. / Jurisprudence / LL.M. (Legal Aspects of HIV/AIDS)

Thesis (DPhil)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Human participant research raises a conflict between medical progress as a societal good and the protection of participants as an individual good. Prior to 1960 the discretionary authority for the protection of participants resided in the hands of individual investigators. However, a wave of research atrocities from Tuskegee in 1932 to the Beecher expose in 1966 stimulated a change to a principle based system of regulation. Research Ethics Committees (RECs) and Institutional Review Boards (IRBs) were henceforth charged with the responsibility of human participant protection. Since 1966, this system of research review was established internationally and at one institution in South Africa. In 1997, placebo-controlled HIV vertical transmission trials in a number of developing countries including South Africa raised unprecedented controversy in research ethics internationally and nationally. In 2000, the fraudulent breast cancer trials conducted by Dr Bezwoda at Baragwanath Hospital drew international attention to research ethics in South Africa. However, the events that called into question the efficiency of the system of ethical review most poignantly were the recent deaths of volunteers in research at centres of excellence in the United States. It was charged that if there were deficiencies in the research ethics review system in developed countries, these were more likely to be present in developing countries. Around the same time the Interim National Health Research Ethics Committee (INHREC) was established in South Africa to explore and regulate the ethical review system in South Africa. Cognisant of these issues, the current study was undertaken to establish the various structural, procedural and substantive ethical challenges facing justifiable and ethical review of research in South Africa. A combination of conceptualphilosophical reflection and empirical research was employed in this dissertation. The empirical work employed both quantitative and qualitative research methodology. The quantitative survey explored the composition of RECs reviewing clinical trials research in South Africa with an emphasis on committee composition and structure as well as the review process. The qualitative research was conducted using semi-structured interviews of ten REC Chairpersons in South Africa to explore complex substantive issues like informed consent, standards of care and participant remuneration, inter alia. While the review system in South Africa is functioning at a reasonable level, there is wide variation from one REC to the next. RECs are geographically distant and function in isolation without opportunity to communicate and share ideas. Amongst institutional RECs, there is a stark contrast between historically disadvantaged institutions and historically advantaged institutions. REC membership, ten years into democracy remains white male dominated. Community representation is inadequate. Most RECs are dominated by scientists and clinicians. The review process is widely variable with delays in review ranging from ten days to ten weeks. Procedural and bureaucratic demands impact on the ability of REC members to engage in debate on important substantive ethics issues like standards of care, informed consent and participant remuneration. Research ethics training and educational needs vary widely across the country. Serious attention must be paid to the way in which RECs are constituted in South Africa. Restructuring of RECs with a view to improving representation in terms of race, gender and religion must be prioritized. There is a need for community representation and non-scientific membership to be explored. RECs in South Africa need to revisit the question of whether they should be conducting both scientific and ethics review or ethics review alone. The review process requires a paradigm shift in emphasis from adverse event reporting to monitoring, from informed consent forms to a culturally relevant informed consent process. Aparadigm shift is indicated to shift the focus from informed consent to a more comprehensive review framework. Policies regarding standards of care and participant remuneration must be clarified and articulated. Although the role of RECs in human participant protection has been questioned, it is clear that in the vast majority of cases, they are fulfilling an important role. Their function could certainly be enhanced. This is being facilitated by training programs and an electronic newsletter. However, responsibility for human participant protection does not reside in the domain of the REC alone. A collective responsibility shared by researchers, institutions, research ethics committees, sponsors and participants is integral to human participant protection and the generation of new, valid and relevant scientific knowledge. / AFRIKAANSE OPSOMMING: Navorsing op menslike subjekte gee aanleiding tot ‘n konflik tussen mediese vooruitgang as ‘n voordeel vir die samelewing en die beskerming van deelnemers as iets waarby die individu direkte belang het. Voor 1960 het die diskresionêre gesag vir die beskerming van deelnemers by die individuele navorsers berus. ‘n Golf van navorsingsvergrype, van Tuskegee in 1932 tot die Beecher onthulling in 1966, het egter veranderinge in die rigting van ‘n stelsel van beginsel-gebaseerde regulasie gestimuleer. Navorsingsetiekkomitees (NEKs) en Institusionele Beoordelings- en toesigrade (IBRs) is gevolglik belas met die verantwoordelikheid om toe te sien dat mense wat deelneem, sover moontlik beskerm word. Sedert 1966 is hierdie stelsel van navorsingshersiening en -toesig internasionaal tot stand gebring – ook, aanvanklik, by een instansie in Suid-Afrika. In 1997 het plasebo-beheerde HIV-vertikale oordrag-proewe in ‘n aantal ontwikkelende lande, insluitend Suid-Afrika, tot ongekende kontroversie op die terrein van navorsingsetiek aanleiding gee, internasionaal en nasionaal. In 2000 het die bedrog met borskankerproewe, uitgevoer deur dr Bezwoda by Baragwanath Hospitaal, internasionale aandag op navorsing in Suid-Afrika gevestig. Hierdie gebeure het egter die effektiwiteit van die stelsel van etiese toesig in Suid-Afrika en elders in die wêreld bevraagteken. Die mees kommerwekkende onlangse insident was die dood van navorsingsvrywilligers by sentra van uitmuntendheid in die Verenigde State. Daar is beweer dat as daar tekortkominge in die navorsingsetiektoesigsisteem in ontwikkelende lande is, daar ‘n groter moontlikheid bestaan dat dit ook (en moontlik meer) in ontwikkelende lande voorkom. Ongeveer dieselfde tyd is die Interim Nasionale Gesondheidsnavorsings-etiekkomitee (INGNEK) [Interim National HealthResearch Ethics Committee (INHREC)] in Suid-Afrika gestig om die etiekoorsigstelsel in Suid-Afrika te ondersoek en te reguleer. Met dit in gedagte is die huidige studie onderneem om die verskillende strukturele-, prosedurele- en substantiewe etiese uitdagings wat regverdigbare en etiese oorsig van en toesig oor navorsing in Suid-Afrika in die gesig staar, vas te stel. Daar is van ‘n kombinasie van konseptuele, filosofiese refleksie en empiriese navorsing in hierdie proefskrif gebruik gemaak. Die empiriese werk maak gebruik van sowel kwantitatiewe as kwalitatiewe navorsingsmetodes. Die kwantitatiewe opname bestudeer die samestelling van NEKs wat toesig hou oor kliniese proewe in Suid-Afrika, met die klem op komiteesamestelling, -struktuur en die toesigproses. Die kwalitatiewe navorsing is gedoen met behulp van van semi-gestruktureerde onderhoude van tien NEK-voorsitters in Suid-Afrika om die komplekse substantiewe aspekte, soos onder andere ingeligte toestemming, standaard van versorging en deelnemervergoeding, te ondersoek. Terwyl die etiek-toesigstelsel in Suid-Afriks op ‘n redelike vlak funksioneer, is daar ‘n groot verskil tussen verskillende NEKs. NEKs is geografies verspreid en funksioneer dikwels in isolasie sonder ‘n geleentheid om te kommunikeer en idees te deel. Ten opsigte van die institusionele NEKs bestaan daar ‘n duidelike kontras tussen histories benadeelde instansies en histories bevoordeelde instansies. NEK-lidmaatskap word, tien jaar na demokrasie, steeds gedomineer deur blanke mans. Gemeenskapsverteenwoordiging is onvoldoende. Die meerderheid NEKs word gedomineer deur wetenskaplikes en klinici. Die toesig- en hersieningsprosesse in die verskillende komitees verskil grootliks, met vertragings wat wissel van 10 dae to 10 weke. Prosedurele- en burokratiese vereistes het ‘n impak op die vermoëns van NEK-lede om by debatte oor belangrike substantiewe etiese aangeleenthede betrokke te raak, soos byvoorbeeld die standaard van versorging, ingeligte toestemming en deelnemervergoeding. Opleiding en opvoedkundige behoeftes verskil wyd oor die land.Ernstige aandag moet geskenk word aan die wyse waarop NEKs in Suid-Afrika saamgestel is. Herstrukturering van NEKs met ‘n visie op verbeterde verteenwoordiging in terme van ras, geslag en geloof is ‘n prioriteitsvereiste. Gemeenskapsverteenwoordiging en lidmaatskap van nie-wetenskaplikes moet verder ondersoek word. NEKs in Suid-Afrika moet die vraag of hulle sowel wetenskaplike- as etiektoesig moet uitvoer, of sl slégs etiektoesig, opnuut ondersoek. Die nasiensproses vereis ‘n paradigmaskuif, vanaf ‘n klem op rapportering van gebeurtenisse, na monitering van ingeligte toestemmingsvorms sowel as na ‘n kultureel toepaslike ingeligte toestemmingsproses. ’n Paradigmaskuif is noodsaaklik ten einde die fokus te verskuif vanaf ingeligte toestemming na ‘n meer omvattende toesig- en nasiensraamwerk. Beleid rakende standaard van versorging en deelnemervergoeding moet verduidelik en geartikuleer word. Alhoewel die rol van NEKs in die beskerming van menslike deelnemers aan navorsing bevraagteken word, is dit duidelik dat NEKs in die meerderheid van gevalle wel ‘n belangrike rol vervul. Hul funksie kan natuurlik uitgebrei word. Dit sal gefasiliteer word deur opleidingsprogramme en ‘n elektroniese nuusbrief. Verantwoordelikheid vir die beskerming van mense wat deelneem aan navorsing berus egter nie uitsluitlik by NEKs nie. ‘n Kollektiewe verantwoordelikheid, gedeel deur navorsers, instellings, navorsingsetiekkomitees, borge en deelnemers is ‘n integrale vereiste vir hierdie beskerming sowel as vir die verwerwing van nuwe, geldige en relevante wetenskaplike kennis.

Thesis (doctoral)-Freie Universität, Berlin, 2004. / Includes bibliographical references (p. 350-399) and index.

This dissertation examines the legal position relating to the participation of children in research, especially in HIV preventive clinical research in South Africa. HIV/AIDS presents a real threat to humanity and particularly to the welfare of children. The participation of children in this type of trials is therefore vital. Children, as vulnerable participants, must also be protected from harm resulting from research. The study also considers the nature of HIV preventive clinical research, pointing to the inconsistencies in the legislation governing children’s participation in HIV preventive vaccine trials. The dissertation concludes that the question of the participation of children in HIV preventive clinical research poses many challenges, as the position in the South African law and relevant ethical guidelines are inconsistent and contradictory. The study recommends in the final instance that the relevant statutory provisions and ethical guidelines be harmonised in order to clear up the inconsistencies. / Jurisprudence / LL.M. (Legal Aspects of HIV/AIDS)

Thesis (MScMedSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Introduction: Primary culture of isolated adult rat cardiomyocytes (ARCMs) is an important model for cardiovascular research, but successful maintenance of these cells in culture for their use in experiments remains challenging (Xu et al, 2009; Louch et al, 2011). Most studies are done on acutely isolated cardiomyocytes immediately after isolation, which is due to low survival of these cells in culture. Obstacles in culture are due to the type of medium and attachment factors (tissue culture adhesives) used to culture and grow these cells. Although we previously identified an optimum medium and adhesive for culture, an adhesive that permits cells to remain attached to the culture surface until after an ischemia/reperfusion insult was elusive. Aims: We therefore aimed to identify the best attachment factor and concentration that will allow adult rat cardiomyocytes to remain attached to the culture surfaces after ischemia/reperfusion experiments. Methods: Cardiomyocytes were isolated from adult Wistar rat hearts and cultured overnight on different concentrations (25 -200 μg/ml) of collagen 1, collagen 4, extracellular matrix (ECM), laminin/entactin (L/E) and laminin. Following overnight cultures, experiments were done in PBS and in PBS versus MMXCB to compare ARCM attachment and viability. Cardiomyocytes cultured on ECM, L/E and L (25−200μg/ml) were subjected to 1 hour of simulated ischemia using MMXCB that contained 3mM SDT and 10mM 2DG, followed by 15 minutes reperfusion. Cell viability was determined by staining cells with JC-1 and images of cells in a field view of 1.17μm/mm2 were captured using fluorescence microscopy. The cells were analysed according to morphology and fluorescence intensity. Results: Total and rod-shaped ARCMs attachment was improved when MMXCB was used as an experimental buffer instead of PBS. Regardless of the buffer used, morphological viability was poor on substrates of Col 1 and Col 4. In contrast to collagens, ARCMs attached efficiently and morphological viability was high on substrates of ECM, L/E and L in MMXCB, but this was greatly reduced in PBS. Mitochondrial viability was high in MMXCB compared to PBS on Col 1 and Col 4 at 75−175μg/ml and on ECM, L/E and L at all concentrations, except at 50 and 150μg/ml ECM, 175μg/ml L/E and 25μg/ml L. When cardiomyocytes cultured on ECM, L/E and L were subjected to simulated ischemia, total ARCMs, rod-shaped and R/G fluorescence (mitochondrial viability) was reduced at all concentrations compared to the control group. Hypercontracted cells were higher in the ischemic treated cells compared to the controls on ECM at 75−150μg/ml and 200μg/ml, L/E at 50,100μg/ml and 175μg/ml and on L at 125μg/ml. Total numbers of ARCMs attached on ECM, L/E and L in the ischemic group consisted of similar numbers of non-viable hypercontracted and viable rod-shaped cells. Conclusion: Cardiomyocytes should be cultured on ECM or L/E or L at concentrations from 25−200μg/ml in MMXCB. PBS is harmful to cultured ARCMs and should thus not be used as an experimental buffer. Ischemia/reperfusion can be simulated on ARCMs cultured on ECM, L/E or L from 25−200μg/ml, provided that a modified culture buffer is used as experimental buffer. / AFRIKAANSE OPSOMMING: Inleiding: Primêre selkulture van geïsoleerde volwasse rot kardiomiosiete (VRKMe) is ‘n belangrike model vir kardiovaskulêre navorsing, maar om hierdie selle suksesvol in kultuur te onderhou is ‘n groot uitdaging (Xu et al, 2009; Louch et al, 2011). Die meeste navorsingstudies maak gebruik van akuut geïsoleerde kardiomiosiete onmiddelik na isolasie omdat oorlewing van hierdie selle in kultuur baie laag is. Die struikelblokke in kultuur is as gevolg van die tipe medium en weefselkultuurgom wat gebruik word. Ons het voorheen 'n optimale medium en weefselkultuurgom geïdentifiseer vir VRKM kultuur oorlewing, maar die weefselkultuurgom was nie effektief genoeg om die selle aan die kultuuroppervlak te laat bly vaskleef, tot na die einde van 'n isgemie/herperfusie eksperiment nie. Doel: Die doel was dus om die beste weefselkultuurgom en konsentrasie te identifiseer, wat sal toelaat dat VRKMe verbonde bly aan die kultuuroppervlaktes tot na die einde van isgemie/herperfusie eksperimente. Metodes: Kardiomiosiete was geïsoleer vanaf volwasse Wistar rotharte en oornag in kultuur op verskillende konsentrasies (25 -200 μg/ml) van kollageen 1, kollageen 4, ekstrasellulêre matriks (ESM), laminin/entactin (L/E) en laminin onderhou. Die volgende dag was die VRKMe vir eksperimentasie in PBS en in PBS teenoor MMXCB gebruik, om selbehoud en oorlewing te vergelyk. Kardiomiosiete op ESM, L/E en L (25−200μg/ml) was aan 1 uur van gesimuleerde isgemie blootgestel, in MMXCB wat 3mM SDT en 10mM 2DG bevat het, gevolg deur 15 minute herperfusie. Sel oorlewing was bepaal deur selle te kleur met JC-1 en daarna was fluoressensiebeelde van die selle in ‘n veldgebied van 1.17μm/mm2 geneem. Die selle was volgens selmorfologie en fluoressensie intensiteit ontleed. Resultate: Met die gebruik van MMXCB as eksperimentele buffer in plaas van PBS, het die aantal totale en staafvormige VRKMe verbinding verbeter. Morfologiese onderhoud was sleg op kollageen 1 en 4, ongeag van watter buffer gebruik was. In kontras met die kollagene was die VRKM verbinding en morfologiese onderhoud op ESM, L/E en L in MMXCB effektief verbeter, maar in PBS aansienlik verminder. Mitochondriale lewensvatbaarheid in MMXCB teenoor PBS op kollageen 1 en 4 by 75−175μg/ml, sowel as op ECM, L/E en L by alle konsentrasies, was hoog, behalwe by 50 en 150μg/ml ESM, 175μg/ml L/E en 25μg/ml L. Isgemie blootstelling van kardiomiosiete gekultuur op alle konsentrasies van ESM, L/E en L, het ‘n afname in die totale, staafvormige en R/G fluoressensie (mitochondriale lewensvatbaarheid) teweeggebring. Meer hiperkontrakteerde kardiomiosiete was in die isgemie behandelde groepe as in die kontrole groepe teenwoordig, spesifiek op ESM by 75−150μg/ml en 200μg/ml, op L/E by 50,100μg/ml en 175μg/ml asook op L by 125μg/ml. In die isgemie groepe het die totale aantal VRKMe op ESM, L/E en L meestal uit ‘n gelyke hoeveelheid hiperkontrakteerde en staafvormige selle bestaan. Gevolgtrekking: Kardiomiosiete moet op ESM of L/E of L by konsentrasises van 25−200μg/ml in MMXCB gekultuur word. PBS is nadelig vir VRKMe in kultuur en moet dus nie gebruik word as eksperimentele buffer nie. Isgemie/herperfusie eksperimente kan gesimuleer word op VRKMe wat op 25−200μg/ml ESM, L/E of L gekultuur is, mits ‘n gemodifiseerde kultuur buffer gebruik word as eksperimentele buffer.

Notre recherche de développement en didactique s’est articulée autour de deux pôles : l’engagement actif des élèves dans les paradigmes constructivistes de l’apprentissage par compétences et l’amélioration technologique d’un environnement de laboratoire utilisant la nouvelle technologie des systèmes MicrolabExAO. Pour ce faire, nous nous sommes intéressés aux possibilités didactiques offertes par ce nouvel environnement MicrolabExAO qui permet aux apprenants de réaliser leurs propres instruments de mesure électroniques avec l’expérimentation assistée par ordinateur (ExAO). En développant une intervention didactique appropriée, nous voulions permettre à l’élève non seulement de construire ses instruments, mais aussi d’en comprendre le fonctionnement. Par la réalisation concrète de quatre instruments de mesure, l’élève s’est approprié progressivement une démarche de résolution de problèmes complexes mobilisant des savoirs et savoir-faire en sciences expérimentales, en mathématique et en technologie. Dans l’activité finale de l’intervention didactique, pour vérifier le niveau d’intégration de cette démarche technoscientifique, nous avons demandé aux apprenants de transférer leurs apprentissages en situation nouvelle en construisant un manomètre de manière autonome. Ce faisant, les apprenants ont déployé leurs savoirs et savoir-faire en sciences expérimentales, en mathématique et en technologie pour construire l’instrument de mesure et en expliciter le fonctionnement, effectuant ainsi un apprentissage interdisciplinaire. Comme ils n’ont obtenu aucune directive de la part de l’enseignant ni aucun protocole de manipulations, nous pouvons dire qu’ils étaient placés dans une situation adidactique qui leur a permis de manifester une expertise de traitement interdisciplinaire. / Our developmental research in didactics has focused on two distinct aspects : The students' active engagement under the constructivist paradigms of competency-based learning and the technological enhancement of laboratory settings using the new MicrolabExAO environment. Towards these ends, we have explored the teaching possibilities offered by MicrolabExAO which allows learners to design their own electronic measuring tools with the computer assisted experimentation. By developing an appropriated teaching intervention, we wanted to enable the student not only to build his/her tools, but also to understand how they work. Through the actual implementation of four measuring tools, the student has progressively developed his/her own approach to resolving complex problems which call upon knowledge and skills in experimental sciences, mathematics and technology. In the final activity of the teaching intervention, with the objective of assessing the level of integration of this technoscientific approach, we have asked the learners to apply their new knowledge within the framework of building a manometer on their own. In doing so, the learners have deployed their knowledge and skills in experimental sciences, mathematics and technology in order to build the measuring tool and to explain its functioning, thereby achieving interdisciplinary learning. Since they have been given neither instructions from the teacher, nor operating protocols, we can say that they have been put in an adidactical situation which allowed them to demonstrate interdisciplinary expertise in their approach.