Microarchitecture’s optimizations have increased the performance but lowered the security. Speculative execution is one of the optimizations that was thought to be secure, but it is exploitable to leak information. The problem with these exploits is that there is no easy software defence and many exploits could be unexplored due to it being a fairly recent discovery. This thesis explores a way to find code that is vulnerable to this. The solution to the problem is to use the tool Side Channel Abstract Model Validator (SCAMV) which implements the method Model-Based Testing (MBT). We examine the core CVA6, which is a RISCV Central Processing Unit (CPU). Test cases are generated by program generators and interesting ones are selected by applying an observational model to them. The observational model abstracts side-channel leakage of the microarchitecture. The selected test cases are executed on the platform to validate the used observational models. The results of the test cases showed no indication of modifying the side channels under speculative execution. The results showed that SCAMV can examine timing-based channels. The conclusion is that our findings indicate that the CVA6 core is not vulnerable to speculative cache or timing-based side-channel attacks. / Optimeringar på mikroarkitektur nivåer har ökat prestandan men minskat säkerheten. Spekulativt utförande (speculative execution) är en av de optimeringar som har ansetts vara säkert, men det har visats att det kan utnyttjas för att läcka information. Problemet med dessa sårbarheter är att det inte finns något enkelt mjukvaruförsvar och att många sårbarheter fortfarande kan vara outforskade. Denna avhandling undersöker ett sätt att försöka hitta kod som är sårbar för detta. Lösningen på problemet är att använda verktyget SCAMV som använder sig av metoden Model-Baserad Testning. Vi undersöker CVA6, vilket är en RISCV CPU. Testfall genereras av programgeneratorer och intressanta testfall väljs genom att tillämpa en observationsmodell på dem. Observationsmodellen abstraherar sidokanalläckage i mikroarkitekturen. De valda testprogrammen verkställs på plattformen för att validera de använda observationsmodellerna. Resultatet från testfallen visade ingen indikation på att det går att modifiera sidokanalerna under spekulativt utförande. Resultatet visade att SCAMV kan undersöka tidsbaserade kanaler. Slutsatsen är att våra resultat indikerar att CVA6 inte är sårbar för spekulativa cache eller tidsbaserade sidokanalattacker.

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Background: Guidelines recommend that patients with haemophilia should preferably receive vaccination subcutaneously. COVID-19 and other vaccines, however, are only licenced for intramuscular application. Aims: To assess the safety of intramuscular COVID-19 vaccination in patients living with haemophilia. Methods: Part A of this prospective observational study enrolled consecutive patients with haemophilia A (HA) and B (HB) of all ages and severities and assessed injection site bleeding and other complications within 30 days of vaccination. Part B enrolled patients providing informed consent for detailed data collection including medication and prophylaxis around the time of vaccination. Logistic regression was performed to assess potential risk factors for bleeding. Results: Four hundred and sixty-one patients were enrolled into part A. The primary endpoint injection site bleeding occurred in seven patients (1.5%, 95% confidence interval .7–3.1%). Comprehensive analysis of 214 patients (404 vaccinations, part B) revealed that 97% of patients with severe haemophilia had prophylaxis before vaccination, either as part of their routine prophylaxis or using additional doses. 56% and 30% of patients with moderate and mild haemophilia, respectively, received prophylaxis before vaccination. Among the seven bleeds recorded, three occurred when intramuscular vaccination was done without prophylaxis (odds ratio 12). Conclusions: This is the first prospective study reporting on the safety of intramuscular vaccination in haemophilia. The rate of injection site bleeding was low in mild haemophilia, and in moderate and severe haemophilia if patients received factor prophylaxis.

[pt] O presente trabalho apresenta a Barragem de Terzaghi em um contexto da evolução tecnológica da construção de barragens de terra, colocando em foco sua construção e desempenho ao longo de 65 anos de operação bem como a verificação atual de suas condições físicas, analisando o impacto que a carga de sedimentos causa sobre a face montante da barragem, em termos de percolação, tensões e deformações. Tendo como base os métodos observacionais aplicados ao longo da operação da barragem e modelagem por elementos finitos, foram traçadas expectativas do fator de segurança para a seção principal da barragem ao longo do tempo. / [en] This work presents the Terzaghi Dam in a technological evolutionary context of the construction of earthfill dams, focusing on its own construction a performance after 65 years in operation as well as a scrutinized assessment of its physical conditions, implying the sediment load on its upstream slope, regarding seepage, stresses and strains. Taking into account observational methods applied throughout the operation of the dam and finite element simulations, the evolution of factor of safety over the dam lifetime and on was evaluated for the main section of the dam.

Objectives: Since their introduction in 2019, the use of e-scooters has become widespread in Germany. Concerns about road safety, especially pedestrian safety, have arisen as the popularity of micro-mobility has grown. In light of this context, the present study investigates which types of road infrastructure e-scooter riders use, with a focus on riding on the sidewalk, which is not permitted in Germany. We considered the following infrastructures: (1) off-road bike lane (+ sidewalk and road), (2) on-road bike lane (+ sidewalk and road), and (3) road (+ sidewalk). Methods: Observations at six sites (recording 738 e-scooter riders) and on-site surveys (involving responses from 129 e-scooter riders) were conducted in two German cities in August 2020 and September 2020. Results: Self-reported sidewalk riding was not found to be linked directly to a lack of rule knowledge, a preference for this type of infrastructure, or perceived safety. Observations indicated that using the sidewalk might be related to situational components, such as comfort or convenience, comprising up to 40% of instances of sidewalk riding. Conclusion: Considering the comfort and convenience factor of sites when building or improving cycling infrastructure can help keep e-scooter riders from riding on the sidewalk.

The aim of the study was to investigate classroom discourse among high school natural science students in Swaziland. The research problem was: Can student interactions tell us something about the negotiation of understanding during natural science teaching? A qualitative approach was used, specifically, the observational case study style. The population comprised three Form 4 students and their natural science teacher, purposely selected. Data was collected using the non-participant observation and the standardised open-ended interview methods. The collected data was analysed using the discourse analysis approach. The analysed data indicated that prevailing discourse patterns were teacher and student talk, as well as written work. A conclusion was that student classroom discourse in the natural sciences should be encouraged among all students for improved understanding and meaning making. / Science and Technology Education / M. Ed. (Natural Science Education)

There is a paramount need for online university education to effectively contribute in the development of students' ability to construct and create new knowledge. Online learning should thus go beyond the production of knowledge for knowledge's sake, but should result in relevant and meaningful learning on the part of the online learner. In addition, online learning ought to result in the application of knowledge to practice. While gains made by constructivism and observational learning are well documented, research addressing online media blends that best encourage constructivist and observational learning in open and distance and e-learning (ODeL) contexts is limited. In addition, guidelines that can be used by online learning facilitators and policy makers regarding media for constructivist and observational learning were lacking when this research was conducted. The research was deemed significant in contributing to the development of an online learning framework that could be used to guide policy formulation and practice in the area of online course implementation in ODeL institutions. Using an explorative qualitative approach, this study explored online media blends for constructivist and observational learning. The study comprised three phases. The first phase was a meta-ethnography study whose objective was to synthesise previous research theses in order to gain an understanding of lecturers' and students' experiences of online media, constructivism and observational learning. The second phase consisted of a phenomenological study conducted at the University of South Africa, to explore lecturers' experiences of online media in the facilitation of constructivism and observational learning. The final phase of the research was the development of a framework based on constructivism and observational learning to guide online teaching and learning. The findings of this research study revealed that lecturers did not use media blends to a large extent in their interaction with students. The study indicated that some cognitive processes need to be exercised on the part of the facilitators when online learning is offered. It is concluded that during the curriculum planning phase, lecturers should decide on methods and media to arouse the students' attention during online courses. This also implies a more reasonable lecturer­ student ratio because large numbers of students per lecturer is not feasible in online learning. / Curriculum and Instructional Studies / D. Ed. (Curriculum Studies)

This qualitative research investigated the implementation problems of apprenticeship training program in the Addis Ababa TVET colleges and enterprises. The research looked into the training program conducted by TVET Colleges and enterprises. Relevant literature on the nature of apprenticeship training and the factors that could affect its implementation were also reviewed. The research applied the theoretical statement of Bandura’s (1977) theory of observation /imitation/, Vygotsky’s theory of ZPD, contextual or the situated learning (Lave and Wenger, 1991), the constructivist view of learning and career theory as the main theoretical frameworks to describe the apprenticeship training process. The theories, however, do not mention the factors that can hamper the implementation of apprenticeship training in a specific social context. The theory of observation was preferred since it can describe the apprentice’s effort to master the skill of an occupation by observing the craftsman at the enterprises. The situated learning was preferred as it gives value to practice as a condition for the effectiveness of learning. Similarly, the research considered Vygotsky’s theory of the ZPD. The application of ZPD indicates the difference between what the apprentice can accomplish independently and what he/she can do with the close assistance of supervisor on a given task. Holland’s career theory (as cited in De lary, Duncan & Swarth, 2006) is also considered to describe the apprenticeship training in relation with an occupation. The current research has enabled to consider context specific conditions by focusing on the investigation of the causes of the implementation challenges of the apprenticeship training. The researcher collected data from Addis Ababa TVET Agency experts, deans of one private and another public TVET Colleges, college apprenticeship training coordinators, trainers, trainees, supervisors and enterprises by employing unstructured and structured interviews, observation and Focus Group Discussion tools. The analysis was made by making the data pass through three successive steps: data reduction, data display and interpretation, and conclusion. The findings showed that the implementation of the apprenticeship training program had challenges that could be shared among its actors; Trade Unions had no involvement in the implementation of the apprenticeship training program; the selected colleges and enterprises addressed their challenges by using limited strategies and without regular and systematic way; the presence of some less motivating factors for the participation of the apprentices in the apprenticeship training was reported; the presence of conditions that could adversely affect the apprentices’ acquisition of occupational skills was reported; the provision of apprenticeship training at the enterprises lack, either facilities or training services, in order to arrange the apprenticeship training program for TVET college trainees; and there were some indications for the presence of some weak professional qualities of supervisors that have implications for the apprentices’ training. Eventually, it was concluded that the implementation of apprenticeship training program in the Addis Ababa TVET Colleges and enterprises had challenges that require the consideration of both institutional and human conditions. / Curriculum and Instructional Studies / D. Ed. (Curriculum Studies)