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  • Item
    Open Access
    Control of Rapid Acceleration in a Planar Legged Robot
    (2023) Mailer, Christopher; Patel, Amir; Govender Reuben
    This thesis details the hardware and control design of Kemba: a planar legged robot intended for investigating bounding and explosive, agile manoeuvres. The robot incorporates both pneumatically actuated knees for powerful, compliant, and impact resistant actuation, and proprioceptive electric actuators at the shoulder and hip for high bandwidth torque control and foot placement. Kemba is capable of bounding at up to 1.7m/s with a full flight phase, jumping just under 1mhigh (2.2 times it's nominal leg length), and accelerating from rest into a top speed bound in only 2 strides and under half a second, demonstrating its agility. Stable bounding and acceleration is achieved using a discrete body oscillation stabiliser, and the more dynamic jumping and somersault motions are generated using offline nonlinear trajectory optimisation. The optimal jumping motion was executed on the physical robot while the somersault is currently still limited to simulation. Due to the unique design and actuator combination, contact implicit trajectory optimisation served as a vital tool for motion identification and controller design. In addition to the robot dynamics and unilateral contact constraints, a more tractable pneumatic actuator model was developed which enabled the numerically stiff, discontinuous air dynamics and discrete valve switching to also be incorporated into the trajectory optimisation formulation. Trajectories resulting from optimisation were accurate enough to be implemented directly on the hardware in the case of the jump motion, and also crucially inform the design of the accelerate from rest controller. The results presented in this work indicate that Kemba is a robust and agile platform, well suited for future work in understanding dynamic manoeuvres and optimal control
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    Open Access
    Common Mental Disorders Among Adolescents Accessing HIV Treatment In Cape Town, South Africa
    (2020) Mtukushe, Bulelwa; Sorsdahl, Katherine; Hoare, Jacqueline
    Background: At the present time, data on the prevalence of common mental disorders (CMD) among adolescents living with HIV (ALHIV) in South Africa (SA) is limited. Studies that exist focus mainly on HIV-infected adults with mental health problems besides a few studies investigating depression and anxiety in children and adolescents living in SA. Research on the mental health of this vulnerable population remains very limited. Therefore, this study aims to address this gap by assessing the prevalence of CMD among adolescents living with HIV in SA; and determining the factors associated with CMD among this vulnerable population. Specific objectives: Specific objectives included, assessing the CMD among adolescents accessing ARV treatment; and determining factors associated with CMD among adolescents accessing HIV treatment. Methods: 121 Participants were recruited into the study through convenience sampling and interviewed. To be included in the study, participants had to be 10 to 19 years old; have knowledge of their own HIV-positive status; and presently on HIV treatment. Participants over 18 years were excluded if they did not provide informed consent and those under 18 were excluded if parent consent or adolescent assent was not obtained. Interviews with participants were conducted by study research assistants using a survey questionnaire which included the following mental health measures; Beck Depression Inventory for youth (BDI-Y), Beck Anxiety Inventory for youth (BAI-Y). Data collection for the study took place at two HIV treatment clinics in Cape Town, Groote Schuur hospital and Kuyasa clinic. Two logistic regression models were developed. Unadjusted and adjusted associations between socio-demographics, SES, food insecurity, alcohol use, years child known status and the presence of anxiety and depression were explored through logistic regression. Age, gender and variables that were significant in the unadjusted associations were included in the adjusted logistical regression models. Significance was set at p<0.05. Results: Four main findings emerged from the current study: 13.2% of participants were at risk for anxiety and 13.2% were at risk for depression; 6.6% participants were at risk for both anxiety and depression; the only variable associated with anxiety was socio-economic status and this was only significant in the unadjusted model; and the only variable associated with depression was highest level of schooling completed (i.e. currently in high school/completed high school) and this was significant in both unadjusted and adjusted models. Overall, adolescents with a higher educational level were less likely to develop depressive symptoms (adjusted model: OR=0.10, 95% CI 0.02-0.68). Conclusion: The present study assessed the prevalence of CMD, including determining the factors associated with CMD among adolescents accessing HIV treatment in Cape Town. Findings revealed that participants were at risk for anxiety, depression and comorbid anxiety and depression. Only highest level of schooling completed was found to be a protective factor against depression for this vulnerable population. Based on these findings, considerations for improving mental health outcomes for this population should include, screening for mental health conditions in ARV clinics, early identification and treatment of mental health problems, and evidence-based mental health counselling
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    Open Access
    Intimate Partner Violence among Adolescent Girls and Young Women in Bulawayo, Zimbabwe and perceived barriers and facilitators to the provision of psychosocial interventions in salons
    (2023) Ndondo, Nonhlanhla Lindelwe; Carney, Tara; Richter, Marlise; Van Der Westhuizen, Claire
    Background. Women are disproportionately affected by intimate partner violence (IPV), particularly those in low-to-middle-income countries (LMIC). Recent research data suggests that IPV prevalence among adolescent girls and young women (AGYW) in Zimbabwe is estimated to be 36.5%. Innovative intervention models that leverage gendered spaces to provide IPV support have shown great potential in high income countries, but little is known about these in LMIC settings, including in Zimbabwe. The current qualitative study explored the experiences of IPV among AGYW as well as the feasibility of the use of pre-existing female spaces such as salons to provide psychosocial interventions in Bulawayo, Zimbabwe. Methods. Nine AGYW who had experienced IPV participated in virtual and in-person key-informant interviews. Two focus groups were conducted with salon and spa workers to explore the potential use of salon-based interventions (n=10). Purposive sampling was used as a recruitment strategy. Thematic analysis was used to analyse the data. Results. The findings indicated that in this study, AGYW participants' experiences of IPV consisted mainly of physical IPV such as being beaten with an object, being slapped, or punched with a fist, followed by psychological and lastly, sexual IPV. The results of the study highlighted the factors that seemed to predispose AGYW participants to IPV such as sociocultural influences, economic disempowerment and partner characteristics and behaviours. AGYW participants also discussed the negative physical and mental health impact of the psychological and sexual abuses they had encountered. Both salon workers and the AGYW interviewed identified peer support facilitated by the positive social capital created in salons, as well as the female-centeredness of salons as conducive elements for an acceptable intervention. However, some speculations around confidentiality and accessibility to salons were some of the potential barriers identified for implementing salon based IPV interventions. Conclusion. The findings of this study indicated that there is a need to identify and address IPV, as well as the mental health consequences that AGYW experience due to IPV. While the use of predominantly female spaces, in this case salons, were discussed as feasible spaces to incorporate into IPV support models for AGYW, there were certain barriers which will need to be addressed for this to be considered. In addition, it was clear that the content of such interventions needed to include not only IPV and associated mental health issues, but also include other components such as economic empowerment of AGYW, while also challenging traditional gender norms through salon-based interventions. Furthermore, AGYW alluded to their preference for IPV psychosocial support interventions to be peer-based and female-driven. Salons typically provide these aspects, hence increasing their viability as a choice for community based IPV support
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    Open Access
    An exploration of Cape Town's Early Childhood Development sector in the face of the Covid-19 pandemic: Challenges, experiences, and opportunities for social support
    (2023) Pearce, Claire; Van Niekerk, Lauren-Jayne
    The early childhood development (ECD) sector, already vulnerable and inequality-ridden, has been hit hard by the Covid-19 pandemic, subsequent regulations, and implications. The Disaster Management Act, No. 57 of 2002, as amended in March 2020, imposed lockdown regulations to combat the spread of Covid-19. ECD programmes were closed by government from 18 March 2020; and only reopened from 6 July 2020 following ECD-sector litigation. This exacerbated existing, and posed new, socioeconomic challenges. To survive, the ECD sector adapted and sought social support, although the experiences thereof were varied. International research continuously emphasises the importance of quality ECD as critical for lifelong development and a nation's socioeconomic development (UNICEF, 2014); thus, a crippled ECD sector is of great concern in South Africa. This study explored Cape Town's ECD sector challenges and experiences in the face of the Covid-19 pandemic as well as the experiences of social support offered and opportunities for enhancing effective social support in the future. Undertaking a qualitative exploratory research design, 15 ECD-centre principals and five ECD non-profit staff participated in semi-structured interviews. The research found that Covid-19 regulations triggered a snowball effect of socioeconomic challenges. Among these include unemployment, income loss, difficulties in ECD-sector reopening, hunger, malnutrition, limited child stimulation, child abuse, gender-based violence, drug and alcohol abuse, gangsterism and other criminal activity, as well as mental-health challenges affecting children, families and communities, including the ECD workforce. ECD centres were found to be a source of social support for the ECD workforce and serve as safe spaces for young children. Families, too, were found to provide critical support for children's development. During the pandemic, ECD NPOs have provided social support through information provision and capacity building. Government support included local government support, and grants and subsidies – yet, the study found that rather than support, these proved problematic with overly-cumbersome requirements, significant delays, and nonpayment. The research study showed ECD-sector social support following the onset of the Covid-19 pandemic through communities and intersectoral collaboration, including food relief, ECD forums and activism. Opportunities for effective ECD-sector support that emerged from the data, and were highlighted by ECD principals and ECD non-profit staff, included recognition of ECD and the ECD sector, empowering families and communities, scaling NPO support, and ECD workforce skills development and capacity building.
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    Open Access
    The embellishment in Mozart's keyboard music with specific application to seven of his late piano concertos
    (1996) Goodall, Shane Leslie
    Background to the study It was the practice in Mozart's day for performers to make improvisatory additions to the written text. They would add ornaments, fill in skeletal passages and decorate works according to their ability and taste. Mozart himself was well-known for his gift of improvising, which he put to good use when performing his concertos. Problem to be studied All Mozart's works published in his lifetime show a great attention to detail. He wrote out ornaments, cadenzas, and lead-ins, and embellished recurring themes. This can be seen in his keyboard sonatas and concertos. However, there are some instances where he was rushed for time when composing, and he used abbreviations, or left recurring themes unembellished. In his piano concertos written for his own performance for example, some sections have been abbreviated and need filling out. Other places require embellishment. These aspects are characteristic of the late piano concertos, and are used in this study, namely: K.466 in D minor, K.482 in Eb major, K.488 in A major, K.491 in C minor, K.503 in C major, K.537 in D major, and K.595 in B b major. The author is of the opinion that modem-day pianists may lack the improvisational skills practised in the latter part of the eighteenth century, and it is therefore problematic for them to lV realise these works fully. The embellishment of these concertos involve adding ornaments such as appoggiaturas, auxiliary notes, turns, cambiatas, echappees, passing notes and trills; filling out abbreviated areas; and improvising lead-ins where fermatas occur over the dominant harmony. Purpose of the study It is the author's aim to provide pianists performing these concertos with sufficient information to embellish these works by: supplying an index of the ornamentation used by Mozart in his keyboard works; applying this information to the piano concertos, in conjunction with suggestions and recommendations obtained form literature on the topic. Conclusions reached Once the study of Mozart's embellishment and relevant literature has been made, care must be taken when applying this information. It is equally bad to add too much embellishment as it is to add none at all. C.P .E. Bach sums up this in the following statement: Good embellishments must be distinguished from bad, the good must be correctly performed, and introduced moderately and fittingly.