38981 research outputs found
Sort by
Estimating value at risk and expected shortfall: a kalman filter approach
Get PDFCalculating Value-at-Risk (VaR) to estimate the maximum loss a portfolio may incur at a given confidence level and over a specified time has undergone several adaptations, iterations, and additions since its inception in 1994. In 2013, the Basel Committee on Banking Supervision (BCBS) replaced VaR with Expected Shortfall (ES), or Conditional VaR (CVaR), as the new primary measure for banking institutions to forecast market risk and hence allocate the relevant amount of regulatory market risk capital. ES measures the probability weighted losses beyond VaR, so VaR remains a crucial step in its computation and retains its significance in estimating market risk and associated measures. A Kalman filter is used for the first time to estimate both VaR (and ES) to provide an alternative technique to existing industry methods. Modelling the volatility of asset returns as a stochastic process, the Kalman filter uses Bayesian statistics to forecast unobservable data by identifying underlying patterns required to predict future values. Back-testing results (in which the number of times VaR or ES forecasted too low a value to cover the following day's market loss is compared with the prescribed confidence level) indicate that the Kalman filter is a reliable and robust contender in the volatility framework milieu, outperforming GARCH, EWMA and equally weighted measures of volatility in both volatile and calm market conditions
Fire the hired gun: Eliminating expert bias in the accusatorial-adversarial civil justice system
Get PDFIn 1954, an expert witness, Dr Unsworth, testifying for the defendant, exculpatorily opined that the plaintiff was a malingerer, but had he testified for the plaintiff instead, his opinion would be that the plaintiff's condition was post-traumatic at the hands of the defendant. 1 This statement captures the essence of the adversarial expert bias problem. As early as 1843, selection expert bias (adversarial bias) was observed in AngloAmerican jurisdictions. 2 From a cursory search of South African case law, more fully set out in section 4.8, it is evident that expert bias is a legitimate and significant problem. 3 This work considers the problematic manifestation of expert bias in South Africa and possible responses thereto in the context of a predominantly adversarial procedural system, but the problem is in no way confined to the adversarial legal system
Exploring the legal means of enhancing access to essential medicines in South Africa
Get PDFThe introduction of ARVs to the care and treatment of HIV and AIDS must comply with South African patent law and international obligations under the TRIPS agreement. However, the prices of patented and/or branded drugs supplied by the manufacturers may prevent equitable access to necessary drugs for South Africans. Recent international trade agreements and the South African law provide a number of ways to address this dilemma. Therefore, if it is deemed necessary and expedient, the government may consider the implementation of measures such as voluntary licensing, compulsory licensing and parallel importation to purchase drugs at affordable and favourable prices (my emphasis)
Risk attitudes and affective states among young adults
Get PDFThis study examines how negative emotions influence risk attitudes and chance attitudes profiles among young adults using data from a novel behaviour modification programme targeted at young adults in South Africa. Risk attitudes are estimated structurally by assuming a stan-dard power utility function for the risky prospects they face in the risk elicitation experiment. The power parameter is recovered, and checks are performed for evidence of risk aversion and probability distortions. We find that while both the control and treatment groups exhibit risk aversion, the programme does not significantly alter risk aversion overall. However, significant treatment effects emerge with respect to probability distortion, suggesting that the programme fosters behaviour more closely aligned with expected utility maximisation. The programme appears to decrease the likelihood that individuals never experience anger or hostility. However, the effects on anger and hostility do not account for the observed treatment effects on probability distortions. Furthermore, individuals who never experience nervousness tend towards risk neutrality, while those who experience it are typically risk averse. Interestingly, both nervousness and fear correlate negatively with probability distortions, indicating a more pessimistic approach to risk among those who do not experience these emotions. This pattern holds across both the treatment and control groups, suggesting that these emotions remain relatively stable in the programme context. These findings emphasise the importance of considering affective states in designing interventions to address risky behaviours among young adults, contributing to improved public health outcomes
The discovery and development of the Namaqualand Diamond Field, 1925-1950
Get PDFDrawing on archival sources, secondary published materials and interviews, this thesis is a historical study of diamond mining in Namaqualand, Northern Cape Province of South Africa, during the period 1925 to 1950. It is a history that led to the region becoming synonymous with diamonds. The focus then is the first diamond find on the coast near Port Nolloth, as well as subsequent mining operations at Alexander Bay (the first State mining venture which contained some socialist elements) and Kleinzee (an extension of the De Beers Consolidated Mines empire). Captain Jack Carstens, ex-soldier and amateur prospector, is generally credited with having discovered the first stone in Namaqualand. However, vague rumours that there were earlier finds in the interior of Namaqualand can now be confirmed. The role of the major players – the State, the mining companies and the workers – is central to this study. Diamond mining has indeed had (and continues to have) a major impact on the local economy and society. By 1925 the harsh socio-economic conditions resulting from closure of the copper mines in Namaqualand, were compounded by drought, unemployment and widespread poverty. Against this background came the fortuitous discovery of the first precious stones on Port Nolloth Reserve or Commonage. This was followed by the astounding discoveries on the coastal terraces at Alexander Bay and Kleinzee, which quickly outdistanced the importance of the copper industry founded in Namaqualand in 1852. This thesis also throws light on the historical relations between the mining companies and their workers who were recruited from the local communities and elsewhere. The discovery of diamonds brought with it migrant labour housed in single-sex hostels or compounds, as well as the entrenchment of wage labour. What originated as a response by labour to economic circumstances would, in time, become entrenched in policy in the interest of the mining houses. Attention is furthermore drawn to the external political and economic forces that during the mid-twentieth century shaped the dominion of the companies over the people on and around the mines. In this way, the wider history of inequitable relations between a white-controlled state and white capitalists on the one hand, and on the other, the local people dispossessed of their historic rights to land and a fair share of the mineral wealth of the district, is illuminated. The labour force was, in addition, racialized along lines of race, ethnicity and class specifically in regard to the preferred status of “poor whites” in the mining industry. In short, the thesis examines how the history of mining sustained the racial hierarchies of colonialism, segregation and apartheid, and the marginalisation of non-white labour. Today, the diamond diggings on the Alexander Bay coast and the closed down mines of Kleinzee along the lower Buffels have simply emphasised the fact that Namaqualand's wealth and potential lie beneath the ground. Unrehabilitated mining sites and huge mine dumps bear witness to a century of diamond mining which left local communities uncertain and having little to show. The future, however, points in the direction of undersea diamond reserves off the coast. Marine mining will certainly continue to grow in importance as the onshore deposits are depleted, opening a new chapter of mining history
Experiences of camouflaging by AFAB University students with ADHD in South Africa
Get PDFAttention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder that continues to be underdiagnosed in people assigned female at birth (AFAB). Increasingly, the gender disparity in ADHD prevalence rates is attributed to differences in the disorder's presentation. A factor that is yet to be explored is the role that camouflaging, or acting neurotypically, plays in the presentation of ADHD in AFAB people. Camouflaging, which has mainly been studied in relation to autism, refers to cognitive and behavioural adaptations that assist neurodiverse people to cope cognitively and socially. This study aimed to investigate camouflaging from the perspective of AFAB university students with ADHD. University students were chosen as the study's sample population as few studies on ADHD focus on this population group. By using an interpretive phenomenological analysis (IPA) approach, the study explored the experiences of camouflaging by 12 AFAB university students with ADHD. The study also sought to gain insight into the camouflaging strategies that participants recognise themselves using and under what circumstances. Three group experiential themes (GETs) were identified in the data, namely Experiences of Living with ADHD, Experiences of Camouflaging, and Camouflaging Strategies. The themes provide important context for participants' need to camouflage and describe their experiences and perceptions of acting neurotypically. Furthermore, the data show that participants employ camouflaging strategies similar to those used by autistic people as well as strategies that speak to challenges more specific to ADHD. By exploring how AFAB university students with ADHD navigate and adapt to neurotypical standards and expectations, the study contributes to a growing understanding of how the disorder manifests in AFAB people and to ADHD research in South Africa
A historiography of South Africa's public health care governance affecting health system strength from the 1940s to 2023
Get PDFSegregationist minority rule socially engineered a system built on the brutality of black and brown people in South Africa leading to the aggravation of opportunistic infections. Centuries of white capitalist governance enslaved Black populations through settler colonialism and continued to inflict violence through the apartheid regime. Circulatory migrant labour and various forms of racist economic, health and land policies entrenched deliberate social disintegration in the country. The political economy formalised the maldistribution of health by ensuring the expansion of debilitating diseases like tuberculosis (TB) and HIV/AIDS throughout the twentieth century. Systemic violence by state government structures exploited Black vulnerabilities through the demonstration of structural violence. This shows how government-sanctioned policies affect not only health institutions within health systems, but also in wider constructions of power and health inequalities in South Africa. So, the unequal distribution of life-threatening diseases were contingent on the racialised dimensions of state power that impacts our contemporary health system. After the materialisation of democracy, scepticism arose toward the ANC's ambitious and unstable re-articulation of social justice and equity, particularly in its propulsions for development and economic growth. In some way, this offers a retrospection on the ANC-led public health system and their shortfalls in redressing deep-rooted health inequities since the injection of systemic racism. In the thesis, I provide openings to question the strength of South Africa's health system through an assemblage of the Health Systems Research and the Health Humanities. These linkages deepen the scholarship and relationship between subjectivities (experiences) of health and the connections to public health legislature among its regulatory bodies. I navigate the histories of the colonial and apartheid public health systems through to the advent of liberation to consider how layers of structural violence plague negative experiences of health, and factors inhibiting access to health facilities and efficient treatment. Engaging with Foucault's theorisation on governmentality is necessary to frame a critique of the structure and scope of state power and its role in the regulation of health. The effects of neoliberal policies directly inspired transnational activism during the HIV/AIDS epidemic by compromising the fundamental freedoms and rights to health outlined in South Africa's Constitution. The thesis thus concentrates on neoliberalism as practiced during apartheid and post-apartheid contexts which has prominently targeted marginalised and vulnerable populations within the wider arrangements of globalisation and global public health. To do so, the project illustrates how democratic governance and health systems designed in South Africa are inextricably connected to neoliberalism which affects the potential for liberatory, equitable and transformed iterations of health care. Therefore, the thesis aims to contribute to the growing literature on health systems research and the health humanities through the construction of a historical account of the public health care system and its impact on the implementation of equitable programs for health and improved health outcomes provincially
Investigating brain metabolite levels in adolescents living with HIV using atlas-based magnetic resonance spectroscopic imaging (MRSI)
Get PDFDeficiencies in brain function and structure have been linked to perinatally acquired HIV (PHIV) despite the introduction of antiretroviral therapy (ART). Current studies are predominantly based on single voxel magnetic resonance spectroscopy (MRS) in younger children, with inconsistent findings. We aimed to develop atlas-based pipelines for analysing MRSI data to examine whether there are differences in brain metabolite levels between adolescents with PHIV and uninfected controls. The study participants were 165 adolescents, of whom 86 were adolescents living with HIV from the CHER trial and 79 were age- and sociodemographically- matched uninfected controls. They were scanned on a Siemens 3T Skyra scanner with the scanning protocol including a high-resolution T1- weighted structural MRI using a multi-echo magnetization-prepared rapid acquisition gradient echo (MEMPRAGE) sequence and volumetric MRSI using spiral-encoded localized adiabatic selective refocusing (LASER) CSI. LCModel was utilized to achieve spe
Constitutional limits on the application of the political question doctrine: a study of Kenya, South Africa and Ghana
Get PDFPolitical branches are increasingly coming under the scrutiny of the judiciary under the now widely embraced principle of constitutional supremacy. What was a call to complete abstention in the face of political questions has been replaced with a call for the constitutional review of political questions as judges continue to embrace their guardianship role over the Constitution. The principle of constitutional supremacy allows judges to intrude into terrain hitherto reserved for political branches. Intrusions, by their very nature, can be disruptive and often result in claims of judicial overreach. Over time, the judiciary has been urged to exercise deference to cure the claim of overreaching. However, principled approaches have yet to be proffered to guide the institution in the deference to employ when reviewing political questions for their constitutionality. This study fills the gap by offering a principled approach to reviewing political questions for their constitutionality. It does this through a comparative study of three jurisdictions that have codified the principle of constitutional supremacy. The study reveals that intrusions are mandated by the Constitution itself, and it therefore also reveals the need to create a distinction between constitutionally permissible and impermissible intrusions. The study finds that a constitutionally permissible intrusion results when courts interpret their institutional authority and the text of the Constitution in a narrow manner that respects the constitutional power and discretion committed to political branches. In contrast, an impermissible intrusion results when courts interpret their institutional authority and the text of the Constitution in an expansive manner that disregards the constitutional power and discretion committed to political branches. The study makes three propositions as a cure to constitutionally impermissible intrusions; first, where a constitutional power has been committed to a political branch, and no discernable textual constraint on that power is evident in the text of the Constitution, judges must refrain from creating constraints foreign to the text of the Constitution as a basis for review. Secondly, when a textual interpretation of the Constitution reveals an absence of normative standards to guide a political branch in answering a constitutional question committed to it, the Constitution empowers political branches with the duty to supply normative standards, which are binding on the court. Third, where a political branch fails to supply normative standards to an indeterminate constitutional provision, the court should not take it upon itself to supply determinacy. Its role is to direct the political branch to develop a normative framework that supplies determinacy. The three propositions offer a more predictable and stable deferential approach to the constitutional review of political questions. Constitutionally impermissible intrusions are inherently undemocratic and sour relations between the judiciary and political branches. They arise when judges set aside fidelity to text in interpreting the Constitution and assume an interpretive role that defiles the Constitution they claim to uphold. Through the approach advanced in this study, judges will be equipped with a framework with which to hold political branches accountable in a manner that does not tread upon terrain inappropriate for judicial intervention
From protection to persecution: exploring the impact of anti-foreigner mobilisation on refugee rights in South Africa
Get PDFThis research explores how anti-foreigner mobilisation impedes the rights and lives of refugees in South Africa. This study does this by highlighting the anti-foreigner mobilisation movement, Operation Dudula. Grounded in a qualitative desk review, the study examines the systemic, social and economic impacts of xenophobia on the refugee communities. Many of the rights of refugees, who have legal rights to protection under international conventions, including the 1951 Refugee Convention and domestic laws such as the Refugees Act of 1998, are being violated. These violations take the form of violence, economic exclusion and social exclusion, usually enabled by scapegoating and misinformation. This research explores the need for multifaceted interventions to mitigate anti-foreigner mobilisation and its negative implications among refugee communities in South Africa. The South African administration must respond to the structural motivators of xenophobia and fortify the legal protections that come with the status of refugees through the implementation of constitutional ideals and international obligations. Addressing the root causes of forced displacement, such as conflict and poverty, requires a human rights-based approach that emphasises prevention, protection and empowerment. In conclusion, this study highlights the importance of collaboration between state and non-state actors, as well as local and international entities, to ensure a rights-based approach to refugee protection, in line with the highest international standards. Through decisive action, South Africa is able to reaffirm its position as a beacon of human rights and solidarity in the region