23 research outputs found
The dynamics of appraisal: A review of 20 years of research using the Fortitude Questionnaire
Fortitude refers to the psychological strength to manage adversity and stay well. It is derived from
adaptive cognitive appraisals of self, family, and social supports and has consistently been identified as
a protective factor in psychological well-being. This study undertakes a scoping review of empirical
research on the Fortitude Questionnaire, which was developed to assess levels of fortitude.
The aims of the study were to categorize and catalogue studies that have used the Fortitude
Questionnaire, identify the variables that have been linked to the scale, and determine the extent to
which prior research has replicated the Fortitude Questionnaire’s psychometric properties. Arksey
and O’Malley’s five-stage framework for scoping reviews was followed to review studies published
between January 1999 and March 2020. A total of 51 studies met the inclusion criteria. The scoping
review found that the Fortitude Questionnaire has been used in different contexts and among
various sample groups across the lifespan, including vulnerable and high-risk populations. The scale
has demonstrated sound reliability and studies have confirmed its factor structure
Reliability based planning methodology for feeder automation
Abstract: One of the most used measures for improving service reliability is distribution automation (DA). The DA technology has been widely used by different utilities for quite some time. Its applicability on the Eskom distribution network is an option but it is still in the research and development stage. This paper proposes a method for a network planning engineer to motivate the use of feeder automation (FA). This methodology will serve as a guideline to a network planner interested in using FA as an alternative or additional solution to improve the reliability of a feeder. The defined method is based on literature and existing research on FA. Furthermore the methodology is analyzed using the Eskom case study. A comparison is made by identifying a pattern of steps or methods followed in planning for Magaliesburg-Hekpoort feasibility project and comparing this method with the proposed methodology
Assessment of epidemic projections using recent HIV survey data in South Africa: A validation analysis of ten mathematical models of HIV epidemiology in the antiretroviral therapy era
Background: Mathematical models are widely used to simulate the effects of interventions to control HIV and to project future epidemiological trends and resource needs. We aimed to validate past model projections against data from a large household survey done in South Africa in 2012. Methods: We compared ten model projections of HIV prevalence, HIV incidence, and antiretroviral therapy (ART) coverage for South Africa with estimates from national household survey data from 2012. Model projections for 2012 were made before the publication of the 2012 household survey. We compared adult (age 15-49 years) HIV prevalence in 2012, the change in prevalence between 2008 and 2012, and prevalence, incidence, and ART coverage by sex and by age groups between model projections and the 2012 household survey. Findings: All models projected lower prevalence estimates for 2012 than the survey estimate (18·8%), with eight models' central projections being below the survey 95% CI (17·5-20·3). Eight models projected that HIV prevalence would remain unchanged (n=5) or decline (n=3) between 2008 and 2012, whereas prevalence estimates from the household surveys increased from 16·9% in 2008 to 18·8% in 2012 (difference 1·9, 95% CI -0·1 to 3·9). Model projections accurately predicted the 1·6 percentage point prevalence decline (95% CI -0·3 to 3·5) in young adults aged 15-24 years, and the 2·2 percentage point (0·5 to 3·9) increase in those aged 50 years and older. Models accurately represented the number of adults on ART in 2012; six of ten models were within the survey 95% CI of 1·54-2·12 million. However, the differential ART coverage between women and men was not fully captured; all model projections of the sex ratio of women to men on ART were lower than the survey estimate of 2·22 (95% CI 1·73-2·71). Interpretation: Projections for overall declines in HIV epidemics during the ART era might have been optimistic. Future treatment and HIV prevention needs might be greater than previously forecasted. Additional data about service provision for HIV care could help inform more accurate projections. Funding: Bill & Melinda Gates Foundation
Assessment of epidemic projections using recent HIV survey data in South Africa: a validation analysis of ten mathematical models of HIV epidemiology in the antiretroviral therapy era
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154578.pdf (publisher's version ) (Open Access)BACKGROUND: Mathematical models are widely used to simulate the effects of interventions to control HIV and to project future epidemiological trends and resource needs. We aimed to validate past model projections against data from a large household survey done in South Africa in 2012. METHODS: We compared ten model projections of HIV prevalence, HIV incidence, and antiretroviral therapy (ART) coverage for South Africa with estimates from national household survey data from 2012. Model projections for 2012 were made before the publication of the 2012 household survey. We compared adult (age 15-49 years) HIV prevalence in 2012, the change in prevalence between 2008 and 2012, and prevalence, incidence, and ART coverage by sex and by age groups between model projections and the 2012 household survey. FINDINGS: All models projected lower prevalence estimates for 2012 than the survey estimate (18.8%), with eight models' central projections being below the survey 95% CI (17.5-20.3). Eight models projected that HIV prevalence would remain unchanged (n=5) or decline (n=3) between 2008 and 2012, whereas prevalence estimates from the household surveys increased from 16.9% in 2008 to 18.8% in 2012 (difference 1.9, 95% CI -0.1 to 3.9). Model projections accurately predicted the 1.6 percentage point prevalence decline (95% CI -0.3 to 3.5) in young adults aged 15-24 years, and the 2.2 percentage point (0.5 to 3.9) increase in those aged 50 years and older. Models accurately represented the number of adults on ART in 2012; six of ten models were within the survey 95% CI of 1.54-2.12 million. However, the differential ART coverage between women and men was not fully captured; all model projections of the sex ratio of women to men on ART were lower than the survey estimate of 2.22 (95% CI 1.73-2.71). INTERPRETATION: Projections for overall declines in HIV epidemics during the ART era might have been optimistic. Future treatment and HIV prevention needs might be greater than previously forecasted. Additional data about service provision for HIV care could help inform more accurate projections. FUNDING: Bill & Melinda Gates Foundation
Restoring lions Panthera leo to northern KwaZulu-Natal, South Africa : short-term biological and technical success but equivocal long-term conservation
The success of efforts to re-establish mammalian carnivores within their former range is dependent on three key factors : methodological considerations, the biological requirements of the target species, and the involvement of local human communities for whom large carnivores pose a threat. We consider the role of these factors in the first 13 years of an effort to re-establish wild lions in northern KwaZulu Natal Province, South Africa. We employed soft-release methods to mitigate the characteristic problems associated with restoration of large carnivores. A pre-release captivity period facilitated acclimatization of reintroduced lions and promoted long-term bonding of unfamiliar individuals into cohesive groups. All individuals remained in the release area and established enduring, stable home ranges. Reintroduced lions successfully reproduced and raised 78% of their cubs to independence. Human activity was the cause of all post-release mortality. Despite rapid population growth and the re-establishment of the species at Phinda Private Game Reserve, the population is small and isolated with little prospect for re-colonizing additional areas where the species has been extirpated, or for connecting with other isolated lion populations in the region. Accordingly, although we essentially overcame the short-term technical and biological challenges facing lion reintroduction, the long-term value of the Phinda population for addressing the conservation issues facing the species remains equivocal.This research was funded by CC Africa, the IUCN Cat Specialist Group, a Pittsburgh Zoo Conservation Fund Award, a University of Pretoria Research Assistantship (to LTBH) and grants from the Foundation for Research Development and W.H. Craib Memorial Trust (to JDS)
HIV treatment as prevention: systematic comparison of mathematical models of the potential impact of antiretroviral therapy on HIV incidence in South Africa
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108066.pdf (publisher's version ) (Open Access)BACKGROUND: Many mathematical models have investigated the impact of expanding access to antiretroviral therapy (ART) on new HIV infections. Comparing results and conclusions across models is challenging because models have addressed slightly different questions and have reported different outcome metrics. This study compares the predictions of several mathematical models simulating the same ART intervention programmes to determine the extent to which models agree about the epidemiological impact of expanded ART. METHODS AND FINDINGS: Twelve independent mathematical models evaluated a set of standardised ART intervention scenarios in South Africa and reported a common set of outputs. Intervention scenarios systematically varied the CD4 count threshold for treatment eligibility, access to treatment, and programme retention. For a scenario in which 80% of HIV-infected individuals start treatment on average 1 y after their CD4 count drops below 350 cells/microl and 85% remain on treatment after 3 y, the models projected that HIV incidence would be 35% to 54% lower 8 y after the introduction of ART, compared to a counterfactual scenario in which there is no ART. More variation existed in the estimated long-term (38 y) reductions in incidence. The impact of optimistic interventions including immediate ART initiation varied widely across models, maintaining substantial uncertainty about the theoretical prospect for elimination of HIV from the population using ART alone over the next four decades. The number of person-years of ART per infection averted over 8 y ranged between 5.8 and 18.7. Considering the actual scale-up of ART in South Africa, seven models estimated that current HIV incidence is 17% to 32% lower than it would have been in the absence of ART. Differences between model assumptions about CD4 decline and HIV transmissibility over the course of infection explained only a modest amount of the variation in model results. CONCLUSIONS: Mathematical models evaluating the impact of ART vary substantially in structure, complexity, and parameter choices, but all suggest that ART, at high levels of access and with high adherence, has the potential to substantially reduce new HIV infections. There was broad agreement regarding the short-term epidemiologic impact of ambitious treatment scale-up, but more variation in longer term projections and in the efficiency with which treatment can reduce new infections. Differences between model predictions could not be explained by differences in model structure or parameterization that were hypothesized to affect intervention impact
Effect of Preexisting Inclusions on the Size and Morphology of Al₂O₃: Results from Two-Stage and Fixed Supersaturation Deoxidation
The effects of preexisting Mn·OSiO2 and FeO inclusions on the size and morphology of Al2O3 were investigated. Two-stage deoxidation with Mn and Si followed by Al and single-stage Al deoxidation at [O] levels of 287 ppm [O], 612 ppm [O], and 1071 ppm [O] were performed. The results showed heterogeneous nucleation and growth of Al2O3 onto MnO·SiO2 and FeO inclusions that were present in the steel before Al deoxidation. The transformation from MnOSiO2 to Al2O3 was slow and controlled by Al diffusion through an Al2O3 reaction product layer but that the conversion of FeO to Al2O3 was relatively fast and likely controlled by Al diffusion in liquid steel. For both deoxidation processes, clustered Al2O3 inclusions were observed. However, reactions involving preexisting FeO also produced dendrites and large spherical inclusions within the inclusion clusters. For same supersaturation level, the average size and area fraction of the spherical Al2O3 produced from reactions with FeO increased with increasing FeO content. Al2O3 inclusions formed from reactions with Mn·OSiO2 inclusions had a smaller area fraction than the preexisting Mn·OSiO2 inclusions