On efficient modelling of radical production in cavitation assisted reactors.

Process intensification by cavitation is gaining widespread attention due to the benefits that the intense bubble collapse conditions can provide, yet, several knowledge gaps exist in the modelling of such systems. This work studies the numerical prediction of single bubble dynamics and the various approaches that can be employed to estimate the changes in the chemical composition of cavitating bubbles. Specific emphasis is placed on the prediction of the radical production rates during bubble collapse and the computational performance, with the aim of coupling the single bubble dynamics to flow models for reactor hydrodynamics. The results reveal that the choice of chemical reaction approach has virtually no effect on the bubble dynamics, whereas the predicted radical production rates can differ substantially. It is found that evaluating the radical production only on temperature peaks, an approach commonly followed in literature, may result in the most erroneous estimations (on average 12.8 times larger than those of the full kinetic model), while a simplified kinetic model yields more accurate predictions (2.3 times larger) at the expense of increased computational times. Continuous evaluation of the bubble content by assuming equilibrium when the bubble temperature is above a certain threshold (≈1500K) is shown to be capable of predicting total radical production values close to those estimated by solving the kinetics of a detailed reaction model (19.8% difference), as well as requiring only 22.2% more computational costs compared to simulations without chemical reaction modelling. Such an equilibrium approach is therefore recommended for future studies aiming to couple flow simulations with single bubble dynamics to accurately predict radical production rates in cavitation devices, involving numerous bubbles following different flow trajectories. Furthermore, an algebraic expression that successfully approximates the full kinetic simulation results is proposed as a function of the initial nucleus size and the time integral of the liquid pressure when it is under vapor pressure. Such a model can be applied in modelling efforts that do not require local instantaneous radical concentrations, and paves the way for efficient closure modelling of radical production in CFD simulations of hydrodynamic reactors.

Pregnancy and STI/HIV prevention intervention preferences of South African adolescent girls: findings from a cultural consensus modelling qualitative study.

South African adolescent girls experience high rates of unintended pregnancy and sexually transmitted infections including HIV. To inform culturally-tailored dual protection interventions to prevent both unintended pregnancy and STIs/HIV, this study qualitatively examined girls' sexual health intervention preferences. Participants were aged 14-17 years old and Sesotho-speaking (N = 25). To elucidate shared cultural beliefs, individual interviews examined participants' perceptions about other adolescent girls' pregnancy and STI/HIV prevention intervention preferences. Interviews were conducted in Sesotho and translated into English. Two independent coders identified key themes in the data using a conventional content analysis approach with discrepancies resolved by a third coder. Participants indicated that intervention content should include efficacious pregnancy and STI/HIV prevention methods and ways to navigate peer pressure. Interventions should be accessible, avoid criticism and provide high-quality information. Preferred intervention formats included online, SMS/text, or delivery by social workers or older, knowledgeable peers, with mixed acceptability for delivery by parents or same-age peers. Schools, youth centres and sexual health clinics were preferred intervention settings. Results highlight the importance of cultural context in tailoring dual protection interventions to address the reproductive health disparities among adolescent girls in South Africa.

'Being a mother is not child's play': The capabilities of mothers in a low-resource setting in South Africa.

BACKGROUND: The importance of a child's first 1000 days has now been widely accepted by the medical fraternity. Yet, we do not know much about caring practices in low-resource settings. AIM: This study aimed to investigate the caring capabilities of mothers in a low-resource setting. METHOD: In this study, in-depth interviews were conducted with 18 mothers with children aged 30 months or younger to better understand the arrangements, means and ends that inform developmental health in a low-resource setting in South Africa. The study was conducted in a low-income area, the former black township of Mangaung in Bloemfontein. The mothers were recruited via pamphlets, and two interviews followed. Because of Covid-19, interviews took place via mobile phones, in Sesotho, the local language in the area. Trained fieldworkers conducted, translated and transcribed the interviews. We used thematic analysis and the capabilities approach as the theoretical framework to analyse the responses from the mothers. FINDINGS: We used the following organizing themes: pregnancy and ante-natal care, nutrition, cognitive and physical development, the home environment and access to health care. Although short-term reactions to pregnancy were often negative, the longer-term responses showed that the respondents have agency. Most of them could change their nutrition habits, breastfeed and receive adequate nutrition support from the public health system. Most experienced joy when their children reached milestones (cognitive and others), although they became anxious if milestones were not reached. They emphasized children's play and had dreams for their children's futures. Technology was often mentioned as playing a role in their children's development. A large proportion of the respondents had disrupted homes (because of absent or abusive fathers), but some had stable homes. Most of them showed substantial capability to overcome adverse home environments. The public health system helped them deal with their health problems and their children's health problems, although it also created anxiety in many cases. Our data show how they develop their capabilities and overcome obstacles organically in the face of resource limitations. Despite pregnancies being unexpected and unplanned and fathers being absent, the respondents accepted the pregnancy, adjusted their diets and social behaviour, showed agency by attending primary healthcare facilities and ensured that their children received the required vaccinations. Their extended families played an important role in providing care. Despite the sacrifices, the respondents expressed joy and helped their children function by eating, playing, socializing, learning and using their senses. CONCLUSION: Our sample of mothers have the agency to adapt to the demands of parenthood and childcare and overcome adversity. Our data support the notion that mothers are held disproportionately and unfairly responsible for achieving the first 1000 days ideals. Despite considerable curtailment of their functionings and capabilities, they nevertheless showed agency to ensure their health and their children's health. A holistic approach should consider these findings in designing policy interventions for children's developmental health. PATIENT AND PUBLIC CONTRIBUTION: We used paid fieldworkers to interact with the research participants.

Hope and mental health problems among orphans and vulnerable children in South Africa.

ABSTRACTThere are over three million orphaned and vulnerable children (OVC) currently living in South Africa. OVC are at high risk for a number of negative outcomes, including poor mental health. Hope has been associated with well-being among youth, including youth in South Africa. However, the relationships between hope and mental health in high-adversity populations such as OVC has not been adequately described. The present study sought to address this research gap by evaluating the relationship between hope and mental health, controlling for gender, age, and orphan status, among OVC. This study includes 8- to 12-year-old OVC (N = 61) in Manguang, Free State, South Africa. Hope was assessed using the Children's Hope Scale (CHS) and mental health outcomes were assessed using the Strengths and Difficulties Questionnaire (SDQ). Hope was significantly, inversely associated with mental health outcomes after controlling for other variables in linear regression analysis. In contrast to previous research, this study found that increased hope scores were associated with adverse mental health outcomes among OVC in South Africa. Hope may be contextualized differently in this population due to resource scarcity and high rates of adversity including HIV-AIDS related stigma and poverty.

Housing and Child Health in South Africa: The Value of Longitudinal Research.

Research investigating the link between housing and health often produces mixed results. It does not always prove that good housing improves health. The results suggest a complex set of factors play a role, and the findings are sometimes contradictory. Two ways of addressing these concerns are longitudinal research, where the relationship between housing and health is measured in the short and medium terms, and a focus on children. We use the children's housing and health data from the five waves of the National Income and Distribution Survey (NIDS) survey in South Africa, 2008 to 2017. We investigate the effect that continued living in informal housing over the five waves has had on these children's health. Our results show a statistically significant relationship between prolonged residence in poor housing and poor health outcomes for some health indicators. The results call for a closer understanding of health issues in housing policy in South Africa.

Mediational Intervention for Sensitizing Caregivers to Improve Mental Health Outcomes in Orphaned and Vulnerable Children.

OBJECTIVE: There is an urgent need to equip community-based careworkers with the skills to address the mental health needs of orphans and vulnerable children (OVC) as an essential response to shortages in human resources for mental health in Sub-Saharan Africa. We conducted a quasi-experimental feasibility trial in South Africa to adapt and evaluate an established year-long semi-structured, manualized video-feedback caregiver intervention (the Mediational Intervention for Sensitizing Caregivers; MISC) for community-based organizations (CBOs). METHODS: Following a year-long iterative cross-cultural adaptation of MISC, we recruited 88 OVC (ages 7-11; 45.5% girls) and their CBO careworkers (N = 18; 94.4% female). Two CBOs (45 children; 9 CBO careworkers) received 12 months of MISC, and two CBOs (43 children; 9 CBO careworkers) received treatment as usual. Child mental health and quality of caregiving were assessed at 6 months into the intervention and at completion through multi-informant questionnaires and video-recordings of careworker-child interactions. Qualitative interviews were conducted to evaluate feasibility and acceptability. RESULTS: MISC-CBO was acceptable and feasible in terms of attendance and post-intervention interviews. MISC improved child mental health, as well as the quality of careworker caregiving in terms of interactive effects for affective and cognitive (Expanding) components of MISC, and main effects for the cognitive components of Rewarding and Provision of meaning. MISC components did not mediate the effects of the intervention. CONCLUSIONS: The current study shows that laypersons with no tertiary education and virtually no prior training who undergo MISC training can improve caregiving quality and the mental health of OVCs.

Targeting for male medical circumcision: profiles from two South African cities.

Male circumcision is considered by some to be an acceptable global approach to reduce HIV infections. Consequently, many governments in sub-Saharan Africa run voluntary male circumcision programmes. South Africa also provides male circumcision for free at state clinics and hospitals. Very little is known about the men who use this service. This study uses data from Cape Town, a sample of 1194 in 2016, and from Mangaung, a sample of 277 in 2017 and 2018, to fill this gap. The study finds that age targeting is inadequate, risk targeting is absent, and religious and cultural factors have a negative effect on the cost-efficiency of the service in the long run.

Cultural Consensus Modeling to Understand South African Adolescent Girls' Attitudes, Awareness, and Uptake of Dual Protection Strategies.

PURPOSE: This study used cultural consensus modeling to elucidate culturally relevant factors associated with dual protection use (strategies to prevent both pregnancy and sexually transmitted infection [STI]/HIV) among South African adolescent girls aged 14-17 years. METHODS: In Phase 1, participants (N = 50) completed a free-listing survey assessing pregnancy and STI/HIV methods used by peers. In Phase 2, participants (N = 100) completed a rating survey to examine perceived peer acceptability of Phase 1 pregnancy and STI/HIV prevention methods. In Phase 3, qualitative individual interviews (N = 25) gathered in-depth information regarding the cultural acceptability of pregnancy and STI/HIV prevention strategies. In Phase 4, participants (N = 300) completed the Phase 2 rating survey for individual beliefs regarding the acceptability of pregnancy and STI/HIV prevention methods. RESULTS: In Phase 1, 41 pregnancy and 29 STI/HIV prevention strategies, along with 16 factors influencing pregnancy prevention method acceptability were endorsed; male condoms were the most commonly endorsed pregnancy and STI/HIV prevention method. In Phase 2, using cultural consensus analysis, participants were consistent in the perceived acceptability of pregnancy and STI/HIV prevention methods (73.4% variance accounted for in single cultural model). In Phase 3, qualitative findings provided in-depth information regarding factors influencing commonly used pregnancy (e.g., injectable contraception) and STI/HIV (e.g., condoms) prevention methods. In Phase 4, a single cultural model was identified (56.3% variance accounted for), with similar acceptability ratings as Phase 2. CONCLUSIONS: A singular cultural model of pregnancy and STI/HIV prevention method acceptability was observed, with little awareness of dual protection. The findings highlight cultural factors for future culturally tailored dual protection interventions for South African adolescent girls.

Socio-economic status and socio-emotional health of orphans in South Africa.

This paper investigates the relationship between socio-economic status and emotional well-being of orphans in Mangaung, South Africa. Five hundred orphans aged 7-11 years participated in the cross-sectional study between 2009 and 2012. Data was collected by trained fieldworkers, who conducted face-to-face interviews and questionnaires with the orphans, their teachers and caregivers, and the heads of the households where the orphans resided. The caregivers, children and teachers all completed the Strengths and Difficulties Questionnaire in order to measure the orphans' mental health, while heads of household provided information about socio-economic indicators. STATA version 12 was used to perform multivariate data analyses to identify socio-economic factors associated with the mental health of orphans. Food security, access to medical services and a male caregiver were factors associated with better emotional well-being of orphans, whereas other variables such as household asset index and monthly household expenditure were not linked with the orphans' mental health. Two of the three variables (food security and access to medical services) associated with better emotional well-being of orphans are also government interventions to assist orphans. Further research is needed to determine whether other government programs also impact the emotional well-being of orphans.

Community-based mental health support for orphans and vulnerable children in South Africa: A triangulation study.

Community-based care is receiving increasing global attention as a way to support children who are orphaned or vulnerable due to the HIV/AIDS pandemic. Using both qualitative and quantitative methodology, this study assesses community-based responses to the well-being of orphans and vulnerable children (OVC) and compares these responses with the actual mental health of OVC in order to evaluate the South African government's approach of funding community-based organisations (CBOs) that support and care for OVC. The study results show that the activities of CBOs mainly extend government services and address poverty. Although this should not be seen as insignificant, the paper argues that CBOs give very little attention to the mental health of OVC.

Housing conditions and mental health of orphans in South Africa.

Literature from the developed world suggests that poor housing conditions and housing environments contribute to poor mental health outcomes, although research results are mixed. This study investigates the relationship between housing conditions and the socio-emotional health of orphans and vulnerable children (OVC) in South Africa. The results of the study are mainly inconclusive, although it is suggested that methodological considerations play a vital role in explaining the mixed results. However, a positive relationship was found between living in informal settlements and better socio-emotional health of the OVC. We speculate that the historical context of informal settlement formation in South Africa helps to explain this unexpected result.