Heat and mass transfer effects of ice growth mechanisms in water and aqueous solutions

Includes bibliographical references.Research into ice crystallization processes is an important area of study. The desire to improve product quality and efficiency of processes involving ice crystallization in industries such as desalination by freezing, freeze drying, freeze concentration and freeze crystallization for food processing, requires insight into the ice growth mechanisms. More so, a novel technology called Eutectic Freeze Crystallization, where water is recovered in the form of ice, requires that ice crystals are of high purity as this directly determines the quality of the water obtained. During ice crystallization, ice growth mechanisms play an important role in determining the structure, size and morphology of ice which have an effect on separation processes and product purity. Heat and mass transfer play a fundamental role in ice growth processes as they affect the thermodynamics and kinetics of the crystallization process. Ice growth experiments were carried out in pure water, in 8.4 wt% and 16.8 wt% magnesium sulphate and in 8.4 wt% sodium nitrate using a 10x5x31 mm test cell made of Plexi-glass®. The Colour Schlieren optical technique was used to conduct the experiments. This is because of its capability to map refractive index gradients related to either temperature or/and concentration gradients of the solution during crystal growth

Wildlife rights and human obligations

Despite exponential growth of the field of animal ethics, wildlife ethics has continued to be a fringe discussion. My thesis seeks to make a theoretical contribution by focusing only on human-induced harms to wild animals. I use the rights approach to investigate demands of wildlife justice on human behaviour and wildlife policy. I take rights to be the best normative resource for determining and evaluating just and unjust relations. Given the fundamental position of moral rights that I espouse, moral rights must constitute the core of an ethically sound wildlife policy. The analytical framework I deploy throughout the thesis consists of the Interest Theory of Rights couched in the Hohfeldian matrix of rights. This framework provides some insights for improving on the influential rights approach expounded by Tom Regan. I apply the adopted rights view to several important ethical conundrums. These include the institution of wildlife property; human interference in wildlife predation and wildlife population control; humanwildlife conflict; and state obligations to ensure wildlife justice. From the rights view, I conclude that wild animals are morally not human property and that they are in fact owners of their habitats and the natural goods on which their wellbeing depends. Humans are morally prohibited from killing predators or lethally controlling wildlife populations except in the unlikely event of preventing an ecological catastrophe. Furthermore, humans are permitted in their acts of self- or other- defence in those circumstances where the humans are innocent and are not morally liable. Policies and cultures that allow the killing of wildlife as a resource are unjust and therefore prohibited. Lastly, I contend that the responsibility for protecting wildlife lies with all states whose citizens, organisations, or corporations harm wildlife anywhere on earth. The diffuse and extraterritoriality of unjust harms to wild animals seems to require a cooperative international approach to securing wildlife rights

Factors associated with provision of mothers' own breast milk for Very Low Birth Weight (VLBW) infants on a South African tertiary care neonatal unit

Background: The maternal struggle to provide adequate breast milk for the infants' nutritional needs disadvantage preterm infants as the outcomes of those exclusively breast milk fed are superior to those fed infant formula. Objectives: To determine the proportion of Mothers' Own breast Milk (MOM) consumed by very low birth weight (VLBW) infants at Groote Schuur Hospital and explore potential maternal difficulties to provide MOM. Methods: In a prospective cross sectional study of 104 VLBW infant-mother dyads admitted between January and May 2015, an interviewer administered a structured questionnaire to the participating mothers before day 3 and on day 14. Infant folders were reviewed for gestational age, weight, and mode of delivery and the proportion of MOM received on days 1, 7 and 14 of life. Results: Ninety-one (88%) infants received 75% of enteral feeds in 60 infants (62%) on day 14 of life and 56(57.7%) received 100% as MOM. Infants with 2 or less siblings (22.2% vs 33.7% p=0.010) received a greater proportion MOM on day 14 as compared to those with larger families. 85.7% of the interviewed mothers would have preferred to stay in the hospital with their infants post discharge. Infant's weight, mode of delivery, maternal age, HIV status, hypertension, breastfeeding counselling, income, transport mode or distance from the hospital had no impact on MOM provision. Conclusion: Domestic responsibilities may affect mothers' breast milk provision to the newborn preterm. Breast-feeding counselling did not improve breast milk provision in this study. The effectiveness of current counselling methods may need to be examined and improved. Facilitating accommodation and rooming in of mother infant pairs from delivery to discharge may be useful in improving MOM provision to VLBW infants

Peritoneal dialysis technique survival at Tygerberg Hospital in Cape Town, South Africa

Background: The use of peritoneal dialysis (PD) as a treatment modality for patients with end-stage renal disease (ESRD) has been declining in many countries over the past few years. One of the reasons is technique failure, which occurs more frequently than is the case with chronic haemodialysis. Identifying and addressing the causes of technique failure is important in order to maintain more patients on PD, especially in settings where there are limited resources for chronic haemodialysis and a “PD first” approach is followed.Methods: In this retrospective study at Tygerberg Hospital in Cape Town, South Africa, we investigated 170 patients who were started on chronic ambulatory PD between January 2008 and July 2014, and determined rates of technique and patient survival. Demographic, clinical and laboratory data were assessed to identify risk factors for these outcomes.Results: The median age of the patients was 36 years and the most common cause of ESRD was glomerulonephritis. Only one patient had diabetes mellitus. Technique survival at 1, 3 and 5 years was 80%, 54% and 39%, respectively, while patient survival was 90%, 82% and 63%. Patients started on PD during the second half of the study period had improved rates of technique survival. Peritonitis was the most common cause of technique failure. Increasing age and Black ethnicity were associated with increased likelihood of technique failure. Other clinical and social factors were not significantly associated with the occurrence of technique failure.Conclusions: In our patients on PD, peritonitis, increased age and Black ethnicity were important factors associated with the development of technique failure. Concerted efforts are required to reduce peritonitis rates at our centre as this is the leading cause of technique failure

Achieving More with Less: Reform and Scaling Down of Food Reserve Agency and Farmer Input Support Programme and Boosting Social Protection

Zambia continues to suffer from a regime of ineffectual subsidies and insufficient social protection. Despite evidence showing how the country’s signature farming input and output subsidy programmes, i.e. the Farmer Input Support Programme (FISP) and the Food Reserve Agency (FRA) respectively, have failed to spur agricultural diversification, address low agricultural productivity, food security, and stubbornly high rural poverty rates, the country has continued to allocate significant resources towards their implementation. Notably, Zambia is currently grappling with the need to make some tough choices as it seeks to deliver on the Zambia-Plus Recovery Plan proposed by the Minister of Finance. Among other options, the government should consider how to scale back on discretionary spending whilst supporting economic growth and social development. Politically, maintaining the status quo is likely to be very costly given that the country can no longer afford the continued financial haemorrhage from the current operations of FISP and FRA. This paper presents a case for reforming FISP and FRA by providing alternative approaches that will work better for both the individual Zambians who rely on the state for support, and the country as a whole

HIV enteropathy and 'Slim disease': Historical and current perspectives.

OBJECTIVES: Chronic diarrhoea and severe wasting associated with HIV infection were first described in East African patients as slim disease (SD) in 1985. The main histological features are flattening of the villi (villous atrophy) and crypt hyperplasia (elongated crypts), i.e., HIV enteropathy (HIVE). Selective loss of mucosal clusters of differentiation 4 (CD4)+ T helper (Th)17+ lymphocytes is the immunological hallmark of HIVE. This review explores (i) the historical background of HIVE and SD, (ii) the relationship between gut mucosal CD4+ Th17+ and intestinal-resident intra-epithelial gamma delta (IRIE) T lymphocytes in pathogenesis of HIVE, (iii) the role of cytokines in regulation of intestinal epithelial proliferation, and (iv) the role of antiretroviral therapy in HIVE. METHODS: Recent studies have highlighted the role of IRIE T lymphocytes, mostly CD8+, in regulating gut epithelial regeneration. CD4+Th17+ and IRIE T cells are necessary to maintain intestinal barrier integrity and mucosal antimicrobial immune defence. However, the immunological cross-talk between such lymphocyte sub-sets culminating in HIVE is uncertain. We undertook a narrative literature review under the headings 'HIVE', 'SD', and 'Highly active antiretroviral therapy (HAART). Relevant studies were located using the electronic search engines Google Scholar and PubMed from 1984 to 2022. RESULTS: Depletion of Th17+ cells in the lamina propria, attributed to low-level viraemia, is accompanied by concomitant increase in the density of gut mucosal IRIE T lymphocytes in AIDS. The latter express a broad range of cytokines (interferon-gamma, tumor necrosis factor-alpha, interleukin-17) and chemokines e.g., keratinocyte growth factor, post exposure to HIV-infected cells. Keratinocyte growth factor induces epithelial proliferation mainly in the crypts, leading to functional immaturity of enterocytes, reduced gut absorptive surface area and malabsorption in animal experiments. Of note, the absence of IRIE T cells is associated with a reduction in epithelial cell turnover. Patients with HIVE receiving early HAART show enhanced expression of mucosal repair genes and improvement of gut symptoms. CONCLUSION: Multiple lines of enquiry suggest HIVE is directly related to HIV infection and is a consequence of perturbations in mucosal CD4+Th17+ and IRIE T lymphocytes. The pathological result is enterocyte immaturity and dysfunction. SD whose main features are malabsorption, diarrhoea and weight loss, is a severe clinical expression of HIVE. A better understanding of immuno-pathogenesis of HIVE opens a window of opportunity for the potential use of immunotherapy in HIV disease and other T cell-mediated enteropathies

Differences in antigen-specific CD4+ responses to opportunistic infections in HIV infection

HIV-infected individuals with severe immunodeficiency are at risk of opportunistic infection (OI). Tuberculosis (TB) may occur without substantial immune suppression suggesting an early and sustained adverse impact of HIV on Mycobacterium tuberculosis (MTB)-specific cell mediated immunity (CMI). This prospective observational cohort study aimed to observe differences in OI-specific and MTB-specific CMI that might underlie this. Using polychromatic flow cytometry, we compared CD4+ responses to MTB, cytomegalovirus (CMV), Epstein-Barr virus (EBV) and Candida albicans in individuals with and without HIV infection. MTB-specific CD4+ T-cells were more polyfunctional than virus specific (CMV/EBV) CD4+ T-cells which predominantly secreted IFN-gamma (IFN-γ) only. There was a reduced frequency of IFN-γ and IL-2 (IL-2)-dual-MTB-specific cells in HIV-infected individuals, which was not apparent for the other pathogens. MTB-specific cells were less differentiated especially compared with CMV-specific cells. CD127 expression was relatively less frequent on MTB-specific cells in HIV co-infection. MTB-specific CD4+ T-cells PD-1 expression was infrequent in contrast to EBV-specific CD4+ T-cells. The variation in the inherent quality of these CD4+ T-cell responses and impact of HIV co-infection may contribute to the timing of co-infectious diseases in HIV infection

Comparison of screening strategies to improve the diagnosis of latent tuberculosis infection in the HIV-positive population: a cohort study

Background HIV is the most important risk factor for progression of latent tuberculosis infection (LTBI) to active tuberculosis (TB). Detection and treatment of LTBI is necessary to reduce the increasing burden of TB in the UK, but a unified LTBI screening approach has not been adopted. Objective To compare the effectiveness of a TB risk-focused approach to LTBI screening in the HIV-positive population against current UK National Institute for Health and Clinical Excellence (NICE) guidance. Design Prospective cohort study. Setting Two urban HIV treatment centres in London, UK. Participants 114 HIV-infected individuals with defined TB risk factors were enrolled prospectively as part of ongoing studies into HIV and TB co-infection. Outcome measures The yield and case detection rate of LTBI cases within the research study were compared with those generated by the NICE criteria. Results 17/114 (14.9%, 95% CI 8.3 to 21.5) had evidence of LTBI. Limiting screening to those meeting NICE criteria for the general population (n=43) would have detected just over half of these, 9/43 (20.9%, 95% CI 8.3 to 33.5) and those meeting criteria for HIV co-infection (n=74) would only have captured 8/74(10.8%, 95% CI 3.6 to 18.1) cases. The case detection rates from the study and NICE approaches were not significantly different. LTBI was associated with the presence of multiple TB risk factors (p=0.002). Conclusion Adoption of a TB risk-focused screening algorithm that does not use CD4 count stratification could prevent more cases of TB reactivation, without changing the case detection rate. These findings should be used to inform a large-scale study to create unified guidelines

Legalizing illegalities? Land titling and land tenure security in informal settlements

This study investigated how land rights formalization had affected land tenure security among landowners in two informal settlements of Lusaka and Chongwe districts, Zambia. It explored how social norms on land inheritance, decision making over land, marital trust and land related conflicts had been affected by the changed nature of land rights. Data was collected through a questionnaire survey of all the 302 households that had obtained title deeds at the time of the survey, two 3-in-1 focus group discussions and four key informant interviews. Results suggest that land tenure security is now a reality for residents that hitherto lived under constant threat of eviction. Landowners have benefitted from the formalization initiative through land laws and local norms that allow equitable access to land. Land rights formalization has curtailed land rights for secondary claimants such as extended family members, in preference for man, spouse and biological children. A sense of ownership undisputedly increased for men and women in the two study sites. About 50% of the respondents in both study sites indicated that formalization of land rights had not resulted in family conflicts. At least one-third from both sites reported an increase in love and trust between spouses after land rights formalization. About half of the respondents reported that no change in decision-making authority had occurred for men while 42% reported an increase. Formalizing land rights in informal settlements has entailed legalizing illegalities as regulations on plot boundaries are set aside by the state to achieve its aspirations of providing land tenure security to poor urbanites who would not otherwise have recourse to legal or regularized land. We recommend that caution be taken in promoting what is unarguably a pro-poor initiative to ensure that such initiatives should not incentivize future land encroachments

Bridging the gap in neonatal resuscitation in Zambia

Neonatal resuscitation has been poorly instituted in many parts of Africa and most neonatal resuscitation algorithms are adapted from environments with abundant resources. Helping Babies Breathe (HBB) is an algorithm designed for resource-limited situations and most other algorithms are designed for resource-rich countries. However, there are neonatal referral centers in resource-limited countries who may provide more advanced resuscitation. Thus, we developed a neonatal resuscitation algorithm for a resource-limited country (Zambia) which considers more advanced interventions in situations where they can be provided. The algorithm described in this paper is based on the Newborn Life Support algorithm from the UK as well as the HBB algorithm and accounts for all situations in a resource-limited country. Most importantly, it focuses on non-invasive ventilation but includes advice on more advanced resuscitation including intravenous access, fluid management, chest compressions and adrenaline for resuscitation. Although intubation skills are included in neonatal training workshops, it is not the main focus of the algorithm as respiratory support equipment is scarce or lacking in most health facilities in Zambia. A home-grown neonatal resuscitation algorithm for a resource-limited country such as Zambia is likely to bridge the gap between limited situations requiring only bag and mask ventilation and better equipped institutions where more advanced resuscitation is possible. This algorithm will be rolled out in all training institutions and delivery facilities across Zambia over the next months