An investigation of impact breakage of rocks using the split Hopkinson pressure bar

Discrete element methods (DEM) are being used to provide detailed impact histories of the particles in comminution devices, such as mills. To match this immense detail of information, far more informative breakage tests than those that are generally conducted are now required. The split Hopkinson pressure bar apparatus is used in this study, as it allows the calculation of breakage forces and absorbed energies. The geometry of rock particles has been identified as significant, so this project undertook to identify the influence of shape on the breakage pattern of blue stone. Comparisons are then made between the breakage pattern of angular rocks and rounded, milled rocks for single impact fracture and consecutive impact loading at low energy. Results of this experiment indicate that although breakage for both geometries occurs over a similar energy range, rounded particles have the greater probability of fracture because they absorb more of the impact energy for a given loading. Size distributions of progeny show that five pebbles or more are sufficient to predict the distribution of most particles in small energy regimes. Cumulative impact testing shows that considerably more energy is required to break a rock through cumulative damage than through a single impact—this is of considerable importance in the light of the indications from DEM simulations that most breakage in a mill will be from cumulative damage rather than single impact breakage

Knowledge and perceptions of nursing staff on the new Road to Health Booklet growth charts in primary healthcare clinics in the Tygerberg subdistrict of the Cape Town metropole district

Objectives: The objectives of the study were to assess the perceptions of nursing staff on the Road to Health Booklet (RTHB), to assess their knowledge of the RTHB growth charts, and to determine whether the level of knowledge was acceptable for successful utilisation of the RTHB growth charts.Design: A cross-sectional descriptive survey.Setting: Twelve primary healthcare clinics in the Tygerberg subdistrict.Subjects: Nursing staff who were going to work with the RTHB on a daily basis.Outcomes measures: The knowledge and perceptions of the nursing staff on the new RTHB were measured using a self-administered questionnaire.Results: The study highlighted that the majority of the nursing staff did not possess sufficient knowledge to successfully utilise the RTHB. The mean score percentage for the total 12 knowledge questions was 55%. Less than a third (n = 13) of participants could correctly interpret the cut-off value for mid-upper-arm circumference. Only 38% and 52% correctly knew that -2 standard deviation for weight-for-age and weight-for-length represents underweight and wasting, respectively. Fifty-five per cent could correctly interpret the growth faltering graph. Forty-three per cent of participants felt the change to the RTHB was unnecessary, and 55% thought that mothers or caregivers would not easily understand the RTHB. More than half (n = 22) of the participants said that they had adequate knowledge to work with the RTHB, while the rest reported that they did not.Conclusion: The RTHB has the potential to decrease the prevalence of malnutrition in children. However, to achieve this, effective usage and understanding of the RTHB is critical.Keywords: Road to Health booklet, growth monitoring, primary healthcare clinics, knowledg

Social constructions of gender roles, gender-based violence and HIV/AIDS in two communities of the Western Cape, South Africa

The links between gender roles, gender-based violence and HIV/AIDS risk are complex and culturally specific. In this qualitative study we investigated how women and men in two black communities in the Western Cape, South Africa, constructed their gender identities and roles, how they understood gender-based violence, and what they believed about the links between gender relations and HIV risk. First we conducted 16 key informant interviews with members of relevant stakeholder organisations. Then we held eight focus group discussions with community members in single-sex groups. Key findings included the perception that although traditional gender roles were still very much in evidence, shifts in power between men and women were occurring. Also, gender-based violence was regarded as a major problem throughout communities, and was seen to be fuelled by unemployment, poverty and alcohol abuse. HIV/AIDS was regarded as particularly a problem of African communities, with strong themes of stigma, discrimination, and especially ‘othering' evident. Developing effective HIV/AIDS interventions in these communities will require tackling the overlapping as well as divergent constructions of gender, gender violence and HIV which emerged in the study. Keywords: gender roles, gender-based violence, HIV/AIDS, South Africa. RÉSUMÉ Les liens entre les rôles de genre, la violence contre les femmes et le risque du VIH/SIDA sont complexes et culturellement particuliers. Dans cette étude qualitative, nous avons examiné: comment des hommes et des femmes ont construit des identités et les rôles de genre dans deux communautés noires du Cap de l'Ouest, en Afrique du Sud, comment ont-ils compris la violence contre les femmes et ce qu'ils croyaient des liens entre les relations de sexes et le risque du VIH. Dans un premier temps, nous avons mené 16 entretiens principaux d'informateurs auprès des membres des organismes dépositaires. Ensuite, nous avons eu huit discussions des groupes de foyer avec des membres de la communauté en deux groupes différents, un pour les femmes un autre pour les hommes. Les résultats de recherche ont inclus la perception que: même si les rôles de genre traditionnels restent toujours évidents, il y a aussi le déplacement de pouvoir entre les hommes et les femmes. De plus, la violence contre les femmes était vue comme un problème majeur à travers les communautés et d'être aggravée par le chômage, la pauvreté et l'abus d'alcool. Le VIH/SIDA était considéré particulièrement comme un problème des communautés africaines avec des thèmes fortes de stigmatisation, de discrimination et surtout le ‘othering' évidents. Le développement des interventions efficaces du VIH/SIDA dans ces communautés va exiger une maîtrise des constructions de genre qui se recouvrent partiellement et qui sont divergentes également, la violence contre les femmes et le VIH qui ont apparu dans cette étude. Mot clés: les rôles de genre, la violence contre les femmes, le VIH/SIDA, l'Afrique du Sud

An integrated approach to pathogen transmission via environmental reservoirs

To mitigate the effects of zoonotic diseases on human and animal populations, it is critical to understand what factors alter transmission dynamics. Here we assess the risk of exposure to lethal concentrations of the anthrax bacterium, Bacillus anthracis, for grazing animals in a natural system over time through different transmission mechanisms. We follow pathogen concentrations at anthrax carcass sites and waterholes for five years and estimate infection risk as a function of grass, soil or water intake, age of carcass sites, and the exposure required for a lethal infection. Grazing, not drinking, seems the dominant transmission route, and transmission is more probable from grazing at carcass sites 1–2 years of age. Unlike most studies of virulent pathogens that are conducted under controlled conditions for extrapolation to real situations, we evaluate exposure risk under field conditions to estimate the probability of a lethal dose, showing that not all reservoirs with detectable pathogens are significant transmission pathways

Quantifying water requirements of African ungulates through a combination of functional traits

Climate and land use change modify surface water availability in African savannas. Surface water is a key resource for both wildlife and livestock and its spatial and temporal distribution is important for understanding the composition of large herbivore assemblages in savannas. Yet, the extent to which ungulate species differ in their water requirements remains poorly quantified. Here, we infer the water requirements of 48 African ungulates by combining six different functional traits related to physiological adaptations to reduce water loss, namely minimum dung moisture, relative dung pellet size, relative surface area of the distal colon, urine osmolality, relative medullary thickness, and evaporation rate. In addition, we investigated how these differences in water requirements relate to differences in dietary water intake. We observed strong correlations between traits related to water loss through dung, urine and evaporation, suggesting that ungulates minimize water loss through multiple pathways simultaneously, which suggests that each trait can thus be used independently to predict water requirements. Furthermore, we found that browsers and grazers had similar water requirements, but browsers are expected to be less dependent on surface water because they acquire more water through their diet. We conclude that these key functional traits are a useful way to determine differences in water requirements and an important tool for predicting changes in herbivore community assembly resulting from changes in surface water availability

From exclusion to informal segregation: The limits to racial transformation at the University of Natal

In the context of higher education transformation in South Africa, this paper attempts to capture a series of observations about transformation at the forme r University ofNatal. From a descriptive, multidisciplinary perspective it critiques racial transformation at the University as driven by concerns of representivity over the need for desegregation. We base this discussion on three sets of observations: an analysis of institutional policy, a review of demographic change in the staff and student bodies and a study ofstudents ' lived experiences of segregation on campus. During the past decade a great deal ofchange has occurred in the overall racial demographics of the student and staff bodies. While demographic transformation efforts at the University do echo national trends, a closer inspection ofthe policy, practice and lived experience oftransformation at the University reveals that all is not well. In particular, institutional policy with respect to transformation has tended to be reactive and superficial and students experience camp us as a segregated and racialized space. Thus, racial transformation at the University has only been partially successful: while overt racist exclusion is withering, informal segregation and attendant racialization remain

Universities and community-based research in developing countries: community voice and educational provision in rural Tanzania

The main focus of recent research on the community engagement role of universities has been in developed countries, generally in towns and cities and usually conducted from the perspectives of universities rather than the communities with which they engage. The purpose of this paper is to investigate the community engagement role of universities in the rural areas of developing countries, and its potential for strengthening the voice of rural communities. The particular focus is on the provision of primary and secondary education. The paper is based on the assumption that in order for community members to have both the capacity and the confidence to engage in political discourse for improving educational capacity and quality, they need the opportunity to become involved and well-versed in the options available, beyond their own experience. Particular attention is given in the paper to community-based research (CBR). CBR is explored from the perspectives of community members and local leaders in the government-community partnerships which have responsibility for the provision of primary and secondary education in rural Tanzania. The historical and policy background of the partnerships, together with findings from two case studies, provide the context for the paper