Lattice Knots in a Slab

In this paper the number and lengths of minimal length lattice knots confined to slabs of width $L$, is determined. Our data on minimal length verify the results by Sharein et.al. (2011) for the similar problem, expect in a single case, where an improvement is found. From our data we construct two models of grafted knotted ring polymers squeezed between hard walls, or by an external force. In each model, we determine the entropic forces arising when the lattice polygon is squeezed by externally applied forces. The profile of forces and compressibility of several knot types are presented and compared, and in addition, the total work done on the lattice knots when it is squeezed to a minimal state is determined

The Compressibility of Minimal Lattice Knots

The (isothermic) compressibility of lattice knots can be examined as a model of the effects of topology and geometry on the compressibility of ring polymers. In this paper, the compressibility of minimal length lattice knots in the simple cubic, face centered cubic and body centered cubic lattices are determined. Our results show that the compressibility is generally not monotonic, but in some cases increases with pressure. Differences of the compressibility for different knot types show that topology is a factor determining the compressibility of a lattice knot, and differences between the three lattices show that compressibility is also a function of geometry.Comment: Submitted to J. Stat. Mec

The aims of initiation ceremonies at universities: Comparisons in time and space1

In this article initiation practices at South African universities are analysed and compared with initiation ceremonies described in anthropological literature. It is argued that any initiation ceremony has at least the partial aim of preparing initiates for the roles and functions in society or specific organizations. Naturally a reasonable degree of harmony between the intent of initiation on the one hand and the values of an institution on the other hand can be expected. The intention of initiation usually is to prepare one for a position or rote by means of the expression of certain values. On the question whether this harmony between ideas and actions is found in the case of existent initiation ceremonies at South African universities, the answer is negative. These ceremonies do not aim to convey and develop attitudes and values essential to a university and in fact do not prepare first-year students for their new environment and a community of scholars. The way in which universities transcend their authority by condoning and officially allowing the demeaning initiation practices is also questioned

Anthropology, social change and the reconstruction of South African society1

In this article it is argued that, since the abuse of anthropology in the colonial and apartheid eras, the responsive relationship between anthropology and society has been re-emphasised. In the reconstruction of South African society, therefore, anthropologists will not be allowed the luxury of evading their social responsibility. In their re-invention of anthropology as a humane science, and the reiteration of their commitment to accountability and relevance, these scientists ought to build their discipline upon the investigation of the major consequences of differential power and inequality. This could be helpful in creating new forms of co-existence in South Afric

Manufacturing challenges for custom made solar vehicles in South Africa

Solar challenges are designed to test the reliability and efficiency of solar powered vehicles in endurance races. In the past these manufactured vehicles were technology drivers and led to advances in electric motors and solar cell efficiency. The speed in relation to power consumption is one of the main design considerations, with the only energy source being solar power. In the design and manufacturing of these vehicles a number of requirements need to be met in order to pass the safety standards. The Sasol Solar Challenge (SSC) created an opportunity for South African universities to design and manufacture custom made solar powered vehicles. This paper explores and discusses the challenges for manufacturing solar vehicles in South Africa. Key elements like the communication gap between design and manufacturing, the cost of lightweight solar encapsulation, the shortage of local suppliers and expertise in composite manufacturing are evaluated. These insights can be used as foundation for strategic decisions by future stakeholders

Case Study: An unusual case of Wernicke’s encephalopathy - Thiamin deficiency in advanced gastric adenocarcinoma

No Abstract

The epidemiology of traumatic brain injuries sustained by children under 10 years of age presenting to a tertiary hospital in Soweto, South Africa

Background. Traumatic brain injury (TBI) in the paediatric population is a significant contributor to death and disability worldwide. In sub-Saharan Africa, death and disability from TBI are still superseded by infectious disease. Mechanisms of injury differ by region and socioeconomics, but in general, falls, road traffic collisions (RTCs), being ‘struck by/against objects’ and non-accidental injuries (NAIs) are responsible for most cases.Objectives. To: (i) quantify the burden of TBI in terms of demographics, causes and severity; (ii) explore resource utilisation regarding length of stay, computed tomography (CT) brain scan use and multidisciplinary participation; (iii) interrogate possible temporal patterns of injury; and (iv) thus identify potential targets for community-based prevention strategies.Methods. In a 5-year retrospective review of all children aged <10 years admitted with TBI between September 2013 and August 2018, demographics, date of injury, mechanism of injury, severity of TBI based on the Glasgow Coma Scale, and requirement for a CT brain scan were collected for each patient. Outcomes were reported as discharge, transfer or death. Outcomes for children sustaining isolated TBI were compared with those for children sustaining TBI with polytrauma.Results. A total of 2 153 patients were included, with a mean (standard deviation) age of 4.6 (2.7) years and a male/female ratio of 1.7:1. RTCs were the most frequent cause of injury at 59% (80% of these were pedestrian-vehicle collisions), followed by falls at 24%. Mild TBIs accounted for 87% of admissions, moderate injuries for 6%, and severe injuries for 7%. Polytrauma was associated with increased severity of TBI. The cohort had a 2.3% mortality. NAIs accounted for 6% of injuries and carried a 4% mortality. The median (interquartile range) duration of hospitalisation was 1 (1 - 3) days, ranging from <24 hours to 132 days. CT scans were performed on 43% of admitted patients, and 48% of patients had consultations with another medical or allied medical discipline. Injuries were more frequent during the summer months and over weekends. Infants aged <1 year were identified as a group particularly vulnerable to injury, specifically NAI.Conclusions. Paediatric TBI was demonstrated to be a resource-intensive public health concern. From the results, we identified potential primary prevention targets that could perhaps be incorporated into broader community-based intervention programmes. We also identified a need to study long-term consequences of mild TBI further in our paediatric population

Clinical and psycho-social profile of child and adolescent mental health care users and services at an urban child mental health clinic in South Africa

Objective: National and international child and adolescent mental healthcare policy and action advocate that the health and well being of children should be increasingly given greater attention. The purpose of this study was to describe the demographic, socio economic and clinical profile of the users at the child and adolescent mental health clinic of the Rahima Moosa Mother and Child Hospital (RMMCH). Method: A descriptive, retrospective clinical audit from users’ clinical files was performed over a one-year period from January to December 2007. Descriptive statistical analyses of demographic and socio-economic variables were made and these variables were compared with the presenting clinical problems. Odds ratios were calculated for variables that showed a statistically significant association (p-value less than 0.05). Results: A total of 303 users attended this clinic. Statistical comparisons between demographic data and disorders revealed that being male increased the likelihood of presenting with AHDH and disruptive behaviourdisorders; being female increased the likelihood of being sexually abused. Race showed a significant association with parent-child relationship difficulties. Regarding socio-economic variables, the identity of the caregiver of the child influenced the risk of disruptive behaviour disorders, sexual abuse, neglect and academic problems. Where the child was placed was a risk factor for disruptive behaviour disorders, sexual abuse, neglect and academic problems. Whether the mother of a user was alive or deceased, was found to be related to ADHD and disruptive behaviour and whether the father of a user was alive or deceased, was found to be related to sexual abuse and academic problems. The education level of the caregiver showed a significant association with sexual abuse, neglectand academic problems; the marital status of the parent (widowed mother) showed a significant association with bereavement. Household income was associated with sexual abuse, neglect and academic problems.Conclusion: This study demonstrated the impact that socio-economic circumstances have on the prevalence of childhood disorders; hence the urgent need for government and social welfare departments to improve the socio-economic status of communities. There is a need to improve psychiatric services for the population served by this hospital, including more clinics in its catchment area, as well as child psychiatry training posts and extended social work services.Keywords: Socio-economic variables; Clinical profile; Child and adolescent mental health services; South Afric

Preparing for solar challenge: critical competences acquired in undergraduate engineering education

Abstract: Engineers are expected to function in a highly competitive environment, which demands that projects are developed in increasingly efficient and cost-effective ways, across various disciplines. This trend necessitates multidisciplinary collaboration which requires both traditional engineering skills and so called ‘soft skills’, such as good communicative competences and working cooperatively in teams. In this paper it is described how these skills were developed in the course of the University of Johannesburg’s preparation for participation in the biannual Solar Challenge