Thermal Behaviour of Euclidean Stars

A recent study of dissipative collapse considered a contracting sphere in which the areal and proper radii are equal throughout its evolution. The interior spacetime was matched to the exterior Vaidya spacetime which generated a temporal evolution equation at the boundary of the collapsing sphere. We present a solution of the boundary condition which allows the study of the gravitational and thermodynamical behaviour of this particular radiating model.Comment: 10 pages, 3 figure

Thermodynamic structure of field equations near apparent horizon for radiating black holes

We study the intriguing analogy between gravitational dynamics of the horizon and thermodynamics for the case of nonstationary radiating spherically symmetric black holes both in four dimensions and higher dimensions. By defining all kinematical parameters of nonstationary radiating black holes in terms of null vectors, we demonstrate that it is possible to interpret the Einstein field equations near the apparent horizon in the form of a thermodynamical identity $TdS=dE+PdV$

Non-adiabatic radiative collapse of a relativistic star under different initial conditions

We examine the role of space-time geometry in the non-adiabatic collapse of a star dissipating energy in the form of radial heat flow, studying its evolution under different initial conditions. The collapse of a star with interior comprising of a homogeneous perfect fluid is compared with that of a star filled with inhomogeneous imperfect fluid with anisotropic pressure. Both the configurations are spherically symmetric, however, in the latter case, the physical space $t= constant$ of the configurations is assumed to be inhomogeneous endowed with spheroidal or pseudo-spheroidal geometry. It is observed that as long as the collapse is shear-free, its evolution depends only on the mass and size of the star at the onset of collapse.Comment: To appear in Pramana- j. of physic

Stellar models with Schwarzschild and non-Schwarzschild vacuum exteriors

A striking characteristic of non-Schwarzschild vacuum exteriors is that they contain not only the total gravitational mass of the source, but also an {\it arbitrary} constant. In this work, we show that the constants appearing in the "temporal Schwarzschild", "spatial Schwarzschild" and "Reissner-Nordstr{\"o}m-like" exteriors are not arbitrary but are completely determined by star's parameters, like the equation of state and the gravitational potential. Consequently, in the braneworld scenario the gravitational field outside of a star is no longer determined by the total mass alone, but also depends on the details of the internal structure of the source. We show that the general relativistic upper bound on the gravitational potential $M/R < 4/9$, for perfect fluid stars, is significantly increased in these exteriors. Namely, $M/R < 1/2$, $M/R < 2/3$ and $M/R < 1$ for the temporal Schwarzschild, spatial Schwarzschild and Reissner-Nordstr{\"o}m-like exteriors, respectively. Regarding the surface gravitational redshift, we find that the general relativistic Schwarzschild exterior as well as the braneworld spatial Schwarzschild exterior lead to the same upper bound, viz., $Z < 2$. However, when the external spacetime is the temporal Schwarzschild metric or the Reissner-Nordstr{\"o}m-like exterior there is no such constraint: $Z < \infty$. This infinite difference in the limiting value of $Z$ is because for these exteriors the effective pressure at the surface is negative. The results of our work are potentially observable and can be used to test the theory.Comment: 19 pages, 3 figures and caption

Spherically symmetric dissipative anisotropic fluids: A general study

The full set of equations governing the evolution of self--gravitating spherically symmetric dissipative fluids with anisotropic stresses is deployed and used to carry out a general study on the behaviour of such systems, in the context of general relativity. Emphasis is given to the link between the Weyl tensor, the shear tensor, the anisotropy of the pressure and the density inhomogeneity. In particular we provide the general, necessary and sufficient, condition for the vanishing of the spatial gradients of energy density, which in turn suggests a possible definition of a gravitational arrow of time. Some solutions are also exhibited to illustrate the discussion.Comment: 28 pages Latex. To appear in Phys.Rev.

Nurses’ monitoring of the Road to Health Chart at primary healthcare level in Makhado, Limpopo province

Background: The Road to Health Chart (RTHC) is a record chart carried by the caregiver that combines essential information on the growth monitoring of a child, immunisation, vitamin A supplementation, deworming medicine and other illnesses. It provides useful information to the parent and healthcare professional. This study sought to determine the challenges faced by professional nurses in monitoring the RTHC during consultation, the degree of implementation of the RTHC programme, and the most utilised aspect of the RTHC at Louis Trichardt Memorial Hospital and surrounding primary healthcare (PHC) clinics.Method: A cross-sectional study was conducted among 128 registered professional nurses. A self-administered questionnaire was used.Results: Ninety-six questionnaires were completed. Most of the respondents were female and aged 40-49 years. The majority of the PHC professional nurses stated that the challenges faced in monitoring the RTHC were staff shortages, lack of equipment, a work overload and unequal distribution of professional nurses on duty per shift. There was poor knowledge on how to identify malnutrition. The majority of PHC professional nurses had not completed their basic courses.Conclusion: PHC professional nurses voiced their concern that challenges encountered during consultations were direct reasons for their poor monitoring of the RTHC. The degree of implementation of the RTHC programme fell short of the norms and standards of the Department of Health and Social Development concerning child health care in South Africa. The most utilised aspect of the RTHC was the expanded programme on immunisation, vitamin A supplementation and deworming medicine.Keywords: immunisation, malnutrition, anthropometric indices, child mortality, child healt

The profile of disability grant applicants in Bishop Lavis, Cape Town

Background: Disability grants in South Africa increased from 600 000 in 2000 to almost 1.3 million in 2004. This rise can be attributed to the HIV/AIDS epidemic, South Africa’s high rate of unemployment and possibly an increased awareness of constitutional rights. The Western Cape, which hasa disability prevalence of 3.8%, has also experienced an influx of applications. The study was conducted at Bishop Lavis Community Health Centre (BLCHC) in the Cape Town Metropole, Western Cape.The primary aim of this study was to establish the profile of adults applying for disability grants at Bishop Lavis. The secondary aim was thedetermination of the degree of activity limitation and participation restriction by means of the International Classification of Functioning, Disability and Health (ICF) shortlist of activity and participation domains.Methods: A descriptive study was conducted with emphasis on identifying and quantifying the relevant factors. The population studied included allprospective adult (18–59-year-old females and 18–64-year-old males) disability grant applicants in Bishop Lavis over a two-month period (April–May 2007). A structured, self-compiled questionnaire was administered during face-to-face interviews with applicants. The questionnaire included the demographic details of the applicants, disability/chronic illness/condition, educational level and social/living conditions. The second part of the questionnaire was based on the ICF shortlist of activity and participation.Results: There were 69 respondents over the period of data collection. Of the 69 applicants who participated in the study, 45 (65%) receiveda temporary disability grant, 6 (8%) received a permanent grant and 18 (26%) applications were rejected. The results demonstrated that mostapplicants were females over the age of 50, were poorly educated with chronic medical conditions and were living in formal accommodation withgood basic services but with minimal or no disposable income. The ICF questionnaire responses showed that the majority of respondents had nodifficulty in most domains, except for the general tasks and demands (multiple tasks), mobility (lifting and carrying, fine hand use and walking) and domestic tasks domains, which showed high percentages of severe to complete difficulty. However, further statistical analysis showed no association between degree of difficulty in the above domains and eventual outcome of type of grant received.Conclusions: This study confirmed that unemployment and a lack of income are the factors influencing patients to seek assistance in the formof disability grants. Most applicants had a chronic medical condition and reported functional restrictions but only received a temporary grant. Thismay be an indication that most patients require further evaluation before a final decision can be made. There is a need for a standardised, objectiveassessment tool for disability grant applications. A campaign to educate patients about disability grants could save patients and hospital medicalservices time and money

Very Low Levels of 25-Hydroxyvitamin D Are Not Associated With Immunologic Changes or Clinical Outcome in South African Patients With HIV-Associated Cryptococcal Meningitis

Background. Vitamin D deficiency is associated with impaired immune responses and increased susceptibility to a number of intracellular pathogens in individuals infected with human immunodeficiency virus (HIV). It is not known whether such an association exists with Cryptococcus neoformans. Methods. Levels of 25-hydroxyvitamin D (25[OH]D) were measured in 150 patients with cryptococcal meningitis (CM) and 150 HIV-infected controls in Cape Town, South Africa, and associations between vitamin D deficiency and CM were examined. The 25-hydroxyvitamin D levels and cryptococcal notifications were analyzed for evidence of reciprocal seasonality. Associations between 25(OH)D levels and disease severity, immune responses, and microbiological clearance were investigated in the patients with CM. Results. Vitamin D deficiency (plasma 25[OH]D ≤50 nmol/L) was present in 74% of patients. Vitamin D deficiency was not associated with CM (adjusted odds ratio, 0.93 [95% confidence interval, .6–1.6]; P = .796). Levels of 25(OH)D showed marked seasonality, but no reciprocal seasonality was seen in CM notifications. No significant associations were found between 25(OH)D levels and fungal burden or levels of tumor necrosis factor α, interferon γ, interleukin 6, soluble CD14, or neopterin in cerebrospinal fluid. Rates of fungal clearance did not vary according to vitamin D status. Conclusions. Vitamin D deficiency does not predispose to the development of CM, or lead to impaired immune responses or microbiological clearance in HIV-infected patients with CM