Coverings and Descent Theory of Finite Spaces

This thesis presents the categorical Galois theory of the reflection of the category of finite topological spaces into the category of discrete finite topological spaces. This turns out to be nothing but the equivalence between the category of coverings of a connected finite topological space and the actions of the fundamental group of that space. Since some descent theory is necessary for categorical Galois theory, this thesis also contains an account of some of the descent theory of finite topological spaces. The reader is assumed to know the basics of category theory, but no descent theory or categorical Galois theory, or even internal category theory, but to be somewhat familiar with coverings and fundamental groups, and the notion of “locally” for topological spaces

The burden of cardiovascular disease in Sub-Saharan Africa

The burden of cardiovascular disease (CVD) in Africa is growing and changing in nature. From the predominance of rheumatic heart disease and cardiomyopathies 50 years ago to hypertensive heart disease and haemorrhagic stroke in the past 25 years. Albeit at low prevalence, an increase in incidence of ischaemic heart disease is now being seen, particularly in urban areas. These changes in the extent and nature of CVD are thought to be the result of the so-called “epidemiological transition”. The challenge for health promotion and prevention is to accelerate the course of that transition and blunt its magnitude in order to avoid the massive epidemics of CVD that were seen in Europe and the USA in the mid-twentieth century

Computational modelling of cardiac function and myocardial infarction

Includes abstract.Includes bibliographical references.Cardiovascular disease is a leading cause of death in South Africa. In particular non-fatal myocardial infarction is a key determinant for future cardiac failure due to adverse remodelling and electrophysiological dysfunction. Computational modelling of the electrophysiology and mechanics of the heart can provide useful insights into the causes of cardiac failure and the efficacy of treatments designed to combat myocardial infarction. A computational model of the healthy and infarcted left ventricle of a rat was developed using the eikonal diffusion equation to simulate the electrophysiology; a continuum mechanical model incorporating a passive mechanical model of Usyk to describe the nonlinear, anisotropic and nearly compressible nature of cardiac tissue; and an active stress model of Guccione to model the contraction of cardiac tissue. Boundary conditions modelling the blood pressure on the heart wall were applied to simulate the cardiac cycle

The impact of real exchange rate on exports in South Africa

The purpose of this study is to establish the impact of real exchange rate on exports in South Africa. In conducting the empirical test, the Vector Error Correction Model and annual time series data between 1973 and 2014 has been utilised. In the model, exports are the dependent variable and the real effective exchange rates, gross domestic product, mining, agricultural, foreign direct investments, and merchandise export prices are explanatory variables. A significant inverse relationship between real effective exchange rates and exports was confirmed in line with economic theory. Except for the Gross Domestic Product which exhibited a positive relationship, all other explanatory variables displayed an inverse relationship with exports. All other variables exhibited a significant impact except for Foreign Direct Investments. Based on the findings of this study, firm and practical policy recommendations are made including a moderated adjustment of monetary and fiscal policy to ensure competitiveness on the supply side

South Africa's Experience of the Closure of the Cellulose Sulphate Microbicide Trial

The researchers who conducted the cellulose sulphate microbicide trial share the lessons they learned from the trial's early closure

EFEKTIVITAS SEDIAAN TINGTUR EKSTRAK DAUN BANDOTAN (Ageratum conyzoides L.) TERHADAP PENYEMBUHAN LUKA PADA TIKUS PUTIH (Rattus norvegicus)

Bandotan (Ageratum conyzoides L.) adalah sejenis tanaman pengganggu yang bagian daunnya dapat digunakan sebagai penyembuh luka karena mempunyai sifat hemostatik. Penelitian sebelumnya telah dilakukan dengan konsentrasi 15% dibuat dalam sediaan krim dan menunjukkan aktivitas dapat mempercepat pertumbuhan serabut kolagen. Tujuan dalam penelitian ini untuk mengetahui efektivitas sediaan tingtur ekstrak etanol daun bandotan dengan variasi konsentrasi 5%, 15%, dan 45% terhadap penyembuhan luka pada tikus putih (Rattus norvegicus). Metode dalam penelitian ini yakni determinasi tumbuhan, ekstraksi dengan metode maserasi, pengeringan ekstrak dengan metode freeze drying, pembuatan sediaan tingtur dengan variasi konsentrasi yakni 5%, 15% dan 45% dan pengujian efektivitas sediaan tingtur ekstrak daun bandotan pada tikus putih yang telah diberi luka sayat. Hasil penelitian menunjukkan sediaan tingtur ekstrak daun bandotan dengan konsentrasi 5%, 15%, dan 45% mempunyai efektivitas terhadap penyembuhan luka pada tikus putih dengan penutupan luka yang sempurna dibandingkan dengan pemberian povidon iodin. Kesimpulan dari penelitian ini sediaan tingtur ekstrak daun bandotan dengan variasi konsentrasi 5%, 15%, dan 45% mempunyai efektivitas terhadap penyembuhan luka pada tikus putih dan terdapat perbedaan yang signifikan terhadap penyembuhan luka pada tikus putih. Kata Kunci : ekstrak daun bandotan, penyembuhan luka baru, sediaan tingtu