Guest Editorial

Acute viral bronchiolitis in South Africa: Diagnosis and current managemen

Synthesis of Control Elements from Petri Net Models

Methods are presented for synthesizing delay-insensitive circuits whose behavior is specified by Petri net models of macromodular control elements. These control elements implement five natural functions used in asynchronous system design. Particular attention is paid to modules requiring mutual exclusion where metastability must be carefully controlled

Childhood pneumonia in Sub-Saharan Africa: Still a challenge

No abstrac

Connecting species’ geographical distributions to environmental variables: range maps versus observed points of occurrence

Connecting the geographical occurrence of a species with underlying environmental variables is fundamental for many analyses of life history evolution and for modeling species distributions for both basic and practical ends. However, raw distributional information comes principally in two forms: points of occurrence (specific geographical coordinates where a species has been observed), and expert-prepared range maps. Each form has potential short-comings: range maps tend to overestimate the true occurrence of a species, whereas occurrence points (because of their frequent non-random spatial distribution) tend to underestimate it. Whereas previous comparisons of the two forms have focused on how they may differ when estimating species richness, less attention has been paid to the extent to which the two forms actually differ in their representation of a species’ environmental associations. We assess such differences using the globally distributed avian order Galliformes (294 species). For each species we overlaid range maps obtained from IUCN and point-of-occurrence data obtained from GBIF on global maps of four climate variables and elevation. Over all species, the median difference in distribution centroids was 234 km, and median values of all five environmental variables were highly correlated, although there were a few species outliers for each variable. We also acquired species’ elevational distribution mid-points (mid-point between minimum and maximum elevational extent) from the literature; median elevations from point occurrences and ranges were consistently lower (median −420 m) than mid-points. We concluded that in most cases occurrence points were likely to produce better estimates of underlying environmental variables than range maps, although differences were often slight. We also concluded that elevational range mid-points were biased high, and that elevation distributions based on either points or range maps provided better estimates

Childhood pneumonia - progress and challenges

No Abstract. South African Medical Journal Vol. 96(9) (Part 2) 2006: 890-89

New advances in cystic fibrosis - implications for developing countries

No Abstract

Asthma - is survival good enough?

Advances in asthma management, particularly the introduction of controller medication of which inhaled corticosteroids are the most important, has resulted in a steady decline in asthma mortality in most countries. This is usually accompanied by a decline in episodes of near-fatal asthma attacks and hospitalisations, and a reduction in other indicators of asthma morbidity. These gains have led to a shift in thinking on the management of asthma, away from simply preventing death and hospitalisations, toward achieving and maintaining sustained control of all clinical features