Gene flow and population structure of a solitary top carnivore in a human-dominated landscape.

While African leopard populations are considered to be continuous as demonstrated by their high genetic variation, the southernmost leopard population exists in the Eastern and Western Cape, South Africa, where anthropogenic activities may be affecting this population's structure. Little is known about the elusive, last free-roaming top predator in the region and this study is the first to report on leopard population structuring using nuclear DNA. By analyzing 14 microsatellite markers from 40 leopard tissue samples, we aimed to understand the populations' structure, genetic distance, and gene flow (Nm). Our results, based on spatially explicit analysis with Bayesian methods, indicate that leopards in the region exist in a fragmented population structure with lower than expected genetic diversity. Three population groups were identified, between which low to moderate levels of gene flow were observed (Nm 0.5 to 3.6). One subpopulation exhibited low genetic differentiation, suggesting a continuous population structure, while the remaining two appear to be less connected, with low emigration and immigration between these populations. Therefore, genetic barriers are present between the subpopulations, and while leopards in the study region may function as a metapopulation, anthropogenic activities threaten to decrease habitat and movement further. Our results indicate that the leopard population may become isolated within a few generations and suggest that management actions should aim to increase habitat connectivity and reduce human-carnivore conflict. Understanding genetic diversity and connectivity of populations has important conservation implications that can highlight management of priority populations to reverse the effects of human-caused extinctions

Die Voedingstand van die Suid-Afrikaanse Bevolking

During the period 1970 to 1975 the world population grew at an average annual rate of 1,98%. At presentthe estimated world population is 4,2 milliard (4,2 x 109). Food production has the formidable task of feeding85 million extra mouths per year.A recent United Nations document stated that during 1974 already about 500 million people suffered fromsome form of malnutrition. Of these about 100 million children under the age of 5 years were malnourished.According to the Gomez classification, which is accepted by the World Health Organization, first degreeprotein-energy-malnutrition (PEM) is present in children who have body weights between 75 and 90% of theexpected weight for age and sex. Children with body weights between 60 and 75% of the expected weight forage and sex suffer from second degree PEM (moderate). Third degree PEM (severely malnourished) is foundin children who reached 60% or less of the expected body weight for age and sex or suffer from oedema.Data are presented for the incidence of malnutrition in Africa and other parts of the world.South Africa and its newly independent territories have a total population of 27,2 million for whom 122,111million hectares of land is available. A hundred million hectares can be used for agricultural purposes andonly 15% of this land is arable.South African food production managed to remain comfortably ahead of population growth over the pastfew decades. At present at least 25 210 kilojoules/capita/day and 146,9g protein/capita/day are available forevery citizen. Despite such an enviable food position we have a considerable problem of malnutrition in SouthAfrica. Firstly, obesity is endangering the health of a fair portion of all ethnic groups. Secondly PEM andvitamin deficiency diseases are frequently diagnosed in the lower socio-economic groups. During 1976 286district surgeons reported 48 783 cases of kwashiorkor, 37 855 cases of pellagra and 1 008 cases of beri-beri.Although some of these diagnoses are unreliable, such figures do give a rough estimate of the extent ofmalnutrition in South Africa. These figures indicate that less than 3% of the population under the age of 5years suffer from kwashiorkor, pellagra and beri-beri.The applicability of the Boston standards to other populations is questioned. It is indicated that thesestandards give false high values for PEM amongst obviously obese South African Indians.The compilation of specific sets of standards for the South African population is suggested

Simulation and Testing of a Latent Heat Thermal Energy Storage Unit with Metallic Phase Change Material

AbstractLatent heat thermal energy storage in metallic phase change materials offers a thermal energy storage concept that can store energy at higher temperatures than with sensible thermal energy storage. This may enable the use of high efficiency thermodynamic cycles in CSP applications, which may lead to a reduction in levelised cost of electricity. Eutectic aluminum silicon alloy, AlSi12, is an attractive phase change material because of its moderate melting temperature, high thermal conductivity, and high heat of fusion. A prototype thermal energy storage test rig has been built and tested as to better understand the behavior of latent heat thermal energy storage. A mathematical model was developed to predict the behavior of such a heat storage unit. The model was compared with the behavior of the test rig during discharge. The model proved to simulate the latent heat thermal energy storage with reasonable accuracy. It is recommended that more accurate material property data be obtained and that the thermal energy storage test rig be modified as to improve readings