Incisor morphology as an aid in the systematics of the South African Leporidae (Mammalia: Lagomorpha)

Photomicrographs of cross-sections through the principal upper incisors of the South African Leporidae were evaluated for use in species identification. Differences in incisor width and the pattern of the enamel fold provide a reliable means of distinction between Lepus capensis and L. saxatilis. Incidental comparisons of incisor cross-sections of the South African L. capensis, including those from the type locality, and the taxonomically controversial L. europaeus reveal marked differences which may be useful in the delimitation of these taxa. Within Pronolagus, distinct differences were evident between the incisor patterns of P. rupestris and its congeners, P. crassicaudatus and P. randensis, which are similar with respect to this character. Similarly, striking differences were evident between the incisors of the monotypic Bunolagus monticularis and both L. saxatilis and, importantly in view of their close phenetic relationship, L. capensis

Influence of a nutritional parameter on the size differences of the three springbok subspecies

Apparent size differences in the three subspecies of the springbok Antldorcas marsupialis were compared in relation to the mean dietary protein values analysed from rumen contents of test animals. Body mass was highly correlated with the winter dietary protein in both sexes. No significant differences were found to exist between the mean body mass values of the two northern subspecies. Significant differences did however exist between the nominate subspecies and the two northern taxa. Similar tendencies were illustrated for most comparisons of subspecific dietary protein values.Waarneembare verskille in grootte van die drie subspesies van die springbok Antidorcas marsupialis is vergelyk met betrekking tot die gemiddelde  proteVenwaarde in die dieet soos verkry deur analise van die rumeninhoud van eksperimentele diere. Daar was by beide geslagte 'n opvallende korrelasie tussen liggaamsmassa en die winterproteTendieet. Geen betekenisvolle verskille is gevind tussen die gemiddelde liggaammassas van die twee noordelike subspesies nie. Oaar is egter betekenisvolle verskille gevind tussen benoemde subspesies en die twee noordelike taksa. Soortgelyke tendense is ook waargeneem met betrekking tot die meeste ander parameters wat vergelyk is met die protei'n waardes in die dieet van hierdie subsDesies

Muon-induced neutron production and detection with GEANT4 and FLUKA

We report on a comparison study of the Monte Carlo packages GEANT4 and FLUKA for simulating neutron production by muons penetrating deep underground. GEANT4 is found to generate fewer neutrons at muon energies above ~100 GeV, by at most a factor of 2 in some materials, which we attribute mainly to lower neutron production in hadronic cascades. As a practical case study, the muon-induced neutron background expected in a 250 kg liquid-xenon WIMP dark matter detector was calculated and good agreement was found for the recoil event rates. The detailed model of neutron elastic scattering in GEANT4 was also shown to influence the nuclear recoil spectrum observed in the target, which is presently a shortcoming of FLUKA. We conclude that both packages are suited for this type of simulation, although further improvements are desirable in both cases.Comment: (23 pages, 14 figures) To appear in Nucl. Instrum. Meth. A v2: Changes to format only; v3: Corrected typo in front matter; v4: Looked up additional experimental data for comparison with simulation

Foreign direct investment flows and fiscal discipline in South Africa

This paper investigates the impact of fiscal policy on foreign direct investment (PDI) in South Africa during the past 30 years. Casual empirical analysis reveals a definite linkage between FDI flows and variables such as the deficit/GDP ratio, representing fiscal discipline, and the tax burden on foreign investors. This relationship is substantiated by econometric analysis. Given the economy's large degree of dependence on foreign capital, the government may contribute to an investor-friendly environment by adjusting fiscal policy. Some inroads have been made in this regard with the government's Medium-term Expenditure Framework (MTEF), which projects a policy of strict fiscal discipline in years to come. However, the tax burden is still relatively high and, due to its impact on foreign direct capital flows, requires urgent attention.Economic

Phosphoproteins and protein-kinase activity in isolated envelopes of pea (Pisum sativum L.) chloroplasts

A protein kinase was found in envelope membranes of purified pea (Pisum sativum L.) chloroplasts. Separation of the two envelope membranes showed that most of the enzyme activity was localized in the outer envelope. The kinase was activated by Mg2+ and inhibited by ADP and pyrophosphate. It showed no response to changes in pH in the physiological range (pH 7-8) or conventional protein substrates. Up to ten phosphorylated proteins could be detected in the envelope-membrane fraction. The molecular weights of these proteins, as determined by polyacrylamide-gel electrophoresis were: two proteins higher than 145 kDa, 97, 86, 62, 55, 46, 34 and 14 kDa. The 86-kDa band being the most pronounced. Experiments with separated inner and outer envelopes showed that most labeled proteins are also localized in the outer-envelope fraction. The results indicate a major function of the outer envelope in the communication between the chloroplast and the parent cell

Update of the management strategy for Oak Ridge National Laboratory Liquid Low-Level Waste

The strategy for management of the Oak Ridge National Laboratory`s (ORNL) radioactively contaminated liquid waste was reviewed in 1991. The latest information available through the end of 1990 on waste characterization, regulations, US Department of Energy (DOE) budget guidance, and research and development programs was evaluated to determine how the strategy should be revised. Few changes are needed to update the strategy to reflect new waste characterization, research, and regulatory information. However, recent budget guidance from DOE indicates that minimum funding will not be sufficient to accomplish original objectives to upgrade the liquid low-level waste (LLLW) system to comply with the Federal Facilities Agreement, provide long-term LLLW treatment capability, and minimize environmental, safety, and health risks. Options are presented that might allow the ORNL LLLW system to continue operations temporarily, but they would significantly reduce its capabilities to handle emergency situations, provide treatment for new waste streams, and accommodate waste from the Environmental Restoration Program and from decontamination and decommissioning of surplus facilities. These options are also likely to increase worker radiation exposure, risk of environmental insult, and generation of solid waste for on-site and off-site disposal/storage beyond existing facility capacities. The strategy will be fully developed after receipt of additional guidance. The proposed budget limitations are too severe to allow ORNL to meet regulatory requirements or continue operations long term

Chromosome painting among Proboscidea, Hyracoidea and Sirenia: support for Paenungulata (Afrotheria, Mammalia) but not Tethytheria

Despite marked improvements in the interpretation of systematic relationships within Eutheria, particular nodes, including Paenungulata (Hyracoidea, Sirenia and Proboscidea), remain ambiguous. The combination of a rapid radiation, a deep divergence and an extensive morphological diversification has resulted in a limited phylogenetic signal confounding resolution within this clade both at the morphological and nucleotide levels. Cross-species chromosome painting was used to delineate regions of homology between Loxodonta africana (2n=56), Procavia capensis (2n=54), Trichechus manatus latirostris (2n=48) and an outgroup taxon, the aardvark (Orycteropus afer, 2n=20). Changes specific to each lineage were identified and although the presence of a minimum of 11 synapomorphies confirmed the monophyly of Paenungulata, no change characterizing intrapaenungulate relationships was evident. The reconstruction of an ancestral paenungulate karyotype and the estimation of rates of chromosomal evolution indicate a reduced rate of genomic repatterning following the paenungulate radiation. In comparison to data available for other mammalian taxa, the paenungulate rate of chromosomal evolution is slow to moderate. As a consequence, the absence of a chromosomal character uniting two paenungulates (at the level of resolution characterized in this study) may be due to a reduced rate of chromosomal change relative to the length of time separating successive divergence events