The ethnobotany and pharmacognosy of Olea europaea subsp. africana (Oleaceae)

AbstractThe ethnobotanical uses of wild olive, O. europaea subsp. africana (sometimes referred to as subsp. cuspidata) in southern Africa and in other parts of Africa are reviewed. Chromatographic analyses of secoiridoids (oleuropein and other oleuropeosides) in 25 wild olive leaf samples from 10 localities in South Africa showed substantial amounts of oleuropein (up to 110mg/g dry weight) and not trace amounts as reported in the literature. Oleuropein is the main active compound in olive leaf, with demonstrated anti-oxidant, anti-microbial, hypolipidemic and hypotensive activities. A comparison with nine cultivated olive leaf samples (subsp. europaea) from six cultivars and two localities showed that commercial olive leaf can be distinguished by the presence of verbascoside, which is absent in wild olive. Extraction methods and solvent systems (TLC and HPLC) were compared, using pure oleuropein (isolated from wild olive leaf and identified by NMR) as an authentic reference sample. The unique peltate scales on the leaves are useful to identify olive leaf raw material (but are the same in both subspecies). The main conclusion is that wild olive leaf is chemically closely similar to cultivated olive leaf and therefore suitable as an alternative source of raw material for olive leaf extract

Anterior Hippocampus and Goal-Directed Spatial Decision Making

Contains fulltext : 115487.pdf (publisher's version ) (Open Access

A Uniform Lower Error Bound for Half-Space Learning

We give a lower bound for the error of any unitarily invariant algorithm learning half-spaces against the uniform or related distributions on the unit sphere. The bound is uniform in the choice of the target half-space and has an exponentially decaying deviation probability in the sample. The technique of proof is related to a proof of the Johnson Lindenstrauss Lemma. We argue that, unlike previous lower bounds, our result is well suited to evaluate the benefits of multi-task or transfer learning, or other cases where an expense in the acquisition of domain knowledge has to be justified

Linear stability analysis of transverse dunes

Sand-moving winds blowing from a constant direction in an area of high sand availability form transverse dunes, which have a fixed profile in the direction orthogonal to the wind. Here we show, by means of a linear stability analysis, that transverse dunes are intrinsically unstable. Any along-axis perturbation on a transverse dune amplify in the course of dune migration due to the combined effect of two main factors, namely: the lateral transport through avalanches along the dune's slip-face, and the scaling of dune migration velocity with the inverse of the dune height. Our calculations provide a quantitative explanation for recent observations from experiments and numerical simulations, which showed that transverse dunes moving on the bedrock cannot exist in a stable form and decay into a chain of crescent-shaped barchans.Comment: 8 pages, 4 figure