No description available.

No description available.

No description available.

No description available.

A concern with organic farming is for the depletion of soil phosphorus. The objectives of this study were to determine which organic management systems deplete soil phosphorus and whether arbuscular mycorrhizal fungi (AMF) could assist crops in taking up phosphorus in these systems. The research site was a 14 year-old study at Glenlea, Manitoba, having 3 different 4-year rotations under organic and conventional management: forage-grain ± manure-compost, grain-only, and a restored tall grass prairie. The modified Hedley procedure revealed organic systems to have lower concentrations of labile phosphorus than conventional but recalcitrant fractions did not differ (P < 0.05). Nitrogen was limiting in the organic grain-only rotation; phosphorus in the organic forage-grain. Mycorrhizal colonization as arbuscules was higher in organic than conventional systems (P < 0.05). To prevent phosphorus limitation, we suggest high-export organic rotations be balanced with sufficient rates of manure-compost and AMF maintained to help with phosphorus absorption.

No description available.

It is common practice to remove impacted mandibular third molars due to pathology associated with these impactions. Alternatively, impactions can be treated conservatively through a closely guarded follow-up regiment. However, many symptoms associated with impacted third molars may be prevented by elective removal of potentially problematic teeth. To determine the risk of developing pathology associated with impacted mandibular third molars, a ransom sample of 200 pantomographs were analyzed displaying 324 impactions from patients who presented for treatment at the Maxillo-Facial and Oral Surgery Department, Faculty of Dentistry, University of the Western Cape.

Thesis (MAppSc(Chem))--University of South Australia, 2000

Thesis (PhD)--University of South Australia, 1997

Geochemical exploration for mineral deposits has generally been restricted to regions dominated by residual regolith or where transported regolith cover is thin. A variety of partial geochemical extraction techniques, linked to new predictive models for element migration through transported regolith cover, have demonstrated a potential to detect deeply buried mineralisation under certain circumstances. Problems with the reliability and further development of such partial extractions are linked to the lack of information on either the form of metals or the factors that control the extraction of metals from regolith materials. This study quantitatively examines the mechanisms of a range of partial extraction methods, based on a suite of surface regolith samples from the Mandamah Cu-Au deposit that is covered by 50m of transported regolith. Samples at were subjected to acetate, hydroxylamine.HCI and Na-pyrophosphate extractions at various reagent concentrations, pH values, temperatures and durations, following various sample preparation and chemical pretreatment permutations. The data were modelled, and reaction conditions subsequently optimized, on the basis of central composite designs. Conventional partial extraction (acetate, hydroxylamine and aqua regia) data, displayed high variability for some major and trace metals surrounding the periphery of mineralisation at Mandamah but little indication of direct vertical migration of ore-related metals. The buffered acetate extraction is primarily controlled by the capacity of the solution to generate acid rather than exchange induced by the cation ofthe acetate salt. Trace metals were highly susceptible to readsorption effects. Acidic hydroxylamine extraction is driven by kinetically limited acid hydrolysis and the hydroxylamine concentration has little effect on metal extractability. Alkaline Na-pyrophosphate extraction proved difficult to model. Two new partial extractions developed in this study - alkaline hydroxylamine.HCI and pH-static calcium nitrate - offer a different functionality to conventional extractions and provide more coherent geochemical patterns at Mandamah related to the location of buried mineralisation. These patterns are also related to the capacity of samples to resist pH neutralization. Systematic optimisation of geochemical extraction procedures is demonstrated to be an effective approach to improving detection of geochemical patterns in surface regolith that can be spatially related to the effects of mineralisation on the chemistry and mineralogy of overlying transported regolith cover.