Darmstadt, Techn. Universiẗat, Diss., 2001. / Dateiformat: tar.gz, Dateien im PDF-Format.

Darmstadt, Techn. Universiẗat, Diss., 2002. / Dateiformat: tar.gz, Dateien im PDF-Format.

München, Techn. Universiẗat, Diss., 2001.

Texte remanié de--Droit--Cambridge--Corpus Christi college, 1991. / Bibliogr. p. 290-307. Index.

The yeast, <i>Saccharomyces cerevisiae</i> requires certain elements for the growth and development of healthy cultures. The divalent cation, zinc is of paramount importance to this yeast, as zinc is a structurally and functionally essential metal that cannot be replaced by any other element. Zinc accumulation by <i>S. cerevisiae </i>is a biphasic response, consisting of a rapid metabolism independent and a metabolism dependent phase. Metabolism-independent metal ion accumulation is a physical process, whereby the ions are associated with the cell wall. This stage of uptake is often referred to as biosorption and zinc uptake is influenced by temperature, pH, biomass concentration and the presence of competing ions. The second phase of zinc uptake (metabolism-dependent metal ion accumulation) concerns the intracellular accumulation of the ions. This biological accumulation, often abbreviated to bioaccumulation, is slower than biosorption as the zinc ions are transported into the cell, via the plasma membrane by the energy consuming process, active transport. The presence and type of metabolisable energy source, metabolic inhibitors, as well as the factors that affect biosorption also affect bioaccumulation. The genetics governing zinc accumulation by <i>S. cerevisiae</i> has recently been unravelled (Zhao and Eide, 1996a & b). Research has shown that a high (ZRT1) and a low (ZRT2) affinity transporter proteins exists, which act in zinc limiting and zinc replete conditions, respectively. Once the transporters aid zinc uptake into the cell, this important divalent cation is either utilised immediately or compartmentalised in the vacuole until required. Zinc accumulation is influenced by yeast cell physiology. Upon examination of zinc uptake with respect to cell growth, in various metabolisable energy sources, the results demonstrate that zinc is influential in the growth of industrial relevant strains of <i>S. cerevisiae</i>, and that zinc accumulation is affected by the presence and type of metabolisable energy source e.g. glucose, fructose, maltose and sucrose. Optimal growth was achieved when the lager yeast and wine yeast was grown in a minimal media containing sucrose as the metabolisable energy source after a 24 hour period with distillers yeast and bakers yeast growth was maximum when grown for 24 hours in a fructose supplemented media. The industrial strains of yeast studied appeared to sequester maximum zinc when the YPDM was supplemented with monosaccharides, as opposed to disaccharide, after a 24 hour examination period. The accumulation of zinc by <i>S. cerevisiae</i> lager yeast is a cyclical event with uptake occurring during lag and early exponential phase of growth, with zinc appearing to convey a protective effect on cells which have been subjected to a chemical (15% ethanol) and a physical (heat shock- 45°C) stress. The influence of zinc accumulation on yeast cell physiology was studied with respect to specific enzyme (Alcohol Dehydrogenase) and metabolite (ethanol) production. The results demonstrate a general trend, with more ADH produced when the cells have sequestered more zinc, this in turn had a positive effect on the overall ethanol production of a strain of lager yeast.

The study sought to analyse the South African common law defence of moderate and reasonable child chastisement. Regarded by those with religious and cultural beliefs as a way of instilling child discipline, child chastisement has been a centre of contestation in recent years. Constitutionally, children have rights to care, dignity and protection. Thus, child chastisement infringes upon these rights. However, regardless of its intentions, child chastisement has an effect of inflicting pain onto its victims thereby infringing on their rights to human dignity, equality and protection. It can also lead to unintended consequences such as injury or death to its victims. Subjecting children to this cruel, inhuman and degrading action affects the development of children and sometimes haunts them at a later stage in life. In addition, child chastisement lacks the measure of determining whether it is moderate or severe, thereby making it prone to abuse or misuse. The study used a qualitative research paradigm, where data was collected from existing documents and analysed towards understanding child chastisement and finding sustainable ways of improving child welfare in the home or in society. The study also analysed the legal framework on child welfare and chastisement globally, regionally and locally. Instruments such as the UNCRC, ACRWC and the UDHR have a clear stance abolishing child chastisement. The study established that, despite the existence of global instruments promoting child care and protection, the common law defence of corporal punishment in the home and society remains a loophole that needs closing and enactment of laws that outlaws it completely.

xii, 108 leaves : maps ; 28 cm Notes Typescript Thesis (M.S.)--University of Oregon, 1983 Includes vita and abstract Bibliography: leaves 104-108 Another copy on microfilm is located in Archives

The overall objective of these experiments was to augment our understanding of how naphthenic acids stimulate metabolism and growth of bean plants. Three separate studies were carried out with bush bean plants (Phaseolus vulgaris L. cultivar Top Crop) to determine: 1) the effect of potassium naphthenates (KNap) on the uptake, distribution, and incorporation of phosphorus-32, 2) the metabolism of the individual naphthenic acid, potassium cyclohexanecarboxylate (KCHC), in leaves and roots, and 3) the effect of KNap and KCHC on the uptake and metabolism of glucose by excised root tips. 1) Fourteen-day-old plants growing in a phosphate-free (-P) or a complete (+P) nutrient solution were sprayed to drip with a 0.5% solution of KNap. Twenty-four hours after spraying, the roots of both control and treated plants were exposed for 2 hours to a nutrient solution containing ³²P. Following the exposure to ³²P, the plants were returned to their original nutrient solutions. Control and treated plants were withdrawn 4, 8, 12, and 24 hours after exposure to ³²P, and were separated into leaf blades, stems, and roots. Acid soluble, acid insoluble, and total ³²P activity, or total phosphorus were determined at each sampling time. KNap treatment increased by 7 to 9% the intake of ³²P by plants grown in the -P or +P nutrient solution. The increases, however, lacked statistical significance at the 0.05 level. The rate at which ³²P was translocated out of the roots of plants grown in the -P nutrient only was increased significantly by treatment, in spite of the fact that at the 24 hour sampling time 84% of the total ³²P label remained in root tissues. At the same sampling time 32% of the total ³²P label was found in the roots of plants grown in the +P nutrient. While KNap treatment significantly increased ³²P activity in stems of -P grown plants over the sampling period, activity in stems of control and treated plants grown in the +P nutrient was similar. Naphthenate treatment increased the rate of incorporation of ³²P into both the acid soluble (sugar phosphates, nucleotides, phospholipids) and acid insoluble (nucleic acids, phosphoproteins) fractions of leaves of plants grown in the +P nutrient solution. Acid soluble ³²P activity declined in all root tissues over the sampling period as acid soluble ³²P-containing compounds, primarily orthophosphate, were translocated acropetally. The percentage acid insoluble ³²P activity in the roots of KNap-treated plants was significantly greater than that found in the roots of control plants at the 24 hour sampling time. Naphthenate treatment did not affect the amount of total P (³¹P + ³²P) in the two P fractions of the three plant organs. The augmented incorporation of ³²P into the acid soluble and acid insoluble fractions is further evidence of the KNap-stimulated P metabolism reported by other workers. 2) KCHC-7-¹⁴C administered to leaf disks in the light or to roots of intact seedlings in the dark was rapidly converted to a mixture of two conjugated metabolites: the glucose ester and the aspartic acid amide. The root-feeding experiment indicated that following their synthesis in root tissues both conjugates were translocated acropetally. The results of amino acid analyses of the acid hydrolysates of several unidentified metabolites strongly suggest that KCHC-7-¹⁴C was also conjugated with a low molecular weight polypeptide. 3) Three sets of root tips cut from 7-day-old seedlings were incubated in a medium containing ¹⁴C glucose for 3 hours. Two of the three sets were pretreated in a solution of KCHC or KNap for 6 hours. Each naphthenate treatment significantly increased ¹⁴C activity in the ethanol-soluble (amino acids, glucose, etc.), ethanol-insoluble (polysaccharides, protein, etc.), and respired CO₂ fractions. The individual naphthenic acid, KCHC, had the greater effect on the uptake and metabolism of labelled glucose. Results also indicated that not only were the uptake of glucose and CO₂ production increased significantly by each treatment, but also amino acids containing the glucose carbon passed more quickly through soluble amino acid pools in root tissues, and were more rapidly fixed into protein. In light of the finding that naphthenate conjugates and not the free acid were detected in the tissue, it may be that the conjugates were associated in a causal way with the stimulated uptake and metabolism of labelled glucose. / Science, Faculty of / Botany, Department of / Graduate

Includes bibliography. / A study of the ecology of the Southern African Kestrel was made in two areas of differing topography in the Eastern Cape Province (32 °S) of South Africa. The main objectives of the study were to describe foraging parameters (behaviour-time budgets, hunting success and diet) and breeding parameters (clutch size, hatching and fledging success, nestling, fledging and post-fledging periods) of the Southern African Kestrel. These parameters were compared to those from studies made on the European Kestrel (Falco tinnunculus tinnunculus) in western Europe (53 °N) in an environment which fluctuates relatively more than the South African study sites. Predictions concerning foraging and breeding ecology made by life-history theory in stable and fluctuating environments prompted the erection of the following hypotheses which were examined in this study. 1. Common Kestrels (Falco tinnunculus) in relatively stable environments have a more consistent but lower foraging yield than those breeding in fluctuating environments. 2. Common Kestrels in relatively stable environments have lower reproductive rates (longer incubation, nestling and post-fledgling dependence periods, later age at first breeding and longer life-span) than those in fluctuating environments. Southern African Kestrels spent different proportions of time of the two main hunting methods used, perch- and hover-hunting, than the European Kestrel. Perch-hunting was the predominant hunting method used by the Southern African Kestrel compared to hover-hunting in the European Kestrel. Southern African Kestrels had a higher prey-capture success for both hunting techniques. However, daily food intake was lower in Southern African Kestrels because a high proportion of the diet consisted of small invertebrates. Average clutch size was smaller in the Southern African Kestrel than that of the European Kestrel and Southern African Kestrels fledged on average fewer young. However, incubation, nestling and post-fledging periods were within the range recorded for the European Kestrel. The hypothesis that Common Kestrels in relatively stable environments have lower foraging yields is supported by this study. Although results from this study suggest that food yields are more consistent in stable environments, it was unable to evaluate this adequately. The hypothesis that reproductive rates are lower in relatively stable environments is partly supported in this study, but more data are required for parameters such as incubation and nestling periods to confirm such trends.

Due to increased adoption of irrigation and advancements in technology, producers in the Mississippi Delta have been unsustainably depleting the water stocks in the Mississippi River Valley Alluvial Aquifer (MRVAA). This research investigates the impacts of various regulatory threats uniformly applied to heterogeneously located producers to avert further overexploitation of the MRVAA. If a regulatory threat successfully incentivizes reduction of producers’ extraction rates, costly implementation of a binding limited-use regulation could be avoided. Laboratory experiments incorporating the major characteristics of the MRVAA were conducted to test two threatened uniform policies, limited-use and moratorium. The main finding of the research is that even with the threat of a moratorium, the regulatory trigger point was too lax to result in significantly slowing over exploitation of the water resource.