No description available.

This thesis reports results of a study of relationships between photosynthetic activity and developmental parameters, and cambial activity (wood formation rate), during and following the period of active wood formation in untreated white spruce seedlings, and in seedlings stressed either by extensive stem incisions, or by tilting. The approach involved the use of two non-destructive methods for measuring photosynthetic activity: chlorophyll a fluorescence using optical instrumentation, and CO₂ uptake using infrared gas exchange techniques. Photosynthetic development was examined by estimating chlorophyll a content from a specific fluorescence parameter (O-level), and by the relative occurence of specific chloroplast stroma and membrane (thylakoid) proteins using electrophoretic and immunoblotting techniques. Cambial activity was determined using digitized image analysis of prepared cross-sections of seedling stems. Several fluorescence parameters were strongly correlated to cambial activity in untreated seedlings during the period of active wood formation (in mid-summer). However, the correlations were severely diminished or non-existent when cambial activity was arrested (in late-summer and autumn). Correlations between fluorescence and cambial activity in stressed seedlings were not discernible at any time, suggesting that the induced stresses resulted in a substantial alteration in normal source:sink relationships. Carbon dioxide uptake measures, either uncorrected or corrected to estimated chlorophyll α content, were not measurably correlated to cambial activity in untreated or stressed seedlings at any time in this system. Chlorophyll α content estimated from O-level fluoresecence, was not related to cambial activity in untreated or stressed seedlings. The relative occurences of two enzymes and proteins associated with photosynthetic carbon fixation, i.e. ribulose 1,5-bisphosphate carboxylase (Rubisco) and Coupling Factor, did not appear to be influenced by applied wounding and geotropic stresses. In contrast to the strong correlations found between fluorescence parameters and current season stem vigour, pre-season seedling height and cross-sectional stem areas were not related to stem vigour. These results suggest that in unstressed white spruce seedlings, the measure of specific chlorophyll α fluorescence parameters, using the methods delineated in this study, offers an alternative and more strongly predictive means of assessing current stem vigour, than measures of seedling dimensions. The results of this study provide strong evidence for, and a degree of elucidation on, the anticipated but previously unestablished existence of a source:sink relationship between leaves and vascular cambium in conifer seedlings. This information should provide an initial foundation for the elucidation of non-invasive methodologies by which to assess stem vigour of white spruce seedlings, and to probe source:sink relationships in other conifer species. / Science, Faculty of / Botany, Department of / Graduate

Infants with bronchopulmonary dysplasia (BPD), showed impaired body growth when compared to control infants. In terms of changes in the biochemical composition of the lung, BPD infants had higher DNA, soluble protein, collagen and desmosine contents as well as increased concentrations of DNA, collagen and desmosine in their lungs when compared to the growth patterns obtained for the lungs of control infants. Pathologically BPD was classified into 4 grades. Grade I BPD, was a phase of acute lung injury, grades II and III were proliferative phases. In grade IV BPD, lung structure returned towards normal. Evidence of fibrosis was seen by a significant increase in collagen concentration in grades II and III while desmosine concentration was seen to increase in grades III and IV suggesting that the increase in collagen and desmosine contents in the lungs of BPD infants may be controlled by two different mechanisms. Collagen type I/III ratio was seen to decrease progressively from grade II to grade IV BPD in comparison to age matched controls, indicating a higher proportion of type III collagen in the lungs of infants with BPD. From the clinical analysis and the results obtained from discriminant analysis procedure, it was seen that there was a high degree of correlation between the continuation of the disease and collagen accumulation in the lungs suggesting that pulmonary fibrosis with excessive collagen accumulation is an integral part of BPD. This fibrotic process seemed to correlate significantly with assisted ventilation and high oxygen supplementation received by the infants, but it was difficult to assess the individual contribution of the two treatments in the pathogenesis of BPD. Other variables such as severity of the initial disease and the length of survival of the infants, made the assessment of individual contribution much more difficult. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

The importance of small firms in a country’s development cannot be over-emphasized. In particular, it is important for them to grow in order to sustain their contributions to a country’s economy. Studies have shown how firms achieve growth using the traditional model of decision making (causation) in which planning, market research and forecasting are used to gain relevant information about the firm’s market/industry. This planning enables the firms to compete favourably with other existing firms in the market. Effectuation as an alternative theory involves decision-making processes under conditions of uncertainty where there is no adequate knowledge of the market due to its latent and emerging nature. Effectuation has been used to examine various concepts in entrepreneurship, but there has been no real effort to apply it to the growth of small knowledge-intensive firms (SKIFs). This study, based on in-depth interviews with six SKIFs, highlights how effectuation can be applied to the growth of SKIFs and it examines how the four underlying principles of contingencies, affordable loss, strategic relationships and adaptation contribute to SKIF growth. In addition, elements of causation are also shown to be relevant, leading to the conclusion that the two models can be used jointly to achieve growth of SKIFs.

Variability in the relationship between tree leaf area (TLA) and selected stem measurements was examined in three Douglas-fir stands (Pseudotsuga menziesii (Mirb.) Franco, var. menziesii) that were less than 50 years-old, spaced to approximately 550 to 650 stems/ha, and differed in soil moisture and nutrients. Attention was given to the effect of mean annual ring width (MARW), cross-sectional area of the live bark (ALB - a surrogate measure of relative nutrient storage in the stem), and cross-sectional area of the most recent annual rings equal in number to the number of whorls in the live crown (ALC), on variability in the relationship between TLA and cross-sectional area of sapwood (ASW). At breast height, basal area, ASW, and cross-sectional area of sapwood plus live bark (ASWLB) were not linearly related to TLA, and linear regression equations using log transformed variables varied significantly between sites. Nonlinear regression equation for ASW at breast height was: TLA = 0.064ASẆ¹•³³ (I² = 0.856). Including D (the distance between breast height and the center of the live crown) in the nonlinear equation, did not significantly improve the regression. Tree leaf area prediction models using stem measures from the base of live crown (blc) had higher adjusted R² values than models using stem measures from breast height. At the blc, basal area, ASW, and ASWLB were linearly related to TLA (adjusted R² = 0.926, 0.908, and 0.934, respectively). Multiplying ASW by MARW did not improve the fit of the regression models. Multiplying ASW by ALB improved the linearity of the relationship of ASW at breast height to TLA. The best fitting TLA model overall used the product of ASW at blc and ALB at blc as the independent variable (adjusted R² = 0.967). The results indicate that research into the allometric relationship of TLA to stem measures should give consideration to more than hydraulic measures and include measures of bark function. At breast height and the blc, the independent variable ALC was linearly related to tree leaf area and had higher adjusted R² values than did ASW. In most trees the ALC stem measure was found to include a portion of heartwood area. The strong relationship between TLA and ALC suggests that a given transpiring leaf mass or area is related to a proportional amount of conducting stemwood and physical support stemwood. A quick alternative approach for estimating individual tree leaf area using photographs taken at fixed distance and angle from the target tree did not result in a reliable tree leaf area prediction technique. The difficulty of obtaining views of the tree crown which were not obstructed by adjacent tree crowns was the major obstacle. Using a fixed distance and camera angle was a problem because of variable tree heights. However, altering these fixed positions introduced additional variation into the tree leaf area estimation. Mean specific leaf area (SLA) varied significantly by site, needle age class, and crown position. Mean SLA per needle age class per branch can be predicted with 95% confidence and a 10% allowable error using six 10-needle samples. / Forestry, Faculty of / Graduate

Independent financial advisers have to address different problems as they pro¬gress through the life cycle stages of their businesses. A number of researchers, however, are of the opinion that small business owners do not have the ability to manage the growth-related transitions effectively. It appears that additional guidance is needed to assist independent financial advisers with the survival and growth of their small businesses. Until now, only a small amount of research has been conducted in this area and no formal research study has proposed a marketing mix framework for these advisers, portraying the various factors threatening their survival and growth in their organisational life cycle, as well as the various marketing mix strategies that can be implemented to proactively manage the problems and help generate sales growth. The objective of this study was to propose such a framework to offer additional assistance for business survival and sales growth. This study was exploratory in nature and commenced with a comprehensive lit¬erature investigation to gain the necessary background to support the empirical part of the study. Different opinions and studies were presented and evaluated, which led to the identification of a general business life cycle model as well as a number of problems and marketing mix solutions that could potentially occur in each life cycle stage. These literature findings were then further investigated among independent financial advisers by means of telephone and personal interviews. Following the empirical findings, the recommended framework suggests that independent financial advisers may experience three types of problems in their businesses: critical problems, important problems and problems that only need consideration. Independent financial advisers can use four groups of recom¬mended marketing mix strategies to address these problems. There are also four groups of recommended marketing mix strategies that can assist these advisers to grow their sales (commission). These advisers would, however, need to ensure that they are aware of and understand the various environmental factors that can hinder the successful implementation of the marketing mix strategies. They also need to be able to use the recommended counterstrategies to address the environmental factors. Ultimately, the successful implementation of the recommended marketing mix strategies could then help independent financial advisers to grow their businesses and progress to a more advanced life cycle stage. / Thesis (DCom)--University of Pretoria, 2010. / Marketing Management / DCom / Unrestricted

Burkea africana Hook. (wild syringa) is an average sized leguminous tree, 10-12 m in height occasionally reaching over 20m. This monotypic genus is dominant and codominant in Zambia, and is present throughout Africa as far north as Ethopia and west to Nigeria, and south to South Africa especially Limpopo, North West, Gauteng and Mpumalanga. It inhabits dry, non–calcareous sandy soils in savanna and woodlands up to 1500 m altitude or gentle slope of 1080 m elevation. Burkea africana produces a relatively large number of seeds, which is unusual for a resprouting species. Several studies conducted on B. africana trees paid more attention to the medicinal attributes, however little or nothing is known regarding the factors and dynamics that contribute to the growth and existence of these trees, particularly because these trees grow naturally in nutrient-poor savanna soils. Although B. africana trees have been in existence for a very long period of time, propagating it through thinning and transplanting of seedlings for regeneration and/ or re-establishment of seedlings to survive until sexual maturity still remains a mystery. It is hypothesized that factors controlling establishment and development of B. africana trees are related to microbial activities in the soil, very complex and species specific but poorly understood. This study aimed to identify, if there is a symbiotic relationship between the soil and mycorhizal fungi, and rhizobium bacteria or other growth stimulating activities, in the Burkea soils, which will accelerate and assist effective growth of B. africana trees to reach reproductive stage and produce pods without dying. The chemical composition of Burkea soil and non-Burkea soils was analysed using HCl extraction method.). The results indicated the similar values (p>0.05) were observed for all micro and macro minerals as well as total nitrogen, pH and organic matter. However, total ions nitrate and ammonium concentration levels of Burkea soils were higher (p<0.05) than those found in non-Burkea soils. The use of advanced metabolomics tool using1H-NMR was used to determine and identify soil metabolites which may be responsible for successful growth and establishment of the Burkea africana trees. The findings of this study indicated that metabolomic analysis showed different metabolites in the respective soils. Growth-promoting metabolites (GPM) such as trehalose and betaine were found to be in higher concentrations in the Burkea soils. Conversely, acetate, lactate and formate, were found in higher concentrations in the non-Burkea soils. Furthermore, LC-MS was used to determine the soil components present in Burkea soil as compared to non-Burkea soil using. The results indicated that a total of 22 compounds consisted of essential amino acids such as phenylalamine, threonine, tryptophan, leucine, isoleucine and lysine; conditional essential amino acids such as arginine, cysteine, glycine, glutamine, proline and tyrosine; non-essential amino acids such as citruline, alinine, aspartic acids, asparagine, glutamic acid and serine; nucleobased amino acids such as guanosine, adenine, adenosine, cytindine; dicarboxylic acid such as fumaric acid as well as common non-proteinogenic amino acids such as 4-hydroxyproline compounds were found in both Burkea and nonBurkea soils. The study investigated the microbial communities in the soil where Burkea africana trees grows successfully (Burkea soils) and how it varies from the soils where they do not grow (non-Burkea soils). DNA was extracted from the soil and a high throughput sequence bask local assignment search tool (BLAST) was used to analyze the microbial diversity (bacterial and fungal) and composition found in both soils, for a comprehensive understanding of the soil microflora. The results revealed that Penicillum sp is prevalent in Burkea soils and was the main discriminant between the two soils. On the contrary, non-cultured fungi, which could not be identified, dominated the non-Burkea soils. The variances in soil composition suggests that species supremacy play a role in the growth of B. africana trees. Lastly, the current study investigated and also identified what attracts caterpillars known as Cirina forda to invade and feed on B. africana trees. In addition, to determining if there is a symbiotic relationship between the plant-growth metabolites; growth-promoting fungi (Penicilium sp) and the caterpillars. The results of the study, revealed that the fungus Pleurostomophora richardsiae was predominant in the leaves of B. africana trees as well as in the caterpillars. It is proposed that Pl. richardsiae is a volatile compound which attracts caterpillars and makes B. africana trees susceptible to caterpillars’ outbreaks. The second largest percentage of fungi found in the caterpillars was Aspergillus nomius. / School of Agriculture and Life Sciences / Ph. D. (Agriculture)

Background: Extrauterine growth restriction (EUGR) is multifactorial in etiology and predisposes infants to multiple morbidities that can be significantly ameliorated by adequate nutrition and appropriate longitudinal growth. Current strategies to reduce the risk of EUGR include optimization of parental nutrition, varying schedules of feeding advances, and caloric supplementation. Very low birthweight (VLBW) preterm infants are particularly affected by EUGR, therefore ensuring adequate postnatal growth is an essential component in improving the long-term health outcomes for VLBW infants. The objectives of this observational study were to examine potential risk factors for growth failure among premature infants that did not respond to caloric and volume supplementation. Methods: We conducted a retrospective chart review of all infants born at the University of Massachusetts level III NICU from January 2016 to June 2020. Growth was tracked using PediTools electronic gestational age and growth calculators. (17) We reviewed the EMRs of infants who met the criteria for EUGR at the time of hospital discharge for a variety of potential factors affecting growth. Results: Overall, a total of 448 infants were screened with a final study cohort of 358 infants, of which 13% were discharge with EUGR. Analysis of demographic and clinical characteristics of infants with EUGR before and after nutritional intervention showed no statistically significant differences between the two cohorts. Pre-protocol, only weight percentiles and z-scores were statistically significant. Post-protocol, the change in z-score was also statistically significant. The only factor found to be statistically significantly different between was Necrotizing enterocolitis (NEC). Timing of EUGR in the pre-protocol groups occurred between 33-35 weeks, while in the post-protocol group EUGR occurred between 32 and 37 weeks (Figure 2). Conclusions: Our findings confirmed the presence of several factors that have been previously shown to increase risk for EUGR, including male sex, lower gestational age, lower birth weight, and the occurrence of NEC. It also identified an additional risk factor, that of being born “constitutionally small”. In the post-protocol cohort, the change in z-score was statistically significant in addition to birth weight percentile and z-score and discharge weight percentile in z-score. The window in which EUGR occurred as well as the interquartile range was significantly widened post-protocol. These data suggest that the volume supplementation protocol successfully addressed the causes of EUGR in some infants, but other mechanisms may have occurred in infants who were still discharged with EUGR post-protocol.

No description available.

No description available.