This thesis concerns the effect of rounding on statistical procedures, where rounding is taken to be the grouping of data at the midpoints of equally spaced intervals. The characteristic function of the rounded distribution is obtained. This is used to derive general expressions for the moments of univariate and bivariate distributions that have been subject to rounding. The interactive effect of rounding and skewness on the moments is examined. The performance of certain normal test statistics is examined for rounded data. A study is carried out to obtain precise values for the significance level and power of these statistical tests for rounded data, over many distributions. Guidance is given on what is an appropriate degree of precision for normal data. Special consideration is given to how much non-normality can be allowed without the effect of rounding seriously distorting the significance level and power of a test. Standard methods of estimating the parameters of a distribution are compared with respect to loss in information caused by rounding. Normal, gamma and exponential distributions are examined. Computational methods are presented for computing the maximum likelihood estimates from rounded normal and gamma data. In general it is concluded that the effect of rounding on statistical procedures can be increased by the departure from normality of the population. It was found that less precision is required of the recorded data than that which is usually given.

No description available.

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In the present study, two strains of Ectocarpus siliculosus with different pollution histories, LIA4 and Es524, were exposed to three PSII inhibitor herbicides, diuron (DIU), terbuthylazine (TBA) and isoproturon (IPU). Evaluation of their effects on growth and photosynthetic efficiency (Fv/Fm, ΦPSII, qP) have demonstrated negative impacts of all herbicides on both strains. With reference to the 7 d RGR EC50 values; DIU (9.9 - 25 μg L-1); TBA (18 – 28 μg L-1); IPU (257 – 315 μg L-1), the reported environmental concentrations for DIU were higher than the values that exert negative effects to E. siliculosus. However, as for TBA and IPU, the environmental concentrations were below the values which caused detrimental effects to E. siliculosus. Strain Es524, which originated from a Cu-polluted site in Chile, was found to exhibit greater resistance to the herbicides, with higher EC50 values recorded, compared to LIA4. To further elucidate the factors contributing to the relative tolerances of the two strains, responses associated with reactive oxygen species (ROS) were investigated. Measurements of H2O2 concentrations and lipid peroxidation showed significant differences between the strains, with increases in both parameters recorded at lower concentrations in LIA4 than Es524. Activities of antioxidant enzymes (CAT, APX and GR) were significantly (P < 0.05) greater in Es524 than LIA4, and total phenolic content and DPPH scavenging activity were also greater in the more tolerant strain. The rank order of toxicity of the three herbicides was diuron > terbuthylazine > isoproturon in both strains of E. siliculosus. In addition to exposure to individual herbicides, the interactions between binary mixtures were also investigated in both strains using physiological and biochemical biomarkers. All three ways of action (synergistic,additive and antagonistic) were exhibited through different endpoints applied in the present study. Significant differences (P < 0.05) between LIA4 and Es524 were observed for the DIU+TBA and TBA+IPU mixtures, while higher impacts were recorded in LIA4 strain compared to Es524. Further studies showed synergistic interactions were observed in Es524 for the aforementioned mixtures (DIU+TBA, TBA+IPU) on the antioxidative enzyme activities while in LIA4 different interactions were exhibited, which probably contribute to the higher tolerance of Es524 to the mixtures. The presence of TBA together with the phenylureas DIU/IPU was also observed to increase the stimulation of antioxidative enzymes (CAT, APX, GR) in both strains of E. siliculosus. This investigation provides new information on the abiotic stress metabolism in brown algae, and HPLC analysis demonstrates the important role of polyphenols in overcoming the impact of oxidative stress. In conclusion, exposure to the herbicides, singly and in mixtures, caused significant (P < 0.05) changes in the growth, photosynthetic efficiency, and ROM of both strains of E. siliculosus. Strain Es524 was found to be more tolerant than LIA4.

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The technique of electron spin resonance spectroscopy was employed primarily to study the effects of ionizing radiation, in the form of x-rays (50Co source), on various organosulphur compounds, selected polyamino acids and proteins, and DNA. The work was carried out exclusively at low temperature ( 240K), powder, frozen aqueous or CD3OD/D2O deoxy glass systems being studied. The underlying principle of the work presented here was "radioprotection". To this end, several known thiol radioprotectors have been studied, along with thiol compounds where previous research has not been so extensive. The aim of this was to try to resolve a long-standing controversy in the literature which has both chemical and biochemical implications. The problem is the fate of radicals generated in the thiol "radioprotector" after it has completed its act of repair in a biochemical system. This is studied, evaluated and discussed in Chapters 2-6 and has direct bearing on the work presented in Chapter 8. The reverse of this radioprotection is discussed in Chapters 7 and 8 that is radiation damage to bio-macromolecules. Chapter 7 is concerned primarily with damage occurring via an electron-loss centre in polyamlno acids and proteins whereas Chapter 8 involves damage to the cells primary target - the DNA molecule itself.

1. The physiology of mammalian respiration and the pharmacology of the potent, synthetic opioids, the fentanyls, are reviewed. The current knowledge of the opioid receptor sub-type involvements in opioid-induced respiratory depression is summarised, together with the experimental methods which have previously been employed in studies of receptor involvement. 2. The comparative binding characteristics of the mu opioid receptor selective ligand [3H]-[D-Ala2-MePhe4-Glyol5] enkephalin ([3H]- DAGO) and the delta receptor ligand [3H]-[D-Pen2,D-Pen5] enkephalin ([3H]-DPDPE) were studied in homogenates of both whole brain and of pons/medulla regions from the rat. The receptor affinities and site-selectivities of five drugs of the fentanyl series (alfentanil, carfentanil, fentanyl, lofentanil and sufentanil) were determined by inhibition studies, using [3H]-DAGO and [3H]-DPDPE as markers of the mu and delta opioid binding sites, respectively. The concentration of delta opioid sites in pons/medulla was found to be approximately one third that of mu sites. The concentrations of both mu and delta sites in whole brain were similar to that of ? sites in pons/medulla. The rank order of affinities of the unlabelled drugs was dissimilar at the mu and delta sites. The most potent fentanyl derivatives exhibited negligible preference for the mu or delta sites, in contrast to the least potent compound, alfentanil, which showed an extremely high mu-site selectivity. 3. The respiratory depressant properties of the fentanyls were investigated in urethane-anaesthetised rats. Ventilatory parameters were measured using a volumetric pressure transducer connected via a Fleisch tube to a tracheal cannula. Intravenous administration of the fentanyls produced an apnea of immediate onset and dose-related duration, in addition to depressing both tidal volume and respiratory frequency, and thus minute volume, in a dose-related manner. The potency ratios of the fentanyls to produce apnea and to depress minute volume were dissimilar. Studies of the effects of alfentanil on arterial blood gases confirmed the reduction in minute volume to be a respiratory depression. 4. A method was developed for the quantification of antagonism of the respiratory effects of opioids by means of infusion of the opioid antagonist, naloxone, to predicted steady-state blood concentrations, which provided accurate measures of pA2. The basis of the technique rests upon determination of the plasma clearance of the antagonist whence appropriate loading doses and zero order infusion rate constants were calculated. The predicted concentrations of naloxone were verified by direct serum measurements using HPLC. 5. Naloxone pA2 values for antagonism of the apnea produced by the fentanyls were identical and indicated sole mediation by the mu opioid receptor, which was confirmed by intravenous administration of receptor-selective opioids. Apnea was produced by DAGO but not by DPDPE or U69,593. This component of the response was shown to be peripherally-mediated and vagally dependent, being abolished by bilateral vagotomy and the quaternary opioid antagonist, N-methyl levallorphan. 6. Naloxone pA2 values for antagonism of the minute volume depressant effects of the fentanyls showed significant differences through the series, implying both a mu and non-mu receptor involvement in this centrally-mediated response, which could still be elicited after vagotomy. A k receptor contribution to respiratory depression was eliminated by investigation of the respiratory effects of U69,593 and U50,488H. The involvement of the delta receptor was suggested by the finding that intracerebroventricular administration of DPDPE produced respiratory depression which was blocked by high doses of naloxone. 7. A study of the cardiovascular effects of the fentanyls confirmed that the different naloxone pA2 values for depression of respiration could not be attributed to this influence. 8. In conclusion, the binding site selectivities of the drugs of the fentanyl series varied inversely with their affinities at the mu and delta sites. In vivo studies have demonstrated that mu receptors alone in the periphery mediate the apneic responses to intravenously administered opioids. Whilst mu receptors in the brain are the most important in the mediation of the minute volume depressant effects of the fentanyls another receptor, possibly delta, contributes to this response. This non-mu contribution is different for each of the fentanyl drugs, broadly in accord with their binding site selectivity exhibited in vitro.

The purpose of this study was to investigate the effects of training and substrate manipulation upon the physiological and metabolic response to graded exercise for both trained and non-trained subjects. A major interest of this work was the concept of an "anaerobic" threshold for exercise of increasing intensity, and the relevance of the anaerobic threshold to endurance performance. Procedures were designed and validated to measure the physiological responses to maximal and submaximal work in an attempt to link physiological measures of performance to running performance for middle distance events. The potential of these measures to detect changes in running performance was investigated using cross-sectional studies of trained athletes and longitudinal studies of the effects of training. Biochemical analyses required the development of high performance liquid chromatographic procedures for the assay of hormones in blood and urine", and gas liquid chromatographic procedures for the assay of plasma fats. Performance times for middle distance running events were found to be highly correlated to selected physiological measures. The sensitivity of these measures were such that they were capable of detecting small differences in running performance between athletes of similar ability. In this respect?, the anaerobic threshold was found to be the most sensitive measure of performance. Changes in the anaerobic threshold were observed for both training and substrate manipulation. The corresponding changes in the metabolic responses to graded exercise suggest that the change in the anaerobic threshold is closely linked to overall metabolic adaptation to training. The data support the role of the anaerobic threshold as a sensitive indicator of the metabolic and cardiovascular adaptation to exercise and training.

Magister Psychologiae - MPsych / We live in a society that continually reinforces the connection between femininity and maternity and for the majority of women, attempts to experience motherhood are successful. However, for others the world of motherhood is not so easy to enter. To date, research regarding the needs and life satisfaction of women who are unsuccessful in becoming mothers, is fairly limited. The purpose of this study was to explore the transitional phase women endure from potential motherhood to non-motherhood and to highlight some of the complexities underpinning infertility and its impact on the lives of women in South Africa. The main objective was to gain deeper insight into how women incorporated this experience into their lives and relationships and how they began to create a future life without their own biological children. A secondary aim of this study was to investigate whether the women viewed aspects such as age and finances as having had an effect on their decision to discontinue treatment for infertility. Feminist standpoint theory served as a theoretical framework for the study that recognized that each individual voice be heard. This study was a qualitative exploration, utilizing a short demographic questionnaire and an in-depth semi-structured interview. Five interviews were conducted with women from diverse backgrounds. These interviews were recorded; transcribed verbatim and thematic analysis of the data was conducted. / South Africa

Six experiments investigating the relationship of familiarity and context to the processing of metaphor are presented. Experiment 1 compares time to understand sets containing idiom or metaphor targets following 1-2 sentence contexts in four conditions: NONLITERAL, where the context was completed by an idiom or metaphor, PARAPHRASE, where the same context was completed by a literal target with the same meaning, SURPRISE, where the context was completed by a less-anticipated literal target, and LITERAL, where the target from the NONLITERAL condition was used in its literal sense in a different context. In Experiment 2, sets of dead metaphors replaced the idiom sets, and the metaphor sets had novel metaphors. Experiment 3 matched the targets in each condition for overall printed word frequency, to investigate whether word familiarity was interacting with type of usage. It also included an UNFAMILIAR condition, where the same context was completed by a much less familiar word used literally. Experiment 4 took 20 contexts from Experiment 3 and asked subjects to generate their own endings. Experiment 5 replicated Experiment 3 but with a two-target semantic choice instead of a single response. Experiment 6 shortened contexts and reduced their information content. Its purpose was to see how much context was contributing to understanding, and whether some conditions would be more affected than others. The results may be interpreted as indicating that familiarity with the use of a word is important in determining speed of understanding. Dead metaphors could be understood just as quickly as words used literally, but novel metaphors took longer. Contextual expectations are also a powerful adjunct to the understanding process. When expectations are thwarted, errors and understanding time increases. Metaphor understanding is interpreted as a class-inclusion process in the manner described by Glucksberg and Keysar (1990), where a word used metaphorically is viewed as a prototypical exemplar of a hierarchically superordinate class that becomes extended to incorporate the context topic. This process takes time, but metaphors have a response latency advantage over surprising or unfamiliar literal words encountered in context. When context is reduced, metaphors are still advantageous in terms of time, but are less useful to depth of understanding. / Arts, Faculty of / Psychology, Department of / Graduate