Criteria for interpretation of scales of steelhead (Salmo gairdneri gairdneri) and for their use in back calculation of early life history were established. With these criteria, features of the life history of 784 steelhead from the anglers' catches of the Chilliwack River, B. C. were studied. Age composition of adult steelhead runs from 1948 to 1953 was uniform except for the suggestion of a slightly dominant year class, represented as 4 year old fish in 1950, 5 year old fish in 1951 and 6 year old fish in 1952. There was no suggestion that fish of any particular age, life history, sex or length tend to return as adults at any particular season of the year. The age and size of smolts at migration is variable, with the majority however in the 2 and 3 year age groups and ranging in size from 15 to 20 cms. Smolt migration usually occurs in March, with a small proportion of late migrants in August. Spawning frequency of adults was reviewed. Females generally spawn at an earlier age and more frequently than males. It is concluded that the variability in the life history of the steelhead acts as a safeguard in its conservation. / Science, Faculty of / Zoology, Department of / Graduate

D.Litt. et Phil. / The psychometric properties of the Comrey Personality Scales (CPS) for Afrikaans speaking university students were examined. The CPS and the 16 Personality Factor Questionnaire (16PF) were completed by 804 first year university students in Afrikaans. The CPS was translated into Afrikaans by the translation-back translation method. Scores for the 40 subscales of the CPS were subjected to an exploratory factor analysis. Nine factors were extracted and orthogonally rotated with the Tandem Criteria. Subsequently, the factors were compared with the eight factors obtained in the original normative study by means of coefficients of congruence. Six of the factors, namely Trust versus Defensiveness, Orderliness versus Lack of Compulsion, Emotional Stability versus Neuroticism, Extroversion versus introversion, Mental Toughness versus Emotional Sensitivity, and Empathy versus Egocentrism, showed congruence coefficients of 0,90 or higher. The Social Conformity versus Rebelliousness factor was clearly recognisable in the Afrikaans speaking sample, but the congruence coefficient was only 0,81. The Activity versus Lack of Energy factor split in two and one of these factors was very similar to the normative Activity factor, with a congruence coefficient of 0,89. The CPS subscales were also subjected to a multiple group confirmatory factor analysis wherein the measurement invariance of the CPS for Afrikaans speaking students and the normative American group was assessed. The results confirmed that the CPS measures the same constructs in the two groups, but the variance of the Afrikaans group for the Social Conformity versus Rebelliousness factor was much smaller than that of the American group. The measurement invariance of the CPS for Afrikaans speaking males and females was also assessed. The multiple groups confirmatory factor analysis supported the measurement invariance of the CPS for males and females. Subsequently, the mean scores of American male students and the Afrikaans speaking male students for the CPS were compared. The Afrikaans speaking students obtained higher scores for Social Conformity versus Rebelliousness and lower scores for Trust versus Defensiveness than their American counterparts. Similar results were obtained for the Afrikaans speaking and American females. The mean scores of the Afrikaans speaking males and females were also compared. The comparison of the males and females revealed that the males had higher Mental Toughness versus Emotional Sensitivity scores. The females had higher scores for Empathy versus Egocentrism, Trust versus Defensiveness, Orderliness versus Lack of Compulsion, and Social Conformity versus Rebelliousness. In the last place the CPS and the 16PF scales were subjected to an interbattery factor analysis. Six factors were extracted and orthogonally rotated. The rotated factors supported the construct validity of the CPS and 16PF scales and also provided support for four of the so-called Big Five factors of personality.

Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Specialized skin scales (generation glands) and undifferentiated skin scales were compared in three species of cordylid lizard, viz. Cordy/us cordy/us, Pseudocordy/us micro/epidotus and P. capensis. These skin derivatives were histologically examined and compared, using data existing in literature (Maderson, 1966; 1967; 1968a) with similar structures in gekkonids. Histological descriptions of cordylid skin structure were the same as those shown for gekkonids. Three types of generation glands were identified in cordylids (Van Wyk & Mouton, 1992), and these proved to be different to those existing in gekkonid species. These three types of generation glands were further compared regarding their ecdysis histology, which proved to be identical, thus, these glands differ only on gross morphological structure. Skin of all three species was also compared with regard to ecdysis, and while the histology of all three was identical, shedding activity was shown to differ in all three species. P. micro/epidotus displayed dormancy in the germinative layer for much longer periods of the year than either of the other two species, while P. capensis displayed very little dormancy. C. cordy/us displayed an intermediate pattern of ecdysis activity and dormancy. Autoradiography was performed on all species in both ecdysis activity and dormancy periods, to compare mitotic activity patterns in these periods. Generation gland activity appeared to correlate well with known testosterone peaks in the testicular cycle in all three species. Asynchrony between generation glands and skin scales was shown in all three species. / AFRIKAANSE OPSOMMING: GENERASIEKLIERE EN VERVELLINGSIKLUSSE IN GORDELAKKEDISSE (SAURIA: CORDYLIDAE) Drie spesies gordelakkedisse, Gordy/us cordy/us, Pseudocordy/us micro/epidofus en P. capensis, se gespesialiseerde velskubbe (generasiekliere) en gewone velskubbe word vergelyk. Hierdie velskubbe word deur histologiese metodes geëksamineer en vergelyk, met gebruik van data wat reeds in die literatuur bestaan (Maderson, 1966; 1967; 1968a), met soortgelyke strukture in Gekkonidae. Histologiese beskrywing van Cordylidae veistruktuur was identies met dié van Gekkonidae. Drie tipes generasiekliere was geïdentifiseer in gordelakkedisse (van Wyk & Mouton, 1992), en hulle verskil gedeeltlik van naverwante strukture in Gekkonidae. Hierdie drie tipes generasiekliere was verder vergelyk met betrekking tot hulle vervellingsiklus histologie, wat identies was. Dus verskil hulle net met betrekking tot hulle vorm. Vel is ook vergelyk met dieselfde metodes. Alhoewel daar geen verskille was met betrekking tot hulle histology nie, was die tye van aktiwiteit van kiem-sellae beduidend verskillend in alle spesies. In P. micro/epidofus het die kiem-sellaag russtadium baie langer geduur as in die ander twee spesies, terwyl P. cepensis amper geen russtadium getoon het nie. G. cordy/us het 'n intermediêre gedragspatroon vertoon tussen aktiewe en rustende fase met betrekking tot sy vervellingsiklus. Outoradiografie is gebruik op elke spesie, in beide aktiewe en rustende vervellingsfases, om verskille in mitotiese aktiwiteit te wys. Generasieklier aktiwiteit blyk te korreleer met pieke van testosteroonvlakke van die testikulêre siklus in al drie spesies. Asinkronie is aangetoon tussen generasiekliere en velskubbe in al drie spesies.

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Oxide scale must be removed before cold drawing wire, otherwise it will cause bad surface quality, inferior die life and many wire ruptures. The nature of oxide scales and the methods of scale removal are reviewed, with particular emphasis on mechanical descaling. This is the major concern of the research, therefore a cantilever bending test has been developed to assess the ease of removal of the scale on commercial steel rod surface in the laboratory. A scanner method and a Finite Element model have been developed to evaluate the critical strain for scale cracking and removal after cantilever bending. Scanning electron microscopy (SEM), together with electron backscattered diffraction (EBSD), energy diffraction spectrum (EDS) and X-ray element mapping analysis, was used to characterize the scale before and/or after bending test. The effects of laying temperature, cooling conditions, ageing time, relative humidity and temperature, and coil positions on scale cracking and removal behaviour were studied. It was found that laying temperature has a larger effect on descalability than cooling conditions. The effect of relative humidity and temperature on descalability depended on a critical holding time. Beyond it, relative humidity and temperature had no further effect on descalability. The higher the environmental temperature, the less the critical holding time. Ageing time had an effect on descalability, but the effect was relatively small. Failure in tension started with first cracks formed at the places with high stress concentration. As tensile strain increased, new cracks formed midway between the existing cracks. Crack spacing stayed uniform but decreased until the scale segments spalled off the rod surface. The crack spacing increased with scale thickness and decreased with strain applied. Scale cracking and spallation mechanisms in compression depended on the relative shear strength of the oxide, the buckling stability of the layer and the relative shear strength of the interface. Spallation always required the propagation of a crack at the interface. The residual sub-layer left on the rod surface of EAF steel after the bending test was identified as magnetite. On the same sample, copper enrichment was found at the scale/metal interface, but within the metal side, and silicon enrichment was found at the scale/metal interface, but within the scale side.

Magister Psychologiae - MPsych / Substance use is a major problem in South Africa, particularly within the Western Cape. The problem of substance use is prominent amongst adolescents in low socio-economic-status communities, and these prevalence rates are increasing. Literature regarding the onset of substance use is often limited and inadequate. It is for this reason that the South African Substance Use Contextual Risk Instrument (SASUCRI) was developed and employed to assess factors which contribute to adolescent substance use. The SASUCRI is a measure of the individual and contextual factors associated with adolescent substance use. It was developed to be used in low socio-economic-status communities to identify adolescents at risk for substance use as well as communities in which these risk factors are present. The initial validation study reports on the validity evidence for this instrument. The initial study identified items to be rewritten to improve the validity of the instrument. It further recommended the inclusion of additional items to improve reliability in some sub-scales. This contributed to the current study. The purpose of this study was to pretest the new and revised items. The researcher pretested both the English and the Afrikaans’s revised sub-scales of the SASUCRI. The following sub-scales were pretested; “School as support” (6 items), “School as a stressor” (6 items), “Tolerance for soft drugs” (6 items), Hopelessness individual”(11 items) and “Hopelessness community” (5 items). The theoretical framework employed was the Multi-Component Approach. The framework guided the data collection, analysis and partially the discussion of the findings. The study was of a qualitative nature. Two schools were selected from low socio-economic status communities. The study had 32 high school learners who participated. There were 4 focus groups conducted in total.

Rater training is important for improving the quality of human resource decisions. However, there is little research that has examined the influence of trainee individual differences on rater training effectiveness. In Study 1, I found support for a partially mediated model in which learning goal orientation, internal locus of control, and promotion focus influenced rater training motivation through general self-efficacy. In Study 2, I extended the model to include rater training criteria, and I found that rater training motivation did not predict declarative knowledge, rating validity, or rating accuracy, but cognitive ability predicted all three outcomes. Overall, the results suggest that although individual differences in attitudes are relevant for understanding rater training motivation, cognitive ability may be much more important for understanding rater training effectiveness. Implications for rater training theory and practice are discussed.