No description available.

No description available.

A Research Report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements of the degree of Master of Science. October 2012, Johannesburg. / Several commentators describe the low performance of South African students in mathematics as ‗a crisis‘. In the Foundation Phase specifically, there is evidence of a lack of shift from concrete counting-based strategies to more abstract calculation-based strategies (Ensor et al., 2009; Schollar, 2009). Concrete counting-based strategies refer to actions where the learner cannot find the answer to a mathematical problem without using concrete objects. In contrast, abstract calculation-based strategies involve strategies where the child does not need concrete objects to find the answer, but can instead use mental calculations in which numbers have been transformed into abstract objects upon which operations can then be carried out. Ensor et al argue that the poor mathematical results in South Africa are the result of inefficient moves made by learners from counting to calculating. In their study, many students failed to move their thinking sufficiently forward from concrete counting actions to abstract thinking. The focus of this study is to investigate a sample of Grade 2 learners‘ strategies on tasks drawn from the Learning Framework in Number (LFIN) test and responses on number related questions in the Annual National Assessment tests (ANA). I use the Learning Framework in Number to describe the stage of learners in their shift from concrete to a more abstract way of thinking about number. The theory of reification refers to the turning of processes into objects, and in this research, the origin of an abstract object in reification is explored. I also aim to understand the kinds of information I can get from children‘s grasp of early number strategies, by looking at the responses of learners on the ANA and LFIN tests. My research question is: What do the two tests (ANA and LFIN) tell us about the strategies on early number used by a sample of Grade 2 learners in a township school in Gauteng? The two critical questions that follow from this are:  How does learner performance on number problems compare across the two tests?  What evidence in relation to concrete/abstract strategies is evident in the responses of learners in the two tests? My findings showed that the learners in the school that I investigated still relied a great deal on concrete counting methods to answer questions. In spite of this, the mean ANA mark were much higher than the LFIN mean. The low number range of the ANA test, (1-34 for most of the number related questions), made it possible for the learners to use concrete counting (fingers or tallies) to answer the questions. The relatively low LFIN mark range indicated that children had difficulties in moving to more abstract ways of working with number. The implications of the reliance on concrete counting is potential difficulties when the learners move into higher grades where the number range is much higher, making the use of concrete methods time consuming and error prone.

This study investigated the physiological ecology, larval biology and population genetics of the nudibranch molluscs Adalaria proxima (A & H) and Onchidoris muricata (Müller). These two species are annual, simultaneous hermaphrodites and are ecologically very similar with the exception that A. proxima reproduces by means of pelagic lecithotrophic larvae whereas Omuricata has long-term planktotrophic larvae. The aim of the study was therefore to determine the selective pressures which resulted in the evolution of different larval types in these two species, and to ascertain the ecological and population genetic consequences thereof. Simple energy budgets comprising the major components (consumption, growth, respiration and reproduction) were constructed for laboratory populations of each species. In both A. proxima and O. muricata, feeding rate displayed an asymptotic increase with body size. Mean feeding rates of A. proxima were greater than those of comparable O. muricata individuals, and overall assimilation efficiency was higher in A. proxima than in O. muricata. This difference was reflected in the somatic growth rates which were correspondingly greater in A. proxima than in O. muricata. Net growth efficiencies were broadly comparable between the two species, however, growth of A. proxima was approximately linear over' time whilst that of O. muricata displayed a curvilinear, almost exponential, pattern. This is interpreted as demonstrating that some form of constraint (possibly feeding rate) operated on the growth rates of A. proxima but not on those of O. muricata. Respiration rates were found to be relatively constant within given animals, but significant differences were found between individuals. The allometry of respiration rate was not constant; Omuricata demonstrated a more rapid increase in respiration rate with increasing body size than did A. proxima. Individual variations in respiration rate did not reflect variations in the energy partitioned to either growth or reproduction. Reproductive patterns in the two species were dissimilar. A. proxima laid fewer spawn masses containing fewer, larger ova than those laid by O. muricata individuals. In addition, the spawning period of A. proxima was shorter than that of O. muricata (60 days and 105 days respectively). Both species exhibited a similar (proportional) degree of somatic catabolism over these periods. The consequently more rapid "degrowth" of A. proxima is interpreted as the necessary utilization of an energy resource (i. e. the soma) caused by an inability to meet the energy demands of reproduction through feeding alone. This was not the case in Oanuricata individuals which exhibited a much smaller maximum body size and were able to feed at a sufficiently rapid rate to maintain reproduction. In the latter case, the longer reproductive period served to maximise the total reproductive output. Several different measures of "Reproductive Effort" (RE) were calculated. These generally indicated that the RE of Omuricata was considerably greater than that of A. proxima. Although such differences have been used in the literature to classify the respective costs of different larval types or "reproductive strategies", the variability of the RE's obtained from the different measures used here has led to the suggestion that the general lack of association between RE and reproductive strategy which has been reported elsewhere may (partially) be attributable to the different measures of RE employed in different studies. Studies of the embryonic and larval period showed that the egg-to-juvenile period of O. muricata was approximately 50% longer than that of A. proxima. This difference was primarily attributable to the extended pelagic development of O. muricata larvae. Estimates of the degree of dispersal, and hence gene-flow, between populations of these species were tested by investigating the biochemical genetics of such populations. No data were available for O. muricata, but A. proxima populations proved to be more genetically heterogeneous than had been expected. It is therefore concluded that actual pelagic dispersal may be considerably abbreviated over that expected on the basis of larval culture data alone. A model is developed to explain the possible consequences of different egg-to-juvenile periods (which accrue from different larval types) on both the ecology of the benthic adult, and on overall energy partitioning to reproduction. However, although (probable) proximate causes and effects of the different reproductive traits exhibited by A. proxima and Oanuricata are shown, it has not been possible to determine the exact selective pressures which caused A. proxima to diverge from the ancestral "O. muricata" stock through the evolution of a pelagic lecithotrophic larva.

The experiments reported in this thesis have investigated the role of the basolateral amygdala (BLA) in the process by which conditioned stimuli (CS) acquire motivational salience and, as conditioned reinforcers, direct cocaine-seeking behaviour in the rat. Excitotoxic lesions of the BLA did not interfere with the reinforcing effects of cocaine in rats. Intra-peritoneal injections of cocaine produced similar locomotor responses in both lesioned and control animals and both groups also produced equivalent dose-response functions during a within- session dose-response test. Similarly, lesioned and control animals acquired cocaine self-administration under both continuous and progressive-ratio schedules of reinforcement. However, BLA-lesioned animals were (i) severely impaired in the acquisition of second-order schedules of cocaine self-administration; (ii) more sensitive than control animals to reductions in drug dose under a progressive-ratio schedule of cocaine self-administration and (iii) less sensitive than control animals to the omission of a drug-related CS, under a fixed-interval schedule of selfadministration. In vivo microdialysis showed that lesions of the BLA were associated with an impaired glutamatergic response to intra-nucleus accumbens infusions of cocaine, but that the dopaminergic response of lesioned and control animals of were identical. These findings suggest that drug-seeking behaviour in rats with lesions of the BLA is influenced more by the primary reinforcer and concomitantly less by secondary, conditioned reinforcers. This would indicate that the BLA is significantly involved in the development of cue-elicited drug-seeking behaviour and, by inference, this structure may also play an important role in the development of problem drug-use in humans.

1. Synaptosomes have been isolated from guiuea-pig cerebral cortex and their appearance and enzymic and respiratory properties found to be similar to those reported for synaptosomes by other workers. 2. The effects of the convulsants, strychnine and pentamethylene tetrazol, and the anticonvulsants, phenobarbitone and acetazolamide, on some of the properties of synaptosomes have been examined. 3. The resting respiratory rate of synaptosomes was found to be insensitive to the convulsants and anticonvulaants and to a variety of other compounds which affect excitable neuronal membranes *in vivo*. The possible significance of these results has been discussed. 4. The incorporation of 14C in to synaptosomes from (U-14C)-glucose was inhibited by pentamethylene tetrazol and enhanced by phenobarbitone. 5. The uptake of xylose, which did not seem to occur by means of a simple diffusion process, was unaffected by phenobarbitone and pentamethylene tetrazol. 6. The concentration of xylose in the synaptosomes, once xylose uptake was complete, was unaffected by 2, 4-dinitroplienol. 7. The release of osmotically active constituents from synaptosomes suspended in warm sucrose was very much reduced by phenobsrbitone at relatively low concentrations and by acetaszolamide at concentrations which were substantially greater than those found 'in vivo'. 8. 45 per cent of the Na+ and 27 per cent of the K+ was lost to the medium if freshly prepared synaptosomes were incubated in sucrose at 25°C for 30 minutes, Phenobarbitone prevented the loss of these ions during the incubation. 9. Phenobarbitone had no effect on the release of xylose from synaptosomes which were suspended in warm sucrose.

M.Sc., Faculty of Science, University of the Witwatersrand, 2011 / This study was concerned with the constitution of the ‘legitimate text’ - a key construct in Basil Bernstein’s (2000) theory of the pedagogic device. The question the study sought to understand was: what is constituted as the legitimate text across the mathematics education literature, the official curriculum document, in the official assessment texts, and in the textbook used in the classroom observed for the topic of number pattern. These sources were compared with what was constituted as the legitimate text in a sequence of five lessons based on number patterns in Grade 11 in an inner city school. This was a qualitative case study, the methodology of which was framed by Bernstein’s theory which explains the sociological nature of knowledge, the implicitness and explicitness of the communication for the acquisition of the legitimate text and hence opportunities to learn. One teacher was observed while teaching number pattern to a G11 class in an inner-city high school in Johannesburg in South Africa. A sequence of five lessons was videotaped and transcribed. The documents were analysed. One broad evaluative event with numerous sub-events called input objects were used to chunk the data into more manageable units of analysis. A framework emanating from the literature and from the analysis of the curriculum was used to present and categorise the legitimate text from the documents and the classroom. Kieran’s (2007) model of school algebra was used to do the analysis as well as Dowling’s (1998) model of domains of practice. The results of the study showed that the documents did not align with each other in terms of what they constituted as the legitimate text. It was found that the teacher aligned with the curriculum document. The results revealed that the teacher preferred working with numeric contexts. The consequence of this misalignment was that the documents created an additional work load for the teacher to understand and interpret them (documents).

Orientador: Maria Alice Faria / Banca: Dagoberto Buim Arena / Banca: Maria Aparecida B. de Camargo / Resumo: Esta pesquisa tem por objetivo o estudo do livro infanto-juvenil O boy da Via Láctea, de Regina Chamlian; a escritora usou o intertexto e se baseou em O capote do escritor russo Gogol recriando o texto adaptando-o aos nossos dias. Procuramos na primeira parte definir literatura e literatura infanto-juvenil; discutimos em seguida as nuances da literatura infantil, infanto-juvenil e a pedagogia numa tentativa de esclarecimentos sobre estes assuntos polêmicos. Nosso trabalho abordou também o conceito de leitura partindo dos métodos utilizados no Brasil para o aprendizado até o conceito de texto e sua diversidade, existente nos Parâmetros Curriculares Nacionais (PNCs). Em seguida analisamos literariamente o texto de Chamlian, O boy da Via Láctea e o conto de Gogol, O capote comparando-os, já que há uma intertextualidade declarada por parte da autora citada. A segunda parte compreendeu a recepção do texto e para isso utilizamos a transcrição de uma entrevista realizada com alunos de uma oitava série de uma escola pública de Assis, SP, no ano de 2000. / Abstract: This research aimed at the study of the infant-juvenile book: O boy da Via Láctea , by Regina Chamlian; the writer used the intertext and was based on O capote, by the Russian writer Gogol recreating the text and adapting it to the today's world. We sought in its first part to define literature and infant-juvenile literature; and after that, we discussed the nuances of infant literature, infant-juvenile literature and the pedagogy in an attempt to explain these polemic subjects. Our work also approached the concept of literature from the learning methods in use in Brazil to the concept of text and its diversity, present in the Parâmetros Curriculares Nacionais (PCNs). After that, we analyzed the text O boy da Via Láctea, by Chamlian and the short story, O capote, by Gogol comparing them as there is an intertextuality according to the first quoted author. The second part comprehended receiving of the text and for these purpose we used the transcription of an interview carried out with students of an eighth grade class in a public school in Assis - SP, in the year 2000. / Mestre

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.