Trophodynamics of carnivorous zooplankton in the region of the subtropical convergence within the Indian sector of the Southern Ocean, with particular emphasis on chaetognaths
- Authors: Sterley, Jessica Anne
- Date: 2009
- Subjects: Zooplankton -- Antarctic Ocean , Chaetognatha , Euphausiacea , Amphipoda , Predation (Biology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5790 , http://hdl.handle.net/10962/d1005478 , Zooplankton -- Antarctic Ocean , Chaetognatha , Euphausiacea , Amphipoda , Predation (Biology)
- Description: Trophodynamics of carnivorous zooplankton in the region of the Subtropical Convergence (STC) in the Indian sector of the Southern Ocean was investigated during austral autumn (April 2007) as part of the first cruise of the Southern Ocean Ecosystem Variability Study. Within the region of the study, the STC was well defined by the 14°C surface isotherm which separated the Agulhas Return Current and Subtropical water in the north from Sub-Antarctic waters to the south. Total average abundance (3.89 ± 5.46ind 100m-3) and biomass (0.14 ± 0.27mg Dwt 100m-3) of carnivorous zooplankton south of the front were significantly higher than the total average abundance (1.33 ± 1.81ind 100m-3) and biomass (0.03 ± 0.05mg Dwt 100m-3) north of the front (p<0.001). There were no significant correlations between the selected physico-chemical (temperature and salinity) and the biological (mesozooplankton abundance and biomass) variables and the total abundance and biomass of the carnivorous zooplankton during the investigation (p>0.05 in all cases). There was no evidence of enhanced biomass and abundance values at stations occupied in the immediate vicinity of the front. Total average carnivorous zooplankton abundance was dominated by chaetognaths (Eukrohnia hamata Möbius 1875, Sagitta gazellae Ritler-Záhony 1909 and S. zetesios Fowler 1905) and euphausiids (Nematoscelis megalops Sars 1883, Euphausia longirostris Hansen 1908 and E. spinifera Sars 1883), which contributed up to 86.58 ± 32.91% of the total counts. The total average biomass was dominated by euphausiids and amphipods (Themisto gaudichaudii Guérin-Méneville 1825, Phronima sedentaria Forsskål 1775 and Vibilia armata Bovallius 1887) which contributed up to 71.45 ± 34.85% of the total counts. In general the populations of both the euphausiids and amphipods were dominated by females while the chaetognaths were dominated by juveniles. Numerical analysis identified two major zooplankton groupings within the survey area which did not coincide with the water masses within the survey area. The SIMPER procedure of the PRIMER package indicated differences between the groups were mainly attributed to changes in the abundance of the numerically dominant species rather than the presence or absence of individual species. The absence of any significant spatial patterns in the distribution of the carnivorous zooplankton suggests that the STC did not act as a biogeographical barrier during the present study. The mean feeding rates of the chaetognaths E. hamata, S. gazellae and S. zetesios were 1.82 ± 0.85prey d-1, 3.63 ± 2.08prey d-1 and 2.18 ± 0.59prey d-1, respectively. These rates correspond to a combined predation impact equivalent to <5% of the mesozooplankton standing stock or <10% of the mesozooplankton secondary production. Mesozooplankton, comprising mainly copepods was the dominant prey in the guts of the three chaetognath species. Total predation impact of the euphausiids, chaetognaths and amphipods, estimated using published daily ration data, on the mesozooplankton standing stock and secondary production ranged from 0.01% to 1.53% and from 0.03% to 30.54%, respectively. Among the carnivorous zooplankton, chaetognaths were generally identified as the dominant predators of mesozooplankton. Low predation impact of selected carnivorous zooplankton suggested that these organisms contributed little to the vertical carbon flux within the region of investigation during the study.
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Trophodynamics of mesozooplankton in the the vicinity of the subtropical convergence in the Indian sector of the Southern Ocean
- Authors: Daly, Ryan
- Date: 2009
- Subjects: Zooplankton -- Antarctic Ocean , Phytoplankton -- Antarctic Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5791 , http://hdl.handle.net/10962/d1005479 , Zooplankton -- Antarctic Ocean , Phytoplankton -- Antarctic Ocean
- Description: The trophodynamics of the numerically dominant mesozooplankton (200-2000 m) in the vicinity of the Subtropical Convergence (STC) in the Indian sector of the Southern Ocean during austral autumn (April / May) 2007 were investigated as part of the Southern Ocean Ecosystem Variability Study. The survey consisted of six north-south transects each bisecting the STC between 38º to 43ºS and 38º to 41º45’E. In total, 48 stations situated at 30 nautical mile intervals were occupied over a period of ten days. Hydrographic data revealed a well defined surface and sub-surface expression of the STC, which appeared to meander considerably between 41ºS and 41º15’S. Surface chlorophyll-a (chla) concentrations were low, ranging between 0.08 and 0.68 mg chl-a.m-3 and were generally dominated by the picophytoplankton (<2 m) which made up 66.6% (SD±17.6) of the total pigment. Chl-a concentrations integrated over the top 150m of the water column ranged between 11.97 and 40.07 mg chl-a.m-2 and showed no significant spatial patterns (p>0.05). Total integrated mesozooplankton abundance and biomass during the study ranged between 3934.9 and 308521.4 ind.m-2 (mean = 47198.19; SD±62411.4 ind.m-2) and between 239.8 and 4614.3 mg Dwt.m-2 (mean = 1338.58; SD ±1060.5), respectively. Again, there were no significant spatial patterns in the total mesozooplankton abundance or biomass within the region of study (p>0.05). No significant correlations were found between biological (chlorophyll-a concentrations and zooplankton abundance) and physico-chemical variables (temperature and salinity) (p>0.05). The total mesozooplankton community was numerically dominated by copepods of the genera Pleuromamma, Calanus, Oncaea and Oithona. Other important representatives of the mesozooplankton community included the tunicate, Salpa thompsoni, and the pteropod, Limacina retroversa. At the 40% similarity level, numerical analysis identified five distinct mesozooplankton groupings within the survey area. Differences between the groupings were associated with changes in the relative contribution of numerically dominant species rather than the presence or absence of individual species. No groupings were associated with any specific feature of the front within the survey area. The feeding rates of the six most numerically abundant mesozooplankton species (Calanus simillimus, Limacina retroversa, Pleuromamma abdominalis, Clausocalanus breviceps, Oncaea conifera, Salpa thompsoni) accounting for on average 39% of the total mesozooplankton counts, were investigated using the gut fluorescence technique. For all species, the total gut pigment contents during the night time were significantly higher than the daytime values (p<0.05 for all species). The gut evacuation rates (k) for selected mesozooplankton ranged between 0.14 and 0.81 h-1. The ingestion rates ranged between 147.8 and 5495.4 ng(pigm)ind-1.day-1 which corresponded to a daily ration of between 2.4 and 10.9% body carbon. The combined grazing impact of the selected species on the daily phytoplankton standing stock was highly variable and ranged between 1.2 and 174.1% with an average of 27.3% (SD±38.78%) within the survey area. The highest grazing impact (>60%) was typically associated with those stations where the pteropod, L. retroversa, and the tunicate, S. thompsoni, contributed more than 5% of the total mesozooplankton counts. No significant differences were found in the grazing impact of any or all selected species situated either north, south or in the immediate vicinity of the front (p>0.05 in all cases). The lack of defined spatial patterns in the mesozooplankton abundance and community structure suggests that the STC did not act as a significant biogeographic barrier to the distribution of mesozooplankton during the study. It is presumed that the large scale mixing event caused by a storm prior to this study was responsible for the observed lack of elevated biological activity within the region of the STC.
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Understanding form and technique : Andrew Tracey's contribution to knowledge of lamellophone (mbira) music of Southern Africa
- Authors: Gumboreshumba, Laina
- Date: 2009
- Subjects: Tracey, Andrew T N Ethnomusicology -- Africa Mbira Mbira music
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2638 , http://hdl.handle.net/10962/d1002303
- Description: This thesis interrogates Andrew Tracey’s career as an ethnomusicologist and the significance of his research and publications on lamellophone (mbira) music of the Shona/Sena in Zimbabwe and Mozambique to subsequent scholarship of lamellophones throughout southern Africa. Through a survey of authors who have cited Tracey’s publications, this study assess how his use of the pulse notation transcription method and his theory of form and harmonic structure in mbira music, which he terms ‘the system of the mbira’ (A. Tracey, 1989) have influenced and contributed to the work of ethnomusicologists, musicologists and composers. Further this research evaluates the impact on subsequent publications by other scholars of Tracey's technical analysis of mbira music. Organizing and indexing Andrew Tracey's field collection in the ILAM archive gave direct knowledge of the scope of his work. The thesis consists of six chapters. The first chapter contains a general introduction to the thesis and outlines the goals of the research. Chapter Two presents a biographical sketch of Andrew Tracey. A general introduction to the lamellophone (mbira) family of musical instruments in Zimbabwe and elsewhere in Africa is presented in Chapter Three, which also addresses the social function of lamellophone music. Chapter Four gives a summary of Andrew Tracey’s research on the Shona mbira (his publications, recordings, films etc), and it analyzes his theory - “The system of the mbira” - in which he defines the form and structure of mbira music. Chapter Five examines the impact of Andrew Tracey’s research and publications on mbira music to subsequent scholarship and makes an analysis and evaluation of the significance of his contribution to the body of knowledge of the instrument and its music. In addition I relate my personal experiences with mbira music as a Shona person and mbira player and give my opinions on Tracey’s and subsequent scholars’ theories on mbira music. Chapter Six concludes with a summary of outcomes of this research. Basing on the analyses of presented data, it is deduced that, despite a few shortcomings, Andrew Tracey’s research on mbira music is crucial for it laid the groundwork for subsequent mbira scholarship.
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Understanding propaganda: Noam Chomsky and the institutional analysis of power
- Authors: Cathey, Paul Eben
- Date: 2009
- Subjects: Chomsky, Noam -- Political and social views Propaganda Gramsci, Antonio, 1891-1937 -- Political and social views Social classes
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2765 , http://hdl.handle.net/10962/d1002975
- Description: This thesis argues that Noam Chomsky’s theory of propaganda is a useful way to understand class domination. The strengths and weaknesses of Chomsky’s theory are examined by means of a comparison with Antonio Gramsci’s theory of cultural hegemony. Since work that discusses and analyses Chomsky’s theory is sparse, this piece first gives a detailed explanation of his theory. This requires a short clarification of Chomsky’s terminology, focusing on his definitions of indoctrination and class. Thereafter a thorough account of Chomsky’s ideas regarding class structure, the indoctrinating functions of educational and media institutions and the difference between upper and lower class propaganda are discussed. A common criticism of Chomsky’s arguments is that they are conspiratorial. Thus, following the discussion of Chomsky’s theory I present an argument that Chomsky uses an institutional analysis as opposed to conspiracy theory to reach his conclusions. After arguing that Chomsky has a coherent, logical theory of propaganda that is not conspiratorial, this thesis shifts to a comparison of Chomsky and Gramsci’s theory. The elements of Gramsci’s theory that are relevant to Chomsky are discussed, focusing on their overall similarities, in particular, the question of consent. The final chapter consists of a comparison of the two theories, examining each theorist’s ideas on the nature of education, language, consent and the possible ways in which the lower classes can oppose their own oppression.
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Understanding the complexity of metabolic regulatory systems an investigation into the regulation of hydantoin-hydrolysis in Pseudomonas putida RU-KM3s
- Authors: De la Mare, Jo-Anne
- Date: 2009
- Subjects: Pseudomonas , Hydantoin , Hydrolysis , Enzymes -- Regulation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3993 , http://hdl.handle.net/10962/d1004053 , Pseudomonas , Hydantoin , Hydrolysis , Enzymes -- Regulation
- Description: It has been well-established that Pseudomonas species possess extremely versatile metabolic systems allowing them to utilise a wide range of nutrient sources and, furthermore, that the regulation of these enzyme systems involves highly evolved and sophisticated regulatory machinery. This study examined the complexity of metabolic regulation in Pseudomonas using the hydantoin-hydrolysing system of the environmental isolate, Pseudomonas putida RU-KM3s. In this system, the genes encoding dihydropyrimidinase and β-ureidopropionase (dhp and bup) are arranged divergently on the chromosome, separated by a 616 bp intergenic region involved in the transcriptional regulation of these genes. The focus was on the transcriptional regulation of dhp expression. DHP activity was found to be sensitive to several environmental signals including growth phase, carbon catabolite repression (CCR), substrate induction and quorum sensing (QS). Bioinformatic analysis of the intergenic region upstream of dhp revealed a number of putative binding sites for transcriptional regulators, including recognition sequences for the alternate sigma factors σ54 and σ38, as well as for the global regulators Anr (for anaerobic regulator) and Vfr (for virulence factor regulator). The targeted disruption of the genes encoding the transcriptional regulators, Vfr and the major CCR protein, Crc, resulted in a partial relief from repression for the vfr- mutant under quorum sensing conditions and a general decrease in activity in the crc- mutant. This data suggested that both Vfr and Crc were involved in regulating DHP activity. Mutational analysis of the dhp promoter revealed that at least two sites were involved in regulating transcriptional activity, one which mediated activation and the other repression. These sites were designated as a putative Anr box, situated 232 bp from the start codon of dhp, and a CRP-like binding site, at a position 213 bp upstream of dhp. Taken together, this data shows the involvement of several global regulatory factors in controlling the expression of dhp. A complex synergistic model was proposed for the transcriptional regulation of dhp, involving alternate sigma factors in addition to both global and specific regulators and responding to a number of environmental signals associated with growth phase, including nutrient availability, cell density and oxygen status.
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Understanding the differences in marking performance of JSC mathematics markers in Namibia : a case study
- Authors: Mutuku, Elizabeth
- Date: 2009
- Subjects: Educational change -- Namibia , Mathematics -- Namibia -- Examinations -- Case studies , Mathematics -- Study and teaching -- Namibia -- Case studies , Grading and marking (Students) -- Namibia -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1999 , http://hdl.handle.net/10962/d1015223
- Description: Education reform in Namibia brought about changes to mathematics education since independence. This has put pressure on the government to provide both resources and qualified mathematics teachers to help drive the reform process in all teaching and learning activities. This included availing reliable and valid national examination results which is a measure of whether the newly introduced programmes are working or not. For the Ministry of Education this meant training more mathematics teachers and ensuring that competent and reliable teachers are appointed for marking national examination every year. The teachers' training process however, has not been going as fast as it was expected and year after year the Directorate of National Examinations and Assessment experienced problems in obtaining competent teachers for the marking of national examination. The purpose of the study was to understand the differences in marking performances of the JSC mathematics national examination markers. Particularly the study was to create a clear and detailed understanding of different factors that could possibly affect the marking performance of different markers. In addition, the study was to investigate the effect the mathematical content knowledge of the markers has on their marking performance. It was evident from the findings that their mathematical content knowledge had influenced their marking performance. Moreover the research findings also gave a strong indication that there are other factors that were influencing the markers marking performance. These were the markers' knowledge of the assessment and marking process, the markers' marking experience, the markers' socioeconomic background. The difference in their moderators' input has emerged as the other factors that have influenced their performance in marking and consequently contributed to the differences in their marking performances.
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Unearthed : personifications of widowhood and acts of memory : volume 1 and 2
- Authors: Arbi, Linda Margaret
- Date: 2009
- Subjects: Widowhood -- Social aspects -- South Africa Widowhood -- Social aspects -- Cape of Good Hope (South Africa) Widows in art -- South Africa Widows in art -- Cape of Good Hope (South Africa) Memory in art -- South Africa Memory in art -- Cape of Good Hope (South Africa)
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2428 , http://hdl.handle.net/10962/d1002225
- Description: By researching visual traditions of representing widows in relation to a social role, I explore how these may be related to processes of mourning and memory. My study begins with an historical reading and, along with an analysis of Renaissance widow portraiture, I trace the experiences of widows in the Cape of Good Hope. For the purposes of this thesis, I have selected images of widows to investigate memory-work particularly when speaking of loss. I re-view these memory processes through recent historical and art historical discourse with reference to contemporary South African artworks in order to understand how public memory is formed by way of visual documentation. These narratives around widowhood have informed the subject matter for my Master’s exhibition and shed light on my own experience as a widow. The interaction between objects and memory are of particular interest and manifest in my studio art practice.
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Using semantic knowledge to improve compression on log files
- Authors: Otten, Frederick John
- Date: 2009 , 2008-11-19
- Subjects: Computer networks , Data compression (Computer science) , Semantics--Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4650 , http://hdl.handle.net/10962/d1006619 , Computer networks , Data compression (Computer science) , Semantics--Data processing
- Description: With the move towards global and multi-national companies, information technology infrastructure requirements are increasing. As the size of these computer networks increases, it becomes more and more difficult to monitor, control, and secure them. Networks consist of a number of diverse devices, sensors, and gateways which are often spread over large geographical areas. Each of these devices produce log files which need to be analysed and monitored to provide network security and satisfy regulations. Data compression programs such as gzip and bzip2 are commonly used to reduce the quantity of data for archival purposes after the log files have been rotated. However, there are many other compression programs which exist - each with their own advantages and disadvantages. These programs each use a different amount of memory and take different compression and decompression times to achieve different compression ratios. System log files also contain redundancy which is not necessarily exploited by standard compression programs. Log messages usually use a similar format with a defined syntax. In the log files, all the ASCII characters are not used and the messages contain certain "phrases" which often repeated. This thesis investigates the use of compression as a means of data reduction and how the use of semantic knowledge can improve data compression (also applying results to different scenarios that can occur in a distributed computing environment). It presents the results of a series of tests performed on different log files. It also examines the semantic knowledge which exists in maillog files and how it can be exploited to improve the compression results. The results from a series of text preprocessors which exploit this knowledge are presented and evaluated. These preprocessors include: one which replaces the timestamps and IP addresses with their binary equivalents and one which replaces words from a dictionary with unused ASCII characters. In this thesis, data compression is shown to be an effective method of data reduction producing up to 98 percent reduction in filesize on a corpus of log files. The use of preprocessors which exploit semantic knowledge results in up to 56 percent improvement in overall compression time and up to 32 percent reduction in compressed size. , TeX , pdfTeX-1.40.3
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Using the van Hiele theory to analyse geometrical conceptualisation in grade 12 students: a Namibian perspective
- Authors: Mateya, Muhongo
- Date: 2009
- Subjects: Hiele, Pierre M. van Hiele-Geldof, Dina van Geometry -- Study and teaching (Secondary) -- Namibia Mathematics -- Study and teaching (Secondary) -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1820 , http://hdl.handle.net/10962/d1003706
- Description: The study reported here utilised a theory of levels of geometric thinking. This theory was proposed and developed by two Dutch mathematics educators, Pierre van Hiele and his wife, Dina van Hiele-Geldof. The van Hiele theory enables investigations into why many students experience difficulties in learning geometry. In many nations, such as the UK, the USA, Netherlands, the USSR and to a certain extent, Nigeria and South Africa, research evidence has indicated that the overall students’ mathematical competencies are linked to their geometric thinking levels. This study is the first of its kind to apply the van Hiele theory of geometric thinking in the Namibian context to analyse geometrical conceptualisation in Grade 12 mathematics students. In all, 50 Grade 12 students (20 from School A and 30 from School B) were involved in this study. These students wrote a van Hiele Geometry Test adapted from the Cognitive Development and Achievement in Secondary School Geometry test items. Thereafter, a clinical interview with the aid of manipulatives was conducted. The results from this study indicated that many of the School A and School B students who participated in the research have a weak conceptual understanding of geometric concepts: 35% of the School A and 40% of the School B subsamples were at the prerecognition level. 25% and 30% of the School A, and 20% and 23.3% of the School B students were at van Hiele levels 1 and 2 respectively. An equal number of students but different in percentages, 2 (10%) in School A and 2 (6.7%) in School B, were at van Hiele level 3. Only one student from School B attained van Hiele level 4. These results were found to be consistent with those of previous similar studies in UK, USA, Nigeria and South Africa. The findings of this study also highlight issues of how the Namibian Grade 12 geometry syllabus should be aligned with the van Hiele levels of geometric thinking as well as the use of appropriate and correct language in geometrical thinking and problem solving.
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Variability analysis of a sample of potential southern calibration sources
- Authors: Hungwe, Faith
- Date: 2009
- Subjects: Southern sky (Astronomy) Radio sources (Astronomy) Active galactic nuclei Very Long Baseline Array (Telescopes) Calibration Radio telescopes -- Southern Hemisphere Radio astronomy -- Southern Hemisphere Radio interferometers Very long baseline interferometry Radio astronomy -- Observations Radio astronomy -- South Africa Radio telescopes -- South Africa Square Kilometer Array (Spacecraft)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5495 , http://hdl.handle.net/10962/d1005281
- Description: A considerable number of Very Long Baseline Interferometry (VLBI) surveys have been conducted in the northern hemisphere and very few in the southern hemisphere mostly because of a lack of telescopes and therefore adequate baseline coverage. Thus there is a deficit of calibrator sources in the southern hemisphere. Further, some of the most interesting astronomical objects eg. the galactic centre and the nearest galaxies (the small and large Magellanic Clouds) lie in the southern hemisphere and these require high resolution studies. With a major expansion of radio astronomy observing capability on its way in the southern hemisphere (with the two SKA (Square Kilometre Array) precursors, meerKAT (Karoo Array Telescope) and ASKAP (Australian SKA Pathfinder), leading to the SKA itself) it is clear that interferometry and VLBI in the southern hemisphere need a dense network of calibration sources at different resolutions and a range of frequencies. This work seeks to help redress this problem by presenting an analysis of 31 southern sources to help fill the gaps in the southern hemisphere calibrator distribution. We have developed a multi-parameter method of classifying these sources as calibrators. From our sample of 31 sources, we have 2 class A sources (Excellent calibrators), 16 class B sources (Good calibrators), 9 class C sources (Poor calibrators) and 4 class D sources (Unsuitable calibrators).
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Vocational language learning and how it relates to language policy issues
- Authors: Maseko, Pamela
- Date: 2009
- Subjects: Language policy -- South Africa Language and education -- South Africa Language and languages -- Study and teaching (Higher) -- South Africa Multilingualism -- South Africa Education, Higher -- South Africa Vocational education -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3583 , http://hdl.handle.net/10962/d1002158
- Description: This research explores issues relating to language policy, and language learning and teaching. It further looks at the relationship that exists between language policy and language learning and teaching. In the research I argue that well-thought out and well-meaning language policies will fail to be implemented meaningfully if there is no clear and unambiguous implementation plan. I also note that the national vision and ideals which are often embodied in the language policy fail to take effect if, again, there is no comprehensive implementation plan. This view is held by many scholars and researchers in the areas of language policy and planning.
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