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Photophysicochemical and photodynamic antimicrobial chemotherapeutic studies of novel phthalocyanines conjugated to silver nanoparticles

  • Authors: Rapulenyane, Nomasonto
  • Date: 2013 , 2013-06-10
  • Subjects: Phthalocyanines , Photochemistry , Photochemotherapy , Cancer -- Photochemotherapy , Anti-infective agents , Escherichia coli , Nanoparticles , Silver , Zinc
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4291 , http://hdl.handle.net/10962/d1003912 , Phthalocyanines , Photochemistry , Photochemotherapy , Cancer -- Photochemotherapy , Anti-infective agents , Escherichia coli , Nanoparticles , Silver , Zinc
  • Description: This work reports on the synthesis, characterization and the physicochemical properties of novel unsymmetrically substituted zinc phthalocyanines: namely tris{11,19, 27-(1,2- diethylaminoethylthiol)-2-(captopril) phthalocyanine Zn ((ZnMCapPc (1.5)), hexakis{8,11,16,19,42,27-(octylthio)-1-(4-phenoxycarboxy) phthalocyanine} Zn (ZnMPCPc(1.7)) and Tris {11, 19, 27-(1,2-diethylaminoethylthiol)-1,2(caffeic acid) phthalocyanine} Zn ((ZnMCafPc (1.3)). Symmetrically substituted counterparts (tetrakis(diethylamino)zinc phthalocyaninato (3.8), octakis(octylthio)zinc phthalocyaninato (3.9) and tetrakis (carboxyphenoxy)zinc phthalocyaninato (3.10) complexes) were also synthesized for comparison of the photophysicochemical properties and to investigate the effect of the substituents on the low symmetry Pcs. The complexes were successfully characterized by IR, NMR, mass spectral and elemental analyses. All the complexes showed the ability to produce singlet oxygen, while the highest triplet quantum yields were obtained for 1.7, 1.5 and 3.9 (0.80, 0.65 and 0.62 respectively and the lowest were obtained for 1.3 and 3.10 (0.57 and 0.47 respectively). High triplet lifetimes (109-286 μs) were also obtained for all complexes, with 1.7 being the highest (286 μs) which also corresponds to its triplet and singlet quantum yields (0.80 and 0.77 respectively). The photosensitizing properties of low symmetry derivatives, ZnMCapPc and ZnMCafPc were investigated by conjugating glutathione (GSH) capped silver nanoparticles (AgNP). The formation of the amide bond was confirmed by IR and UV-Vis spectroscopies. The photophysicochemical behaviour of the novel phthalocyanine-GSH-AgNP conjugates and the simple mixture of the Ag NPs with low the symmetry phthalocyanines were investigated. It was observed that upon conjugation of the phthalocyanines to the GSH-AgNPs, a blue shift in the Q band was induced. The triplet lifetimes and quantum yields improved upon conjugation as compared to the phthalocyanines (Pc) alone. Complex 1.5 triplet lifetimes increased from 109 to 148 and triplet quantum yield from 0.65 to 0.86 upon conjugation. Fluorescence lifetimes and quantum yields decreased for the conjugates compared to the phthalocyanines alone, due to the quenching caused by the Ag NPs. The antimicrobial activity of the zinc phthalocyanines (complexes 1.3 and 1.5) and their conjugates against Escherichia coli was investigated. Only 1.3 and 1.5 complexes were investigated because of the availability of the sample. In general phthalocyanines showed increase in antibacterial activity with the increase in phthalocyanines concentration in the presence and absence of light. The Pc complexes and their Ag NP conjugates showed an increase in antibacterial activity, due to the synergistic effect afforded by Ag NP and Pcs. Improved antibacterial properties were obtained upon irradiation. 1.5-AgNPs had the highest antibacterial activity compared to 1.3-AgNPs conjugate; these results are in agreement with the photophysical behaviour. This work demonstrates improved photophysicochemical properties of low symm
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  • Date Issued: 2013

A new continuum mapping procedure at HartRAO

  • Authors: Büchner, Sarah
  • Date: 2012-06-19
  • Subjects: Hartebeesthoek Radio Astronomy Observatory , Radio astronomy -- Methodology , Galactic cosmic rays
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5510 , http://hdl.handle.net/10962/d1007766 , Hartebeesthoek Radio Astronomy Observatory , Radio astronomy -- Methodology , Galactic cosmic rays
  • Description: A basket weaving technique for making radio continuum maps has been developed at the Hartebeesthoek Radio Astronomy Observatory (HartRAO). This data reduction technique significantly reduces scanning effects by using independent maps scanned in orthogonal directions. The observation and data analysis procedures that were developed are presented. The technique was used to map the supernova remnant MSH 15-52 at frequencies of 5000 MHz and 8500 MHz. The flux spectral index for this supernova remnant was found to be 0.83 ± 0.02 in this frequency range. Two regions (A and B) of the Galactic plane were observed at 8500 MHz with a resolution of 6'. Region A covered the 5°x5° area 47.5°< k 52.5°, Ibl < 2.5°, and region B was the 4.2°x3° area 320.4°< I <334.6°, Ibl < 1.5°. Far infrared observations at 60 !lm were used in conjunction with the radio maps to separate the thermal and non-thermal components of the radio emission. The technique can be used to map the Galactic plane at 8500 MHz using dual polarisation once the receiver at HartRAO has been upgraded. This would fulfil a need for a medium resolution, high frequency survey of the southern Galactic plane. , Adobe Acrobat Pro 9.4.6 , Adobe Acrobat 9.46 Paper Capture Plug-in
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Understanding the biomolecular interactions involved in dimerisation of the Saccharomyces cerevisiae eukaryotic translation initiation factor 5A

  • Authors: Charlton, Jane Laura
  • Date: 2012
  • Subjects: Proteins -- Synthesis -- Research , Saccharomyces cerevisiae -- Research , Dimers , Dimers -- Research , Eukaryotic cells -- Research , Yeast -- Research
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4057 , http://hdl.handle.net/10962/d1004118 , Proteins -- Synthesis -- Research , Saccharomyces cerevisiae -- Research , Dimers , Dimers -- Research , Eukaryotic cells -- Research , Yeast -- Research
  • Description: Translation initiation factor 5A (IF5A) is an essential, highly conserved protein found within all eukaryotic (eIF5A) and archaeal (aIF5A) cells. The IF5A protein is unique in that it contains the amino acid hypusine; a two-step post translational modification of a single, conserved lysine residue. Although hypusination of eIF5A is vital for eukaryotic cell viability, the primary role of the protein and its hypusine side chain remain a mystery. eIF5A, initially identified as a translation initiation factor, is not required for global protein synthesis leading to the prevailing proposal that eIF5A is purely involved in the translation of a select subset of mRNAs. Recently a number of mutational studies have focused on the conserved, hypusine-containing loop region of eIF5A where specific residues have been found to be essential for activity without affecting hypusination. It has been postulated that eIF5A exists as a dimer (40 kDa) under native conditions and that these residues may be at the interface of dimerisation. The aim of this research was therefore to conduct a mutational analysis of the loop region in support of this hypothesis. A functional analysis of the Saccharomyces cerevisiae eIF5A mutant proteins K48D, G50A, H52A and K56A revealed that these substitutions impaired growth to varying degrees in vivo with G50A and K48D mutant proteins displaying the most convincing defects. Gel filtration profiles gave unexpected results determining eIF5A mutant and wild type proteins to have a native molecular weight of 30 to 31 kDa, suggesting that the eIF5A oligomeric state may be transitory and subject to certain conditions. The inconclusive results obtained from using gel filtration studies led to an investigation into the feasibility of producing native, hypusinated peptides for future structural studies using nuclear magnetic resonance. Hypusinated and unhypusinated eIF5A were successfully separated into their domains making this a possibility. Finally, this study proposes a role for eIF5A in eukaryotic IRES-driven translation initiation.
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  • Date Issued: 2012

Synthesis of triprenylated toluquinone and toluhydroquinone metabolites from a marine-derived Penicillium fungus

  • Authors: Scheepers, Brent Ashley
  • Date: 2007
  • Subjects: Penicillium , Antineoplastic agents , Marine fungi , Quinone
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4373 , http://hdl.handle.net/10962/d1005038 , Penicillium , Antineoplastic agents , Marine fungi , Quinone
  • Description: This project forms part of a collaborative effort between the marine natural products chemists at Rhodes University and the medical biochemists at the University of Cape Town’s School of Medicine. Our UCT collaborators tested the cytotoxicity of a group of toluhydroquinones and toluquinones (9-15) against the oesophageal cancer cell line WHCO1 and revealed that the triprenylated toluhydroquinone 11 and it’s oxidised analogue 12 were the most active. This thesis presents an investigation into the role of the polyprenyl side-chain in the cytotoxicity of compound 11 and it’s oxidised analogue 12 by synthesizing and testing the cytotoxicity of simplified analogues of this compound. The synthesis of the two ortho-prenylated toluhydroquinone analogues 5-methyl-2-[(2'E,6'E)-3',7' -dimethyl-2',6'-octadienyl]-1,4-benzenediol (19) and 5-methyl-2-[(2'E,6'E)-3',7',11'-trimethyl-2',6',10'-dodecatrienyl]-1,4-benzenediol (21) and their two ortho-prenylated toluquinone analogues, 5-methyl-2-[(2'E,6'E)-3',7'-dimethyl-2',6'-octadienyl]-2,5-cyclohexadiene-1,4-dione (20) and 5-methyl-2-[(2'E,6'E)-3',7',11'-trimethyl-2',6',10'-dodecatrienyl]-2,5-cyclohexadiene-1,4-dione (22) is described. Our initial attempts to couple geranyl bromide, farnesyl bromide and farnesal to the aromatic precursors m-cresol and 1,4-dimethoxy-2-methylbenzene using directed ortho-prenylation and phenoxide carbon-alkylation were unsuccessful. The four target analogues were eventually synthesized via the initial metal halogen exchange reaction between 1-bromo-2,5-dimethoxy-4-methylbenzene and geranyl bromide/farnesyl bromide using n-BuLi and TMEDA in ditheyl ether at 0 °C to yield 92 and 104 respectively in moderate yield. The demethylation of both compounds preceded smoothly using AgO giving the target analogues 20 and 22 in good yield (approx. 90 %). The reduction of quinones 20 and 22 with sodium dithionite gave 19 and 21 in quantitative yield. The synthesis reported here is the first regioselective synthesis of these compounds. The anti-oesophageal cancer activity of 19-22 and two commercially available non-prenylated analogues 17 and 18 were tested against WHCO1. The conclusion drawn from the anti-oesophageal cancer study was that the polyprenyl side-chain plays a negligable role in the cytotoxicity of compounds such as 11 and 9 against the oesophageal cancer cell line WHCO1.
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  • Date Issued: 2007

Puerulus and early juvenile recruitment of the rock lobster jasus lalandii in relation to the environment at Lüderitz Bay, Namibia

  • Authors: Keulder, Felicia Juanita
  • Date: 2005
  • Subjects: Jasus lalandii , Lobster fisheries -- Namibia , Lobster culture -- Namibia
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5315 , http://hdl.handle.net/10962/d1005160 , Jasus lalandii , Lobster fisheries -- Namibia , Lobster culture -- Namibia
  • Description: A global decline in the lobster fishery has necessitated the growout of wild-caught postlarvae (pueruli) on farms to meet the worlds lobster demand. A limited knowledge on puerulus settlement in the West Coast rock lobster (Jasus lalandii) constitutes a major barrier for J. lalandii culture development in Southern Africa. As an extension of an existing long-term puerulus monitoring program of the Ministry of Fisheries and Marine Resources of Namibia, the present study monitored puerulus recruitment (supply), puerulus condition and juvenile growth of J. lalandii and their relationship with environmental variables on an oyster farm at Lüderitz Bay, Namibia. Implications for lobster aquaculture and fisheries management are discussed. Oyster bags, crates and collectors were sampled daily, weekly and bimonthly, for pueruli and juveniles, respectively, between August 2001 and July 2003 to establish spatialtemporal patterns in their distribution. Animals were transported to the laboratory for morphometric analyses where they were staged as puerulus (Pt = transparent; Pp = pigmented) and juvenile lobsters. The carapace lengths (0.1mm CL) and wet weights (0.01gram) of animals were recorded. Carapace length frequencies were subjected to Modal Progression analysis to identify early juvenile cohorts and calculate their growths. The weight-length ratios calculated and percentage fat content were used as indices of nutritional condition. Seasonal peaks in puerulus and juvenile abundance were estimated using Periodic Regression analysis. The relationships of puerulus and juvenile abundance with respect to sea surface temperature (SST), wind speed-direction, moon phase, swell and tidal range were established using time lag analysis (ADL). Transparent pueruli were randomly distributed on oyster bags and crates, and also between collector sites, suggesting that they have no particular settlement preference for certain areas on these structures (p>0.05; n=150). Pigmented puerulus (p<0.05; n=566) and juveniles (p<0.05; n=3528) preferred structurally complex structures that provided better shelter such as crates, which were more sheltered from sea swells, compared to oyster bags. Among oyster rafts, pigmented puerulus and juveniles preferred occupying the sheltered and centred raft areas, which provided better protection from wave action, compared to exposed raft areas, which were exposed to the incoming swell. Puerulus and juvenile lobster appeared to recolonise adjacent bags and crates, and possibly migrate to the substrate and off the farm due to the disturbance of the habitat during harvesting. The booth crevice collector was more efficient in collecting puerulus possibly due to the high structurally complex habitat and the better shelter they provided compared to the hogshair collector. The occupation of structurally complex habitats by early benthic stages may be related to morphological changes associated with metamorphosis. Puerulus settlement peaked during early spring (August-September) and was related to low sea surface temperatures (12.3°C), strong south winds, and moderate swells in the week preceding settlement. These conditions are synonymous with the “spring upwelling” season of the Lüderitz upwelling cell in the central Benguela current region. Puerulus nutritional condition peaked during this period possibly due to high levels of planktonic food (due to high nutrients from upwelling) that was available to the late stage phyllosoma larvae further offshore. A “good” puerulus settlement year during 2000 was associated with lower than average SST (11.6°C) and strong south winds and was followed by “poor” puerulus settlement years during 2001 and 2002 when higher than average SST were experienced with below average wind speeds experienced during 2001 only. Puerulus of J. lalandii recruited in high numbers into Lüderitz Bay during the new moon, full moon and last quarter moon phases by making use of the increased tides during these phases of the lunar cycle. Peak juvenile abundance during early summer (November-December) lagged by 8 weeks was significantly correlated with peak puerulus abundance. Puerulus size was similar (8.5–9.7mm CL) over the study period. Juvenile cohorts, 9.9-20.6mm CL in size recruited in 2 distinct waves in August 2001-June 2002 and July 2002-February 2003. The 2001/2002 recruits had higher monthly growth increments and better nutritional condition compared to 2002/2003 recruits. Peak frequencies of 2nd moult juveniles (9.9- 10.8mm CL) occurred in September of both recruitment events with nutritional condition being poorest during the 2002/2003 event. The nutritional condition of the settling puerulus did not appear to be related to the subsequent growth of juvenile lobster. These preliminary results suggest that pueruli recruit once a year mainly during late winter/ early spring under conditions typical of coastal upwelling in the Benguela current near Lüderitz. It appears that puerulus settlement is driven by favourable shoreward currents, which help in transporting puerulus to their settlement grounds. Puerulus supply is highly variable between years, which appears to be consistent with a highly variable Benguela environment. The oyster farm supported a substantial standing stock averaging 123 800 lobster per day (range: 22 600-325 300 lobster per day) of which 26 600 were puerulus and 97 200 were juveniles, that may have been harvested once off on any given day during the sample period. Monthly harvesting of the total lobster standing stock during the one and a half year sampling period was just over 2 million lobsters (505 700 pueruli and 1.85 million juveniles) and would potentially have been sufficient seed for a 200 ton lobster production in puerulus lobster growout facilities. In the light of high inter-annual variation in puerulus settlement observed at Lüderitz, the seed supply at the Lüderitz oyster farm is clearly limited and therefore it is prudent that other sites of high puerulus settlement is established before large commercial scale lobster growout can commence. The migration of lobster off the farm suggested that these lobsters potentially recruit to the fishery and therefore harvesting the entire standing stock on the farm may have adverse negative effects on the wild fishery. A policy decision will be required as to whether more efficient harvesting of lobster from the farm should be allowed. If puerulus removal in J. lalandii for aquaculture is allowed in the near future, it should be conducted on an experimental scale or small commercial scale until the potential effects on recruitment into the fishery are clearer.
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  • Date Issued: 2005

An assessment of the South African east coast linefishery from Kei Mouth to Stil Bay

  • Authors: Brouwer, Stephen Leonard
  • Date: 1998
  • Subjects: Fisheries -- Research -- South Africa , Fisheries -- Environmental aspects -- Research -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5233 , http://hdl.handle.net/10962/d1005076 , Fisheries -- Research -- South Africa , Fisheries -- Environmental aspects -- Research -- South Africa
  • Description: During the period April 1994 and February 1996 as part of an investigation into the national Iinefishery, the east coast shore fishery and the recreational and commercial ski-boat fisheries were surveyed, at eight sites between Kei Mouth in the East and Stil Bay in the West. Roving creel, access point and aerial surveys were used. A questionnaire was developed for each sector to gather data on catch and effort, fisher demographics, economics, fisher attitudes towards, and knowledge of, the current management regulations and assess the efficacy of the fisheries inspectorate. During the access point survey the catch of 3273 fishers was inspected and 1556 interviews were conducted. Questionnaires were conducted on 118 recreational ski-boaters and the catch of 165 boats was inspected. 96 commercial skippers were interviewed and 230 had their catch inspected. Three aerial surveys of the entire area were conducted during which a total of 1067 shore fishers were counted giving a shore fisher density of 0.39 fishers.km⁻¹. The majority (99%) of participants in all sectors of the linefishery were male. The greatest number of participants were white, shore fishery 77% recreational ski-boat 98% commercial skiboat 89%, followed by coloured, asian and black people. To a large extent this reflects the income of various racial groups. Most fishers supported the current linefish management plan. However, when tested on their knowledge of the size limits, bag limits and closed seasons of their target species many shore fishers (59%) did not know them and a high proportion of fishers in all sectors had disobeyed at least one of the regulations (shore 50%, recreational ski-boat 70%, commercial ski-boat 56%). When compared to historical data the present catch per unit effort (CPUE) in all sectors has decreased. Most interviewees in the various sectors did not accept responsibility for the decline in CPUE, but attributed it to three principal reasons vis their perceived direct competitors, trawling and pollution. Analysis of the catch revealed that all sectors were multispecies fisheries, with each sector being characterised by a small number of target species. Catch composition differed significantly between the shore and ski-boat sectors, but there was significant overlap between the two skiboat sectors. Analysis of the catch in comparison to that reported to the National Marine Linefish System (NMLS) revealed that there was a substantial degree of under-reporting. There was little seasonal difference in effort in the shore fishery while the recreational ski-boat effort was highest in the summer and the commercial ski-boat effort was high in the winter. Effort in the shore and recreational ski-boat fisheries was concentrated over weekends while the commercial ski-boat effort was highest during weekdays. Total effort for the entire area was estimated at 903 186 (±1913) fisher days per annum in the shore fishery, 24 357 (±685) recreational ski-boat fisher days and 64 266 (±1686) commercial ski-boat fisher days. Expenditure and capital investment in the various sectors was calculated, as were earnings of the participants in the commercial ski-boat sector. The linefishery in the Eastern Cape was estimated to have a minimum capital investment in excess of R210 million and more than R32 million is spent annually on running costs. The commercial ski-boat fishery directly employed an estimated 3184 people. The economic implications of changes in CPUE for the commercial ski-boat fishery are considered, as are the benefits of a recreational angling licence. Management of the linefishery is discussed in relation to the findings of this study.
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  • Date Issued: 1998

Aspects of the ecology and reproductive biology of three cichlid fish species of Southern Lake Malombe (Malawi)

  • Authors: Jambo, Collins Mayeso
  • Date: 1998
  • Subjects: Cichlids -- Africa, East -- Lake Malombe , Cichlids -- Ecology
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5224 , http://hdl.handle.net/10962/d1005067 , Cichlids -- Africa, East -- Lake Malombe , Cichlids -- Ecology
  • Description: The three major species Lethrinops ''pinkhead'', Otopharynx argyrosoma "red" and Copadichromis. cf virginalis which used to dominate the catches (by weight) of Lake Malombe in the past decade were investigated. In order to make rational recommendations regarding size and boundary of the existing sanctuary area (lightly fished), distribution and abundance, population structure and reproductive biology of the three species were related to habitat types of the southern part of the lake (south western side and south eastern side). Analysis of catch composition showed that species richness was higher in the south eastern side than in the south western side of the lake. Rare species such as Labeo mesops and Opsaridium microiepis were observed in the south eastern side and there was visual absence of such species in the south western side of the lake. The overall fish abundance was significantly greater in the south eastern side than in the south western side of the lake. In the south eastern side, the catch per unit effort (CPUE) was twice that of the south western side (P< 0.05). Seasonal fluctuations in CPUE were also prominent, with the highest peak occurring during September-October period. However, there was an indication of weak relationship among CPUE, phytoplankton biomass, temperature and water depth. The length-weight relationships revealed that growth of the three species closely followed the cubic law for isometric growth in both sides of the lake. Differences in regression coefficients between sides were not significant (ttest, P>0.05). The length-frequency distribution analysis revealed that the three species had the same growth rate regardless of habitat type. However, females grew faster than males. An investigation of reproductive biology showed that the three species have low fecundity and they are asynchronous spawners, with a breeding peak during August and September period. Furthermore, the length-fecundity relationships for L. ''pinkhead'', and 0. argyrosoma "red" indicated that fecundity was more closely related to length in the south eastern side than in the south western side. Based on the above characteristics of L. ''pinkhead'', 0. argyrosoma "red" and C. cf virginalis, and the substrate types, it was strongly suggested that the existing sanctuary (lightly fished) in the south eastern side of the lake could immediately be enlarged to conserve the fish stocks, favourable substratum and aquatic animals that may be of tourists concern.
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  • Date Issued: 1998

The influence of geological, genetic and economic factors on the ore reserve estimation of Kwaggashoek east iron ore deposit

  • Authors: Latorre-Muzzio, Gina
  • Date: 1993
  • Subjects: Iron ores -- Geology -- South Africa , Geology -- South Africa -- Transvaal
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4972 , http://hdl.handle.net/10962/d1005584 , Iron ores -- Geology -- South Africa , Geology -- South Africa -- Transvaal
  • Description: Tectonics plays an important role in the genesis and subsequent mlnlng development of the Kwaggashoek East ore body. Lithological key units control the effectiveness of the ore forming processes, affecting the in situ ore reserve, The Kwaggashoek East deposit is the product of primary and secondary processes. A genetic model focussed on the source, migration and deposition of iron suggests a possible original source of iron as the product of very dilute hydrothermal input into deep ocean waters, with subsequent migration through structural conduits. Supergene processes account for the upgrading of the ore and the phosphorus redistribution. A good correlation between samples in a preliminary geostatistical study reflects the effectiveness of this process in the high grade ore zone. A broad overview of the economic issues which affect the commercialization of iron, indicates a balanced supply-demand situation for the five next years. The reserve estimation procedure requires accurate scientific terminology and appropriate methodology. Documentation is essential and should be detailed enough to allow for future reassessment. The results of three estimation methods in Kwaggashoek East differ by less than 5%. The accuracy of the final results depends more on geological interpretation and assumptions than on the method applied. Although optimization of grade and tonnage in the Kwaggashoek East deposit seems to be met with the actual cut-off grade used in the Thabazimbi mine district, the grade-quality concept introduced in this thesis indicates a decrease in the estimated reserves for the deposit
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  • Date Issued: 1993

Initial findings of an investigation into the feasibility of a low level image processing workstation using transputers

  • Authors: Cooke, Nicholas Duncan
  • Date: 1990 , 2013-02-07
  • Subjects: Image processing , Computer graphics , Fourier transformations -- Data processing , Transputers
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4679 , http://hdl.handle.net/10962/d1006702 , Image processing , Computer graphics , Fourier transformations -- Data processing , Transputers
  • Description: From Introduction: The research concentrates primarily on a feasibility study involving the setting up of an image processing workstation. As broad as this statement concerning the workstation may seem, there are several factors limiting the extent of the research. This project is not concerned with the design and implementation of a fully-fledged image processing workstation. Rather, it concerns an initial feasibility study of such a workstation, centered on the theme image processing aided by the parallel processing paradigm. In looking at the hardware available for the project, in the context of an image processing environment, a large amount of initial investigation was required prior to that concerned with the transputer and parallel processing. Work was done on the capturing and displaying of images. This formed a vital part of the project. Furthermore, considering that a new architecture was being used as the work horse within a conventional host architecture, the INTEL 80286, several aspects of the host architecture had also to be investigated. These included the actual processing capabilities of the host, the capturing and storing of the images on the host, and most importantly, the interface between the host and the transputer [C0089]. Benchmarking was important in order for good conclusions to be drawn about the viability of the two types of hardware used, both individually and together. On the subject of the transputer as the workhorse, there were several areas whlch required investigation. Initial work had to cover the choice of network topology on whlch the benchmarking of some of the image processing applications were performed. Research into this was based on the previous work of several authors, whlch introduced features relevant to this investigation. The network used for this investigation was chosen to be generally applicable to a broad spectrum of applications in image processing. It was not chosen for its applicability for a single dedicated application, as has been the case for much of the past research performed in image processing [SAN88] [SCH89]. The concept of image processing techniques being implemented on the transputer required careful consideration in respect of what should be implemented. Image processing is not a new subject, and it encompasses a large spectrum of applications. The transputer, with image processing being hlghly suited to it, has attracted a good deal of research. It would not be rash to say that the easy research was covered first. The more trivial operations in image processing, requiring matrix type operations on the pixels attracted, the most coverage. Several researchers in the field of image processing on the transputer have broken the back of this set of problems. Conclusions regarding these operations on the transputer returned a fairly standard answer. An area of image processing which has not produced the same volume of return as that concerning the more trivial operations, is the subject of Fourier Analysis, that is, the Fourier Transform. Thus a major part of this project concerns an investigation into the Fourier Transform in image processing, in particular the Fast Fourier Transform. The network chosen for thls research has placed some constraint upon the degree of parallelism that can be achleved. It should be emphasized that this project is not concerned with the most efficient implementation of a specific image processing algorithm on a dedicated topology. Rather, it looks at the feasibility of a general system in the domain of image processing, concerned with a hlghly computationally intensive operation. This has had the effect of testing the processing power of the hardware used, and contributing a widely applicable parallel algorithm for use in Fourier Analysis. 3 These are discussed more fully in Chapter 2, which covers the work related to tbis project. The results of the investigation are presented along with a discussion of the methods throughout the thesis. The final chapter summarizes the findings of the research, assesses the value of the investigation, and points out areas for future investigation.
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  • Date Issued: 1990

Bacterial degradation of ixodicide amitraz

  • Authors: Allcock, Errol Ralph
  • Date: 1978
  • Subjects: Ticks -- Control , Pesticides -- Biodegradation , Acaricides
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4081 , http://hdl.handle.net/10962/d1007473 , Ticks -- Control , Pesticides -- Biodegradation , Acaricides
  • Description: The control of ticks on cattle has long been a matter of prime importance to stock owners over most of the intensive natural grazing areas in the Southern Hemisphere. The only practical method of dealing with the cattle tick problem in the short term is by treating the infected bovine host with ixodicides i. e. by chemical control. This can be achieved by either plunging the cattle into a dip tank containing aqueous suspensions or emulsions of the ixodicide or by spraying them with dip suspensions in a spray race.
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  • Date Issued: 1978
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