List of Titles

Quick View

A Legacy Adapter Component of a 1394-Based Professional Studio Architecture

- Foss, Richard, Moses, Bob, Laubscher, Rob

Authors: Foss, Richard , Moses, Bob , Laubscher, Rob
Date: 2001
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/427362 , vital:72433 , https://www.aes.org/e-lib/browse.cfm?elib=9853
Description: Digital Harmony Studio is a specification for an IEEE-1394-based studio architecture for professional audio production. The specification identifies a number of device categories, including legacy adapters. Legacy adapters provide a vital link between the pro studio environments and current pro audio devices, and will typically take the form of breakout boxes exposing legacy ports. This paper describes a reference design for the first working device within the 'Legacy Adapter' category of the specification.
Full Text:
Date Issued: 2001

Quick View

A sensitive and reliable method for the detection of lipid peroxidation in biological tissues

- Anoopkumar-Dukie, Shailendra, Walker, Roderick B, Daya, Santylal

Authors: Anoopkumar-Dukie, Shailendra , Walker, Roderick B , Daya, Santylal
Date: 2001
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/184325 , vital:44208 , xlink:href="https://doi.org/10.1211/0022357011775299"
Description: A simple, accurate and cost effective method has been designed for the determination of lipid peroxidation in biological tissue samples. The method was a modification and improvement on existing methods available for lipid peroxidation determination. Solid-phase extraction was used to separate the thiobarbituric acid–malondialdehyde complex from thiobarbituric acidreactive substances and HPLC was performed using a C18 (Waters Spherisorb, 5 µm, 250¬4.6 mm i.d.) column to achieve isolation of the complex. The procedure was validated with respect to linearity of calibration (0.998), precision, sensitivity and limits of quantitation (1 nmol mL−1) and detection (0.5 nmol mL−1). Resorcinol was used as an external standard. The method was tested by inducing free radical generation with a known free radical generator, quinolinic acid, in rat brain homogenate. The results showed that the method presented allowed detection of lipid peroxidation products at concentrations in the nanomolar (nM) range compared with the micromolar (µM) range detected by other methods, thus rendering it suitable for use with biological samples. In addition, the modified method allowed for detection of the purified lipid peroxidation products, thus eliminating the possibility of simultaneous detection of impurities that absorb at the same wavelength.
Full Text:
Date Issued: 2001

Quick View

Active learning in schools

- Lotz-Sisitka, Heila, Timmermans, Ingrid

Authors: Lotz-Sisitka, Heila , Timmermans, Ingrid
Date: 2001
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/389696 , vital:68475 , xlink:href="https://eeasa.org.za/wp-content/uploads/2016/12/Bulletin_vol21-_Sep-2001.pdf"
Description: The Rhodes University Environmental Education Unit has initiated a project to support school-based environmental education work in Grahamstown. In line with national environmental education policy, the project supports a focus on environmental learning in the context of the OBE curriculum, and provides professional development support to teachers implementing the project (NEEP, 2000). An action research evaluation is taking place to monitor key aspects of the project and a number of interim evaluation reports have been produced (Mbanjwa, 2001).
Full Text:
Date Issued: 2001

Quick View

An inventory of medicinal plants traded on the western boundary of the Kruger National Park, South Africa

- Botha, Jenny, Witkowski, Ed T F, Shackleton, Charlie M

Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
Date: 2001
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/181662 , vital:43756 , xlink:href="https://doi.org/10.4102/koedoe.v44i2.172"
Description: The World Health Organisation estimates that traditional medicine still plays a vital role in the lives of 70-80 of the populations of developing countries. Approximately 20 000 tons of medicinal plants are estimated to be traded in South Africa annually, resulting in considerable pressure on the wild populations from which these plants are harvested. In 1997, a study was initiated to assess the extent of trade in medicinal plants on the western boundary of the Kruger National Park, and to determine local perceptions of the availability and values of these plants. This paper presents an inventory of the species traded, including vendors' and traders' perceptions of current availability of species and consumer demand, as well as price/kg. In Mpumalanga, 176 species were identified (71 of the vernacular names encountered in the market place), representing 69 families. In Northern Province, 70 different species were identified (84 of the vernacular names recorded in the markets), representing 40 families. Perceptions of availability of a species varied considerably, often within the same markets. Perceptions of demand tended to be more consistent, although these also sometimes varied. Although monitoring markets is an efficient means of assessing the conservation status of medicinal plants, it is important to select appropriate parameters. Markets often differ from one another, and an understanding of local conditions is crucial. For example, in the medicinal markets on the western boundary of the Kruger National Park, price/kg and market perceptions of availability of species were highly variable and would thus not provide a consistent monitoring parameter. Perceptions of demand provide an indication of current and potential pressure on a species, particularly when combined with the monitoring of species traded, and the introduction of substitutes in the market place. The size of plant parts traded could also provide useful monitoring data. It is important to identify the plants utilised locally first hand where possible, due to the variation of vernacular names from one area to another.
Full Text:
Date Issued: 2001

Quick View

Behavioural interactions of predators and spawning chokka squid off South Africa: towards quantification

- Smale, Malcolm J, Sauer, Warwick H H, Roberts, M

Authors: Smale, Malcolm J , Sauer, Warwick H H , Roberts, M
Date: 2001
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/123921 , vital:35516 , https://doi.10.1007/s002270100664
Description: The interaction of a suite of predators with mating and spawning chokka squid (Loligo vulgaris reynaudii) was studied at inshore (<50 m) spawning grounds off South Africa. This study provides the first detailed records of predator–prey interactions of squids on their spawning grounds and is the first attempt to time disruptions caused by predators to the egg-laying behaviour of squids, thereby quantifying the perceived threat to the prey. The squids are focused on mate choice and reproduction while they aggregate over egg beds and they may be more vulnerable to predation than at other times. Their vulnerability to different predators in the field is examined and the tactics used against different predatory species are illustrated using recordings made with underwater video cameras. Predators recorded included two cephalopods (Octopus vulgaris and L. v. reynaudii), five teleosts (Pagellus bellotii natalensis, Spondyliosoma emarginatum, Pachymetopon aeneum, Cheimerius nufar and Pomatomus saltatrix), seven chondrichthyians (Squalus megalops, Mustelus mustelus, Carcharias taurus, Dasyatis brevicaudata, Gymnura natalensis, Poroderma africanum and P. pantherinum) and three marine mammals (Arctocephalus puscillus, Tursiops aduncus and Delphinus delphis). Analysis of behavioural interactions between predators and prey showed that predator disruption of egg laying may be quantified in terms of time. Marine mammals caused the most acute disruption, whereas other taxa had more chronic disruption effects because they spent more time on the spawning grounds. During November 1995, the suite of predators changed during the course of a 2-day period of underwater video recording, possibly because of an increase in water temperature. The hypothesis that predators would be concentrated around a spawning aggregation was tested by surveying the spawning ground using an underwater camera towed by a boat navigating with differential GPS. The results supported the hypothesis because predators were located only around the spawning sites. The serial spawning of chokka squids in recently upwelled water may reduce predation pressure. Furthermore, it may be difficult for predators to predict the specific spawning site on a particular day because squids disperse away from egg beds at night and use numerous spawning sites along the coast.
Full Text:
Date Issued: 2001

Quick View

Challenges facing a community structure to implement CBNRM in the Eastern Cape, South Africa:

- Cocks, Michelle L, Dold, Anthony P, Grundy, Isla

Authors: Cocks, Michelle L , Dold, Anthony P , Grundy, Isla
Date: 2001
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/141416 , vital:37970 , http://asq.africa.ufl.edu/files/Cocks-Dold-Grundy-Vol-5-Issue-3.pdf
Description: In most developing countries, community based natural resource management (CBNRM) initiatives have been adopted in an attempt to address the issue of environmental sustainability. This has largely come about due to an increasing recognition of the ineffectiveness of the state to achieve such sustainability. Within the South African context, recent policies have been drafted that aim to achieve these outcomes, which strongly articulate the need for the participation of local people in the management of natural resources both within communal areas and on state-owned land. The objectives of new policies, however, are not being met in the Eastern Cape of South Africa for the following key reasons: the insufficient recognition of the impact of past historical and political upheavals experienced within the former homelands’ situation; the government’s inability to process land applications; the government’s lack of ability and capacity to implement these policies; and frustratingly high levels of hierarchy at both the local and national level. The Masakane community, a group of former farm workers from the former Ciskei homeland in South Africa, are attempting to implement CBNRM initiatives. The Masakane case study reveals the urgent need to develop, implement and enforce new institutional and managerial arrangements, because without such arrangements state policies are unlikely to be implemented at the grassroots level.
Full Text:
Date Issued: 2001

Quick View

Comparative photosensitised transformation of polychlorophenols with different sulphonated metallophthalocyanine complexes in aqueous medium

- Ozoemena, Kenneth, Kuznetsova, Nina, Nyokong, Tebello

Authors: Ozoemena, Kenneth , Kuznetsova, Nina , Nyokong, Tebello
Date: 2001
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/291520 , vital:56883 , xlink:href="https://doi.org/10.1016/S1381-1169(01)00243-6"
Description: The relative efficiencies for the oxidation of trichlorophenol (TCP) and pentachlorophenol (PCP), sensitised by sulphonated phthalocyanine complexes containing Zn, Al, Sn and Si as central metals, were studied in aqueous solutions. For the first time, sulphonated silicon and tin phthalocyanines were synthesised and their activity towards photosensitisation of singlet oxygen and photo-oxidation of polychlorophenols was examined. The efficiency of the sensitised photo-oxidative degradation of polychlorophenols depends not only on singlet oxygen quantum yield of sensitiser, but also on its stability. The influence of substrate structure and the pH of the solution on the photo-oxidation efficiency, as well as on the sensitiser photodegradation were studied. It was found that the contribution of the Type II (singlet oxygen-mediated) mechanism to the relative efficiency of the photosensitised photo-oxidation of the phenol, decreased from phenol to p-chlorophenol, TCP and PCP, whereas Type I radical pathway increased. The results obtained for PCP give evidence that electron transfer from the excited sensitiser to the substrate in its unionised form is responsible for enhanced sensitiser photodegradation.
Full Text:
Date Issued: 2001

Quick View

Construction and characterization of carbon paste ultra-microelectrodes

- Oni, Joshua, Westbroek, Philippe, Nyokong, Tebello

Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
Date: 2001
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/291531 , vital:56884 , xlink:href="https://doi.org/10.1016/S1388-2481(01)00212-0"
Description: The construction and characterization of carbon paste ultra-microelectrodes is reported. Besides a disc-shaped electrode, a carbon paste band electrode is studied. It was found that for both electrode configurations steady-state currents were obtained but that with the type of electrode material used for the band electrode, the upper limit of ultra-microelectrode dimensions, which could be used was 100–150 μm. Smaller dimensions for the band electrodes resulted in a high resistance due to the limited conductivity of the carbon paste, when using the optimal paste composition. With cyclic voltammetry, the oxidation of [Fe(CN)6]4− was studied at individual constructed electrodes and at ensembles of individual electrodes. Detection limits of less than 10−6moll−1 were obtained. Using the data of the same curves it was possible to test if the electrodes have errors and about 20% of the constructed electrodes did not pass this test. Finally it was found that these electrodes show good stability.
Full Text:
Date Issued: 2001

Quick View

Effect of oligomerization on the photochemical properties of silicon octaphenoxyphthalocyanine

- Maree, M David, Nyokong, Tebello

Authors: Maree, M David , Nyokong, Tebello
Date: 2001
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/291542 , vital:56885 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00485-3"
Description: The photochemical properties of silicon octaphenoxyphthalocyanines (SiOPPc) oligomerized were studied in dimethylsulfoxide (DMSO) solutions. Oligomers containing 2–5 and 9 SiOPPc rings linked with terephthalate linkages were synthesized. Singlet oxygen quantum yields were found to be in the range 0.11–0.34, and increased with the number of rings up to five rings, a decrease in the quantum yield was observed for nine rings. This is explained in terms of the high aggregation of the oligomer containing nine rings.
Full Text:
Date Issued: 2001

Quick View

Electrooxidation of cresols on carbon electrodes modified with phthalocyaninato and octabutoxyphthalocyaninato cobalt (II) complexes

- Grootboom, Natasha, Nyokong, Tebello

Authors: Grootboom, Natasha , Nyokong, Tebello
Date: 2001
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/293207 , vital:57065 , xlink:href="https://doi.org/10.1016/S0003-2670(00)01351-9"
Description: Glassy carbon electrodes (GCE) modified with cobalt(II) phthalocyanine (CoPc-GCE) and cobalt(II) octabutoxyphthalocyanine (CoOBuPc-GCE) were employed for the electrochemical analysis of ortho-, meta-, and para-cresols. The oxidation potential of p-cresol was shifted towards less positive values to a larger extent, when compared to m- and o-cresols, on CoOBuPc-GCE. However, the GCE was less stable when modified with CoOBuPc than with CoPc. This is explained using the possible differences in the orientation of the adsorbed phthalocyanine molecules on the electrode. Bulk electrolysis of p-cresol at anodic potentials (1.0 V versus Ag|AgCl) on carbon electrodes modified with CoPc resulted in the formation of radicals which coupled to form trimeric products. On unmodified carbon electrodes, coupling of the radicals resulted in dimeric products following bulk electrolysis. The products formed following bulk electrolysis were characterized by liquid chromatography coupled with mass spectrometry.
Full Text:
Date Issued: 2001

Quick View

Experiences in porting a virtual reality system to Java

- Bangay, Shaun D

Authors: Bangay, Shaun D
Date: 2001
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/433157 , vital:72947 , https://doi.org/10.1145/513867.513875
Description: Practical experience in porting a large virtual reality system from C/C++ to Java indicates that porting this type of real-time application is both feasible, and has several merits. The ability to transfer objects in space and time allows useful facilities such as distributed agent support and persistence to be added. Reflection and type comparisons allow flexible manipulations of objects of different types at run-time. Native calls and native code compilation reduce or remove the overhead of interpreting code.Problems encountered include difficulty in achieving cross-platform code portability, limitations of the networking libraries in Java, and clumsy coding practices forced by the language.
Full Text:
Date Issued: 2001

Quick View

Factors Influencing the Entrepreneurial Orientation of Students

- Amos, Trevor L, Louw, L, Baxter, Jeremy

Authors: Amos, Trevor L , Louw, L , Baxter, Jeremy
Date: 2001
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/270879 , vital:54488 , xlink:href="https://scialert.net/abstract/?doi=jas.2001.329.334"
Description: With entrepreneurship being an important catalyst in wealth creation, it is imperative that entrepreneurs be developed. The aim of this exploratory research is to contribute to our understanding of the development of entrepreneurs and to encourage further research in the area. This paper proposes a model of entrepreneurship and tests the influencing factors on this model. Based on the findings of this research, it appears that entrepreneurial activity of family members influences the development of entrepreneurship more than gender, race, age or education. With education being a logical site for the development of entrepreneurship within society, this finding raises more questions than it provides answers, highlighting the need for educators to critically review the educational process if entrepreneurship is to be a realistic outcome.
Full Text:
Date Issued: 2001

Quick View

Implementation and applications of the distortion operator

- Bangay, Shaun D

Authors: Bangay, Shaun D
Date: 2001
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/433382 , vital:72966 , https://doi.org/10.1145/513867.513872
Description: The distortion operator transforms 2D images in a manner similar to image warping or morphing, allowing source pixels to be mapped to any destination pixel. This operator can be implemented on current hardware, allowing at least one distortion per frame at interactive frame rates. Potential applications are numerous, but those described include re-mapping images for correct projection onto curved screens, correcting camera distortion from multiple sources simultaneously, and allowing constant time dynamic texturing and lighting of a static scene which is independent of geometric complexity.
Full Text:
Date Issued: 2001

Quick View

Interaction of serotonin and melatonin with sodium, potassium, calcium, lithium and aluminium

- Lack, Barbara, Daya, Santy, Nyokong, Tebello

Authors: Lack, Barbara , Daya, Santy , Nyokong, Tebello
Date: 2001
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/291553 , vital:56886 , xlink:href="https://doi.org/10.1034/j.1600-079x.2001.310202.x"
Description: In the present study, we investigated the ability of serotonin and melatonin to bind metals that occur naturally in the brain. An electrochemical technique called adsorptive cathodic stripping voltammetry (AdCSV) was employed to study the metal–serotonin or metal–melatonin interactions. The results show that both serotonin and melatonin form stable complexes with lithium and potassium, with serotonin favouring lithium over potassium, and melatonin favouring potassium over lithium. Coordination between either serotonin or melatonin and calcium was not favoured. The stability of the complexes formed between serotonin and the metals decreased with the metals as follows: Li+>K+>Al3+>Na+>Ca2+. The trend for melatonin–metal complexes was K+>Li+>Na+>Al3+>Ca2+. The binding and stable complex formation between both ligands, serotonin and melatonin with lithium, potassium and sodium is of biological importance. The binding of serotonin to lithium could provide an explanation for the therapeutic effects of lithium in depression treatment, whereas the binding of aluminium by melatonin could provide insight into the role of this element in the aetiology of Alzheimer's disease.
Full Text:
Date Issued: 2001

Quick View

Showing items 3301 - 3320 of 3516