Browsing by Issue Date
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Jeffries, Michael; Tucker, William D. (Telkom, 2001)[more][less]
Abstract: The Session Initiation Protocol and H.323 dominate the Voice over IP world. These signaling protocols are responsible for call setup and call tear down by IP telephony solutions. This project analyses and discusses the underlying H.323 and SIP interoperability issues and intends to build a scalable solution for the interoperability of these protocols. The gateway maps the call sequences between the two protocols. A test scenario establishes a barrage of call setup and tear down requests to test the scalability of any H.323/SIP interoperability solution. URI: http://hdl.handle.net/10566/465 Files in this item: 1
JeffriesTuckerSIP2001.pdf (65.32Kb) -
Brierley, Andrew S.; Axelson, Bjorn Erik; Buecher, Emmanuelle; Sparks, Conrad A.J.; Boyer, Helen; Gibbons, Mark J. (Inter-Research, 2001)[more][less]
Abstract: Multi-frequency acoustic data (18, 38 and 120 kHz) were collected in conjunction with pelagic trawl sampling for gelatinous macrozooplankton during a cruise to the Namibian Benguela in September 1999. Sampling focused specifically on the scyphozoan Chrysaora hysoscella and the hydrozoan Aequorea aequorea, both of which occur in large numbers, are probably of major ecological importance, and physically hamper pelagic fishing and diamond extraction activities. C. hysoscella was detected predominantly at an inshore station and A. aequorea was found in greatest abundance further offshore in deeper water. Echo-sounder observations were linked directly to net catches, and relationships between catch density (number of individuals m–3) and nautical area scattering coefficients (sA) at each frequency were determined for both species in order to estimate target strength (TS) using the comparison method. TS for C. hysoscella (mean umbrella diameter 26.8 cm) was –51.5 dB at 18 kHz, –46.6 dB at 38 kHz and –50.1 dB at 120 kHz; for A. aequorea (mean central umbrella diameter 7.4 cm) TS was –68.1 dB at 18 kHz, –66.3 dB at 38 kHz and –68.5 dB at 120 kHz. These TS values compared favourably with previously published estimates for related species. Jellyfish were caught at high numerical densities (maxima 3 C. hysoscella per 100 m3, 168 A. aequorea per 100 m3). These high densities, combined with the not unsubstantial TS at frequencies used for fisheries surveys, imply that jellyfish could potentially bias acoustic estimates of fish abundance. We suggest a simple multifrequency approach that could be used to discriminate between echoes from jellyfish and some commercially important pelagic fish in the northern Benguela ecosystem. URI: http://hdl.handle.net/10566/246 Files in this item: 1
BrierleyAcoustic 2001.pdf (799.2Kb) -
Bock, Zannie; Gough, David H. (Routledge, 2001)[more][less]
Abstract: The question of the 'great divide' between orality and literacy has been critically addressed by various scholars of literacy, including social literacy theorists. This paper uses the notions of primary and secondary discourse across both oral and literate contexts to examine this 'divide'. Using evidence from the oral tradition of the Xhosa, it is shown that 'traditional' societies have well-established primary and secondary discourse types. Against this understanding, the issue of 'access' to Western academic literacy is examined. It is argued that within the changing context of South African society and as a direct result of former apartheid policies, individuals may have failed to acquire the cultural capital of both oral secondary and literate secondary discourse types. The literate secondary discourse practices of Xhosa-speaking students at univer¬sity are explored through an analysis of student writing. This paper then reports on several projects which attempt to address some of the concerns of academic staff with respect to student writing. In particular, this section argues for a broadening of the notion of 'academic literacy' and suggests some ways in which texts derived from the oral tradition may be used to develop awareness of secondary discourse types. URI: http://hdl.handle.net/10566/266 Files in this item: 1
Bock_Perspectives2001.pdf (637.5Kb) -
du Toit, Francois (Juta, 2001)[more][less]
Abstract: This article analyses critically the impact of constitutionalism on freedom of testation and its limitation in South African law. It proposes the judicial utilisation of a 'constitutionally-founded boni mores criterion' in addressing particularly testamentary forfeiture clauses and charitable testamentary bequests. URI: http://hdl.handle.net/10566/230 Files in this item: 1
Stell LR 2001.pdf (18.56Mb) -
Kerfoot, Caroline; Geidt, Jonathan; Alexander, Lucy; Dayile, Nomvuyo; Groener, Zelda; Hendriks, Natheem; Walters, Shirley (Centre for Continuing and Adult Education (CACE), University of the Western Cape, 2001)[more][less]
Abstract: This study presents the results of an investigation into the impact of CACE courses for adult educators, trainers and development practitioners. The report describes how the courses affected the training practices and lives of past students. Case studies document and analyse the problems and successes of implementing capacity-building ABET training in the Northern Cape. URI: http://hdl.handle.net/10566/216 Files in this item: 1
KerfootABET2001.pdf (923.6Kb) -
Penton, Jason; Tucker, William D.; Glaser, Meryl (Telkom, 2002)[more][less]
Abstract: We have developed a prototype bridge that relays text and speech between Teldem, a text telephone for the Deaf, and a standard telephone or H.323 endpoint. Telgo323 uses modified H.323 media gateways and open source Text to Speech and Speech to Text software. The approach allows for easy integration of new tools as the technologies mature. This paper presents the design of the implementation prototype, discusses Teldem tone decoding, and suggests directions for future work. The Telgo323 provides evidence that an automated relay bridge is imminently viable for the Deaf Community, and further demonstrates an attractive approach for building bridges over the Digital Divide. URI: http://hdl.handle.net/10566/612 Files in this item: 1
PentonTuckerGlaser-SATNAC2002.pdf (99.60Kb) -
Lewis, John; Tucker, William D.; Blake, Edwin H. (Telkom, 2002)[more][less]
Abstract: Users and computing equipment have varying capabilities that include the abilities to exchange text and audio, engage in high bandwidth communication, etc. As the technological options increase, e ective communication between the di erent media has be able to bridge across these options: the bridges have to take into account network quality, end-user equipment capabilities as well as user preferences and capabilities. Our research proposes a Soft- Bridge, an abstracted communications platform for the construction of applications across disparate capabilities found in various Digital Divides. We outline the architecture and the requirements that the SoftBridge has to ful ll. An approach and some initial work is described. URI: http://hdl.handle.net/10566/606 Files in this item: 1
LewisTuckerBlake-SATNAC2002.pdf (126.3Kb) -
Hart, Genevieve (Bibliotek I Samhalle (BIS), 2002)[more][less]
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Ravjee, Neetha (UNISA, 2002)[more][less]
Abstract: This article investigates the tensions in the "mode 2" thesis, which suggests the emergence of new, global trends in the production and dissemination of knowledge. I explain its influence in recent South African higher education policy debates and research practices by referring to competing readings of "mode 2", which have allowed it to feed simultaneously into both liberal and critical discourses on higher education transformation in South Africa. Clear tensions emerge from the limitations of "mode 2" in speaking to existing inequalities and in informing non-corporate models of institutional transformation. URI: http://hdl.handle.net/10566/414 Files in this item: 1
RavjeeKnowledgeProduction2002.pdf (175.5Kb) -
Bock, Zannie; Dadlana, Phakamani (University of Stellenbosch, 2002)[more][less]
Abstract: This article aims to characterize typical linguistic and discourse features of academic writing in Xhosa and English among prospective Xhosa-speaking students at the University of the Western Cape so as to account for strengths and weaknesses in the writing and provide possible ‘points’ for pedagogic intervention. It presents an analysis of a sample of entrance essays written by these students in English and Xhosa. The analysis is in terms of a framework which considers aspects of argument, register and syntax. It aims to highlight strengths and weaknesses in student writing and to ascertain the extent to which these characteristics are language-specific or cross-linguistic. The results of the analysis suggest that the ability to argue coherently in an appropriate register is the defining mark of good writing in any language, and that control over the syntax of the language is particularly important for these students when writing in English. The ability to write well, like certain aspects of style, seems to be a generic ability and affects students’ performance in both languages. URI: http://dx.doi.org /10.5785/18-1-8 Files in this item: 1
Bock_cross-linguistic2002.pdf (243.5Kb) -
Burton, Stephanie; Cowan, Donald A.; Woodley, John M. (Nature Publishing Group, 2002)[more][less]
Abstract: While the use of enzymes as biocatalysts to assist in the industrial manufacture of fine chemicals and pharmaceuticals has enormous potential, application is frequently limited by evolution-led catalyst traits. The advent of designer biocatalysts, produced by informed selection and mutation through recombinant DNA technology, enables production of process-compatible enzymes. However, to fully realize the potential of designer enzymes in industrial applications, it will be necessary to tailor catalyst properties so that they are optimal not only for a given reaction but also in the context of the industrial process in which the enzyme is applied. URI: http://hdl.handle.net/10566/150 Files in this item: 1
BurtonCowanWoodley2002.pdf (768Kb) -
Bustard, Mark T.; Whiting, Samantha; Cowan, Donald A.; Wright, Phillip C. (Springer Verlag, 2002)[more][less]
Abstract: The aerobic biodegradation of high-concentration, to 24 g l –1 , 2-propanol (IPA) by a thermophilic isolate ST3, identified as Bacillus pallidus , was successfully carried out for the first time. This solvent-tolerant B. pallidus utilized IPA as the sole carbon source within a minimal salts medium. Cultivation was carried out in 100-ml shake flasks at 60°C and compared with cultivation within a 1-l stirred tank reactor (STR). Specific growth rate () was about 0.2 h–1 for both systems, with a maximum cell density of 2.4 x 10 8 cells ml–1 obtained with STR cultivation. During exponential growth and stationary phase, IPA biodegradation rates were found to be 0.14 and 0.02 g l –1h–1, respectively, in shake-flask experiments, whereas corresponding values of 0.09 and 0.018 g l –1h–1 were achievable in the STR. Generation of acetone, the major intermediate in aerobic IPA biodegradation, was also monitored as an indicator of microbial IPA utilization. Acetone levels reached a maximum of 2.2–2.3 g l–1 after 72 and 58 h for 100-ml and 1-l systems, respectively. Both IPA and acetone were completely removed from the medium following 160 and 175 h, respectively, during STR growth, although this was not demonstrated within shake-flask reactions. Growth of B. pallidus on acetone or IPA alone demonstrated that the maximum growth rate () obtainable was 0.247 h–1 at 4 g l–1 acetone and 0.202 h–1 at 8 g l–1 IPA within shake-flask cultivation. These results indicate the potential of the solvent-tolerant thermophile B. pallidus ST3 in the bioremediation of hot solvent-containing industrial waste streams. URI: http://hdl.handle.net/10566/154 Files in this item: 1
BustardBiodegradation2002.pdf (453.9Kb) -
Wilkinson, Dianne E.; Jaenicke, Thomas; Cowan, Donald A. (Kluwer Academic Publishers, 2002)[more][less]
Abstract: An efficient and simple method for constructing an environmental library using mechanically sheared DNA obtained directly from geothermal sediments is presented. The method is based on blunt-end modification of DNA fragments followed by 3' -adenylation using Vent DNA polymerase and Taq DNA polymerase, respectively. The prepared DNA fragments are then ligated into a TA cloning vector and used in the transformation of Escherichia coli. This method has been successfully applied to the cloning of ORFs derived from uncultivated prokaryotes present in geothermal sediment. URI: http://hdl.handle.net/10566/161 Files in this item: 1
WilkinsonEfficientMolecular2002.pdf (754.4Kb) -
Cowan, Donald A.; Mamais, A.; Russell, Nick A.; Sheppard, Devon M. (Springer Verlag, 2002)[more][less]
Abstract: We have applied bioluminescent ATP detection methods to microbial enumeration in Antarctic Dry Valley mineral soils, and validated our ATP data by two independent methods. We have demonstrated that ATP measurement is a valid means of determining microbial biomass in such sites, and that the desiccated surface mineral soils of the Antarctic Dry Valleys contain cell numbers over four orders of magnitude higher than previously suggested URI: http://hdl.handle.net/10566/162 Files in this item: 1
CowanAntacticDryValleys2002.pdf (475.3Kb) -
Puoane, Thandi; Steyn, Kristela; Bradshaw, Debbie; Laubscher, Ria; Fourie, Jean; Lambert, Vicki; Mbanangwa, Nolwazi (Nature Publishing Group, 2002)[more][less]
Abstract: To ascertain the anthropometric profile and determinants of obesity in South Africans who participated in the Demographic and Health Survey in 1998. RESEARCH METHODS AND PROCEDURES: A sample of 13,089 men and women (age, _15 years) were randomly selected and then stratified by province and urban and nonurban areas. Height, weight, mid-upper arm circumference, and waist and hip circumference were measured. Body mass index (BMI) was used as an indicator of obesity, and the waist/hip ratio (WHR) was used as an indicator of abdominal obesity. Multivariate regression identified sociodemographic predictors of BMI and waist circumference in the data. RESULTS: Mean BMI values for men and women were 22.9 kg/m2 and 27.1 kg/m2, respectively. For men, 29.2% were overweight or obese (_25 kg/m2) and 9.2% had abdominal obesity (WHR _1.0), whereas 56.6% of women were overweight or obese and 42% had abdominal obesity (WHR _0.85). Underweight (BMI _18.5 kg/m2) was found in 12.2% of men and 5.6% of women. For men, 19% of the variation of BMI and 34% of the variation in waist circumference could be explained by age, level of education, population group, and area of residence. For women, these variables explained 16% of the variation of BMI and 24% of the variation in waist circumference. Obesity increased with age, and higher levels of obesity were found in urban African women. DISCUSSION: Overnutrition is prevalent among adult South Africans, particularly women. Determinants of overnutrition include age, level of education, ethnicity, and area of residence. URI: http://hdl.handle.net/10566/291 Files in this item: 1
PuoaneSurvey2002.pdf (63.15Kb) -
Adesemowo, A. Kayode; Tucker, William D. (Telkom, 2003)[more][less]
Abstract: As mobile devices and networks become more data-centric, text messaging requires an extension of co-presence capabilities for better interactive discussion between input/output handicapped handheld users and their free form desktop counterparts. Given some degree of co-presence (online presence and awareness) in text-based Instant Messaging, we hope to increase this co-presence on a handheld with fast-track feedback (FF) mechanisms. These are user-defined gestures, such as emoticons, and prioritised messages. We are building a system that facilitates gesture input within an interactive text-based chat over a wireless network running Session Initiation Protocol (SIP). The chat bridges a robust desktop environment and a small number of handhelds. This work in progress looks into the SIP Instant Messaging and Presence Leveraging Extensions as a platform to provide fast-track interactive and co-presence feedback. The aim is to rubberise a hitherto plastic and limited instant messaging conversation. We shall measure co-presence levels between FF and standard IM environments in and without desktop and handhelds by engaging two groups of users in chats session. We expect to demonstrate that there exists high co-presence notion in open (work by Sun Research Awarenex Group and AT&T Hubbubme in similar domain were in closed systems) FF text messaging open environment as we would like to show that this higher presence brings a much more enhanced interactive discourse. The envisaged results are intended to extrapolate to online aware co-presence in the up and coming smart phones on 3G packet networks. URI: http://hdl.handle.net/10566/539 Files in this item: 1
AdesemowoTuckerMobileDevices2003.pdf (180.9Kb) -
Benjamin, Anita; Tucker, William D. (Telkom, 2003)[more][less]
Abstract: We have built a hybrid voice/text web–board that utilizes floor control for handling resources such as microphone and interface events. The aim of this research is to determine the most appropriate floor control mechanism for a hybrid communication tool that allows conventional text and audio users to communicate with one another using a common interface. Research on floor control mechanisms provides many implementations for arbitration that are application-specific. Myers proposes a categorical explanation of the most widely used mechanisms for providing floor control and discusses these different dimensions with respect to a project called Pebbles. We have chosen to model our arbitration policies along these categories. The application will be implemented as a Java applet and gives users a view of both the text and audio aspects of the exchange. To facilitate the multi-modality of the system we will provide media conversion, using the Nuance system’s Java API. Our hypothesis is that well–known multi-tasking arbitration protocols such as FCFS, Round Robin, Token – based, and many more can be adapted to create a conferencing floor control policy for the interface of a hybrid communication environment so as to facilitate free–flowing multi-modal conversation. Measurements to determine which floor control implementation provides the best arbitration in terms of user interaction with the system will be calculated using RPT, ORT and usage tests based on the Kirkpatrick Model. We hope to show that users benefit more from an implicit arbitration mechanism than they do from an explicit one. URI: http://hdl.handle.net/10566/538 Files in this item: 1
BenjaminTuckerHybridVoice2003.pdf (123.3Kb) -
Lewis, John; Tucker, William D.; Blake, Edwin H. (Telkom, 2003)[more][less]
Abstract: Instant Messaging is traditionally a text only a air. However, there are instances when it would be useful to bridge to other types of media, like speech. The SoftBridge is an application framework that enables this kind of communications bridging using instant messages. Its use of protocols like the Jabber Instant Messaging Protocol and the Simple Object Access Protocol makes it simple, open and extensible. It also allows bridging to non IP communications infrastructure, like the telephone network. We describe the design and architecture of the system, protocol and extensibility mechanism. Finally we describe our experimental methodology and discuss the results of our initial experiments. URI: http://hdl.handle.net/10566/537 Files in this item: 1
LewisTuckerBlakeInstantMessaging2003.pdf (202.4Kb) -
Tucker, William D.; Glaser, Meryl; Lewis, John (Telkom, 2003)[more][less]
Abstract: Following on several partial prototypes, we built an automated Deaf Telephony bridging application with the SoftBridge platform. The SoftBridge performs multi-modal bridging in real-time using Text-to-Speech (TTS) and Automatic Speech Recognition (ASR) utilities accessed via web services. To perform Action Research with the Deaf community in Cape Town, we invited a Deaf user (DU) to participate in a pilot study. We conducted three tests varying the input/output modalities of the hearing user (HU). The DU had a standard text in/text out Instant Messaging client. The HU client used the following specific modality combinations: Text & TTS in/Text out, TTS in/Text out and TTS in/Text & ASR out. The SoftBridge logged the conversations for subsequent analysis. The trial showed a largely successful conversation. Success factors include a) a text and computer literate DU who is familiar with research practise, b) using the system to explain the research as we conducted it and c) that the multi-modal bridging capabilities overcame the expected shortcomings of TTS and especially ASR. The lessons learned from this trial will be applied to the next trial once the necessary modifications have been implemented. URI: http://hdl.handle.net/10566/535 Files in this item: 1
TuckerDeafTelephony2003.pdf (108.8Kb) -
Chetty, Marshini; Tucker, William D.; Blake, Edwin H. (Telkom, 2003)[more][less]
Abstract: There is a great disparity between those who have access to Information and Communication Technologies (ICTs) and those that do not. This phenomenon forms part of the Digital Divide. Many ICTs may be used to help overcome this divide if they are applied in a useful way, providing locally applicable content and services. Critical Action Research (CAR) is an approach used to develop such applications. CAR aims to empower people by involving them in the development process. Using CAR, this project investigates how Voice over IP (VoIP) may be applied in a productive way in an underserviced community. VoIP is an ICT used for sending voice over packet switched networks using Internet Protocol. It can be used to integrate data and voice to produce multimedia applications. In South Africa (SA), VoIP may only be provided by Telkom, the Second National Operator and the Under-Serviced Area Licensees. Using CAR and VoIP, an application is being developed to service a specific need of a particular rural community. The application will either provide a service to a small rural business or aid the provision of healthcare in rural areas. The project evaluates how well CAR integrates with a normal Software Development Lifecycle and makes policy recommendations for the use of VoIP in rural SA. URI: http://hdl.handle.net/10566/479 Files in this item: 1
ChettyTuckerBlakeDigitalDivide2003.pdf (35.78Kb)