Browsing Faculty of Natural Sciences by Title
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Segers, Vaughn; Connan, James (2009)[more][less]
Abstract: This paper discusses an implementation for gesture recognition using eigenvectors under controlled conditions. This application of eigenvector recognition is trained on a set of defined hand images. Training images are processed using eigen techniques from the OpenCV image processing library. Test images are then compared in real-time. These techniques are outlined below. URI: http://hdl.handle.net/10566/63 Files in this item: 1
Segers_Real2009.pdf (179.9Kb) -
Tucker, William D.; Blake, Edwin H.; Marsden, Gary; Pearson, Murray; Westerveld, Rudi (Telkom, 2007)[more][less]
Abstract: This paper reports on three years of research and fieldwork with a rural wireless Internet Protocol communication project. We built a long-range WiFi network and custom communication software to support a rural telehealth project in the remote Eastern Cape. We report on our work using cellular networks, devices and applications as reference technologies because our users and beneficiaries are very comfortable with them. Of most concern are the technological and contextual issues affecting take up of the systems we designed. The paper intends to provide a summary analysis of our experience so that others in the field can learn from our successes and mistakes with respect to rural Information and Communication Technology for Development (ICT4D) in a South African context. URI: http://hdl.handle.net/10566/487 Files in this item: 1
TuckerIP-Communication2007.pdf (1.427Mb) -
Daniels, Francois; Tucker, William D. (Telkom, 2008)[more][less]
Abstract: This paper presents a fully decentralised peer-topeer voice communication tool intended for use across mobile ad hoc networks (MANET) by distributed groups who desired collaboration. We examined the synergy between MANETs and peer-to-peer virtual overlay networks which allowed the creation of ad hoc applications. One style of communication considered suitable for task oriented distributed group collaboration was push-to-talk. This research was focused on providing a push-to-talk communication platform suitable for deployment across MANETs. The research methodology employed was a proof of concept approach within a classical experimental computer science paradigm. We developed a prototype which used JXTA, a peer-to-peer virtual overlay network, to provide push-to-talk functionality across MANETs. Guaranteed delivery of messages was provided via a peer-to-peer voicemail delivery system. While the system did what intended we show that JXTA had a problem with the efficient delivery of voice samples. URI: http://hdl.handle.net/10566/508 Files in this item: 1
DanielsTuckerMANET2008.pdf (216.0Kb) -
Baker, Gillian; Smith, J.J.; Cowan, Donald A. (Elsevier, 2003)[more][less]
Abstract: The Polymerase Chain Reaction (PCR) has facilitated the detection of unculturable microorganisms in virtually any environmental source and has thus been used extensively in the assessment of environmental microbial diversity. This technique relies on the assumption that the gene sequences present in the environment are complementary to the “universal” primers used in their amplification. The recent discovery of new taxa with 16S rDNA sequences not complementary to standard universal primers suggests that current 16S rDNA libraries are not representative of true prokaryotic biodiversity. Here we re-assess the specificity of commonly used 16S rRNA gene primers and present these data in tabular form designed as a tool to aid simple analysis, selection and implementation. In addition, we present two new primer pairs specifically designed for effective ‘universal’ Archaeal 16S rDNA sequence amplification. These primers are found to amplify sequences from Crenarchaeote and Euryarchaeote type strains and environmental DNA. URI: http://hdl.handle.net/10566/169 Files in this item: 1
BakerReviewReanalysis2003.pdf (969.0Kb) -
Samaai, Toufiek; Gibbons, Mark J.; Kelly, Michelle (Cambridge University Press, 2009)[more][less]
Abstract: The sponge genus Strongylodesma is reviewed and redefined, and now accommodates eight closely related species. The type species of Strongylodesma Le´vi is redescribed and an additional two new species are described from the Indo-Pacific: S. novaecaledoniae sp. nov. and S. tongaensis sp. nov. Several specimens previously identified as species of Batzella (Poecilosclerida: Chondropsidae) have been re-assigned to Strongylodesma, as the new species S. purpureus sp. nov. and S. nigra sp. nov. With the description here of new species from the Pacific Ocean and Caribbean Atlantic, the biogeographical distribution of Strongylodesma now appears to be generally tropical with a subtropical South African component, whereas previously it was only known from South Africa. Although species of Strongylodesma have not previously been recorded from the intermediate locations (Western Indian Ocean, South-east Asia, central west Pacific, and New Zealand), re-evaluation here will facilitate more readily the recognition of taxa in these intermediate regions, if they exist, in the future. The species are not widespread, except perhaps along the south-east coast of South Africa, and where they occur they are not abundant. Species occur over a wide depth range, from the intertidal in Tsitsikamma, South Africa, to 140 m in the Caribbean. URI: http://hdl.handle.net/10566/248 Files in this item: 1
SamaaiRevision2009.pdf (893.7Kb) -
Tucker, William D.; Blake, Edwin H. (International Information Management Corporation, 2008)[more][less]
Abstract: We describe the use of Outcome Mapping to guide the design of a rural telemedicine consultation system in South Africa. While Outcome Mapping was not primarily intended to guide design, we show that it tied in well with a cyclical participatory design method for an Information and Communication Technology for Development project. URI: http://hdl.handle.net/10566/525 Files in this item: 1
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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) -
Poroye, Adeola; Tucker, William D.; Norman, Michael (Telkom, 2009)[more][less]
Abstract: This paper presents work in progress to explore the utility of Near Field Communication technology to secure mobile financial services. The objective is to evaluate the potential of this approach as an upcoming technology for mobile cash transactions. The paper argues that Near Field Communication technology offers a feasible solution and can be integrated into a standard cellular handset to turn it into a contactless smart card. The motivation is to create a new secure way for the unbanked to perform financial transactions. A prototype has been developed and tested with participants in a laboratory environment. This paper also reports on preliminary results. URI: http://hdl.handle.net/10566/540 Files in this item: 1
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Pagaling, Eulyn; Haigh, Richard D.; Grant, William D.; Cowan, Donald A.; Jones, Brian; Ma, Yanhe; Ventosa, Antonio; Heaphy, Shaun (BioMed Central, 2007)[more][less]
Abstract: Background: We are profoundly ignorant about the diversity of viruses that infect the domain Archaea. Less than 100 have been identified and described and very few of these have had their genomic sequences determined. Here we report the genomic sequence of a previously undescribed archaeal virus. Results: Haloarchaeal strains with 16S rRNA gene sequences 98% identical to Halorubrum saccharovorum were isolated from a hypersaline lake in Inner Mongolia. Two lytic viruses infecting these were isolated from the lake water. The BJ1 virus is described in this paper. It has an icosahedral head and tail morphology and most likely a linear double stranded DNA genome exhibiting terminal redundancy. Its genome sequence has 42,271 base pairs with a GC content of ~65 mol%. The genome of BJ1 is predicted to encode 70 ORFs, including one for a tRNA. Fifty of the seventy ORFs had no identity to data base entries; twenty showed sequence identity matches to archaeal viruses and to haloarchaea. ORFs possibly coding for an origin of replication complex, integrase, helicase and structural capsid proteins were identified. Evidence for viral integration was obtained. Conclusion: The virus described here has a very low sequence identity to any previously described virus. Fifty of the seventy ORFs could not be annotated in any way based on amino acid identities with sequences already present in the databases. Determining functions for ORFs such as these is probably easier using a simple virus as a model system. URI: http://hdl.handle.net/10566/140 Files in this item: 1
PagalingSequenceAnalysis2007.PDF (1.860Mb) -
Wu, Wilson; Radovanovic, Aleksandar; Tucker, William D. (Telkom, 2005)[more][less]
Abstract: This paper presents an innovative use of the Session Initiation Protocol (SIP) for the subscription and notification of geographic information in order to provide a privacy concerned location-based service. SIP is a signaling protocol used for establishing sessions in an IP network. It has been widely used for Internet conferencing and telephony. This research project aims to enhance the SIP presence model in order to protect sensitive geographic information. To achieve this goal, we thoroughly analyzed existing Location-Based Services (LBS), reviewed LBS designs’ pitfalls and identified several key privacy requirements. Based on this research, we presented a SIP flow that meets the privacy requirements. This SIP message flow includes SUBSCRIBE, NOTIFY and PUBLISH messages. A data format to carry geographic location information has also been introduced. The data format is based on Presence Information Data Format (PIDF). We define it as Location-enhanced PIDF, or LPIDF. LPIDF contains geographical information objects. We hope that the outcome of this research project will provide rich, convenient, privacy concerned architecture for LBS. Because LPIDF is based on SIP, this approach can be easily integrated into IP telephony services. LPIDF enables personalization of the Location-Based services address user privacy concerns and hereby increase their satisfaction. URI: http://hdl.handle.net/10566/494 Files in this item: 1
WuRadovanovicTuckerSIP2005.pdf (385.7Kb) -
Kobo, Hlabishi Isaac; Tucker, William D. (IIMC International Information Management Corporation, 2012)[more][less]
Abstract: This paper describes a situation-aware algorithm based on the current situation of a mesh network with mobile nodes that improves quality of service. After running laboratory performance tests, we concluded that a situation-aware mesh routing protocol offers potential to address issues pertaining to mobility, congestion and scalability in dynamic mesh networks with mobile nodes. Such networks appear promising to provide connectivity to people living in rural areas in developing regions of Africa, and can be easily interconnected to telco-styled networks through gateways for voice and Internet services. Such services can remain free in the mesh, yet can also be billed for interconnection. Our vision offers an attractive business model for up scaling a rural customer base for telcos, while at the same time offering increased quality of service for mobile users on rural mesh networks. URI: http://hdl.handle.net/10566/585 Files in this item: 1
KoboTuckerISTAfrica2012.pdf (465.0Kb) -
Roro, Zukile; Rey-Moreno, Carlos; Tucker, William D.; Siya, Masbulele Jay (Telkom, 2012)[more][less]
Abstract: This paper describes work in progress towards developing a business case and preliminary design for an 802.11-based mesh network in the remote rural community of Mankosi in the Eastern Cape province of South Africa. Aside from the technical challenges to building the network to be sustainable in the long term, this network needs to generate some revenue. Hence, there needs to be a business model that has revenue generation potential. This study will explore the economical and social aspects of voice over Internet- Protocol as a service for this community. After talking to the village leaders, we learned that there is a demand for telecommunication services and that most of them were interested only in telephony service. Very few villagers were interested in or had any knowledge about the Internet. We also learned that most of their cellular phone calls are local within the Mankosi community. This allows us to deploy an experimental local telephony service; a perfect opportunity for a low-cost and lowcosting inverse mesh infrastructure that can easily be connected to breakout and Internet services in the future. URI: http://hdl.handle.net/10566/594 Files in this item: 1
RoroRey-MorenoTuckerSiya-SATNAC2012.pdf (150.8Kb) -
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) -
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) -
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) -
Sun, Tao; Tucker, William D. (Telkom, 2004)[more][less]
Abstract: We have built a SoftBridge prototype within a JAIN (Java APIs for the Integrated Network) SLEE (Service Logic Execution Environment). A SoftBridge is a semi-synchronous multimodal IP (Internet Protocol) -based communication system and the first prototype has been built for deaf telephony. This research addresses service life-cycle management for a SoftBridge with carrier grade reliability. An approach is proposed that carrier grade reliability support for a SoftBridge is provided by moving it into a JAIN SLEE. A JAIN SLEE is a general application server, which provides execution and management environment for telecommunication services. An empirical evaluation methodology is adopted to verify that JAIN SLEE enables carrier grade support for a SoftBridge. This work includes the development of functions of a SoftBridge and life-cycle management of a SoftBridge within a JAIN SLEE. Current work is busy in developing multimodal media adaptation functions of the SoftBridge prototype. System test, experiments with PBX (Private Branch Exchange)/PSTN (Public Switched Telephone Network) and evaluation of the SoftBridge prototype will be carried out in the next steps. Carrier grade reliability enables a SoftBridge to access the PSTN. A highly reliable SoftBridge could bring more new value-added services for telecom providers. Using a SoftBridge as an example, we also can learn how to go about carrier grade enhancement for IP-based communication applications in the telecoms domain. URI: http://hdl.handle.net/10566/592 Files in this item: 1
SunTucker-SATNAC2004.pdf (66.62Kb) -
Kimani, Serah W.; Agarkar, Vinod B.; Cowan, Donald A.; Sayed, Muhammed F.; Sewell, B. Trevor (International Union of Crystallography, 2007)[more][less]
Abstract: The amidase from Geobacillus pallidus RAPc8, a moderate thermophile, is a member of the nitrilase superfamily and catalyzes the conversion of amides to the corresponding carboxylic acids and ammonia. It shows both amide-hydrolysis and acyl-transfer activities and also exhibits stereoselectivity for some enantiomeric substrates, thus making it a potentially important industrial catalyst. The crystal structure of G. pallidus RAPc8 amidase at a resolution of 1.9 A ˚ was solved by molecular replacement from a crystal belonging to the primitive cubic space group P4232. G. pallidus RAPc8 amidase is homohexameric in solution and its monomers have the typical nitrilase-superfamily α-β-β-α fold. Association in the hexamer preserves the eight-layered α-β-β-α:α-β-β-α structure across an interface which is conserved in the known members of the superfamily. The extended carboxy-terminal tail contributes to this conserved interface by interlocking the monomers. Analysis of the small active site of the G. pallidus RAPc8 amidase suggests that access of a water molecule to the catalytic triad (Cys, Glu, Lys) side chains would be impeded by the formation of the acyl intermediate. It is proposed that another active-site residue, Glu142, the position of which is conserved in the homologues, acts as a general base to catalyse the hydrolysis of this intermediate. The small size of the substrate-binding pocket also explains the specificity of this enzyme for short aliphatic amides and its asymmetry explains its enantioselectivity. URI: http://hdl.handle.net/10566/141 Files in this item: 1
KimaniAliphaticAmidase2007.pdf (2.155Mb) -
Ghaziasgar, Mehrdad; Connan, James (2008)[more][less]
Abstract: Current wireless human-computer interaction devices such as wireless mice and touchscreens, by and large, incorporate a sophisticated electronic architecture. The sophistication achieves wireless capabilities but carries over a cost overhead. In this paper we lay the foundation for developing a novel human-computer interaction device with reduced hardware sophistication. We developed a surface acoustic wave touchscreen-type device using only two transducers, as opposed to, typically, three or more transducers in conventional surface acoustic wave touchscreens. The transducers are mounted on a glass surface and connected into the line-in of a stereo sound card. User-initiated taps are detected, analysed and located on the surface, and the mouse cursor is moved to the computed screen location. URI: http://hdl.handle.net/10566/54 Files in this item: 1
Ghaziasgar_Surface(2008).pdf (454.3Kb) -
Felix, Cecil; Maiyalagan, Thandavarayan; Sivakumar, Pasupathi; Linkov, Vladimir (Bentham Science Publishers, 2012)[more][less]
Abstract: IrO2 as an anodic electrocatalyst for the oxygen evolution reaction (OER) in solid polymer electrolyte (SPE) electrolysers was synthesised by adapting the Adams fusion method. Optimisation of the IrO2 electrocatalyst was achieved by varying the synthesis duration (0.5 – 4 hours) and temperature (250 - 500°C). The physical properties of the electrocatalysts were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD). Electrochemical characterisation of the electrocatalysts toward the OER was evaluated by chronoamperometry (CA). CA analysis revealed the best electrocatalytic activity towards the OER for IrO2 synthesised for 2 hours at 350oC which displayed a better electrocatalytic activity than the commercial IrO2 electrocatalyst used in this study. XRD and TEM analyses revealed an increase in crystallinity and average particle size with increasing synthesis duration and temperature which accounted for the decreasing electrocatalytic activity. At 250°C the formation of an active IrO2 electrocatalyst was not favoured. URI: http://hdl.handle.net/10566/439 Files in this item: 1
FelixElectrocatalyst2012.pdf (3.090Mb) -
Felix, Cecil; Maiyalagan, Thandavarayan; Pasupathi, Sivakumar; Bladergroen, Bernard Jan; Linkov, Vladimir (Electochemical Society Inc., 2012)[more][less]
Abstract: IrO2, IrxRu1-xO2, IrxSnx-1O2 and IrxTax-1O2 (1 ≥ x ≥ 0.7) were synthesized, characterised and evaluated as electrocatalysts for the oxygen evolution reaction in solid polymer electrolyte electrolysers. The electrocatalysts were synthesised by adapting the Adams fusion method. The physical properties of the electrocatalysts were characterised by scanning electron microscopy, transmission electron microscopy and x-ray diffraction. Electrochemical activity of the electrocatalysts toward the oxygen evolution reaction was evaluated by cyclic voltammetry and chronoamperometry. X-ray diffraction revealed no phase separation when RuO2 or SnO2 was introduced into the IrO2 lattice suggesting that solid solutions were formed. Transmission electron microscope analysis revealed nanosize particles for all synthesised metal oxides. Crystallinity increased with the addition of RuO2 and SnO2 while a suppression of crystal growth was observed with the addition of Ta2O5 to IrO2. Chronoamperometry revealed that the addition of all the secondary metal oxides to IrO2 resulted in improved catalytic performance. Ir0.7Ru0.3O2 was identified as the most promising electrocatalyst for the oxygen evolution reaction. Keywords: URI: http://hdl.handle.net/10566/504 Files in this item: 1
FelixOxygenEvolutionReaction2012.pdf (1.464Mb)