Physicochemical and photodynamic antimicrobial chemotherapy studies of mono- and tetra-pyridyloxy substituted indium(III) phthalocyanines
- Authors: Osifeko, Olawale L , Durmuş, Mahmut , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: vital:7255 , http://hdl.handle.net/10962/d1020264 , http://dx.doi.org/10.1016/j.jphotochem.2014.12.011
- Description: The synthesis and photophysicochemical properties of mono- and tetra-pyridyloxy substituted indium(III) phthalocyanines (InPcs) are presented in this study. General trends are described for quantum yields of fluorescence, triplet, singlet oxygen and photodegradation as well as lifetimes of fluorescence and triplet state of these compounds. The complexes exhibited high singlet oxygen quantum yields (ФΔ) ranging from 0.44 to 0.66 in DMF, and from 0.44 to 0.69 in DMSO and ФΔ = 0.31 for the quartenized tetra substituted InPc which is soluble in water. The triplet quantum yields (ФT) ranged from 0.77 to 0.95 in DMF and from 0.77 to 0.94) in DMSO. The tetra substituted photosensitizers do not differ in their inactivation of bacteria with over 8 log reduction of viable bacteria when compared with the mono substituted photosensitizer which could only manage a 1 log reduction. , Original publication is available at http://dx.doi.org/10.1016/j.jphotochem.2014.12.011
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The development of an e-Health system for health awareness campaigns in poor areas
- Authors: Gremu, Chikumbutso , Terzoli, Alfredo , Tsietsi, Mosiuoa
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430638 , vital:72705 , 10.1109/ISTAFRICA.2015.7190527
- Description: This paper discusses work to develop an e-Health system called HealthAware to assist health service organisations to carry out targeted health awareness campaigns in poor areas. The system comprises two components called the Dashboard and the Health Messenger, which are web-based, Java applications that run in a peer-to-peer fashion. The Dashboard is used to create, manage, and publish awareness campaigns. The HealthMessenger facilitates end-users' access to the relevant awareness campaigns. A targeted communication strategy which splits the target population into subgroups based on their demo-graphic characteristics and geographic locations is used to determine relevant campaigns for a user. The HealthMessenger is hosted on an application service integration platform called TeleWeaver, while the Dashboard is hosted independently of TeleWeaver. Message queuing is used to ensure reliable communication between the Dashboard and the HealthMessenger. The implementation of HealthAware contributes knowledge on developing a system that ensures that users access only the information that is relevant to them. This addresses the challenge of sifting through potentially irrelevant information before arriving at the important information which is posed by generic materials.
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Variation in urease and β-glucosidase activities with soil depth and root density in a ‘Cripp's Pink’/M7 apple orchard under conventional and organic management.
- Authors: Meyer, André H , Wooldridge, John , Dames, Joanna F
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444051 , vital:74181 , https://doi.org/10.1080/02571862.2015.1053155
- Description: The effects of conventional (CON; utilising synthetic fertiliser and herbicide) and organic (ORG; nutrients supplied in compost, weeds controlled with straw mulch) orchard floor management practices on depth-wise variation in urease and β-glucosidase activities in tree-row soils were compared in a Western Cape ‘Cripp's Pink’/M7 apple orchard. Urease and β-glucosidase activities were determined spectrophotometrically in soils from five depth intervals from the walls of trenches excavated across the tree rows after seven years of treatment application. Soil pH, organic carbon, nitrate (NO3 ) and ammonium (NH4 ) nitrogen were also determined, as was root density. Enzyme activities were higher in the ORG than the CON topsoils but did not differ significantly (p = 0.05) at depths >30 cm. The positive effects of the ORG treatments were attributed to the liming effect and carbon and nitrogen contributions of the compost. Urease and β-glucosidase activities correlated strongly. Activities of both enzymes correlated significantly and positively with carbon, NO3− and pH, with urease correlated more strongly than β-glucosidase. Only urease correlated with root density. Organic orchard floor management practices may be more effective than CON practices in promoting microbial enzyme activities in the 0–30 cm soil depth intervals of Western Cape apple orchard soils.
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A response to the South African Jewish report and Ms Klazinga on "Jews unwelcome at Rhodes"
- Authors: Badat, Saleem
- Date: 2014
- Language: English
- Type: text
- Identifier: vital:7883 , http://hdl.handle.net/10962/d1016432
- Description: On 1 January 2014, the South African Jewish Report and Ms Larissa Klazinga made a number of unfounded claims and unsubstantiated allegations against Rhodes University. Stripped of the hysteria, lies and inaccuracies, the central claim made is that Rhodes University is hostile to Jews and seeks to be rid of Jews. We reject with contempt these baseless and self-serving claims and allegations of the South African Jewish Report and Klazinga. Rhodes is committed to an institutional culture that respects and promotes equity, human dignity and human rights, embraces difference and diversity and is comfortable for all people irrespective of ‘race’, gender, language, culture, nationality, sexual orientation and religion. Rhodes welcomes all and will continue to strive to be a Home for All.
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A temporal dimension to the influence of pollen rewards on bee behaviour and fecundity in Aloe tenuior
- Authors: Duffy, Karl J , Johnson, Steven D , Peter, Craig I
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:6561 , http://hdl.handle.net/10962/d1011735 , http://dx.doi.org/10.1371/journal.pone.0094908
- Description: The net effect of pollen production on fecundity in plants can range from negative – when self-pollen interferes with fecundity due to incompatibility mechanisms, to positive – when pollen availability is associated with increased pollinator visitation and fecundity due to its utilization as a reward. We investigated the responses of bees to pollen and nectar rewards, and the effects of these rewards on pollen deposition and fecundity in the hermaphroditic succulent shrub Aloe tenuior. Self-pollinated plants failed to set fruit, but their ovules were regularly penetrated by self-pollen tubes, which uniformly failed to develop into seeds as expected from ovarian self-incompatibility (or strong early inbreeding depression). Bees consistently foraged for pollen during the morning and early afternoon, but switched to nectar in the late afternoon. As a consequence of this differential foraging, we were able to test the relative contribution to fecundity of pollen- versus nectar-collecting flower visitors. We exposed emasculated and intact flowers in either the morning or late afternoon to foraging bees and showed that emasculation reduced pollen deposition by insects in the morning, but had little effect in the afternoon. Despite the potential for self-pollination to result in ovule discounting due to late-acting self-sterility, fecundity was severely reduced in artificially emasculated plants. Although there were temporal fluctuations in reward preference, most bee visits were for pollen rewards. Therefore the benefit of providing pollen that is accessible to bee foragers outweighs any potential costs to fitness in terms of gender interference in this species.
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An Associative Shared Memory Approach to Audio Connection Management
- Authors: Eales, Andrew , Foss, Richard
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426841 , vital:72395 , https://www.aes.org/e-lib/browse.cfm?elib=17539
- Description: A distributed, associative memory that advertises audio streams and represents audio connections between networked audio devices is described. Characteristic features of a shared, associative memory are discussed, and three parameter-based models that represent audio signals and audio connections are introduced. Connection management is then discussed with reference to a distributed, associative memory environment. This environment allows changes made to audio connections to be automatically propagated to all networked devices, while also eliminating potential race conditions between connection requests. Additionally, connection management applications can be shared between different networked devices and controllers.
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Applications of lead phthalocyanines embedded in electrospun fibers for the photoinactivation of Escherichia coli in water
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:7304 , http://hdl.handle.net/10962/d1020381
- Description: Lead (II) pyridyloxyphthalocyanine (PbTpyPc) and its quaternized form (PbTepyPc) were synthesized and the photophysical behavior examined. Low fluorescence quantum yields (ΦF) of 0.01 and 0.02 were observed for PbTepyPc and PbTpyPc, respectively. The singlet oxygen quantum yields (ΦΔ) were 0.60 and 0.68, for PbTepyPc and PbTpyPc, respectively using DPBF as a quencher in DMF. Singlet oxygen production of the embedded sensitizers in electrospun fiber were quantified using ADMA and were found to be ΦΔ = 0.41 and ΦΔ = 0.21 for PbTepyPc and PbTpyPc, respectively. Photodynamic inactivation of Escherichia coli (E. coli) with the quaternized photosensitizer at 5 μM, totally inactivated the E. coli (with log CFU = 10 decrease). Only 0.4 log CFU decrease was obtained with PbTpyPc. The embedded non-quaternized photosensitizer (PbTpyPc) was less active on the gram negative bacteria but the quaternized photosensitizer (PbTepyPc) was effective towards inactivation of E. coli. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2014.05.010
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Life-history characteristics of an age-validated established invasive African sharptooth catfish, Clarias gariepinus, population in a warm-temperate African impoundment
- Authors: Wartenberg, Reece , Weyl, Olaf L F , Booth, Anthony J , Winker, A Henning
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443542 , vital:74130 , https://hdl.handle.net/10520/EJC145790
- Description: It has been suggested that the invasive, omnivorous Clarias garipienus is capable of rapid invasions and long-term persistence in recently inhabited freshwater systems. To test this hypothesis, the life history of the established, extralimital Darlington Dam (33°10'31"S, 25°09'13"E) population was investigated. By counting post-fluorescent mark increments on otoliths from 21 chemically tagged wild fish recaptured 244-537 days later, the deposition of growth zones, comprising alternating opaque and translucent bands, was validated as annual. Examination of sectioned otoliths from 175 fish revealed that the oldest fish, two males of 840 and 1074 mm total length (TL), were 25 years old - 10 years older than previously described for any C. gariepinus population. The oldest female was 885 mm TL and 21 years old. Length-at-age was subsequently described using the von Bertalanffy growth model. Combined-sex growth was best described as Lt = 931.7 ( 1 - exp(-0.15(t +2.43))) mm TL. Total mortality (Z) was calculated using catch curve analysis and the Chapman and Robson estimator to be 0.35/yr. The presence of specimens 15 years and older indicates that these fish established quickly and supports the finding that mortality rates are low, which, in turn, suggests likely long-term population persistence.
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On the viability of pro-active automated PII breach detection: A South African case study
- Authors: Swart, Ignus , Irwin, Barry V W , Grobler, Marthie
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430235 , vital:72676 , https://doi.org/10.1145/2664591.2664600
- Description: Various reasons exist why certain types of information is deemed personal both by legislation and society. While crimes such as identity theft and impersonation have always been in existence, the rise of the internet and social media has exacerbated the problem. South Africa has recently joined the growing ranks of countries passing legislation to ensure the privacy of certain types of data. As is the case with most implemented security enforcement systems, most appointed privacy regulators operate in a reactive way. While this is a completely acceptable method of operation, it is not the most efficient. Research has shown that most data leaks containing personal information remains available for more than a month on average before being detected and reported. Quite often the data is discovered by a third party who selects to notify the responsible organisation but can just as easily copy the data and make use of it. This paper will display the potential benefit a privacy regulator can expect to see by implementing pro-active detection of electronic personally identifiable information (PII). Adopting pro-active detection of PII exposed on public networks can potentially contribute to a significant reduction in exposure time. The results discussed in this paper were obtained by means of experimentation on a custom created PII detection system.
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Primary wing-moult in relation to body-mass, wing-length and latitude in four insectivorous passerines from southern Africa
- Authors: Bonnevie, Bo T , Craig, Adrian J F K
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465424 , vital:76609 , https://doi.org/10.1071/MU13072
- Description: In southern African passerine birds, the timing of moult often varies regionally in relation to breeding season and patterns of rainfall, and may also differ between sexes in sexually dimorphic species. However, the relationship between feeding ecology andmoult has not been studied in this region. We investigated primary-moult, body-mass and wing-length in four southern African passerines belonging to a feeding guild of hawking (sallying) insectivores, using bird-banding (ringing) data. The timing of wing-moult, from December to April throughout the region, was very similar in all four species, in contrast to other sympatric species, which moult at different times in summer-and winter-rainfall regions. For each species the duration of moult decreased southwards, as did wing-length corrected for body-mass. There was no difference between the sexes in the timing or duration of wing-moult, even in sexually dimorphic species, but juveniles generally started moult later than adults and completed their moult more rapidly. Our results suggest that foraging ecology and life-history traits of insectivorous hawkers may constrain the timing of moult.
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Temporal and spatial variability in the abundance, biomass and distribution of Palaemon peringueyi (Decapoda: Crustacea) are influenced by biological but not physico-chemical factors in the permanently open Kariega Estuary, South Africa
- Authors: Nyalungu, Nonhlanhla P , Hodgson, Alan N , Froneman, P William , Dopolo, M , Masubelele, M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68106 , vital:29200 , https://doi.org/10.2989/16085914.2014.960792
- Description: Publisher version , Biological and physico-chemical factors affecting abundance and biomass of shrimp Palaemon peringueyi were investigated in 2010–2011 in the lower, middle and upper reaches of the freshwater-deprived permanently open Kariega Estuary. Shrimp abundance and biomass ranged from 0 to 88 ind. m−2 and 0 to 4.4 g wwt m−2, respectively. Shrimps were most abundant in the lower reach, and highest abundances and biomasses were recorded in the lower reach in June when salinities were low. The shrimps were almost always absent in the upper reach. Juveniles were found mostly in the lower and middle reaches, whereas adults were distributed in all three reaches. Regression analyses showed no statistically significant relationship for either abundance or biomass of the shrimps with temperature, salinity and dissolved oxygen (p > 0.05). The relationship between shrimp abundance and biomass and vegetation cover was positive and statistically significant (R2 = 0.109 and 0.185, respectively; p < 0.05). Vegetation cover plays an important role in determining the presence, distribution and abundance or biomass of P. peringueyi in this estuary.
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Towards a Sandbox for the Deobfuscation and Dissection of PHP Malware
- Authors: Wrench, Peter M , Irwin, Barry V W
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429700 , vital:72633 , 10.1109/ISSA.2014.6950504
- Description: The creation and proliferation of PHP-based Remote Access Trojans (or web shells) used in both the compromise and post exploitation of web platforms has fuelled research into automated methods of dissecting and analysing these shells. Current malware tools disguise themselves by making use of obfuscation techniques designed to frustrate any efforts to dissect or reverse engineer the code. Advanced code engineering can even cause malware to behave differently if it detects that it is not running on the system for which it was originally targeted. To combat these defensive techniques, this paper presents a sandbox-based environment that aims to accurately mimic a vulnerable host and is capable of semi-automatic semantic dissection and syntactic deobfuscation of PHP code.
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Towards building an indigenous knowledge platform to enable culturally-sensitive education underpinned by technological pedagogical and content knowledge (TPACK)
- Authors: Ntšekhe, Mathe , Terzoli, Alfredo , Thinyane, Mamello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431424 , vital:72773 , http://proceedings.e-skillsconference.org/2014/e-skills275-284Ntsekhe821.pdf
- Description: The everyday use of Information and Communication Technologies (ICTs) is ingrained to the fabric of today’s society. A question open for debate is whether this use is or can be optimized to engender authentic solutions, which are aligned to the natural environment of the people? In this paper, we examine at the question from the vantage point of ed-ucating the rural African child. We engage with the sub-question: can ICTs facilitate education grounded in people's own realities, especially those of the marginalized rural poor? We believe this is possible under specific conditions, which include making Indigenous Knowledge (IK) readily available. We propose building an ICT platform that allows injec-tion of IK into the education process: develop a solution that valorizes IK, but also supports efforts to use ICTs in education driven by Tech-nology, Pedagogy, and Content Knowledge (TPACK) framework. The main goal of this framework is to facilitate effective teaching with tech-nology. TPACK partially embeds IK within pedagogical knowledge and ‘contexts’ of learning; we argue for explicit inclusion of IK within the framework to complement the other knowledges.
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Tufa stromatolite ecosystems on the South African south coast
- Authors: Perissinotto, Renzo , Bornman, Thomas G , Steyn, Paul-Pierre , Miranda, Nelson A F , Dorrington, Rosemary A , Matcher, Gwynneth F , Strydom, Nadine A , Peer, Nasreen
- Date: 2014
- Language: English
- Type: Article
- Identifier: vital:6490 , http://hdl.handle.net/10962/d1014585 , http://dx.doi.org/10.1590/sajs.2014/20140011
- Description: Following the first description of living marine stromatolites along the South African east coast, new investigations along the south coast have revealed the occurrence of extensive fields of actively calcifying stromatolites. These stromatolites have been recorded at regular distances along a 200-km stretch of coastline, from Cape Recife in the east to the Storms River mouth in the west, with the highest density found between Schoenmakerskop and the Maitland River mouth. All active stromatolites are associated with freshwater seepage streams flowing from the dune cordon, which form rimstone dams and other accretions capable of retaining water in the supratidal platform. Resulting pools can reach a maximum depth of about 1 m and constitute a unique ecosystem in which freshwater and marine organisms alternate their dominance in response to vertical mixing and the balance between freshwater versus marine inflow. Although the factors controlling stromatolite growth are yet to be determined, nitrogen appears to be supplied mainly via the dune seeps. The epibenthic algal community within stromatolite pools is generally co-dominated by cyanobacteria and chlorophytes, with minimal diatom contribution.
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Using multivariate analysis and stable isotopes to assess the effects of substrate type on phytobenthos communities
- Authors: Dalu, Tatenda , Richoux, Nicole B , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68123 , vital:29201 , https://doi.org/10.5268/IW-4.4.719
- Description: Publisher version , For more than a century, artificial substrates have been employed in phytobenthos studies. In the present study, we compared the phytobenthos community structure in a field experiment over 3 seasons (summer, autumn, and winter) on 3 types of artificial substrates (brick, brown clay tiles, and grey clay tiles) and 3 natural substrates (macrophytes, rocks, and sediment) in a small, temperate system. A combination of multivariate analyses (cluster, multi-response permutation procedure, indicator species [IndVal], and canonical correspondence analysis [CCA]) and stable isotope analysis was used. We identified 96 total phytobenthos taxa. Artificial substrates resulted in different substrate communities, as shown by stable isotope analysis, cluster analysis, and a multi-response permutation procedure, with only those communities growing on grey tiles being similar to natural substrate communities. Overall, artificial substrates exhibited slightly higher species richness compared to natural substrates over the 3 seasons, although there were no significant differences (p> 0.05). Phytobenthos grown on brown tiles, rocks, and bricks showed seasonal variability of the carbon isotope δ13C values using one-way ANOVA (p< 0.05). Phytobenthos community structure did not show great seasonal variation; however, CCA identified water flow, conductivity, ammonium, phosphate, and water depth as important in structuring phytobenthos communities on different substrates. IndVal analysis showed that common phytobenthos taxa were not restricted to a single substrate, but preference was generally high for natural substrate, especially rocks, compared to artificial substrates. Substrate microhabitat type seems to influence the communities within the study areas.
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Utilizing gesture recognition and Ethernet AVB for distributed surround sound control
- Authors: Hedges, Mitchell , Foss, Richard
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426816 , vital:72393 , https://www.aes.org/e-lib/online/browse.cfm?elib=17540
- Description: Gesture recognition has become a preferred approach to the control of various systems. This allows users of the system to interact without having to use any controls or equipment. This paper investigates the use of gesture recognition in order to select and transport audio tracks over an Ethernet AVB network to speaker endpoints. The research uses equipment that is commercially available and relatively cost efficient. The endpoints receive audio samples that are encapsulated within network packets and processes them. The audio tracks are mixed at the endpoints according to gain ratios that will change and be different for each endpoint.
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The context of differentiation in Higher Education: A perspective
- Authors: Badat, Saleem
- Date: 2013-01-24
- Language: English
- Type: Text
- Identifier: vital:7902 , http://hdl.handle.net/10962/d1016452
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A baseline study of potentially malicious activity across five network telescopes
- Authors: Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429714 , vital:72634 , https://ieeexplore.ieee.org/abstract/document/6568378
- Description: +This paper explores the Internet Background Radiation (IBR) observed across five distinct network telescopes over a 15 month period. These network telescopes consisting of a /24 netblock each and are deployed in IP space administered by TENET, the tertiary education network in South Africa covering three numerically distant /8 network blocks. The differences and similarities in the observed network traffic are explored. Two anecdotal case studies are presented relating to the MS08-067 and MS12-020 vulnerabilities in the Microsoft Windows platforms. The first of these is related to the Conficker worm outbreak in 2008, and traffic targeting 445/tcp remains one of the top constituents of IBR as observed on the telescopes. The case of MS12-020 is of interest, as a long period of scanning activity targeting 3389/tcp, used by the Microsoft RDP service, was observed, with a significant drop on activity relating to the release of the security advisory and patch. Other areas of interest are highlighted, particularly where correlation in scanning activity was observed across the sensors. The paper concludes with some discussion on the application of network telescopes as part of a cyber-defence solution.
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Audio Device Representation, Control, and Monitoring Using SNMP
- Authors: Eales, Andrew , Foss, Richard
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426855 , vital:72396 , https://www.aes.org/e-lib/browse.cfm?elib=17012
- Description: The Simple Network Management Protocol (SNMP) is widely used to configure and monitor networked devices. The architecture of complex audio devices can be elegantly represented using SNMP tables. Carefully considered table indexing schemes support a logical device model that can be accessed using standard SNMP commands. This paper examines the use of SNMP tables to represent the architecture of audio devices. A representational scheme that uses table indexes to provide direct-access to context-sensitive SNMP data objects is presented. The monitoring of parameter values and the implementation of connection management using SNMP are also discussed.
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Developing a virtualised testbed environment in preparation for testing of network based attacks
- Authors: Van Heerden, Renier , Pieterse, Heloise , Burke, Ivan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429648 , vital:72629 , 10.1109/ICASTech.2013.6707509
- Description: Computer network attacks are difficult to simulate due to the damage they may cause to live networks and the complexity required simulating a useful network. We constructed a virtualised network within a vSphereESXi environment which is able to simulate: thirty workstations, ten servers, three distinct network segments and the accompanying network traffic. The VSphere environment provided added benefits, such as the ability to pause, restart and snapshot virtual computers. These abilities enabled the authors to reset the simulation environment before each test and mitigated against the damage that an attack potentially inflicts on the test network. Without simulated network traffic, the virtualised network was too sterile. This resulted in any network event being a simple task to detect, making network traffic simulation a requirement for an event detection test bed. Five main kinds of traffic were simulated: Web browsing, File transfer, e-mail, version control and Intranet File traffic. The simulated traffic volumes were pseudo randomised to represent differing temporal patterns. By building a virtualised network with simulated traffic we were able to test IDS' and other network attack detection sensors in a much more realistic environment before moving it to a live network. The goal of this paper is to present a virtualised testbedenvironmentin which network attacks can safely be tested.
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