The comparative growth rates of indigenous street and garden trees in Grahamstown, South Africa
- Authors: De Lacy, Peter J G , Shackleton, Charlie M
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180943 , vital:43672 , xlink:href="https://doi.org/10.1016/j.sajb.2014.02.007"
- Description: Urban forestry is advocated worldwide as a means of enhancing the liveability of towns and cities, and mitigating some of the anticipated impacts of climate change. Optimisation of the benefits of trees in urban areas is dependent upon knowledge of tree form, growth, and the products and benefits that trees provide. Growth rates are a vital variable for modelling benefits, yet there is a significant gap in knowledge pertaining to growth rates of trees in urban areas, especially indigenous species in developing world countries. Here we report on growth rates of indigenous street and garden trees in Grahamstown, South Africa, using two approaches; tree ring counts on increment cores and mean rates from trees of known planting age. Growth equations for both street and garden trees were derived. There was no significant difference in mean growth rates determined via the two methods. For both methods street trees grew approximately 30% slower than trees in gardens.
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- Date Issued: 2014
The effect of sap-sucking by Falconia intermedia (Hemiptera: Miridae) on the emission of volatile organic compounds from the leaves of Lantana camara varieties
- Authors: Heshula, Lelethu U , Hill, Martin P
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406141 , vital:70242 , xlink:href="https://hdl.handle.net/10520/EJC150957"
- Description: Evidence from more than 100 plant species has confirmed that plants emit volatile organic chemicals (VOC) in response to herbivory (Karban and Baldwin 1997; Dicke et al. 2003; Arimura et al. 2005). Feeding-induced plant responses may result in higher levels of volatiles, and different bouquets of compounds being emitted by plants following herbivore damage (Wei et al. 2006). The emission of volatile chemicals may be beneficial to plants in two ways; undamaged plants may interpret the chemical signals from damaged plants and in turn prime themselves for defence (Arimura et al. 2000; Dicke et al. 2003; Agrawal 2005), or volatiles emitted by damaged plants may attract natural enemies of the herbivores, which may reduce further damage to the plants (Tumlinson et al. 1993; De Moraes et al. 1998; Dicke and Vet 1999).
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- Date Issued: 2014
The ethical function of research and teaching
- Authors: Tabensky, Pedro
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/305738 , vital:58608 , xlink:href="https://doi.org/10.1111/j.1469-5812.2011.00813.x"
- Description: It is the epistemic as well as the ethical responsibility of academics to aim to approach their research and teaching with a proper understanding of the ultimate ethical purpose or telos of their defining activities and products,which is the practical aim of promoting human flourishing. Minimally, academics should aim at understanding, and a key component of understanding is to understand the ideal ethical purpose of what is being researched and taught. For instance, sadistic Nazi medical researchers and teachers—Mengeles of sorts—in addition to having reprehensible commitments,would be significantly ignorant about their own intellectual concerns by virtue of their abject (belief-expressing) commitments. I will show that insights drawn from extreme cases such as this one apply across disciplines and in less extreme cases.
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- Date Issued: 2014
The extent and perceptions of vandalism as a cause of street tree damage in small towns in the Eastern Cape, South Africa
- Authors: Richardson, Emma , Shackleton, Charlie M
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180954 , vital:43676 , xlink:href="https://doi.org/10.1016/j.ufug.2014.04.003"
- Description: Street trees are important foundations of urban sustainability due to the ecosystem services that they provide society and the environment. However, street trees are vulnerable to vandalism and damage, especially when small, which constraints the flow of benefits they provide and also increases the costs of planting programmes. Despite being a common phenomenon, there is limited knowledge regarding the extent of vandalism and the reasons for it. Here we seek to understand the causes and extent of street tree damage in eleven small Eastern Cape (South Africa) towns and to assess the perceptions of residents and officials. The condition of newly planted street trees was assessed in each town and residents were interviewed in the two towns with the highest number of newly planted street trees. Almost half (42%) of recently planted street trees were totally snapped, ranging between 0% and 63% per town. There was no difference in the prevalence of trees being snapped between those with protective structures and those without. Each town used different structures around newly planted street trees, but in only two towns were all the structures intact. The prevalence of damage declined with increasing trunk thickness and increasing town size. According to residents, boredom, misbehaviour, lack of appreciation of trees and collection for wood were the main factors for tree vandalism by people along with damage by livestock. Ward councillors recognised the presence of vandalism, but indicated that it was not a priority topic in their ward meetings. Suggestions by residents to prevent vandalism included: planting in sensible areas, re-designing the protective structures, re-locating livestock and engendering community participation and ownership in all aspects of street tree planting.
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- Date Issued: 2014
The herbivorous arthropods associated with the invasive alien plant, Arundo donax, and the native analogous plant, Phragmites australis, in the Free State Province, South Africa s
- Authors: Canavan, Kim N , Paterson, Iain D , Hill, Martin P
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406155 , vital:70243 , xlink:href="https://hdl.handle.net/10520/EJC155690"
- Description: The Enemy Release Hypothesis (ERH) predicts that when plant species are introduced outside their native range there is a release from natural enemies resulting in the plants becoming problematic invasive alien species (Lake and Leishman 2004; Puliafico et al. 2008). The release from natural enemies may benefit alien plants more than simply reducing herbivory because, according to the Evolution of Increased Competitive Ability (EICA) hypothesis, without pressure from herbivores more resources that were previously allocated to defence can be allocated to reproduction (Blossey and Notzold 1995). Alien invasive plants are therefore expected to have simpler herbivore communities with fewer specialist herbivores (Frenzel and Brandl 2003; Heleno et al. 2008; Heger and Jeschke 2014).
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- Date Issued: 2014
The impact of manufacturing variables on in vitro release of clobetasol 17-propionate from pilot scale cream formulations
- Authors: Fauzee, Ayesha F B , Khamanga, Sandile M , Walker, Roderick B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183872 , vital:44077 , xlink:href="https://doi.org/10.3109/03639045.2013.842579"
- Description: The purpose of the study was to evaluate the effect of different homogenization speeds and times, anchor speeds and cooling times on the viscosity and cumulative % clobetasol 17-propionate released per unit area at 72 h from pilot scale cream formulations. A 24 full factorial central composite design for four independent variables were investigated. Thirty pilot scale batches of cream formulations were manufactured using a Wintech® cream/ointment plant. The viscosity and in vitro release of CP were monitored and compared to an innovator product that is commercially available on the South African market, namely, Dermovate® cream. Contour and three-dimensional response surface plots were produced and the viscosity and cumulative % CP released per unit area at 72 h were found to be primarily dependent on the homogenization and anchor speeds. An increase in the homogenization and anchor speeds appeared to exhibit a synergistic effect on the resultant viscosity of the cream whereas an antagonistic effect was observed for the in vitro release of CP from the experimental cream formulations. The in vitro release profiles were best fitted to a Higuchi model and diffusion proved to be the dominant mechanism of drug release that was confirmed by use of the Korsmeyer–Peppas model. The research was further validated and confirmed by the high prognostic ability of response surface methodology (RSM) with a resultant mean percentage error of (±SD) 0.17 ± 0.093 suggesting that RSM may be an efficient tool for the development and optimization of topical formulations.
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- Date Issued: 2014
The influence of gold nanoparticles on the electroactivity of nickel tetrasulfonated phthalocyanine
- Authors: Maringa, Audacity , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189774 , vital:44930 , xlink:href="https://doi.org/10.1142/S1088424614500333"
- Description: We report on the electrodeposition of gold nanoparticles (AuNPs) on a glassy carbon electrode (GCE) followed by deposition of nickel tetrasulfonated phthalocyanine (NiTSPc) film by electropolymerization (poly-NiTSPc-GCE) to form Poly-NiTSPc/AuNPs-GCE. The presence of the gold nanoparticles caused a lowering of the anodic and cathodic peak separation (ΔEp) of ferricyanide from 126 mV on poly-NiTSPc to 110 mV on poly-NiTSPc/AuNPs. The electrooxidation of nitrite improved on modified electrodes compared to GCE, with the latter giving Ep = 0.78 V and the modified electrodes gave Ep = 0.62 V or 0.61 V. Poly-NiTSPc/AuNPs-GCE had higher currents compared to poly-NiTSPc-GCE. This indicates the enhancement effect caused by the AuNPs. Electrochemical impedance spectroscopy and chronoamperometric studies also showed that poly-NiTSPc/AuNPs-GCE was a better electrocatalyst than poly-NiTSPc-GCE or AuNPs-GCE.
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- Date Issued: 2014
The life history traits of the arctiine moth Pareuchaetes insulata, a biological control agent of Chromolaena odorata in South Africa
- Authors: Uyi, Osariyekemwen , Zachariades, Costas , Hill, Martin P
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406170 , vital:70244 , xlink:href="https://hdl.handle.net/10520/EJC160238"
- Description: Pareuchaetes insulata (Walker) (Lepidoptera: Erebidae: Arctiinae) was released in KwaZulu-Natal, South Africa, as a biological control agent against Chromolaena odorata (L.) King and Robinson (Asteraceae) between 2001 and 2009. Although the moth did establish at one out of some 30 release sites, its population level is generally low in the field. Two closely related biological control agents, P. pseudoinsulata Rego Barros and P. aurata aurata (Butler) had previously failed to establish despite several years of releases. Studies of life history traits of P. insulata (males and females) were conducted to determine whether several aspects of its developmental and reproductive biology can explain its poor performance, and to compare the development and reproductive biology of P. insulata with the two other closely related species. At 25 °C, overall mortality of immature stages was generally low (below 12 %). Although the duration of the larval life stage was statistically longer for females, overall they eclosed as adults before the males (i.e. protogyny). Pupal mass, growth rate and total leaf area consumed were higher in females. Mated females laid 74% of their eggs on the first four nights following eclosion and lived an average of 5.92 ± 0.19 days. The moth also showed good biological attributes such as high fecundity (number of eggs), egg hatchability and female mating success (the number of matings that resulted in fertile eggs). Significant positive correlations were detected between insect performance metrics and leaf consumption and between fecundity and pupal mass. A 23 % greater lifetime reproductive output (387.62 ± 19.50 eggs per female) for P. insulata compared with P. aurata aurata was recorded. We hypothesize that the absence of protandry in P. insulata might have contributed to the low population levels of the moth in the field. The results of this study contribute to our understanding of the life history traits of erebid moths in the subfamily Arctiinae deployed for the biological control of C. odorata.
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- Date Issued: 2014
the programmable bride
- Authors: Krueger, Anton
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229698 , vital:49701 , xlink:href="https://hdl.handle.net/10520/EJC156969"
- Description: the man gently opens his machine and finding an agreeable port for his firm flash, he eagerly installs the software he's been waiting on for so very long... once booted up, the man takes his first tentative steps, finding his bride perfect in every way, already completely in love with him, and dreamy... the man tenderly reaches out for her-she understands him so well, she's concerned about his needs, she wants to know how he feels, wants only to please him, she only-/but-there's an interruption/somebody's on the stairs, someone's knocking at his door-the man is forced to close her down a little too abruptly, shutting the machine to attend to other matters while he's away he can't wait to get back, he thinks about her all the time; he longs to flip his laptop lid up, to open her again... but when finally he silently prises open the instrument of his heart's desires, she seems a little disorientated... he didn't shut her down properly …
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- Date Issued: 2014
Towards a platform to visualize the state of South Africa's information security
- 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/10962/429688 , vital:72632 , 10.1109/ISSA.2014.6950511
- Description: Attacks via the Internet infrastructure is increasingly becoming a daily occurrence and South Africa is no exception. In response, certain governments have published strategies pertaining to information security on a national level. These policies aim to ensure that critical infrastructure is protected, and that there is a move towards a greater state of information security readiness. This is also the case for South Africa where a variety of policy initiatives have started to gain momentum. While establishing strategy and policy is essential, ensuring its implementation is often difficult and dependent on the availability of resources. This is even more so in the case of information security since virtually all standardized security improvement processes start off with specifying that a proper inventory is required of all hardware, software, people and processes. While this may be possible to achieve at an organizational level, it is far more challenging on a national level. In this paper, the authors examine the possibility of making use of available data sources to achieve inventory of infrastructure on a national level and to visualize the state of a country's information security in at least a partial manner.
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- Date Issued: 2014
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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- Date Issued: 2014
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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- Date Issued: 2014
Trends in the TD-DFT calculations of porphyrin and phthalocyanine analogs
- Authors: Mack, John , Stone, Justin , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193882 , vital:45402 , xlink:href="https://doi.org/10.1142/S108842461450045X"
- Description: In 2005, Kobayashi and coworkers reported trends in the TD-DFT spectra of 17 Zn (II) porphyrinoids [J. Am. Chem. Soc. 2005; 127: 17697] that were analyzed using Michl's perimeter model as part of a study of the anomalous magnetic circular dichroism (MCD) spectroscopy of zinc tetraphenyltetraacenaphthoporphyrin. In recent years, it has become increasingly clear that TD-DFT calculations with the commonly used hybrid B3LYP exchange-correlation functional of the Gaussian software package are problematic in the B-band region of porphyrinoid spectra, since the degree of configurational interaction between the B and higher energy ππ* state appears to be significantly overestimated. The CAM-B3LYP functional is now often preferred for analyzing the optical properties of porphyrinoids, since it includes a long-range correction of the exchange potential, which incorporates an increasing fraction of Hartree–Fock (HF) exchange as the interelectronic separation increases, making it better suited for studying compounds where there is significant charge transfer in the electronic excited states. The trends in the TD-DFT calculations are reexamined with a wider range porphyrinoid compounds including several with pyrazino moieties and are found to provide a closer agreement with the experimental in the B-band region for complexes such as zinc tetraphenylporphyrin and phthalocyanine.
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- Date Issued: 2014
Understanding food security in a perfect storm: an ecosystem services approach
- Authors: Poppy, G M , Chiotha, S , Eigenbrod, Felix , Harvey, Celia A , Honza´k, M , Hudson, Malcolm D , Jarvis, A , Madise, Nyovani J , Schreckenberg, Kate , Shackleton, Charlie M , Villa, F , Dawson, Terrence P
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/398423 , vital:69410 , xlink:href="https://doi.org/10.1098/rstb.2012.0288"
- Description: Achieving food security in a ‘perfect storm’ scenario is a grand challenge for society. Climate change and an expanding global population act in concert to make global food security even more complex and demanding. As achieving food security and the millennium development goal (MDG) to eradicate hunger influences the attainment of other MDGs, it is imperative that we offer solutions which are complementary and do not oppose one another. Sustainable intensification of agriculture has been proposed as a way to address hunger while also minimizing further environmental impact. However, the desire to raise productivity and yields has historically led to a degraded environment, reduced biodiversity and a reduction in ecosystem services (ES), with the greatest impacts affecting the poor. This paper proposes that the ES framework coupled with a policy response framework, for example Driver-Pressure-State-Impact-Response (DPSIR), can allow food security to be delivered alongside healthy ecosystems, which provide many other valuable services to humankind. Too often, agro-ecosystems have been considered as separate from other natural ecosystems and insufficient attention has been paid to the way in which services can flow to and from the agro-ecosystem to surrounding ecosystems. Highlighting recent research in a large multi-disciplinary project (ASSETS), we illustrate the ES approach to food security using a case study from the Zomba district of Malawi.
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- Date Issued: 2014
Unsymmetrically substituted nickel triazatetra-benzcorrole and phthalocynanine complexes
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189818 , vital:44934 , xlink:href="https://doi.org/10.1007/s10895-013-1317-4"
- Description: We report on the design and application of fluorescent nanoprobes based on the covalent linking of L-glutathione-capped CdSe@ZnS quantum dots (QDs) to newly synthesized unsymmetrically substituted nickel mercaptosuccinic acid triazatetra-benzcorrole (3) and phthalocyanine (4) complexes. Fluorescence quenching of the QDs occurred on conjugation to complexes 3 or 4. The nanoprobes were selectively screened in the presence of different cations and Hg2+ showed excellent affinity in “turning ON” the fluorescence of the nanoprobes. Experimental results showed that the sensitivity of QDs-4 towards Hg2+ was much higher than that of QDs-3 nanoprobe. The mechanism of reaction has been elucidated based on the ability of Hg2+ to coordinate with the sulphur atom of the Ni complex ring and apparently “turn ON” the fluorescence of the linked QDs.
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- Date Issued: 2014
Voltammetric investigation of complex growth media at a bare glassy carbon electrode: a case study of oxytetracycline
- Authors: Kruid, Jan , Fogel Ronen , Limson, Janice
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431206 , vital:72753 , xlink:href="https://doi.org/10.1016/j.electacta.2013.08.188"
- Description: Reports regarding the voltammetric properties of microbiological growth media are scarce in the literature and limited focus has been placed towards the application of electroanalysis for analyte monitoring in these complex media. This work aims to investigate the viability of voltammetry as a quantification method for analytes in microbiological growth media, using oxytetracycline (OTC) as a model analyte. Analysis of both commercially available and laboratory prepared growth media indicated the presence of interfering media components which produced anodic peaks at potentials ranging from ∼+0.85 V to ∼+1.30 V (vs. Ag/AgCl) under acidic conditions and ∼+0.62 V to ∼+1.35 V (vs. Ag/AgCl) under neutral pH. These peaks were identified as originating from proteinaceous components of growth media and correlated to the presence of peptone, malt extract and yeast extract. Electrochemical impedance spectroscopy demonstrated significant increases in the charge transfer resistance for Fe(CN)63−/4− redox probes at glassy carbon electrodes in the presence of peptone-comprised media (130.3 Ω) compared to media-free buffer (50.4 Ω). Adsorption of the aforementioned media components to the electrode surface thus contributes to analytical interference through faradaic and non-faradaic processes. By adapting the growth media for analyte detection purposes, this study proves the feasibility of detecting OTC, as well as the use of dilution of the media to further decrease the interferent effects of growth media. A 50-fold dilution of the media provided a 96.7% recovery of the OTC peak current at 20 μM concentration. The empirical detection limit of OTC in 50-fold diluted media was determined to be 0.5 μM, which makes it applicable to current industrial OTC fermentation processes.
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- Date Issued: 2014