Exploring contradictions and absences in mobilizing ‘learning as process' for sustainable agricultural practices
- Authors: Pesanayi, Tichaona
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437008 , vital:73323 , ISBN 9781315660899 , https://www.routledge.com/Critical-Realism-Environmental-Learning-and-Social-Ecological-Change/Price-Lotz-Sistka/p/book/9780367597689
- Description: Water is a fascinating, life-giving being. It flows. It cuts into the earth to create its passage by finding the places where the earth will give. As it meanders it passes through many different contexts, whether at a fastrush-full-blown flood or the trickle of an underground desert stream. It does not demand that the space it moves through is homogenous. It adapts to whatever terrain it finds itself journeying through. Human creatures, dependent as they are on water for their own beings and for life, flock to water like flies to food. We build our cities, our factories and homes on the banks and corners of rivers and draw and drink and use (and abuse) water. We throw in and we take out and the river keeps going until sometimes it doesn’t. Then we worry. Sometimes it is not the lack of flow that worries us but the fact that when we drink it babies become sick, some die and this causes a stir. In South Africa this security, or lack of it, is embedded in the political historical landscape of this land. Water is classified as scarce. Our rainfall is low in comparison to other countries. In South Africa, during apartheid this scarce resource was not avail able in equal measure to all. The rulers of apartheid South Africa were farmers and miners. They were of British decent, sent to farm the new colony. They were also descended from first colonial settlers arriving from the Nether-lands and then Germany, known colloquially as the Boers. South Africa was divided and redivided until in 1948 the Boers gained independence from British rule and finished the job that the British had started by legalizing the separation of races. Farming was still core to the Boer way of life and this is reflect-ed in the laws that dictated resource use and management, such as the 1956 Water Act No. 54 (RSA, 1956) which gave riparian rights to those that owned land. Water was also subsi-dized to boost the economy, particularly for the large mines, and parastatals such as Eskom (Byrnes, 1996). Water was not only used to ensure that the economy of white South Africa flourished, it also was the landmark of division.
- Full Text:
- Date Issued: 2015
Exploring critical realist insights into transformative environmental learning processes in contexts of social-ecological risk
- Authors: Schudel, Ingrid J
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437045 , vital:73326 , ISBN 9781315660899 , https://www.routledge.com/Critical-Realism-Environmental-Learning-and-Social-Ecological-Change/Price-Lotz-Sistka/p/book/9780367597689
- Description: Environment and sustainability are continually recognized for significance to the future of planetary well-being. But the com-plex, cross-cutting transversal nature and associated ‘new-ness’1 of environment and sustainability concerns within edu-cation and training systems raise a number of challenges for education and training systems. In this chapter I explore how critical realist dialectics can help to more fully explain the ab-sence of intermediate pathways in the environment and sus-tain able development ‘sector’ in South Africa and through this analysis raise opportunities for creating more seamless envi-ronmental learning pathways into green jobs, enhancing social justice potential and public good concerns. The chapter situ-ates the discussion within the South African policy discourse of meaningful learning pathways (DHET, 2010) through a study of two priority scarce skills occupations in the environmental sector (environmental scientist and environmental technician). This is used as an example to illustrate systemic disjunctures that demonstrate how environmental learning pathways in and for sustain able development emerge. Using a critical realist lens to understand the absences that denote a relationship away from being allows the chapter to conceptualize absence as central to the real and hence to being (Lotz-Sisitka and Ramsarup, 2012; Bhaskar, 1993). Privileging absence allows me to develop a vantage point that connects being to becom-ing and hence underlines the intent for change inherent within this research. Norrie (2010, p. 28) states that ‘understanding change as a process of absenting of absences as well as the absenting of those structural constraints that keep absences in place . . . lies at the core of change’.
- Full Text:
- Date Issued: 2015
Facile synthesis, spectroscopic and electrochemical properties, and theoretical calculations of porphyrin dimers with a bridging amide-bonded xanthene moiety
- Authors: Liang, Xu , Xu, Li , Li, Minzhi , Mack, John , Stone, Justin , Nyokong, Tebello , Jiang, Yu , Kobayashi, Nagao , Zhu, Weihua
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241390 , vital:50935 , xlink:href="https://doi.org/10.1142/S1088424615500492"
- Description: A free base porphyrin dimer bridged by a flexible amide-bonded xanthene moiety and its binuclear zinc(II) complex zinc(II) complex were synthesized and characterized. Structural characterization by MS and 1H NMR spectroscopy confirmed the bridged porphyrin dimer structure. The properties of the dimers were characterized by IR, UV-visible absorption, fluorescence and magnetic circular dichroism (MCD) spectroscopy, and electrochemistry studies. Theoretical calculations were carried out to analyze the electronic structures of porphyrin dimers with a bridging amide-bonded xanthene moiety.
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- Date Issued: 2015
Fluorescence behavior and singlet oxygen generating abilities of aluminum phthalocyanine in the presence of anisotropic gold nanoparticles
- Authors: Mthethwa, Thandekile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193598 , vital:45351 , xlink:href="https://doi.org/10.1016/j.jlumin.2014.09.005"
- Description: Gold nanoparticles (spheres, rods and bipyramids) were synthesized. The nanocrystals were characterized by UV–visible spectrometry, transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The as prepared gold nanoparticles were then conjugated to a quaternized 2,(3)-tetra [2-(dimethylamino) ethanethio] substituted Al(OH) phthalocyanine (complex 1). The conjugation of phthalocyanines with gold nanoparticles resulted in a decrease in the fluorescence quantum yields and lifetimes. Conversely, an increase in the singlet oxygen quantum yields was observed for the conjugated complex 1 in the presence of AuNPs.
- Full Text:
- Date Issued: 2015
Fluorescence behavior and singlet oxygen generating abilities of aluminum phthalocyanine in the presence of anisotropic gold nanoparticles
- Authors: Mthethwa, Thandekile , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189865 , vital:44941 , xlink:href="https://doi.org/10.1016/j.jlumin.2014.09.005"
- Description: Gold nanoparticles (spheres, rods and bipyramids) were synthesized. The nanocrystals were characterized by UV–visible spectrometry, transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The as prepared gold nanoparticles were then conjugated to a quaternized 2,(3)-tetra [2-(dimethylamino) ethanethio] substituted Al(OH) phthalocyanine (complex 1). The conjugation of phthalocyanines with gold nanoparticles resulted in a decrease in the fluorescence quantum yields and lifetimes. Conversely, an increase in the singlet oxygen quantum yields was observed for the conjugated complex 1 in the presence of AuNPs.
- Full Text:
- Date Issued: 2015
Fluorescence Behaviour of an Aluminium Octacarboxy Phthalocyanine-NaYGdF 4
- Authors: Taylor, Jessica , Litwinski, Christian , Nyokong, Tebello , Antunes, Edith M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189503 , vital:44852 , xlink:href="https://doi.org/10.1007/s10895-015-1539-8"
- Description: Using a methanol assisted thermal decomposition approach, sphere shaped NaYGdF4:Yb/Er upconversion nanoparticles (UCNPs) were successfully synthesized. The chemical, spectroscopic and fluorescence properties of the UCNPs were fully characterized. Characteristic upconversion fluorescence emissions were produced by the NPs in the green, red and NIR regions and the NPs were also shown to possess paramagnetic properties. The influence of the UCNPs on the spectroscopic and fluorescence properties of an aluminium octacarboxy phthalocyanine AlOCPc was investigated. Covalent conjugation to an AlOCPc resulted in a large blue shift of the phthalocyanine’s Q band, which was accompanied by a decrease in the Pc’s fluorescence lifetime in DMSO. By combining the phthalocyanine and upconversion nanoparticle, we present a system capable of multimodal imaging, using both the upconversion nanoparticle’s and phthalocyanine’s emission, and magnetic resonance imaging (as a result of doping the upconversion nanoparticles with Gd3+ ions).
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- Date Issued: 2015
Food on the Table: Human Responses and Changing Coastal Fisheries in Solomon Islands
- Authors: Albert, Simon , Aswani, Shankar , Fisher, Paul L , Albert, Joelle
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421887 , vital:71893 , xlink:href="https://doi.org/10.1371/journal.pone.0130800"
- Description: Globally the majority of commercial fisheries have experienced dramatic declines in stock and catch. Likewise, projections for many subsistence fisheries in the tropics indicate a dramatic decline is looming in the coming decades. In the Pacific Islands coastal fisheries provide basic subsistence needs for millions of people. A decline in fish catch would therefore have profound impacts on the health and livelihoods of these coastal communities. Given the decrease in local catch rates reported for many coastal communities in the Pacific, it is important to understand if fishers have responded to ecological change (either by expanding their fishing range and/or increasing their fishing effort), and if so, to evaluate the costs or benefits of these responses. We compare data from fish catches in 1995 and 2011 from a rural coastal community in Solomon Islands to examine the potentially changing coastal reef fishery at these time points. In particular we found changes in preferred fishing locations, fishing methodology and catch composition between these data sets. The results indicate that despite changes in catch rates (catch per unit effort) between data collected in 2011 and 16 years previously, the study community was able to increase gross catches through visiting fishing sites further away, diversifying fishing methods and targeting pelagic species through trolling. Such insight into local-scale responses to changing resources and/or fisheries development will help scientists and policy makers throughout the Pacific region in managing the region’s fisheries in the future.
- Full Text:
- Date Issued: 2015
Genetic and biological characterisation of a novel Plutella xylostella granulovirus, PlxyGV-SA
- Authors: Abdulkadir, Fatima , Knox, Caroline M , Marsberg, Tamryn , Hill, Martin P , Moore, Sean D
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417971 , vital:71498 , xlink:href="https://doi.org/10.1007/s10526-015-9666-3"
- Description: Plutella xylostella granulovirus (PlxyGV) has been isolated from insect populations in many countries and is considered a potential biopesticide for sustainable control of P. xylostella (L.) (Lepidoptera: Plutellidae). Several PlxyGV isolates have been genetically characterised, and the full genome sequence of PlxyGV-Japan is available for comparison with novel isolates. A South African PlxyGV was recently recovered from an overcrowded laboratory P. xylostella colony and identified as a genetically distinct isolate by sequencing of the granulin gene and restriction endonuclease (REN) analysis of genomic DNA. In this report, PlxyGV-SA was further characterised by PCR amplification and sequencing of egt, lef-8 and lef-9 genes, and several amino acid substitutions were observed. The PstI REN profile of PlxyGV-SA was different from that of PlxyGV-Japan in terms of band size and number, thereby confirming its novel genetic identity. Surface dose bioassays showed that PlxyGV-SA is pathogenic to neonate but not late instar larvae at the same and higher virus doses, indicating that a biopesticide should be targeted at early larval stages in the field.
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- Date Issued: 2015
Host searching and oviposition behaviour of Agathis bishopi (Hymenoptera: Braconidae), a larval parasitoid of false codling moth, Thaumatotibia leucotreta (Lepidoptera: Tortricidae): a potential proxy indicator for fruit infestation
- Authors: Zimba, Kennedy J , Heshula, LU , Moore, Sean D , Hill, Martin P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/407019 , vital:70330 , xlink:href="https://hdl.handle.net/10520/EJC195073"
- Description: Agathis bishopi (Nixon) (Hymenoptera: Braconidae)is an arrhenotokous larval endoparasitoid of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) (Gendall 2007; Hofmeyr et al. 2015) commonly known as false codling moth (FCM), a major pest of citrus in South Africa (Moore et al. 2004; Malan et al. 2011). Under field conditions, A. bishopi was identified attacking more than 34% of FCM larvae in fruit, showing good biocontrol potential (Gendall 2007). Preference by A. bishopi for parasitising the early instars of its concealed host suggests that the parasitoid has strong natural host location ability (Sishuba 2003; Gendall 2007).
- Full Text:
- Date Issued: 2015
Implementing uncertainty analysis in water resources assessment and planning
- Authors: Hughes, Denis A , Mohobane, T , Mallory, S
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438281 , vital:73448 , ISBN 978-1-4312-0629-2 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2056-1-14.pdf
- Description: The main objective of the project was to contribute to the incorporation of uncer-tainty assessments in practical water resource decision-making in South Africa. There are three main components to this objective. The first is the quantification of realistic levels of uncertainty that are as low as possible given the available infor-mation (reducing uncertainty). The second is the availability of tools to implement uncertainty analysis across the broad spectrum of data analysis and modelling plat-forms that form part of practical water resources assessment (including hydrologi-cal and water resources yield models). The third relates to the issue of using uncer-tain information in the process of making decisions about the design, development or operation of water resources systems. The latter includes social, political and economic uncertainties as well as the hydrological uncertainties that are directly addressed in this report. None of these are independent and all are associated with the fundamental issue that all of the role players should understand the key con-cepts of uncertainty and that virtually all of the information we use to make deci-sions is uncertain. One of the major challenges in this project as well as the previous WRC-supported project on uncertainty methods, was the lack of understanding of some of the key issues, or a lack of appreciation of the importance of uncertainty in all water resources decision-making.
- Full Text:
- Date Issued: 2015
Improved triplet state parameters for indium octacarboxy phthalocyanines when conjugated to quantum dots and magnetite nanoparticles
- Authors: Tshangana, Charmaine , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189337 , vital:44838 , xlink:href="https://doi.org/10.1016/j.molstruc.2015.02.040"
- Description: Fe3O4 magnetic nanoparticles (MNPs) and glutathione (GSH) capped CdSe@ZnS quantum dots (QDs) were separately coordinated to indium octacarboxy phthalocyanine (InPc(COOH)8) to form ClInPc(COOH)8–MNPs and ClInPc(COOH)8–GSH–CdSe@ZnS, respectively. The photophysical parameters (triplet state and fluorescence quantum yields and lifetimes) were determined for the conjugates. The triplet quantum yields increased from ΦT = 0.49 for InPc(COOH)8 alone to ΦT = 0.61 and 0.56 for InPc(COOH)8 in the conjugates: ClInPc(COOH)8–MNPs and ClInPc(COOH)8–GSH–CdSe@ZnS, respectively. The lifetimes also became longer for the conjugates compared to Pc alone.
- Full Text:
- Date Issued: 2015
Integrating local knowledge and forest surveys to assess Lantana camara impacts on indigenous species recruitment in Mazeppa Bay, South Africa
- Authors: Jevon, Tui , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180843 , vital:43650 , xlink:href="https://doi.org/10.1007/s10745-015-9748-y"
- Description: Invasive alien species have variable impacts on peoples’ livelihoods, plant communities and species at the local scale. Local people often have deeper insights into and experiences of these impacts than can be measured by scientific surveys. Here we examine the impacts of Lantana camara on the recruitment of indigenous forest species, many of which are used by local people. We integrate findings from conversations with elderly respondents with standard ecological surveys. Both sources of information indicate that the increasing presence of Lantana suppresses the number and species richness of recruits of indigenous forest species, which may retard forest succession. Dense thickets of Lantana also restricted access to non-timber forest products and species of cultural significance. The origin and date of the Lantana introduction in the area was identified by respondents as the 1960s and it escaped into the wild in the early 1970s. These findings can be incorporated into locally based management considerations.
- Full Text:
- Date Issued: 2015
Introduction: the need to understand the ecological sustainability of non-timber forest products harvesting systems
- Authors: Shackleton, Charlie M , Ticktin, Tamara , Pandey, Ashok K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433683 , vital:72994 , ISBN 9781317916130 , https://www.taylorfrancis.com/chapters/edit/10.4324/9781315851587-2/introduction-charlie-shackleton-tamara-ticktin-ashok-pandey
- Description: The importance of non-timber forest products (NTFPs) in rural livelihoods in developing countries has become widely acknowledged over the last decade or so within the research and, increasingly, policy arenas, on the basis of numerous studies from around the world. Indeed, there has been a tenfold increase in the annual number of research papers published over the last 20 years (Figure 1.1). Most of these studies are from developing countries, but they do include developed countries (e.g. Kim et al. 2012, Poe et al. 2013, Sténs and Sandström 2013). Additionally, most are from rural areas, albeit with a smattering from urban settings (e.g. Kilchling et al. 2009, Poe et al. 2013, Kaoma and Shackleton 2014), although with increasing urbanization this distinction is blurred with significant markets for rural NTFPs imported into towns and cities (Lewis 2008, Padoch et al. 2008, McMullin et al. 2012). Two pertinent findings of many of these studies is that NTFPs generally contribute in many different ways to local livelihoods (see Chapter 2) and that when translated into income terms many households earn a significant proportion of their income (cash and/or non-cash) from NTFPs (Shackleton et al. 2007, Angelsen et al. 2014). In other words, they are not simply minor products of little value, but rather they are vital components of livelihoods, and in some instances, of local and regional economies. This requires that they, and the land on which they are found, are managed in a responsible manner to ensure that these livelihood benefits continue to accrue to rural, and often impoverished, people.
- Full Text:
- Date Issued: 2015
Iodine-Doped Cobalt Phthalocyanine Supported on Multiwalled Carbon Nanotubes for Electrocatalysis of Oxygen Reduction Reaction
- Authors: Nyoni, Stephen , Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189434 , vital:44846 , xlink:href="https://doi.org/10.1002/elan.201400499"
- Description: 4-(4,6-Diaminopyrimidin-2-ylthio) phthalocyaninatocobalt(II) (CoPyPc) was iodine doped, and its electrocatalytic properties explored. Physical characterization techniques such as UV-vis, X-ray photoelectron, electron paramagnetic resonance and infra-red spectroscopy were used. Cyclic voltammetry, electrochemical impedance spectroscopy and rotating disk electrode were used for electrochemical characterization of electrodes modified with the prepared phthalocyanine and its nanocomposites. The electrocatalytic effect of a new iodine-doped cobalt phthalocyanine derivative supported on multiwalled carbon nanotubes was then investigated towards oxygen reduction reaction. The electrocatalytic activity of the iodine-doped cobalt phthalocyanine was found to be superior in terms of current over the undoped phthalocyanine nanocomposite.
- Full Text:
- Date Issued: 2015
Key critical realist concepts for environmental educators
- Authors: Price, Leigh
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/437022 , vital:73324 , ISBN 9781315660899 , https://www.routledge.com/Critical-Realism-Environmental-Learning-and-Social-Ecological-Change/Price-Lotz-Sistka/p/book/9780367597689
- Description: This chapter describes aspects of critical realism that are rele-vant to environmental educators. Critical realism acts an un-derlabourer for the sciences and the practices of human emancipation. In its underlabouring role, critical realism chal-lenges the Humean assumption that correlations (constant conjunctions) are the only way to know causation and offers an alternative, which is that causation is based on the layered, deep nature of reality (the real, actual and empirical). Critical realism explains how higher levels of being are emergent from lower levels; therefore society (structure) is emergent from the activities of people (agency). Environmental educators should take an interest in structure and agency, not least because cer-tain approaches offer questionable power strategies to people and particularly governments. One consequence of the critical realist version of causation is that it becomes possible to en-visage an environmental ethics that is based on an axiology that is neither absolutist nor relativist. To provide a full enough account of causation to achieve one’s purposes, Bhaskar has suggested a model, the seven laminations of scale. Bhaskar also differentiates between the transitive and intransitive realms and explains that there are questionable ideological advantages to failing to make this distinction. The intransi-tive/transitive realms have implications for our use of catego-ries: critical realism explains how we can use categories to prevent oppression. Critical realism also argues against a purely positive, rather than a negative, account of the dialectic: thus change is absenting the constraints on absenting ab-sences. Contrary to a frequent assumption made by both non-critical realists and critical realists alike, critical realism is not a return to positivism.
- Full Text:
- Date Issued: 2015
Local wood demand, land cover change and the state of Albany thicket on an urban commonage in the Eastern Cape, South Africa
- Authors: Stickler, M M , Shackleton, Charlie M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/398343 , vital:69402 , xlink:href="https://doi.org/10.1007/s00267-014-0396-6"
- Description: Understanding the rates and causes of land-use change is crucial in identifying solutions, especially in sensitive landscapes and ecosystems, as well as in places undergoing rapid political, socioeconomic or ecological change. Despite considerable concern at the rate of transformation and degradation of the biodiversity-rich Albany Thicket biome in South Africa, most knowledge is gleaned from private commercial lands and state conservation areas. In comparison, there is limited work in communal areas where land uses include biomass extraction, especially for firewood and construction timber. We used aerial photographs to analyze land use and cover change in the high- and low-use zones of an urban commonage and an adjacent protected area over almost six decades, which included a major political transition. Field sampling was undertaken to characterize the current state of the vegetation and soils of the commonage and protected area and to determine the supply and demand for firewood and construction timber. Between the 1950s and 1980s, there was a clear increase in woody vegetation cover, which was reversed after the political transition in the mid-1990s. However, current woody plant standing stocks and sustainable annual production rates are well above current firewood demand, suggesting other probable causes for the decline in woody plant cover. The fragmentation of woody plant cover is paralleled by increases in grassy areas and bare ground, an increase in soil compaction, and decreases in soil moisture, carbon, and nutrients.
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- Date Issued: 2015
Meso-and axially-modified IrIIItriarylcorroles with tunable electrocatalytic properties
- Authors: Zhang, Xifeng , Wang, Yu , Zhu, Weihua , Mack, John , Soy, Rodah C , Nyokong, Tebello , Liang, Xu
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190851 , vital:45034 , xlink:href="https://doi.org/10.1016/j.molstruc.2015.02.040"
- Description: The synthesis of three A2B type Ir(III)triarylcorroles with meso-aryl substituents that provide electron donating (push) and withdrawing (pull) properties and three A3 type IrIIItriphenylcorroles with differing pyridine axial ligands is reported, along with their structural characterization. An analysis of the structure-property relationships in the optical and redox properties has been carried out by comparing their optical spectroscopy and electrochemistry to trends predicted in DFT and TD-DFT calculations. The results demonstrate that A2B type IrIIItriarylcorroles are highly efficient electrocatalyzed oxygen reduction reactions (ORRs) and that their reactivity can be modulated by modulating the electronic structure by changing the nature of the meso-substituent at the B-positions, and even axial pyridine ligands.
- Full Text:
- Date Issued: 2015
Mitochondrial STAT3 and reactive oxygen species: a fulcrum of adipogenesis?
- Authors: Kramer, Adam H , Kadye, Rose , Houseman, Pascalene S , Prinsloo, Earl
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431674 , vital:72795 , xlink:href="https://doi.org/10.1080/21623996.2015.1084084"
- Description: The balance between cellular lineages can be controlled by reactive oxygen species (ROS). Cellular differentiation into adipocytes is highly dependent on the production of ROS to initiate the process through activation of multiple interlinked factors that stimulate mitotic clonal expansion and cellular maturation. The signal transducer and activator of transcription family of signaling proteins have accepted roles in adipogenesis and associated lipogenesis. Non-canonical mitochondrial localization of STAT3 and other members of the STAT family however opens up new avenues for investigation of its role in the aforementioned processes. Following recent observations of differences in mitochondrially localized serine 727 phosphorylated STAT3 (mtSTAT3-pS727) in preadipocytes and adipocytes, here, we hypothesize and speculate further on the role of mitochondrial STAT3 in adipogenesis.
- Full Text:
- Date Issued: 2015
Modelling stock return volatility dynamics in selected African markets
- Authors: King, Daniel , Botha, Ferdi
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396104 , vital:69150 , xlink:href=" https://doi.org/10.1016/j.econmod.2014.11.008"
- Description: This paper examines whether accounting for structural changes in the conditional variance process, through the use of Markov-switching models, improves estimates and forecasts of stock return volatility over those of the more conventional single-state (G)ARCH models, within and across selected African markets for the period 2002–2012. In the univariate portion of the paper, the performances of various Markov-switching models are tested against a single-state benchmark model through the use of in-sample goodness-of-fit and predictive ability measures. In the multivariate context, the single-state and Markov-switching models are comparatively assessed according to their usefulness in constructing optimal stock portfolios. Accounting for structural breaks in the conditional variance process, conventional GARCH effects remain important in capturing heteroscedasticity. However, those univariate models including a GARCH term perform comparatively poorly when used for forecasting purposes. In the multivariate study, the use of Markov-switching variance–covariance estimates improves risk-adjusted portfolio returns relative to portfolios constructed using the more conventional single-state models. While there is evidence that some Markov-switching models can provide better forecasts and higher risk-adjusted returns than those models which include GARCH effects, the inability of the simpler Markov-switching models to fully capture heteroscedasticity in the data remains problematic.
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- Date Issued: 2015
Multi sensor national cyber security data fusion
- Authors: Swart, Ignus , Irwin, Barry V W , Grobler, Marthie
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430393 , vital:72688 , https://www.academic-bookshop.com/ourshop/prod_3774091-ICCWS-2015-10th-International-Conference-on-Cyber-Warfare-and-Security-Kruger-National-Park-South-Africa-PRINT-ver-ISBN-978191030996.html
- Description: A proliferation of cyber security strategies have recently been published around the world with as many as thirty five strategies documented since 2009. These published strategies indicate the growing need to obtain a clear view of a country’s information security posture and to improve on it. The potential attack surface of a nation is extremely large however and no single source of cyber security data provides all the required information to accurately describe the cyber security readiness of a nation. There are however a variety of specialised data sources that are rich enough in relevant cyber security information to assess the state of a nation in at least key areas such as botnets, spam servers and incorrectly configured hosts present in a country. While informative both from an offensive and defensive point of view, the data sources range in a variety of factors such as accuracy, completeness, representation, cost and data availability. These factors add complexity when attempting to present a clear view of the combined intelligence of the data.
- Full Text:
- Date Issued: 2015