Ontogenetic and seasonal shifts in the diet of Diplodus cervinus hottentotus (Pisces: Sparidae) in southern Angola
- Authors: Winkler, Alexander C , Santos, Carmen V D , Potts, Warren M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125452 , vital:35784 , https://doi.10.2989/1814232X.2014.951392
- Description: Fishes of the family Sparidae occupy a diverse range of trophic niches, from herbivores to generalist omnivores and specialist predators (Hanel and Tsigenopoulos 2011). Feeding specialisation in this family is facilitated by diversity in tooth type and anterior jaw arrangement (Vandewalle et al. 1995). Other fish families, such as Cyprinidae and Labridae, have developed crushing pharyngeal teeth to process their food. Sparids, however, have retained a simple pharyngeal tooth arrangement and instead have developed molariform teeth to process hard-shelled molluscs and invertebrate prey. Hanel and Tsigenopoulos (2011) suggested that this alternate strategy is a major factor facilitating the trophic diversity in sparid fishes.
- Full Text:
- Date Issued: 2014
The role of reflection and new ideas in the advancement of a strong and responsive democratic system
- Authors: Badat, Saleem
- Date: 2013-09-25
- Language: English
- Type: Text
- Identifier: vital:7921 , http://hdl.handle.net/10962/d1016471
- Full Text:
- Date Issued: 2013-09-25
Knockdown of Hop downregulates RhoC expression, and decreases pseudopodia formation and migration in cancer cell lines:
- Authors: Willmer, Tarryn , Contu, Lara , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165196 , vital:41217 , DOI: 10.1016/j.canlet.2012.09.021
- Description: The Hsp90/Hsp70 organising protein (Hop) is a co-chaperone that mediates the interaction of Hsp90 and Hsp70 molecular chaperones during assembly of Hsp90 complexes in cells. Formation of Hsp90 complexes is a key intermediate step in the maturation and homeostasis of oncoproteins and several hormone receptors. In this paper, we demonstrate that knockdown of Hop decreased migration of Hs578T and MDA-MB-231 breast cancer cells. Hop was identified in isolated pseudopodia fractions; it colocalised with actin in lamellipodia, and co-sedimented with purified actin in vitro. Knockdown of Hop caused a decrease in the level of RhoC GTPase, and significantly inhibited pseudopodia formation in Hs578T cells. Our data suggest that Hop regulates directional cell migration by multiple unknown mechanisms.
- Full Text:
- Date Issued: 2013
Section 40 of the Consumer Protection Act in comparative perspective: aantekeninge
- Authors: Glover, Graham B
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/70527 , vital:29672 , https://hdl.handle.net/10520/EJC144971
- Description: The purpose of this comment is to consider some of the problems with how we are to understand the role and purpose of section 40 of South Africa's Consumer Protection Act 68 of 2008 when viewed from a doctrinal perspective. Section 40 has the heading "Unconscionable conduct", and contains three subsections.
- Full Text: false
- Date Issued: 2013
Inter-seasonal persistence and size-structuring of two minnow species within headwater streams in the Eastern Cape, South Africa
- Authors: Kadye, Wilbert T , Booth, Anthony J
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124866 , vital:35705 , https://doi.10.1111/j.1439-0426.2012.02027.x
- Description: This study examined temporal variation in population dynamics and size structuring of two cyprinid minnows, Pseudobarbus afer and Barbus anoplus, in relation to their proximate physical habitats. Population estimates were determined using three-pass depletion sampling during both summer and winter. The habitats were characterised by seasonal variation in all physico-chemical conditions and spatial variation in substrata compositions. Whereas significant differences in population size were noted between seasons for B. anoplus, no differences were found between seasons for density and capture probability for either species. An increase in boulders was associated with increase in population size and density for P. afer; for B. anoplus, increased percentages of bedrock and bank vegetation were associated with an increase in population size and probability of capture, respectively. According to Canonical Correspondence Analysis, size structuring in P. afer was explained predominantly by seasonality, with smaller length classes associated with the seasonal variable of summer, while larger length classes were associated with pH that was higher in winter. By comparison, for B. anoplus, the habitat variables – bank vegetation and bedrock – accounted for much of the explained variance for size structuring. Recruitment appeared to be the major driver of size structuring for the two species; refugia, especially boulders and bank vegetation, also appeared to be important. Overall, the two species were adapted to the headwater streams that were generally variable in environmental conditions. Potential invasions by non-native invasive fishes that occur within the mainstream habitats threaten these two species. Efforts should continue to protect these minnows from such invasions by constructing barriers to upstream migration of non-native fishes into these headwater habitats.
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- Date Issued: 2012
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: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124921 , vital:35710 , https://doi.10.3377/004.048.0225
- Description: African sharptooth catfish Clarias gariepinus (Burchell, 1822) is a widely distributed fish that has now invaded water bodies in South America, Eastern Europe, Asia and South Africa (Cambray 2003). In South Africa it is native as far south as the Orange-Vaal river system, but inter-basin water transfer schemes (IBWTs), illegal stocking by anglers and from aquaculture has resulted in the establishment of extralimital populations in almost all river systems (van Rensburg et al. 2011). Within the Eastern Cape Province, C. gariepinus has invaded the Great Fish and Sundays rivers through IBWTs, that connect the Orange River to the Great Fish River and then to the Sundays River system which flows directly into Darlington Dam (Kadye & Booth 2013a) (Fig. 1). Soon after the completion of the IBWTs sharptooth catfish were recorded in Grassridge Dam in 1976 (Laurenson & Hocutt 1985), and later from Darlington Dam in 1981 (Scott et al. 2006). Although Cambray & Jubb (1977) are of the opinion that the species was translocated prior to the IBWT connection, there is now a permanent corridor between the Orange River and its receiving river systems that can facilitate the continued introduction of non-native Orange River fishes and other aquatic biota.
- Full Text:
- Date Issued: 2012
Pre-concentration of toxic metals using electrospun amino-functionalized nylon-6 nanofibre sorbent
- Authors: Darko, G , Sobola, A , Adewuyi, Sheriff , Okonkwo, J O , Torto, N
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6571 , http://hdl.handle.net/10962/d1004134
- Description: This paper presents a new approach for pre-concentrating toxic metals (As, Cd, Ni and Pb) in aqueous environments using an amino-functionalized electrospun nanofibre sorbent. The sorbent, composed of nanofibres of average diameter 80 ± 10 nm and specific surface area of 58m2 g–1, exhibited fast adsorption kinetics (<20 min) for As, Cd, Ni and Pb. The optimalpHfor the uptake of As, Cd, Ni and Pb were 5.5, 6.0, 6.5 and 11, respectively. The adsorption process best fitted the Freundlich isothermand followed the first-order kinetics. The highest pre-concentration achieved using the sorbent was 41.99 (Ni in treated wastewater). The capacity of the sorbent to pre-concentrate the toxic metals was compared with those of aqua regia and HNO3+H2O2 digestions. The pre-concentration factors achieved for Cd in river water samples can be ranked as aqua regia digestion (0.73) > adsorption (0.34)>HNO3+H2O2 (0.23) digestion.Asimilar trend was observed for Ni in river water as well as Ni andCdin tap water samples. Pb ions in the river water samples were pre-concentrated slightly better using the two digestion methods pre-concentration factors ~22) compared to adsorption method (pre-concentration factor ~21). The use of the electrospun amino-functionalized nanofibre sorbent presentsanefficientand cost-effective alternative for pre-concentration of toxic metals inaqueousenvironments.
- Full Text:
- Date Issued: 2012
The nature and quality of the mathematical connections teachers make:
- Authors: Mhlolo, Michael K , Schäfer, Marc , Venkat, Hamsa
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140893 , vital:37927 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC120887
- Description: Current reforms in mathematics education emphasise the need for pedagogy because it offers learners opportunities to develop their proficiency with complex high-level cognitive processes. One has always associated the ability to make mathematical connections, together with the teacher's role in teaching them, with deep mathematical understanding. This article examines the nature and quality of the mathematical connections that the teachers' representations of those connections enabled or constrained. The researchers made video recordings of four Grade 11 teachers as they taught a series of five lessons on algebra-related topics. The results showed that the teachers' representations of mathematical connections were either faulty or superficial in most cases. It compromised the learners' opportunities for making meaningful mathematical connections. The researchers concluded by suggesting that helping teachers to build their representation repertoires could increase the effectiveness of their instructional practices.
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- Date Issued: 2012
The use of response surface methodology to evaluate the impact of level 2 SUPAC–IR changes on the in vitro release of metronidazole and ranitidine from a fixed-dose combination tablet
- Authors: King’ori, Loti D , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6391 , http://hdl.handle.net/10962/d1006313
- Description: The purpose of this study was to evaluate the effect of different levels of disintegrant (croscarmellose sodium, CCS), binder (polyvinylprrolidone K30, PVP–K30), and lubricant (magnesium stearate) on the in vitro release of metronidazole (MTZ) and rantidine (RTD) from a solid oral fixed-dose combination tablet. The excipient levels investigated were Level 2 changes in component and composition described in the Scale-Up and Post Approval Changes for Immediate Release (SUPAC–IR) guidance (1). Batches of tablets (1000 units) were manufactured by wet granulation using a Saral high-shear mixer granulator and a Manesty B3B rotary tablet press. Weight uniformity, friability, and disintegration of all tablets were assessed, and all batches complied with compendial specifications. The amount of drug released (Q) at ten minutes was dependent on the levels of CCS in the formulation, and the effect of PVP–K30 and magnesium stearate was dependent on the levels of CCS. Synergistic interactions between independent variables were observed for the Q10 value for RTD, whereas PVP–K30 and magnesium stearate exhibited an antagonistic effect on the Q10 values for MTZ and RTD. The use of response surface methodology facilitated an investigation into the effect of Level 2 component and composition changes, as described in SUPAC–IR, on the in vitro release of MTZ and RTD from a fixed-dose combination (FDC) solid oral dosage form (SODF).
- Full Text:
- Date Issued: 2012
Towards empowering learners in a democratic mathematics classroom: to what extent are teachers' listening orientations conducive to and respectful of learners' thinking?
- Authors: Mhlolo, Michael K , Schäfer, Marc
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140882 , vital:37926 , https://0-hdl.handle.net.wam.seals.ac.za/10520/EJC129235
- Description: In an effort to make education accessible, to 'heal the divisions of the past and establish a society based on democratic values', the South African Department of Education claims that a series of mathematics reforms that has so far been introduced is underpinned by the principles of 'social justice, fundamental human rights and inclusivity'. Critics however argue that the system has remained 'undemocratic' in that those groups of learners who were supposed to be 'healed' continue to underperform and hence be disempowered. In this study, we conceptualised a democratic and mathematically empowering classroom as one that is consistent with the principle of inclusivity and in which a hermeneutic listening orientation towards teaching promotes such a democratic and mathematically empowering learning environment. We then worked with three different orientations teachers might have towards listening in the mathematics classroom: evaluative, interpretive and hermeneutic. We then used these orientations to analyse 20 video-recorded lessons with a specific focus on learners' unexpected contributions and how teachers listened and responded to such contributions. The results were consistent with the literature, which shows that teachers tend to dismiss learners' ways of thinking by imposing their own formalised constructions.
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- Date Issued: 2012
English Method 4: EDL 322
- Authors: Botha, E K , Mdaka, V N
- Date: 2012-01
- Language: English
- Type: Examination paper
- Identifier: vital:18298 , http://hdl.handle.net/10353/d1011305
- Description: English Method 4: EDL 322, supplementary examination January 2012.
- Full Text: false
- Date Issued: 2012-01
Introduction to Accounting: ACC 121/AAC 121
- Authors: Mnconywa, N , Mtshwelo, L , Staude, D , Lockyear, M
- Date: 2012-01
- Subjects: Accounting
- Language: English
- Type: Examination paper
- Identifier: vital:17410 , http://hdl.handle.net/10353/d1009776
- Description: Introduction to Accounting: ACC 121/AAC 121, supplementary examination January 2011.
- Full Text: false
- Date Issued: 2012-01
Use a humanizing pedagogy to assist students
- Authors: Alfred H. Makura
- Date: 2011-11
- Language: English
- Type: Newsletter
- Identifier: vital:12225 , http://hdl.handle.net/10353/d1016143
- Description: Teaching and Learning Centre Newsletter November 2011
- Full Text: false
- Date Issued: 2011-11
Academic Practices and Reasoning: APR 111
- Authors: Scott, R , Blatchford, M
- Date: 2011-07
- Language: English
- Type: Examination paper
- Identifier: vital:18261 , http://hdl.handle.net/10353/d1011257
- Description: Academic Practices and Reasoning: APR 111, examination July/August 2011.
- Full Text: false
- Date Issued: 2011-07
Accounting 1: AFA 112
- Authors: Nobuya, X , Mnconywa, N
- Date: 2011-06
- Subjects: Accounting
- Language: English
- Type: Examination paper
- Identifier: vital:17420 , http://hdl.handle.net/10353/d1009789
- Description: Accounting 1: AFA 112, June 2011, Supplementary examination.
- Full Text: false
- Date Issued: 2011-06
Introduction to Industrial Psychology: IPS 121
- Authors: Chipunza, C , Gcaza, N
- Date: 2011-02
- Subjects: Psychology, Industrial
- Language: English
- Type: Examination paper
- Identifier: vital:17486 , http://hdl.handle.net/10353/d1010461
- Description: Introduction to Industrial Psychology: IPS 121, Supplementary examination February 2011.
- Full Text: false
- Date Issued: 2011-02
Dimethylglyoxime based ion-imprinted polymer for the determination of Ni(II) ions from aqueous samples
- Authors: Rammika, M , Darko, G , Tshentu, Z , Sewry, J D , Torto, N
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6590 , http://hdl.handle.net/10962/d1004173
- Description: A Ni(II)-dimethylglyoxime ion-imprinted polymer {Ni(II)-DMG IIP} was synthesised by the bulk polymerisation method. The morphology of the Ni(II)-DMG IIP and non-imprinted polymer were observed by scanning electron microscopy and the chemical structures were evaluated by infrared spectroscopy. Selectivity of the Ni(II)-DMG IIP was studied by analysing, using an inductively coupled plasma-optical emission spectrometer, for Ni(II) ions that were spiked with varying concentrations of Co(II), Cu(II), Zn(II), Pd(II), Fe(II), Ca(II), Mg(II), Na(I) and K(I) in aqueous samples. The studies revealed Ni(II) recoveries ranging from 93 to 100% in aqueous solutions with minimal interference from competing ions. Enrichment factors ranged from 2 to 18 with a binding capacity of 120 μg∙g−1. Co(II) was the only ion found to slightly interfere with the determination of Ni(II). Selectivity studies confirmed that the Ni(II)-DMG IIP had very good selectivity, characterised by %RSD of less than 5%. The limits of detection and quantification were 3x10-4 μg∙mℓ−1 and 9x10-4 μg∙mℓ−1, respectively. The accuracy of the method was validated by analysing a custom solution of certified reference material (SEP-3) and the concentration of Ni(II) obtained was in close agreement with the certified one. The Ni(II)-DMG IIP was successfully employed to trap Ni(II) ions from a matrix of sea, river and sewage water. It is believed that the Ni(II)-DMG IIP has potential to be used as sorbent material for pre-concentration of Ni(II) ions from aqueous solutions by solid-phase extraction.
- Full Text:
- Date Issued: 2011
Diverse pollination systems of the twin-spurred orchid genus Satyrium in African grasslands
- Authors: Johnson, S.D , Peter, C.I , Ellis, A.G , Boberg, E , Botes, C , Van der Niet, T
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6558 , http://hdl.handle.net/10962/d1006025 , http://dx.doi.org/10.1007/s00606-010-0411-1
- Description: The large terrestrial orchid genus Satyrium underwent evolutionary radiations in the Cape floral region and the grasslands of southern and eastern Africa. These radiations were accompanied by tremendous diversification of the unusual twin-spurred flowers that characterize the genus, but pollination data required to interpret these patterns of floral evolution have been lacking for grassland species in the genus. Here we document pollinators, nectar properties, and levels of pollination success for 11 grassland Satyrium species in southern and south-central Africa. Pollinators of these species include bees, beetles, butterflies, hawkmoths, noctuid moths, long-proboscid flies, and sunbirds. Most species appear to be specialized for pollination by one functional pollinator group. Long-proboscid fly pollination systems are reported for the first time in Satyrium (in S. macrophyllum and a high-altitude form of S. neglectum). Floral morphology, especially spur length and rostellum structure, differs markedly among plants with different pollinators, while nectar volume, concentration, and sugar composition are fairly uniform across species. Most taxa exhibited high levels of pollination success (>50% of flowers pollinated), a trend that can be attributed to the presence of nectar in the twin spurs.
- Full Text:
- Date Issued: 2011
Ilam's Archival Revitalisation: the past five years at the International Library of African Music
- Authors: Still-Drewett, F
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6983 , http://hdl.handle.net/10962/d1006719
- Description: The International Library for African Music (ILAM) was begun in 1954 by ethnomusicologist Hugh Tracey (1903–1977). Since 2007, an active set of projects in preservation and digitisation of both sound and photographic archives have meant that this highly important archive of traditional African music has been stabilized and conserved. New outreach education projects are helping distribute the wealth of the collection back to the African people. ILAM now has a more secure future and makes seminal contributions in the fields of research, publication and education for African music. French Abstract La Bibliothèque Internationale pour la Musique Africaine (ILAM) a été établie en 1954 par l’ethnomusicologue Hugh Tracey (1903–1977). Depuis 2007, un ensemble de projets actifs dans la préservation et la numérisation des archives sonores et photographiques, a eu comme résultat que ces archives très importantes de la musique traditionnelle africaine ont été stabilisées et conservées. De nouveaux projets d’éducation et de sensibilisation aident à distribuer la richesse de cette collection à la population africaine. ILAM a maintenant un avenir plus sûr et apporte une contribution fondamentale dans les domaines de la recherche, la publication et l’enseignement de la musique africaine. German Abstract Die International Library for African Music (ILAM) wurde im Jahr 1954 durch den Musi kethnolo - gen Hugh Tracey (1903–1977) gegründet. Seit 2007 laufende Projekte zur Bestandssicherung und Digitalisierung des Schall- und Fotoarchivs helfen, dieses überaus wichtige Archiv für traditionelle afrikanische Musik zu erhalten und in seiner Existenz zu stabilisieren. Neue, nach außen wirkende Bildungsprojekte tragen dazu bei, den Reichtum der Sammlung an die afrikanische Bevölkerung zurückzugeben. Durch seine nun gesicherte Zukunft kann ILAM für die afrikanische Musik grundlegende Beiträge in Forschung, Veröffentlichung und Bildung leisten. Afrikaans Abstract Die International Library of African Music (ILAM) is in 1954 deur die etnomusikoloog, Hugh Tracey (1903–1977), gestig. Aktiewe preserverings- en digitaliseringsprojekte van beide klank- en foto-argiewe sedert 2007, het tot gevolg gehad dat hierdie hoogs belangrike argief van tradisionele Afrikamusiek gestabiliseer en bewaar kon word. Nuwe ontwikkelings-uitreikprojekte dra daartoe by dat die rykdom van hierdie versameling teruggeploeg word aan Afrika. ILAM het tans ‘n meer versekerde toekoms en lewer invloedryke bydraes op die gebied van navorsing, publikasie en opleiding in Afrikamusiek. IsiXhosa Abstract Ithala lehlabathi lomculo wase-Afrika, i- International Library for African Music (ILAM) laqalwa ngo- 1954 yingcali yomculo weentlanga ngeentlanga, uHugh Tracey (1903–1977). Ukususela ngo-2007 umsebenzi wokulondoloza nokugcina ngekhompyutha isandi seengoma kwakunye neefoto uthetha ukuba le mbali ibalulekileyo kumculo we-Afrika wemveli iqiniselwe kwaye igcinwe ngononophelo. Iiprojekti ezintsha zokolulela isandla kwabanye abantu ziyanceda ekusasazeni le ndyebo kwabo bantu isuka kubo, ama-Afrika. Ngoku i-ILAM inekamva elingagunqgiyo kwaye inegalelo elibonakalayo kuphando, upapasho nemfundo ngomculo wase-Afrika.
- Full Text:
- Date Issued: 2011
Selective removal of chromium (VI) from sulphates and other metal anions using an ion-imprinted polymer
- Authors: Pakade, V , Cukrowska, E , Darkwa, J , Torto, N , Chimuka, L
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6588 , http://hdl.handle.net/10962/d1004171
- Description: A linear copolymer was prepared from 4-vinylpyridine and styrene. An ion-imprinted polymer (IIP) specific for Cr (VI) adsorption was prepared by copolymerisation of the quaternised linear copolymer (quaternised with 1,4-chlorobutane), 2-vinylpyridine functional monomer and ethylene glycol dimethacrylate (EGDMA), as the cross-linking monomer, in the presence of 1,1’-azobis(cyclohexanecarbonitrile) as initiator. Ammonium dichromate and aqueous methanol were used as a template and porogenic solvent, respectively. Leaching of the chromate template from the polymer particles was achieved with successive stirring of the ion-imprinted polymer (IIP) particles in 4 M HNO3 solutions to obtain leached materials, which were then used for selective rebinding of Cr (VI) ions from aqueous solutions. Similarly, the non-imprinted polymer/ control polymer (NIP/CP) material was also prepared under exactly the same conditions as the IIP but without the chromate anion template. Various parameters, such as solution pH, initial concentration, aqueous phase volume, sorbent dosage, contact time and leaching solution volumes, were investigated. Scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, BET surface area and pore size analysis were used for the characterisation of IIP (both unleached and leached) and CP materials. Optimal parameters were as follows: solution pH, 3; contact time, 120 min; eluent, 20 mℓ of 0.1 M NaOH; and sorbent amount, 125 mg. Maximum retention capacity of IIP and CP was 37.58 and 25.44 mg∙g-1, respectively. The extraction efficiencies of the IIP and CP were compared using a batch and SPE mode of extraction. In the absence of high concentrations of ions, especially sulphate ions, both CP and IIP demonstrated no differences in binding of Cr (VI), which was almost 100%. However, in the presence of high concentrations of sulphate ions, the selectivity on the CP completely collapsed. The study clearly demonstrates the suitably of the developed IIP for selective extraction of Cr (VI) in complex samples such as those from acid mine drainage. The selectivity was also compared by direct injection of the real-world sample, both spiked and non-spiked, into that obtained after IIP selective extraction. Despite the method’s very low detection limits for direct injection (below 1 μg∙ℓ-1), no Cr (VI) was obtained. However, after IIP selective extraction, spiked Cr (VI) was detected in the spiked sample.
- Full Text:
- Date Issued: 2011