Leipoldt in 1980*)

Oor Leipoldt se veelsydigheid hoef daar nie veel gésê te word nie. Hy was digter, dramaturg, romanskrywer, joemalis, geneesheer, kos- en wynkenner, filantroop, wêreldburger, maar bly tog vir ons in die eerste plek digter. Ons beeld van Leipoldt so oeuvre kan verander - daar is vanjaar al twee “nuwe” werke van hom ontdek - maar as daar iets van Leipoldt behoue sal bly, sal dit eerder sy poësie as sy drama, prosa, joemalistieke werk of kookboeke wees; so lyk dit altans op die oomblik. Daarom beperk ek my to t sy poësie en sal ek nie probeer om u totaalbeeld van sy ryk maar erg ongelyke oeuvre te gee nie

Ouerbegeleidingsbehoeftes ten aansien van die fisiek-gestremde voorskoolse kind as voorbereiding vir 'n insluitende onderwysomgewing

This article focuses on parents' educational needs concerning their physically disabled pre-school child with the view to placement in an inclusive learning environment. Support services include, among other things, preparation of these children to enter an inclusive learning environment, and parent education to reach this goal. Therefore parent education with a view to promoting the success of inclusion is of utmost importance, by focusing on those skills needed by physcially disabled children to perform sucessfully in the inclusive classroom milieu. The goal of parent education is to mediate those skills necessary to become an integral part of regular classroom activities and be accepted within the inclusive learning environment ; to facilitate a functional family life and educational atmosphere as basis for further growth ; to promote the least restrictive educational environment at home ; to facilitate modeling of socially acceptable behaviour patterns ; to promote a cognitively, emotionally, and socially stimulating learning environment at home ; to provide interpersonal interaction with nonhandicapped siblings and peers; and to remove stereotypes and stigmata attached to physically disabled children and to facilitate successful adjustment within the inclusive learning environment and the broader community during adulthood. (South African Journal of Education: 2002 22(4): 338-344

Malic Acid in Wine: Origin, Function and Metabolism during Vinification

The production of quality wines requires a judicious balance between the sugar, acid and flavour components of wine.  L-Malic and tartaric acids are the most prominent organic acids in wine and play a crucial role in the winemaking process, including the organoleptic quality and the physical, biochemical and microbial stability of wine.  Deacidification of grape must and wine is often required for the production of well-balanced wines. Malolactic fermentation induced by the addition of malolactic starter cultures, regarded as the preferred method for naturally reducing wine acidity, efficiently decreases the acidic taste of wine, improves the microbial stability and modifies to some extent the organoleptic character of wine. However, the recurrent phenomenon of delayed or sluggish malolactic fermentation often causes interruption of cellar operations, while the malolactic fermentation is not always compatible with certain styles of wine. Commercial wine yeast strains of Saccharomyces are generally unableto degrade L-malic acid effectively in grape must during alcoholic fermentation, with relatively minor modifications in total acidity during vinification. Functional expression of the malolactic pathway genes, i.e. the malate transporter (mae1) of Schizosaccharomyces pombe and the malolactic enzyme (mleA) from Oenococcus oeni in wine yeasts, haspaved the way for the construction of malate-degrading strains of Saccharomyces for commercial winemaking

Researching the first year accounting problem : factors influencing success or failure at a South African higher education institutions

Published ArticleUnder-performance and failure in first year accounting is a problem experienced in many higher education institutions world-wide as well as in South Africa. Literature shows that the problem is relatively well researched. Most of the research has taken place within the quantitative paradigm and in many cases focused on a search for determinants of possible success and / or failure in the subject or the factors contributing to the situation. The findings of all these research projects are varied and often inconclusive. It also becomes clear that the contexts of the studies are diverse, which makes it difficult for institutions and concerned lecturers to apply the findings in their specific situations. In this article the authors provide an overview of some of the most prominent research findings on factors determining or influencing success / failure in the field. They also attempt to organise these findings in a digestible way for the concerned lecturer and interested researcher. This is followed by a report on the first phase of an investigation into possible factors contributing to the low performance levels of students at a South African higher education institution. The unit of analysis is the first year accounting class of the first author (a lecturer at the institution). The research is quantitative in nature and statistical analyses are employed. In addition to factors such as age, gender, matric performance in key subjects, M-scores, class attendance and nationality, the investigation also looked at the levels of learning approach of the students as a possible determinant of success or failure. The findings are compared with the findings from literature and the implications of the research are discussed

Piroklastiese afsettings van perm-ouderdom in die Hoof-Karookom met spesiale verwysing na die Collingham Formasie, Ecca Groep

Proefskrif (Ph. D) -- Universiteit van Stellenbosch, 1995.ENGLISH ABSTRACT: This study comprises a geological and geochemical investigation of the K-bentonites (potassium-rich, illitic clay beds interpreted as altered volcanic ash) of Permian age in the Karoo Supergroup of the Main Karoo Basin. It also includes a sedimentological and stratigraphical study of the Collingham Formation (Ecca Group), which is the unit with the h.ighest concentration of K-bentonite layers. The 30 co 70 m thick Collingham Formation is conformably underlain by the white-weathering, carbonaceous Whitehill Formation and is overlain by the Ripon Formation in the southeast, the Vischkuil Formation in the southwest and the Tierberg Formation in the west and northwest. The formation consists essentially of alternating thin beds of hard, dark grey, siliceous mudrock and very thin beds of relatively softer yellow­ weathering K-bentonite beds. These sediments are sporadically interrupted by chert beds, and in the upper part of the formation by siltstone and very fine-grained sandstone beds. In the southern and southwestern part of its outcrop area the formation can be divided into three members, namely the Zoute KJoof, Buffels River and Wilgehout River. The basal two members are separated by the Matjiesfontein Chert Bed. Deposition of the Collingham Formation occurred as basin floor muds which settled out of suspension from under and upper flows and as pelagic and hemipelagic material. These deposits were sporadically interrupted by short-lived volcanic ash-falls. The upper part of the formation in the west consists of basin floor and outer fan deposits of a submarine fan. K-bentonite layers are distributed throughout the Karoo Basin, ranging stratigraphcally from the Dwyka Group through the Ecca Group up to and including the basal Beaufort Group. Three zones of relatively higher concentrations of K-bentonite occur, namely in the Prince Albert, Collingham and Abrahamskraal Formations. By using the K-bentonites as marker beds it was confirmed that the Dwyka/Prince Albert contact is younging southwards, that the Whitehill Formation is correlatable with the upper part of the Vryheid Formation and that the Wilgehout River Member is older that the Ripon Formation. Transport of the volcanic ash was from the south and southwest as aerially transported tephra originating from terrestrial Plinian eruptions. The K-bentonite consists mainly of illite, feldspar and quartz (except where it is silicified or enriched in iron oxides and/or carbonates). The maximum opserved grain size of the largest feldspar and quartz grains is 0.5 mm. Diageneticstructures indicate that a large percentage of the minerals that are recognised are diagenetic of origin. The diagenesis and very low grade metamorphism which the K-bentonite has undergone can be represented by the following reactions: Siliceous volcanic ash + H₂0 -> montmorillonite + silica (opal-A) + ions in solution -> montmorillonite + zeolite + silica (opal - CT) -> mixed-layer montmorillonite/illite + zeolite + silica (chert) - > illite + albite + quartz. Chemically the K-bentonite is depleted in Si0₂ and enriched in Al₂ (20-30%} and O (5-10%) in comparison with normal mudstones. Most of the movement of the components occurcd during the first phase i.e. when the volcanic glass was altered to montroorillonite. Only the following analysed components were apparently to a large extent immobile; A1₂0₃, Ti0₂, Zr, Nb, Y and Ga. The geochemistry indicates that the K-bentonites and silicified K-bentonites were originally acid (felsic) volcanic ash. The K-bentonite beds in the lower half of the Collingham Formation as well as the older ones show a within-plate granite geochemical signature, whereas the younger ones correspond better to a volcanic-arc granite association. All the K-bentonites seem to originate from a magma which was generated by the melting of crust that had already undergone a cycle of subduction-zone or continent-continent collision magmatism. The dacitic to rhyolitic volcanism was probably related to the broad Permian magmatic belt which at present crops out in southern South America and/or its eastward extension. This magmatism can probably be linked to tension and graben formation in Patagonia and was followed by southward-directed, and later northward­ directed subduction-related magmatism to the south of the African Plate. A counter-clockwise rotation of Patagonia can probably explain the tension in the west and the compression in the east to form the Cape Fold Belt. Although still tentative, the possiblity exists that the three K-bentonite-rich zones in the Karoo Supergroup can be correlated with the deformation events of the Cape Fold Belt. A preliminary single zircon age of 262 ± 4 Ma was obtained by R. Armstrong for the basal part of the Collingham Formation. Due to their mineralogical composition (illite instead of montmorillonite) the K-bentonites no longer possess the physical properties necessary for use as an industrial material (eg. drilling mud). There is, however, the possibility that the K-bentonites could be exploited as a source for potassium and aluminium, but at present this is not economically viable.AFRIKAANSE OPSOMMING: Hierdie studie omvat 'n geologiese en geochemiese ondersoek van die K-bentoniete (kaliumryke, illitiese kleilae wat as veranderde vulkaniese aslagies beskou word) van Perm-ouderdom in die Karoo Supergroep van die Hoof-Karookom. Dit behels ook 'n sedimentologiese en stratigrafiese ondersoek van die Collingham Formasie (Ecca Groep) wat die eenheid is met die hoogste konsentrasie K-bentonietlae. Die 30 tot 70 i:n dik Collingham Formasie word konkordant deur die witverwerende, koolstofryke Whitehill Formasie onderle en deur die Ripon Formasie in die suidooste, die Vischkuil Formasie in die suidweste en die Tierberg Formasie in die weste en noordweste oorle. Die formasie bestaan hoofsaaklik uit afwisselende dun lae harde, donkergrys, silikahoudende modderklip en baie dun relatief sagter geelverwerende K­ bentonietlagies. Hierdie opeenvolging word sporadies onderbreek deur chertlae, en in die boonste gedeelte van die formasie deur sliksteen en baie fynkorrelrige sandsteenlae. Ysterryke moddersteen en fosfatiese kleisteen kom ook sporadies voor. Die formasie kan in die suidelike en suidwestelike gedeelte van sy dagsoomgebied in drie lede onderverdeel word naamlik die Zoute Kloof, Buffelsrivier en Wilgehoutrivier. Die basale twee lede word geskei deur die Matjiesfonteinchert Laag. Afsetting van die Collingham Formasie het plaasgevind as komvloermodders wat uit suspensie uitgesak het van onder- en bovloeie en as pelagiese en hemipelagiese materiaal. Hierdie afsettings is periodiek onderbreek deur kortstondige vulkaniese asvalle. Die boonste gedeelte van die formasie bestaan in die weste uit komvloer- en buitewaaier-afsettings van 'n fynkorrelrige onderwaterwaaier. K-bentonietlagies kom verspreid oor die hele Karookom voor, stratigrafies vanaf die Dwyka Groep regdeur die Ecca Groep tot en met die basale Beaufort Groep. Drie sones wat relatief hoer konsentrasies K­ bentoniet bevat is teenwoordig, naamlik in die Prins Albert, Collingham en Abrahamskraal Formasies. Deur die K-bentoniete te gebruik as merkerlae is bevestiging verkry dat die Dwyka/Prins Albert-kontak suidwaarts jonger word, dat die Whitehill Formasie met die boonste gedeelte van die Vryheid Formasie gekorreleer kan word en dat die Wilgeboutrivier Lid ouer is as die Ripon Formasie. Aanvoer van die vulkaniese as was vanuit die suide en suidweste as lugvervoerde tefra afkomstig van oplandige Pliniese erupsies. Die K-bentoniet bestaan hoofsaaklik uit illiet, veldspaat en kwarts (buiten waar dit gesilisifiseer of verryk is aan ysteroksiede en/of karbonate). Die maksimum waargenome korrelgrootte vir die grootste veldspaat- en kwartskorrels is 0,5 mm. Diagenetiese teksture dui daarop dat 'n groot persentasie van die minerale wat tans waarneembaar is diageneties van oorsprong is. Die diagenese en baie laegraadse metamorfose wat die K­ bentoniet ondergaan het kan deur die volgende reaksies weergegee word: Silikaryke vulkaniese as + H₂0 -> montmoriJloniet + silika (opaal-A) + ione in oplossing-> montmorilloniet + zeoliet + silika (opaal-CT) -> montmorilloniet/illiet menglaagklei + zeoliet + silika (chert) -> illiet + albiet + kwarts. Cbemies is die K-benloniet verarm aan SiO₂ en verryk in Al₂O₃ (20-30%) en KP (5-10%) in vergelyking met normale moddcrstenc. Die mccste beweging van komponente bet gedurende die eerste stadium van diagenese plaasgevind, dit wil se gedurende die verandering van vulkaniese glas na montmorilloniet. Dit is slegs die volgende geanaliseerde komponenlc wat skynbaar tot 'n groot mate immobiel gebly het: Al₂O₃, TiO2i Zr, Nb, Y en Ga. Die geochemie dui daarop dat die K-bentoniet en gesilisifiseerde K-bentoniet oorspronklik suu.r (felsiese) vulkaniese as was. Die K-bentonietlagies in die onderste helfte van die Collingham Formasie en die wat ouer is vertoon geochemies 'n inlraplaatgraniet-verwantskap terwyl die wat jonger is meer 'n vulkaniese eilandbooggraniet-neiging toon. Al die K-bentoniete skyn afkomstig te wees van 'n magma wat gevorm bet deur die smelting van kors wat reeds deur 'n siklus van subduksie- of kontinent­ kontinent-botsingsmagmatisme was. Die dasitiese tot riolitiese vulkane was waarskynlik verwant aan die bree magmatiese gordel van Perm­ ouderdom wat tans in suidelike Suid-Amerika dagsoom, en/ of sy ooswaartse voortsetting. Hierdie magmatisme kan waarskynlik gekoppel word aan tensie en graben-vorming in Patagonie gevolg deur suidwaarts- en nog later noordwaartsgerigte subduksie-verwante magmatisme ten suide van die Afrilcaplaat. 'n Linksomdraaiing van Patagonie kan moontlik die tensie in die weste en die kompressie tydens dievormiog van die Kaapse Plooigordel in die ooste verklaar. Hoewel baie tentatief bestaan die moontli.kheid dat diedrie K-bentonietryke sones in die Karoo Supergroep met die vervormingsfases van die Kaapse Plooigordel gekorreleer kan word. 'n Voorlopige enkelsirkoon-ouderdom van 262 :!: 4 mj is vir die basale gedeelce van die Collingham Formasie deur R. Armstrong verkry. As gevolg van sy mineralogiese samestelling (illiet i.p.v. montmorilloniet) besit die K-bentoniel nie meer die gewensLe fisiese eienskappe vir gebruik as indusLriele maleriaal (bv. boormodder) nie. Daar bescaan egter 'n moontlikheid dal die K-bentoniet as 'n bron van kalium en aluminium benut kan word, maar dit is tans nie ekonomies rue

The Paleoarchean Buffalo River komatiites: Progressive melting of a single large mantle plume beneath the growing Kaapvaal craton

Several Archean granitoid-greenstone terranes are exposed on the southeastern Kaapvaal craton in South Africa, but they received little scientific attention compared to the archetypal greenstone belt successions of the Barberton Mountain Land at the eastern craton margin. This study reports on a detailed field and geochemical survey of the Buffalo River Greenstone Belt at the southern Kaapvaal craton margin in KwaZulu-Natal, with focus on hitherto unstudied komatiites and basaltic rocks from this volcanic succession. Cross-cutting relationships and new U-Pb zircon age determinations for several granitoid units establish a minimum age of 3.26 Ga for komatiitic volcanism, possibly as old as ca. 3.5 Ga if a 3.47 Ga granodiorite sheet is interpreted as ‘intrusive’ into the greenstone succession. Geochemical data reveal three types of Paleoarchean komatiites at Buffalo River. Spinifex textured lava flows represent Al-depleted komatiites, with subchondritic Al2O3/TiO2 ratios and enrichment of LREE over HREE. The second type comprises Al-undepleted komatiites that have chondritic Al2O3/TiO2 and flat REE patterns. The third type identified comprises Al-enriched komatiites that display suprachondritic Al2O3/TiO2 ratios, with significant LREE depletion. The Al-depleted and Al-undepleted komatiites from Buffalo River are geochemically similar to komatiites from the 3.48 Ga Komati and 3.26 Ga Weltevreden formations of the Barberton Supergroup respectively, whereas the Al-enriched komatiites resemble the 3.33 Ga Commondale komatiites on the southeastern Kaapvaal craton. To explain the co-occurrence of three discrete komatiite types within a single volcanic succession at Buffalo River, we suggest that each major komatiite magmatic pulse originated from the same upwelling mantle source, from which melt was extracted at different pressure but similarly hot temperature conditions. 187Os/188Os data for the Al-depleted komatiites suggest an ultimate magma origin from a primitive mantle reservoir. The contrasting γOs values for Kaapvaal craton komatiites (zero to positive) and peridotitic mantle xenoliths (zero to negative) support a complementary nature of these lithologies as high-degree melts and depleted residues linked by vigorous mantle plume activity at around 3.5 Ga. Such a relationship can explain the contrasting Re/Os systematics of komatiites and lithospheric mantle peridotites, which creates the contrasting γOs over time. The highly siderophile element patterns of the Al-depleted komatiites from Buffalo River are similar to those of Barberton-type komatiites, for which an origin from the deepest upper mantle with high melt retention in an upwelling plume source was suggested. We confirm that this ca. 3.5 Ga mantle source had only 60–80 % of the platinum-group element budget of the modern ambient mantle, which points indirectly to a location at great depth in the aftermath of the meteoritic late accretion. Progressive melting of such an upwelling mantle source, to the point of majoritic garnet exhaustion, may explain the Al-undepleted and Al-enriched komatiites at Buffalo River. The presence of all three major komatiite types within a single volcanic succession may be linked to deep critical melting of a large mantle plume associated with growth of the Kaapvaal ‘continent’ at 3.5 Ga

Malic Acid Distribution and Degradation in Grape Must During Skin Contact: The Influence of Recombinant Malo-Ethanolic Wine Yeast Strains

Wine acidity plays an important role in determining wine quality and ensuring physiochemical and microbiological stability. In high-acid wines, the L-malic acid concentration is usually reduced through bacterial malolactic fermentation, while acidulation in low-acidity wines is usually done during final blending of the wine before bottling.  This study showed that skin contact did not influence the relative concentration of L-malic acid in the pulp and juice fractions from Colombard, Ruby Cabernet and Cabernet Sauvignon grape musts, with 32%-44% of the L-malic acid present in the pulp fraction. Four recombinant malo-ethanolic (ME) Saccharomyces wine yeast strains containing the malic enzyme (mae2) and malate transporter (mael) genes of Schizasaccharomyces pombe, effectively degraded the L-malic acid in both the juice and pulp fractions of all three cultivars, with a complete degradation of malic acid in the juice fraction within 2 days

Factors influencing the distribution of Cactoblastis cactorum, a biological control agent of Opuntia stricta in Kruger National Park, South Africa

Cactoblastis cactorum, a phycitid moth, has been used with considerable success as a biological control agent against several different cactus species in many parts of the world, including Opuntia stricta in Kruger National Park [KNP], South Africa. Although the moth has become widespread and abundant in KNP, its populations have not reached levels where it is able to provide the desired level of control on the alien species which has invaded more than 35 000 ha of the park and continues to spread. Although several factors, especially acquired predators and parasitoids, are known to curb the abundance of C. cactorum in South Africa, the extent to which this applies in KNP is unknown. Logistic regression and Canonical Community Analysis were used to determine the biotic and abiotic factors affecting the distribution and abundance of C. cactorum in KNP. To do this, maps of the ranges of the insect and host plant were constructed and integrated with other environmental features. The logistic regression showed that O. stricta density had no influence on whether or not C. cactorum was present in an area. The Canonical Community Analysis suggested that a high fire frequency, the herbicide control programme and the presence of small host plants may be important in limiting the distribution of C. cactorum, either directly or indirectly, through impacts on associated predators or parasitoids