Heavy Baryons with Strangeness in a Soliton Model

We present results from a chiral soliton model calculation for the spectrum of baryons with a single heavy quark (charm or bottom) and non-zero strangeness. We treat the strange components within a three flavor collective coordinate quantization of the soliton that fully accounts for light flavor symmetry breaking. Heavy baryons emerge by binding a heavy meson to the soliton. The dynamics of this heavy meson is described by the heavy quark effective theory with finite mass effects included.Comment: Ten pages, one figures, two tables, version to be published in PL

Molecular genetics of arrhythmogenic right ventricular cardiomyopathy in South Africa

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable disorder characterised by progressive degeneration of the right ventricular myocardium, arrhythmias and an increased risk of sudden death at a young age. Fourteen chromosomal loci have been linked to ARVC and nine disease genes have been identified. Linkage analysis of a South African family was previously performed at ARVC loci 1 to 6. ARVC loci 1 to 5 were excluded as disease loci in this family based on lack of evidence for linkage. However, a peak lod score of 2.93 was obtained for the ARVC-6 locus which is highly suggestive of linkage. Subsequently another locus (ARVC-7) and five ARVC disease genes (ARVC loci 8 to 12) have been reported. The aim of this project was to identify the disease gene that causes ARVC in this family

Behavioural Anomalies, Bounded Rationality and Simple Heuristics

The use of bounded rationality in explaining economic phenomena has attracted growing attention. In spite of this, there is still considerable disagreement regarding the meaning of bounded rationality. Basov (2005) argues that when modeling boundedly rational behaviour it is desirable to start with an explicit formulation of the learning process. A complete understanding of the boundedly rational decision-making process requires development of an evolutionary-dynamic model which can give rise to such learning processes. Evolutionary dynamics implies that individuals use heuristics to adjust their choices in light of past experiences, moving in the direction that appears most beneficial, where these adjustment rules are assumed ‘hardwired’ into human cognition through the process of biological evolution. In this paper we elaborate on the latter point by building a model of evolutionary selection relevant to heuristics. We show that in addition to explaining the origin of learning rules this approach also sheds light on some well documented preference anomalies.Bounded Rationality;Heuristics;Replicator Dynamics

CATULLUS EN KROG: GEBRUIK VAN 'N PERSONA AS METAFOOR VIR DIE KREATIEWE PROSES VAN SKRYF

You died two thousand years ago, Catullus, Myriads since then have walked the earth you knew All their long lives and faded into nothing, And still across that waste men think of you.J C Squire: “To a Roman” (1923)1 Hierdie bespreking ondersoek die moontlikheid dat beide Gaius Valerius Catullus en Antjie Krog in hulle digkuns gebruik maak van 'n persona as metafoor vir die kreatiewe proses van skryf. Gedig c. 50 van Catullus word as voorbeeld gebruik waar die moontlikheid bestudeer word dat die Calvus in gedig c. 50 gebruik word as 'n metafoor vir die kreatiewe proses van skryf. Deur die bestudering van die betrokke gedig word die effek wat Calvus op Catullus uitoefen metafories vergelyk met die effek wat die kreatiewe proses op Catullus uitoefen.Volgens hierdie lesing van c. 50 konsentreer die digter-persona op sy ervaring van die kreatiewe proses as soortgelyk aan die ervaring van 'n liefdesverhouding. Die studie verken Catullus se gebruik van die Calvus persona in c. 50 as 'n poging van die digter om beide die emosionele en erotiese ervaring van digkuns te verwoord.In 'n soortgelyke ondersoek word Antjie Krog se gedig “die skryfproses, as sonnet” as 'n voorbeeld van moderne digkuns bespreek, waar (a) die man as metafoor gebruik word vir die proses van kreatiwiteit, en (b) voorbeelde van erotika gebruik word om die ervaring van die kreatiewe proses te verwoord.  Hierdie bespreking van die gedigte van beide 'n antieke en moderne digter plaas die kompleksiteit van Catullus se ervaring van die kreatiewe proses in perspektief ten opsigte van moderne digkuns.

Quantity and quality losses of 'Crimson Seedless' grape and 'Packham's Triumph' pear along the supply chain and associated impacts

Thesis (PhDAgric)--Stellenbosch University, 2022.ENGLISH ABSTRACT: Postharvest loss and waste (often referred to as wastage) is a global problem affecting all produce along the supply chain from farm to plate. These losses not only decrease food supply but also mean that huge amounts of the resources and effort used in the production of horticultural crops are squandered. From an economic perspective, addressing postharvest losses is not only helpful to producers aiming to sell more, but also to consumers who could save money as the available food becomes more affordable. To date, there is little scientific data available on the incidence and magnitude of postharvest losses of fruit and other food crops in South Africa. The aims of this study were to assess postharvest losses in quantity and quality of ‘Crimson Seedless’ table grape and ‘Packham’s Triumph’ pear along the supply chain and quantify the associated economic, environmental and resource impacts in order to inform mitigating actions. The base measurement for table grape losses occurred in the packhouses of four farms in the Western Cape during the commercial harvest. The highest quantity (%) of physical losses in the supply chain was found to occur at this level when compared to the cold storage (2 or 4 weeks at -0.3°C ± 0.7°C and 81.3% ± 4.1% RH), retail (10 days at 5.4°C ± 0.6°C and 83.7% ± 2.9% RH) and consumer/home (ambient) storage (25.1 ± 1.3°C and 46.6 ± 6.0% RH) stages. There were large differences between the 2017 and 2018 seasons, with the 2018 season’s losses being half that of the first. The main reason for losses at the packhouse level was mechanical damage (7.1% in 2017 and 3.09% in 2018) due to rough handling of crates and could be improved by making workers more aware of the necessity to handle crates with care. Harvest timing is also essential, as delayed harvesting reduces shelf life and increases postharvest losses, as evidenced by this research. The farm that sustained the highest losses in 2017 (23.3%) harvested later than was optimal, and therefore, the bunches stayed on the vines too long. In 2018 the harvest occurred two weeks earlier than in 2017, and the grapes were in better condition leading to fewer losses on farm level (5.85%). Among all supply chain scenarios, the main quality problem was rachis and stem browning at temperatures higher than -0.5ºC. This caused berries to drop faster and bunches to look less fresh, as well as causing bunches to weigh less when sold. While 500 g and 1 kg punnets are routinely kept at around 5ºC at the retail level, during peak season 4.5–10 kg cartons are often stacked on the floor under ambient conditions. Therefore, the table grapes would have a maximum shelf life of seven days before the stems have browned and too many berries per bunch are decayed to sell. Therefore, it is advisable to keep cartons at -0.5ºC and high RH and only place bunches in punnets in 5ºC display fridges as the stock sells. The base measurement for losses of pear occurred in the orchard of two farms in the Western Cape during commercial harvest. It was found that 18% of the harvest on the one farm and 19% of the harvest on the other, did not reach the minimum quality standards. The main reasons were deformed fruit and too small size. The only decay, among all supply chain scenarios, occurred when pears were kept under ambient conditions (25.1 ± 1.3°C, 46.6 ± 6.0% RH) where 3.3% were decayed after seven days and 6.6% after 10 days. The majority of physical losses were due to weight loss with a 3.9%, 3.6 and 3.7% decrease in weight for supply chain Scenario B (to local retail markets), supply chain Scenario C (to export retail markets) and supply chain Scenario D (simulated ‘abusive’ treatment of fruit within the export chain) respectively. . Of the data gaps in the existing knowledge on global food loss and waste, the largest gap is the lack of available data on postharvest losses, retail and household level (shelf-life) food waste data. Therefore, this study contributed to the advancement of new knowledge by generating primary data on postharvest quantity and quality losses along the supply chain to manage the food loss and waste problem better.AFRIKAANSE OPSOMMING: Na-oes verliese en vermorsing is 'n wêreldwye probleem wat alle produkte in die voorsieningskettings van plaas tot bord beïnvloed. Hierdie verliese verminder nie net die voedselvoorraad nie, maar beteken ook dat groot hoeveelhede van die hulpbronne en moeite wat in die produksie van tuinbougewasse gebruik word, vermors word. Vanuit 'n ekonomiese oogpunt is die vermindering van na-oesverliese nie net nuttig vir produsente wat meer wil verkoop nie, maar ook vir verbruikers wat geld kan bespaar namate die beskikbare voedsel meer bekostigbaar word. Tot op hede is daar min wetenskaplike data beskikbaar oor die voorkoms en omvang van na-oesverliese van vrugte en ander voedselgewasse in Suid-Afrika. Die doel van hierdie studie was om na-oes verliese in hoeveelheid en kwaliteit van druiwe 'Crimson Seedless' en pere 'Packham's Triumph' deur die verskaffingsketting te meet en die gepaardgaande ekonomiese, omgewings- en hulpbronimpakte te bereken om ingeligte besluite te kan maak wat na-oesverliese verminder. Die basismeting vir tafeldruifverliese het tydens die kommersiële oes in die pakhuise van vier plase in die Wes -Kaap plaasgevind. Die grootste hoeveelheid (%) fisiese verliese in die voorsieningsketting het op hierdie stadium voorgekom in vergelyking met die verkoelde opberging (2 of 4 weke by -0.3°C ± 0.7°C en 81.3% ± 4.1% RH), kleinhandel (10 dae by 5.4°C ± 0.6°C en 83.7% ± 2.9% RH) en verbruiker (25.1 ± 1.3°C en 46.6 ± 6.0% RH) stadiums. Daar was groot verskille tussen die 2017- en 2018- seisoene met 2018 se verliese die helfte van die gedurende die 2017-seisoen. Die hoofrede vir verliese op pakhuisvlak was meganiese skade (7.1% in 2017 en 3.09% in 2018) as gevolg van rowwe hantering van kratte en kan verbeter word deur werkers meer bewus te maak van die noodsaaklikheid om kratte versigtig te hanteer. Oestydsberekening is ook noodsaaklik, aangesien vertraagde oes raklewe verminder en lei tot verhoogde na-oes verlies soos bewys deur hierdie navorsing. Die plaas wat die hoogste verliese in 2017 gely het (23.3%) het later as optimaal geoes en die trosse het dus te lank aan die stokke gebly. In 2018 het die oes twee weke vroeër as in 2017 plaasgevind, en die druiwe was in 'n beter toestand wat gelei het tot minder verliese op plaasvlak (5.85%). Die belangrikste kwaliteitsprobleem was rachis en stingel verbruining by temperature hoër as -0,5ºC. Dit het veroorsaak dat bessies vinniger val en dat trosse minder vars lyk, asook dat trosse minder weeg as hulle verkoop word. Terwyl 500 g of 1 kg plastiek bakkies gereeld by ongeveer 5ºC op kleinhandelvlak gehou word, word 4,5 –10 kg kartonne dikwels op die vloer gestapel tydens piek seisoen by kamer temperatuur en humiditeit. Die tafeldruiwe sou dus 'n maksimum rakleeftyd van sewe dae hê voordat die stingels verbruin en te veel bessies per tros vrot om te verkoop. Dit word dus aanbeveel dat kartonne by -0,5ºC en hoë RH gehou word en trosse slegs in bakkies in 5ºC yskaste geplaas word soos die voorraad verkoop. Die basismeting vir verliese van pere het tydens die kommersiële oes in die boord van twee plase in die Wes-Kaap plaasgevind. Daar is gevind dat 18% van die oes op die een plaas en 19% van die oes op die ander plaas nie die minimum kwaliteitstandaarde bereik het nie. Die hoofredes was misvormde en te klein vrugte. Die enigste bederf, onder alle voorsieningskettingscenario's, het plaasgevind toe pere by kamer- temperatuur en humiditeit (25.1 ± 1.3°C, 46.6 ± 6.0% RH) gestoor is waar 3.3% na 7 dae en 6.6% na 10 dae bederf het. Die meerderheid fisiese verliese was as gevolg van gewigsverlies met 'n 3.9%, 3.6 en 3.7% afname in gewig vir voorsieningsketting Scenario B (na plaaslike kleinhandelmarkte), voorsieningsketting Scenario C (om kleinhandelmarkte uit te voer) en voorsieningsketting Scenario D (gesimuleerde swak hantering van vrugte in die uitvoerketting) onderskeidelik. Die grootste gaping in die bestaande kennis oor wêreldwye voedselverliese en vermorsing, is die gebrek aan beskikbare data oor na-oesverliese, kleinhandel- en huishoudelike vlak (rakleeftyd). Hierdie studie het dus ten doel gehad om nuwe kennis by te dra deur primêre data oor na-oesvelies hoeveelheid en kwaliteitverliese in die voorsieningsketting te genereer om sodoende die voedselverlies- en afvalprobleem beter te bestuur.Doctora

Preference of Western Cape Province consumers for the eating quality and appearance of pears

Thesis (MSc)--Stellenbosch University, 2015.ENGLISH ABSTRACT: Our study aimed to determine the preference of Western Cape consumers for the eating quality and appearance of pears. Identifying the main sensory drivers of liking and consumer groupings with similar preferences may allow the pear industry to target specific markets and increase local consumption, which is stagnating at relatively low levels. Our first trial included 9 European pear cultivars (Pyrus communis L.) and one Asian pear cultivar (P. pyrifolia (Burm.) Nak.). These were chosen to represent a wide range of characteristics in order to identify the main sensory drivers of liking and possible consumer groupings. The majority of the 421 consumers, irrespective of gender, ethnicity and age, preferred pears with a distinct pear flavour, a sweet taste, a fair amount of malic acid, soft, juicy flesh with melt character, and a yellow or pale green peel colour with a typical pear shape. Astringency, sourness and grittiness negatively affected consumer preference. None of the pears were mealy and therefore we could not assess this characteristic. Two consumer clusters with similar preferences for eating quality and also for appearance were identified. In terms of eating quality, group 1 (55% of consumers) indicated a liking for a wide range of cultivars with poorly defined likes and dislikes. Group 2 (45% of consumers), in contrast, had a high liking for the eating quality of a small selection of cultivars while disliking the rest. Based on the preferences for appearance, group 1 (61% of consumers) again indicated a liking for a wide range of cultivars. Group 2 (39% of consumers) scored the most familiar cultivars, viz. Bon Chretien and Packham’s Triumph, very high and the other cultivars much lower than group 1. The objective of our second study was to investigate consumer preference for firm, juicy pears compared to soft pears with a melt character and to identify which of ‘Forelle’, ‘Packham’s Triumph’ and ‘Abate Fetel’ is best suited to either option. Pears were harvested within the commercial harvest window (H1) (flesh firmness at 6- 6.8kg, 6.4-7kg and 6-6.8kg respectively) and again a month later (H2). H1 and H2 pears were ripened at room temperature (20 ºC) for seven or one day, respectively. More consumers (67%) correlated positively with melt character, juiciness, overall pear flavour and sweet taste. These characteristics were the most prominent in H1 ‘Packham’s Triumph’ pears while H2 fruit were much firmer, but lower in preferred flavour characteristics. There is, however, also a market for crisp and juicy pears as 33% of the consumers showed a preference for these characteristics. ‘Forelle’ and ‘Abate Fetel’ could both be suitable for this market. ‘Forelle’ was preferred firm, probably because H1 soft pears were more astringent and sour as well as less juicy than H2. There was no difference in preference between H1 and H2 in ‘Abate Fetel’. In conclusion, most Western Cape consumers prefer European pears with the characteristic soft, melting texture, but a third of consumers seem to like firm, juicy pears. Hence, there is opportunity to develop a market for tree-ripe and Asian pears, but marketing will be needed to overcome appearance preferences.AFRIKAANSE OPSOMMING: Ons studie was daarop gemik om die voorkeur van Wes-Kaap verbruikers vir die eetkwaliteit en voorkoms van pere te bepaal. Die identifisering van die belangrikste sensoriese drywers van smaakvoorkeure en verbruikersgroepe met soortgelyke voorkeure kan die peerbedryf toelaat om spesifieke markte te teiken en plaaslike verbruik te verhoog, wat tans op relatief lae vlakke stagneer. Ons eerste proef het 9 Europese peer kultivars (Pyrus communis L.) en een Asiatiese peer kultivar (P. pyrifolia (Burm.) Nak.) ingesluit. Die kultivars is gekies om 'n wye verskeidenheid eienskappe te verteenwoordig sodat die belangrikste drywers van sensoriese smaakvoorkeure en moontlike verbruikersgroeperings geïdentifiseer kon word. Die meerderheid van die 421 verbruikers, ongeag geslag, etnisiteit en ouderdom, het pere met 'n duidelike peer geur, 'n soet smaak, 'n redelike hoeveelheid appelsuur, sagte en sappige tekstuur met n smeltkarakter, en 'n geel of liggroen skilkleur met 'n tipiese peer vorm verkies. Frankheid, hoë suurvlakke en grinterigheid het verbruikers voorkeur negatief beinvloed. Geen pere in ons studie was melerig nie en daarom kon ons nie hierdie eienskap evalueer nie. Twee verbruikersgroepe met soortgelyke voorkeure vir eetkwaliteit en peervoorkoms is geïdentifiseer. In terme van eetkwaliteit het groep 1 (55% van die verbruikers) voorkeur vir 'n wye verskeidenheid van kultivars aangedui. Groep 2 (45% van die verbruikers) daarteenoor het die eetkwaliteit van net 'n klein seleksie van kultivars verkies, terwyl hul ‘n afkeur getoon het vir die res. In terme van voorkoms, het groep 1 (61% van die verbruikers) weereens van 'n wye verskeidenheid kultivars gehou terwyl groep 2 (39% van die verbruikers) baie hoë punte aan die bekende Bon Chretien en Packham's Triumph kultivars toegeken het, maar die ander kultivars baie laer as groep 1 bepunt het. Die doel van ons tweede proef was om verbruikersvoorkeur vir ferm, sappige pere teenoor sagte pere met 'n smelt tekstuur te bepaal en tot watter mate 'Forelle', 'Packham's Triumph’ en ‘Abate Fetel' geskik is vir iedere opsie. Pere is tydens die kommersiële oesvenster (H1) (fermheid 6-6.8kg, 6.4-7kg en 6-6.8kg onderskeidelik) en weer 'n maand later (H2) geoes. H1 en H2 pere is teen kamertemperatuur (20 ºC) onderskeidelik vir sewe of een dag rypgemaak. Die meeste verbruikers (67%) se voorkeur korreleer positief met 'n smeltende tekstuur, sappigheid, peer geur en soet smaak. Hierdie eienskappe was die prominentste in H1 'Packham’s Triumph' pere terwyl H2 vrugte baie fermer, maar laer in voorkeur geureienskappe was. Daar is egter wel 'n mark vir ferm, sappige pere aangesien 33% van die verbruikers 'n voorkeur toon vir hierdie eienskappe. 'Forelle' en 'Abate Fetel' sou beide geskik kon wees vir hierdie mark. 'Forelle' is verkies as fermer peer, waarskynlik omdat H1 sagte pere meer frank, suurder sowel as minder sappig was. Daar was geen verskil in verbruikersvoorkeur tussen 'Abate Fetel’ se H1 en H2 pere nie. Ten slotte, die meeste verbruikers van die Wes-Kaap verkies die smaak van ryp Europese pere met hul karakteristieke sagte, smeltende tekstuur, maar 'n derde van die verbruikers hou wel van ferm, sappige pere. Daar is dus 'n geleentheid om die mark vir boomryp en Asiatiese pere te ontwikkel, maar bemarking sal nodig wees om die verbruikersvoorkeure vir voorkoms te oorkom

Resurrection ecology of invertebrates in temporary wetlands in the Cape Floristic region: effects of urbanisation and fire

Despite their importance to regional biodiversity, temporary wetlands and their invertebrate communities are generally understudied and under-conserved. Resurrection ecology is used to study the communities present in the dry phase of temporary wetlands to gain a better understanding of the functioning and health of these systems. The hatching success of invertebrate propagules in dried soil sediments, collected from temporary wetlands in Cape Sand Fynbos regions of Cape Town, were investigated in 2016. Soil samples were collected from conserved and urban sites (during May and June 2016) using a standard soil auger method and complemented with monthly aquatic phase sampling using standard sweep net methods (during September and October 2016). The effects of fire were tested, on hatching success by staging vegetation fires over the collected soil samples for five temporary wetland areas in the same region. Mann-Whitney U tests were used to test differences in abundances between treatments, whereas for comparison of taxon richness, Shannon diversity and Pielou's evenness linear mixed effect models (LMER) were used. Non-metric multidimensional scaling (nMDS) plots were used to graphically visualize the community composition between the different treatments, with 'adonis' analysis used to test their statistical significance. Results found a total of 18 invertebrate taxa hatched, while a total of 27 taxa were identified from the wet phase. Results from hatching assays showed no significant differences in diversity patterns of invertebrates between conserved and urban areas in the dry phase. However, wetlands that were in the conserved area supported higher invertebrate diversity during the wet phase, although not significant (lmer, Z = -1.75, p = 0.08). These results suggest that human activity (alien vegetation, littering and polluting) in the area did not impact the ability of invertebrate propagules to emerge, but did slightly affect the natural aquatic phase. Fire had a significantly negative impact on invertebrate diversity measures (lmer, p < 0.001) and community composition (adonis, F = 24.494, p = 0.001) during hatching assays. Management of unpredicted and uncontrolled fire in urban areas is essential to ensure future protection of critical biodiversity areas created by these temporary wetlands. More research should focus on the impact of increasing fire frequency and intensity on these systems to understand the management challenges in a changing climate

On collecting southern African art: interrogating private collecting practices and the construction of 'traditional' southern African art as 'national' and 'cultural heritage'

M.A. University of the Witwatersrand, Faculty of Humanities (Art History), 2012This dissertation critically engages Karel Nel’s personal/private collection of southern African art in relation to other collections to which he is connected. An examination of Nel’s collecting practices is conducted, after an extensive comparison with the public collections held by both the Wits Art Museum and the Johannesburg Art Gallery. I then investigate the degree of influence between his private collecting praxes and the collecting praxes of the selected public institutions. It is argued that this helps to establish the degree to which private collecting influences the creation of what is understood as ‘national’ and ‘cultural heritage’ in public collections of southern African art