Van Wyk Research Articles

A taxonomic revision of the South African endemic genus Dasispermum (Apiaceae, Apioideae)

A taxonomic revision of the recircumscribed South African endemic genus Dasispermum Raf. is presented, including keys to the species, complete nomenclature, typifications, descriptions, and geographical distributions. In addition, two new species, D. grandicarpum Magee & B.-E.van Wyk and D. perennans Magee & B.-E.van Wyk, are described. Seven species of Dasispermum are now recognised and can be distinguished from one another by their habit (life history and growth form), leaf morphology (leaf texture, leaf colour and width of the ultimate leaflet segments), inflorescence structure (length of the peduncle, presence or absence and division of involucral and involucel bracts), fruit morphology (relative length of the styles, fruit size and the prominence and relative orientation of the ribs) and fruit anatomy (shape of the cells external to the vittae).

Secure Software Engineering: A New Teaching Perspective Based on the SWEBOK

Introduction Many authors (Graff & Van Wyk, 2002; Howard, 2005; Howard & LeBlanc, 2002; Lipner & Howard, 2005; Microsoft, 2009; Shumba, Walden, Ludi, Taylor, & Wang, 2006; Walden & Frank, 2006; Viega & McGraw, 2002, Viega & Messier, 2003) have discussed integration of the concept of security into the software life cycle; however, none of them has done so within the framework of the Software Engineering Body of Knowledge (SWEBOK). Moreover, from an academic point of view, few university software engineering courses or textbooks incorporate guidelines and practices related to software engineering. Most focus on securing only one phase of the development process, which is coding (Graff & Van Wyk, 2002; Howard & LeBlanc, 2002; Viega & Messier, 2003). From an industry point of view, current surveys indicate that we are far from being able to develop acceptably secure software systems, CERT (CERT, 2003; PricewaterhouseCoopers, 2004) having reported over 5,000 software vulnerabilities in 2005. One of the main reasons for this is that software engineers do not always have a strong background in computer security and lack expertise in secure software system development. In spite of this, in practice, they are asked to develop software systems that call for security features. Without appropriate methodologies and modeling languages to guide them during the development process, it is likely that they will fail to produce effective solutions (McDermott & Fox, 1999). Articulating a body of knowledge is an essential step in the development of a profession because it represents a broad consensus regarding the contents of the discipline. The IEEE Computer Society, with the support of a consortium of industrial sponsors, has published the Guide to the Software Engineering Body of Knowledge (SWEBOK). It has also gained international recognition as ISO Technical Report 19759. Although the concept of security is not explicitly referred to in it, the Guide describes generally accepted knowledge about software engineering, and its ten knowledge areas summarize basic concepts and include a list of references to detailed information. This paper takes from the Guide a summary of the guidelines and practices that can measurably reduce software requirements, as well as design and implementation defects, and improve the education of current and future software developers. Our paper introduces a new way of teaching secure software engineering based on the SWEBOK Guide. This work differs from others by the following outcomes: * The topic of security will be highlighted through the SWEBOK Guide. * The summary of guidelines and practices are derived from the SWEBOK Guide to secure requirements analysis, design, implementation, and testing phases * The proposed topics to be covered in the course during the academic term are provided based on the SWEBOK Guide. Differences between our work and that of others are more detailed in the Literature Review section. The paper summarizes the guidelines and practices derived from the SWEBOK Guide in the Proposed Guidelines and Practices based on SWEBOK section. In the Proposed Course Topics section, it describes the detailed topics to be covered during the academic term, and in the section Suggested Recommendations to Enhance SWEBOK Guide we recommend some possible additions for SWEBOK 2010. The conclusions and our plans for future work are introduced in the last section. Literature Review Many authors have discussed the integration of security into the coding phase of the development process (Graff & Van Wyk, 2002; Howard & LeBlanc, 2002; Microsoft, 2009; Viega & McGraw, 2002, 2003). Howard and Leblanc (2002) described the best practices for writing secure code and stopping malicious hackers in their tracks, based on the knowledge of top security experts at Microsoft. …

Prevalence of diabetes mellitus in the rural southern Free State

SA Fam Pract 2009;51(6):502-505 Background: A worldwide increase in the prevalence of diabetes mellitus (DM) has been reported and an even further increase is expected as a result of lifestyle changes. The objectives of this study were to determine the prevalence of DM in the rural southern Free State and to investigate the contribution of risk factors such as age, physical activity, body mass index (BMI), waist-to-hip ratio and waist circumference to the development of impaired fasting glucose (IFG) or DM. Methods: Fasting venous plasma glucose (FVPG) levels were obtained from a total of 552 participants from Springfontein (n = 195), Trompsburg (n = 162) and Philippolis (n = 180). Participants were between 25 and 64 years of age, with 28.1% male (mean age 47.3 years) and 71.9% female (mean age 46 years). Anthropometric status was determined using standardised techniques. Levels of physical activity were determined using a 24-hour recall of physical activity as well as frequency of performing certain activities. Relative risks (RR) as well as 95% confidence intervals (95% CI) were used to distinguish significant risk factors for having IFG or DM. Results: In the study population the prevalence of DM was 7.6% (5.2% in men and 8.6% in women) and that of IFG was 6.3% (4.5% in men and 7.1% in women). The majority of nondiabetic (34%), IFG (55%) and DM (61%) participants were between the ages of 51 and 60 years. Age was found to be a statistically significant risk factor for having IFG or DM in participants older than 40 years of age (RR 2.3; 95% CI (1.22; 4.34)). Crude measurements (not age- and gender-adjusted) of waist circumference (RR 3.23; 95% CI (1.82; 5.74)), BMI (RR 2.32; 95% CI (1.43; 3.78)) and waist-to-hip ratio (RR 2.51; 95% CI (1.55; 4.07)) were statistically significant risk factors for having IFG or DM. Physical inactivity in men ≥ 40 years was also a statistically significant risk factor (RR 3.23; 95% CI (1.15; 9.05)) for having IFG or DM. Conclusions: In this study, 37.5% of diabetics were newly discovered. A high waist circumference, BMI and waist-to-hip-ratio were associated with an increased risk for developing IFG or DM, with a high waist circumference being the most significant general risk factor. Physically inactive men (≥ 40 years) were also at a higher risk of having IFG or DM. Follow-up FVPG and glucose tolerance tests should be performed on participants in the IFG group. A need for intervention regarding the identification and treatment of DM in these rural areas has been identified. a van Wyk HJ, MBChB, MMed (Clin Pathol) b

A revision of the genus Bolusia (Fabaceae, Crotalarieae)

A taxonomic revision of Bolusia Benth. is presented. Diagnostic characters at generic level are the dentate stipules, the helically coiled keel of the flowers, the glabrous style and the chromosome number of 2 n = 18. The five species recognised in this revision are all endemic to tropical Africa south of the equator. They are B. amboensis (Schinz) Harms, B. resupinata Milne-Redhead, B. ervoides (Welw. ex Baker) Torre, B. acuminata (DC.) Polhill and B. grandis B.-E. Van Wyk. One species from Tanzania is insufficiently known and no material is available for study. Bolusia is morphologically rather uniform, so that morphological characters do not allow for a meaningful analysis of phylogenetic relationships within the genus. ITS, rbcL and morphological data confirmed the sister relationship between Crotalaria and Bolusia. The revision includes a brief discussion of morphological characters, phylogenetic relationships, a key to the species, a distribution map, descriptions and synonymies, together with the correct nomenclature and typification of the genus and the species.

A new species of Polemanniopsis (Apiaceae) from Namibia

A new species of woody Apiaceae, Polemanniopsis namibensis B-E. Van Wyk, A. Burke & C. Mannheimer, is described. The species is allied to Polemanniopsis marlothii but differs in the much smaller habit of (up to 0.6 m vs 1.5–4 m in Polemanniopsis marlothii), the white or greyish colour of the twigs (brown in Polemanniopsis marlothii), the 3-foliolate leaves (predominantly 5-foliate in Polemanniopsis marlothii), the smaller inflorescences with persistent involucral bracts (caducous in Polemanniopsis marlothii) and anatomical details of the leaves. The species is endemic to Namibia and is known only from a localised area in the southern Namib desert near Lüderitz, where it is relatively common.

An interdisciplinary look at legumes and their bacterial symbionts: some thoughts from Big Sky

An interdisciplinary look at legumes and their bacterial symbionts: some thoughts from Big Sky

Evaluation of several tree species for activity against the animal fungal pathogen Aspergillus fumigatus

Aspergillus fumigatus causes severe problems in poultry production systems. Seven South African tree species were selected from the database of the Phytomedicine Programme based on its antifungal activity against the fungus Cryptococcus neoformans. The acetone leaf extracts of the selected species had minimum inhibitory concentrations (MICs) of 0.16 mg/ml and lower in the preliminary screening. The antibacterial and antifungal activities of hexane, dichloromethane, acetone and methanol extracts of the leaves were determined using a two-fold serial microdilution method against a range of commonly encountered animal pathogenic fungi ( A. fumigatus, Candida albicans, C. neoformans, Microsporum canis and Sporothrix schenckii) and four nosocomial bacteria ( Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa). The plant species investigated were Combretum vendae (A.E. van Wyk) (Combretaceae), Commiphora harveyi (Engl.) Engl. (Burseraceae), Khaya anthotheca (Welm.) C.DC (Meliaceae), Kirkia wilmsii Engl. (Kirkiaceae), Loxostylis alata A. Spreng. ex Rchb. (Anacardiaceae), Ochna natalitia (Meisn.) Walp. (Ochnaceae) and Protorhus longifolia (Bernh.) Engl. (Anacardiaceae). All the extracts had activity against at least one of the test organisms over an incubation period of 24 or 48 h. The MIC values of the non-polar and intermediate polarity extracts of O. natalitia, K. anthotheca, C. vendae, C. harveyi, and P. longifolia had MICs as low as 0.08 mg/ml against at least one of the tested bacteria. Furthermore, the acetone extracts of L. alata, K. wilmsii, O. natalitia and C. vendae had antifungal activities with MIC values ranging from 0.04 to 0.08 mg/ml against at least one of the tested fungi. The average MIC values of the plant extracts against the different bacteria ranged from 0.17 to 2.11 mg/ml, while the range was 0.23–1.98 mg/ml for fungi. The Gram-positive bacteria ( S. aureus and E. faecalis) were more susceptible to the plant extracts than the Gram-negative bacteria ( E. coli and P. aeruginosa). E. faecalis was the most susceptible microbe and C. vendae extracts were the most active against nearly all the bacteria tested. The acetone extract of L. alata was the most active against fungal pathogens, with activity against at least 3 fungal organisms. L. alata was selected for further work to isolate compounds active against A. fumigatus and other fungal pathogens.

Legitimate Peripheral Participation (LPP) – The case for Recognition of Prior Learning sites and knowledges in South Africa's transforming education system

By definition and purpose, education is the development of human capital towards meeting the individual and social needs of learners and their societies. This transdisciplinary collaboration parallels the underpinning principle of Lave and Wenger's Legitimate Peripheral Participation ( Lave & Wenger, 1990) to South Africa's post-colonial legitimation of alternative sites and enskilment canons. Central to both is legitimation of knowledge acquisition from communities of practice or sites and ‘knowers’ ( Mphahlele, 1992) ‘outside formal institutions’ of teaching/learning. Considered and termed ‘informal’ and by deduction, less legitimate for meritorious enskilment, the South African Qualifications Authority (1995, 2002) decrees a transformative paradigm and method of validating these sites and their skills production. SAQA highlights the fact that the pedagogical approach of such sites is context- and learner-centred with demonstrable socially valuable skills. This post-colonial mandate thus centres the Recognition of Prior Learning (RPL) as an acknowledgement of multiple foci of skills production, decreeing their overdue certification, as in our case study of the Van Wyk situation. The approach confronts and deconstructs the colonial marginalisation of human capital from outside ‘formal’/official institutions. It is part of the ideological framework of redressing the race and class exclusion mechanisms of artisans and others from the landscape of skills possession. It subscribes therefore to the canon of different ‘ways of knowing’ ( Mosala, 1998). Van Wyk's narrative exemplify the merits of ‘outside-institutions’ learning and enskilment to various levels of complexity. The objective of such legitimation is that certification provides credibility and legitimacy, thereby widening the marketability of apprentices' skills. The social recognition and accorded certification thereof carries uncontested confirmation of expertise.

The generic concept of Lebeckia (Crotalarieae, Fabaceae): Reinstatement of the genus Calobota and the new genus Wiborgiella

Evidence from the internal transcribed spacer (ITS) of nuclear ribosomal DNA and plastid rbcL data revealed that the genus Lebeckia Thunb. as currently circumscribed may not be monophyletic. These analyses, combined with morphological and anatomical data, showed that the genus could be divided into three genera: (1) Lebeckia sensu stricto ( L. section Lebeckia); (2) Calobota [ L. section Calobota (Eckl. and Zeyh.) Benth. and L. section Stiza (E.Mey.) Benth.] including the monotypic, North African genus Spartidium Pomel; (3) a new genus, Wiborgiella [ L. section Viborgioides Benth., together with L. inflata Bolus, L. mucronata Benth. and Wiborgia humilis (Thunb.) Dahlgr.]. The reinstatement of the genus Calobota Eckl. and Zeyh. is proposed and Wiborgiella Boatwr. and B.-E. Van Wyk described as new. Synopses of the genera Calobota and Wiborgiella, including nomenclature, synonymy, descriptions and diagnostic characters are presented.

On the compressive response of carbon nanotube tangles

The nonlinear bulk compressibility of entangled multiwalled carbon nanotubes is studied. The analogy with textile fibre assemblies is explored by means of the well established van Wyk model. In view of the small diameter of the nanotubes, the possible effect of adhesive van der Waals interactions at tube–tube contacts is analysed. It is found, however, that the contribution of adhesive contacts to the bulk stress should be negligible. Compression experiments are performed on multi-walled carbon nanotubes and show that van Wyk's model is able to describe the response, although the values of the dimensionless parameter k of van Wyk's model were lower than expected. There is indeed no indication that van der Waals interactions play any significant role.

Africanisation of education and the search for relevance and context

As the 21st century dawned, some African intellectuals were already contemplating an education system based on African philosophy and African values. These intellectuals were motioning for an education system that would uphold the indigenous knowledge systems (Makgoba, 1996; Seepe, 2004; Higgs and Van Wyk, 2007). This group also contends that through education, African societies will be enhanced if education reflects the local indigenous knowledge systems. Other critics though, believe that africanising education institutions, will not only lower standards, but that it will also be incongruent to globalisation as indigenous knowledge systems will not be compatible with modernisation. The article comprises of a literature study focusing on the challenges arising as a result of several stakeholders, whose proposals include the africanisation of knowledge in formal education institutions in Africa. The article also examines whether formal (africanised) education has the potential to democratise and transform society. As South Africa is gradually changing socially and politically, many see education as a vehicle for improving the political, social and economic landscape. Key words: Africanisation, African renaissance, African philosophy, indigenous, Indigenous knowledge systems (IKS).

A taxonomic revision of Capnophyllum (Apiaceae: Apioideae)

The Cape endemic genus Capnophyllum Gaertn. is revised. As a result of valuable recent collections and extensive fieldwork, this hitherto neglected genus was found to comprise four annual species, two of which are newly described, namely C. lutzeyeri Magee and B.-E.van Wyk, and C. macrocarpum Magee and B.-E.van Wyk. The four species are distinguished from one another by their fruit morphology (relative length of the styles, the shape and position of the stylopodium, fruit size, surface sculpturing, and the presence or absence of a sterile apical portion) and fruit anatomy (marginal wings slightly or prominently involute and secondary ribs present or absent). A comprehensive key to the species, their complete nomenclature and typification, together with complete descriptions and known geographical distributions for all the species are presented and illustrated.

Ovarian tumor in a 12‐year old female with severe hypothyroidism: A case of Van Wyk and Grumbach syndrome

We report a 12-year-old female presenting with an abdominal tumor. Diagnostic workup revealed giant bilateral ovarian cysts, severe hypothyroidism as well as an elevation of CA 125. We refrained from ovariectomy, which would be necessary for a malignant tumor, in view of an evident Van Wyk and Grumbach syndrome. The patient promptly responded to L-thyroxine with complete regression of all symptoms. Hypothyroidism should be considered in the evaluation of ovarian cysts. Although the Van Wyk and Grumbach syndrome is rare, it is crucial to rule it out in order to avoid unnecessary ovarian surgery when thyroid replacement is completely sufficient.

Van Wyk and Grumbach syndrome revisited: imaging and clinical findings in pre- and postpubertal girls

Van Wyk and Grumbach syndrome revisited: imaging and clinical findings in pre- and postpubertal girls

Introduction: Uveal melanoma

Introduction: Uveal melanoma

A revision of Lebeckia sect . Lebeckia: The L. pauciflora and L. wrightii groups (Fabaceae, Crotalarieae)

All 14 species of the type section of the genus Lebeckia Thunb. are endemic to the Cape Floristic Region and are easily recognized by their phyllodinous, acicular (needle-shaped) leaves. Ten of the 14 species, comprising the L. sepiaria and L. plukenetiana groups, have already been revised. The last two groups are formally treated in this paper: 1. the L. pauciflora group (two virgate perennials with terete to semi-terete, stipitate fruits) and 2. the L. wrightii group (two trailing fireweeds with flat, sessile fruits). One of these, L. uniflora B-E.van Wyk and M.M.le Roux sp. nov., is here described as new. The new species was previously confused with L. wrightii (Harv.) Bolus but differs in the single-flowered inflorescences, larger flowers and black seeds. The nomenclature, typification, morphological and diagnostic characters are presented as well as distribution maps. A comprehensive key to all 14 species of section Lebeckia is provided.

Phylogenetic relationships in the genus Lichtensteinia (Apiaceae) based on morphological, anatomical and DNA sequence data

Evolutionary relationships within the poorly known and anomalous South African endemic genus Lichtensteinia were elucidated. Phylogenetic analysis of morphological and anatomical characters suggests that there are two main groups of species, viz. the L. obscura– L. globosa– L. interrupta (including L. kolbeana) clade and the L. latifolia– L. trifida– L. lacera– L. crassijuga clade. Furthermore, Lichtensteinia is not monophyletic, with the former group allied weakly with the Namibian endemic genus Marlothiella and the latter group allied strongly with Annesorhiza macrocarpa. In contrast, the results of phylogenetic analyses of nrDNA ITS and cpDNA trnQ-5'trnK sequences, separately and combined, as well as the results of a total evidence analysis of all available data, suggest three main groups of species in a monophyletic Lichtensteinia: the aforementioned L. latifolia– L. trifida– L. lacera– L. crassijuga complex, a clade comprising L. interrupta and L. globosa, and L. obscura. DNA sequence data, however, are not currently available for Marlothiella. The new species L. globosa B.-E. Van Wyk and P.M. Tilney is sister group to L. interrupta in the molecular analyses; in the analysis of morphological/anatomical data, however, the relationships among L. globosa, L. interrupta and L. obscura are equivocal. Lichtensteinia lacera and L. trifida are each not monophyletic based on the molecular phylogenies. The various populations of L. lacera and L. trifida examined are morphologically quite distinct, with large differences observed among populations but limited variation within populations. The size and shape of the leaves and of the marginal teeth, as well as the presence and length of setae, were found to be of diagnostic value in distinguishing among the species.

Arnold Van Wyk's <i>Primavera</i>: Music Of Another South Africa

Coinciding with what would have been his 90th birthday is a long overdue resurgence of interest in Arnold van Wyk (1916-1983).1 This may be due to the greater accessibility now of his private documents, especially his autographs, sketches, letters and other unpublished material in the care of the library of the University of Stellenbosch. But at the same time there seems to be a growing recognition in musical circles of Van Wyk's significance as one of the pioneers of South African music. Both trends are to be welcomed, and hopefully they will translate into more frequent performances of his music, so that he also receives the recognition within the broader musical culture that is his due. South African Music Studies Vol. 26-27 2006/7: pp. 87-107

A new species of Lichtensteinia (Apiaceae)

Lichtensteinia globosa B.-E. Van Wyk & P.M. Tilney, a distinct new species from the Cedarberg Mountains in the Western Cape Province of South Africa, is described. The new species is related to Lichtensteinia interrupta (= L. kolbeana) but differs in having tuberculate (pustulate), globose fruits (fruits smooth in all other species and strongly dorsally compressed in all except L. obscura and L. interrupta). It is geographically isolated from L. interrupta, which has a wide distribution in the southern and eastern coastal parts of South Africa. The new species has serrate–aristate leaf margins and pustulate fruits which appear to further reduce the taxonomic distance between Lichtensteinia and the subfamily Saniculoideae, where bristly or even spiny leaf margins and tuberculate fruits are common. Furthermore, Lichtensteinia species also have crystals right around the pericarp, rounded cotyledons, large rib oil ducts and a complete absence of vittae, all of which are typical of the Saniculoideae.

A Dime a Day: The Possibilities and Limits of Private Schooling in Pakistan

This paper looks at the private schooling sector in Pakistan, a country that is seriously behind schedule in achieving the Millennium Development Goals. Using new data, the authors document the phenomenal rise of the private sector in Pakistan and show that an increasing segment of children enrolled in private schools are from rural areas and from middle-class and poorer families. The key element in their rise is their low fees - the average fee of a rural private school in Pakistan is less than a dime a day (Rs.6). They hire predominantly local, female, and moderately educated teachers who have limited alternative opportunities outside the village. Hiring these teachers at low cost allows the savings to be passed on to parents through low fees. This mechanism - the need to hire teachers with a certain demographic profile so that salary costs are minimized - defines the possibility of private schools: where they arise, fees are low. It also defines their limits. Private schools are horizontally constrained in that they arise in villages where there is a pool of secondary educated women. They are also vertically constrained in that they are unlikely to cater to the secondary levels in rural areas, at least until there is an increase in the supply of potential teachers with the required skills and educational levels.