Predictors of learner performance in mathematics and science according to a large-scale study in Mpumalanga

Eight hundred and ninety-nine (431 male, 467 female and one missing value) Grade 8 and 9 (n = 184 and 713, respectively, with two missing values) learners from secondary schools in Mpumalanga completed a science and mathematics questionnaire. Student's t tests showed that male and female, as well as language groups' scores, differed significantly. Stepwise non-linear regression shows that a combination of factors contributes significantly to learner, science and mathematics performance (R2 = 25%, 20%, and 11%, respectively). South African Journal of Education Vol. 26(2) 2006: 229–25

Aligning design with science : tree grids and rings in the landscape

Tree grids and tree rings pose certain challenges to the designer of landscapes especially designing hard landscapes such as pavements, parking areas and roadsides. One challenge is insufficient knowledge of lateral growth space required by tree stems over time. Inappropriate size selection may cause damage to tree rings, tree grids and trees, resulting in costly repairs and unsightly landscape features. Lack of a rigorous knowledge base may prevent the designer or urban forester from choosing appropriate ring or grid sizes. However, these situations may be prevented or avoided should the choices be based on scientific knowledge of tree stem growth rates. This paper presents the results of an investigation of stem growth rates of three indigenous savannah street trees species growing in the City of Pretoria, Gauteng Province, South Africa. The stem diameters of each species were measured at ground level. Random stratified sampling was conducted, with the total sample size being 282, the oldest tree being more than 46 years of age. Stem diameter was regressed on tree age to compute estimated stem diameter growth rates. Thereafter comparisons were made to rings found in the local landscape industry. The differences in growth rates showed that Combretum erytrophyllum, Searsia lancea and Searsia pendulina will outgrow small tree grids in approximately 10.75, 18.50, and 15.50 years, respectively. The paper suggests that the statistical analysis and modelling of field data increase certainty for design parameters, enhancing the excellence of urban landscapes and forests.Afrox, the Bradlows Foundation, the National Research Foundation (Grant no. 2053522) and the University of South Africa (Unisa).http://www.actahort.orgam2016Plant ScienceStatistic

Prevalence of oral and oropharyngeal human papillomavirus in a sample of South African men : a pilot study

BACKGROUND. Human papillomavirus (HPV) infection is well known to be associated with head and neck cancers (HNCs). HPV-associated HNCs are related to sexual behaviour, particularly the lifetime number of oral sex partners, but the epidemiology of oral and oropharyngeal HPV in South African men has not yet been studied. Objectives. To determine the oral and oropharyngeal HPV strain prevalence and associated factors in a selected male population in Pretoria, South Africa (SA). METHODS. Male factory workers were recruited. Oral rinse and gargle samples were tested for 37 HPV types using the Linear Array HPV Genotyping Test (Roche Molecular Systems). A questionnaire was used to obtain information regarding age, medical conditions, substance and alcohol use and sexual behaviour. HIV testing was optional. RESULTS. The HPV prevalence was 5.6% among men (N=125) aged 17 - 64 years. High-risk HPV (hrHPV) types 16 and 68 were found in two men. Oral sex seemed to be an uncommon practice in the majority of respondents, but the two respondents with hrHPV did practise oral sex. There was a statistically significant association between HPV infection and an increased number of sexual partners (p=0.027), but not between HPV and substance use, HIV status or clinical mucosal pathology. CONCLUSION. The prevalence of oral and oropharyngeal HPV was lower than reported in other countries. An association between oral HPV and having multiple sexual partners was found. A larger nationwide study would give a more representative view of the burden of oral and oropharyngeal HPV infection in SA.The Dental Research Education and Development Trust of the South African Dental Associationhttp://www.samj.org.zaam201

Neoadjuvant chemoradiotherapy plus surgery versus active surveillance for oesophageal cancer: A stepped-wedge cluster randomised trial

Background: Neoadjuvant chemoradiotherapy (nCRT) plus surgery is a standard treatment for locally advanced oesophageal cancer. With this treatment, 29% of patients have a pathologically complete response in the resection specimen. This provides the rationale for investigating an active surveillance approach. The aim of this study is to assess the (cost-)effectiveness of active surveillance vs. standard oesophagectomy after nCRT for oesophageal cancer. Methods: This is a phase-III multi-centre, stepped-wedge cluster randomised controlled trial. A total of 300 patients with clinically complete response (cCR, i.e. no local or disseminated disease proven by histology) after nCRT will be randomised to show non-inferiority of active surveillance to standard oesophagectomy (non-inferiority margin 15%, intra-correlation coefficient 0.02, power 80%, 2-sided α 0.05, 12% drop-out). Patients will undergo a first clinical response evaluation (CRE-I) 4-6 weeks after nCRT, consisting of endoscopy with bite-on-bite biopsies of the primary tumour site and other suspected lesions. Clinically complete responders will undergo a second CRE (CRE-II), 6-8 weeks after CRE-I. CRE-II will include 18F-FDG-PET-CT, followed by endoscopy with bite-on-bite biopsies and ultra-endosonography plus fine needle aspiration of suspected lymph nodes and/or PET- positive lesions. Patients with cCR at CRE-II will be assigned to oesophagectomy (first phase) or active surveillance (second phase of the study). The duration of the first phase is determined randomly over the 12 centres, i.e., stepped-wedge cluster design. Patients in the active surveillance arm will undergo diagnostic evaluations similar to CRE-II at 6/9/12/16/20/24/30/36/48 and 60 months after nCRT. In this arm, oesophagectomy will be offered only to patients in whom locoregional regrowth is highly suspected or proven, without distant dissemination. The main study parameter is overall survival; secondary endpoints include percentage of patients who do not undergo surgery, quality of life, clinical irresectability (cT4b) rate, radical resection rate, postoperative complications, progression-free survival, distant dissemination rate, and cost-effectiveness. We hypothesise that active surveillance leads to non-inferior survival, improved quality of life and a reduction in costs, compared to standard oesophagectomy. Discussion: If active surveillance and surgery as needed after nCRT leads to non-inferior survival compared to standard oesophagectomy, this organ-sparing approach can be implemented as a standard of care

Does delay in diagnosing colorectal cancer in symptomatic patients affect tumor stage and survival? A population-based observational study

<p>Abstract</p> <p>Background</p> <p>Diagnosing colorectal cancer (CRC) at an early stage improves survival. To what extent any delay affects outcome once patients are symptomatic is still unclear.</p> <p>Our objectives were to evaluate the association between diagnostic delay and survival in symptomatic patients with early stage CRC and late stage CRC.</p> <p>Methods</p> <p>Prospective population-based observational study evaluating daily clinical practice in Northern Holland. Diagnostic delay was determined through questionnaire-interviews. Dukes' stage was classified into two groups: early stage (Dukes A or B) and late stage (Dukes C or D) cancer. Patients were followed up for 3.5 years after diagnosis.</p> <p>Results</p> <p>In total, 272 patients were available for analysis. Early stage CRC was present in 136 patients while 136 patients had late stage CRC. The mean total diagnostic delay (SE) was 31 (1.5) weeks in all CRC patients. No significant difference was observed in the mean total diagnostic delay in early versus late stage CRC (<it>p </it>= 0.27).</p> <p>In early stage CRC, no difference in survival was observed between patients with total diagnostic delay shorter and longer than the median (Kaplan-Meier, log-rank <it>p </it>= 0.93).</p> <p>In late stage CRC, patients with a diagnostic delay shorter than the median had a shorter survival than patients with a diagnostic delay longer than the median (log-rank <it>p </it>= 0.01). In the multivariate Cox regression model with survival as dependent variable and median delay, age, open access endoscopy, number and type of symptoms as independent variables, the odd's ratio for survival in patients with long delay (>median) versus short delay (≤median) was 1.8 (95% confidence interval (CI) 1.1 to 3.0; <it>p </it>= 0.01). Tumor-site was not associated with patient survival. When separating late stage CRC in Dukes C and Dukes D tumors, a shorter delay was associated with a shorter survival in Dukes D tumors only and not in Dukes C tumors.</p> <p>Conclusion</p> <p>In symptomatic CRC patients, a longer diagnostic and therapeutic delay in routine clinical practice was not associated with an adverse effect on survival. The time to CRC diagnosis and initiation of treatment did not differ between early stage and late stage colorectal cancer.</p

The diversity and evolution of pollination systems in large plant clades: Apocynaceae as a case study

Background and Aims Large clades of angiosperms are often characterized by diverse interactions with pollinators, but how these pollination systems are structured phylogenetically and biogeographically is still uncertain for most families. Apocynaceae is a clade of >5300 species with a worldwide distribution. A database representing >10 % of species in the family was used to explore the diversity of pollinators and evolutionary shifts in pollination systems across major clades and regions. Methods The database was compiled from published and unpublished reports. Plants were categorized into broad pollination systems and then subdivided to include bimodal systems. These were mapped against the five major divisions of the family, and against the smaller clades. Finally, pollination systems were mapped onto a phylogenetic reconstruction that included those species for which sequence data are available, and transition rates between pollination systems were calculated. Key Results Most Apocynaceae are insect pollinated with few records of bird pollination. Almost three-quarters of species are pollinated by a single higher taxon (e.g. flies or moths); 7 % have bimodal pollination systems, whilst the remaining approx. 20 % are insect generalists. The less phenotypically specialized flowers of the Rauvolfioids are pollinated by a more restricted set of pollinators than are more complex flowers within the Apocynoids + Periplocoideae + Secamonoideae + Asclepiadoideae (APSA) clade. Certain combinations of bimodal pollination systems are more common than others. Some pollination systems are missing from particular regions, whilst others are over-represented. Conclusions Within Apocynaceae, interactions with pollinators are highly structured both phylogenetically and biogeographically. Variation in transition rates between pollination systems suggest constraints on their evolution, whereas regional differences point to environmental effects such as filtering of certain pollinators from habitats. This is the most extensive analysis of its type so far attempted and gives important insights into the diversity and evolution of pollination systems in large clades