An analysis of the efficiency of player performance at the 2011 Cricket World Cup

In limited overs cricket, efficiency plays a significant role in team success. Batsmen especially are under pressure to score quickly rather than in large quantities because only 50 overs are available per innings. This paper uses data envelopment analysis (DEA) and stochastic multicriteria acceptability analysis (SMAA) to assess the efficiency with which players at the 2011 Cricket World Cup converted inputs (balls faced or bowled) into performance outputs. The effect that non-discretionary variables like the cricketing resources available to a player have on his efficiency is controlled for, allowing for a fairer assessment across players from different countries

Breeding systems of floral colour forms in the Drosera cistiflora species complex

The study was supported by the National Research Foundation of South Africa (Grant 46372 to SDJ).Variation in plant breeding systems has implications for pollinator‐mediated selection on floral traits and the ecology of populations. Here we evaluate pollinator contribution to seed production, self‐compatibility and pollen limitation in different floral colour forms of Drosera cistiflora sensu lato (Droseraceae). These insectivorous perennial plants are endemic to fynbos and renosterveld vegetation in the Cape Floristic Region of South Africa, and the species complex includes five floral colour forms (pink, purple, red, white and yellow), some of which are known to be pollinated by beetles. Controlled hand‐pollination experiments were conducted in 15 populations of D. cistiflora s.l. (two to four populations per floral colour form) to test whether the colour forms vary in their degree of self‐compatibility and their ability to produce seeds through autonomous self‐fertilization. Yellow‐flowered forms were highly self‐incompatible, while other floral colour forms exhibited partial self‐compatibility. Seed set resulting from autonomous selfing was very low, and pollinator dependence indices were high in all populations. Since hand cross‐pollination resulted in greater seed set than open pollination in 13 of the 15 populations, we inferred that seed production is generally pollen‐limited.Drosera cistiflora s.l. typically exhibits high levels of pollinator dependence and pollen limitation. This is unusual among Drosera species worldwide and suggests that pollinators are likely to mediate strong selection on attractive traits such as floral colour and size in D. cistiflora s.l. These results also suggest that the floral colour forms of D. cistiflora s.l. which are rare and threatened are likely to be vulnerable to local extinction if mutualisms were to collapse indefinitely.PostprintPeer reviewe

An analysis of corporate board networks in South Africa

In this paper we analyse the networks created from directors sitting on the boards of companies in South Africa. We consider two projections of this network: a director network, in which only directors are present and two directors are linked if they sit together on one or more common boards; and a firm network, in which only firms are present and an edge indicates that the two firms share one or more directors. We describe these networks in terms of the statistical properties that they possess, and compare them to theoretical values obtained under various random network models. The network analysis is the first to be applied to a relatively small emerging economy like South Africa. We find that many of the features previously found to hold for highly-developed countries also apply here, suggesting that corporate networks may be fairly robust to stages of economic development

Co-authorship networks in South African chemistry and mathematics

CITATION: Durbach, I. N., Naidoo, D. & Mouton, J. 2008. Co-authorship networks in South African chemistry and mathematics. South African Journal of Science, 104:487-492.The original publication is available at https://journals.co.zaCo-authorship networks are graphs in which the nodes of the graph represent authors and two authors are connected by an edge if they have written one or more papers together. When applied to the authorship of scholarly papers, analysing the structure of a co-authorship network can provide useful insights into the way in which research is carried out in a particular field. We examine two co-authorship networks in our article, constructed from papers written on the subjects of chemistry and mathematics during the period 1990 to 2005, in which at least one of the authors was South African. Local results are compared with other studies conducted in much larger discipline-wide networks. We find that many of the same patterns exist locally, with the main difference being a far more fragmented South African mathematics network. We discuss some tentative implications of these results.https://journals.co.za/content/sajsci/104/11-12/EJC96734Publisher's versio

Integrating Operators' Preferences into Decisions of Unmanned Aerial Vehicles: Multi-layer Decision Engine and Incremental Preference Elicitation

International audienceDue to the nature of autonomous Unmanned Aerial Vehicles (UAV) missions, it is important that the decisions of a UAV stay consistent with the priorities of an operator, while at the same time allowing them to be easily audited and explained. We therefore propose a multi-layer decision engine that follows the logic of an operator and integrates its preferences through a Multi-Criteria Decision Aiding model. We also propose an incremental approach to elicit the operator's preferences, in view of minimizing his/her cognitive fatigue during this task