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Health clinic gardens in North-West province, South Africa, as complex social-ecological systems
No full textThe world’s urban population (54%) is currently increasing. The fastest growth rates are expected to occur in urban areas of Africa and Asia. Since urban areas will continue to expand, ecological studies should also take social influences into consideration. Changes in social-ecological systems are often studied by using a resilience thinking approach. The diversity of biophysical and social factors can play an important role in maintaining resilience of a social-ecological system. Complex or “wicked” problems can occur at the interface of social and ecological systems which contain many interacting factors making it difficult to solve. Poverty, food and nutrition security and biodiversity loss are some of South Africa’s main “wicked” problems. Although food is available in most parts of South Africa, the nutrient content of the food consumed is not sufficient. Health clinics were established across South Africa (in urban and rural areas) to provide free health care, but their gardens may also have several advantages. The first aim of this study was to determine the plant species composition, floristic and functional diversity at each health clinic garden and to compare it to home/domestic gardens in the North-West Province as well as over the different local municipalities of the Bojanala District Municipality. The second aim was to determine the resource diversity (social and physical) of these gardens and to compare them over the different local municipalities. The third aim was to determine the perceptions of the different stakeholders on ecosystem services and disservices at health clinic gardens. A subset of best practice clinics was also identified which can contribute towards developing a management framework to ensure a more resilient system of health clinic gardens in South Africa. Results showed that health clinic gardens are similar to home/domestic gardens in the North-West Province regarding dominant families, dominant genera and species representation except for the greater diversity of exotic ornamental species and endangered species present in home/domestic gardens. No clear difference could be found between local municipalities according to plant species composition. There was greater physical and social resource diversity at Moses Kotane and Moretele Local municipalities than at Rustenburg (physical) and Madibeng (social) Local municipalities. Although the individual perceptions of the stakeholders differed according to their role at the clinic garden, results showed that food and sense of place (as well as the spiritual value of the garden) were overall perceived as the most important ecosystem services of clinic gardens. Damonsville, Leseding and Reagile clinics obtained the highest score in comparison with other health clinic gardens in the Bojanala District Municipality and are good examples of best practise regarding diversity of natural, social and physical resources as well as perceptions of ecosystem services. It is suggested that the health clinic gardens should be managed using a step-by-step approach, starting with the limitations at the best practice (highest ranking scores) health clinic gardens. Communication between all stakeholders involved at the clinic gardens as well as with the community is one of the key factors that can contribute to successful management of health clinic gardens.National Research Foundatio
The technical assessment of individual performance in rugby union players
No full textPerformance in Rugby Union relies on a wide variety of contributions of different individual skills. Individual tasks, such as passing, kicking or scrummaging are dependent on an individual’s ability and may vary according to a player’s playing position. The focus of this thesis is a series of studies which have assessed the performance of individual rugby players (particularly related to the assessment of passing, kicking and scrummaging) and to evaluate such performance in relation to factors (most often kinematic factors) which have been identified and correlated to better performance. The main body of this thesis includes seven studies, in the form of original papers, which firstly describe the factors which contribute to rugby passing accuracy (two studies), thereafter two studies which focus on kicking success are described. The final three studies describe the development of a new device for measuring individual scrummaging performance. These studies also investigated: the role of body positioning in the generation of scrummaging force; and assessed how such factors may respond to the fatigue experienced over the duration of a rugby game.
One skill that all rugby players require is the ability to effectively pass the ball to another player. Two original research studies are presented in this thesis that describe multiple approaches to accomplishing passes in rugby players. A target frame was constructed, and the ball position relative to the centre of the target frame was recorded and reported as the accuracy error distance. The first study of this thesis assessed the accuracy of the running pass using self-selected passing strategies. Two strategies were identified: in-step passing and out-of-step passing, although differences in the step sequence resulted in no change in the pass accuracy. The second study evaluated the differences in accuracy and kinematic strategies used to execute the ground pass. Passes performed using a side-on body orientation were more accurate than those performed using a front-on body orientation. The two body orientations utilised different kinematic strategies: front-on relied on torso and pelvic
rotations, whereas the side-on relied less on trunk rotations and utilised greater extension angles of the stance arm.
Match victory can also be determined by individual kicking success, but in this case is reliant on the role of individual kickers in a team. In the third study, kinematic predictors of place kicking accuracy and distance were explored. Larger axial torso and pelvic rotations were related to further place kicks, and greater extensions of the stance arm was related to more accurate place kicks. However larger torso rotations, which were positively related to kicking distance, were negatively related to kick accuracy. The fourth study was devised to compare the kinematic sequences of two points scoring kicking types. The comparisons suggest that the body kinematics used during the place and drop kicks were not different, although kicking distances were further in the place kick.
The fifth study of this thesis evaluated the feasibility of a custom individual scrummaging ergometer. The design, calibration, and measurement accuracy of the individual scrum ergometer are presented. Application of the ergometer revealed differences in individual scrummaging attributes, such as position of force application and centre of pressure variation, of players in different playing positions. No differences were observed in the force magnitude between playing positions.
The sixth study investigated individual kinematic scrum performance using conventional kinematic techniques and the custom individual scrum ergometer. The results highlight the role of a lower body height and wider stance in the attainment of greater individual scrummaging forces. No static kinematic variables were related to individual scrum performance. The final study investigated the effects of fatigue resulting from a simulated rugby match on individual scrummaging kinetics and kinematics. Although an increase in psychological and physiological markers of fatigue were observed, no scrummaging
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differences were noted in peak forces or in body kinematics at peak force following the rugby match simulation.
In conclusion, the identification of performance related factors and the invalidation of others which have been identified in this body of work, may provide an opportunity for performance tailoring strategies of individual players, selection strategies for teams or even the tailoring of training practices to optimise performance. As an initial set of studies, however, many of these factors still need reassessment and validation by subsequent research and therefore this work has provided a number of research possibilities for later studies. To this end, a suggested topic of ensuing research may be to assess the repeatability of predictive power of the variables identified here, whether they are uniformly predictive over time or in different subject groups and lastly whether the individual performances (which were the focus of these studies) are translatable into team performance.National Research Foundatio
RNAi of selected insect genes
No full textDiuraphis noxia (Kurdjumov, Hemiptera: Aphididae), commonly known as the Russian wheat aphid (RWA), is regarded as one of the most destructive and widely distributed insect species in the world. Nonetheless, the currently available control strategies, including chemical pesticides, biological control agents, and RWA resistant wheat cultivars, are still very limited and rather ineffective. The process of double-stranded RNA (dsRNA)-mediated interference (RNAi) displays high specificity and the prospect of developing into a new specific method for managing agricultural pests. Plants can potentially be genetically engineered to express dsRNA to down-regulate vital gene functions present in pest insects, resulting in the protection of plants. In order to survive and reproduce, aphids require close interaction with their host plants, during which effectors are transported inside the plant to modify host cell processes. Four previously identified RWA salivary secretion proteins were investigated in the present study. However, cloning and sequencing results indicated that only two of the aforementioned proteins – C002 and 14-3-3 epsilon (ɛ) – could be potential protein elicitors in RWA. Thus, these two transcripts were subjected to RNAi experiments via artificial diet feeding and feeding on siRNA injected wheat leaf trials in order to investigate their role in RWA-host interactions and their importance in the survival and reproduction of the RWA. The relative expression levels of C002 and 14-3-3 ɛ at 0h were compared between SAM, the most virulent RWA biotype, and SA1, the least virulent RWA biotype in South Africa, and the results indicated that both transcripts had a higher relative expression in SAM than in SA1. Therefore, suggesting that C002 and 14-3-3 ɛ might play an important part in RWA virulence. From the RT-qPCR results it was evident that successful silencing of both C002 and 14-3-3 ɛ were achieved at 24h after initial siRNA exposure and that the transient silencing effect subsided thereafter. The expression data pertaining to the wheat leaf injection experiments, however, displayed high standard deviations that are not ideal and suggested that the expression of the transcripts differs greatly between the aphids within each group. This is likely due to the custom-made aphid cages and injection procedure of the siRNA into wheat leaves that appears to hinder the accuracy of the results. The fecundity data produced quite inconclusive results due to previously mentioned inadequacies and therefore an accurate and decisive conclusion cannot be drawn as to how the C002 and 14-3-3 ɛ silencing effects the survival and reproduction of the RWA. Both methods used for RNAi – the artificial diet trial and the injection of wheat leaves trial – have their drawback. After considering the RT-qPCR data, it appears as though the artificial diet trial produced more accurate and feasible results. Even so, the injection method establishes a more natural mode of feeding for the aphids and consequently more optimal cages need to be designed and tested to produce precise results.National Research Foundatio
Nutritional requirements and survival of the red wine spoilage yeast Brettanomyces bruxellensis
No full textBrettanomyces bruxellensis is a red wine spoilage yeast that plagues the wine industry. It
facilitates the formation of compounds such as volatile phenols, which impart negative aromas
in red wines. Its ability to survive in wine through adaptations to various stressors (e.g. high
ethanol and sulphur dioxide concentrations, low pH) have made it the subject of several studies.
These studies aim to understand its biology (and in particular its nutrient requirements) and its
survival mechanisms in general, as well as to detect and enumerate it accurately and to
eliminate it. Nevertheless, literature on the subject is at certain times contradictory with regard to
the nutritional needs of this yeast. The survival of this yeast for extended periods of time lead us
to question how it is so well adapted to this deficient environment. In other words, what
substrates does B. bruxellensis utilise to sustain growth or at least survival in such a nutrientdeficient
medium where stronger fermenters (e.g. Saccharomyces cerevisiae) cannot survive?
This study investigates the carbon and nitrogen source assimilation of three B. bruxellensis
strains in a defined and model synthetic wine medium. In addition, the growth kinetics were
determined (as well as the consumption pattern of the various carbon and nitrogen sources).
This was performed in conditions similar to bottle ageing (anaerobic) and barrel maturation
(semi-anaerobic). Furthermore, the purpose of assimilating these sources is explored with a
focus on growth or cell maintenance (i.e. survival with no growth). The data showed that carbon
consumption followed a step wise pattern. At first, sugars were consumed, thereby leading to
the production of ethanol and biomass concurrently. Upon complete consumption of the sugars,
malic acid was consumed together with ethanol, but only when oxygen was present for the
latter. These compounds were consumed slowly and resulted in the survival of the cells for a
period of 45 days. After this period, the consumption of ethanol allowed for the extended
functioning of the cell, however the assimilation of ethanol lead to an increasing degree of
imbalance (more and more NADH was produced with little to no conversion to NAD+) in the cell
and eventually lead to a slow but steady decline of the population. The formation of 4-
Ethylphenol (4-EP) was investigated in order to ascertain its ability to correct the redox potential
of the B. bruxellensis cell. The results displayed the partial regeneration of NAD+ during 4-EP
formation, however, this metabolic pathway alone is not solely responsible.
Unlike for carbon sources, the data showed that the assimilation of nitrogen compounds were
strain specific and certain strains required more nitrogen than the others. The sources of prime
importance were ammonia and arginine and were assimilated during the exponential growth
phase (i.e. during sugar consumption). During the stationary phase, proline was assimilated
regardless of the presence/absence of oxygen, possibly to counteract stressors in the cell and
ensure survival of the population.
This study contributes to an improved understanding of how B. bruxellensis survives in wine and
is able to maintain cell function for extended periods of time. This leads to a better
understanding of the spoilage yeast B. bruxellensis and will allow for the production of wine in
an integrated manner to avoid the proliferation of this microorganism.National Research Foundatio
Modulation of oxidative stress and inflammation using a grape seed derived polyphenol
No full textOxidative stress and inflammation are intricately interlinked, especially in the context of ageing/accelerated ageing, as well as several chronic disease states, where they are implicated as aetiological factors. In the past decade polyphenols have been investigated for their potent anti-oxidant as well as anti-inflammatory properties. Previous research by our group has highlighted the potential of a grape seed-derived polyphenol as both anti-oxidant and anti-inflammatory modality. However, no data has been generated in human models and the mechanism(s) of action is still largely unknown. Thus the aim of this study was to more comprehensively investigate potential anti-oxidant or anti-inflammatory mechanisms of a grape seed-derived polyphenol (PCO) on acute (as found with exercise) and chronic (as in ageing) models of oxidative stress.
After obtaining ethical clearance, blood samples were obtained from healthy human subjects from two different groups (aged (n=7) and young (n=14). In the young group a further distinction was made between sedentary (n=8) and fit individuals (n=6) whom we exposed to an HIIT exercise intervention to induce acute oxidative stress. Oxidative status was assessed in plasma using validated photometric and colorimetric assays and plasma myeloperoxidase (MPO) assessed as baseline inflammatory indicator. Neutrophils were isolated at rest (and after exercise from young fit subjects) and treated with the polyphenol in vitro for 1 hour. The chemokinetic capacity of treated and control neutrophils in response to a chemotactic signal was then determined using a Dunn chamber and live cell imaging. In addition, neutrophils were analysed for the expression of functional capacity markers (intracellular MPO, Fcγ Receptor IIIb (CD16) and CEACAM 8 (CD66b)) via flow cytometry. Oxidative status of neutrophils were also performed on isolates.
The results indicate that the aged population had significantly worse oxidative and inflammatory profiles than young sedentary controls - this was evident in their conjugated dienes content as well as decreased ferric reducing ability of plasma (FRAP). In neutrophils, aged and young subjects had increased chemokinetic accuracy and capacity after 1 hour of in vitro polyphenol treatment. The treatment was also associated with a shedding of CD16 and increased expression of CD66b - both linked to improved neutrophil motility. The intracellular MPO content of neutrophils indicated that PCO had an anti-inflammatory effect across groups. The exercise intervention did not induce measurable changes in oxidative stress or inflammation.
We therefore concluded that grape seed-derived polyphenols modulate inflammation and oxidative responses by facilitating more efficient neutrophil motility. This decreases the number of neutrophils required per response, effectively resulting in less secondary tissue damage, less oxidative stress and faster resolution of inflammation.National Research Foundatio
Analysing network motifs in a complex network of freight movements
No full textMotifs are over-represented subgraphs in a complex network, and represent the building blocks of the network. There is a lack of studies that apply complex network theory in a supply chain context. In this dissertation 3-node motifs were identified and analysed in a complex network representing direct freight trips between firms in the Nelson Mandela Bay Metropolitan, South Africa. The G-Tries and ISMAGS algorithms were tested on small complex networks, and were compared according to quantitative and qualitative properties. It was found that ISMAGS is the most suitable for this dissertation. Freight activities were identified from raw GPS traces of freight vehicles, and the activities were clustered into firms using a density-based clustering algorithm. Multi-objective optimisation indicated that the clustering parameter configuration
γ = (20, 20) can be used to increase the visual accuracy of the firms, while maximising the completeness of the complex network. The freight complex network was built by identifying direct trips between firms. Using ISMAGS, it was found that three firms with two (X0X) or three (XXX) reciprocal freight trips between them are statistically overrepresented in the network. A brewery, shopping centres, distribution centres, and truck stops frequently appeared in the motifs. Motifs that contain the brewery and one of the truck stops were identified as the most central motifs based on the number of direct freight trips that occur in the motifs. Some freight trips in XXX motifs occur frequently over long distances, increasing total transport costs of the firms. Supply chain improvements can be applied to these identified firms. It was also found that there is a relationship between ranking firms according to the number of motifs they appear in and their degree centrality scores. This relationship can be studied more rigorously in future work. Another avenue for future research is to study the supply chain structures of firms in motifs, as well as the commodity flows between firms in motifs.National Research Foundatio
Audit of predetermined objectives PFMA 2015-16
No full textThe Grants Management and Systems Administration (GMSA) Directorate hosted its 7th annual Research Administrators Workshop (RAW) from 4 to 6 October 2016 in Polokwane. The workshop aimed to bring together key stakeholders from universities and science councils across South Africa, including international delegates, to share experiences and best practices in research administration and management
The role of the DA in science councils
No full textThe Grants Management and Systems Administration (GMSA) Directorate hosted its 7th annual Research Administrators Workshop (RAW) from 4 to 6 October 2016 in Polokwane. The workshop aimed to bring together key stakeholders from universities and science councils across South Africa, including international delegates, to share experiences and best practices in research administration and management
The role of the designated authority
No full textThe Grants Management and Systems Administration (GMSA) Directorate hosted its 7th annual Research Administrators Workshop (RAW) from 4 to 6 October 2016 in Polokwane. The workshop aimed to bring together key stakeholders from universities and science councils across South Africa, including international delegates, to share experiences and best practices in research administration and management
A multi-objective approach towards geospatial facility location
No full textApplications of the sub-discipline of location science within the larger discipline of operations
research include the location of important facilities, such as hospitals, fire stations, libraries and
depots. Existing facility location resolution techniques are generally based on commercial and
transportation modelling criteria with little or no consideration given to the characteristics and
influence of surrounding terrain. Recent technological advances have, however, resulted in a sub-
field of location science rapidly increasing in popularity — the field of geospatial facility location.
Geospatial facility location science places a strong emphasis on terrain and environmental factors
in the search for suitable sites for facilities with complex location requirements. Examples of
such facilities include radars, telecommunication towers, watchtowers and wind turbines.
The applications in which geospatial facility location solution approaches are relevant generally
include only one type of facility. As a result, problem-specific solution approaches tailored to the
specific facility type considered are usually adopted. On closer inspection, however, the solution
approaches followed for these facility location problems reveal striking similarities which may be
exploited in a generic manner in order to provide more efficient solution tradeoff alternatives.
By removing the problem-specific approach to facility location modelling and the design of
the associated solution techniques, there is an opportunity to develop a generic, dynamically
implementable geospatial facility location framework which may be applied to identify facility
location trade-off alternatives in various applications. Moreover, networks of multiple facility
types may be considered in such a framework — something that is a rarity in the current
geospatial facility location literature. In view of the continual advancement of technology, a
generic geospatial facility location framework may even prove to be applicable to future facility
location problems in which the placement criteria are currently unknown.
The design of a generic geospatial facility location framework is therefore pursued in this dissertation.
A dynamic mathematical foundation, which eliminates facility-specific solution methodologies,
is established. A computerised concept demonstrator based on this framework is implemented
within a generic solution paradigm. This concept demonstrator accommodates as
special cases a variety of popular facility location problems from the literature. The geospatial
facility location framework is demonstrated to be a dynamic and useful tool for solving complex
facility location problems that have not previously been encountered due to the limitations of
problem-specific solution search designs.National Research Foundatio