South Africa has an array of mining commodities which all play an integral role in our everyday surroundings, income, and most importantly, in the economy of the country. These mining activities also produce vast amounts of discard material, better known as tailings material, which is stored in different ways after extraction has taken place. Usually, storage entails the construction of tailings storage facilities, normal discard or tailings dumps. The upper surfaces of these anthropogenic structures are usually unstable and are, in most cases, characterised by different forms of erosion. This can be due to the chemical and physical properties of the materials of which they are constructed, but mainly due to unstable construction geomorphology, steep slopes, which leads to poor water run-off management and subsequent instability. Therefore, these structures need to be actively managed in order to increase and maintain their stability. Grass establishment, as a stabilisation technique, is the most effective out of all of the techniques, but there are certain constraints regarding this method (Titshall et al. 2013). The most costly constraint is nutrient supplementation during aftercare phases. In order to minimize this cost, new and innovative technologies need to be explored, and trialled. The contribution of soil biological processes in this regard was assessed, in order to minimise anthropogenic inputs. These biological processes refer to the fixation of atmospheric nitrogen by nodular root bacteria that grow on a group of plants referred to as legumes. These bacteria, also known as rhizobia, live in a symbiotic relationship with the host plant where they receive energy in the form of nutrients by trading nitrogen, which is an essential plant nutrient. Nine different tailings materials from different commodities available from South African Mines were selected. For a control medium, a well-drained soil type with an apedel structure and a clay content of approximately 6% was selected in order to promote optimal natural growth. These materials were chemically and physically analysed in order to develop a more holistic understanding on a micro scale level, as well as to ascertain possible constraints in this regard. Pot trials were selected as the experimental method in order to apply more specific control over root growth, plant development and growing conditions. The experimental data were collected over one growing season for both live forms. For this study, seven legume species were selected for establishment in the tailings materials in order to investigate their establishment potential in the growth mediums and their ability to fixate nitrogen. Based on the data, specific species were identified as viable options to include in future tailings amelioration projects; it can be assumed that the nitrogen produced by these species will be available in the growth medium for uptake by neighbouring plants that lack this biological function. These plants will also play a vital role in the long-term sustainable development of vegetation in the anthropogenic growth mediums. Sericea lespedeza had the highest enrichment ability during this study. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

The Swedish Island of Gotland provides an interesting case of how renewable energy technologies can be combined and integrated into the electricity system. The study simulates the load, wind power production and PV power production to estimate the PV power potential for existing buildings on Gotland. The theoretical PV power potential on Gotland is calculated to be 667 MW. The PV power potential is split between 28% for dwelling buildings, 9% for multi-dwelling buildings, 7% for industry and 56% for other buildings. The current limit for wind power on Gotland is 195 MW. With the installed capacity of 194 MW wind power, an additional of 22 MW of PV power is possible to integrate without increasing the hours of overload on the power cable. With the prospected submarine power cable, a total of 529 MW PV power is possible to integrate with the existing 194 MW of wind power.

Studiens syfte var att ta reda på hur chefer uppfattar begreppet ”chefspotential”, hur medarbetare med denna potential identifieras och sedermera utvärderas i verksamheten. Detta ska ses i ljuset av att allt färre vill bli chefer idag och att chefen spelar en avgörande roll för medarbetarens fortsatta karriärsutveckling. Studien har genomförts med hjälp av semistrukturerade intervjuer och analyserats utifrån begrepp så som ”potential”, ”identifiering” och ”utvärdering”. Studien visar att chefernas egen preferens vad gäller vem som uppfattas ha ”chefspotential” väger tungt i bedömningen av vem som blir identifierad som chefspotential. Samtidigt visar studien att antalet strategier för att utveckla dessa medarbetare är begränsade och riskerar att få motsatt effekt hos de identifierade medarbetarna som förväntar sig feedback och relevanta utmaningar på väg till sin första chefsroll.

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Abstract: Identification of, and responsiveness to, the communicative attempts of children with developmental delays’ is essential to developing intentional, symbolic communication. The current study was a replication of Keen, Sigafoos, and Woodyatt’s 2005 study titled Teacher Responses to the Communicative Attempts of Children With Autism, with modifications to the participants used in the study. The Inventory of Potential Communicative Acts (IPCA; Sigafoos et al, 2000) was used with three teachers of three children with deafblindness to determine if teachers were able to identify potential communicative acts (PCAs) of their students using the IPCA during an interview session. Additionally, analysis of teacher responsiveness to student PCAs took place during a 30-minute classroom observation session. All three teachers identified a wide range of student PCAs during the IPCA interview and showed high levels of responsiveness to those PCAs during the naturalistic, classroom observation. Low interobserver agreement, clinical implications, and directions for future research are discussed. / text

Stretch is known to result in an electrically less stable ventricular substrate, yet the reported effects of stretch on measured electrophysiological parameters have been inconsistent and even contradictory. The goal of this study was to evaluate the effects of acute mechanical stretch on cardiac electrical features thought to be key in generation of arrhythmia, namely restitution of action potential duration (APD), electrical memory, and onset of alternans. Microelectrodes were used to record intracellular potentials pre, during, and post-stretch from isolated right ventricular tissues from swine. In separate experiments, the effects of two levels of stretch were quantified. Pacing protocols employing explicit diastolic interval (DI) control and cycle length (CL) control were used to obtain measures of restitution of APD, memory, and alternans of APD. Stretching the tissue had varying effects on APD, restitution and memory. Stretch increased APD, restitution slopes and memory by as much as 24, 30 and 53 % in some cases, while it decreased these by up to 18, 37 and 81 % in others. During stretch, alternans of APD were observed in some cases, which occurred at slower rates of activation than before stretch. Histology of tissue samples showed localized changes in orientation of cells relative to the direction of stretch. Our results show that among individual trials, stretch altered the measured electrophysiological properties, sometimes markedly. However, when pooled together, these changes cancelled each other and the averages showed no statistically significant difference after stretch. A potential mechanism that explains this divergent and inconsistent response to stretch is the presence of local, micron level, variation in orientation of myocytes. Upon stretch, these divergent effects likely increase dispersion of repolarization diffusely and might thus be the reason behind the consistently observed increase in arrhythmic substrate after stretch.

Propensity score matching is commonly used to estimate causal effects of treatments. However, when using data with a hierarchical structure, we need to take the multilevel nature of the data into account. In this thesis the estimation of propensity scores with multilevel models is presented to extend propensity score matching for use with multilevel data. A Monte Carlo simulation study is performed to evaluate several different estimators. It is shown that propensity score estimators ignoring the multilevel structure of the data are biased, while fixed effects models produce unbiased results. An empirical study of the causal effect of truancy on mathematical ability for Swedish 9th graders is also performed, where it is shown that truancy has a negative effect on mathematical ability.

My overall claim in this paper is twofold: Firstly, the activity of developing arguments in favour of the existence of the Christian God is tenable and worthwhile and, secondly, the “infinite God objection” fails to undermine the kalam cosmological argument. Concerning the former, it is often claimed that the very activity of developing arguments in favour of God’s existence is futile. I argue, however, that such theistic arguments play an important role in the philosophy of religion, natural theology, and apologetics. Concerning the latter claim, I will attempt to show how the infinite God objection fails to undermine a notable theistic argument, namely, the kalam cosmological argument. As regards this objection, the proponents of the kalam cosmological argument face a dilemma – either an actual infinity cannot exist or God’s knowledge cannot be infinite. More specifically, this objection claims that God’s omniscience entails the existence of an actual infinity with God knowing an actual infinite number of future events and mathematical truths. My solution to this problem is that (1) God’s omniscience should be understood as maximal knowledge; (2) the existence of abstract objects (such as numbers and propositions) should be denied; and (3) God’s knowledge is non-propositional in nature. / MPhil, North-West University, Potchefstroom Campus, 2014

The standard practice of spectroscopic data reduction is generally to fit data to level energy expansions in terms of the vibrational and rotational quantum numbers. However, the utility of such expressions is limited because they extrapolate poorly and they need very large sets of parameters, many of which have no independent physical significance. One method of addressing these problems is to fit the spectroscopic data directly to analytical potential energy functions incorporating the natural physical behaviour of the molecule in question. Although there have been a number of successful applications of this approach, there are still certain problems associated with the types of potential forms being used. This thesis will explore some of these problems and determine how effective the potential forms being used are for a number of specific cases.

Diabetic cystopathy is a chronic and common complication of diabetes with a classical triad of symptoms; decreased bladder sensation, increased bladder capacity and impaired detrusor muscle contractility (Hunter and Moore, 2003). In animal models of diabetes such as streptozotocin-induced diabetes in the rat, abnormalities of bladder function have been reported (Longhurst and Belis, 1986). The prototypic TRPV channel, TRPV1, is activated by capsaicin, which has been shown to cause contraction of the rat bladder (Saitoh et al., 2007), and this is reduced in STZ-diabetic rat bladder (Pinna et al., 1994). Therefore we hypothesize that TRPV1 function will be reduced in the diabetic bladder. The aim of this study are the following: Firstly, to investigate the effect of the streptozotocin (STZ) model of diabetes on a range of TRP channel functions in the urinary bladder smooth muscle preparation using TRP channel agonists and antagonists and to study the neurotransmitters involved in the contractile or relaxant responses. Some studies were also performed on colon tissues. Secondly, to explore the involvement of cholesterol modudation in TRP channel signalling. Thirdly, to study the change in TRP channel response with time following the treatment with streptozotocin. The results showed that the contractile responses to the TRPV1 agonist capsaicin, TRPV4 agonist 4-α-PDD, and TRPA1 agonist allyl isothiocyanate were significantly reduced in diabetic bladder. The selective TRPV1 antagonist, SB-366791, inhibited the contractile responses to capsaicin confirming the involvement of TRPV1 channels. The effect of diabetes is unlikely to be at the level of contractile machinery since the contractile responses to muscarinic receptor agonist carbachol were not significantly reduced in diabetic tissues. It is reported for the first time that the combination of neurokinin 1 and 2 antagonists GR-205171 and SB-207164 inhibited the contractile responses to capsaicin suggesting that a neurokinin may be the neurotransmitter involved in the capsaicin responses. In addition, the reduction of the responses to capsaicin in STZ-induced diabetic tissues occurred not only in urinary bladder but also in colon. Cholesterol-PEG significantly lowered the maximal contractile responses to capsaicin of rat bladder strips. Methyl-β-cyclodextrin, α-cyclodextrin and β-cyclodextrin at the same concentrations enhanced the contractile responses to capsaicin in the control and diabetic rat bladder strips. These effects of cyclodextrin are specific to capsaicin activated contractions and not seen with TRPA1 activation, suggesting that the effects are not mediated downstream of channel activation. Since α-cyclodextrin does not sequester cholesterol, the enhanced responses to cyclodextrins may not be due to the cholesterol modulations. Instead, theses novel findings may possibly occur by changing the local membrane lipid environment of the TRPV1 channel. As early as 36 hours after induction of diabetes by STZ, the contractile responses to capsaicin were significantly reduced in comparison to those of the controls and this reduction persisted until the eight weeks time point. In contrast, responses to the TRPA1 agonist allyl isothiocyanate were not affected at early time points but were reduced one week after STZ treatment. This detailed time course analysis suggests that there are novel mechanisms of modulation of the TRPV1 channels in this STZ model. In conclusion, in the rat urinary bladder or colon preparations, diabetes mellitus using STZ animal model caused 1) the impairment of a number of TRP channel subfamily functions, TRPV1, TRPV4 and TRPA1 but not TRPM8. The combination of NK1 and NK2 antagonists significantly inhibited the responses to capsaicin. This may suggest the involvement of neurokinin in postsynaptic transmission in rat bladder following the activation of TRPV1 channel, 2) the impairment caused by STZ-induced diabetes occurred very early (within 36 hours after diabetes induction) in TRPV1 channel but not TRPA1 channel. There are specific early effects of STZ treatment on TRPV1 channel function at a time when other afferent nerve terminal channels (TRPA1) are functioning normally, suggesting that early onset of dysfunction in TRPV1 signalling may not merely be the consequence of nerve damage, 3) the mechanism of this impairment may not be the effect of neuropathy on neurotransmitter release or nerve damage. Improving the responsiveness of nerves of bladder in diabetic patients might be of therapeutic benefit. The present studies suggest that it is possible to enhance function using indirect modulators such as bradykinin which potentiated the TRPV1 channel function in diabetic rat bladders.