Wireless networks have received considerable attention recently due to the high user demand for wireless services and the emergence of new applications. This thesis focuses on the problem of information dissemination in a class of wireless networks known as the multi-way relay channel. Physical layer network coding is considered to increase the throughput in these networks. First, an algorithm is proposed that increases the full data exchange throughput by 33% compared to traditional routing. This gain arises from providing common knowledge to users and exploiting this knowledge to restrain some users from transmitting. Second, for complex field network coding, a transmission scheme is designed that ensures the receipt of a QAM constellation at the relay. This requires precoding the user symbols to make all possible combinations distinguishable at the relay. Using this approach, the throughput of data exchange is 1/2 symbol per user per channel use. The error performance of both schemes is derived analytically for AWGN channels. / Graduate

This study is designed to examine distribution channel selection and evaluation policies of small, medium, and large United States manufacturers. Significance of various factors considered in the selection and evaluation procedures is ascertained.

The ubiquitously expressed pannexin 1 (Panx1) ion- and metabolite-permeable channel is capable of mediating ATP release in a multitude of cells and tissues. This leads to activation of nearby purinergic (P2X/P2Y) receptors in an autocrine/paracrine manner. Stimulation of P2 receptors also triggers Panx1 activation, leading to the formation of a positive feedback loop. Although the focus of Panx1 research has primarily been on its expression at the cell surface, there is robust and stable expression of Panx1 on intracellular membranes. Whether intracellular Panx1 was the consequence of direct diversion from the secretory pathway or internalization from the cell surface was unknown at the onset of my studies. I postulated that Panx1 internalization to these membranes would require a ubiquitous constitutively or episodically released stimulus to allow stable intracellular expression. ATP, a potent signalling molecule released via exocytosis (constitutive or regulated) or large pore channels, fit this criterion. My hypothesis was that ATP triggered Panx1 internalization to intracellular compartments. Upon elevation of extracellular ATP, I observed P2X7R-mediated non-canonical internalization of Panx1 via macropinocytosis. This involved upstream cholesterol-dependent P2X7R-Panx1 clustering via a physical interaction between P2X7R-Panx1 ectodomains and possible contribution of phospholipid (PA, PIP, PIP2) interactions localized to the Panx1 C-terminus. Physical P2X7R-Panx1 interaction may promote Panx1 association with actively endocytosing regions of the membrane. Internalized Panx1 was targeted to slow recycling Rab14/Rab11-positive endosomes in an Arf6-dependent mechanism. The data I presented here provides an additional negative feedback layer to P2X7R-Panx1 crosstalk in the many cell types where they are co-expressed. Further, this is the first evidence demonstrating that Panx1 surface expression is labile to changes in the cellular environment, which contributes to the understanding of the regulation of Panx1 and associated behaviours through trafficking mechanisms. / Graduate / 2018-06-20

In South Africa the need to protect and manage the national water resource has led to the development of the Reserve as a basic right under the National Water Act (1998). The Ecological Reserve relates to the quality and quantity of water necessary to protect the sustainable functioning of aquatic ecosystems. The geomorphological contribution to setting the Reserve has focussed on three groups of information requirements: the spatial and temporal availability of habitat, the maintenance of substratum characteristics, and the maintenance of channel form. This thesis focusses on the second and third information requirements. The thesis has attempted to achieve this by adding value to the theoretical and applied understanding of the magnitude and frequency of channel forming discharge for selected southern African rivers. Many of the eastern sea-board rivers are strongly influenced by bed rock in the channel perimeter, and by a highly variable hydrological regime. This has resulted in characteristic channel forms, with an active channel incised into a larger macro-channel being a common feature of eastern seaboard rivers. Within the active channel inset channel benches commonly occur. This alluvial architecture is used to provide clues as to the types of flows necessary to meet the Reserve. Three river basins are considered : the Mkomazi, Mhlathuze and Olifants. The Mkomazi is a relatively un-impacted perennial eastern-sea board river and forms the research component of the study. The Mhlathuze and Olifants rivers are highly regulated systems and form the application component of the study. Utilising synthesised daily hydrological data, bed material data, cross-sectional surveys, hydraulic data and relevant bed material transport equations, channel form was related to dominant discharge and effective discharge in an attempt to identify the magnitude and frequency offlows that can be considered to be ' effective'. Results from the Mkomazi River indicate that no single effective discharge exists, but rather that there is a range of effective discharges in the 5-0.1% range on the 1-day daily flow duration curves that are responsible for the bulk (>80%) of the bed material transport. Only large floods (termed 'reset'discharges) with average return periods of around 20 years generate sufficient stream power and shear stress to mobilise the entire bed. The macro-channel is thus maintained by the large ' reset' flood events, and the active channel is maintained both by the range of effective discharges and the ' reset 'discharges. These are the geomorphologically 'effective' flows. Results from the Mhlathuze River have indicated that the Goedertrouw Dam has had a considerable impact on the downstream channel morphology and bed material transport capacity and consequently the effective and dominant discharges. It has been suggested that the Mhlathuze River is now adjusting its channel geometry in sympathy with the regulated flow environment. Under present-day conditions it has been demonstrated that the total bed material load has been reduced by up to three times, but there has also been a clear change in the way in which the load has been distributed around the duration curve. Under present-day conditions, over 90% of the total bed material load is transported by the top 5% of the flows, whereas under virgin flow conditions 90% of the total bed material load was transported by the top 20% of the flows. For the Olifants River there appears to be no relationship between the estimated bankfull discharge and any hydrological statistic. The effective discharge flow class is in the 5-0.01% range on the 1-day daily flow duration curve. It has also been pointed out that even the highest flows simulated for the Olifants River do not generate sufficient energy to mobilise the entire bed. It is useful to consider the Olifants River as being adapted to a highly variable flow regime. It is erroneous to think of one ' effective' discharge, but rather a range of effective discharges are of significance. It has been argued that strong bed rock control and a highly variable flow regime in many southern African rivers accounts for the channel architecture, and that there is a need to develop an ' indigenous knowledge' in the management of southern African fluvial systems

The increase in number of banks entering the South African banking sector has caused the big four banks to lose their market share to the new entrants. As a result, the new entrants in this sector have also had negative effects on the existing banks’ sales growth and net profits. Business banking, in particular, has been one of the departments which has become competitive as it is considered to generate the most revenue from all the different bank departments. Business clients have been targeted as their fees are high compared to normal individual clients and also, their investment sizes are big compared to individuals, hence the increased interest in this section. This then prompts the question, what are the factors influencing sales growth in business banking? This question then brings one to the following sub-problems: Is the pricing offered by the various banks to their business bank customers competitive enough to retain them?; How competent and knowledgeable is the staff dealing with business bank customers in ensuring good relationships with business banking clients?; is the technology used by the banks advanced enough to address the banking requirements of business banking customers? Are business banking customers loyal to their respective banks to ensure repetitive sales? In dealing with the above, the author undertook a research study to determine whether factors such as competitive pricing, competent staff, advanced technology and customer loyalty influence sales growth in business banking in Buffalo City Municipality “BCM”. The sample of 90 business banking customers who were given questionnaires to test the above were from a population of business banking customers in BCM. The author underwent a theoretical and an empirical investigation using the survey method through questionnaires. These questionnaires were distributed to the various financing institutions dealing with business banking clients. The findings of the empirical study suggest that through the use of the hypothesis test, it was concluded that of the four factors, advanced technology and customer loyalty influence sales growth in business banking in BCM. While pricing and competent staff do not influence sales revenue growth.

Hyperkalemic periodic paralysis (HyperKPP) is an autosomal dominant human skeletal muscle channelopathy that causes periods of myotonic discharge and periodic paralysis due to defective Nav1.4 sodium channels. Patients are asymptomatic at birth, attacks become short and frequent during childhood, and more severe during adolescence. Since the Nav1.4 content in the cell membrane is relatively constant during childhood, it was hypothesized that some symptoms start with the defective Nav1.4 channels, while other symptoms start after some changes occur in gene expression affecting other membrane channel content and/or activity. To test the hypothesis, the contractile characteristics of EDL and soleus muscles from HyperKPP mice from the age of 0.5 to 12 months were tested in vitro. For both EDL and soleus, contractile defects, including low force generation, instability and large unstimulated force were observed by two weeks of age. With aging, the defects did not worsen, but muscles actually showed some improvement. Considering that Nav1.4 protein content reaches maximum at three weeks of age, the data suggests that HyperKPP symptoms are solely due to the defective Nav1.4 channels.

This study investigates channel bed scour and fill as a result of individual flood events in a gravel-bed channel. Given the complexity of interactions between hydraulic force, the texture and arrangement of bed material, and input of sediment to a particular point of the channel bed, study objectives were pursued with the view that bed material movement is a stochastic phenomenon. A two-year field program was conducted in Carnation Creek, a small gravel-bed stream draining 11 km2 on the west coast of Vancouver Island, British Columbia. In the 900 m study reach, an array of measurement techniques, including scour indicators, magnetically-tagged stones, and conventional survey, yielded information about the fluctuations of the channel bed elevation and movement of scoured material for individual flooding periods. Frequency distributions of scour and fill depths associated with individual flooding periods are adequately modeled by negative exponential functions over the range of flood peak magnitudes observed in Carnation Creek. Analysis of scour depths measured in streams on the Queen Charlotte Islands demonstrates the applicability of the exponential model to flooding periods and flood seasons. Further, exploratory analysis suggests that a regional scour depth model is possible. Power functions relating mean depths of scour and fill to flood peak discharge show that depth increases with an increase in peak magnitude. Observed maximum scour depths in flooding periods are linked, in general, to streambed conditions influenced by antecedent flow conditions. These patterns in scour and fill exist within an overall pattern of increasing variability in depths of scour and fill as peak discharge increases. Evaluation of a heuristic model for mean travel distance as a function of particle size proposed by Church and Hassan (1992) provides convincing evidence for its general merit. Mean travel distance decreases inversely with particle size as size increases beyond the median diameter of subsurface sediment. This trend is consistent in both individual flooding periods as well as flood seasons. The majority of material finer than the median diameter of surface sediment is supplied from subsurface material, which influences the travel distances of these finer fractions because of burial. Computation of volumetric transport rates of bed material, based on the active scour depth and width of the channel bed, the virtual velocity of particle movement, and sediment porosity, suggests the potential for building scale correlations with streamflow, which have usually been defined by bedload sampling during floods. Error analysis indicates that determination of active width contributes most significantly to the imprecision of transport rate estimates. Results underscore the stochastic nature of sediment transport in gravel-bed channels. / Arts, Faculty of / Geography, Department of / Graduate

The ‘bottom of the pyramid’ (BoP) refers to the world’s poorest socio-economic group. In South Africa, consumers in this segment are an increasingly attractive target market for multi-national corporations (MNCs), partly because they constitute more than one-third of the population. However, a key managerial challenge remains in distributing goods and services to these consumers. This research sought to identify the alternative channels of distribution that firms develop to reach the BoP. Using a qualitative research methodology, eighteen depth interviews were conducted tracing the channels of seven firms from firm to end-user. The results suggest that many MNCs are indeed developing BoP channels, with varying degrees of success. Further, success seems to be driven by the level of managerial commitment. In addition, the BoP in South Africa is best understood as two distinct sub-segments, the urban BoP is characterised by more competition and crime, while the rural BoP has lower population density which heightens logistical challenges. Community involvement, where locals serve as distributors or salespeople, is a central feature of successful strategies to reach the BoP. Finally, the findings suggest that alternative distribution channels present benefits for MNCs in terms of cost to serve, local knowledge and increased penetration. / Dissertation (MBA)--University of Pretoria, 2014. / zkgibs2015 / Gordon Institute of Business Science (GIBS) / Unrestricted

The introduction of new schemes that are based on the communication among nodes has motivated the use of composite fading models due to the fact that the nodes experience different multipath fading and shadowing statistics, which subsequently determines the required statistics for the performance analysis of different transceivers. The end-to-end signal-to-noise-ratio (SNR) statistics plays an essential role in the determination of the performance of cascaded digital communication systems. In this thesis, a closed-form expression for the probability density function (PDF) of the end-end SNR for independent but not necessarily identically distributed (i.n.i.d.) cascaded generalized-K (GK) composite fading channels is derived. The developed PDF expression in terms of the Meijer-G function allows the derivation of subsequent performance metrics, applicable to different modulation schemes, including outage probability, bit error rate for coherent as well as non-coherent systems, and average channel capacity that provides insights into the performance of a digital communication system operating in N cascaded GK composite fading environment. Another line of research that was motivated by the introduction of composite fading channels is the error performance. Error performance is one of the main performance measures and derivation of its closed-form expression has proved to be quite involved for certain systems. Hence, in this thesis, a unified closed-form expression, applicable to different binary modulation schemes, for the bit error rate of dual-branch selection diversity based systems undergoing i.n.i.d. GK fading is derived in terms of the extended generalized bivariate Meijer G-function.

A dissertation submitted in fulfillment of the requirements for the Degree of D. Litt in Communication Science at the University of Zululand, 2007. / The main task of Chief Superintendents of Education Management (CSEMs) and Superintendents of Education Management (SEMs) and principals is to achieve the goals of the Education Department. They direct the activities and performance of their supervisees. In pursuing this, a leadership relationship and interaction between the supervisors and his supervisees is necessary. These leaders however, perform two significant roles; that of leading and that of being led. The leadership of these leaders is influenced /affected by the relationship the leader has with his supervisor to perform optimally or rninimally. For these managers in Education to lead effectively, they need to be well and timeously informed about matters. The SEMs need to be kept abreast of education related issues because of the type of work they do. It ranges from communicating departmental goals and objectives, consultation with stakeholders, chairing workshops and meetings of principals, parents and School Governing Bodies. They also serve on recruitment panels, among many other functions. Various forms of communication styles systems and communication strategies are viewed as significantly crucial in the work of the SEM. The SEM however relies on senior management for information. Latest and revised policies come to the SEM via the line function. Reaching the set destination depends on the leadership styles of the supervisors, whether they are traditional or transformational leaders. The SEM likewise, disseminates the information to the principals of schools. They in turn do the same to their supervisees at school and to School Governing Bodies, where necessary. The leadership styles of the SEMs and principals also affect information dissemination either positively or negatively. The results of the study points out that communication channels are not always adhered to in the Department of Education. Information does not reach the SEMs on time. E-communication is still minimally used in the Department of Education.