Waterfilling Theorems for Linear Time-Varying Channels and Related Nonstationary Sources

The capacity of the linear time-varying (LTV) channel, a continuous-time LTV filter with additive white Gaussian noise, is characterized by waterfilling in the time-frequency plane. Similarly, the rate distortion function for a related nonstationary source is characterized by reverse waterfilling in the time-frequency plane. Constraints on the average energy or on the squared-error distortion, respectively, are used. The source is formed by the white Gaussian noise response of the same LTV filter as before. The proofs of both waterfilling theorems rely on a Szego theorem for a class of operators associated with the filter. A self-contained proof of the Szego theorem is given. The waterfilling theorems compare well with the classical results of Gallager and Berger. In the case of a nonstationary source, it is observed that the part of the classical power spectral density is taken by the Wigner-Ville spectrum. The present approach is based on the spread Weyl symbol of the LTV filter, and is asymptotic in nature. For the spreading factor, a lower bound is suggested by means of an uncertainty inequality.Comment: 13 pages, 5 figures; channel model in Section III now restricted to LTV filters with real-valued kerne

The role of personality and organisational cultural differences in the success of salesperson-buyer dyads

A thesis submitted to the Faculty of Commerce Law and Management, University of Witwatersrand Business School, Johannesburg, in fulfilment of the Degree of Doctor of Philosophy Johannesburg, 2015Arguably the most important function a business focuses on is revenue generation, which is ultimately achieved through immediate sales and the inculcation of future customer spend. For many businesses, notably in the business-to-business realm, salespeople are still required to form relationships with key customer buyers and to achieve or facilitate sales through this “dyadic” interpersonal relationship. Understanding what makes relationships and interactions between customer buyers and salespeople successful – from a sales perspective – remains an important concern for organisations and marketing theorists. In such sales relationships, the “success” of the sale and the longer term sales relationship can depend on aspects of the interpersonal relationships such as the ability of the parties to communicate well, come to agreement, and potentially even bond socially. The ability of parties to form productive and conducive interpersonal relationships in turn depends on factors such as personality and culture. This thesis argues that there is no particular “best” personality or culture for the formation of successful sales relationships, but that match between the personality traits of salespeople and customers as well as between their respective organisation’s cultures may facilitate success in sales. As indicated above, the thesis studies two main dependent variables, namely sales success and word-of-mouth. These variables are derived from the theory of customer equity management (Rust, Lemon, & Narayandas, 2005). The thesis argues that prior to generating income through either a sale or through word-of-mouth the organisation will need to have a relationship with the customer. Relationship marketing (Morgan & Hunt, 1994) provides a framework for understanding what constitutes a relationship. The current study aligns itself with prior literature arguing that relationship quality comprises three components specifically; trust, satisfaction and commitment. Personality research has remained at the heart of industrial research and managerial practise. Voluminous literature has used the Big Five personality traits for understanding customer’s interactions. The five personality traits include Extraversion, Agreeableness, Conscientiousness, Neuroticism and Openness to Experience (Soto & John, 2012). The current study argues that it is not the personality traits themselves which are important, but rather the similarities or differences between the customer and the salesperson. Organisation culture has been shown to affect several different arenas within the management field, but has not been much examined within the context of dyadic relationships. The specific relationship that the study addresses is the customer-salesperson relationship. In this thesis I argue that both the customer and salesperson to some extent embody and reflect their respective organisational cultures, and in addition, sales systems can reflect organizational cultures, for instance where bureaucratic organizational culture creates sales systems with high levels of formality. In turn, match or mismatch in organizational cultures may affect sales or relationship outcomes in various ways. The well-known organisational culture index (Wallach, 1983) will be used to capture the cultures from both the salesperson and customer. The three elements of organisational culture measured by the index include bureaucratic cultural aspects, innovative cultural aspects, and supportive cultural aspects. To test these relationships, the thesis presents an empirical study based on a cross-sectional, quantitative, survey of the SME market in South Africa. One hundred salesperson-customer dyads participated in the study, and data from each member of the dyad was surveyed separately. Statistical techniques such as partial least squares structural equation modelling and polynomial regression were used in the analysis of the data. A response surface methodology allowed for graphical representation of the polynomial regression results. These results then acted as inputs for a Bayesian Networks analysis (Charniak, 1991), which are used to improve the understanding of causality. Results of the empirical survey indicate that trust, satisfaction and commitment affect the level of word-of-mouth while only trust and commitment have an effect on sales. The analysis indicates that matches or mismatches in the personality traits of extraversion, agreeableness, conscientiousness, neuroticism and openness do affect dependent variables of relationship quality, sales success and word-of-mouth, and do so in differing ways. This thesis provides several unique contributions to sales theory and literature. First, although the salesperson-customer dyad has been studied before, the differences in personality traits have not been included. This is particularly true within the South African context. Secondly, organisational culture literature has been reviewed and studied but has neglected the role that organisational culture plays in the sales environment, specifically when interacting with a customer. Third, several theories are used to explain why the constructs came together; however certain aspects of these theories are questioned. Lastly, several practical applications are provided that allow organisations to improve the hiring process and implement training objectives for their sales force. Key Words: Dyad, satisfaction, trust, commitment, customer lifetime value, relationship marketing, relationship quality, organisational culture, bureaucracy, innovation, supportive, response surface, polynomial regression, Bayesian network, customer equity management.MB201

Temperature-controlled change of charge transport mechanisms in nonionic water-in-oil microemulsions

 The temperature-controlled transition from the Stokes charge transport of aqueous nanodroplets to the intrinsic conduction of nanodroplet clusters in nonionic microemulsions was studied. Two different charge transport processes apparent from a minimum value of the conductance have been simulated based on straightforward physical models. Their predictions compare favourably with the observation

Instrumenting gait with an accelerometer: A system and algorithm examination

Gait is an important clinical assessment tool since changes in gait may reflect changes in general health. Measurement of gait is a complex process which has been restricted to the laboratory until relatively recently. The application of an inexpensive body worn sensor with appropriate gait algorithms (BWM) is an attractive alternative and offers the potential to assess gait in any setting. In this study we investigated the use of a low-cost BWM, compared to laboratory reference using a robust testing protocol in both younger and older adults. We observed that the BWM is a valid tool for estimating total step count and mean spatio-temporal gait characteristics however agreement for variability and asymmetry results was poor. We conducted a detailed investigation to explain the poor agreement between systems and determined it was due to inherent differences between the systems rather than inability of the sensor to measure the gait characteristics. The results highlight caution in the choice of reference system for validation studies. The BWM used in this study has the potential to gather longitudinal (real-world) spatio-temporal gait data that could be readily used in large lifestyle-based intervention studies, but further refinement of the algorithm(s) is required