In studying the diamagnetism of free electrons in a uniform magnetic field it was found that reducing the field to zero in the wavefunction did not yield the experimentally indicated free particle plane wave wavefunction. However, solving the Schroedinger Equation resulting from setting the field equal to zero in the original equation did yield a plane wave wavefunction. This paradox was not found to be peculiar to the case of a charged particle in a uniform magnetic field but was found to occur in a number of other systems. In order to gain an understanding of this unexpected behavior, the following systems were analyzed: the one-dimensional square well potential; a charged, spinless particle in a Coulomb field and in a uniform electric field; a one-dimensional harmonic oscillator; and a charged, spinless particle in a uniform magnetic field. From these studies the following were obtained: conditions for determining the result of reducing the potential in a wavefunction; the condition under which the potential of a system may be switched off while maintaining the energy of the system constant; the relationship between the result of physically switching off a potential, the result of reducing it in the wavefunction, and the solution of the Schroedinger Equation obtained by decreasing the potential to zero in the original wave equation; and a general property of any wavefunction with respect to reducing any parameter within this wavefunction. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The use of potential field based navigation schemes in robotics has been limited by inherent local minima issues. Local minima traps, small passages, unstable motion, and targets positioned near objects all pose major concerns when using potential fields for local vehicle control. This work proposes a new algorithm, "Re-Active Vector Equilibrium" (RAVE) that mitigates many of these issues. The vehicle representation model is expanded to use multiple points subject to potential calculation and the addition of two forces, a velocity dependent "risk force" (F_rsk) and a velocity and direction dependent "tangential force" (F_tan). The vehicle representation model is also expanded from a single reactive point to a series of points that define the vehicle body, providing better and simpler vehicle control. This has the effect of simplifying the required calculations at the cost of increasing the calculation count. The risk force, F_rsk, allows for dynamic adaptation to the immediate environment by acting in opposition to the net obstacle force, and is inversely proportional to the vehicle speed. The tangential force, F_tan, encourages better wall-following behaviour and provides a biasing mechanism to resolve obstacle aligned with target local minima issues.

This thesis is dedicated to the estimation of the potential of African continent for the automotive market entry. The work starts with the introduction of key internationalization, market assessment and market entry theories. Author then conducts a general analysis of automotive industry and evaluates the competitive forces that are shaping it nowadays. The research continues with the identification and evaluation of key drivers of Africa's future growth. Final practical part of the thesis is presented in the form of comparative study of four African countries: Egypt, Morocco, South Africa and Tunisia, that according to the author present the highest market potential for automotive in Africa. Country comparison and ranking is conducted by the application of PESTLE framework. In the end Egypt is identified as a preferred country and a list of recommendations on the automotive market entry strategy for Egypt is provided.

Denna studie undersöker vilket stöd lärare får från rektor och huvudman för att kunna undervisa särskilt begåvade elever i matematik. Den granskar även hur lärare bedriver undervisningen av dessa elever och vilket stöd lärare anser sig sakna från rektor och huvudman för att kunna bedriva undervisningen för särskilt begåvade elever inom matematik. Detta har studerats med en enkät som rektor fick besvara samt intervjuer med lärare. Frågorna baserades på en taxonomi designad för att utveckla och förbättra matematikundervisningen, samt generella undervisningsstrategier för de särskilt begåvade. Fem rektorer och fem lärare, utspridda över fem skolor i norra Sverige deltog i studien. Resultatet visade att lärare inte får särskilt mycket stöd för att undervisa särskilt begåvade elever i matematik i de flesta fall på de utvalda skolorna samt att lärare använde sig av två metoder för att undervisa dessa elever: Acceleration och berikning.

The main question that has been answered in this research project is: what happens to the singularities of the S-matrix when the interaction potential becomes complex? In other words, we looked at the resonance spectral points and traced their movements on the complex momentum plane, when the imaginary part of the potential is gradually increased from zero to a certain reasonable value. This question is important in many fields of research where optical potentials are used. An optical potential can effectively take into account the loss of the beam of particles into all the reaction channels that are formally ignored. Such a simplified approach is widely used in nuclear and atomic physics. In order to study the movement of the spectral points, we used a simple potential and the Jost function method that allowed us to easily locate the spectral points as complex zeros of the Jost function. / Dissertation (MSc)--University of Pretoria, 2016. / Physics / MSc / Unrestricted

MESC / Department of Mining and Environmental Geology

MESMEG / Department of Mining and Environmental Geology / See the attached abstract below

One of the most pressing needs society has in 2012 is addressing the plight of the 4 billion people, globally, who live at the bottom of the economic pyramid. Unless initiatives are undertaken to alleviate poverty and hardship in this portion of society, human potential will be wasted and the economic burden on the rest of society to support them will remain significant. In South Africa a significant portion of the population live at the bottom of the pyramid. One initiative to alleviate poverty and hardship is to enable bottom of the pyramid people who are excluded from formal financial services to access to them. By accessing formal financial services they would be able to safely save and borrow money. They would also be able to escape exploitative informal financial practices. Technology has the potential to expand access to financial services and reduce the cost of service provision. To date, however, it has not delivered on its promise of expanding financial inclusion at the bottom of the pyramid. Intermediaries, too, have been used to increase access to financial services but have also not successfully expanded financial inclusion at the bottom of the pyramid. Understanding which factors would allow these approaches to realize their potential has the ability to meaningfully contribute to addressing the plight of people at the bottom of the pyramid. This study brings together the potential of technology and the role of intermediaries to model expanding financial inclusion at the bottom of the pyramid in South Africa. The Technology Acceptance Model is used as a basis to propose an extended TAM model that explains adoption of technology enabled financial services through an intermediary at the bottom of the pyramid in South Africa. The proposed model is validated using structural equation modelling with data collected in a national survey in South Africa. The extended TAM model successfully explains more than 90% of the behavioural intention of financially excluded people at the bottom of the pyramid to adopt financial services through an intermediary. Using the findings, a strategic approach to expanding financial inclusion at the bottom of the pyramid is proposed. / Thesis (PhD(Eng))--University of Pretoria, 2012. / Industrial and Systems Engineering / unrestricted

Brandmurara stadens oidentifierade potential.

Bupivacaine is one of the amide type local anesthetics and is widely used for epidural anesthesia and blockade of nerves. Bupivacaine administration locally could result in neuron injury showing transient neurologic symptoms. Dexamethasone is a synthetic glucocorticoid and may exert cytoprotective properties against damage induced by some stimuli. In the present study, we evaluated the effects of dexamethasone on bupivacaine-induced toxicity in mouse neuroblastoma N2a cells. N2a cells were exposed to bupivacaine in the presence or absence of dexamethasone. After treatment, the cell viability, nuclear condensation, and lactate dehydrogenase levels were evaluated. Mitochondrial potential and Akt (threonine-serine protein kinase B) activation were also examined. In a separate experiment, we examined the effect of Akt inhibition by triciribine on cell viability following dexamethasone treatment. We also investigated whether dexamethasone could prevent lidocaine-induced neurotoxicity. Treatment of N2a cells with bupivacaine resulted in significant cell injury as evidenced by morphological changes, LDH leakage, and nuclear condensation. Pretreatment of the cells with dexamethasone significantly attenuated bupivacaine- and lidocaine-induced cell injury. Dexamethasone treatment prevented the decline of mitochondrial potential caused by bupivacaine and increased the levels of Akt phosphorylation. Importantly, pharmacological inhibition of Akt abolished the protective effect of dexamethasone against bupivacaine-induced cell injury. Our data suggest that pretreatment of neuroblastoma cells with dexamethasone exerts a protective effect on bupivacaine-induced neuronal cell injury. The mechanisms involve activating the Akt signaling pathway.