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M.Sc. (Nursing), Faculty of Health Sciences, University of the Witwatersrand, 2009

Spinal motoneurons (MNs) relay neural commands from the brain to the muscles to produce functional movement. However, MNs are more than passive conduits of neural commands; they also shape motor output through alterations in their intrinsic excitability. These alterations allow MNs to modify (e.g., amplify and/or prolong) motor output even in the absence of descending motor commands. How MNs respond to this modulation, under various conditions, is not fully understood. In the scope of this dissertation, we leverage high-density electromyography and motor unit decomposition algorithms to investigate how human MNs behave in (Aim 1) different muscles under similar task demands; (Aim 2) the same muscle under different task demands; and (Aim 3) in response to exogenous neuromodulation. First, in Aim 1 we demonstrate that MN excitability varies across motor pools and, thus, may be functionally tuned to the task and its muscle-specific demands. The results indicate that the MN discharge rates were significantly higher in the first dorsal interosseous, a small hand muscle used for fine motor control. Conversely, higher MN excitability was observed within the tibialis anterior, a lower leg muscle involved in balance and locomotion. Next, in Aim 2 we show that a muscle (i.e., the biceps brachii) with multiple biomechanical functions (e.g., supination and flexion) receives differential synaptic input to perform each action while the MN discharge characteristics remain the same. Finally, in Aim 3 we demonstrate that a single cup of coffee can alter fundamental motor control mechanisms by increasing discharge rate, inter-pulse variability, and excitability through caffeine-induced neuromodulation. Collectively, findings from this dissertation demonstrate the human motor system’s tremendous ability to adapt to internal and external states. / Public Health

No / The purpose of this paper is to present a critical viewpoint on the negative aspects of market, price and cost transparencies to consumers in terms of its costs. It adopts an inter-disciplinary approach from the marketing, economics and accounting literature. The paper explores market transparency in the ever-changing world and uses brand names like Starbucks and iPhone to illuminate instances where imperfect markets are supported by consumers. Recognizing the role that the Internet plays in promoting price transparency, it espouses how extant information can add costs and risks to the consumer’s value judgement. Finally, the paper advocates that arbitrary judgements existing in cost accounting make it difficult to compare unit cost. This could result in consumers paying extra money to benefit from cost transparency. This paper argues that three main issues may arise in providing unit cost to the consumers. First, transparency entails built-in costs, whether they are in taxes or product prices. Second, in accounting, unit cost information is currently not equitable between businesses. Finally, the paper argues that extra time and effort in making sense of unit cost information lead to questions about the viability of transparent costing. The arguments for transparency have been widely discussed, supported and promoted by many. While negative aspects are known to businesses, few consider the consumer’s perspective. By amalgamating evidence and arguments from different disciplines, this paper lends value, providing a critical perspective where transparent unit cost revelation can be more costly and less viable than what is assumed.

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The unit load is the form of most commercial and industrial products during storage and distribution. A simple form of a unit load, a palletized bulk bin is commonly used to transport fruit and vegetables from the point of harvest to processing facilities. These vibration sensitive products are often subjected to damaging vibrations during this period. Most damage occurs during the large accelerations associated with resonance, which occurs when the natural frequency of the unit load matches the input frequencies commonly encountered during transportation. A computer model, called RoPUL (resonance of palletized unit loads), of a palletized bulk bin loaded with fruit, was developed using finite element analysis techniques. Unit loads consisting of palletized bulk bins of apples and peaches were tested and RoPUL was found to accurately predict the resonant frequencies of these loads. Using RoPUL, the effects of product mass, container design, and pallet design on natural frequencies can be analyzed. As the input frequencies of most transportation modes is well documented, RoPUL can be used to help design a unit load to better protects vibration sensitive products during shipment. / Ph. D.

Hardy space scalar theory on the disk is now classical. Some extensions have been done, one of them is the approach done by Donald Sarason using Laurent series. We present the more complicated function theory, without the use of either power series or Laurent series, for finitely-connected planar domains. / Master of Science

Information, products and services can be requested and purchased via the Interactive Video Data Service (IVDS) system developed by The Center for Wireless Telecommunications, Virginia Tech. This system consists of three components - User control, Repeater unit and a Host program. The user requests a service using his/her television remote (User control). A transceiver (User control) located near the television set responds to user requests by extracting information hidden in the commercial's audio, and transmitting information to the repeater unit. The receiver unit decodes received messages and forwards them in capsules to the Host component. Thus the user requests are received by the host system. The repeater unit is a real-time operating system with its in-built hardware and software functions. Application specific software can be written using the existing software drivers and libraries (kernel) to decode and process messages. The Host program monitors and responds to received user messages. This thesis focuses on the repeater unit hardware setup and discusses the application software implementation developed to receive messages from the transceiver box and to retransmit the messages in a different format over the Internet. The software specifications included no incoming message loss, ability to statically hold 10000 user messages, time-stamp and location-stamp (using a GPS receiver) forwarded messages, scheduling messages for retransmission based on message priority, and retransmission using the point-to-point protocol (PPP) using a dial-up modem connection. In order to achieve better performance the existing software kernel was re-written in some sections. This thesis also discusses some of the system limitations from the repeater unit's perspective. / Master of Science