Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 81-91).

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / To correctly demodulate a signal sent through a multiple-input multiple-output (MIMO) channel, a receiver may use training to learn the channel parameters. The choice of training parameters can significantly impact system performance. Training too often yields low throughput while training infrequently produces poor channel estimates and increased transmission errors. Previous work on optimal training parameters has focused on the block fading Rayleigh model. This work examines a more general case; finding the training parameters that maximize throughput for a continuously varying channel. Training parameters that maximize a lower bound on channel capacity are determined via simulation, and general guidelines are presented for selecting optimal training parameters.

Sigma receptors have been implicated in the regulation of the cardiovascular system. Some of the cardiovascular effects of sigma receptors may be through the modulation of autonomic neurons. Studies on the expression and cellular function of sigma receptors in autonomic neurons were conducted in neonatal rat intracardiac (ICG) and superior cervical ganglia (SCG). Individual neurons from SCG and ICG were shown to express transcripts encoding the sigma-1 receptor. The effects of sigma receptors activation on high-voltage-activated Ca2+ channels was studied in isolated neurons of these ganglia. Bath application of sigma receptor agonists depressed peak calcium channel currents in a dose-dependent manner and the rank order potency of haloperidol> ibogaine > (+)-pentazocine > DTG is consistent with the effects being mediated by a sigma-2 receptor. Sigma receptor antagonist, metaphit, blocked DTG-mediated inhibition of Ca2+ current. Sigma ligands also altered the biophysical properties of these channels. Activation of sigma receptors reversibly blocked delayed outwardly rectifying potassium channels, large conductance Ca2+-sensitive K+ channels, and the M-current with maximal inhibition >80%. The rank order potency of different sigma ligands suggests that the effect is mediated by sigma-1 receptor. While bath application of sigma ligands depolarized ICG neurons, the number of action potentials (AP) fired by the cells in response to depolarizing current pulses was decreased. Experiments on the signal transduction cascade mediated the inhibition of K+ and Ca2+ channels by sigma ligands showed that the signal transduction pathway does not involve a diffusible cytosolic second messenger or a G-protein. Sigma ligands also modulate voltage-gated Na+ channels (VGSC) in ICG neurons. Bath application of sigma ligands inhibited VGSC current with maximal inhibition >90% and altered the biophysical properties of VGSC. The latency of AP generation during depolarizing current ramp was increased by sigma ligands and this effect is through the inhibition of VGSC. These data suggest that activation of sigma receptors on autonomic neurons modulates voltage-gated Ca2+, K+ and Na+ channels and as a result, the generation of AP is inhibited in these neurons. Sigma receptors are likely altering the cell-to-cell signaling in autonomic ganglia and thus regulating cardiac function by the peripheral nervous system.

Background Omni-channel retailing has developed as an extension of multi-channel retailing. The difference between the concepts is the level of integration, where an omni-channel requires seamless and complete channel integration compared to a multi-channel where the level of integration varies from non-existing to high. Today’s customers expect an integrated shopping experience where they can combine the different channels according to their preferences and omni-channel is a way for retailers to meet this need. Purpose The purpose of this thesis is to explore the concept of omni-channel retailing and its implementation in retail firms operating in the Swedish market. Method This study is based on an interpretive approach and takes the form of an exploratory multiple case study through the investigation of four retailers. Qualitative data was collected through semi-structured interviews and the findings were analyzed abductively. Conclusion The conclusion of this thesis is that the investigated retailers still have, more or less, a long way to go in their integrative efforts. The retailer that has come the furthest in their effort has only implemented nine out of fifteen omni-channel criteria. Three main incentives for implementing an omni-channel strategy were identified. These are to respond to customer demands, to optimize the individual sales channels and to gain a competitive advantage. Additionally, several challenges arise as the retailer moves towards an omni-channel. These include technological investments, change management, channel conflict, return management and consistency. Furthermore, five potential sources of these challenges were identified as technological requirements, organizational changes, sales accreditation policies, in-store returns and finally the franchise business model.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 22-27).

Thesis (M.S.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (January 12, 2010) Includes bibliographical references (p. 34-40)

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper presents the results of land-based SHF channel modeling experiments. Channel modeling data were collected at Edwards AFB, California at S-Band, X-Band and Ku-band. Frequency domain analysis techniques were used to evaluate candidate channel models. A graphical user interface (GUI) was developed to search for the optimum channel parameters. The model parameters corresponding to different frequencies were compared for multipath events captured at approximately the same locations. A general trend was observed where the magnitude of the first multipath reflection decreased as frequency increased and the delay remained relatively unchanged.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Initial results of wideband channel sounding experiments sponsored by the Advanced Range Telemetry (ARTM) program are presented. Data collected at Edwards EAFB during the Winter 1998-1999, are analyzed in the frequency domain to estimate the number, strength, and delays of the significant multipath reflections observed during the experiments. We observe that the channel is adequately modeled using two or three multipath reflections. The multipath fade events are correlated with recorded bit error rates and transmitter location to provide a comprehensive overview of the channel characteristics. Summaries from two test flights are included where it is seen that the 2- and 3-ray channel models provide excellent models for the data. In general, the 3-ray model captures the essential features of the multipath interference. In this model the first multipath is a strong specular reflection with relative amplitude greater than 0.5 and relative delay in the 30 to 70 ns range. The second multipath is a much weaker reflection with relative amplitude less than 0.5 and relative delay in the 175 to 325 ns range.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper uses ARTM channel sounding data collected at Edwards Air Force Base to investigate the dependency between the characteristics of frequency selective multipath fading and carrier frequency and ground based received antenna diameter. Channel model parameters are obtained from data sets measured at different frequencies and various ground based antenna diameters. The analysis shows that the multipath characteristics do not statistically change between the L-band and S-band carrier frequencies, but do change with antenna diameter. Furthermore, Flight 18 data shows that antenna diversity may be a useful technique to reduce data loss from multipath fading.