http://hdl.handle.net/2374.OX/4082 2013-05-19T14:29:02Z http://hdl.handle.net/2374.OX/107891 ICI Reduction Methods for MC-CDMA Systems Wu, Meng Multi-carrier code-division multiple-access (MC-CDMA) is an important multiple access candidate for 4G wireless communication system. While MC-CDMA provides high performance and high capacity in frequency selective fading channels, it is very sensitive to the signal distortion, especially the Inter Carrier Interference (ICI). We apply self-cancelation and a frequency transmission paradigm to MC-CDMA system to improve the sytem performance in an ICI rich environment. Furthermore, we combine the frequency transmission paradigm FD-MC-CDMA with ICI cancelation. Also, we apply all these three schemes into non-contiguous OFDM and non-contiguous MC-CDMA systems in simple Cognitive Radio communication environments and present the simulation results. Theoretical analysis and numerical results confirm the effectiveness of our proposed new schemes. 2009-04-10T08:06:47Z http://hdl.handle.net/2374.OX/107890 Differential effects of mutant TAp63γ on transactivation of p53 and/or p63 responsive genes and their effects on global gene expression Khokhar, Shama Khan p63, a member of the p53 gene family, known to play a role in development, has more recently also been implicated in cancer progression. Mice lacking p63 exhibit severe developmental defects such as limb truncations, abnormal skin, and absence of hair follicles, teeth, and mammary glands. Germline missense mutations of p63 have been shown to be responsible for several human developmental syndromes including SHFM, EEC and ADULT syndromes and are associated with anomalies in the development of organs of epithelial origin. The contrasting phenotypes associated with the different classes of p63 mutations might be in part due to the differential regulation of target genes. A previous report has demonstrated that heterozygous p63 mutations display high predisposition to tumor formation. Moreover, it has been shown that both p63 and p73, another member of the p53 family, are required for p53 mediated DNA damage induced apoptosis. Finally, differential splicing of p63 gene gives rise to p63 isoforms which can either act as tumor suppressors or oncogenes. The goal of this study is to determine the effects of naturally occurring TAp63γ mutants on regulation of p53/p63 and p63 specific target genes and their effects on global gene expression. Our results indicate that both TAp63γ(R227Q) and TAp63γ(R298Q) mutants mimic wildtype TAp63γ effects on its target genes. TAp63γ(K194E) and TAp63γ(R280C) significantly induced genes regulated by p63 and p53, but not those specific for p63. TAp63γ(R279H) andTAp63γ(R204W) were unable to induce any of the targets tested in this study. Co-transfection of p63 mutants along with wildtype p63 was performed to assess the effects of p63 mutants on ability of wildtype p63 to induce its target genes, while co-transfection of TAp63γ(R279H) and TAp63γ(R204W) led to a complete inhibition of the wildtype TAp63γ mediated induction of p63 specific target genes, they had no effect on p53/p63 target genes. We demonstrated that the ability of these mutants to regulate wildtype activity was independent of their ability to either interact with wildtype TAp63γ or affect its localization. In addition, we demonstrated that the effects of these mutants on cell growth and survival were consistent with their ability to regulate the downstream targets when compared to wildtype TAp63γ. Furthermore, our analysis of the GeneChip data using GeneSpring led to the identification of several common and unique genes regulated by specific p63 mutants when compared to cells transfected with wildtype p63. Additionally, the specific genes regulated by the p63 mutants observed in EEC, SHFM and ADULT syndrome might offer unique insights in understanding the involvement of p63 in development, ectodermal-mesenchymal interactions and differentiation. In summary, we show that p63 mutants exhibit a differential effect on p63 specific and p53/p63 specific target genes and on induction of apoptosis. This, in turn might have a significant impact on p63 mutation associated abnormalities of human developmental syndromes. Taken together, our data shows that p63 mutants differentially regulate gene expression and provide an insight into the molecular biology of p63. Further, these results will aid in better understanding of role of p63 mutants in development and cancer. 2009-04-10T08:06:35Z http://hdl.handle.net/2374.OX/107889 Adaptive Performance: An Examination of Convergent and Predictive Validity Stokes, Charlene K. The purpose of the present study was twofold: 1) to examine the convergent validity of the two foremost measurement methods, subjective and objective, used to assess adaptive performance; and 2) to examine the predictive validity of variables across measurement methods using a path model framework. Specifically, various dispositional traits are posited to influence adaptive performance through the mediating mechanisms of stress appraisals and self-efficacy. Beyond examining the potential causal paths associated with predictors, the study included a commensurate focus on adaptability as an outcome and addressed the measurement issues that surround adaptive performance. Participants (N = 275) in teams of five completed a task, the Computer-based Aerial Port Simulation (CAPS; Lyons, Stokes, Palumbo, Boyle, Seyba, & Ames, 2008), that included a disturbance during the second session, which required an adaptive response. In addition to assessing adaptive performance as objective task scores following the disturbance, peer and self ratings of adaptive performance were assessed. Marginal support was found for the convergent validity of adaptive performance measures; r = .52 for subjective and objective adaptive performance. Given the marginal support, as opposed to a composite measure for adaptive performance, all hypotheses were examined using both subjective and objective measures in separate analyses. Results supported the posited path model, and indicated that stress appraisals and self-efficacy mediate the relationship between dispositional traits and adaptive performance. This mediated relationship was supported across divergent measurement methods for adaptive performance. The results provide initial support for two previously unexplored areas in adaptive performance research: 1) stress appraisals as a predictor of adaptive performance, and 2) the mediating effects of self-efficacy and stress appraisals. The results offer promising applied implications for selection based on the supported dispositional traits, and training interventions based on the self-regulatory aspects of stress appraisals and self-efficacy. In terms of theoretical implications, the results of the present study direct attention to the construct validity of adaptive performance and suggest caution in interpreting previous research results in the area. Future research is needed that thoroughly examines the construct validity of adaptive performance and confirms if results are indeed generalizeable across measurement methods, and beyond. 2009-04-10T08:06:22Z http://hdl.handle.net/2374.OX/107888 A STUDY OF MULTI-ECHELON INVENTORY SYSTEMS WITH STOCHASTIC CAPACITY AND INTERMEDIATE PRODUCT DEMAND Niranjan, Suman The research in this dissertation involves the study of several multi-echelon inventory systems with stochastic capacity and intermediate product demand. Specifically we analyze the behavior of the system which consists of several intermediate product demands. The analysis is primarily three fold i) developed update (relational) equations for all the multi-echelon inventory systems under several inventory allocation policies, ii) develop two simulation optimization approaches 1) OptQuest framework, and 2) IPA (Infinitesimal Perturbation Analysis) framework, used to minimize the total cost of the inventory systems that satisfy the desired customer service level, iii) obtain numerical results for all the multi-echelon inventory systems under several scenarios and instances, and an extensive analysis and implications of the results. The research done in this dissertation differ from earlier works, since it considers a complex (combination of serial and assembly systems) multi-period multi-echelon inventory system with several sources of demand (specifically intermediate product demands). We obtain the best found base-stock levels for each node in the system that satisfies the required customer service level. A SIO (Simulation based Inventory Optimization) approach is used to obtain the best found base-stock level for the system under several inventory allocation policies. We consider a system which is closer to the actual world and can be used to solve contemporary issues like, 1) manufacturing firm that produces finished products as well as spare parts, 2) manufacturer-warehouse-distribution center-retail outlets etc. I am not aware of any work that studies the impact of inventory allocation polices for multi-period in a multi-echelon inventory system, and obtains best found base stock level for each node using an IPA framework. Moreover the best found base-stock level for each node is obtained under realistic conditions like stochastic demand, stochastic capacity, and lead time. 2009-04-10T08:06:08Z