published_or_final_version / abstract / Paediatrics and Adolescent Medicine / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Botany / Master / Master of Philosophy

published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / Biological Sciences / Master / Master of Philosophy

This work presents two mechanisms for modeling alliance formation between leader carriers in a freight network for more efficient utilization of their resources: partial collaboration and complete collaboration. The performance of these alliance formation mechanisms is compared against the no collaboration case for various network topologies and demand levels. In the partial collaboration case, each leader carrier first maximizes his individual profits and leases out the residual capacity to other carriers. In the complete collaboration case all leader carriers join together to maximize the profit of the alliance. The profits are then distributed among the alliance members using the Shapley value principle. Numerical tests reveal that the topology of the network and the demand levels play an important role in determining the profits from each collaboration mechanism. It was also inferred that each of these factors also play a major role in determining the best collaboration strategy. / text

Arabidopsis thaliana Acyl-CoA-Binding Protein 3, one of six acyl-CoA-binding proteins, is unique by the C-terminal location of its acyl-CoA-binding (ACB) domain. It promotes autophagy (ATG)-mediated leaf senescence and confers resistance to Pseudomonas syringae pv. tomato DC3000. To understand the regulation of ACBP3, a 1.7 kb 5’-flanking region of ACBP3 and its deletion derivatives were characterized using β-glucuronidase (GUS) reporter gene fusions. A 374 bp minimal fragment (-151/+223) could drive GUS expression while a 1698 bp fragment (-1475/+223) conferred maximal activity. Further, histochemical GUS staining analysis on transgenic Arabidopsis harboring the largest (1698 bp) ACBP3pro::GUS fusion displayed ubiquitous expression in floral organs and vascular bundles of leaves and stems, consistent with previous results that extracellularly localized ACBP3 functions in plant defense. A 160 bp region (-434/-274) induced GUS expression in extended darkness and conferred down-regulation in extended light. Electrophoretic mobility shift assay (EMSA) and DNase I footprinting assay showed that the DNA binding with one finger box (Dof-box, -341/-338) interacted specifically with leaf nuclear proteins from dark-treated Arabidopsis while GT-1 (-406/-401) binds both dark- and light-treated Arabidopsis, suggesting that Dof and GT-1 motifs are required to mediate circadian regulation of ACBP3. Moreover, GUS staining and fluorometric measurements revealed that a 109 bp region (-543/-434) was responsive to phytohormones and pathogens. Within this 109 bp region, an S-box of AT-rich sequence (-516/-512) was identified to bind nuclear proteins from pathogen-infected Arabidopsis leaves, providing the basis for pathogen-inducible regulation of ACBP3 expression. Hence, three cis-responsive elements (Dof, GT-1 and S-box) in the 5’-flanking region of ACBP3 were demonstrated to participate in the regulation of ACBP3. The regulation of ACBP3 by circadian control is not surprising given that defense genes are now known to be circadian-regulated; infection being anticipated at dawn coinciding with pathogen activity in spore dispersal during the light period. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

No description available.

No description available.

Spectrum sensing is the process of identifying the frequencies of a spectrum in which Signals Of Interest (SOI) are present. In case of continuous time signals present in a wideband spectrum, the information rate is seen to be much less than that suggested by its bandwidth and are therefore known as sparse signals. A review of the literature in [1] and [2] indicates that two of the many techniques used in wideband spectrum sensing of sparse signals are the Wideband Compressive Radio Receiver (WCRR) for multitoned signals and the mixed analog digital system for multiband signals. In both of these techniques even though the signals are sampled at sub-Nyquist rates using Compressive Sampling (CS), the recovery algorithms used by them are different from that of CS. In WCRR, a simple correlation function is used for the detection of carrier frequencies and in a mixed analog digital system, a simple digital algorithm is used for the identification of frequency support. Through a literature survey, we could identify that a VHSIC hardware descriptive ModelSim simulation model for wideband spectrum sensing of multitoned and multiband signals using sub Nyquist sampling does not exist. If a ModelSim simulation model can be developed using VHDL codes, it can be easily adapted for FPGA implementation leading to the development of a realistic hardware prototype for use in Cognitive Radio (CR) communication systems. The research work reported through this dissertation deals with the implementation of simulation models of WCRR and mixed analog digital system in ModelSim by making use of VHDL coding. Algorithms corresponding to different blocks contained in the conceptual design of these models have been formulated prior to the coding phase. After the coding phase, analyses of the models are performed using test parameter choices to ensure that they meet the design requirements. Different parametric choices are then assigned for the parametric study and a sufficient number of iterations of these simulations were carried out to verify and validate these models. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

The retention of sailors is paramount to the viability of the United States Navy. While numerous aspects, including pay, benefits, family issues, etc., factor into the decision of each sailor to leave the Navy, job satisfaction is one of the most important. This study examines the extent job satisfaction played in sailors' decisions to leave after their initial enlistment. The Navy's own survey instrument was utilized to gather the data from sailors who were separating from the U.S.S. John F. Kennedy (CV-67) at the end of their first enlistment contract. The survey questions were broken down into three general areas: Job Satisfaction, Pay and Benefits, and Quality of Life, to measure the level of satisfaction within each of these areas. The relationship between gender, martial status and ethnic group were key components in analyzing each of the key areas. The results of these findings are reviewed and discussed.