Macrophomina phaseolina is a necrotrophic soil-borne fungal pathogen that causes a disease commonly known as charcoal rot. This fungus has the potential to infect over 500 different plant species worldwide including many important crops such as soybean, corn and sorghum. The fungal infection dramatically decreases the yield of a crop due to loss in biomass, low seed quality and plant death. Currently, there is not an effective method for controlling the disease, because knowledge about the pathogen, the development of the disease and how it interacts with the plant host is limited. Therefore, a study was proposed to investigate the interactions between M. phaseolina and the model legume Medicago truncatula, following a molecular genetics approach where the host genes involved in the disease development will be identified. We conducted a genetic screen in a mutant population of M. truncatula to look for strains that have altered susceptibility to M. phaseolina. The initial screen of 259 Tnt1 lines identified seven lines that showed altered susceptibility to M. phaseolina. However, the second screen did not corroborate the results that were first obtained, and none of the seven Tnt1 lines showed altered susceptibility to the fungus. In addition, we screened 174 M. truncatula wild type ecotypes. As was expected, these ecotypes did not show altered susceptibility to M. phaseolina. Finally, we examined the effects of phytohormones jasmonic acid (JA) and ethylene (ET) in M. truncatula when infected with the M. phaseolina. Our results indicated that JA and ET slightly increased the resistance of the plants to this fungal pathogen. This makes us think that the modification of JA or ET signaling pathways may improve plant resistance to M. phaseolina. This study provides a basis for a further investigation of molecular interactions between M. phaseolina and its plant hosts. / Thesis (M.S.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Biological Sciences.

On February 12, 1951, Francis Nwia-Kofi “Kwame” Nkrumah walked out of James Fort Prison to become the first Prime Minister of the Gold Coast. After a landslide election, Nkrumah and his Convention People’s Party (CPP) sought to end British imperial rule in the Gold Coast and create a socialist Pan African union on the continent. In six years the highly educated and charismatic Nkrumah gained independence for the Gold Coast, which he promptly renamed Ghana, on March 6, 1957. Both Nkrumah and Ghana entered independence with a great deal of potential and possibility for success. However, Nkrumah’s desire for a United States of Africa became an obsession that prevented the leader from attending to Ghana’s crucial economic and development needs. As national opposition to Nkrumah’s leadership rose, he responded with oppressive laws and increased centralized authority over the people who came to view Nkrumah more as an egotistical dictator than a savior. The majority of the literature surrounding the biography and legacy of Kwame Nkrumah focuses on the leader’s shortcomings in an attempt to negate Nkrumah’s early accomplishments. This work explores Nkrumah’s legacy from a middle ground perspective by examining how Nkrumah successfully introduced Pan Africanism to Ghana and fought for the potential of African unity. The composition also demonstrates how Nkrumah’s intoxication with his own image and clear decline into dictatorship shattered his dreams of a United States of Africa. / Thesis (M.A.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of History.

The need for users to be able to setup wireless networks as, and when they require, has led to a boom in MANET. The constantly changing status of wireless links, mobility and resource scarcity, pose serious problems when a node in an ad hoc network is required to not only be able to communicate with other neighbors (multiple hops away), but also have demand QOS of intermediate nodes to its delay sensitive packets. As this technology has matured, resource starving of best effort traffic in the presence of priority traffic is not acceptable. Moreover, a true seamless, wireless network would be one in which intermediate nodes do not always need to support the same type of routing protocol in their TCP/IP stack to allow communication between the source and destination node. This research proposes to solve the QOS issues in a wireless ad hoc network by enriching the nodes in a network with trust databases, and a pool table to keep records of its previous interactions with all malicious and trustworthy nodes. A node can assign trust points to well behaving nodes and deduct points away from the database for a bad node. Thus, a node can always have a look at an intermediate node’s trust points and its previous performance to decide if this node can be trusted to properly forward its multimedia traffic by satisfying the QOS request. Also, QOS favors are returned promptly to provide incentives for nodes to become trustworthy. This author has proposed to solve the QOS issues in a MANET in a unique way, and has also tried to capture the dynamism of wireless channels by using a Best Effort (BE) timer to gain the best utilization of a costly channel and to provide fairness. A Universal Packet Format is used in this research to ensure communication between two nodes which may be separated by nodes that do not support the same routing protocol in their TCP/IP stack. Hence, an attempt toward a comprehensive solution for achieving the goals of a seamless QOS aware ad hoc network is made in this research work. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science.

Privacy plays an indispensable role over internet transactions. There are existing methods in place which enhance the level of privacy over WorldWide Web (WWW). Anonymity intends to hide the identity of the user during web transactions. Sender anonymity attempts to hide the identity of the sender of a message. Various anonymous systems exist today which provide different levels of anonymity to their users. Comparing various anonymous systems on the Web by quantifying the degree of anonymity provided by them is a daunting and challenging task. This thesis illustrates with examples that existing measures in literature are not sufficient to fully characterize the anonymity provided by a system and introduces a new isolation measure. The new isolation measure is proposed based on the existence of outliers in a distribution which is critical towards quantifying the anonymity provided by the system. The need for three distinct aspects of anonymity is justified, important from the perspectives of a user, a system designer and an attacker, leading to a three-dimensional approach towards measuring sender anonymity. A 3-tuple metric is proposed, and various properties of metric are also discussed. The interpretation of proposed metric depends on the desired characteristics of the system. Two anonymous systems can be compared in terms of the degree of anonymity provided, using the proposed 3-tuple metric and appropriate weights reflecting the attributes desired in the system. The proposed metric is applied to quantify the degree of anonymity provided by various existing anonymous systems. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science.

TheWireless Sensor Networks (WSNs) employs thousands of small sensors that communicate between themselves in a distributed manner using Medium Access Control (MAC) protocols. The energy required for wireless sensors is obtained from non-rechargeable energy sources. Due to their small size, wireless sensors are highly constrained in terms of battery energy. Hence, energy efficiency is considered a key factor in the design of a WSN. MAC protocols play an important role in the successful operation of WSNs. Energy efficiency can be achieved by introducing some significant changes that effect the energy consumption at the MAC layer. Existing protocols achieve energy savings, trading off either latency or throughput. The Sensor Medium Access Control (SMAC) is one such protocol that identifies a few sources of energy wastage and proposes an adaptive sleep-and-listen scheme to minimize energy wastage. This thesis studies the S-MAC protocol and proposes a new one Cluster-Based Energy-Efficient Medium Access Control (CBMAC), which attempts to increase energy savings by introducing changes to the existing S-MAC protocol. CBMAC introduces a clustering mechanism, in which the nodes form clusters and elect a cluster head. The cluster head takes care of data transfer and synchronization issues, while the cluster nodes are allowed to spend maximum time in the sleep state. The role of the cluster head is shared among several nodes over time in order to achieve uniform energy utilization in the network. The energy savings achieved with the CBMAC protocol are primarily due to the increased sleep-time fraction for cluster nodes. The clustering mechanism also reduces control overhead, which is prevalent in the S-MAC protocol due to the periodic control packet exchanges. CBMAC was studied under various topologies, and the results show significant energy savings over the S-MAC protocol, particularly in low-data-traffic scenarios. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science.

A production system is a system where the raw materials are converted to finished products. A production system is classified in to two types based on the products processed namely single product production system and multi-product production system. The products in any production system would be in either value added or non-value added state. This research focuses on reducing the non-value added state in multi-product or complex production system by analyzing the bottlenecks. A bottleneck machine causes blocking or starving of parts in the system thereby increasing the non-value added time and reducing the system performance. Bottlenecks can be mitigated by control strategies such as buffer allocation and capacity addition. In order to mitigate the bottlenecks, the location, source and type of bottleneck in any system has to be identified. This research uses multiple metrics in order to identify the bottleneck and its type. Based on the metric values, the control strategies are implemented by the developed heuristics such as buffer allocation based on qualitative characteristics, capacity addition based on highest utilization and economic analysis based on sensitivity analysis. Multiple options are given with respect to their performance improvement for the management or the customer to select in order to give flexibility in terms of investment, demand and layout space. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering.

Gage Repeatability & Reproducibility (GRR) Studies have become critical in process improvement projects in the manufacturing sectors. There are various methods to conduct GRR study. However, the most widely used is the Automotive Industry Action Group (AIAG) method, which was standardized after the recognition of the importance of measurement systems. In this study, AIAG method and Wheeler’s method are compared, with specific interest in the proportions of the estimates of variation. An experimental study was designed, with factors being the operators and parts. The spectrum analyzer – Quattro, was tested for its adequacy of measurement and to understand the variability in the measurement system. In this research, vibration-impact testing was performed on Stereolithography (SL) parts and the measured feature was the natural frequency. The data was analyzed following the AIAG method and that proposed by Wheeler. From the results obtained, the Repeatability and Reproducibility were over estimated by AIAG method in comparison to Wheeler’s. The Wheeler’s method gave a better understanding of the sources of variation. Due to which, the measurement system capability could be judged without bias. Also, Wheeler’s method helps in making right decisions about the measurement system. Therefore, Wheeler’s method is strongly recommended over the AIAG. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering.

This thesis presents a quantitative analysis of medium access control (MAC) delays in saturated ad hoc networks and their impact on node packet service-time. First, the medium access delay at an ad hoc node was modeled in terms of the time spent in collisions and successful transmission. Secondly, the variations in route discovery time with respect to the variations in medium access delays were analyzed. Finally, the overall effect of MAC delay on node packet service time was discussed. In stationary networks, the routing delays are negligible after the initial route discoveries; hence MAC delays determine the packet service-time. In mobile networks, the upper layer delays associated with node transmission such as route discovery time together with MAC delay effect the node packet service-time. The simulations were carried out for stationary network scenarios, and the results support the presented model. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science.

A model for predicting the hangar airflow on the aircraft exterior and interior is presented. The objective was to analyze the amount of air flowing over and inside the aircraft at the time of painting, in order to dry the paint effectively and to avoid possible hazardous effects on the painting crew. A 2D model was simulated for the exterior airflow. Five different sections of the aircraft were considered in simulating the exterior airflow. The angle at which air flows from the diffuser was varied as 0°, 22.5°, 45°. Optimize the air distribution in the hangar area for effective drying and minimal contamination by paint particles. It was evident that the distribution of air along the aircraft exterior was more effective at angles of 0° and 22.5°. At 45° the airflow was directed away from the aircraft resulting in the circulation of air inside the hangar area. It was concluded that the diffuser can be remodeled in such a way that center of the diffuser is at 0° and 22.5° towards the corners in order to distribute air evenly into the hangar area for effective drying of the paint. The drying of paint on fuselage depends on the airflow from the outside through strategic openings. A 3D model of the aircraft was developed with open airflow passages. The analysis was conducted for 7 different scenarios where in the pilot and rear doors were closed randomly. The analysis identified the best scenario for uniform distribution within the aircraft. Two major constraints were to maintain a minimum velocity of 100fpm throughout the inside of the aircraft and 12000 cfm of air at each exit (dog houses). The study showed that an external airflow distributed at 0° and 22.5° provided the best scenario for the airflow inside with all doors open. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.

This study is a further investigation of epistemological beliefs, specifically ways of knowing, and whether people will adapt these beliefs dependent upon social context (i.e. in-group or out-group). In addition, this research examined the role of gender and one’s use of connected knowing (CK) or separate knowing (SK). One hundred twenty-three college students were surveyed to determine if use of CK or SK shifted when thinking of in-group or out-group associations. Results did not confirm a shift in the use of CK or SK dependent upon social context. The results confirmed that men had higher SK scores than women; however, no gender differences were confirmed in CK scores. / Thesis (M.Ed.)--Wichita State University, College of Education, Dept. of Educational and School Psychology.