In order to identify complex systems capable of modeling artificial life, we study the notion of complexity within a class of dynamical systems called cellu- lar automata. We present a novel classification of cellular automata dynamics, which helps us identify interesting behavior in large automaton spaces. We give a detailed comparison of our results to previous methods of dynamics classification. In the second part of the thesis, we study the backward dynamics of cellular au- tomata. We present a novel representation of one-dimensional cellular automata, which can be used to charcterize all their garden of eden configurations. We demonstrate the usefulness of this method on examples. 1

A major goal in restoration is to reestablish native plant communities. There are several ways to reestablish species, but for large areas the most logistically feasible approach is to sow seed of desirable species. However, most wetland seeds are buoyant and are extremely difficult to establish in designated areas before floating away. In upland areas, tackifiers have been used to stabilize hill slopes from erosion and to keep seeds in place. The tackifier works as an adhesive that binds the seeds to the soil. However, the use of a tackifier has not been widely employed in wetland restorations, and prior to its broad implementation into wetland restoration practice, it is important to determine if tackifiers will hold up in wetland conditions. In greenhouse studies, we tested the effectiveness of different tackifier types and concentrations on Bolboschoenus maritimus seedling emergence, the influence of soil moisture and flooding on the duration of tackifier effectiveness, the effect of a mulch addition on tackifier effectiveness (Bolboschoenus maritimus, Schoenoplectus acutus and S. americanus), the effectiveness of pre-germination in enhancing Bolboschoenus maritimus seedling emergence using a tackifier, and the effectiveness of tackifier over time. We concluded that the use of a tackifier was effective at keeping seeds from washing away for at least 15 days, a mulch addition did not enhance tackifier effectiveness, and pre-germination did not benefit B. maritimus seedling emergence. The results from this study provide strong evidence that the use of a tackifier could be an effective solution to establish bulrush species in designated areas in wetland restorations.

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Recently, cotton production throughout the southern U.S. have declined substantially. Additionally, the pest status of bollworm, Helicoverpa zea (Boddie), has increased in soybean. As a result, there is growing interest to have commercial access to transgenic soybean varieties that express the Bt toxins to help manage against lepidopteran pests. However, soybeans are assumed to be a key host in the natural refuge concept used for Bt cotton. Research was conducted to determine if the introduction of Bt soybeans into the U.S. would present an unacceptable risk to the sustainability of other crops. This project examines the contribution of soybean to the susceptible heliothine populations in the natural refuge system, the potential of delayed in-season emergence of H. zea from field corn, effects of soil moisture on emergence and pupal duration, fitness of adult H. zea from Bt and non-Bt corn, and provide more accurate parameters for future resistance development models.

Tobacco seed performance is traditionally measured as percentage germination at 14 d under controlled laboratory conditions. However, under greenhouse conditions, seed lots with equal 14-d germination may exhibit substantial differences in uniformity of early seedling growth and spiral root incidence that impact the number of usable transplants. A seedling performance index (SPI) was developed to quantitatively describe greenhouse tobacco seedling performance. The 14-d emergence, relative leaf area uniformity, and seedling leaf area determined by computer image analysis were used to calculate the index. Greenhouse tobacco seed trials demonstrated that seed with the Rickard pellet had higher emergence, but the higher spiral root incidence associated with the Rickard pellet lowered the SPI compared to the Cross Creek pellet. Primed seed lots of flue-cured cultivars (NC 72 and NC 71) had a significantly higher SPI than the nonprimed seed lots at one location but not at a second location. Seed lots sown in Premier Pro-Mix TA commercial medium had a higher spiral root incidence, which resulted in a lower SPI compared to Carolina Choice, Carolina Gold, and Sunshine LP5 commercial media. The index quantitatively determined differences in seedling performance under greenhouse conditions not reflected by standard germination tests. Significant differences in the SPI were observed among seed lots with certified 90% germination. The SPI is a simple method to describe seedling performance because the data used to calculate the SPI is obtained from one seed tray image. In contrast, frequent counting and seedling evaluations are involved with standard germination and vigor tests. / Master of Science

Horseweed has been documented in 70 countries and 40 different crops around the world and is listed as being a problem weed in no-till production systems. Horseweed has developed resistance to many herbicide modes of action including glycine. Field experiments were conducted from 2004 to 2006 in the Mississippi Delta to evaluate the field emergence of horseweed and most effective treatment programs for its control. Field emergence of horseweed was observed occurring primarily in the fall of the year, September through early November, when temperatures were between 15.6 to 23.4 C with later flushes occurring from late January through early April with temperatures ranging from 5.2 to 16 C. Tillage in September followed by herbicide in March gave 100% control of horseweed across all locations. Glyphosate + 2,4-D and glyphosate + dicamba were the best glyphosate-based treatments and provided 90% or better horseweed control 4 WAT both years. Glufosinate-based burndowns provided 81 to 97% horseweed control and soybean yields were generally similar with all glufosinate-based programs.

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Team cohesion represents arguably the most studied team construct as it has been consistently shown to be associated with improved performance. However, although cohesion is now understood to be an emergent state—as it develops over a team's life cycle—research has yet to uncover the dynamic nature of cohesion. The current study was designed to particularly test the impact of team personality composition both on the initial status of cohesion, and on changes in cohesion over time. 80 newly formed teams performed a highly interdependent team task, and team cohesion was measured over six time points. Personality was measured prior to the task and calculated at the team level, as both an average and a variability score. After performing longitudinal hierarchical linear modeling, results indicated that team personality impacts cohesion differently at initial status and over time. In particular, higher team agreeableness predicted greater slopes of cohesion, but not initial cohesion levels. Also, higher extraversion predicted greater initial status of cohesion, but not greater slopes. These results present important boundary conditions for understanding the role of team personality composition on team cohesion. / Master of Science

Systems engineering has many subdisciplines which would be useful to study in terms of complex system behavior. However, it is the interactions between a complex system and its operating environment which drive the motivation for this analysis. Specifically, this work introduces a new approach to assessing these interactions called "boundary resilience." While classical resilience theory measures a system's internal reaction to adverse event, boundary resilience evaluates the impacts such an event may have on the surrounding environment. As the scope of this analysis is quite large, it was deemed appropriate to conduct a case study to determine the fundamental tenants of boundary resilience. SpaceX's satellite Internet mega-constellation (StarLink) was chosen due to its large potential to impact the space environment as well as its size and complexity. This study produced two boundary resilience measures, one for local boundary resilience of a single component and one for the global boundary behavior of the entire system. The local metric measures the likelihood of an adverse event occurring at that boundary location as well as its potential to impact the surrounding environment. The global boundary resilience metric reflects a nonlinear relationship among the system components. / Doctor of Philosophy / It is no secret that the world and the systems which enable it to function have become increasingly complex in recent decades. This complexity has the potential to create both innovative uses as well as unplanned and unexpected behaviors in these systems. As they interact with their environment, complex systems can produce equally complex and unpredictable behaviors which have potential to have a negative impact on their environment. This work seeks to study one component of this behavior: resilience. Resilience usually measures a system's ability to continue providing a service in the event of a disruption, or to recover the ability to provide the service after some amount of time. Boundary resilience, on the other hand, takes the perspective of potential environmental damage caused by an adverse event, rather than damage to the system's functionality. This study uses a case study of the StarLink satellite constellation to examine this phenomenon. The outcome of the analysis shows that the size of a complex system negatively impacts its potential to cause damage to the surrounding environment, but increasingly mature components can mitigate this degradation.