This research evaluated the new red imported fire ant (RIFA) bait Advion™. Advion™ contains the active ingredient indoxacarb which, following ingestion, must be metabolized into an N-decarbomethoxyllated metabolite known as JT333 in order to become acutely toxic. Laboratory experimentation was conducted to determine the most effective chemical form and concentration of indoxacarb, as well as the most appropriate grit size, for use in Advion™. The results indicated that Advion™ containing indoxacarb was more effective than Advion™ containing JT333, that 0.10%, 0.06%, and 0.045% were the most effective concentrations of indoxacarb, and that standard sized grit (~2 mm) was more effective than small sized grit (<1 mm). Field experimentation was conducted to determine the most effective concentration and quantity of Advion™, as well as the most effective placement of the bait, for obtaining maximum control of RIFA colonies via individual mound treatments. The results indicated that 10 g (2 Tbsp) of 0.045% Advion™ placed around the mound in a circle with a radius of 0.5-3.0 m was the most effective manner in which to treat individual RIFA mounds. Field experimentation was also conducted to compare the effectiveness of label-rate broadcast treatment with Advion™ to the effectiveness of both label-rate broadcast treatment with Amdro® and pre-baiting broadcast treatment with Advion™. Both pre-baiting broadcast treatment and label-rate broadcast treatment with Advion™ ultimately resulted in 98-99% RIFA colony mortality, which was significantly greater than the 87% colony mortality resulting from broadcast treatment with Amdro®. The 6.2 d LT90 for label-rate broadcast treatment with Advion™ was nearly one half that of the LT90 for pre-baiting broadcast treatment. Laboratory experimentation was conducted to determine whether RIFA workers were capable of metabolizing indoxacarb into the toxic metabolite, and the results clearly indicated that they were. Finally, field experimentation was conducted to evaluate the effectiveness of label-rate broadcast treatment with Advion™ at controlling multiple ant species. The results indicated that label-rate broadcast treatment with Advion™ resulted in control of the RIFA and Pogonomyrmex barbatus for at least 7 wk, and Monomorium pharaonis and Dorymyrmex pyramicus for some period of time between 3 and 7 wk.

NASA's current plans for human spaceflight include an evolutionary series of missions based on a steady increase in capability to explore cis-lunar space, the Moon, near-Earth asteroids, and eventually Mars. Although the system architecture definition has the greatest impact on the eventual performance and cost of an exploration program, selecting an optimal architecture is a difficult task due to the lack of methods to adequately explore the architecture design space and the resource-intensive nature of architecture analysis. This research presents a modeling framework to mathematically represent and analyze the space system architecture design space using graph theory. The framework enables rapid exploration of the design space without the need to limit trade options or the need for user interaction during the exploration process. The architecture design space for three missions in a notional evolutionary exploration program, which includes staging locations, vehicle implementation, and system functionality, for each mission destination is explored. Using relative net present value of various system architecture options, the design space exploration reveals that the launch vehicle selection is the primary driver in reducing cost, and other options, such as propellant type, staging location, and aggregation strategy, provide less impact.

This thesis focuses on the role of nonhumans in the process of value production on social media platforms. In particular, we investigate the relation between algorithm based sorting mechanisms and human work, here exemplified by the role of a hashtag in social media users’ production of identity. Previous research has shown that social media users produce identity by organising web material into coherent narratives. As suggested by Marxist media scholars (Fuchs, 2014; Bolin, 2011), such organising of material can be perceived as a value generating work process. However, little research has explored how hashtags, and other digital nonhuman actors, are involved in this process. The ambition of this study is therefore to enable a closer understanding of hastags’ relation to value producing organisational work. To do this we have selected a specific case to analyse; the hashtag rockasockorna – a Swedish version of the American hashtag rockthesocks. Our empirical material consists of a quantitative data set, collected with aid of a statistical analysis software (hashtracking.com), as well as two qualitative ethnographic case studies on the two statistically most influential users. To analyse the material we use a methodological approach based on Bruno Latour’s (2005) Actor Network Theory. Primarily, the approach is inspired by Latour’s concept of the circulating reference (1999), meaning that relations described in the qualitative material are gradually reduced into a generalised model. The model suggests that the hashtag takes a position of what we refer to as a “quasi consumer”, an imitator of human organisational work. In the paper’s final section the results are brought into dialogue with contemporary Marxist value theory. We argue that existing literature tends to neglect the aspect of nonhumans as consumers, and thus further research should investigate the implications of nonhuman consumption.

Geographic Information Systems (GIS) have demonstrated their utility in predictively modeling the location of archaeological sites, and providing a framework for cataloging sites eligible for heritage management status. The intent of this GIS-based study is to begin to create a geohistorically organized database of information culled from historic documents and archaeological excavation. In this case study of postbellum land tenure in Hillsborough County, Florida, a GIS-based approach is used to demonstrate the impacts of federal and state land ownership policy decisions during the Reconstruction Era and beyond. GIS data are also used to reveal information about how people use their allotted environment to non-verbally communicate their perceptions of the world and their place in it. Finally, GIS are shown to be ideally suited for allowing multi-scalar, diachronic comparisons of archaeological sites and materials. This research was conducted according to the concepts of Actor-Network-Theory (ANT), which assumes there is a generalized symmetry between the agency of human actors and non-human actants (i.e. it does not assume the primacy of human intentional action). ANT accepts that materials can carry non-verbal messages (e.g. colors, aromas, tactility), which affect how humans interact, communicate, and organize themselves in space. ANT allows for the use of scales based on human action, and analyses that are based standardized metrologies. Finally, ANT obviates being limited to strict categories of macro- and micro-, by accepting that networks may bridge both. This research shows that two rural communities have undergone similar growth trajectories, with a historically black community having experienced some setbacks in the early 20th century. However, the results show that the rural African American community was not more subdivided than the neighboring Euro-American community, contrary to initial expectations. Additionally, there is a suggestion that communities may move socially important buildings such as churches schools to the community center or periphery, depending on the intended recipient of the message. The study also documents the centralization, concentration, and clustering of the county's African American population through time.

Process planning and scheduling are two important manufacturing planning functions which are traditionally performed separately and sequentially. Usually, the process plan has to be prepared first before scheduling can be performed. However, due to the complexity of manufacturing systems and the uncertainties and dynamical changes encountered in practical production, process plans and schedules may easily become inefficient or even infeasible. The concept of integrated process planning and scheduling (IPPS) has been proposed to improve the efficiency, effectiveness as well as flexibility of the respective process plan and schedule. By combining both functions together, the process plan for producing a part could be dynamically arranged in accordance with the availability of manufacturing resources and current status of the system, and its operations’ schedule could be determined concurrently. Therefore, IPPS could provide an essential solution to the dynamic process planning and scheduling problem in the practical manufacturing environment. Nevertheless, process planning and scheduling are both complex functions that depend on many factors and flexibilities in the manufacturing system, IPPS is therefore a highly complex NP-hard problem. Ant colony optimization (ACO) is a widely applied meta-heuristics, which has been proved capable of generating feasible solutions for IPPS problem in previous research. However, due to the nature of the ACO algorithm, the performance is not that favourable compared with other heuristics. This thesis presents an enhanced ACO approach for IPPS. The weaknesses and limitations of standard ACO algorithm are identified and corresponding modifications are proposed to deal with the drawbacks and improve the performance of the algorithm. The mechanism is implemented on a specifically designed multi-agent system (MAS) framework in which ants are assigned as software agents to generate solutions. First of all, the manufacturing processes of the parts are graphically formulated as a disjunctive AND/OR graph. In applying the ACO algorithm, ants are deployed to find a path on the disjunctive graph. Such an ant route indicates a corresponding solution with associated operations scheduled by the sequence of ant visit. The ACO in this thesis is enhanced with the novel node selection heuristic and pheromone update strategy. With the node selection heuristic, pheromone is deposited on the nodes as well as edges on the ant path. This is contrast to the conventional ACO algorithm that pheromone is only deposited on edges. In addition, a more reasonable strategy based on “earliest completion time” of operations are used to determine the heuristic desirability of ants, instead of the “greedy” strategy used in standard ACO, which is based on the “shortest processing time”. The approach is evaluated by a comprehensive set of problems with a full set of flexibilities, while multiple performance measurements are considered, including makespan, mean flow time, average machine utilization and CPU time, among which makespan is the major criterion. The results are compared with other approaches and encouraging improvements on solution quality could be observed. / published_or_final_version / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

<p>Plants commonly produce multiple, seemingly redundant defenses, but the reasons for this are poorly understood. The specificity of defenses to particular herbivores could drive investment in multiple defenses. Alternatively, genetic correlations between defenses could lead to their joint expression, even if possessing both defenses is non-adaptive. Plants may produce multiple defenses if putative resistance traits do not reduce damage, forcing plants to rely on tolerance of damage instead. Furthermore, resource shortages caused by herbivore damage could lead to compensatory changes in expression and selection on non-defense traits, such as floral traits. Natural selection could favor producing multiple defenses if synergism between defenses increases the benefits or decrease the costs of producing multiple defenses. Non-linear relationships between the costs and benefits of defense trait investment could also favor multiple defenses.</p><p>Passiflora incarnata (`maypop') is a perennial vine native to the southeast United States that produces both direct, physical traits (leaf toughness and trichomes) and rewards thought to function in indirect defense (extrafloral nectar in a defense mutualism with ants), along with tolerance of herbivore damage. I performed two year-long common garden experiments with clonal replicates of plants originating from two populations. I measured plant fitness, herbivore damage, and defense traits. I ran a genotypic selection analysis to determine if manipulating herbivore damage through a pesticide exclusion treatment presence mediated selection on floral traits, and if herbivore damage led to plastic changes in floral trait expression. To evaluate the role of selection in maintaining multiple defenses, I estimated fitness surfaces for pairwise combinations of defense traits and evaluated where the fitness optima were on each surface. </p><p>I found that resistance traits did not reduce herbivore damage, but plants demonstrated specific tolerance to different classes of herbivore damage. Tolerance was negatively correlated with resistance, raising the possibility that tolerance of herbivore damage instead of resistance may be the key defense in this plant, and that production of the two type of defense is constrained by underlying genetic architecture. Plants with higher levels of generalist beetle damage flowered earlier and produced proportionally more male flowers. I found linear selection for both earlier flowering and a lower proportion of male flowers in the herbivore exclusion treatment. I found that selection favored investment in multiple resistance traits. However, for two tolerance traits or one resistance and one tolerance trait, investment in only one trait was favored. </p><p>These results highlight the possibility of several mechanisms selecting for the expression of multiple traits, including non-defense traits. Resistance traits may have a non-defensive primary function in this plant, and tolerance may instead be a key defense strategy. These results also emphasize the need to consider the type of trait--resistance or tolerance--when making broad predictions about their joint expression.</p> / Dissertation

Mutualism is an often-complex positive interaction between species, each of which responds independently to varying biotic and abiotic conditions. Temperature is an important factor that can affect species both directly (e.g., physiologically) and indirectly (e.g., via its effects on interactions with consumers, competitors, and mutualists). Although much research has investigated the consequences of temperature for individual organisms, the effects of temperature on the formation, dissolution, and success of species interactions remain minimally understood. The unique ways in which species respond to temperature likely play a role in structuring communities. Environmental heterogeneity, including the thermal environment, can promote coexistence when species exploit resources in different ways, such as by occupying different thermal niches. This dissertation examines the consequences of temperature for participants in an ant-plant protection mutualism, and investigates how the thermal ecology of individual species affects the interaction. Many mutualisms involve multiple species, or interacting guilds. In these mutualisms, species interact with partner species that vary in multiple characteristics. Mutualists are quite sensitive to both partner quantity and partner quality (e.g., their effectiveness at performing a beneficial task). Mutualisms between ants and plants are common across a variety of habitats worldwide, which differ in thermal range, fluctuation, and seasonality. In light of ants’ well-studied and predictable responses to temperature, ant-plant interaction networks provide excellent systems for studying the thermal ecology of mutualisms. In ant-plant protection mutualisms, each of the participants (ants, plants, and enemies) likely differs in its response to temperature. In addition to the direct effects of temperature on ant species, temperature may affect the magnitude of mutualistic interactions among species by affecting the quantity and quality of the reward offered to partners, and the activity of the partners themselves and the plant’s enemies (i.e., herbivores). If herbivores are more thermally tolerant than the mutualistic ant defenders, the consequences for plants may well be severe; however, if herbivores are less thermally tolerant than are the ants, the effects of rising temperatures might be mitigated: although less-effective ants might be more frequent in a warmer world, herbivores would be less abundant there. This dissertation describes the thermal ecology of the participants in a mutualism between the cactus Ferocactus wislizeni and four of its common ant defenders (Forelius pruinosus, Crematogaster opuntiae, Solenopsis aurea, and Solenopsis xyloni) in the extreme environment of the Sonoran Desert, USA. The ants are attracted to extrafloral nectar produced by the plant, and in exchange protect the plants from herbivores, including a common phytophagous cactus bug, Narnia pallidicornis (Hemiptera: Coreidae). Specifically, it investigates how thermal ecology of the individual species affects the interactions among those species. Also, it considers the impact of a tradeoff between behavioral dominance and thermal tolerance among ants.

The aim of this thesis was to describe the structure and dynamics of ant and plant communities in the southern Karoo and to assess mechanisms of species coexistence in ant and plant communities. The role of species interactions in structuring natural communities was emphasised. Diversity indices were used to determine the importance of habitat in maintaining ant species diversity. Ant species diversity was not predicted by measurements of plant species diversity or vegetation structural diversity. Ant species richness was correlated with vegetation structural diversity but not with plant species diversity. Ant species appeared to respond to aspects of vegetation height. Although vegetation complexity influences ant species richness, competitive effects, particularly of dominant ant species, appear to suppress sub-ordinate ant species influencing measures of richness and diversity. Aggressive dominant ant species determine the distribution and abundance of sub-ordinate ant species. Interference competition for space was prevalent between dominant ant species and competitive success was a function of vegetation. It was not clear whether ants respond directly to physical conditions created by vegetation which then influences foraging activity or, alternatively, whether ants respond to productivity gradients which are affected by vegetation. Understanding vegetation dynamics is critical to interpreting patterns of ant species distribution and abundance. A patchy habitat disrupts the competitive dominance of aggressive dominant species, removing the potential towards habitat monopolisation, and therefore maintaining ant species diversity. In the Portulacaria afra rangeland, Pheidole sp. 2 was superior in well-shaded microhabitats but Messor capensis nested successfully under woody shrubs and several ant species (Tetramorium peringueyi, T. quadrispinosum, Monomorium alamarum, Ocymyrmex barbiger) persisted on bare nutrient-rich patches. Rangeland dominated by grass would favour Pheidole sp. 2 at the expense of other ant species which would be unable to establish successfully. There is no evidence supporting the notion that ant communities are at equilibrium. Rather, dominance hierarchies lead to the replacement of species over vegetation gradients with the tendency towards the aggressive acquisition and monopolisation of space. The coexistence of dominant ant species at study sites in the southern Karoo was a combination of territorial strategy and colonisation ability. In the P. afra rangeland most ant species escaped the severe competitive effect of Pheidole sp. 2 by persisting as fugitives on bare areas of local disturbance where Pheidole sp. 2 was less successful. At Tierberg, competitively inferior ant species with a decentralised territorial system coexisted with competitively superior ant species in an unstable equilibrium by pre-empting newly available space through the lateral expansion of territories. Competitively superior species, however, replace the inferior competitor (yet, superior coloniser) in time. Plant succession in the Portulacaria afra rangeland follows a deterministic pattern of cyclical replacement. No single mechanism adequately explains the coexistence of all plant species in this community. Nurse-plant effects were important for the establishment of P. afra and later-successional trees below woody shrubs and P. afra respectively. Soil moisture and nutrient levels below nurse plants were favourable for the successful establishment of seedlings but nurse plants also disrupt the inhibitory effect of grass on seedlings and young plants. Linked to the facilitative process is the directed dispersal of seeds by biotic vectors. Seed dispersal by ants and birds moves propagules away from the harsh competitive environment of established adult plants (particularly grass) to safe establishment sites below nurse plants. Complementary root systems of seedlings and nurse plants may facilitate the establishment of young plants but ultimately competition will reduce nurse plant vigour leading inevitably to the death of the nurse plant. At least two plant species (Lycium cinereum and Psilocaulon absimile) persist in the P. afra rangeland as fugitives on areas of local disturbance. The relatively cool and moist environment below P. afra clumps supports a variety of detritivorous taxa that enrich the soil. Once the P. afra clump collapses and dies, bare nutrient rich patches that favour the establishment of L. cinereum and P. absimile, ahead of the competitively superior grass component, remain. However, the replacement of the fugitive plant species by grass is inevitable as the soil nutrient levels decline. The competitive superiority of grass controls the dynamics of the P. afra rangeland system. Disruption of the inhibitory effect of grasses by elevated nutrient levels (e.g. detritivore activity, ant nests) permits plant species to establish that would otherwise be unable to in the absence of disturbance. Degradation of the grass component by overgrazing at the P. afra rangeland site has the same effect as disturbance by soil-nutrient enrichment and results in an increase in plant species diversity. All stages of the cyclical process would be relatively uncommon in a grass dominated system because of the inability of plants to establish successfully in grass. Strong feedback links exist between the ant and plant communities studied. Habitat patchiness maintains ant species diversity by disrupting dominance hierarchies. Ants maintain plant species diversity by moving seeds out of competitively harsh microhabitats into safe sites (often below nurse plants) for establishment. Soil nutrient enrichment (ant nests and various detritivore taxa) create disturbances which also facilitates plant establishment. Overgrazing by domestic stock causes the replacement of palatable by unpalatable plant species. Unpalatable plant species, released of suppressive effects, develop into a monospecific stand that inhibits the further establishment of seedlings. Loss of habitat patchiness results in habitat monopolisation by one (or two) dominant ant species. Habitat degradation therefore severs the complex feedback links between the plant community and the important invertebrate component (dispersal agents and detritivores) which disrupts the dynamic processes driving the system. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1998.

Vehicular Ad hoc Networks (VANET) exhibit highly dynamic behavior with high mobility and random network topologies. The performance of Transmission Control Protocols in such wireless ad hoc networks is plagued by a number of problems: frequent link failures, scalability, multi-hop data transmission and data loss. To address these VANET routing issues, I have used the ideas from swarm intelligence. The Ant Colony Optimization (ACO), which is a branch of swarm intelligence, is the main source of my inspiration. I have designed an ant-based routing algorithm which addresses routing issues prevalent in VANETs: adaptivity, robustness and scalability. One attractive feature of ACO is that they provide multiple routes from source to destination, resulting in more robust network. In this work, together with ACO, I have used the ideas from zone routing protocols to develop my algorithm: Mobility Aware Zone based Ant Colony Optimization Routing for VANET that exhibits locality and scalability.

This thesis seeks to answer the ‘key question’: ‘how is the border worked at an international airport?’ To answer this key question the author, who is employed as a Customs officer, uses participant observation to provide material for an anthropological analysis of this question. The primary anthropological focus that will permeate throughout this thesis is interconnectedness of human and non human actors. This focus on interconnectedness will be linked to the ability of the workers of the border to communicate about risk to one another. Risk at the border is highly political following the terrorist attacks of September 11 (9/11). The attacks are not a focus of this thesis but a study of the border network will shed some light on how the workers of the border make sense of external factors such as these attacks (9/11) in their work world. The thesis accounts for links between the border workers of different government agencies and uses the idea of an occupational community to do so. The thesis will attempt to account for technologies within the border network. The account of technologies will demonstrate through an actor network approach their hybrid nature, and their ability to negotiate and renegotiate the border network. Power is analysed at the border through the ideas of Foucault. Though the idea of occupational community, actor network theory and the ideas of Foucault on power are not linked outside of this thesis in any way, they provide an honest account of the border network as expressed through the case study of risk and interagency communication at an international airport.