The inherent genetic similarity between oat (<i>Avena sativa</i> L.) and wild oat (<i>Avena fatua</i> L.) precludes selective herbicide use to control wild oat. Consequently, large reductions in oat yield and quality due to wild oat consistently constrain oat production in western Canada. Traditionally, delayed seeding followed by tillage prior to planting was used to control wild oat, but new studies have shown that this practice also results in substantial reductions to oat yield and quality. Thus, new methods are needed to ameliorate the adverse effects of wild oat competition on oat. Planting more competitive varieties with earlier emergence and larger seeds may minimize losses associated with wild oat competition. Therefore, the objectives of this research were i) to determine the influence of wild oat emerging at different times and varying densities on oat yield and quality and ii) to determine the relative importance of seed size and genotype in affecting wild oat oat competition. High densities of early emerging wild oat greatly reduced oat yield and increased wild oat contamination. Observed oat yield losses were as great as 70% and resulted in a 15% wild oat contamination level. Wild oat that emerged before oat also had higher biomass and reproductive output than wild oat that emerged after oat. Furthermore, early emerging wild oat reduced percentage plump oat kernels and increased percentage thin kernels. Oat plants established from large caryopses produced 18% more biomass and 15% more panicles m^-2 than plants established from small caryopses. In addition, wild oat produced 31% less biomass and fewer panicles m^-2 when grown with oat plants established from large caryopses. CDC Boyer appeared to be the most competitive of the varieties examined, having significantly higher biomass and panicle production both in the presence and absence of wild oat competition. Conclusions that emerge from this research are i) emergence time is critical to wild oat oat competition, ii) it is essential for oat producers to control early emerging wild oat and ensure crop emergence precedes wild oat emergence, iii) planting large seed of competitive cultivars may improve the competitive response of oat to wild oat.

The Texas Blackland Prairie is one of the most productive agricultural regions in Texas. This region provides a long growing season coupled with soils that have a high water holding capacity. However, the soils also provide significant challenges to producers because the high water holding capacity is a product of a high clay percentage. This research was aimed to develop and test an expert-based trafficabililty index, based upon soil moisture, for planting cotton (Gossypium hirsutum L.) and corn (Zea mays L.) on the Texas Blackland Prairie. Testing the index focused on quantify the potential effect of high soil moisture at planting on seed furrow sidewall compaction and associated plant growth response. Once the trafficability index was developed, three workable soil moisture regimes were recreated in no-tillage and conventional tillage plots at the Stiles Farm Foundation in Thrall, Texas. The index nomenclature included: "Dry-Workable", "Optimal" and "Wet-Workable". After planting corn and cotton into conventional and no tillage plots, 0.45 x 0.20 x 0.15 m intact soil blocks were removed from each plot and kept in a controlled environment. At 28 days, each block was destructively harvested to quantify plant root and shoot growth responses. Each of the three soil moisture indexes was replicated thrice per crop, and the whole experiment was replicated twice in time, n = 48 blocks. The trafficability index was created using three producer experts, and over 10 interviews to collect a range in soil moisture samples. From "Wet Workable" to "Dry Workable", the gravimetric soil moistures were 0.17, 0.22, and 0.26 g g-1. For corn and cotton, a positive relationship between plant growth factors and planting at soil moisture existed. Plants planted at the highest soil moisture emerged faster and developed more root and shoot biomass than those planted at the lowest soil moisture. No evidence of a detrimental plant response because of seed furrow, sidewall compaction from planting at too high a soil moisture content could be quantified. Furthermore, the cotton plants in no-tillage performed better than in conventional tillage, but corn performed better in conventional tillage. Because the results showed an advantage to plant growth by planting in the "Wet Workable" index, the tillage practice that allows the producer to enter the field with a planter at higher moisture contents appears to have an advantage.

Recent studies in cognitive science indicate that language has an important social function. The structure and knowledge of language emerges from the processes of human communication together with the domain-general cognitive processes. Each individual of a community interacts socially with a limited number of peers. Nevertheless societies are characterized by their stunning global regularities. By dealing with the language as a complex adaptive system, we are able to analyze how languages change and evolve over time. Multi-agent computational simulations assist scientists from different disciplines to build several language emergence scenarios. In this thesis several simulations are implemented and tested in order to categorize examples in a test data set efficiently and accurately by using a population of agents interacting by playing categorization games inspired by L. Steels&#039 / s naming game. The emergence of categories throughout interactions between a population of agents in the categorization games are analyzed. The test results of categorization games as a model combination algorithm with various machine learning algorithms on different data sets have shown that categorization games can have a comparable performance with fast convergence.

Works on semiotic dynamics and language as a complex adaptive system in general has been an important lane of research over the last decade. In this study, the mean-field naming game model developed in the course of the pioneering research programme of Luc Steels and colleagues is modified to include probabilistic word choice based on weighted lists of words, instead of either deterministic or totally random word choice based on (ordered) sets of words. The parameters&rsquo / interaction and this interaction&rsquo / s effect on time of convergence of the system and size of individual lexicons over time are investigated. The classical model is found to be a special case of this proposed model. Additionally, this model has more parameters and a larger state space which provides additional room for tweaking for time- or space-optimization of the convergence process.

Two peaks of eclosion dates, about 15 days apart, occur in the same batch of fertilized eggs in the marine midge, Pontomyia oceana. Two hypotheses, the variable adaptive peaks and the bet-hedging hypotheses, were proposed as the ultimate factor of the polymorphic phenomenon. They were tested by experiments controlling feeding amount and photoperiod, as well as selective breeding experiments. The offspring eclosing in the two peaks do not differ in fecundities, egg diameters, thorax and head lengths of males; this is not compatible with the variable adaptive peaks hypothesis. Both peaks exist under various feeding and photoperiods, although peak ratios differed in the former. The results in the first peak lineage did not support there is genetic component in peak ratio determination. The experiments in the second peak lineage had much lower success rates, although the results seemed to suggest a genetic component. The results in a more extreme selection experiment did not support that there is genetic component either. The present results are more compatible with the bet-hedging hypothesis. Wind velocity may be a factor hard to predict by the midges, and it may cause reproductive failure of them. Whereas high emergence synchronization, a prominent feature of the marine midge, may have advantages in many aspects, it also concentrates the risk of total reproductive failure. Spreading offspring to more than one suitable eclosion peak, the midge may have sacrificed short-term reproductive rate for long-term fitness.

This paper seeks to forge a grounds for conversation between the affective turn in contemporary theory and a vital materialist ontology. This conversation focuses on materials and their affects through the experience of weirdness. I use weirdness to describe a register of enchantment which is disruptive and alienating, rather than enticing and delightful. The project is motivated by a desire for ways to think about our relationship to the natural world that afford for fuller experiences of perception. The paper works through four major sections; the first three form a conceptual framework while the fourth is an exercise in mobilizing the concepts through subjective readings of affect. It begins by establishing a concept of vitalism with which to think about interactions with a moving, active world and, in following vitalism across borders of embodied flora and fauna, agitates the notion of what constitutes life. To put vitalism into a dynamic of engagement between entities, I then chart processes of affect through various conditions and situations, such as haunting, hallucination, anticipation and psychotropics. I then address the concept of the event in order to trace the contours of affect as it manifests through situated, temporal passages of force. This conceptual netting culminates in episodic readings of affective experiences, taking a kaleidoscopic form oriented toward anxious fascination. / text

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Nous proposons de contribuer par une approche géographique à l'étude du phénomène d'émergence de maladies virales en Afrique forestière équatoriale en nous appuyant sur les origines probables de l'infection à VIH-sida. Le Virus d'Immunodéficience Humaine (VIH), responsable de la pandémie actuelle de sida, est d'origine zoonotique. Né de la recombinaison des formes simiennes de rétrovirus, le virus humain (VIH) est issu du passage de la barrière inter-espèces des agents viraux portés par les primates (Virus d'Immunodéficience Simienne - VIS) et qui ont été sélectionnés au fil des temps et à l'occasion d'expositions multiples et prolongées aux organismes humains. L'objet de ce travail est la lecture du processus d'émergence des maladies virales comme un système dans lequel interagissent dynamiques spatiales, aspects humains et paramètres environnementaux. Il s'agit d'explorer la piste des origines de l'émergence du VIH-sida sous le prisme d'une étude géographique : les habitudes migratoires, territoriales, domestiques des populations forestières de l'est Cameroun peuvent créer des situations périlleuses en termes d'exposition, de diffusion et de propagation des maladies virales

In this thesis we investigate two approaches to quantum gravity. The first is the emergence of gravity from a discrete fundamental theory, and the second is the direct quantisation of gravity. For the first we develop tools to determine with relatively high accuracy the speed of propagation of information in collective modes which ultimately should give us some information about the emergent causal structure. We found a way of finding the dependence on the relative interaction strengths of the Hamiltonian and we also managed to calculate this speed in the case where the operators in the Hamitonian were not necessarily bounded. For the second approach, we investigated the phenomenology of Loop Quantum Gravity. We found that ultra light black holes (lighter than the Planck mass) have interesting new properties on top of being non-singular. First their horizon is hidden behind a Plancksized wormhole, second their specific heat capacity is positive and they are quasi-stable, they take an infinite amount of time evaporate. We investigated the dynamics of their collapse and evaporation explicitly seeing that not only was there no singularity, but there is also no information loss problem. Looking at how primordial black holes were in existence, we found that they might account for a significant portion of dark matter. And if they did, their radiation spectrum is such that the black holes in the dark matter halo of our galaxy could be the source for the ultra high energy cosmic rays we observe on earth.

Identifying the emergence and development of new technologies has become an essential ability for firms competing in dynamic environments. Nonetheless, current technology intelligence practices are unstructured and vaguely defined. Moreover, the existing literature in future technology studies lacks strong, systematic explanations of what technologies are, where technologies come from, and how new technologies emerge and evolve. The present study builds on Structuration Theory, and proposes the structurational model of emerging technologies (SMET). The SMET suggests not only an ongoing view of technologies as social objects, but also a process for thinking through scientifically the complex, multidimensional and emergent dynamic of social and technological change. The SMET proposes that the emergence and development of a new technology can be tracked by examining systematically and collectively the extent of development of its technology-related social structure – its degree of structuration. The degree of structuration of a technology is an ongoing process instantiated in social practices, and can be observed through visible patterns or specific social outcomes of systemic activity organized in three analytical dimensions: structures of meaning, power, and legitimacy. The SMET assumes that the conceptual initiation of a new technology triggers new patterns of social activity or a signal of technological change; thus, the variation in the slope or trajectory of the degree of structuration of a technology may indicate an early signal of technological change. The SMET sets a foundation for identifying early signals of technological change when it is used on a systematic basis. Empirically, the study conducted an exploratory case study in the Internet industry. The study employed a sequential transformative mixed method procedure, and relied on 77 Internet experts to create retrospectively a systematic and collective interpretation of the Internet industry in the last ten (10) years. The test of hypotheses was based on only seven (7) Internet technologies due to time and instrumental constraints. The results confirm the fundamental relationships among constructs in the model, and support, thus, the SMET. The degree of structuration of a technology is revealed as a process independent of individuals’ participation in the enactment of a technology. Technological outcomes are explained by the extent of development of structures of meaning, power, and legitimacy (i.e., the degree of structuration of a technology). Moreover, influential technological outcomes shape individuals’ perspectives over time – i.e., the structurational effect. Hence, the study not only provides evidence that supports this novel theoretical framework, but also illustrates methodologically how to identify the emergence and development of new technologies. Likewise, the study discusses the implications of these results for technology management practices (e.g., product and technology development, innovation policies, and technology transfer activities). Lastly, the study recognizes limitations and suggests further research avenues.