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This paper argues that polyphony is built on the transaction between voices and experiential truths, where voice and experience constitute each other. From this perspective voice is associated with the plural, transformational character of moment-to-moment experience. This view differs from the prevalent appropriation of polyphony where voice expresses a relatively stable identity (e.g. Hazen 1993) such that many voices (polyphony) may be reduced to many identities. The experiential understanding of polyphony is examined through close inspection of Bakhtin's contextualization of polyphony in carnival, a reading of his work that is largely missing from the organizational literature. This reading is further developed in the context of talk about teamwork in a large healthcare organization. Analysis of this talk reveals three different types of discursive truths that create different kinds of identities and different kinds of possibilities for organizational change: the public, teleological truths of epic discourse; the intimate truths of confession and irony; and the contested truths of the argument and what Bakhtin (1984) calls the microdialogue (or inner conversations with ourselves).

This study addressed two aspects of ecological theory developed primarily in North America and examined these theories using an Australian passerine as a model species. The first theory concerns the mechanisms by which habitat fragmentation affects avian populations. I investigated the mechanisms causing the decline of the Brown Treecreeper (Climacteris picumnus) in fragmented habitat, and specifically considered the effects of isolation and habitat degradation, which are potentially important in Australian woodlands, and edge (patch size), which are important in North America. Brown Treecreeper groups were as productive in isolated patches as in connected patches of habitat regardless of patch size, yet unpaired males were common in isolated fragments of habitat. I conducted a field experiment that confirmed that female dispersal was disrupted among isolated fragments. Thus, my results suggested Brown Treecreepers were declining due to disruption of dispersal by habitat fragmentation rather than degradation or edge effects. I compared the results of an individual-based, spatially explicit simulation model to field observations and concluded that territory spatial arrangement and matrix composition altered dispersal success, recruitment, and subsequent population growth. With the aid of a geographic information system, I determined that both landscape factors (fragmentation patterns within 4.5-km) and habitat characteristics (cavity density) explained Brown Treecreeper presence and absence from random locations in woodland habitat. The birds appear to be absent from suitable habitat in unsuitable landscapes. The second theory I addressed concerns the maintenance of avian cooperative breeding. The most widely accepted models to explain cooperative breeding suggest that individuals that delay dispersal obtain a payoff under conditions in which the quality of breeding positions varies greatly. These models arose chiefly from a few long-term studies in North American. This is an unfortunate bias because the occurrence of cooperative breeding among birds of Gondwanan origin is 22%, whereas the worldwide incidence is only 3%. I used demographic and habitat data to examine the influence of habitat and cooperative breeding on Brown Treecreeper fitness. Group size affected one component of fitness and habitat variables affected another. High cavity density may be favorable due to intense inter-specific competition for suitable cavities, which Brown Treecreepers require for roosting and nesting. Low tree density may be advantageous by favoring ground foraging, in which Brown Treecreepers frequently engage. Experimental manipulations of important habitat variables are needed to determine whether variability in these ecological factors is critical in maintaining group formation in this species. / Ph. D.

The rapidity space available for hadron production in electron-proton interactions at HERA is 11.4 units in width. In such a space the separation of virtual photon fragmentation from proton fragmentation is observed in events where the invariant mass of the final state hadronic system, W, is greater than 130 Ge V. Experimental cross sections for the virtual photon fragmentation process are presented. A new class of events is identified, where only virtual photon fragmentation and no proton fragmentation is observed. In the final state hadronic system of these events a rapidity gap over four units in width was discovered. Cross sections for these events are also presented, and comparisons are made with the theoretical predictions of the pomeron and hard diffraction models. / Ph. D.

Titre de l'écran-titre (visionné le 23 mai 2023) / Les changements dans les propriétés du minerai apportent des défis pour le contrôle des broyeurs semi-autogènes (SAG) car ils sont généralement difficiles à mesurer en temps réel et ont des impacts significatifs sur le procédé. Bien qu'il y ait un manque de compréhension de la nature des variations des propriétés du minerai dans les opérations réelles, les données disponibles sur la distribution granulométrique indiquent qu'elles sont caractérisées par des changements abrupts et des comportements en rampe, pour lesquels les modèles de perturbation standard utilisés dans le contrôle des procédés ne sont pas conçus. Dans ce travail, un modèle de perturbation déterministe se produisant de manière aléatoire (randomly-occurring deterministic disturbances (RODDs)) est considéré. Celui-ci possède une entrée commutant entre deux bruits aléatoires. Puisque la perturbation n'est pas gaussienne, un filtre de Kalman standard, qui est généralement utilisé pour l'estimation d'état, n'est pas optimal. Les capacités de deux observateurs à modèles multiples de détecter et d'estimer les états de systèmes soumis à des RODD non mesurés sont évaluées. Ces observateurs maintiennent plusieurs estimations des états du système sur la base de différentes hypothèses sur la commutation de la perturbation. La vraisemblance de chaque hypothèse compte tenu des mesures disponibles est évaluée et utilisée pour produire une meilleure estimation des états et de la sortie du procédé, qui demeure toutefois sous-optimale. Deux types d'observateurs à modèles multiples sous-optimaux sont évalués et comparés à un filtre de Kalman standard en utilisant des mesures de bruit simulées à partir de trois systèmes différents--un système linéaire avec un RODD et une sortie, un système linéaire avec deux RODD et deux sorties, et une simulation réaliste d'un circuit de broyage avec une mesure de sortie et une alimentation commutant entre deux types de minerai. Les résultats montrent que les observateurs à modèles multiples détectent et réagissent rapidement aux changements instantanés de la perturbation, sans pour autant avoir une sensibilité accrue au bruit lorsqu'en régime permanent. Cela suggère que des modèles plus réalistes de perturbations du minerai alimenté et une meilleure estimation en temps réel des changements dans les propriétés du minerai pourraient améliorer le contrôle du procédé, bien que les gains par rapport à un filtre unique de Kalman dépendent du niveau du bruit de mesure. / Changes in ore properties create challenges for the control of semi-autogenous grinding (SAG) mills because they are generally difficult to measure in real time and have significant impacts on the grinding process. Although there is a lack of understanding of the nature of variations in ore properties in real operations, available data on the particle size distribution indicates that they are characterised by abrupt step changes and ramp behaviours, which standard disturbance models used in process control are not designed for. In this work, an alternative disturbance model known as the randomly-occurring deterministic disturbance (RODD) is considered. This has a switching random noise input, which makes it suitable for modelling these types of disturbances. However, since the noise is non-Gaussian, a standard Kalman filter, which is typically used for state estimation, is not optimal. The capabilities of two multiple-model observers to detect and estimate the states of systems subjected to unmeasured RODDs are evaluated. These observers maintain multiple estimates of the system states based on different hypotheses about the switching of the disturbance. The likelihood of each hypothesis given the available measurements is estimated and used to produce a better, although still sub-optimal, estimate the process states and output. Two types of sub-optimal multiple-model observer are evaluated and compared to a standard Kalman filter using simulated noisy measurements from three different process systems--a linear system with one RODD and one output, a linear system with two RODDs and two-outputs, and a realistic grinding process simulation with a switching ore feed and one output measurement. The results show that the multiple-model observers detect and respond quickly to step changes in the disturbance, without having a compromised sensitivity to noise during steady-state. This suggests that more realistic models of ore feed disturbances and improved real-time estimation of changes in ore properties could have benefits in terms of improved process control, although the improvement compared to a single Kalman filter was found to depend on the magnitude of the measurement noise.

Wildlife biodiversity provides a variety of ecosystem services and is an important indicator of overall ecosystem health. This research investigates the relationship between wildlife biodiversity and landscape characteristics in Virginia. The goal is to produce predictive models of biodiversity within the Commonwealth using environmental characteristics, including fragmentation metrics at the class- and landscape-levels, as well as other environmental variables. The 1248 12-digit watersheds in Virginia are the sampling units for the analyses, with the state stratified into the seven US Environmental Protection Agency's Level III classification. Data on wildlife alpha diversity is based on two sets of species data maintained by the Virginia Dept. of Game & Inland Fisheries (VDGIF). The first chapter provides an introduction to the issue of biodiversity conservation and the background information for this work. The second chapter describes the study using the 2001 National Land Cover Data to calculate class- and landscape-level fragmentation metrics. Best subset regression is used to determine the best predictors for wildlife biodiversity using these metrics. Final selected models range in predictive power from R2 = 0.41 to 0.73 for each of the 7 ecoregions. The third chapter analyzes the relationship between wildlife biodiversity and various environmental variables in order to determine the strength of these factors as drivers for alpha diversity. These variables are then incorporated with the fragmentation metrics in an attempt to improve the biodiversity models. The environmental variable models had R2 = 0.22 to 0.65 across the ecoregions, while R2 = 0.28 to 0.72 when the environmental and fragmentation variables are combined. The last chapter focuses on the conclusions of the studies, the limitations of the data, and the benefits of this work. Overall, our results underline the importance of using fragmentation metrics in Virginia's wildlife models. / Master of Science

Personal Information Management (PIM) studies the practice of storing, organizing, and retrieving information by an individual in support of their roles and tasks (Bergman, et al., 2004). One important problem in PIM is information fragmentation (IF) — the condition of having data in different formats, distributed across multiple locations, manipulated by different applications, and residing in a generally disconnected manner (Tungare, 2007). IF can conflict with the PIM ideal that users should have access to the right information at the right time, in the right place, in the right form, and of sufficient completeness and quality to perform the task at hand (Bergman, et al., 2004). It is typically assumed that IF is unintentional, and occurs as a result of the many applications and devices we use to do our daily work. It is further assumed that IF is "bad" or has negative consequences. In this thesis, I study when IF occurs intentionally. Intentional IF (IIF) refers to the fragmentation in PIM that occurs when a person fragments his or her own personal data purposefully. Although research into the problem of IF has been growing quickly in the past decade, IIF has not been investigated in the literature. Prior studies have portrayed IF as a problematic type of information management. Email is a common context in which IF is found. While IF in email may be unintentional, such as when required by an employer, it is also likely to be intentional, as is the case when users use separate email accounts for different purposes. To further the research in this field, this project investigated the phenomenon of IIF in email by conducting and analyzing data from an online survey. In addition to finding the extent of IIF in email, the survey addressed what motivates the participant to purposely fragment their email as well as the advantages and disadvantages in doing so. My study is the first that has explored intentional fragmentation of information. The findings of this study show that IIF exists in email usage, revealing that IIF occurs across a user's devices and also across a user's multiple email accounts. The two most common motivations for IIF are to keep information separated by the user's social roles (work, school, personal communications, etc.), and to filter out extraneous information in order to simplify their information management. These results show that in addition to the negative consequences of IF there also exists positive uses of IF, that is helpful for some users. / Master of Science

Clinch Dace (Chrosomus sp. cf. saylori) is a newly recognized species of minnow with a restricted distribution in southwestern Virginia. Field sampling and genetic analysis support the hypothesis that Clinch Dace populations are small and fragmented. Analysis of neutral genetic markers shows that most Clinch Dace populations have undergone past bottleneck events and are being operated upon by random genetic drift. Bayesian cluster analysis showed that three out of the seven populations found in 2017 are distinct, while the other four show signs of more recent admixture. However, Fst values among streams were high and analysis of molecular variance indicated differentiation among populations in all streams. These findings support the view that these populations are genetically isolated. Effective populations sizes were low at most sites, enhancing the likelihood of loss of alleles to genetic drift. Low M-ratios, non-zero Fis values, and high degrees of relatedness among individuals indicate that some inbreeding is taking place. Habitat analysis did not identify variables affecting distribution or abundance of Clinch Dace populations. As the collection sites were targeted near known Clinch Dace occupied sites, it is likely that habitat variables known to impact Clinch Dace, such as conductivity, were within the species' range of tolerance. Results showed that Clinch Dace seem particularly resilient to sedimentation, corroborating earlier work showing a negative relationship between Clinch Dace abundance to sediment size. That is, small sediment size does not seem to have a negative impact on Clinch Dace abundance. Of all sites where Clinch Dace were found, only one culvert at one site was clearly perched and may present a barrier to upstream migration, a possibility which is supported by the genetic differentiation found among collections above and below that culvert. While this study demonstrates that selectively neutral genetic differentiation has taken place among Clinch Dace populations, it does address any local adaptation that may be taking place which would render translocations a risk for outbreeding depression. The findings of this study can inform conservation management in identifying possible sources of individuals for translocations among populations or for augmentation following captive breeding. / Master of Science / The Clinch Dace is a small, threatened minnow in the Clinch River basin that was unknown until 1999. Since then, research has addressed the biology, life history, and distribution of this fish. This study used data from selectively neutral genetic markers to analyze the population structure and degree of differentiation of Clinch Dace populations. My study sites were targeted at road crossings near known Clinch Dace populations to assess the effect of habitat fragmentation on Clinch Dace populations and to maximize the likelihood that I would collect enough genetic material for analysis. Genetic analyses showed that while there is some admixture among certain populations of Clinch Dace, there is differentiation at neutral genetic markers. This differentiation does not necessarily indicate adaptive variation among populations which could result in outbreeding depression should populations be mixed through translocations, but it is reason to proceed with caution. Road crossings were generally not found to be a cause of further population fragmentation in Clinch Dace, as demonstrated by genetic analysis and statistical analysis. Almost all of the occupied road crossing sites in this study were either embedded, free-flowing culverts that were not perched or small bridges, and these were not deemed to be obvious barriers to fish movement. The only exception was Hart Creek 2, where the culvert is slightly perched and Fst is high between populations in the upstream and downstream reaches. The results of this study will help to inform managers as to what conservation actions can be taken to improve population viability. One potential management action from this study could be the retrofitting of culverts that have become perched and are acting as barriers to Clinch Dace movement. Another potential conservation strategy is to translocate individuals from large population to small populations. The study determined: 1) which translocations might be acceptable based on the degree of genetic differentiation among populations, and 2) identified potential donor and receiving streams for translocations.