Bubble Universe Dynamics After Free Passage

We consider bubble collisions in single scalar field theories with multiple vacua. Recent work has argued that at sufficiently high impact velocities, collisions between such bubble vacua are governed by 'free passage' dynamics in which field interactions can be ignored during the collision, providing a systematic process for populating local minima without quantum nucleation. We focus on the time period that follows the bubble collision and provide evidence that, for certain potentials, interactions can drive significant deviations from the free-passage bubble profile, thwarting the production of bubbles with different field values.Comment: 21pages, 8 figures, Revised version modified to include Acknowledgements sectio

Optical and probe determination of soot concentrations in a model gas turbine combustor

An experimental program was conducted to track the variation in soot loading in a generic gas turbine combustor. The burner is a 12.7-cm dia cylindrical device consisting of six sheet-metal louvers. Determination of soot loading along the burner length is achieved by measurement at the exit of the combustor and then at upstream stations by sequential removal of liner louvers to shorten burner length. Alteration of the flow field approaching and within the shortened burners is minimized by bypassing flow in order to maintain a constant linear pressure drop. The burner exhaust flow is sampled at the burner centerline to determine soot mass concentration and smoke number. Characteristic particle size and number density, transmissivity of the exhaust flow, and local radiation from luminous soot particles in the exhaust are determined by optical techniques. Four test fuels are burned at three fuel-air ratios to determine fuel chemical property and flow temperature influences. Particulate concentration data indicate a strong oxidation mechanism in the combustor secondary zone, though the oxidation is significantly affected by flow temperature. Soot production is directly related to fuel smoke point

Turbine endwall single cylinder program

Measurements of the flow field in front of a large-scale single cylinder, mounted in a wind tunnel are discussed. Static pressures on the endwall and cylinder surfaces, extensive five-hole probe pressures in front of and around the cylinder, and velocity fluctuations using a hot-wire probe where the flow is steady enough to yield meaningful results are included

Measurements of a turbulent horseshoe vortex formed around a cylinder

An experimental investigation was conducted to characterize a symmetrical horseshoe vortex system in front of and around a single large-diameter right cylinder centered between the sidewalls of a wind tunnel. Surface flow visualization and surface static pressure measurements as well as extensive mean velocity and pressure measurements in and around the vortex system were acquired. The results lend new insight into the formation and development of the vortex system. Contrary to what has been assumed previously, a strong vortex was not identified in the streamwise plane of symmetry, but started a significant angular distance away from it. Rather than the multiple vortex systems reported by others, only a single primary vortex and saddle point were found. The scale of the separation process at the saddle point was much smaller than the scale of the approaching boundary layer thickness. Results of the present study not only shed light on such phenomena as the nonsymmetrical endwall flow in axial turbomachinery but can also be used as a test case for three-dimensional computational fluid mechanics computer codes

Capriccio For Strings: Collision-Mediated Parallel Transport in Curved Landscapes and Conifold-Enhanced Hierarchies Among Mirror Quintic Flux Vacua

This dissertation begins with a review of Calabi-Yau manifolds and their moduli spaces, flux compactification largely tailored to the case of type IIb supergravity, and Coleman-De Luccia vacuum decay. The three chapters that follow present the results of novel research conducted as a graduate student. Our first project is concerned with bubble collisions in single scalar field theories with multiple vacua. Lorentz boosted solitons traveling in one spatial dimension are used as a proxy to the colliding 3-dimensional spherical bubble walls. Recent work found that at sufficiently high impact velocities collisions between such bubble vacua are governed by "free passage" dynamics in which field interactions can be ignored during the collision, providing a systematic process for populating local minima without quantum nucleation. We focus on the time period that follows the bubble collision and provide evidence that, for certain potentials, interactions can drive significant deviations from the free passage bubble profile, thwarting the production of a new patch with different field value. However, for simple polynomial potentials a fine-tuning of vacuum locations is required to reverse the free passage kick enough that the field in the collision region returns to the original bubble vacuum. Hence we deem classical transitions mediated by free passage robust. Our second project continues with soliton collisions in the limit of relativistic impact velocity, but with the new feature of nontrivial field space curvature. We establish a simple geometrical interpretation of such collisions in terms of a double family of field profiles whose tangent vector fields stand in mutual parallel transport. This provides a generalization of the well-known limit in flat field space (free passage). We investigate the limits of this approximation and illustrate our analytical results with numerical simulations. In our third and final project we investigate the distribution of field theories that arise from the low energy limit of flux vacua built on type IIb string theory compactified on the mirror quintic. For a large collection of these models, we numerically determine the distribution of Taylor coefficients in a polynomial expansion of each model's scalar potential to fourth order. We provide an analytic explanation of the proncounced hierarchies exhibited by the random sample of masses and couplings generated numerically. The analytic argument is based on the structure of masses in no scale supergravity and the divergence of the Yukawa coupling at the conifold point in the moduli space of the mirror quintic. Our results cast the superpotential vev as a random element whose capacity to cloud structure vanishes as the conifold is approached

Systematics of Aligned Axions

We describe a novel technique that renders theories of $N$ axions tractable, and more generally can be used to efficiently analyze a large class of periodic potentials of arbitrary dimension. Such potentials are complex energy landscapes with a number of local minima that scales as $\sqrt{N!}$, and so for large $N$ appear to be analytically and numerically intractable. Our method is based on uncovering a set of approximate symmetries that exist in addition to the $N$ periods. These approximate symmetries, which are exponentially close to exact, allow us to locate the minima very efficiently and accurately and to analyze other characteristics of the potential. We apply our framework to evaluate the diameters of flat regions suitable for slow-roll inflation, which unifies, corrects and extends several forms of "axion alignment" previously observed in the literature. We find that in a broad class of random theories, the potential is smooth over diameters enhanced by $N^{3/2}$ compared to the typical scale of the potential. A Mathematica implementation of our framework is available online.Comment: 68 pages, 17 figure

Understanding the Impact of Information Quality on Customer Relationship Management

Information represents a valuable firm resource. The quality of this resource can benefit or adversely impact social and/or economic outcomes within the organization. Previous studies predominately establish that a global measure of information quality has a positive relationship with the success of technology adoption. But there is limited understanding of the impact of information quality on outcomes other than technology adoption. This study investigates the multi-dimensional aspect of information quality and advances the proposition that it acts as a strategic success factor to customer relationship performance. Specifically, this study explores information as a resource for the firm and suggests that higher quality information will yield better decisions, which in turn, induces higher customer perceived relationship investment and relationship quality. This research builds upon resource based view theory to conceptualize information as a firm resource and will empirically investigate information quality as either an enhancement or impediment to organizational success of customer relationship management. Finally, this contributes to cross domain literature consisting of information systems and marketing which is currently underexplored. If organizations can identify vulnerability in the information quality structure, information can then be calibrated to reflect necessary improvements. Using a survey of 303 participants from multiple respondent groups (e.g., information producers, custodians, consumers and managers), findings suggest that information quality dimensions have different effects on perceived customer relationship management. Due to the exploratory nature of the study and complexity of the model, results were analyzed using PLS-SEM. Results of the study (1) build upon previous information systems literature to identify and analyze information quality dimensions that are a relevant consideration in today’s digital era (2) contribute to resource based view theory literature by establishing that information quality resources represent a strategic success factor to customer relationship performance, and (3) expand upon customer relationship management literature by discovering that information quality drivers distinctively impact management levels in a contrasting manner thereby effecting perceived customer relationship investment and perceived customer relationship quality. In terms of managerial implications, results provide valuable insight that information quality initiatives are a business issue worthy of recognition since the use of information is inextricably linked to performance measures. If organizations continue to struggle with information quality, the information will remain an impediment to customer relationship management success and economic performance

Prefacing Texts, Authorizing Authors, and Constructing Selves: the Preface as Autobiographical Space

The preface is a unique textual space, one that demands very particular kind of rhetoric because of its generic constraints and yet allows ample room for an author\u27s manipulation and creativity. Perhaps the best articulation of the prefaces paradoxical nature appears in Barbara Johnson\u27s playful response to Jacques Derrida\u27s Dissemination. The autobiographical details summarized here paradoxically depict Speght as the heroic defender of all people and, simultaneously, a woman who clearly knows her place. In her work on French Renaissance women writers, Anne R. Larsen reveals the value of this kind of study: Early women writers exploited the prefaces marginality and epistolarity. Early modern women writers were similarly able to capitalize on the prefaces traditional epistolarity, for prefatory texts are always addressed to a reader whether known or unknown, general or specific, singular or plural and sometimes actually take the form of an epistolary dedication. The advent of the female writer in English literary history is complicated, based on numerous interconnected factors