VictorJuiz/thesis huggingface dataset:
The Geographic Concentration of Retail Stores: Trends and Determinants

This dissertation mainly assesses the relative importance of two mechanisms–consumer searching and cost sharing for the spatial concentration of retail stores. I first present a simple model of firms’ location choice and consumers’ shopping destination choice. This model shows how both mechanisms promote the agglomeration of retail firms. The degree of retail agglomeration, measured by Ripley’s K function, increases with the importance of consumer searching and with the benefits from scale economy in intermediate inputs such as advertisements and delivery services. I then present stylized facts based on industry agglomeration. Using the 2012 National Establishment Time-Series database, I calculate Ripley’s K function and Ellison-Glaeser index that measure the degree of agglomeration for each CBSA-NAICS industry-year pair in the U.S. from 1992 to 2012. The estimated Ripley’s K values show that the overall degree of retail agglomeration has been decreasing since 1992. Also, I find much inconsistency between the estimated Ripley’s K and Eillson-Glaeser indices. Using the variation in the percentage of population that use Internet across regions and in the Internet sales share across retailing industries, I find that a 10 percentage points increases in the Internet use percentage and in the Internet sales share is associated with a 3.1-3.5 decrease and a 9.5-10.8 decrease in the calculated Ripley’s K value. This provides suggestive evidence of the role consumer searching plays in promoting retail agglomeration since Internet decreases the importance of consumer searching in person. A difference-in-differences analysis shows that industries easy to make comparison shopping online experience a greater decrease in the degree of agglomeration by 6.8-12.6 before and after 2000. Last, I use a triple-difference approach based on the bankruptcy of chain stores like Borders and Circuit City to distinguish the effects of consumer searching and cost sharing. The estimation results for various types of chain stores using sales, employment size, the probability of closure, and the birth of new stores as dependent variables are mixed. Consumer searching alone cannot well explain retail agglomeration; however, there is little evidence of the contribution of the cost sharing mechanism to retail agglomeration.

Advisor: Deakin, Elizabeth
Joint Optimization of Pavement Management and Reconstruction Policies for Segment and System Problems

This dissertation presents a methodology for the joint optimization of a variety of pavement construction and management activities for segment and system problems under multiple budget constraints. The objective of pavement management is to minimize the total discounted life time costs for the agency and the highway users by finding optimal policies. The scope of the dissertation is focused on continuous time and continuous state formulations of pavement condition. We use a history-dependent pavement deterioration model to account for the influence of history on the deterioration rate./nThree topics, representing different aspects of the problem are covered in the dissertation. In the first part, the subject is the joint optimization of pavement design, maintenance and rehabilitation (M&R) strategies for the segment-level problem. A combination of analytical and numerical tools is proposed to solve the problem. In the second part of the dissertation, we present a methodology for the joint optimization of pavement maintenance, rehabilitation and reconstruction (MR&R) activities for the segment-level problem. The majority of existing Pavement Management Systems (PMS) do not optimize reconstruction jointly with maintenance and rehabilitation policies. We show that not accounting for reconstruction in maintenance and rehabilitation planning results in suboptimal policies for pavements undergoing cumulative damage in the underlying layers (base, sub-base or subgrade). We propose dynamic programming solutions using an augmented state which includes current surface condition and age. In the third part, we propose a methodology for the joint optimization of rehabilitation and reconstruction activities for heterogeneous pavement systems under multiple budget constraints. Within a bottom-up solution approach, Genetic Algorithm (GA) is adopted. The complexity of the algorithm is polynomial in the size of the system and the policy-related parameters.

Advisor: Madanat, Samer M
Technologies of Expression: Poetic Inscriptions in Postwar America

My dissertation argues that mid-twentieth-century American poetry was part of a multi-disciplinary effort to renegotiate the traditional boundary between living beings and manufactured forms. I depart from the prevailing understanding that postwar American poetry reprises Romantic “organic form,” claiming to the contrary that postwar poets cast the literary text as an inorganic but nevertheless animate organization—an exteriorized correlate of the poet’s vital processes. Instead of invoking the analogy between organic life and textual form as a way of naturalizing literary production, postwar poets endeavored to extend the category of life to man-made forms. Their effort to animate the artificial space of the poetic text is, I contend, a major contribution to a central problem of the postwar decades: namely, how to rethink nature and technology, organism and machine as non-oppositional pairings. I explore this problem as it unfolded across different discursive and creative practices—from the trans-disciplinary science of cybernetics, which modeled machinic intelligence after recursive, biological processes (rather than the abstract, representational capacities of the mind) to the poetics of the Projectivist and New York schools, which reconstituted the temporalities and rhythms proper to bodily life as graphic-verbal patterns on paper. Throughout, I argue that American poets and scientists, far from representing two antithetical cultures, were mutually invested in modeling life inorganically, that is, in designing dynamic, self-organizing configurations, and thereby upending the Aristotelian conception of the technical object as matter devoid of self-formative power.

Advisor: Altieri, Charles
Fretting Wear Mechanisms in A216 Plain Carbon Steel

The subsurface and surface microstructures during pin-on-disk fretting wear of A216 steel disks under various loading conditions and times are investigated. The corresponding pins are fabricated from 410 stainless steel to simulate in-service conditions found in such engineering components as the Siemens W501FD engine row-2 diaphragm of a Siemens turbine engine, which is known to be prone to failure by fretting wear. Loading conditions range from 2N to 15N and times from 1 hour to a maximum of 69 hours, when steady state is confirmed. Wear track depth is quantitatively determined by optical profilometry, and found to range from 3 to 11 microns dependent upon load. Wear depth increases from 2N to 10N load, but decreases when increased to 15N load, due to heavier transfer of pin material to disk, as can be seen by EDS images of chromium transfer on A216 disk. Microstructures are evaluated by transmission electron microscopy of samples prepared by focused ion beam machining to pinpoint wear tracks and expose them in cross-section. EDS is used, in conjunction with TEM, to elucidate primary wear mechanisms at each stage of fretting wear. Microstructures in the subsurface of wear tracks are found to be heavily dislocated and layered, features that vary with both applied load and time. The microstructure eventually evolves into stable dislocation cells with cell walls aligned parallel to the surface. Penetration depth of the damaged layers increases with applied load, associated with a non-uniform maximum shear stress distribution that varies with depth. Primary oxide appears to evolve from Fe2O3 to Fe3O4, with increasing fretting time, leading to a uniform oxide on the surface of the A216 disk. Oxidation rate may be increased with the evolution of this subsurface dislocation cell structure. It is concluded that fretting wear failure is likely associated with a synergy between oxidative wear and crack initiation and propagation along dislocation cell walls under high strain accumulation at sufficiently high loads or sufficiently long times.

Advisor: Gronsky, Ronald
Komvopoulos, Kyriakos
Racial Disparities in Child Welfare and Infant Health: An Examination at the County-Level

The goal of this study is to contribute to an important gap in research on Black infants in the child welfare system. Black infants represent a high-risk population at the center of both health and child welfare disparities. Using both the child welfare and public health disparities knowledge base as a foundation, this research aims to better understand how health, when analyzed as an attribute of place, may function as an ecological risk or protective factor by influencing patterns of child welfare outcomes among infants. Birth indicators are well established as individual-level risk factors for child maltreatment, yet whether this relationship exists at the county-level and its potential impact on current levels of disparity among infants has not been explored. County-level studies in child welfare can contribute to the scope of research needed to answer imperative questions regarding how local community factors, social service system characteristics, and service availability may influence disparate outcomes across geographies. As such, this study 1) examines variation and changes over time in levels of low birth weight and infant allegation disparity across California counties 2) uses Poisson regression models to determine whether low birth weight is associated with increased incidence of infant maltreatment allegations and 3) examines the relationship between a county’s rate of low birth weight disparity and its rate of infant allegation disparity./nResults of this study identified wide ranges of maltreatment allegation and disparity rates across California counties. A number of statistically significant differences in mean infant allegation disparity rates were observed for counties that were grouped and compared according to select contextual measures of interest. Findings from the Poisson regression modeling indicated that the model for Black infants was the only case in which county low birth weight was a significant predictor of maltreatment allegations. The effect of county low birth weight on maltreatment allegations for racial groups combined and for White infants were negligible and did not reach statistical significance. Results support the case for multi-level studies that incorporate more sophisticated measures of ecological health to explore the potential relationships between developmentally relevant, health-related factors and child welfare outcomes.

Advisor: Snowden, Lonnie
Provisional Reconstructions: Geo-Histories of Infrastructure and Agrarian Configuration in Malanje, Angola

Fueled by a massive offshore deep-water oil boom, Angola has since the end of war in 2002 undertaken a huge, complex, and contradictory national reconstruction program whose character and dynamics have yet to be carefully studied and analyzed. What explains the patterns of such projects, who is benefitting from them, and how? The dissertation is grounded in the specific dynamics of cassava production, processing and marketing in two villages in Western Malanje Province in north central Angola. The ways in which Western Malanje’s cassava farmers’ livelihoods are shaped by transport, marketing, and an overall agrarian configuration illustrate how contemporary reconstruction – in the context of an offshore oil boom – has occurred through the specific conjunctures of multiple geo-historical processes associated with settler colonialism, protracted war, and leveraged liberalization. Such an explanation contrasts with previous more narrow emphases on elite enrichment and domination through control of external trade. Infrastructure projects are occurring as part of an agrarian configuration in which patterns of land, roads, and markets have emerged through recursive relations, and which is characterized by concentration, hierarchy and fragmentation.

Advisor: Watts, Michael J
Microscale Simulation of the Mechanical and Electromagnetic Behavior of Textiles

A computational framework for assisting in the development of novel textiles is pre- sented. Electronic textiles are key in the rapidly growing field of wearable electronics for both consumer and military uses. Fabric actuators can be made with electrically function- alized fabrics that can be manipulated by externally applied electromagnetic fields when electric current is run through the yarns of the fabric. There are two main challenges to the modeling of electronic textiles: the discretization of the textile microstructure and the interaction between electromagnetic and mechanical fields./nThe fully coupled mechanical, thermal, and electromagnetic behavior of a textile can be simulated in the context of quasistatic material property prediction and dynamic analysis of high speed impacts. Director-based beam formulations are used to discretize the fabric at the level of individual fibrils. Instead of solving Maxwell’s equations in full detail, a quasistatic approximation is used to solve the electric potential in the presence of a moving material medium. While this formulation alleviates the spatial and temporal discretization restrictions, the coupled problem is a Differential Algebraic Equation requiring special treat- ment. Diagonally Implicit Runge-Kutta methods using a monolithic Newton’s method solver are used to integrate the resulting nonlinear coupled systems in time. The finite element model is implemented using the open source package FEniCS. Contact integrals were added into the FEniCS framework so that multiphysics contact laws can be incorporated in the same framework, leveraging the code generation and automatic differentiation capabilities of FEniCS to produce the tangents needed by the implicit solution method./nThe nonlinear deformation of a current-carrying elastic string is solved analytically. The computational model for a single fibril is validated using by comparison the static problem and verifying the convergence orders for higher-order finite element basis functions. The time stepping method for the fully coupled differential algebraic equation is verified using the convergence orders of the higher-order Runge-Kutta methods. The computational model is used to construct and determine the mechanical, thermal, and electrical properties of representative volume elements of textiles using dynamic relaxation to solve the decoupled fields in a static context. The dynamic deformation of a small electronic textile under various orientations of magnetic fields is solved. An electromagnetically-enhanced textile armor system impacted by a projectile is simulated.

Advisor: Zohdi, Tarek I
Protective Normalcy: Experience and Management of Stigma in LGBT Families with Children.

This dissertation explores explores how LGBT families with children experience and manage stigma in a sociohistorical moment marked by tensions between growing legal recognition and cultural acceptance and the persisting realities of heterosexism and homophobia. Drawing on intensive interviews with LGBT identified parents from 51 families, I find that, despite parents' low reports of direct hostility and overt discrimination in their daily lives, subtle expressions of stigma continue to shape the creation and day-to-day practice of their family relations. These experiences can be broken down into two categories: (1) anticipated stigmas, or the fear that oneself or one’s family will encounter violence, discrimination, or prejudice on the basis of their LGBT identities or queer family structure in the immediate or distant future; and (2) microaggressions, or subtle forms of insults, invalidations, and modes of discrimination that are consciously and unconsciously deployed in day-to-day interactions. Building on insights from the family practices and accounts scholarship in sociology, I found that parents manage these subtle forms of stigma through a range of family practices including: methods for having children, legal interventions taken in family building, how children refer to their parents, naming children, where they live, which schools their children attend, parent volunteerism in schools, and the degree to which a family is out in public spaces. I also found that parents’ stigma management strategies varied according position in family cycle and age of children. Parents with young children engaged in stigma management for their families directly and prepared children for future discriminatory encounters. Parents with adolescent and young adult children engaged in practices that, rather than directly manage stigma, provide children with a broad range of stigma management strategies that they may deploy in their day-to-day lives. These experiences of stigma and stigma management are also heavily shaped by normative expectations of monoracial families, whiteness, middle class norms, and biogenetic ties. However, I find in many cases that parents’ investment with normative cultural beliefs to be a pragmatic one that is marked with ambivalence. It is a stigma management strategy, a form of “protective normalcy” whose practice is, at least in part, motivated by concerns of heterosexism and homophobia that their families may encounter, now and in the future. This work has important implications for developing a better understanding of the subtle stigma experiences of LGBT families and other marginalized populations, even as overt discrimination and regressive policies diminish. It also expands theoretical understandings of stigma by closely examining how individuals think about stigma in relation to time. In other words, it is not just that experiences change over time but also how present day actions are shaped by hopes, fears, and aspirations for the near and distant future.

Advisor: Johnson-Hanks, Jennifer
Ion Channel Photoswitch Reveals Crosstalk between Intact and Injured Nociceptive Neurons after Nerve Injury

The development of novel techniques utilizing the advantages of light has created an optical revolution for neuroscience research. Controlling and probing neuronal function with light has provided unprecedented insights by being able to manipulate many neurons simultaneously in intact circuits and living organisms./nIn my dissertation research, I used novel optical methods to probe the cellular permeability of sensory neuron populations. Primary nociceptive afferents detect, modulate and integrate many pain-related stimuli. Sensory information is transmitted from the periphery through the dorsal root ganglia along labeled lines coding for sensory modalities and receptive fields. Recently, our understanding of sensory processing has been expanded by the discovery of neuronal interactions both on the level of peripheral nerve endings and in the spinal cord. Here I report a crosstalk between injured and intact neuronal population after peripheral nerve injury. This communication is revealed at the somata of sensory neurons distant from the site of injury and correlates with permeability changes of both injured and intact nociceptor populations after injury. I devised a sensitive probe to measure the activity of nociceptive cells in intact tissue using a photoswitch molecule. Transient Receptor Potential (TRP) ion channel are a major class of molecular sensors detecting painful stimuli. I show that TRPA1, a member of the TRP family, is necessary for this crosstalk which is limited to petidergic, slow conducting C fibers. In addition, electrical activity of nociceptive fibers alone is sufficient to mimic similar permeability changes as nerve injury. Injury induced hyperexcitability of sensory fibers and TRP channel dysfunction have been implicated with conditions of pain hypersensitivity, chronic and neuropathic pain. I therefore propose that this crosstalk might contribute to adaptions of pain signaling in various disease states./nPhotoswitch molecules have found many experimental applications in neuroscience research. However, the exact mechanism by which they function remains unclear. Therefore, another part of my research focused on studying interactions of the photoswitchable compound QAQ with the model potassium channel Shaker. I investigated the affinity of both QAQ isomers to the open Shaker channel and surprisingly found that block is not voltage-dependent. Further, I analyzed the effects of use-dependent inhibition and report that QAQ does not associate with closed channels. However, once channels are opened, QAQ does interfere with the kinetics of the gate slowing down the closing of the channel.

Advisor: Kramer, Richard H
Infrastructures of Injury: Railway Accidents and the Remaking of Class and Gender in Mid-Nineteenth Century Britain

As steam-powered industrialization intensified in mid-nineteenth century Britain, the rate and severity of workplace injuries spiked. At the same time, a range of historical dynamics made working class people individually responsible for bearing the effects of industrial injury and carrying on in the aftermath of accidents without support from state or company. By the midcentury, railway accidents were represented as events that put on display the moral character of individual rail workers and widows, rather than — as in radical rhetorics of previous decades — the rottenness of state or company bureaucracies. Bearing injury or loss in a reserved manner came to appear as a sign of domestic virtue for working class women and men, though the proper manifestations of this idealized resilience varied by gender. Focusing on dynamics in the railway and nursing sectors, and in the sphere of reproduction, Infrastructures of Injury shows how variously situated working class subjects responded to their conditions of vulnerability over the second half of the nineteenth century. These responses ranged from individualized or family-based self-help initiatives to — beginning in the 1870s — strikes, unionization drives, and the looting of company property. Ultimately, this dissertation tells a story about how working class cultural and political practices were remade through the experience of injury and loss.

Advisor: Vernon, James
Wintroub, Michael