In response to construction activities and loads from permanent structures, soil generally is subjected to a variety of loading modes varying both in time and location. It also has been increasingly appreciated that the strains around well-designed foundations, excavations and tunnels are mostly small, with soil responses at this strain...
><p><em>Vibrio cholerae</em>, the causative agent of the severe diarrheal disease cholera, secretes several "accessory" toxins including RTX toxin, which causes cross-linking of the actin cytoskeleton. The rtx locus of <em>V. cholerae</em> is located adjacent to the integrated CTX? prophage. The RTX toxin itself is encoded by the <em>rtxA</em> gene found...
The rapid growth of digital imaging technology and the accumulation of large collections of digital images has created the need for efficient and intelligent schemes for content-based image retrieval. Our goal is to organize the contents semantically, according to meaningful categories. We present a new approach for semantic classification that...
Two new strategies have been developed to accomplish direct nucleophilic acylation reactions. In the first approach, acylsilanes are added to various electrophiles using N-heterocyclic carbenes as catalysts. The second method utilizes O-silyl thiazolium carbinols as stoichiometric acyl anion precursors to afford acylated products under mild reaction conditions.
N-heterocyclic carbenes generated...
Flexibility can be created in manufacturing and service operations by using multipurpose production sources such as cross-trained labor and flexible machines/factories. We focus on control and design issues in systems with flexible resources. In Chapter 2, we consider optimal scheduling of a fully cross-trained server in a finite-population queueing system...
The Galactic center (GC) is a dense and chaotic region filled with unusual sources, such as intense star forming regions, dense star clusters, nonthermal radio filaments, and a massive black hole. The proximity of the GC region makes it an ideal place to study the unusual processes that tend to...
The electronic transport and magnetoresistive properties of the ferromagnetic semiconductor In1-xMnxAs were investigated in order to determine the nature of the transport and ferromagnetism in the films. p-InMnAs/n-InAs and metal/oxide/InMnAs heterojunctions were fabricated and characterized to elucidate the transport and magnetoresistance mechanisms at these technologically important interfaces.
The electronic transport...
Neurofibrillary tangle (NFT) formation in Alzheimer's disease (AD) and tauopathies occurs when tau protein adopts secondary structure and self-aggregates within neurons. Accompanying NFT maturation are post-translational modifications to tau; hyperphosphorylation, truncation and conformational changes occur in a highly sequential manner. In contrast, granulovacuolar degeneration bodies (GVDs) are a second type...
Biomorphic silicon carbide (bioSiC) is a novel porous ceramic material derived directly from wood precursors. This material is fabricated by pyrolysis of a natural wood precursor in an inert atmosphere leaving an amorphous carbon scaffold. The amorphous carbon is infiltrated with molten Si in vacuum at elevated temperature, which reacts...
Stem cells show great promise as cellular replacement and drug delivery therapies for a number of neurological disorders. This dissertation examines embryonic and adult types of stem cells, their plasticity, and mechanisms governing their development (Chapters 1-5). Our studies illustrate that leukemia inhibitory factor (LIF) signaling and bone morphogenetic protein...
Solid oxide fuel cells (SOFCs), renowned for their high electrical generation efficiency with low pollutant production, are promising for reducing global energy and environmental concerns. However, there are major barriers for SOFC commercialization. A primary challenge is reducing the capital cost of SOFC power plants to levels that can compete...
Fundamental investigations on the origins of friction at the nanoscale were carried out using both theoretical and experimental approaches. A model was developed that analytically solves for friction by the motion of dislocations at atomically flat crystalline interfaces. It combines known concepts from dislocation drag, grain boundary theory, and contact...
The role that spinal motion plays during ambulation is not clearly understood. Little in vivo regional spinal motion data exists in the literature with regard to walking and most gait models disregard the upper body altogether, or regard it as a single rigid structure. This study aims to increase understanding...
This dissertation is a multi-method study of the relocation process under the Chicago Housing Authority's implementation of federal redevelopment policies intended to decrease the racial and economic isolation of public housing tenants. It combines quantitative and spatial analysis of program administrative data, interviews with 'expert respondents,' and qualitative semi-structured interviews...
Three critical problem areas pertinent to the development of precision high-speed spindles for meso-scale machine tools (mMTs), driven by air turbines, constitute the focus of this work. These are the development of the spindle, of a new tool clamping device, and of a measurement system for spindle error motions.
For...
The work presented here represents a series of research projects that are unified in their goal: to use volume holographic gratings to enhance traditional signal processing applications in ways that would otherwise not be possible. To this end, we have completed work that can be classified into four different projects....
Arsenic trioxide (As<sub>2</sub>0<sub>3</sub>) is an arsenic-derivative that exhibits potent growth inhibitory effects against malignant cells. The remarkable antitumor effects of As<sub>2</sub>0<sub>3</sub> in vitro and in vivo have prompted the development of various clinical trials that established its activity in acute promyelocytic leukemia (APL). As<sub>2</sub>0<sub>3</sub> is part of the standard treatment...
Most women diagnosed with epithelial ovarian carcinoma (EOC) initially present with metastases, but little is known about the regulation of ovarian tumor cell dissemination by the tumor microenvironment. Because ovarian cancer cell dissemination is mostly limited to the peritoneal cavity and often results in the accumulation of malignant ascites, the...
Two-year colleges are a critical site for the expansion of educational opportunity in the United States. They enroll nearly half of all postsecondary students and are a gateway to higher education for low-income, non-traditional, racial and ethnic minority, and first-generation college students. Degree completion rates in the two-year sector are...
Spectral elements are p-type element which can provide better accuracy
and faster convergence. However, applications of these elements make
conformation to discontinuities in the function or its derivative
difficult. The eXtended Finite Element Method (XFEM) recently
developed at Northwestern University can easily treat the arbitrarily
aligned discontinuities, i.e. independent of...
Experimental and numerical studies of lasing in multiple light scattering media with gain are presented in this thesis. Depending on the dielectric constant spatial distribution is random or periodic, two different kinds of lasers are discussed: the random laser and the photonic crystal laser. This thesis, therefore, is divided into...
The optical and magneto-optical properties of the ferromagnetic semiconductors, InMnAs and its alloy InMnAsP were investigated to determine the band structure and nature of the ferromagnetism in these materials. Alloys were grown by metal-organic vapor phase epitaxy. Infrared absorption of InMnAs was investigated to determine the presence and properties of...
The abundance and breadth of condition data generated by advanced inspection technologies have increased the frequency and accuracy of data collection, which is not exploited by the existing performance models. Moreover, simultaneity of deterioration and maintenance causes difficulty of estimating effectiveness of maintenance activities for existing performance models. To address...
The purpose of this dissertation study was to build on scholarly work in the area of critical mathematics by such scholars as Gutstein (2003) and Gutierrez (2002). Critical pedagogy is designed to foster political agency and critical consciousness in students (Freire, 1971). That is the aim of critical mathematics in...
The goal of this study was to investigate the properties of the retinal ganglion cell receptive field at low light levels. There has been considerable interest in whether the surround of a ganglion cell receptive field disappears and the center expands in size under scotopic conditions. The previous data from...
Ceramic matrix composites are known for their low density, high strength and high stiffness, but lower fracture toughness compared to metal matrix composites. The addition of a reinforcing agent within the matrix can increase the toughness of the composite via many strain energy absorption mechanisms such as plastic deformation. This...
I examine horizontally differentiated firms in three different contexts. First, I look at an industry where firms can develop self-customizable products -- products which appeal to different consumers for different reasons. This addition results in an unexpected conclusion that sometimes more differentiated firms can end up with lower profits than...
The goal of this dissertation was to examine the influence of motivational incentives on visual spatial attention in patients with probable Alzheimer's Disease (PRAD), patients with mild cognitive impairment (MCI) and healthy age-matched control subjects (EC). Specifically, I compared the ability of monetary incentives to influence behavioral and neural performance...
The motion of thin drops under the effects of surfactants and gravity is studied. First, the effects of surfactant and temperature on the spreading of a viscous droplet are considered. Lubrication theory is used to develop a two-dimensional model for the evolution of the droplet. The surfactant is assumed to...
This dissertation studies the organizing local approach to labor renewal, a union model centered on organizing new workers. I examine the role of activists and what motivates them to participate beyond a rational evaluation of gains. Additionally, I establish the conditions for successful union reform, specifically, how to overcome inertial...
Should the government subsidize entry to promote competition? In theory, free entry does not guarantee the socially optimum number of entrants. In differentiated product markets, free entry can result either in excessive or insufficient entry. Quantifying this inefficiency and identifying the optimal subsidy level require an empirical framework that combines...
Wave propagation at the bottom of the electromagnetic spectrum (below 300 kHz) in the Earth-ionosphere system is a problem having a rich history of theoretical investigation extending over many decades. Propagation within this system involves complex interactions of electromagnetic waves with the lithosphere, oceans, and ionosphere, leading to resonances that...
Substrate-mediated delivery involves the immobilization of DNA, complexed with nonviral vectors, to a biomaterial or surface that supports cell adhesion. Cells cultured on the substrate are exposed to elevated DNA concentrations within the local microenvironment, which enhances transfection. As surface properties are critical to this delivery approach, self-assembled monolayers (SAMs)...
Autoxidation is a primary route by which lubricants in working conditions undergo degradation. Degraded lubricants, if not replaced periodically, contribute to increased wear and product failure. Experimental studies of lubricant degradation have yielded useful results but have left important questions unanswered. While many computational studies of degradation have been carried...
We compute Lawson homology groups and semi-topological K-theory for certain "degenerate" varieties. "Degenerate" varieties are those smooth complex projective varieties whose zero cycles are supported on a proper subvariety. Rationally connected varieties are examples of such varieties. Our main method of study makes use of a technique of Bloch and...
The study of III-Nitride based optoelectronics devices is a maturing field, but there are still many underdeveloped areas in which to make a contribution of new and original research. This work specifically targets the goals of realizing high-efficiency back-illuminated solar-blind photodetectors, solar-blind focal plane arrays, and visible- and solar-blind Avalanche...
Recent work exploring children's verb learning in the laboratory has generated some interesting contradictions. Some studies have found that children as old as 4 years old are unable to reliably map a novel verb to an action (e.g., Kersten & Smith, 2002; Imai, Haryu, & Okada, 2005), even though much...
In mammalian development, cell specification and organogenesis are achieved by the regulated expression and repression of specific subsets of genes. The anterior pituitary gland, comprised of five cell types that arise from a common precursor, is an excellent model system for understanding these developmental processes. Examination of factors regulating transcription...
In this dissertation we analyze, using standard formal imperfect competition models from the literature, two central public policy issues in the deregulated wholesale electricity markets. The first issue is the regulatory rules around generator ownership of transmission companies or transmission rights in general. The second issue we look into is...
Social networks play an important role in the labor market. Various surveys document that 30-60% of jobs are found through friends or relatives. To better understand how networks operate in the labor market, I examine how networks that were formed involuntarily as a result of the American Civil War and...
This dissertation explains why some rebel groups act in a highly coercive fashion toward local populations, only to shift to increasingly contractual behavior, and why other groups that share similar circumstances evolve in the opposite direction. Drawing upon fieldwork in Sudan, Iraq, Turkey, and Colombia, this study examines three rebel...
This dissertation investigates the ways in which poetry encourages visual images in the reader. This investigation breaks new ground, for in the wake of behaviorist psychology and the linguistic turn in literary theory, literary critics have ignored and often spurned the visual imagination. The project uses Imagist poetry as a...
Information processing in the striatum is crucial for voluntary movement control and associative learning and in the normal condition is subject to balanced dopaminergic and cholinergic modulation. However, in Parkinson's disease (PD) striatal dopamine (DA) level falls because of degeneration of DA neurons in the substantia nigra pars compacta and...