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...
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...
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...
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...
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...
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)...
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...
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...
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...
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...
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...
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...
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...
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...
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 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 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...
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...
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...
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...