Leakage currents limit the operation of high performance type II InAs/GaSb superlattice photodiode technology. Surface leakage current becomes a dominant, limiting factor to the ideal performance of a photodiode, especially at the scale of a focal plane array pixel (< 25 µm), and must be addressed. A reduction of the...
During movement, the dendrites of spinal motoneurons receive steady excitatory and inhibitory synaptic input from supraspinal sources, interneurons, and sensory afferents. Motoneurons also have dendritic voltage sensitive ion channels. Most notable is a persistent inward current (PIC), which can enhance the amplitude of synaptic input by several fold. PICs are...
Filopodia play a central role in proper cell navigation; they extend from the cell surface and scan the local environment to guide the cell to its proper destination. These dynamic events require precise mechanisms for the turnover of key molecules which determine the morphology of filopodia. As of yet, such...
Chapter 1 describes the homopolymerization of styrene and the copolymerization of ethylene and styrenic comonomers mediated by the single-site bimetallic "constrained geometry catalysts" (CGCs), (µ-CH2CH2-3,3'){(η5-indenyl)[1-Me2Si(tBuN)](TiMe2)}2 [EBICGC(TiMe2)2; Ti2], (µ-CH2CH2-3,3'){(η5-indenyl)[1-Me2Si(tBuN)](ZrMe2)}2 [EBICGC(ZrMe2)2; Zr2], (µ-CH2-3,3'){(η5-indenyl)[1-Me2Si(tBuN)](TiMe2)}2 [MBICGC(TiMe2)2; C1-Ti2], and (µ-CH2-3,3'){(η5-indenyl)[1-Me2Si(tBuN)](ZrMe2)}2 [MBICGC(ZrMe2)2; C1-Zr2], in combination with the borate activator/cocatalyst Ph3C+B(C6F5)4- (B1). Under identical styrene homopolymerization conditions,...
Influenza virus assembly and budding is a complex process involving the organization of viral membrane proteins on the cell surface, incorporation of the segmented RNA genome, and formation of viral particles that must bud from the cell by pinching off from the plasma membrane. Interactions between the soluble influenza virus...
Metal nanoparticles in polymeric matrices are of particular scientific interest due to their useful ability to self-assemble into complex nanocomposites. Recent examples involve using ultrathin diblock copolymers coupled with metal nanoparticles in the fabrication of novel electronic, magnetic and photonic devices. As this ordering process takes place far from equilibrium...
Short-range stiffness (SRS) of a skeletal muscle describes the muscle's capability to resist external perturbations before the nervous system can intervene. Knowledge of the SRS of individual muscles is critical in understanding their contributions to single joint stiffness and whole limb stability. While the dependence of SRS on muscle force...
Two main topics are addressed in this dissertation: (1) adhesion in hydrogels; (2) interfacial interactions between model glassy polymers. A self-assembly technique for the formation of hydrogels from acrylic triblock copolymer solutions was developed, based on vapor phase solvent exchange. Structure formation in the gels was characterized by small angle...
In urban areas, an accurate evaluation of ground deformations from various construction activities requires one to properly consider both the probable ground strain level under expected working conditions and the recent stress history of the soil. For well-designed projects, the levels of ground strains typically are less than 0.5%, emphasizing...
Upward influence is an important vehicle for employee participation in work and decision-making. Research suggests that the forms and success of upward influence vary according to agent attributes, the supervisor-employee relationship, and the work context (Waldron, 1999; Wilson, 2002). Unexamined within this array are employee attempts at shaping their own...
Multi-hop wireless networks hold promise for increasing network capacity, lowering power requirements, and improving coverage over traditional cellular networks. However, their widespread adoption is hampered by challenges that include: 1) unreliable and complex routing protocols due to the transient nature of wireless nodes, 2) difficulties in guaranteeing quality of service...
Metal nanoprisms are a novel class of anisotropic nanomaterials with unique optical properties dependent on their size, shape, and composition. Silver nanoprisms are of particular interest because their surface plasmon resonance bands are readily tunable in the visible and near-IR region. The objectives of this thesis research focus on photochemical...
A novel cryogenic variable temperature UHV STM has been constructed and utilized to investigate the dynamical behavior of isolated organic molecules covalently bound to silicon surfaces.
The microscope can be operated from 8-300 K, and exhibits extremely low drift rates. A new design has been implemented for the rails (used...
This dissertation demonstrates how self-assembly can direct nanoscale ordering and optimize electronic properties of organic semiconductors, as well as organic-inorganic hybrids. In excitonic solar cells, controlling the ordering and interfaces between electron-transporting (n-type) and hole-transporting (p-type) domains is crucial. In addressing this challenge, hybrid nanostructures were designed by mineralization of...
This dissertation, "Myth and the Modern Problem: Mythic Thinking in Twentieth-Century Britain," argues that a widespread phenomenon best described as "mythic thinking" emerged in the early twentieth century as way for a variety of thinkers and key cultural groups to frame and articulate their anxieties about, and their responses to,...
IL-6 is a pleiotropic cytokine involved in both immune and non-immune functions. In the immune system, IL-6 induces terminal differentiation of B cells into plasma cells, thereby promoting antibody production. IL-6 stimulates growth of T cells by enhancing the expression of the IL-2 receptor, and IL-6 also causes differentiation of...
Granular matter and living cells represent two extremes of what have come to be regarded as complex systems - systems characterized by a richness in global behavior that is not easily deduced from the interactions of their individual parts, even when those interactions are simple and well understood. On the...
Actin polymerization is responsible for the protrusion of filopodia and lamellipodia in immune, cancer, and other motile cells, as well as for propulsion of some intra cellular pathogens. Protrusion of a lamellipodium by the very filaments supporting the membrane load operates by the Brownian ratchet mechanism, with overall organization governed...
A primary limitation of non-viral gene therapy is the low level of expression achieved. One of the reasons that higher expression is not achieved is that there are many physical obstacles that prevent the DNA from reaching the nucleus to be expressed. A plasmid must cross the cell membrane, traverse...
On average, homosexual people are more gender nonconforming than heterosexual people. They also show increased distress, possibly due to their stigmatized minority status. Not surprisingly, gender nonconformity and psychological distress may be related, particularly in homosexual men (e.g., Skidmore, Linsenmeier, & Bailey, 2006), although the mechanisms explaining this relationship have...
A study of the optical properties and superconductivity in semiconductors is presented using the highly precise all-electron full-potential linearized augmented plane wave (FLAPW) density functional calculations.
Optical properties [$\varepsilon(\omega)$,$n(\omega)$,$k(\omega)$,$R(\omega)$ and $\alpha(\omega)$] of some III-V semiconductors [InAs, InSb, GaSb, and AlSb] and their critical point (CP) energies, are calculated from the...
In the same way that a sculptor shapes a block of stone to reveal the ideal form within, one's relationship partner can help one to become more like one's ideal self (Drigotas, Rusbult, Wieselquist, & Whitton, 1999). This interpersonal process is called "the Michelangelo phenomenon." The current research examines whether...
The perinucleolar compartment is a nuclear substructure that is associated with, but structurally distinct from the nucleolus. Previous studies have shown that the PNC preferentially forms in cancer cells and PNC prevalence (% of non-mitotic and non-apoptotic cells in a population with one or more PNC) is a prognostic in...
We can represent many real-world data sets as data streams and/or high-dimensional data. Major stock market such as New York Stock Exchange (NYSE) trades more than 8000 financial products daily, which generates massive trading time series in the form of data streams. NetFlow and DNS querying data generated by real-time...
In three essays, this dissertation examined the associations between child characteristics, interparental discord and various aspects of child development and physiological functioning. In the first essay, using longitudinal, nationally representative data on infants and their families from the early childhood longitudinal study (ECLS-B), results revealed small, but significant associations between...
This dissertation aims at contributing to the literature of organizational learning and organizational change. More specifically, this dissertation focuses on three fundamental issues of exploitation and exploration: the relationship between exploitation and exploration, the balance of exploitation and exploration, and the performance implications of exploitation and exploration. This dissertation comprises...
Cellular interactions are important for the development and maintenance of tissue structural integrity. In the developing neuroepithelium, the adherens junction proteins, N-cadherin and β-catenin, are highly enriched at the apical surface of the proliferative ventricular zone and have been suggested to have critical functions in ensuring the proper development of...
This dissertation is a textual history of Thomas Paine's Common Sense and the American independence movement during the first half of 1776. The study uses the methodologies and vocabularies of rhetorical studies, early modern history, and political theory to analyze the 180-degree turn in colonial public opinion away from a...
Humans routinely answer questions, make decisions, and provide explanations in the face of incomplete knowledge and time constraints. From everyday questions like "What will it cost to take that vacation?" to policy questions like "How can a carbon taxing scheme affect climate change?" we often do not have all the...
Drawing on seven years of ethnographic fieldwork, as well as interviews, crime statistics, and census data, this study documents the demolition and redevelopment of a predominately African-American housing development in Chicago. I describe how living in a hypersegregated, high crime neighborhood affects the way residents use, affectively feel, and navigate...
The prediction of multicomponent adsorption equilibria from pure component data alone has been an active research area for over forty years. The Ideal Adsorbed Solution theory (IAS) has been the standard method of doing so, but contains an embedded assumption of Langmuir mixing. This assumption causes its predictions to be...
In the first chapter of my dissertation, I study the effects of an exogenous increase in government spending in models incorporating price and wage nominal rigidities. I find that the effects of price stickiness on the output multiplier depend crucially on the behavior of the monetary authority. If the monetary...
The recent tightening of permissible NOx release from diesel-powered engines has intensified the search for a catalytic system that can effectively remove NOx under challenging diesel exhaust conditions. Hydrogen-assisted selective catalytic reduction (H2-SCR) using supported palladium catalysts offers significant promise for lean NOx treatment due to its high activity at...
Conjugated organic molecules and polymers hold significant promise for use as active materials in electronic devices. Employing such "soft" materials can decrease cost of device fabrication, while enabling unique properties such as mechanical flexibility, large-area coverage, and highly tunable materials properties. A primary roadblock to the realization of this dream...
The kinetics of nanoscale Cu-rich precipitates of multicomponent concentrated steels has been investigated utilizing primarily APT and supplemented with a synchrotron radiation experiment, first-principles calculations, Thermo-Calc study, and CTEM (at the longest aging time). Results on mechanical properties and microstructure at a greater length scale are also presented. The studied...
The neurotropic alphaherpesviruses infect and spread trans-synaptically within the vertebrate nervous system. Recurrent diseases are often manifested at the periphery of the host organism but occasional dissemination of the virus to the brain results in fatal encephalitis. Interactions between viral and host cellular proteins are integral to the success of...
This dissertation combines critical ethnography, critical performance and historical analysis to examine three Trinidadian dance companies - Malick Folk Performing Company, Shiv Shakti Dance Company, and Noble Douglas Dance Company Inc. - asking how each choreographs Trinidadian discourses of race/ethnicity, class and national belonging through its own uniquely crafted embodied...
The addition of nanoparticles into polymer materials has been observed to dramatically change the mechanical, thermal, electrical, and diffusion properties of the host polymers, promising a novel class of polymer matrix composite materials with superior properties and added functionalities that are ideal candidates in many applications, including aerospace, automobile, medical...
The work presented in this dissertation focuses on ceramic anode materials for solid oxide fuel cells (SOFCs). The primary goal was to characterize the anode and relate the electrochemical behavior to the microstructure. The anode that was most extensively studied in this work was a composite of Gd0.10Ce0.90O1.95 (GDC) and...
Two experimental methods have been developed to induce flexural waves in concrete piles for which a portion of the shaft is accessible, and the test results were compared to theoretical solutions of flexural guided wave propagation. The pile response is measured and the results are analyzed to compute the group...
The important application for the infrared photodetectors is mainly thermal imaging by focal plane arrays (FPAs) for military and commercial purposes. So far, most mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) FPAs are based either on HgCdTe (MCT) or quantum well infrared photodetectors (QWIPs). Even though those technologies are well...
Chemical vapor deposition (CVD) is a well-developed technique for growing thin films of a wide variety of materials, which relies on the development of new and better performing metal-organic precursors. To this end, three studies have been conducted into the compatibility of sulfur and phosphine containing ligands with low- and...
This thesis summarizes our research efforts on the application of the nano-structured anodic aluminum oxide (AAO) membrane in heterogeneous catalysis. Procedures for growing the AAO membrane in the center of an aluminum disc have been developed by appropriately masking the disk's perimeter during the anodization and etching steps. The remaining...
Metallic nanostructures are able to confine and manipulate electromagnetic fields because light can couple to free electron oscillations called surface plasmons (SPs). These plasmons exist on metal surfaces as localized (short-range) or as propagating (long-range) modes depending upon the size and geometry of the nanostructure. This dichotomy is primarily an...
This thesis investigates singlet exciton fission, a physical process that converts one singlet exciton to a pair of triplet excitons. Singlet fission was discovered nearly forty years ago, but the mechanism for this process is still not well understood. Recent work has suggested that singlet fission may be capable of...
In this research, the optical and electrical properties of graphene-based materials are investigated. In particular, "graphene oxide", which is an individual layer of graphite oxide, and its chemically reduced form, is probed in terms of its properties, and the properties of graphene oxide and chemically modified graphene oxide are compared...
This thesis attempts a combined theoretical/experimental investigation of two fundamental scaling laws in charge transfer reactions: how the rate of those reactions varies as a function of distance between an electron donor and an electron acceptor and how the rate varies as a function of the number of distinct pathways...
The Satake category is the category of perverse sheaves on the affine Grassmannian of a complex reductive group G. The global cohomology functor induces a tensor equivalence between the Satake category and the category of finite-dimensional representations of the split form of the Langlands dual group of G. We give...
The task of designing porous materials for use in specific applications requires a detailed understanding of the adsorption process and how adsorption is affected by material properties. Applications of interest include maximizing gravimetric or volumetric adsorption capacity for hydrogen and carbon dioxide and increasing the selectivity for carbon dioxide in...
Two subjects are the focus of this dissertation: Au/TiO2 catalyst used for oxidation of CO at low temperature and siloxane nanocages, a novel material (~2nm) recently developed in our group
While bulk gold is chemically inert, gold supported as nanoparticles is remarkably active for the oxidation of carbon monoxide at...