Digital Commons Network^™

Pacemaker Heterogeneity In The Suprachiasmatic Nucleus: Origins And Network Implications, Alexis Webb

All Theses and Dissertations (ETDs)

In mammals, the suprachiasmatic nuclei: SCN) in the ventral hypothalamus function as a circadian pacemaker, controlling daily rhythms in behavior and physiology. Together the SCN contain approximately 20,000 neurons that maintain rhythms in firing rate and gene expression. Previous studies led to the assumption that single SCN neurons are capable of self-sustained circadian rhythms. Whether and which SCN neurons can maintain cell-autonomous daily oscillations has not been extensively tested. We measured PERIOD2::LUCIFERASE expression in isolated SCN neurons over multiple days to determine if all SCN neurons were circadian. We then examined neuropeptide content of the recorded neurons. We found that …

The Small Animals Of Maasai Settlements: Ethnoarchaeological Investigations Of The Commensalism Model, Lior Weissbrod

All Theses and Dissertations (ETDs)

This research was designed to test Tchernov's model of commensalism and the idea that remains of commensal species that today coexist with humans in settlement environments could be used to detect early sedentism in the archaeological record. The validity of the model has been questioned due to the lack of empirical knowledge on commensalism in a wide range of settlement environments including sedentary and more mobile ones. This study examined the commensalism model by focusing on seasonally occupied settlements of Maasai pastoralists in East Africa. Methods from ecology, ethnography, and archaeology were used to document the impact of Maasai settlements …

Abstractions And Algorithms For Control Of Extensible And Heterogeneous Virtualized Network Infrastructures, Charles Wiseman

All Theses and Dissertations (ETDs)

Virtualized network infrastructures are currently deployed in both research and commercial contexts. The complexity of the virtualization layer varies greatly in different deployments, ranging from cloud computing environments, to carrier Ethernet applications using stacked VLANs, to networking testbeds. In all of these cases, many users are sharing the resources of one provider and each user expects their resources to be isolated from all other users. There are many challenges associated with the control and management of these systems, including resource allocation and sharing, resource isolation, system security, and usability. Among the different types of virtualized infrastructures, network testbeds are of …

Structure And Function Of The Fmo Protein From The Photosynthetic Green Sulfur Bacteria, Jianzhong Wen

All Theses and Dissertations (ETDs)

The Fenna-Matthews-Olson: FMO) bacteriochlorophyll a protein has served as a model antenna system for understanding pigment-protein interaction and the energy transfer mechanism. The FMO protein has been extensively studied by a wide range of spectroscopic and theoretical techniques due to its stability, spectral resolution of pigments, water-soluble nature and availability of high-resolution structural information. A new 1.3 ├à FMO structure: PDB: 3EOJ) revealed an 8th pigment at the monomer connection region with partial occupancy. To understand the nature and stoichiometry of this new pigment, the molecular weight of the whole FMO complex was measured by the recently developed mass spectrometry: …

Frustrated Magnetism In Distorted Triangular Lattice Materials; & Extraordinary Electroconductance In Iii-V Metal Semiconductor Hybrid Structures, Jian Wu

All Theses and Dissertations (ETDs)

PART I: We have synthesized a series of spin S = 1/2 distorted triangular lattice materials Cu_2(1-x)Zn_2x(OH)₃NO₃and their long chain alkyl carboxylic group intercalated derivatives, Cu_2(1-x)Zn_2x(OH)₃(C₇H₁₅COO).mH₂O). Their structural properties, magnetic properties and specific heat have been carefully studied in this thesis. We found that antiferromagnetic-type long-range order develops in all the nitrate group compounds below the Neel temperatures T_N, which decreases with increasing Zn content. For the organic long chain intercalated samples, the temperature dependence of magnetic susceptibility …

Transient-State Kinetic Studies Of The Mechanisms Of Dna Unwinding And Translocation Of The E. Coli Recbc And Recbcd Helicases, Colin Wu

All Theses and Dissertations (ETDs)

This thesis presents mechanistic studies of the E. coli RecBC and RecBCD helicases using transient-state kinetic approaches to understand the relationship between DNA unwinding and ssDNA translocation. RecBC initiates unwinding from duplex DNA ends with pre-existing 5'-(dT)6 and 3'-(dT)6 ssDNA tails using a series of repeated rate-limiting steps with a rate of 345 ┬▒ 8 bp/sec and an average kinetic step-size of ~4 bp: 20 mM Mops-KOH, pH 7.0 at 25°C, 30 mM NaCl, 10 mM MgCl2, 5% glycerol, 1 mM 2-mercaptoethanol) while RecBCD unwinds these same DNA substrates with a rate of 745 ┬▒ 18 bp/sec using a more …

Organizational Processes Contribute To The Testing Effect In Free Recall, Franklin Zaromb

All Theses and Dissertations (ETDs)

In educational contexts, tests not only assess what students know, they can also directly improve long-term retention of subject matter relative to restudying it. More importantly, the memorial advantage of testing is not limited to select information that was tested earlier. Research has shown that testing can serve as a versatile learning tool by enhancing the long-term retention of non-tested information that is conceptually related to previously tested information; stimulating the subsequent learning of new information; and permitting better transfer of learning to new knowledge domains. We further investigated the potential benefits of testing on learning by asking whether testing …

A Free-Breathing Lung Motion Model, Tianyu Zhao

All Theses and Dissertations (ETDs)

Lung cancer has been the leading cause of cancer deaths for decades in the United States. Although radiotherapy is one of the most effective treatments, side effects from error in delivery of radiation due to organ motion during breathing remain a significant issue. To compensate the breathing motion during the treatment, a free breathing lung motion model, x= x0+αv+βf, was developed and discussed, where x is the position of a piece of tissue located at reference position x0. α is a parameter which characterizes the motion due to local air filling: motion as a function of tidal volume) and β …

Essays In Corporate Finance, Kangzhen Xie

All Theses and Dissertations (ETDs)

This dissertation studies the effects of information asymmetry, financial constraints and stock market valuation on the behavior of firms. The first essay explores the role of deal initiation and bidder asymmetry in determining the use of auction and target premia in merges and acquisitions. The second essay examines the behavior of the segments of conglomerates and single segment firms in the distressed industries. The third essay investigates the incentive of takeover arising from the temporary disparity of stock valuation. While half of all acquisition targets are sold in negotiated deals with only one buyer rather than by auction, the wealth …

Fcs Analysis Of Pore Formation By The Human Protein Bax In Lipid Membranes, Olena Ivashyna

All Theses and Dissertations (ETDs)

Bax is a pro-apoptotic member of the BCL-2 protein family and its paramount function during apoptosis is to form pores in the mitochondrial outer membrane: MOM). In a simplified apoptosis model, upon apoptotic stimulation, Bax is activated via an unresolved mechanism, translocates to the MOM, where it changes conformation, inserts into the membrane as a monomer, and finally undergoes in-membrane oligomerization to form a pore. Once the Bax pore is formed, cytochrome c and other mitochondria-resident proteins escape into the cytoplasm where they activate the cascade of caspases, which dismantle the cell. To date, the structure of the inactive cytoplasmic …

Whose Identity Is It Anyway? A Study Of The Media's Representation Of Iraq Citizens And Their Culture, Joyce L'Heureux

Open Access Master's Theses

What happens to our perceptions when provided with an invitation by news media, specifically print media, to accept what is presented as reality? Does what we read in the news media constrict our thinking and create an acceptance of the words as they are written, a type of cultural blindness to the qualities, the humanness and individuality of other cultures? Or, do we read the words on the paper and open our lens to create a greater understanding of individuals who differ from us in values, attitudes and beliefs? The truth is the same stories which provide us with an …

Relationship Between Psychosocial And Interpersonal Factors And Implicit Sex-Submission Associations In Hispanic/Latina And White Women, Myriel Rodríguez Boissén

Open Access Dissertations

The purpose of this study was to investigate implicit sex-submission associations for Hispanic /Latina and White women. Furthermore, this study examined how childhood sexual abuse, anticipated negative partner reaction-refusal, psychosexual functioning, sexual assertiveness-refusal and communication, and hyperfemininity are associated with women's implicit sex-submission associations. These interpersonal and psychosocial factors were analyzed for Hispanic/Latina and White women to help us determine if these associations are found for two different groups of women.

Previous research has demonstrated that individuals associate sex with power and aggression at an unconscious level (Bargh et al., 1995; Mussweiler & Forster, 2000; Zurbriggen, 2000). For men, implicit …

Studies Toward The Synthesis Of Lomaiviticins A And B And Englerin A, Srinivas Achanta

All Theses and Dissertations (ETDs)

Part I: Studies toward the central core of lomaiviticins A and B Lomaiviticins A and B are novel C2-symmetric dimeric molecules with profound cytotoxic activity. The most challenging feature of these molecules is the densely functionalized central core. Despite the effort by several research groups, the total synthesis of lomaiviticins has not been reported so far. We envisioned the synthesis of the lomaiviticin core by an unprecedented Diels-Alder dimerization of ortho-quinols and masked ortho-benzoquinones, followed by the fragmentation of the extra carbon-carbon bond. This chapter describes the stereoselective elaboration of the ortho-quinol and masked ortho-benzoquinone dimers to the fragmentation precursors …

Essays On Macro-Finance Relationships, Azamat Abdymomunov

All Theses and Dissertations (ETDs)

In my dissertation, I study relationships between macroeconomics and financial markets. In particular, I empirically investigate the links between key macroeconomic indicators, such as output, inflation, and the business cycle, and the pricing of financial assets. The dissertation comprises three essays. The first essay investigates how the entire term structure of interest rates is influenced by regime-shifts in monetary policy. To do so, we develop and estimate an arbitrage-free dynamic term-structure model which accounts for regime shifts in monetary policy, volatility, and the price of risk. Our results for U.S. data from 1985-2008 indicate that: i) the Fed's reaction to …

Physics Of Ultrasonic Wave Propagation In Bone And Heart Characterized Using Bayesian Parameter Estimation, Christian Anderson

All Theses and Dissertations (ETDs)

This Dissertation explores the physics underlying the propagation of ultrasonic waves in bone and in heart tissue through the use of Bayesian probability theory. Quantitative ultrasound is a noninvasive modality used for clinical detection, characterization, and evaluation of bone quality and cardiovascular disease. Approaches that extend the state of knowledge of the physics underpinning the interaction of ultrasound with inherently inhomogeneous and isotropic tissue have the potential to enhance its clinical utility. Simulations of fast and slow compressional wave propagation in cancellous bone were carried out to demonstrate the plausibility of a proposed explanation for the widely reported anomalous negative …

A Geometric Approach For Deciphering Protein Structure From Cryo-Em Volumes, Sasakthi Abeysinghe

All Theses and Dissertations (ETDs)

Electron Cryo-Microscopy or cryo-EM is an area that has received much attention in the recent past. Compared to the traditional methods of X-Ray Crystallography and NMR Spectroscopy, cryo-EM can be used to image much larger complexes, in many different conformations, and under a wide range of biochemical conditions. This is because it does not require the complex to be crystallisable. However, cryo-EM reconstructions are limited to intermediate resolutions, with the state-of-the-art being 3.6A, where secondary structure elements can be visually identified but not individual amino acid residues. This lack of atomic level resolution creates new computational challenges for protein structure …

Effects Of Attention Allocation On Habituation To Food Cues In Normal Weight And Overweight Children, Vandana Aspen

All Theses and Dissertations (ETDs)

ABSTRACT OF THE DISSERTATION Effects of Attention Allocation on Habituation to Food Cues in Normal weight and Overweight Children by Vandana Passi Aspen Doctor of Philosophy in Psychology Washington University in St. Louis, 2010 Professor Denise Wilfley, Chairperson Despite the rising prevalence of pediatric overweight, minimal research has been conducted to understand the basic biological processes underlying overweight in children. The present study assesses changes in physiological response: i.e., salivation) to food over time. The primary aims were to examine whether salivation patterns in children vary based on weight status and/or allocating attention to a distracter task. It was hypothesized …

Tandem, Oxidative Cyclizations By Anodic Electrochemistry And The Use Of Solar Power As An Alternate Energy Source, Laura Anderson

All Theses and Dissertations (ETDs)

Cyclization reactions are a significant pursuit in organic synthesis. Unfortunately, many cyclization reactions are either reductive in nature or redox neutral. This can force post-cyclization manipulations to add functional groups and continue the total synthesis. These additional reactions create excess waste and decrease the efficiency of a synthetic scheme. In these cases, it would be nice to do the cyclization in an oxidative fashion. Oxidative cyclizations have been performed, but are currently limited in nature and scope. One way to address this issue is with the use of organic electrochemistry. Electrochemistry appears to be an ideal choice for initiating oxidative …

Development Of Atomistic Potentials For Silicate Materials And Coarse-Grained Simulation Of Self-Assembly At Surfaces, Brian Barnes

All Theses and Dissertations (ETDs)

This thesis is composed of two parts. The first is a study of evolutionary strategies for parametrization of empirical potentials, and their application in development of a charge-transfer potential for silica. An evolutionary strategy was meta-optimized for use in empirical potential parametrization, and a new charge-transfer empirical model was developed for use with isobaric-isothermal ensemble molecular dynamics simulations. The second is a study of thermodynamics and self-assembly in a particular class of athermal two-dimensional lattice models. The effects of shape on self-assembly and thermodynamics for polyominoes and tetrominoes were examined. Many interesting results were observed, including complex clustering, non-ideal mixing, …

Now That's Promising: A Social Influence Model Of Innovation Evaluation, Peter Boumgarden

All Theses and Dissertations (ETDs)

Identifying and investing in innovative initiatives is a fundamental challenge for individuals in the contemporary organization. And yet, while we know a good deal about the psychology of innovation evaluation, we know decidedly less about how such processes are influenced by the formal and informal structures within which individuals in this setting operate. To address these limitations, I first draw from work on the psychology of idea evaluation to identify and develop a heuristic of evaluation relevant to the evaluation of innovation--that of an initiative's promise. I then suggest that such promise evaluations will be simultaneously influenced by the formal …

Synthetic Ion Transporters: New Analytical Approaches For The Investigation Of Ion Binding And Transport, Ionut Carasel

All Theses and Dissertations (ETDs)

Synthetic ion transporters: new analytical approaches for the investigation of ion binding and transport by Ionut Alexandru Carasel Doctor of Philosophy in Chemistry Washington University in St. Louis, 2010 Dr. George W. Gokel, co-Chair Dr. Kevin Moeller, co-Chair The work reported in this dissertation focuses on synthetic ion transporters: SATs). SATs have a relatively simple chemical structure but they aggregate, self-assemble and insert in biological membranes much in the same way as their much more complex naturally occurring analogs. This makes SATs valuable tools for the investigation of these supramolecular and membrane related processes with the final goal of developing …

Impact Of Second Messenger Modulation On Activity-Dependent And Basal Properties Of Excitatory Synapses, Chun Yun Chang

All Theses and Dissertations (ETDs)

Cognitive processing in the central nervous system relies on accurate information propagation; neurotransmission is the fundamental mechanism underlying network information flow. Because network information is coded by the timing and the strength of neuronal activity, synaptic properties that translate neuronal activity into synaptic output profoundly determine the precision of information transfer. Synaptic properties are in turn shaped by changes in network activity to ensure appropriate synaptic output. Activity-dependent adjustment of synaptic properties is often initiated by second messenger signals. Understanding how second messengers sculpt synaptic properties and produce changes in synaptic output is key for elucidating the interplay between network …

Towards Real-Time Wireless Sensor Networks, Octav Chipara

All Theses and Dissertations (ETDs)

Wireless sensor networks are poised to change the way computer systems interact with the physical world. We plan on entrusting sensor systems to collect medical data from patients, monitor the safety of our infrastructure, and control manufacturing processes in our factories. To date, the focus of the sensor network community has been on developing best-effort services. This approach is insufficient for many applications since it does not enable developers to determine if a system's requirements in terms of communication latency, bandwidth utilization, reliability, or energy consumption are met. The focus of this thesis is to develop real-time network support for …

Drilling Induced Fatigue Damage In Ti-6al-4v, James Castle

All Theses and Dissertations (ETDs)

The objective of this work is to develop an understanding of the relationship between hole drilling processes and the fatigue performance of the resulting part in Ti-6Al-4V. This problem is significant, as on the order of one-hundred thousand to a million holes are created in a typical large aircraft, and the limiting performance criterion is usually the fatigue lifetime. The path between the drilling process parameters and the fatigue performance has two main steps: characterization of the thermo-mechanical drill process and assessment of the relationship between the hole integrity left by the drill process and the fatigue performance. Development has …

Quantitative Phosphoproteomics Through Β-Elimination And Michael Addition With Natural Abundance And Stable Isotope Labeled Thiocholine, Meng Chen

All Theses and Dissertations (ETDs)

The reversible covalent phosphorylation of cellular proteins is widely believed to be the most important mechanism for the regulation of multiple signal transduction pathways in cell growth, division, and death by acting as a molecular switch at multiple nodes in metabolic networks. In this dissertation, first, a novel mass spectrometric strategy is reported that exploited the unique chemical properties of thiocholine that was introduced into protein phosphosites through alkaline beta-elimination and Michael addition: BEMA), allowing the specific detection, identification and quantitation of phosphorylated serine/threonine containing peptides. Through replacement of the phosphate with thiocholine as the Michael donor, this strategy resulted …

Light-Harvesting And The Primary Photochemistry Of Roseiflexus Castenholzii, Aaron Collins

All Theses and Dissertations (ETDs)

Photosynthetic organisms have evolved diverse antennas to harvest light of various qualities and intensities. Anoxygenic phototrophs can have bacteriochlorophyll Q_y antenna absorption bands ranging from about 700-1100 nm. This broad range of usable wavelengths has allowed many organisms to thrive in unique environments. Roseiflexus castenholzii is a niche-adapted, filamentous anoxygenic phototroph: FAP) that lacks chlorosomes, the dominant antenna found in all green bacteria. Light-harvesting is realized only in the membrane with BChl a and a variety of carotenoids. Through biochemical and spectroscopic methods, a model for the size and organization of the photosynthetic antenna is presented. Despite the wide …

The Hematopoietic Compartment Regulates Osteoblast Differentiation And Apoptosis During Cytokine Treatment, Matthew Christopher

All Theses and Dissertations (ETDs)

Adult hematopoiesis normally occurs in bone marrow, where hematopoietic stem cells: HSC) reside within a specialized microenvironment. At steady state, hematopoiesis state is regulated such that immature hematopoietic stem and progenitor cells: HSPC) are restricted to the bone marrow and are rarely observed in peripheral blood. Under certain circumstances, however, this regulation is loosened and significant numbers of HSPC are released to the circulation, a process termed "mobilization." Mobilization can be induced pharmacologically by a wide range of agents. Of these, the best characterized and most widely used mobilizing agent is Granulocyte-colony stimulating factor: G-CSF). G-CSF is widely used clinically …

The Relationship Between Hand-Nearness, Emotional Arousal, And Visual Processing, Christopher Davoli

All Theses and Dissertations (ETDs)

When an observer holds his or her hands near an object: hand-nearness), visual processing of that object differs in several ways from visual processing of an object far from the hands. Interestingly, the changes that visual processing undergoes during hand-nearness are the same as those that occur when an observer is emotionally aroused. In the present dissertation, three experiments examined whether hand-nearness and emotional arousal affect visual processing through a shared cognitive mechanism. More specifically, it was proposed that hand-nearness activates the same visual processing mechanism that is engaged during arousal. All experiments included replications of studies that have shown …

Stress Reactivity, Stress Appraisal And Coping Responses In Schizophrenia, Zainab Delawalla

All Theses and Dissertations (ETDs)

Psychosocial factors have long been recognized as important to the etiology of schizophrenia. According to the stress-vulnerability model, the experience of stress is critical to the onset and/or maintenance of schizophrenia. Although there is no conclusive evidence to suggest that people with schizophrenia experience more stressful events than the general population, there is ample evidence that stress is linked with the course of illness. Traditionally, two lines of research have examined stress processing mechanisms: one focusing on the biological response to stress by studying the hypothalamic-pituitary-adrenal: HPA) axis and the other focusing on the psychological mechanisms delineated in the transactional …

Brain Insulin Action Regulates Hypothalamic Glucose Sensing And The Counterregulatory Response To Hypoglycemia, Kelly Diggs-Andrews

All Theses and Dissertations (ETDs)

The brain is the primary organ that senses blood glucose levels and initiates a stress response when blood glucose levels are too low: hypoglycemia). Insulin-dependent people with Type 1 diabetes: T1DM) have an impaired ability to sense hypoglycemia and an impaired ability to activate this counterregulatory response: CRR) to hypoglycemia. As a result, T1DM are at a greater risk of experiencing insulin induced severe hypoglycemic episodes, which can result in seizures, brain damage, or even death. Since hypoglycemia is a major barrier that limits intensive blood glucose control, important research initiatives are needed to prevent or reduce the burden of …