Physical Sciences and Mathematics Commons^™

Identifying Examinees Who Possess Distinct And Reliable Subscores When Added Value Is Lacking For The Total Sample, Joseph A. Rios

Doctoral Dissertations

Research has demonstrated that although subdomain information may provide no added value beyond the total score, in some contexts such information is of utility to particular demographic subgroups (Sinharay & Haberman, 2014). However, it is argued that the utility of reporting subscores for an individual should not be based on one’s manifest characteristics (e.g., gender or ethnicity), but rather on individual needs for diagnostic information, which is driven by multidimensionality in subdomain scores. To improve the validity of diagnostic information, this study proposed the use of Mahalanobis Distance and H^T indices to assess whether an individual’s data significantly departs …

A Quantitative Measurement Of Structural Changes Of Rna Kissing Complexes Using Fluorescence Resonance Energy Transfer, Sheema Rahmanseresht

Doctoral Dissertations

Many RNA interactions in cells occur in the form of loop-loop interactions, also known as a "kissing complex". In the bacterial and viral systems discussed here, there are transiently bound proteins involved that modulate the function of kissing complex. These proteins either stabilize the kissing complex or facilitate its conversion to extended duplex. I studied R1inv-R2inv kissing complex (KC), derivatived from RNAI-RNAII complex of E.Coli. Rop protein is known to stabilize the bent R1inv-R2inv KC against dissociation. The goal was to study structural change of this kissing complex after binding of the stabilizing Rop protein. In this work for …

Search For Long-Lived, Weakly Interacting Particles That Decay To Displaced Hadronic Jets In Proton-Proton Collisions At √S = 8 Tev With The Atlas Detector, Preema R. Pais

Doctoral Dissertations

Many new physics models predict the existence of neutral, weakly interacting, long-lived particles that can decay within the detector volume, producing a distinctive experimental signature. A search is performed for a pair of such particles, using proton-proton collision data at √s = 8 TeV collected by the ATLAS detector in 2012, corresponding to a total integrated luminosity of 20.3 fb^-1. Novel techniques are developed for the reconstruction of displaced decays to hadronic jets in the inner tracking detector and muon spectrometer. No significant deviation is found from the number of background events expected from Standard Model processes. The …

Prospects For Infrared Quantum Gravity: From Cosmology To Black Holes, Basem K. Mahmoud El-Menoufi

Doctoral Dissertations

Although perturbatively non-renormalizable, general relativity is a perfectly valid quantum theory at low energies. Treated as an effective field theory one is able to make genuine quantum predictions by applying the conventional rules of quantum field theory. The low energy degrees of freedom and couplings of quantum gravity are fully dictated by the symmetries of general relativity. To realize the full EFT treatment one has to supplement the theory with experimental input necessary to fix the Wilson coefficients of the most general Lagrangian. In spite of the fact that this is not feasible, one can still extract the leading quantum …

Aggregation And Coagulation Of C60 Fullerene As Affected By Natural Organic Matter And Ionic Strength, Hamid Mashayekhi

Doctoral Dissertations

With widespread production and use of C₆₀ fullerene nanoparticles, their release to the environment and natural waters is inevitable. The colloidal nature of C₆₀ fullerene in the aquatic environment significantly influences its behavior in the environment including its transport, bioavailability and toxicity to different organisms. Natural organic matter (NOM) is a ubiquitous and reactive material in aquatic environments with significant structural heterogeneity. Therefore, the effect of NOM molecules on the colloidal behavior of fullerene particles needs to be studied. A major part of NOM consists of humic acids (HA). HAs have pronounced effects on the aggregation of C …

Learning From Pairwise Proximity Data, Hamid Dadkhahi

Doctoral Dissertations

In many areas of machine learning, the characterization of the input data is given by a form of proximity measure between data points. Examples of such representations are pairwise differences, pairwise distances, and pairwise comparisons. In this work, we investigate different learning problems on data represented in terms of such pairwise proximities. More specifically, we consider three problems: masking (feature selection) for dimensionality reduction, extension of the dimensionality reduction for time series, and online collaborative filtering. For each of these problems, we start with a form of pairwise proximity which is relevant in the problem at hand. We evaluate the …

Cell Modulation Using Functionalized Nanoparticles, Rui Tang

Doctoral Dissertations

Monolayer functionalized ultra-small gold nanoparticles (AuNPs) provide a versatile platform for applications in cell research. Through rational design of surface ligands, the chemistry of AuNPs are precisely regulated at atomic level. In this dissertation, applications of AuNPs in cell modulation are discussed. The topics are split into two categories. In the first category, functionalized AuNPs are harnessed to generate a robust monolayer on cell culture surface for cell modulation. The proliferation and behavior of different types of cancer cells and normal cells are modulated by tuning the surface ligands of AuNPs. Fate decision of mesenchymal stem cells are also modulated …

Uptake And Accumulation Of Engineered Nanomaterials By Agricultural Crops And Associated Risks In The Environment And Food Safety, Yingqing Deng

Doctoral Dissertations

Engineered nanomaterials (ENMs) are being discharged into the environment and to agricultural fields, with unknown impacts on crop species. This study focused on the bioaccumulation of engineered nanomaterials into crops and the associated impact on plant growth and plant uptake of secondary contaminant. Investigations into the interactions between nanomaterials and agricultural plants will provide a more developed understanding of nanomaterials implications in the environment; in addition, evaluations of the risks associated with plant-nanomaterials interactions will provide guidelines for safe use of nanomaterials in agriculture. In the screening study on phytotoxicity, carbon-based nanoparticles (NPs) including C₆₀, MWCNTs, NH_{2 …}

Combining Static And Dynamic Analysis For Bug Detection And Program Understanding, Kaituo Li

Doctoral Dissertations

This work proposes new combinations of static and dynamic analysis for bug detection and program understanding. There are 3 related but largely independent directions: a) In the area of dynamic invariant inference, we improve the consistency of dynamically discovered invariants by taking into account second-order constraints that encode knowledge about
invariants; the second-order constraints are either supplied by the programmer or vetted by the programmer (among candidate constraints suggested automatically); b) In the area of testing dataflow (esp. map-reduce) programs, our tool, SEDGE, achieves higher testing coverage by leveraging existing
input data and generalizing them using a symbolic reasoning engine …

Functional Hydrophilic Polymers For Solution Assembly And Non-Viral Gene Therapy, Rachel A. Letteri

Doctoral Dissertations

This thesis examines functional hydrophilic polymers designed in linear and comb architectures and that carry functional moieties in the context of solution assembly and non-viral gene therapy. Specifically, polymers containing cations, zwitterions, and reactive groups are investigated as non-viral gene therapy reagents and at oil-water interfaces on droplets. Cations facilitate complexation of nucleic acids and interaction with cellular and nuclear membranes, while zwitterions impart stimuli-responsive solution properties and biocompatibility. Reactive groups, including alkenes, alkynes, and benzylic methylenes, permit post-polymerization modification leading to tunable polymer properties in solution and at interfaces. This work expands the knowledge base related to solution, interfacial, …

Kinetics And Dynamics Of Electrophoretic Translocation Of Polyelectrolytes Through Nanopores, Harshwardhan Katkar

Doctoral Dissertations

The idea of sequencing a DNA based on single-file translocation of the DNA through nanopores under the action of an electric field has received much attention over the past two decades due to the societal need for low cost and high-throughput sequencing. However, due to the high speed of translocation, interrogating individual bases with an acceptable signal to noise ratio as they traverse the pore has been a major problem. Experimental facts on this phenomenon are rich and the associated phenomenology is yet to be fully understood. This thesis focuses on understanding the underlying principles of polymer translocation, with an …

Engineering The Nano-Bio Interface Of Gold Nanoparticles For Biomedical Applications, Ying Jiang

Doctoral Dissertations

Gold nanoparticles (AuNPs) have emerged as a promising platform for a myriad of biomedical applications, including sensing, drug delivery, and antibiotics. In this thesis, I have studied and engineered the interface of AuNPs with different biological systems, demonstrating a large variety of biomedical applications by modulation of these interfaces. My research was initially focused on systematically tuning the physicochemical properties of nanoparticles to understand nano-bio interactions at the cellular level. The results demonstrate that size and surface charge of AuNP interact in an interrelated fashion to modulate nanoparticle internalization by cells, providing an engineering strategy for designing nanomaterials for drug …

Polymer And Small Molecule Designs For Anion Conducting Membranes: Connected Ion-Channel Morphologies And Highly Alkaline Stable Ammonium Cations, Sedef P. Ertem

Doctoral Dissertations

Fuel cells are one of the oldest sustainable energy generation devices, converting chemical energy into electrical energy via reverse-electrolysis reactions. With the rapid development of polymer science, solid polymer electrolyte (SPE) membranes replaced the conventional liquid ion transport media, rendering low-temperature fuel cells more accessible for applications in portable electronics and transportation. However, SPE fuel cells are still far from commercialization due to high operation cost, and insufficient lifetime and performance limitations. Anion exchange membrane fuel cells (AEMFCs) are inexpensive alternatives to current proton exchange membrane fuel cell (PEMFC) technology, which relies on utilizing expensive noble-metal catalysts and perfluorinated SPE …

The Cosmic Web, And The Role Of Environment In Galaxy Evolution, Ryan Cybulski

Doctoral Dissertations

The Universe, on extra-galactic scales, is composed of a vast network of structures dubbed the “cosmic web”. One of the most fundamental discoveries about the evolution of galaxies is that their properties have a dependence on their location relative to this cosmic web (i.e., their environment). However, detailed studies of the environmental dependence on galaxy evolution have been extremely challenging due to the inherent complexity of the structures on the largest scales, a plethora of techniques being used to try to map the cosmic web, and other confounding factors, such as the masses of galaxies, that also affect their evolution. …

Embedding Oriented Graphs In Books, Stacey R. Mcadams

Doctoral Dissertations

A book consists of a line L in [special characters omitted]3, called the spine, and a collection of half planes, called pages, whose common boundary is L. A k-book is book with k pages. A k-page book embedding is a continuous one-to-one mapping of a graph G into a book such that the vertices are mapped into L and the edges are each mapped to either the spine or a particular page, such that no two edges cross in any page. Each page contains a planar subgraph of G. The book thickness, denoted bt( …

Anxiolytic Effects Of Propranolol And Diphenoxylate On Mice And Automated Stretch-Attend Posture Analysis, Kevin Scott Holly

Doctoral Dissertations

The prevention of social anxiety, performance anxiety, and social phobia via the combination of two generic drugs, diphenoxylate HC1 (opioid) plus atropine sulfate (anticholinergic) and propranolol HCl (beta blocker) was evaluated in mice through behavioral studies. A patent published on a September 8, 2011 by Benjamin D. Holly, US 2011/0218215 Al, prompted the research. The drug combination of diphenoxylate and atropine plus propranolol could be an immediate treatment for patients suffering from acute phobic and social anxiety disorders. Demonstrating the anxiolytic effects of the treatment on mice would validate a mouse model for neuroscientist to be used to detect the …

Generalized Partial Directed Coherence And Centrality Measures In Brain Networks For Epileptogenic Focus Localization, Joshua Aaron Adkinson

Doctoral Dissertations

Accurate epileptogenic focus localization is required prior to surgical resection of brain tissue for treatment of patients with intractable temporal lobe epilepsy, a clinical need that is partially fulfilled to date through a subjective, and at times inconclusive, evaluation of the recorded electroencephalogram (EEG). Using brain connectivity analysis, patterns of causal interactions between brain regions were derived from multichannel EEG of 127 seizures in nine patients with focal, temporal lobe epilepsy (TLE). The statistically significant directed interactions in the reconstructed brain networks were estimated from three second intracranial multi-electrode EEG segments using the Generalized Partial Directed Coherence (GPDC) and validated …

Lattice Boltzmann Methods For Wind Energy Analysis, Stephen Lloyd Wood

Doctoral Dissertations

An estimate of the United States wind potential conducted in 2011 found that the energy available at an altitude of 80 meters is approximately triple the wind energy available 50 meters above ground. In 2012, 43% of all new electricity generation installed in the U.S. (13.1 GW) came from wind power. The majority of this power, 79%, comes from large utility scale turbines that are being manufactured at unprecedented sizes. Existing wind plants operate with a capacity factor of only approximately 30%. Measurements have shown that the turbulent wake of a turbine persists for many rotor diameters, inducing increased vibration …

Synthesis And Characterization Of New Multifunctional Initiators For Anionic Polymerization And The Use Of Poly(4-Hydroxystyrene) As A Template For New Polymers, Christopher Michael Hurley

Doctoral Dissertations

This dissertation explores the synthesis and use of multifunctional anionic polymerization initiators for the purpose of opening the gateway to the synthesis of polymer architectures of greater complexity. First the multifunctional oxyanion initiator generated by reacting poly(4-hydroxystyrene) with sodium hydride was used to synthesize a previously unknown polymer containing an aryl halide functional group. The homopolymer solution self-assembly behavior of poly(4-hydroxystyrene) and the newly synthesized poly (4-bromo-phenyloxystyrene) were both investigated. This is followed by the synthesis and characterization of multifunctional alkyne core molecules and random copolymers of polystyrene-co-poly(4-hydroxystyrene) which served as templates for the synthesis of new random copolymers of …

The Effect Of Attractive Polymer-Nanoparticle Interactions On The Local Segmental Dynamics Of Polymer Nanocomposites, Adam Prillaman Holt

Doctoral Dissertations

Considerable progress has been made in understanding the miscibility and morphology of polymer nanocomposites (PNCs). However, to date, there is little understood concerning the modification of segmental mobility at the polymer-nanoparticle interface, which due to prevalence of interfaces in PNCs, will predominately control the viscoelastic and mechanical properties of these materials.

In this dissertation, static and dynamic experimental techniques are combined to identify the specific parameters controlling the modification of segmental dynamics at the polymer-nanoparticle interface in the model system of poly(2-vinyl pyridine)/silica nanocomposites. In general, the experimental results clearly demonstrate that the segmental dynamics at the polymer-nanoparticle interface are …

Achieving High Reliability And Efficiency In Maintaining Large-Scale Storage Systems Through Optimal Resource Provisioning And Data Placement, Lipeng Wan

Doctoral Dissertations

With the explosive increase in the amount of data being generated by various applications, large-scale distributed and parallel storage systems have become common data storage solutions and been widely deployed and utilized in both industry and academia. While these high performance storage systems significantly accelerate the data storage and retrieval, they also bring some critical issues in system maintenance and management. In this dissertation, I propose three methodologies to address three of these critical issues.

First, I develop an optimal resource management and spare provisioning model to minimize the impact brought by component failures and ensure a highly operational experience …

Reducing Power Consumption And Latency In Mobile Devices Using A Push Event Stream Model, Kernel Display Server, And Gui Scheduler, Stephen Gregory Marz

Doctoral Dissertations

The power consumed by mobile devices can be dramatically reduced by improving how mobile operating systems handle events and display management. Currently, mobile operating systems use a pull model that employs a polling loop to constantly ask the operating system if an event exists. This constant querying prevents the CPU from entering a deep sleep, which unnecessarily consumes power.

We’ve improved this process by switching to a push model which we refer to as the event stream model (ESM). This model leverages modern device interrupt controllers which automatically notify an application when events occur, thus removing the need to constantly …

A Generalized Method For Fissile Material Characterization Using Short-Lived Fission Product Gamma Spectroscopy, Justin Richard Knowles

Doctoral Dissertations

Characterizing the fissile content of nuclear materials is of particular interest to the safeguards and nuclear forensics communities. Short-lived fission product gamma spectroscopy offers a significant reduction in analysis time and detection limits when compared to traditional non-destructive assay measurements. Through this work, a fully generalizable method that can be applied to variations in fissile compositions and neutron spectra was developed for the modeling and measurement of short-lived fission product gamma-rays. This method uses a 238-group neutron flux that was characterized for two pneumatic tube positions in the High Flux Isotope Reactor using flux monitor irradiations. This flux spectrum was …

Characterizing Local Order And Physical Properties Of Rare Earth Complex Oxides, Thomas Jacob Shamblin

Doctoral Dissertations

With more than 500 compositions, materials possessing the pyrochlore structure have a myriad of technological applications and physical phenomena. Three of the most noteworthy properties are the structure’s ability to resist amorphization making it a possible host matrix for spent nuclear fuel, its exotic magnetic properties arising from geometric frustration, and fast ionic conductivity for solid-oxide fuel cell applications. This work focuses on these three aspects of the pyrochlore’s many potential uses. Structural characterization revealed that pyrochlore-type oxides have a tendency to disorder from a high symmetry cubic structure to a lower symmetry orthorhombic arrangement in response to a variety …

Conditional Computation In Deep And Recurrent Neural Networks, Andrew Scott Davis

Doctoral Dissertations

Recently, deep learning models such as convolutional and recurrent neural networks have displaced state-of-the-art techniques in a variety of application domains. While the computationally heavy process of training is usually conducted on powerful graphics processing units (GPUs) distributed in large computing clusters, the resulting models can still be somewhat heavy, making deployment in resource- constrained environments potentially problematic. In this work, we build upon the idea of conditional computation, where the model is given the capability to learn how to avoid computing parts of the graph. This allows for models where the number of parameters (and in a sense, the …

Hybrid Micellar Network Hydrogels Of Thermosensitive Hydrophilic Triblock Copolymers And Thermosensitive Hairy Nanoparticles, Bin Hu

Doctoral Dissertations

Hybrid micellar network hydrogels, composed of thermosensitive hydrophilic triblock copolymers and thermosensitive polymer brush-grafted nanoparticles (hairy NPs), exhibit intriguing rheological properties. This dissertation work studies thermosensitive hybrid hydrogels with NPs positioned either inside or outside the core of block copolymer micelles.

Chapter 1 is an introduction. Chapter 2 examines the effect of NP’s location on properties of hybrid hydrogels of a thermosensitive ABA triblock copolymer and hairy NPs. Two batches of thermoresponsive polymer brush-grafted silica NPs and an ABA triblock copolymer with thermosensitive outer blocks were prepared. When the lower critical solution temperature (LCST) of hairy NPs was similar to …

Synthesis And Application Of Polymer Brush-Grafted Nanoparticles As Hydrogel Gelators And Lubricant Additives, Roger Anthony Emory Wright

Doctoral Dissertations

This dissertation describes the synthesis of polymer brush-grafted nanoparticles (hairy NPs) and an analysis of their behavior or utility in multiple areas. The hairy NPs were synthesized from silica NPs functionalized with initiating moieties by surface-initiated atom transfer radical polymerization. A brief introduction to hairy NPs, with a focus on the synthesis and behavior of stimuli-responsive polymer brush-grafted particles, is given in Chapter 1 to provide context for this work.

Chapters 2 and 3 present the synthesis of thermosensitive diblock copolymer brush-grafted nanoparticles designed as hairy NP analogues in place of thermosensitive block copolymers micelles for the construction of hybrid, …

Spectroscopic Imaging Of Aluminum Containing Plasma, David Michael Surmick

Doctoral Dissertations

This dissertation aims to characterize laser-induced plasma from a physics point of view as warm, dense matter. Use of nominal nanosecond pulsed laser radiation initiates a plasma with electron temperatures of the order of 10 electron volts and electron densities of the order of air species densities at standard ambient temperature and pressure. For laser ablation and/or optical breakdown at or near a solid surface, the electron density can amount to be 1000 times greater. Spectroscopic investigations of the plasma emissions provide a method by which the electron density, temperature, and shockwave expansion may be determined. Of particular interest are …

Actinium-225 Production Via Proton Irradiation Of Thorium-232, Justin Reed Griswold

Doctoral Dissertations

High energy proton spallation reactions on natural thorium metal targets have been utilized to produce multi mCi [milliCurie] quantities of Actinium-225. Theoretical cross sections for actinium and thorium isotopes as well as for a select number of the fission products produced in these reactions were generated by the Monte Carlo radiation transport code PHITS to simulate the experimental data obtained from sixteen irradiations of thorium metal targets with 25-210 µA [microampere] proton beams ranging in energies from 77 to 192 MeV. Irradiations were conducted at Brookhaven National Laboratory (BNL) and Los Alamos National Laboratory (LANL), while target dissolution and processing …

Lignin-Based Li-Ion Anode Materials Synthesized From Low-Cost Renewable Resources, Nicholas William Mcnutt

Doctoral Dissertations

In today’s world, the demand for novel methods of energy storage is increasing rapidly, particularly with the rise of portable electronic devices, electric vehicles, and the personal consumption and storage of solar energy. While other technologies have arguably improved at a rate that is exponential in accordance with Moore’s law, battery technology has lagged behind largely due to the difficulty in devising new electric storage systems that are simultaneously high performing, inexpensive, and safe.

In order to tackle these challenges, novel Li-ion battery anodes have been developed at Oak Ridge National Laboratory that are made from lignin, a low-cost, renewable …