Physical Sciences and Mathematics Commons^™

New Microarray Image Segmentation Using Segmentation Based Contours Method, Yuan Cheng

Doctoral Dissertations

The goal of the research developed in this dissertation is to develop a more accurate segmentation method for Affymetrix microarray images. The Affymetrix microarray biotechnologies have become increasingly important in the biomedical research field. Affymetrix microarray images are widely used in disease diagnostics and disease control. They are capable of monitoring the expression levels of thousands of genes simultaneously. Hence, scientists can get a deep understanding on genomic regulation, interaction and expression by using such tools.

We also introduce a novel Affymetrix microarray image simulation model and how the Affymetrix microarray image is simulated by using this model. This simulation …

Nonlinear Granger Causality And Its Application In Decoding Of Human Reaching Intentions, Mengting Liu

Doctoral Dissertations

Multi-electrode recording is a key technology that allows the brain mechanisms of decision making, cognition, and their breakdown in diseases to be studied from a network perspective. As the hypotheses concerning the role of neural interactions in cognitive paradigms become increasingly more elaborate, the ability to evaluate the direction of neural interactions in neural networks holds the key to distinguishing their functional significance.

Granger Causality (GC) is used to detect the directional influence of signals between multiple locations. To extract the nonlinear directional flow, GC was completed through a nonlinear predictive approach using radial basis functions (RBF). Furthermore, to obtain …

Using Power-Law Properties Of Social Groups For Cloud Defense And Community Detection, Justin L. Rice

Doctoral Dissertations

The power-law distribution can be used to describe various aspects of social group behavior. For mussels, sociobiological research has shown that the Lévy walk best describes their self-organizing movement strategy. A mussel's step length is drawn from a power-law distribution, and its direction is drawn from a uniform distribution. In the area of social networks, theories such as preferential attachment seek to explain why the degree distribution tends to be scale-free. The aim of this dissertation is to glean insight from these works to help solve problems in two domains: cloud computing systems and community detection.

Privacy and security are …

Characterization Of Nano-Scaled Metal-Hydrides Confined In Nano-Porous Carbon Frameworks, David Edward Peaslee

Doctoral Dissertations

"Metal hydrides are currently being studied to provide hydrogen for use in fuel cells and for transportation applications. Hydrogen can be stored in chemical compounds at higher density and lower volume than liquid H₂ or compressed gas. Thermodynamic properties of metal hydrides differ between bulk and nano-sized particles. Many metal hydrides with useful volumetric and gravimetric capacities have high decomposition temperatures, but when placed in nano-sized frameworks (or templates) desorption and adsorption temperatures can be fine-tuned to meet engineering requirements for real-world systems. Additionally, some metal hydrides have shown a change in the decomposition pathway when infiltrated into these frameworks, …

Sparse Group Sufficient Dimension Reduction And Covariance Cumulative Slicing Estimation, Bilin Zeng

Doctoral Dissertations

"This dissertation contains two main parts: In Part One, for regression problems with grouped covariates, we adopt the idea of sparse group lasso (Friedman et al., 2010) to the framework of the sufficient dimension reduction. We propose a method called the sparse group sufficient dimension reduction (sgSDR) to conduct group and within group variable selections simultaneously without assuming a specific model structure on the regression function. Simulation studies show that our method is comparable to the sparse group lasso under the regular linear model setting, and outperforms sparse group lasso with higher true positive rates and substantially lower false positive …

Fundamental Properties Of Colloidal Unimolecular Polymer Particles, Minghang Chen

Doctoral Dissertations

"Colloidal Unimolecular Polymer (CUP) particles are a new genre of material formed by self-assembly into spheroidal particles due to the effect of hydrophilic/hydrophobic interactions of the polymer with a change in the solvent. The particle sizes were characterized by means of Dynamic Light Scattering with corrected viscosities instead of water's viscosity. The distribution of particle size agreed well with the distribution of molecular weight proving that the polymer had undergone unimolecular collapse. The rheology study shows the presence of surface water and its significant effect on the rheology. The primary and secondary electroviscous effects were also found to play roles …

Snoop-Forge-Replay Attack On Continuous Verification With Keystrokes, Khandaker Abir Rahman

Doctoral Dissertations

We present a new attack called the snoop-forge-replay attack on the keystroke-based continuous verification systems. We performed the attacks on two levels – 1) feature-level and 2) sample-level.

(1) Feature-level attack targets specific keystroke-based continuous verification method or system. In feature-level attacks, we performed a series of experiments using keystroke data from 50 users who typed approximately 1200 to 2300 keystrokes of free text during three different periods. The experiments consisted of two parts. In the first part, we conducted zero-effort verification experiments with two verifiers ("R" and "S") and obtained Equal Error Rates (EERs) between 10% and 15% under …

Structural And Magnetic Properties Of Ni And Cr Substituted La₀.₇Sr₀.₃Mno₃, Thomas Franklin Creel Jr.

Doctoral Dissertations

"The La₁₋ₓSrₓMn_1-yB_yO₃ perovskite systems where B represents a 3d transition metal such as Cr, Fe, Co, Ni, Cu, and Zn, are of significant interest due to their large magnetoresistance, and electronic transport properties that change significantly, depending on values of x and which transition metal used. Their applications in technology include cathodes for solid oxide fuel cells, resistance random access memory and catalysis. At certain doping concentrations on the B-site, metal-to-semiconductor or metal-to-insulator transitions coupled with colossal magnetoresistance occur, decreasing the resistivity (up to six orders of magnitude) upon the application of an external magnetic field. …

Privacy-Preserving Friend Recommendations In Online Social Networks, Bharath Kumar Samanthula

Doctoral Dissertations

"Online social networks, such as Facebook and Google+, have been emerging as a new communication service for users to stay in touch and share information with family members and friends over the Internet. Since the users are generating huge amounts of data on social network sites, an interesting question is how to mine this enormous amount of data to retrieve useful information. Along this direction, social network analysis has emerged as an important tool for many business intelligence applications such as identifying potential customers and promoting items based on their interests. In particular, since users are often interested to make …

Exploring Run-Time Reduction In Programming Codes Via Query Optimization And Caching, Venkata Krishna Suhas Nerella

Doctoral Dissertations

"Object oriented programming languages raised the level of abstraction by supporting the explicit first class query constructs in the programming codes. These query constructs allow programmers to express operations on collections more abstractly than relying on their realization in loops or through provided libraries. Join optimization techniques from the field of database technology support efficient realizations of such language constructs. However, the problem associated with the existing techniques such as query optimization in Java Query Language (JQL) incurs run time overhead. Besides the programming languages supporting first-class query constructs, the usage of annotations has also increased in the software engineering …

Phase Transitions In Disordered Systems, Fawaz Y. Hrahsheh

Doctoral Dissertations

"Disorder can have a wide variety of consequences for the physics of phase transitions. Some transitions remain unchanged in the presence of disorder while others are completely destroyed. In this thesis we study the effects of disorder on several classical and quantum phase transitions in condensed matter systems. After a brief introduction, we study the ferromagnetic phase transition in a randomly layered Heisenberg magnet using large-scale Monte-Carlo simulations. Our results provide numerical evidence for the exotic infinite-randomness scenario. We study classical and quantum smeared phase transitions in substitutional alloys A₁₋ₓBₓ. Our results show that the disorder completely destroys the phase …

Social-Context Based Routing And Security In Delay Tolerant Networks, Roy A. Cabaniss

Doctoral Dissertations

"Delay Tolerant Networks (DTNs) were originally intended for interplanetary communications and have been applied to a series of difficult environments: wireless sensor networks, unmanned aerial vehicles, and short-range personal communications. There is a class of such environments in which nodes follow semi-predictable social patterns, such as wildlife tracking or personal devices. This work introduces a series of algorithms designed to identify the social patterns present in these environments and apply this data to difficult problems, such as efficient message routing and content distribution. Security is also difficult in a mobile environment. This is especially the case in the event that …

Verification Of Information Flow Security In Cyber-Physical Systems, Rav Akella

Doctoral Dissertations

"With a growing number of real-world applications that are dependent on computation, securing the information space has become a challenge. The security of information in such applications is often jeopardized by software and hardware failures, intervention of human subjects such as attackers, incorrect design specification and implementation, other social and natural causes. Since these applications are very diverse, often cutting across disciplines a generic approach to detect and mitigate these issues is missing. This dissertation addresses the fundamental problem of verifying information security in a class of real world applications of computation, the Cyber-physical systems (CPSs). One of the motivations …

Quantum Phase Transitions In Disordered Magnets, David Nozadze

Doctoral Dissertations

"We study the effects of quenched weak disorder on quantum phase transitions in disordered magnets. The presence of disorder in the system can lead to a variety of exotic phenomena, e.g., the smearing of transitions or quantum Griffiths singularities. Phase transitions are smeared if individual spatial regions can order independently of the bulk system. In paper I, we study smeared quantum phase transitions in binary alloys A₁₋ₓBₓ that are tuned by changing the composition x. We show that in this case the ordered phase is extended over all compositions x < 1. We also study the composition dependence of observables. In paper II, we investigate the influence of spatial disorder correlations on smeared phase transitions. As an experimental example, we demonstrate in paper III, that the composition-driven ferromagnetic-toparamagnetic quantum phase transition in Sr₁₋ₓCaₓ RuO₃ is smeared. When individual spatial regions cannot order but fluctuate slowly, the phase transition is characterized by strong singularities in the quantum Griffiths phase. In paper IV, we develop a theory of the quantum Griffiths phases in disordered ferromagnetic metals. We show that the quantum Griffiths singularities are stronger than the usual power-law quantum Griffiths singularities in insulating magnets. In paper V, we present an efficient numerical method for studying quantum phase transitions in disordered systems with O(N) order parameter symmetry in the large-N limit. Our algorithm solves iteratively the large-N self-consistent equations for the renormalized distances from criticality. Paper VI is devoted to the study of transport properties in the quantum Griffiths phase associated with the antiferromagnetic quantum phase transition in a metal. We find unusual behavior of transport properties which is in contrast to the normal Fermi-liquid behavior"--Abstract, page v.

Creating New Superconducting & Semiconducting Nanomaterials And Investingating The Effect Of Reduced Dimensionality On Their Properties, Sukhada Mishra

Doctoral Dissertations

"The field of nanomaterials has continued to attract researchers to understand the fundamentals and to investigate potential applications in the fields of semiconductor physics, microfabrication, nanomedicine, surface sciences etc. One of the most critical aspects of the nanomaterials research is to establish synthetic protocols, which can address the underlying product requirements of reproducibility, homogenous morphology and controlled elemental composition. We have focused our research in exploring synthetic routes for the synthesis of superconducting and semiconducting nanomaterials and analyze their structure--property relationship through detailed characterizations. The first part of dissertation is focused on the synthesis of superconducting FeSe nanostructures using catalyst …

Polybenzoxazine Aerogels: Synthesis, Characterization, Conversion To Porous Carbons, And Energetic Composites, Shruti Mahadik-Khanolkar

Doctoral Dissertations

"Aerogels are nanoporous, low-density bulk objects, consisting of three-dimensional assemblies of nanoparticle. Structured similarly, polymeric aerogels are emerging as a mechanically strong alternative to traditional silica aerogels, which are fragile. Amongst polymeric aerogels, those based on polybenzoxazine (PBO - a type of phenolic resin), are extremely robust and comprise an economic alternative to resorcinol-formaldehyde aerogels, also a class of phenolic resins, as the main source of carbon aerogels. The drawback of the PBO chemistry has been the long (days) processing time at high-temperatures (>130 ºC). Herewith, we have developed an energy- and time-efficient process to PBO aerogels by inducing …

Isocyanate-Derived Organic Aerogels: Polyurethanes, Polyureas, Polyamides And Polyimides, Chakkaravarthy Chidambareswarapattar

Doctoral Dissertations

"Aerogels are 3D assemblies of nanoparticles with high open porosity and high surface area, and are pursued for their low density, low thermal conductivity, low dielectric constant and high acoustic attenuation. The foundation for those exceptional properties is their complex hierarchical solid framework (agglomerates of porous, fractal secondary nanoparticles). On the down side, however, aerogels are also fragile materials. The mechanical strength of silica aerogels has been improved by crosslinking the framework with organic polymers. The crosslinking polymer has been assumed to form a conformal coating on the surface of the skeletal framework bridging covalently the elementary building blocks. However, …

Polarization And Opinion Analysis In An Online Argumentation System For Collaborative Decision Support, Ravi Santosh Arvapally

Doctoral Dissertations

"Argumentation is an important process in a collaborative decision making environment. Argumentation from a large number of stakeholders often produces a large argumentation tree. It is challenging to comprehend such an argumentation tree without intelligent analysis tools. Also, limited decision support is provided for its analysis by the existing argumentation systems. In an argumentation process, stakeholders tend to polarize on their opinions, and form polarization groups. Each group is usually led by a group leader. Polarization groups often overlap and a stakeholder is a member of multiple polarization groups. Identifying polarization groups and quantifying a stakeholder's degree of membership in …

Geochemical And Isotopic Characterization Of Lead In Fugitive Dust From Unsurfaced Roads In Missouri, Emitt C. Witt

Doctoral Dissertations

"Eighteen unsurfaced roadways in Missouri's rural Ozark region were sampled to characterize the differences in trace element and isotopic chemistry to determine if there is a human health concern with inhaling and/or ingestion of fugitive dust generated by a moving vehicle. Road reaches were selected to represent those in similar rural areas with and without the presence of mining activity--13 roads were selected in the Viburnum Trend (VT) resource mining area and five were located to the southwest of the mining areas. Samples were collected using a novel cyclonic fugitive dust sampler (patent pending) that collects a composite sample from …

A Comparison Of Two Teaching Methods For Pediatric Medication Administration: Multimedia And Text-Based Modules, Renee Granados

Doctoral Dissertations

A Comparison of Two Teaching Methods for Pediatrics: Multimedia and Text-based Modules to Teach Pediatric Medication Administration

Nurse educators are in a position to design and develop effective methods that consider the cognitive structures and how the mind processes information to teach pediatric medication content to nursing students. The majority of methods teaching medication administration use only one mode: the visual mode. One mode to present leaning material does not take advantage of the additive effects of using two modes to present learning material.

The purpose of the study was to compare the effectiveness of two teaching methods to present …

Palynology Of Acid-Saline Lakes Of Western Australiabiostratigraphy And Paleoenvironmental Reconstruction, Carlos A. Sanchez Botero

Doctoral Dissertations

"Lakes are excellent repositories of fossils and sedimentary features that provide clues to past climatic and geologic events. Sediments from four cores drilled in Lake Aerodrome (LA1-09, LA2-09) and Lake Brown (LB1-09, LB2-09), two of the hundreds of ephemeral lakes in southern Western Australia, were analyzed for their palynological contents to understand the geologic and climatic evolution of the depositional basin. Palynofacies assemblages defined by statistical analyses of dispersed organic matter suggested differences in the depositional conditions and probable correlations between Lake Aerodrome cores. Detailed identifications and quantification of organic-walled microfossils yielded two palynomorph assemblages that reflect a climatic turnover: …

Transport In Correlated And Uncorrelated Random Media, With Applications To Molecularly Doped Polymers, Nilanka Praveena Gurusinghe

Doctoral Dissertations

"The commonly observed Poole-Frenkel field dependence; of the mobility of photo-injected charges in molecularly-doped polymers has been shown to arise from the spatially-correlated, Gaussian energy distribution of transport sites encountered by charges moving through the material. Experimental current-time transients obtained for molecularly-doped polymers exhibit universality with respect to electric field and a metal-insulator-like transition from non-dispersive to dispersive transport, features usually identified with multiple trapping models that assume an uncorrelated exponential distribution of trap energies. For materials that exhibit both sets of features the possibility arises that both kinds of disorder coexist. We study here, analytically and numerically, transport in …

Study Of Artificially Disordered Optical Fibers, Herath Mudiyanselage Sumudu Rasika Kumari Herath

Doctoral Dissertations

"Light transmission through photo-sensitive multi-mode fibers (MMF) with controlled volume disorder is investigated. Experiment shows that a segment of disordered MMF as short as 10 cm is sufficient to distribute power uniformly over all co-propagating modes and the intensity at the output surface of the fiber follows the Rayleigh negative exponential function. To explain the experimental findings, a comprehensive theoretical model is developed with three main results. First, statistical properties of all components of the dielectric tensor are obtained and analyzed in the framework a microscopical model of photo-sensitivity in a germano-silicate glasses. Secondly, it is shown that induced birefringence …

Optical Spectroscopic Studies Of Two Star Forming Regions, Kristen Leilani Erickson

Doctoral Dissertations

"The ρ Ophiuchi and Serpens molecular clouds are sites of low mass star formation. The goals of this study were to identify young stellar objects (YSOs) and estimate ages and masses in order to infer an initial mass function (IMF), investigate disk evolution, and determine the star-forming history. Optical spectroscopic surveys of an unbiased sample of candidate young stars have been completed. Optical images taken in different photometric bands were used to create color-magnitude diagrams from which sources were selected for spectroscopic observation. In combination with published data, 135 association members in ρ Ophiuchi and 63 association members plus 16 …

Quantum Phase Transitions In Impurity Models And Percolating Lattices, Manal M. Al-Ali

Doctoral Dissertations

"This thesis investigates the influence of random disorder and dissipation on zero-temperature quantum phase transitions. Both phenomena can fundamentally change the character of the phases of a quantum many-particle system and of the transitions between them. If dissipation and disorder occur simultaneously in a system undergoing a quantum phase transition, particularly strong effects can be expected. In the first paper reproduced in this thesis, we study a single quantum rotor coupled to a sub-Ohmic dissipative bath. We find that this system undergoes a quantum phase transition from a delocalized phase to a localized phase as the dissipation strength is increased. …

Charge, Bonding, And Magneto-Elastic Coupling In Nanomaterials, Qi Sun

Doctoral Dissertations

Phonons are exquisitely sensitive to finite length scale effects in a wide variety of materials because they are intimately connected to charge, structure, and magnetism, and a quantitative analysis of their behavior can reveal microscopic aspects of chemical bonding and spin-phonon coupling. To investigate these effects, we measured infrared vibrational properties of bulk and nanoscale MoS₂ [molybdenum disulfide], MnO [manganese(II) oxide], and CoFe₂O₄ [cobalt iron oxide]. From an analysis of frequencies, oscillator strengths, and high-frequency dielectric constants, we extracted Born and local effective charges, and polarizability for MoS₂ and MnO. For MoS₂ nanoparticles, in …

Local Residents' Experience Of The Coal Ash Spill In Kingston, Tennessee: A Phenomenological Study, Amy Lynn Mathis

Doctoral Dissertations

On December 22, 2008, near Kingston, Tennessee, a Tennessee Valley Authority (TVA) retention pond holding approximately 1.7 million cubic yards of coal fly ash failed, spilling the ash into the nearby Emory River and inundating farms and homes in the Swan Pond community. As a result more than 100 people were permanently displaced from their homes and the clean-up effort is ongoing.

The purpose of this study was to explore the experience of living near Kingston, Tennessee, in the aftermath of the spill. Using existential phenomenology as the guiding research methodology, I interviewed 9 participants from the area and asked …

Condensed Matter From Gauge/Gravity Duality, Jason Edward Therrien

Doctoral Dissertations

Currently strongly coupled systems present the greatest challenge to theoretical physics. For years conventional methods of approach have failed to describe these systems analytically. In recent years it has been shown that there is a duality between weakly coupled and strongly coupled systems, the Gauge Theory/Gravity Duality. In this dissertation I will discuss how the AdS/CFT is used to describe strongly coupled condensed matter systems as well as present the work done by the author and collaborators.

Measurement Of Theta-13 Neutrino Mixing Angle From The Disappearance Of Electron Antineutrinos At The Double Chooz Experiment, Brandon Reed White

Doctoral Dissertations

The measurement of the remaining neutrino-mixing angle, theta-130, is a critical step toward further understanding of neutrino properties and to guide future neutrino oscillation experiments. Double Chooz has a unique opportunity to perform this measurement building on the original CHOOZ reactor anti-neutrino experiment, the experience that set the previous limits on theta-13. In the first phase of Double Chooz, 101 days of data was analyzed with only the far detector operating of a two-detector plan. In this thesis I will describe the design of the low background neutrino detector and the oscillation analysis performed. From the deficiency between the expected …

Charge-Lattice-Spin Interactions In Molecule-Based Magnets, Tatiana Vladimir Brinzari

Doctoral Dissertations

Many of the most attractive properties of multifunctional materials can be traced to the competition between charge, structure, and magnetism. The discovery that these interactions can be tuned with various physical stimuli has accelerated interest in their behavior under extreme conditions. In this dissertation I present a spectroscopic investigation of several model molecule-based magnets under external stimuli of magnetic field and temperature. The compounds of interest include M^II[N(CN)₂]₂ (M=Mn, Co) and [Ru₂(O₂CMe)₄]₃[Cr(CN)₆]. These materials are attractive for their subtle interplay between electronic, magnetic and structural …