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Articles 2311 - 2340 of 4195

Full-Text Articles in Physical Sciences and Mathematics

Characterization Of Gold Black And Its Application In Un-Cooled Infrared Detectors, Deep Panjwani Jan 2015

Characterization Of Gold Black And Its Application In Un-Cooled Infrared Detectors, Deep Panjwani

Electronic Theses and Dissertations

Gold black porous coatings were thermally evaporated in the chamber backfilled with inert gas pressure and their optical properties were studied in near-far-IR wavelengths. The porosities of coatings were found to be extremely high around ~ 99%. Different approaches of effective medium theories such as Maxwell-Garnett, Bruggeman, Landau-Lifshitz-Looyenga and Bergman Formalism were utilized to calculate refractive index (n) and extinction coefficient (k). The aging induced changes on electrical and optical properties were studied in regular laboratory conditions using transmission electron microscopy, Fourier transform infrared spectroscopy, and fore-probe electrical measurements. A significant decrease in electrical resistance in as deposited coating was …


Optical Propagation Of Self-Sustaining Wavefronts And Nonlinear Dynamics In Parabolic Multimode Fibers, Matthew Mills Jan 2015

Optical Propagation Of Self-Sustaining Wavefronts And Nonlinear Dynamics In Parabolic Multimode Fibers, Matthew Mills

Electronic Theses and Dissertations

The aim of this thesis is to introduce my work which has generally been focused on optical wavefronts that have the unusual property of resisting commonplace phenomena such as diffraction and dispersion. Interestingly, these special beams are found both in linear and nonlinear situations. For example, in the linear regime, localized spatio-temporal waves which resemble the spherical harmonic symmetries of the hydrogen quantum orbitals can simultaneously negotiate both diffractive and dispersive effects. In the nonlinear regime, dressed optical filaments can be arranged to propagate multi-photon produced plasma channels orders of magnitude longer than expected. The first portion of this dissertation …


Quantum Chemical Studies For The Engineering Of Metal Organic Materials, Hector Javier Rivera Jacquez Jan 2015

Quantum Chemical Studies For The Engineering Of Metal Organic Materials, Hector Javier Rivera Jacquez

Electronic Theses and Dissertations

Metal Organic Materials (MOM) are composed of transition metal ions as connectors and organic ligands as linkers. MOMs have been found to have high porosity, catalytic, and optical properties. Here we study the gas adsorption, color change, and non-linear optical properties of MOMs. These properties can be predicted using theoretical methods, and the results may provide experimentalists with guidance for rational design and engineering of novel MOMs. The theory levels used include semi-empirical quantum mechanical calculations with the PM7 Hamiltonian and, Density Functional Theory (DFT) to predict the geometry and electronic structure of the ground state, and Time Dependent DFT …


Synthesis And Characterization Of New Probes For Use In Fluorescence And X-Ray Ct Bioimaging, Simon Tang Jan 2015

Synthesis And Characterization Of New Probes For Use In Fluorescence And X-Ray Ct Bioimaging, Simon Tang

Electronic Theses and Dissertations

The pursuit of more suitable drugs intended for possible biological applications are a continuously growing topic of research within the scientific community. One of these suitable qualities includes the need for hydrophilicity and or some appropriate delivery system for the drug to enter into biological systems. A system of analyzing and following these compounds would then, however, be necessary to conduct any kind of mechanistic or interaction studies for he said drug within the biological system. Just to name a few, fluorescence and X-ray computed tomography (CT) methods allow for imaging of biological systems but require the need of compounds …


Characterization Of Groundwater Discharge In A Back Barrier Tidal Creek, Matthew L. Carter Jan 2015

Characterization Of Groundwater Discharge In A Back Barrier Tidal Creek, Matthew L. Carter

Electronic Theses and Dissertations

Groundwater discharge in the coastal environment is known to be a complex process. The driving mechanisms of groundwater discharge vary on spatial and temporal scales that can significantly impact coastal water chemistry and play a role in ecological zonation. Evolving combinations of observational and modeling approaches provide a basis to quantify groundwater discharge in a spatial and temporal sense. Here we employ a combination of geochemical (naturally occurring radon isotope) and geophysical (electrical resistivity) techniques to measure groundwater-surface water interactions along a back-barrier tidal creek. In addition to field measurements, a unique non-steady state radon mass balance equation was developed …


Linking Water Quality And Beach Morphodynamics In A Heavily Impacted Tidal Creek In Myrtle Beach, South Carolina, Brittany Lynne Hoffnagle Jan 2015

Linking Water Quality And Beach Morphodynamics In A Heavily Impacted Tidal Creek In Myrtle Beach, South Carolina, Brittany Lynne Hoffnagle

Electronic Theses and Dissertations

The morphological changes of small tidal creeks, driven by coastal processes, can pose risks to infrastructure and engineered coastlines and often rely on dredging to maintain them. These changes along the beachface can negatively affect the health of associated estuaries where open exchange between the ocean and creek basins is vital. This study used Real Time Kinematic-Differential Global Positioning System equipment to survey a small tidal creek in Myrtle Beach, South Carolina that often experiences migration to the south and requires dredging to maintain an open exchange between the ocean and the estuary. In order to understand the relationships between …


Synthetic Study Of Karlotoxins And Investigation Of Alpha-Diaminoboryl Carbanion Chemistry, Yusuke Takahashi Jan 2015

Synthetic Study Of Karlotoxins And Investigation Of Alpha-Diaminoboryl Carbanion Chemistry, Yusuke Takahashi

Electronic Theses and Dissertations

Karlotoxins (KmTxs), produced by a toxic marine/estuarine phytoplankton, the dinoflagellate Karlodinium veneficum, are known to be ichthyotoxic, thus being associated with numerous fish deaths events worldwide. They have also been reported to show a variety of biological activities such as hemolytic, cytotoxic, and anti-fungal activities. Recently, the Hamann group successfully assigned the absolute configurations of KmTx2, the first complete structure elucidation among the congeners. In a structural sense, karlotoxins are a family of linear polyketides with three distinctive regions; a bis-tetrahydropyran core fragment, a long, highly oxygenated carbon chain, and a lipophilic chlorodiene unit. Such potent biological activities as well …


The Sensitivity Of A Test Based On Spearman's Rho In Cross-Correlation Change Point Problems, Congjian Liu Jan 2015

The Sensitivity Of A Test Based On Spearman's Rho In Cross-Correlation Change Point Problems, Congjian Liu

Electronic Theses and Dissertations

In change point problems, there are three main questions that researchers are interested in. First of all, is there a change point or not? Second, when does the change point occur in a time series? Third, how quickly can we detect the change point? In this thesis, we first explain what a change point is, and what a cross-correlation is. We then discuss prior research in this area. Then we discuss and examine a test based on Spearman's rho, introduced by Wied and Dehling (2011), which tests the null hypothesis of no change point, and compare the change point we …


Automorphisms Of Graph Curves On K3 Surfaces, Joshua C. Ferrerra Jan 2015

Automorphisms Of Graph Curves On K3 Surfaces, Joshua C. Ferrerra

Electronic Theses and Dissertations

We examine the automorphism group of configurations of rational curves on $K3$ surfaces. We use the properties of finite automorphisms of $\PP^1$ to examine what restrictions a given elliptic fibration imposes on the possible finite order non-symplectic automorphisms of the $K3$ surface. We also examine the fixed loci of these automorphisms, and construct an explicit fibration to demonstrate the process.


Enumerating Graphs Using Integrals From Quantum Field Theory, William A. Coggins Jan 2015

Enumerating Graphs Using Integrals From Quantum Field Theory, William A. Coggins

Electronic Theses and Dissertations

Enumerating graphs is a relatively new subfield of mathematics. In this thesis, we will discuss a enumerative method that derives from Quantum Field Theory. We begin with the basic ideas of Calculus and extend them into a enumerative method that will allow us to classify graphs embedded on surfaces.


Calibration Of Option Pricing In Reproducing Kernel Hilbert Space, Lei Ge Jan 2015

Calibration Of Option Pricing In Reproducing Kernel Hilbert Space, Lei Ge

Electronic Theses and Dissertations

A parameter used in the Black-Scholes equation, volatility, is a measure for variation of the price of a financial instrument over time. Determining volatility is a fundamental issue in the valuation of financial instruments. This gives rise to an inverse problem known as the calibration problem for option pricing. This problem is shown to be ill-posed. We propose a regularization method and reformulate our calibration problem as a problem of finding the local volatility in a reproducing kernel Hilbert space. We defined a new volatility function which allows us to embrace both the financial and time factors of the options. …


Analysis And Simulation For Homogeneous And Heterogeneous Sir Models, Joseph Wilda Jan 2015

Analysis And Simulation For Homogeneous And Heterogeneous Sir Models, Joseph Wilda

Electronic Theses and Dissertations

In mathematical epidemiology, disease transmission is commonly assumed to behave in accordance with the law of mass action; however, other disease incidence terms also exist in the literature. A homogeneous Susceptible-Infectious-Removed (SIR) model with a generalized incidence term is presented along with analytic and numerical results concerning effects of the generalization on the global disease dynamics. The spatial heterogeneity of the metapopulation with nonrandom directed movement between populations is incorporated into a heterogeneous SIR model with nonlinear incidence. The analysis of the combined effects of the spatial heterogeneity and nonlinear incidence on the disease dynamics of our model is presented …


On The Theory Of Zeta-Functions And L-Functions, Almuatazbellah Awan Jan 2015

On The Theory Of Zeta-Functions And L-Functions, Almuatazbellah Awan

Electronic Theses and Dissertations

In this thesis we provide a body of knowledge that concerns Riemann zeta-function and its generalizations in a cohesive manner. In particular, we have studied and mentioned some recent results regarding Hurwitz and Lerch functions, as well as Dirichlet's L-function. We have also investigated some fundamental concepts related to these functions and their universality properties. In addition, we also discuss different formulations and approaches to the proof of the Prime Number Theorem and the Riemann Hypothesis. These two topics constitute the main theme of this thesis. For the Prime Number Theorem, we provide a thorough discussion that compares and contrasts …


Theoretical Study Of Laser Beam Quality And Pulse Shaping By Volume Bragg Gratings, Sergiy Kaim Jan 2015

Theoretical Study Of Laser Beam Quality And Pulse Shaping By Volume Bragg Gratings, Sergiy Kaim

Electronic Theses and Dissertations

The theory of stretching and compressing of short light pulses by the chirped volume Bragg gratings (CBG) is reviewed based on spectral decomposition of short pulses and on the wavelength-dependent coupled wave equations. The analytic theory of diffraction efficiency of a CBG with constant chirp and approximate theory of time delay dispersion are presented. Based on those, we performed comparison of the approximate analytic results with the exact numeric coupled-wave modeling. We also study theoretically various definitions of laser beam width in a given cross-section. Quality of the beam is characterized by the dimensionless beam propagation products (?x???_x)?? , which …


Tiling With Polyominoes, Polycubes, And Rectangles, Michael Saxton Jan 2015

Tiling With Polyominoes, Polycubes, And Rectangles, Michael Saxton

Electronic Theses and Dissertations

In this paper we study the hierarchical structure of the 2-d polyominoes. We introduce a new infinite family of polyominoes which we prove tiles a strip. We discuss applications of algebra to tiling. We discuss the algorithmic decidability of tiling the infinite plane Z x Z given a finite set of polyominoes. We will then discuss tiling with rectangles. We will then get some new, and some analogous results concerning the possible hierarchical structure for the 3-d polycubes.


Towards High-Flux Isolated Attosecond Pulses With A 200 Tw Cpa, Eric Cunningham Jan 2015

Towards High-Flux Isolated Attosecond Pulses With A 200 Tw Cpa, Eric Cunningham

Electronic Theses and Dissertations

Attosecond pulses have been developed as a means for investigating phenomena that proceed on the order of the atomic unit of time (24 as). Unfortunately, these extreme ultraviolet (XUV) pulses by themselves contain too few photons to initiate nonlinear dynamics or dress states in an attosecond pump--attosecond probe scheme. As a result, most attosecond experiments thus far have featured complementary near infrared (NIR) femtosecond lasers for instigating electron dynamics. In order to access the benefits of all-attosecond measurements and open attosecond physics to new fields of exploration, the photon flux of these pulses must be increased. One way to boost …


Quantitative Assessment Of The Effects Of Microbial Degradation Of A Simple Hydrocarbon Mixture, Jessica Kindell Jan 2015

Quantitative Assessment Of The Effects Of Microbial Degradation Of A Simple Hydrocarbon Mixture, Jessica Kindell

Electronic Theses and Dissertations

Ignitable liquids consist of either a single organic compound or a complex organic mixture. In regards to fire debris analysis, the analyst is responsible for determining if an ignitable liquid residue is present. However, when extracted from soil-containing fire debris evidence, chemical degradation from microorganisms is observed to result in the loss of compounds based on chemical structure. It can also happen when the evidence container is stored at room temperature before analysis. This can present a challenge to the fire debris analyst when identifying and classifying the ignitable liquid residue based on the criteria established by standard test methods. …


Investigation Of Optical And Electronic Properties Of Au Decorated Mos2, Udai Bhanu Jan 2015

Investigation Of Optical And Electronic Properties Of Au Decorated Mos2, Udai Bhanu

Electronic Theses and Dissertations

Achieving tunability of two dimensional (2D) transition metal dichalcogenides (TMDs) functions calls for the introduction of hybrid 2D materials by means of localized interactions with zero dimensional (0D) materials. A metal-semiconductor interface, as in gold (Au) - molybdenum disulfide (MoS2), is of great interest from the standpoint of fundamental science as it constitutes an outstanding platform to investigate optical and electronic properties due to charge transfer. The applied aspects of such systems introduce new options for electronics, photovoltaics, detectors, catalysis, and biosensing. Here in this dissertation, we study the charge transfer interaction between Au nanoparticals and MoS2 flakes and its …


Nano And Nanostructured Materials For Optical Applications, Panit Chantharasupawong Jan 2015

Nano And Nanostructured Materials For Optical Applications, Panit Chantharasupawong

Electronic Theses and Dissertations

Nano and nanostructured materials offer unique physical and chemical properties that differ considerably from their bulk counterparts. For decades, due to their fascinating properties, they have been extensively explored and found to be beneficial in numerous applications. These materials are key components in many cutting-edge optic and photonic technologies, including photovoltaics, waveguides and sensors. In this dissertation, the uses of nano and nanostructured materials for optical applications are investigated in the context of optical limiting, three dimensional displays, and optical sensing. Nanomaterials with nonlinear optical responses are promising candidates for self-activating optical limiters. In the first part of this study, …


Two-Photon Absorption In Bulk Semiconductors And Quantum Well Structures And Its Applications, Himansu Pattanaik Jan 2015

Two-Photon Absorption In Bulk Semiconductors And Quantum Well Structures And Its Applications, Himansu Pattanaik

Electronic Theses and Dissertations

The purpose of this dissertation is to provide a study and possible applications of two-photon absorption (2PA), in direct-gap semiconductors and quantum-well (QW) semiconductor structures. One application uses extremely nondegenerate (END) 2PA, for mid-infrared (mid-IR) detection in uncooled semiconductors. The use of END, where the two photons have very different energies gives strong enhancement comapared to degenerate 2PA. This END-2PA enhanced detection is also applied to mid-IR imaging and light detection and ranging (LIDAR) in uncooled direct-gap photodiodes. A theoretical study of degenerate 2PA (D-2PA) in quantum wells, QWs, is presented, along with a new theory of ND 2PA in …


Spectral Study Of Asteroids And Laboratory Simulation Of Asteroid Organics, Kelsey Hargrove Jan 2015

Spectral Study Of Asteroids And Laboratory Simulation Of Asteroid Organics, Kelsey Hargrove

Electronic Theses and Dissertations

We investigate the spectra of asteroids at near- and mid-infrared wavelengths. In 2010 and 2011 we reported the detection of 3 ?m and 3.2-3.6 ?m signatures on (24) Themis and (65) Cybele indicative of water-ice and complex organics [1] [2] [3]. We further probed other primitive asteroids in the Cybele dynamical group and Themis family, finding diversity in the shape of their 3 ?m [4] [5] [6] and 10 ?m spectral features [4]. These differences indicated mineralogical and compositional variations within these asteroid populations. Also in the mid-infrared region we studied a larger population of asteroids belonging to the Bus …


Forensic Application Of Chemometric Analysis To Visible Absorption Spectra Collected From Dyed Textile Fibers, Alejandra Flores Jan 2015

Forensic Application Of Chemometric Analysis To Visible Absorption Spectra Collected From Dyed Textile Fibers, Alejandra Flores

Electronic Theses and Dissertations

Forensic analysis of evidence consists of the comparison of physical, spectroscopic, or chemical characteristics of a questioned sample to a set of knowns. Currently, decisions as to whether or not the questioned sample can be associated or grouped with the knowns are left up to the discretion of the forensic analyst. The implications of these outcomes are presented as evidence to a jury in a court of law to determine if a defendant is guilty of committing a crime or not. Leading up to, and since, the publication of the National Academy of Sciences (NAS) report entitled “Strengthening Forensic Science …


Microscopic Theory Of The Knight Shift, Bianca Hall Jan 2015

Microscopic Theory Of The Knight Shift, Bianca Hall

Electronic Theses and Dissertations

This dissertation is the beginning of the development of a microscopic theory of the Knight shift. The Knight shift experiment has been used in superconductivity research throughout history, however, a complete understanding of the Knight shift in conventional as well as unconventional superconductors does not yet exist. Motivated by the results of a literature review, which discusses Knight shift anomalies in multiple superconducting materials, this research studies a new model of the Knight shift, which involves the processes involved in nuclear magnetic resonance measurements in metals. The result of this study is a microscopic model of nuclear magnetic resonance in …


A Theoretical And Experimental Investigation Of The Physical And Chemical Properties Of Solid Nanoscale Interfaces, Jeronimo Matos Jan 2015

A Theoretical And Experimental Investigation Of The Physical And Chemical Properties Of Solid Nanoscale Interfaces, Jeronimo Matos

Electronic Theses and Dissertations

With the emerging interest in nanoscale materials, the fascinating field of surface science is rapidly growing and presenting challenges to the design of both experimental and theoretical studies. The primary aim of this dissertation is to shed some light on the physical and chemical properties of selected nanoscale materials at the interface. Furthermore, we will discuss the effective application of cutting edge theoretical and experimental techniques that are invaluable tools for understanding the systems at hand. To this effect, we use density functional theory (DFT) with the inclusion of van der Waals (vdW) interactions to study the effect of long-range …


Quantifying Water Budgets To Evaluate The Hydrologic Performance Of Two Stormwater Detention Ponds In Coastal South Carolina, Samantha Corley Jan 2015

Quantifying Water Budgets To Evaluate The Hydrologic Performance Of Two Stormwater Detention Ponds In Coastal South Carolina, Samantha Corley

Electronic Theses and Dissertations

Due to their ability to reduce local flooding and protect receiving waters from intense stormwater pulses, stormwater detention ponds are commonly used stormwater management practices. Stormwater engineers construct ponds to moderate peak flow intensities and to allow residence time of the water within the pond to enhance nutrient removal prior to discharging into downstream ecosystems. Yet rarely, if ever, is the functionality of these ponds verified post-construction. This study aimed to compare hydrologic performance of two stormwater detention ponds located in coastal South Carolina to theoretical design plans by assessing a high resolution water budget. Inflow components of the water …


An Economic Analysis Of High-Intensity, Short-Duration Grazing Systems In South Dakota And Nebraska, Bronc Mcmurtry Jan 2015

An Economic Analysis Of High-Intensity, Short-Duration Grazing Systems In South Dakota And Nebraska, Bronc Mcmurtry

Electronic Theses and Dissertations

Four different grazing systems: two rotational, a continuous, and a high-intensity, short-duration (mob) system, replicated twice, were evaluated from an economic perspective. Mob grazing is defined as a system having very high stocking rates for a small amount of time. Livestock are forced to eat or trample the vegetation. Stocking rates and average daily gains (ADG) were collected from the UNL Barta Brothers ranch near Rose, Nebraska. The study started in 2011 and lasted until 2014. Using the performance data and other cost data relevant to South Dakota and Nebraska, budgets were set up for each system and extrapolated to …


Improvements On Instrumentation To Explore The Multidimensionality Of Luminescence Spectroscopy, Anthony Moore Jan 2015

Improvements On Instrumentation To Explore The Multidimensionality Of Luminescence Spectroscopy, Anthony Moore

Electronic Theses and Dissertations

This dissertation presents experimental and instrumentation developments that take full advantage of the multidimensional nature of line narrowing spectroscopy at liquid nitrogen (77 K) and liquid helium (4.2 K) temperatures. The inconvenience of sample freezing procedures is eliminated with the aid of cryogenic fiber optic probes. Rapid collection of multidimensional data formats such as wavelength time matrices, excitation emission matrices, time-resolved excitation emission matrices and time resolved excitation emission cubes is made possible with the combination of a pulsed tunable dye laser, a spectrograph and an intensifier-charged coupled device. These data formats provide unique opportunities for processing vibrational luminescence data …


Optical Fibers For Space-Division Multiplexed Transmission And Networking, Cen Xia Jan 2015

Optical Fibers For Space-Division Multiplexed Transmission And Networking, Cen Xia

Electronic Theses and Dissertations

Single-mode fiber transmission can no longer satisfy exponentially growing capacity demand. Space-division multiplexing (SDM) appears to be the only way able to dramatically improve the transmission capacity, for which, novel optical fiber is one of the key technologies. Such fibers must possess the following characteristics: 1) high mode density per cross-sectional area and 2) low crosstalk or low modal differential group delay (DMGD) to reduce complexity of digital signal processing. In this dissertation, we explore the design and characterization of three kinds of fibers for SDM: few-mode fiber (FMF), few-mode multi-core fiber (FM-MCF) and coupled multi-core fiber (CMCF) as well …


Aggregation Of Squaraine Dye Derivatives In Solid State Spin-Coated Thin Films, Mohammed Daoudi Jan 2015

Aggregation Of Squaraine Dye Derivatives In Solid State Spin-Coated Thin Films, Mohammed Daoudi

Electronic Theses and Dissertations

Squaraine dyes have been the subject of intensive studies due their unusual electronic properties that make them good candidates for a wide range of applications in various technological fields. They are particularly promising in nonlinear optics, bioimaging for labeling and sensing of biomolecules, as sensitizers for solar energy harvesting in solar cells and organic photovoltaics, two-photon absorbing materials, near-infrared (NIR) emitting fluorescent probes, second harmonic generation organic dyes, and sensitizers for photodynamic therapy among others. In this dissertation, the aggregation behaviors and features of several squaraine dye derivatives in solid state thin films were studied and reported. In the first …


Modeling Crowd Mobility And Communication In Wireless Networks, Gurkan Solmaz Jan 2015

Modeling Crowd Mobility And Communication In Wireless Networks, Gurkan Solmaz

Electronic Theses and Dissertations

This dissertation presents contributions to the fields of mobility modeling, wireless sensor networks (WSNs) with mobile sinks, and opportunistic communication in theme parks. The two main directions of our contributions are human mobility models and strategies for the mobile sink positioning and communication in wireless networks. The first direction of the dissertation is related to human mobility modeling. Modeling the movement of human subjects is important to improve the performance of wireless networks with human participants and the validation of such networks through simulations. The movements in areas such as theme parks follow specific patterns that are not taken into …