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Articles 1 - 30 of 55
Full-Text Articles in Physical Sciences and Mathematics
Topographic Signatures Of Geodynamics, Samuel G. Roy
Topographic Signatures Of Geodynamics, Samuel G. Roy
Electronic Theses and Dissertations
The surface of the Earth retains an imperfect memory of the diverse geodynamic, climatic, and surface transport processes that cooperatively drive the evolution of Earth. In this thesis I explore the potential of using topographic analysis and landscape evolution models to unlock past and/or present evidence for geodynamic activity. I explore the potential isolated effects of geodynamics on landscape evolution, particularly focusing on two byproducts of tectonic strain: rock displacement and damage. Field evidence supports a strong correlation between rock damage and erodibility, and a numerical sensitivity analysis supports the hypothesis that an order of magnitude weakening in rock, well …
The Local Cygnus Cold Cloud And Further Constraints On A Local Hot Bubble., Geoffrey Robert Lentner
The Local Cygnus Cold Cloud And Further Constraints On A Local Hot Bubble., Geoffrey Robert Lentner
Electronic Theses and Dissertations
Recent studies of the local interstellar medium have identified regions of nearby cold neutral gas with unexpected low temperatures and high pressures well within the boundaries of the local cavity (Meyer et al., 2006). Now, a multi-wavelength study of the local Leo cold cloud (LLCC) has strengthened our understanding of this apparent conflict with the conventional view of this environment (Peek et al., 2011, Meyer et al., 2012). The soft X-ray background observed here cannot be completely accounted for by a local hot bubble model (Snowden et al., 2015). Interstellar absorption of Na I (D2 λ5889.591 and D1 λ5895.924) was …
Combination Treatment With Conjugated Linoleic Acid And Nitrite Protects Against Myocaridal Infarction., Natia Qipshidze Kelm
Combination Treatment With Conjugated Linoleic Acid And Nitrite Protects Against Myocaridal Infarction., Natia Qipshidze Kelm
Electronic Theses and Dissertations
According to the CDC, the most common type of heart disease is coronary artery disease, which frequently leads to myocardial infarction (MI). Therapeutic approaches to lessen the resulting cardiovascular injury associated with MI are limited. Recently, the management paradigm for cardiac injury has entered the molecular era and microRNAs (miRNAs) have been shown to act as negative regulators of gene expression by inhibiting mRNA translation and/or stimulating mRNA degradation. A single miRNA can modulate physiological or disease phenotypes by regulating whole functional systems. Importantly, miRNAs can regulate cardiac function, thereby modulating heart muscle contraction, heart growth and morphogenesis. MicroRNA-499 (miRNA-499) …
High-Precision Time-Series Photometry For The Discovery And Characterization Of Transiting Exoplanets., Karen Alicia Collins 1962-
High-Precision Time-Series Photometry For The Discovery And Characterization Of Transiting Exoplanets., Karen Alicia Collins 1962-
Electronic Theses and Dissertations
The discovery of more than a thousand planets orbiting stars other than the Sun (i.e. exoplanets) over the past 20 years has shown that planetary systems are commonplace in the Milky Way galaxy. However, these discoveries are only a starting point in the quest to answer one of the most compelling questions posed by mankind for centuries – "are we alone in the universe?". This research aims to help build the foundation needed to search for that answer by optimizing data reduction techniques, determining and refining fundamental properties of known exoplanets, and searching for new exoplanets. Many exoplanets have been …
Liquid Crystal-Based Biosensors For The Detection Of Bile Acids, Sihui He
Liquid Crystal-Based Biosensors For The Detection Of Bile Acids, Sihui He
Electronic Theses and Dissertations
Bile acids are physiologically important metabolites, which are synthesized in liver as the end products of cholesterol metabolism and then secreted into intestine. They are amphiphilic molecules which play a critical role in the digestion and absorption of fats and fat-soluble vitamins through emulsification. The concentration of bile acids is an indicator for liver function. Individual suffering from liver diseases has a sharp increase in bile acid concentrations. Hence, the concentration level of bile acids has long been used as a biomarker for the early diagnosis of intestinal and liver diseases. Conventional methods of bile acid detection such as chromatography-mass …
High Efficiency And Wide Color Gamut Liquid Crystal Displays, Zhenyue Luo
High Efficiency And Wide Color Gamut Liquid Crystal Displays, Zhenyue Luo
Electronic Theses and Dissertations
Liquid crystal display (LCD) has become ubiquitous and indispensable in our daily life. Recently, it faces strong competition from organic light emitting diode (OLED). In order to maintain a strong leader position, LCD camp has an urgent need to enrich the color performance and reduce the power consumption. This dissertation focuses on solving these two emerging and important challenges. In the first part of the dissertation we investigate the quantum dot (QD) technology to improve the both the color gamut and the light efficiency of LCD. QD emits saturated color and grants LCD the capability to reproduce color vivid images. …
Electromechanical Lifting Actuation Of A Mems Cantilever And Nano-Scale Analysis Of Diffusion In Semiconductor Device Dielectrics, Imen Rezadad
Electronic Theses and Dissertations
This dissertation presents experimental and theoretical studies of physical phenomena in micro- and nano-electronic devices. Firstly, a novel and unproven means of electromechanical actuation in a micro-electro-mechanical system (MEMS) cantilever was investigated. In nearly all MEMS devices, electric forces cause suspended components to move toward the substrate. I demonstrated a design with the unusual and potentially very useful property of having a suspended MEMS cantilever lift away from the substrate. The effect was observed by optical micro-videography, by electrical sensing, and it was quantified by optical interferometry. The results agree with predictions of analytic and numerical calculations. One potential application …
Entanglement And Coherence In Classical And Quantum Optics, Kumel Kagalwala
Entanglement And Coherence In Classical And Quantum Optics, Kumel Kagalwala
Electronic Theses and Dissertations
We explore the concepts of coherence and entanglement as they apply to both the classical and quantum natures of light. In the classical domain, we take inspiration from the tools and concepts developed in foundational quantum mechanics and quantum information science to gain a better understanding of classical coherence theory of light with multiple degrees of freedom (DoFs). First, we use polarization and spatial parity DoFs to demonstrate the notion of classical entanglement, and show that Bell's measure can serve as a useful tool in distinguishing between classical optical coherence theory. Second, we establish a methodical yet versatile approach called …
Attosecond Transient Absorption Spectroscopy Of Atoms And Molecules, Yan Cheng
Attosecond Transient Absorption Spectroscopy Of Atoms And Molecules, Yan Cheng
Electronic Theses and Dissertations
One of the most fundamental goals of attosecond science is to observe and to control the dynamic evolutions of electrons in matter. The attosecond transient absorption spectroscopy is a powerful tool to utilize attosecond pulse to measure electron dynamics in quantum systems directly. In this work, isolated single attosecond pulses are used to probe electron dynamics in atoms and to study dynamics in hydrogen molecules using the attosecond transient absorption spectroscopy technique. The target atom/molecule is first pumped to excited states and then probed by a subsequent attosecond extreme ultraviolet (XUV) pulse or by a near infrared (NIR) laser pulse. …
Conservation Laws And Electromagnetic Interactions, Veerachart Kajorndejnukul
Conservation Laws And Electromagnetic Interactions, Veerachart Kajorndejnukul
Electronic Theses and Dissertations
Aside from energy, light carries linear and angular momenta that can be transferred to matter. The interaction between light and matter is governed by conservation laws that can manifest themselves as mechanical effects acting on both matter and light waves. This interaction permits remote, precise, and noninvasive manipulation and sensing at microscopic levels. In this dissertation, we demonstrated for the first time a complete set of opto-mechanical effects that are based on nonconservative forces and act at the interface between dielectric media. Without structuring the light field, forward action is provided by the conventional radiation pressure while a backward movement …
The Safe Removal Of Frozen Air From The Annulus Of A Liquid Hydrogen Storage Tank, Angela Krenn
The Safe Removal Of Frozen Air From The Annulus Of A Liquid Hydrogen Storage Tank, Angela Krenn
Electronic Theses and Dissertations
Large Liquid Hydrogen (LH2) storage tanks are vital infrastructure for NASA. Eventually, air may leak into the evacuated and perlite filled annular region of these tanks. Although the vacuum level is monitored in this region, the extremely cold temperature causes all but the helium and neon constituents of air to freeze. A small, often unnoticeable pressure rise is the result. As the leak persists, the quantity of frozen air increases, as does the thermal conductivity of the insulation system. Consequently, a notable increase in commodity boiloff is often the first indicator of an air leak. Severe damage can then result …
Nanoscale Control Of Gap-Plasmon Enhanced Optical Processes, Chatdanai Lumdee
Nanoscale Control Of Gap-Plasmon Enhanced Optical Processes, Chatdanai Lumdee
Electronic Theses and Dissertations
Surface plasmon resonances of metal nanostructures have been studied intensely in recent years. The strong plasmon-mediated electric field enhancement and field confinement well beyond the diffraction limit has been demonstrated to improve the performance of optical devices including ultrasensitive sensors, light emitters, and optical absorbers. A plasmon resonance mode of particular recent interest is the gap plasmon resonance that occurs on closely spaced metallic structures. In contrast to plasmon resonances supported by isolated metal nanostructures, coupled nanostructures provide additional spectral and spatial control over the plasmon resonance response. For example, the resonance frequencies of metal nanoparticle dimers depend strongly on …
Photon Statistics In Disordered Lattices, Hasan Kondakci
Photon Statistics In Disordered Lattices, Hasan Kondakci
Electronic Theses and Dissertations
Propagation of coherent waves through disordered media, whether optical, acoustic, or radio waves, results in a spatially redistributed random intensity pattern known as speckle -- a statistical phenomenon. The subject of this dissertation is the statistics of monochromatic coherent light traversing disordered photonic lattices and its dependence on the disorder class, the level of disorder and the excitation configuration at the input. Throughout the dissertation, two disorder classes are considered, namely, diagonal and off-diagonal disorders. The latter exhibits disorder-immune chiral symmetry -- the appearance of the eigenmodes in skew-symmetric pairs and the corresponding eigenvalues in opposite signs. When a disordered …
Nanoelectronic Devices Using Carbon Nanotubes And Graphene Electrodes: Fabrication And Electronic Transport Investigations, Narae Kang
Electronic Theses and Dissertations
Fabrication of high-performance electronic devices using the novel semiconductors is essential for developing future electronics which can be applicable in large-area, flexible and transparent displays, sensors and solar cells. One of the major bottlenecks in the fabrication of high-performance devices is a large interfacial barrier formation at metal/semiconductor interface originated from Schottky barrier and interfacial dipole barrier which causes inefficient charge injection at the interface. Therefore, having a favorable contact at electrode/semiconductor is highly desirable for high-performance devices fabrication. In this dissertation, the fabrication of nanoelectronic devices and investigation of their transport properties using carbon nanotubes (CNTs) and graphene as …
Nonlinear Optical Response Of Simple Molecules And Two-Photon Semiconductor Lasers, Matthew Reichert
Nonlinear Optical Response Of Simple Molecules And Two-Photon Semiconductor Lasers, Matthew Reichert
Electronic Theses and Dissertations
This dissertation investigates two long standing issues in nonlinear optics: complete characterization of the ultrafast dynamics of simple molecules, and the potential of a two-photon laser using a bulk semiconductor gain medium. Within the Born-Oppenheimer approximation, nonlinear refraction in molecular liquids and gases can arise from both bound-electronic and nuclear origins. Knowledge of the magnitudes, temporal dynamics, polarization and spectral dependences of each of these mechanisms is important for many applications including filamentation, white-light continuum generation, all-optical switching, and nonlinear spectroscopy. In this work the nonlinear dynamics of molecules are investigated in both liquid and gas phase with the recently …
Translocation Of A Semiflexible Polymer Through A Nanopore, Ramesh Adhikari
Translocation Of A Semiflexible Polymer Through A Nanopore, Ramesh Adhikari
Electronic Theses and Dissertations
The transport of a biomolecule through a nanopore occurs in many biological functions such as, DNA or RNA transport across nuclear pores and the translocation of proteins across the eukaryotic endoplasmic reticulum. In addition to the biological processes, it has potential applications in technology such as, drug delivery, gene therapy, and single molecule sensing. The DNA translocation through a synthetic nanopore device is considered as the basis for cheap and fast sequencing technology. Motivated by the experimental advances, many theoretical models have been developed. In this thesis, we explore the dynamics of driven translocation of a semiflexible polymer through a …
Mid-Infrared Plasmonics, Farnood Khalilzadeh Rezaie
Mid-Infrared Plasmonics, Farnood Khalilzadeh Rezaie
Electronic Theses and Dissertations
This dissertation reports investigations into materials for, and applications of, infrared surface plasmon polaritons (SPP). SPPs are inhomogeneous electromagnetic waves that are bound to the surface of a conductor. Tight confinement of electromagnetic energy, the primary virtue of SPPs for so-called "plasmonic" applications, requires plasma frequencies for the conductor near the intended infrared operational frequencies. This requires carrier concentrations that are much less than those of usual metals such as gold and silver. I have investigated the optical properties and SPP excitation resonances of two materials having infrared plasma frequencies, namely the semimetal bismuth and the transparent conducting fluorine-doped tin-oxide …
Characterization Of Gold Black And Its Application In Un-Cooled Infrared Detectors, Deep Panjwani
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
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 …
Theoretical Study Of Laser Beam Quality And Pulse Shaping By Volume Bragg Gratings, Sergiy Kaim
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 …
Towards High-Flux Isolated Attosecond Pulses With A 200 Tw Cpa, Eric Cunningham
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 …
Investigation Of Optical And Electronic Properties Of Au Decorated Mos2, Udai Bhanu
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
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
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
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 …
Microscopic Theory Of The Knight Shift, Bianca Hall
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
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 …
Optical Fibers For Space-Division Multiplexed Transmission And Networking, Cen Xia
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 …
Broadband Coherent Perfect Absorption In One-Dimensional Optical Systems, Massimo Maximilian Villinger
Broadband Coherent Perfect Absorption In One-Dimensional Optical Systems, Massimo Maximilian Villinger
Electronic Theses and Dissertations
Absorption plays a critical role in a variety of optical applications – sometimes it is desirable to minimize it as in optical fibers and waveguides, or to enhance it as in solar cells and photodetectors. We describe here a new optical scheme that controllably produces high optical absorption over a broad wavelength range (hundreds of nm) in systems that have low intrinsic absorption over the same range. This effect, 'coherent perfect absorption' or CPA, arises from a subtle interplay between interference and absorption of two beams incident on a weakly absorbing medium. In the first part of this study, we …
Resistive Pulse Study Of Vesicles And Liposomes, Yuqing Lin
Resistive Pulse Study Of Vesicles And Liposomes, Yuqing Lin
Electronic Theses and Dissertations
In this work, the properties of the liposomes, the artificially created vesicles by various methods, are explored by a resistive pulse method using micropipettes. The fact that vesicles are fundamental in the wide range of functionalities they fulfill as organelles strengthen the desire of understanding the properties of them. The motivation of this work comes from the significant roles that liposomes play in the development of targeted drug delivery systems. Among other significant variables, the size of liposomes is found to be one of the dominating parameters in liposome based drug delivery, and the correlation between liposome size and delivery …