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Articles 2821 - 2850 of 4195

Full-Text Articles in Physical Sciences and Mathematics

Preferential Arrangement Containment In Strict Superpatterns, Martha Louise Liendo May 2012

Preferential Arrangement Containment In Strict Superpatterns, Martha Louise Liendo

Electronic Theses and Dissertations

Most results on pattern containment deal more directly with pattern avoidance, or the enumeration and characterization of strings which avoid a given set of patterns. Little research has been conducted regarding the word size required for a word to contain all patterns of a given set of patterns. The set of patterns for which containment is sought in this thesis is the set of preferential arrangements of a given length. The term preferential arrangement denotes strings of characters in which repeated characters are allowed, but not necessary. Cardinalities for sets of all preferential arrangements of given lengths and alphabet sizes …


Studies On The Preparation, Immobilization, And Luminescence Properties Of Zinc Oxide (Zno)Quantum Dots, Yasemin Hakat May 2012

Studies On The Preparation, Immobilization, And Luminescence Properties Of Zinc Oxide (Zno)Quantum Dots, Yasemin Hakat

Electronic Theses and Dissertations

Quantum dots are a part of very important our technological future because of their intriguing and useful properties. These properties are different in character from those of the corresponding bulk material. Quantum dots are inorganic artificial semiconductor nanocrystal whose electrons influence their physical and chemical properties. Zinc oxide quantum dots were synthesized through an ethanol based precipitation via colloidal synthesis method at various pH values. Various emission colors were obtained because the excited quantum dots of various sizes emitted specific wavelengths of light. The emission spectra indicated that the pH dependent quantum dots were successfully synthesized. Zinc oxide quantum dots …


On The Algebraic Reformulation Of The Partition Function, Emily Igo May 2012

On The Algebraic Reformulation Of The Partition Function, Emily Igo

Electronic Theses and Dissertations

The partition function has long enchanted the minds of great mathematicians, dating from Euler's attempts at calculating the value of this function in the 1700's, to Hardy and Ramanujan's asymptotic approach in the early twentieth century, through to Rademacher's representation as an explicit infinite series mid-century. This thesis will explore the historical attempts at grasping the behavior of this function, with particular attention paid to Euler's Pentagonal Number Theorem and Rademacher's Infinite Sum. We will then explore two reformulations due to Ono et al., with sample calculations from the recent algebraic reformulation, announced January, 2011.


Synthesis And Characterization Of Mesoporous Silica Membranes Modified By Atomic And Molecular Layer Deposition, David Emmett Cassidy May 2012

Synthesis And Characterization Of Mesoporous Silica Membranes Modified By Atomic And Molecular Layer Deposition, David Emmett Cassidy

Electronic Theses and Dissertations

Inorganic membranes offer a means for chemical separations in a variety of applications including chemical processing, drug delivery systems, battery separators and fuel cells. There is currently a “pore size gap” in silica membranes between 1-2 nanometers. Synthesizing membranes with a fine control of the pore size and distribution within that gap is a significant challenge. This thesis reports findings on using atomic and molecular layer deposition as new synthesis approaches to controlling pore size and chemical functionality of silica membranes. Mesoporous silica membranes, prepared using surfactant-templates with pore diameters ~4nm, were modified using atomic layer deposition and molecular layer …


From Automobiles To Alternatives: Applying Attitude Theory And Information Technologies To Increase Shuttle Use At Rocky Mountain National Park, Kourtney Kristen Collum May 2012

From Automobiles To Alternatives: Applying Attitude Theory And Information Technologies To Increase Shuttle Use At Rocky Mountain National Park, Kourtney Kristen Collum

Electronic Theses and Dissertations

This thesis examines potential strategies for increasing voluntary shuttle use at Rocky Mountain National Park (ROMO) and the gateway community of Estes Park, Colorado. The first chapter of this two-part study evaluates the impact of a pilot intelligent transportation system (ITS) on visitor awareness and use of shuttles during the summer of 2011. Two forms of ITS, dynamic message signs (DMS) and highway advisory radio (HAR), were evaluated. Specifically, the ITS was meant to influence day-visitors to park at a new park-and-ride lot just east of Estes Park where they could then board a connector shuttle and transfer to any …


Structure And Rheology Of The Sandhill Corner Shear Zone, Norumbega Fault System, Maine: A Study Of A Fault From The Base Of The Seismogenic Zone, Nancy Ann Price May 2012

Structure And Rheology Of The Sandhill Corner Shear Zone, Norumbega Fault System, Maine: A Study Of A Fault From The Base Of The Seismogenic Zone, Nancy Ann Price

Electronic Theses and Dissertations

Determining the structure and rheology of a seismogenic fault at frictional-to-viscous transition (FVT) depths is vital for understanding its strength and behavior. Few studies describe a fault from within this depth level, so the architecture of a shear zone at these depths as well as the effect of transient coseismic and postseismic deformation on the rheology of the shear zone is poorly-understood. The Sandhill Corner strand of the Paleozoic Norumbega fault system of Maine is the one of the few known examples of a subvertical, strike-slip fault exhumed from FVT depths. Using a suite of samples collected from the Sandhill …


Exploration Of The Chemistry Of Alkynes And Selectfluor : Search For Cytotoxic Agents From The Amazonian Rainforest., Zhuang Jin May 2012

Exploration Of The Chemistry Of Alkynes And Selectfluor : Search For Cytotoxic Agents From The Amazonian Rainforest., Zhuang Jin

Electronic Theses and Dissertations

Vicinal dithioethers and alkenyl thioethers were synthesized under environmentally friendly conditions using alkyne and thiol in water. Alkynes were also used to develop a multibond-fonning reaction that fonned cyclic ketones or ketoesters through a goldcatalyzed intramolecular oxygen transfer isomerization of 2-alkynyl-l ,5-diketones or 2- alkyny 1-5 -ketoesters. The investigation of Selectfluor chemistry yielded a highly stereoselective synthesis of fluoroalky (E)-a,ß-unsaturated ketones from allenyl esters, through a gold-catalyzed rearrangement that produced an intennediate dienyl ester. When Selectfluor was combined with copper, it produced two oxidative systems, F-TEDA-BF4 and F-TEDAPF 6, both of which efficiently converted amides into imides at room temperature …


Vertical Field Switching Blue Phase Liquid Crystals For Field Sequential Color Displays, Hui-Chuan Cheng Jan 2012

Vertical Field Switching Blue Phase Liquid Crystals For Field Sequential Color Displays, Hui-Chuan Cheng

Electronic Theses and Dissertations

Low power consumption is a critical requirement for all liquid crystal display (LCD) devices. A field sequential color (FSC) LCD was proposed by using red (R), green (G) and blue (B) LEDs and removing the lossy component of color filters which only transmits ~30% of the incoming white light. Without color filters, FSC LCDs exhibit a ~3X higher optical efficiency and 3X higher resolution density as compared to the conventional color filters-based LCDs. However, color breakup (CBU) is a most disturbing defect that degrades the image quality in FSC displays. CBU can be observed in stationary or moving images. It …


Investigation Of Breakdown Power During Electrical Breakdown Of Aligned Array Of Carbon Nanotubes, Udai Bhanu Jan 2012

Investigation Of Breakdown Power During Electrical Breakdown Of Aligned Array Of Carbon Nanotubes, Udai Bhanu

Electronic Theses and Dissertations

Massively parallel arrays of single walled carbon nanotubes (SWNT) have attracted significant research interests because of their ability to (i) average out inhomogeneities of individual SWNTs, (ii) provide larger on currents, and (iii) reduce noise to provide higher cutoff frequency for radio frequency applications. However, the array contains both metallic and semiconducting SWNTs and the presence of metallic nanotube in an aligned array negatively affects the device properties. Therefore, it is essential to selectively remove metallic nanotubes to obtain better transistor properties. It was recently found that although such a selective removal can be effective for a low density array, …


Use Of An Activated Magnesium/Cosolvent System For The Desorption And Degradation Of Polycyclic Aromatic Hydrocarbons And Their Oxygenated Derivatives In Contaminated Soils, Marc Elie Jan 2012

Use Of An Activated Magnesium/Cosolvent System For The Desorption And Degradation Of Polycyclic Aromatic Hydrocarbons And Their Oxygenated Derivatives In Contaminated Soils, Marc Elie

Electronic Theses and Dissertations

The contamination of soils, with polycyclic aromatic hydrocarbons (PAHs), remains a widespread environmental concern. In the past two decades, many physical, chemical and biological methods have been developed and evaluated for the degradation of PAHs. However, due to their low aqueous solubility, high sorption affinity, hydrophobicity and recalcitrance, the environmental remediation of PAHs in soil continues to be economically challenging. In addition to PAH contamination, the presence of oxygenated derivatives of PAHs (OPAHs), in soils, has increasingly become a concern due to their greater toxic properties compared to parent PAH compounds. To date, no investigations on OPAH-remediation methods have been …


Photochemistry And Applications Of Diels-Alder Adducts And Photoacids In Materials Science, Valentine Johns Jan 2012

Photochemistry And Applications Of Diels-Alder Adducts And Photoacids In Materials Science, Valentine Johns

Electronic Theses and Dissertations

In chapter I Photo-retro-Diels-Alder (PrDA) reactions of a variety of Diels Alder (DA) adducts were studied. Experimental results showed that the photoreactivity (quantum yield) depends on the electron-donating ability of the diene component and the electronwithdrawing ability of the dienophile component. The mechanism was studied by trapping the reaction intermediate, O2 quenching and femtosecond time-resolved absorption spectroscopy. All the results support a mechanism that involves a charge-separated intermediate generated from a singlet excited state. The PrDA reaction may find applications in photoresponsive materials, photolithography, drug delivery and mechanistic research. Chapter II shows two applications of the PrDA reaction. The first, …


First Principles Studies Of Pattern Formations And Reactions On Catalyst Surfaces, Duy Le Jan 2012

First Principles Studies Of Pattern Formations And Reactions On Catalyst Surfaces, Duy Le

Electronic Theses and Dissertations

This dissertation undertakes theoretical research into the adsorption, pattern formation, and reactions of atoms, molecules, and layered materials on catalyst surfaces. These investigations are carried out from first-principles calculations of electronic and geometric structures using density functional theory (DFT) for predictions and simulations at the atomic scale. The results should be useful for further study of the catalytic activities of materials and for engineering functional nanostructures. The first part of the dissertation focuses on systematic first-principles simulations of the energetic pathways of CO oxidation on the Cu2O(100) surface. These simulations show CO to oxidize spontaneously on the O-terminated Cu2O(100) surface …


State (Hydrodynamics) Identification In The Lower St. Johns River Using The Ensemble Kalman Filter, Hitoshi Tamura Jan 2012

State (Hydrodynamics) Identification In The Lower St. Johns River Using The Ensemble Kalman Filter, Hitoshi Tamura

Electronic Theses and Dissertations

This thesis presents a method, Ensemble Kalman Filter (EnKF), applied to a highresolution, shallow water equations model (DG ADCIRC-2DDI) of the Lower St. Johns River with observation data at four gauging stations. EnKF, a sequential data assimilation method for non-linear problems, is developed for tidal flow simulation for estimation of state variables, i.e., water levels and depth-integrated currents for overland unstructured finite element meshes. The shallow water equations model is combined with observation data, which provides the basis of the EnKF applications. In this thesis, EnKF is incorporated into DG ADCIRC-2DDI code to estimate the state variables. Upon its development, …


Third Order Nonlinearity Of Organic Molecules, Honghua Hu Jan 2012

Third Order Nonlinearity Of Organic Molecules, Honghua Hu

Electronic Theses and Dissertations

The main goal of this dissertation is to investigate the third-order nonlinearity of organic molecules. This topic contains two aspects: two-photon absorption (2PA) and nonlinear refraction (NLR), which are associated with the imaginary and real part of the third-order nonlinearity (χ (3)) of the material, respectively. With the optical properties tailored through meticulous molecular structure engineering, organic molecules are promising candidates to exhibit large third-order nonlinearities. Both linear (absorption, fluorescence, fluorescence excitation anisotropy) and nonlinear (Z-scan, two-photon fluorescence, pump-probe) techniques are described and utilized to fully characterize the spectroscopic properties of organic molecules in solution or solid-state form. These properties …


Detecting And Characterizing Exoplanets: The Gj 436 And Hd 149026 Systems, Kevin Stevenson Jan 2012

Detecting And Characterizing Exoplanets: The Gj 436 And Hd 149026 Systems, Kevin Stevenson

Electronic Theses and Dissertations

This dissertation investigates two stellar systems known to contain extrasolar planets. It is comprised of five chapters that are readily divided into three independent but related analyses. Chapter 1 reports on the analysis of low signal-to-noise secondary-eclipse observations of the Neptune-sized exoplanet GJ 436b using the Spitzer Space Telescope in multiple infrared channels. The measured wavelength-dependent eclipse depths provide constraints on the planet’s dayside atmospheric composition and thermal profile. The analysis indicates that GJ 436b’s atmosphere is abundant in carbon monoxide and deficient in methane relative to thermochemical equilibrium models for the predicted hydrogen-dominated atmosphere. Chapter 2 discusses the techniques …


Autoregressive Models, Kelly Wade Jan 2012

Autoregressive Models, Kelly Wade

Electronic Theses and Dissertations

Consider a sequence of random variables which obeys a first order autoregressive model with unknown parameter alpha. Under suitable assumptions on the error structure of the model, the limiting distribution of the normalized least squares estimator of alpha is discussed. The choice of the normalizing constant depends on whether alpha is less than one, equals one, or is greater than one in absolute value. In particular, the limiting distribution is normal provided that the absolute value of alpha is less than one, but is a function of Brownian motion whenever the absolute value of alpha equals one. Some general remarks …


An Assessment Of Ecological Processes In The Apalachicola Estuarine System, Florida, Daina Smar Jan 2012

An Assessment Of Ecological Processes In The Apalachicola Estuarine System, Florida, Daina Smar

Electronic Theses and Dissertations

The following is a compilation of field data collected in 2011 and 2012 in Apalachicola, FL as part of a five year study assessing the ecological effects of sea level rise in the northern Gulf of Mexico. Many coastal communities, both natural and developed, will soon be working to mitigate the effects of sea level rise, if they are not already doing so. This thesis investigates the natural patterns of the Apalachicola estuarine system through the collection and analysis of in situ water, sediment, and biomass samples. Additionally, results of the field samples are presented and recommendations for additional sampling …


Online Path Planning And Control Solution For A Coordinated Attack Of Multiple Unmanned Aerial Vehicles In A Dynamic Environment, Juan Vega-Nevarez Jan 2012

Online Path Planning And Control Solution For A Coordinated Attack Of Multiple Unmanned Aerial Vehicles In A Dynamic Environment, Juan Vega-Nevarez

Electronic Theses and Dissertations

The role of the unmanned aerial vehicle (UAV) has significantly expanded in the military sector during the last decades mainly due to their cost effectiveness and their ability to eliminate the human life risk. Current UAV technology supports a variety of missions and extensive research and development is being performed to further expand its capabilities. One particular field of interest is the area of the low cost expendable UAV since its small price tag makes it an attractive solution for target suppression. A swarm of these low cost UAVs can be utilized as guided munitions or kamikaze UAVs to attack …


Convective Heat Transfer In Nanofluids, Steven Schraudner Jan 2012

Convective Heat Transfer In Nanofluids, Steven Schraudner

Electronic Theses and Dissertations

In recent years, the study of fluid flow with nanoparticles in base fluids has attracted the attention of several researchers due to its various applications to science and engineering problems. Recent investigations on convective heat transfer in nanofluids indicate that the suspended nanoparticles markedly change the transport properties and thereby the heat transfer characteristics. Convection in saturated porous media with nanofluids is also an area of growing interest. In this thesis, we study the effects of radiation on the heat and mass transfer characteristics of nanofluid flows over solid surfaces. In Chapter 2, an investigation is made into the effects …


Improving Student Learning In Undergraduate Mathematics, Gabrielle Rejniak Jan 2012

Improving Student Learning In Undergraduate Mathematics, Gabrielle Rejniak

Electronic Theses and Dissertations

The goal of this study was to investigate ways of improving student learning, par- ticularly conceptual understanding, in undergraduate mathematics courses. This study focused on two areas: course design and animation. The methods of study were the following: Assessing the improvement of student conceptual understanding as a result of team project-based learning, individual inquiry-based learning and the modi ed empo- rium model; and Assessing the impact of animated videos on student learning with the emphasis on concepts. For the first part of our study (impact of course design on student conceptual understanding) we began by comparing the following three groups …


Towards Evolving More Brain-Like Artificial Neural Networks, Sebastian Risi Jan 2012

Towards Evolving More Brain-Like Artificial Neural Networks, Sebastian Risi

Electronic Theses and Dissertations

An ambitious long-term goal for neuroevolution, which studies how artificial evolutionary processes can be driven to produce brain-like structures, is to evolve neurocontrollers with a high density of neurons and connections that can adapt and learn from past experience. Yet while neuroevolution has produced successful results in a variety of domains, the scale of natural brains remains far beyond reach. In this dissertation two extensions to the recently introduced Hypercube-based NeuroEvolution of Augmenting Topologies (HyperNEAT) approach are presented that are a step towards more brain-like artificial neural networks (ANNs). First, HyperNEAT is extended to evolve plastic ANNs that can learn …


Submillisecond-Response Blue Phase Liquid Crystals For Display Applications, Kuan Ming Chen Jan 2012

Submillisecond-Response Blue Phase Liquid Crystals For Display Applications, Kuan Ming Chen

Electronic Theses and Dissertations

With exploding growth of information exchanges between people, display has become indispensable in our daily lives. After decades of intensive research and development in materials and devices, and massive investment in manufacturing technologies, liquid crystal display (LCD) has overcome various obstacles and achieved the performance we need, such as wide viewing angle, high contrast ratio, and high resolution, etc. These excellent performances make LCD prevailed in every perspective. Recently, with the demands of energy conservation, a greener LCD with lower power consumption is desired. In order to achieve this goal, new energy-effective driving methods, such as field sequential color display, …


Setpad: A Sketch-Based Tool For Exploring Discrete Math Set Problems, Travis Cossairt Jan 2012

Setpad: A Sketch-Based Tool For Exploring Discrete Math Set Problems, Travis Cossairt

Electronic Theses and Dissertations

We present SetPad, a new application prototype that lets computer science students explore discrete math problems by sketching set expressions using pen-based input. Students can manipulate the expressions interactively with the tool via pen or multi-touch interface. Likewise, discrete mathematics instructors can use SetPad to display and work through set problems via a projector to better demonstrate the solutions to the students. We discuss the implementation and feature set of the application, as well as results from both an informal perceived usefulness evaluation for students taking a computer science foundation exam in addition to a formal user study measuring the …


Characterization Of Online Archives Of Astronomical Imaging Vis-A-Vis Serendipitous Asteroids, And Their Astrometric Properties, Jean Marc Denis Jan 2012

Characterization Of Online Archives Of Astronomical Imaging Vis-A-Vis Serendipitous Asteroids, And Their Astrometric Properties, Jean Marc Denis

Electronic Theses and Dissertations

The identification of known asteroids on existing CCD pictures would allow us to obtain accurate astrometric and photometric asteroid properties. Some asteroids might have ambiguous orbital elements, thus their identification along with their exact positions on multiple picture frames could significantly improve their orbital elements. Furthermore, the possibility of identifying known asteroids on older pictures, sometimes preceding their discovery date, might allow the study of non-gravitational effects like the Yarkovsky effect. Identifying a potential Yarkovsky effect on asteroids is challenging because it is extremely weak. However, this effect cumulates with time, therefore, it is necessary to find astronomical pictures that …


High-Efficiency Blue Phase Liquid Crystal Displays, Yan Li Jan 2012

High-Efficiency Blue Phase Liquid Crystal Displays, Yan Li

Electronic Theses and Dissertations

Blue phase liquid crystals (BPLCs) have a delicate lattice structure existing between chiral nematic and isotropic phases, with a stable temperature range of about 2 K. But due to short coherent length, these self-assembled nano-structured BPLCs have a fast response time. In the past three decades, the application of BPLC has been rather limited because of its narrow temperature range. In 2002, Kikuchi et al. developed a polymer stabilization method to extend the blue-phase temperature range to more than 60 K. This opens a new gateway for display and photonic applications. In this dissertation, I investigate the material properties of …


Structure, Stability, Vibrational, Thermodynamic, And Catalytic Properties Of Metal Nanostructures: Size, Shape, Support, And Adsorbate Effects, Farzad Behafarid Jan 2012

Structure, Stability, Vibrational, Thermodynamic, And Catalytic Properties Of Metal Nanostructures: Size, Shape, Support, And Adsorbate Effects, Farzad Behafarid

Electronic Theses and Dissertations

Recent advances in nanoscience and technology have provided the scientific community with new exciting opportunities to rationally design and fabricate materials at the nanometer scale with drastically different properties as compared to their bulk counterparts. A variety of challenges related to nanoparticle (NP) synthesis and materials characterization have been tackled , allowing us to make more homogenous, well defined, size- and shape-selected NPs, and to probe deeper and more comprehensively into their distinct properties. In this dissertation, a variety of phenomena relevant to nanosized materials are investigated, including the thermal stability of NPs and coarsening phenomena in different environments, the …


The Effect Of Carbon Nanotube/Organic Semiconductor Interfacial Area On The Performance Of Organic Transistors, Narae Kang Jan 2012

The Effect Of Carbon Nanotube/Organic Semiconductor Interfacial Area On The Performance Of Organic Transistors, Narae Kang

Electronic Theses and Dissertations

Organic field-effect transistors (OFETs) have attracted tremendous attention due to their flexibility, transparency, easy processiblity and low cost of fabrication. High-performance OFETs are required for their potential applications in the organic electronic devices such as flexible display, integrated circuit, and radiofrequency identification tags. One of the major limiting factors in fabricating high-performance OFET is the large interfacial barrier between metal electrodes and OSC which results in low charge injection from the metal electrodes to OSC. In order to overcome the challenge of low charge injection, carbon nanotubes (CNTs) have been suggested as a promising electrode material for organic electronic devices. …


Laser Filamentation Interaction With Materials For Spectroscopic Applications, Matthew Weidman Jan 2012

Laser Filamentation Interaction With Materials For Spectroscopic Applications, Matthew Weidman

Electronic Theses and Dissertations

Laser filamentation is a non-diffracting propagation regime consisting of an intense core that is surrounded by an energy reservoir. For laser ablation based spectroscopy techniques such as Laser Induced Breakdown Spectroscopy (LIBS), laser filamentation enables the remote delivery of high power density laser radiation at long distances. This work shows a quasiconstant filament-induced mass ablation along a 35 m propagation distance. The mass ablated is sufficient for the application of laser filamentation as a sampling tool for plasma based spectroscopy techniques. Within the scope of this study, single-shot ablation was compared with multi-shot ablation. The dependence of ablated mass on …


Design, Synthesis, And Biological Evaluation Of Novel Polyamine Transport System Probes And Their Application To Human Cancers, Aaron Muth Jan 2012

Design, Synthesis, And Biological Evaluation Of Novel Polyamine Transport System Probes And Their Application To Human Cancers, Aaron Muth

Electronic Theses and Dissertations

The mammalian polyamine transport system (PTS) has been of interest due to its roles in cancer and maintaining cellular homeostasis. Polyamines are essential growth factors which are tightly controlled via a balance of biosynthesis, metabolism, import, and export. This work focused on the development and biological testing of polyamine transport probes to help understand the molecular requirements of the PTS. This was mediated through the use of a CHO (PTS active) and CHO-MG* (PTS deficient) screen, where compounds demonstrating high toxicity in CHO and low toxicity in CHO-MG* were considered PTS selective. The first chapter focused on the development of …


Study Of Human Activity In Video Data With An Emphasis On View-Invariance, Nazim Ashraf Jan 2012

Study Of Human Activity In Video Data With An Emphasis On View-Invariance, Nazim Ashraf

Electronic Theses and Dissertations

The perception and understanding of human motion and action is an important area of research in computer vision that plays a crucial role in various applications such as surveillance, HCI, ergonomics, etc. In this thesis, we focus on the recognition of actions in the case of varying viewpoints and different and unknown camera intrinsic parameters. The challenges to be addressed include perspective distortions, differences in viewpoints, anthropometric variations, and the large degrees of freedom of articulated bodies. In addition, we are interested in methods that require little or no training. The current solutions to action recognition usually assume that there …