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2013

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Articles 10291 - 10320 of 11462

Full-Text Articles in Physical Sciences and Mathematics

Response Of A Small Population Of Greater Sage-Grouse To Tree Removal: Implications Of Limiting Factors, S. Nicole Frey, Rachel Curtis, Kevin Heaton Jan 2013

Response Of A Small Population Of Greater Sage-Grouse To Tree Removal: Implications Of Limiting Factors, S. Nicole Frey, Rachel Curtis, Kevin Heaton

Human–Wildlife Interactions

In Utah, greater sage-grouse (Centrocercus urophasianus; hereafter, sage-grouse) range has been reduced to 50% of what is considered historical availability due to habitat degradation and loss. In an effort to improve sage-grouse habitat in southern Utah, the U.S. Bureau of Land Management (BLM) conducted a tree-removal treatment in 2005. We conducted a study to determine if (a) the tree-removal treatment was effective at creating new sage-grouse habitat, and (b) if characteristics of used habitat were similar to those reported in previous literature. The treatment resulted in increased abundance of grasses and forbs. Additionally, shrub percentage cover and height …

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Influence Of Vectors' Risk-Spreading Strategies And Environmental Stochasticity On The Epidemiology And Evolution Of Vector-Borne Diseaes: The Example Of Chagas' Disease, Christopher Kribs, Perrine Pelosse, Marine Ginoux, Jorge E. Rabinovich, Sebastien Gourbiere, Frederic Menu Jan 2013

Influence Of Vectors' Risk-Spreading Strategies And Environmental Stochasticity On The Epidemiology And Evolution Of Vector-Borne Diseaes: The Example Of Chagas' Disease, Christopher Kribs, Perrine Pelosse, Marine Ginoux, Jorge E. Rabinovich, Sebastien Gourbiere, Frederic Menu

Mathematics Faculty Publications

Insects are known to display strategies that spread the risk of encountering unfavorable conditions, thereby decreasing the extinction probability of genetic lineages in unpredictable environments. To what extent these strategies influence the epidemiology and evolution of vector-borne diseases in stochastic environments is largely unknown. In triatomines, the vectors of the parasite Trypanosoma cruzi, the etiological agent of Chagas’ disease, juvenile development time varies between individuals and such variation most likely decreases the extinction risk of vector populations in stochastic environments. We developed a simplified multi-stage vector-borne SI epidemiological model to investigate how vector riskspreading strategies and environmental stochasticity influence the …

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Investigation Of Dominant States In The Collisions Of Ar Vii And Kr Xxiv With H_2 And He Targets, Abdel Aziz Habib, Alaa Abo Zalam, Hassan Ramadan Jan 2013

Investigation Of Dominant States In The Collisions Of Ar Vii And Kr Xxiv With H_2 And He Targets, Abdel Aziz Habib, Alaa Abo Zalam, Hassan Ramadan

Turkish Journal of Physics

In thermal plasma, the ion--atom collisions proceed most probably through resonance processes. One of the important processes is the resonant transfer excitation followed by emission of X-rays (RTEX), which causes self-cooling for plasma. In addition, it is identical to the dielectronic recombination (DR) in electron-ion collisions. The present work deals with the calculation of DR cross-sections (\sigma^{DR}s) and DR rate coefficients (\alpha^{DR}s) as well as RTEX cross-sections (\sigma^{RTEX}s) for Mg-like ions [Ar^{6+} and Kr^{24+}] with L-shell and K-shell excitation for \Deltan = 0 and \Delta n \neq 0. Comparison between the present results and other calculations for the rates are …

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Defect Studies In Strain-Relaxed Si_{1-X}Ge_X Alloys, Şeref Kalem Jan 2013

Defect Studies In Strain-Relaxed Si_{1-X}Ge_X Alloys, Şeref Kalem

Turkish Journal of Physics

Raman light scattering, low-temperature photoluminescence, light-scattering tomography, and hydrogenation were used to investigate optical properties of defects in strain-relaxed Si_{1-x}Ge_x (0.05 \le x \le 0.50) alloys. The photoluminescence emission was characterized by typical zero-phonon, phonon-assisted, and dislocations-related emissions, which are dependent on Ge composition x. However, luminescence spectra exhibited above band-gap features, which are likely associated with the presence of Si-rich regions in the alloys. The results are correlated with light-scattering tomography, revealing the presence of dislocations and Si precipitates. The excess peak at 519 cm^{-1} in Ge-rich samples is supportive of this observation. At low Ge content, a dislocation-related …

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Structure And Odd--Even Staggering Of Mo, Ru, And Pd Even--Even Nuclei In The Framework Of Ibm-1, Vidya Devi Jan 2013

Structure And Odd--Even Staggering Of Mo, Ru, And Pd Even--Even Nuclei In The Framework Of Ibm-1, Vidya Devi

Turkish Journal of Physics

In this study, we employed the interacting boson model (IBM-1) to determine the most appropriate Hamiltonian for the study of ^{94-108}Mo, ^{94-110}Ru, and ^{96-114}Pd isotopes in the region A cong 100. The soft rotor formula (SRF) calculation was also done to study these isotopes. Using the best fit values of parameters to construct the Hamiltonian of the IBM-1 we calculated energy levels and B(E2) values for number of transitions in Mo, Ru, and Pd nuclei. The results obtained from the IBM-1 and SRF were compared with experimental data and IBM-2 calculation. On comparing the results it was observed that they …

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Study Of Solid-State Stability Of The Zoto Binary System, Sandeep A. Waghuley Jan 2013

Study Of Solid-State Stability Of The Zoto Binary System, Sandeep A. Waghuley

Turkish Journal of Physics

The ZOTO binary system contains different compositions of zinc oxide (ZnO) and tin oxide (SnO_2). These are important semiconductors and have been intensively explored for various applications. SnO_2, ZnO, and different mole ratios (70:30, 40:60, 30:70, and 20:80 SnO_2:ZnO) of the ZOTO system were prepared through proper thermal treatment in powder form. The comparative solid-state stability was investigated using thermogravimetric and differential thermal analysis (TG-DTA). The stability study showed that the SnO_2 material absorbs much lower heat (Ea = -72.06 kJ/g mol) compared with ZnO and their compositions. Thus the SnO_2 material shows stability at near room temperature operation. The …

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Numerical Experiments For Determining Laser-Induced Temperature Fields, Lyubomir Kostadinov Lazov, Nikolay Angelov Petrov Jan 2013

Numerical Experiments For Determining Laser-Induced Temperature Fields, Lyubomir Kostadinov Lazov, Nikolay Angelov Petrov

Turkish Journal of Physics

Based on the equation of energy balance and the equation of heat conductivity with the help of specialized software, tentative engineering calculations were performed for the process of laser marking by melting and structural changes. The functional capabilities of the software product were examined. Distribution of temperature by layers for samples of tool steel was obtained.

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Regular And Chaotic Motions In Hénon-Heiles Like Hamiltonian, Idugba Mathias Echi, Alexander Nwabeze Amah, Emmanuel Anthony Jan 2013

Regular And Chaotic Motions In Hénon-Heiles Like Hamiltonian, Idugba Mathias Echi, Alexander Nwabeze Amah, Emmanuel Anthony

Turkish Journal of Physics

The dynamics of a system subjected to a potential equal to the sum of the Hénon--Heiles potential and that of hydrogen in an electric field was studied. The 4 Hamilton's equations of motion follow from the Hamiltonian and they were integrated numerically using the Runge-Kutta fourth order method. The Poincaré surface of a section fixed at x = 0 and px> 0 was used to reduce the phase space to a 2-dimensional plane. The analysis of the Poincaré surface, the Lyapunov exponent, and the autocorrelation shows that as the constant of motion, E, increases from 0.30 to 0.45, the dynamics …

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Quasi-Exact Thermodynamic Properties Of A Relativistic Spin-Zero System Under Cornell And Generalized Morse Potentials, Bentol Hoda Yazarloo, Hassan Hassanabadi, Saber Zarrinkamar Jan 2013

Quasi-Exact Thermodynamic Properties Of A Relativistic Spin-Zero System Under Cornell And Generalized Morse Potentials, Bentol Hoda Yazarloo, Hassan Hassanabadi, Saber Zarrinkamar

Turkish Journal of Physics

The thermodynamic properties of a relativistic spin-zero system are investigated via the Klein-Gordon equation under the Cornell and generalized Morse potentials. In particular, the partition function and mean and free energies are calculated and their behavior versus variations of the potential coefficients is presented.

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Stable Isotope-Based Reconstruction Of Oligo-Miocene Paleoenvironment And Paleohydrology Of Central Anatolian Lake Basins (Turkey), Tina Lüdecke, Tamás Mikes, Fuat Bora Rojay, Michael A. Cosca, Andreas Mulch Jan 2013

Stable Isotope-Based Reconstruction Of Oligo-Miocene Paleoenvironment And Paleohydrology Of Central Anatolian Lake Basins (Turkey), Tina Lüdecke, Tamás Mikes, Fuat Bora Rojay, Michael A. Cosca, Andreas Mulch

Turkish Journal of Earth Sciences

Isotope geochemistry of lacustrine carbonate represents a powerful tool to reconstruct paleoclimatic and paleoenvironmental conditions. Here, we present a comprehensive set of long-term oxygen (delta^{18}O) and carbon (delta^{13}C) stable isotope records from 5 Chattian to Burdigalian lacustrine sequences distributed over the Central Anatolian Plateau. Field relationships combined with stable isotope geochemistry indicate a relatively humid subtropic Late Oligocene climate with an environment characterized by large, temporally open freshwater lakes. Approximately during the middle Aquitanian, a 4%o-5%o increase in lake delta^{18}O values indicates changes in regional climate including more arid conditions and an increasing dominance of closed saline lake conditions in …

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Spin-One Dkp Equation In The Presence Of Nonminimal Vector Woods-Saxon Potential In (1 + 1) Dimensions, Hassan Hassanabadi, Zahra Molaee, Saber Zarrinkamar Jan 2013

Spin-One Dkp Equation In The Presence Of Nonminimal Vector Woods-Saxon Potential In (1 + 1) Dimensions, Hassan Hassanabadi, Zahra Molaee, Saber Zarrinkamar

Turkish Journal of Physics

The Duffin-Kemmer-Petiau equation in the presence of a nonminimal vector Woods-Saxon potential is solved for spin-one particles via the Nikiforov-Uvarov method. The reflection and transmission coefficients of the general form of the DKP equation in the presence of a nonminimal vector interaction are discussed.

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Molecular Dynamic Simulation On Iron Corrosion-Reduction In High Temperature Molten Lead-Bismuth Eutectic, Artoto Arkundato, Zaki Su'ud, Mikrajuddin Abdullah, Widayani Sutrisno Jan 2013

Molecular Dynamic Simulation On Iron Corrosion-Reduction In High Temperature Molten Lead-Bismuth Eutectic, Artoto Arkundato, Zaki Su'ud, Mikrajuddin Abdullah, Widayani Sutrisno

Turkish Journal of Physics

Molecular dynamic simulation on iron in high-temperature molten lead-bismuth eutectic has been carried out to investigate the iron corrosion and its mitigation. The aim of the work is to investigate the corrosion and evaluate proper oxygen content of injection for significant and effective reduction. To study the phenomena we calculated the diffusion coefficients, radial distribution functions and mean square displacement of iron, and also observed the micro-structure of iron before and after oxygen injection into coolant. The present calculation shows that a significant and effective reduction of corrosion can be achieved by injection of 7.68 \times 10^{-2}-1.55 \times 10^{-1} wt\% …

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Improved Hilbert Moment Thermal Qcd Sum Rules For B_S Meson And Stability With Respect To Moment Parameter, Elşen Veli̇, Gülşah Kaya, Arzu Türkan, Eni̇s Yazici Jan 2013

Improved Hilbert Moment Thermal Qcd Sum Rules For B_S Meson And Stability With Respect To Moment Parameter, Elşen Veli̇, Gülşah Kaya, Arzu Türkan, Eni̇s Yazici

Turkish Journal of Physics

In this paper, we deal with the temperature dependence of the leptonic decay constant and mass of B_s meson in the framework of the Hilbert moment QCD sum rule. In our calculations, we improve the thermal QCD sum rules, taking into account the thermal spectral density and the perturbative 2-loop order corrections to the correlation function. Moreover, we investigate the stability of the results with respect to the Hilbert moment parameter. Our numerical calculations demonstrate that the mass and decay constant are insensitive to the variation of temperature up to T \cong 100 MeV; however, after this value, they start …

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Effect Of Stepwise Replacement Of Lif By Zno On Structural And Optical Properties Of Lif.B_2o_3 Glasses, Susheel Arora, Virender Kundu, Dev Raj Goyal, Anup Singh Maan Jan 2013

Effect Of Stepwise Replacement Of Lif By Zno On Structural And Optical Properties Of Lif.B_2o_3 Glasses, Susheel Arora, Virender Kundu, Dev Raj Goyal, Anup Singh Maan

Turkish Journal of Physics

Zinc fluoroborate glasses with compositions xZnO.(40 - x) LiF.60B_2O_3 (x = 0, 5, 10, 15, and 20) were synthesized by the melt-quench method. The amorphous nature of the glassy samples was confirmed by XRD analysis. The nature of the bonds formed and the role of various species in the composition of the glasses were examined using FTIR spectroscopy. FTIR analysis showed shifting of an absorption band with the addition of ZnO. A UV-visible study was carried out to calculate the optical band gap energy, E_gIt was found that E_gdecreased with increase in concentration of ZnO up to x = 15 …

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Planar Waveguide With Left-Handed Material Guiding Film For Refractometry Applications, Taher M. El-Agez, Sofyan A. Taya, Mohamed M. Shabat, Hani M. Kullab Jan 2013

Planar Waveguide With Left-Handed Material Guiding Film For Refractometry Applications, Taher M. El-Agez, Sofyan A. Taya, Mohamed M. Shabat, Hani M. Kullab

Turkish Journal of Physics

A symmetric 3-layer slab waveguide with a left-handed material as a guiding layer is examined analytically for cover refractive index detection. The TM mode dispersion relation of the proposed waveguide is investigated. The sensitivity of the proposed sensor to changes in the cover refractive index and the power flowing within each layer are presented. Some unusual features are found; for example, the sensitivity of the proposed sensor is negative. Moreover, the sensitivity improvement compared with the conventional 3-layer waveguide sensor is approximately a factor of 6.

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Theoretical Modeling And Numerical Solutions Of Some Standard Thermoluminescence Detector Crystals, Erdem Uzun Jan 2013

Theoretical Modeling And Numerical Solutions Of Some Standard Thermoluminescence Detector Crystals, Erdem Uzun

Turkish Journal of Physics

MCP-100, MYS-N, MTS-7, MTS-100, and MCP-N standard thermoluminescence detector materials are annealed and irradiated. Glow curves and all trap parameters are determined. For these materials new theoretical energy band models are suggested and differential equations governing the charge carrier traffics are derived. The equations are solved by using computer-based numerical methods. During the simulations, experimental data measured in the previous step are given to computer code as the initial conditions. Experimental and numerical results show that the electron-band structures of standard thermoluminescence crystals are represented fairly well by the suggested models.

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Vacuum Properties Of Tarla, Hüsnü Aksakal, Ertan Arikan, Zafer Nergi̇z Jan 2013

Vacuum Properties Of Tarla, Hüsnü Aksakal, Ertan Arikan, Zafer Nergi̇z

Turkish Journal of Physics

The Turkish Accelerator and Radiation Laboratory at Ankara (TARLA) is a part of the Turkish Accelerator Center project, which was designed to produce an infrared free electron laser in the wavelength band of 2-250 mu m. The beamline of TARLA consists of 4 major sections: injector, beam transport line with linacs, optical cavities, and dump. All system components must be kept under ultrahigh vacuum standards to prevent beam scattering with residual gas. In the present study, the vacuum requirements of the beamline are defined and simulation vacuum and gas flow in the accelerator are presented.

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Synthesis And Optical Characterization Of Zn_{1-X}Mg_Xs: Eu Nanoparticles, Alexander Nwabueze Amah, Audu Onoja, Richard Akpagher Jan 2013

Synthesis And Optical Characterization Of Zn_{1-X}Mg_Xs: Eu Nanoparticles, Alexander Nwabueze Amah, Audu Onoja, Richard Akpagher

Turkish Journal of Physics

Zn_{1-x}Mg_xS: Eu^{3+} nanoparticles were synthesized by a facile co-precipitation technique with varying magnesium concentrations (0 =< x =< 0.20). X-ray diffraction results showed a mixture of cubic and hexagonal structures. There was an observed peak shift towards higher angles, decrease in peak intensities, disappearance of other peaks, and increase in diffraction peak broadening as Mg concentration increased. The estimated average particle sizes ranged from 2.0 nm to 8.79 nm. Scanning electron microscopy results showed smooth and uniform surface morphology. Energy dispersive X-ray studies indicated that the samples contained mainly Zn, S, and Eu because of the low detection limit for Mg. UV-Vis absorption spectrophotometer results showed a blue shift in energy due to quantum confinement as Mg concentration increased.

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Agroforestry And Smallholder Farmers: Climate Change Adaptation Through Sustainable Land Use, Colin Mccabe Jan 2013

Agroforestry And Smallholder Farmers: Climate Change Adaptation Through Sustainable Land Use, Colin Mccabe

Capstone Collection

Agriculture in the developing world will be extremely hard hit by climate change, and smallholder farmers in Least Developed Countries (LDCs) are among the most vulnerable to its impacts. There is a range of agricultural adaptations to climate change, and each context demands a unique appraisal of impacts and adaptations based on specific geography, local climate variability and expected change, and social conditions. The term “climate-smart agriculture” (CSA) has come to embody a set of practices in crop and livestock cultivation that 1) reduce greenhouse gas emissions (climate change mitigation), 2) build resilience to the impacts of climate change for …

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Optimization Of Laser Marking With The Help Of Simulation Models, Lyubomir Kostadimov Lazov, Nikolay Angelov Petrov Jan 2013

Optimization Of Laser Marking With The Help Of Simulation Models, Lyubomir Kostadimov Lazov, Nikolay Angelov Petrov

Turkish Journal of Physics

This article covers the results of several numerical experiments carried out with specific software working under MATLAB for marking of tool steel and electronic elements. CuBr and Nd:YAG lasers were used in this study. Simulations with 3 different durations of pulse of laser radiation were achieved. Numerical calculations were performed with values (for laser sources and technological parameters) based on real experiments.

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A Fission Model Approach To Alpha Decay And Cluster Radioactivity Of Dy, Er, And Yb Isotopes, Kizhakkath Kalam Girija, Antony Joseph Jan 2013

A Fission Model Approach To Alpha Decay And Cluster Radioactivity Of Dy, Er, And Yb Isotopes, Kizhakkath Kalam Girija, Antony Joseph

Turkish Journal of Physics

Rare earth nuclei are probable candidates for exhibiting cluster radioactivity. In the present work, a theoretical study of alpha decay and heavy cluster emission from Dy, Er, and Yb nuclei in the mass range 150 < A < 190 has been carried out in a fission model approach. Some of the proton-rich isotopes of these nuclei are found to have long half-lives, but within the measurable range. Many of the neutron-rich isotopes under consideration are far from beta stability and the most probable light clusters predicted are highly exotic in nature and the corresponding half-lives are extremely short. However, the decays of most probable heavy clusters predicted have half-lives in the measurable range. The calculations on neutron-rich isotopes indicate the emergence of new magic numbers for protons and neutrons. The centrifugal barrier effect on decay rate of some proton-rich Er isotopes is also investigated.

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Bound States And The Oscillator Strengths For The Klein-Gordon Equation Under Möbius Square Potential, Hassan Hassanabadi, Bentol Hoda Yazarloo, Saber Zarrinkamar Jan 2013

Bound States And The Oscillator Strengths For The Klein-Gordon Equation Under Möbius Square Potential, Hassan Hassanabadi, Bentol Hoda Yazarloo, Saber Zarrinkamar

Turkish Journal of Physics

The Klein-Gordon equation under the equal scalar and vector Möbius square potentials in D-dimensions is solved by using the Nikiforov-Uvarov method. The energy eigenvalues and the corresponding eigenfunctions are obtained and numerically calculated. The oscillator strengths are determined and discussed in terms of parameters of the system.

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Analyses Of Elastically Scattered Charged Pions From Calcium Isotopes And The ^{48}Ca-^{54}Fe Isotone At 180 Mev, Zuhair Fayyad Mahmoud Shehadeh Jan 2013

Analyses Of Elastically Scattered Charged Pions From Calcium Isotopes And The ^{48}Ca-^{54}Fe Isotone At 180 Mev, Zuhair Fayyad Mahmoud Shehadeh

Turkish Journal of Physics

The elastic scattering of 180 MeV positively and negatively charged pions, incident on a set of calcium isotopes and the isotone ^{48}Ca - ^{54}Fe, has been analyzed within the framework of a recently updated simple local optical potential. This potential, particularly at the tail region, has been originally determined from available phase shifts using inverse scattering theory and the Klein--Gordon equation as a guide. The analysis is carried out with and without considering the squared potential term in the Klein-Gordon equation. Coulomb effects are accounted for by implementing Stricker's prescription. The numerical results for the angular distributions with isotopic and …

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Accompanying Figures For "Rotation Periods Of Small Trojan Asteroids", Linda French Jan 2013

Accompanying Figures For "Rotation Periods Of Small Trojan Asteroids", Linda French

Scholarship

No abstract provided.

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Applications Of Agent Based Approaches In Business: A Three Essay Dissertation, Shankar Prawesh Jan 2013

Applications Of Agent Based Approaches In Business: A Three Essay Dissertation, Shankar Prawesh

USF Tampa Graduate Theses and Dissertations

The goal of this dissertation is to investigate the enabling role that agent based simulation plays in business and policy. The aforementioned issue has been addressed in this dissertation through three distinct, but related essays. The first essay is a literature review of different research applications of agent based simulation in various business disciplines, such as finance, economics, information systems, management, marketing and accounting. Various agent based simulation tools to develop computational models are discussed. The second essay uses an agent-based simulation approach to study important properties of the widely used most popular news recommender systems (NRS). This essay highlights …

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Ecology Of The Late Neogene Extinctions: Perspectives From The Plio-Pleistocene Of Florida, Shubhabrata Paul Jan 2013

Ecology Of The Late Neogene Extinctions: Perspectives From The Plio-Pleistocene Of Florida, Shubhabrata Paul

USF Tampa Graduate Theses and Dissertations

The ecological impact of past extinction events is one of the central issues in paleobiology. In face of present environmental changes, a better understanding of past extinctions will enable us to identify the magnitude of biodiversity crises and their underlying processes. The Late Neogene was a time of extraordinary climatic reorganization, including Northern Hemisphere glaciation, the rise of the Central American Isthmus, and associated changes in environmental conditions. Therefore, the Late Neogene extinctions of marine molluscs of South Florida present an ideal platform to examine the interaction between environmental changes and biotic response. In the present study, three different aspects …

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Synthesis And Investigations Of Type I And Ii Clathrates Of Group 14, Michael Blosser Jan 2013

Synthesis And Investigations Of Type I And Ii Clathrates Of Group 14, Michael Blosser

USF Tampa Graduate Theses and Dissertations

Clathrates are a class of new materials that have an open-framework structure that allows guest atoms or molecules to be enclosed inside of their polyhedral framework. Varying the number, weight, and size of the guest species in a particular framework allows one to alter the physical properties of the clathrate. This relationship enables one to further the fundamental understanding of the physics and chemistry of the clathrate structure and use this knowledge to "tune" certain properties. This "tunability" of inorganic clathrates is of great interest as it allows one to optimize their physical properties; making them promising candidates for a …

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Characterizing Interactions Between Chromophores In Synthetic And Natural Macromolecular Films Via Maldi-Tof, Ibf And Dielectric Analyzer, Parul Jain Jan 2013

Characterizing Interactions Between Chromophores In Synthetic And Natural Macromolecular Films Via Maldi-Tof, Ibf And Dielectric Analyzer, Parul Jain

USF Tampa Graduate Theses and Dissertations

With the emergence of Matrix Assisted Laser Desorption/Ionization-Time-of-flight as a tool for diagnosis of diseases via proteomics, there is an increasing need for greater sensitivity. Analysis of peptides by MALDI-TOF-MS is affected by sample formulation and spotting onto a MALDI target. This dissertation investigates a novel MALDI sample preparation technique, Induction Based Fluidics (IBF), for depositing precise volumes (pL to nL) of samples onto the target. We have seen that while using IBF, the induced electric field accompanying deposition enhances matrix crystallization yielding smaller crystals with more homogeneity, as compared to conventional manual micropipette (MP) depositions. An investigation of the …

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Synthesis And Properties Of Polymer Nanocomposites With Tunable Electromagnetic Response, Kristen Lee Stojak Jan 2013

Synthesis And Properties Of Polymer Nanocomposites With Tunable Electromagnetic Response, Kristen Lee Stojak

USF Tampa Graduate Theses and Dissertations

Multifunctional polymer nanocomposites (PNCs) are attractive for the design of tunable RF and microwave components such as flexible electronics, attenuators, and antennas due to cost-effectiveness and durability of polymeric matrices. In this work, three separate PNCs were synthesized. Magnetite (Fe3O4) and cobalt ferrite (CFO) nanoparticles, synthesized by thermal decomposition, were used as PNC fillers. Polymers used in this work were a commercial polymer provided by the Rogers Corporation (RP) and polyvinylidene fluoride (PVDF). PNCs in this thesis consist of Fe3O4 in RP, CFO in RP, and Fe3O4 in PVDF. Characterization techniques for determining morphology of the nanoparticles, and their resulting …

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Effectiveness Of Propensity Score Methods In A Multilevel Framework: A Monte Carlo Study, Aarti P. Bellara Jan 2013

Effectiveness Of Propensity Score Methods In A Multilevel Framework: A Monte Carlo Study, Aarti P. Bellara

USF Tampa Graduate Theses and Dissertations

Propensity score analysis has been used to minimize the selection bias in observational studies to identify causal relationships. A propensity score is an estimate of an individual's probability of being placed in a treatment group given a set of covariates. Propensity score analysis aims to use the estimate to create balanced groups, akin to a randomized experiment. This study used Monte Carlo methods to examine the appropriateness of using propensity score methods to achieve balance between groups on observed covariates and reproduce treatment effect estimates in multilevel studies. Specifically, this study examined the extent to which four different propensity score …

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