Physics Commons^™

The Early Medieval Transition: Diet Reconstruction, Mobility, And Culture Contact In The Ravenna Countryside, Northern Italy, Anastasia Temkina

USF Tampa Graduate Theses and Dissertations

This research project evaluates the effects of increased mobility and culture contact on dietary practices, and on dietary variation among people buried at two northern Italian sites, Chiunsano di Ficarolo and Chiesazza di Ficarolo, located near the ancient Roman capital of Ravenna and dating 4th to 7th century CE. The Early Medieval period was a time of change, political instability, migration and invasion of the “barbarian” tribes, and diet was not unaffected. In particular, it is hypothesized that a new staple crop, millet, was introduced and that meat consumption had increased. The goal of this research is to use stable …

Characterizing Childhood And Diet In Migration Period Hungary, Kirsten A. Verostick

USF Tampa Graduate Theses and Dissertations

This project investigates children, childhood and diet of two different Migration Period (4^th-8^th century AD) populations, the Gepids and the Avars, in the Great Hungarian Plain. The main goal was to assess whether there are differences in treatment of children and differences in breastfeeding and weaning practices in these distinct sites and populations. Secondarily, this research also focused on characterizing diet for the Gepids and the Avars at four different sites from the Migration Period, to understand how the migration and settling into the region and the assimilation of other groups into the two populations affected their …

It's About Time: Dynamics Of Inflationary Cosmology As The Source Of The Asymmetry Of Time, Emre Keskin

USF Tampa Graduate Theses and Dissertations

This project is about the asymmetry of time. The main source of discontent for physicists and philosophers alike is that even though in every physical theory we developed and/or discovered for explaining how the universe functions, the laws are time reversal invariant; there seems to be a very genuine asymmetry between the past and the future. The aim of this project is to examine several attempts to solve this friction between the laws of physics and the asymmetry and provide a new proposal that makes use of modern cosmology. In the recent history of physics and in contemporary philosophy of …

Functional Magnetic Nanoparticles, James Gass

USF Tampa Graduate Theses and Dissertations

Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields.

Magnetite nanoparticles have been successfully dispersed in a polymer. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogenous and well separated high density dispersion in PMMA. Theoretical studies found in the literature have indicated that surface interface energy …

Multidimensional Spectroscopy Of Semiconductor Quantum Dots, Jason Michael Bylsma

USF Tampa Graduate Theses and Dissertations

The coherent properties of semiconductor nanostructures are inherently difficult to measure and one-dimensional spectroscopies are often unable to separate inhomogeneous and homogeneous linewidths. We have refined and improved a method of performing multidimensional Fourier transform spectroscopy based on four-wave

mixing (FWM) experiments in the box geometry. We have modified our system with broadband beamsplitters in all interferometer arms, high-resolution translation stages and the ability to work in reflection geometry. By improving the phase-stability of our setup and scanning pulse delays with sub-optical cycle precision, we are able to

reproduce 2DFT spectra of GaAs multiple quantum wells. With the FWM signal …

Evanescent Wave Coupling Using Different Subwavelength Gratings For A Mems Accelerometer, Al-Aakhir A. Rogers

USF Tampa Graduate Theses and Dissertations

A novel technique of coupling near-field evanescent waves by means of variable period subwavelength gratings (1.2 ìm and 1.0 ìm), using a 1.55 ìm infrared semiconductor laser is presented for the use of an optical MEMS accelerometer. The subwavelength gratings were fabricated on both glass and silicon substrates respectively.

Optical simulation of the subwavelength gratings was carried out to obtain the maximum coupling efficiency of the two subwavelength gratings; the grating thickness, grating width, and the grating separation were optimized. This was performed for both silicon and glass substrates.

The simulations were used to determine the total system noise, including …

Physical Models Of Amyloid Fibril Assembly, Shannon Elizabeth Hill

USF Tampa Graduate Theses and Dissertations

Formation of large fibers and plaques by amyloid proteins is recognized as the molecular hallmark of an increasing number of human disorders, including Parkinson's disease, Alzheimer's disease and even type II diabetes. The broader objective of my research is to unravel the basic mechanisms that initiate and regulate fibril formation by amyloidogenic proteins. This objective is significant because even basic aspects of how fibril formation proceeds from a soluble, monomeric protein to an insoluble amyloid fibril remain much debated. Furthermore, there is increasingly strong evidence suggesting that intermediates of the aggregation process, with properties distinct from those of mature fibrils, …

Assessment Of The Dependence Of Ventilation Image Calculation From 4d-Ct On Deformation And Ventilation Algorithms, Kujtim Latifi

USF Tampa Graduate Theses and Dissertations

Ventilation imaging using 4D-CT is a convenient and cost effective functional imaging methodology which might be of value in radiotherapy treatment planning to spare functional lung volumes. To calculate ventilation imaging from 4D-CT we must use deformable image registration (DIR). This study validates the DIR methods and investigates the dependence of calculated ventilation on DIR methods and ventilation algorithms.

The first hypothesis is if ventilation algorithms are robust then they will be insensitive to the precise DIR used provided the DIR is accurate. The second hypothesis is that the change in Houndsfield Unit (HU) method is less dependent on the …

Carbon Nanotubes Interactions: Theory And Applications, Adrian Popescu

USF Tampa Graduate Theses and Dissertations

A theoretical framework describing the carbon nanotubes interaction, involving two distinct approaches, is presented. Based on the results obtained practical applications using carbon nanotubes are further proposed.

First a classical approach is employed for different geometrical configurations, such as parallel or concentric carbon nanotubes. For all the cases analytical expressions for the systems potential energies are derived.

The results obtained using the classical approach are used to propose a few practical applications. These applications include a non-contact device for profiling surfaces and a custom telescopic double wall carbon nanotube for nanolithography applications. It is expected that such devices can be …

Novel Magnetic Materials For Sensing And Cooling Applications, Anurag Chaturvedi

USF Tampa Graduate Theses and Dissertations

The overall goals of the present PhD research are to explore the giant magnetoimpedance (GMI) and giant magnetocaloric (GMC) effects in functional magnetic materials and provide guidance on the optimization of the material properties for use in advanced magnetic sensor and refrigeration applications.

GMI has attracted growing interest due to its promising applications in high-performance magnetic sensors. Research in this field is focused on the development of new materials with properties appropriate for practical GMI sensor applications. In this project, we have successfully set up a new magneto-impedance measurement system in the Functional Materials Laboratory at USF. We have established, …

Growth And Characterization Of Thermoelectric Ba8Ga16Ge30 Type-I Clathrate Thin-Films Deposited By Pulsed Dual-Laser Ablation, Robert Harry Hyde

USF Tampa Graduate Theses and Dissertations

The on-going interest in thermoelectric (TE) materials, in the form of bulk and films, motivates investigation of materials that exhibit low thermal conductivity and good electrical conductivity. Such materials are phonon-glass electron-crystals (PGEC), and the multi-component type-I clathrate Ba₈Ga₁₆Ge₃₀ is in this category. This work reports the first investigation of Ba₈Ga₁₆Ge₃₀ films grown by pulsed laser deposition (PLD).

This dissertation details the in-situ growth of polycrystalline type-I clathrate Ba₈Ga₁₆Ge₃₀ thin-films by pulsed laser ablation. Films deposited using conventional laser ablation produced films that contained a …

Device Physics Of Solution Processable Solar Cells, Jason Erik Lewis

USF Tampa Graduate Theses and Dissertations

This Ph.D work reports the studies of photovoltaic devices produced by solution processable methods. Two material systems are of interest: one is based on organic semiconductors, and another on organic/inorganic hybrid composites. Specifically, organic photovoltaic (OPV) devices are made using photoactive materials consisted of a p-conjugated polymer [Poly(3-hexylthiophene), or P3HT] and fullerene derivative [phenyl-C60-butric acid methyl ester, or PCBM] in a bulk heterojunction (BHJ) structure of donor/acceptor network. On the other hand, hybrid photovoltaic (HPV) devices are made from blend of quantum dots and p-conjugated polymers. The QD material presented here are of the lead sulfide (PbS), and lead selenide …

A Study Of Complex Systems: From Magnetic To Biological, Douglas Carroll Lovelady

USF Tampa Graduate Theses and Dissertations

This work is a study of complex many-body systems with non-trivial interactions. Many such systems can be described with models that are much simpler than the real thing but which can still give good insight into the behavior of realistic systems. We take a look at two such systems. The first part looks at a model that elucidates the variety of magnetic phases observed in rare-earth heterostructures at low temperatures: the six-state clock model. We use an ANNNI-like model Hamiltonian that has a three dimensional parameter space and yields two-dimensional multiphase regions in this space. A low-temperature expansion of the …

Problems In Classical Potential Theory With Applications To Mathematical Physics, Erik Lundberg

USF Tampa Graduate Theses and Dissertations

In this thesis we are interested in some problems regarding harmonic functions. The topics are divided into three chapters.

Chapter 2 concerns singularities developed by solutions of the Cauchy problem for a holomorphic elliptic equation, especially Laplace's equation. The principal motivation is to locate the singularities of the Schwarz potential. The results have direct applications to Laplacian growth (or the Hele-Shaw problem).

Chapter 3 concerns the Dirichlet problem when the boundary is an algebraic set and the data is a polynomial or a real-analytic function. We pursue some questions related to the Khavinson-Shapiro conjecture. A main topic of interest is …

Atomistic Studies Of Shock-Wave And Detonation Phenomena In Energetic Materials, Mikalai Budzevich

USF Tampa Graduate Theses and Dissertations

The major goal of this PhD project is to investigate the fundamental properties of energetic materials, including their atomic and electronic structures, as well as mechanical properties, and relate these to the fundamental mechanisms of shock wave and detonation propagation using state-of-the-art simulation methods. The first part of this PhD project was aimed at the investigation of static properties of energetic materials (EMs) with specific focus on 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). The major goal was to calculate the isotropic and anisotropic equations of state for TATB within a range of compressions not accessible to experiment, and to make predictions of anisotropic sensitivity …

Biological Effective Dose (Bed) Distribution Matching For Obtaining Brachytherapy Prescription Doses & Dosimetric Optimization For Hybrid Seed Brachytherapy, Jakub Pritz

USF Tampa Graduate Theses and Dissertations

Radioactive seed implant brachytherapy is a common radiotherapy treatment method for prostate cancer. In current clinical practice, a seed consists of a single isotope, such as ¹²⁵I or ¹⁰³Pd. A seed containing a mixture of two isotopes has been proposed for prostate cancer treatment. This study investigates a method for defining a prescription dose for new seed compositions based on matching the biological equivalent dose (BED) of a reference plan.

Ten prostate cancer cases previously treated using single isotope seeds (5 using ¹²⁵I seeds and 5 using ¹⁰³Pd seeds) were selected for this study. Verification of …

Libs And Lite Emission Based Laser Remote Sensing Of Chemical Species And Enhanced Modeling Of Atmospheric Absorption, Dzianis V. Pliutau

USF Tampa Graduate Theses and Dissertations

Laser-Induced Breakdown spectroscopy (LIBS) and Laser-Induced Thermal Emission (LITE) emission based laser remote sensing were investigated with the application to the remote measurements of trace chemical species. In particular, UVvisible LIBS and Mid-IR LITE systems were developed and measurements of remote targets and chemical surfaces were studied. The propagation through the atmosphere of the multi-wavelength backscattered LIBS and LITE optical spectrum with atmospheric absorption effects on the returned lidar signal was investigated. An enhanced model of the atmospheric effects on emission-based laser-remote sensing was developed and found to be consistent and in agreement with our experimental results.

LITE measurements were …

Optical Design Of Beam Shaping Optics For Camera Probe And Led Light Illumination Used For Minimally Invasive Abdominal Surgery, Weiyi He

USF Tampa Graduate Theses and Dissertations

The optical design of a LED illuminator and camera imaging system were studied for potential use in a small medical "robotic type" probe to be used for minimally invasive abdominal surgery. Beam shaping optical reflectors were studied to increase the intensity distribution of the LED beam directed toward a close-by target surface. A CMOS/CCD camera and lens was used to image the targeted area. In addition, extensive optical ray tracing simulations were made to predict the intensity patterns. The experimental measurements and ray tracing simulations were in good agreement, and indicated that 20 degree cone reflectors for the LED sources …

Magnetocaloric Effect In Thin Films And Heterostructures, Christopher Bauer

USF Tampa Graduate Theses and Dissertations

The goals of this work are the optimization of the magnetocaloric effect in Gadolinium thin film structures. We approach this issue from two directions, that of process optimization and of interface effects. Past results showed Gd₂O₃ in our Gadolinium thin films, and the presence of such oxide seemed to grow with the temperature at which the film was grown or annealed. Comparison of samples grown without chamber gettering to those that were gettered show differences in their structural and magnetic properties, and we conclude that gettering is an effective step in enhancing the quality of Gd thin …

Evanescent Field Absorption Sensing Using Sapphire Fibers, Michael Grossman

USF Tampa Graduate Theses and Dissertations

This thesis explores the application of coiled sapphire multimode optical fibers for evanescent wave chemical sensing in both the visible spectrum and the near infrared. As has been suggested in the literature pertaining to silica fibers, bending converts low-order modes to high order ones, which leads to more evanescent absorption and thus a more sensitive chemical detector. By coiling the fiber many times, it was expected that even greater sensitivity would be attained.

Experiments were performed to investigate the sensor response to different solutions and to characterize this response. In the first of three experiments, the large absorption peak of …

Dynamic Monitoring Of Cytotoxicity Using Electric Cell Substrate Impendence Sensing, Alfred Brian Wafula

USF Tampa Graduate Theses and Dissertations

Electric cell-substrate impedance sensing (ECIS) pioneered by Giaever and Keese is suitable for continuous, automatic and real-time cell attachment analysis. ECIS is a novel electrical method to study, in real time, many of the activities of animal cells when grown in tissue culture. These include morphological changes, cell locomotion, and other behaviors directed by the cell's cytoskeleton. One of the most direct ECIS measurements is that of the attachment and spreading behaviors of cells. These measurements allow one to study and quantify the interaction of cultured cells with extracellular matrix (ECM) proteins and other macromolecules continuously and in real time. …