Biological and Chemical Physics Commons^™

Commissioning Of Micro-Cube Thermoluminescent Dosimeters For Small Field Dosimetry Quality Assurance In Radiotherapy, Brandon Luckett

Dissertations and Theses (Open Access)

Small field dosimetry presents complications and uncertainties that could be circumvented by using detectors which are smaller than the radiation field. This study evaluates the reproducibility and accuracy of TLD micro-cubes for use in stereotactic radiosurgery (SRS) remote auditing quality assurance (QA) for treatment centers participating in clinical trials. This study tested the hypothesis that TLD micro-cubes could be commissioned to evaluate small field dosimetry, and provide reproducibility within 3%, as well as assure agreement between measured dose and calculated doses to within 5%.

The aims of this thesis were to characterize and commission TLD micro-cubes as well as to …

Modeling Proton Relative Biological Effectiveness Using Monte Carlo Simulations Of Microdosimetry, Mark A. Newpower

Dissertations and Theses (Open Access)

Proton therapy is a radiotherapy modality that can offer a better physical dose distribution when compared to photon radiotherapy by taking advantage of the Bragg peak, a narrow region of rapid energy loss. Proton therapy is also known to offer an enhanced relative biological effectiveness (RBE) compared to photons. In the current clinical standard, RBE is fixed at 1.1 at all points along the proton beam, meaning protons are assumed to require 10% less dose than photons to achieve target coverage and organ at risk (OAR) sparing. However, there is mounting clinical evidence, and a significant number of in vitro …

Quantifying Uncertainty In A Measurement-Based Assessment Of Relative Biological Effectiveness In Carbon Ion Radiotherapy, Shannon Hartzell

Dissertations and Theses (Open Access)

One of the largest inconsistencies in dose delivered during carbon ion therapy is due to uncertainties in relative biological effectiveness (RBE), a value that is calculated via one of several clinically implemented algorithms. This study investigates the uncertainty in measured microdosimetric parameters for RBE calculation by the Microdosimetric Kinetic Model (MKM), Repair Misrepair Fixation model (RMF), and Local Effect Model I (LEM) using a Tissue Equivalent Proportional Counter (TEPC).

Microdosimetric spectra, kinetic energy spectra, and dose fragment contributions were calculated using Monte Carlo (GEANT IV) for monoenergetic and SOBP carbon beams of clinical energy. From microdosimetric spectra, lineal energy values …

A Comprehensive Assessment Of The Low-Temperature Thermal Properties And Thermodynamic Functions Of Ceo2, Tyler D. Morrison, Elizabeth Sooby Wood, Phillippe F. Weck, Eunja Kim, Sung Oh Woo, Andrew T. Nelson, Donald G. Naugle

Physics & Astronomy Faculty Research

Reported is an experimental and computational investigation of the low temperature heat capacity, thermodynamic functions, and thermal conductivity of stoichiometric, polycrystalline CeO2. The experimentally measured heat capacity at T... (See full abstract in article).

Computational Investigation Of The Interactions Between Bioactive Compounds And Biological Assemblies, Tye D. Martin

Biomedical Engineering ETDs

Small, biologically active molecules with unique properties and applications are potential solutions to a wide range of threats to global health including infectious agents and neurodegenerative disease. Experimental studies on a class of oligomeric p-phenylene ethynylenes (OPEs) have shown potential both as bioactive antimicrobials and fluorescent sensing agents for tracking amyloid-β (Aβ) aggregates found in Alzheimer’s Disease (AD). A second type of small molecule with potential applications in AD therapy, curcumin, has been found to interfere with Aβ fibril growth. Curcumin also attenuates Aβ-membrane interactions and Aβ toxicity. Our goal has been to use computational techniques to better understand the …

Quantifying Complex Systems Via Computational Fly Swarms, Troy Taylor

Senior Theses

Complexity is prevalent both in natural and in human-made systems, yet is not well understood quantitatively. Qualitatively, complexity describes a phenomena in which a system composed of individual pieces, each having simple interactions with one another, results in interesting bulk properties that would otherwise not exist. One example of a complex biological system is the bird flock, in particular, a starling murmuration. Starlings are known to move in the direction of their neighbors and avoid collisions with fellow starlings, but as a result of these simple movement choices, the flock as a whole tends to exhibit fluid-like movements and form …

Magnetic Borophenes From An Evolutionary Search, Meng-Hong Zhu, Xiao-Ji Weng, Guoying Gao, Shuai Dong, Ling-Fang Lin, Wei-Hua Wang, Qiang Zhu, Artem R. Oganov, Xiao Dong, Yongjun Tian, Xiang-Feng Zhou, Hui-Tian Wang

Physics & Astronomy Faculty Research

A computational methodology based on ab initio evolutionary algorithms and spin-polarized density functional theory was developed to predict two-dimensional magnetic materials. Its application to a model system borophene reveals an unexpected rich magnetism and polymorphism. A metastable borophene with nonzero thickness is an antiferromagnetic semiconductor from first-principles calculations, and can be further tuned into a half-metal by finite electron doping. In this borophene, the buckling and coupling among three atomic layers are not only responsible for magnetism, but also result in an out-of-plane negative Poisson's ratio under uniaxial tension, making it the first elemental material possessing auxetic and magnetic properties …

Topics In Three-Dimensional Imaging, Source Localization And Super-Resolution, Zhixian Yu

Physics & Astronomy ETDs

The realization that twisted light beams with helical phasefronts could carry orbital angular momentum (OAM) that is in excess of the photon's spin angular momentum (SAM) has spawned various important applications. One example is the design of novel imaging systems that achieve three-dimensional (3D) imaging in a single snapshot via the rotation of point spread function (PSF).

Based on a scalar-field analysis, a particular simple version of rotating PSF imagery, which was proposed by my advisor Dr. Prasad, furnishes a practical approach to perform 3D source localization using a spiral phase mask that generates a combination of Bessel vortex beams. …

Seeing Eye To Eye: A Machine Learning Approach To Automated Saccade Analysis, Maigh Attre

Honors Scholar Theses

Abnormal ocular motility is a common manifestation of many underlying pathologies particularly those that are neurological. Dynamics of saccades, when the eye rapidly changes its point of fixation, have been characterized for many neurological disorders including concussions, traumatic brain injuries (TBI), and Parkinson’s disease. However, widespread saccade analysis for diagnostic and research purposes requires the recognition of certain eye movement parameters. Key information such as velocity and duration must be determined from data based on a wide set of patients’ characteristics that may range in eye shapes and iris, hair and skin pigmentation [36]. Previous work on saccade analysis has …

Scope Of Self-Interacting Thermal Wimps In A Minimal U(1) D Extension And Its Future Prospects, Rahool Kumar Barman, Biplob Bhattacherjee, Arindam Chatterjee, Arghya Choudhury, Aritra Gupta

Journal Articles

In this work we have considered a minimal extension of Standard Model by a local U(1) gauge group in order to accommodate a stable (fermionic) Dark Matter (DM) candidate. We have focussed on parameter regions where DM possesses adequate self-interaction, owing to the presence of a light scalar mediator (the dark Higgs), alleviating some of the tensions in the small-scale structures. We have studied the scenario in the light of a variety of data, mostly from dark matter direct searches, collider searches and flavor physics experiments, with an attempt to constrain the interactions of the standard model (SM) particles with …

Methods To Remotely Eliminate Biofilm From Medical Implants Using 2.4 Ghz Microwaves, Brett Glenn

Mechanical Engineering Undergraduate Honors Theses

Infections associated with biofilm growth are usually challenging to eradicate due to their high tolerance toward antibiotics [11, 12]. Biofilms often form on the inert surfaces of medically implanted devices [13]. No matter the sophistication, microbial infections can develop on all medical devices and tissue engineering constructs [12]. Related infections lead to 2 million cases annually in the U.S., costing the healthcare system over $5 billion in additional healthcare expenses [12].

Novel solutions to biofilm’s microbial colonization span the spectrum of engineering and science disciplines. Yet a practical solution still does not exist. The research presented here will explore a …

Optical Enhancement In Periodic Plasmonic Gratings For Sers And Metal-Semiconductor-Metal Photodetectors (Msm-Pds) Applications, Ahmad Aziz Darweesh

Graduate Theses and Dissertations

This dissertation is aimed to numerically study the effect of plasmonic grating electrodes on the efficiency of metal-semiconductor-metal photodetectors (MSM PDs) and the sensitivity of Surface Enhanced Raman Spectroscopy (SERS). This research can benefit many areas of nanoscience and optics, including plasmonic applications, such as, super lenses, nano-scale optical circuits, optical filters, surface plasmon enhanced photo-detectors solar cells, imaging sensors, charge-coupled devices (CCD), and optical-fiber communication systems. Several parameters, wire widths and thickness, gap space, taper angle, and the incident wavelength and angle, were investigated. The goal of this research is to utilize the plasmonic phenomenon by using plasmonic gratings …

Quantification Of Contrast-Enhanced Ultrasound, Joseph Pathoulas

All College Thesis Program, 2016-2019

The aim of this experiment was to investigate the effect of manipulating ultrasound scanner settings on time-intensity curve parameters in a tube perfusion phantom system using contrast-enhanced ultrasound imaging. Imaging was performed using a Philips LOGIQ E9 ultrasound scanner equipped with a C1-6VN transducer and utilized two different microbubble contrast agents: Definity and Lumason. The ultrasound scanner settings manipulated included: gain, dynamic range, and frequency. Additionally, relative microbubble concentration, microbubble type, and perfusion flow rate were manipulated. Four time-intensity curve parameters (time to peak, area under curve, gradient, peak intensity) were measured from linearized pixel data. Time to peak was …

Exploring Variations In Diet And Migration From Late Antiquity To The Early Medieval Period In The Veneto, Italy: A Biochemical Analysis, Ashley B. Maxwell

USF Tampa Graduate Theses and Dissertations

This project tests the hypothesis that the Langobard migration into the Roman/Byzantine Veneto (northeastern Italy) resulted in significant dietary changes from Late Antiquity (4-5th centuries AD) to the Early Medieval period (6-8th centuries AD). At the end of the Great Germanic Migrations in AD 568, Langobards from Pannonia entered and occupied two-thirds of the Italian peninsula. It is unclear how large these migrations were, as historical documents exaggerate mass movements; however, conservative estimates suggest they made up 8% of the areas they occupied. The degree to which the Langobards influenced economic change and subsistence in this area is poorly understood. …

Three-Dimensional Time-Resolved Trajectories From Laboratory Insect Swarms, Michael Sinhuber, Kasper Van Der Vaart, Rui Ni, James G. Puckett, Douglas H. Kelley, Nicholas T. Ouellette

Physics and Astronomy Faculty Publications

Aggregations of animals display complex and dynamic behaviour, both at the individual level and on the level of the group as a whole. Often, this behaviour is collective, so that the group exhibits properties that are distinct from those of the individuals. In insect swarms, the motion of individuals is typically convoluted, and swarms display neither net polarization nor correlation. The swarms themselves, however, remain nearly stationary and maintain their cohesion even in noisy natural environments. This behaviour stands in contrast with other forms of collective animal behaviour, such as flocking, schooling, or herding, where the motion of individuals is …

A Theoretical Model Of Underground Dipole Antennas For Communications In Internet Of Underground Things, Abdul Salam, Mehmet C. Vuran, Xin Dong, Christos Argyropoulos, Suat Irmak

Faculty Publications

The realization of Internet of Underground Things (IOUT) relies on the establishment of reliable communication links, where the antenna becomes a major design component due to the significant impacts of soil. In this paper, a theoretical model is developed to capture the impacts of change of soil moisture on the return loss, resonant frequency, and bandwidth of a buried dipole antenna. Experiments are conducted in silty clay loam, sandy, and silt loam soil, to characterize the effects of soil, in an indoor testbed and field testbeds. It is shown that at subsurface burial depths (0.1-0.4m), change in soil moisture impacts …

Fluorine Chemistry At Extreme Conditions: Possible Synthesis Of Hgf4, Michael G. Pravica, Sarah Schyck, Blake Harris, Petrika Cifligu, Eunja Kim, Brant Billinghurst

Physics & Astronomy Faculty Research

By irradiating a pressurized mixture of a fluorine-bearing compound (XeF2XeF2) and HgF2HgF2 with synchrotron hard x-rays ... (See full text for complete abstract)

Fundamental Limits Of Measuring Single-Molecule Rotational Mobility, Oumeng Zhang, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

Various methods exist for measuring molecular orientation, thereby providing insight into biochemical activities at nanoscale. Since fluorescence intensity and not electric field is detected, these methods are limited to measuring even-order moments of molecular orientation. However, any measurement noise, for example photon shot noise, will result in nonzero measurements of any of these even-order moments, thereby causing rotationally-free molecules to appear to be partially constrained. Here, we build a model to quantify measurement errors in rotational mobility. Our theoretical framework enables scientists to choose the optimal single-molecule orientation measurement technique for any desired measurement accuracy and photon budget.

Magnetic Resonance Studies Of Free Radicals Generation And Their Impact In Different Polymers, Sunita Humagain

Dissertations, Theses, and Capstone Projects

Studies of free radicals in the physics, chemistry, biology, and materials science have contributed to advancements in those fields. The presence of radicals can damage the material and system in some instances and, in some cases, they may enhance the property of the material as well. Knowledge of free radical transformations helps in resilience of certain polymers and inhibition of the oxidation of food and medicine. In this thesis, using the magnetic resonance techniques, EPR and NMR, the generation of free radicals and their effect on the structure of the material is being studied.

Kapton Polyimide (PI, Kapton®) used in …

Studying The Interface Between Croconic Acid Thin Films And Substrates Using A Slow Positron Beam, Dean Peterson, Jiandang Liu, Jonas Etzweiler, Gabriel Sontoyo, Sara J. Callori, Kimberley R. Cousins, Timothy Usher, Renwu Zhang

Physics Faculty Publications

Croconic acid (CA) is the first organic ferroelectric with a spontaneous polarity in bulk samples comparable to its inorganic counterparts. As a natural extension of study, ultrathin CA films (∼nm scale) were investigated to reveal ferroelectric effects in films on different substrates for their fundamental and industrial significance. However, the void defect at the interface between the film and substrate is presumed to interfere with surface effects. In this work, a non-invasive technique, a slow positron beam, coupled with Doppler broadening energy spectroscopy (DBES), is applied to study the void defects within the interfacial layer between CA films and Si …