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- Title
- Dosimetric Influence of Dose due to the PTV Dose Uniformity on the Critical Organs.
- Creator
- Yigit, Erdem, Pella, Silvia, Theodora Leventouri, Theodora Leventouri,, Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
- Abstract/Description
-
Dose uniformity in the Planning Target Volume (PTV) can induce a higher-than-expected dose distribution in the nearby critical organs. The goal of this study is to evaluate the influence of the Planning Target volume dose uniformity on the surrounding critical organs (OAR). Ten cases of anonymized patients’ data were selected for our study including: Breast cancer, Brain cancer, Head and Neck cancer, Lung and Prostate calculations of Conformity indices, Biological Effective Doses (BED), Tumor...
Show moreDose uniformity in the Planning Target Volume (PTV) can induce a higher-than-expected dose distribution in the nearby critical organs. The goal of this study is to evaluate the influence of the Planning Target volume dose uniformity on the surrounding critical organs (OAR). Ten cases of anonymized patients’ data were selected for our study including: Breast cancer, Brain cancer, Head and Neck cancer, Lung and Prostate calculations of Conformity indices, Biological Effective Doses (BED), Tumor Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) were used to calculate the dose distribution in PTV as well as the dose delivered to the surrounding critical organs of each PTV. We assume that the tumors PTVs have homogeneous density as well as the surrounding normal tissue. Conformity indices (CI) for Breast (PTV) are between 1.8 – 1.9, for Brain (PTV) are between 1.6 – 2.0, for Lungs are 1.5 – 1.6, for Prostate are between 0.4 – 0.5, for Head and Neck are 0.3 – 0.4. Dose uniformity in all the PTVs is 1.089 which is a good indication of the quality of treatment delivered to the tumor. TCP is averaging of value of 87.94 and NTCP is 3.4445.
Show less - Date Issued
- 2023
- PURL
- http://purl.flvc.org/fau/fd/FA00014339
- Subject Headings
- Radiation dosimetry, Biophysics, Cancer
- Format
- Document (PDF)
- Title
- Gravitational signature of core-collapse supernova results of CHIMERA simulations.
- Creator
- Yakunin, Konstantin., Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
Core-collapse supernovae (CCSN) are among the most energetic explosions in the universe, liberating ~1053 erg of gravitational binding energy of the stellar core. Most of this energy ( ~99%) is emitted in neutrinos and only 1% is released as electromagnetic radiation in the visible spectrum. Energy radiated in the form of gravitational waves (GWs) is about five orders smaller. Nevertheless, this energy corresponds to a very strong GW signal and, because of this CCSN are considered as one of...
Show moreCore-collapse supernovae (CCSN) are among the most energetic explosions in the universe, liberating ~1053 erg of gravitational binding energy of the stellar core. Most of this energy ( ~99%) is emitted in neutrinos and only 1% is released as electromagnetic radiation in the visible spectrum. Energy radiated in the form of gravitational waves (GWs) is about five orders smaller. Nevertheless, this energy corresponds to a very strong GW signal and, because of this CCSN are considered as one of the prime sources of gravitational waves for interferometric detectors. Gravitational waves can give us access to the electromagnetically hidden compact inner core of supernovae. They will provide valuable information about the angular momentum distribution and the baryonic equation of state, both of which are uncertain. Furthermore, they might even help to constrain theoretically predicted SN mechanisms. Detection of GW signals and analysis of the observations will require realistic signal predi ctions from the non-parameterized relativistic numerical simulations of CCSN. This dissertation presents the gravitational wave signature of core-collapse v supernovae. Previous studies have considered either parametric models or nonexploding models of CCSN. This work presents complete waveforms, through the explosion phase, based on first-principles models for the first time. We performed 2D simulations of CCSN using the CHIMERA code for 12, 15, and 25M non-rotating progenitors. CHIMERA incorporates most of the criteria for realistic core-collapse modeling, such as multi-frequency neutrino transport coupled with relativistic hydrodynamics, eective GR potential, nuclear reaction network, and an industry-standard equation of state., Based on the results of our simulations, I produced the most realistic gravitational waveforms including all postbounce phases of core-collapse supernovae: the prompt convection, the stationary accretion shock instability, and the corresponding explosion. Additionally, the tracer particles applied in the analysis of the GW signal reveal the origin of low-frequency component in the prompt part of gravitational waveform. Analysis of detectability of the GW signature from a Galactic event shows that the signal is within the band-pass of current and future GW observatories such as AdvLIGO, advanced Virgo, and LCGT.
Show less - Date Issued
- 2011
- PURL
- http://purl.flvc.org/FAU/3322512
- Subject Headings
- Mathematical physics, Continuum mechanics, Supernovae, Mathematical models
- Format
- Document (PDF)
- Title
- The electronic structure and properties of equi-atomic CuAu.
- Creator
- Xu, Xumou, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
The electronic structure of equi-atomic CuAu has been investigated by a combination of photoelectron spectroscopy and first-principles band structure calculations. The study includes the first ever ARUPS and ARAES measurements from a single crystal of CuAu I. We have studied in detail the energy dispersion and shifts of a Tamm state on the (001) and (100) surfaces and we determined the surface lattice constants and the dependencies of the energy shifts on atomic concentration and geometry....
Show moreThe electronic structure of equi-atomic CuAu has been investigated by a combination of photoelectron spectroscopy and first-principles band structure calculations. The study includes the first ever ARUPS and ARAES measurements from a single crystal of CuAu I. We have studied in detail the energy dispersion and shifts of a Tamm state on the (001) and (100) surfaces and we determined the surface lattice constants and the dependencies of the energy shifts on atomic concentration and geometry. Two new surface states were found on the two surfaces and their properties have been investigated. Comparisons between the valence band spectra from the two samples of CuAu I have been carried out and the results show that the different atomic arrangements in the crystal do not have a significant effect on the band structure. We also compared spectra from the alloy with those from the parent metals. A series of calculations of the electronic structure of CuAu I has been carried out by the SCF-LMTO-ASA and RKKR methods. We found that the superzone boundaries that are created when the CuAu II phase is formed destroy appreciable regions of Fermi surface, thus, favoring the latter phase. The positions of the new boundaries are related directly to the period of the long period superlattice and we have investigated their dependence on the e/a ratio and pressure. The results are in very good agreement with previous experimental measurements. We also calculated the Fermi surfaces of three disordered Cu-Au alloys near the equi-atomic composition using the KKR-CPA scheme. The results have shown strong evidence that the Fermi surface topology may play an important role in stabilizing and determining the modulation of the LPS in CuAu II.
Show less - Date Issued
- 1995
- PURL
- http://purl.flvc.org/fcla/dt/12423
- Subject Headings
- Physics, Condensed Matter
- Format
- Document (PDF)
- Title
- Structural, electrical and magnetic properties of transition metal nickel oxides.
- Creator
- Wu, Guoqing, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
Neutron powder diffraction, high pressure, magnetic susceptibility, and heat capacity measurements, as well as x-ray powder diffraction and iodometric titration, have been conducted on transition metal nickel oxides (TMOs), representative Ruddlesden-Popper (RP) phases Lan+1NinO3n+1 (n = 1, 2, ..., infinity) and hole-doped La2-xSr xNiO4 (0
Show moreNeutron powder diffraction, high pressure, magnetic susceptibility, and heat capacity measurements, as well as x-ray powder diffraction and iodometric titration, have been conducted on transition metal nickel oxides (TMOs), representative Ruddlesden-Popper (RP) phases Lan+1NinO3n+1 (n = 1, 2, ..., infinity) and hole-doped La2-xSr xNiO4 (0 < x < 1.2). The first complete study of La 2-xSrxNiO4 (0 < x < 1.2) and La n+1NinO3n+1 (n = 2 and 3) phases under high pressure is produced. Strong direct experimental evidence for polaron dominated electrical conduction in these charge transfer (CT) gap La2-xSr xNiO4 compounds is provided. Temperature evolution of the crystal structure of La2-xSrxNiO4 (x = 1/4 and 1/3) is revealed through neutron powder diffraction, structural relationships among n = 1, 2, and 3 phases are exhibited, and charge density wave (CDW) in multilayer Lan+1NinO3n+1 phases is strongly suggested. No superconductivity is observed at pressures up to 1.6 GPa and temperatures down to 4.2 K.
Show less - Date Issued
- 2002
- PURL
- http://purl.flvc.org/fcla/dt/11997
- Subject Headings
- Physics, Condensed Matter
- Format
- Document (PDF)
- Title
- METASTABLE EXCITATION OF POPULATION INVERSION IN A HELIUM-HYDROGEN AFTERGLOW PLASMA.
- Creator
- WOO, KING NIEN., Florida Atlantic University, Burnett, Clyde R., Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
A spectroscopic study of a helium-hydrogen afterglow plasma in a pulsed discharge hollow-cathode has been made to determine the energy transfer process which results in a population inversion in atomic hydrogen. Time-resolved emission measurements were made for the Balmer series in hydrogen and self-absorption measurements with lambda 3889 A (2s 3S - 3p 3P) and lambda 4650 A (2s 3sigma - 3p 3n) of helium were taken to monitor the metastable populations. Observations were made as a function of...
Show moreA spectroscopic study of a helium-hydrogen afterglow plasma in a pulsed discharge hollow-cathode has been made to determine the energy transfer process which results in a population inversion in atomic hydrogen. Time-resolved emission measurements were made for the Balmer series in hydrogen and self-absorption measurements with lambda 3889 A (2s 3S - 3p 3P) and lambda 4650 A (2s 3sigma - 3p 3n) of helium were taken to monitor the metastable populations. Observations were made as a function of impurity concentration and as a function of helium pressure. The energy transfer from the 3S atomic metastables appears highly probable with only a minor contribution from the 3sigma molecular metastables.
Show less - Date Issued
- 1975
- PURL
- http://purl.flvc.org/fcla/dt/13746
- Subject Headings
- Physics--Experiments, Energy transfer--Experiments
- Format
- Document (PDF)
- Title
- A Dosimetric Comparison of 3D-CRT, IMRT, and SAVI HDR via NTCP/TCP and DVH Analysis of Critical Organs for Breast Cancer.
- Creator
- Wisnoskie, Sarah, Pella, Silvia, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
Accelerated Partial Breast Irradiation (APBI) is a common treatment of breast cancer with many modalities including 3D Conformal Radiation Therapy (3D-CRT), Intensity Modulated Radiation Therapy (IMRT), and High Dose Rate Brachytherapy (HDR). In this research, a retrospective analysis of patient’s data was performed to analyze the NTCP/TCP (Normal Tissue Complication Probability/Tumor Control Probability) and Dose Volume Histogram (DVH) parameters for HDR with SAVI, 3D, and IMRT and compare...
Show moreAccelerated Partial Breast Irradiation (APBI) is a common treatment of breast cancer with many modalities including 3D Conformal Radiation Therapy (3D-CRT), Intensity Modulated Radiation Therapy (IMRT), and High Dose Rate Brachytherapy (HDR). In this research, a retrospective analysis of patient’s data was performed to analyze the NTCP/TCP (Normal Tissue Complication Probability/Tumor Control Probability) and Dose Volume Histogram (DVH) parameters for HDR with SAVI, 3D, and IMRT and compare them focusing on critical organs such as the heart, ipsilateral lung, chest wall, ribs, and skin. TCP was 90.275%, 55.948%, and 53.369% for HDR, 3D, and IMRT respectively. The ribs were the most sensitive critical organ for all 3 modalities with a mean NTCP of 8%, 15%, and 8% for HDR, 3D, and IMRT respectively. DVH analysis showed HDR spares critical organs more than EBRT except for 2 patients receiving high doses to the ribs and chest wall.
Show less - Date Issued
- 2019
- PURL
- http://purl.flvc.org/fau/fd/FA00013281
- Subject Headings
- Radiation dosimetry--Evaluation, Breast--Cancer--Treatment, Organs, Tissues--Effect of radiation on
- Format
- Document (PDF)
- Title
- General relativistic quasi-local angular momentum continuity and the stability of strongly elliptic eigenvalue problems.
- Creator
- Wilder, Shawn M., Beetle, Christopher, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
In general relativity, angular momentum of the gravitational field in some volume bounded by an axially symmetric sphere is well-defined as a boundary integral. The definition relies on the symmetry generating vector field, a Killing field, of the boundary. When no such symmetry exists, one defines angular momentum using an approximate Killing field. Contained in the literature are various approximations that capture certain properties of metric preserving vector fields. We explore the...
Show moreIn general relativity, angular momentum of the gravitational field in some volume bounded by an axially symmetric sphere is well-defined as a boundary integral. The definition relies on the symmetry generating vector field, a Killing field, of the boundary. When no such symmetry exists, one defines angular momentum using an approximate Killing field. Contained in the literature are various approximations that capture certain properties of metric preserving vector fields. We explore the continuity of an angular momentum definition that employs an approximate Killing field that is an eigenvector of a particular second-order differential operator. We find that the eigenvector varies continuously in Hilbert space under smooth perturbations of a smooth boundary geometry. Furthermore, we find that not only is the approximate Killing field continuous but that the eigenvalue problem which defines it is stable in the sense that all of its eigenvalues and eigenvectors are continuous in Hilbert space. We conclude that the stability follows because the eigenvalue problem is strongly elliptic. Additionally, we provide a practical introduction to the mathematical theory of strongly elliptic operators and generalize the above stability results for a large class of such operators.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00004235
- Subject Headings
- Boundary element methods, Boundary value problems, Differential equations, Elliptic -- Numerical solutions, Differential equations, Partial -- Numerical solutions, Eigenvalues, Spectral theory (Mathematics)
- Format
- Document (PDF)
- Title
- The multiple scattering approach to the electronic structure of ordered solids, impurities, and alloys.
- Creator
- Wang, Yang, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
In this dissertation, multiple scattering theory (MST) plays a fundamental role. It is applied to develop the electronic structure calculation techniques for ordered solids, single impurities and binary alloys. The most accurate fast-band-theory technique based on the MST is the quadratic Korringa-Kohn-Rostoker (QKKR) method. A method for carrying out the self-consistent QKKR calculation for ordered compounds is derived and applied to palladium hydride. The application of the QKKR method to...
Show moreIn this dissertation, multiple scattering theory (MST) plays a fundamental role. It is applied to develop the electronic structure calculation techniques for ordered solids, single impurities and binary alloys. The most accurate fast-band-theory technique based on the MST is the quadratic Korringa-Kohn-Rostoker (QKKR) method. A method for carrying out the self-consistent QKKR calculation for ordered compounds is derived and applied to palladium hydride. The application of the QKKR method to single impurity problems is also examined. In order to study phase diagrams of binary alloys, a new approach, called the embedded cluster Monte Carlo (ECMC) method, is developed. It is used to calculate the miscibility gap in the Pd-Rh alloy phase diagram to an accuracy that has never before been achieved. A non-magnetic calculation for Cu-Ni alloys is also provided. These calculations required the mastery of Korringa-Kohn-Rostoker coherent-potential-approximation methods and the development of embedded cluster codes.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/12333
- Subject Headings
- Physics, Condensed Matter, Engineering, Materials Science
- Format
- Document (PDF)
- Title
- Spectroscopic studies of ZnWO4 and doped ZnWO4 single crystals.
- Creator
- Wang, Hong, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
Zinc tungstate (ZnWO4) is promising as a scintillator and laser host material. However, the presence of color centers limit its applications. It has been found that special annealing techniques or doping with metallic elements such as Nb or Sb can bleach the samples (Zhou et al. 1986a, 1986b, 1989). A group-theoretical analysis of the characteristic lattice vibrational modes for ZnWO4 single crystals is given. The mode assignments have been made. The temperature dependence of the Raman...
Show moreZinc tungstate (ZnWO4) is promising as a scintillator and laser host material. However, the presence of color centers limit its applications. It has been found that special annealing techniques or doping with metallic elements such as Nb or Sb can bleach the samples (Zhou et al. 1986a, 1986b, 1989). A group-theoretical analysis of the characteristic lattice vibrational modes for ZnWO4 single crystals is given. The mode assignments have been made. The temperature dependence of the Raman spectra has been obtained experimentally in various polarization geometries. Anharmonic contributions and interactions between phonons are discussed. Photoluminescence studies of ZnWO4 (colored, color-free), ZnWO4: Nb and ZnWO4:Sb have been carried out in the temperature range from 11 to 430 K. All samples show the blue emission band. An IR emission band with a zero-phonon line (ZPL) has been found in ZnWO4 colored samples only. The lineshape function of the emission bands has been theoretically studied and compared with the experimental results. Radiative, non-radiative and multiphonon transitions have been investigated in the thermal quenching model. The temperature dependences of the intensity, the frequency and the linewidth of the ZPL have been studied. Using the Single Configurational Coordinate model, the linear coupling between electrons and phonons has been analyzed. The quadratic coupling of electrons and phonons has been studied in the Debye approximation. The coupling of electronic transitions to normal vibrational modes, pseudo-localized vibrational modes and localized modes is also discussed.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/12346
- Subject Headings
- Physics, Condensed Matter, Physics, Optics, Engineering, Materials Science
- Format
- Document (PDF)
- Title
- LOOP QUANTUM GRAVITY DYNAMICS: MODELS AND APPLICATIONS.
- Creator
- Vilensky, Ilya, Engle, Jonathan, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
In this dissertation we study the dynamics of loop quantum gravity and its applications. We propose a tunneling phenomenon of a black hole-white hole transition and derive an amplitude for such transition using the spinfoam framework. We investigate a special class of kinematical states for loop quantum gravity - Bell spin networks - and show that their entanglement entropy obeys the area law. We develop a new spinfoam vertex amplitude that has the correct semi-classical limit. We then apply...
Show moreIn this dissertation we study the dynamics of loop quantum gravity and its applications. We propose a tunneling phenomenon of a black hole-white hole transition and derive an amplitude for such transition using the spinfoam framework. We investigate a special class of kinematical states for loop quantum gravity - Bell spin networks - and show that their entanglement entropy obeys the area law. We develop a new spinfoam vertex amplitude that has the correct semi-classical limit. We then apply this new amplitude to calculate the graviton propagator and a cosmological transition amplitude. The results of these calculations show feasibility of computations with the new amplitude and its viability as a spinfoam model. Finally, we use physical principles to radically constrain ambiguities in the cosmological dynamics and derive unique Hamiltonian dynamics for Friedmann-Robertson-Walker and Bianchi I cosmologies.
Show less - Date Issued
- 2019
- PURL
- http://purl.flvc.org/fau/fd/FA00013349
- Subject Headings
- Quantum gravity, Loop quantum gravity, Cosmology, Spinfoam
- Format
- Document (PDF)
- Title
- A characterization of the LAP Aquarius Phantom for external LAP laser alignment and magnetic resonance geometric distortion verification for stereotactic radiation surgery patient simulation.
- Creator
- Vergara, Daniel, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
The Thesis explores additional applications of LAP's Aquarius external laser alignment verification Phantom by examining geometric accuracy of magnetic resonance images commonly used for planning intracranial stereotactic radiation surgery (ICSRS) cases. The scans were performed with MRI protocols used for ICSRS, and head and neck diagnosis, and their images fused to computerized tomographic (CT) images. The geometric distortions (GDs) were measured against the CT in all axial, sagittal, and...
Show moreThe Thesis explores additional applications of LAP's Aquarius external laser alignment verification Phantom by examining geometric accuracy of magnetic resonance images commonly used for planning intracranial stereotactic radiation surgery (ICSRS) cases. The scans were performed with MRI protocols used for ICSRS, and head and neck diagnosis, and their images fused to computerized tomographic (CT) images. The geometric distortions (GDs) were measured against the CT in all axial, sagittal, and coronal directions at different levels. Using the Aquarius Phantom, one is able to detect GD in ICSRS planning MRI acquisitions, and align the external LAP patient alignment lasers, by following the LAP QA protocol. GDs up to about 2 mm are observed at the distal regions of the longitudinal axis in the SRS treatment planning MR images. Based on the results, one may recommend the use of the Aquarius Phantom to determine if margins should be included for SRS treatment planning.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3352878
- Subject Headings
- Radiotherapy, Techniques, Medical physics, Imaging systems in medicine, Tomographic images, Computerized axial tomography
- Format
- Document (PDF)
- Title
- Hamiltonian Methods in the Quantization of Gauge Systems.
- Creator
- Vaulin, Ruslan, Florida Atlantic University, Miller, Warner A., Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
The new formalism for quantization of gauge systems based on the concept of the dynamical Hamiltonian recently introduced as a basis for the canonical theory of quantum gravity was considered in the context of general gauge theories. This and other Hamiltonian methods, that include Dirac's theory of extended Hamiltonian and the Hamiltonian reduction formalism were critically examined. It was established that the classical theories of constrained gauge systems formulated within the framework...
Show moreThe new formalism for quantization of gauge systems based on the concept of the dynamical Hamiltonian recently introduced as a basis for the canonical theory of quantum gravity was considered in the context of general gauge theories. This and other Hamiltonian methods, that include Dirac's theory of extended Hamiltonian and the Hamiltonian reduction formalism were critically examined. It was established that the classical theories of constrained gauge systems formulated within the framework of either of the approaches are equivalent. The central to the proof of equivalence was the fact that the gauge symmetries resuIt in the constraints of the first class in Dirac's terminology that Iead to redundancy of equations of motion for some of the canonica variables. Nevertheless, analysis of the quantum theories showed that in general, the quantum theory of the dynamical Hamiltonian is inequivalent to those of the extended Hamiltonian and the Hamiltonian reduction. The new method of quantization was applied to a number of gauge systems, including the theory of relativistic particle, the Bianchi type IX cosmological model and spinor electrodynamics along side with the traditional methods of quantization. In all of the cases considered the quantum theory of the dynamical Hamiltonian was found to be well-defined and to possess the appropriate classical limit. In particular, the quantization procedure for the Bianchi type IX cosmological spacetime did not run into any of the known problems with quantizing the theory of General Relativity. On the other hand, in the case of the quantum electrodynamics the dynamical Hamiltonian approach led to the quantum theory with the modified self-interaction in the matter sector. The possible consequence of this for the quantization of the full theory of General Relativity including the matter fields are discussed.
Show less - Date Issued
- 2006
- PURL
- http://purl.flvc.org/fau/fd/FA00000882
- Subject Headings
- Quantum field theory, Mathematical physics, Evolution equations, Nonlinear, Hamiltonian systems
- Format
- Document (PDF)
- Title
- Binary neutron star mergeres: simulations with arbitrarily spinning stars.
- Creator
- Tsatsin, Petr, Marronetti, Pedro, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
The starting point of any general relativistic numerical simulation is a solution of the Hamiltonian and momentum constraints that (ideally) represents an astrophysically realistic scenario. This dissertation presents a new method to produce initial data sets for binary neutron stars with arbitrary spins and orbital eccentricities. The method only provides approximate solutions to the constraints. However, it was shown that the corresponding constraint violations subside after a few orbits,...
Show moreThe starting point of any general relativistic numerical simulation is a solution of the Hamiltonian and momentum constraints that (ideally) represents an astrophysically realistic scenario. This dissertation presents a new method to produce initial data sets for binary neutron stars with arbitrary spins and orbital eccentricities. The method only provides approximate solutions to the constraints. However, it was shown that the corresponding constraint violations subside after a few orbits, becoming comparable to those found in evolutions of standard conformally flat, helically symmetric binary initial data. This dissertation presents the first spinning neutron star binary simulations in circular orbits with a orbital eccentricity less then 0.01. The initial data sets corresponding to binaries with spins aligned, zero and anti-aligned with the orbital angular momentum were evolved in time. These simulations show the orbital “hang-up” effect previously seen in binary black holes. Additionally, they show orbital eccentricities that can be up to one order of magnitude smaller than those found in helically symmetric initial sets evolutions.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fau/fd/FA0004067
- Subject Headings
- Astrophysics, Black holes (Astronomy), General relativity (Physics), Gravitational waves, Neutron stars, Particles (Nuclear physics)
- Format
- Document (PDF)
- Title
- Central Moments of Squeezed States: A Coincidence Statistics Analogue.
- Creator
- Tison, Christopher C., Miller, Warner A., Alsing, Paul M., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
As a subset of quantum optics, single photons are one of the competing physical resources for quantum information processing. When used as carriers of quantum information, they have no equal. For the processing of quantum information, single photons have proven difficult to scale beyond the order of ⇠ 10 photons. The lack of single-photon-level interaction has led to creative approaches which rely on postselection to filter the possible measured outcomes to those which appear as though...
Show moreAs a subset of quantum optics, single photons are one of the competing physical resources for quantum information processing. When used as carriers of quantum information, they have no equal. For the processing of quantum information, single photons have proven difficult to scale beyond the order of ⇠ 10 photons. The lack of single-photon-level interaction has led to creative approaches which rely on postselection to filter the possible measured outcomes to those which appear as though interaction occurred. This approach of post-selection leans heavily on the ability to not only generate but also detect scores of single photons simultaneously and with near perfect efficiency. Our work relaxes the emphasis which has been placed on single photons for quantum information processing to that of states with, in principle, an arbitrary number of photons. Central moment expectations on two-mode squeezed states are shown to exhibit post-selection behavior which reflects the single-photon counterpart. These measures are proven to be robust to loss and return entangled state statistics on average. With naive estimation of the central moment, states with ~ 20 modes are within reach with current technology, closing the gap between quantum states which can and cannot be classically simulated.
Show less - Date Issued
- 2018
- PURL
- http://purl.flvc.org/fau/fd/FA00005951
- Subject Headings
- Squeezed states (Optics), Quantum optics, Photons, Integrated optics
- Format
- Document (PDF)
- Title
- Magnetic, thermodynamic, and structural studies of manganese oxides.
- Creator
- Terashita, Hirotoshi, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
Magnetic, thermodynamic, and structural properties of the manganese oxides La1-xCa xMnO3 are studied. Neutron powder diffraction reveals two distinct crystallographic phases as well as two magnetic (ferromagnetic and antiferromagnetic) phases for 0.08
Show moreMagnetic, thermodynamic, and structural properties of the manganese oxides La1-xCa xMnO3 are studied. Neutron powder diffraction reveals two distinct crystallographic phases as well as two magnetic (ferromagnetic and antiferromagnetic) phases for 0.08 < x < 0.14. Details of the compositional dependence of the phase fractions is discussed in the context of local ferromagnetism. Comparisons of magnetic and crystallographic properties are made to the analogous electron-doped Ca1- yLayMnO3 (0 < y < 0.20) system. Thermodynamic properties of La1- xCaxMnO 3 (0 < x < 0.54) are investigated for possible applications in magnetic refrigeration. A maximum magnetic entropy change of 5.5 J/kg K and a corresponding temperature change of 2 K are estimated for x = 0.28. The magnetocaloric effect in antiferromagnetic and charge-ordering compounds is found to be small.
Show less - Date Issued
- 2005
- PURL
- http://purl.flvc.org/fau/fd/FADT12133
- Subject Headings
- Physics, Condensed Matter
- Format
- Document (PDF)
- Title
- AN IMPROVED NEUTRINO TRANSPORT ALGORITHM FOR THE CHIMERA SUPERNOVA CODE.
- Creator
- Tejedor, Ruben Dario, Bruenn, Stephen W., Tichy, Wolfgang, Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
- Abstract/Description
-
Core-Collapse Supernovae (CCSNe) are some of the most powerful events in the universe liberating an astonishing 3×1053 ergs of the gravitational binding energy released by the collapse of the stellar core to a nascent neutron star (PNS) that is formed in these events. The visible display is capable of outshining the entire galaxy where it inhabits. Most of this energy, ~ 99%, is carried away by neutrinos of all flavors, however. According to the favored theory of CCSNe, the production and...
Show moreCore-Collapse Supernovae (CCSNe) are some of the most powerful events in the universe liberating an astonishing 3×1053 ergs of the gravitational binding energy released by the collapse of the stellar core to a nascent neutron star (PNS) that is formed in these events. The visible display is capable of outshining the entire galaxy where it inhabits. Most of this energy, ~ 99%, is carried away by neutrinos of all flavors, however. According to the favored theory of CCSNe, the production and transport of neutrinos from the dense core through the less dense mantle is believed to deposit energy in the mantle and thereby initiate the supernova explosion. Numerically modeling these events realistically to validate the model therefore requires an accurate neutrino transport algorithm coupled to sophisticated neutrino microphysics to compute the emission, transport, and energy deposition of neutrinos. The CHIMERA code is a radiation-hydrodynamics code that has been developed to numerically model CCSNe in multiple spatial dimensions. The neutrino transport algorithm currently incorporated in CHIMERA is based upon the Multigroup Flux-Limited Diffusion (MGFLD) method. This current method basically uses only the zeroth angular moment of the Boltzmann equation and closes the system with terms dropped from the first angular moment to produce a diffusion-like equation. A flux-limiter is added to interpolate between the diffusive and free-streaming regimes, and to prevent the algorithm from computing acausal, i.e., faster than light transport, in regions where the neutrino mean free paths are large.
Show less - Date Issued
- 2023
- PURL
- http://purl.flvc.org/fau/fd/FA00014293
- Subject Headings
- Supernovae, Neutrinos, Astrophysics
- Format
- Document (PDF)
- Title
- Spatiotemporal patterns of neural fields in a spherical cortex with general connectivity.
- Creator
- Tayefeh, Vahid, Fuchs, Armin, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
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The human brain consists of billions of neurons and these neurons pool together in groups at different scales. On one hand, these neural entities tend to behave as single units and on the other hand show collective macroscopic patterns of activity. The neural units communicate with each other and process information over time. This communication is through small electrical impulses which at the macroscopic scale are measurable as brain waves. The electric field that is produced collectively...
Show moreThe human brain consists of billions of neurons and these neurons pool together in groups at different scales. On one hand, these neural entities tend to behave as single units and on the other hand show collective macroscopic patterns of activity. The neural units communicate with each other and process information over time. This communication is through small electrical impulses which at the macroscopic scale are measurable as brain waves. The electric field that is produced collectively by macroscopic groups of neurons within the brain can be measured on the surface of the skull via a brain imaging modality called Electroencephalography (EEG). The brain as a neural system has variant connection topology, in which an area might not only be connected to its adjacent neighbors homogeneously but also distant areas can directly transfer brain activity [16]. Timing of these brain activity communications between different neural units bring up overall emerging spatiotemporal patterns. The dynamics of these patterns and formation of neural activities in cortical surface is influenced by the presence of long-range connections between heterogeneous neural units. Brain activity at large-scale is thought to be involved in the information processing and the implementation of cognitive functions of the brain. This research aims to determine how the spatiotemporal pattern formation phenomena in the brain depend on its connection topology. This connection topology consists of homogeneous connections in local cortical areas alongside the couplings between distant functional units as heterogeneous connections. Homogeneous connectivity or synaptic weight distribution representing the large-scale anatomy of cortex is assumed to depend on the Euclidean distance between interacting neural units. Altering characteristics of inhomogeneous pathways as control parameters guide the brain pattern formation through phase transitions at critical points. In this research, linear stability analysis is applied to a macroscopic neural field in a one-dimensional circular and a twodimensional spherical model of the brain in order to find destabilization mechanism and subsequently emerging patterns.
Show less - Date Issued
- 2018
- PURL
- http://purl.flvc.org/fau/fd/FA00013119
- Subject Headings
- Cerebral cortex, Neural circuitry, Electroencephalography, Neural fields, Spatiotemporal patterns
- Format
- Document (PDF)
- Title
- Narrow and broad band photoluminescence spectroscopy of Cd(x)Zn(1-x)Se semiconductor.
- Creator
- Sweiti, Ayman, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
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In this dissertation I have used photoluminescence (PL) spectrometric analysis to measure the temperature dependence of the spectral features of the direct band gap semiconductor CdxZn1-xSe , for two nominal concentrations x = 0.25, 0.50, in the temperature range 25--300 K. The effective concentrations were obtained from analysis of the spectra. The parameters that describe the temperature dependence of the line width broadening have been evaluated using different models. The PL broadband...
Show moreIn this dissertation I have used photoluminescence (PL) spectrometric analysis to measure the temperature dependence of the spectral features of the direct band gap semiconductor CdxZn1-xSe , for two nominal concentrations x = 0.25, 0.50, in the temperature range 25--300 K. The effective concentrations were obtained from analysis of the spectra. The parameters that describe the temperature dependence of the line width broadening have been evaluated using different models. The PL broadband characteristics of Cd0.22Zn0.78Se and Cd0.41Zn0.59Se are also investigated within the energy range 1.36--2.40 eV and temperature range 25--305 K. Two broad bands are observed, the higher energy band I centered at 1.991 and 1.773 eV, the lower energy band II centered at 1.844 and 1.705 eV for the two samples, respectively. The emission bands are attributed to donor-acceptor pair transitions. The energy scheme shows two donors and two acceptor levels, the binding energies of the donors for Cd 0.22Zn0.78Se are 29 and 208 meV below the conduction band, the binding energies of the acceptors 472 and 511 meV above the valence band. The binding energies of the donors for Cd0.41Zn 0.59Se are 27 and 137 meV, the binding energies of the acceptors 393 and 423 eV. A significant blue shift in energy with increasing temperature was observed for the lower energy band. The ionization temperatures for the deep donors are 279 and 287 K for Cd0.22Zn0.78Se and Cd0.41Zn0.59Se, respectively.
Show less - Date Issued
- 2003
- PURL
- http://purl.flvc.org/fau/fd/FADT12075
- Subject Headings
- Chemistry, Analytical, Physics, Condensed Matter
- Format
- Document (PDF)
- Title
- Development of a Monte Carlo Simulation Model for Varian ProBeam Compact Single-Room Proton Therapy System using GEANT4.
- Creator
- String, Shawn, Muhammad, Wazir, Shang, Charles, Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
- Abstract/Description
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Proton therapy with pencil beam scanning technique is a novel technique to treat cancer patients due to its unique biophysical properties. However, a small error in dose calculation may lead towards undesired greater uncertainties in planed doses. This project aims to create a simulation model of Varian ProBeam Compact using the GEANT4 Monte Carlo simulation tool kit. Experimental data from the first clinical ProBeam Compact system at South Florida Proton Therapy Institute was used to...
Show moreProton therapy with pencil beam scanning technique is a novel technique to treat cancer patients due to its unique biophysical properties. However, a small error in dose calculation may lead towards undesired greater uncertainties in planed doses. This project aims to create a simulation model of Varian ProBeam Compact using the GEANT4 Monte Carlo simulation tool kit. Experimental data from the first clinical ProBeam Compact system at South Florida Proton Therapy Institute was used to validate the simulation model. A comparison was made between the experimental and simulated Integrated Depth-Dose curves using a 2%/2mm gamma index test with 100% of points passing. The beam spot standard deviation sizes (s!) were compared using percent deviation. All simulated s! matched the experimental s! within 2.5%, except 70 and 80 MeV. The model can be used to develop a more comprehensive model as an independent dose verification tool and further investigate dose distribution.
Show less - Date Issued
- 2020
- PURL
- http://purl.flvc.org/fau/fd/FA00013547
- Subject Headings
- Proton Therapy, Monte-Carlo-Simulation, Radiotherapy Dosage
- Format
- Document (PDF)
- Title
- Improved Methodology of Static HDMLC Virtual Cone based Rapid Arcs for Stereotactic Ablative Radiotherapy.
- Creator
- Stevens, Ryan, Shang, Charles, Muhammad, Wazir, Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
- Abstract/Description
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Physical cones equipped on GammaKnife, Cyberknife, and C-arm linacs have been the standard practice in Stereotactic Ablative Radiotherapy (SART) for small intracranial lesions, such as treating trigeminal or glossopharyngeal neuralgia targets. The advancement of high-definition multi-leaf collimators (HDMLC), treatment planning systems, and small field dosimetry now allows for treatment without the need for an auxiliary mounted physical cone. This treatment type uses the “virtual cone”, a...
Show morePhysical cones equipped on GammaKnife, Cyberknife, and C-arm linacs have been the standard practice in Stereotactic Ablative Radiotherapy (SART) for small intracranial lesions, such as treating trigeminal or glossopharyngeal neuralgia targets. The advancement of high-definition multi-leaf collimators (HDMLC), treatment planning systems, and small field dosimetry now allows for treatment without the need for an auxiliary mounted physical cone. This treatment type uses the “virtual cone”, a permanent high-definition MLC, arrangement to deliver “very small fields” with comparable spherical dose distributions to physical cones. The virtual cone therapy, on a Varian Edge™ linac using multiple non-coplanar arcs with static HDMLCs, is a comparable technique that can be used to treat small intracranial neuralgia or other small lesions. In this investigation, two flattening filter free (FFF) photon beams, 6MV FFF and 10MV FFF, were tested for optimal delivery and safety conditions for treating intracranial lesions. The virtual cone method on a Varian Edge™ Linear accelerator using rapid arc stereotactic radiosurgery was used to treat cranial neuralgia for chronic pain for six patients. Absolute dose, relative dose measurements, and monitor units were the main characteristics that were examined to decide which energy was the best for treatment. Source-to-axis distances (SAD) of 100cm measurements were taken at depths of 10cm and 5cm, respectively.
Show less - Date Issued
- 2020
- PURL
- http://purl.flvc.org/fau/fd/FA00013630
- Subject Headings
- Radiotherapy, Radiation dosimetry, Stereotaxic Techniques
- Format
- Document (PDF)