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Full-Text Articles in Physics

Fabrication Of Magnetocaloric La(Fe,Si)13 Thick Films, N H. Dung, N B. Doan, P De Rango, L Ranno, Karl G. Sandeman, N M. Dempsey Jun 2020

Fabrication Of Magnetocaloric La(Fe,Si)13 Thick Films, N H. Dung, N B. Doan, P De Rango, L Ranno, Karl G. Sandeman, N M. Dempsey

Publications and Research

La(Fe,Si)13–based compounds are considered to be very promising magnetocaloric materials for magnetic refrigeration applications. Many studies have focused on this material family but only in bulk form. In this paper we report on the fabrication of thick films of La(Fe,Si)13, both with and without post-hydriding. These films exhibit magnetic and structural properties comparable to bulk materials. We also observe that the ferromagnetic phase transition has a negative thermal hysteresis, a phenomenon not previously found in this material but which may have its origins in the availability of a strain energy reservoir, as in ...


Syllabus Ee330 Electromagnetics, Nicholas Madamopoulos Mar 2020

Syllabus Ee330 Electromagnetics, Nicholas Madamopoulos

Open Educational Resources

Concepts covered in the undergraduate electrical engineering class of electromagnetics


Effect Of Direct-Current Magnetic Field On The Specific Absorption Rate Of Metamagnetic Comnsi: A Potential Approach To Switchable Hyperthermia Therapy, K C. Ugochukwu, M M. Sadiq, E S. Biegel, L Meagher, M R. Hill, Karl G. Sandeman, A Haydon, K Suzuki Jan 2020

Effect Of Direct-Current Magnetic Field On The Specific Absorption Rate Of Metamagnetic Comnsi: A Potential Approach To Switchable Hyperthermia Therapy, K C. Ugochukwu, M M. Sadiq, E S. Biegel, L Meagher, M R. Hill, Karl G. Sandeman, A Haydon, K Suzuki

Publications and Research

Materials with 1st order antiferromagnetic (AFM) to high-magnetization (MM) phase transition known for their inverse magnetocaloric effect, abrupt rise in magnetization and magnetoelastic coupling, are promising for application in combined simultaneous diagnosis and targeted cancer therapy. A therapy that combines alternating-current (ac) and direct-current (dc) magnetic fields for simultaneous magnetic hyperthermia therapy (MHT) and magnetic resonance imaging (MRI), using same magnetic particles for heating and as con- trast agents. We report a proof-of-concept study on the induction heating ability of 1st order metamagnetic material with moderate specific absorption rates (SAR) and no tendency for agglomeration, for potential MHT and MRI ...


Mode Discrimination In Dissipatively Coupled Laser Arrays, Jiajie Ding, Mohammad-Ali Miri Jan 2020

Mode Discrimination In Dissipatively Coupled Laser Arrays, Jiajie Ding, Mohammad-Ali Miri

Publications and Research

No abstract provided.


Optical Potts Machine Through Networks Of Three-Photon Down-Conversion Oscillators, Mostafa Honari-Latifpour, Mohammad-Ali Miri Jan 2020

Optical Potts Machine Through Networks Of Three-Photon Down-Conversion Oscillators, Mostafa Honari-Latifpour, Mohammad-Ali Miri

Publications and Research

In recent years there has been a growing interest in optical simulation of lattice spin models for applications in classical computing. Here, we propose optical implementation of a three-state Potts spin model by using networks of coupled parametric oscillators with phase tristability. We first show that the cubic nonlinear process of spontaneous three-photon down-conversion is accompanied by a tristability in the phase of the subharmonic signal between three states with 2��/3 phase contrast. The phase of such a parametric oscillator behaves like a three-state spin system. Next, we show that a network of dissipatively coupled three-photon down-conversion oscillators emulates ...


An Application Of The Ising Model, Juliano A. Everett Dec 2019

An Application Of The Ising Model, Juliano A. Everett

Publications and Research

Understanding how the Ising model works,what it represents, and how it can be applied to neurology. Given that an Ising model is an Entropy model that could be representative of the firing of neurons, some assumptions of the system are made and then the process is simulated through Monte Carlo methods.


Static Solid Relaxation Ordered Spectroscopy: Ss-Rosy, Gregory S. Boutis, Ravinath Kausik Nov 2019

Static Solid Relaxation Ordered Spectroscopy: Ss-Rosy, Gregory S. Boutis, Ravinath Kausik

Publications and Research

A two-dimensional pulse sequence is introduced for correlating nuclear magnetic resonance anisotropic chemical shifts to a relaxation time (e.g., T1) in solids under static conditions. The sequence begins with a preparatory stage for measuring relaxation times, and is followed by a multiple pulse sequence for homonuclear dipolar decoupling. Data analysis involves the use of Fourier transform, followed by a one-dimensional inverse Laplace transform for each frequency index. Experimental results acquired on solid samples demonstrate the general approach, and additional variations involving heteronuclear decoupling and magic angle spinning are discussed.


Biophysics In Applications, Marilyn R. Gunner Oct 2019

Biophysics In Applications, Marilyn R. Gunner

Open Educational Resources

No abstract provided.


Yields Of Weakly Bound Light Nuclei As A Probe Of The Statistical Hadronization Model, Yiming Cai, Thomas D. Cohen, Boris A. Gelman, Yukari Yamauchi Aug 2019

Yields Of Weakly Bound Light Nuclei As A Probe Of The Statistical Hadronization Model, Yiming Cai, Thomas D. Cohen, Boris A. Gelman, Yukari Yamauchi

Publications and Research

The statistical hadronization model successfully describes the yields of hadrons and light nuclei from central heavy-ion collisions over a wide range of energies. It is a simple and efficient phenomenological framework in which the relative yields for very high energy collisions are essentially determined by a single model parameter—the chemical freeze-out temperature. Recent measurements of yields of hadrons and light nuclei covering over nine orders of magnitudes from the ALICE collaboration at the Large Hadron Collider were described by the model with remarkable accuracy with a chemical freeze-out temperature of 156.5 ± 1.5 MeV. A key physical question ...


Rocketry And Observability Predictions For Cubesat, Juliano A. Everett Aug 2019

Rocketry And Observability Predictions For Cubesat, Juliano A. Everett

Publications and Research

Estimating the visibility of Sunlight reflected by the holographic retro-reflector of Cubesat Alpha, and to convert this to star apparent magnitude to learn more about the visibility of these sails through reflected sunlight, to in turn determine if glints of these holograms are visible by terrestrial observers.


Exploring A Practical Development Of Quantum Computing, Juliano A. Everett, Andrea N. Zambrano, Carlos Aguayza Apr 2019

Exploring A Practical Development Of Quantum Computing, Juliano A. Everett, Andrea N. Zambrano, Carlos Aguayza

Publications and Research

Tasked with describing a Quantum architecture (Superconducting loops), we additionally explored how the chosen architecture is used, developed, and how one could get started in understanding the way in which some quantum algorithms work with this architecture through Python and IBM's tools (Qiskit and IBM Q Experience).


Peculiar Optical Properties Of Bilayer Silicene Under The Influence Of External Electric And Magnetic Fields, Thi-Nga Do, Godfrey Gumbs, Po-Hsin Shih, Danhong Huang, Chih-Wei Chiu, Chia-Yun Chen, Ming-Fa Lin Jan 2019

Peculiar Optical Properties Of Bilayer Silicene Under The Influence Of External Electric And Magnetic Fields, Thi-Nga Do, Godfrey Gumbs, Po-Hsin Shih, Danhong Huang, Chih-Wei Chiu, Chia-Yun Chen, Ming-Fa Lin

Publications and Research

We conduct a comprehensive investigation of the effect of an applied electric field on the optical and magneto-optical absorption spectra for AB-bt (bottom-top) bilayer silicene. The generalized tightbinding model in conjunction with the Kubo formula is efficiently employed in the numerical calculations. The electronic and optical properties are greatly diversified by the buckled lattice structure, stacking configuration, intralayer and interlayer hopping interactions, spin-orbital couplings, as well as the electric and magnetic fields (Ez ˆz & Bz ˆz ). An electric field induces spin-split electronic states, a semiconductor-metal phase transitions and the Dirac cone formations in different valleys, leading to the special absorption ...


New Perspectives On The Schrödinger-Pauli Theory Of Electrons: Part I, Viraht Sahni Jan 2019

New Perspectives On The Schrödinger-Pauli Theory Of Electrons: Part I, Viraht Sahni

Publications and Research

Schrödinger-Pauli (SP) theory is a description of electrons in the presence of a static electromagnetic field in which the interaction of the magnetic field with both the orbital and spin moments is explicitly considered. The theory is described from the new perspective of the individual electron via its equation of motion or ‘Quantal Newtonian’ first law. The law is in terms of ‘classical’ fields whose sources are quantum mechanical expectation values of Hermitian operators taken with respect to the system wave function. The law states that each electron experiences an external and an internal field, the sum of which vanish ...


New Perspectives On The Schrödinger-Pauli Theory Of Electrons: Part Ii: Application To The Triplet State Of A Quantum Dot In A Magnetic Field, Marlina Slamet, Viraht Sahni Jan 2019

New Perspectives On The Schrödinger-Pauli Theory Of Electrons: Part Ii: Application To The Triplet State Of A Quantum Dot In A Magnetic Field, Marlina Slamet, Viraht Sahni

Publications and Research

The Schrödinger-Pauli (SP) theory of electrons in the presence of a static electromagnetic field can be described from the perspective of the individual electron via its equation of motion or 'Quantal Newtonian' first law. The law is in terms of 'classical' fields whose sources are quantum-mechanical expectation values of Hermitian operators taken with respect to the wave function. The law states that the sum of the external and internal fields experienced by each electron vanishes. The external field is the sum of the binding electrostatic and Lorentz fields. The internal field is the sum of fields representative of properties of ...


Computational Techniques For Scattering Amplitudes, Juliano A. Everett Dec 2018

Computational Techniques For Scattering Amplitudes, Juliano A. Everett

Publications and Research

Scattering amplitudes in quantum field theory can be described as the probability of a scattering process to happen within a high energy particle interaction, as well as a bridge between experimental measurements and the prediction of the theory.

In this research project, we explore the Standard Model of Particle Theory, it’s representation in terms of Feynman diagrams and the algebraic formulas associated with each combination.

Using the FeynArts program as a tool for generating Feynman diagrams, we evaluate the expressions of a set of physical processes, and explain why these techniques become necessary to achieve this goal.


Impact Of Fiber Parameters On Edfa And/Or Raman Amplified High-Spectral-Efficiency Coherent Wdm Transmissions, Lufeng Leng Nov 2018

Impact Of Fiber Parameters On Edfa And/Or Raman Amplified High-Spectral-Efficiency Coherent Wdm Transmissions, Lufeng Leng

Publications and Research

The impact of fiber properties is investigated for coherent systems employing polarization-division multiplexed high-level quadrature amplitude modulation, wavelength-division multiplexing, and erbium-doped fiber amplifier and/or distributed Raman amplification. This is done by comparing the performances of fiber links of various attenuation coefficients and effective areas via experimentally verified analytical methods. Results show that the excess noise, which originates at amplifiers compensating for the losses of filters and switches located between fiber spans, can weaken or even diminish the performance enhancement brought about by lowering the fiber attenuation coefficient, especially if distributed Raman amplification is employed. This leads to the difference ...


Study Of The Kinetic Energy Densities Of Electrons As Applied To Quantum Dots In A Magnetic Field, Marlina Slamet, Viraht Sahni Oct 2018

Study Of The Kinetic Energy Densities Of Electrons As Applied To Quantum Dots In A Magnetic Field, Marlina Slamet, Viraht Sahni

Publications and Research

There are three expressions for the kinetic energy density t(r) expressed in terms of its quantal source, the single‐particle density matrix: tA(r), the integrand of the kinetic energy expectation value; tB(r), the trace of the kinetic energy tensor; tC(r), a virial form in terms of the 'classical' kinetic field. These kinetic energy densities are studied by application to 'artificial atoms' or quantum dots in a magnetic field in a ground and excited singlet state. A comparison with the densities for natural atoms and molecules in their ground state is made. The near ...


The Diverse Magneto-Optical Selection Rules In Bilayer Black Phosphorus, Jhao-Ying Wu, Szu-Chao Chen, Thi-Nga Do, Wu-Pei Su, Godfrey Gumbs, Ming-Fa Lin Sep 2018

The Diverse Magneto-Optical Selection Rules In Bilayer Black Phosphorus, Jhao-Ying Wu, Szu-Chao Chen, Thi-Nga Do, Wu-Pei Su, Godfrey Gumbs, Ming-Fa Lin

Publications and Research

The magneto-optical properties of bilayer phosphorene is investigated by the generalized tight-binding model and the gradient approximation. The vertical inter-Landau-level transitions, being sensitive to the polarization directions, are mainly determined by the spatial symmetries of sub-envelope functions on the distinct sublattices. The anisotropic excitations strongly depend on the electric and magnetic fields. A uniform perpendicular electric field could greatly diversify the selection rule, frequency, intensity, number and form of symmetric absorption peaks. Specifically, the unusual magneto-optical properties appear beyond the critical field as a result of two subgroups of Landau levels with the main and side modes. The rich and ...


Kinetic Effects In 2d And 3d Quantum Dots: Comparison Between High And Low Electron Correlation Regimes, Marlina Slamet, Viraht Sahni Aug 2018

Kinetic Effects In 2d And 3d Quantum Dots: Comparison Between High And Low Electron Correlation Regimes, Marlina Slamet, Viraht Sahni

Publications and Research

Kinetic related ground state properties of a two-electron 2D quantum dot in a magnetic field and a 3D quantum dot (Hooke's atom) are compared in the Wigner high (HEC) and low (LEC) electron correlation regimes. The HEC regime corresponds to low densities sufficient for the creation of a Wigner molecule. The LEC regime densities are similar to those of natural atoms and molecules. The results are determined employing exact closed-form analytical solutions of the Schrödinger-Pauli and Schrödinger equations, respectively. The properties studied are the local and nonlocal quantal sources of the density and the single particle density matrix; the ...


Comparative Study Of Qubits, Juliano A. Everett, Mubinjon Satymov, Zechariah Ilmot May 2018

Comparative Study Of Qubits, Juliano A. Everett, Mubinjon Satymov, Zechariah Ilmot

Publications and Research

In quantum computing, a quantum bit ("qubit") is a unit of quantum information. A qubit is a two-level quantum system. The developing of qubits with optimal properties, related to quantum entanglement and possibilities of control the states of qubits, is very important for quantum computing applications. We analyzed various types of qubits. There are at least five major quantum computing approaches being explored worldwide: silicon spin qubits, ion traps, superconducting loops, diamond vacancies and topological qubits. We compared the advantages and disadvantages in the properties of all these qubits for applications for quantum computing. We analyzed possible strategies to improve ...


Multi Institutional Quantitative Phantom Study Of Yttrium-90 Pet In Pet/Mri: The Mr-Quest Study, Nicole M. Maughan, Mootaz Eldib, David Faul, Maurizio Conti, Mattijs Elschot, Karin Knešaurek, Francesca Leek, David Townsend, Frank P. Difilippo, Kimberly Jackson, Stephan G. Nekolla, Mathias Lukas, Michael Tapner, Parag J. Parikh, Richard Laforest Apr 2018

Multi Institutional Quantitative Phantom Study Of Yttrium-90 Pet In Pet/Mri: The Mr-Quest Study, Nicole M. Maughan, Mootaz Eldib, David Faul, Maurizio Conti, Mattijs Elschot, Karin Knešaurek, Francesca Leek, David Townsend, Frank P. Difilippo, Kimberly Jackson, Stephan G. Nekolla, Mathias Lukas, Michael Tapner, Parag J. Parikh, Richard Laforest

Publications and Research

Background

Yttrium-90 (90Y) radioembolization involves the intra-arterial delivery of radioactive microspheres to treat hepatic malignancies. Though this therapy involves careful pre-treatment planning and imaging, little is known about the precise location of the microspheres once they are administered. Recently, there has been growing interest post-radioembolization imaging using positron-emission tomography (PET) for quantitative dosimetry and identifying lesions that may benefit from additional salvage therapy. In this study, we aim to measure the inter-center variability of 90Y PET measurements as measured on PET/MRI in preparation for a multi-institutional prospective phase I/II clinical trial.

Eight institutions participated in this ...


Diy Science Sims, James Hedberg Apr 2018

Diy Science Sims, James Hedberg

Open Educational Resources

No abstract provided.


Dissipation Effects In Schrödinger And Quantal Density Functional Theories Of Electrons In An Electromagnetic Field, Xiao-Yin Pan, Viraht Sahni Mar 2018

Dissipation Effects In Schrödinger And Quantal Density Functional Theories Of Electrons In An Electromagnetic Field, Xiao-Yin Pan, Viraht Sahni

Publications and Research

Dissipative effects arise in an electronic system when it interacts with a time-dependent environment. Here, the Schrödinger theory of electrons in an electromagnetic field including dissipative effects is described from a new perspective. Dissipation is accounted for via the effective Hamiltonian approach in which the electron mass is time-dependent. The perspective is that of the individual electron: the corresponding equation of motion for the electron or time-dependent differential virial theorem—the ‘Quantal Newtonian’ second law—is derived. According to the law, each electron experiences an external field comprised of a binding electric field, the Lorentz field, and the electromagnetic field ...


Demonstration Of Ultra-High Recyclable Energy Densities In Domain-Engineered Ferroelectric Films, Hongbo Cheng, Jun Ouyang, Yun-Xiang Zhang, David J. Ascienzo, Yao Li, Yu-Yao Zhao, Yuhang Ren Dec 2017

Demonstration Of Ultra-High Recyclable Energy Densities In Domain-Engineered Ferroelectric Films, Hongbo Cheng, Jun Ouyang, Yun-Xiang Zhang, David J. Ascienzo, Yao Li, Yu-Yao Zhao, Yuhang Ren

Publications and Research

Dielectric capacitors have the highest charge/discharge speed among all electrical energy devices, but lag behind in energy density. Here we report dielectric ultracapacitors based on ferroelectric films of Ba(Zr0.2,Ti0.8)O3 which display high-energy densities (up to 166 J cm–3) and efficiencies (up to 96%). Different from a typical ferroelectric whose electric polarization is easily saturated, these Ba(Zr0.2,Ti0.8)O3 films display a much delayed saturation of the electric polarization, which increases continuously from nearly zero at remnant in a multipolar state, to a large value under the maximum electric field, leading ...


Dynamic Self-Assembly And Self-Organized Transport Of Magnetic Micro-Swimmers, Gašper Kokot, German Kolmakov V, Igor S. Aranson, Alexey Snezhko Nov 2017

Dynamic Self-Assembly And Self-Organized Transport Of Magnetic Micro-Swimmers, Gašper Kokot, German Kolmakov V, Igor S. Aranson, Alexey Snezhko

Publications and Research

We demonstrate experimentally and in computer simulations that magnetic microfloaters can self-organize into various functional structures while energized by an external alternating (ac) magnetic field. The structures exhibit self-propelled motion and an ability to carry a cargo along a pre-defined path. The morphology of the self-assembled swimmers is controlled by the frequency and amplitude of the magnetic field.


Experiential Learning Opportunity (Elo) And Utilization Of Field-And-Data- Based Information Obtained Through The Infusion Of Technology: Highlights On Nasa Stem And Earth Science Curricula, Nazrul I. Khandaker, Matthew Khargie, Shuayb Siddiqu, Sol De Leon, Katina Singh, Newrence Wills, Krishna Mahibar Oct 2017

Experiential Learning Opportunity (Elo) And Utilization Of Field-And-Data- Based Information Obtained Through The Infusion Of Technology: Highlights On Nasa Stem And Earth Science Curricula, Nazrul I. Khandaker, Matthew Khargie, Shuayb Siddiqu, Sol De Leon, Katina Singh, Newrence Wills, Krishna Mahibar

Publications and Research

There is a greater emphasis on hands-on involvement and critical thinking skills in the geosciences and other STEM fields to inspire and engage K- 16 students to value scientific content and enable them to discover the well-documented nature of the fundamental scientific principles needed to explain various earth science and other STEM-related core phenomena. NASA MAA curricula are ideal for engaging K1-16 students in this context, since grade-specific lesson plans open-up a plethora of pedagogically sound and relevant earth science activities. These include earth’s materials and properties, meteorites, robotics, hot air balloon, flight simulation, star gazing, material science, crystal ...


Stochastic Resonance In A Proton Pumping Complex I Of Mitochondria Membranes, Davneet Kaur, Ilan Filonenko, Lev Mourokh, Cornelius Fendler, Robert H. Blick Sep 2017

Stochastic Resonance In A Proton Pumping Complex I Of Mitochondria Membranes, Davneet Kaur, Ilan Filonenko, Lev Mourokh, Cornelius Fendler, Robert H. Blick

Publications and Research

We make use of the physical mechanism of proton pumping in the so-called Complex I within mitochondria membranes. Our model is based on sequential charge transfer assisted by conformational changes which facilitate the indirect electron-proton coupling. The equations of motion for the proton operators are derived and solved numerically in combination with the phenomenological Langevin equation describing the periodic conformational changes. We show that with an appropriate set of parameters, protons can be transferred against an applied voltage. In addition, we demonstrate that only the joint action of the periodic energy modulation and thermal noise leads to efficient uphill proton ...


Holography For Field Theory Solitons, Sophia K. Domokos, Andrew B. Royston Jul 2017

Holography For Field Theory Solitons, Sophia K. Domokos, Andrew B. Royston

Publications and Research

We extend a well-known D-brane construction of the AdS/dCFT correspondence to non-abelian defects. We focus on the bulk side of the correspondence and show that there exists a regime of parameters in which the low-energy description consists of two approximately decoupled sectors. The two sectors are gravity in the ambient spacetime, and a six-dimensional supersymmetric Yang-Mills theory. The Yang-Mills theory is defined on a rigid AdS4 S2 background and admits sixteen supersymmetries. We also consider a one-parameter deformation that gives rise to a family of Yang-Mills theories on asymptotically AdS4 S2 spacetimes, which are invariant under eight supersymmetries. With ...


Quadrality For Supersymmetric Matrix Models, Sebastian Franco, Sangmin Lee, Rak-Kyeong Seong, Cumrun Vafa Jul 2017

Quadrality For Supersymmetric Matrix Models, Sebastian Franco, Sangmin Lee, Rak-Kyeong Seong, Cumrun Vafa

Publications and Research

We introduce a new duality for N = 1 supersymmetric gauged matrix models. This 0d duality is an order 4 symmetry, namely an equivalence between four different theories, hence we call it Quadrality. Our proposal is motivated by mirror symmetry, but is not restricted to theories with a D-brane realization and holds for general N = 1 matrix models. We present various checks of the proposal, including the matching of: global symmetries, anomalies, deformations and the chiral ring. We also consider quivers and the corresponding quadrality networks. Finally, we initiate the study of matrix models that arise on the worldvolume of D ...


Light-Induced Electrohydrodynamic Instability In Plasmonically Absorbing Gold Nanofluids, Sujan Shrestha, Luat T. Vuong, Jorge Luis Dominguez-Juarez Jun 2017

Light-Induced Electrohydrodynamic Instability In Plasmonically Absorbing Gold Nanofluids, Sujan Shrestha, Luat T. Vuong, Jorge Luis Dominguez-Juarez

Publications and Research

Plasmonically absorbing nanofluids exhibit light-induced electrokinetics. We measure an electrical response to the light-induced Rayleigh-Bénard-Marangoni convective instabilities in gold-polyvinylpyrrolidone (PVP) nanoparticles (NPs) suspended in isopropanol and water. Microampere current oscillations are measured and attributed to the presence of the Au-PVP NPs with negative zeta potential, in correspondence with the accompanying thermal lens oscillations and a nanofluid thermoelectric effect. The measured electrical oscillations represent an electrohydrodynamic stability driven by light, one among many that should be observed with plasmonic nanoparticles in liquids.