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2020

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Articles 31 - 60 of 624

Full-Text Articles in Physical Sciences and Mathematics

Why Was Nicholson's Theory So Successful: An Explanation Of A Mysterious Episode In 20 Century Atomic Physics, Olga Kosheleva, Vladik Kreinovich Dec 2020

Why Was Nicholson's Theory So Successful: An Explanation Of A Mysterious Episode In 20 Century Atomic Physics, Olga Kosheleva, Vladik Kreinovich

Departmental Technical Reports (CS)

In the early 1910s, John Nicholson suggested that all atoms are formed by four basic elementary particles. This theory had a spectacular match with observations: it explained, with an unbelievable accuracy of 0.1, the atomic weights of all 92 elements known at that time. Specifically, it was shown that every atomic weight can be represented, with this accuracy, as an integer combination of four basic atomic weights. However, in a few years, this theory turned out to be completely wrong: atoms consist of protons, neutrons, and electrons, not of Nicholson's particles. This mysterious episode seems to contradict the usual development …

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Need For Shift-Invariant Fractional Differentiation Explains The Appearance Of Complex Numbers In Physics, Olga Kosheleva, Vladik Kreinovich Dec 2020

Need For Shift-Invariant Fractional Differentiation Explains The Appearance Of Complex Numbers In Physics, Olga Kosheleva, Vladik Kreinovich

Departmental Technical Reports (CS)

Complex numbers are ubiquitous in physics, they lead to a natural description of different physical processes and to efficient algorithms for solving the corresponding problems. But why this seemingly counterintuitive mathematical construction is so natural here? In this paper, we provide a possible explanation of this phenomenon: namely, we show that complex numbers appear if take into account that some physical system are described by derivatives of fractional order and that a physically meaningful analysis of such derivatives naturally leads to complex numbers.

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Why Physical Processes Are Smooth Or Almost Smooth: A Possible Physical Explanation Based On Intuitive Ideas Behind Energy Conservation, Olga Kosheleva, Vladik Kreinovich Dec 2020

Why Physical Processes Are Smooth Or Almost Smooth: A Possible Physical Explanation Based On Intuitive Ideas Behind Energy Conservation, Olga Kosheleva, Vladik Kreinovich

Departmental Technical Reports (CS)

While there are some non-smooth (and even discontinuous) processes in nature, most processes are smooth or almost smooth. This smoothness help estimate physical quantities, but a natural question is: why are physical processes smooth or almost smooth? Are there any fundamental reasons for this ubiquitous smoothness? In this paper, we provide a possible physical explanation for emirical smoothness: namely, we show that smoothness naturally follows from intuitive ideas behind energy conservation.

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Evidence For Electron Energization Accompanying Spontaneous Formation Of Ion Acceleration Regions In Expanding Plasmas, Evan M. Aguirre, Rikard Bodin, Neng Yin, Timothy N. Good, Earl E. Scime Dec 2020

Evidence For Electron Energization Accompanying Spontaneous Formation Of Ion Acceleration Regions In Expanding Plasmas, Evan M. Aguirre, Rikard Bodin, Neng Yin, Timothy N. Good, Earl E. Scime

Physics and Astronomy Faculty Publications

We report experiments conducted in an expanding argon plasma generated in the inductive mode of a helicon source in the Hot hELIcon eXperiment–Large Experiment on Instabilities and Anisotropies facility. As the neutral gas pressure increases, the supersonic ion acceleration weakens. Increasing neutral pressure also alters the radial profile of electron temperature, density, and plasma potential upstream of the plasma expansion region. Langmuir probe measurements of the electron energy probability function (EEPF) show that heating of electrons at the plasma edge by RF fields diminishes with increasing gas pressure, yielding a plasma with a centrally peaked electron temperature, and flat potential …

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The Importance Of Frontier Orbital Symmetry In The Adsorption Of Diiodobenzene On Mos2(0001), Prescott E. Evans, Zahra Hooshmand, Talat S. Rahman, Peter Dowben Dec 2020

The Importance Of Frontier Orbital Symmetry In The Adsorption Of Diiodobenzene On Mos2(0001), Prescott E. Evans, Zahra Hooshmand, Talat S. Rahman, Peter Dowben

Peter Dowben Publications

Evidence of a role of frontier orbital symmetry, in the adsorption process of diiodobenzene on MoS2(0001), appears in the huge differences in the rate of adsorption between 1,3-diiodobenzene, 1,2-diiodobenzene and 1,4-diiodobenzene isomers on MoS2. Experiments indicate that the rate of adsorption of 1,3-diiodobenzene on MoS2(0001) is much greater than that of the 1,2-diodobenzene and 1,4-diiodbenzene isomers. As the differences in calculated diiodobenzene isomer-MoS2 system adsorption energies and electron affinities are negligible, frontier orbital symmetry appears to play a significant role in diiodobenzene adsorption on MoS2(0001). The experimental and theory results, in combination, suggest …

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Spatial And Temporal Variability Of Carbonaceous Aerosol Absorption In The Po Valley, Stefania Gilardoni, Paola Massoli, Angela Marinoni, Claudio Mazzoleni, Andrew Freedman, Giovanni Lonati, Silvana De Iuliis, Vorne Gianelle Dec 2020

Spatial And Temporal Variability Of Carbonaceous Aerosol Absorption In The Po Valley, Stefania Gilardoni, Paola Massoli, Angela Marinoni, Claudio Mazzoleni, Andrew Freedman, Giovanni Lonati, Silvana De Iuliis, Vorne Gianelle

Michigan Tech Publications

Knowledge gaps in the optical properties of carbonaceous aerosols account for a significant fraction of the uncertainty of aerosol-light interactions in climate models. Both black carbon (BC) and brown carbon (BrC) can display a range of optical properties in ambient aerosol due to different sources and chemical transformation pathways. This study investigates the optical absorption properties of BC and BrC at an urban and a rural site in the Po Valley (Italy), a known European pollution hot spot. We observed spatial and seasonal variability of aerosol absorption coefficients, with the highest values measured in winter at the urban site of …

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3-D Fabry–Pérot Cavities Sculpted On Fiber Tips Using A Multiphoton Polymerization Process, Jonathan W. Smith, Jeremiah C. Williams, Joseph S. Suelzer, Nicholas G. Usechak, Hengky Chandrahalim Dec 2020

3-D Fabry–Pérot Cavities Sculpted On Fiber Tips Using A Multiphoton Polymerization Process, Jonathan W. Smith, Jeremiah C. Williams, Joseph S. Suelzer, Nicholas G. Usechak, Hengky Chandrahalim

Faculty Publications

This paper presents 3-D Fabry–Pérot (FP) cavities fabricated directly onto cleaved ends of low-loss optical fibers by a two-photon polymerization (2PP) process. This fabrication technique is quick, simple, and inexpensive compared to planar microfabrication processes, which enables rapid prototyping and the ability to adapt to new requirements. These devices also utilize true 3-D design freedom, facilitating the realization of microscale optical elements with challenging geometries. Three different device types were fabricated and evaluated: an unreleased single-cavity device, a released dual-cavity device, and a released hemispherical mirror dual-cavity device. Each iteration improved the quality of the FP cavity's reflection spectrum. The …

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All-Dielectric Magnetic Metasurface For Advanced Light Control In Dual Polarizations Combined With High-Q Resonances, Daria O. Ignatyeva, Dolendra Karki, Andrey A. Voronov, Mikhail A. Kozhaev, Denis M. Krichevsky, Alexander I. Chernov, Miguel Levy, Vladimir I. Belotelov Dec 2020

All-Dielectric Magnetic Metasurface For Advanced Light Control In Dual Polarizations Combined With High-Q Resonances, Daria O. Ignatyeva, Dolendra Karki, Andrey A. Voronov, Mikhail A. Kozhaev, Denis M. Krichevsky, Alexander I. Chernov, Miguel Levy, Vladimir I. Belotelov

Michigan Tech Publications

Nanostructured magnetic materials provide an efficient tool for light manipulation on sub-nanosecond and sub-micron scales, and allow for the observation of the novel effects which are fundamentally impossible in smooth films. For many cases of practical importance, it is vital to observe the magneto-optical intensity modulation in a dual-polarization regime. However, the nanostructures reported on up to date usually utilize a transverse Kerr effect and thus provide light modulation only for p-polarized light. We present a concept of a transparent magnetic metasurface to solve this problem, and demonstrate a novel mechanism for magneto-optical modulation. A 2D array of bismuth-substituted iron-garnet …

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Transfer-To-Transfer Learning Approach For Computer Aided Detection Of Covid-19 In Chest Radiographs, Barath Narayanan Narayanan, Russell C. Hardie, Vignesh Krishnaraja, Christina Karam, Venkata Salini Priyamvada Davuluru Dec 2020

Transfer-To-Transfer Learning Approach For Computer Aided Detection Of Covid-19 In Chest Radiographs, Barath Narayanan Narayanan, Russell C. Hardie, Vignesh Krishnaraja, Christina Karam, Venkata Salini Priyamvada Davuluru

Electrical and Computer Engineering Faculty Publications

The coronavirus disease 2019 (COVID-19) global pandemic has severely impacted lives across the globe. Respiratory disorders in COVID-19 patients are caused by lung opacities similar to viral pneumonia. A Computer-Aided Detection (CAD) system for the detection of COVID-19 using chest radiographs would provide a second opinion for radiologists. For this research, we utilize publicly available datasets that have been marked by radiologists into two-classes (COVID-19 and non-COVID-19). We address the class imbalance problem associated with the training dataset by proposing a novel transfer-to-transfer learning approach, where we break a highly imbalanced training dataset into a group of balanced mini-sets and …

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Quantum Oscillations From Networked Topological Interfaces In A Weyl Semimetal, I. Lin Liu, Colin Heikes, Taner Yildirim, Chris Eckberg, Tristin Metz, Hyunsoo Kim, Sheng Ran, William D. Ratcliff, Johnpierre Paglione, For Full List Of Authors, See Publisher's Website. Dec 2020

Quantum Oscillations From Networked Topological Interfaces In A Weyl Semimetal, I. Lin Liu, Colin Heikes, Taner Yildirim, Chris Eckberg, Tristin Metz, Hyunsoo Kim, Sheng Ran, William D. Ratcliff, Johnpierre Paglione, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Layered transition metal chalcogenides are promising hosts of electronic Weyl nodes and topological superconductivity. MoTe2 is a striking example that harbors both noncentrosymmetric Td and centrosymmetric T' phases, both of which have been identified as topologically nontrivial. Applied pressure tunes the structural transition separating these phases to zero temperature, stabilizing a mixed Td–T' matrix that entails a network of interfaces between the two nontrivial topological phases. Here, we show that this critical pressure range is characterized by distinct coherent quantum oscillations, indicating that the difference in topology between topologically nonvtrivial Td and T' phases gives …

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Tuning Magnetic Confinement Of Spin-Triplet Superconductivity, Wen Chen Lin, Daniel J. Campbell, Sheng Ran, I. Lin Liu, Hyunsoo Kim, Andriy H. Nevidomskyy, David Graf, Nicholas P. Butch, Johnpierre Paglione Dec 2020

Tuning Magnetic Confinement Of Spin-Triplet Superconductivity, Wen Chen Lin, Daniel J. Campbell, Sheng Ran, I. Lin Liu, Hyunsoo Kim, Andriy H. Nevidomskyy, David Graf, Nicholas P. Butch, Johnpierre Paglione

Physics Faculty Research & Creative Works

Electrical magnetoresistance and tunnel diode oscillator measurements were performed under external magnetic fields up to 41 T applied along the crystallographic b axis (hard axis) of UTe2 as a function of temperature and applied pressures up to 18.8 kbar. In this work, we track the field-induced first-order transition between superconducting and magnetic field-polarized phases as a function of applied pressure, showing suppression of the transition with increasing pressure until the demise of superconductivity near 16 kbar and the appearance of a pressure-induced ferromagnetic-like ground state that is distinct from the field-polarized phase and stable at zero field. Together with …

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Polarization-Selective Modulation Of Supercavity Resonances Originating From Bound States In The Continuum, Chan Kyaw, Riad Yahiaoui, Joshua A. Burrow, Viet Tran, Kyron Keelen, Wesley Sims, Eddie C. Red, Willie S. Rockward, Mikkel A. Thomas, Andrew M. Sarangan, Imad Agha, Thomas A. Searles Dec 2020

Polarization-Selective Modulation Of Supercavity Resonances Originating From Bound States In The Continuum, Chan Kyaw, Riad Yahiaoui, Joshua A. Burrow, Viet Tran, Kyron Keelen, Wesley Sims, Eddie C. Red, Willie S. Rockward, Mikkel A. Thomas, Andrew M. Sarangan, Imad Agha, Thomas A. Searles

Electro-Optics and Photonics Faculty Publications

Bound states in the continuum (BICs) are widely studied for their ability to confine light, produce sharp resonances for sensing applications and serve as avenues for lasing action with topological characteristics. Primarily, the formation of BICs in periodic photonic band gap structures are driven by symmetry incompatibility; structural manipulation or variation of incidence angle from incoming light. In this work, we report two modalities for driving the formation of BICs in terahertz metasurfaces. At normal incidence, we experimentally confirm polarization driven symmetry-protected BICs by the variation of the linear polarization state of light. In addition, we demonstrate through strong coupling …

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Parton Distribution Functions From Ioffe Time Pseudodistributions From Lattice Calculations: Approaching The Physical Point, Bálint Joó, Joseph Karpie, Kostas Orginos, Anatoly V. Radyushkin, David G. Richards, Savvas Zafeiropoulos Dec 2020

Parton Distribution Functions From Ioffe Time Pseudodistributions From Lattice Calculations: Approaching The Physical Point, Bálint Joó, Joseph Karpie, Kostas Orginos, Anatoly V. Radyushkin, David G. Richards, Savvas Zafeiropoulos

Physics Faculty Publications

We present results for the unpolarized parton distribution function of the nucleon computed in lattice QCD at the physical pion mass. This is the first study of its kind employing the method of Ioffe time pseudodistributions. Beyond the reconstruction of the Bjorken-x dependence, we also extract the lowest moments of the distribution function using the small Ioffe time expansion of the Ioffe time pseudodistribution. We compare our findings with the pertinent phenomenological determinations.

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A Climatological Analysis Of The Monsoon Break Following The Summer Monsoon Onset Over Luzon Island, Philippines, Lyndon Mark P. Olaguera, Jun Matsumoto, Hisayuki Kubota, Esperanza O. Cayanan, Flaviana D. Hilario Nov 2020

A Climatological Analysis Of The Monsoon Break Following The Summer Monsoon Onset Over Luzon Island, Philippines, Lyndon Mark P. Olaguera, Jun Matsumoto, Hisayuki Kubota, Esperanza O. Cayanan, Flaviana D. Hilario

Physics Faculty Publications

This study investigates the climatology of the monsoon break following the onset of the summer rainy season over Luzon Island (120–122.5°E, 13–22°N) in the Philippines from 1979–2017. The first post-onset monsoon break is remarkable in stations located over the north and central Luzon Island and occurs climatologically in early June. Composite analysis of the large-scale circulation features during the monsoon break period shows that this break is associated with the westward extension of the western North Pacific Subtropical High (WNPSH), which weakened the monsoon southwesterlies and induced enhanced low-level divergence over Luzon Island. The westward extension of the WNPSH may …

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A Model For Massless Gravitons In Radiation And Matter Dominated Universes, Ioannis Haranas, Eli Cavan, Ioannis Gkigkitzis Nov 2020

A Model For Massless Gravitons In Radiation And Matter Dominated Universes, Ioannis Haranas, Eli Cavan, Ioannis Gkigkitzis

Physics and Computer Science Faculty Publications

A massless model of the graviton is explored by considering the minimum amount of information they can carry. The total entropy of the universe is calculated and compared to estimates from Super Massive Black holes and massive models of the graviton. The running cosmological constant is calculated using the entropy relation previously computed and compared to its experimentally accepted value. Both results are quantified considering radiation and matter dominated universes.

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The Vimentin Cytoskeleton: When Polymer Physics Meets Cell Biology, Alison E. Patteson, Robert J. Carroll, Daniel V. Iwamoto, Paul A. Janmey Nov 2020

The Vimentin Cytoskeleton: When Polymer Physics Meets Cell Biology, Alison E. Patteson, Robert J. Carroll, Daniel V. Iwamoto, Paul A. Janmey

Physics - All Scholarship

The proper functions of tissues depend on the ability of cells to withstand stress and maintain shape. Central to this process is the cytoskeleton, comprised of three polymeric networks: F-actin, microtubules, and intermediate filaments (IFs). IF proteins are among the most abundant cytoskeletal proteins in cells; yet they remain some of the least understood. Their structure and function deviate from those of their cytoskeletal partners, F-actin and microtubules. IF networks show a unique combination of extensibility, flexibility and toughness that confers mechanical resilience to the cell. Vimentin is an IF protein expressed in mesenchymal cells. This review highlights exciting new …

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Response Of The Mode Grüneisen Parameters With Anisotropic Compression: A Pressure And Temperature Dependent Raman Study Of Β-Sn, Jasmine K. Hinton, Christian Childs, Dean Smith, Paul B. Ellison, Keith V. Lawler, Ashkan Salamat Nov 2020

Response Of The Mode Grüneisen Parameters With Anisotropic Compression: A Pressure And Temperature Dependent Raman Study Of Β-Sn, Jasmine K. Hinton, Christian Childs, Dean Smith, Paul B. Ellison, Keith V. Lawler, Ashkan Salamat

Physics & Astronomy Faculty Research

The lattice dynamic response of body-centered tetragonal β−Sn (I41/amd) under high pressure and -temperature conditions is determined using experimental optical vibration modes. Raman scattering is used to map the phase stability region of β−Sn to perform mode Grüneisen analysis, and we demonstrate the necessity of an optical intensity calibration for Raman thermometry. The Grüneisen tensor is evaluated along a set of isotherms to address shortcomings of single-mode Grüneisen parameters with respect to anisotropic deformations of this tetragonal structured soft metal. The changes observed here in the Grüneisen tensor as a function of temperature are related to anharmonicity and denote potential …

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A Significant Excess In Major Merger Rate For Agns With The Highest Eddington Ratios At Z < 0.2, Victor Marian, Knud Jahnke, Irham Andika, Eduardo Bañados, Vardha N. Bennert, Seth Cohen, Bernd Husemann, Melanie Kaasinen, Anton M. Koekemoer, Mira Mechtley, Masafusa Onoue, Jan-Torge Schindler, Malte Schramm, Andreas Schulze, John D. Silverman, Irina Smirnova-Pinchukova, Arjen Van Der Wel, Carolin Villforth, Rogier A. Windhorst Nov 2020

A Significant Excess In Major Merger Rate For Agns With The Highest Eddington Ratios At Z < 0.2, Victor Marian, Knud Jahnke, Irham Andika, Eduardo Bañados, Vardha N. Bennert, Seth Cohen, Bernd Husemann, Melanie Kaasinen, Anton M. Koekemoer, Mira Mechtley, Masafusa Onoue, Jan-Torge Schindler, Malte Schramm, Andreas Schulze, John D. Silverman, Irina Smirnova-Pinchukova, Arjen Van Der Wel, Carolin Villforth, Rogier A. Windhorst

Physics

Observational studies are increasingly finding evidence against major mergers being the dominant mechanism responsible for triggering an active galactic nucleus (AGN). After studying the connection between major mergers and AGNs with the highest Eddington ratios at z = 2, we here expand our analysis to z < 0.2, exploring the same AGN parameter space. Using ESO VLT/FORS2 B-, V-, and color images, we examine the morphologies of 17 galaxies hosting AGNs with Eddington ratios , and 25 mass- and redshift-matched control galaxies. To match the appearance of the two samples, we add synthetic point sources to the inactive comparison galaxies. The combined sample of AGN and inactive galaxies was …

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Band Structure Topology And Spin Transport In Magnon Systems, Bo Li Nov 2020

Band Structure Topology And Spin Transport In Magnon Systems, Bo Li

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

As the spin excitation quanta in magnetic materials, the magnon is at the heart of the spintronics research because it plays a key role in magnetic dynamics, energy and spin transport, and even determining the ground state of magnetic systems. In this thesis, we will study the band-structure topology and transport properties of magnons in both collinear and noncollinear magnets. Inspired by the great success of topological insulators, exploring magnon topology can unveil the topological nature of bosonic particles and widen the zoo of topological materials. We propose a three-dimensional magnon topological insulator model protected by sublattice chiral symmetries, which …

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Non-Hermitian Topology Of One-Dimensional Spin-Torque Oscillator Arrays, Benedetta Flebus, Rembert A. Duine, Hilary M. Hurst Nov 2020

Non-Hermitian Topology Of One-Dimensional Spin-Torque Oscillator Arrays, Benedetta Flebus, Rembert A. Duine, Hilary M. Hurst

Faculty Research, Scholarly, and Creative Activity

Magnetic systems have been extensively studied both from a fundamental physics perspective and as building blocks for a variety of applications. Their topological properties, in particular those of excitations, remain relatively unexplored due to their inherently dissipative nature. The recent introduction of non-Hermitian topological classifications opens up new opportunities for engineering topological phases in dissipative systems. Here, we propose a magnonic realization of a non-Hermitian topological system. A crucial ingredient of our proposal is the injection of spin current into the magnetic system, which alters and can even change the sign of terms describing dissipation. We show that the magnetic …

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Induced Interactions And Quench Dynamics Of Bosonic Impurities Immersed In A Fermi Sea, K. Mukherjee, Simeon I. Mistakidis, S. Majumder, P. Schmelcher Nov 2020

Induced Interactions And Quench Dynamics Of Bosonic Impurities Immersed In A Fermi Sea, K. Mukherjee, Simeon I. Mistakidis, S. Majumder, P. Schmelcher

Physics Faculty Research & Creative Works

We Unravel The Ground-State Properties And The Nonequilibrium Quantum Dynamics Of Two Bosonic Impurities Immersed In A One-Dimensional Fermionic Environment By Applying A Quench Of The Impurity-Medium Interaction Strength. In The Ground State, The Impurities And The Fermi Sea Are Phase Separated For Strong Impurity-Medium Repulsions While They Experience A Localization Tendency Around The Trap Center For Large Attractions. We Demonstrate The Presence Of Attractive Induced Interactions Mediated By The Host For Impurity-Medium Couplings Of Either Sign And Analyze The Competition Between Induced And Direct Interactions. A Quench To Repulsive Interactions Triggers A Breathing Motion In Both Components, With An …

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Making Artificial Cips Data With A Generative Adversarial Neural Network, Austin Hedges Nov 2020

Making Artificial Cips Data With A Generative Adversarial Neural Network, Austin Hedges

Fall Showcase for Research and Creative Inquiry

Polar mesospheric clouds (PMCs) have been studied for thirteen years by NASA's Aeronomy of Ice in the Mesosphere (AIM) satellite. The Cloud Imaging and Particle Size (CIPS) instrument onboard AIM has taken many images of PMCs over this time. Such a large number of images makes CIPS data ideal for training neural networks which require large datasets. CIPS images were used to train a Generative Adversarial Network (GAN) to train towards being able to generate purely artificial CIPS-like images.

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Atmospheric Turbulence Study With Deep Machine Learning Of Intensity Scintillation Patterns, Artem V. Vorontsov, Mikhail A. Vorontsov, Grigorii A. Fillimonov, Ernst Polnau Nov 2020

Atmospheric Turbulence Study With Deep Machine Learning Of Intensity Scintillation Patterns, Artem V. Vorontsov, Mikhail A. Vorontsov, Grigorii A. Fillimonov, Ernst Polnau

Electro-Optics and Photonics Faculty Publications

A new paradigm for machine learning-inspired atmospheric turbulence sensing is developed and applied to predict the atmospheric turbulence refractive index structure parameter using deep neural network (DNN)-based processing of short-exposure laser beam intensity scintillation patterns obtained with both: experimental measurement trials conducted over a 7 km propagation path, and imitation of these trials using wave-optics numerical simulations. The developed DNN model was optimized and evaluated in a set of machine learning experiments. The results obtained demonstrate both good accuracy and high temporal resolution in sensing. The machine learning approach was also employed to challenge the validity of several eminent atmospheric …

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Cft Unitarity And The Ads Cutkosky Rules, David Meltzer, Allic Sivaramakrishnan Nov 2020

Cft Unitarity And The Ads Cutkosky Rules, David Meltzer, Allic Sivaramakrishnan

Physics and Astronomy Faculty Publications

We derive the Cutkosky rules for conformal field theories (CFTs) at weak and strong coupling. These rules give a simple, diagrammatic method to compute the double-commutator that appears in the Lorentzian inversion formula. We first revisit weakly-coupled CFTs in flat space, where the cuts are performed on Feynman diagrams. We then generalize these rules to strongly-coupled holographic CFTs, where the cuts are performed on the Witten diagrams of the dual theory. In both cases, Cutkosky rules factorize loop diagrams into on-shell sub-diagrams and generalize the standard S-matrix cutting rules. These rules are naturally formulated and derived in Lorentzian momentum space, …

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Proximity-Induced Magnetization In Graphene: Towards Efficient Spin Gating, Mihovil Bosnar, Ivor Lončarić, P. Lazić, Kirill Belashchenko, Igor Žutić Nov 2020

Proximity-Induced Magnetization In Graphene: Towards Efficient Spin Gating, Mihovil Bosnar, Ivor Lončarić, P. Lazić, Kirill Belashchenko, Igor Žutić

Kirill Belashchenko Publications

Gate-tunable spin-dependent properties could be induced in graphene at room temperature through the magnetic proximity effect by placing it in contact with a metallic ferromagnet. Because strong chemical bonding with the metallic substrate makes gating ineffective, an intervening passivation layer is needed. Previously considered passivation layers result in a large shift of the Dirac point away from the Fermi level, so that unrealistically large gate fields are required to tune the spin polarization in graphene (Gr). We show that a monolayer of Au or Pt used as the passivation layer between Co and graphene brings the Dirac point closer to …

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Photo-Production Of Eta Mesons, Mahmoud Mohamed Kamel Nov 2020

Photo-Production Of Eta Mesons, Mahmoud Mohamed Kamel

FIU Electronic Theses and Dissertations

In this work we present the GlueX experiment extensive high statistics measurements of the η meson photo-production differential cross sections at beam energies between 3 GeV and 11.6 GeV. We compared the low energy (2.9 GeV< Eγ < 5.9 GeV) differential cross section (dσ/dΩ) results to previous experimental results from the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) collaboration. These (dσ/dΩ) results are also compared to the theoretical isobar model EtaMAID2018 by Tiator et. al., and the Regge model by Nys et. al. The differential cross section dσ/dt is also presented and compared to the previous experimental results, and to the above models, in addition to a model by J. M. Laget. The high energy (6.2 GeV< Eγ < 11.6 GeV) cross section results (dσ/dΩ, and dσ/dt) are compared to the isobar model EtaMAID2018. These results will provide new constraints on η photo-production mechanisms and high energy t- channel processes.

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Discovering Rare-Earth-Free Magnetic Materials Through The Development Of A Database, Masahiro Sakurai, Renhai Wang, Timothy Liao, Chao Zhang, Huaijun Sun, Yang Sun, Haidi Wang, Xin Zhao, Songyou Wang, Balamurugan Balasubramanian, Xiaoshan S. Xu, David J. Sellmyer, Vladimir Antropov, Jianhua Zhang, Cai-Zhuang Wang, Kai-Ming Ho, James R. Chelikowsky Nov 2020

Discovering Rare-Earth-Free Magnetic Materials Through The Development Of A Database, Masahiro Sakurai, Renhai Wang, Timothy Liao, Chao Zhang, Huaijun Sun, Yang Sun, Haidi Wang, Xin Zhao, Songyou Wang, Balamurugan Balasubramanian, Xiaoshan S. Xu, David J. Sellmyer, Vladimir Antropov, Jianhua Zhang, Cai-Zhuang Wang, Kai-Ming Ho, James R. Chelikowsky

Department of Physics and Astronomy: Faculty Publications

We develop an open-access database that provides a large array of datasets specialized for magnetic compounds as well as magnetic clusters. Our focus is on rare-earth-free magnets. Available datasets include (i) crystallography, (ii) thermodynamic properties, such as the formation energy, and (iii) magnetic properties that are essential for magnetic-material design. Our database features a large number of stable and metastable structures discovered through our adaptive genetic algorithm (AGA) searches. Many of these AGA structures have better magnetic properties when compared to those of the existing rare-earth-free magnets and the theoretical structures in other databases. Our database places particular emphasis on …

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Production Of B¯B At Forward Rapidity In P+P Collisions At √S=510  Gev, Mike Daugherity, Donald Isenhower, Rusty Towell Nov 2020

Production Of B¯B At Forward Rapidity In P+P Collisions At √S=510  Gev, Mike Daugherity, Donald Isenhower, Rusty Towell

Engineering and Physics

The cross section of bottom quark-antiquark (b¯b) production in p+p collisions at √s=510  GeV is measured with the PHENIX detector at the Relativistic Heavy Ion Collider. The results are based on the yield of high mass, like-sign muon pairs measured within the PHENIX muon arm acceptance (1.2<|y|<2.2). The b¯b signal is extracted from like-sign dimuons by utilizing the unique properties of neutral B meson oscillation. We report a differential cross section of dσb¯b→μ±μ±/dy=0.16±0.01 (stat)±0.02 (syst)±0.02 (global)  nb for like-sign muons in the rapidity and pT ranges 1.2<|y|<2.2 and pT>1  GeV/c, and dimuon mass of 5–10  GeV/c2. The extrapolated total cross section at this energy for b¯b production is 13.1±0.6 (stat)±1.5 (syst)±2.7 (global) μb. The total cross section is compared to a perturbative quantum chromodynamics calculation and is consistent within uncertainties. The azimuthal opening angle between muon pairs from b¯b decays and …

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Effective Number Theory: Counting The Identities Of A Quantum State, Ivan Horváth, Robert Mendris Nov 2020

Effective Number Theory: Counting The Identities Of A Quantum State, Ivan Horváth, Robert Mendris

Anesthesiology Faculty Publications

Quantum physics frequently involves a need to count the states, subspaces, measurement outcomes, and other elements of quantum dynamics. However, with quantum mechanics assigning probabilities to such objects, it is often desirable to work with the notion of a “total” that takes into account their varied relevance. For example, such an effective count of position states available to a lattice electron could characterize its localization properties. Similarly, the effective total of outcomes in the measurement step of a quantum computation relates to the efficiency of the quantum algorithm. Despite a broad need for effective counting, a well-founded prescription has not …

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Atmospheric Measurements With Unmanned Aerial Systems (Uas), Marcelo I. Guzman Nov 2020

Atmospheric Measurements With Unmanned Aerial Systems (Uas), Marcelo I. Guzman

Chemistry Faculty Publications

This Special Issue provides the first literature collection focused on the development and implementation of unmanned aircraft systems (UAS) and their integration with sensors for atmospheric measurements on Earth. The research covered in the Special Issue combines chemical, physical, and meteorological measurements performed in field campaigns as well as conceptual and laboratory work. Useful examples for the development of platforms and autonomous systems for environmental studies are provided, which demonstrate how careful the operation of sensors aboard UAS must be to gather information for remote sensing in the atmosphere. The work serves as a key collection of articles to introduce …

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