Magnetogenesis through Relativistic Velocity Shear
Miller, Evan
Magnetic fields at all scales are prevalent in our universe. However, current cosmological models predict that initially the universe was bereft of large-scale fields. Standard magnetohydrodynamics (MHD) does not permit magnetogenesis; in the MHD Faraday's law, the change in magnetic field B depends on B itself. Thus if B is initially zero, it will remain zero for all time. A more accurate physical model is needed to explain the origins of the galactic-scale magnetic fields observed today. In this thesis, I explore two velocity-driven mechanisms for magnetogenesis in 2-fluid plasma. The first is a novel kinematic 'battery' arising from convection of vorticity. A coupling between thermal and plasma oscillations, this non-relativistic mechanism can operate in flows that are incompressible, quasi-neutral and barotropic. The second mechanism results from inclusion of thermal effects in relativistic shear flow instabilities. In such flows, parallel perturbations are ubiquitously unstable at small scales, with growth rates of order with the plasma frequency over a defined range of parameter-space. Of these two processes, instabilities seem far more likely to account for galactic magnetic fields. Stable kinematic effects will, at best, be comparable to an ideal Biermann battery, which is suspected to be orders of magnitude too weak to produce the observed galactic fields. On the other hand, instabilities grow until saturation is reached, a topic that has yet to be explored in detail on cosmological scales. In addition to investigating these magnetogenesis sources, I derive a general dispersion relation for three dimensional, warm, two species plasma with discontinuous shear flow. The mathematics of relativistic plasma, sheared-flow instability and the Biermann battery are also discussed.
Relativistic and Non-relativistic Equations of Motion
Mangiarotti, L
1998-01-01
It is shown that any second order dynamic equation on a configuration space $X$ of non-relativistic time-dependent mechanics can be seen as a geodesic equation with respect to some (non-linear) connection on the tangent bundle $TX\\to X$ of relativistic velocities. Using this fact, the relationship between relativistic and non-relativistic equations of motion is studied.
Relativistic r-modes and shear viscosity
Gualtieri, L; Miralles, J A; Ferrari, V
2006-01-01
We derive the relativistic equations for stellar perturbations, including in a consistent way shear viscosity in the stress-energy tensor, and we numerically integrate our equations in the case of large viscosity. We consider the slow rotation approximation, and we neglect the coupling between polar and axial perturbations. In our approach, the frequency and damping time of the emitted gravitational radiation are directly obtained. We find that, approaching the inviscid limit from the finite viscosity case, the continuous spectrum is regularized. Constant density stars, polytropic stars, and stars with realistic equations of state are considered. In the case of constant density stars and polytropic stars, our results for the viscous damping times agree, within a factor two, with the usual estimates obtained by using the eigenfunctions of the inviscid limit. For realistic neutron stars, our numerical results give viscous damping times with the same dependence on mass and radius as previously estimated, but sys...
Towards universal quantum computation through relativistic motion
Bruschi, David Edward; Kok, Pieter; Johansson, Göran; Delsing, Per; Fuentes, Ivette
2013-01-01
We show how to use relativistic motion to generate continuous variable Gaussian cluster states within cavity modes. Our results can be demonstrated experimentally using superconducting circuits where tunable boundary conditions correspond to mirrors moving with velocities close to the speed of light. In particular, we propose the generation of a quadripartite square cluster state as a first example that can be readily implemented in the laboratory. Since cluster states are universal resources for universal one-way quantum computation, our results pave the way for relativistic quantum computation schemes.
Strong electron-scale instability in relativistic shear flows
Alves, Eduardo Paulo; Grismayer, Thomas; Fonseca, Ricardo; Silva, Luis
2013-10-01
Collisionless shear-driven plasma instabilities have recently been shown to be capable of generating strong and large-scale magnetic fields and may therefore play an important role in relativistic astrophysical outflows. We present a new collisionless shear-driven plasma instability, which operates in the plane transverse to the Kelvin Helmholtz instability (KHI). We develop the linear stability analysis of electromagnetic modes in the transverse plane and find that the growth rate of this instability is greater than the competing KHI in relativistic shears. The analytical results are confirmed with 2D particle-in-cell (PIC) simulations. Simulations also reveal the nonlinear evolution of the instability which leads to the development of mushroom-like electron-density structures, similar to the Rayleigh Taylor instability. Finally, the interplay between the competing instabilities is investigated in 3D PIC simulations.
Equations of motion in relativistic gravity
Lämmerzahl, Claus; Schutz, Bernard
2015-01-01
The present volume aims to be a comprehensive survey on the derivation of the equations of motion, both in General Relativity as well as in alternative gravity theories. The topics covered range from the description of test bodies, to self-gravitating (heavy) bodies, to current and future observations. Emphasis is put on the coverage of various approximation methods (e.g., multipolar, post-Newtonian, self-force methods) which are extensively used in the context of the relativistic problem of motion. Applications discussed in this volume range from the motion of binary systems -- and the gravitational waves emitted by such systems -- to observations of the galactic center. In particular the impact of choices at a fundamental theoretical level on the interpretation of experiments is highlighted. This book provides a broad and up-do-date status report, which will not only be of value for the experts working in this field, but also may serve as a guideline for students with background in General Relativity who ...
Pireaux, S
2008-01-01
The Relativistic Motion Integrator (RMI) consists in integrating numerically the EXACT relativistic equations of motion, with respect to the appropriate gravitational metric, instead of Newtonian equations plus relativistic corrections. The aim of the present paper is to validate the method, and to illustrate how RMI can be used for space missions to produce relativistic ephemerides of satellites. Indeed, nowadays, relativistic effects have to be taken into account, and comparing a RMI ephemeris with a classical keplerian one helps to quantify such effects. LISA is a relevant example to use RMI. This mission is an interferometer formed by three spacecraft which aims at the detection of gravitational waves. Precise ephemerides of LISA spacecraft are needed not only for the sake of the orbitography but also to compute the photon flight time in laser links between spacecraft, required in LISA data pre-processing in order to reach the gravitational wave detection level. Relativistic effects in LISA orbitography n...
Transverse electron-scale instability in relativistic shear flows
Alves, E P; Fonseca, R A; Silva, L O
2015-01-01
Electron-scale surface waves are shown to be unstable in the transverse plane of a shear flow in an initially unmagnetized plasma, unlike in the (magneto)hydrodynamics case. It is found that these unstable modes have a higher growth rate than the closely related electron-scale Kelvin-Helmholtz instability in relativistic shears. Multidimensional particle-in-cell simulations verify the analytic results and further reveal the emergence of mushroom-like electron density structures in the nonlinear phase of the instability, similar to those observed in the Rayleigh Taylor instability despite the great disparity in scales and different underlying physics. Macroscopic ($\\gg c/\\omega_{pe}$) fields are shown to be generated by these microscopic shear instabilities, which are relevant for particle acceleration, radiation emission and to seed MHD processes at long time-scales.
New shear-free relativistic models with heat flow
Msomi, A M; Maharaj, S D
2013-01-01
We study shear-free spherically symmetric relativistic models with heat flow. Our analysis is based on Lie's theory of extended groups applied to the governing field equations. In particular, we generate a five-parameter family of transformations which enables us to map existing solutions to new solutions. All known solutions of Einstein equations with heat flow can therefore produce infinite families of new solutions. In addition, we provide two new classes of solutions utilising the Lie infinitesimal generators. These solutions generate an infinite class of solutions given any one of the two unknown metric functions.
Relativistic diffusive motion in random electromagnetic fields
Haba, Z, E-mail: zhab@ift.uni.wroc.pl [Institute of Theoretical Physics, University of Wroclaw, 50-204 Wroclaw, Plac Maxa Borna 9 (Poland)
2011-08-19
We show that the relativistic dynamics in a Gaussian random electromagnetic field can be approximated by the relativistic diffusion of Schay and Dudley. Lorentz invariant dynamics in the proper time leads to the diffusion in the proper time. The dynamics in the laboratory time gives the diffusive transport equation corresponding to the Juettner equilibrium at the inverse temperature {beta}{sup -1} = mc{sup 2}. The diffusion constant is expressed by the field strength correlation function (Kubo's formula).
Relativistic Motion of Spinning Particles in a Gravitational Field
Chicone, C.; Mashhoon, B.; Punsly, B.
2005-01-01
The relative motion of a classical relativistic spinning test particle is studied with respect to a nearby free test particle in the gravitational field of a rotating source. The effects of the spin-curvature coupling force are elucidated and the implications of the results for the motion of rotating plasma clumps in astrophysical jets are discussed.
Relativistic motion of spinning particles in a gravitational field
Chicone, C.; Mashhoon, B.; Punsly, B.
2005-08-01
The relative motion of a classical relativistic spinning test particle is studied with respect to a nearby free test particle in the gravitational field of a rotating source. The effects of the spin-curvature coupling force are elucidated and the implications of the results for the motion of rotating plasma clumps in astrophysical jets are discussed.
Magnetic Field Generation and Particle Energization in Relativistic Shear Flows
Liang, Edison; Boettcher, Markus; Smith, Ian
2012-10-01
We present Particle-in-Cell simulation results of magnetic field generation by relativistic shear flows in collisionless electron-ion (e-ion) and electron-positron (e+e-) plasmas. In the e+e- case, small current filaments are first generated at the shear interface due to streaming instabilities of the interpenetrating particles from boundary perturbations. Such current filaments create transverse magnetic fields which coalesce into larger and larger flux tubes with alternating polarity, eventually forming ordered flux ropes across the entire shear boundary layer. Particles are accelerated across field lines to form power-law tails by semi-coherent electric fields sustained by oblique Langmuir waves. In the e-ion case, a single laminar slab of transverse flux rope is formed at the shear boundary, sustained by thin current sheets on both sides due to different drift velocities of electrons and ions. The magnetic field has a single polarity for the entire boundary layer. Electrons are heated to a fraction of the ion energy, but there is no evidence of power-law tail forming in this case.
New charged shear-free relativistic models with heat flux
Nyonyi, Y; Govinder, K S
2014-01-01
We study shear-free spherically symmetric relativistic gravitating fluids with heat flow and electric charge. The solution to the Einstein-Maxwell system is governed by the generalised pressure isotropy condition which contains a contribution from the electric field. This condition is a highly nonlinear partial differential equation. We analyse this master equation using Lie's group theoretic approach. The Lie symmetry generators that leave the equation invariant are found. The first generator is independent of the electromagnetic field. The second generator depends critically on the form of the charge, which is determined explicitly in general. We provide exact solutions to the gravitational potentials using the symmetries admitted by the equation. Our new exact solutions contain earlier results without charge. We show that other charged solutions, related to the Lie symmetries, may be generated using the algorithm of Deng. This leads to new classes of charged Deng models which are generalisations of conform...
New charged shear-free relativistic models with heat flux
Nyonyi, Y.; Maharaj, S. D.; Govinder, K. S.
2013-11-01
We study shear-free spherically symmetric relativistic gravitating fluids with heat flow and electric charge. The solution to the Einstein-Maxwell system is governed by the generalised pressure isotropy condition which contains a contribution from the electric field. This condition is a highly nonlinear partial differential equation. We analyse this master equation using Lie's group theoretic approach. The Lie symmetry generators that leave the equation invariant are found. The first generator is independent of the electromagnetic field. The second generator depends critically on the form of the charge, which is determined explicitly in general. We provide exact solutions to the gravitational potentials using the symmetries admitted by the equation. Our new exact solutions contain earlier results without charge. We show that other charged solutions, related to the Lie symmetries, may be generated using the algorithm of Deng. This leads to new classes of charged Deng models which are generalisations of conformally flat metrics.
Effect of relativistic motion on witnessing nonclassicality of quantum states
Checińska, Agata; Lorek, Krzysztof; Dragan, Andrzej
2017-01-01
We show that the operational definition of nonclassicality of a quantum state depends on the motion of the observer. We use the relativistic Unruh-DeWitt detector model to witness nonclassicality of the probed field state. It turns out that the witness based on the properties of the P representation of the quantum state depends on the trajectory of the detector. Inertial and noninertial motion of the device have qualitatively different impact on the performance of the witness.
Relativistic description of the Fermi motion effects on deuterium targets
Kusno, D.
1979-12-01
A comprehensive analysis of the inconsistencies of the conventional, non-relativistic approach, which has been used so far in the extraction of neutron data from deuterium targets, is given. A new approach dealing with the smearing effects, due to the nucleon's Fermi motion inside the deuteron, is developed as an alternative to the conventional one. This new approach is a spin-less, relativistic, simple and consistent approach. A new covariant model of the elastic electromagnetic form factors of the deuteron in the impulse approximation is also presented. The treatment includes spin and allows for a possibility of determining completely the two elastic structure functions.
Chaotic Motion of Relativistic Electrons Driven by Whistler Waves
Khazanov, G. V.; Telnikhin, A. A.; Kronberg, Tatiana K.
2007-01-01
Canonical equations governing an electron motion in electromagnetic field of the whistler mode waves propagating along the direction of an ambient magnetic field are derived. The physical processes on which the equations of motion are based .are identified. It is shown that relativistic electrons interacting with these fields demonstrate chaotic motion, which is accompanied by the particle stochastic heating and significant pitch angle diffusion. Evolution of distribution functions is described by the Fokker-Planck-Kolmogorov equations. It is shown that the whistler mode waves could provide a viable mechanism for stochastic energization of electrons with energies up to 50 MeV in the Jovian magnetosphere.
The Hydrogen Atom in Relativistic Motion
Jarvinen, M
2004-01-01
The Lorentz contraction of bound states in field theory is often appealed to in qualitative descriptions of high energy particle collisions. Surprisingly, the contraction has not been demonstrated explicitly even in simple cases such as the Hydrogen atom. It requires a calculation of wave functions evaluated at equal (ordinary) time for bound states in motion. Such wave functions are not obtained by kinematic boosts from the rest frame. Starting from the exact Bethe-Salpeter equation we derive the equal-time wave function of a fermion-antifermion bound state in QED, i.e., positronium or the Hydrogen atom, in any frame to leading order in alpha. We show explicitly that the bound state energy transforms as the fourth component of a vector and that the wave function of the fermion-antifermion Fock state contracts as expected. Transverse photon exchange contributes at leading order to the binding energy of the bound state in motion. We study the general features of the corresponding fermion-antifermion-photon Foc...
Slow down of a globally neutral relativistic $e^-e^+$ beam shearing the vacuum
Alves, E P; Silveirinha, M G; Fonseca, R A; Silva, L O
2015-01-01
The microphysics of relativistic collisionless sheared flows is investigated in a configuration consisting of a globally neutral, relativistic $e^-e^+$ beam streaming through a hollow plasma/dielectric channel. We show through multidimensional PIC simulations that this scenario excites the Mushroom instability (MI), a transverse shear instability on the electron-scale, when there is no overlap (no contact) between the $e^-e^+$ beam and the walls of the hollow plasma channel. The onset of the MI leads to the conversion of the beam's kinetic energy into magnetic (and electric) field energy, effectively slowing down a globally neutral body in the absence of contact. The collisionless shear physics explored in this configuration may operate in astrophysical environments, particularly in highly relativistic and supersonic settings where macroscopic shear processes are stable.
The ‘twin paradox’ in relativistic rigid motion
Ben-Ya'acov, Uri
2016-09-01
Relativistic rigid motion suggests a new version for the so-called ‘twin paradox’, comparing the ages of two astronauts on a very long spaceship. Although there is always an instantaneous inertial frame in which the whole spaceship, being rigid, is simultaneously at rest, the twins’ ages, measured as the proper-times along their individual world lines, are different when they are located at remote parts of the spaceship. The age, or proper-time, difference depends on the distance at rest between the astronauts and the rapidity difference between start to end. The relation of the age difference with the relative Doppler shift of light signals transmitted between the astronauts and implications for the possibility to assign a common age (proper-time) to complex, spatially extended, relativistic systems are also discussed.
Rębilas, Krzysztof
2014-01-01
Starting from the classical Newton's second law which, according to our assumption, is valid in any instantaneous inertial rest frame of body that moves in Minkowskian space-time we get the relativistic equation of motion $\\vec{F}=d\\vec{p}/dt$, where $\\vec{p}$ is the relativistic momentum. The relativistic momentum is then derived without referring to any additional assumptions concerning elastic collisions of bodies. Lorentz-invariance of the relativistic law is proved without tensor formalism. Some new method of force transformation is also presented.
Trembling motion of relativistic electrons in a magnetic field
Rusin, Tomasz M
2010-01-01
One-electron 3+1 and 2+1 Dirac equations are used to calculate the motion of a relativistic electron in a vacuum in the presence of an external magnetic field. First, calculations are carried on an operator level and exact analytical results are obtained for the electron trajectories which contain both intraband frequency components, identified as the cyclotron motion, as well as interband frequency components, identified as the trembling motion (Zitterbewegung, ZB). Next, time-dependent Heisenberg operators are used for the same problem to compute average values of electron position and velocity employing Gaussian wave packets. It is shown that the presence of a magnetic field and the resulting quantization of the energy spectrum has pronounced effects on the electron Zitterbewegung: it introduces intraband frequency components into the motion, influences all the frequencies and makes the motion stationary (not decaying in time) in case of the 2+1 Dirac equation. Finally, simulations of the 2+1 Dirac equatio...
Thermodynamic Laws and Equipartition Theorem in Relativistic Brownian Motion
Koide, T.; Kodama, T.
2011-01-01
We extend the stochastic energetics to a relativistic system. The thermodynamic laws and equipartition theorem are discussed for a relativistic Brownian particle and the first and the second law of thermodynamics in this formalism are derived. The relation between the relativistic equipartition relation and the rate of heat transfer is discussed in the relativistic case together with the nature of the noise term.
Thermodynamic laws and equipartition theorem in relativistic Brownian motion.
Koide, T; Kodama, T
2011-06-01
We extend the stochastic energetics to a relativistic system. The thermodynamic laws and equipartition theorem are discussed for a relativistic Brownian particle and the first and the second law of thermodynamics in this formalism are derived. The relation between the relativistic equipartition relation and the rate of heat transfer is discussed in the relativistic case together with the nature of the noise term.
Fine-grained uncertainty relation under the relativistic motion
Feng, Jun; Gould, Mark D; Fan, Heng
2014-01-01
One of the most important features of quantum theory is the uncertainty principle. Amount various uncertainty relations, the profound Fine-Grained Uncertainty Relation (FGUR) is used to distinguish the uncertainty inherent in obtaining any combination of outcomes for different measurements. In this paper, we explore this uncertainty relation in relativistic regime. For observer undergoes an uniform acceleration who immersed in an Unruh thermal bath, we show that the uncertainty bound is dependent on the acceleration parameter and choice of Unruh modes. Dramatically, we find that the measurements in Mutually Unbiased Bases (MUBs), sharing same uncertainty bound in inertial frame, could be distinguished from each other for a noninertial observer. On the other hand, once the Unruh decoherence is prevented by utilizing the cavity, the entanglement could be generated from nonuniform motion. We show that, for the observer restricted in a single rigid cavity, the uncertainty exhibits a periodic evolution with respec...
Motional Effect on Wall Shear Stresses
Kock, Samuel Alberg; Torben Fründ, Ernst; Yong Kim, Won
Atherosclerosis is the leading cause of death and severe disability. Wall Shear Stress (WSS), the stress exerted on vessel walls by the flowing blood is a key factor in the development of atherosclerosis. Computational Fluid Dynamics (CFD) is widely used for WSS estimations. Most CFD simulations...... are based on static models to ease computational burden leading to inaccurate estimations. The aim of this work was to estimate the effect of vessel wall deformations (expansion and bending) on WSS levels....
Oscillatory motion of sheared nanorods beyond the nematic phase.
Strehober, David A; Engel, Harald; Klapp, Sabine H L
2013-07-01
We study the role of the control parameter triggering nematic order (temperature or concentration) on the dynamical behavior of a system of nanorods under shear. Our study is based on a set of mesoscopic equations of motion for the components of the tensorial orientational order parameter. We investigate these equations via a systematic bifurcation analysis based on a numerical continuation technique, focusing on spatially homogeneous states. Exploring a wide range of parameters we find, unexpectedly, that states with oscillatory motion can exist even under conditions where the equilibrium system is isotropic. These oscillatory states are characterized by a wagging motion of the paranematic director, and they occur if the tumbling parameter is sufficiently small. We also present full nonequilibrium phase diagrams in the plane spanned by the concentration and the shear rate.
Oscillatory motion of sheared nanorods beyond the nematic phase
Strehober, David A.; Engel, Harald; Klapp, Sabine H. L.
2013-07-01
We study the role of the control parameter triggering nematic order (temperature or concentration) on the dynamical behavior of a system of nanorods under shear. Our study is based on a set of mesoscopic equations of motion for the components of the tensorial orientational order parameter. We investigate these equations via a systematic bifurcation analysis based on a numerical continuation technique, focusing on spatially homogeneous states. Exploring a wide range of parameters we find, unexpectedly, that states with oscillatory motion can exist even under conditions where the equilibrium system is isotropic. These oscillatory states are characterized by a wagging motion of the paranematic director, and they occur if the tumbling parameter is sufficiently small. We also present full nonequilibrium phase diagrams in the plane spanned by the concentration and the shear rate.
Dodin, I Y; Fraiman, G M
2003-01-01
The Lagrangian and Hamiltonian functions describing average motion of a relativistic particle under the action of intensive high-frequency electromagnetic radiation are obtained. In weak, low-frequency background fields, such a particle on average drifts with an effective, relativistically invariant mass, which depends on the intensity of the electromagnetic field.
Ion waves driven by shear flow in a relativistic degenerate astrophysical plasma
KHAN SHABBIR A; BAKHTIAR-UD-DIN; ILYAS MUHAMMAD; WAZIR ZAFAR
2016-05-01
We investigate the existence and propagation of low-frequency (in comparison to ion cyclotron frequency) electrostatic ion waves in highly dense inhomogeneous astrophysical magnetoplasma comprising relativistic degenerate electrons and non-degenerate ions. The dispersion equation is obtained by Fourier analysis under mean-field quantum hydrodynamics approximationfor various limits of the ratio of rest mass energy to Fermi energy of electrons, relevant to ultrarelativistic, weakly-relativistic and non-relativistic regimes. It is found that the system admits an oscillatory instability under certain condition in the presence of velocity shear parallel to ambient magnetic field. The dispersive role of plasma density and magnetic field is also discussed parametrically in the scenario of dense and degenerate astrophysical plasmas.
Radiation from the Relativistic Jet a Role of the Shear Boundary Layer
Stawarz, L
2002-01-01
Recent radio and optical large scale jets' observations suggest a two-component jet morphology, consisting of a fast central spine surrounded with a boundary layer with a velocity shear. We study radiation of electrons accelerated at such boundary layers as an option for standard approaches involving internal shocks in jets. The acceleration process in the boundary layer yields in a natural way a two component electron distribution: a power-law continuum with a bump at the energy, where energy gains equal radiation losses, followed by a cut-off. For such distributions we derive the observed spectra of synchrotron and inverse-Compton radiation, including comptonization of synchrotron and CMB photons. Under simple assumptions of energy equipartition between the relativistic particles and the magnetic field, the relativistic jet velocity at large scales and a turbulent character of the shear layer, the considered radiation can substantially contribute to the jet radiative output. In the considered conditions the...
Moroz, O
2014-01-01
Using Mathematica package, we derive analytical closed-form expressions for the shear and the bulk viscosity coefficients in multicomponent relativistic gases with constant cross sections, being the relativistic generalization for the hard spheres model. Some of them are cumbersome and require symbolic manipulations in an algebraic package. The constant cross sections are of the elastic processes, while the inelastic (or number-changing) processes (collisions or decays) are considered only partly. As examples, we find explicit expressions of the correct single-component first-order shear viscosity coefficient and some explicit analytical results for the binary mixture. These formulas have numerous applications in approximate nonequilibrium descriptions of gases of particles or quasiparticles with averaged (temperature dependent) cross sections. In addition to this, we present formulas for collision rates and some other related formulas. This paper is a shortened version of a previous one.
Equations of motion for a relativistic wave packet
L Kocis
2012-05-01
The time derivative of the position of a relativistic wave packet is evaluated. It is found that it is equal to the mean value of the momentum of the wave packet divided by the mass of the particle. The equation derived represents a relativistic version of the second Ehrenfest theorem.
Mechanisms of intruder motion in cyclically sheared granular media
Zheng, Hu; Barés, Jonathan; Wang, Dong; Behringer, Robert
2016-11-01
We perform an experimental study showing how an intruder, a Teflon disk that experiences a moderate constant force, F, can advance through a granular material that is subject to quasi-static cyclic shear. The large Teflon disk is embedded in a layer of smaller bidisperse photoelastic disks. The granular medium and disk are contained in a horizontal cell, which is deformed from a square to a parallelogram and back again. The area of the cell remains constant throughout, and the protocol corresponds to cyclical simple shear. We find that the net intruder motion per cycle increases as a power law in Nc. The intruder motion relative to the granular background occurs primarily following strain reversals. We acknowledge support from NSF Grant No. DMR1206351, NASA Grant No. NNX15AD38G and the W.M. Keck Foundation.
Magnetic Field Generation, Particle Energization and Radiation at Relativistic Shear Boundary Layers
Liang, Edison; Fu, Wen; Spisak, Jake; Boettcher, Markus
2015-11-01
Recent large scale Particle-in-Cell (PIC) simulations have demonstrated that in unmagnetized relativistic shear flows, strong transverse d.c. magnetic fields are generated and sustained by ion-dominated currents on the opposite sides of the shear interface. Instead of dissipating the shear flow free energy via turbulence formation and mixing as it is usually found in MHD simulations, the kinetic results show that the relativistic boundary layer stabilizes itself via the formation of a robust vacuum gap supported by a strong magnetic field, which effectively separates the opposing shear flows, as in a maglev train. Our new PIC simulations have extended the runs to many tens of light crossing times of the simulation box. Both the vacuum gap and supporting magnetic field remain intact. The electrons are energized to reach energy equipartition with the ions, with 10% of the total energy in electromagnetic fields. The dominant radiation mechanism is similar to that of a wiggler, due to oscillating electron orbits around the boundary layer.
Radiation from Particles Accelerated in Relativistic Jet Shocks and Shear-flows
Nishikawa, K -I; Dutan, I; Zhang, B; Meli, A; Choi, E J; Min, K; Niemiec, J; Mizuno, Y; Medvedev, M; Nordlund, A; Frederiksen, J T; Sol, H; Pohl, M; Hartmann, D
2014-01-01
We have investigated particle acceleration and emission from shocks and shear flows associated with an unmagnetized relativistic jet plasma propagating into an unmagnetized ambient plasma. Strong electro-magnetic fields are generated in the jet shock via the filamentation (Weibel) instability. Shock field strength and structure depend on plasma composition (($e^{\\pm}$ or $e^-$- $p^+$ plasmas) and Lorentz factor. In the velocity shear between jet and ambient plasmas, strong AC ($e^{\\pm}$ plasmas) or DC ($e^-$- $p^+$ plasmas) magnetic fields are generated via the kinetic Kelvin-Helmholtz instability (kKHI), and the magnetic field structure also depends on the jet Lorentz factor. We have calculated, self-consistently, the radiation from electrons accelerated in shock generated magnetic fields. The spectra depend on the jet's initial Lorentz factor and temperature via the resulting particle acceleration and magnetic field generation. Our ongoing "Global" jet simulations containing shocks and velocity shears will ...
Shukla, Chandrasekhar; Patel, Kartik
2016-01-01
We carry out Particle-in-Cell (PIC) simulations to study the instabilities associated with a 2-D sheared electron flow configuration against a neutralizing background of ions. Both weak and strong relativistic flow velocities are considered. In the weakly relativistic case, we observe the development of electromagnetic Kelvin Helmholtz instability with similar characteristics as that predicted by the electron Magnetohydrodynamic (EMHD) model. On other hand, in strong relativistic case the compressibility effects of electron fluid dominate and introduce upper hybrid electrostatic oscillations transverse to the flow which are very distinct from EMHD fluid behaviour. In the nonlinear regime, both weak and strong relativistic cases lead to turbulence with broad power law spectrum.
Tanahashi, Shigehito; Ashihara, Kaoru; Ujike, Hiroyasu
2015-01-01
Recent studies have found that self-motion perception induced by simultaneous presentation of visual and auditory motion is facilitated when the directions of visual and auditory motion stimuli are identical. They did not, however, examine possible contributions of auditory motion information for determining direction of self-motion perception. To examine this, a visual stimulus projected on a hemisphere screen and an auditory stimulus presented through headphones were presented separately or simultaneously, depending on experimental conditions. The participant continuously indicated the direction and strength of self-motion during the 130-s experimental trial. When the visual stimulus with a horizontal shearing rotation and the auditory stimulus with a horizontal one-directional rotation were presented simultaneously, the duration and strength of self-motion perceived in the opposite direction of the auditory rotation stimulus were significantly longer and stronger than those perceived in the same direction of the auditory rotation stimulus. However, the auditory stimulus alone could not sufficiently induce self-motion perception, and if it did, its direction was not consistent within each experimental trial. We concluded that auditory motion information can determine perceived direction of self-motion during simultaneous presentation of visual and auditory motion information, at least when visual stimuli moved in opposing directions (around the yaw-axis). We speculate that the contribution of auditory information depends on the plausibility and information balance of visual and auditory information.
Measuring shear viscosity using transverse momentum correlations in relativistic nuclear collisions.
Gavin, Sean; Abdel-Aziz, Mohamed
2006-10-20
Elliptic flow measurements at the Brookhaven National Laboratory Relativistic Heavy Ion Collider suggest that quark-gluon fluid flows with very little viscosity compared to weak-coupling expectations, challenging theorists to explain why this fluid is so nearly "perfect." It is therefore vital to find quantitative experimental information on the viscosity of the fluid. We propose that measurements of transverse momentum fluctuations can be used to determine the shear viscosity. We use current data to estimate the viscosity-to-entropy ratio in the range from 0.08 to 0.3 and discuss how future measurements can reduce this uncertainty.
On the nonuniqueness of free motion of the fundamental relativistic rotator
Bratek, Łukasz
2009-01-01
Consider a class of relativistic rotators described by position and a single null direction. Such a rotator is called fundamental if both its Casimir invariants are intrinsic dimensional parameters independent of arbitrary constants of motion. As shown by Staruszkiewicz, only one rotator with this property exists (its partner with similar property can be excluded on physical grounds). We obtain a general solution to equations of free motion of the fundamental relativistic rotator in a covariant manner. Surprisingly, this motion is not entirely determined by initial conditions but depends on one arbitrary function of time, which specifies rotation of the null direction in the centre of momentum frame. This arbitrariness is in manifest contradiction with classical determinism. In this sense the isolated fundamental relativistic rotator is pathological as a dynamical system. To understand why this is so, we study the necessary condition for the uniqueness of the related Cauchy problem. It turns out that the fund...
Liang, Edison; Fu, Wen; Böttcher, Markus
2017-10-01
We present particle-in-cell simulation results of relativistic shear boundary layers between electron–ion and electron–positron plasmas and discuss their potential applications to astrophysics. Specifically, we find that in the case of a fast electron–positron spine surrounded by a slow-moving or stationary electron–ion sheath, lepton acceleration proceeds in a highly anisotropic manner due to electromagnetic fields created at the shear interface. While the highest-energy leptons still produce a beaming pattern (as seen in the quasi-stationary frame of the sheath) of order 1/Γ, where Γ is the bulk Lorentz factor of the spine, for lower-energy particles, the beaming is much less pronounced. This is in stark contrast to the case of pure electron–ion shear layers, in which anisotropic particle acceleration leads to significantly narrower beaming patterns than 1/Γ for the highest-energy particles. In either case, shear-layer acceleration is expected to produce strongly angle-dependent lepton (hence, emanating radiation) spectra, with a significantly harder spectrum in the forward direction than viewed from larger off-axis angles, much beyond the regular Doppler boosting effect from a co-moving isotropic lepton distribution. This may solve the problem of the need for high (and apparently arbitrarily chosen) minimum Lorentz factors of radiating electrons, often plaguing current blazar and GRB jet modeling efforts.
Classical shear cracks drive the onset of dry frictional motion.
Svetlizky, Ilya; Fineberg, Jay
2014-05-08
Frictional processes entail the rupture of the ensemble of discrete contacts defining a frictional interface. There are a variety of views on how best to describe the onset of dry frictional motion. These range from modelling friction with a single degree of freedom, a 'friction coefficient', to theoretical treatments using dynamic fracture to account for spatial and temporal dynamics along the interface. We investigated the onset of dry frictional motion by performing simultaneous high-speed measurements of the real contact area and the strain fields in the region surrounding propagating rupture tips within the dry (nominally flat) rough interfaces formed by brittle polymer blocks. Here we show that the transition from 'static' to 'dynamic' friction is quantitatively described by classical singular solutions for the motion of a rapid shear crack. We find that these singular solutions, originally derived to describe brittle fracture, are in excellent agreement with the experiments for slow propagation, whereas some significant discrepancies arise as the rupture velocity approaches the Rayleigh wave speed. In addition, the energy dissipated in the fracture of the contacts remains nearly constant throughout the entire range in which the rupture velocity is less than the Rayleigh wave speed, whereas the size of the dissipative zone undergoes a Lorentz-like contraction as the rupture velocity approaches the Rayleigh wave speed. This coupling between friction and fracture is critical to our fundamental understanding of frictional motion and related processes, such as earthquake dynamics.
Irreversible degradation of quantum coherence under relativistic motion
Wang, Jieci; Jing, Jiliang; Fan, Heng
2016-01-01
We study the dynamics of quantum coherence under Unruh thermal noise and seek under which condition the coherence can be frozen in a relativistic setting. We find that the quantum coherence can not be frozen for any acceleration due to the effect of Unruh thermal noise. We also find that quantum coherence is more robust than entanglement under the effect of Unruh thermal noise and therefore the coherence type quantum resources are more accessible for relativistic quantum information processing tasks. Besides, the dynamic of quantum coherence is found to be more sensitive than entanglement to the preparation of the detectors' initial state and the atom-field coupling strength, while it is less sensitive than entanglement to the acceleration of the detector.
Azimuthal Correlation of Collective Motion in Relativistic Heavy Ion Collisions
HUO Lei; ZHANG Wei-Ning; CHEN Xiang-Jun; TANG Gui-Xin; ZHANG Jing-Bo
2001-01-01
The out-of-plane squeeze-out effect in relativistic heavy ion collisions is used to estimate the reaction plane by performing a modified transverse momentum analysis. A technique for investigating the azimuthal correlation between the out-of-plane squeeze-out and directed in-plane flow is described. A clear signature of the azimuthal correlation is evidenced in the 600 A MeV Au + Au reaction from the quantum molecular dynamic model calculations.
Gallo, Emanuel
2016-01-01
We present a general approach for the formulation of equations of motion for compact objects in general relativistic theories. The particle is assumed to be moving in a geometric background which in turn is asymptotically flat. By construction, the model incorporates the back reaction due to gravitational radiation generated by the motion of the particle. Our approach differs from other constructions tackling the same kind of problem.
Radiation from relativistic particles in nongeodesic motion in a strong gravitational field
Aliev, A.N. (AN Gruzinskoj SSR, Abastumani. Abastumanskaya Astrofizicheskaya Observatoriya); Galtsov, D.V. (Moskovskij Gosudarstvennyj Univ. (USSR). Kafedra Teoreticheskoj Fiziki)
1981-10-01
The scalar and electromagnetic radiation emitted by relativistic particles moving along the stable nongeodesic trajectories in the Kerr gravitational field are described. Two particular models of the nongeodesic motion are developed involving a slightly charged rotating black hole and a rotating black hole immersed in an external magnetic field.
How relativistic motion affects Einstein-Podolsky-Rosen steering
Sun, Wen-Yang; Wang, Dong; Ye, Liu
2017-09-01
In this letter, the dynamic behavior of Einstein-Podolsky-Rosen (EPR) steering and the redistribution of EPR steering under a relativistic framework are investigated. Specifically, we explore the scenario that particle A held by Alice is in a flat space-time and another particle B held by Bob entangled with A is in a non-inertial framework. The results show that EPR steering from Alice to Bob is dramatically destroyed by the Unruh effect caused by the acceleration of Bob. Besides, EPR steering possess asymmetry, and EPR steering asymmetry increases with growing intensity of the Unruh effect, implying that the Unruh effect can bring about EPR steering asymmetry. Furthermore, the reduced physically accessible EPR steering from Alice to Bob is distributed to the physically inaccessible EPR steering (from Alice to anti-Bob or from Bob to anti-Bob). Notably, unlike entanglement and quantum discord, only one of the EPR steering from Alice to anti-Bob and Bob to anti-Bob experiences a sudden birth with increase in the acceleration parameter, which means that they cannot simultaneously survive. That is, the monogamous relationship of EPR steering is still tenable in such a scenario. Consequently, we believe that EPR steering could also serve as an important information resource within long-distance quantum secure communication under the relativistic framework.
Effect of a sheared flow on iceberg motion and melting
FitzMaurice, A.; Straneo, F.; Cenedese, C.; Andres, M.
2016-12-01
Icebergs account for approximately half the freshwater flux into the ocean from the Greenland and Antarctic ice sheets and play a major role in the distribution of meltwater into the ocean. Global climate models distribute this freshwater by parameterizing iceberg motion and melt, but these parameterizations are presently informed by limited observations. Here we present a record of speed and draft for 90 icebergs from Sermilik Fjord, southeastern Greenland, collected in conjunction with wind and ocean velocity data over an 8 month period. It is shown that icebergs subject to strongly sheared flows predominantly move with the vertical average of the ocean currents. If, as typical in iceberg parameterizations, only the surface ocean velocity is taken into account, iceberg speed and basal melt may have errors in excess of 60%. These results emphasize the need for parameterizations to consider ocean properties over the entire iceberg draft.
Higher dimensional charged shear-free relativistic models with heat flux
Nyonyi, Y; Govinder, K S
2014-01-01
We analyse shear-free spherically symmetric relativistic models of gravitating fluids with heat flow and electric charge defined on higher dimensional manifolds. The solution to the Einstein-Maxwell system is governed by the pressure isotropy condition which depends on the spacetime dimension. We study this highly nonlinear partial differential equation using Lie's group theoretic approach. The Lie symmetry generators that leave the equation invariant are determined. We provide exact solutions to the gravitational potentials using the first symmetry admitted by the equation. Our new exact solutions contain the earlier results for the four-dimensional case. Using the other Lie generators, we are able to provide solutions to the gravitational potentials or reduce the order of the master equation to a first order nonlinear differential equation. We derive the temperature transport equation in higher dimensions and find expressions for the causal and Eckart temperatures showing their explicit dependance on the di...
Influence of nucleonic motion in Relativistic Fermi Gas inclusive responses
Alvarez-Ruso, L; Donnelly, T W; Molinari, A
2001-01-01
Impulsive hadronic descriptions of electroweak processes in nuclei involve two distinctly different elements: one stems from the nuclear many-body physics --- the medium --- which is rather similar for the various inclusive response functions, and the other embodies the responses of the hadrons themselves to the electroweak probe and varies with the channel selected. In this letter we investigate within the context of the relativistic Fermi gas in both the quasi-elastic and $N\\to\\Delta$ regimes the interplay between these two elements. Specifically, we focus on expansions in the one small parameter in the problem, namely, the momentum of a nucleon in the initial wave function compared with the hadronic scale, the nucleon mass. Both parity-conserving and -violating inclusive responses are studied and the interplay between longitudinal ($L$) and transverse ($T$ and $T'$) contributions is highlighted.
Thermal conductivity, shear and bulk viscosities for a relativistic binary mixture
Moratto, Valdemar; Kremer, Gilberto M.
2016-11-01
In the present work, we deal with a binary mixture of diluted relativistic gases within the framework of the kinetic theory. The analysis is made within the framework of the Boltzmann equation. We assume that the gas is under the influence of an isotropic Schwarzschild metric and is composed of particles with speeds comparable with the light speed. Taking into account the constitutive equations for the laws of Fourier and Navier-Stokes, we obtain expressions for the thermal conductivity, the shear, and bulk viscosities. To evaluate the integrals we assume a hard-sphere interaction along with non-disparate masses for the particles of each component. We show the analytical expressions and the behavior of the transport coefficients with respect to a relativistic parameter which gives the ratio of the rest energy of the particles to the thermal energy of the gas. We also determine the dependence of the transport coefficients with respect to the gravitational potential and demonstrate that the corresponding one component limit is recovered by considering particles with equal masses, in accordance with the kinetic theory of a single fluid.
Doppler cloak restores invisibility to objects in relativistic motion
Ramaccia, Davide; Sounas, Dimitrios L.; Alù, Andrea; Toscano, Alessandro; Bilotti, Filiberto
2017-02-01
Although cloaks are effective at suppressing the observability of static objects, they can be defeated when in motion. Here we discuss a general technique to cloak the motion of objects from static observers, based on compensating the Doppler shift associated with their motion with frequency conversion sustained by a spatiotemporally modulated cover. The concept is theoretically and numerically demonstrated in a system composed of a planar reflector covered by a spatiotemporally modulated slab. It is shown that, for properly selected modulation frequency, the composite system can appear to an external observer as stationary, even though it is actually moving. This concept may pave the way to the minimization of clutter produced by moving objects as well as to new directions in the science of cloaking.
Shukla, Chandrasekhar; Das, Amita; Patel, Kartik
2016-08-01
We carry out particle-in-cell simulations to study the instabilities associated with a 2-D sheared electron flow configuration against a neutralizing background of ions. Both weak and strong relativistic flow velocities are considered. In the weakly relativistic case, we observe the development of electromagnetic Kelvin-Helmholtz instability with similar characteristics as that predicted by the electron Magnetohydrodynamic (EMHD) model. On the contrary, in a strong relativistic case, the compressibility effects of electron fluid dominate and introduce upper hybrid electrostatic oscillations transverse to the flow which are very distinct from EMHD fluid behavior. In the nonlinear regime, both weak and strong relativistic cases lead to turbulence with broad power law spectrum.
Kayaking and wagging of liquid crystals under shear:comparing director and mesogen motions
Tao, Y.G.; den Otter, Wouter K.; Briels, Willem J.
2009-01-01
Rod-like colloids in dense solutions perform collective orientational motions under shear flow. The periodic tumbling motions of the director, i.e. the average orientation of the rods, are commonly characterized as kayaking, wagging and flow-aligning, in order of increasing shear rate. Our
Pengfei Song; Heng Zhao; Urban, Matthew W; Manduca, Armando; Pislaru, Sorin V; Kinnick, Randall R; Pislaru, Cristina; Greenleaf, James F; Shigao Chen
2013-12-01
Ultrasound tissue harmonic imaging is widely used to improve ultrasound B-mode imaging quality thanks to its effectiveness in suppressing imaging artifacts associated with ultrasound reverberation, phase aberration, and clutter noise. In ultrasound shear wave elastography (SWE), because the shear wave motion signal is extracted from the ultrasound signal, these noise sources can significantly deteriorate the shear wave motion tracking process and consequently result in noisy and biased shear wave motion detection. This situation is exacerbated in in vivo SWE applications such as heart, liver, and kidney. This paper, therefore, investigated the possibility of implementing harmonic imaging, specifically pulse-inversion harmonic imaging, in shear wave tracking, with the hypothesis that harmonic imaging can improve shear wave motion detection based on the same principles that apply to general harmonic B-mode imaging. We first designed an experiment with a gelatin phantom covered by an excised piece of pork belly and show that harmonic imaging can significantly improve shear wave motion detection by producing less underestimated shear wave motion and more consistent shear wave speed measurements than fundamental imaging. Then, a transthoracic heart experiment on a freshly sacrificed pig showed that harmonic imaging could robustly track the shear wave motion and give consistent shear wave speed measurements of the left ventricular myocardium while fundamental imaging could not. Finally, an in vivo transthoracic study of seven healthy volunteers showed that the proposed harmonic imaging tracking sequence could provide consistent estimates of the left ventricular myocardium stiffness in end-diastole with a general success rate of 80% and a success rate of 93.3% when excluding the subject with Body Mass Index higher than 25. These promising results indicate that pulse-inversion harmonic imaging can significantly improve shear wave motion tracking and thus potentially
Relativistic Brownian motion: from a microscopic binary collision model to the Langevin equation.
Dunkel, Jörn; Hänggi, Peter
2006-11-01
The Langevin equation (LE) for the one-dimensional relativistic Brownian motion is derived from a microscopic collision model. The model assumes that a heavy pointlike Brownian particle interacts with the lighter heat bath particles via elastic hard-core collisions. First, the commonly known, nonrelativistic LE is deduced from this model, by taking into account the nonrelativistic conservation laws for momentum and kinetic energy. Subsequently, this procedure is generalized to the relativistic case. There, it is found that the relativistic stochastic force is still delta correlated (white noise) but no longer corresponds to a Gaussian white noise process. Explicit results for the friction and momentum-space diffusion coefficients are presented and discussed.
Hamlin, Nathaniel D; Newman, William I
2013-04-01
. Sufficiently strong fields (M(A)<6) completely suppress vortex formation. Maximum jet deceleration, and viscous dissipation, occur for intermediate vortex-disruptive fields, while electromagnetic energy is maximized for the strongest fields which allow vortex formation. Highly relativistic flows destabilize the system, supporting modes with near-maximum growth at smaller wavelengths than the shear width of the velocity. This helps to explain early numerical breakdown of highly relativistic simulations using numerical viscosity, a long-standing problem. While magnetic fields generally stabilize the system, we have identified many features of the complex and turbulent reorganization that occur for sufficiently weak fields in RMHD flows, and have described the transition from disruptive to stabilizing fields at M(A)≈6. Our results are qualitatively similar to observations of numerous jets, including M87, whose knots may exhibit vortex-like behavior. Furthermore, in both the linear and nonlinear analyses, we have successfully unified the HD, MHD, RHD, and RMHD regimes.
Kayaking and wagging of liquid crystals under shear:comparing director and mesogen motions
Tao, Y.G.; den Otter, Wouter K.; Briels, Willem J.
2009-01-01
Rod-like colloids in dense solutions perform collective orientational motions under shear flow. The periodic tumbling motions of the director, i.e. the average orientation of the rods, are commonly characterized as kayaking, wagging and flow-aligning, in order of increasing shear rate. Our event-driven Brownian dynamics simulations of rigid spherocylinders reproduce these three distinct director motions, but also clearly show, for the first time, that the individual mesogens are kayaking at a...
Motion-dependent levels of order in a relativistic universe.
Frieden, B Roy; Petri, Michael
2012-09-01
Consider a generally closed system of continuous three-space coordinates x with a differentiable amplitude function ψ(x). What is its level of order R? Define R by the property that it decreases (or stays constant) after the system is coarse grained. Then R turns out to obey R=8(-1)L(2)I,where quantity I=4∫dx[nabla]ψ(*)·[nabla]ψ is the classical Fisher information in the system and L is the longest chord that can connect two points on the system surface. In general, order R is (i) unitless, and (ii) invariant to uniform stretch or compression of the system. On this basis, the order R in the Universe was previously found to be invariant in time despite its Hubble expansion, and with value R=26.0×10(60) for flat space. By comparison, here we model the Universe as a string-based "holostar," with amplitude function ψ(x)[proportionality]1/r over radial interval r=(r(0),r(H)). Here r(0) is of order the Planck length and r(H) is the radial extension of the holostar, estimated as the known value of the Hubble radius. Curvature of space and relative motion of the observer must now be taken into account. It results that a stationary observer observes a level of order R=(8/9)(r(H)/r(0))(3/2)=0.42×10(90); while for a free-falling observer R=2(-1)(r(H)/r(0))(2)=0.85×10(120). Both order values greatly exceed the above flat-space value. Interestingly, they are purely geometric measures, depending solely upon ratio r(H)/r(0). Remarkably, the free-fall value ~10(120) of R approximates the negentropy of a universe modeled as discrete. This might mean that the Universe contains about equal amounts of continuous and discrete structure.
Liu, Ruoyu
2015-06-10
Ultrahigh energy cosmic rays are extreme energetic particles from outer space. They have aroused great interest among scientists for more than fifty years. However, due to the rarity of the events and complexity of the process of their propagation to Earth, they are still one of the biggest puzzles in modern high energy astrophysics. This dissertation is dedicated to study the origin of ultrahigh energy cosmic rays from various aspects. Firstly, we discuss a possible link between recently discovered sub-PeV/PeV neutrinos and ultrahigh energy cosmic rays. If these two kinds of particles share the same origin, the observation of neutrinos may provide additional and non-trivial constraints on the sources of ultrahigh energy cosmic rays. Secondly, we jointly employ the chemical composition measurement and the arrival directions of ultrahigh energy cosmic rays, and find a robust upper limit for distances of sources of ultrahigh energy cosmic rays above ∝55 EeV, as well as a lower limit for their metallicities. Finally, we study the shear acceleration mechanism in relativistic jets, which is a more efficient mechanism for the acceleration of higher energy particle. We compute the acceleration efficiency and the time-dependent particle energy spectrum, and explore the feature of synchrotron radiation of the accelerated particles. The possible realizations of this mechanism for acceleration of ultrahigh energy cosmic rays in different astrophysical environments is also discussed.
Huang, Chun Yu; Ma, Wenchao; Wang, Dong; Ye, Liu
2017-02-01
In this work, the quantum fisher information (QFI) and Bell non-locality of a multipartite fermionic system are investigated. Unlike the currently existing research of QFI, we focus our attention on the differences between quantum fisher information and Bell non-locality under the relativistic framework. The results show that although the relativistic motion affects the strength of the non-locality, it does not change the physical structure of non-locality. However, unlike the case of non-locality, the relativistic motion not only influence the precision of the QFI Fϕ but also broke the symmetry of the function Fϕ. The results also show that for a special multipartite system, , the number of particles of a initial state do not affect the Fθ. Furthermore, we also find that Fθ is completely unaffected in non-inertial frame if there are inertial observers. Finally, in view of the decay behavior of QFI and non-locality under the non-inertial frame, we proposed a effective scheme to battle against Unruh effect.
Relativistic equation-of-motion coupled-cluster method using open-shell reference wavefunction
Pathak, Himadri; Nayak, Malaya K; Vaval, Nayana; Pal, Sourav
2016-01-01
The open-shell reference relativistic equation-of-motion coupled-cluster method within its four-component description is successfully implemented with the consideration of single- and double- excitation approximation. The one-body and two-body matrix elements required for the correlation calculation are generated using Dirac-Coulomb Hamiltonian. As a first attempt, the implemented method is employed to calculate a few of the low-lying ionized states of heavy atomic (Ag, Cs, Au, Fr, Lr) and valence ionization potential of molecular (HgH, PbF) systems, where the effect of relativity does really matter to obtain highly accurate results. Not only the relativistic effect, but also the effect of electron correlation is crucial in these heavy atomic and molecular systems. To justify the fact, we have taken two further approximations in the four-component relativistic equation-of-motion framework to quantify how the effect of electron correlation plays a role in the calculated values at different level of the approxi...
Amador Carrascal, Carolina; Chen, Shigao; Manduca, Armando; Greenleaf, James F; Urban, Matthew
2017-01-11
Quantitative ultrasound elastography is increasingly being used in the assessment of chronic liver disease. Many studies have reported ranges of liver shear wave velocities values for healthy individuals and patients with different stages of liver fibrosis. Nonetheless, ongoing efforts exist to stabilize quantitative ultrasound elastography measurements by assessing factors that influence tissue shear wave velocity values, such as food intake, body mass index (BMI), ultrasound scanners, scanning protocols, ultrasound image quality, etc. Time-to-peak (TTP) methods have been routinely used to measure the shear wave velocity. However, there is still a need for methods that can provide robust shear wave velocity estimation in the presence of noisy motion data. The conventional TTP algorithm is limited to searching for the maximum motion in time profiles at different spatial locations. In this study, two modified shear wave speed estimation algorithms are proposed. The first method searches for the maximum motion in both space and time (spatiotemporal peak, STP); the second method applies an amplitude filter (spatiotemporal thresholding, STTH) to select points with motion amplitude higher than a threshold for shear wave group velocity estimation. The two proposed methods (STP and STTH) showed higher precision in shear wave velocity estimates compared to TTP in phantom. Moreover, in a cohort of 14 healthy subjects STP and STTH methods improved both the shear wave velocity measurement precision and the.
Improved shear wave motion detection using coded excitation for transient elastography
He, Xiao-Nian; Diao, Xian-Fen; Lin, Hao-Ming; Zhang, Xin-Yu; Shen, Yuan-Yuan; Chen, Si-Ping; Qin, Zheng-Di; Chen, Xin
2017-01-01
Transient elastography (TE) is well adapted for use in studying liver elasticity. However, because the shear wave motion signal is extracted from the ultrasound signal, the weak ultrasound signal can significantly deteriorate the shear wave motion tracking process and make it challenging to detect the shear wave motion in a severe noise environment, such as within deep tissues and within obese patients. This paper, therefore, investigated the feasibility of implementing coded excitation in TE for shear wave detection, with the hypothesis that coded ultrasound signals can provide robustness to weak ultrasound signals compared with traditional short pulse. The Barker 7, Barker 13, and short pulse were used for detecting the shear wave in the TE application. Two phantom experiments and one in vitro liver experiment were done to explore the performances of the coded excitation in TE measurement. The results show that both coded pulses outperform the short pulse by providing superior shear wave signal-to-noise ratios (SNR), robust shear wave speed measurement, and higher penetration intensity. In conclusion, this study proved the feasibility of applying coded excitation in shear wave detection for TE application. The proposed method has the potential to facilitate robust shear elasticity measurements of tissue. PMID:28295027
Improved shear wave motion detection using coded excitation for transient elastography.
He, Xiao-Nian; Diao, Xian-Fen; Lin, Hao-Ming; Zhang, Xin-Yu; Shen, Yuan-Yuan; Chen, Si-Ping; Qin, Zheng-Di; Chen, Xin
2017-03-15
Transient elastography (TE) is well adapted for use in studying liver elasticity. However, because the shear wave motion signal is extracted from the ultrasound signal, the weak ultrasound signal can significantly deteriorate the shear wave motion tracking process and make it challenging to detect the shear wave motion in a severe noise environment, such as within deep tissues and within obese patients. This paper, therefore, investigated the feasibility of implementing coded excitation in TE for shear wave detection, with the hypothesis that coded ultrasound signals can provide robustness to weak ultrasound signals compared with traditional short pulse. The Barker 7, Barker 13, and short pulse were used for detecting the shear wave in the TE application. Two phantom experiments and one in vitro liver experiment were done to explore the performances of the coded excitation in TE measurement. The results show that both coded pulses outperform the short pulse by providing superior shear wave signal-to-noise ratios (SNR), robust shear wave speed measurement, and higher penetration intensity. In conclusion, this study proved the feasibility of applying coded excitation in shear wave detection for TE application. The proposed method has the potential to facilitate robust shear elasticity measurements of tissue.
Computational biomechanics of a lumbar motion segment in pure and combined shear loads.
Schmidt, Hendrik; Bashkuev, Maxim; Dreischarf, Marcel; Rohlmann, Antonius; Duda, Georg; Wilke, Hans-Joachim; Shirazi-Adl, Aboulfazl
2013-09-27
Anterior shear has been implicated as a risk factor in spinal injuries. A 3D nonlinear poroelastic finite element model study of a lumbar motion segment L4-L5 was performed to predict the temporal shear response under various single and combined shear loads. Effects of nucleotomy and facetectomy as well as changes in the posture and facet gap distance were analyzed as well. Comparison of the predicted anterior displacement and stiffness response with available measurements indicates satisfactory agreement. Under shear loads up to 400 N, the model predicted an almost linear displacement response. With increasing shear load and/or compressive preload, the stiffening behavior becomes evident, primarily due to stretched collagen fibers and greater facet interactions. Removal of the facets markedly decreases the segmental stiffness in shear and thus highlights the importance of the facets in resisting shear force; 61-87% of the applied shear force is transmitted through the facets depending on the magnitude of the applied shear and compressive preload. Fluid exudation during the day as well as reduced facet gap distance and a more extended posture yielded higher facet joint forces. The shear resistance of the motion segment remains almost the same with time despite the transfer of load sharing from the disc to facets. Large forces on facet joints are computed especially under greater compression preloads, shear forces and extension rotations, as time progresses and with smaller gap distances. The disc contribution on the other hand increases under larger shear loads, smaller compression preloads, flexed postures, larger facet gap distances and at transient periods. Copyright © 2013 Elsevier Ltd. All rights reserved.
On relativistic motion of a pair of particles having opposite signs of masses
Ivanov, Pavel B.
2012-12-01
In this methodological note, we consider, in a weak-fleld limit, the relativistic linear motion of two particles with masses of opposite signs and a small difference between their absolute values: m_{1,2}=+/- (\\mu+/- \\Delta \\mu) , \\mu \\gt 0, \\vert\\Delta \\mu \\vert \\ll\\mu. In 1957, H Bondi showed in the framework of both Newtonian analysis and General Relativity that, when the relative motion of particles is absent, such a pair can be accelerated indefinitely. We generalize the results of his paper to account for the small nonzero difference between the velocities of the particles. Assuming that the weak-field limit holds and the dynamical system is conservative, an elementary treatment of the problem based on the laws of energy and momentum conservation shows that the system can be accelerated indefinitely, or attain very large asymptotic values of the Lorentz factor \\gamma. The system experiences indefinite acceleration when its energy-momentum vector is null and the mass difference \\Delta \\mu \\le 0. When the modulus of the square of the norm of the energy-momentum vector, \\vert N^{\\,2}\\vert, is sufficiently small, the system can be accelerated to very large \\gamma \\propto \\vert N^{\\,2}\\vert^{-1}. It is stressed that, when only leading terms in the ratio of a characteristic gravitational radius to the distance between the particles are retained, our elementary analysis leads to equations of motion equivalent to those derived from relativistic weak-field equations of motion by Havas and Goldberg in 1962. Thus, in the weak-field approximation it is possible to bring the system to the state with extremely high values of \\gamma. The positive energy carried by the particle with positive mass may be conveyed to other physical bodies, say by intercepting this particle with a target. If we suppose that there is a process of production of such pairs and the particles with positive mass are intercepted, while the negative mass particles are expelled
Relativistic equation-of-motion coupled-cluster method for the electron attachment problem
Pathak, Himadri; Nayak, Malaya K; Vaval, Nayana; Pal, Sourav
2016-01-01
The article considers the successful implementation of relativistic equation-of-motion coupled clus- ter method for the electron attachment problem (EA-EOMCC) at the level of single- and double- excitation approximation. The Dirac-Coulomb Hamiltonian is used to generate the single particle orbitals and two-body matrix elements. The implemented relativistic EA-EOMCC method is em- ployed to calculate ionization potential values of alkali metal atoms (Li, Na, K, Rb, Cs, Fr) and the vertical electron affinity values of LiX (X=H, F, Cl, Br), NaY (Y=H, F, Cl) starting from their closed-shell configuration. We have taken C 2 as an example to understand what should be the na- ture of the basis and cut off in the orbital energies that can be used for the correlation calculations without loosing a considerable amount of accuracy in the computed values. Both four-component and X2C calculations are done for all the opted systems to understand the effect of relativity in our calculations as well as to justify the fact tha...
Tat, Jimmy; Kociolek, Aaron M; Keir, Peter J
2013-10-01
Non-inflammatory fibrosis and thickening of the subsynovial connective tissue (SSCT) are characteristic in carpal tunnel syndrome (CTS) patients. These pathological changes have been linked to repetitive hand tasks that create shear forces between the flexor tendons and SSCT. We measured the relative motion of the flexor digitorum superficialis tendon and SSCT during two repetitive finger tasks using color Doppler ultrasound. Twelve participants performed flexion-extension cycles for 30 min with the long finger alone (differential movement) and with all four fingers together (concurrent movement). Shear strain index (SSI, a relative measure of excursion in flexion and extension) and maximum velocity ratio (MVR, the ratio of SSCT versus tendon during flexion and extension) were used to represent shear. A linear effect of exertion time was significant and corresponded with larger tendon shear in differential motion. The flexion SSI increased 20.4% from the first to the 30th minute, while MVR decreased 8.9% in flexion and 8.7% in extension. No significant changes were found during concurrent motion. These results suggest that exposure to repetitive differential finger tasks may increase the risk of shear injury in the carpal tunnel. Copyright © 2013 Orthopaedic Research Society.
Small-scale motions in turbulent boundary-free shear flows
Fiscaletti, D.
2016-01-01
The present work is an experimental and numerical investigation of the small-scale motions in turbulent free-shear flows. In the far-field turbulence of a jet at high Reynolds number (Reλ = 350) hot-wire anemometry (HWA) is applied to measure time series of flow velocity. By filtering these time ser
Periodic orientational motions of rigid liquid-crystalline polymers in shear flow
Tao, Y.G.; den Otter, Wouter K.; Briels, Willem J.
2006-01-01
The collective periodic motions of liquid-crystalline polymers in a nematic phase in shear flow have, for the first time, been simulated at the particle level by Brownian dynamics simulations. A wide range of parameter space has been scanned by varying the aspect ratio L/D between 10 and 60 at three
It's Alive! Spontaneous Motion of Shear Thickening Fluids Floating on the Air-Water Interface
Khandavalli, Sunilkumar; Rothstein, Jonathan P
2013-01-01
In this fluid dynamics video, we show the spontaneous random motion of thin filaments of a shear-thickening colloidal dispersions floating on the surface of water. The fluid is a dispersion of fumed silica nanoparticles in a low molecular weight polypropylene glycol (PPG) solvent. No external field or force is applied. The observed motion is driven by strong surface tension gradients as the polypropylene glycol slowly diffuses from from the filaments into water, resulting in the observed Marangoni flow. The motion is exaggerated by the thin filament constructs by the attractive interactions between silica nanoparticles and the PPG.
Nakamura, Masanori
2014-01-01
We describe a new paradigm for understanding both relativistic motions and particle acceleration in the M87 jet: a magnetically dominated relativistic flow that naturally produces four relativistic magnetohydrodynamic (MHD) shocks (forward/reverse fast and slow modes). We apply this model to a set of optical super- and subluminal motions discovered by Biretta and coworkers with the {\\em Hubble Space Telescope} during 1994 -- 1998. The model concept consists of ejection of a {\\em single} relativistic Poynting jet, which possesses a coherent helical (poloidal + toroidal) magnetic component, at the remarkably flaring point HST-1. We are able to reproduce quantitatively proper motions of components seen in the {\\em optical} observations of HST-1 with the same model we used previously to describe similar features in radio VLBI observations in 2005 -- 2006. This indicates that the quad relativistic MHD shock model can be applied generally to recurring pairs of super/subluminal knots ejected from the upstream edge o...
SHEAR STRESS FOR INITIATION OF MOTION OF NON-UNIFORM SEDIMENT MIXTURES
无
2007-01-01
Experiments on initiation of motion of different fractions of non-uniform sediment mixtures are reported. Four sediment mixes and reference transport method to define the threshold of bed particle movement are used in this analysis. Factors controlling the initiation of motion are analyzed. It is found that relative size of different grains with respect to a median size greatly affects the initiation of movement. The incipient motion of non-uniform sediment is very much dependent on the absolute size for coarser fractions.Considering the factors controlling the initiation of motion the experimental data sets along with the other available data yield a new relationship for the calculation of critical shear stress of non-uniform sediments. A set of equations have found that all the data points fall into a single line for the finer and for coarser fractions.
Geodesic motions of test particles in a relativistic core-shell spacetime
Liu, Lei; Wu, Xin; Huang, Guoqing
2017-02-01
In this paper, we discuss the geodesic motions of test particles in the intermediate vacuum between a monopolar core and an exterior shell of dipoles, quadrupoles and octopoles. The radii of the innermost stable circular orbits at the equatorial plane depend only on the quadrupoles. A given oblate quadrupolar leads to the existence of two innermost stable circular orbits, and their radii are larger than in the Schwarzschild spacetime. However, a given prolate quadrupolar corresponds to only one innermost stable circular orbit, and its radius is smaller than in the Schwarzschild spacetime. As to the general geodesic orbits, one of the recently developed extended phase space fourth order explicit symplectic-like methods is efficiently applicable to them although the Hamiltonian of the relativistic core-shell system is not separable. With the aid of both this fast integrator without secular growth in the energy errors and gauge invariant chaotic indicators, the effect of these shell multipoles on the geodesic dynamics of order and chaos is estimated numerically.
Scale Relativistic signature in the Brownian motion of micro-spheres in optical traps
Lebohec, Stephan
2017-09-01
The development of mechanics of nondifferentiable paths36 suggested by Scale Relativity31,32 results in a foundation of Quantum Mechanics30,37 including Schrödinger’s equation and all the other axioms under the assumption the path nondifferentiability can be described as a Wiener process at the resolution-scale of observation. This naturally brings under question the possibility that the statistics of the dynamics of macroscopic systems fulfilling this hypothesis could fall under a quantum-like description with the Planck constant replaced with some other constant, possibly system specific, and corresponding to a diffusion coefficient. The observation of such a quantum-like dynamics would establish if the Scale Relativistic principle is implemented in macroscopic complex or chaotic systems. This would have major implications for the study of structure formation dynamics in various research fields. In this paper, I investigate the possibility for the detection of such an effect in the Brownian motion of a micro-sphere in an optical trap. I find that, if it exists, the observation of the transition to a quantum-like regime is within reach of modern experiments.
On relativistic motion of a pair of particles having opposite signs of masses
Ivanov, Pavel
2012-01-01
(abbreviated) In this note we consider, in a weak-field limit, a relativistic linear motion of two particles with opposite signs of masses having a small difference between their absolute values $m_{1,2}=\\pm (\\mu\\pm \\Delta \\mu) $, $\\mu > 0$, $|\\Delta \\mu | \\ll \\mu$ and a small difference between their velocities. Assuming that the weak-field limit holds and the dynamical system is conservative an elementary treatment of the problem based on the laws of energy and momentum conservation shows that the system can be accelerated indefinitely, or attain very large asymptotic values of the Lorentz factor $\\gamma$. The system experiences indefinite acceleration when its energy-momentum vector is null and the mass difference $\\Delta \\mu \\le 0$. When modulus of the square of the norm of the energy-momentum vector, $|N^2|$, is sufficiently small the system can be accelerated to very large $\\gamma \\propto |N^2|^{-1}$. It is stressed that when only leading terms in the ratio of a characteristic gravitational radius to th...
Critical bed shear stress and threshold of motion of maerl biogenic gravel
Joshi, Siddhi; Duffy, Garret Patrick; Brown, Colin
2017-07-01
A determination of the critical bed shear stress of maerl is a prerequisite for quantifying its mobility, rate of erosion and deposition in conservation management. The critical bed shear stress for incipient motion has been determined for the first time for samples from biogenic free-living maerl beds in three contrasting environments (open marine, intertidal and beach) in Galway Bay, west of Ireland. The bed shear stress was determined using two methods, Law of the Wall and Turbulent Kinetic Energy, in a rotating annular flume and in a linear flume. The velocity profile of flowing water above a bed of natural maerl grains was measured in four runs of progressively increasing flow velocity until the flow exceeded the critical shear stress of grains on the bed. The critical Shields parameter and the mobility number are estimated and compared with the equivalent curves for natural quartz sand. The critical Shields parameters for the maerl particles from all three environments fall below the Shields curve. Along with a previously reported correlation between maerl grain shape and settling velocity, these results suggest that the highly irregular shapes also allow maerl grains to be mobilised more easily than quartz grains with the same sieve diameter. The intertidal beds with the roughest particles exhibit the greatest critical shear stress because the particle thalli interlock and resist entrainment. In samples with a high percentage of maerl and low percentage of siliciclastic sand, the lower density, lower settling velocity and lower critical bed shear stress of maerl results in its preferential transport over the siliciclastic sediment. At velocities ∼10 cm s-1 higher than the threshold velocity of grain motion, rarely-documented subaqueous maerl dunes formed in the annular flume.
Shear-induced fractures and three-dimensional motions in an organogel
Grondin, Pauline; Manneville, Sébastien; Pozzo, Jean-Luc; Colin, Annie
2009-01-01
International audience; The flow behavior of a viscoelastic organogel is investigated using ultrasonic velocimetry combined with rheometry. Our gel presents a decreasing flow curve, i.e., the measured stress decreases as a function of the applied shear rate. Strikingly, we note that the local flow curve calculated from the velocity profiles also exhibits a decreasing part. We attribute this regime to the presence of a fracturing process and three-dimensional motions in the bulk of the sample.
Shear-induced fractures and three-dimensional motions in an organogel
Grondin, Pauline; Manneville, Sébastien; Pozzo, Jean-Luc; Colin, Annie
2008-01-01
The flow behavior of a viscoelastic organogel is investigated using ultrasonic velocimetry combined with rheometry. Our gel presents a decreasing flow curve, i.e., the measured stress decreases as a function of the applied shear rate. Strikingly, we note that the local flow curve calculated from the velocity profiles also exhibits a decreasing part. We attribute this regime to the presence of a fracturing process and three-dimensional motions in the bulk of the sample.
Pathak, Himadri; Sasmal, Sudip; Nayak, Malaya K.; Vaval, Nayana; Pal, Sourav
2016-08-01
The open-shell reference relativistic equation-of-motion coupled-cluster method within its four-component description is successfully implemented with the consideration of single- and double- excitation approximations using the Dirac-Coulomb Hamiltonian. At the first attempt, the implemented method is employed to calculate ionization potential value of heavy atomic (Ag, Cs, Au, Fr, and Lr) and molecular (HgH and PbF) systems, where the effect of relativity does really matter to obtain highly accurate results. Not only the relativistic effect but also the effect of electron correlation is crucial in these heavy atomic and molecular systems. To justify the fact, we have taken two further approximations in the four-component relativistic equation-of-motion framework to quantify how the effect of electron correlation plays a role in the calculated values at different levels of theory. All these calculated results are compared with the available experimental data as well as with other theoretically calculated values to judge the extent of accuracy obtained in our calculations.
W.P.Wang; X.M.Zhang; X.F.Wang; X.Y.Zhao; J.C.Xu; Y.H.Yu; L.Q.Yi; Y.Shi; L.G.Zhang; T.J.Xu; C.Liu; Z.K.Pei; B.F.Shen
2014-01-01
The effects of ion motion on the generation of short-cycle relativistic laser pulses during radiation pressure acceleration are investigated by analytical modeling and particle-in-cell simulations. Studies show that the rear part of the transmitted pulse modulated by ion motion is sharper compared with the case of the electron shutter only. In this study, the ions further modulate the short-cycle pulses transmitted. A 3.9 fs laser pulse with an intensity of 1.33×1021W cm-2is generated by properly controlling the motions of the electron and ion in the simulations. The short-cycle laser pulse source proposed can be applied in the generation of single attosecond pulses and electron acceleration in a small bubble regime.
Onset and cessation of grain motion in fluid-sheared beds
Clark, Abe; Salevan, Julia; Shattuck, Mark; Ouellette, Nick; O'Hern, Corey
2015-11-01
We performed molecular dynamics simulations of granular beds driven by a model hydrodynamic shear flow to elucidate general grain-scale mechanisms that determine the onset and cessation of sediment transport. By varying the Shields number (the nondimensional shear stress at the top of the bed) and particle Reynolds number (the ratio of particle inertia to viscous damping), we explore how variations of the fluid flow rate, particle inertia, and fluid viscosity affect the onset and cessation of bed motion. For low to moderate particle Reynolds numbers, a critical boundary separates mobile and static states. Transition times between these states diverge as this boundary is approached both from above and below. At high particle Reynolds number, inertial effects become dominant, and particle motion can be sustained well below flow rates at which mobilization of a static bed occurs. We also find that the onset of bed motion (for both low and high particle Reynolds numbers) is described by Weibullian weakest-link statistics, and thus is crucially dependent on the packing structure of the granular bed, even deep beneath the surface. This work was supported by the US Army Research Office under Grant No. W911NF-14-1-0005.
Small-scale motions in turbulent boundary-free shear flows
Fiscaletti, D.
2016-01-01
The present work is an experimental and numerical investigation of the small-scale motions in turbulent free-shear flows. In the far-field turbulence of a jet at high Reynolds number (Reλ = 350) hot-wire anemometry (HWA) is applied to measure time series of flow velocity. By filtering these time series, large- and small-scale velocity fluctuations are obtained. Both the amplitude and the frequency of the small-scale signals are locally stronger (weaker) for positive (negative) fluctuations of...
Hydrodynamics of passing-over motion during binary droplet collision in shear flow
Wang, Cheng-Yao; Zhang, Cheng-Bin; Huang, Xiang-Yong; Liu, Xiang-Dong; Chen, Yong-Ping
2016-10-01
A combined experimental and numerical study is undertaken to investigate the hydrodynamic characteristics of single-phase droplet collision in a shear flow. The passing-over motion of interactive droplets is observed, and the underlying hydrodynamic mechanisms are elucidated by the analysis of the motion trajectory, transient droplet deformation and detailed hydrodynamic information (e.g., pressure and flow fields). The results indicate that the hydrodynamic interaction process under shear could be divided into three stages: approaching, colliding, and separating. With the increasing confinement, the interaction time for the passing-over process is shorter and the droplet processes one higher curvature tip and more stretched profile. Furthermore, the lateral separation Δy/R 1 exhibits larger decrease in the approaching stage and the thickness of the lubrication film is decreased during the interaction. As the initial lateral separation increases, the maximum trajectory shift by the collision interaction is getting smaller. During the collision between two droplets with different sizes, the amplitude of the deformation oscillation of the larger droplet is decreased by reducing the size ratio of the smaller droplet to the bigger one. Project supported by the NSAF (Grants No. U1530260), the National Natural Science Foundation of China (Grant No. 51306158), the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20130621), and the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund (the second phase).
Off-plane motion of a non-spherical capsule in simple shear flow
Omori, Toshihiro; Ishikawa, Takuji; Imai, Yohsuke; Yamaguchi, Takami
2012-11-01
Dynamics of a capsule and a biological cell in fluid flow is now of great interest in chemical engineering and bioengineering. In this study, we numerically investigated the motion of a spheroid capsule in simple shear flow including a red blood cell type biconcave disk. The membrane of a capsule was modeled by a two-dimensional hyperelastic material, and its large deformation was solved by a finite element method. The motion of internal and external liquids was estimated as a Stokes flow and solved by a boundary element method. The results showed that the orientation of a spheroid capsule is variant under time reversal, though that of a rigid spheroid is invariant. The final orientation of a spheroid capsule over a long time duration tends to converge to a certain direction depending on the shear rate despite initial placement with random orientation. These results can be utilized for a particle alignment technique and form a fundamental basis of the suspension mechanics of capsules and biological cells.
Onset of motion at the surface of a porous granular bed by a shearing fluid flow
Hong, Anyu; Tao, Mingjiang; Kudrolli, Arshad
2014-03-01
We will discuss an experimental investigation of the onset of particle motion by a fluid flow over an unconsolidated granular bed. This situation arises in a number of natural and industrial processes including wind blowing over sand, sediment transport in rivers, tidal flows interacting with beaches and flows in slurry pipelines and mixing tanks. The Shields criteria given by the ratio of the viscous shear and normal stresses is used to understand the onset of motion. However, reviews reveals considerable scatter while noting broad trends with Reynolds Number. We discuss an idealized model system where fluid flows with a prescribed flow rate through a horizontal rectangular pipe initially fully filled with granular beads. The granular bed height decreases and reaches a constant height when the shear stress at the boundary decreases below a critical value. We compare and contrast the values obtained assuming no-slip boundary conditions with those observed with PIV using florescent tracer particles to measure the actual fluid flow profile near the porous interface. We will also report the observed variation of the Shields criteria with particle Reynolds Number by varying particle size and fluid flow rates.
Itoh, Y
2004-01-01
An equation of motion for relativistic compact binaries is derived through the third post-Newtonian (3 PN) approximation of general relativity. The strong field point particle limit and multipole expansion of the stars are used to solve iteratively the harmonically relaxed Einstein equations. We take into account the Lorentz contraction on the multipole moments defined in our previous works. We then derive a 3 PN acceleration of the binary orbital motion of the two spherical compact stars based on a surface integral approach which is a direct consequence of local energy momentum conservation. Our resulting equation of motion admits a conserved energy (neglecting the 2.5 PN radiation reaction effect), is Lorentz invariant and is unambiguous: there exist no undetermined parameter reported in the previous works. We shall show that our 3 PN equation of motion agrees physically with the Blanchet and Faye 3 PN equation of motion if $\\lambda = - 1987/3080$, where $\\lambda$ is the parameter which is undetermined with...
On The Relativistic Classical Motion of a Radiating Spinning Particle in a Magnetic Field
Kar, Arnab
2010-01-01
We propose classical equations of motion for a charged particle with magnetic moment, taking radiation reaction into account. This generalizes the Landau-Lifshitz equations for the spinless case. In the special case of spin-polarized motion in a constant magnetic field (synchrotron motion) we verify that the particle does lose energy. Previous proposals did not predict dissipation of energy and also suffered from runaway solutions analogous to those of the Lorentz-Dirac equations of motion.
On the relativistic classical motion of a radiating spinning particle in a magnetic field
Kar, Arnab; Rajeev, S. G.
2011-04-01
We propose classical equations of motion for a charged particle with magnetic moment, taking radiation reaction into account. This generalizes the Landau-Lifshitz equations for the spinless case. In the special case of spin-polarized motion in a constant magnetic field (synchrotron motion) we verify that the particle does lose energy. Previous proposals did not predict dissipation of energy and also suffered from runaway solutions analogous to those of the Lorentz-Dirac equations of motion.
Velocity Shear of the Thick Disk from SPM3 Proper Motions at the South Galactic Pole
Girard, T M; Casetti-Dinescu, D I; Van Altena, W F; Lopez, C E; Monet, D G
2006-01-01
The kinematical properties of the Galactic Thick Disk are studied using absolute proper motions from the SPM3 Catalog and 2MASS near-infrared photometry for a sample of ~1200 red giants in the direction of the South Galactic Pole. The photometrically-selected sample is dominated by Thick Disk stars, as indicated by the number-density distribution that varies with distance from the Galactic plane as a single-valued exponential over the range 1
Pabon, Rommel; Barnard, Casey; Ukeiley, Lawrence; Sheplak, Mark
2016-11-01
Particle image velocimetry (PIV) and fluctuating wall shear stress experiments were performed on a flat plate turbulent boundary layer (TBL) under zero pressure gradient conditions. The fluctuating wall shear stress was measured using a microelectromechanical 1mm × 1mm floating element capacitive shear stress sensor (CSSS) developed at the University of Florida. The experiments elucidated the imprint of the organized motions in a TBL on the wall shear stress through its direct measurement. Spatial autocorrelation of the streamwise velocity from the PIV snapshots revealed large scale motions that scale on the order of boundary layer thickness. However, the captured inclination angle was lower than that determined using the classic method by means of wall shear stress and hot-wire anemometry (HWA) temporal cross-correlations and a frozen field hypothesis using a convection velocity. The current study suggests the large size of these motions begins to degrade the applicability of the frozen field hypothesis for the time resolved HWA experiments. The simultaneous PIV and CSSS measurements are also used for spatial reconstruction of the velocity field during conditionally sampled intense wall shear stress events. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1315138.
罗少盈; 刘琦
2014-01-01
In this article, we concern the motion of relativistic membranes and null mem-branes in the Reissner-Nordstr¨om space-time. The equation of relativistic membranes moving in the Reissner-Nordstr¨om space-time is derived and some properties are discussed. Spherical symmetric solutions for the motion are illustrated and some interesting physical phenomena are discovered. The equations of the null membranes are derived and the exact solutions are also given. Spherical symmetric solutions for null membranes are just the two horizons of Reissner-Nordstr¨om space-time.
C. Dhanapal
2016-01-01
Full Text Available This paper analyzes the peristaltic flow of an incompressible micropolar nanofluid in a tapered asymmetric channel in the presence of thermal radiation and heat sources parameters. The rotation of the nanoparticles is incorporated in the flow model. The equations governing the nanofluid flow are modeled and exact solutions are managed under long wavelength and flow Reynolds number and long wavelength approximations. Explicit expressions of axial velocity, stream function, microrotation, nanoparticle temperature, and concentration have been derived. The phenomena of shear stress and trapping have also been discussed. Finally, the influences of various parameters of interest on flow variables have been discussed numerically and explained graphically. Besides, the results obtained in this paper will be helpful to those who are working on the development of various realms like fluid mechanics, the rotation, Brownian motion, thermophoresis, coupling number, micropolar parameter, and the nondimensional geometry parameters.
Dhanapal, C.; Kamalakkannan, J.; Prakash, J.
2016-01-01
This paper analyzes the peristaltic flow of an incompressible micropolar nanofluid in a tapered asymmetric channel in the presence of thermal radiation and heat sources parameters. The rotation of the nanoparticles is incorporated in the flow model. The equations governing the nanofluid flow are modeled and exact solutions are managed under long wavelength and flow Reynolds number and long wavelength approximations. Explicit expressions of axial velocity, stream function, microrotation, nanoparticle temperature, and concentration have been derived. The phenomena of shear stress and trapping have also been discussed. Finally, the influences of various parameters of interest on flow variables have been discussed numerically and explained graphically. Besides, the results obtained in this paper will be helpful to those who are working on the development of various realms like fluid mechanics, the rotation, Brownian motion, thermophoresis, coupling number, micropolar parameter, and the nondimensional geometry parameters. PMID:27688703
Current accumulation at an asymmetric 3D null point caused by generic shearing motions
Galsgaard, K.; Pontin, D. I.
2011-10-01
Context. Here we investigate the dynamical evolution of the reconnection process at an initially linear 3D null point that is stressed by a localised shear motion across the spine axis. The difference to previous investigations is that the fan plane is not rotationally symmetric and this allows for different behaviours depending on the alignment of the fan plane relative to the imposed driver direction. Aims: The aim is to show how the current accumulation and the associated reconnection process at the non-axisymmetric null depends on the relative orientation between the driver imposed stress across the spine axis of the null and the main eigenvector direction in the fan plane. Methods: The time evolution of the 3D null point is investigated solving the 3D non-ideal MHD equations numerically in a Cartesian box. The magnetic field is frozen to the boundaries and the boundary velocity is only non-zero where the imposed driving for stressing the system is applied. Results: The current accumulation is found to be along the direction of the fan eigenvector associated with the smallest eigenvalue until the direction of the driver is almost parallel to this eigenvector. When the driving velocity is parallel to the weak eigenvector and has an impulsive temporal profile the null only has a weak collapse forming only a weak current layer. However, when the null point is stressed continuously boundary effects dominates the current accumulation. Conclusions: There is a clear relation between the orientation of the current concentration and the direction of the fan eigenvector corresponding to the small eigenvalue. This shows that the structure of the magnetic field is the most important in determining where current is going to accumulate when a single 3D null point is perturbed by a simple shear motion across the spine axis. As the angle between the driving direction and the strong eigenvector direction increases, the current that accumulates at the null becomes progressively
Red blood cell: from its mechanics to its motion in shear flow.
Viallat, A; Abkarian, M
2014-06-01
There is a number of publications on red blood cell deformability, that is, on the remarkable cell ability to change its shape in response to an external force and to pass through the narrowest blood capillaries and splenic sinuses. Cell deformability is postulated to be a major determinant of impaired perfusion, increase of blood viscosity, and occlusion in microvessels. Current deformability tests like ektacytometry measure global parameters, related to shape changes at the whole cell scale. Despite strong advances in our understanding of the molecular organization of red blood cells, the relationships between the rheology of each element of the cell composite structure, the global deformability tests, and the cell behavior in microflows are still not elucidated. This review describes recent advances in the description of the dynamics of red blood cells in shear flow and in the mechanistic understanding of this dynamics at the scale of the constitutive rheological and structural elements of the cell. These developments could open up new horizons for the determination of red blood cell mechanical parameters by analyzing their motion under low shear flows.
Relativistic and non-relativistic geodesic equations
Giambo' , R.; Mangiarotti, L.; Sardanashvily, G. [Camerino Univ., Camerino, MC (Italy). Dipt. di Matematica e Fisica
1999-07-01
It is shown that any dynamic equation on a configuration space of non-relativistic time-dependent mechanics is associated with connections on its tangent bundle. As a consequence, every non-relativistic dynamic equation can be seen as a geodesic equation with respect to a (non-linear) connection on this tangent bundle. Using this fact, the relationships between relativistic and non-relativistic equations of motion is studied.
Sahai, Aakash A
2014-01-01
We analyze the motion of the plasma critical layer by two different processes in the relativistic-electron laser-plasma interaction regime ($a_0>1$). The differences are highlighted when the critical layer ions are stationary in contrast to when they move with it. Controlling the speed of the plasma critical layer in this regime is essential for creating low-$\\beta$ traveling acceleration structures of sufficient laser-excited potential for laser ion accelerators (LIA). In Relativistically Induced Transparency Acceleration (RITA) scheme the heavy plasma-ions are fixed and only trace-density light-ions are accelerated. The relativistic critical layer and the acceleration structure move longitudinally forward by laser inducing transparency through apparent relativistic increase in electron mass. In the Radiation Pressure Acceleration (RPA) scheme the whole plasma is longitudinally pushed forward under the action of the laser radiation pressure, possible only when plasma ions co-propagate with the laser front. I...
Does motion affect liver stiffness estimates in shear wave elastography? Phantom and clinical study.
Pellot-Barakat, Claire; Chami, Linda; Correas, Jean Michel; Lefort, Muriel; Lucidarme, Olivier
2016-09-01
This study was undertaken to evaluate the impact of free-breathing (FB) vs. Apnea on Shear-wave elastography (SWE) measurements. Quantitative liver-stiffness measurements were obtained during FB and Apnea for 97 patients with various body-morphologies and liver textures. Quality indexes of FB and Apnea elasticity maps (percentage of non-filling (PNF), temporal (TV) and spatial (SV) variabilities) were computed. SWE measurements were also obtained from an homogeneous phantom at rest and during a mechanically-induced motion. Liver-stiffness values estimated from FB and Apnea acquisitions were correlated, particularly for homogeneous livers (r=0.76, PFB values were consistently 20-25% lower than Apnea ones (PFB also systematically resulted in degradation of TV (PFB measurements are highly correlated, although FB data quality is degraded compared to Apnea and estimated stiffness in FB is systematically lower than in Apnea. These discrepancies between rest and motion states were observed for patients but not for phantom data, suggesting that patient breath-holding impacts liver stiffness.
Acoustic perturbations in special-relativistic parallel flows
Rogava, A D; Mahajan, S M
1996-01-01
Acoustic perturbations in a parallel relativistic flow of an inviscid fluid are considered. The general expression for the frequency of the sound waves in a uniformly (with zero shear) moving medium is derived. It is shown that relativity evokes a difference in the frequencies of the sound-type perturbations propagating along and against the current. Besides, it is shown that the perturbations are not purely irrotational as they are in nonrelativistic case. For a non-uniformly (with nonzero shear) moving fluid a general set of equations, describing the evolution of the acoustic perturbations in relativistic sheared flows, is obtained and analysed when the temperature is nonrelativistic. It is shown that, like the nonrelativistic case, in the new system: (a) the excitation of vortical, transiently growing perturbations, and (b) the excitation of sound-type perturbations, extracting the kinetic energy of the background flow, are possible. It is demonstrated that the relativistic character of the motion signific...
A classical and a relativistic law of motion for SN1987A
Zaninetti, L
2016-01-01
In this paper we derive some first order differential equations which model the classical and the relativistic thin layer approximations in the presence of a circumstellar medium with a density which is decreasing in the distance $z$ from the equatorial plane. The circumstellar medium is assumed to follow a density profile with $z$ of hyperbolic type, power law type, exponential type or Gaussian type. The first order differential equations are solved analytically, or numerically, or by a series expansion, or by Pad\\'e approximants. The initial conditions are chosen in order to model the temporal evolution of SN 1987A over 23 years. The free parameters of the theory are found by maximizing the observational reliability which is based on an observed section of SN 1987A.
,
2016-01-01
With Einstein's inertial motion (free-falling and non-rotating relative to gyroscopes), geodesics for non-relativistic particles can intersect repeatedly, allowing one to compute the space-time curvature $R^{\\hat{0} \\hat{0}}$ exactly. Einstein's $R^{\\hat{0} \\hat{0}}$ for strong gravitational fields and for relativistic source-matter is identical with the Newtonian expression for the relative radial acceleration of neighboring free-falling test-particles, spherically averaged.--- Einstein's field equations follow from Newtonian experiments, local Lorentz-covariance, and energy-momentum conservation combined with the Bianchi identity.
Current accumulation at an asymmetric 3D null point caused by generic shearing motions
Galsgaard, Klaus
2011-01-01
Context. We investigate the dynamical evolution of the reconnection process at an initially linear 3D null point that is stressed by a localised shear motion across the spine axis. The fan plane is not rotationally symmetric and this allows for different behaviours depending on the alignment of the fan plane relative to the imposed driver direction. Aims. The aim is to show how the current accumulation and the associated reconnection process depends on the relative orientation between the driver imposed stress across the spine axis of the null and the main eigenvector direction in the fan plane. Methods. The time evolution of the 3D null point is investigated solving the 3D non-ideal MHD equations numerically in a Cartesian box. The magnetic field is frozen to the boundaries and the boundary velocity is only non-zero where the imposed driving is for stressing the system is applied. Results. The current accumulation is found to be along the direction of the fan eigenvector associated with the smallest eigenval...
Motion of a distant solid particle in a shear flow along a porous slab
Khabthani, S.; Sellier, A.; Feuillebois, F.
2013-12-01
The motion of a solid and no-slipping particle immersed in a shear flow along a sufficiently porous slab is investigated. The fluid flow outside and inside of the slab is governed by the Stokes and Darcy equations, respectively, and the so-called Beavers and Joseph slip boundary conditions are enforced on the slab surface. The problem is solved for a distant particle with length scale a in terms of the small parameter a/ d where d designates the large particle-slab separation. This is achieved by asymptotically inverting a relevant boundary-integral equation on the particle surface, which has been recently proposed for any particle location (distant or close particle) in Khabthani et al. (J Fluid Mech 713:271-306, 2012). It is found that at order O( a/ d) the slab behaves for any particle shape as a solid plane no-slip wall while the slab properties (thickness, permeability, associated slip length) solely enter at O(( a/ d)2). Moreover, for a spherical particle, the numerical results published in Khabthani et al. (J Fluid Mech 713:271-306, 2012) perfectly agree with the present asymptotic analysis.
Ditlevsen, Ove Dalager; Lazarov, Boyan Stefanov
2003-01-01
, and with no force feed back from any of the three masses to masses situated below it. The first mass from the ground is force excited by stationary Gaussian white noise as specified in the Clough-Penzien filter definition. The study includes comparisons between plastic displacement results for the same three story...... for a single story shear frame excited by stationary Gaussian ground motion defined by the output of a Clough-Penzien filter with Gaussian white noise input. This is equivalent to considering an artificial three story elasto-plastic shear frame with possible yielding solely in the third column connection...... frame with partial or full feed back from the movement of the top mass to the second and the first mass (top soil layer mass and base rock mass, respectively). Keywords: Clough-Penzien filtered white noise excitation, elasto-plastic shear frame oscillator, plastic displacement distributions, simplified...
Itoh, Yousuke
2009-01-01
We report our rederivation of the equations of motion for relativistic compact binaries through the third-and-a-half post-Newtonian (3.5 PN) order approximation to general relativity using the strong field point particle limit to describe self-gravitating stars instead of the Dirac delta functional. The computation is done in harmonic coordinates. Our equations of motion describe the orbital motion of the binary consisting of spherically symmetric non-rotating stars. The resulting equations of motion fully agree with the 3.5 PN equations of motion derived in the previous works. We also show that the locally defined energy of the star has a simple relation with its mass up to the 3.5 PN order.
Itoh, Y; Asada, H; Itoh, Yousuke; Futamase, Toshifumi; Asada, Hideki
2001-01-01
We study the equation of motion appropriate to an inspiralling binary star system whose constituent stars have strong internal gravity. We use the post-Newtonian approximation with the strong field point particle limit by which we can introduce into general relativity a notion of a point-like particle with strong internal gravity without using Dirac delta distribution. Besides this limit, to deal with strong internal gravity we express the equation of motion in surface integral forms and calculate these integrals explicitly. As a result we obtain the equation of motion for a binary of compact bodies accurate through the second and half post-Newtonian (2.5 PN) order. This equation is derived in the harmonic coordinate. Our resulting equation perfectly agrees with Damour and Deruelle 2.5 PN equation of motion. Hence it is found that the 2.5 PN equation of motion is applicable to a relativistic compact binary.
Performances of motion tracking enhanced Tomo-PIV on turbulent shear flows.
Novara, Matteo; Scarano, Fulvio
The motion tracking enhancement technique (MTE) is a recently introduced method to improve the accuracy of tomographic PIV measurements at seeding density higher than currently practiced. The working principle is based on the fact that the particle field and its projections are correlated between the two exposures. Therefore, information from subsequent exposures can be shared within the tomographic reconstruction process of a single object, which largely reduces the energy lost into ghost particles. The study follows a previous work based on synthetic particle images, showing that the MTE technique has an effect similar to that of increasing the number of cameras. In the present analysis, MTE is applied to Tomographic PIV data from two time-resolved experiments on turbulent shear flows: a round jet at Re = 5,000 (facq = 1,000 Hz) and a turbulent boundary layer at the trailing edge of an airfoil (Rec = 370,000) measured at 12,000 Hz. The application of MTE is extended to the case of more than two recordings. The performance is assessed comparing the results from a lowered number of cameras with respect to the full tomographic imaging system. The analysis of the jet flow agrees with the findings of numerical simulations provided the results are scaled taking into account the concept of MTE efficiency based on the volume fraction where ghost-pairs (Elsinga et al. 2010a) are produced. When a large fraction of fluid has uniform motion (stagnant fluid surrounding the jet), only a moderate reduction in ghost intensity is expected by MTE. Nevertheless, a visible recovery of reconstruction quality is observed for the 3-cameras system when MTE is applied making use of 3 recordings. In the turbulent boundary layer, the objective is set to increase the seeding density beyond current practice, and the experiments are performed at approximately 200,000 particles/megapixel. The measurement robustness is monitored with the signal-to-noise ratio S/N for the cross
Performances of motion tracking enhanced Tomo-PIV on turbulent shear flows
Novara, Matteo; Scarano, Fulvio
2012-04-01
The motion tracking enhancement technique (MTE) is a recently introduced method to improve the accuracy of tomographic PIV measurements at seeding density higher than currently practiced. The working principle is based on the fact that the particle field and its projections are correlated between the two exposures. Therefore, information from subsequent exposures can be shared within the tomographic reconstruction process of a single object, which largely reduces the energy lost into ghost particles. The study follows a previous work based on synthetic particle images, showing that the MTE technique has an effect similar to that of increasing the number of cameras. In the present analysis, MTE is applied to Tomographic PIV data from two time-resolved experiments on turbulent shear flows: a round jet at Re = 5,000 ( f acq = 1,000 Hz) and a turbulent boundary layer at the trailing edge of an airfoil ( Re c = 370,000) measured at 12,000 Hz. The application of MTE is extended to the case of more than two recordings. The performance is assessed comparing the results from a lowered number of cameras with respect to the full tomographic imaging system. The analysis of the jet flow agrees with the findings of numerical simulations provided the results are scaled taking into account the concept of MTE efficiency based on the volume fraction where ghost- pairs (Elsinga et al. 2010a) are produced. When a large fraction of fluid has uniform motion (stagnant fluid surrounding the jet), only a moderate reduction in ghost intensity is expected by MTE. Nevertheless, a visible recovery of reconstruction quality is observed for the 3-cameras system when MTE is applied making use of 3 recordings. In the turbulent boundary layer, the objective is set to increase the seeding density beyond current practice, and the experiments are performed at approximately 200,000 particles/megapixel. The measurement robustness is monitored with the signal-to-noise ratio S/N for the cross
Vemareddy, P.
2017-08-01
We study the magnetic field evolution in AR 12371, related to its successive eruptive nature. During the disk transit of seven days, the active region (AR) launched four sequential fast coronal mass ejections (CMEs), which are associated with long duration M-class flares. Morphological study delineates a pre-eruptive coronal sigmoid structure above the polarity inversion line (PIL) similar to Moore et al.’s study. The velocity field derived from tracked magnetograms indicates persistent shear and converging motions of polarity regions about the PIL. While these shear motions continue, the crossed arms of two sigmoid elbows are being brought to interaction by converging motions at the middle of the PIL, initiating the tether-cutting reconnection of field lines and the onset of the CME explosion. The successive CMEs are explained by a cyclic process of magnetic energy storage and release referred to as “sigmoid-to-arcade-to-sigmoid” transformation driven by photospheric flux motions. Furthermore, the continued shear motions inject helicity flux with a dominant negative sign, which contributes to core field twist and its energy by building a twisted flux rope (FR). After a limiting value, the excess coronal helicity is expelled by bodily ejection of the FR, which is initiated by some instability as realized by intermittent CMEs. This AR is in contrast with the confined AR 12192 with a predominant negative sign and larger helicity flux, but much weaker (-0.02 turns) normalized coronal helicity content. While predominant signed helicity flux is a requirement for CME eruption, our study suggests that the magnetic flux normalized helicity flux is a necessary condition accommodating the role of background flux and appeals to a further study of a large sample of ARs.
Xu Sheng-Hua; Sun Zhi-Wei; Li Xu; Jin Tong Wang
2012-01-01
Simultaneous orthokinetic and perikinetic coagulations(SOPCs)are studied for small and large Peclet numbers(Pe)using Brownian dynamics simulation.The results demonstrate that the contributions of the Brownian motion and the shear flow to the overall coagulation rate are basically not additive.At the early stages of coagulation with small Peclet numbers,the ratio of overall coagulation rate to the rate of pure perikinetic coagulation is proportional to Pe1/2,while with high Peclet numbers,the ratio of overall coagulation rate to the rate of pure orthokinetic coagulation is proportional to pe-1/2.Moreover,our results show that the aggregation rate generally changes with time for the SOPC,which is different from that for pure preikinetic and pure orthokinetic coagulations.By comparing the SOPC with pure preikinetic and pure orthokinetic coagulations,we show that the redistribution of particles due to Brownian motion can play a very important role in the SOPC.In addition,the effects of redistribution in the directions perpendicular and parallel to the shear flow direction are different.This perspective explains the behavior of coagulation due to the joint effects of the Brownian motion(perikinetic)and the fluid motion(orthokinetic).
Sun, Yu-Long; Wei, Zhuang; Zhao, Chunfeng; Jay, Gregory D; Schmid, Thomas M; Amadio, Peter C; An, Kai-Nan
2015-06-01
Achilles tendon is one of the most commonly injured tendons. Mechanical force is regarded as a major causative factor. However, the biomechanics of Achilles tendon and mechanical mechanism of the injuries are unclear. Lubricin expresses at regions exposed to sliding motion and shear force in a number of tissues. This study investigated the distribution and concentration of lubricin in human Achilles tendons for better understanding the biomechanics of Achilles tendon. Achilles tendons were harvested from nine cadavers. Lubricin was extracted from various locations proximal to the calcaneal insertion and quantified with ELISA. The distribution of lubricin was investigated with immunohistochemistry. Lubricin was mainly identified at the interfaces of tendon fascicles, especially in the mid-portion of the tendon. The concentration of lubricin in Achilles tendons varied by individual and the distance from its calcaneal insertion. The distal portion of the tendon had a higher concentration of lubricin than the proximal regions of the tendon. This study suggests the presence of intratendinous sliding motion of fascicles and shear force at interfaces of fascicles in human Achilles tendon. Shear force could be an important mechanical factor for the development of Achilles tendinopathy and rupture.
Sahai, Aakash A., E-mail: aakash.sahai@gmail.com [Department of Electrical Engineering, Duke University, Durham, North Carolina 27708 (United States)
2014-05-15
We analyze the motion of the plasma critical layer by two different processes in the relativistic-electron laser-plasma interaction regime (a{sub 0}>1). The differences are highlighted when the critical layer ions are stationary in contrast to when they move with it. Controlling the speed of the plasma critical layer in this regime is essential for creating low-β traveling acceleration structures of sufficient laser-excited potential for laser ion accelerators. In Relativistically Induced Transparency Acceleration (RITA) scheme, the heavy plasma-ions are fixed and only trace-density light-ions are accelerated. The relativistic critical layer and the acceleration structure move longitudinally forward by laser inducing transparency through apparent relativistic increase in electron mass. In the Radiation Pressure Acceleration (RPA) scheme, the whole plasma is longitudinally pushed forward under the action of the laser radiation pressure, possible only when plasma ions co-propagate with the laser front. In RPA, the acceleration structure velocity critically depends upon plasma-ion mass in addition to the laser intensity and plasma density. In RITA, mass of the heavy immobile plasma-ions does not affect the speed of the critical layer. Inertia of the bared immobile ions in RITA excites the charge separation potential, whereas RPA is not possible when ions are stationary.
Sahai, Aakash A.
2014-05-01
We analyze the motion of the plasma critical layer by two different processes in the relativistic-electron laser-plasma interaction regime (a0>1). The differences are highlighted when the critical layer ions are stationary in contrast to when they move with it. Controlling the speed of the plasma critical layer in this regime is essential for creating low-β traveling acceleration structures of sufficient laser-excited potential for laser ion accelerators. In Relativistically Induced Transparency Acceleration (RITA) scheme, the heavy plasma-ions are fixed and only trace-density light-ions are accelerated. The relativistic critical layer and the acceleration structure move longitudinally forward by laser inducing transparency through apparent relativistic increase in electron mass. In the Radiation Pressure Acceleration (RPA) scheme, the whole plasma is longitudinally pushed forward under the action of the laser radiation pressure, possible only when plasma ions co-propagate with the laser front. In RPA, the acceleration structure velocity critically depends upon plasma-ion mass in addition to the laser intensity and plasma density. In RITA, mass of the heavy immobile plasma-ions does not affect the speed of the critical layer. Inertia of the bared immobile ions in RITA excites the charge separation potential, whereas RPA is not possible when ions are stationary.
Nandy, D K; Sahoo, B K
2014-01-01
We report the implementation of equation-of-motion coupled-cluster (EOMCC) method in the four-component relativistic framework with the spherical atomic potential to generate the excited states from a closed-shell atomic configuration. This theoretical development will be very useful to carry out high precision calculations of varieties of atomic properties in many atomic systems. We employ this method to calculate excitation energies of many low-lying states in a few Ne-like highly charged ions, such as Cr XV, Fe XVII, Co XVIII and Ni XIX ions, and compare them against their corresponding experimental values to demonstrate the accomplishment of the EOMCC implementation. The considered ions are apt to substantiate accurate inclusion of the relativistic effects in the evaluation of the atomic properties and are also interesting for the astrophysical studies. Investigation of the temporal variation of the fine structure constant (\\alpha) from the astrophysical observations is one of the modern research problems...
Theoretical study of motion of small spherical air bubbles in a uniform shear flow of water
Mehdi, Syed Murtuza [Mechatronics Engineering, Jeju National University, Jeju (Korea, Republic of); Kim, Sin [School of Energy Systems Engineering, Chung-Ang University, Seoul (Korea, Republic of)
2015-02-15
A simple Couette flow velocity profile with an appropriate correlation for the free terminal rise velocity of a single bubble in a quiescent liquid can produce reliable results for the trajectories of small spherical air bubbles in a low-viscosity liquid (water) provided the liquid remains under uniform shear flow. Comparison of the model adopted in this paper with published results has been accomplished. Based on this study it has also been found that the lift coefficient in water is higher than its typical value in a high-viscosity liquid and therefore a modified correlation for the lift coefficient in a uniform shear flow of water within the regime of the Eoetvoes number 0:305 ≤ Eo ≤ 1:22 is also presented.
Performances of motion tracking enhanced Tomo-PIV on turbulent shear flows
Novara, M.; Scarano, F.
2012-01-01
The motion tracking enhancement technique (MTE) is a recently introduced method to improve the accuracy of tomographic PIV measurements at seeding density higher than currently practiced. The working principle is based on the fact that the particle field and its projections are correlated between th
Motion of cells sedimenting on a solid surface in a laminar shear flow.
Tissot, O; Pierres, A; Foa, C; Delaage, M; Bongrand, P
1992-01-01
Cell adhesion often occurs under dynamic conditions, as in flowing blood. A quantitative understanding of this process requires accurate knowledge of the topographical relationships between the cell membrane and potentially adhesive surfaces. This report describes an experimental study made on both the translational and rotational velocities of leukocytes sedimenting of a flat surface under laminar shear flow. The main conclusions are as follows: (a) Cells move close to the wall with constant velocity for several tens of seconds. (b) The numerical values of translational and rotational velocities are inconsistent with Goldman's model of a neutrally buoyant sphere in a laminar shear flow, unless a drag force corresponding to contact friction between cells and the chamber floor is added. The phenomenological friction coefficient was 7.4 millinewton.s/m. (c) Using a modified Goldman's theory, the width of the gap separating cells (6 microns radius) from the chamber floor was estimated at 1.4 micron. (d) It is shown that a high value of the cell-to-substrate gap may be accounted for by the presence of cell surface protrusions of a few micrometer length, in accordance with electron microscope observations performed on the same cell population. (e) In association with previously reported data (Tissot, O., C. Foa, C. Capo, H. Brailly, M. Delaage, and P. Bongrand. 1991. Biocolloids and Biosurfaces. In press), these results are consistent with the possibility that cell-substrate attachment be initiated by the formation of a single molecular bond, which might be considered as the rate limiting step.
Pireaux, S; Rosenblatt, P
2006-01-01
Today, the motion of spacecrafts is still described according to the classical Newtonian equations plus the so-called "relativistic corrections", computed with the required precision using the Post-(Post-)Newtonian formalism. The current approach, with the increase of tracking precision (Ka-Band Doppler, interplanetary lasers) and clock stabilities (atomic fountains) is reaching its limits in terms of complexity, and is furthermore error prone. In the appropriate framework of General Relativity, we study a method to numerically integrate the native relativistic equations of motion for a weak gravitational field, also taking into account small non-gravitational forces. The latter are treated as perturbations, in the sense that we assume that both the local structure of space-time is not modified by these forces, and that the unperturbed satellite motion follows the geodesics of the local space-time. The use of a symplectic integrator to compute the unperturbed geodesic motion insures the constancy of the norm ...
Exact Relativistic 'Antigravity' Propulsion
Felber, F S
2006-01-01
The Schwarzschild solution is used to find the exact relativistic motion of a payload in the gravitational field of a mass moving with constant velocity. At radial approach or recession speeds faster than 3^-1/2 times the speed of light, even a small mass gravitationally repels a payload. At relativistic speeds, a suitable mass can quickly propel a heavy payload from rest nearly to the speed of light with negligible stresses on the payload.
Exact Relativistic `Antigravity' Propulsion
Felber, Franklin S.
2006-01-01
The Schwarzschild solution is used to find the exact relativistic motion of a payload in the gravitational field of a mass moving with constant velocity. At radial approach or recession speeds faster than 3-1/2 times the speed of light, even a small mass gravitationally repels a payload. At relativistic speeds, a suitable mass can quickly propel a heavy payload from rest nearly to the speed of light with negligible stresses on the payload.
Wachter, H
2007-01-01
The aim of these three papers (I, II, and III) is to develop a q-deformed version of non-relativistic Schroedinger theory. Paper I introduces the fundamental mathematical and physical concepts. The braided line and the three-dimensional q-deformed Euclidean space play the role of position space. For both cases the algebraic framework is extended by a time element. A short review of the elements of q-deformed analysis on the spaces under consideration is given. The time evolution operator is introduced in a consistent way and its basic properties are discussed. These reasonings are continued by proposing q-deformed analogs of the Schroedinger and the Heisenberg picture.
Koch, Jon; Borg, John; Mattson, Abby; Olsen, Kris; Bahcall, James
2012-01-01
Objective. This in vitro study compared the flow pattern and shear stress of an irrigant induced by ultrasonic and polymer rotary finishing file activation in an acrylic root canal model. Flow visualization analysis was performed using an acrylic canal filled with a mixture of distilled water and rheoscopic fluid. The ultrasonic and polymer rotary finishing file were separately tested in the canal and activated in a static position and in a cyclical axial motion (up and down). Particle movement in the fluid was captured using a high-speed digital camera and DaVis 7.1 software. The fluid shear stress analysis was performed using hot film anemometry. A hot-wire was placed in an acrylic root canal and the canal was filled with distilled water. The ultrasonic and polymer rotary finishing files were separately tested in a static position and in a cyclical axial motion. Positive needle irrigation was also tested separately for fluid shear stress. The induced wall shear stress was measured using LabVIEW 8.0 software.
Qin, Y P
2003-01-01
We display by numerical calculation how rest frame spectral lines appear in the observed spectrum of gamma-ray bursts due to the Doppler effect in the fireball framework. The analysis shows that: a) in the spectrum of a relativistically expanding fireball, all rest frame lines would shift to higher energy bands and would be significantly smoothed; b) rest frame weak narrow emission lines as well as narrow absorption lines and absorption line forests would be smoothed and would hardly be detectable; c) the features of rest frame broad emission lines as well as both strong and weak broad absorption lines would remain almost unchanged and therefore would be easier to detect; d) deep gaps caused by rest frame broad absorption lines would be significantly filled; e) a rest frame emission line forest would form a single broad line feature; f) the observed relative width of the rest frame very narrow line would approach $ 0.162$; g) when the Lorentz factor $\\Gamma $ is large enough, the observed line frequency $\
Xu, Peng
2016-01-01
With continuous advances in technologies related to deep space ranging and satellite gravity gradiometry, corrections from general relativity to the dynamics of relative orbital motions will certainly become important. In this work, we extend,in a systematic way, the Hill-Clohessy-Wiltshire Equations to include the complete first order post-Newtonian effects from general relativity. Within certain short time limit, post-Newtonian corrections to general periodic solutions of the Hill-Clohessy-Wiltshire Equations are also worked out.
Graybill, George
2007-01-01
Take the mystery out of motion. Our resource gives you everything you need to teach young scientists about motion. Students will learn about linear, accelerating, rotating and oscillating motion, and how these relate to everyday life - and even the solar system. Measuring and graphing motion is easy, and the concepts of speed, velocity and acceleration are clearly explained. Reading passages, comprehension questions, color mini posters and lots of hands-on activities all help teach and reinforce key concepts. Vocabulary and language are simplified in our resource to make them accessible to str
Yu, Qingjuan; Lu, Youjun
2016-01-01
In this paper, we investigate the quality of constraining the spin of the massive black hole (MBH) at the Galactic center (GC), by using full general relativistic simulations of the motion of a surrounding star. We obtain the mapping of the dependence of the spin-induced signals on any spin direction of the MBH for given example stars, which indicates the feasibility to test whether the spin direction is the same as the normal of the young stellar disk located at the GC and further to provide insights into the assembly history of the MBH. We demonstrate the quality of constraining the MBH spin that may be achieved, given any set of the astrometric and the redshift precisions of observational facilities. We find that in the ranges of the astrometric and the velocity precisions with 1--30$\\mu$as and 0.1--10 km/s, an improvement in astrometric precision would be more effective in improving the quality of constraining the spin than an improvement in velocity precision. We obtain the parameter space of the semimaj...
Rosén, T.; Einarsson, J.; Nordmark, A.; Aidun, C. K.; Lundell, F.; Mehlig, B.
2015-12-01
We numerically analyze the rotation of a neutrally buoyant spheroid in a shear flow at small shear Reynolds number. Using direct numerical stability analysis of the coupled nonlinear particle-flow problem, we compute the linear stability of the log-rolling orbit at small shear Reynolds number Rea. As Rea→0 and as the box size of the system tends to infinity, we find good agreement between the numerical results and earlier analytical predictions valid to linear order in Rea for the case of an unbounded shear. The numerical stability analysis indicates that there are substantial finite-size corrections to the analytical results obtained for the unbounded system. We also compare the analytical results to results of lattice Boltzmann simulations to analyze the stability of the tumbling orbit at shear Reynolds numbers of order unity. Theory for an unbounded system at infinitesimal shear Reynolds number predicts a bifurcation of the tumbling orbit at aspect ratio λc≈0.137 below which tumbling is stable (as well as log rolling). The simulation results show a bifurcation line in the λ -Rea plane that reaches λ ≈0.1275 at the smallest shear Reynolds number (Rea=1 ) at which we could simulate with the lattice Boltzmann code, in qualitative agreement with the analytical results.
Relativistic magnetohydrodynamics in one dimension.
Lyutikov, Maxim; Hadden, Samuel
2012-02-01
We derive a number of solutions for one-dimensional dynamics of relativistic magnetized plasma that can be used as benchmark estimates in relativistic hydrodynamic and magnetohydrodynamic numerical codes. First, we analyze the properties of simple waves of fast modes propagating orthogonally to the magnetic field in relativistically hot plasma. The magnetic and kinetic pressures obey different equations of state, so that the system behaves as a mixture of gases with different polytropic indices. We find the self-similar solutions for the expansion of hot strongly magnetized plasma into vacuum. Second, we derive linear hodograph and Darboux equations for the relativistic Khalatnikov potential, which describe arbitrary one-dimensional isentropic relativistic motion of cold magnetized plasma and find their general and particular solutions. The obtained hodograph and Darboux equations are very powerful: A system of highly nonlinear, relativistic, time-dependent equations describing arbitrary (not necessarily self-similar) dynamics of highly magnetized plasma reduces to a single linear differential equation.
Rosen, T; Nordmark, A; Aidun, C K; Lundell, F; Mehlig, B
2015-01-01
We numerically analyse the rotation of a neutrally buoyant spheroid in a shear flow at small shear Reynolds number. Using direct numerical stability analysis of the coupled nonlinear particle-flow problem we compute the linear stability of the log-rolling orbit at small shear Reynolds number, ${\\rm Re}_a$. As ${\\rm Re}_a \\to 0$ and as the box size of the system tends to infinity we find good agreement between the numerical results and earlier analytical predictions valid to linear order in ${\\rm Re}_a$ for the case of an unbounded shear. The numerical stability analysis indicates that there are corrections to the analytical result of order ${\\rm Re}_a^{3/2}$. We also compare the analytical results to results of lattice-Boltzmann simulations to analyse the stability of the tumbling orbit at shear Reynolds numbers of order unity. Theory for an unbounded system at infinitesimal shear Reynolds number predicts a bifurcation of the tumbling orbit at aspect ratio $\\lambda_{\\rm c} \\approx 0.137$ below which tumbling ...
Demianski, Marek
2013-01-01
Relativistic Astrophysics brings together important astronomical discoveries and the significant achievements, as well as the difficulties in the field of relativistic astrophysics. This book is divided into 10 chapters that tackle some aspects of the field, including the gravitational field, stellar equilibrium, black holes, and cosmology. The opening chapters introduce the theories to delineate gravitational field and the elements of relativistic thermodynamics and hydrodynamics. The succeeding chapters deal with the gravitational fields in matter; stellar equilibrium and general relativity
Formation of dynamical structures in relativistic jets: the FRI case
Rossi, P; Bodo, G; Massaglia, S; Ferrari, A
2008-01-01
Strong observational evidence indicates that all extragalactic jets associated with AGNs move at relativistic speed up to 100 pc - 1 kpc scales from the nucleus. At larger distances, reflecting the Fanaroff-Riley radio source classification, we observe an abrupt deceleration in FR-I jets while relativistic motions persist up to Mpc scale in FR-II. Moreover, VLBI observations of some object like B2 1144+35, Mrk501 and M87 show limb brightening of the jet radio emission at the parsec scale. This effect is interpreted kinematically as due to the presence of a deboosted central spine at high Lorentz factor and of a weakly relativistic external layer. In this paper we investigate whether these effects can be interpreted by a breaking of the collimated flow by external medium entrainment favored by shear instabilities, namely Kelvin-Helmholtz instabilities. We examine in details the physical conditions under which significant deceleration of a relativistic flow is produced. We investigate the phenomenon by means of...
Homminga, Jasper; Lehr, Anne M.; Meijer, Gerdine J. M.; Janssen, Michiel M. A.; Schlosser, Tom P. C.; Verkerke, Gijsbertus J.; Castelein, Rene M.
2013-01-01
Study Design. Finite element study. Objective. To analyze the effects of posterior shear loads, disc degeneration, and the combination of both on spinal torsion stiffness. Summary of Background Data. Scoliosis is a 3-dimensional deformity of the spine that presents itself mainly in adolescent girls
Homminga, J.J.; Lehr, A.M.; Meijer, G.J.M.; Janssen, M.M.A.; Schlösser, T.P.C.; Verkerke, G.J.; Castelein, R.M.
2013-01-01
Objective. To analyze the effects of posterior shear loads, disc degeneration, and the combination of both on spinal torsion stiffness. Summary of Background Data. Scoliosis is a 3-dimensional deformity of the spine that presents itself mainly in adolescent girls and elderly patients. Our concept o
Classical simulation of relativistic Zitterbewegung in photonic lattices.
Dreisow, Felix; Heinrich, Matthias; Keil, Robert; Tünnermann, Andreas; Nolte, Stefan; Longhi, Stefano; Szameit, Alexander
2010-10-01
We present the first experimental realization of an optical analog for relativistic quantum mechanics by simulating the Zitterbewegung (trembling motion) of a free Dirac electron in an optical superlattice. Our photonic setting enables a direct visualization of Zitterbewegung as a spatial oscillatory motion of an optical beam. Direct measurements of the wave packet expectation values in superlattices with tuned miniband gaps clearly show the transition from weak-relativistic to relativistic and far-relativistic regimes.
Ditlevsen, Ove Dalager; Lazarov, Boyan Stefanov
2003-01-01
frame. A suitable number of the lower floors has been considered to represent the soil both as a filter of a white noise base rock excitation and as a simplified model for soil structure interaction. In the present paper the Slepian model is applied to obtain plastic displacement distributions...... frame with partial or full feed back from the movement of the top mass to the second and the first mass (top soil layer mass and base rock mass, respectively). Keywords: Clough-Penzien filtered white noise excitation, elasto-plastic shear frame oscillator, plastic displacement distributions, simplified...
Ion motion in the current sheet with sheared magnetic field – Part 1: Quasi-adiabatic theory
A. V. Artemyev
2013-02-01
Full Text Available We present a theory of trapped ion motion in the magnetotail current sheet with a constant dawn–dusk component of the magnetic field. Particle trajectories are described analytically using the quasi-adiabatic invariant corresponding to averaging of fast oscillations around the tangential component of the magnetic field. We consider particle dynamics in the quasi-adiabatic approximation and demonstrate that the principal role is played by large (so called geometrical jumps of the quasi-adiabatic invariant. These jumps appear due to the current sheet asymmetry related to the presence of the dawn–dusk magnetic field. The analytical description is compared with results of numerical integration. We show that there are four possible regimes of particle motion. Each regime is characterized by certain ranges of values of the dawn–dusk magnetic field and particle energy. We find the critical value of the dawn–dusk magnetic field, where jumps of the quasi-adiabatic invariant vanish.
Stephenson, William J.; Odum, Jackson K.; McNamara, Daniel E.; Williams, Robert A.; Angster, Stephen J
2014-01-01
We characterize shear-wave velocity versus depth (Vs profile) at 16 portable seismograph sites through the epicentral region of the 2011 Mw 5.8 Mineral (Virginia, USA) earthquake to investigate ground-motion site effects in the area. We used a multimethod acquisition and analysis approach, where active-source horizontal shear (SH) wave reflection and refraction as well as active-source multichannel analysis of surface waves (MASW) and passive-source refraction microtremor (ReMi) Rayleigh wave dispersion were interpreted separately. The time-averaged shear-wave velocity to a depth of 30 m (Vs30), interpreted bedrock depth, and site resonant frequency were estimated from the best-fit Vs profile of each method at each location for analysis. Using the median Vs30 value (270–715 m/s) as representative of a given site, we estimate that all 16 sites are National Earthquake Hazards Reduction Program (NEHRP) site class C or D. Based on a comparison of simplified mapped surface geology to median Vs30 at our sites, we do not see clear evidence for using surface geologic units as a proxy for Vs30 in the epicentral region, although this may primarily be because the units are similar in age (Paleozoic) and may have similar bulk seismic properties. We compare resonant frequencies calculated from ambient noise horizontal:vertical spectral ratios (HVSR) at available sites to predicted site frequencies (generally between 1.9 and 7.6 Hz) derived from the median bedrock depth and average Vs to bedrock. Robust linear regression of HVSR to both site frequency and Vs30 demonstrate moderate correlation to each, and thus both appear to be generally representative of site response in this region. Based on Kendall tau rank correlation testing, we find that Vs30 and the site frequency calculated from average Vs to median interpreted bedrock depth can both be considered reliable predictors of weak-motion site effects in the epicentral region.
Relativistic impulse dynamics.
Swanson, Stanley M
2011-08-01
Classical electrodynamics has some annoying rough edges. The self-energy of charges is infinite without a cutoff. The calculation of relativistic trajectories is difficult because of retardation and an average radiation reaction term. By reconceptuallizing electrodynamics in terms of exchanges of impulses rather than describing it by forces and potentials, we eliminate these problems. A fully relativistic theory using photonlike null impulses is developed. Numerical calculations for a two-body, one-impulse-in-transit model are discussed. A simple relationship between center-of-mass scattering angle and angular momentum was found. It reproduces the Rutherford cross section at low velocities and agrees with the leading term of relativistic distinguishable-particle quantum cross sections (Møller, Mott) when the distance of closest approach is larger than the Compton wavelength of the particle. Magnetism emerges as a consequence of viewing retarded and advanced interactions from the vantage point of an instantaneous radius vector. Radiation reaction becomes the local conservation of energy-momentum between the radiating particle and the emitted impulse. A net action is defined that could be used in developing quantum dynamics without potentials. A reinterpretation of Newton's laws extends them to relativistic motion.
Relativistic suppression of wave packet spreading.
Su, Q; Smetanko, B; Grobe, R
1998-03-30
We investigate numerically the solution of Dirac equation and analytically the Klein-Gordon equation and discuss the relativistic motion of an electron wave packet in the presence of an intense static electric field. In contrast to the predictions of the (non-relativistic) Schroedinger theory, the spreading rate in the field's polarization direction as well as in the transverse directions is reduced.
Hansen, S; Schwartz, S
2006-02-08
A comprehensive study of mantle anisotropy along the Red Sea and across Saudi Arabia was performed by analyzing shear-wave splitting recorded by stations from three different seismic networks: the largest, most widely distributed array of stations examined across Saudi Arabia to date. Stations near the Gulf of Aqaba display fast orientations that are aligned parallel to the Dead Sea Transform Fault, most likely related to the strike-slip motion between Africa and Arabia. However, most of our observations across Saudi Arabia are statistically the same, showing a consistent pattern of north-south oriented fast directions with delay times averaging about 1.4 s. Fossilized anisotropy related to the Proterozoic assembly of the Arabian Shield may contribute to the pattern but is not sufficient to fully explain the observations. We feel that the uniform anisotropic signature across Saudi Arabia is best explained by a combination of plate and density driven flow in the asthenosphere. By combining the northeast oriented flow associated with absolute plate motion with the northwest oriented flow associated with the channelized Afar plume along the Red Sea, we obtain a north-south oriented resultant that matches our splitting observations and supports models of active rifting processes. This explains why the north-south orientation of the fast polarization direction is so pervasive across the vast Arabian Plate.
Special Relativistic Hydrodynamics with Gravitation
Hwang, Jai-chan; Noh, Hyerim
2016-12-01
Special relativistic hydrodynamics with weak gravity has hitherto been unknown in the literature. Whether such an asymmetric combination is possible has been unclear. Here, the hydrodynamic equations with Poisson-type gravity, considering fully relativistic velocity and pressure under the weak gravity and the action-at-a-distance limit, are consistently derived from Einstein’s theory of general relativity. An analysis is made in the maximal slicing, where the Poisson’s equation becomes much simpler than our previous study in the zero-shear gauge. Also presented is the hydrodynamic equations in the first post-Newtonian approximation, now under the general hypersurface condition. Our formulation includes the anisotropic stress.
Special relativistic hydrodynamics with gravitation
Hwang, Jai-chan
2016-01-01
The special relativistic hydrodynamics with weak gravity is hitherto unknown in the literature. Whether such an asymmetric combination is possible was unclear. Here, the hydrodynamic equations with Poisson-type gravity considering fully relativistic velocity and pressure under the weak gravity and the action-at-a-distance limit are consistently derived from Einstein's general relativity. Analysis is made in the maximal slicing where the Poisson's equation becomes much simpler than our previous study in the zero-shear gauge. Also presented is the hydrodynamic equations in the first post-Newtonian approximation, now under the {\\it general} hypersurface condition. Our formulation includes the anisotropic stress.
Black Sun: Ocular Invisibility of Relativistic Luminous Astrophysical Bodies
Lee, Jeffrey S
2015-01-01
The relativistic Doppler shifting of visible electromagnetic radiation to beyond the human ocular range reduces the incident radiance of the source. Consequently, luminous astrophysical bodies (LABs) can be rendered invisible with sufficient relativistic motion. This paper determines the proper distance as a function of relativistic velocity at which a luminous object attains ocular invisibility.
Luciano, Rezzolla
2013-01-01
Relativistic hydrodynamics is a very successful theoretical framework to describe the dynamics of matter from scales as small as those of colliding elementary particles, up to the largest scales in the universe. This book provides an up-to-date, lively, and approachable introduction to the mathematical formalism, numerical techniques, and applications of relativistic hydrodynamics. The topic is typically covered either by very formal or by very phenomenological books, but is instead presented here in a form that will be appreciated both by students and researchers in the field. The topics covered in the book are the results of work carried out over the last 40 years, which can be found in rather technical research articles with dissimilar notations and styles. The book is not just a collection of scattered information, but a well-organized description of relativistic hydrodynamics, from the basic principles of statistical kinetic theory, down to the technical aspects of numerical methods devised for the solut...
Shear Acceleration in Expanding Flows
Rieger, F M
2016-01-01
Shear flows are naturally expected to occur in astrophysical environments and potential sites of continuous non-thermal Fermi-type particle acceleration. Here we investigate the efficiency of expanding relativistic outflows to facilitate the acceleration of energetic charged particles to higher energies. To this end, the gradual shear acceleration coefficient is derived based on an analytical treatment. The results are applied to the context of the relativistic jets of active galactic nuclei. The inferred acceleration timescale is investigated for a variety of conical flow profiles (i.e., power law, Gaussian, Fermi-Dirac) and compared to the relevant radiative and non-radiative loss timescales. The results exemplify that relativistic shear flows are capable of boosting cosmic-rays to extreme energies. Efficient electron acceleration, on the other hand, requires weak magnetic fields and may thus be accompanied by a delayed onset of particle energization and affect the overall jet appearance (e.g., core, ridge ...
Evidence of Solar Flare Triggering due to Loop-Loop Interaction Caused by Footpoint Shear-Motion
Kumar, Pankaj; Somov, B V; Manoharan, P K; Erdelyi, R; Uddin, Wahab
2010-01-01
We analyze multi-wavelength data of a M7.9/1N class solar flare which occurred on 27 April, 2006 from AR NOAA 10875. GOES soft X-ray images provide the most likely signature of two interacting loops and their reconnection, which triggers the solar flare. TRACE 195 A images also reveal the loop-loop interaction and the formation of `X' points with converging motion (~30 km/s) at the reconnection site in-between this interacting loop system. This provides the evidence of progressive reconnection and flare maximization at the interaction site in the active region. The absence of type III radio burst during this time period indicates no opening of magnetic field lines during the flare energy release, which implies only the change of field lines connectivity/orientation during the loop-loop interaction and reconnection process. The Ondrejov dynamic radio spectrum shows an intense decimetric (DCIM) radio burst (2.5--4.5 GHz, duration ~3 min) during flare initiation, which reveals the signature of particle accelerat...
Haba, Z
2009-02-01
We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.
Sahoo, Raghunath
2016-01-01
This lecture note covers Relativistic Kinematics, which is very useful for the beginners in the field of high-energy physics. A very practical approach has been taken, which answers "why and how" of the kinematics useful for students working in the related areas.
New Developments in Relativistic Viscous Hydrodynamics
Romatschke, Paul
2009-01-01
Starting with a brief introduction into the basics of relativistic fluid dynamics, I discuss our current knowledge of a relativistic theory of fluid dynamics in the presence of (mostly shear) viscosity. Derivations based on the generalized second law of thermodynamics, kinetic theory, and a complete second-order gradient expansion are reviewed. The resulting fluid dynamic equations are shown to be consistent for all these derivations, when properly accounting for the respective region of appl...
Transverse relativistic effects in paraxial wave interference
Bliokh, Konstantin Y; Nori, Franco
2013-01-01
We consider relativistic deformations of interfering paraxial waves moving in the transverse direction. Owing to superluminal transverse phase velocities, noticeable deformations of the interference patterns arise when the waves move with respect to each other with non-relativistic velocities. Similar distortions also appear on a mutual tilt of the interfering waves, which causes a phase delay analogous to the relativistic time delay. We illustrate these observations by the interference between a vortex wave beam and a plane wave, which exhibits a pronounced deformation of the radial fringes into a fork-like pattern (relativistic Hall effect). Furthermore, we describe an additional relativistic motion of the interference fringes (a counter-rotation in the vortex case), which become noticeable at the same non-relativistic velocities.
Relativistic gas in a Schwarzschild metric
Kremer, Gilberto M
2013-01-01
A relativistic gas in a Schwarzschild metric is studied within the framework of a relativistic Boltzmann equation in the presence of gravitational fields, where Marle's model for the collision operator of the Boltzmann equation is employed. The transport coefficients of bulk and shear viscosities and thermal conductivity are determined from the Chapman-Enskog method. It is shown that the transport coefficients depend on the gravitational potential. Expressions for the transport coefficients in the presence of weak gravitational fields in the non-relativistic (low temperatures) and ultra-relativistic (high temperatures) limiting cases are given. Apart from the temperature gradient the heat flux has two relativistic terms. The first one, proposed by Eckart, is due to the inertia of energy and represents an isothermal heat flux when matter is accelerated. The other, suggested by Tolman, is proportional to the gravitational potential gradient and indicates that -- in the absence of an acceleration field -- a stat...
Dixon, Timothy; Farina, Fred; DeMets, Charles; Suarez-Vidal, Francisco; Fletcher, John; Marquez-Azua, Bertha; Miller, Meghan; Sanchez, Osvaldo; Umhoefer, Paul
2000-12-01
We use new models for present-day Pacific-North America motion to evaluate the tectonics of offshore regions west of the Californias. Vandenburg in coastal Alta California moves at the Pacific plate velocity within uncertainties (˜1 mm/yr) after correcting for strain accumulation on the San Andreas and San Gregorio-Hosgri faults with a model that includes a viscoelastic lower crust. Modeled and measured velocities at coastal sites in Baja California south of the Agua Blanca fault, a region that most previous models consider Pacific plate, differ by 3-8 mm/yr, with coastal sites moving slower that the Pacific plate. We interpret these discrepancies in terms of strain accumulation on known on-shore faults, combined with right lateral slip at a rate of 3-4 mm/yr on additional faults offshore peninsular Baja California in the Pacific. Offshore seismicity, offset Quaternary features along the west coast of Baja California, and a discrepancy between the magnetically determined spreading rate in the Gulf Rise and the total plate rate from a geological model provide independent evidence for a “Baja California shear zone.”
Parker, Edward
2017-08-01
A nonrelativistic particle released from rest at the edge of a ball of uniform charge density or mass density oscillates with simple harmonic motion. We consider the relativistic generalizations of these situations where the particle can attain speeds arbitrarily close to the speed of light; generalizing the electrostatic and gravitational cases requires special and general relativity, respectively. We find exact closed-form relations between the position, proper time, and coordinate time in both cases, and find that they are no longer harmonic, with oscillation periods that depend on the amplitude. In the highly relativistic limit of both cases, the particle spends almost all of its proper time near the turning points, but almost all of the coordinate time moving through the bulk of the ball. Buchdahl's theorem imposes nontrivial constraints on the general-relativistic case, as a ball of given density can only attain a finite maximum radius before collapsing into a black hole. This article is intended to be pedagogical, and should be accessible to those who have taken an undergraduate course in general relativity.
Frontiers in relativistic celestial mechanics
2014-01-01
Relativistic celestial mechanics – investigating the motion celestial bodies under the influence of general relativity – is a major tool of modern experimental gravitational physics. With a wide range of prominent authors from the field, this two-volume series consists of reviews on a multitude of advanced topics in the area of relativistic celestial mechanics – starting from more classical topics such as the regime of asymptotically-flat spacetime, light propagation and celestial ephemerides, but also including its role in cosmology and alternative theories of gravity as well as modern experiments in this area.
Hakim, Rémi
1994-01-01
Il existe à l'heure actuelle un certain nombre de théories relativistes de la gravitation compatibles avec l'expérience et l'observation. Toutefois, la relativité générale d'Einstein fut historiquement la première à fournir des résultats théoriques corrects en accord précis avec les faits.
Jones, Bernard J. T.; Markovic, Dragoljub
1997-06-01
Preface; Prologue: Conference overview Bernard Carr; Part I. The Universe At Large and Very Large Redshifts: 2. The size and age of the Universe Gustav A. Tammann; 3. Active galaxies at large redshifts Malcolm S. Longair; 4. Observational cosmology with the cosmic microwave background George F. Smoot; 5. Future prospects in measuring the CMB power spectrum Philip M. Lubin; 6. Inflationary cosmology Michael S. Turner; 7. The signature of the Universe Bernard J. T. Jones; 8. Theory of large-scale structure Sergei F. Shandarin; 9. The origin of matter in the universe Lev A. Kofman; 10. New guises for cold-dark matter suspects Edward W. Kolb; Part II. Physics and Astrophysics Of Relativistic Compact Objects: 11. On the unification of gravitational and inertial forces Donald Lynden-Bell; 12. Internal structure of astrophysical black holes Werner Israel; 13. Black hole entropy: external facade and internal reality Valery Frolov; 14. Accretion disks around black holes Marek A. Abramowicz; 15. Black hole X-ray transients J. Craig Wheeler; 16. X-rays and gamma rays from active galactic nuclei Roland Svensson; 17. Gamma-ray bursts: a challenge to relativistic astrophysics Martin Rees; 18. Probing black holes and other exotic objects with gravitational waves Kip Thorne; Epilogue: the past and future of relativistic astrophysics Igor D. Novikov; I. D. Novikov's scientific papers and books.
Schulz, William H.; Wang, Gonghui
2014-01-01
Most large seismogenic landslides are reactivations of preexisting landslides with basal shear zones in the residual strength condition. Residual shear strength often varies during rapid displacement, but the response of residual shear zones to seismic loading is largely unknown. We used a ring shear apparatus to perform simulated seismic loading tests, constant displacement rate tests, and tests during which shear stress was gradually varied on specimens from two landslides to improve understanding of coseismic landslide reactivation and to identify shear strength models valid for slow gravitational failure through rapid coseismic failure. The landslides we studied represent many along the Oregon, U.S., coast. Seismic loading tests resulted in (1) catastrophic failure involving unbounded displacement when stresses represented those for the existing landslides and (2) limited to unbounded displacement when stresses represented those for hypothetical dormant landslides, suggesting that coseismic landslide reactivation may be significant during future great earthquakes occurring near the Oregon Coast. Constant displacement rate tests indicated that shear strength decreased exponentially during the first few decimeters of displacement but increased logarithmically with increasing displacement rate when sheared at 0.001 cm s−1 or greater. Dynamic shear resistance estimated from shear strength models correlated well with stresses observed during seismic loading tests, indicating that displacement rate and amount primarily controlled failure characteristics. We developed a stress-based approach to estimate coseismic landslide displacement that utilizes the variable shear strength model. The approach produced results that compared favorably to observations made during seismic loading tests, indicating its utility for application to landslides.
Relativistic magnetohydrodynamics
Hernandez, Juan; Kovtun, Pavel
2017-05-01
We present the equations of relativistic hydrodynamics coupled to dynamical electromagnetic fields, including the effects of polarization, electric fields, and the derivative expansion. We enumerate the transport coefficients at leading order in derivatives, including electrical conductivities, viscosities, and thermodynamic coefficients. We find the constraints on transport coefficients due to the positivity of entropy production, and derive the corresponding Kubo formulas. For the neutral state in a magnetic field, small fluctuations include Alfvén waves, magnetosonic waves, and the dissipative modes. For the state with a non-zero dynamical charge density in a magnetic field, plasma oscillations gap out all propagating modes, except for Alfvén-like waves with a quadratic dispersion relation. We relate the transport coefficients in the "conventional" magnetohydrodynamics (formulated using Maxwell's equations in matter) to those in the "dual" version of magnetohydrodynamics (formulated using the conserved magnetic flux).
Leardini, Fabrice
2013-01-01
This manuscript presents a problem on special relativity theory (SRT) which embodies an apparent paradox relying on the concept of simultaneity. The problem is represented in the framework of Greek epic poetry and structured in a didactic way. Owing to the characteristic properties of Lorenz transformations, three events which are simultaneous in a given inertial reference system, occur at different times in the other two reference frames. In contrast to the famous twin paradox, in the present case there are three, not two, different inertial observers. This feature provides a better framework to expose some of the main characteristics of SRT, in particular, the concept of velocity and the relativistic rule of addition of velocities.
Kayen, Robert; Scasserra, Giuseppe; Stewart, Jonathan P.; Lanzo, Giuseppe
2008-01-01
A long sequence of earthquakes, eight with magnitudes between 5 and 6, struck the Umbria and Marche regions of central Italy between September 26, 1997 and July 1998. The earthquake swarm caused severe structural damage, particularly to masonry buildings, and resulted in the loss of twelve lives and about 150 injuries. The source of the events was a single seismogenic structure that consists of several faults with a prevailing northwest-southeast strike and crosses the Umbria-Marche border. The focal mechanism of the largest shocks indicates that the events were the product of shallow extensional normal faulting along a NE-SW extension perpendicular to the trend of the Apennines. The network of analog seismometer stations in the Umbria and Marche regions recorded motions of the main September and October 1997 events and a dense array of mobile digital stations, installed since September 29, recorded most of the swarm. The permanent national network Rete Accelerometrica Nazionale (RAN) is administered and maintained by Dipartimento delle Protezione Civile (DPC: Civil Protection Department); the temporary array was managed by Servizio Sismico Nazionale (SSN) in cooperation with small agencies and Universities. ENEA, the operator of many seismometer stations in Umbria, is the public Italian National Agency for New Technologies, Energy and the Environment. Many of the temporary and permanent stations in the Italian seismic network have little or no characterization of seismic velocities. In this study, we investigated 17 Italian sites using an active-source approach that employs low frequency harmonic waves to measure the dispersive nature of surface waves in the ground. We used the Spectral Analysis of Surface Wave (SASW) approach, coupled with an array of harmonic-wave electro-mechanical sources that are driven in-phase to excite the ground. An inversion algorithm using a non-linear least-squares best-fit method is used to compute shear wave velocities for up to 100
Isotropic Forms of Dynamics in the Relativistic Direct Interaction Theory
Duviryak, A A; Tretyak, V I
1998-01-01
The Lagrangian relativistic direct interaction theory in the various forms of dynamics is formulated and its connections with the Fokker-type action theory and with the constrained Hamiltonian mechanics are established. The motion of classical two-particle system with relativistic direct interaction is analysed within the framework of isotropic forms of dynamics in the two- and four-dimensional space-time. Some relativistic exactly solvable quantum-mechanical models are also discussed.
Relativistic quantum information
Mann, R. B.; Ralph, T. C.
2012-11-01
Over the past few years, a new field of high research intensity has emerged that blends together concepts from gravitational physics and quantum computing. Known as relativistic quantum information, or RQI, the field aims to understand the relationship between special and general relativity and quantum information. Since the original discoveries of Hawking radiation and the Unruh effect, it has been known that incorporating the concepts of quantum theory into relativistic settings can produce new and surprising effects. However it is only in recent years that it has become appreciated that the basic concepts involved in quantum information science undergo significant revision in relativistic settings, and that new phenomena arise when quantum entanglement is combined with relativity. A number of examples illustrate that point. Quantum teleportation fidelity is affected between observers in uniform relative acceleration. Entanglement is an observer-dependent property that is degraded from the perspective of accelerated observers moving in flat spacetime. Entanglement can also be extracted from the vacuum of relativistic quantum field theories, and used to distinguish peculiar motion from cosmological expansion. The new quantum information-theoretic framework of quantum channels in terms of completely positive maps and operator algebras now provides powerful tools for studying matters of causality and information flow in quantum field theory in curved spacetimes. This focus issue provides a sample of the state of the art in research in RQI. Some of the articles in this issue review the subject while others provide interesting new results that will stimulate further research. What makes the subject all the more exciting is that it is beginning to enter the stage at which actual experiments can be contemplated, and some of the articles appearing in this issue discuss some of these exciting new developments. The subject of RQI pulls together concepts and ideas from
Cao, Zhanli; Li, Zhendong; Wang, Fan; Liu, Wenjian
2017-02-01
The spin-separated exact two-component (X2C) relativistic Hamiltonian [sf-X2C+so-DKHn, J. Chem. Phys., 2012, 137, 154114] is combined with the equation-of-motion coupled-cluster method with singles and doubles (EOM-CCSD) for the treatment of spin-orbit splittings of open-shell molecular systems. Scalar relativistic effects are treated to infinite order from the outset via the spin-free part of the X2C Hamiltonian (sf-X2C), whereas the spin-orbit couplings (SOC) are handled at the CC level via the first-order Douglas-Kroll-Hess (DKH) type of spin-orbit operator (so-DKH1). Since the exponential of single excitations, i.e., exp(T1), introduces sufficient spin orbital relaxations, the inclusion of SOC at the CC level is essentially the same in accuracy as the inclusion of SOC from the outset in terms of the two-component spinors determined variationally by the sf-X2C+so-DKH1 Hamiltonian, but is computationally more efficient. Therefore, such an approach (denoted as sf-X2C-EOM-CCSD(SOC)) can achieve uniform accuracy for the spin-orbit splittings of both light and heavy elements. For light elements, the treatment of SOC can even be postponed until the EOM step (denoted as sf-X2C-EOM(SOC)-CCSD), so as to further reduce the computational cost. To reveal the efficacy of sf-X2C-EOM-CCSD(SOC) and sf-X2C-EOM(SOC)-CCSD, the spin-orbit splittings of the (2)Π states of monohydrides up to the sixth row of the periodic table are investigated. The results show that sf-X2C-EOM-CCSD(SOC) predicts very accurate results (within 5%) for elements up to the fifth row, whereas sf-X2C-EOM(SOC)-CCSD is useful only for light elements (up to the third row but with some exceptions). For comparison, the sf-X2C-S-TD-DFT-SOC approach [spin-adapted open-shell time-dependent density functional theory, Mol. Phys., 2013, 111, 3741] is applied to the same systems. The overall accuracy (1-10%) is satisfactory.
Relativistic top in the Ostrohrads'kyj dynamics
Matsyuk, Roman
2015-01-01
A variational equation of the fourth order for the free relativistic top is developed starting from the Dixon's system of equations for the motion of the relativistic dipole. The obtained equation is then cast into the homogeneous space-time Hamiltonian form.
Clumps in large scale relativistic jets
Tavecchio, F; Celotti, A
2003-01-01
The relatively intense X-ray emission from large scale (tens to hundreds kpc) jets discovered with Chandra likely implies that jets (at least in powerful quasars) are still relativistic at that distances from the active nucleus. In this case the emission is due to Compton scattering off seed photons provided by the Cosmic Microwave Background, and this on one hand permits to have magnetic fields close to equipartition with the emitting particles, and on the other hand minimizes the requirements about the total power carried by the jet. The emission comes from compact (kpc scale) knots, and we here investigate what we can predict about the possible emission between the bright knots. This is motivated by the fact that bulk relativistic motion makes Compton scattering off the CMB photons efficient even when electrons are cold or mildly relativistic in the comoving frame. This implies relatively long cooling times, dominated by adiabatic losses. Therefore the relativistically moving plasma can emit, by Compton sc...
Relabeling symmetry in relativistic fluids and plasmas
Kawazura, Yohei; Fukumoto, Yasuhide
2014-01-01
The conservation of the recently formulated relativistic canonical helicity [Yoshida Z, Kawazura Y, and Yokoyama T 2014 J. Math. Phys. 55 043101] is derived from Noether's theorem by constructing an action principle on the relativistic Lagrangian coordinates (we obtain general cross helicities that include the helicity of the canonical vorticity). The conservation law is, then, explained by the relabeling symmetry pertinent to the Lagrangian label of fluid elements. Upon Eulerianizing the Noether current, the purely spatial volume integral on the Lagrangian coordinates is mapped to a space-time mixed three-dimensional integral on the four-dimensional Eulerian coordinates. The relativistic conservation law in the Eulerian coordinates is no longer represented by any divergence-free current; hence, it is not adequate to regard the relativistic helicity (represented by the Eulerian variables) as a Noether charge, and this stands the reason why the "conventional helicity" is no longer a constant of motion. We have...
A RELATIVISTIC QUASI-STATIC MODEL FOR ELECTRONS IN INTENSE LASER FIELDS
CHEN BAO-ZHEN
2001-01-01
A relativistic quasi-static model for the motion of the electrons in relativistic laser fields is proposed. Using the model, the recent experimental results about the generation of the hot electrons in relativistic laser fields can be fit quite well and the important role of the rescattering can be shown clearly.
Volatility smile as relativistic effect
Kakushadze, Zura
2017-06-01
We give an explicit formula for the probability distribution based on a relativistic extension of Brownian motion. The distribution (1) is properly normalized and (2) obeys the tower law (semigroup property), so we can construct martingales and self-financing hedging strategies and price claims (options). This model is a 1-constant-parameter extension of the Black-Scholes-Merton model. The new parameter is the analog of the speed of light in Special Relativity. However, in the financial context there is no ;speed limit; and the new parameter has the meaning of a characteristic diffusion speed at which relativistic effects become important and lead to a much softer asymptotic behavior, i.e., fat tails, giving rise to volatility smiles. We argue that a nonlocal stochastic description of such (Lévy) processes is inadequate and discuss a local description from physics. The presentation is intended to be pedagogical.
Double Relativistic Electron Accelerating Mirror
Saltanat Sadykova
2013-02-01
Full Text Available In the present paper, the possibility of generation of thin dense relativistic electron layers is shown using the analytical and numerical modeling of laser pulse interaction with ultra-thin layers. It was shown that the maximum electron energy can be gained by optimal tuning between the target width, intensity and laser pulse duration. The optimal parameters were obtained from a self-consistent system of Maxwell equations and the equation of motion of electron layer. For thin relativistic electron layers, the gaining of maximum electron energies requires a second additional overdense plasma layer, thus cutting the laser radiation off the plasma screen at the instant of gaining the maximum energy (DREAM-schema.
General relativistic observables for the ACES experiment
Turyshev, Slava G; Toth, Viktor T
2015-01-01
We develop a high-precision model for relativistic observables of the Atomic Clock Ensemble in Space (ACES) experiment on the International Space Station (ISS). We develop all relativistic coordinate transformations that are needed to describe the motion of ACES in Earth orbit and to compute observable quantities. We analyze the accuracy of the required model as it applies to the proper-to-coordinate time transformations, light time equation, and spacecraft equations of motion. We consider various sources of nongravitational noise and their effects on ACES. We estimate the accuracy of orbit reconstruction that is needed to satisfy the ACES science objectives. Based on our analysis, we derive models for the relativistic observables of ACES, which also account for the contribution of atmospheric drag on the clock rate. We include the Earth's oblateness coefficient $J_2$ and the effects of major nongravitational forces on the orbit of the ISS. We demonstrate that the ACES reference frame is pseudo-inertial at th...
Cattaneo, Carlo
2011-01-01
This title includes: Pham Mau Quam: Problemes mathematiques en hydrodynamique relativiste; A. Lichnerowicz: Ondes de choc, ondes infinitesimales et rayons en hydrodynamique et magnetohydrodynamique relativistes; A.H. Taub: Variational principles in general relativity; J. Ehlers: General relativistic kinetic theory of gases; K. Marathe: Abstract Minkowski spaces as fibre bundles; and, G. Boillat: Sur la propagation de la chaleur en relativite.
Relativistic Stern-Gerlach Deflection: Hamiltonian Formulation
Mane, S R
2016-01-01
A Hamiltonian formalism is employed to elucidate the effects of the Stern-Gerlach force on beams of relativistic spin-polarized particles, for passage through a localized region with a static magnetic or electric field gradient. The problem of the spin-orbit coupling for nonrelativistic bounded motion in a central potential (hydrogen-like atoms, in particular) is also briefly studied.
Relativistic radiative transfer in relativistic spherical flows
Fukue, Jun
2017-02-01
Relativistic radiative transfer in relativistic spherical flows is numerically examined under the fully special relativistic treatment. We first derive relativistic formal solutions for the relativistic radiative transfer equation in relativistic spherical flows. We then iteratively solve the relativistic radiative transfer equation, using an impact parameter method/tangent ray method, and obtain specific intensities in the inertial and comoving frames, as well as moment quantities, and the Eddington factor. We consider several cases; a scattering wind with a luminous central core, an isothermal wind without a core, a scattering accretion on to a luminous core, and an adiabatic accretion on to a dark core. In the typical wind case with a luminous core, the emergent intensity is enhanced at the center due to the Doppler boost, while it reduces at the outskirts due to the transverse Doppler effect. In contrast to the plane-parallel case, the behavior of the Eddington factor is rather complicated in each case, since the Eddington factor depends on the optical depth, the flow velocity, and other parameters.
One-dimensional relativistic dissipative system with constant force and its quantization
López, G; Hernández, H; L\\'opez, Gustavo; L\\'opez, Xaman-Ek; Hern\\'andez, Hector
2005-01-01
For a relativistic particle under a constant force and a linear velocity dissipation force, a constant of motion is found. Problems are shown for getting the Hamiltoninan of this system. Thus, the quantization of this system is carried out through the constant of motion and using the quantization of the velocity variable. The dissipative relativistic quantum bouncer is outlined within this quantization approach.
One-Dimensional Relativistic Dissipative System with Constant Force and its Quantization
López, G.; López, X. E.; Hernández, H.
2006-04-01
For a relativistic particle under a constant force and a linear velocity dissipation force, a constant of motion is found. Problems are shown for getting the Hamiltonian of this system. Thus, the quantization of this system is carried out through the constant of motion and using the quantization on the velocity variable. The dissipative relativistic quantum bouncer is outlined within this quantization approach.
$\\Lambda$ polarization in peripheral collisions at moderate relativistic energies
Xie, Y L; Stöcker, H; Wang, D J; Csernai, L P
2016-01-01
The polarization of $\\Lambda$ hyperons from relativistic flow vorticity is studied in peripheral heavy ion reactions at FAIR and NICA energies, just above the threshold of the transition to the Quark-Gluon Plasma. Previous calculations at higher energies with larger initial angular momentum, predicted significant $\\Lambda$ polarization based on the classical vorticity term in the polarization, while relativistic modifications decreased the polarization and changed its structure in the momentum space. At the lower energies studied here, we see the same effect namely that the relativistic modifications decrease the polarization arising from the initial shear flow vorticity.
Relativistic Remnants of Non-Relativistic Electrons
Kashiwa, Taro
2015-01-01
Electrons obeying the Dirac equation are investigated under the non-relativistic $c \\mapsto \\infty$ limit. General solutions are given by derivatives of the relativistic invariant functions whose forms are different in the time- and the space-like region, yielding the delta function of $(ct)^2 - x^2$. This light-cone singularity does survive to show that the charge and the current density of electrons travel with the speed of light in spite of their massiveness.
Fermion confinement by a relativistic flux tube
Olsson, M G; Williams, K; Olsson, M G; Veseli, S; Williams, K
1996-01-01
We formulate the description of the dynamic confinement of a single fermion by a flux tube. The range of validity extends from the relativistic corrections of a slowly moving quark to the ultra-relativistic motion in a heavy-light meson. The reduced Salpeter equation, also known as the no-pair equation, provides the framework for our discussion. The Regge structure is that of a Nambu string with one end fixed. Numerical solutions are found giving very good fits to heavy-light meson masses. The Isgur-Wise function with a zero recoil slope of \\xi'(1)\\simeq -1.23 is obtained.
Relativistic Quantum Teleportation with superconducting circuits
Friis, Nicolai; Truong, Kevin; Sabín, Carlos; Solano, Enrique; Johansson, Göran; Fuentes, Ivette
2012-01-01
We study the effects of relativistic motion on quantum teleportation and propose a realizable experiment where our results can be tested. We compute bounds on the optimal fidelity of teleportation when one of the observers undergoes non-uniform motion for a finite time. The upper bound to the optimal fidelity is degraded due to the observer's motion however, we discuss how this degradation can be corrected. These effects are observable for experimental parameters that are within reach of cutting-edge superconducting technology.
A new exact solution of the relativistic Boltzmann equation and its hydrodynamic limit
Denicol, Gabriel S; Martinez, Mauricio; Noronha, Jorge; Strickland, Michael
2014-01-01
We present an exact solution of the relativistic Boltzmann equation for a system undergoing boost-invariant longitudinal and azimuthally symmetric transverse flow ("Gubser flow"). The resulting exact non-equilibrium dynamics is compared to 1st- and 2nd-order relativistic hydrodynamic approximations for various shear viscosity to entropy density ratios. This novel solution can be used to test the validity and accuracy of different hydrodynamic approximations in conditions similar to those generated in relativistic heavy-ion collisions.
Real vs. simulated relativistic jets
Gómez, J L; Agudo, I; Marscher, A P; Jorstad, S G; Aloy, M A
2005-01-01
Intensive VLBI monitoring programs of jets in AGN are showing the existence of intricate emission patterns, such as upstream motions or slow moving and quasi-stationary componentes trailing superluminal features. Relativistic hydrodynamic and emission simulations of jets are in very good agreement with these observations, proving as a powerful tool for the understanding of the physical processes taking place in the jets of AGN, microquasars and GRBs. These simulations show that the variability of the jet emission is the result of a complex combination of phase motions, viewing angle selection effects, and non-linear interactions between perturbations and the underlying jet and/or ambient medium. Both observations and simulations suggest that shock-in-jet models may be an overly simplistic idealization when interpreting the emission structure observed in actual jets.
Relativistic quantum mechanics
Wachter, Armin
2010-01-01
Which problems do arise within relativistic enhancements of the Schrödinger theory, especially if one adheres to the usual one-particle interpretation, and to what extent can these problems be overcome? And what is the physical necessity of quantum field theories? In many books, answers to these fundamental questions are given highly insufficiently by treating the relativistic quantum mechanical one-particle concept very superficially and instead introducing field quantization as soon as possible. By contrast, this monograph emphasizes relativistic quantum mechanics in the narrow sense: it extensively discusses relativistic one-particle concepts and reveals their problems and limitations, therefore motivating the necessity of quantized fields in a physically comprehensible way. The first chapters contain a detailed presentation and comparison of the Klein-Gordon and Dirac theory, always in view of the non-relativistic theory. In the third chapter, we consider relativistic scattering processes and develop the...
ZHANG Peng-Fei; RUAN Tu-Nan
2001-01-01
A systematic theory on the appropriate spin operators for the relativistic states is developed. For a massive relativistic particle with arbitrary nonzero spin, the spin operator should be replaced with the relativistic one, which is called in this paper as moving spin. Further the concept of moving spin is discussed in the quantum field theory. A new is constructed. It is shown that, in virtue of the two operators, problems in quantum field concerned spin can be neatly settled.
Relativistic Guiding Center Equations
White, R. B. [PPPL; Gobbin, M. [Euratom-ENEA Association
2014-10-01
In toroidal fusion devices it is relatively easy that electrons achieve relativistic velocities, so to simulate runaway electrons and other high energy phenomena a nonrelativistic guiding center formalism is not sufficient. Relativistic guiding center equations including flute mode time dependent field perturbations are derived. The same variables as used in a previous nonrelativistic guiding center code are adopted, so that a straightforward modifications of those equations can produce a relativistic version.
Relativistic Linear Restoring Force
Clark, D.; Franklin, J.; Mann, N.
2012-01-01
We consider two different forms for a relativistic version of a linear restoring force. The pair comes from taking Hooke's law to be the force appearing on the right-hand side of the relativistic expressions: d"p"/d"t" or d"p"/d["tau"]. Either formulation recovers Hooke's law in the non-relativistic limit. In addition to these two forces, we…
MALFLIET, R
1993-01-01
We discuss the present status of relativistic transport theory. Special emphasis is put on problems of topical interest: hadronic features, thermodynamical consistent approximations and spectral properties.
Predicting Mercury's Precession using Simple Relativistic Newtonian Dynamics
Friedman, Y
2016-01-01
We present a new simple relativistic model for planetary motion describing accurately the anomalous precession of the perihelion of Mercury and its origin. The model is based on transforming Newton's classical equation for planetary motion from absolute to real spacetime influenced by the gravitational potential and introducing the concept of influenced direction.
Gomez R, F
2004-07-01
In the chapter 1 we show the foundations of the special relativity in the frame of the classical mechanics and we develop the necessary theory for the theoretical description of the relativistic dynamics of charged particles in the interaction with electromagnetic fields. It will see that starting from the energy conservation principle is derived the Einstein's law that establishes the relationship among this and the mass. Later on, it will take the action of a charged particle in a given radiation field and in the one which only we will take two parts, the action of the free particle and the one that defines the interaction of this with the field. The equations of motion of a charge in an electromagnetic field come given by the Lagrange equations, being obtained an expression for the force, well-known as Lorentz force, which consists of two terms, the first of them is the force that the electric field E exercises on the particle; which doesn't depend on the charge speed and is oriented in the direction of the field, the second term represents the force that exercises the magnetic field B and that it is proportional to the charge speed, being perpendicular to the direction of it. In the chapter 2 an integration method of the Hamilton-Jacobi for the case of a pulse is that allows to found analytical forms for the moment, the energy and the charge position is developed with detail. We will present, also, a discussion of the classical theory of the relativistic dynamic of free electrons. They are also obtained, invariant quantities like the phase, before the frame of the reference inertial changes, well-known as Lorentz invariants of the system. In this part it is considered to the electron in the laboratory frame (frame in which the particle is initially in repose regarding the observer), of which the speed and the acceleration quadrivectors can be calculated. We demonstrate that the {eta} phase is a Lorentz invariant. It is shown, also that the proper time
A Lagrangian formulation of relativistic Israel-Stewart hydrodynamics
Torrieri, Giorgio
2016-01-01
We rederive relativistic hydrodynamics as a Lagrangian effective theory using the doubled coordinates technique, allowing us to include dissipative terms. We include Navier-Stokes shear and bulk terms, as well as Israel-Stewart relaxation time terms, within this formalism. We show how the inclusion of shear viscosity, and the requirement of a bounded energy-momentum "vacuum", forces the inclusion of the Israel-Stewart term into the theory, thereby providing a justification for the origin and uniqueness of these terms.
Lagrangian formulation of relativistic Israel-Stewart hydrodynamics
Montenegro, David; Torrieri, Giorgio
2016-09-01
We rederive relativistic hydrodynamics as a Lagrangian effective theory using the doubled coordinates technique, allowing us to include dissipative terms. We include Navier-Stokes shear and bulk terms, as well as Israel-Stewart relaxation time terms, within this formalism. We show how the inclusion of shear dissipation forces the inclusion of the Israel-Stewart term into the theory, thereby providing an additional justification for the form of this term.
Relativistic quantum mechanics; Mecanique quantique relativiste
Ollitrault, J.Y. [CEA Saclay, 91 - Gif-sur-Yvette (France). Service de Physique Theorique]|[Universite Pierre et Marie Curie, 75 - Paris (France)
1998-12-01
These notes form an introduction to relativistic quantum mechanics. The mathematical formalism has been reduced to the minimum in order to enable the reader to calculate elementary physical processes. The second quantification and the field theory are the logical followings of this course. The reader is expected to know analytical mechanics (Lagrangian and Hamiltonian), non-relativistic quantum mechanics and some basis of restricted relativity. The purpose of the first 3 chapters is to define the quantum mechanics framework for already known notions about rotation transformations, wave propagation and restricted theory of relativity. The next 3 chapters are devoted to the application of relativistic quantum mechanics to a particle with 0,1/5 and 1 spin value. The last chapter deals with the processes involving several particles, these processes require field theory framework to be thoroughly described. (A.C.) 2 refs.
Relativistic Hotspots in FR II Radio Sources
Chartrand, Alex M.; Miller, B. P.; Brandt, W. N.; Gawronski, M. P.; Cederbloom, S. E.
2011-01-01
We present a list of six FR II radio sources that are candidates to possess hotspots with modestly relativistic (v/c > 0.2) bulk velocities, in contrast to the vast majority of FR II radio sources that possess non-relativistic hotspot bulk velocities (e.g., v/c = 0.03+/- 0.02 from Scheuer 1995). These objects display arm- length and flux-ratio asymmetries between lobes that self-consistently indicate relativistic motion. The candidates are selected from the FIRST 1.4 GHz survey (including but not limited to the catalog of FR II quasars of de Vries et al. 2006) with the requirement that the radio core have a spectroscopic SDSS counterpart. We find no significant difference in the number of neighboring sources within 300 projected kpc of the candidate sources and randomly selected nearby regions. The deprojected and light travel-time corrected lobe distances are not abnormal for FR II sources, and neither are the core-to-lobe flux ratios after correcting for lobe beaming. We briefly consider four possibilities for these type of objects: (i) environmental interactions randomly mimicking relativistic effects, (ii) a restarted jet causing the near hotspot to brighten while the far hotspot still appears faint, (iii) observation during a short interval common to FR II lifetimes during which the hotspot decelerates from relativistic to non-relativistic velocities, and (iv) innately unusual characteristics (e.g., a mass-loaded jet) driving relativistic bulk velocities in the hotspots of a small fraction (< 1%) of FR II objects. We favor the last interpretation but cannot rule out the alternatives. We also comment on the useful external constraints such objects provide to the evaluation of hotspot X-ray emission mechanisms.
Towards relativistic quantum geometry
Ridao, Luis Santiago [Instituto de Investigaciones Físicas de Mar del Plata (IFIMAR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Mar del Plata (Argentina); Bellini, Mauricio, E-mail: mbellini@mdp.edu.ar [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, C.P. 7600, Mar del Plata (Argentina); Instituto de Investigaciones Físicas de Mar del Plata (IFIMAR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Mar del Plata (Argentina)
2015-12-17
We obtain a gauge-invariant relativistic quantum geometry by using a Weylian-like manifold with a geometric scalar field which provides a gauge-invariant relativistic quantum theory in which the algebra of the Weylian-like field depends on observers. An example for a Reissner–Nordström black-hole is studied.
Best-fit estimate of relativistic effects in time-delay experiments.
Richard, J.-P.
1972-01-01
Time-delay experiments are analyzed within the frame of a curved space-time. Residuals from Newtonian best fits of relativistic data are used as a measure of the 'relativistic effects.' Radial transponder trajectories are considered. If the motion is towards the sun, the relativistic residuals are of the order of 100 m. If the motion is away from the sun, they are at the 10-km level and the fraction due to the second-order curvature of the metric is at the 1-km level. Those effects are significantly smaller than those calculated from the divergence of the Newtonian and relativistic predictions after exact fit of the initial measurements.
General relativistic observables of the GRAIL mission
Turyshev, Slava G; Sazhin, Mikhail V
2012-01-01
We present a realization of astronomical relativistic reference frames in the solar system and its application to the GRAIL mission. We model the necessary spacetime coordinate transformations for light-trip time computations and address some practical aspects of the implementation of the resulting model. We develop all the relevant relativistic coordinate transformations that are needed to describe the motion of the GRAIL spacecraft and to compute all observable quantities. We take into account major relativistic effects contributing to the dual one-way range observable, which is derived from one-way signal travel times between the two GRAIL spacecraft. We develop a general relativistic model for this fundamental observable of GRAIL, accurate to 1 $\\mu$m. We develop and present a relativistic model for another key observable of this experiment, the dual one-way range-rate, accurate to 1 $\\mu$m/s. The presented formulation justifies the basic assumptions behind the design of the GRAIL mission. It may also be ...
Estakhr, Ahmad Reza
2016-10-01
DJ̲μ/Dτ =J̲ν ∂νU̲μ + ∂νT̲μν +Γαβμ J̲αU̲β ︷ Steady Component + ∂νRμν +Γαβμ Rαβ ︷ Perturbations EAMG equations are proper time-averaged equations of relativistic motion for fluid flow and used to describe Relativistic Turbulent Flows. The EAMG equations are used to describe Relativistic Jet.
R P Tiwari; V K Gahalaut; Ch U B Rao; C Lalsawta; B Kundu; Malsawmtluanga
2015-07-01
The motion between India and Sunda plates is accommodated along the Churachandpur Mao Fault (CMF) in the Indo-Burmese Wedge (IBW) and Sagaing Fault in the Myanmar region. Within the IBW, the Mat Fault is the most prominent transverse structure with prominent topographic and geomorphic expressions. We undertook Global Positioning System (GPS) measurements across this fault to investigate the current deformation across it. Modelling of these observations using locking depth of up to 4 km yields no resolvable slip (dextral slip rate as 0±5 mm/year) across the fault. Due to limited spatial extent of the GPS measurements, it is not possible to comment on the status of deeper slip, if any.
K-shell ionization in relativistic ion-atom collisions
Mehler, G.; Soff, G.; Rumrich, K.; Greiner, W.
1989-08-01
We present calculations of K-shell ionization probabilities in asymmetric ion-atom collisions at relativistic velocities of the projectile. The time-dependent Dirac equation is represented as a system of coupled differential equations. The transition probabilities are determined using the coordinate space method. This necessitates an extension of the angular momentum coupling compared with nonrelativistic collision systems. Effects of the relativistic projectile motion on the coupling matrix elements and their consequences on K-shell ionization are discussed. (orig.).
K-shell ionization in relativistic ion-atom collisions
Mehler, G.; Rumrich, K.; Greiner, W.; Soff, G.
1989-02-01
We present calculations of K-shell ionization probabilities in asymmetric ion-atom collisions at relativistic velocities of the projectile. The time-dependent Dirac equation is represented as a system of coupled differential equations. The transition probabilities are determined using the coordinate space method. This necessitates an extension of the angular momentum coupling compared with nonrelativistic collision systems. Effects of the relativistic projectile motion on the coupling matrix elements and their consequences on K-shell ionization are discussed.
Swinging of red blood cells under shear flow
Abkarian, M; Viallat, A; Abkarian, Manouk; Faivre, Magalie; Viallat, Annie
2007-01-01
We reveal that under moderate shear stress (of the order of 0.1 Pa) red blood cells present an oscillation of their inclination (swinging) superimposed to the long-observed steady tanktreading (TT) motion. A model based on a fluid ellipsoid surrounded by a visco-elastic membrane initially unstrained (shape memory) predicts all observed features of the motion: an increase of both swinging amplitude and period (1/2 the TT period) upon decreasing the shear stress, a shear stress-triggered transition towards a narrow shear stress-range intermittent regime of successive swinging and tumbling, and a pure tumbling motion at lower shear stress-values.
Hydrodynamics of ultra-relativistic bubble walls
Leonardo Leitao
2016-04-01
Full Text Available In cosmological first-order phase transitions, gravitational waves are generated by the collisions of bubble walls and by the bulk motions caused in the fluid. A sizeable signal may result from fast-moving walls. In this work we study the hydrodynamics associated to the fastest propagation modes, namely, ultra-relativistic detonations and runaway solutions. We compute the energy injected by the phase transition into the fluid and the energy which accumulates in the bubble walls. We provide analytic approximations and fits as functions of the net force acting on the wall, which can be readily evaluated for specific models. We also study the back-reaction of hydrodynamics on the wall motion, and we discuss the extrapolation of the friction force away from the ultra-relativistic limit. We use these results to estimate the gravitational wave signal from detonations and runaway walls.
Gomez R, F
2004-07-01
In the chapter 1 we show the foundations of the special relativity in the frame of the classical mechanics and we develop the necessary theory for the theoretical description of the relativistic dynamics of charged particles in the interaction with electromagnetic fields. It will see that starting from the energy conservation principle is derived the Einstein's law that establishes the relationship among this and the mass. Later on, it will take the action of a charged particle in a given radiation field and in the one which only we will take two parts, the action of the free particle and the one that defines the interaction of this with the field. The equations of motion of a charge in an electromagnetic field come given by the Lagrange equations, being obtained an expression for the force, well-known as Lorentz force, which consists of two terms, the first of them is the force that the electric field E exercises on the particle; which doesn't depend on the charge speed and is oriented in the direction of the field, the second term represents the force that exercises the magnetic field B and that it is proportional to the charge speed, being perpendicular to the direction of it. In the chapter 2 an integration method of the Hamilton-Jacobi for the case of a pulse is that allows to found analytical forms for the moment, the energy and the charge position is developed with detail. We will present, also, a discussion of the classical theory of the relativistic dynamic of free electrons. They are also obtained, invariant quantities like the phase, before the frame of the reference inertial changes, well-known as Lorentz invariants of the system. In this part it is considered to the electron in the laboratory frame (frame in which the particle is initially in repose regarding the observer), of which the speed and the acceleration quadrivectors can be calculated. We demonstrate that the {eta} phase is a Lorentz invariant. It is shown, also that the proper time
Kinematics of a relativistic particle with de Sitter momentum space
Arzano, Michele [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, Leuvenlaan 4, Utrecht 3584 TD (Netherlands); Kowalski-Glikman, Jerzy, E-mail: marzano@uu.nl, E-mail: jkowalskiglikman@ift.uni.wroc.pl [Institute for Theoretical Physics, University of Wroclaw, Pl. Maxa Borna 9, Pl-50-204 Wroclaw (Poland)
2011-05-21
We discuss kinematical properties of a free relativistic particle with deformed phase space in which momentum space is given by (a submanifold of) de Sitter space. We provide a detailed derivation of the action, Hamiltonian structure and equations of motion for such a free particle. We study the action of deformed relativistic symmetries on the phase space and derive explicit formulae for the action of the deformed Poincare group. Finally we provide a discussion on parametrization of the particle worldlines stressing analogies and differences with ordinary relativistic kinematics.
Criterion for stability of a special relativistically covariant dynamical system
Horwitz, L. P.; Zucker, D.
2017-03-01
We study classically the problem of two relativistic particles with an invariant Duffing-like potential which reduces to the usual Duffing form in the nonrelativistic limit. We use a special relativistic generalization (RGEM) of the geometric method (GEM) developed for the analysis of nonrelativistic Hamiltonian systems to study the local stability of a relativistic Duffing oscillator. Poincaré plots of the simulated motion are consistent with the RGEM. We find a threshold for the external driving force required for chaotic behavior in the Minkowski spacetime.
A two-dimensional approach to relativistic positioning systems
Coll, B; Morales, J A; Coll, Bartolom\\'{e}; Ferrando, Joan Josep; Morales, Juan Antonio
2006-01-01
A relativistic positioning system is a physical realization of a coordinate system consisting in four clocks in arbitrary motion broadcasting their proper times. The basic elements of the relativistic positioning systems are presented in the two-dimensional case. This simplified approach allow to explain and to analyze the properties and interest of these new systems. The positioning system defined by geodesic emitters in flat metric is developed in detail. The information that the data generated by a relativistic positioning system give on the space-time metric interval is analyzed, and the interest of these results in gravimetry is pointed out.
Scaling Calculations for a Relativistic Gyrotron.
2014-09-26
a relativistic gyrotron. The results of calculations are given in Section 3. The non- linear , slow-time-scale equations of motion used for these...corresponds to a cylindrical resonator and a thin annular electron beam ;, " with the beam radius chosen to coincide with a maximum of the resonator...entering the cavity. A tractable set of non- linear equations based on a slow-time-scale formulation developed previously was used. For this
Relativistic Fluid Dynamics: Physics for Many Different Scales
Comer Gregory L.
2007-01-01
Full Text Available The relativistic fluid is a highly successful model used to describe the dynamics of many-particle, relativistic systems. It takes as input basic physics from microscopic scales and yields as output predictions of bulk, macroscopic motion. By inverting the process, an understanding of bulk features can lead to insight into physics on the microscopic scale. Relativistic fluids have been used to model systems as “small” as heavy ions in collisions, and as large as the Universe itself, with “intermediate” sized objects like neutron stars being considered along the way. The purpose of this review is to discuss the mathematical and theoretical physics underpinnings of the relativistic (multiple fluid model. We focus on the variational principle approach championed by Brandon Carter and his collaborators, in which a crucial element is to distinguish the momenta that are conjugate to the particle number density currents. This approach differs from the “standard” text-book derivation of the equations of motion from the divergence of the stress-energy tensor in that one explicitly obtains the relativistic Euler equation as an “integrability” condition on the relativistic vorticity. We discuss the conservation laws and the equations of motion in detail, and provide a number of (in our opinion interesting and relevant applications of the general theory.
Newtonian Limits of the Relativistic Cosmological Perturbations
Hwang, J
1997-01-01
Relativistic cosmological perturbation analyses can be made based on several different fundamental gauge conditions. In the pressureless limit the variables in certain gauge conditions show the correct Newtonian behaviors. We consider the general curvature and the cosmological constant in the background medium. The perturbed density in the comoving gauge, and the perturbed velocity and the perturbed potential in the zero-shear gauge show the same behavior as the Newtonian ones in a general scale. Far inside horizon, except for the uniform-density gauge, density perturbations in all the fundamental gauge conditions show the correct Newtonian behavior. In this paper we elaborate these Newtonian correspondences. We also present the relativistic results considering general pressures in the background and perturbation.
DYNAMICS OF STRONGLY TWISTED RELATIVISTIC MAGNETOSPHERES
Parfrey, Kyle [Astronomy Department, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Beloborodov, Andrei M.; Hui, Lam, E-mail: parfrey@astro.princeton.edu [Physics Department and Columbia Astrophysics Laboratory, Columbia University, 538 West 120th Street, New York, NY 10027 (United States)
2013-09-10
Magnetar magnetospheres are believed to be strongly twisted due to shearing of the stellar crust by internal magnetic stresses. We present time-dependent axisymmetric simulations showing in detail the evolution of relativistic force-free magnetospheres subjected to slow twisting through large angles. When the twist amplitude is small, the magnetosphere moves quasi-statically through a sequence of equilibria of increasing free energy. At some twist amplitude the magnetosphere becomes tearing-mode unstable to forming a resistive current sheet, initiating large-scale magnetic reconnection in which a significant fraction of the magnetic free energy can be dissipated. This ''critical'' twist angle is insensitive to the resistive length scale. Rapid shearing temporarily stabilizes the magnetosphere beyond the critical angle, allowing the magnetosphere of a rapidly differentially rotating star to store and dissipate more free energy. In addition to these effects, shearing the surface of a rotating star increases the spindown torque applied to the star. If shearing is much slower than rotation, the resulting spikes in spindown rate can occur on timescales anywhere from the long twisting timescale to the stellar spin period or shorter, depending both on the stellar shear distribution and the existing distribution of magnetospheric twists. A model in which energy is stored in the magnetosphere and released by a magnetospheric instability therefore predicts large changes in the measured spindown rate before soft gamma repeater giant flares.
Relativistic Kinetic Theory: An Introduction
Sarbach, Olivier
2013-01-01
We present a brief introduction to the relativistic kinetic theory of gases with emphasis on the underlying geometric and Hamiltonian structure of the theory. Our formalism starts with a discussion on the tangent bundle of a Lorentzian manifold of arbitrary dimension. Next, we introduce the Poincare one-form on this bundle, from which the symplectic form and a volume form are constructed. Then, we define an appropriate Hamiltonian on the bundle which, together with the symplectic form yields the Liouville vector field. The corresponding flow, when projected onto the base manifold, generates geodesic motion. Whenever the flow is restricted to energy surfaces corresponding to a negative value of the Hamiltonian, its projection describes a family of future-directed timelike geodesics. A collisionless gas is described by a distribution function on such an energy surface, satisfying the Liouville equation. Fibre integrals of the distribution function determine the particle current density and the stress-energy ten...
Relativistic spherical plasma waves
Bulanov, S. S.; Maksimchuk, A.; Schroeder, C. B.; Zhidkov, A. G.; Esarey, E.; Leemans, W. P.
2012-02-01
Tightly focused laser pulses that diverge or converge in underdense plasma can generate wake waves, having local structures that are spherical waves. Here we study theoretically and numerically relativistic spherical wake waves and their properties, including wave breaking.
Relativistic GLONASS and geodesy
Mazurova, E. M.; Kopeikin, S. M.; Karpik, A. P.
2016-12-01
GNSS technology is playing a major role in applications to civil, industrial and scientific areas. Nowadays, there are two fully functional GNSS: American GPS and Russian GLONASS. Their data processing algorithms have been historically based on the Newtonian theory of space and time with only a few relativistic effects taken into account as small corrections preventing the system from degradation on a fairly long time. Continuously growing accuracy of geodetic measurements and atomic clocks suggests reconsidering the overall approach to the GNSS theoretical model based on the Einstein theory of general relativity. This is essentially more challenging but fundamentally consistent theoretical approach to relativistic space geodesy. In this paper, we overview the basic principles of the relativistic GNSS model and explain the advantages of such a system for GLONASS and other positioning systems. Keywords: relativistic GLONASS, Einstein theory of general relativity.
Bliokh, Konstantin Y
2011-01-01
We consider the relativistic deformation of quantum waves and mechanical bodies carrying intrinsic angular momentum (AM). When observed in a moving reference frame, the centroid of the object undergoes an AM-dependent transverse shift. This is the relativistic analogue of the spin Hall effect, which occurs in free space without any external fields. Remarkably, the shifts of the geometric and energy centroids differ by a factor of 2, and both centroids are crucial for the correct Lorentz transformations of the AM tensor. We examine manifestations of the relativistic Hall effect in quantum vortices, mechanical flywheel, and discuss various fundamental aspects of the phenomenon. The perfect agreement of quantum and relativistic approaches allows applications at strikingly different scales: from elementary spinning particles, through classical light, to rotating black-holes.
Relativistic quantum revivals.
Strange, P
2010-03-26
Quantum revivals are now a well-known phenomena within nonrelativistic quantum theory. In this Letter we display the effects of relativity on revivals and quantum carpets. It is generally believed that revivals do not occur within a relativistic regime. Here we show that while this is generally true, it is possible, in principle, to set up wave packets with specific mathematical properties that do exhibit exact revivals within a fully relativistic theory.
Relativistic viscoelastic fluid mechanics.
Fukuma, Masafumi; Sakatani, Yuho
2011-08-01
A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.
The Post-Newtonian Approximation for Relativistic Compact Binaries
Futamase Toshifumi
2007-03-01
Full Text Available We discuss various aspects of the post-Newtonian approximation in general relativity. After presenting the foundation based on the Newtonian limit, we show a method to derive post-Newtonian equations of motion for relativistic compact binaries based on a surface integral approach and the strong field point particle limit. As an application we derive third post-Newtonian equations of motion for relativistic compact binaries which respect the Lorentz invariance in the post-Newtonian perturbative sense, admit a conserved energy, and are free from any ambiguity.
Testing Relativistic Gravity with Radio Pulsars
Wex, Norbert
2014-01-01
Before the 1970s, precision tests for gravity theories were constrained to the weak gravitational fields of the Solar system. Hence, only the weak-field slow-motion aspects of relativistic celestial mechanics could be investigated. Testing gravity beyond the first post-Newtonian contributions was for a long time out of reach. The discovery of the first binary pulsar by Russell Hulse and Joseph Taylor in the summer of 1974 initiated a completely new field for testing the relativistic dynamics of gravitationally interacting bodies. For the first time the back reaction of gravitational wave emission on the binary motion could be studied. Furthermore, the Hulse-Taylor pulsar provided the first test bed for the orbital dynamics of strongly self-gravitating bodies. To date there are a number of pulsars known, which can be utilized for precision test of gravity. Depending on their orbital properties and their companion, these pulsars provide tests for various different aspects of relativistic dynamics. Besides tests...
Lateral shear interferometry with holo shear lens
Joenathan, C.; Mohanty, R. K.; Sirohi, R. S.
1984-12-01
A simple method for obtaining lateral shear using holo shear lenses (HSL) has been discussed. This simple device which produces lateral shears in the orthogonal directions has been used for lens testing. The holo shear lens is placed at or near the focus of the lens to be tested. It has also been shown that HSL can be used in speckle shear interferometry as it performs both the functions of shearing and imaging.
Bulk and shear viscosity in Hagedorn fluid
Tawfik, A.; Wahba, M. [Egyptian Center for Theoretical Physics (ECTP), MTI University, Faculty of Engineering, Cairo (Egypt)
2010-11-15
Assuming that the Hagedorn fluid composed of known particles and resonances with masses m <2 GeV obeys the first-order theory (Eckart) of relativistic fluid, we discuss the transport properties of QCD confined phase. Based on the relativistic kinetic theory formulated under the relaxation time approximation, expressions for bulk and shear viscosity in thermal medium of hadron resonances are derived. The relaxation time in the Hagedorn dynamical fluid exclusively takes into account the decay and eventually van der Waals processes. We comment on the in-medium thermal effects on bulk and shear viscosity and averaged relaxation time with and without the excluded-volume approach. As an application of these results, we suggest the dynamics of heavy-ion collisions, non-equilibrium thermodynamics and the cosmological models, which require thermo- and hydro-dynamics equations of state. (Abstract Copyright [2010], Wiley Periodicals, Inc.)
Bulk and Shear Viscosity in Hagedorn Fluid
Tawfik, A
2010-01-01
Assuming that the Hagedorn fluid composed of known particles and resonances with masses $m<2\\,$GeV obeys the {\\it first-order} theory (Eckart) of relativistic fluid, we discuss the transport properties of QCD confined phase. Based on the relativistic kinetic theory formulated under the relaxation time approximation, expressions for bulk and shear viscosity in thermal medium are derived. The relaxation time in the Hagedorn dynamical fluid exclusively takes into account the decay and eventually van der Waals processes. We comment on the {\\it in-medium} thermal effects on bulk and shear viscosities and averaged relaxation time with and without the excluded-volume approach. As an application of these results, we suggest the dynamics of heavy-ion collisions, non-equlibrium thermodynamics and the cosmological models, which require thermo and hydrodynamics equations of state.
Poincare algebra realized in Hamiltonian formalism of the Relativistic Theory of Gravitation
Soloviev, V O
2010-01-01
We obtain the Poincare group generators by proper choice of arbitrary functions present in the Relativistic Theory of Gravitation (RTG) Hamiltonian. Their Dirac brackets give the Poincare algebra in accordance with the fact that RTG has 10 integrals of motion.
Radiation of non-relativistic particle on a conducting sphere and a string of spheres
Shul'ga, N F; Larikova, E A
2016-01-01
The radiation arising under uniform motion of non-relativistic charged particle by (or through) perfectly conducting sphere is considered. The rigorous results are obtained using the method of images known from electrostatics.
李明; 刘勇; 孙哲哲; 袁赫
2015-01-01
近断层脉冲型地震动对结构有很大的潜在破坏作用.为分析不同类型该类地震动对框架剪力墙结构地震反应的影响,搜集了近断层双脉冲和多脉冲型地震动,计算了这些地震动的加速度反应谱,及其引起的一个22层钢筋混凝土框架-剪力墙结构的时程反应.对比了双脉冲和多脉冲型地震动的平均弹性加速度反应谱,及其引起框架-剪力墙结构的平均基底剪力、平均最大层间位移角、平均顶层位移和平均结构整体破坏指数.结果表明:近断层双脉冲型地震动的平均弹性加速度反应谱谱值均接近或大于近断层多脉冲型地震动;近断层双脉冲型地震动引起的框架-剪力墙结构平均基底剪力、平均最大层间位移角、平均顶层位移和平均结构整体破坏指数均不小于近断层多脉冲型地震动.由此说明,在统计意义上,当分析近断层脉冲型地震动对框架-剪力墙结构破坏作用的影响时,输入地震动可近似仅考虑双脉冲型地震动.%Near-fault pulse ground motion has large potential damage effect on structure.In order to analyze the effect of this kind of ground motion on frame-shear wall structures,near-fault double-pulse-type and multi-pulse-type ground motion are collected.Their elastic acceleration response spectra and the time history response of a 22-floor concrete reinforced frame-shear wall structure induced by them are calculated.The average elastic acceleration response spectra of the near-fault double-pulse-type ground motion is compared with that of the multi-pulse-type ground motion.The average base shear,the average maximum storey-drift-angle,the average top floor displacement,and the average whole structure damage index induced by the near-fault double-pulse-type ground motion are also compared with those induced by the multi-pulse-type ground motion.The results show:the average elastic acceleration response spectra of the near-fault double
Relativistic differential-difference momentum operators and noncommutative differential calculus
Mir-Kasimov, R. M.
2013-09-01
The relativistic kinetic momentum operators are introduced in the framework of the Quantum Mechanics (QM) in the Relativistic Configuration Space (RCS). These operators correspond to the half of the non-Euclidean distance in the Lobachevsky momentum space. In terms of kinetic momentum operators the relativistic kinetic energy is separated as the independent term of the total Hamiltonian. This relativistic kinetic energy term is not distinguishing in form from its nonrelativistic counterpart. The role of the plane wave (wave function of the motion with definite value of momentum and energy) plays the generating function for the matrix elements of the unitary irreps of Lorentz group (generalized Jacobi polynomials). The kinetic momentum operators are the interior derivatives in the framework of the noncommutative differential calculus over the commutative algebra generated by the coordinate functions over the RCS.
Shear Viscosity in a Gluon Gas
Xu, Zhe; Greiner, Carsten
2007-01-01
The relation of the shear viscosity coefficient to the recently introduced transport rate is derived within relativistic kinetic theory. We calculate the shear viscosity over entropy ratio \\eta/s for a gluon gas, which involves elastic gg-> gg perturbative QCD (PQCD) scatterings as well as inelastic ggggg PQCD bremsstrahlung. For \\alpha_s=0.3 we find \\eta/s=0.13 and for \\alpha_s=0.6, \\eta/s=0.076. The small \\eta/s values, which suggest strongly coupled systems, are due to the gluon bremsstrah...
ON WALL SHEAR STRESS OF ARTERY
Liu Zhao-rong; Liu Bao-yu; Qin Kai-rong
2003-01-01
In this paper, a method was proposed that the wall shear stress of artery could be determined by measuring the centerline axial velocity and radial motion of arterial wall simultaneously.The method is simple in application and can get higher precision when it is used to determine the shear stress of arterial wall in vivo.As an example, the shear stress distribution in periodic oscillatory flow of human carotid was calculated and discussed.The computed results show that the shear stress distribution at any given instant is almost uniform and will be zero at the centerline and tends to maximum at the vessel wall.
Electromagnetic Radiation and Motion of Really Shaped Particle
Klacka, J
2001-01-01
Relativistically covariant form of equation of motion for real particle (neutral in charge) under the action of electromagnetic radiation is derived. Various formulations of the equation of motion in the proper frame of reference of the particle are used. Main attention is devoted to the reformulation of the equation of motion in the general frame of reference, e. g., in the frame of reference of the source of electromagnetic radiation. This is the crucial form of equation of motion in applying it to motion of particles (cosmic dust, asteroids, ...) in the Universe if electromagnetic radiation acts on the particles. General relativistic equation of motion is presented.
Relativistic fluid dynamics in heavy ion collisions
Pu, Shi
2011-01-01
This dissertation is about the study of three important issues in the theory of relativistic fluid dynamics: the stability of dissipative fluid dynamics, the shear viscosity, and fluid dynamics with triangle anomaly.(1)The second order theory of fluid dynamics is necessary for causality. However the causality cannot be guaranteed for all parameters. The constraints for parameters are then given. We also point out that the causality and the stability are inter-correlated. It is found that a causal system must be stable, but an acausal system in the boost frame at high speed must be unstable. (2)The transport coefficients can be determined in kinetic theory. We will firstly discuss about derivation of the shear viscosity via variational method in the Boltzmann equation. Secondly, we will compute the shear viscosity via AdS/CFT duality in a Bjorken boost invariant fluid with radial flow. It is found that the ratio of the shear viscosity to entropy density is consistent with the work of Policastro, Son and Starin...
Relativistic theories of materials
Bressan, Aldo
1978-01-01
The theory of relativity was created in 1905 to solve a problem concerning electromagnetic fields. That solution was reached by means of profound changes in fundamental concepts and ideas that considerably affected the whole of physics. Moreover, when Einstein took gravitation into account, he was forced to develop radical changes also in our space-time concepts (1916). Relativistic works on heat, thermodynamics, and elasticity appeared as early as 1911. However, general theories having a thermodynamic basis, including heat conduction and constitutive equations, did not appear in general relativity until about 1955 for fluids and appeared only after 1960 for elastic or more general finitely deformed materials. These theories dealt with materials with memory, and in this connection some relativistic versions of the principle of material indifference were considered. Even more recently, relativistic theories incorporating finite deformations for polarizable and magnetizable materials and those in which couple s...
Relativistic Quantum Communication
Hosler, Dominic
2013-01-01
In this Ph.D. thesis, I investigate the communication abilities of non-inertial observers and the precision to which they can measure parametrized states. I introduce relativistic quantum field theory with field quantisation, and the definition and transformations of mode functions in Minkowski, Schwarzschild and Rindler spaces. I introduce information theory by discussing the nature of information, defining the entropic information measures, and highlighting the differences between classical and quantum information. I review the field of relativistic quantum information. We investigate the communication abilities of an inertial observer to a relativistic observer hovering above a Schwarzschild black hole, using the Rindler approximation. We compare both classical communication and quantum entanglement generation of the state merging protocol, for both the single and dual rail encodings. We find that while classical communication remains finite right up to the horizon, the quantum entanglement generation tend...
Relativistic quantum mechanics
Horwitz, Lawrence P
2015-01-01
This book describes a relativistic quantum theory developed by the author starting from the E.C.G. Stueckelberg approach proposed in the early 40s. In this framework a universal invariant evolution parameter (corresponding to the time originally postulated by Newton) is introduced to describe dynamical evolution. This theory is able to provide solutions for some of the fundamental problems encountered in early attempts to construct a relativistic quantum theory. A relativistically covariant construction is given for which particle spins and angular momenta can be combined through the usual rotation group Clebsch-Gordan coefficients. Solutions are defined for both the classical and quantum two body bound state and scattering problems. The recently developed quantum Lax-Phillips theory of semigroup evolution of resonant states is described. The experiment of Lindner and coworkers on interference in time is discussed showing how the property of coherence in time provides a simple understanding of the results. Th...
Relativistic-microwave theory of ball lightning
Wu, H.-C.
2016-06-01
Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics.
Relativistic Rotation: A Comparison of Theories
Klauber, R D
2006-01-01
Alternative theories of relativistic rotation considered viable as of 2004 are compared in the light of experiments reported in 2005. En route, the contentious issue of simultaneity choice in rotation is resolved by showing that only one simultaneity choice, the one possessing continuous time, gives rise, via the general relativistic equation of motion, to the correct Newtonian limit Coriolis acceleration. In addition, the widely dispersed argument purporting to justify an absolute Lorentz contraction in rotation is analyzed and found lacking for more than one reason. It is argued that only via experiment can we know whether such absolute contraction exists in rotation or not. The Coriolis/simultaneity correlation, and the results of the 2005 experiments, support the Selleri theory as being closest to the truth, though it is incomplete in a more general applicability sense, because it does not provide a global metric. Two alternatives, a modified Klauber approach and a Selleri-Klauber hybrid, are presented wh...
Relativistic-microwave theory of ball lightning.
Wu, H-C
2016-06-22
Ball lightning, a fireball sometimes observed during lightnings, has remained unexplained. Here we present a comprehensive theory for the phenomenon: At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation. The latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. This mechanism is verified by particle simulations. The many known properties of ball lightning, such as the occurrence site, relation to the lightning channels, appearance in aircraft, its shape, size, sound, spark, spectrum, motion, as well as the resulting injuries and damages, are also explained. Our theory suggests that ball lighting can be created in the laboratory or triggered during thunderstorms. Our results should be useful for lightning protection and aviation safety, as well as stimulate research interest in the relativistic regime of microwave physics.
Exact Relativistic Magnetized Haloes around Rotating Disks
Antonio C. Gutiérrez-Piñeres
2015-01-01
Full Text Available The study of the dynamics of magnetic fields in galaxies is one of important problems in formation and evolution of galaxies. In this paper, we present the exact relativistic treatment of a rotating disk surrounded by a magnetized material halo. The features of the halo and disk are described by the distributional energy-momentum tensor of a general fluid in canonical form. All the relevant quantities and the metric and electromagnetic potentials are exactly determined by an arbitrary harmonic function only. For instance, the generalized Kuzmin-disk potential is used. The particular class of solutions obtained is asymptotically flat and satisfies all the energy conditions. Moreover, the motion of a charged particle on the halo is described. As far as we know, this is the first relativistic model describing analytically the magnetized halo of a rotating disk.
Handbook of relativistic quantum chemistry
Liu, Wenjian (ed.) [Peking Univ., Beijing (China). Center for Computational Science and Engineering
2017-03-01
This handbook focuses on the foundations of relativistic quantum mechanics and addresses a number of fundamental issues never covered before in a book. For instance: How can many-body theory be combined with quantum electrodynamics? How can quantum electrodynamics be interfaced with relativistic quantum chemistry? What is the most appropriate relativistic many-electron Hamiltonian? How can we achieve relativistic explicit correlation? How can we formulate relativistic properties? - just to name a few. Since relativistic quantum chemistry is an integral component of computational chemistry, this handbook also supplements the ''Handbook of Computational Chemistry''. Generally speaking, it aims to establish the 'big picture' of relativistic molecular quantum mechanics as the union of quantum electrodynamics and relativistic quantum chemistry. Accordingly, it provides an accessible introduction for readers new to the field, presents advanced methodologies for experts, and discusses possible future perspectives, helping readers understand when/how to apply/develop the methodologies.
SU(3) Polyakov linear-sigma model: bulk and shear viscosity of QCD matter in finite magnetic field
Tawfik, Abdel Nasser; Hussein, T M
2016-01-01
Due to off-center relativistic motion of the charged spectators and the local momentum-imbalance of the participants, a short-lived huge magnetic field is likely generated, especially in relativistic heavy-ion collisions. In determining the temperature dependence of bulk and shear viscosities of the QCD matter in vanishing and finite magnetic field, we utilize mean field approximation to the SU($3$) Polyakov linear-sigma model (PLSM). We compare between the results from two different approaches; Green-Kubo correlation and Boltzmann master equation with Chapman-Enskog expansion. We find that both approaches have almost identical results, especially in the hadron phase. In the temperature dependence of bulk and shear viscosities relative to thermal entropy at the critical temperature, there is a rapid decrease in the chiral phase-transition and in the critical temperature with increasing magnetic field. As the magnetic field strength increases, a peak appears at the critical temperature ($T_c$). This can be und...
On the time delay between ultra-relativistic particles
Pierre Fleury
2016-09-01
Full Text Available The time delay between the receptions of ultra-relativistic particles emitted simultaneously is a useful observable for both fundamental physics and cosmology. The expression of the delay when the particles travel through an arbitrary spacetime has been derived recently by Fanizza et al., using a particular coordinate system and self-consistent assumptions. The present article shows that this formula enjoys a simple physical interpretation: the relative velocity between two ultra-relativistic particles is constant. This result reveals an interesting kinematical property of general relativity, namely that the tidal forces experienced by ultra-relativistic particles in the direction of their motion are much smaller than those experienced orthogonally to their motion.
On the time delay between ultra-relativistic particles
Fleury, Pierre
2016-09-01
The time delay between the receptions of ultra-relativistic particles emitted simultaneously is a useful observable for both fundamental physics and cosmology. The expression of the delay when the particles travel through an arbitrary spacetime has been derived recently by Fanizza et al., using a particular coordinate system and self-consistent assumptions. The present article shows that this formula enjoys a simple physical interpretation: the relative velocity between two ultra-relativistic particles is constant. This result reveals an interesting kinematical property of general relativity, namely that the tidal forces experienced by ultra-relativistic particles in the direction of their motion are much smaller than those experienced orthogonally to their motion.
Beaming of particles and synchrotron radiation in relativistic magnetic reconnection
Kagan, Daniel; Piran, Tsvi
2016-01-01
Relativistic reconnection has been invoked as a mechanism for particle acceleration in numerous astrophysical systems. According to idealised analytical models reconnection produces a bulk relativistic outflow emerging from the reconnection sites (X-points). The resulting radiation is therefore highly beamed. Using two-dimensional particle-in-cell (PIC) simulations, we investigate particle and radiation beaming, finding a very different picture. Instead of having a relativistic average bulk motion with isotropic electron velocity distribution in its rest frame, we find that the bulk motion of particles in X-points is similar to their Lorentz factor gamma, and the particles are beamed within about 5/gamma. On the way from the X-point to the magnetic islands, particles turn in the magnetic field, forming a fan confined to the current sheet. Once they reach the islands they isotropise after completing a full Larmor gyration and their radiation is not strongly beamed anymore. The radiation pattern at a given freq...
Relativistic electronic dressing
Attaourti, Y
2002-01-01
We study the effects of the relativistic electronic dressing in laser-assisted electron-hydrogen atom elastic collisions. We begin by considering the case when no radiation is present. This is necessary in order to check the consistency of our calculations and we then carry out the calculations using the relativistic Dirac-Volkov states. It turns out that a simple formal analogy links the analytical expressions of the differential cross section without laser and the differential cross section in presence of a laser field.
Fabian, A C; Parker, M L
2014-01-01
Broad emission lines, particularly broad iron-K lines, are now commonly seen in the X-ray spectra of luminous AGN and Galactic black hole binaries. Sensitive NuSTAR spectra over the energy range of 3-78 keV and high frequency reverberation spectra now confirm that these are relativistic disc lines produced by coronal irradiation of the innermost accretion flow around rapidly spinning black holes. General relativistic effects are essential in explaining the observations. Recent results are briefly reviewed here.
Relativistic Rotating Vector Model
Lyutikov, Maxim
2016-01-01
The direction of polarization produced by a moving source rotates with the respect to the rest frame. We show that this effect, induced by pulsar rotation, leads to an important correction to polarization swings within the framework of rotating vector model (RVM); this effect has been missed by previous works. We construct relativistic RVM taking into account finite heights of the emission region that lead to aberration, time-of-travel effects and relativistic rotation of polarization. Polarizations swings at different frequencies can be used, within the assumption of the radius-to-frequency mapping, to infer emission radii and geometry of pulsars.
The special relativistic shock tube
Thompson, Kevin W.
1986-01-01
The shock-tube problem has served as a popular test for numerical hydrodynamics codes. The development of relativistic hydrodynamics codes has created a need for a similar test problem in relativistic hydrodynamics. The analytical solution to the special relativistic shock-tube problem is presented here. The relativistic shock-jump conditions and rarefaction solution which make up the shock tube are derived. The Newtonian limit of the calculations is given throughout.
Non-relativistic classical mechanics for spinning particles
Salesi, G
2004-01-01
We study the classical dynamics of non-relativistic particles endowed with spin. Non-vanishing Zitterbewegung terms appear in the equation of motion also in the small momentum limit. We derive a generalized work-energy theorem which suggests classical interpretations for tunnel effect and quantum potential.
Bruce, Adam L
2015-01-01
We show the traditional rocket problem, where the ejecta velocity is assumed constant, can be reduced to an integral quadrature of which the completely non-relativistic equation of Tsiolkovsky, as well as the fully relativistic equation derived by Ackeret, are limiting cases. By expanding this quadrature in series, it is shown explicitly how relativistic corrections to the mass ratio equation as the rocket transitions from the Newtonian to the relativistic regime can be represented as products of exponential functions of the rocket velocity, ejecta velocity, and the speed of light. We find that even low order correction products approximate the traditional relativistic equation to a high accuracy in flight regimes up to $0.5c$ while retaining a clear distinction between the non-relativistic base-case and relativistic corrections. We furthermore use the results developed to consider the case where the rocket is not moving relativistically but the ejecta stream is, and where the ejecta stream is massless.
Relativistic cosmology; Cosmologia Relativista
Bastero-Gil, M.
2015-07-01
Relativistic cosmology is nothing but the study of the evolution of our universe expanding from the General Theory of Relativity, which describes the gravitational interaction at any scale and given its character far-reaching is the force that dominate the evolution of the universe. (Author)
Antippa, Adel F.
2009-01-01
We solve the problem of the relativistic rocket by making use of the relation between Lorentzian and Galilean velocities, as well as the laws of superposition of successive collinear Lorentz boosts in the limit of infinitesimal boosts. The solution is conceptually simple, and technically straightforward, and provides an example of a powerful…
Relativistic length agony continued
Redžić D.V.
2014-01-01
Full Text Available We made an attempt to remedy recent confusing treatments of some basic relativistic concepts and results. Following the argument presented in an earlier paper (Redžić 2008b, we discussed the misconceptions that are recurrent points in the literature devoted to teaching relativity such as: there is no change in the object in Special Relativity, illusory character of relativistic length contraction, stresses and strains induced by Lorentz contraction, and related issues. We gave several examples of the traps of everyday language that lurk in Special Relativity. To remove a possible conceptual and terminological muddle, we made a distinction between the relativistic length reduction and relativistic FitzGerald-Lorentz contraction, corresponding to a passive and an active aspect of length contraction, respectively; we pointed out that both aspects have fundamental dynamical contents. As an illustration of our considerations, we discussed briefly the Dewan-Beran-Bell spaceship paradox and the ‘pole in a barn’ paradox. [Projekat Ministarstva nauke Republike Srbije, br. 171028
Electromagnetic Radiation and Motion of Real Particle
Klacka, J
2000-01-01
Relativistically covariant equation of motion for real dust particle under the action of electromagnetic radiation is derived. The particle is neutral in charge. Equation of motion is expressed in terms of particle's optical properties, standardly used in optics for stationary particles.
Frontiers in Relativistic Celestial Mechanics, Vol. 1. Theory
Kopeikin, Sergei
2014-10-01
Relativistic celestial mechanics - investigating the motion celestial bodies under the influence of general relativity - is a major tool of modern experimental gravitational physics. With a wide range of prominent authors from the field, this two-volume series consists of reviews on a multitude of advanced topics in the area of relativistic celestial mechanics - starting from more classical topics such as the regime of asymptotically-flat spacetime, light propagation and celestial ephemerides, but also including its role in cosmology and alternative theories of gravity as well as modern experiments in this area. This first volume of a two-volume series is concerned with theoretical foundations such as post-Newtonian solutions to the two-body problem, light propagation through time-dependent gravitational fields, as well as cosmological effects on the movement of bodies in the solar systems. On the occasion of his 80-th birthday, these two volumes honor V. A. Brumberg - one of the pioneers in modern relativistic celestial mechanics. Contributions include: M. Soffel: On the DSX-framework T. Damour: The general relativistic two body problem G. Schaefer: Hamiltonian dynamics of spinning compact binaries through high post-Newtonian approximations A. Petrov and S. Kopeikin: Post-Newtonian approximations in cosmology T. Futamase: On the backreaction problem in cosmology Y. Xie and S. Kopeikin: Covariant theory of the post-Newtonian equations of motion of extended bodies S. Kopeikin and P. Korobkov: General relativistic theory of light propagation in multipolar gravitational fields
Relativistic hadrons and the origin of relativistic outflows in active galactic nuclei
Contopoulos, John; Kazanas, D.
1995-01-01
We examine the hydrodynamic origin of relativistic outflows in active galactic nuclei (AGN). Specifically, we propose that the presence of a population of relativistic hadrons in the AGN 'central engine' and the associated neutron production suffices to produce outflows which under rather general conditions could be relativistic. The main such condition is that the size of the neutron production region be larger than the neutron flight path tau(sub n) approximately 3 x 10(exp 13) cm. This condition guarantees that the mean energy per particle in the proton fluid, resulting from the decay of the neutrons outside their production region, be greater than the proton rest mass. The expansion of this fluid can then lead naturally to a relativistic outflow by conversion of its internal energy to directed motion. We follow the development of such flows by solving the mass, energy as well as the kinetic equation for the proton gas in steady state, taking into account the source terms due to compute accurately the adiabatic index of the expanding gas, and in conjunction with Bernoulli's equation the detailed evolution of the bulk Lorentz factor. We further examine the role of large-scale magnetic fields in confining these outflows to produce the jets observed at larger scales.
Relativistic Hydrodynamics with Wavelets
DeBuhr, Jackson; Anderson, Matthew; Neilsen, David; Hirschmann, Eric W
2015-01-01
Methods to solve the relativistic hydrodynamic equations are a key computational kernel in a large number of astrophysics simulations and are crucial to understanding the electromagnetic signals that originate from the merger of astrophysical compact objects. Because of the many physical length scales present when simulating such mergers, these methods must be highly adaptive and capable of automatically resolving numerous localized features and instabilities that emerge throughout the computational domain across many temporal scales. While this has been historically accomplished with adaptive mesh refinement (AMR) based methods, alternatives based on wavelet bases and the wavelet transformation have recently achieved significant success in adaptive representation for advanced engineering applications. This work presents a new method for the integration of the relativistic hydrodynamic equations using iterated interpolating wavelets and introduces a highly adaptive implementation for multidimensional simulati...
Fractality and geometry in ultra-relativistic nuclear collisions
Zborovský, I
2002-01-01
Assuming fractality of hadronic constituents, we argue that asymmetry of space-time can be induced in the ultra-relativistic interactions of hadrons and nuclei. The asymmetry is expressed in terms of the anomalous fractal dimensions of the colliding objects. Besides state of motion, the relativistic principle is applied to the state of asymmetry as well. Such realization of relativity concerns scale dependence of physical laws emerging at small distances. We show that induced asymmetries of space-time are a priori not excluded by the Michelson's experiment even at large scales.
A relativistic toy model for Unruh black holes
Carbonaro, P.
2014-08-01
We consider the wave propagation in terms of acoustic geometry in a quantum relativistic system. This reduces, in the hydrodynamic limit, to the equations which govern the motion of a relativistic Fermi-degenerate gas in one space dimension. The derivation of an acoustic metric for one-dimensional (1D) systems is in general plagued with the impossibility of defining a conformal factor. Here we show that, although the system is intrinsically one-dimensional, the Unruh procedure continues to work because of the particular structure symmetry of the model. By analyzing the dispersion relation, attention is also paid to the quantum effects on the wave propagation.
General Relativistic Mean Field Theory for rotating nuclei
Madokoro, Hideki [Kyushu Univ., Fukuoka (Japan). Dept. of Physics; Matsuzaki, Masayuki
1998-03-01
The {sigma}-{omega} model Lagrangian is generalized to an accelerated frame by using the technique of general relativity which is known as tetrad formalism. We apply this model to the description of rotating nuclei within the mean field approximation, which we call General Relativistic Mean Field Theory (GRMFT) for rotating nuclei. The resulting equations of motion coincide with those of Munich group whose formulation was not based on the general relativistic transformation property of the spinor fields. Some numerical results are shown for the yrast states of the Mg isotopes and the superdeformed rotational bands in the A {approx} 60 mass region. (author)
Relativistic heavy ion reactions
Brink, D.M.
1989-08-01
The theory of quantum chromodynamics predicts that if nuclear matter is heated to a sufficiently high temperature then quarks might become deconfined and a quark-gluon plasma could be produced. One of the aims of relativistic heavy ion experiments is to search for this new state of matter. These lectures survey some of the new experimental results and give an introduction to the theories used to interpret them. 48 refs., 4 tabs., 11 figs.
Relativistic spherical plasma waves
Bulanov, S S; Schroeder, C B; Zhidkov, A G; Esarey, E; Leemans, W P
2011-01-01
Tightly focused laser pulses as they diverge or converge in underdense plasma can generate wake waves, having local structures that are spherical waves. Here we report on theoretical study of relativistic spherical wake waves and their properties, including wave breaking. These waves may be suitable as particle injectors or as flying mirrors that both reflect and focus radiation, enabling unique X-ray sources and nonlinear QED phenomena.
Relativistic Quantum Noninvasive Measurements
Bednorz, Adam
2014-01-01
Quantum weak, noninvasive measurements are defined in the framework of relativity. Invariance with respect to reference frame transformations of the results in different models is discussed. Surprisingly, the bare results of noninvasive measurements are invariant for certain class of models, but not the detection error. Consequently, any stationary quantum realism based on noninvasive measurements will break, at least spontaneously, relativistic invariance and correspondence principle at zero temperature.
Relativistic cosmological hydrodynamics
Hwang, J
1997-01-01
We investigate the relativistic cosmological hydrodynamic perturbations. We present the general large scale solutions of the perturbation variables valid for the general sign of three space curvature, the cosmological constant, and generally evolving background equation of state. The large scale evolution is characterized by a conserved gauge invariant quantity which is the same as a perturbed potential (or three-space curvature) in the comoving gauge.
Relativistic gravity gradiometry
Bini, Donato; Mashhoon, Bahram
2016-12-01
In general relativity, relativistic gravity gradiometry involves the measurement of the relativistic tidal matrix, which is theoretically obtained from the projection of the Riemann curvature tensor onto the orthonormal tetrad frame of an observer. The observer's 4-velocity vector defines its local temporal axis and its local spatial frame is defined by a set of three orthonormal nonrotating gyro directions. The general tidal matrix for the timelike geodesics of Kerr spacetime has been calculated by Marck [Proc. R. Soc. A 385, 431 (1983)]. We are interested in the measured components of the curvature tensor along the inclined "circular" geodesic orbit of a test mass about a slowly rotating astronomical object of mass M and angular momentum J . Therefore, we specialize Marck's results to such a "circular" orbit that is tilted with respect to the equatorial plane of the Kerr source. To linear order in J , we recover the gravitomagnetic beating phenomenon [B. Mashhoon and D. S. Theiss, Phys. Rev. Lett. 49, 1542 (1982)], where the beat frequency is the frequency of geodetic precession. The beat effect shows up as a special long-period gravitomagnetic part of the relativistic tidal matrix; moreover, the effect's short-term manifestations are contained in certain post-Newtonian secular terms. The physical interpretation of this effect is briefly discussed.
Gravitationally confined relativistic neutrinos
Vayenas, C. G.; Fokas, A. S.; Grigoriou, D.
2017-09-01
Combining special relativity, the equivalence principle, and Newton’s universal gravitational law with gravitational rather than rest masses, one finds that gravitational interactions between relativistic neutrinos with kinetic energies above 50 MeV are very strong and can lead to the formation of gravitationally confined composite structures with the mass and other properties of hadrons. One may model such structures by considering three neutrinos moving symmetrically on a circular orbit under the influence of their gravitational attraction, and by assuming quantization of their angular momentum, as in the Bohr model of the H atom. The model contains no adjustable parameters and its solution, using a neutrino rest mass of 0.05 eV/c2, leads to composite state radii close to 1 fm and composite state masses close to 1 GeV/c2. Similar models of relativistic rotating electron - neutrino pairs give a mass of 81 GeV/c2, close to that of W bosons. This novel mechanism of generating mass suggests that the Higgs mass generation mechanism can be modeled as a latent gravitational field which gets activated by relativistic neutrinos.
Relativistic Radiation Mediated Shocks
Budnik, Ran; Sagiv, Amir; Waxman, Eli
2010-01-01
The structure of relativistic radiation mediated shocks (RRMS) propagating into a cold electron-proton plasma is calculated and analyzed. A qualitative discussion of the physics of relativistic and non relativistic shocks, including order of magnitude estimates for the relevant temperature and length scales, is presented. Detailed numerical solutions are derived for shock Lorentz factors $\\Gamma_u$ in the range $6\\le\\Gamma_u\\le30$, using a novel iteration technique solving the hydrodynamics and radiation transport equations (the protons, electrons and positrons are argued to be coupled by collective plasma processes and are treated as a fluid). The shock transition (deceleration) region, where the Lorentz factor $ \\Gamma $ drops from $ \\Gamma_u $ to $ \\sim 1 $, is characterized by high plasma temperatures $ T\\sim \\Gamma m_ec^2 $ and highly anisotropic radiation, with characteristic shock-frame energy of upstream and downstream going photons of a few~$\\times\\, m_ec^2$ and $\\sim \\Gamma^2 m_ec^2$, respectively.P...
Point form relativistic quantum mechanics and relativistic SU(6)
Klink, W. H.
1993-01-01
The point form is used as a framework for formulating a relativistic quantum mechanics, with the mass operator carrying the interactions of underlying constituents. A symplectic Lie algebra of mass operators is introduced from which a relativistic harmonic oscillator mass operator is formed. Mass splittings within the degenerate harmonic oscillator levels arise from relativistically invariant spin-spin, spin-orbit, and tensor mass operators. Internal flavor (and color) symmetries are introduced which make it possible to formulate a relativistic SU(6) model of baryons (and mesons). Careful attention is paid to the permutation symmetry properties of the hadronic wave functions, which are written as polynomials in Bargmann spaces.
COUNTER-ROTATION IN RELATIVISTIC MAGNETOHYDRODYNAMIC JETS
Cayatte, V.; Sauty, C. [Laboratoire Univers et Théories, Observatoire de Paris, UMR 8102 du CNRS, Université Paris Diderot, F-92190 Meudon (France); Vlahakis, N.; Tsinganos, K. [Department of Astrophysics, Astronomy and Mechanics, Faculty of Physics, University of Athens, 15784 Zografos, Athens (Greece); Matsakos, T. [Department of Astronomy and Astrophysics, The University of Chicago, Chicago, IL 60637 (United States); Lima, J. J. G., E-mail: veronique.cayatte@obspm.fr [Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal)
2014-06-10
Young stellar object observations suggest that some jets rotate in the opposite direction with respect to their disk. In a recent study, Sauty et al. showed that this does not contradict the magnetocentrifugal mechanism that is believed to launch such outflows. Motion signatures that are transverse to the jet axis, in two opposite directions, have recently been measured in M87. One possible interpretation of this motion is that of counter-rotating knots. Here, we extend our previous analytical derivation of counter-rotation to relativistic jets, demonstrating that counter-rotation can indeed take place under rather general conditions. We show that both the magnetic field and a non-negligible enthalpy are necessary at the origin of counter-rotating outflows, and that the effect is associated with a transfer of energy flux from the matter to the electromagnetic field. This can be realized in three cases: if a decreasing enthalpy causes an increase of the Poynting flux, if the flow decelerates, or if strong gradients of the magnetic field are present. An illustration of the involved mechanism is given by an example of a relativistic magnetohydrodynamic jet simulation.
Experimental Study on Silt Incipient Motion Under Wave Action
无
2007-01-01
Experiments on silt incipient motion under wave action were carried out. Under wave action, for different wave periods, water depths and bulk densities of silt, the shear stress or height of waves for incipient motion was determined, and a relation between the shear stress and bulk density of silt was established. Results indicate that the critical shear stress depends on the structure of the silt itself, related to the tightness between the grains (or bulk density). Exterior condition is only an external cause of silt incipient motion, and the critical shear stress for the incipient motion is the token of exterior condition.
Lattice Boltzmann model for resistive relativistic magnetohydrodynamics
Mohseni, F; Succi, S; Herrmann, H J
2015-01-01
In this paper, we develop a lattice Boltzmann model for relativistic magnetohydrodynamics (MHD). Even though the model is derived for resistive MHD, it is shown that it is numerically robust even in the high conductivity (ideal MHD) limit. In order to validate the numerical method, test simulations are carried out for both ideal and resistive limits, namely the propagation of Alfv\\'en waves in the ideal MHD and the evolution of current sheets in the resistive regime, where very good agreement is observed comparing to the analytical results. Additionally, two-dimensional magnetic reconnection driven by Kelvin-Helmholtz instability is studied and the effects of different parameters on the reconnection rate are investigated. It is shown that the density ratio has negligible effect on the magnetic reconnection rate, while an increase in shear velocity decreases the reconnection rate. Additionally, it is found that the reconnection rate is proportional to $\\sigma^{-\\frac{1}{2}}$, $\\sigma$ being the conductivity, w...
Effective actions for relativistic fluids from holography
de Boer, Jan; Pinzani-Fokeeva, Natalia
2015-01-01
Motivated by recent progress in developing action formulations of relativistic hydrodynamics, we use holography to derive the low energy dissipationless effective action for strongly coupled conformal fluids. Our analysis is based on the study of novel double Dirichlet problems for the gravitational field, in which the boundary conditions are set on two codimension one timelike hypersurfaces (branes). We provide a geometric interpretation of the Goldstone bosons appearing in such constructions in terms of a family of spatial geodesics extending between the ultraviolet and the infrared brane. Furthermore, we discuss supplementing double Dirichlet problems with information about the near-horizon geometry. We show that upon coupling to a membrane paradigm boundary condition, our approach reproduces correctly the complex dispersion relation for both sound and shear waves. We also demonstrate that upon a Wick rotation, our formulation reproduces the equilibrium partition function formalism, provided the near-horiz...
Dissipation in relativistic superfluid neutron stars
Gusakov, M E; Chugunov, A I; Gualtieri, L
2012-01-01
We analyze damping of oscillations of general relativistic superfluid neutron stars. To this aim we extend the method of decoupling of superfluid and normal oscillation modes first suggested in [Gusakov & Kantor PRD 83, 081304(R) (2011)]. All calculations are made self-consistently within the finite temperature superfluid hydrodynamics. The general analytic formulas are derived for damping times due to the shear and bulk viscosities. These formulas describe both normal and superfluid neutron stars and are valid for oscillation modes of arbitrary multipolarity. We show that: (i) use of the ordinary one-fluid hydrodynamics is a good approximation, for most of the stellar temperatures, if one is interested in calculation of the damping times of normal f-modes; (ii) for radial and p-modes such an approximation is poor; (iii) the temperature dependence of damping times undergoes a set of rapid changes associated with resonance coupling of neighboring oscillation modes. The latter effect can substantially accel...
On relativistic particle creation in Bose-Einstein condensates
Sabín, Carlos
2014-01-01
We show that particle creation of Bogoliubov modes in a Bose-Einstein condensate due to the accelerated motion of the trap is a genuinely relativistic effect. To this end we show that Bogoliubov modes can be described by a time rescaling of the Minkowski metric. A consequence of this is that Rindler transformations are perceived by the phonons as generalised Rindler transformations where the speed of light is replaced by the speed of sound, enhancing particle creation at small velocities. Since the non-relativistic limit of a Rindler transformation is just a Galilean transformation entailing no length contraction or time dilation, we show that the effect vanishes in the non-relativistic limit.
Fields and fluids on curved non-relativistic spacetimes
Geracie, Michael; Roberts, Matthew M
2015-01-01
We consider non-relativistic curved geometries and argue that the background structure should be generalized from that considered in previous works. In this approach the derivative operator is defined by a Galilean spin connection valued in the Lie algebra of the Galilean group. This includes the usual spin connection plus an additional "boost connection" which parameterizes the freedom in the derivative operator not fixed by torsion or metric compatibility. As an example of this approach we develop the theory of non-relativistic dissipative fluids and find significant differences in both equations of motion and allowed transport coefficients from those found previously. Our approach also immediately generalizes to systems with independent mass and charge currents as would arise in multicomponent fluids. Along the way we also discuss how to write general locally Galilean invariant non-relativistic actions for multiple particle species at any order in derivatives. A detailed review of the geometry and its rela...
Relativistic Effects on Reflection X-ray Spectra of AGN
Lee, Khee-Gan; /University Coll. London; Fuerst, Steven V.; /KIPAC, Menlo Park; Brandwardi-Raymond, Graziella; Wu, Kinwah; Crowley, Oliver; /University Coll. London
2007-01-05
We have calculated the reflection component of the X-ray spectra of active galactic nuclei (AGN) and shown that they can be significantly modified by the relativistic motion of the accretion flow and various gravitational effects of the central black hole. The absorption edges in the reflection spectra suffer severe energy shifts and smearing. The degree of distortion depends on the system parameters, and the dependence is stronger for some parameters such as the inner radius of the accretion disk and the disk viewing inclination angles. The relativistic effects are significant and are observable. Improper treatment of the reflection component of the X-ray continuum in spectral fittings will give rise to spurious line-like features, which will mimic the fluorescent emission lines and mask the relativistic signatures of the lines.
Essén, Hanno; Nordmark, Arne B.
2016-09-01
The canonical Poisson bracket algebra of four-dimensional relativistic mechanics is used to derive the equation of motion for a charged particle, with the Lorentz force, and the homogeneous Maxwell equations.
Kinematical Diagrams for Conical Relativistic Jets
Gopal-Krishna; Pronoy Sircar; Samir Dhurde
2007-03-01
We present diagrams depicting the expected inter-dependences of two key kinematical parameters of radio knots in the parsec-scale jets of blazars, deduced from VLBI observations. The two parameters are the apparent speed (app = capp) and the effective Doppler boosting factor (eff) of the relativistically moving radio knot. A novel aspect of these analytical computations of – diagrams is that they are made for parsecscale jets having a conical shape, with modest opening angles ( up to 10°), in accord with the VLBI observations of the nuclei of the nearest radio galaxies. Another motivating factor is the recent finding that consideration of a conical geometry can have important implications for the interpretation of a variety of radio observations of blazar jets. In addition to uniform jet flows (i.e., those having a uniform bulk Lorentz factor, ), computational results are also presented for stratified jets where an ultra-relativistic central spine along the jet axis is surrounded by a slower moving sheath, possibly arising from a velocity shear.
Recurrence relation for relativistic atomic matrix elements
Martínez y Romero, R P; Salas-Brito, A L
2000-01-01
Recurrence formulae for arbitrary hydrogenic radial matrix elements are obtained in the Dirac form of relativistic quantum mechanics. Our approach is inspired on the relativistic extension of the second hypervirial method that has been succesfully employed to deduce an analogous relationship in non relativistic quantum mechanics. We obtain first the relativistic extension of the second hypervirial and then the relativistic recurrence relation. Furthermore, we use such relation to deduce relativistic versions of the Pasternack-Sternheimer rule and of the virial theorem.
Relativistic twins or sextuplets?
Sheldon, E S
2003-01-01
A recent study of the relativistic twin 'paradox' by Soni in this journal affirmed that 'A simple solution of the twin paradox also shows anomalous behaviour of rigidly connected distant clocks' but entailed a pedagogic hurdle which the present treatment aims to surmount. Two scenarios are presented: the first 'flight-plan' is akin to that depicted by Soni, with constant-velocity segments, while the second portrays an alternative mission undertaken with sustained acceleration and deceleration, illustrated quantitatively for a two-way spacecraft flight from Earth to Polaris (465.9 light years distant) and back.
Numerical Relativistic Quantum Optics
2013-11-08
µm and a = 1. The condition for an atomic spectrum to be non-relativistic is Z α−1 ≈ 137, as follows from elementary Dirac theory. One concludes that...peculiar result that B0 = 1 TG is a weak field. At present, such fields are observed only in connection with astrophysical phenomena [14]. The highest...pulsars. The Astrophysical Journal, 541:367–373, Sep 2000. [15] M. Tatarakis, I. Watts, F.N. Beg, E.L. Clark, A.E. Dangor, A. Gopal, M.G. Haines, P.A
Corinaldesi, Ernesto
1963-01-01
Geared toward advanced undergraduate and graduate students of physics, this text provides readers with a background in relativistic wave mechanics and prepares them for the study of field theory. The treatment originated as a series of lectures from a course on advanced quantum mechanics that has been further amplified by student contributions.An introductory section related to particles and wave functions precedes the three-part treatment. An examination of particles of spin zero follows, addressing wave equation, Lagrangian formalism, physical quantities as mean values, translation and rotat
Rössler, O E; Matsuno, K
1998-04-01
The two mindsets of absolutism and relativism are juxtaposed, and the relational or relativist stance is vindicated. The only 'absolute' entity which undeniably exists, consciousness has the reality of a dream. The escape hatch from this prison is relational, as Descartes and Levinas found out: Unfalsified relational consistency implies exteriority. Exteriority implies infinite power which in turn makes compassion inevitable. Aside from ethics as a royal way to enlightenment, a new technology called 'deep technology' may be accessible. It changes the whole world in a demonstrable fashion by manipulation of the micro frame--that is, the observer-world interface.
Söderholm, Lars H.; Borg, Karl I.
2003-05-01
An axially symmetric body small compared with the mean free path is free to move in a shearing gas. The body is treated as a test particle. The force and torque acting on the body are calculated. This force and torque will set the body in motion, which asymptotically will take place in one of the eigendirections of the rate of deformation tensor. The axis of the body then points in the same direction. For a velocity field vx(y) the final motion is parallel to one of the lines x = y and x = -y, and the speed of the motion is given by V = 9μβN/8p (2πkBT/m)1/2 ατb1/4 + 1/2πατ + [8 - (6 - πατ)]b3vx,y. Here μ is the viscosity of the gas, p is the pressure, βN is a number close to unity, T is the temperature, m is the mass of a gas molecule, and ατ is parameter in the boundary conditions close to unity. The non-dimensional numbers b1 and b3 depends on the shape of the body. This speed is of the order of the mean free path of the gas multiplied by the shearing. There will be no motion for a body, which is reflection symmetric in a plane orthogonal to the axis of symmetry. This means that there is a phenomenon of phoresis in a shearing gas, which is analogous to thermophoresis in a gas with a temperature gradient.
Exotic Non-relativistic String
Casalbuoni, Roberto; Longhi, Giorgio
2007-01-01
We construct a classical non-relativistic string model in 3+1 dimensions. The model contains a spurion tensor field that is responsible for the non-commutative structure of the model. Under double dimensional reduction the model reduces to the exotic non-relativistic particle in 2+1 dimensions.
'Antigravity' Propulsion and Relativistic Hyperdrive
Felber, F S
2006-01-01
Exact payload trajectories in the strong gravitational fields of compact masses moving with constant relativistic velocities are calculated. The strong field of a suitable driver mass at relativistic speeds can quickly propel a heavy payload from rest to a speed significantly faster than the driver, a condition called hyperdrive. Hyperdrive thresholds and maxima are calculated as functions of driver mass and velocity.
A Simple Relativistic Bohr Atom
Terzis, Andreas F.
2008-01-01
A simple concise relativistic modification of the standard Bohr model for hydrogen-like atoms with circular orbits is presented. As the derivation requires basic knowledge of classical and relativistic mechanics, it can be taught in standard courses in modern physics and introductory quantum mechanics. In addition, it can be shown in a class that…
A Simple Relativistic Bohr Atom
Terzis, Andreas F.
2008-01-01
A simple concise relativistic modification of the standard Bohr model for hydrogen-like atoms with circular orbits is presented. As the derivation requires basic knowledge of classical and relativistic mechanics, it can be taught in standard courses in modern physics and introductory quantum mechanics. In addition, it can be shown in a class that…
Formation of relativistic jets. Magnetohydrodynamics and synchrotron radiation
Porth, Oliver Joachim Georg
2011-11-09
In this thesis, the formation of relativistic jets is investigated by means of special relativistic magnetohydrodynamic simulations and synchrotron radiative transfer. Our results show that the magnetohydrodynamic jet self-collimation paradigm can also be applied to the relativistic case. In the first part, jets launched from rotating hot accretion disk coronae are explored, leading to well collimated, but only mildly relativistic flows. Beyond the light-cylinder, the electric charge separation force balances the classical trans-field Lorentz force almost entirely, resulting in a decreased efficiency of acceleration and collimation in comparison to non-relativistic disk winds. In the second part, we examine Poynting dominated flows of various electric current distributions. By following the outflow for over 3000 Schwarzschild radii, highly relativistic jets of Lorentz factor Γ>or similar 8 and half-opening angles below 1 are obtained, providing dynamical models for the parsec scale jets of active galactic nuclei. Applying the magnetohydrodynamic structure of the quasi-stationary simulation models, we solve the relativistically beamed synchrotron radiation transport. This yields synthetic radiation maps and polarization patterns that can be used to confront high resolution radio and (sub-) mm observations of nearby active galactic nuclei. Relativistic motion together with the helical magnetic fields of the jet formation site imprint a clear signature on the observed polarization and Faraday rotation. In particular, asymmetries in the polarization direction across the jet can disclose the handedness of the magnetic helix and thus the spin direction of the central engine. Finally, we show first results from fully three-dimensional, high resolution adaptive mesh refinement simulations of jet formation from a rotating magnetosphere and examine the jet stability. Relativistic field-line rotation leads to an electric charge separation force that opposes the magnetic
Komissarov, S S; Lyutikov, M
2015-01-01
In this paper we describe a simple numerical approach which allows to study the structure of steady-state axisymmetric relativistic jets using one-dimensional time-dependent simulations. It is based on the fact that for narrow jets with v~c the steady-state equations of relativistic magnetohydrodynamics can be accurately approximated by the one-dimensional time-dependent equations after the substitution z=ct. Since only the time-dependent codes are now publicly available this is a valuable and efficient alternative to the development of a high-specialized code for the time-independent equations. The approach is also much cheaper and more robust compared to the relaxation method. We tested this technique against numerical and analytical solutions found in literature as well as solutions we obtained using the relaxation method and found it sufficiently accurate. In the process, we discovered the reason for the failure of the self-similar analytical model of the jet reconfinement in relatively flat atmospheres a...
Robust relativistic bit commitment
Chakraborty, Kaushik; Chailloux, André; Leverrier, Anthony
2016-12-01
Relativistic cryptography exploits the fact that no information can travel faster than the speed of light in order to obtain security guarantees that cannot be achieved from the laws of quantum mechanics alone. Recently, Lunghi et al. [Phys. Rev. Lett. 115, 030502 (2015), 10.1103/PhysRevLett.115.030502] presented a bit-commitment scheme where each party uses two agents that exchange classical information in a synchronized fashion, and that is both hiding and binding. A caveat is that the commitment time is intrinsically limited by the spatial configuration of the players, and increasing this time requires the agents to exchange messages during the whole duration of the protocol. While such a solution remains computationally attractive, its practicality is severely limited in realistic settings since all communication must remain perfectly synchronized at all times. In this work, we introduce a robust protocol for relativistic bit commitment that tolerates failures of the classical communication network. This is done by adding a third agent to both parties. Our scheme provides a quadratic improvement in terms of expected sustain time compared with the original protocol, while retaining the same level of security.
A relativistic trolley paradox
Matvejev, Vadim N.; Matvejev, Oleg V.; Grøn, Ø.
2016-06-01
We present an apparent paradox within the special theory of relativity, involving a trolley with relativistic velocity and its rolling wheels. Two solutions are given, both making clear the physical reality of the Lorentz contraction, and that the distance on the rails between each time a specific point on the rim touches the rail is not equal to 2 π R , where R is the radius of the wheel, but 2 π R / √{ 1 - R 2 Ω 2 / c 2 } , where Ω is the angular velocity of the wheels. In one solution, the wheel radius is constant as the velocity of the trolley increases, and in the other the wheels contract in the radial direction. We also explain two surprising facts. First that the shape of a rolling wheel is elliptical in spite of the fact that the upper part of the wheel moves faster than the lower part, and thus is more Lorentz contracted, and second that a Lorentz contracted wheel with relativistic velocity rolls out a larger distance between two successive touches of a point of the wheel on the rails than the length of a circle with the same radius as the wheels.
Fractional Dynamics of Relativistic Particle
Tarasov, Vasily E
2011-01-01
Fractional dynamics of relativistic particle is discussed. Derivatives of fractional orders with respect to proper time describe long-term memory effects that correspond to intrinsic dissipative processes. Relativistic particle subjected to a non-potential four-force is considered as a nonholonomic system. The nonholonomic constraint in four-dimensional space-time represents the relativistic invariance by the equation for four-velocity u_{\\mu} u^{\\mu}+c^2=0, where c is a speed of light in vacuum. In the general case, the fractional dynamics of relativistic particle is described as non-Hamiltonian and dissipative. Conditions for fractional relativistic particle to be a Hamiltonian system are considered.
Donker, H. C.; Katsnelson, M. I.; De Raedt, H.; Michielsen, K.
2016-09-01
The logical inference approach to quantum theory, proposed earlier De Raedt et al. (2014), is considered in a relativistic setting. It is shown that the Klein-Gordon equation for a massive, charged, and spinless particle derives from the combination of the requirements that the space-time data collected by probing the particle is obtained from the most robust experiment and that on average, the classical relativistic equation of motion of a particle holds.
The effect of a two-fluid atmosphere on relativistic stars
Govender, Gabriel; Maharaj, Sunil D
2015-01-01
We model the physical behaviour at the surface of a relativistic radiating star in the strong gravity limit. The spacetime in the interior is taken to be spherically symmetrical and shear-free. The heat conduction in the interior of the star is governed by the geodesic motion of fluid particles and a nonvanishing radially directed heat flux. The local atmosphere in the exterior region is a two-component system consisting of standard pressureless (null) radiation and an additional null fluid with nonzero pressure and constant energy density. We analyse the generalised junction condition for the matter and gravitational variables on the stellar surface and generate an exact solution. We investigate the effect of the exterior energy density on the temporal evolution of the radiating fluid pressure, luminosty, gravitational redshift and mass flow at the boundary of the star. The influence of the density on the rate of gravitational collapse is also probed and the strong, dominant and weak energy conditions are al...
Klacka, J
2001-01-01
Relativistically covariant form of equation of motion for real particle (body) under the action of electromagnetic radiation is derived. Equation of motion in the proper frame of the particle uses the radiation pressure cross section 3 $\\times$ 3 matrix. Obtained covariant equation of motion is compared with another covariant equation of motion which was presented more than one year ago.
Arzeliès, Henri
1972-01-01
Relativistic Point Dynamics focuses on the principles of relativistic dynamics. The book first discusses fundamental equations. The impulse postulate and its consequences and the kinetic energy theorem are then explained. The text also touches on the transformation of main quantities and relativistic decomposition of force, and then discusses fields of force derivable from scalar potentials; fields of force derivable from a scalar potential and a vector potential; and equations of motion. Other concerns include equations for fields; transfer of the equations obtained by variational methods int
Shearing radiative collapse with expansion and acceleration
Thirukkanesh, S; Maharaj, S D
2013-01-01
We investigate the behaviour of a relativistic spherically symmetric radiative star with an accelerating, expanding and shearing interior matter distribution in the presence of anisotropic pressures. The junction condition can be written in standard form in three cases: linear, Bernoulli and Riccati equations. We can integrate the boundary condition in each case and three classes of new solutions are generated. For particular choices of the metric we investigate the physical properties and consider the limiting behaviour for large values of time. The causal temperature can also be found explicitly.
Lattice Boltzmann model for resistive relativistic magnetohydrodynamics.
Mohseni, F; Mendoza, M; Succi, S; Herrmann, H J
2015-08-01
In this paper, we develop a lattice Boltzmann model for relativistic magnetohydrodynamics (MHD). Even though the model is derived for resistive MHD, it is shown that it is numerically robust even in the high conductivity (ideal MHD) limit. In order to validate the numerical method, test simulations are carried out for both ideal and resistive limits, namely the propagation of Alfvén waves in the ideal MHD and the evolution of current sheets in the resistive regime, where very good agreement is observed comparing to the analytical results. Additionally, two-dimensional magnetic reconnection driven by Kelvin-Helmholtz instability is studied and the effects of different parameters on the reconnection rate are investigated. It is shown that the density ratio has a negligible effect on the magnetic reconnection rate, while an increase in shear velocity decreases the reconnection rate. Additionally, it is found that the reconnection rate is proportional to σ-1/2, σ being the conductivity, which is in agreement with the scaling law of the Sweet-Parker model. Finally, the numerical model is used to study the magnetic reconnection in a stellar flare. Three-dimensional simulation suggests that the reconnection between the background and flux rope magnetic lines in a stellar flare can take place as a result of a shear velocity in the photosphere.
Harvesting short rotation woody crops with a shear
Wellington Cardoso; Dana Mitchell; Tom Gallagher; Daniel. and de Souza
2014-01-01
A time and motion study was performed on a skid steer equipped with a 14-inch tree shear attachment. The machine was used to install initial coppice harvesting treatments on three stands across the south. The study included one willow and two cottonwood sites. The stands averaged from 2 to 4 years old. Approximately 200 trees were shear harvested from each of the...
Special-relativistic model flows of viscous fluid
Rogava, A D
1996-01-01
Two, the most simple cases of special-relativistic flows of a viscous, incompressible fluid are considered: plane Couette flow and plane Poiseuille flow. Considering only the regular motion of the fluid we found the distribution of velocity in the fluid (velocity profiles) and the friction force, acting on immovable wall. The results are expressed through simple analytical functions for the Couette flow, while for the Poiseiulle flow they are expressed by higher transcendental functions (Jacobi's elliptic functions).
Noether Theorem of Relativistic-Electromagnetic Ideal Hydrodynamics
Elsas, J H Gaspar; Kodama, T
2014-01-01
We present a variational approach for relativistic ideal hydrodynamics interacting with electromagnetic fields. The momentum of fluid is introduced as the canonical conjugate variable of the position of a fluid element, which coincides with the conserved quantity derived from the Noether theorem. We further show that our formulation can reproduce the usual electromagnetic hydrodynamics which is obtained so as to satisfy the conservation of the inertia of fluid motion.
Massively parallel simulations of relativistic fluid dynamics on graphics processing units with CUDA
Bazow, Dennis; Strickland, Michael
2016-01-01
Relativistic fluid dynamics is a major component in dynamical simulations of the quark-gluon plasma created in relativistic heavy-ion collisions. Simulations of the full three-dimensional dissipative dynamics of the quark-gluon plasma with fluctuating initial conditions are computationally expensive and typically require some degree of parallelization. In this paper, we present a GPU implementation of the Kurganov-Tadmor algorithm which solves the 3+1d relativistic viscous hydrodynamics equations including the effects of both bulk and shear viscosities. We demonstrate that the resulting CUDA-based GPU code is approximately two orders of magnitude faster than the corresponding serial implementation of the Kurganov-Tadmor algorithm. We validate the code using (semi-)analytic tests such as the relativistic shock-tube and Gubser flow.
Vorticity production through rotation, shear and baroclinicity
Del Sordo, Fabio
2010-01-01
In the absence of rotation and shear, and under the assumption of constant temperature or specific entropy, purely potential forcing by localized expansion waves is known to produce irrotational flows that have no vorticity. Here we study the production of vorticity under idealized conditions when there is rotation, shear, or baroclinicity, to address the problem of vorticity generation in the interstellar medium in a systematic fashion. We use three-dimensional periodic box numerical simulations to investigate the various effects in isolation. We find that for slow rotation, vorticity production in an isothermal gas is small in the sense that the ratio of the root-mean-square values of vorticity and velocity is small compared with the wavenumber of the energy carrying motions. For Coriolis numbers above a certain level, vorticity production saturates at a value where the aforementioned ratio becomes comparable with the wavenumber of the energy carrying motions. Shear also raises the vorticity production, but...
Magnetic Dissipation in Relativistic Jets
Yosuke Mizuno
2016-10-01
Full Text Available The most promising mechanisms for producing and accelerating relativistic jets, and maintaining collimated structure of relativistic jets involve magnetohydrodynamical (MHD processes. We have investigated the magnetic dissipation mechanism in relativistic jets via relativistic MHD simulations. We found that the relativistic jets involving a helical magnetic field are unstable for the current-driven kink instability, which leads to helically distorted structure in relativistic jets. We identified the regions of high current density in filamentary current sheets, indicative of magnetic reconnection, which are associated to the kink unstable regions and correlated to the converted regions of magnetic to kinetic energies of the jets. We also found that an over-pressured relativistic jet leads to the generation of a series of stationary recollimation shocks and rarefaction structures by the nonlinear interaction of shocks and rarefaction waves. The differences in the recollimation shock structure due to the difference of the magnetic field topologies and strengths may be observable through mm-VLBI observations and space-VLBI mission.
Relativistic Fractal Cosmologies
Ribeiro, Marcelo B
2009-01-01
This article reviews an approach for constructing a simple relativistic fractal cosmology whose main aim is to model the observed inhomogeneities of the distribution of galaxies by means of the Lemaitre-Tolman solution of Einstein's field equations for spherically symmetric dust in comoving coordinates. This model is based on earlier works developed by L. Pietronero and J.R. Wertz on Newtonian cosmology, whose main points are discussed. Observational relations in this spacetime are presented, together with a strategy for finding numerical solutions which approximate an averaged and smoothed out single fractal structure in the past light cone. Such fractal solutions are shown, with one of them being in agreement with some basic observational constraints, including the decay of the average density with the distance as a power law (the de Vaucouleurs' density power law) and the fractal dimension in the range 1 <= D <= 2. The spatially homogeneous Friedmann model is discussed as a special case of the Lemait...
Relativistic Gravothermal Instabilities
Roupas, Zacharias
2014-01-01
The thermodynamic instabilities of the self-gravitating, classical ideal gas are studied in the case of static, spherically symmetric configurations in General Relativity taking into account the Tolman-Ehrenfest effect. One type of instabilities is found at low energies, where thermal energy becomes too weak to halt gravity and another at high energies, where gravitational attraction of thermal pressure overcomes its stabilizing effect. These turning points of stability are found to depend on the total rest mass $\\mathcal{M}$ over the radius $R$. The low energy instability is the relativistic generalization of Antonov instability, which is recovered in the limit $G\\mathcal{M} \\ll R c^2$ and low temperatures, while in the same limit and high temperatures, the high energy instability recovers the instability of the radiation equation of state. In the temperature versus energy diagram of series of equilibria, the two types of gravothermal instabilities make themselves evident as a double spiral! The two energy l...
Lock, Maximilian P E
2016-01-01
The conflict between quantum theory and the theory of relativity is exemplified in their treatment of time. We examine the ways in which their conceptions differ, and describe a semiclassical clock model combining elements of both theories. The results obtained with this clock model in flat spacetime are reviewed, and the problem of generalizing the model to curved spacetime is discussed, before briefly describing an experimental setup which could be used to test of the model. Taking an operationalist view, where time is that which is measured by a clock, we discuss the conclusions that can be drawn from these results, and what clues they contain for a full quantum relativistic theory of time.
Galilean relativistic fluid mechanics
Ván, Péter
2015-01-01
Single component Galilean-relativistic (nonrelativistic) fluids are treated independently of reference frames. The basic fields are given, their balances, thermodynamic relations and the entropy production is calculated. The usual relative basic fields, the mass, momentum and energy densities, the diffusion current density, the pressure tensor and the heat flux are the time- and spacelike components of the third order mass-momentum-energy density tensor according to a velocity field. The transformation rules of the basic fields are derived and prove that the non-equilibrium thermodynamic background theory, that is the Gibbs relation, extensivity condition and the entropy production is absolute, that is independent of the reference frame and also of the fluid velocity. --- Az egykomponensu Galilei-relativisztikus (azaz nemrelativisztikus) disszipativ folyadekokat vonatkoztatasi rendszertol fuggetlenul targyaljuk. Megadjuk az alapmennyisegeket, ezek merlegeit, a termodinamikai osszefuggeseket es kiszamoljuk az ...
Relativistic Runaway Electrons
Breizman, Boris
2014-10-01
This talk covers recent developments in the theory of runaway electrons in a tokamak with an emphasis on highly relativistic electrons produced via the avalanche mechanism. The rapidly growing population of runaway electrons can quickly replace a large part of the initial current carried by the bulk plasma electrons. The magnetic energy associated with this current is typically much greater than the particle kinetic energy. The current of a highly relativistic runaway beam is insensitive to the particle energy, which separates the description of the runaway current evolution from the description of the runaway energy spectrum. A strongly anisotropic distribution of fast electrons is generally prone to high-frequency kinetic instabilities that may cause beneficial enhancement of runaway energy losses. The relevant instabilities are in the frequency range of whistler waves and electron plasma waves. The instability thresholds reported in earlier work have been revised considerably to reflect strong dependence of collisional damping on the wave frequency and the role of plasma non-uniformity, including radial trapping of the excited waves in the plasma. The talk also includes a discussion of enhanced scattering of the runaways as well as the combined effect of enhanced scattering and synchrotron radiation. A noteworthy feature of the avalanche-produced runaway current is a self-sustained regime of marginal criticality: the inductive electric field has to be close to its critical value (representing avalanche threshold) at every location where the runaway current density is finite, and the current density should vanish at any point where the electric field drops below its critical value. This nonlinear Ohm's law enables complete description of the evolving current profile. Work supported by the U.S. Department of Energy Contract No. DEFG02-04ER54742 and by ITER contract ITER-CT-12-4300000273. The views and opinions expressed herein do not necessarily reflect those of
Duzen, Carl; And Others
1992-01-01
Presents a series of activities that utilizes a leveling device to classify constant and accelerated motion. Applies this classification system to uniform circular motion and motion produced by gravitational force. (MDH)
What is "Relativistic Canonical Quantization"?
Arbatsky, D. A.
2005-01-01
The purpose of this review is to give the most popular description of the scheme of quantization of relativistic fields that was named relativistic canonical quantization (RCQ). I do not give here the full exact account of this scheme. But with the help of this review any physicist, even not a specialist in the relativistic quantum theory, will be able to get a general view of the content of RCQ, of its connection with other known approaches, of its novelty and of its fruitfulness.
A microscopic analysis of shear acceleration
Rieger, F M; Rieger, Frank M.; Duffy, Peter
2006-01-01
A microscopic analysis of the viscous energy gain of energetic particles in (gradual) non-relativistic shear flows is presented. We extend previous work and derive the Fokker-Planck coefficients for the average rate of momentum change and dispersion in the general case of a momentum-dependent scattering time $\\tau(p) \\propto p^{\\alpha}$ with $\\alpha \\geq 0$. We show that in contrast to diffusive shock acceleration the characteristic shear acceleration timescale depends inversely on the particle mean free path which makes the mechanism particularly attractive for high energy seed particles. Based on an analysis of the associated Fokker-Planck equation we show that above the injection momentum $p_0$ power-law differential particle number density spectra $n(p) \\propto p^{-(1+ \\alpha)}$ are generated for $\\alpha >0$ if radiative energy losses are negligible. We discuss the modifications introduced by synchrotron losses and determine the contribution of the accelerated particles to the viscosity of the background ...
Shear Viscosity Coefficient from Microscopic Models
Muronga, A
2004-01-01
The transport coefficient of shear viscosity is studied for a hadron matter through microscopic transport model, the Ultra--relativistic Quantum Molecular Dynamics (UrQMD), using the Green--Kubo formulas. Molecular--dynamical simulations are performed for a system of light mesons in a box with periodic boundary conditions. Starting from an initial state composed of $\\pi, \\eta ,\\omega ,\\rho ,\\phi$ with a uniform phase--space distribution, the evolution takes place through elastic collisions, production and annihilation. The system approaches a stationary state of mesons and their resonances, which is characterized by common temperature. After equilibration, thermodynamic quantities such as the energy density, particle density, and pressure are calculated. From such an equilibrated state the shear viscosity coefficient is calculated from the fluctuations of stress tensor around equilibrium using Green--Kubo relations. We do our simulations here at zero net baryon density so that the equilibration times depend o...
Shear System Debugging and Shear Test
YANG; Dong-xue; JIAO; Hai-yang
2015-01-01
Shear system is the essential equipment of head-end processing in the spent fuel reprocessing process,with the aim of cutting spent fuels into appropriate lengths for dissolve,separatingspent fuel core from jacket.Shear system of CRARL is mainly set in 01Bhot cell,element rods will be cut into short lengths of 10-30mm
Observational Cosmology With Semi-Relativistic Stars
Loeb, Abraham
2014-01-01
Galaxy mergers lead to the formation of massive black hole binaries which can accelerate background stars close to the speed of light. We estimate the comoving density of ejected stars with a peculiar velocity in excess of $0.1c$ or $0.5c$ to be $\\sim 10^{10}$ and $10^5$ Gpc$^{-3}$ respectively, in the present-day Universe. Semi-relativistic giant stars will be detectable with forthcoming telescopes out to a distance of a few Mpc, where their proper motion, radial velocity, and age, can be spectroscopically measured. In difference from traditional cosmological messengers, such as photons, neutrinos, or cosmic-rays, these stars shine and so their trajectories need not be directed at the observer for them to be detected. Tracing the stars to their parent galaxies as a function of speed and age will provide a novel test of the equivalence principle and the standard cosmological parameters. Semi-relativistic stars could also flag black hole binaries as gravitational wave sources for the future eLISA observatory.
Spatial Growth of the Current-Driven Instability in Relativistic Jets
Mizuno, Yosuke; Nishikawa, Ken-Ichi
2014-01-01
We have investigated the influence of velocity shear and a radial density profile on the spatial development of the current driven kink instability along helically magnetized relativistic jets via three-dimensional relativistic magnetohydrodynamic simulations. In this study, we use a non-periodic computational box, the jet flow is initially established across the computational grid, and a precessional perturbation at the inlet triggers growth of the kink instability. If the velocity shear radius is located inside the characteristic radius of the helical magnetic field, a static non-propagating current driven kink is excited as the perturbation propagates down the jet. Temporal growth disrupts the initial flow across the computational grid not too far from the inlet. On the other hand, if the velocity shear radius is outside the characteristic radius of the helical magnetic field, the kink is advected with the flow and grows spatially down the jet. In this case flow is maintained to much larger distances from ...
Shear modulus of neutron star crust
Baiko, D A
2011-01-01
Shear modulus of solid neutron star crust is calculated by thermodynamic perturbation theory taking into account ion motion. At given density the crust is modelled as a body-centered cubic Coulomb crystal of fully ionized atomic nuclei of one type with the uniform charge-compensating electron background. Classic and quantum regimes of ion motion are considered. The calculations in the classic temperature range agree well with previous Monte Carlo simulations. At these temperatures the shear modulus is given by the sum of a positive contribution due to the static lattice and a negative $\\propto T$ contribution due to the ion motion. The quantum calculations are performed for the first time. The main result is that at low temperatures the contribution to the shear modulus due to the ion motion saturates at a constant value, associated with zero-point ion vibrations. Such behavior is qualitatively similar to the zero-point ion motion contribution to the crystal energy. The quantum effects may be important for li...
Stephenson, W.J.; Louie, J.N.; Pullammanappallil, S.; Williams, R.A.; Odum, J.K.
2005-01-01
Multichannel analysis of surface waves (MASW) and refraction microtremor (ReMi) are two of the most recently developed surface acquisition techniques for determining shallow shear-wave velocity. We conducted a blind comparison of MASW and ReMi results with four boreholes logged to at least 260 m for shear velocity in Santa Clara Valley, California, to determine how closely these surface methods match the downhole measurements. Average shear-wave velocity estimates to depths of 30, 50, and 100 m demonstrate that the surface methods as implemented in this study can generally match borehole results to within 15% to these depths. At two of the boreholes, the average to 100 m depth was within 3%. Spectral amplifications predicted from the respective borehole velocity profiles similarly compare to within 15 % or better from 1 to 10 Hz with both the MASW and ReMi surface-method velocity profiles. Overall, neither surface method was consistently better at matching the borehole velocity profiles or amplifications. Our results suggest MASW and ReMi surface acquisition methods can both be appropriate choices for estimating shearwave velocity and can be complementary to each other in urban settings for hazards assessment.
The homopolar motor: A true relativistic engine
Guala-Valverde, Jorge; Mazzoni, Pedro; Achilles, Ricardo
2002-10-01
This article discusses experiments which enable the identification of the seat of mechanical forces in homopolar-machines reported earlier in this journal [J. Guala-Valverde and P. Mazzoni, Am. J. Phys. 63, 228-229 (1995); J. Guala-Valverde, P. Mazzoni, and K. Blas, ibid. 65, 147-148 (1997)]. We provide a suitable variation on a recent work "The Unipolar Dynamotor: A Genuine Relational Engine" [J. Guala-Valverde and P. Mazzoni, Apeiron 8, 41-52 (2001)], where "relational" implies "absolutely relativistic." Our view agrees with both Weber's recognition in the 19th century of the importance of relative motion in electromagnetic phenomena [A. K. T. Assis, Electrodynamics (Kluwer, Dordrecht, 1994)] and Einstein's 1905 statement concerning electromagnetism [Ann. Phys. 17, 891-921 (1905)].
Relativistic Accretion Mediated by Turbulent Comptonization
Socrates, Aristotle
2008-01-01
Black hole and neutron star accretion flows display unusually high levels of hard coronal emission in comparison to all other optically thick, gravitationally bound, turbulent astrophysical systems. Since these flows sit in deep relativistic gravitational potentials, their random bulk motions approach the speed of light, therefore allowing turbulent Comptonization to be an important effect. We show that the inevitable production of hard X-ray photons results from turbulent Comptonization in the limit where the turbulence is trans-sonic and the accretion power approaches the Eddington Limit. In this regime, the turbulent Compton y-parameter approaches unity and the turbulent Compton temperature is a significant fraction of the electron rest mass energy, in agreement with the observed phenomena.
Simulating relativistic binaries with Whisky
Baiotti, L.
We report about our first tests and results in simulating the last phase of the coalescence and the merger of binary relativistic stars. The simulations were performed using our code Whisky and mesh refinement through the Carpet driver.
Relativistic effects in atom gravimeters
Tan, Yu-Jie; Shao, Cheng-Gang; Hu, Zhong-Kun
2017-01-01
Atom interferometry is currently developing rapidly, which is now reaching sufficient precision to motivate laboratory tests of general relativity. Thus, it is extremely significant to develop a general relativistic model for atom interferometers. In this paper, we mainly present an analytical derivation process and first give a complete vectorial expression for the relativistic interferometric phase shift in an atom interferometer. The dynamics of the interferometer are studied, where both the atoms and the light are treated relativistically. Then, an appropriate coordinate transformation for the light is performed crucially to simplify the calculation. In addition, the Bordé A B C D matrix combined with quantum mechanics and the "perturbation" approach are applied to make a methodical calculation for the total phase shift. Finally, we derive the relativistic phase shift kept up to a sensitivity of the acceleration ˜1 0-14 m/s 2 for a 10 -m -long atom interferometer.
Twisted Radiation by Electrons in Spiral Motion
Katoh, M; Mirian, N S; Konomi, T; Taira, Y; Kaneyasu, T; Hosaka, M; Yamamoto, N; Mochihashi, A; Takashima, Y; Kuroda, K; Miyamoto, A; Miyamoto, K; Sasaki, S
2016-01-01
We theoretically show that a single free electron in circular/spiral motion radiates an electromagnetic wave possessing helical phase structure and carrying orbital angular momentum. We experimentally demonstrate it by double-slit diffraction on radiation from relativistic electrons in spiral motion. We show that twisted photons should be created naturally by cyclotron/synchrotron radiations or Compton scatterings in various situations in astrophysics. We propose promising laboratory vortex photon sources in various wavelengths ranging from radio wave to gamma-rays.
The relativistic feedback discharge model of terrestrial gamma ray flashes
Dwyer, Joseph R.
2012-02-01
As thunderclouds charge, the large-scale fields may approach the relativistic feedback threshold, above which the production of relativistic runaway electron avalanches becomes self-sustaining through the generation of backward propagating runaway positrons and backscattered X-rays. Positive intracloud (IC) lightning may force the large-scale electric fields inside thunderclouds above the relativistic feedback threshold, causing the number of runaway electrons, and the resulting X-ray and gamma ray emission, to grow exponentially, producing very large fluxes of energetic radiation. As the flux of runaway electrons increases, ionization eventually causes the electric field to discharge, bringing the field below the relativistic feedback threshold again and reducing the flux of runaway electrons. These processes are investigated with a new model that includes the production, propagation, diffusion, and avalanche multiplication of runaway electrons; the production and propagation of X-rays and gamma rays; and the production, propagation, and annihilation of runaway positrons. In this model, referred to as the relativistic feedback discharge model, the large-scale electric fields are calculated self-consistently from the charge motion of the drifting low-energy electrons and ions, produced from the ionization of air by the runaway electrons, including two- and three-body attachment and recombination. Simulation results show that when relativistic feedback is considered, bright gamma ray flashes are a natural consequence of upward +IC lightning propagating in large-scale thundercloud fields. Furthermore, these flashes have the same time structures, including both single and multiple pulses, intensities, angular distributions, current moments, and energy spectra as terrestrial gamma ray flashes, and produce large current moments that should be observable in radio waves.
Scattering in Relativistic Particle Mechanics.
de Bievre, Stephan
The problem of direct interaction in relativistic particle mechanics has been extensively studied and a variety of models has been proposed avoiding the conclusions of the so-called no-interaction theorems. In this thesis we study scattering in the relativistic two-body problem. We use our results to analyse gauge invariance in Hamiltonian constraint models and the uniqueness of the symplectic structure in manifestly covariant relativistic particle mechanics. We first present a general geometric framework that underlies approaches to relativistic particle mechanics. This permits a model-independent and geometric definition of the notions of asymptotic completeness and of Moller and scattering operators. Subsequent analysis of these concepts divides into two parts. First, we study the kinematic properties of the scattering transformation, i.e. those properties that arise solely from the invariance of the theory under the Poincare group. We classify all canonical (symplectic) scattering transformations on the relativistic phase space for two free particles in terms of a single function of the two invariants of the theory. We show how this function is determined by the center of mass time delay and scattering angle and vice versa. The second part of our analysis of the relativistic two-body scattering problem is devoted to the dynamical properties of the scattering process. Hence, we turn to two approaches to relativistic particle mechanics: the Hamiltonian constraint models and the manifestly covariant formalism. Using general geometric arguments, we prove "gauge invariance" of the scattering transformation in the Todorov -Komar Hamiltonian constraint model. We conclude that the scattering cross sections of the Todorov-Komar models have the same angular dependence as their non-relativistic counterpart, irrespective of a choice of gauge. This limits the physical relevance of those models. We present a physically non -trivial Hamiltonian constraint model, starting from
Soliton propagation in relativistic hydrodynamics
Fogaça, D A; 10.1016/j.nuclphysa.2007.03.104
2013-01-01
We study the conditions for the formation and propagation of Korteweg-de Vries (KdV) solitons in nuclear matter. In a previous work we have derived a KdV equation from Euler and continuity equations in non-relativistic hydrodynamics. In the present contribution we extend our formalism to relativistic fluids. We present results for a given equation of state, which is based on quantum hadrodynamics (QHD).
Relativistic formulation and reference frame
Klioner, Sergei A.
2004-01-01
After a short review of experimental foundations of metric theories of gravity, the choice of general relativity as a theory to be used for the routine modeling of Gaia observations is justified. General principles of relativistic modeling of astronomical observations are then sketched and compared to the corresponding Newtonian principles. The fundamental reference system -- Barycentric Celestial Reference System, which has been chosen to be the relativistic reference system underlying the f...
Dodelson, Scott; /Fermilab /Chicago U., Astron. Astrophys. Ctr. /Northwestern U.; Shapiro, Charles; /Chicago U. /KICP, Chicago; White, Martin J.; /UC, Berkeley, Astron.
2005-08-01
Measurements of ellipticities of background galaxies are sensitive to the reduced shear, the cosmic shear divided by (1-{kappa}) where {kappa} is the projected density field. They compute the difference between shear and reduced shear both analytically and with simulations. The difference becomes more important an smaller scales, and will impact cosmological parameter estimation from upcoming experiments. A simple recipe is presented to carry out the required correction.
Dodelson, Scott; /Fermilab /Chicago U., Astron. Astrophys. Ctr. /Northwestern U.; Shapiro, Charles; /Chicago U. /KICP, Chicago; White, Martin J.; /UC, Berkeley, Astron.
2005-08-01
Measurements of ellipticities of background galaxies are sensitive to the reduced shear, the cosmic shear divided by (1-{kappa}) where {kappa} is the projected density field. They compute the difference between shear and reduced shear both analytically and with simulations. The difference becomes more important an smaller scales, and will impact cosmological parameter estimation from upcoming experiments. A simple recipe is presented to carry out the required correction.
Determining the Macroscopic Properties of Relativistic Jets
Hardee, P. E.
2004-08-01
The resolved relativistic jets contain structures whose observed proper motions are typically assumed to indicate the jet flow speed. In addition to structures moving with the flow, various normal mode structures such as pinching or helical and elliptical twisting can be produced by ejection events or twisting perturbations to the jet flow. The normal mode structures associated with relativistic jets, as revealed by numerical simulation, theoretical calculation, and suggested by observation, move more slowly than the jet speed. The pattern speed is related to the jet speed by the sound speed in the jet and in the surrounding medium. In the event that normal mode structures are observed, and where proper motions of pattern and flow speed are available or can be estimated, it is possible to determine the sound speed in the jet and surrounding medium. Where spatial development of normal mode structures is observed, it is possible to make inferences as to the heating rate/macroscopic viscosity of the jet fluid. Ultimately it may prove possible to separate the microscopic energization of the synchrotron radiating particles from the macroscopic heating of the jet fluid. Here I present the relevant properties of useful normal mode structures and illustrate the use of this technique. Various aspects of the work presented here have involved collaboration with I. Agudo (Max-Planck, Bonn), M.A. Aloy (Max-Planck, Garching), J. Eilek (NM Tech), J.L. Gómez (U. Valencia), P. Hughes (U. Michigan), A. Lobanov (Max-Planck, Bonn), J.M. Martí (U. Valencia), & C. Walker (NRAO).
Simulation of ultra-relativistic electrons and positrons channeling in crystals with MBN Explorer
Sushko, Gennady B.; Bezchastnov, Victor G.; Solov'yov, Ilia;
2013-01-01
A newly developed code, implemented as a part of the MBN Explorer package (Solov'yov et al., 2012; http://www.mbnexplorer.com/, 2012) [1] and [2] to simulate trajectories of an ultra-relativistic projectile in a crystalline medium, is presented. The motion of a projectile is treated classically...... by integrating the relativistic equations of motion with account for the interaction between the projectile and crystal atoms. The probabilistic element is introduced by a random choice of transverse coordinates and velocities of the projectile at the crystal entrance as well as by accounting for the random...
Mellema, Daniel C; Song, Pengfei; Kinnick, Randall R; Urban, Matthew W; Greenleaf, James F; Manduca, Armando; Chen, Shigao
2016-09-01
Ultrasound shear wave elastography (SWE) utilizes the propagation of induced shear waves to characterize the shear modulus of soft tissue. Many methods rely on an acoustic radiation force (ARF) "push beam" to generate shear waves. However, specialized hardware is required to generate the push beams, and the thermal stress that is placed upon the ultrasound system, transducer, and tissue by the push beams currently limits the frame-rate to about 1 Hz. These constraints have limited the implementation of ARF to high-end clinical systems. This paper presents Probe Oscillation Shear Elastography (PROSE) as an alternative method to measure tissue elasticity. PROSE generates shear waves using a harmonic mechanical vibration of an ultrasound transducer, while simultaneously detecting motion with the same transducer under pulse-echo mode. Motion of the transducer during detection produces a "strain-like" compression artifact that is coupled with the observed shear waves. A novel symmetric sampling scheme is proposed such that pulse-echo detection events are acquired when the ultrasound transducer returns to the same physical position, allowing the shear waves to be decoupled from the compression artifact. Full field-of-view (FOV) two-dimensional (2D) shear wave speed images were obtained by applying a local frequency estimation (LFE) technique, capable of generating a 2D map from a single frame of shear wave motion. The shear wave imaging frame rate of PROSE is comparable to the vibration frequency, which can be an order of magnitude higher than ARF based techniques. PROSE was able to produce smooth and accurate shear wave images from three homogeneous phantoms with different moduli, with an effective frame rate of 300 Hz. An inclusion phantom study showed that increased vibration frequencies improved the accuracy of inclusion imaging, and allowed targets as small as 6.5 mm to be resolved with good contrast (contrast-to-noise ratio ≥ 19 dB) between the target and
Notes on shear viscosity bound violation in anisotropic models
Ge, Xian-Hui
2015-01-01
The shear viscosity bound violation in Einstein gravity for anisotropic black branes is discussed, with the aim of constraining the deviation of the shear viscosity-entropy density ratio from the shear viscosity bound using causality and thermodynamics analysis. The results show that no stringent constraints can be imposed. The diffusion bound in anisotropic phases is also studied. Ultimately, it is concluded that shear viscosity violation always occurs in cases where the equation of motion of the metric fluctuations cannot be written in a form identical to that of the minimally coupled massless scalar fields.
Shear viscosity of nuclear matter
Magner, A G; Grygoriev, U V; Plujko, V A
2016-01-01
Shear viscosity $\\eta$ is calculated for the nuclear matter described as a system of interacting nucleons with the van der Waals (VDW) equation of state. The Boltzmann-Vlasov kinetic equation is solved in terms of the plane waves of the collective overdamped motion. In the frequent collision regime, the shear viscosity depends on the particle number density $n$ through the mean-field parameter $a$ which describes attractive forces in the VDW equation. In the temperature region $T=15\\div 40$~MeV, a ratio of the shear viscosity to the entropy density $s$ is smaller than 1 at the nucleon number density $n =(0.5\\div 1.5)\\,n^{}_0$, where $n^{}_0=0.16\\,$fm$^{-3}$ is the particle density of equilibrium nuclear matter at zero temperature. A minimum of the $\\eta/s$ ratio takes place somewhere in a vicinity of the critical point of the VDW system. Large values of $\\eta/s\\gg 1$ are however found in both the low density, $n\\ll n^{}_0$, and high density, $n>2n^{}_0$, regions. This makes the ideal hydrodynamic approach ina...
Refining a relativistic, hydrodynamic solver: Admitting ultra-relativistic flows
Bernstein, J. P.; Hughes, P. A.
2009-09-01
We have undertaken the simulation of hydrodynamic flows with bulk Lorentz factors in the range 102-106. We discuss the application of an existing relativistic, hydrodynamic primitive variable recovery algorithm to a study of pulsar winds, and, in particular, the refinement made to admit such ultra-relativistic flows. We show that an iterative quartic root finder breaks down for Lorentz factors above 102 and employ an analytic root finder as a solution. We find that the former, which is known to be robust for Lorentz factors up to at least 50, offers a 24% speed advantage. We demonstrate the existence of a simple diagnostic allowing for a hybrid primitives recovery algorithm that includes an automatic, real-time toggle between the iterative and analytical methods. We further determine the accuracy of the iterative and hybrid algorithms for a comprehensive selection of input parameters and demonstrate the latter’s capability to elucidate the internal structure of ultra-relativistic plasmas. In particular, we discuss simulations showing that the interaction of a light, ultra-relativistic pulsar wind with a slow, dense ambient medium can give rise to asymmetry reminiscent of the Guitar nebula leading to the formation of a relativistic backflow harboring a series of internal shockwaves. The shockwaves provide thermalized energy that is available for the continued inflation of the PWN bubble. In turn, the bubble enhances the asymmetry, thereby providing positive feedback to the backflow.
Relativistic Zitterbewegung in non-Hermitian photonic waveguide systems
Wang, Guanglei; Xu, Hongya; Huang, Liang; Lai, Ying-Cheng
2017-01-01
Zitterbewegung (ZB) is a phenomenon in relativistic quantum systems where the electron wave packet exhibits a trembling or oscillating behavior during its motion, caused by its interaction or coupling with the negative energy state. To directly observe ZB in electronic systems is difficult, due to the challenges associated with the small amplitude of the motion which is of the order of Compton wavelength. Photonic systems offer an alternative paradigm. We exploit the concept of pseudo parity-time (pseudo { P }{ T }) symmetry to study ZB in non-Hermitian quantum systems implemented as an experimentally feasible optical waveguide array. In particular, the non-Hermitian Hamiltonian is realized through evanescent coupling among the waveguides to form a one-dimensional lattice with periodic modulations in gain and loss along the guiding direction. As the modulation frequency is changed, we obtain a number of phenomena including periodically suppressed ZB trembling, spatial energy localization, and Hermitian-like ZB oscillations. We calculate phase diagrams indicating the emergence of different types of dynamical behaviors of the relativistic non-Hermitian quantum system in an experimentally justified parameter space. We provide numerical results and a physical analysis to explain the distinct dynamical behaviors revealed by the phase diagrams. Our findings provide a deeper understanding of both the relativistic ZB phenomenon and non-Hermitian pseudo-{ P }{ T } systems, with potential applications in controlling/harnessing light propagation in waveguide-based optical systems.
Laser-driven relativistic tunneling from p-states
Klaiber, Michael
2014-01-01
The tunneling ionization of an electron from a p-state in a highly charged ion in the relativistic regime is investigated in a linearly polarized strong laser field. In contrast to the case of an s-state, the tunneling ionization from the p-state is spin asymmetric. We have singled out two reasons for the spin asymmetry: first, the difference of the electron energy Zeeman splitting in the bound state and during tunneling, and second, the relativistic momentum shift along the laser propagation direction during the under-the barrier motion. Due to the latter, those states are predominantly ionized where the electron rotation is opposite to the electron relativistic shift during the under-the-barrier motion. We have investigated the dependence of the ionization rate on the laser intensity for different projections of the total angular momentum and identified the intensity parameter which governs this behaviour. The significant change of the ionization rate is originated from the different precession dynamics of ...
Gilbert, Peter; Giacomin, A. Jeffrey; Schmalzer, Andrew; Bird, R. B.
Recent work has focused on understanding the molecular origins of higher harmonics that arise in the shear stress response of polymeric liquids in large-amplitude oscillatory shear flow. These higher harmonics have been explained using only the orientation distribution of a dilute suspension of rigid dumbbells in a Newtonian fluid, which neglects molecular interactions and is the simplest relevant molecular model of polymer viscoelasticity [R.B. Bird et al., J Chem Phys, 140, 074904 (2014)]. We explore these molecular interactions by examining the Curtiss-Bird model, a kinetic molecular theory that accounts for restricted polymer motions arising when chains are concentrated [Fan and Bird, JNNFM, 15, 341 (1984)]. For concentrated systems, the chain motion transverse to the chain axis is more restricted than along the axis. This anisotropy is described by the link tension coefficient, ɛ, for which several special cases arise: ɛ =0 corresponds to reptation, ɛ > 1 1 8 8 to rod-climbing, 1 1 2 2 >= ɛ >= 3 3 4 4 to reasonable shear-thinning predictions in steady simple shear flow, and ɛ =1 to a dilute solution of chains. We examine the shapes of the shear stress versus shear rate loops for the special cases, ɛ = 0 , 1 0 , 1 8 , 3 3 8 8 8 , 3 3 8 8 , 1 , of the Curtiss-Bird model, and we compare these with those of rigid dumbbell and reptation model predictions.
Empirical Foundations of Relativistic Gravity
Ni, W T
2005-01-01
In 1859, Le Verrier discovered the mercury perihelion advance anomaly. This anomaly turned out to be the first relativistic-gravity effect observed. During the 141 years to 2000, the precisions of laboratory and space experiments, and astrophysical and cosmological observations on relativistic gravity have been improved by 3 orders of magnitude. In 1999, we envisaged a 3-6 order improvement in the next 30 years in all directions of tests of relativistic gravity. In 2000, the interferometric gravitational wave detectors began their runs to accumulate data. In 2003, the measurement of relativistic Shapiro time-delay of the Cassini spacecraft determined the relativistic-gravity parameter gammaγ with a 1.5-order improvement. In October 2004, Ciufolini and Pavlis reported a measurement of the Lense-Thirring effect on the LAGEOS and LAGEOS2 satellites to 10 percent of the value predicted by general relativity. In April 2004, Gravity Probe B was launched and has been accumulating science data for more than ...
Vesicle dynamics in shear and capillary flows
Noguchi, Hiroshi; Gompper, Gerhard
2005-11-01
The deformation of vesicles in flow is studied by a mesoscopic simulation technique, which combines multi-particle collision dynamics for the solvent with a dynamically triangulated surface model for the membrane. Shape transitions are investigated both in simple shear flows and in cylindrical capillary flows. We focus on reduced volumes, where the discocyte shape of fluid vesicles is stable, and the prolate shape is metastable. In simple shear flow at low membrane viscosity, the shear induces a transformation from discocyte to prolate with increasing shear rate, while at high membrane viscosity, the shear induces a transformation from prolate to discocyte, or tumbling motion accompanied by oscillations between these two morphologies. In capillary flow, at small flow velocities the symmetry axis of the discocyte is found not to be oriented perpendicular to the cylinder axis. With increasing flow velocity, a transition to a prolate shape occurs for fluid vesicles, while vesicles with shear-elastic membranes (like red blood cells) transform into a coaxial parachute-like shape.
Microalga propels along vorticity direction in a shear flow
Chengala, Anwar; Hondzo, Miki; Sheng, Jian
2013-05-01
Using high-speed digital holographic microscopy and microfluidics, we discover that, when encountering fluid flow shear above a threshold, unicellular green alga Dunaliella primolecta migrates unambiguously in the cross-stream direction that is normal to the plane of shear and coincides with the local fluid flow vorticity. The flow shear drives motile microalgae to collectively migrate in a thin two-dimensional horizontal plane and consequently alters the spatial distribution of microalgal cells within a given suspension. This shear-induced algal migration differs substantially from periodic rotational motion of passive ellipsoids, known as Jeffery orbits, as well as gyrotaxis by bottom-heavy swimming microalgae in a shear flow due to the subtle interplay between torques generated by gravity and viscous shear. Our findings could facilitate mechanistic solutions for modeling planktonic thin layers and sustainable cultivation of microalgae for human nutrition and bioenergy feedstock.
Relativistic soliton-like collisionless ionization wave
Arefiev, Alexey; McCormick, Matthew; Quevedo, Hernan; Bengtson, Roger; Ditmire, Todd
2014-10-01
It has been observed in recent experiments with laser-irradiated gas jets that a plasma filament produced by the laser and containing energetic electrons can launch a relativistic ionization wave into ambient gas. Here we present a self-consistent theory that explains how a collisionless ionization wave can propagate in a self-sustaining regime. A population of hot electrons necessarily generates a sheath electric field at the plasma boundary. This field penetrates the ambient gas, ionizing the gas atoms and thus causing the plasma boundary to expand. We show that the motion of the newly generated electrons can form a potential well adjacent to the plasma boundary. The outwards motion of the well causes a bunch of energetic electrons to become trapped, while allowing the newly generated electrons to escape into the plasma without retaining much energy. The resulting soliton-like ionizing field structure propagates outwards with a bunch of hot electrons that maintain a strong sheath field despite significant plasma expansion. We also present 1D and 2D particle-in-cell simulations that illustrate the described mechanism. The simulations were performed using HPC resources provided by the Texas Advanced Computing Center. This work was supported by NNSA Contract No. DE-FC52-08NA28512 and U.S. DOE Contract No. DE-FG02-04ER54742.
Dynamic signatures of driven vortex motion.
Crabtree, G. W.; Kwok, W. K.; Lopez, D.; Olsson, R. J.; Paulius, L. M.; Petrean, A. M.; Safar, H.
1999-09-16
We probe the dynamic nature of driven vortex motion in superconductors with a new type of transport experiment. An inhomogeneous Lorentz driving force is applied to the sample, inducing vortex velocity gradients that distinguish the hydrodynamic motion of the vortex liquid from the elastic and-plastic motion of the vortex solid. We observe elastic depinning of the vortex lattice at the critical current, and shear induced plastic slip of the lattice at high Lorentz force gradients.
Relativistic causality and clockless circuits
Matherat, Philippe; 10.1145/2043643.2043650
2011-01-01
Time plays a crucial role in the performance of computing systems. The accurate modelling of logical devices, and of their physical implementations, requires an appropriate representation of time and of all properties that depend on this notion. The need for a proper model, particularly acute in the design of clockless delay-insensitive (DI) circuits, leads one to reconsider the classical descriptions of time and of the resulting order and causal relations satisfied by logical operations. This questioning meets the criticisms of classical spacetime formulated by Einstein when founding relativity theory and is answered by relativistic conceptions of time and causality. Applying this approach to clockless circuits and considering the trace formalism, we rewrite Udding's rules which characterize communications between DI components. We exhibit their intrinsic relation with relativistic causality. For that purpose, we introduce relativistic generalizations of traces, called R-traces, which provide a pertinent des...
Channeling of ultra-relativistic positrons in bent diamond crystals
R.G. Polozkov
2015-06-01
Full Text Available Results of numerical simulations of channeling of ultra-relativistic positrons are reported for straight and uniformly bent diamond crystals. The projectile trajectories in a crystal are computed using a newly developed module of the MBN Explorer package which simulates classical trajectories in a crystalline medium by integrating the relativistic equations of motion with account for the interaction between the projectile and the crystal atoms. The Monte Carlo method is employed to sample the incoming positrons and to account for thermal vibrations of the crystal atoms. The channeling parameters and emission spectra of incident positrons with a projecti le energy of 855 MeV along C(110 crystallographic planes are calculated for different bending radii of the crystal. Two features of the emission spectrum associated with positron oscillations in a channel and synchrotron radiation are studied as a function of crystal curvature.
Dielectric effects on Thomson scattering in a relativistic magnetized plasma
Bindslev, H.
1991-01-01
the absorption is small. Symmetry between variables relating to incident and scattered fields is demonstrated and shown to be in agreement with the reciprocity relation. Earlier results are confirmed in the cold plasma limit. Significant relativistic effects, of practical importance to the scattering......The effects of the dielectric properties of a relativistic magnetized plasma on the scattering of electromagnetic radiation by fluctuations in electron density are investigated. The origin of the density fluctuations is not considered. Expressions for the scattering cross-section and the scattered...... power accepted by the receiving antenna are derived for a plasma with spatial dispersion. The resulting expressions allow thermal motion to be included in the description of the plasma and remain valid for frequencies of the probing radiation in the region of omega(p) and omega(ce), provided...
Relativistic Lagrangian model of a nematic liquid crystal
Obukhov, Yuri N; Rubilar, Guillermo F
2012-01-01
We develop a relativistic variational model for a nematic liquid crystal interacting with the electromagnetic field. The constitutive relation for an anisotropic uniaxial diamagnetic and dielectric medium is analyzed. We discuss light wave propagation in this moving uniaxial medium, for which the corresponding optical metrics are identified explicitly. A Lagrangian for the coupled system of a nematic liquid crystal and the electromagnetic field is constructed. We derive a complete set of equations of motion for the system. The canonical energy-momentum and spin tensors are systematically obtained. We compare our results with those within the non-relativistic models. As an application of our general formalism, we discuss the so-called Abraham-Minkowski controversy on the momentum of light in a medium.
Relativistic energies for the SiC radical
Jia, Chun-Sheng [Southwest Petroleum University, State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu (China); Shui, Zheng-Wei [Southwest Petroleum University, School of Vocational and Technical Education, Nanchong (China)
2015-11-15
The analytical solutions of the Dirac equation with the modified Rosen-Morse potential energy model have been explored. Under the condition of the spin symmetry, we present the bound state energy equation. In the nonrelativistic limit, the relativistic energy equation becomes the nonrelativistic energy form deduced within the framework of the Schroedinger equation. We find that the relativistic effect of the relative motion of the ions leads to a little decrease in the vibrational energies when the vector potential is equal to the scalar potential for the electronic ground state of the SiC radical, while to an increase in those if the vector potential is greater than the scalar potential. (orig.)
Relativistic Corrections to the Zeeman Effect of Helium Atom
关晓旭; 李白文; 王治文
2002-01-01
The high-order relativistic corrections to the Zeeman g-factors of the helium atom are calculated. AII the relativistic correction terms and the term describing the motion of the mass centre are treated as perturbations. Most of our results are in good agreement with those of Yah and Drake [Phys. Rev. A 50 (1994)R1980/, who used the wavefunctions constructed by Hylleraas coordinates. For the correction δg of the g-factor of the 3 3P state in 4He, our result, 2.91415 × 10-7 a.u., should be more reasonable and accurate, although there are no experimental data available in the literature to compare.
Shearing stability of lubricants
Shiba, Y.; Gijyutsu, G.
1984-01-01
Shearing stabilities of lubricating oils containing a high mol. wt. polymer as a viscosity index improver were studied by use of ultrasound. The oils were degraded by cavitation and the degradation generally followed first order kinetics with the rate of degradation increasing with the intensity of the ultrasonic irradiation and the cumulative energy applied. The shear stability was mainly affected by the mol. wt. of the polymer additive and could be determined in a short time by mechanical shearing with ultrasound.
Shearing stability of lubricants
Shiba, Y.; Gijyutsu, G.
1984-03-01
Shearing stabilities of lubricating oils containing a high mol. wt. polymer as a viscosity index improver were studied by use of ultrasound. The oils were degraded by cavitation and the degradation generally followed first order kinetics with the rate of degradation increasing with the intensity of the ultrasonic irradiation and the cumulative energy applied. The shear stability was mainly affected by the mol. wt. of the polymer additive and could be determined in a short time by mechanical shearing with ultrasound.
Relativistic RPA in axial symmetry
Arteaga, D Pena; 10.1103/PhysRevC.77.034317
2009-01-01
Covariant density functional theory, in the framework of self-consistent Relativistic Mean Field (RMF) and Relativistic Random Phase approximation (RPA), is for the first time applied to axially deformed nuclei. The fully self-consistent RMF+RRPA equations are posed for the case of axial symmetry and non-linear energy functionals, and solved with the help of a new parallel code. Formal properties of RPA theory are studied and special care is taken in order to validate the proper decoupling of spurious modes and their influence on the physical response. Sample applications to the magnetic and electric dipole transitions in $^{20}$Ne are presented and analyzed.
Multifragmentation calculated with relativistic forces
Feldmeier, H; Papp, G
1995-01-01
A saturating hamiltonian is presented in a relativistically covariant formalism. The interaction is described by scalar and vector mesons, with coupling strengths adjusted to the nuclear matter. No explicit density depe ndence is assumed. The hamiltonian is applied in a QMD calculation to determine the fragment distribution in O + Br collision at different energies (50 -- 200 MeV/u) to test the applicability of the model at low energies. The results are compared with experiment and with previous non-relativistic calculations. PACS: 25.70Mn, 25.75.+r
Relativistic Stern-Gerlach Deflection
Talman, Richard
2016-01-01
Modern advances in polarized beam control should make it possible to accurately measure Stern-Gerlach (S-G) deflection of relativistic beams. Toward this end a relativistically covariant S-G formalism is developed that respects the opposite behavior under inversion of electric and magnetic fields. Not at all radical, or even new, this introduces a distinction between electric and magnetic fields that is not otherwise present in pure Maxwell theory. Experimental configurations (mainly using polarized electron beams passing through magnetic or electric quadrupoles) are described. Electron beam preparation and experimental methods needed to detect the extremely small deflections are discussed.
Vector Theory in Relativistic Thermodynamics
刘泽文
1994-01-01
It is pointed out that five defects occur in Planck-Einstein’s relativistic thermodynamics (P-E theory). A vector theory in relativistic thermodynamics (VTRT) is established. Defining the internal energy as a 4-vector, and supposing the entropy and the number of. particles to be invariants we have derived the transformations of all quantities, and subsequently got the Lagrangian and 4-D forms of thermodynamic laws. In order to test the new theory, several exact solutions with classical limits are given. The VTRT is free from the defects of the P-E theory.
Swinging of two-domains vesicles in shear flow
Viallat, Annie; Tusch, Simon; Khelloufi, Kamel; Leonetti, Marc
2014-11-01
Giant lipid vesicles and red blood cells in shear flow at low shear rates tank tread (TT) at small viscosity ratio between the inner particle volume and the external fluid, and flip or tumble (T) at large viscosity ratio. The phase diagram of motion of red blood cells is however much more complex. Swinging superimposes to TT, cells wobble and roll rather than tumble with increasing shear rate and present a shear-rate driven transition between TT to T. These features are attributed to the shear elasticity and the non spherical stress-free shape of the cell membrane, which stores shear elastic energy as a function of the relative position of its elements. We have created vesicles with a phase diagram of motion comparable to that of red blood cells by preparing membranes with two lipids and cholesterol. These membranes present two domains separated by a contact line. The line has a tension energy that depends on its relative position on the vesicle. Similarly to red blood cells, two-domains vesicles swing and wobble. An analytical model where line tension energy is added to the Keller and Skalak's model fits our experimental data without any adjustable parameter. Our experiments and model shed light on the motion of deformable particles in shear flow.
Frontiers in Relativistic Celestial Mechanics, Vol. 2, Applications and Experiments
Kopeikin, Sergei
2014-08-01
Relativistic celestial mechanics - investigating the motion celestial bodies under the influence of general relativity - is a major tool of modern experimental gravitational physics. With a wide range of prominent authors from the field, this two-volume series consists of reviews on a multitude of advanced topics in the area of relativistic celestial mechanics - starting from more classical topics such as the regime of asymptotically-flat spacetime, light propagation and celestial ephemerides, but also including its role in cosmology and alternative theories of gravity as well as modern experiments in this area. This second volume of a two-volume series covers applications of the theory as well as experimental verifications. From tools to determine light travel times in curved space-time to laser ranging between earth and moon and between satellites, and impacts on the definition of time scales and clock comparison techniques, a variety of effects is discussed. On the occasion of his 80-th birthday, these two volumes honor V. A. Brumberg - one of the pioneers in modern relativistic celestial mechanics. Contributions include: J. Simon, A. Fienga: Victor Brumberg and the French school of analytical celestial mechanics T. Fukushima: Elliptic functions and elliptic integrals for celestial mechanics and dynamical astronomy P. Teyssandier: New tools for determining the light travel time in static, spherically symmetric spacetimes beyond the order G2 J. Müller, L. Biskupek, F. Hofmann and E. Mai: Lunar laser ranging and relativity N. Wex: Testing relativistic celestial mechanics with radio pulsars I. Ciufolini et al.: Dragging of inertial frames, fundamental physics, and satellite laser ranging G. Petit, P. Wolf, P. Delva: Atomic time, clocks, and clock comparisons in relativistic spacetime: a review
EFFECT OF INTERACTING RAREFACTION WAVES ON RELATIVISTICALLY HOT JETS
Matsumoto, Jin; Shibata, Kazunari [Kwasan and Hida Observatories, Kyoto University, Kyoto (Japan); Masada, Youhei, E-mail: jin@kusastro.kyoto-u.ac.jp [Graduate School of System Informatics, Department of Computational Science, Kobe University, Kobe (Japan)
2012-06-01
The effect of rarefaction acceleration on the propagation dynamics and structure of relativistically hot jets is studied through relativistic hydrodynamic simulations. We emphasize the nonlinear interaction of rarefaction waves excited at the interface between a cylindrical jet and the surrounding medium. From simplified one-dimensional (1D) models with radial jet structure, we find that a decrease in the relativistic pressure due to the interacting rarefaction waves in the central zone of the jet transiently yields a more powerful boost of the bulk jet than that expected from single rarefaction acceleration. This leads to a cyclic in situ energy conversion between thermal and bulk kinetic energies, which induces radial oscillating motion of the jet. The oscillation timescale is characterized by the initial pressure ratio of the jet to the ambient medium and follows a simple scaling relation, {tau}{sub oscillation}{proportional_to}(P{sub jet,0}/P{sub amb,0}){sup 1/2}. Extended two-dimensional simulations confirm that this radial oscillating motion in the 1D system manifests as modulation of the structure of the jet in a more realistic situation where a relativistically hot jet propagates through an ambient medium. We find that when the ambient medium has a power-law pressure distribution, the size of the reconfinement region along the propagation direction of the jet in the modulation structure {lambda} evolves according to a self-similar relation {lambda}{proportional_to}t{sup {alpha}/2}, where {alpha} is the power-law index of the pressure distribution.
Relativistic Celestial Mechanics of the Solar System
Kopeikin, Sergei; Efroimsky, Michael; Kaplan, George
2011-09-01
objects like vectors and tensors, for example, the velocity, acceleration, force, electromagnetic field, and so on. Chapter 3 is devoted to general relativity. It explains the main ideas of the tensor calculus on curved manifolds, the theory of the affine connection and parallel transport, and the mathematical and physical foundations of Einstein's approach to gravity. Within this chapter, we have also included topics which are not well covered in standard books on general relativity: namely, the variational analysis on manifolds and the multipolar expansion of gravitational radiation. Chapter 4 introduces a detailed theory of relativistic reference frames and time scales in an N-body system comprised of massive, extended bodies - like our own solar system. Here, we go beyond general relativity and base our analysis on the scalar-tensor theory of gravity. This allows us to extend the domain of applicability of the IAU resolutions on relativistic reference frames, which in their original form were applicable only in the framework of general relativity. We explain the principles of construction of reference frames, and explore their relationship with the solutions of the gravitational field equations. We also discuss the post-Newtonian multipolemoments of the gravitational field from the viewpoint of global and local coordinates. Chapter 5 discusses the principles of derivation of transformations between reference frames in relativistic celestial mechanics. The standard parameterized post-Newtonian (PPN) formalism by K. Nordtevdt and C. Will operates with a single coordinate frame covering the entire N-body system, but it is insufficient for discussion of more subtle relativistic effects showing up in orbital and rotational motion of extended bodies. Consideration of such effects require, besides the global frame, the introduction of a set of local frames needed to properly treat each body and its internal structure and dynamics. The entire set of global and local frames
Gilbert, P. H.; Giacomin, A. J.
2016-10-01
Recent work has focused on deepening our understanding of the molecular origins of the higher harmonics that arise in the shear stress response of polymeric liquids in large-amplitude oscillatory shear flow. For instance, these higher harmonics have been explained by just considering the orientation distribution of rigid dumbbells suspended in a Newtonian solvent. These dumbbells, when in dilute suspension, form the simplest relevant molecular model of polymer viscoelasticity, and this model specifically neglects interactions between the polymer molecules [R. B. Bird et al., "Dilute rigid dumbbell suspensions in large-amplitude oscillatory shear flow: Shear stress response," J. Chem. Phys. 140, 074904 (2014)]. In this paper, we explore these interactions by examining the Curtiss-Bird model, a kinetic molecular theory designed specifically to account for the restricted motions that arise when polymer chains are concentrated, thus interacting and specifically, entangled. We begin our comparison using a heretofore ignored explicit analytical solution [X.-J. Fan and R. B. Bird, "A kinetic theory for polymer melts. VI. Calculation of additional material functions," J. Non-Newtonian Fluid Mech. 15, 341 (1984)]. For concentrated systems, the chain motion transverse to the chain axis is more restricted than along the axis. This anisotropy is described by the link tension coefficient, ɛ, for which several special cases arise: ɛ = 0 corresponds to reptation, ɛ > 1/8 to rod-climbing, 1/5 ≤ ɛ ≤ 3/4 to reasonable predictions for shear-thinning in steady simple shear flow, and ɛ = 1 to the dilute solution without hydrodynamic interaction. In this paper, we examine the shapes of the shear stress versus shear rate loops for the special cases ɛ = (" separators=" 0 , 1 / 8 , 3 / 8 , 1 ) , and we compare these with those of rigid dumbbell and reptation model predictions.
Bulk viscosity-driven suppression of shear viscosity effects on the flow harmonics at RHIC
Noronha-Hostler, J; Grassi, F
2014-01-01
The interplay between shear and bulk viscosities on the flow harmonics, $v_n$'s, at RHIC is investigated using the newly developed relativistic 2+1 hydrodynamical code v-USPhydro that includes bulk and shear viscosity effects both in the hydrodynamic evolution and also at freeze-out. While shear viscosity is known to attenuate the flow harmonics, we find that the inclusion of bulk viscosity decreases the shear viscosity-induced suppression of the flow harmonics bringing them closer to their values in ideal hydrodynamical calculations. Depending on the value of the bulk viscosity to entropy density ratio, $\\zeta/s$, in the quark-gluon plasma, the bulk viscosity-driven suppression of shear viscosity effects on the flow harmonics may require a re-evaluation of the previous estimates of the shear viscosity to entropy density ratio, $\\eta/s$, of the quark-gluon plasma previously extracted by comparing hydrodynamic calculations to heavy ion data.
Matsas, G E A
2003-01-01
We investigate and solve in the context of General Relativity the apparent paradox which appears when bodies floating in a background fluid are set in relativistic motion. Suppose some macroscopic body, say, a submarine designed to lie just in equilibrium when it rests (totally) immersed in a certain background fluid. The puzzle arises when different observers are asked to describe what is expected to happen when the submarine is given some high velocity parallel to the direction of the fluid surface. On the one hand, according to observers at rest with the fluid, the submarine would contract and, thus, sink as a consequence of the density increase. On the other hand, mariners at rest with the submarine using an analogous reasoning for the fluid elements would reach the opposite conclusion. The general relativistic extension of the Arquimedes law for moving bodies shows that the submarine sinks.
Vujanovic, Gojko; Denicol, Gabriel S; Luzum, Matthew; Jeon, Sangyong; Gale, Charles
2016-01-01
The penetrating nature of electromagnetic signals makes them suitable probes to explore the properties of the strongly-interacting medium created in relativistic nuclear collisions. We examine the effects of the initial conditions and shear relaxation time on the spectra and flow coefficients of electromagnetic probes, using an event-by-event 3+1D viscous hydrodynamic simulation (MUSIC).
Lopez, Rodrigo A.; Munoz, Victor [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Asenjo, Felipe A. [Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States); Alejandro Valdivia, J. [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y la Nanotecnologia, CEDENNA, Santiago (Chile)
2012-08-15
The nonlinear evolution of a circularly polarized electromagnetic wave in an electron-positron plasma propagating along a constant background magnetic field is considered, by studying its parametric decays. Relativistic effects, of the particle motion in the wave field and of the plasma temperature, are included to obtain the dispersion relation of the decays. The exact dispersion relation of the pump wave has been previously calculated within the context of a relativistic fluid theory and presents two branches: an electromagnetic and an Alfven one. We investigate the parametric decays for the pump wave in these two branches, including the anomalous dispersion zone of the Alfven branch where the group velocity is negative. We solve the nonlinear dispersion relation for different pump wave amplitudes and plasma temperatures, finding various resonant and nonresonant wave couplings. We are able to identify these couplings and study their behavior as we modify the plasma parameters. Some of these couplings are suppressed for larger amplitudes or temperatures. We also find two kinds of modulational instabilities, one involving two sideband daughter waves and another involving a forward-propagating electroacoustic mode and a sideband daughter wave.
Relativistic Hydrodynamics for Heavy-Ion Collisions
Ollitrault, Jean-Yves
2008-01-01
Relativistic hydrodynamics is essential to our current understanding of nucleus-nucleus collisions at ultrarelativistic energies (current experiments at the Relativistic Heavy Ion Collider, forthcoming experiments at the CERN Large Hadron Collider). This is an introduction to relativistic hydrodynamics for graduate students. It includes a detailed…
On the spectrum of relativistic Schrödinger equation in finite differences
Berezin, V A; Neronov, Andrii Yu
1999-01-01
We develop a method for constructing asymptotic solutions of finite-difference equations and implement it to a relativistic Schroedinger equation which describes motion of a selfgravitating spherically symmetric dust shell. Exact mass spectrum of black hole formed due to the collapse of the shell is determined from the analysis of asymptotic solutions of the equation.
A Dynamical Approach to the Exterior Geometry of a Perfect Fluid as a Relativistic Star
Fathi, Mohsen
2011-01-01
The aim of this article is to compare some of the solution classes, which were presented for a perfect charged fluid in Ref. [8], through studying the motion of a test charged particle on a relativistic charged star. We will show that how the interior solutions of such star, can affect its exterior geometry, by illustrating the corresponding effective potentials.
Bargmann-Michel-Telegdi equation and one-particle relativistic approach
Della Selva, A; Masperi, L
1995-01-01
A reexamination of the semiclassical approach of the relativistic electron indicates a possible variation of its helicity for electric and magnetic static fields applied along its global motion due to zitterbewegung effects, proportional to the anomalous part of the magnetic moment.
An introduction to relativistic magnetohydrodynamics I. The force-free approximation
Karas, Vladimír
2005-12-01
This lecture summarizes basic equations of relativistic magnetohydrodynamics (MHD). The aim of the lecture is to present important relations and approximations that have been often employed and found useful in the astrophysical context, namely, in situations when plasma motion is governed by magnetohydrodynamic and gravitational effects competing with each other near a black hole.
Luo Shao-Kai
2007-01-01
For a relativistic holonomic nonconservative system, by using the Noether symmetry, a new non-Noether conserved quantity is given under general infinitesimal transformations of groups. On the basis of the theory of invariance of differential equations of motion under general infinitesimal transformations, we construct the relativistic Noether symmetry, Lie symmetry and the condition under which the Noether symmetry is a Lie symmetry under general infinitesimal transformations. By using the Noether symmetry, a new relativistic non-Noether conserved quantity is given which only depends on the variables t, qs and (q)s. An example is given to illustrate the application of the results.
Microscopic Processes in Relativistic Jets
Nishikawa, K.-I.; Hardee, P.; Mizuno, Y.; Medvedev, M.; Zhang, B.; Nordlund, A.; Fredricksen, J.; Sol, H.; Niemiec, J.; Lyubarsky, Y.;
2008-01-01
Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electro-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the collisionless relativistic shock particle acceleration is due to plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.
The Highest Redshift Relativistic Jets
Cheung, C.C.; Stawarz, L.; Siemiginowska, A.; Harris, D.E; Schwartz, D.A.; Wardle, J.F.C.; Gobeille, D.; Lee, N.P.
2007-12-18
We describe our efforts to understand large-scale (10's-100's kpc) relativistic jet systems through observations of the highest-redshift quasars. Results from a VLA survey search for radio jets in {approx} 30 z > 3.4 quasars are described along with new Chandra observations of 4 selected targets.
Circular polarization in relativistic jets
Macquart, JP
2003-01-01
Circular polarization is observed in some relativistic jet sources at radio wavelengths. It is largely associated with activity in the cores of the radio sources, is highly variable, and is strongest during ejection episodes. VLBI imaging and interstellar scintillation arguments show that the degree
Eliasson, B.; Papadopoulos, K.
2017-10-01
A theoretical study of the propagation of left-hand polarized shear Alfvén waves in spatially decreasing magnetic field geometries near the EMIC resonance, including the spectrum and amplitude of the mode converted EMIC waves and the pitch angle scattering of relativistic electrons transiting the resonant region, is presented. The objective of the paper is to motivate an experimental study of the subject using the UCLA LAPD chamber. The results are relevant in exploring the possibility that shear Alfvén waves strategically injected into the radiation belts using either ionospheric heating from ground based RF transmitters or injected by transmitters based on space platforms can enhance the precipitation rate of trapped relativistic electrons. Effects of multi-ionic composition are also investigated.
Fast lattice Boltzmann solver for relativistic hydrodynamics.
Mendoza, M; Boghosian, B M; Herrmann, H J; Succi, S
2010-07-01
A lattice Boltzmann formulation for relativistic fluids is presented and numerically validated through quantitative comparison with recent hydrodynamic simulations of relativistic fluids. In order to illustrate its capability to handle complex geometries, the scheme is also applied to the case of a three-dimensional relativistic shock wave, generated by a supernova explosion, impacting on a massive interstellar cloud. This formulation opens up the possibility of exporting the proven advantages of lattice Boltzmann methods, namely, computational efficiency and easy handling of complex geometries, to the context of (mildly) relativistic fluid dynamics at large, from quark-gluon plasmas up to supernovae with relativistic outflows.
Eliazar, Iddo I., E-mail: eliazar@post.tau.ac.il [Holon Institute of Technology, P.O. Box 305, Holon 58102 (Israel); Shlesinger, Michael F., E-mail: mike.shlesinger@navy.mil [Office of Naval Research, Code 30, 875 N. Randolph St., Arlington, VA 22203 (United States)
2013-06-10
Brownian motion is the archetypal model for random transport processes in science and engineering. Brownian motion displays neither wild fluctuations (the “Noah effect”), nor long-range correlations (the “Joseph effect”). The quintessential model for processes displaying the Noah effect is Lévy motion, the quintessential model for processes displaying the Joseph effect is fractional Brownian motion, and the prototypical model for processes displaying both the Noah and Joseph effects is fractional Lévy motion. In this paper we review these four random-motion models–henceforth termed “fractional motions” –via a unified physical setting that is based on Langevin’s equation, the Einstein–Smoluchowski paradigm, and stochastic scaling limits. The unified setting explains the universal macroscopic emergence of fractional motions, and predicts–according to microscopic-level details–which of the four fractional motions will emerge on the macroscopic level. The statistical properties of fractional motions are classified and parametrized by two exponents—a “Noah exponent” governing their fluctuations, and a “Joseph exponent” governing their dispersions and correlations. This self-contained review provides a concise and cohesive introduction to fractional motions.
A Relativistic Long-term Precession of the Earth
Tang, K.
2016-05-01
A long-term precession represents a secular motion of the ecliptic and th equator in a long time interval. With Vondrák et al. (2011), we assume that precession covers all periods longer than 100 centuries, while the shorter ones are included in the nutation. This thesis deals with the long-term precession in a relativistic framework. Compared with the P03 precession theory which is only valid for several centuries around the epoch J2000.0, the new theory better reflects the realistic long-term behavior of precession. All previous works are not fully consistent with General Relativity. They only consider the dominant relativistic corrections: the first-order post-Newtonian corrections due to the Sun and the geodetic precession. Their standard way to account for the geodetic precession is to solve the purely Newtonian equations of rotational motion and add the geodetic precession as a correction to the solution. In this thesis, we aim to determine the acceleration of the SSB from astrometric and geodetic observations obtained by Very Long Baseline Interferometry (VLBI), which is a technique using the telescopes globally distributed on the Earth to observe a radio source simultaneously, and with the capacity of angular positioning for compact radio sources at 10-milliarcsecond level. The method of the global solution, which allows the acceleration vector to be estimated as a global parameter in the data analysis, is developed. Through the formal error given by the solution, this method shows directly the VLBI observations' capability to constrain the acceleration of the SSB, and demonstrates the significance level of the result. In the next step, the impact of the acceleration on the ICRS is studied in order to obtain the correction of the celestial reference frame (CRF) orientation. Recently, Klioner, Gerlach, and Soffel (2010) have constructed a relativistic theory of Earth's rotation. According to the post-Newtonian equations of rotational motion given by Klioner
Naderyan, Vahid; Hickey, Craig J.; Raspet, Richard
2016-02-01
Wind noise is a problem in seismic surveys and can mask the seismic signals at low frequency. This research investigates ground motions caused by wind pressure and shear stress perturbations on the ground surface. A prediction of the ground displacement spectra using the measured ground properties and predicted pressure and shear stress at the ground surface is developed. Field measurements are conducted at a site having a flat terrain and low ambient seismic noise. Triaxial geophones are deployed at different depths to study the wind-induced ground vibrations as a function of depth and wind velocity. Comparison of the predicted to the measured wind-induced ground displacement spectra shows good agreement for the vertical component but significant underprediction for the horizontal components. To validate the theoretical model, a test experiment is designed to exert controlled normal pressure and shear stress on the ground using a vertical and a horizontal mass-spring apparatus. This experiment verifies the linear elastic rheology and the quasi-static displacements assumptions of the model. The results indicate that the existing surface shear stress models significantly underestimate the wind shear stress at the ground surface and the amplitude of the fluctuation shear stress must be of the same order of magnitude as the normal pressure. Measurement results show that mounting the geophones flush with the ground provides a significant reduction in wind noise on all three components of the geophone. Further reduction in wind noise with depth of burial is small for depths up to 40 cm.
Relativistic quantum level-spacing statistics in chaotic graphene billiards.
Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso
2010-05-01
An outstanding problem in quantum nonlinear dynamics concerns about the energy-level statistics in experimentally accessible relativistic quantum systems. We demonstrate, using chaotic graphene confinements where electronic motions are governed by the Dirac equation in the low-energy regime, that the level-spacing statistics are those given by Gaussian orthogonal ensemble (GOE) random matrices. Weak magnetic field can change the level-spacing statistics to those of Gaussian unitary ensemble for electrons in graphene. For sufficiently strong magnetic field, the GOE statistics are restored due to the appearance of Landau levels.
Classical and relativistic flux of energy conservation in astrophysical jets
Zaninetti, L
2016-01-01
The conservation of the energy flux in turbulent jets which propagate in the intergalactic medium (IGM) allows deducing the law of motion in the classical and relativistic cases. Three types of IGM are considered: constant density, hyperbolic and inverse power law decrease of density. An analytical law for the evolution of the magnetic field along the radio-jets is deduced using a linear relation between the magnetic pressure and the rest density. Astrophysical applications are made to the centerline intensity of synchrotron emission in NGC315 and to the magnetic field of 3C273.
Magnonic analog of relativistic Zitterbewegung in an antiferromagnetic spin chain
Wang, Weiwei; Gu, Chenjie; Zhou, Yan; Fangohr, Hans
2017-07-01
We theoretically investigate the spin-wave (magnon) excitations in a classical antiferromagnetic spin chain with easy-axis anisotropy. We obtain a Dirac-like equation by linearizing the Landau-Lifshitz-Gilbert equation in this antiferromagnetic system, in contrast to the ferromagnetic system in which a Schrödinger-type equation is derived. The Hamiltonian operator in the Dirac-like equation is a pseudo-Hermitian. We compute and demonstrate relativistic Zitterbewegung (trembling motion) in the antiferromagnetic spin chain by measuring the expectation values of the wave-packet position.
Upward swimming of a sperm cell in shear flow.
Omori, Toshihiro; Ishikawa, Takuji
2016-03-01
Mammalian sperm cells are required to swim over long distances, typically around 1000-fold their own length. They must orient themselves and maintain a swimming motion to reach the ovum, or egg cell. Although the mechanism of long-distance navigation is still unclear, one possible mechanism, rheotaxis, was reported recently. This work investigates the mechanism of the rheotaxis in detail by simulating the motions of a sperm cell in shear flow adjacent to a flat surface. A phase diagram was developed to show the sperm's swimming motion under different shear rates, and for varying flagellum waveform conditions. The results showed that, under shear flow, the sperm is able to hydrodynamically change its swimming direction, allowing it to swim upwards against the flow, which suggests that the upward swimming of sperm cells can be explained using fluid mechanics, and this can then be used to further understand physiology of sperm cell navigation.
Upward swimming of a sperm cell in shear flow
Omori, Toshihiro; Ishikawa, Takuji
2016-03-01
Mammalian sperm cells are required to swim over long distances, typically around 1000-fold their own length. They must orient themselves and maintain a swimming motion to reach the ovum, or egg cell. Although the mechanism of long-distance navigation is still unclear, one possible mechanism, rheotaxis, was reported recently. This work investigates the mechanism of the rheotaxis in detail by simulating the motions of a sperm cell in shear flow adjacent to a flat surface. A phase diagram was developed to show the sperm's swimming motion under different shear rates, and for varying flagellum waveform conditions. The results showed that, under shear flow, the sperm is able to hydrodynamically change its swimming direction, allowing it to swim upwards against the flow, which suggests that the upward swimming of sperm cells can be explained using fluid mechanics, and this can then be used to further understand physiology of sperm cell navigation.
Zhang, Weiqun; Wang, Peng
2008-01-01
Magnetic field strengths inferred for relativistic outflows including gamma-ray bursts (GRB) and active galactic nuclei (AGN) are larger than naively expected by orders of magnitude. We present three-dimensional relativistic magnetohydrodynamics (MHD) simulations demonstrating amplification and saturation of magnetic field by a macroscopic turbulent dynamo triggered by the Kelvin-Helmholtz shear instability. We find rapid growth of electromagnetic energy due to the stretching and folding of field lines in the turbulent velocity field resulting from non-linear development of the instability. Using conditions relevant for GRB internal shocks and late phases of GRB afterglow, we obtain amplification of the electromagnetic energy fraction to $\\epsilon_B \\sim 5 \\times 10^{-3}$. This value decays slowly after the shear is dissipated and appears to be largely independent of the initial field strength. The conditions required for operation of the dynamo are the presence of velocity shear and some seed magnetization b...
Motion of charged particles in a knotted electromagnetic field
Arrayas, M; Trueba, J L, E-mail: joseluis.trueba@urjc.e [Area de Electromagnetismo, Universidad Rey Juan Carlos, Camino del Molino s/n, 28943 Fuenlabrada, Madrid (Spain)
2010-06-11
In this paper we consider the classical relativistic motion of charged particles in a knotted electromagnetic field. After reviewing how to construct electromagnetic knots from maps between the three-sphere and the two-sphere, we introduce a mean quadratic radius of the energy density distribution in order to study some properties of this field. We study the classical relativistic motion of electrons in the electromagnetic field of the Hopf map, and compute their trajectories. It is observed that these electrons initially at rest are strongly accelerated by the electromagnetic force, becoming ultrarelativistic in a period of time that depends on the knot energy and size.
Shear wave elastography with a new reliability indicator
Christoph F. Dietrich
2016-09-01
Full Text Available Non-invasive methods for liver stiffness assessment have been introduced over recent years. Of these, two main methods for estimating liver fibrosis using ultrasound elastography have become established in clinical practice: shear wave elastography and quasi-static or strain elastography. Shear waves are waves with a motion perpendicular (lateral to the direction of the generating force. Shear waves travel relatively slowly (between 1 and 10 m/s. The stiffness of the liver tissue can be assessed based on shear wave velocity (the stiffness increases with the speed. The European Federation of Societies for Ultrasound in Medicine and Biology has published Guidelines and Recommendations that describe these technologies and provide recommendations for their clinical use. Most of the data available to date has been published using the Fibroscan (Echosens, France, point shear wave speed measurement using an acoustic radiation force impulse (Siemens, Germany and 2D shear wave elastography using the Aixplorer (SuperSonic Imagine, France. More recently, also other manufacturers have introduced shear wave elastography technology into the market. A comparison of data obtained using different techniques for shear wave propagation and velocity measurement is of key interest for future studies, recommendations and guidelines. Here, we present a recently introduced shear wave elastography technology from Hitachi and discuss its reproducibility and comparability to the already established technologies.
Bay, Niels; Bjerregaard, Henrik; Petersen, Søren. B;
1994-01-01
The present paper describes an investigation of roll bonding an AlZn alloy to mild steel. Application of cross shear roll bonding, where the two equal sized rolls run with different peripheral speed, is shown to give better bond strength than conventional roll bonding. Improvements of up to 20......-23% in bond strength are found and full bond strength is obtained at a reduction of 50% whereas 65% is required in case of conventional roll bonding. Pseudo cross shear roll bonding, where the cross shear effect is obtained by running two equal sized rolls with different speed, gives the same results....
Ruda, Mitchell C [Tucson, AZ; Greynolds, Alan W [Tucson, AZ; Stuhlinger, Tilman W [Tucson, AZ
2009-07-14
One or more disc-shaped angular shear plates each include a region thereon having a thickness that varies with a nonlinear function. For the case of two such shear plates, they are positioned in a facing relationship and rotated relative to each other. Light passing through the variable thickness regions in the angular plates is refracted. By properly timing the relative rotation of the plates and by the use of an appropriate polynomial function for the thickness of the shear plate, light passing therethrough can be focused at variable positions.
Opportunities for shear energy scaling in bulk acoustic wave resonators.
Jose, Sumy; Hueting, Raymond J E
2014-10-01
An important energy loss contribution in bulk acoustic wave resonators is formed by so-called shear waves, which are transversal waves that propagate vertically through the devices with a horizontal motion. In this work, we report for the first time scaling of the shear-confined spots, i.e., spots containing a high concentration of shear wave displacement, controlled by the frame region width at the edge of the resonator. We also demonstrate a novel methodology to arrive at an optimum frame region width for spurious mode suppression and shear wave confinement. This methodology makes use of dispersion curves obtained from finite-element method (FEM) eigenfrequency simulations for arriving at an optimum frame region width. The frame region optimization is demonstrated for solidly mounted resonators employing several shear wave optimized reflector stacks. Finally, the FEM simulation results are compared with measurements for resonators with Ta2O5/ SiO2 stacks showing suppression of the spurious modes.
Suppression of a kinematic dynamo by large shear
Sood, Aditi; Kim, Eun-jin
2016-01-01
We numerically solve the magnetic induction equation in a spherical shell geometry, with a kinematically prescribed axisymmetric flow that consists of a superposition of a small-scale helical flow and a large-scale shear flow. The small-scale flow is chosen to be a local analog of the classical Roberts cells, consisting of strongly helical vortex rolls. The large-scale flow is a shearing motion in either the radial or the latitudinal directions. In the absence of large-scale shear, the small-scale flow is an efficient dynamo, in agreement with previous results. Adding increasingly large shear flows strongly suppresses the dynamo efficiency, indicating that shear is not always a favourable ingredient in dynamo action.
Impact of Vertical Wind Shear on Tropical Cyclone Rainfall
Cecil, Dan; Marchok, Tim
2014-01-01
While tropical cyclone rainfall has a large axisymmetric component, previous observational and theoretical studies have shown that environmental vertical wind shear leads to an asymmetric component of the vertical motion and precipitation fields. Composites consistently depict a precipitation enhancement downshear and also cyclonically downwind from the downshear direction. For consistence with much of the literature and with Northern Hemisphere observations, this is subsequently referred to as "Downshear-Left". Stronger shear magnitudes are associated with greater amplitude precipitation asymmetries. Recent work has reinforced the prior findings, and explored details of the response of the precipitation and kinematic fields to environmental vertical wind shear. Much of this research has focused on tropical cyclones away from land, to limit the influence of other processes that might distort the signal related to vertical wind shear. Recent evidence does suggest vertical wind shear can also play a major role in precipitation asymmetries during and after landfall.
High Resolution Shear Profile Measurements in Entangled Polymers
Hayes, Keesha A.
2008-11-17
We use confocal microscopy and particle image velocimetry to visualize motion of 250-300 nm. fluorescent tracer particles in entangled polymers subject to a rectilinear shear flow. Our results show linear velocity profiles in polymer solutions spanning a wide range of molecular weights and number of entanglements (8≤Z≤56), but reveal large differences between the imposed and measured shear rates. These findings disagree with recent reports that shear banding is a characteristic flow response of entangled polymers, and instead point to interfacial slip as an important source of strain loss. © 2008 The American Physical Society.
Orientational Distribution of Fibres in Sheared Fibre Suspensions
KU Xiao-Ke; LIN Jian-Zhong
2007-01-01
Motion of fibres in sheared fibre suspensions is simulated numerically by using the lattice Boltzmann method. The orientational distributions of the fibres are presented for different Reynolds numbers, Stokes numbers, shear rate and fibre aspect ratio. Some computational results are compared with the experimental data of pipe Bow, and the qualitative agreement is achieved. The results show that the orientational distributions are greatly affected by the Reynolds numbers, while relatively insensitive to the fibre aspect ratio. The Stokes number and shear rate have obvious influence on the orientation distribution.
Relativistic electron beams above thunderclouds
Füellekrug, M.; Roussel-Dupre, R.; Symbalisty, E. M. D.;
2011-01-01
Non-luminous relativistic electron beams above thunderclouds have been detected by the radio signals of low frequency similar to 40-400 kHz which they radiate. The electron beams occur similar to 2-9 ms after positive cloud-to-ground lightning discharges at heights between similar to 22-72 km above...... thunderclouds. Intense positive lightning discharges can also cause sprites which occur either above or prior to the electron beam. One electron beam was detected without any luminous sprite which suggests that electron beams may also occur independently of sprites. Numerical simulations show that beams...... of electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of similar to 7MeV to transport a total charge of similar to-10mC upwards. The impulsive current similar to 3 x 10(-3) Am-2 associated with relativistic electron beams above thunderclouds...
Relativistic electron beams above thunderclouds
M. Füllekrug
2011-05-01
Full Text Available Non-luminous relativistic electron beams above thunderclouds are detected by radio remote sensing with low frequency radio signals from 40–400 kHz. The electron beams occur 2–9 ms after positive cloud-to-ground lightning discharges at heights between 22–72 km above thunderclouds. The positive lightning discharges also cause sprites which occur either above or before the electron beam. One electron beam was detected without any luminous sprite occurrence which suggests that electron beams may also occur independently. Numerical simulations show that the beamed electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of 7 MeV to transport a total charge of 10 mC upwards. The impulsive current associated with relativistic electron beams above thunderclouds is directed downwards and needs to be considered as a novel element of the global atmospheric electric circuit.
Relativistic stars in bigravity theory
Aoki, Katsuki; Tanabe, Makoto
2016-01-01
Assuming static and spherically symmetric spacetimes in the ghost-free bigravity theory, we find a relativistic star solution, which is very close to that in general relativity. The coupling constants are classified into two classes: Class [I] and Class [II]. Although the Vainshtein screening mechanism is found in the weak gravitational field for both classes, we find that there is no regular solution beyond the critical value of the compactness in Class [I]. This implies that the maximum mass of a neutron star in Class [I] becomes much smaller than that in GR. On the other hand, for the solution in Class [II], the Vainshtein screening mechanism works well even in a relativistic star and the result in GR is recovered.
Relativistic Hydrodynamics on Graphic Cards
Gerhard, Jochen; Bleicher, Marcus
2012-01-01
We show how to accelerate relativistic hydrodynamics simulations using graphic cards (graphic processing units, GPUs). These improvements are of highest relevance e.g. to the field of high-energetic nucleus-nucleus collisions at RHIC and LHC where (ideal and dissipative) relativistic hydrodynamics is used to calculate the evolution of hot and dense QCD matter. The results reported here are based on the Sharp And Smooth Transport Algorithm (SHASTA), which is employed in many hydrodynamical models and hybrid simulation packages, e.g. the Ultrarelativistic Quantum Molecular Dynamics model (UrQMD). We have redesigned the SHASTA using the OpenCL computing framework to work on accelerators like graphic processing units (GPUs) as well as on multi-core processors. With the redesign of the algorithm the hydrodynamic calculations have been accelerated by a factor 160 allowing for event-by-event calculations and better statistics in hybrid calculations.
A relativistic symmetry in nuclei
Ginocchio, J N [MS B283, Theoretical Division, Los Alamos National Laboratory Los Alamos, New Mexico 87545 (Mexico)
2007-11-15
We review some of the empirical and theoretical evidence supporting pseudospin symmetry in nuclei as a relativistic symmetry. We review the case that the eigenfunctions of realistic relativistic nuclear mean fields approximately conserve pseudospin symmetry in nuclei. We discuss the implications of pseudospin symmetry for magnetic dipole transitions and Gamow-Teller transitions between states in pseudospin doublets. We explore a more fundamental rationale for pseudospin symmetry in terms of quantum chromodynamics (QCD), the basic theory of the strong interactions. We show that pseudospin symmetry in nuclei implies spin symmetry for an anti-nucleon in a nuclear environment. We also discuss the future and what role pseudospin symmetry may be expected to play in an effective field theory of nucleons.
Fluctuations in Relativistic Causal Hydrodynamics
Kumar, Avdhesh; Mishra, Ananta P
2013-01-01
The formalism to calculate the hydrodynamics fluctuation using the quasi-stationary fluctuation theory of Onsager to the relativistic Navier-Stokes hydrodynamics is already known. In this work we calculate hydrodynamic fluctuations in relativistic causal theory of Muller, Israel and Stewart and other related causal hydrodynamic theories. We show that expressions for the Onsager coefficients and the correlation functions have form similar to the ones obtained by using Navier-Stokes equation. However, temporal evolution of the correlation functions obtained using MIS and the other causal theories can be significantly different than the correlation functions obtained using the Navier-Stokes equation. Finally, as an illustrative example, we explicitly plot the correlation functions obtained using the causal-hydrodynamics theories and compare them with correlation functions obtained by earlier authors using the expanding boost-invariant (Bjorken) flows.
Induced Compton Scattering by Relativistic Electrons in Magnetized Astrophysical Plasmas.
Sincell, Mark William
1994-01-01
The effects of stimulated scattering on high brightness temperature radiation are studied in two important contexts. In the first case, we assume that the radiation is confined to a collimated beam traversing a relativistically streaming magnetized plasma. When the plasma is cold in the bulk frame, stimulated scattering is only significant if the angle between the photon motion and the plasma velocity is less than gamma^{-1} , where gamma is the bulk Lorentz factor. Under the assumption that the center of the photon beam is parallel to the bulk motion, we calculate the scattering rate as a function of the angular spread of the beam and gamma. Magnetization changes the photon recoil, without which stimulated scattering has no effect. It also introduces a strong dependence on frequency and polarization: if the photon frequency matches the electron cyclotron frequency, the scattering rate of photons polarized perpendicular to the magnetic field can be substantially enhanced relative to Thomson, and if the photon frequency is much less than the cyclotron frequency the scattering is suppressed. Applying these calculations to pulsars, we find that stimulated scattering of the radio beam in the magnetized wind believed to exist outside the light cylinder can substantially alter the spectrum and polarization state of the radio signal. We suggest that the scattering rate is so high in some pulsars that the ability of the radio signal to penetrate the pulsar magnetosphere requires modification of either the conventional model of the magnetosphere or assumptions about the effects of stimulated scattering upon a beam. In the second case, we present a model of the radio emission from synchrotron self-absorbed sources, including the effects of induced Compton scattering by the relativistic electrons in the source. Order of magnitude estimates show that stimulated scattering becomes the dominant absorption process when (kTB/m ec^2)tau_{T }_sp{~}> 0.1. Numerical simulations
Avancini, S.S.; Marinelli, J.R. [Universidade Federal de Santa Catarina Florianopolis, Depto de Fisica - CFM, Florianopolis (Brazil); Carlson, B.V. [Instituto Tecnologico de Aeronautica, Sao Jose dos Campos (Brazil)
2013-06-15
Relativistic models for finite nuclei contain spurious center-of-mass motion in most applications for the nuclear many-body problem, where the nuclear wave function is taken as a single Slater determinant within a space-fixed frame description. We use the Peierls-Yoccoz projection method, previously developed for relativistic approaches together with a reparametrization of the coupling constants that fits binding energies and charge radius and apply our results to calculate elastic electron scattering monopole charge form factors for light nuclei. (orig.)
DONG Yu-Bing; FENG Qing-Guo
2002-01-01
Based on a relativistic quark model approach, the transition properties of the first nucleon resonance △(1232), and the coupling constants gπNN, g△πN are investigated. Tvo different vays to remove the center of mass motion are considered. The results of the relativistic approaches with and without center ofmass correction are compared with those of nonrelativistic constituent quark model. Moreover, pion meson cloud effect on these calculated observables is explicitly addressed. Better results are obtained by taking the pion meson cloud into account.
Simulation of the relativistic electron dynamics and acceleration in a linearly-chirped laser pulse
Jisrawi, Najeh M; Salamin, Yousef I
2014-01-01
Theoretical investigations are presented, and their results are discussed, of the laser acceleration of a single electron by a chirped pulse. Fields of the pulse are modeled by simple plane-wave oscillations and a $\\cos^2$ envelope. The dynamics emerge from analytic and numerical solutions to the relativistic Lorentz-Newton equations of motion of the electron in the fields of the pulse. All simulations have been carried out by independent Mathematica and Python codes, with identical results. Configurations of acceleration from a position of rest as well as from injection, axially and sideways, at initial relativistic speeds are studied.
Study of the Lie symmetries of a relativistic variable mass system
方建会
2002-01-01
The differential equations of motion of a relativistic variable mass system are given. By using the invariance of the differential equations under the infinitesimal transformations of groups, the determining equations and the restriction equations of the Lie symmetries of a relativistic variable mass system are built, and the structure equation and the conserved quantity of the Lie symmetries are obtained. Then the inverse problem of the Lie symmetries is studied. The corresponding Lie symmetries are found according to a known conserved quantity. An example is given to illustrate the application of the result.
Thermodynamic and relativistic uncertainty relations
Artamonov, A. A.; Plotnikov, E. M.
2017-01-01
Thermodynamic uncertainty relation (UR) was verified experimentally. The experiments have shown the validity of the quantum analogue of the zeroth law of stochastic thermodynamics in the form of the saturated Schrödinger UR. We have also proposed a new type of UR for the relativistic mechanics. These relations allow us to consider macroscopic phenomena within the limits of the ratio of the uncertainty relations for different physical quantities.
Pythagoras Theorem and Relativistic Kinematics
Mulaj, Zenun; Dhoqina, Polikron
2010-01-01
In two inertial frames that move in a particular direction, may be registered a light signal that propagates in an angle with this direction. Applying Pythagoras theorem and principles of STR in both systems, we can derive all relativistic kinematics relations like the relativity of simultaneity of events, of the time interval, of the length of objects, of the velocity of the material point, Lorentz transformations, Doppler effect and stellar aberration.
Tropical Cyclone Structure and Motion
2016-06-07
rotational motion of the storm due to storm tilt that was identified in dry simulations is reduced in simulations that include parameterizations of convective...right of the zero-shear storm track. Currently, the model resolution is being increased to 5 km with a third inner mesh and all convective processes...that were previously parameterized on the 15- and 45-km meshes are calculated using an explicit physical representation of convection scheme. Because
Magnetohydrodynamic Shearing Waves
Johnson, B M
2006-01-01
I consider the nonaxisymmetric linear theory of an isothermal magnetohydrodynamic (MHD) shear flow. The analysis is performed in the shearing box, a local model appropriate for a thin disk geometry. Linear perturbations in this model can be decomposed in terms of shearing waves (shwaves), which appear spatially as plane waves in a frame comoving with the shear. The time dependence of these waves cannot in general be expressed in terms of a frequency eigenvalue as in a normal mode decomposition, and numerical integration of a set of first-order amplitude equations is required for a complete characterization of their behavior. Their generic time dependence, however, is oscillatory with slowly-varying frequency and amplitude, and one can construct accurate analytic solutions by applying the Wentzel-Kramers-Brillouin method to the full set of amplitude equations. For the bulk of wavenumber space, therefore, the shwaves are well-approximated as modes with time-dependent frequencies and amplitudes. The incompressiv...
Relativistic Binaries in Globular Clusters
Benacquista Matthew J.
2006-02-01
Full Text Available The galactic population of globular clusters are old, dense star systems, with a typical cluster containing 10^4 - 10^7 stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or two compact objects. In this review, we discuss the theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution which lead to relativistic binaries, and current and possible future observational evidence for this population. Globular cluster evolution will focus on the properties that boost the production of hard binary systems and on the tidal interactions of the galaxy with the cluster, which tend to alter the structure of the globular cluster with time. The interaction of the components of hard binary systems alters the evolution of both bodies and can lead to exotic objects. Direct N-body integrations and Fokker-Planck simulations of the evolution of globular clusters that incorporate tidal interactions and lead to predictions of relativistic binary populations are also discussed. We discuss the current observational evidence for cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries as well as possible future detection of relativistic binaries with gravitational radiation.
Relativistic Binaries in Globular Clusters
Benacquista Matthew
2002-01-01
Full Text Available The galactic population of globular clusters are old, dense star systems, with a typical cluster containing $10^4 - 10^6$ stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or two compact objects. In this review, we discuss the theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution which lead to relativistic binaries, and current and possible future observational evidence for this population. Globular cluster evolution will focus on the properties that boost the production of hard binary systems and on the tidal interactions of the galaxy with the cluster, which tend to alter the structure of the globular cluster with time. The interaction of the components of hard binary systems alters the evolution of both bodies and can lead to exotic objects. Direct $N$-body integrations and Fokker--Planck simulations of the evolution of globular clusters that incorporate tidal interactions and lead to predictions of relativistic binary populations are also discussed. We discuss the current observational evidence for cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries as well as possible future detection of relativistic binaries with gravitational radiation.
Relativistic Binaries in Globular Clusters
Matthew J. Benacquista
2013-03-01
Full Text Available Galactic globular clusters are old, dense star systems typically containing 10^4 – 10^6 stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or two compact objects. In this review, we discuss theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution that leads to relativistic binaries, and current and possible future observational evidence for this population. Our discussion of globular cluster evolution will focus on the processes that boost the production of tight binary systems and the subsequent interaction of these binaries that can alter the properties of both bodies and can lead to exotic objects. Direct N-body integrations and Fokker–Planck simulations of the evolution of globular clusters that incorporate tidal interactions and lead to predictions of relativistic binary populations are also discussed. We discuss the current observational evidence for cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries as well as possible future detection of relativistic binaries with gravitational radiation.
Relativistic Tennis Using Flying Mirror
Pirozhkov, A. S.; Kando, M.; Esirkepov, T. Zh.; Ma, J.; Fukuda, Y.; Chen, L.-M.; Daito, I.; Ogura, K.; Homma, T.; Hayashi, Y.; Kotaki, H.; Sagisaka, A.; Mori, M.; Koga, J. K.; Kawachi, T.; Daido, H.; Bulanov, S. V.; Kimura, T.; Kato, Y.; Tajima, T.
2008-06-01
Upon reflection from a relativistic mirror, the electromagnetic pulse frequency is upshifted and the duration is shortened by the factor proportional to the relativistic gamma-factor squared due to the double Doppler effect. We present the results of the proof-of-principle experiment for frequency upshifting of the laser pulse reflected from the relativistic "flying mirror", which is a wake wave near the breaking threshold created by a strong driver pulse propagating in underdense plasma. Experimentally, the wake wave is created by a 2 TW, 76 fs Ti:S laser pulse from the JLITE-X laser system in helium plasma with the electron density of ≈4-6×1019 cm-3. The reflected signal is observed with a grazing-incidence spectrograph in 24 shots. The wavelength of the reflected radiation ranges from 7 to 14 nm, the corresponding frequency upshifting factors are ˜55-115, and the gamma-factors are y = 4-6. The reflected signal contains at least 3×107 photons/sr. This effect can be used to generate coherent high-frequency ultrashort pulses that inherit temporal shape and polarization from the original (low-frequency) ones. Apart from this, the reflected radiation contains important information about the wake wave itself, e.g. location, size, phase velocity, etc.
Magnetohydrodynamics of Chiral Relativistic Fluids
Boyarsky, Alexey; Ruchayskiy, Oleg
2015-01-01
We study the dynamics of a plasma of charged relativistic fermions at very high temperature $T\\gg m$, where $m$ is the fermion mass, coupled to the electromagnetic field. In particular, we derive a magneto-hydrodynamical description of the evolution of such a plasma. We show that, as compared to conventional MHD for a plasma of non-relativistic particles, the hydrodynamical description of the relativistic plasma involves new degrees of freedom described by a pseudo-scalar field originating in a local asymmetry in the densities of left-handed and right-handed fermions. This field can be interpreted as an effective axion field. Taking into account the chiral anomaly we present dynamical equations for the evolution of this field, as well as of other fields appearing in the MHD description of the plasma. Due to its non-linear coupling to helical magnetic fields, the axion field significantly affects the dynamics of a magnetized plasma and can give rise to a novel type of inverse cascade.
Shear-resistant behavior of light composite shear wall
李升才; 董毓利
2015-01-01
Shear test results for a composite wall panel in a light composite structure system are compared with test results for shear walls in Japan. The analysis results show that this kind of composite wall panel works very well, and can be regarded as a solid panel. The composite wall panel with a hidden frame is essential for bringing its effect on shear resistance into full play. Comprehensive analysis of the shear-resistant behavior of the composite wall panel suggests that the shear of the composite shear wall panel can be controlled by the cracking strength of the web shearing diagonal crack.
Shear-Resistant Behavior Analysis of Light Composite Shear Walls
李升才; 江见鲸; 于庆荣
2002-01-01
Shear test results for a composite wall panel in a light composite structure system are compared with test results for shear walls in Japan in this paper. The analysis results show that this kind of composite wall panel works very well, and can be regarded as a solid panel. The composite wall panel with a hidden frame is essential for bringing its effect on shear resistance into full play. Comprehensive analysis of the shear-resistant behavior of the composite wall panel suggests that the shear of the composite shear wall panel can be controlled by the cracking strength of the web shearing diagonal crack.
Direct Shear Tests with Evaluation of Variable Shearing Area
Šarūnas Skuodis
2014-12-01
Full Text Available Investigations of soil shear strength properties for Baltic Sea shore sand along Klaipėda city are presented. Investigated sand angle of internal friction (φ and cohesion (c is determined via two different direct shear tests procedures. First procedure is standard and ordinary in geotechnical practice, when direct shear test is provided using constant shearing area A0. Second test procedure is different because shearing area according to horizontal displacement each test second is recalculated. This recalculated shearing area author’s call corrected shearing area A. Obtained normal and tangential stresses’ difference via two different testing procedures was 10%.
Evolution of shear banding flows in metallic glasses characterized by molecular dynamics
Yao, Li, E-mail: yltiger@sjtu.edu.cn [Shanghai Institute of Space Power-Sources, 2965 Dongchuan Rd., Shanghai 200245 (China); Luan, Yingwei [School of Materials Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Rd., Shanghai 200240 (China)
2016-06-21
To reveal the evolution of shear banding flows, one-dimensional nanostructure metallic glass composites have been studied with molecular dynamics. The inherent size determines the initial thickness of shear bands, and the subsequent broadening can be restricted to some extent. The vortex-like flows evoke the atomic motion perpendicular to the shear plane, which accelerates the interatomic diffusion. The reduction of local strain rate causes the flow softening for monolithic Cu-Zr glass, but the participation of Cu-atoms in the shear banding flow gradually leads to the shear hardening for the composites.
Particle dynamics in a relativistic invariant stochastic medium
Cabo-Bizet, A; Cabo-Bizet, Alejandro; Oca, Alejandro Cabo Montes de
2005-01-01
The dynamics of particles moving in a medium defined by its relativistically invariant stochastic properties is investigated. For this aim, the force exerted on the particles by the medium is defined by a stationary random variable as a function of the proper time of the particles. The equations of motion for a single one-dimensional particle are obtained and numerically solved. A conservation law for the drift momentum of the particle during its random motion is shown. Moreover, the conservation of the mean value of the total linear momentum for two particles repelling each other according with the Coulomb interaction is also following. Therefore, the results indicate the realization of a kind of stochastic Noether theorem in the system under study. Possible applications to the stochastic representation of Quantum Mechanics are advanced.
Particle dynamics in a relativistic invariant stochastic medium
Cabo-Bizet, Alejandro [Facultad de Fisica, Universidad de La Habana, Colina Universitaria, Havana (Cuba); Cabo Montes de Oca, Alejandro [Grupo de Fisica Teorica, Instituto de Cibernetica, Matematica y Fisica, Havana (Cuba) and Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, Miramare, Trieste (Italy)]. E-mail: cabo@fis.puc.cl
2006-11-27
The dynamics of particles moving in a medium defined by its relativistically invariant stochastic properties is investigated. For this aim, the force exerted on the particles by the medium is defined by a stationary random variable as a function of the proper time of the particles. The equations of motion for a single one-dimensional particle are obtained and numerically solved. A conservation law for the drift momentum of the particle during its random motion is shown. Moreover, the conservation of the mean value of the total linear momentum for two particles repelling each other according to the Coulomb interaction also follows. Therefore, the results indicate the realization of a kind of stochastic Noether theorem in the system under study.
Improving Planck calibration by including frequency-dependent relativistic corrections
Quartin, Miguel
2015-01-01
The Planck satellite detectors are calibrated in the 2015 release using the "orbital dipole", which is the time-dependent dipole generated by the Doppler effect due to the motion of the satellite around the Sun. Such an effect has also relativistic time-dependent corrections of relative magnitude 10^(-3), due to coupling with the "solar dipole" (the motion of the Sun compared to the CMB rest frame), which are included in the data calibration by the Planck collaboration. We point out that such corrections are subject to a frequency-dependent multiplicative factor. This factor differs from unity especially at the highest frequencies, relevant for the HFI instrument. Since currently Planck calibration errors are dominated by systematics, to the point that polarization data is currently unreliable at large scales, such a correction can in principle be highly relevant for future data releases.
Improving Planck calibration by including frequency-dependent relativistic corrections
Quartin, Miguel; Notari, Alessio
2015-09-01
The Planck satellite detectors are calibrated in the 2015 release using the "orbital dipole", which is the time-dependent dipole generated by the Doppler effect due to the motion of the satellite around the Sun. Such an effect has also relativistic time-dependent corrections of relative magnitude 10-3, due to coupling with the "solar dipole" (the motion of the Sun compared to the CMB rest frame), which are included in the data calibration by the Planck collaboration. We point out that such corrections are subject to a frequency-dependent multiplicative factor. This factor differs from unity especially at the highest frequencies, relevant for the HFI instrument. Since currently Planck calibration errors are dominated by systematics, to the point that polarization data is currently unreliable at large scales, such a correction can in principle be highly relevant for future data releases.
Relativistic effects in Lyman-alpha forest
Iršič, Vid; Viel, Matteo
2015-01-01
We present the calculation of the Lyman-alpha (Lyman-$\\alpha$) transmitted flux fluctuations with full relativistic corrections to the first order. Even though several studies exist on relativistic effects in galaxy clustering, this is the first study to extend the formalism to a different tracer of underlying matter at unique redshift range ($z = 2 - 5$). Furthermore, we show a comprehensive application of our calculations to the Quasar- Lyman-$\\alpha$ cross-correlation function. Our results indicate that the signal of relativistic effects can be as large as 30% at Baryonic Acoustic Oscillation (BAO) scale, which is much larger than anticipated and mainly due to the large differences in density bias factors of our tracers. We construct an observable, the anti-symmetric part of the cross- correlation function, that is dominated by the relativistic signal and offers a new way to measure the relativistic terms at relatively small scales. The analysis shows that relativistic effects are important when considerin...
Entropy current for non-relativistic fluid
Banerjee, Nabamita; Jain, Akash; Roychowdhury, Dibakar
2014-01-01
We study transport properties of a parity-odd, non-relativistic charged fluid in presence of background electric and magnetic fields. To obtain stress tensor and charged current for the non-relativistic system we start with the most generic relativistic fluid, living in one higher dimension and reduce the constituent equations along the light-cone direction. We also reduce the equation satisfied by the entropy current of the relativistic theory and obtain a consistent entropy current for the non-relativistic system (we call it "canonical form" of the entropy current). Demanding that the non-relativistic fluid satisfies the second law of thermodynamics we impose constraints on various first order transport coefficients. For parity even fluid, this is straight forward; it tells us positive definiteness of different transport coefficients like viscosity, thermal conductivity, electric conductivity etc. However for parity-odd fluid, canonical form of the entropy current fails to confirm the second law of thermody...
A group theoretic approach to shear-free radiating stars
Abebe, G. Z.; Maharaj, S. D.; Govinder, K. S.
2015-10-01
A systematic analysis of the junction condition, relating the radial pressure with the heat flow in a shear-free relativistic radiating star, is undertaken. This is a highly nonlinear partial differential equation in general. We obtain the Lie point symmetries that leave the boundary condition invariant. Using a linear combination of the symmetries, we transform the junction condition into ordinary differential equations. We present several new exact solutions to the junction condition. In each case we can identify the exact solution with a Lie point generator. Some of the solutions obtained satisfy the linear barotropic equation of state. As a special case we regain the conformally flat models which were found previously. Our analysis highlights the interplay between Lie algebras, nonlinear differential equations and application to relativistic astrophysics.
A group theoretic approach to shear-free radiating stars
Abebe, G; Govinder, K S
2015-01-01
A systematic analysis of the junction condition, relating the radial pressure with the heat flow in a shear-free relativistic radiating star, is undertaken. This is a highly nonlinear partial differential equation in general. We obtain the Lie point symmetries that leave the boundary condition invariant. Using a linear combination of the symmetries, we transform the junction condition into ordinary differential equations. We present several new exact solutions to the junction condition. In each case we can identify the exact solution with a Lie point generator. Some of the solutions obtained satisfy the linear barotropic equation of state. As a special case we regain conformally flat models which were found previously. Our analysis highlights the interplay between Lie algebras, nonlinear differential equations and application to relativistic astrophysics.
Non-Relativistic Spacetimes with Cosmological Constant
Aldrovandi, R.; Barbosa, A. L.; Crispino, L.C.B.; Pereira, J. G.
1998-01-01
Recent data on supernovae favor high values of the cosmological constant. Spacetimes with a cosmological constant have non-relativistic kinematics quite different from Galilean kinematics. De Sitter spacetimes, vacuum solutions of Einstein's equations with a cosmological constant, reduce in the non-relativistic limit to Newton-Hooke spacetimes, which are non-metric homogeneous spacetimes with non-vanishing curvature. The whole non-relativistic kinematics would then be modified, with possible ...
Relativistic non-equilibrium thermodynamics revisited
García-Colin, L S
2006-01-01
Relativistic irreversible thermodynamics is reformulated following the conventional approach proposed by Meixner in the non-relativistic case. Clear separation between mechanical and non-mechanical energy fluxes is made. The resulting equations for the entropy production and the local internal energy have the same structure as the non-relativistic ones. Assuming linear constitutive laws, it is shown that consistency is obtained both with the laws of thermodynamics and causality.
Analogy betwen dislocation creep and relativistic cosmology
J.A. Montemayor-Aldrete; J.D. Muñoz-Andrade; Mendoza-Allende, A.; Montemayor-Varela, A.
2005-01-01
A formal, physical analogy between plastic deformation, mainly dislocation creep, and Relativistic Cosmology is presented. The physical analogy between eight expressions for dislocation creep and Relativistic Cosmology have been obtained. By comparing the mathematical expressions and by using a physical analysis, two new equations have been obtained for dislocation creep. Also, four new expressions have been obtained for Relativistic Cosmology. From these four new equations, one may determine...
A relativistic correction to semiclassical charmonium
Weiss, J.
1995-09-01
It is shown that the relativistic linear potentials, introduced by the author within the particle à la Wheeler-Feynman direct-interaction (AAD) theory, applied to the semiclassically quantized charmonium, yield energy spectrum comparable to that of some known models. Using the expansion of the relativistic linear AAD potentials in powers ofc -1, the charmonium spectrum, given as a rule by Bohr-Sommerfeld quantization of circular orbits, is extended up to the second order of relativistic corrections.
Generalized One-Dimensional Point Interaction in Relativistic and Non-relativistic Quantum Mechanics
Shigehara, T; Mishima, T; Cheon, T; Cheon, Taksu
1999-01-01
We first give the solution for the local approximation of a four parameter family of generalized one-dimensional point interactions within the framework of non-relativistic model with three neighboring $\\delta$ functions. We also discuss the problem within relativistic (Dirac) framework and give the solution for a three parameter family. It gives a physical interpretation for so-called high energy substantially differ between non-relativistic and relativistic cases.
Relativistic Cyclotron Instability in Anisotropic Plasmas
López, Rodrigo A.; Moya, Pablo S.; Navarro, Roberto E.; Araneda, Jaime A.; Muñoz, Víctor; Viñas, Adolfo F.; Alejandro Valdivia, J.
2016-11-01
A sufficiently large temperature anisotropy can sometimes drive various types of electromagnetic plasma micro-instabilities, which can play an important role in the dynamics of relativistic pair plasmas in space, astrophysics, and laboratory environments. Here, we provide a detailed description of the cyclotron instability of parallel propagating electromagnetic waves in relativistic pair plasmas on the basis of a relativistic anisotropic distribution function. Using plasma kinetic theory and particle-in-cell simulations, we study the influence of the relativistic temperature and the temperature anisotropy on the collective and noncollective modes of these plasmas. Growth rates and dispersion curves from the linear theory show a good agreement with simulations results.
Do non-relativistic neutrinos oscillate?
Akhmedov, Evgeny
2017-07-01
We study the question of whether oscillations between non-relativistic neutrinos or between relativistic and non-relativistic neutrinos are possible. The issues of neutrino production and propagation coherence and their impact on the above question are discussed in detail. It is demonstrated that no neutrino oscillations can occur when neutrinos that are non-relativistic in the laboratory frame are involved, except in a strongly mass-degenerate case. We also discuss how this analysis depends on the choice of the Lorentz frame. Our results are for the most part in agreement with Hinchliffe's rule.
Geometric Models of the Relativistic Harmonic Oscillator
Cotaescu, I I
1997-01-01
A family of relativistic geometric models is defined as a generalization of the actual anti-de Sitter (1+1) model of the relativistic harmonic oscillator. It is shown that all these models lead to the usual harmonic oscillator in the non-relativistic limit, even though their relativistic behavior is quite different. Among quantum models we find a set of models with countable energy spectra, and another one having only a finite number of energy levels and in addition a continuous spectrum.
Relativistic and non-relativistic solitons in plasmas
Barman, Satyendra Nath
This thesis entitled as "Relativistic and Non-relativistic Solitons in Plasmas" is the embodiment of a number of investigations related to the formation of ion-acoustic solitary waves in plasmas under various physical situations. The whole work of the thesis is devoted to the studies of solitary waves in cold and warm collisionless magnetized or unmagnetized plasmas with or without relativistic effect. To analyze the formation of solitary waves in all our models of plasmas, we have employed two established methods namely - reductive perturbation method to deduce the Korteweg-de Vries (KdV) equation, the solutions of which represent the important but near exact characteristic concepts of soliton-physics. Next, the pseudopotential method to deduce the energy integral with total nonlinearity in the coupling process for exact characteristic results of solitons has been incorporated. In Chapter 1, a brief description of plasma in nature and laboratory and its generation are outlined elegantly. The nonlinear differential equations to characterize solitary waves and the relevant but important methods of solutions have been mentioned in this chapter. The formation of solitary waves in unmagnetized and magnetized plasmas, and in relativistic plasmas has been described through mathematical entity. Applications of plasmas in different fields are also put forwarded briefly showing its importance. The study of plasmas as they naturally occur in the universe encompasses number of topics including sun's corona, solar wind, planetary magnetospheres, ionospheres, auroras, cosmic rays and radiation. The study of space weather to understand the universe, communications and the activities of weather satellites are some useful areas of space plasma physics. The surface cleaning, sterilization of food and medical appliances, killing of bacteria on various surfaces, destroying of viruses, fungi, spores and plasma coating in industrial instruments ( like computers) are some of the fields
Solutions of Conformal Israel-Stewart Relativistic Viscous Fluid Dynamics
Marrochio, Hugo; Denicol, Gabriel S; Luzum, Matthew; Jeon, Sangyong; Gale, Charles
2013-01-01
We use symmetry arguments developed by Gubser to construct the first radially-expanding explicit solutions of the Israel-Stewart formulation of hydrodynamics. Along with a general semi-analytical solution, an exact analytical solution is given which is valid in the cold plasma limit where viscous effects from shear viscosity and the relaxation time coefficient are important. The radially expanding solutions presented in this paper can be used as nontrivial checks of numerical algorithms employed in hydrodynamic simulations of the quark-gluon plasma formed in ultra-relativistic heavy ion collisions. We show this explicitly by comparing such analytic and semi-analytic solutions with the corresponding numerical solutions obtained using the MUSIC viscous hydrodynamics simulation code.
Relativistic plasma optics enabled by near-critical density nanostructured material
Bin, J H; Wang, H Y; Streeter, M J V; Kreuzer, C; Kiefer, D; Yeung, M; Cousens, S; Foster, P S; Dromey, B; Yan, X Q; Meyer-ter-Vehn, J; Zepf, M; Schreiber, J
2014-01-01
The nonlinear optical properties of a plasma due to the relativistic electron motion in an intense laser field are of fundamental importance for current research and the generation of brilliant laser-driven sources of particles and photons1-15. Yet, one of the most interesting regimes, where the frequency of the laser becomes resonant with the plasma, has remained experimentally hard to access. We overcome this limitation by utilizing ultrathin carbon nanotube foam16 (CNF) targets allowing the strong relativistic nonlinearities at near- critical density (NCD) to be exploited for the first time. We report on the experimental realization of relativistic plasma optics to spatio-temporally compress the laser pulse within a few micrometers of propagation, while maintaining about half its energy. We also apply the enhanced laser pulses to substantially improve the properties of an ion bunch accelerated from a secondary target. Our results provide first insights into the rich physics of NCD plasmas and the opportuni...
On the relative importance of second-order terms in relativistic dissipative fluid dynamics
Molnár, E; Denicol, G S; Rischke, D H
2013-01-01
In Denicol et al., Phys. Rev. D 85, 114047 (2012), the equations of motion of relativistic dissipative fluid dynamics were derived from the relativistic Boltzmann equation. These equations contain a multitude of terms of second order in Knudsen number, in inverse Reynolds number, or their product. Terms of second order in Knudsen number give rise to non-hyperbolic (and thus acausal) behavior and must be neglected in (numerical) solutions of relativistic dissipative fluid dynamics. The coefficients of the terms which are of the order of the product of Knudsen and inverse Reynolds numbers have been explicitly computed in the above reference, in the limit of a massless Boltzmann gas. Terms of second order in inverse Reynolds number arise from the collision term in the Boltzmann equation, upon expansion to second order in deviations from the single-particle distribution function in local thermodynamical equilibrium. In this work, we compute these second-order terms for a massless Boltzmann gas with constant scatt...
Incipient Motion of Sediment Under Currents
DOU Guoren
2000-01-01
Summarized in the paper are the author′s studies on incipient motion of sediment in recent 40years. In addition to the forces of gravity, drag and lift, the cohesive force and the additional static pressure are important for fine particles. The relations between three stages of incipient motion are defined by use of instantaneous velocity. Formulas for initial velocity and critical shear stress are given and overall verified by the author′s and others′ experimental data
Relativistic Corrections to the Bohr Model of the Atom
Kraft, David W.
1974-01-01
Presents a simple means for extending the Bohr model to include relativistic corrections using a derivation similar to that for the non-relativistic case, except that the relativistic expressions for mass and kinetic energy are employed. (Author/GS)
RAM: a Relativistic Adaptive Mesh Refinement Hydrodynamics Code
Zhang, Wei-Qun; /KIPAC, Menlo Park; MacFadyen, Andrew I.; /Princeton, Inst. Advanced Study
2005-06-06
The authors have developed a new computer code, RAM, to solve the conservative equations of special relativistic hydrodynamics (SRHD) using adaptive mesh refinement (AMR) on parallel computers. They have implemented a characteristic-wise, finite difference, weighted essentially non-oscillatory (WENO) scheme using the full characteristic decomposition of the SRHD equations to achieve fifth-order accuracy in space. For time integration they use the method of lines with a third-order total variation diminishing (TVD) Runge-Kutta scheme. They have also implemented fourth and fifth order Runge-Kutta time integration schemes for comparison. The implementation of AMR and parallelization is based on the FLASH code. RAM is modular and includes the capability to easily swap hydrodynamics solvers, reconstruction methods and physics modules. In addition to WENO they have implemented a finite volume module with the piecewise parabolic method (PPM) for reconstruction and the modified Marquina approximate Riemann solver to work with TVD Runge-Kutta time integration. They examine the difficulty of accurately simulating shear flows in numerical relativistic hydrodynamics codes. They show that under-resolved simulations of simple test problems with transverse velocity components produce incorrect results and demonstrate the ability of RAM to correctly solve these problems. RAM has been tested in one, two and three dimensions and in Cartesian, cylindrical and spherical coordinates. they have demonstrated fifth-order accuracy for WENO in one and two dimensions and performed detailed comparison with other schemes for which they show significantly lower convergence rates. Extensive testing is presented demonstrating the ability of RAM to address challenging open questions in relativistic astrophysics.
Cheng, Roseanne M
2013-01-01
We consider tidal encounters between a white dwarf and an intermediate mass black hole. Both weak encounters and those at the threshold of disruption are modeled. The numerical code combines mesh-based (PPM) hydrodynamics, a spectral method (FFT) solution of the self-gravity, and a general relativistic Fermi normal coordinate (FNC) system that follows the star and debris. FNCs provide an expansion of the black hole tidal field that includes quadrupole and higher multipole moments and relativistic corrections. We compute the mass loss from the white dwarf that occurs in weak tidal encounters. Secondly, we compute carefully the energy deposition onto the star, examining the effects of non-radial and radial mode excitation, surface layer heating, mass loss, and relativistic orbital motion. We find evidence of a slight relativistic suppression in tidal energy transfer. Tidal energy deposition is compared to orbital energy loss due to gravitational bremsstrahlung and the combined losses are used to estimate tidal ...
An octahedral shear strain-based measure of SNR for 3D MR elastography
McGarry, M D J; Perrinez, P R; Pattison, A J; Weaver, J B; Paulsen, K D [Thayer School of Engineering, Dartmouth College, Hanover, NH 03755 (United States); Van Houten, E E W, E-mail: matthew.d.mcgarry@dartmouth.edu [Department of Mechanical Engineering, University of Canterbury, Christchurch (New Zealand)
2011-07-07
A signal-to-noise ratio (SNR) measure based on the octahedral shear strain (the maximum shear strain in any plane for a 3D state of strain) is presented for magnetic resonance elastography (MRE), where motion-based SNR measures are commonly used. The shear strain, {gamma}, is directly related to the shear modulus, {mu}, through the definition of shear stress, {tau} = {mu}{gamma}. Therefore, noise in the strain is the important factor in determining the quality of motion data, rather than the noise in the motion. Motion and strain SNR measures were found to be correlated for MRE of gelatin phantoms and the human breast. Analysis of the stiffness distributions of phantoms reconstructed from the measured motion data revealed a threshold for both strain and motion SNR where MRE stiffness estimates match independent mechanical testing. MRE of the feline brain showed significantly less correlation between the two SNR measures. The strain SNR measure had a threshold above which the reconstructed stiffness values were consistent between cases, whereas the motion SNR measure did not provide a useful threshold, primarily due to rigid body motion effects. (note)
An Octahedral Shear Strain Based measure of SNR for 3D MR Elastography
McGarry, MDJ; Van Houten, EEW; Perriñez, PR; Pattison, AJ; Weaver, JB; Paulsen, KD
2011-01-01
A signal to noise ratio (SNR) measure based on the octahedral shear strain (the maximum shear strain in any plane for a 3D state of strain) is presented for MR elastography, where motion-based SNR measures are commonly used. The shear strain, γ, is directly related to the shear modulus, μ, through the definition of shear stress, τ = μγ. Therefore, noise in the strain is the important factor in determining the quality of motion data, rather than the noise in the motion. Motion and strain SNR measures were found to be correlated for MRE of gelatin phantoms and human breast. Analysis of the stiffness distributions of phantoms reconstructed from the measured motion data revealed a threshold for both strain and motion SNR where MRE stiffness estimates match independent mechanical testing. MRE of the feline brain showed significantly less correlation between the two SNR measures. The strain SNR measure had a threshold above which the reconstructed stiffness values were consistent between cases, whereas the motion SNR measure did not provide a useful threshold, primarily due to rigid body motion effects. PMID:21654044
An octahedral shear strain-based measure of SNR for 3D MR elastography.
McGarry, M D J; Van Houten, E E W; Perriñez, P R; Pattison, A J; Weaver, J B; Paulsen, K D
2011-07-07
A signal-to-noise ratio (SNR) measure based on the octahedral shear strain (the maximum shear strain in any plane for a 3D state of strain) is presented for magnetic resonance elastography (MRE), where motion-based SNR measures are commonly used. The shear strain, γ, is directly related to the shear modulus, μ, through the definition of shear stress, τ = μγ. Therefore, noise in the strain is the important factor in determining the quality of motion data, rather than the noise in the motion. Motion and strain SNR measures were found to be correlated for MRE of gelatin phantoms and the human breast. Analysis of the stiffness distributions of phantoms reconstructed from the measured motion data revealed a threshold for both strain and motion SNR where MRE stiffness estimates match independent mechanical testing. MRE of the feline brain showed significantly less correlation between the two SNR measures. The strain SNR measure had a threshold above which the reconstructed stiffness values were consistent between cases, whereas the motion SNR measure did not provide a useful threshold, primarily due to rigid body motion effects.
Relativistic Plasma Polarizer: Impact of Temperature Anisotropy on Relativistic Transparency
Hazeltine, R. D.; Stark, David J.; Bhattacharjee, Chinmoy; Arefiev, Alexey V.; Toncian, Toma; Mahajan, S. M.
2015-11-01
3D particle-in-cell simulations demonstrate that the enhanced transparency of a relativistically hot plasma is sensitive to how the energy is partitioned between different degrees of freedom. We consider here the simplest problem: the propagation of a low amplitude pulse through a preformed relativistically hot anisotropic electron plasma to explore its intrinsic dielectric properties. We find that: 1) the critical density for propagation depends strongly on the pulse polarization, 2) two plasmas with the same density and average energy per electron can exhibit profoundly different responses to electromagnetic pulses, 3) the anisotropy-driven Weibel instability develops as expected; the timescales of the growth and back reaction (on anisotropy), however, are long enough that sufficient anisotropy persists for the entire duration of the simulation. This plasma can then function as a polarizer or a wave plate to dramatically alter the pulse polarization. This work was supported by the U.S. DOE Contract Nos. DE-FG02-04ER54742 and DE-AC05-06OR23100 (D. J. S.) and NNSA Contract No. DE-FC52-08NA28512.
On the relativistic anisotropic configurations
Shojai, F. [University of Tehran, Department of Physics, Tehran (Iran, Islamic Republic of); Institute for Research in Fundamental Sciences (IPM), Foundations of Physics Group, School of Physics, Tehran (Iran, Islamic Republic of); Kohandel, M. [Alzahra University, Department of Physics and Chemistry, Tehran (Iran, Islamic Republic of); Stepanian, A. [University of Tehran, Department of Physics, Tehran (Iran, Islamic Republic of)
2016-06-15
In this paper we study anisotropic spherical polytropes within the framework of general relativity. Using the anisotropic Tolman-Oppenheimer-Volkov equations, we explore the relativistic anisotropic Lane-Emden equations. We find how the anisotropic pressure affects the boundary conditions of these equations. Also we argue that the behavior of physical quantities near the center of star changes in the presence of anisotropy. For constant density, a class of exact solution is derived with the aid of a new ansatz and its physical properties are discussed. (orig.)
Simple waves in relativistic fluids.
Lyutikov, Maxim
2010-11-01
We consider the Riemann problem for relativistic flows of polytropic fluids and find relations for the flow characteristics. Evolution of physical quantities takes especially simple form for the case of cold magnetized plasmas. We find exact explicit analytical solutions for one-dimensional expansion of magnetized plasma into vacuum, valid for arbitrary magnetization. We also consider expansion into cold unmagnetized external medium both for stationary initial conditions and for initially moving plasma, as well as reflection of rarefaction wave from a wall. We also find self-similar structure of three-dimensional magnetized outflows into vacuum, valid close to the plasma-vacuum interface.
Observation of relativistic antihydrogen atoms
Blanford, Glenn Delfosse, Jr.
1997-09-01
An observation of relativistic antihydrogen atoms is reported in this dissertation. Experiment 862 at Fermi National Accelerator Laboratory observed antihydrogen atoms produced by the interaction of a circulating beam of high momentum (3 production is outlined within. The cross section corresponds to the process where a high momentum antiproton causes e+e/sp- pair creation near a nucleus with the e+ being captured by the antiproton. Antihydrogen is the first atom made exclusively of antimatter to be detected. The observation experiment's results are the first step towards an antihydrogen spectroscopy experiment which would measure the n = 2 Lamb shift and fine structure.
Einstein Toolkit for Relativistic Astrophysics
Collaborative Effort
2011-02-01
The Einstein Toolkit is a collection of software components and tools for simulating and analyzing general relativistic astrophysical systems. Such systems include gravitational wave space-times, collisions of compact objects such as black holes or neutron stars, accretion onto compact objects, core collapse supernovae and Gamma-Ray Bursts. The Einstein Toolkit builds on numerous software efforts in the numerical relativity community including CactusEinstein, Whisky, and Carpet. The Einstein Toolkit currently uses the Cactus Framework as the underlying computational infrastructure that provides large-scale parallelization, general computational components, and a model for collaborative, portable code development.
Density perturbations with relativistic thermodynamics
Maartens, R
1997-01-01
We investigate cosmological density perturbations in a covariant and gauge- invariant formalism, incorporating relativistic causal thermodynamics to give a self-consistent description. The gradient of density inhomogeneities splits covariantly into a scalar part, a rotational vector part that is determined by the vorticity, and a tensor part that describes the shape. We give the evolution equations for these parts in the general dissipative case. Causal thermodynamics gives evolution equations for viswcous stress and heat flux, which are coupled to the density perturbation equation and to the entropy and temperature perturbation equations. We give the full coupled system in the general dissipative case, and simplify the system in certain cases.
Thermodynamics of polarized relativistic matter
Kovtun, Pavel
2016-07-01
We give the free energy of equilibrium relativistic matter subject to external gravitational and electromagnetic fields, to one-derivative order in the gradients of the external fields. The free energy allows for a straightforward derivation of bound currents and bound momenta in equilibrium. At leading order, the energy-momentum tensor admits a simple expression in terms of the polarization tensor. Beyond the leading order, electric and magnetic polarization vectors are intrinsically ambiguous. The physical effects of polarization, such as the correlation between the magneto-vortically induced surface charge and the electro-vortically induced surface current, are not ambiguous.
Thermodynamics of polarized relativistic matter
Kovtun, Pavel
2016-01-01
We give the free energy of equilibrium relativistic matter subject to external gravitational and electromagnetic fields, to one-derivative order in the gradients of the external fields. The free energy allows for a straightforward derivation of bound currents and bound momenta in equilibrium. At leading order, the energy-momentum tensor admits a simple expression in terms of the polarization tensor. Beyond the leading order, electric and magnetic polarization vectors are intrinsically ambiguous. The physical effects of polarization, such as the correlation between the magneto-vortically induced surface charge and the electro-vortically induced surface current, are not ambiguous.
Relativistic solitons and superluminal signals
Maccari, Attilio [Technical Institute ' G. Cardano' , Piazza della Resistenza 1, Monterotondo, Rome 00015 (Italy)]. E-mail: solitone@yahoo.it
2005-02-01
Envelope solitons in the weakly nonlinear Klein-Gordon equation in 1 + 1 dimensions are investigated by the asymptotic perturbation (AP) method. Two different types of solitons are possible according to the properties of the dispersion relation. In the first case, solitons propagate with the group velocity (less than the light speed) of the carrier wave, on the contrary in the second case solitons always move with the group velocity of the carrier wave, but now this velocity is greater than the light speed. Superluminal signals are then possible in classical relativistic nonlinear field equations.
Maiti, Moumita; Vinutha, H. A.; Sastry, Srikanth; Heussinger, Claus
2015-10-01
Using an athermal quasistatic simulation protocol, we study the distribution of free volumes in sheared hard-particle packings close to, but below, the random-close packing threshold. We show that under shear, and independent of volume fraction, the free volumes develop features similar to close-packed systems — particles self-organize in a manner as to mimick the isotropically jammed state. We compare athermally sheared packings with thermalized packings and show that thermalization leads to an erasure of these structural features. The temporal evolution in particular the opening-up and the closing of free-volume patches is associated with the single-particle dynamics, showing a crossover from ballistic to diffusive behavior.
Multi-Channel Optical Coherence Elastography Using Relative and Absolute Shear-Wave Time of Flight
Elyas, Eli; Grimwood, Alex; Erler, Janine Terra
2017-01-01
a commercial four-channel swept-source OCT system. Shear-wave time of arrival (TOA) was detected by tracking the axial OCT-speckle motion using cross-correlation methods. Shear-wave speed was then calculated from inter-channel differences of TOA for a single burst (the relative TOA method) and compared...
The Micro-Pillar Shear-Stress Sensor MPS3 for Turbulent Flow
Grosse, S.; Schröder, W.
2009-01-01
Wall-shear stress results from the relative motion of a fluid over a body surface as a consequence of the no-slip condition of the fluid in the vicinity of the wall. To determine the two-dimensional wall-shear stress distribution is of utter importance in theoretical and applied turbulence research.
Kayaking and wagging of rods in shear flow
Tao, Y.G.; den Otter, Wouter K.; Briels, Willem J.
2005-01-01
For the first time, we have simulated the periodic collective orientational motions performed by rigid liquid-crystalline polymers with large aspect ratio in the nematic state in shear flow. In order to be able to do so, we developed a new, event-driven Brownian dynamics technique. We present the
Mixing through shear instabilities
Brüggen, M
2000-01-01
In this paper we present the results of numerical simulations of the Kelvin-Helmholtz instability in a stratified shear layer. This shear instability is believed to be responsible for extra mixing in differentially rotating stellar interiors and is the prime candidate to explain the abundance anomalies observed in many rotating stars. All mixing prescriptions currently in use are based on phenomenological and heuristic estimates whose validity is often unclear. Using three-dimensional numerical simulations, we study the mixing efficiency as a function of the Richardson number and compare our results with some semi-analytical formalisms of mixing.
Anomalous diffusion of proteins in sheared lipid membranes
Khoshnood, Atefeh
2013-01-01
We use coarse grained molecular dynamics simulations to investigate diffusion properties of sheared lipid membranes with embedded transmembrane proteins. In membranes without proteins, we find normal in-plane diffusion of lipids in all flow conditions. Protein embedded membranes behave quite differently: by imposing a simple shear flow and sliding the monolayers of the membrane over each other, the motion of protein clusters becomes strongly superdiffusive in the shear direction. In such a circumstance, subdiffusion regime is predominant perpendicular to the flow. We show that superdiffusion is a result of accelerated chaotic motions of protein--lipid complexes within the membrane voids, which are generated by hydrophobic mismatch or the transport of lipids by proteins.
Flow birefringence of a triblock copolymer in steady shear flow
Osaki, Kunihiro; Takatori, Eiichi
1988-06-20
Because the stress-optical law was estimated not to be valid in triblock copolymer, informations on molecular motion can be obtained by studying the discrepancy from stress-optical law. The relatioship between the stress and birefringence for a triblock copolymer was investigated in steady shear flow. It was verified experimentally the discrepancy from the stress-optical law, change of macroscopic stress deviation coefficient and normal stress deviation coefficient due to shear rate, and the difference of average stress-optical coefficients calculated from the compoments. These features of birefringence proved that the contribution to stress of a polymer segment depended on its position along the chain and was larger as it was closer the center of the chain. This was useful to investigate the relaxation behavior of birefringence after the steplike shear deformation, as well as the motion of polymer chain. (4 figs, 1 tab, 11 refs)
Magnetism and rotation in relativistic field theory
Mameda, Kazuya; Yamamoto, Arata
2016-09-01
We investigate the analogy between magnetism and rotation in relativistic theory. In nonrelativistic theory, the exact correspondence between magnetism and rotation is established in the presence of an external trapping potential. Based on this, we analyze relativistic rotation under external trapping potentials. A Landau-like quantization is obtained by considering an energy-dependent potential.
Relativistic heavy-ion physics: Experimental overview
Itzhak Tserruya
2003-04-01
The ﬁeld of relativistic heavy-ion physics is reviewed with emphasis on new results and highlights from the ﬁrst run of the relativistic heavy-ion collider at BNL and the 15 year research programme at the super proton synchrotron (SPS) at CERN and the AGS at BNL.
Physico-mathematical foundations of relativistic cosmology
Soares, Domingos
2013-01-01
I briefly present the foundations of relativistic cosmology, which are, General Relativity Theory and the Cosmological Principle. I discuss some relativistic models, namely, "Einstein static universe" and "Friedmann universes". The classical bibliographic references for the relevant tensorial demonstrations are indicated whenever necessary, although the calculations themselves are not shown.
Einstein Never Approved of Relativistic Mass
Hecht, Eugene
2009-01-01
During much of the 20th century it was widely believed that one of the significant insights of special relativity was "relativistic mass." Today there are two schools on that issue: the traditional view that embraces speed-dependent "relativistic mass," and the more modern position that rejects it, maintaining that there is only one mass and it's…
General relativistic Boltzmann equation, I: Covariant treatment
Debbasch, F.; van Leeuwen, W.A.
2009-01-01
This series of two articles aims at dissipating the rather dense haze existing in the present literature around the General Relativistic Boltzmann equation. In this first article, the general relativistic one-particle distribution function in phase space is defined as an average of delta functions.
Critique of Conventional Relativistic Quantum Mechanics.
Fanchi, John R.
1981-01-01
Following an historical sketch of the development of relativistic quantum mechanics, a discussion of the still unresolved difficulties of the currently accepted theories is presented. This review is designed to complement and update the discussion of relativistic quantum mechanics presented in many texts used in college physics courses. (Author/SK)
Lattice Boltzmann equation for relativistic quantum mechanics.
Succi, Sauro
2002-03-15
Relativistic versions of the quantum lattice Boltzmann equation are discussed. It is shown that the inclusion of nonlinear interactions requires the standard collision operator to be replaced by a pair of dynamic fields coupling to the relativistic wave function in a way which can be described by a multicomponent complex lattice Boltzmann equation.
Relativistic corrections to molecular dynamic dipole polarizabilities
Kirpekar, Sheela; Oddershede, Jens; Jensen, Hans Jørgen Aagaard
1995-01-01
Using response function methods we report calculations of the dynamic isotropic polarizability of SnH4 and PbH4 and of the relativistic corrections to it in the random phase approximation and at the correlated multiconfigurational linear response level of approximation. All relativistic corrections...
Bulanov, S. V.; Esirkepov, T. Zh.; Kando, M.; Koga, J. K.; Pirozhkov, A. S.; Rosanov, N. N.; Zhidkov, A. G.
2011-01-01
We formulate the Flying Mirror Concept for relativistic interaction of ultra-intense electromagnetic waves with plasmas, present its theoretical description and the results of computer simulations and laboratory experiments. In collisionless plasmas, the relativistic flying mirrors are thin and dense electron or electron-ion layers accelerated by the high intensity electromagnetic waves up to velocity close to the speed of light in vacuum; in nonlinear-media and in nonlinear vacuum they are the ionization fronts and the refraction index modulations induced by a strong electromagnetic wave. The reflection of the electromagnetic wave at the relativistic mirror results in its energy and frequency change due to the double Doppler effect. In the co-propagating configuration, in the radiation pressure dominant regime, the energy of the electromagnetic wave is transferred to the ion energy providing a highly efficient acceleration mechanism. In the counter-propagation configuration the frequency of the reflected wave is multiplied by the factor proportional to the gamma-factor squared. If the relativistic mirror performs an oscillatory motion as in the case of the electron motion at the plasma-vacuum interface, the reflected light spectrum is enriched with high order harmonics.
Relativistic electron beams above thunderclouds
M. Füllekrug
2011-08-01
Full Text Available Non-luminous relativistic electron beams above thunderclouds have been detected by the radio signals of low frequency ∼40–400 kHz which they radiate. The electron beams occur ∼2–9 ms after positive cloud-to-ground lightning discharges at heights between ∼22–72 km above thunderclouds. Intense positive lightning discharges can also cause sprites which occur either above or prior to the electron beam. One electron beam was detected without any luminous sprite which suggests that electron beams may also occur independently of sprites. Numerical simulations show that beams of electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of ∼7 MeV to transport a total charge of ∼−10 mC upwards. The impulsive current ∼3 × 10^{−3} Am^{−2} associated with relativistic electron beams above thunderclouds is directed downwards and needs to be considered as a novel element of the global atmospheric electric circuit.
Ponderomotive Acceleration by Relativistic Waves
Lau, Calvin; Yeh, Po-Chun; Luk, Onnie; McClenaghan, Joseph; Ebisuzaki, Toshikazu; Tajima, Toshiki
2014-01-01
In the extreme high intensity regime of electromagnetic (EM) waves in plasma, the acceleration process is found to be dominated by the ponderomotive acceleration (PA). While the wakefields driven by the ponderomotive force of the relativistic intensity EM waves are important, they may be overtaken by the PA itself in the extreme high intensity regime when the dimensionless vector potential $a_0$ of the EM waves far exceeds unity. The energy gain by this regime (in 1D) is shown to be (approximately) proportional to $a_0^2$. Before reaching this extreme regime, the coexistence of the PA and the wakefield acceleration (WA) is observed where the wave structures driven by the wakefields show the phenomenon of multiple and folded wave-breakings. Investigated are various signatures of the acceleration processes such as the dependence on the mass ratio for the energy gain as well as the energy spectral features. The relevance to high energy cosmic ray acceleration and to the relativistic laser acceleration is conside...
Single electron relativistic clock interferometer
Bushev, P. A.; Cole, J. H.; Sholokhov, D.; Kukharchyk, N.; Zych, M.
2016-09-01
Although time is one of the fundamental notions in physics, it does not have a unique description. In quantum theory time is a parameter ordering the succession of the probability amplitudes of a quantum system, while according to relativity theory each system experiences in general a different proper time, depending on the system's world line, due to time dilation. It is therefore of fundamental interest to test the notion of time in the regime where both quantum and relativistic effects play a role, for example, when different amplitudes of a single quantum clock experience different magnitudes of time dilation. Here we propose a realization of such an experiment with a single electron in a Penning trap. The clock can be implemented in the electronic spin precession and its time dilation then depends on the radial (cyclotron) state of the electron. We show that coherent manipulation and detection of the electron can be achieved already with present day technology. A single electron in a Penning trap is a technologically ready platform where the notion of time can be probed in a hitherto untested regime, where it requires a relativistic as well as quantum description.
24-Hour Relativistic Bit Commitment
Verbanis, Ephanielle; Martin, Anthony; Houlmann, Raphaël; Boso, Gianluca; Bussières, Félix; Zbinden, Hugo
2016-09-01
Bit commitment is a fundamental cryptographic primitive in which a party wishes to commit a secret bit to another party. Perfect security between mistrustful parties is unfortunately impossible to achieve through the asynchronous exchange of classical and quantum messages. Perfect security can nonetheless be achieved if each party splits into two agents exchanging classical information at times and locations satisfying strict relativistic constraints. A relativistic multiround protocol to achieve this was previously proposed and used to implement a 2-millisecond commitment time. Much longer durations were initially thought to be insecure, but recent theoretical progress showed that this is not so. In this Letter, we report on the implementation of a 24-hour bit commitment solely based on timed high-speed optical communication and fast data processing, with all agents located within the city of Geneva. This duration is more than 6 orders of magnitude longer than before, and we argue that it could be extended to one year and allow much more flexibility on the locations of the agents. Our implementation offers a practical and viable solution for use in applications such as digital signatures, secure voting and honesty-preserving auctions.
Chaos and Maps in Relativistic Dynamical Systems
Horwitz, L P
1999-01-01
The basic work of Zaslavskii et al showed that the classical non-relativistic electromagnetically kicked oscillator can be cast into the form of an iterative map on the phase space; the resulting evolution contains a stochastic flow to unbounded energy. Subsequent studies have formulated the problem in terms of a relativistic charged particle in interaction with the electromagnetic field. We review the structure of the covariant Lorentz force used to study this problem. We show that the Lorentz force equation can be derived as well from the manifestly covariant mechanics of Stueckelberg in the presence of a standard Maxwell field, establishing a connection between these equations and mass shell constraints. We argue that these relativistic generalizations of the problem are intrinsically inaccurate due to an inconsistency in the structure of the relativistic Lorentz force, and show that a reformulation of the relativistic problem, permitting variations (classically) in both the particle mass and the effective...
Relativistic Particles in Clusters of Galaxies
Ensslin, T A
2002-01-01
A brief overview on the theory and observations of relativistic particle populations in clusters of galaxies is given. The following topics are addressed: (i) the diffuse relativistic electron population within the intra-cluster medium (ICM) as seen in the cluster wide radio halos and possibly also seen in the high energy X-ray and extreme ultraviolet excess emissions of some clusters, (ii) the observed confined relativistic electrons within fresh and old radio plasma and their connection to cluster radio relics at cluster merger shock waves, (iii) the relativistic proton population within the ICM, and its observable consequences (if it exists), and (iv) the confined relativistic proton population (if it exists) within radio plasma. The importance of upcoming, sensitive gamma-ray telescopes for this research area is highlighted.
Relativistic recursion relations for transition matrix elements
Martínez y Romero, R P; Salas-Brito, A L
2004-01-01
We review some recent results on recursion relations which help evaluating arbitrary non-diagonal, radial hydrogenic matrix elements of $r^\\lambda$ and of $\\beta r^\\lambda$ ($\\beta$ a Dirac matrix) derived in the context of Dirac relativistic quantum mechanics. Similar recursion relations were derived some years ago by Blanchard in the non relativistic limit. Our approach is based on a generalization of the second hypervirial method previously employed in the non-relativistic Schr\\"odinger case. An extension of the relations to the case of two potentials in the so-called unshifted case, but using an arbitrary radial function instead of a power one, is also given. Several important results are obtained as special instances of our recurrence relations, such as a generalization to the relativistic case of the Pasternack-Sternheimer rule. Our results are useful in any atomic or molecular calculation which take into account relativistic corrections.
Quadratic relativistic invariant and metric form in quantum mechanics
Pissondes, Jean-Claude [DAEC, Observatoire de Paris-Meudon, Meudon (France)
1999-04-16
The Klein-Gordon equation is recovered in the framework of the theory of scale-relativity, first in the absence, then in the presence of an electromagnetic field. In this framework, spacetime at quantum scales is characterized by non-differentiability and continuity, which involves the introduction of explicit resolution-dependent fractal coordinates. Such a description leads to the notion of scale-covariance and its corresponding tool, a scale-covariant; derivative operator {theta}/ds. Due to it, the Klein-Gordon equation is written as an equation of free motion and interpreted as a geodesic equation in fractal spacetime. However, we obtain a new form for the corresponding relativistic invariant, which differs from that of special and general relativity. Characterizing quantum mechanics in the present approach, it is not simply quadratic in terms of velocities, but contains an extra term of divergence, which is intrinsically present in its expression. Moreover, in spite of the scale-covariance statements of the present theory, we find an extra term of current in addition to the Lorentz force, within the equations of motion with electromagnetic field written in this framework. Finally, we introduce another tool - a 'symmetric product' - from the requirement of recovering the usual form of the Leibniz rule written with the operator {theta}/ds. This tool allows us to write most equations in this framework in their usual classical form; in particular the simple rules of differentiation, the equations of motion with field and also our new relativistic invariant. (author)
Incipient motion of gravel and coal beds
Subhasish Dey; Uddaraju V Raju
2002-10-01
An experimental study on incipient motion of gravel and coal beds under unidirectional steady-uniform ﬂow is presented. Experiments were carried out in a ﬂume with various sizes of gravel and coal samples. The critical bed shear stresses for the experimental runs determined using side-wall correction show considerable disagreement with the standard curves. The characteristic parameters affecting the incipient motion of particles in rough-turbulent regime, identiﬁed based on physical reasoning and dimensional analysis, are the Shields parameter, particle Froude number, non-dimensional particle diameter and non-dimensional ﬂow depth. Equations of critical bed shear stress for the initial movement of gravel and coal beds were obtained using experimental data. The method of application of critical bed shear stress equations is also mentioned.
Antimagnetic rotation in 108,110In with tilted axis cranking relativistic mean-field approach
Sun, Wu-Ji; Xu, Hai-Dan; Li, Jian; Liu, Yong-Hao; Ma, Ke-Yan; Yang, Dong; Lu, Jing-Bing; Ma, Ying-Jun
2016-08-01
Based on tilted axis cranking relativistic mean-field theory within point-coupling interaction PC-PK1, the rotational structure and the characteristic features of antimagnetic rotation for ΔI = 2 bands in 108,110In are studied. Tilted axis cranking relativistic mean-field calculations reproduce the experimental energy spectrum well and are in agreement with the experimental I ∼ ω plot, although the calculated spin overestimates the experimental values. In addition, the two-shears-like mechanism in candidate antimagnetic rotation bands is clearly illustrated and the contributions from two-shears-like orbits, neutron (gd) orbits above Z = 50 shell and Z = 50, N = 50 core are investigated microscopically. The predicted B(E2), dynamic moment of inertia ℑ(2), deformation parameters β and γ, and ℑ(2)/B(E2) ratios in tilted axis cranking relativistic mean-field calculations are discussed and the characteristic features of antimagnetic rotation for the bands before and after alignment are shown. Supported by National Natural Science Foundation of China (11205068, 11205069, 11405072, 11475072, 11547308) and China Postdoctoral Science Foundation (2012M520667)
Hansen, Klaus
This report gives a summary of the present information on the behaviour of vertical keyed shear joints in large panel structures. An attemp is made to outline the implications which this information might have on the analysis and design of a complete wall. The publications also gives a short...
Akira Onuki; Akira Furukawa; Akihiko Minami
2005-05-01
We present a time-dependent Ginzburg–Landau model of nonlinear elasticity in solid materials. We assume that the elastic energy density is a periodic function of the shear and tetragonal strains owing to the underlying lattice structure. With this new ingredient, solving the equations yields formation of dislocation dipoles or slips. In plastic flow high-density dislocations emerge at large strains to accumulate and grow into shear bands where the strains are localized. In addition to the elastic displacement, we also introduce the local free volume . For very small the defect structures are metastable and long-lived where the dislocations are pinned by the Peierls potential barrier. However, if the shear modulus decreases with increasing , accumulation of around dislocation cores eventually breaks the Peierls potential leading to slow relaxations in the stress and the free energy (aging). As another application of our scheme, we also study dislocation formation in two-phase alloys (coherency loss) under shear strains, where dislocations glide preferentially in the softer regions and are trapped at the interfaces.
Drift Wave Test Particle Transport in Reversed Shear Profile
Horton, W.; Park, H.B.; Kwon, J.M.; Stronzzi, D.; Morrison, P.J.; Choi, D.I.
1998-06-01
Drift wave maps, area preserving maps that describe the motion of charged particles in drift waves, are derived. The maps allow the integration of particle orbits on the long time scale needed to describe transport. Calculations using the drift wave maps show that dramatic improvement in the particle confinement, in the presence of a given level and spectrum of E x B turbulence, can occur for q(r)-profiles with reversed shear. A similar reduction in the transport, i.e. one that is independent of the turbulence, is observed in the presence of an equilibrium radial electric field with shear. The transport reduction, caused by the combined effects of radial electric field shear and both monotonic and reversed shear magnetic q-profiles, is also investigated.
Shear Thinning of Noncolloidal Suspensions
Vázquez-Quesada, Adolfo; Tanner, Roger I.; Ellero, Marco
2016-09-01
Shear thinning—a reduction in suspension viscosity with increasing shear rates—is understood to arise in colloidal systems from a decrease in the relative contribution of entropic forces. The shear-thinning phenomenon has also been often reported in experiments with noncolloidal systems at high volume fractions. However its origin is an open theoretical question and the behavior is difficult to reproduce in numerical simulations where shear thickening is typically observed instead. In this letter we propose a non-Newtonian model of interparticle lubrication forces to explain shear thinning in noncolloidal suspensions. We show that hidden shear-thinning effects of the suspending medium, which occur at shear rates orders of magnitude larger than the range investigated experimentally, lead to significant shear thinning of the overall suspension at much smaller shear rates. At high particle volume fractions the local shear rates experienced by the fluid situated in the narrow gaps between particles are much larger than the averaged shear rate of the whole suspension. This allows the suspending medium to probe its high-shear non-Newtonian regime and it means that the matrix fluid rheology must be considered over a wide range of shear rates.
Attosecond Control of Relativistic Electron Bunches using Two-Colour Fields
Yeung, M; Bierbach, J; Li, L; Eckner, E; Kuschel, S; Woldegeorgis, A; Rödel, C; Sävert, A; Paulus, G G; Coughlan, M; Dromey, B; Zepf, M
2016-01-01
Energy coupling during relativistically intense laser-matter interactions is encoded in the attosecond motion of strongly driven electrons at the pre-formed plasma-vacuum boundary. Studying and controlling this motion can reveal details about the microscopic processes that govern a vast array of light-matter interaction physics and applications. These include research areas right at the forefront of extreme laser-plasma science such as laser-driven ion acceleration1, bright attosecond pulse generation2,3 and efficient energy coupling for the generation and study of warm dense matter4. Here we demonstrate attosecond control over the trajectories of relativistic electron bunches formed during such interactions by studying the emission of extreme ultraviolet (XUV) harmonic radiation. We describe how the precise addition of a second laser beam operating at the second harmonic of the driving laser pulse can significantly transform the interaction by modifying the accelerating potential provided by the fundamental ...
Shear strength of non-shear reinforced concrete elements
Hoang, Cao linh
1997-01-01
The paper deals with the plastic shear strength of non shear reinforced T-beams.The influence of an un-reinforced flange on the shear capacity is investigated by considering a failure mechanism involving crack sliding in the web and a kind of membrane action over an effective width of the flange...
Variable-amplitude oscillatory shear response of amorphous materials
Perchikov, Nathan; Bouchbinder, Eran
2014-06-01
Variable-amplitude oscillatory shear tests are emerging as powerful tools to investigate and quantify the nonlinear rheology of amorphous solids, complex fluids, and biological materials. Quite a few recent experimental and atomistic simulation studies demonstrated that at low shear amplitudes, an amorphous solid settles into an amplitude- and initial-conditions-dependent dissipative limit cycle, in which back-and-forth localized particle rearrangements periodically bring the system to the same state. At sufficiently large shear amplitudes, the amorphous system loses memory of the initial conditions, exhibits chaotic particle motions accompanied by diffusive behavior, and settles into a stochastic steady state. The two regimes are separated by a transition amplitude, possibly characterized by some critical-like features. Here we argue that these observations support some of the physical assumptions embodied in the nonequilibrium thermodynamic, internal-variables based, shear-transformation-zone model of amorphous viscoplasticity; most notably that "flow defects" in amorphous solids are characterized by internal states between which they can make transitions, and that structural evolution is driven by dissipation associated with plastic deformation. We present a rather extensive theoretical analysis of the thermodynamic shear-transformation-zone model for a variable-amplitude oscillatory shear protocol, highlighting its success in accounting for various experimental and simulational observations, as well as its limitations. Our results offer a continuum-level theoretical framework for interpreting the variable-amplitude oscillatory shear response of amorphous solids and may promote additional developments.
Restoration of rotational symmetry in deformed relativistic mean-field theory
YAO Jiang-Ming; MENG Jie; Pena Arteaga Daniel; Ring Peter
2009-01-01
We report on a very recently developed three-dimensional angular momentum projected relativistic mean-field theory with point-coupling interaction (3DAMP+RMF-PC). Using this approach the same effective nucleon-nucleon interaction is adopted to describe both the single-particle and collective motions in nuclei.Collective states with good quantum angular momentum are built projecting out the intrinsic deformed meanfield states. Results for 24Mg are shown as an illustrative application.
Noether's theorem of relativistic-electromagnetic ideal hydrodynamics
Elsas, J.H. Gaspar; Koide, T.; Kodama, T., E-mail: jhelsas@gmail.com, E-mail: kodama.takeshi@gmail.com, E-mail: tomoikoide@gmail.com [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Instituto de Fisica
2015-06-15
We present a variational approach for relativistic ideal hydrodynamics interacting with electromagnetic fields. The momentum of fluid is introduced as the canonical conjugate variable of the position of a fluid element, which coincides with the conserved quantity derived from Noether's theorem. We further show that our formulation can reproduce the usual electromagnetic hydrodynamics which is obtained so as to satisfy the conservation of the inertia of fluid motion. (author)
Berard, A.; Grandati, Y.; Mohrbach, H. [Universite Paul Verlaine, Institut de Physique, Laboratoire de Physique Moleculaire et des Collisions, ICPMB, IF CNRS 2843, Metz, Cedex 3 (France); Ghosh, Subir [Indian Statistical Institute, Physics and Applied Mathematics Unit, Kolkata (India); Pal, Probir [S.N. Bose National Centre for Basic Sciences, Kolkata (India)
2011-11-15
In this paper we have considered the dynamics of an anomalous (g{ne}2) charged relativistic spinning particle in the presence of an external electromagnetic field. A constraint analysis is done and the complete set of Dirac brackets are provided that generate the canonical Lorentz algebra and dynamics through Hamiltonian equations of motion. The spin-induced effective curvature of spacetime and its possible connection with Analogue Gravity models are commented upon. (orig.)
Relativistic Dirac equation for particles with arbitrary half-integral spin
Guseinov, I I
2008-01-01
The sets of 2(2s+1)-component matrices through the four-component Dirac matrices are suggested, where s=3/2, 5/2,.... Using these matrices sets the Dirac relativistic equation for a description of arbitrary half-integral spin particles is constructed. The new Dirac equation of motion leads to an equation of continuity with a positive-definite probability density.
Shear-induced dynamic polarization and mesoscopic structure in suspensions of polar nanorods.
Heidenreich, Sebastian; Hess, Siegfried; Klapp, Sabine H L
2009-01-16
We investigate the spatiotemporal behavior of sheared suspensions of rodlike particles with permanent dipole moments. Our calculations are based on a self-consistent hydrodynamic model including feedback effects between orientational motion and velocity profile. The competition between shear-induced tumbling motion and the boundary conditions imposed by plates leads to oscillatory alignment structures. These give rise to a spontaneous time-dependent polarization generating, in turn, magnetic fields. This novel shear-induced effect is robust against varying the boundary conditions. The field strengths are of a measurable magnitude for a broad parameter range.
Troxel, M A; Peel, Austin
2013-01-01
The study of relativistic, higher order and nonlinear effects has become necessary in recent years in the pursuit of precision cosmology. We develop and apply here a framework to study gravitational lensing in exact models in general relativity that are not restricted to homogeneity and isotropy, and where full nonlinearity and relativistic effects are included. We apply the framework to a specific, anisotropic galaxy cluster model which is based on a modified NFW halo density profile and described by the Szekeres metric. We examine the effects of increasing levels of anisotropy in the galaxy cluster on lensing observables like the convergence and shear for various lensing geometries, finding a strong nonlinear response in both the convergence and shear for rays passing through anisotropic regions of the cluster. Deviation from the expected values in a spherically symmetric structure are asymmetric with respect to path direction and thus will persist as a statistical effect when averaged over some ensemble of...
Shear Behavior of Concrete Beams Reinforced with GFRP Shear Reinforcement
Heecheul Kim; Min Sook Kim; Myung Joon Ko; Young Hak Lee
2015-01-01
This paper presents the shear capacities of concrete beams reinforced with glass fiber reinforced polymer (GFRP) plates as shear reinforcement. To examine the shear performance, we manufactured and tested a total of eight specimens. Test variables included the GFRP strip-width-to-spacing ratio and type of opening array. The specimen with a GFRP plate with a 3×2 opening array showed the highest shear strength. From the test results, the shear strength increased as the strip-width-to-strip-spac...
Relativistic Electrons in Electric Discharges
Cinar, Deniz
discharges as the source. The “Atmosphere-Space Interactions Monitor” (ASIM) for the International Space Station in 2016, led by DTU Space, and the French microsatellite TARANIS, also with launch in 2016, will identify with certainty the source of TGFs. In preparation for the missions, the Ph.D. project has...... developed a Monte Carlo module of a simulation code to model the formation of avalanches of electrons accelerated to relativistic energies, and the generation of bremsstrahlung through interactions with the neutral atmosphere. The code will be used in the analysis of data from the two space missions. We...... scattering. However, we only explored the properties of the complete number of photons reaching space, not the distribution at speci_c locations as in the case of a satellite. With this reservation we conclude that it is not possible to deduce much information from a satellite measurement of the photons...
Causal categories: relativistically interacting processes
Coecke, Bob
2011-01-01
A symmetric monoidal category naturally arises as the mathematical structure that organizes physical systems, processes, and composition thereof, both sequentially and in parallel. This structure admits a purely graphical calculus. This paper is concerned with the encoding of a fixed causal structure within a symmetric monoidal category: causal dependencies will correspond to topological connectedness in the graphical language. We show that correlations, either classical or quantum, force terminality of the tensor unit. We also show that well-definedness of the concept of a global state forces the monoidal product to be only partially defined, which in turn results in a relativistic covariance theorem. Except for these assumptions, at no stage do we assume anything more than purely compositional symmetric-monoidal categorical structure. We cast these two structural results in terms of a mathematical entity, which we call a `causal category'. We provide methods of constructing causal categories, and we study t...
Relativistic effects and quasipotential equations
Ramalho, G; Peña, M T
2002-01-01
We compare the scattering amplitude resulting from the several quasipotential equations for scalar particles. We consider the Blankenbecler-Sugar, Spectator, Thompson, Erkelenz-Holinde and Equal-Time equations, which were solved numerically without decomposition into partial waves. We analyze both negative-energy state components of the propagators and retardation effects. We found that the scattering solutions of the Spectator and the Equal-Time equations are very close to the nonrelativistic solution even at high energies. The overall relativistic effect increases with the energy. The width of the band for the relative uncertainty in the real part of the scattering $T$ matrix, due to different dynamical equations, is largest for backward-scattering angles where it can be as large as 40%.
Relativistic heavy-ion collisions
Bhalerao, Rajeev S
2014-01-01
The field of relativistic heavy-ion collisions is introduced to the high-energy physics students with no prior knowledge in this area. The emphasis is on the two most important observables, namely the azimuthal collective flow and jet quenching, and on the role fluid dynamics plays in the interpretation of the data. Other important observables described briefly are constituent quark number scaling, ratios of particle abundances, strangeness enhancement, and sequential melting of heavy quarkonia. Comparison is made of some of the basic heavy-ion results obtained at LHC with those obtained at RHIC. Initial findings at LHC which seem to be in apparent conflict with the accumulated RHIC data are highlighted.
General relativity and relativistic astrophysics
Mukhopadhyay, Banibrata
2016-01-01
Einstein established the theory of general relativity and the corresponding field equation in 1915 and its vacuum solutions were obtained by Schwarzschild and Kerr for, respectively, static and rotating black holes, in 1916 and 1963, respectively. They are, however, still playing an indispensable role, even after 100 years of their original discovery, to explain high energy astrophysical phenomena. Application of the solutions of Einstein's equation to resolve astrophysical phenomena has formed an important branch, namely relativistic astrophysics. I devote this article to enlightening some of the current astrophysical problems based on general relativity. However, there seem to be some issues with regard to explaining certain astrophysical phenomena based on Einstein's theory alone. I show that Einstein's theory and its modified form, both are necessary to explain modern astrophysical processes, in particular, those related to compact objects.
In search of relativistic time
Lachieze-Rey, Marc
2013-01-01
This paper explores the status of some notions which are usually associated to time, like datations, chronology, durations, causality, cosmic time and time functions in the Einsteinian relativistic theories. It shows how, even if some of these notions do exist in the theory or for some particular solution of it, they appear usually in mutual conflict: they cannot be synthesized coherently, and this is interpreted as the impossibility to construct a common entity which could be called time. This contrasts with the case in Newtonian physics where such a synthesis precisely constitutes Newtonian time. After an illustration by comparing the status of time in Einsteinian physics with that of the vertical direction in Newtonian physics, I will conclude that there is no pertinent notion of time in Einsteinian theories.
Playing relativistic billiards beyond graphene
Sadurni, E [Institut fuer Quantenphysik, Ulm Universitaet, Albert-Einstein Allee 11, 89081 Ulm (Germany); Seligman, T H [Centro Internacional de Ciencias A.C., Apartado Postal 6-101 C.P. 62131 Cuernavaca, Mor. (Mexico); Mortessagne, F, E-mail: esadurni@uni-ulm.d, E-mail: seligman@fis.unam.m, E-mail: fabrice.mortessagne@unice.f [Laboratoire de Physique de la Matiere Condensee, Universite de Nice-Sophia Antipolis, CNRS, UMR 6622 Parc Valrose, 06108 Nice cedex 2 (France)
2010-05-15
The possibility of using hexagonal structures in general, and graphene in particular, to emulate the Dirac equation is the topic under consideration here. We show that Dirac oscillators with or without rest mass can be emulated by distorting a tight-binding model on a hexagonal structure. In the quest to make a toy model for such relativistic equations, we first show that a hexagonal lattice of attractive potential wells would be a good candidate. Firstly, we consider the corresponding one-dimensional (1D) model giving rise to a 1D Dirac oscillator and then construct explicitly the deformations needed in the 2D case. Finally, we discuss how such a model can be implemented as an electromagnetic billiard using arrays of dielectric resonators between two conducting plates that ensure evanescent modes outside the resonators for transversal electric modes, and we describe a feasible experimental setup.