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Sample records for subject superluminal motion

  1. Superluminal motion in astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Falla, D.F.; Floyd, M.J. [Department of Physics, University of Wales, Aberystwyth (United Kingdom)

    2002-01-01

    Several examples of 'intrinsic-type' superluminal motion in astronomy are taken. A simple signal-delay transformation is devised and shown to be sufficient to explain the superluminal effect as resulting from differential signal delay across an expanding source. The distinction between relativistic motion and relativistic kinematics is made. The key kinematical equation used to describe superluminal motion is an alternative statement of the Doppler effect. Relativistic transformations, which are relevant when intervals in different reference frames are compared, then lead to the relativistic Doppler factor ({delta}), which is applicable to measurements on a photographic image, for example that of a relativistic quasar jet with superluminal components. (author)

  2. Superluminal motion (review)

    Science.gov (United States)

    Malykin, G. B.; Romanets, E. A.

    2012-06-01

    Prior to the development of Special Relativity, no restrictions were imposed on the velocity of the motion of particles and material bodies, as well as on energy transfer and signal propagation. At the end of the 19th century and the beginning of the 20th century, it was shown that a charge that moves at a velocity faster than the speed of light in an optical medium, in particular, in vacuum, gives rise to impact radiation, which later was termed the Vavilov-Cherenkov radiation. Shortly after the development of Special Relativity, some researchers considered the possibility of superluminal motion. In 1923, the Soviet physicist L.Ya. Strum suggested the existence of tachyons, which, however, have not been discovered yet. Superluminal motions can occur only for images, e.g., for so-called "light spots," which were considered in 1972 by V.L. Ginzburg and B.M. Bolotovskii. These spots can move with a superluminal phase velocity but are incapable of transferring energy and information. Nevertheless, these light spots may induce quite real generation of microwave radiation in closed waveguides and create the Vavilov-Cherenkov radiation in vacuum. In this work, we consider various paradoxes, illusions, and artifacts associated with superluminal motion.

  3. Superluminal motion in compact radio sources

    Science.gov (United States)

    Marscher, A. P.; Scott, J. S.

    1980-01-01

    The observations of radio sources whose components appear to move superluminally are now sufficient to eliminate certain theoretical models. However, a number of models might be still relevant. The models which involve relativistic bulk motions of the radio components seem to provide the most likely explanation of apparent superluminal motion. A summary of observational predictions of various models for superluminal motions is included.

  4. Field signature for apparently superluminal particle motion

    Science.gov (United States)

    Land, Martin

    2015-05-01

    In the context of Stueckelberg's covariant symplectic mechanics, Horwitz and Aharonovich [1] have proposed a simple mechanism by which a particle traveling below light speed almost everywhere may exhibit a transit time that suggests superluminal motion. This mechanism, which requires precise measurement of the particle velocity, involves a subtle perturbation affecting the particle's recorded time coordinate caused by virtual pair processes. The Stueckelberg framework is particularly well suited to such problems, because it permits pair creation/annihilation at the classical level. In this paper, we study a trajectory of the type proposed by Horwitz and Aharonovich, and derive the Maxwell 4-vector potential associated with the motion. We show that the resulting fields carry a signature associated with the apparent superluminal motion, providing an independent test for the mechanism that does not require direct observation of the trajectory, except at the detector.

  5. How superluminal motion can lead to backward time travel

    CERN Document Server

    Nemiroff, Robert J

    2015-01-01

    It is commonly asserted that superluminal particle motion can enable backward time travel, but little has been written providing details. It is shown here that the simplest example of a "closed loop" event -- a twin paradox scenario where a single spaceship both traveling out and returning back superluminally -- does {\\it not} result in that ship straightforwardly returning to its starting point before it left. However, a more complicated scenario -- one where the superluminal ship first arrives at an intermediate destination moving subluminally -- can result in backwards time travel. This intermediate step might seem physically inconsequential but is shown to break Lorentz-invariance and be oddly tied to the sudden creation of a pair of spacecraft, one of which remains and one of which annihilates with the original spacecraft.

  6. Superluminal motion in the double-lobed quasar 3C263

    Science.gov (United States)

    Zensus, J. A.; Hough, D. H.; Porcas, R. W.

    1987-01-01

    The detection of superluminal motion in the quasar 3C263 is reported. The milliarcsecond structure of this source consists of two nearly unresolved components whose separation is increasing at a rate of 0.06 + or - 0.02 marcsec/yr. This corresponds to an expansion speed of 2.7 + or - 0.9 c (H/0/ = 55 km/s/Mpc, q/0/ = 0.05). This quasar is the weakest superluminal source found so far, and there are indications that superluminal motion occurs frequently in this class of object.

  7. On the Superluminal Motion of Radio-Loud AGNs Zhi-Bin Zhang1,2 ...

    Indian Academy of Sciences (India)

    xies—radiation mechanisms: non-thermal—quasars: general. 1. Introduction. Rees (1966) predicted that the transverse velocity of an object moving relativistically in some special directions may appear to exceed the speed of light. The apparent superluminal motion (SM) is essentially a geometric effect or a light travel-time.

  8. Is the Consequence of Superluminal Signalling to Physics Absolute Motion through an Ether?

    CERN Document Server

    Cornwall, R O

    2011-01-01

    In an earlier paper the author expounded an interferometer scheme to communicate classical data over an entangled quantum channel. We return to this concept to show that the laws of Quantum Mechanics are not violated and that the device is able to affect the statistical blend of the quantum states (and that this can be detected) but not the statistics - i.e. the physics of observables. The ideas of superluminal information transfer, discussed in the previous paper, are taken forward to develop a notion of absolute space, time and motion with relativistic effects ascribed to motion through an absolute reference frame - as the logical consequences dictate, permeated with a material causing the 'relativistic' effects. The reciprocal nature of the Lorentz Transform is shown to fail under superluminal signalling - one frame will be absolutely time dilated and length contacted; thus a full 'Ether Transformation' (though this cannot be a group) and a velocity addition law are derived, the Twin's Paradox is reconside...

  9. Special Relativity and Superluminal Motions a Discussion of Some Recent Experiments

    CERN Document Server

    Recami, E; Garavaglia, R

    2000-01-01

    Some experiments, performed at Berkeley, Cologne, Florence, Vienna, Orsay and Rennes led to the claim that something seems to travel with a group velocity larger than the speed c of light in vacuum. Various other experimental results seem to point in the same direction: For instance, localized wavelet­type solutions of Maxwell equations have been found, both theoretically and experimentally, that travel with Superluminal speed. Even muonic and electronic neutrinos ­ it has been proposed ­ might be "tachyons", since their square mass appears to be negative. With regard to the first­mentioned experiments, it was very recently claimed by Guenter Nimtz that those results with evanescent waves or "tunneling photons" ­ implying Superluminal signal and impulse transmission ­ violate Einstein causality. In this note, on the contrary, we want to stress that all such results do not place relativistic causality in jeopardy, even if they refer to actual tachyonic motions: In fact, Special Relativity can cope even w...

  10. Superluminal motion in the double-lobed quasar 3C 245

    Science.gov (United States)

    Hough, D. H.; Readhead, A. C. S.

    1987-01-01

    VLBI observations of 3C 245 obtained at 10.7 GHz with the Mark III array at five epochs in 1981-1986 are reported. The data-reduction and model-fitting procedures are explained, and the results are presented in tables, graphs, and maps along with previously published data on 11 other superluminal sources. The central component of the quasar is found to have an apparent transverse velocity of (3.1 + or - 1.4) c/h, assuming H0 = 100h km/s Mpc and q0 = 0.5. From the apparent source orientation (based on R, variability, apparent curvature, and projected linear size) it is inferred that the apparent transverse velocity is anticorrelated with the angle to the line of sight, as predicted by relativistic-beaming models of superluminal motion.

  11. BL Lacertae variability and superluminal motion via a helical filament/shock interface

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, A. (Georgia State Univ., Atlanta (USA))

    1990-08-01

    The combination of a helical filament found by VLA observations at kpc scales in the M87 jet by Hardee, Owen, and Cornwell (1989) with a shock propagating down a jet suggests a kinematical model that could explain much of the flux variation in sources where the jet is aligned almost directly toward the observer, such as BL Lacertae objects. This model also naturally generates a superluminal pattern speed. The assumptions made by a first-order approximate model are discussed. Reasonable values for jet opening angle, viewing angle, shock speed, and radiative particle speed are used to match the model both to flux variations and superluminal motion of BL Lacertae itself with reasonable success. 33 refs.

  12. Special relativity and superluminal motions: a discussion of some recent experiments

    Energy Technology Data Exchange (ETDEWEB)

    Recami, E. [Istituto Nazionale di Fisica Nucleare, Milan (Italy)]|[Bergamo Univ., Bergamo (Italy). Fac. di Ingegneria]|[State Univ. of Campinas, Campinas (Brazil); Fontana, F. [Pirelli Cavi, Milan (Italy). R and D sector; Garavaglia, R. [Milan Univ., Milan (Italy). Dipt. di Scienze dell' Informazione

    2000-03-01

    Some experiments, performed at Berkeley, Cologne, Florence, Vienna, Orsay and Rennes led to the claim that something seems to travel with a group velocity larger than the speed c of light in vacuum. Various other experimental results seem to point in the same direction. For instance, localized wavelet-type solutions of Maxwell equations have been found, both theoretically and experimentally, that travel with superluminal speed. Even mounic and electronic neutrinos - it has been proposed - might be tachyons, since their square mass appears to be negative. With regard to the first mentioned experiments, it was very recently claimed by Guenter Nimtz that those results with evanescent waves or tunnelling photons - implying superluminal signal and impulse transmission - violate Einstein causality. This note, on the contrary, discusses that all such results do not place relativistic causality in jeopardy, even if they refer to actual tachyonic motions. In fact, special relativity can cope even with also the known paradoxes , devised for faster than light motion, even if this is not widely recognized. Here the paper shows, in detail and rigorously, how to solve the oldest casual paradox. originally proposed by Tolman, which is the kernel of many further tachyon paradoxes. The key to the solution is a careful application of tachyon mechanics, as it unambiguously follows from special relativity.

  13. The superluminal motion of Gamma-Ray-Burst sources and the complex afterglow of GRB 030329

    CERN Document Server

    Dado, S; De Rújula, Alvaro; Dado, Shlomo; Dar, Arnon

    2004-01-01

    The source of the very bright Gamma-Ray Burst GRB 030329 is close enough to us for there to be a hope to measure or significantly constrain its putative superluminal motion. Such a phenomenon is expected in the ``Cannonball'' (CB) model of GRBs. Recent precise data on the optical and radio afterglow of this GRB --which demonstrated its very complex structure-- allow us to pin down the CB-model's prediction for the afterglow-source position as a function of time. It has been stated that (the unpublished part of) the new radio data ``unequivocably disprove'' the CB model. We show how greatly exaggerated that obituary announcement was, and how precise a refined analysis of the data would have to be, to be still of interest.

  14. MOJAVE. X. PARSEC-SCALE JET ORIENTATION VARIATIONS AND SUPERLUMINAL MOTION IN ACTIVE GALACTIC NUCLEI

    Energy Technology Data Exchange (ETDEWEB)

    Lister, M. L.; Richards, J. L. [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States); Aller, M. F.; Aller, H. D. [Department of Astronomy, University of Michigan, 817 Dennison Building, Ann Arbor, MI 48109 (United States); Homan, D. C. [Department of Physics, Denison University, Granville, OH 43023 (United States); Kellermann, K. I. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Kovalev, Y. Y. [Astro Space Center of Lebedev Physical Institute, Profsoyuznaya 84/32, 117997 Moscow (Russian Federation); Pushkarev, A. B.; Ros, E.; Savolainen, T., E-mail: mlister@purdue.edu [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)

    2013-11-01

    We describe the parsec-scale kinematics of 200 active galactic nucleus (AGN) jets based on 15 GHz Very Long Baseline Array (VLBA) data obtained between 1994 August 31 and 2011 May 1. We present new VLBA 15 GHz images of these and 59 additional AGNs from the MOJAVE and 2 cm Survey programs. Nearly all of the 60 most heavily observed jets show significant changes in their innermost position angle over a 12-16 yr interval, ranging from 10° to 150° on the sky, corresponding to intrinsic variations of ∼0.°5 to ∼2°. The BL Lac jets show smaller variations than quasars. Roughly half of the heavily observed jets show systematic position angle trends with time, and 20 show indications of oscillatory behavior. The time spans of the data sets are too short compared to the fitted periods (5-12 yr), however, to reliably establish periodicity. The rapid changes and large jumps in position angle seen in many cases suggest that the superluminal AGN jet features occupy only a portion of the entire jet cross section and may be energized portions of thin instability structures within the jet. We have derived vector proper motions for 887 moving features in 200 jets having at least five VLBA epochs. For 557 well-sampled features, there are sufficient data to additionally study possible accelerations. We find that the moving features are generally non-ballistic, with 70% of the well-sampled features showing either significant accelerations or non-radial motions. Inward motions are rare (2% of all features), are slow (<0.1 mas yr{sup –1}), are more prevalent in BL Lac jets, and are typically found within 1 mas of the unresolved core feature. There is a general trend of increasing apparent speed with distance down the jet for both radio galaxies and BL Lac objects. In most jets, the speeds of the features cluster around a characteristic value, yet there is a considerable dispersion in the distribution. Orientation variations within the jet cannot fully account for the

  15. VLBI limits on the proper motion of the 'core' of the superluminal quasar 3C345

    Science.gov (United States)

    Bartel, N.; Herring, T. A.; Ratner, M. I.; Shapiro, I. I.; Corey, B. E.

    1986-01-01

    VLBI (very-long-baseline interferometry) observations between 1971 and 1983 have been used to determine the positions of the 'core' of the quasar 3C345 relative to the more distant compact quasar NRAO512 with a fractional uncertainty as small as two parts in a hundred million. The core of 3C345 appears stationary in right ascension to within 20 arc microsec/yr, a subluminal bound corresponding to 0.7c. The apparent velocities of the jets are superluminal, up to 14c in magnitude.

  16. Simulating superluminal physics with superconducting circuit technology

    Science.gov (United States)

    Sabín, Carlos; Peropadre, Borja; Lamata, Lucas; Solano, Enrique

    2017-09-01

    We provide tools for the quantum simulation of superluminal motion with superconducting circuits. We show that it is possible to simulate the motion of a superconducting qubit at constant velocities that exceed the speed of light in the electromagnetic medium and the subsequent emission of Ginzburg radiation. We also consider possible setups for simulating the superluminal motion of a mirror, finding a link with the super-radiant phase transition of the Dicke model.

  17. Superluminal neutrinos

    OpenAIRE

    Franklin, Jerrold

    2011-01-01

    Comment: The energy dependence of version 1 did not agree with that observed by OPERA. In version 2, an energy dependent potential is shown to be capable of producing superluminal propagation due to the interaction of neutrinos with matter. Many references have been added

  18. Superluminal antenna

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, John; Earley, Lawrence M.; Krawczyk, Frank L.; Potter, James M.; Romero, William P.; Wang, Zhi-Fu

    2017-03-28

    A superluminal antenna element integrates a balun element to better impedance match an input cable or waveguide to a dielectric radiator element, thus preventing stray reflections and consequent undesirable radiation. For example, a dielectric housing material can be used that has a cutout area. A cable can extend into the cutout area. A triangular conductor can function as an impedance transition. An additional cylindrical element functions as a sleeve balun to better impedance match the radiator element to the cable.

  19. Superluminal censorship

    OpenAIRE

    Visser, Matt; Bassett, Bruce; Liberati, Stefano

    1998-01-01

    We argue that ``effective'' superluminal travel, potentially caused by the tipping over of light cones in Einstein gravity, is always associated with violations of the null energy condition (NEC). This is most easily seen by working perturbatively around Minkowski spacetime, where we use linearized Einstein gravity to show that the NEC forces the light cones to contract (narrow). Given the NEC, the Shapiro time delay in any weak gravitational field is always a delay relative to the Minkowski ...

  20. Synchro-Compton emission from superluminal sources

    Science.gov (United States)

    Marscher, Alan P.

    1987-01-01

    The application of synchro-Compton theory to real compact radio sources, the question of a self-Compton origin of the X-rays in radio-loud quasars and active galactic nuclei, and the phenomenology of superluminal motion are discussed in a review of research concerning synchro-Compton emission from superluminal sources. After examining the basic synchro-Compton theory of ideal sources, applications of the theory to real sources is discussed. It is concluded that the Compton problem and total energy requirements are not substantially mitigated by considering source structures more complicated than the multiple, uniform-component model used by most investigators. Also, alternatives to the standard model of superluminal motion are discussed, focusing on the assumptions usually made when interpreting superluminal sources.

  1. Superluminal Dark Neutrinos

    OpenAIRE

    Aref'eva, Irina Ya.; Volovich, Igor V.

    2011-01-01

    The OPERA collaboration has claimed the discovery of supeluminal neutrino propagation. However the superluminal interpretation of the OPERA result was refuted by Cohen and Glashow because it was shown that such superluminal neutrinos would lose energy rapidly via the bremsstrahlung of electron-positron pairs (arXiv:1109.6562). We note that the superluminal interpretation is still possible if there exists a new (dark) neutrino which can propagate with a superluminal velocity and which couples ...

  2. Pilot KaVA monitoring on the M 87 jet: Confirming the inner jet structure and superluminal motions at sub-pc scales

    Science.gov (United States)

    Hada, Kazuhiro; Park, Jong Ho; Kino, Motoki; Niinuma, Kotaro; Sohn, Bong Won; Ro, Hyun Wook; Jung, Taehyun; Algaba, Juan-Carlos; Zhao, Guang-Yao; Lee, Sang-Sung; Akiyama, Kazunori; Trippe, Sascha; Wajima, Kiyoaki; Sawada-Satoh, Satoko; Tazaki, Fumie; Cho, Ilje; Hodgson, Jeffrey; Lee, Jeong Ae; Hagiwara, Yoshiaki; Honma, Mareki; Koyama, Shoko; Oh, Junghwan; Lee, Taeseak; Yoo, Hyemin; Kawaguchi, Noriyuki; Roh, Duk-Gyoo; Oh, Se-Jin; Yeom, Jae-Hwan; Jung, Dong-Kyu; Oh, Chungsik; Kim, Hyo-Ryoung; Hwang, Ju-Yeon; Byun, Do-Young; Cho, Se-Hyung; Kim, Hyun-Goo; Kobayashi, Hideyuki; Shibata, Katsunori M.

    2017-08-01

    We report the initial results of our high-cadence monitoring program on the radio jet in the active galaxy M 87, obtained by the KVN and VERA Array (KaVA) at 22 GHz. This is a pilot study that preceded a larger KaVA-M 87 monitoring program, which is currently ongoing. The pilot monitoring was mostly performed every two to three weeks from 2013 December to 2014 June, at a recording rate of 1 Gbps, obtaining data for a total of ten epochs. We successfully obtained a sequence of good quality radio maps that revealed the rich structure of this jet from ≲1 mas to 20 mas, corresponding to physical scales (projected) of ∼0.1-2 pc (or ∼140-2800 Schwarzschild radii). We detected superluminal motions at these scales, together with a trend of gradual acceleration. The first evidence for such fast motions and acceleration near the jet base were obtained from recent VLBA studies at 43 GHz, and the fact that very similar kinematics are seen at a different frequency and time with a different instrument suggests that these properties are fundamental characteristics of this jet. This pilot program demonstrates that KaVA is a powerful VLBI array for studying the detailed structural evolution of the M 87 jet and also other relativistic jets.

  3. Superluminal censorship

    Energy Technology Data Exchange (ETDEWEB)

    Visser, Matt; Bassett, B.A.; Liberati, S

    2000-06-01

    We argue that 'effective' superluminal travel, potentially caused by the tipping over of light cones in Einstein gravity, is always associated with violations of the null energy condition (NEC). This is most easily seen by working perturbatively around Minkowski spacetime, where we use linearized Einstein gravity to show that the NEC forces the light cones to contract (narrow). Given the NEC, the Shapiro time delay in any weak gravitational field is always a delay relative to the Minkowski background, and never an advance. Furthermore, any object travelling within the lightcones of the weak gravitational field is similarly delayed with respect to the minimum traversal time possible in the background Minkowski geometry.

  4. Superluminal light echoes in astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Falla, D F; Floyd, M J; Potter, A G [Department of Physics, University of Wales, Aberystwyth, SY23 3BZ (United Kingdom)

    2003-03-01

    The echo produced when a light 'pulse' from a stellar source (e.g. a nova or supernova) is reflected by circumstellar or interstellar material can appear as a luminous ring expanding at a rate that can be superluminal, i.e. having an apparent motion within the source, transverse to the observer's line of sight, at a speed greater than that of light. 'Light-echo optics' applied to the star RS Puppis and its nebula suggests that when nebular features in peripheral regions of circumstellar-shell images are observed, superluminal effects are not evident; however, such observations can give the stellar distance from the observer. Light-echo optics for an interstellar plane sheet, inclined to the observer's line of sight, can be applied to Nova GK Persei 1901 and SN 1987A, which show superluminal effects. For SN 1987A, an intense thermal x-ray source should be produced in AD 2003, when the advancing supernova ejecta interact with a circumstellar ring, 250 light days in radius: the arc-shaped x-ray image, while not actually a 'radiation echo', should expand at a superluminal rate for about 75 days from the time of its first appearance, and also for the same time before the completion of its 'circuit' around the ring.

  5. DISCOVERY OF SUB- TO SUPERLUMINAL MOTIONS IN THE M87 JET: AN IMPLICATION OF ACCELERATION FROM SUB-RELATIVISTIC TO RELATIVISTIC SPEEDS

    Energy Technology Data Exchange (ETDEWEB)

    Asada, Keiichi; Nakamura, Masanori; Inoue, Makoto [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Doi, Akihiro [Institute of Space and Astronautial Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuou-ku, Sagamihara, Kanagawa 229-8510 (Japan); Nagai, Hiroshi, E-mail: asada@asiaa.sinica.edu.tw, E-mail: nakamura@asiaa.sinica.edu.tw [National Astronomical Observatory of Japan, 2-21-1, Osawa, Tokyo 81-8588 (Japan)

    2014-01-20

    The velocity field of the M87 jet from milli-arcsecond (mas) to arcsecond scales is extensively investigated together with new radio images taken from European VLBI Network (EVN) observations. We detected proper motions of components located at between 160 mas from the core and the HST-1 complex for the first time. Newly derived velocity fields exhibit a systematic increase from sub- to superluminal speeds in the upstream of HST-1. If we assume that the observed velocities reflect the bulk flow, here we suggest that the M87 jet may be gradually accelerated through a distance of 10{sup 6} times the Schwarzschild radius of the supermassive black hole. The acceleration zone is co-spatial with the jet parabolic region, which is interpreted as the collimation zone of the jet. The acceleration and collimation take place simultaneously, which we suggest is characteristic of magnetohydrodynamic flows. The distribution of the velocity field has a peak at HST-1, which is considered as the site of over-collimation, and shows a deceleration downstream of HST-1 where the jet is conical. Our interpretation of the velocity map in the M87 jet provides a hypothesis for active galactic nuclei which suggests that the acceleration and collimation zone of relativistic jets extends over the whole scale within the sphere of influence of the supermassive black hole.

  6. Superluminal light echoes in astronomy

    CERN Document Server

    Falla, D F; Potter, A G

    2003-01-01

    The echo produced when a light 'pulse' from a stellar source (e.g. a nova or supernova) is reflected by circumstellar or interstellar material can appear as a luminous ring expanding at a rate that can be superluminal, i.e. having an apparent motion within the source, transverse to the observer's line of sight, at a speed greater than that of light. 'Light-echo optics' applied to the star RS Puppis and its nebula suggests that when nebular features in peripheral regions of circumstellar-shell images are observed, superluminal effects are not evident; however, such observations can give the stellar distance from the observer. Light-echo optics for an interstellar plane sheet, inclined to the observer's line of sight, can be applied to Nova GK Persei 1901 and SN 1987A, which show superluminal effects. For SN 1987A, an intense thermal x-ray source should be produced in AD 2003, when the advancing supernova ejecta interact with a circumstellar ring, 250 light days in radius: the arc-shaped x-ray image, while not ...

  7. Superluminality in dilatationally invariant generalized Galileon theories

    Science.gov (United States)

    Kolevatov, R. S.

    2015-12-01

    We consider small perturbations about homogeneous backgrounds in dilatationally invariant Galileon models. The issues we address are stability (absence of ghosts and gradient instabilities) and superluminality. We show that in the Minkowski background, it is possible to construct the Lagrangian in such a way that any homogeneous Galileon background solution is stable and small perturbations about it are subluminal. On the other hand, in the case of Friedmann-Lemaitre-Robertson-Walker (FLRW) backgrounds, for any Lagrangian functions there exist homogeneous background solutions to the Galileon equation of motion and time dependence of the scale factor, such that the stability conditions are satisfied, but the Galileon perturbations propagate with superluminal speed.

  8. Galactic superluminal sources at different wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Iyudin, A.F

    2000-05-01

    Jet-like superluminal motion was observed in few types of the astrophysical systems. The early observations were made from radio galaxies with an active galactic nuclei (AGN) harboring accreting supermassive black hole. Similar type superluminal jets were detected in some of the hard X-ray transients with a stellar mass black hole. Galactic black-hole X-ray binaries with relativistic jets are reminiscent, though on a much smaller scale, of many of the phenomena seen in AGNs. The contemporaneous multiwavelength observations of the superluminal sources reveal the close connection between instabilities obviously originated in the accretion disk and manifested by their short timescale signature in X-rays, and the ejection of clouds of relativistic plasma observed as synchrotron emission at longer wavelengths. In this review I will attempt to summarise the observational status of the galactic relativistic jet sources and to stress out the importance of the multiwavelength observations.

  9. Optimal superluminal systems.

    Science.gov (United States)

    Macke, Bruno; Ségard, Bernard; Wielonsky, Franck

    2005-09-01

    We demonstrate that significant effects in the "superluminal propagation" of light pulses cannot be observed without involving systems whose gain explodes outside the pulse spectrum. We explicitly determine the minimum norm of the gain to attain given superluminal effects and the transfer function of the corresponding optimal system. The gain norms, which would be required with the most efficient systems considered up to now (dispersive media, photonic barriers) to attain the same effects, are shown to exceed the minimum by several orders of magnitude. We finally estimate the largest superluminal advances which could be attained in a realistic experiment.

  10. No apparent superluminal motion in the first-known jetted tidal disruption event Swift J1644+5734

    Science.gov (United States)

    Yang, J.; Paragi, Z.; van der Horst, A. J.; Gurvits, L. I.; Campbell, R. M.; Giannios, D.; An, T.; Komossa, S.

    2016-10-01

    The first-known tidal disruption event (TDE) with strong evidence for a relativistic jet - based on extensive multiwavelength campaigns - is Swift J1644+5734. In order to directly measure the apparent speed of the radio jet, we performed very long baseline interferometry (VLBI) observations with the European VLBI network (EVN) at 5 GHz. Our observing strategy was to identify a very nearby and compact radio source with the real-time e-EVN, and then utilize this source as a stationary astrometry reference point in the later five deep EVN observations. With respect to the in-beam source FIRST J1644+5736, we have achieved a statistical astrometric precision about 12 μas (68 per cent confidence level) per epoch. This is one of the best phase-referencing measurements available to date. No proper motion has been detected in the Swift J1644+5734 radio ejecta. We conclude that the apparent average ejection speed between 2012.2 and 2015.2 was less than 0.3c with a confidence level of 99 per cent. This tight limit is direct observational evidence for either a very small viewing angle or a strong jet deceleration due to interactions with a dense circum-nuclear medium, in agreement with some recent theoretical studies.

  11. POSSIBLE DETECTION OF APPARENT SUPERLUMINAL INWARD MOTION IN MARKARIAN 421 AFTER THE GIANT X-RAY FLARE IN 2010 FEBRUARY

    Energy Technology Data Exchange (ETDEWEB)

    Niinuma, K. [Graduate School of Science and Engineering, Yamaguchi University, Yamaguchi 753-8511 (Japan); Kino, M.; Oyama, T. [Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan); Nagai, H. [ALMA-J Project, National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan); Isobe, N. [Institute of Space and Astronautics, Japan Aerospace Exploration Agency, Yoshinodai, Chuo, Sagamihara 252-5210 (Japan); Gabanyi, K. E. [Hungarian Academy of Sciences, Research Group for Physical Geodesy and Geodynamics, FOMI Satellite Geodetic Observatory Budapest, 1592 Budapest (Hungary); Hada, K. [INAF Istituto di Radioastronomia, via Gobetti 101, I-40129 Bologna (Italy); Koyama, S. [Department of Astronomy, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8654 (Japan); Asada, K. [Academia Sinica Institute of Astronomy and Astrophysics, Taipei 10617, Taiwan (China); Fujisawa, K., E-mail: niinuma@yamaguchi-u.ac.jp [Research Institute for Time Studies, Yamaguchi University, Yamaguchi 753-8511 (Japan)

    2012-11-10

    We report on the very long baseline interferometry (VLBI) follow-up observations using the Japanese VLBI Network array at 22 GHz for the largest X-ray flare of TeV blazar Mrk 421 that occurred in 2010 mid-February. The total of five epochs of observations were performed at intervals of about 20 days between 2010 March 7 and May 31. No newborn component associated with the flare was seen directly in the total intensity images obtained by our multi-epoch VLBI observations. However, one jet component located at {approx}1 mas northwest from the core was able to be identified, and its proper motion can be measured as -1.66 {+-} 0.46 mas yr{sup -1}, which corresponds to an apparent velocity of -3.48 {+-} 0.97c. Here, this negative velocity indicates that the jet component was apparently moving toward the core. As the most plausible explanation, we discuss that the apparent negative velocity was possibly caused by the ejection of a new component, which could not be resolved with our observations. In this case, the obtained Doppler factor of the new component is around 10-20, which is consistent with the ones typically estimated by model fittings of spectral energy distribution for this source.

  12. IMMIGRANT WOMEN: BODY AND SUBJECTIVITY IN MOTION

    Directory of Open Access Journals (Sweden)

    Rosa Lázaro-Castellanos

    2012-01-01

    Full Text Available The visibility of women in contemporary migration has broken with the course and social representation of the organization and implementation of international migration projects are predominantly male (Pedone, 2008. The growing presence of women has inspired a large number of studies have focused on immigrant women and their relationship to the labor market, changes in social structure and family and gender systems in both societies of origin and the destination. However, the literature takes as a center for immigrant women and their relationship to emotions and body are relatively recent, the most important contributions are found in disciplines such as anthropology or psychology. The transnational perspective little has reflected on the physical and mental health, emotions and subjectivities of women, resulting from their migration experience. From a socio-anthropological point of view of immigrants and bring their own notions of subjectivity related to gender, race or social class, do not always coincide with those in the host country. We suspect that the same applies to perception, practices and experiences on the body and emotions of women.

  13. The Superluminal Tunneling Story

    OpenAIRE

    Aichmann, Horst; Nimtz, Günter

    2013-01-01

    Since 1992 experimental evidence of superluminal (faster than light, FTL) signals are causing much excitement in the physical community and in the media. Superluminal signal velocity and zero time tunneling was first observed in an analog tunneling experiment with microwaves. Recently, the conjectured zero time of electron was claimed to be observed in ionizing helium. The FTL signal velocity was reproduced with infrared light and with various tunneling barriers in several laboratories worldw...

  14. Superluminal Neutrinos and Monopoles

    OpenAIRE

    Wang, Peng; Wu, Houwen; Yang, Haitang

    2011-01-01

    In this letter, we show that superluminal neutrinos announced by OPERA could be explained by the existence of a monopole, which is left behind after the spontaneous symmetry breaking (SSB) phase transition of some scalar fields in the universe. We assume the 't Hooft-Polyakov monopole couples to the neutrinos but not photon fields. The monopole introduces a different effective metric to the neutrinos from the one experienced by photons. We find that the superluminal propagation only exists in...

  15. A model of superluminal neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Marfatia, D., E-mail: marfatia@ku.edu [Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045 (United States); Paes, H. [Fakultaet fuer Physik, Technische Universitaet Dortmund, D-44221 Dortmund (Germany); Pakvasa, S. [Department of Physics and Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Weiler, T.J. [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States)

    2012-02-07

    Motivated by the tentative observation of superluminal neutrinos by the OPERA experiment, we present a model of active-sterile neutrino oscillations in which sterile neutrinos are superluminal and active neutrinos appear superluminal by virtue of neutrino mixing. The model demonstrates some interesting possibilities and challenges that apply to a large class of models aiming to explain the OPERA result.

  16. A model of superluminal neutrinos

    OpenAIRE

    Marfatia, D.; Päs, H.; Pakvasa, S.; Weiler, T. J.

    2011-01-01

    Motivated by the tentative observation of superluminal neutrinos by the OPERA experiment, we present a model of active-sterile neutrino oscillations in which sterile neutrinos are superluminal and active neutrinos appear superluminal by virtue of neutrino mixing. The model demonstrates some interesting possibilities and challenges that apply to a large class of models aiming to explain the OPERA result.

  17. THE SUPERLUMINAL CHARACTER OF THE COMPACT STEEP SPECTRUM QUASAR 3C-216

    NARCIS (Netherlands)

    VENTURI, T; PEARSON, TJ; BARTHEL, PD; HERBIG, T

    We report the results of fourth epoch VLBI observations at 4990.99 MHz, with a resolution of approximately 1 mas, of the compact steep-spectrum quasar 3C 216. Superluminal motion in this object is confirmed. Although a constant superluminal expansion at upsilon(app) = 3.9c +/- 0.6 is not ruled out,

  18. Superluminality in DGP

    CERN Document Server

    Hinterbichler, Kurt; Porrati, Massimo

    2009-01-01

    We reconsider the issue of superluminal propagation in the DGP model of infrared modified gravity. Superluminality was argued to exist in certain otherwise physical backgrounds by using a particular, physically relevant scaling limit of the theory. In this paper, we exhibit explicit five-dimensional solutions of the full theory that are stable against small fluctuations and that indeed support superluminal excitations. The scaling limit is neither needed nor invoked in deriving the solutions or in the analysis of its small fluctuations. To be certain that the superluminality found here is physical, we analyze the retarded Green's function of the scalar excitations, finding that it is causal and stable, but has support on a widened light-cone. We propose to use absence of superluminal propagation as a method to constrain the parameters of the DGP model. As a first application of the method, we find that whenever the 4D energy density is a pure cosmological constant and a hierarchy of scales exists between the ...

  19. Subject-Motion Correction in HARDI Acquisitions: Choices and Consequences.

    Science.gov (United States)

    Elhabian, Shireen; Gur, Yaniv; Vachet, Clement; Piven, Joseph; Styner, Martin; Leppert, Ilana R; Pike, G Bruce; Gerig, Guido

    2014-01-01

    Diffusion-weighted imaging (DWI) is known to be prone to artifacts related to motion originating from subject movement, cardiac pulsation, and breathing, but also to mechanical issues such as table vibrations. Given the necessity for rigorous quality control and motion correction, users are often left to use simple heuristics to select correction schemes, which involves simple qualitative viewing of the set of DWI data, or the selection of transformation parameter thresholds for detection of motion outliers. The scientific community offers strong theoretical and experimental work on noise reduction and orientation distribution function (ODF) reconstruction techniques for HARDI data, where post-acquisition motion correction is widely performed, e.g., using the open-source DTIprep software (1), FSL (the FMRIB Software Library) (2), or TORTOISE (3). Nonetheless, effects and consequences of the selection of motion correction schemes on the final analysis, and the eventual risk of introducing confounding factors when comparing populations, are much less known and far beyond simple intuitive guessing. Hence, standard users lack clear guidelines and recommendations in practical settings. This paper reports a comprehensive evaluation framework to systematically assess the outcome of different motion correction choices commonly used by the scientific community on different DWI-derived measures. We make use of human brain HARDI data from a well-controlled motion experiment to simulate various degrees of motion corruption and noise contamination. Choices for correction include exclusion/scrubbing or registration of motion corrupted directions with different choices of interpolation, as well as the option of interpolation of all directions. The comparative evaluation is based on a study of the impact of motion correction using four metrics that quantify (1) similarity of fiber orientation distribution functions (fODFs), (2) deviation of local fiber orientations, (3) global

  20. Apparent Superluminal Behavior

    NARCIS (Netherlands)

    Jackson, A. D.; Lande, A.; Lautrup, B.

    2000-01-01

    Abstract: The apparent superluminal propagation of electromagnetic signals seen in recent experiments is shown to be the result of simple and robust properties of relativistic field equations. Although the wave front of a signal passing through a classically forbidden region can never move faster

  1. Superluminal neutrino, flavor, and relativity

    OpenAIRE

    Klinkhamer, F. R.

    2011-01-01

    Modified neutrino dispersion relations, which still obey the relativity principle, can have both a superluminal (muon-type) neutrino and a luminal (electron-type) neutrino, as long as neutrino-mass effects can be neglected. The idea is to allow for flavor-dependent deformed Lorentz transformations and an appropriate hierarchy of energy scales. If OPERA's result on a superluminal velocity of the muon-neutrino is confirmed, the model has a matching superluminal velocity of the corresponding cha...

  2. MONITORING OF THE SUPERLUMINAL QUASAR 4C 34.47

    NARCIS (Netherlands)

    HOOIMEYER, JRA; BARTHEL, PD; SCHILIZZI, RT; MILEY, GK

    10.7 GHz VLBI observations of the giant double-lobed quasar 4C 34.47 (1721 + 343) are presented. Previous VLBI monitoring at 5 GHz indicated the presence of superluminal motion in the core of this large radio source, at velocities of approximately 2.5h-1 c (Barthel et al. 1989). In the present

  3. Apparent Superluminal Behavior

    OpenAIRE

    Jackson, A D; Lande, A.; Lautrup, B.

    2000-01-01

    Abstract: The apparent superluminal propagation of electromagnetic signals seen in recent experiments is shown to be the result of simple and robust properties of relativistic field equations. Although the wave front of a signal passing through a classically forbidden region can never move faster than light, an attenuated replica of the signal is reproduced ``instantaneously'' on the other side of the barrier. The reconstructed signal, causally connected to the forerunner rather than the bulk...

  4. Noncausal Superluminal Nonlocal Signalling

    OpenAIRE

    Srikanth, R.

    1999-01-01

    We propose a thought experiment for classical superluminal signal transmission based on the quantum nonlocal influence of photons on their momentum entangled EPR twins. The signal sender measures either position or momentum of particles in a pure ensemble of the entangled pairs, leaving their twins as localized particles or plane waves. The signal receiver distinguishes these outcomes interferometrically using a double slit interferometer modified by a system of optical filters. Since the col...

  5. Superluminal graviton propagation

    Science.gov (United States)

    Benakli, Karim; Chapman, Shira; Darmé, Luc; Oz, Yaron

    2016-10-01

    We use the method of characteristics to study superluminal graviton (which we call the swift graviton) propagation in theories of higher-curvature gravity of the form (Riemann)2 , (Riemann)3 , ∇2(Riemann)2 and (Riemann)4 . We consider a p p -wave background. When probed by gravitons with an appropriate polarization, several of the gravitational theories under consideration exhibit characteristic hypersurfaces outside the flat spacetime light cone.

  6. Superluminal Gravitational Waves

    OpenAIRE

    Moffat, J. W.

    2014-01-01

    The quantum gravity effects of vacuum polarization of gravitons propagating in a curved spacetime cause the quantum vacuum to act as a dispersive medium with a refractive index. Due to this dispersive medium gravitons acquire superluminal velocities. The dispersive medium is produced by higher derivative curvature contributions to the effective gravitational action. It is shown that in a Friedmann-Lema\\^{i}tre-Robertson-Walker spacetime in the early universe near the Planck time $t_{\\rm PL}\\g...

  7. ''Superluminal'' scalar fields and cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Vikman, A. [LMU-ASC, Muenchen (Germany)

    2007-07-01

    It is well known that in manifestly Lorentz invariant theories with non-trivial kinetic terms, perturbations around some classical dynamical backgrounds can travel faster than light. These exotic ''superluminal'' models may have interesting consequences for cosmology and astrophysics. I begin my talk by explaining how a nonlinearity of equations of motion can yield a superluminal propagation. Further I consider an inflationary model with the sound speed larger than the speed of light. The most interesting property of the model is a higher, in comparison to the standard chaotic inflation, amount of gravitational waves produced during inflation. Finally I discuss causality and stability of these models. (orig.)

  8. Models of subjective response to in-flight motion data

    Science.gov (United States)

    Rudrapatna, A. N.; Jacobson, I. D.

    1973-01-01

    Mathematical relationships between subjective comfort and environmental variables in an air transportation system are investigated. As a first step in model building, only the motion variables are incorporated and sensitivities are obtained using stepwise multiple regression analysis. The data for these models have been collected from commercial passenger flights. Two models are considered. In the first, subjective comfort is assumed to depend on rms values of the six-degrees-of-freedom accelerations. The second assumes a Rustenburg type human response function in obtaining frequency weighted rms accelerations, which are used in a linear model. The form of the human response function is examined and the results yield a human response weighting function for different degrees of freedom.

  9. Subjective Evaluations of Motion Area and Velocity Characteristics of Dual Manipulator in Young and Elderly People

    Science.gov (United States)

    Yoda, Mitsumasa; Yoda, Asako; Shiota, Yasuhito

    In this study, we conducted a subjective evaluation experiment of a dual manipulator, which exhibits different motion characteristics. There are three motion characteristics: two of which are age-related, and the third is a robot motion characteristic and is newly added to these two motions. The motions are evaluated from motion areas and motion velocities. Subjects are elderly and young people, and the impressions of the motions are compared in two of the different age groups by the Semantic Differential (SD) method. The obtained results indicate that there are age differences in the evaluation of three manipulator motion areas. The elderly people show a higher reliability and a higher familiarity in a robot motion area than in the other two motions. The elderly people seem to be more affected by the manipulator motion than the young people. Therefore, a careful consideration is required when planning the motion of a manipulator for elderly people.

  10. Relativistic Superluminal Neutrinos

    OpenAIRE

    Kehagias, Alex

    2011-01-01

    We present a possible solution to the reported OPERA anomaly for the speed of neutrinos, based on the idea that it is a local effect caused by a scalar field sourced by the earth. The coupling of the scalar to neutrinos effectively changes the background metric where neutrinos propagate, leading to superluminality. The strength of the coupling is set by a new mass scale, which should be at $1\\, {\\rm TeV}$ to account for the OPERA anomaly. Moreover, if this scenario is valid, the neutrino velo...

  11. Quantum Superluminal Communication

    CERN Document Server

    Shan\\Gao

    2003-01-01

    The implications of quantum nonlocality are briefly reviewed. It is shown that the collapse of the wave function requires the existence of a preferred Lorentz frame. This opens the first door to quantum superluminal communication (QSC). The possibility of the existence of QSC is further analyzed. We demonstrate that the combination of the collapse of the wave function and the consciousness of the observer will permit the observer to distinguish nonorthogonal states under some condition. This provides a principle for realizing QSC. A practical QSC scheme and some optimizing schemes are given based upon the QSC principle. Some evidence of the existence of QSC is also discussed.

  12. Superluminal waves in amplifying media

    Energy Technology Data Exchange (ETDEWEB)

    Oraevsky, Anatolii N [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    1998-12-31

    In amplifying media steady-state waves can travel faster than the speed of light in vacuum without violating the principles of special relativity. The possibility of generating superluminal waves in induced elementary particle production processes is discussed. (methodological notes)

  13. Superluminous Supernovae hydrodynamic models

    Science.gov (United States)

    Orellana, M.

    2017-07-01

    We use our radiation hydrodynamic code in order to simulate magnetar powered Superluminous Supernovae (SLSNe). It is assumed that a central rapidly rotating magnetar deposits all its rotational energy into the ejecta where is added to the usual power. The magnetar luminosity and spin-down timescale are adopted as the free parameters of the model. For the case of ASASSN-15lh, which has been claimed as the most luminous supernova ever discovered, we have found physically plausible magnetar parameters can reproduce the overall shape of the bolometric light curve (LC) provided the progenitor mass is ≍ 8M⊙. The ejecta dynamics of this event shows signs of the magnetar energy input which deviates the expansion from the usually assumed homologous behaviour. Our numerical experiments lead us to conclude that the hydrodynamical modeling is necessary in order to derive the properties of powerful magnetars driving SLSNe.

  14. Unified interpretation of superluminal behaviors in wave propagation

    Energy Technology Data Exchange (ETDEWEB)

    Ranfagni, A. [Istituto di Fisica Applicata ' Nello Carrara' , Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Firenze (Italy); Viliani, G. [Dipartimento di Fisica, Universita di Trento, 38050 Povo, Trento (Italy); Ranfagni, C. [Facolta di Scienze Matematiche Fisiche e Naturali, Corso di Laurea in Fisica dell' Universita di Firenze, Firenze (Italy); Mignani, R. [Dipartimento di Fisica ' Edoardo Amaldi' , Universita degli Studi di Roma ' Roma Tre' , Via della Vasca Navale 84, 00146 Roma (Italy); Ruggeri, R. [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Sezione di Firenze, Firenze (Italy)], E-mail: rocco.ruggeri@isc.cnr.it; Ricci, A.M. [Istituto per le Telecomunicazioni e l' Elettronica della Marina Militare ' Giancarlo Vallauri' (Mariteleradar), Viale Italia 72, 57100 Livorno (Italy)

    2007-10-29

    By using two approaches, we demonstrate that superluminal behaviors in wave propagation can be attributed to mechanisms acting in the near-field limit. One approach is based on complex waves, while the other relies on a path-integral treatment of stochastic motion. The results of the two approaches are comparable, and suitable for interpreting the data obtained in microwave experiments; these experiments, over a wide range of distances, show a time advance which, in any case, is limited to nanoseconds.

  15. Subject-Specific Carpal Ligament Elongation in Extreme Positions, Grip, and the Dart Thrower's Motion

    Science.gov (United States)

    Rainbow, Michael J.; Kamal, Robin N.; Moore, Douglas C.; Akelman, Edward; Wolfe, Scott W.; Crisco, Joseph J.

    2015-01-01

    This study examined whether the radiocarpal and dorsal capsular ligaments limit end-range wrist motion or remain strained during midrange wrist motion. Fibers of these ligaments were modeled in the wrists of 12 subjects over multiple wrist positions that reflect high demand tasks and the dart thrower's motion. We found that many of the volar and dorsal ligaments were within 5% of their maximum length throughout the range of wrist motion. Our finding of wrist ligament recruitment during midrange and end-range wrist motion helps to explain the complex but remarkably similar intersubject patterns of carpal motion. PMID:26367853

  16. Quantum noise and superluminal propagation

    Energy Technology Data Exchange (ETDEWEB)

    Segev, Bilha [Department of Chemistry, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, (Israel); Milonni, Peter W. [Theoretical Division (T-4), Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Babb, James F. [Institute for Theoretical Atomic and Molecular Physics, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 (United States); Chiao, Raymond Y. [Department of Physics, University of California, Berkeley, Berkeley, California 94720 (United States)

    2000-08-01

    Causal ''superluminal'' effects have recently been observed and discussed in various contexts. The question arises whether such effects could be observed with extremely weak pulses, and what would prevent the observation of an ''optical tachyon.'' Aharonov, Reznik, and Stern (ARS) [Phys. Rev. Lett. 81, 2190 (1998)] have argued that quantum noise will preclude the observation of a superluminal group velocity when the pulse consists of one or a few photons. In this paper we reconsider this question both in a general framework and in the specific example, suggested by Chiao, Kozhekin, and Kurizki (CKK) [Phys. Rev. 77, 1254 (1996)], of off-resonant, short-pulse propagation in an optical amplifier. We derive in the case of the amplifier a signal-to-noise ratio that is consistent with the general ARS conclusions when we impose their criteria for distinguishing between superluminal propagation and propagation at the speed c. However, results consistent with the semiclassical arguments of CKK are obtained if weaker criteria are imposed, in which case the signal can exceed the noise without being ''exponentially large.'' We show that the quantum fluctuations of the field considered by ARS are closely related to superfluorescence noise. More generally, we consider the implications of unitarity for superluminal propagation and quantum noise and study, in addition to the complete and truncated wave packets considered by ARS, the residual wave packet formed by their difference. This leads to the conclusion that the noise is mostly luminal and delayed with respect to the superluminal signal. In the limit of a very weak incident signal pulse, the superluminal signal will be dominated by the noise part, and the signal-to-noise ratio will therefore be very small. (c) 2000 The American Physical Society.

  17. Superluminal Signaling and Time Machine

    CERN Document Server

    Shan Gao

    2003-01-01

    Recently, time machine becomes a hot topic in the physics community[1-7]. But it is still unclear whether or not time machine does exist. In this short paper, we will analyze the possible relation between superluminal signaling and time machine. It will be shown that the realization of superluminal signaling will exclude the existence of time machine, or vice versa. Furthermore, we denote that the usual proof for the possible existence of time machine may fail due to ignoring the limitation of relativity.

  18. Superluminal self-interacting neutrino

    OpenAIRE

    Trojan, Ernst

    2012-01-01

    The effect of nonlinear self-interaction can be associated with superluminal velocity of neutrino. The power energy spectrum E=p+Cp^a is derived from the nonlinear Dirac equation when interaction term V=\\lambda (\\psi \\gamma_\\mu \\psi \\psi \\gamma^\\mu \\psi)^a is added to the Lagrangian of a free spin-1/2 particle. The superluminal velocity recorded by the OPERA and MINOS collaborations is achieved when the coupling constants are taken in the range a=0.4-1.18 and \\lambda =-(0.5-1.6)x10^-4. The se...

  19. Superluminal travel requires negative energies

    OpenAIRE

    Olum, Ken D.

    1998-01-01

    I investigate the relationship between faster-than-light travel and weak-energy-condition violation, i.e., negative energy densities. In a general spacetime it is difficult to define faster-than-light travel, and I give an example of a metric which appears to allow superluminal travel, but in fact is just flat space. To avoid such difficulties, I propose a definition of superluminal travel which requires that the path to be traveled reach a destination surface at an earlier time than any neig...

  20. Modelling motion sickness and subjective vertical mismatch detailed for vertical motions

    NARCIS (Netherlands)

    Bos, J. E.; van der Bles, W.

    1998-01-01

    In an attempt to predict the amount of motion sickness given any kind of motion stimulus, we describe a model using explicit knowledge of the vestibular system. First, the generally accepted conflict theory is restated in terms of a conflict between a vertical as perceived by the sense organs like

  1. Image motion and context: a between- and within-subjects comparison.

    Science.gov (United States)

    Simons, R F; Detenber, B H; Reiss, J E; Shults, C W

    2000-09-01

    In two previous experiments, we studied how stimulus motion affects both the self-report of emotion experience and the physiological sequelae of emotion. In both studies, image motion intensified emotional responding, and the effect of motion was relatively specific to the arousal dimension of the emotion; there was little evidence that image motion altered the valence of the image. Moving images also appeared to sustain the attention of the participants for a longer period of time than did the still images. In these two experiments, however, image motion was manipulated within participants. In the present experiment, we used a between-subjects manipulation of image motion and found a nearly identical pattern of results. These data indicate that motion inherently increments the arousal value of an image and that this increment is not dependent on the context in which motion is introduced.

  2. Invisibility cloaking without superluminal propagation

    Energy Technology Data Exchange (ETDEWEB)

    Perczel, Janos; Leonhardt, Ulf [School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom); Tyc, Tomas, E-mail: jp394@st-andrews.ac.uk, E-mail: tomtyc@physics.muni.cz, E-mail: ulf@st-andrews.ac.uk [Faculty of Science, Kotlarska 2 and Faculty of Informatics, Botanicka 68a, Masaryk University, 61137 Brno (Czech Republic)

    2011-08-15

    Conventional cloaking based on Euclidean transformation optics requires that the speed of light should tend to infinity on the inner surface of the cloak. Non-Euclidean cloaking still needs media with superluminal propagation. Here we show by giving an example that this is no longer necessary.

  3. Superluminality, black holes and EFT

    Science.gov (United States)

    Goon, Garrett; Hinterbichler, Kurt

    2017-02-01

    Under the assumption that a UV theory does not display superluminal behavior, we ask what constraints on superluminality are satisfied in the effective field theory (EFT). We study two examples of effective theories: quantum electrodynamics (QED) coupled to gravity after the electron is integrated out, and the flat-space galileon. The first is realized in nature, the second is more speculative, but they both exhibit apparent superluminality around non-trivial backgrounds. In the QED case, we attempt, and fail, to find backgrounds for which the superluminal signal advance can be made larger than the putative resolving power of the EFT. In contrast, in the galileon case it is easy to find such backgrounds, indicating that if the UV completion of the galileon is (sub)luminal, quantum corrections must become important at distance scales of order the Vainshtein radius of the background configuration, much larger than the naive EFT strong coupling distance scale. Such corrections would be reminiscent of the non-perturbative Schwarzschild scale quantum effects that are expected to resolve the black hole information problem. Finally, a byproduct of our analysis is a calculation of how perturbative quantum effects alter charged Reissner-Nordstrom black holes.

  4. Coordinated Control of Wave Energy Converters Subject to Motion Constraints

    Directory of Open Access Journals (Sweden)

    Liguo Wang

    2016-06-01

    Full Text Available In this paper, a generic coordinated control method for wave energy converters is proposed, and the constraints on motion amplitudes and the hydrodynamic interaction between converters are considered. The objective of the control problem is to maximize the energy converted from ocean waves, and this is achieved by coordinating the power take-off (PTO damping of each wave energy converter in the frequency domain in each sea state. In a case study, a wave energy farm consisting of four converters based on the concept developed by Uppsala University is studied. In the solution, motion constraints, including constraints on the amplitudes of displacement and velocity, are included. Twelve months of sea states, based on measured wave data at the Lysekil test site on the Swedish west coast, are used in the simulation to evaluate the performance of the wave energy farm using the new method. Results from the new coordinated control method and traditional control method are compared, indicating that the coordinated control of wave energy converters is an effective way to improve the energy production of wave energy farm in harmonic waves.

  5. Temporal Parts and Superluminal Motion | Balashov | Philosophical ...

    African Journals Online (AJOL)

    Hud Hudson has recently suggested a scenario intended to show that, assuming the doctrine of temporal parts and a sufficiently liberal view of composition, there are material objects that move faster than light. I accept Hudson's conditional but contend that his modus ponens is less plausible than the corresponding modus ...

  6. Vainshtein solutions without superluminal modes

    Science.gov (United States)

    Gabadadze, Gregory; Kimura, Rampei; Pirtskhalava, David

    2015-06-01

    The Vainshtein mechanism suppresses the fifth force at astrophysical distances, while enabling it to compete with gravity at cosmological scales. Typically, Vainshtein solutions exhibit superluminal perturbations. However, a restricted class of solutions with special boundary conditions was shown to be devoid of the faster-than-light modes. Here we extend this class by finding solutions in a theory of quasidilaton, amended by derivative terms consistent with its symmetries. Solutions with Minkowski asymptotics are not stable, while the ones that exhibit the Vainshtein mechanism by transitioning to cosmological backgrounds are free of ghosts, tachyons, gradient instability, and superluminality, for all propagating modes present in the theory. These solutions require a special choice of the strength and signs of nonlinear terms, as well as a choice of asymptotic cosmological boundary conditions.

  7. SUPERLUMINAL WAVES IN PULSAR WINDS

    Energy Technology Data Exchange (ETDEWEB)

    Arka, Ioanna [Current address: Institut de Planetologie et d' Astrophysique de Grenoble, UMR 5274, BP 53 F-38041 Grenoble, France. (France); Kirk, John G., E-mail: ioanna.arka@mpi-hd.mpg.de, E-mail: john.kirk@mpi-hd.mpg.de [Max-Planck-Institut fuer Kernphysik, Postfach 10 39 80, 69029 Heidelberg (Germany)

    2012-02-01

    The energy lost by a rotation-powered pulsar is carried by a relativistic flow containing a mixture of electromagnetic fields and particles. In the inner regions, this is thought to be a magnetically dominated, cold, electron-positron wind that is well described by the MHD equations. However, beyond a critical radius r{sub cr}, the same particle, energy, and momentum fluxes can be transported by a strong, transverse electromagnetic wave with superluminal phase speed. We analyze the nonlinear dispersion relation of these waves for linear and circular polarization, and find the dependence of r{sub cr} on the mass-loading, magnetization, and luminosity of the flow, as well as on the net magnetic flux. We show that, for most isolated pulsars, the wind lies well outside r{sub cr} and speculate that superluminal modes play an important role in the dissipation of electromagnetic energy into nonthermal particles at the termination shock.

  8. NEW SUPERLUMINAL QUASAR-1633+382 AND THE BLAZAR-GAMMA-RAY CONNECTION

    NARCIS (Netherlands)

    BARTHEL, PD; CONWAY, JE; MYERS, ST; PEARSON, TJ; READHEAD, ACS

    1995-01-01

    We report detection of superluminal motion in the core of 4C 38.41, associated with the z = 1.814 quasar 1633+382. The dominant nucleus in the similar to 30 kpc triple morphology of the radio source displays a core-jet structure on the milliarcsecond scale, and a jet component is found moving

  9. Cloning and superluminal signaling£

    Indian Academy of Sciences (India)

    is possible, we can then have (usable) superluminal signaling [8]. The basic principle behind no exact cloning is the principle of no-signaling (i.e., no superluminal signaling). Allowing no-signaling, Gisin [7] has reproduced the 1. 2 optimal universal symmetric cloning machine of Buzek and Hillery [2] for qubits. We shall ...

  10. Observation of image pair creation and annihilation from superluminal scattering sources.

    Science.gov (United States)

    Clerici, Matteo; Spalding, Gabriel C; Warburton, Ryan; Lyons, Ashley; Aniculaesei, Constantin; Richards, Joseph M; Leach, Jonathan; Henderson, Robert; Faccio, Daniele

    2016-04-01

    The invariance of the speed of light is one of the foundational pillars of our current understanding of the universe. It implies a series of consequences related to our perception of simultaneity and, ultimately, of time itself. Whereas these consequences are experimentally well studied in the case of subluminal motion, the kinematics of superluminal motion lack direct evidence or even a clear experimental approach. We investigate kinematic effects associated with the superluminal motion of a light source. By using high-temporal-resolution imaging techniques, we directly demonstrate that if the source approaches an observer at superluminal speeds, the temporal ordering of events is inverted and its image appears to propagate backward. Moreover, for a source changing its speed and crossing the interface between subluminal and superluminal propagation regions, we observe image pair annihilation and creation, depending on the crossing direction. These results are very general and show that, regardless of the emitter speed, it is not possible to unambiguously determine the kinematics of an event from imaging and time-resolved measurements alone. This has implications not only for light, but also, for example, for sound and other wave phenomena.

  11. Galactic Superluminal Sources

    OpenAIRE

    Harmon, B. A.

    1998-01-01

    A new class of X-ray sources was clearly established with the discovery of highly relativistic radio jets from the galactic sources GRS 1915+105 and GRO J1655-40. Both of these objects have given us a broader view of black holes and the formation of jets, yet they also show the complexity of the accretion environment near relativistic objects. The fast apparent motion of the jets, their luminosity and variability, their high energy spectrum, and approximate scaling to the behavior of active g...

  12. Nature of "superluminal" barrier tunneling.

    Science.gov (United States)

    Winful, Herbert G

    2003-01-17

    We show that the distortionless tunneling of electromagnetic pulses through a barrier is a quasistatic process in which the slowly varying envelope of the incident pulse modulates the amplitude of a standing wave. For pulses longer than the barrier width, the barrier acts as a lumped element with respect to the pulse envelope. The envelopes of the transmitted and reflected fields can adiabatically follow the incident pulse with only a small delay that originates from energy storage. The theory presented here provides a physical explanation of the tunneling process and resolves the mystery of apparent superluminality.

  13. Relativistic solitons and superluminal signals

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Enhanced effects of subluminal and superluminal propagation

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Feng; Guo Hong; Li Luming; Liu Cheng; Chen Xuzong

    2004-06-21

    We have experimentally investigated the enhanced effects of subluminal and superluminal propagation, based on electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA), respectively. By adding only an incoherently pumping laser to each case, the slower subluminal group velocity, and the faster superluminal pulse propagation are, respectively, observed. By only changing the intensity of the incoherent pumping beam, we are able to control, respectively, the subluminal group velocity continuously from v{sub g}=c/20000 to v{sub g}=c/8300, and superluminal group velocity from v{sub g}=-c/1667 to v{sub g}=-c/3030. Qualitative explanations for the two cases are given.

  15. Ultrasound fusion image error correction using subject-specific liver motion model and automatic image registration.

    Science.gov (United States)

    Yang, Minglei; Ding, Hui; Zhu, Lei; Wang, Guangzhi

    2016-12-01

    Ultrasound fusion imaging is an emerging tool and benefits a variety of clinical applications, such as image-guided diagnosis and treatment of hepatocellular carcinoma and unresectable liver metastases. However, respiratory liver motion-induced misalignment of multimodal images (i.e., fusion error) compromises the effectiveness and practicability of this method. The purpose of this paper is to develop a subject-specific liver motion model and automatic registration-based method to correct the fusion error. An online-built subject-specific motion model and automatic image registration method for 2D ultrasound-3D magnetic resonance (MR) images were combined to compensate for the respiratory liver motion. The key steps included: 1) Build a subject-specific liver motion model for current subject online and perform the initial registration of pre-acquired 3D MR and intra-operative ultrasound images; 2) During fusion imaging, compensate for liver motion first using the motion model, and then using an automatic registration method to further correct the respiratory fusion error. Evaluation experiments were conducted on liver phantom and five subjects. In the phantom study, the fusion error (superior-inferior axis) was reduced from 13.90±2.38mm to 4.26±0.78mm by using the motion model only. The fusion error further decreased to 0.63±0.53mm by using the registration method. The registration method also decreased the rotation error from 7.06±0.21° to 1.18±0.66°. In the clinical study, the fusion error was reduced from 12.90±9.58mm to 6.12±2.90mm by using the motion model alone. Moreover, the fusion error decreased to 1.96±0.33mm by using the registration method. The proposed method can effectively correct the respiration-induced fusion error to improve the fusion image quality. This method can also reduce the error correction dependency on the initial registration of ultrasound and MR images. Overall, the proposed method can improve the clinical practicability of

  16. Galactic Superluminal Sources

    Science.gov (United States)

    Harmon, B. Alan

    1998-01-01

    A new class of X-ray sources was clearly established with the discovery of highly relativistic radio jets from the two galactic sources GRS 1915+105 and GRO Jl655-40. Both of these objects have given us a broader view of black holes and the formation of jets, yet they also show the complexity of the accretion environment near relativistic objects. The fast apparent motion of the jets, their luminosity and variability, their high energy spectrum, and approximately scaling to the behavior of active galactic nuclei, certainly warrant the description "microquasar". A review of the observational data on these sources is presented, and where we stand on a physical picture of GRS 1915+105 and GRO J165540 as taken from multi-wavelength studies is also discussed. Other galactic sources which share some of the properties of the microquasars, and what to look for as a high energy "signature" in future observations is also discussed.

  17. PARTICLE ACCELERATION IN SUPERLUMINAL STRONG WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Teraki, Yuto; Ito, Hirotaka; Nagataki, Shigehiro, E-mail: yuto.teraki@riken.jp [Astrophysical Big Bang Laboratory, RIKEN, Saitama 351-0198 (Japan)

    2015-06-01

    We calculate the electron acceleration in random superluminal strong waves (SLSWs) and radiation from them using numerical methods in the context of the termination shocks of pulsar wind nebulae. We pursue the orbit of electrons by solving the equation of motion in the analytically expressed electromagnetic turbulences. These consist of a primary SLS and isotropically distributed secondary electromagnetic waves. Under the dominance of the secondary waves, all electrons gain nearly equal energy. On the other hand, when the primary wave is dominant, selective acceleration occurs. The phase of the primary wave for electrons moving nearly along the wavevector changes very slowly compared with the oscillation of the wave, which is “phase-locked,” and such electrons are continuously accelerated. This acceleration by SLSWs may play a crucial role in pre-shock acceleration. In general, the radiation from the phase-locked population is different from the synchro-Compton radiation. However, when the amplitude of the secondary waves is not extremely weaker than that of the primary wave, the typical frequency can be estimated from synchro-Compton theory using the secondary waves. The primary wave does not contribute to the radiation because the SLSW accelerates electrons almost linearly. This radiation can be observed as a radio knot at the upstream of the termination shocks of the pulsar wind nebulae without counterparts in higher frequency ranges.

  18. Particle Acceleration in Superluminal Strong Waves

    Science.gov (United States)

    Teraki, Yuto; Ito, Hirotaka; Nagataki, Shigehiro

    2015-06-01

    We calculate the electron acceleration in random superluminal strong waves (SLSWs) and radiation from them using numerical methods in the context of the termination shocks of pulsar wind nebulae. We pursue the orbit of electrons by solving the equation of motion in the analytically expressed electromagnetic turbulences. These consist of a primary SLS and isotropically distributed secondary electromagnetic waves. Under the dominance of the secondary waves, all electrons gain nearly equal energy. On the other hand, when the primary wave is dominant, selective acceleration occurs. The phase of the primary wave for electrons moving nearly along the wavevector changes very slowly compared with the oscillation of the wave, which is “phase-locked,” and such electrons are continuously accelerated. This acceleration by SLSWs may play a crucial role in pre-shock acceleration. In general, the radiation from the phase-locked population is different from the synchro-Compton radiation. However, when the amplitude of the secondary waves is not extremely weaker than that of the primary wave, the typical frequency can be estimated from synchro-Compton theory using the secondary waves. The primary wave does not contribute to the radiation because the SLSW accelerates electrons almost linearly. This radiation can be observed as a radio knot at the upstream of the termination shocks of the pulsar wind nebulae without counterparts in higher frequency ranges.

  19. Motion or activity: their role in intra- and inter-subject variation in fMRI

    DEFF Research Database (Denmark)

    Lund, Torben E; Nørgaard, Minna D; Rostrup, Egill

    2005-01-01

    MRI to pre-surgical planning because of a higher requirement for intra-subject precision. The purpose of this study was to investigate the impact of residual movement artefacts on intra-subject and inter-subject variability in the observed fMRI activation. Ten subjects were examined using three different...... word-generation tasks. Two of the subjects were examined 10 times on 10 different days using the same paradigms. We systematically investigated one approach of correcting for residual movement effects: the inclusion of regressors describing movement-related effects in the design matrix of a General...... Linear Model (GLM). The data were analysed with and without modeling the residual movement artefacts and the impact on inter-session variance was assessed using F-contrasts. Inclusion of motion parameters in the analysis significantly reduced both the intra-subject as well as the inter-subject-variance....

  20. Pair creation constrains superluminal neutrino propagation.

    Science.gov (United States)

    Cohen, Andrew G; Glashow, Sheldon L

    2011-10-28

    The OPERA collaboration claims that muon neutrinos with a mean energy of 17.5 GeV travel 730 km from CERN to the Gran Sasso at a speed exceeding that of light by about 7.5 km/s or 25 ppm. However, we show that superluminal neutrinos may lose energy rapidly via the bremsstrahlung of electron-positron pairs (ν → ν + e- + e+). For the claimed superluminal velocity and at the stated mean energy, we find that most of the neutrinos would have suffered several pair emissions en route, causing the beam to be depleted of higher energy neutrinos. This presents a significant challenge to the superluminal interpretation of the OPERA data. Furthermore, we appeal to Super-Kamiokande and IceCube data to establish strong new limits on the superluminal propagation of high-energy neutrinos.

  1. Observasi Eksperimental Fenomena Superluminal di Bidang Elektro

    NARCIS (Netherlands)

    Uranus, H.P.; Zhuang, L.; Budiman, Dede A.; Roeloffzen, C.G.H.; Hoekstra, Hugo

    2012-01-01

    Superluminal atau faster-than-light (FTL) adalah fenomena propagasi yang lebih cepat dari laju cahaya di vakum (c). Fenomena ini sering menimbulkan kontroversi karena dianggap tidak konsisten dengan teori relativitas khusus. Makalah ini melaporkan dua observasi eksperimental dari fenomena

  2. Failure of a proposed superluminal scheme

    Science.gov (United States)

    Furuya, K.; Milonni, P. W.; Steinberg, A. M.; Wolinsky, M.

    1999-02-01

    We consider a “superluminal quantum Morse telegraph”, recently proposed by Garuccio, involving a polarization-correlated photon pair and a Michelson interferometer in which one of the mirrors is replaced by a phase-conjugating mirror (PCM). Superluminal information transfer in this scheme is precluded by the impossibility of distinguishing between unpolarized photons prepared by mixing linear polarization states or by mixing circular polarization states.

  3. Motion or activity: their role in intra- and inter-subject variation in fMRI

    DEFF Research Database (Denmark)

    Lund, Torben E; Nørgaard, Minna D; Rostrup, Egill

    2005-01-01

    Linear Model (GLM). The data were analysed with and without modeling the residual movement artefacts and the impact on inter-session variance was assessed using F-contrasts. Inclusion of motion parameters in the analysis significantly reduced both the intra-subject as well as the inter-subject-variance......Functional MRI (fMRI) carries the potential for non-invasive measurements of brain activity. Typically, what are referred to as activation images are actually thresholded statistical parametric maps. These maps possess large inter-session variability. This is especially problematic when applying f......MRI to pre-surgical planning because of a higher requirement for intra-subject precision. The purpose of this study was to investigate the impact of residual movement artefacts on intra-subject and inter-subject variability in the observed fMRI activation. Ten subjects were examined using three different...

  4. A biomechanical analysis of trunk and pelvis motion during gait in subjects with knee osteoarthritis compared to control subjects.

    Science.gov (United States)

    Linley, Heather S; Sled, Elizabeth A; Culham, Elsie G; Deluzio, Kevin J

    2010-12-01

    Trunk lean over the stance limb during gait has been linked to a reduction in the knee adduction moment, which is associated with joint loading. We examined differences in knee adduction moments and frontal plane trunk lean during gait between subjects with knee osteoarthritis and a control group of healthy adults. Gait analysis was performed on 80 subjects (40 osteoarthritis). To define lateral trunk lean two definitions were used. The line connecting the midpoint between two reference points on the pelvis and the midpoint between the acromion processes was projected onto the lab frontal plane and the pelvis frontal plane. Pelvic tilt was also measured in the frontal plane as the angle between the pelvic and lab coordinate systems. Angles were calculated across the stance phase of gait. We analyzed the data, (i) by extracting discrete parameters (mean and peak) waveform values, and (ii) using principal component analysis to extract shape and magnitude differences between the waveforms. Osteoarthritis subjects had a higher knee adduction moment than the control group (α=0.05). Although the discrete parameters for trunk lean did not show differences between groups, principal component analysis did detect characteristic waveform differences between the control and osteoarthritis groups. A thorough biomechanical analysis revealed small differences in the pattern of motion of the pelvis and the trunk between subjects with knee osteoarthritis and control subjects; however these differences were only detectable using principal component analysis. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Prospective motion correction with volumetric navigators (vNavs) reduces the bias and variance in brain morphometry induced by subject motion

    Science.gov (United States)

    Tisdall, M. Dylan; Reuter, Martin; Qureshi, Abid; Buckner, Randy L.; Fischl, Bruce; van der Kouwe, André J. W.

    2015-01-01

    Recent work has demonstrated that subject motion produces systematic biases in the metrics computed by widely used morphometry software packages, even when the motion is too small to produce noticeable image artefacts. In the common situation where the control population exhibits different behaviours in the scanner when compared to the experimental population, these systematic measurement biases may produce significant confounds for between-group analyses, leading to erroneous conclusions about group differences. While previous work has shown that prospective motion correction can improve perceived image quality, here we demonstrate that, in healthy subjects performing a variety of directed motions, the use of the volumetric navigator (vNav) prospective motion correction system significantly reduces the motion-induced bias and variance in morphometry. PMID:26654788

  6. Long-distance superluminal propagation in optical fibers: recent advances

    Science.gov (United States)

    Zhan, Li; Zhang, Liang; Qin, Minglei; Liu, Jinmei

    2016-03-01

    Recent progresses towards distance-limitless superluminal propagation based on stimulated Brillouin scattering have been presented. By suppressing multiple-longitudinal-mode lasing oscillation, Brillouin-induced superluminal propagation through hundreds-of-meter optical fibers can be successfully achieved.

  7. Seismic Response of Power Transmission Tower-Line System Subjected to Spatially Varying Ground Motions

    Directory of Open Access Journals (Sweden)

    Li Tian

    2010-01-01

    Full Text Available The behavior of power transmission tower-line system subjected to spatially varying base excitations is studied in this paper. The transmission towers are modeled by beam elements while the transmission lines are modeled by cable elements that account for the nonlinear geometry of the cables. The real multistation data from SMART-1 are used to analyze the system response subjected to spatially varying ground motions. The seismic input waves for vertical and horizontal ground motions are also generated based on the Code for Design of Seismic of Electrical Installations. Both the incoherency of seismic waves and wave travel effects are accounted for. The nonlinear time history analytical method is used in the analysis. The effects of boundary conditions, ground motion spatial variations, the incident angle of the seismic wave, coherency loss, and wave travel on the system are investigated. The results show that the uniform ground motion at all supports of system does not provide the most critical case for the response calculations.

  8. Probing Superluminal Neutrinos Via Refraction

    CERN Document Server

    Stebbins, Albert

    2011-01-01

    One phenomenological explanation of superluminal propagation of neutrinos, which may have been observed by OPERA and MINOS, is that neutrinos travel faster inside of matter than in vacuum. If so neutrinos exhibit refraction inside matter and should exhibit other manifestations of refraction, such as deflection and reflection. Such refraction would be easily detectable through the momentum imparted to appropriately shaped refractive material inserted into the neutrino beam. For NuMI this could be as large as ~10g cm/s. If these effect were found, they would provide new ways of manipulating and detecting neutrinos. Reasons why this scenario seems implausible are given, however it is still worthwhile to conduct simple searches for differential refraction of neutrinos.

  9. Spectral-motion aftereffects and the tritone paradox among Canadian subjects.

    Science.gov (United States)

    Dawe, L A; Platt, J R; Welsh, E

    1998-02-01

    The effect of spectral motion on the tritone paradox was investigated by pretesting subjects residing in southwestern Ontario, Canada, on the tritone task, presenting them with a continuous ascending or descending chromatic scale created using Shepard tones, and then retesting them on the tritone task. Results indicated a negative-motion aftereffect that affected the orientation of the pitch class circle. Differential effects of perceived pitch height on the lower portion of the pitch class circle and of adaptation on the upper portion of the pitch class circle were found in the pre- and postadaptation data, respectively. The implications of this dissociation are discussed. In addition, since our subjects lived relatively close to the U.S. border, the experimental pretests allowed us to examine the hypothesis that a canonical American pitch template similar to that found among "Californian" subjects (Deutsch, 1991) is propagated by linguistic influences of media such as television and radio (Ragozzine & Deutsch, 1994). A survey of our subjects indicated that overall, the majority of time engaged in listening to the radio and watching television or movies was spent with American sources. Despite this, and despite the fact that subjects had widely varying language and cultural backgrounds, a tight distribution of peak-pitch classes was found that is indicative of a "British" pitch template (Deutsch, 1991) for every subject tested.

  10. Interpreting OPERA results on superluminal neutrino

    CERN Document Server

    Giudice, Gian F; Strumia, Alessandro

    2012-01-01

    OPERA has claimed the discovery of superluminal propagation of neutrinos. We analyze the consistency of this claim with previous tests of special relativity. We find that reconciling the OPERA measurement with information from SN1987a and from neutrino oscillations requires stringent conditions. The superluminal limit velocity of neutrinos must be nearly flavor independent, must decrease steeply in the low-energy domain, and its energy dependence must depart from a simple power law. We construct illustrative models that satisfy these conditions, by introducing Lorentz violation in a sector with light sterile neutrinos. We point out that, quite generically, electroweak quantum corrections transfer the information of superluminal neutrino properties into Lorentz violations in the electron and muon sector, in apparent conflict with experimental data.

  11. Interpreting OPERA results on superluminal neutrino

    Energy Technology Data Exchange (ETDEWEB)

    Giudice, Gian F. [CERN, Theory Division, CH-1211 Geneva 23 (Switzerland); Sibiryakov, Sergey [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, 117312 Moscow (Russian Federation); Strumia, Alessandro, E-mail: Alessandro.Strumia@mail.df.unipi.it [Dipartimento di Fisica dell' Universita di Pisa and INFN (Italy); National Institute of Chemical Physics and Biophysics, Ravala 10, Tallinn (Estonia)

    2012-08-01

    OPERA has claimed the discovery of superluminal propagation of neutrinos. We analyze the consistency of this claim with previous tests of special relativity. We find that reconciling the OPERA measurement with information from SN1987a and from neutrino oscillations requires stringent conditions. The superluminal limit velocity of neutrinos must be nearly flavor independent, must decrease steeply in the low-energy domain, and its energy dependence must depart from a simple power law. We construct illustrative models that satisfy these conditions, by introducing Lorentz violation in a sector with light sterile neutrinos. We point out that, quite generically, electroweak quantum corrections transfer the information of superluminal neutrino properties into Lorentz violations in the electron and muon sector, in apparent conflict with experimental data.

  12. Superluminal ring laser for hypersensitive sensing.

    Science.gov (United States)

    Yum, H N; Salit, M; Yablon, J; Salit, K; Wang, Y; Shahriar, M S

    2010-08-16

    The group velocity of light becomes superluminal in a medium with a tuned negative dispersion, using two gain peaks, for example. Inside a laser, however, the gain is constant, equaling the loss. We show here that the effective dispersion experienced by the lasing frequency is still sensitive to the spectral profile of the unsaturated gain. In particular, a dip in the gain profile leads to a superluminal group velocity for the lasing mode. The displacement sensitivity of the lasing frequency is enhanced by nearly five orders of magnitude, leading to a versatile sensor of hyper sensitivity.

  13. Nonlinear dynamic modeling of a simple flexible rotor system subjected to time-variable base motions

    Science.gov (United States)

    Chen, Liqiang; Wang, Jianjun; Han, Qinkai; Chu, Fulei

    2017-09-01

    Rotor systems carried in transportation system or under seismic excitations are considered to have a moving base. To study the dynamic behavior of flexible rotor systems subjected to time-variable base motions, a general model is developed based on finite element method and Lagrange's equation. Two groups of Euler angles are defined to describe the rotation of the rotor with respect to the base and that of the base with respect to the ground. It is found that the base rotations would cause nonlinearities in the model. To verify the proposed model, a novel test rig which could simulate the base angular-movement is designed. Dynamic experiments on a flexible rotor-bearing system with base angular motions are carried out. Based upon these, numerical simulations are conducted to further study the dynamic response of the flexible rotor under harmonic angular base motions. The effects of base angular amplitude, rotating speed and base frequency on response behaviors are discussed by means of FFT, waterfall, frequency response curve and orbits of the rotor. The FFT and waterfall plots of the disk horizontal and vertical vibrations are marked with multiplications of the base frequency and sum and difference tones of the rotating frequency and the base frequency. Their amplitudes will increase remarkably when they meet the whirling frequencies of the rotor system.

  14. Superluminal Velocities in the Synchronized Space-Time

    Directory of Open Access Journals (Sweden)

    Medvedev S. Yu.

    2014-07-01

    Full Text Available Within the framework of the non-gravitational generalization of the special relativity, a problem of possible superluminal motion of particles and signals is considered. It has been proven that for the particles with non-zero mass the existence of anisotropic light barrier with the shape dependent on the reference frame velocity results from the Tangherlini transformations. The maximal possible excess of neutrino velocity over the absolute velocity of light related to the Earth (using th e clock with instantaneous synchronization has been estimated. The illusoriness of t he acausality problem has been illustrated and conclusion is made on the lack of the upper limit of velocities of signals of informational nature.

  15. The nasal provocation test combined with spirometry establishes paradoxical vocal fold motion in allergic subjects.

    Science.gov (United States)

    Olivier, Celso Eduardo; Argentão, Daiana Guedes Pinto; Lima, Regiane Patussi dos Santos; da Silva, Mariana Dias; dos Santos, Raquel Acácia Pereira Gonçalves

    2013-01-01

    Vocal cord dysfunction (also called paradoxical vocal cord motion) or paradoxical vocal fold motion (PVFM) is an event elicited by specific and nonspecific triggers in which its diagnosis is limited by the restricted number of available functional tests. This study was designed to appreciate the contribution of the spirometric changes elicited by the allergen-specific nasal provocation test (NPT) performed with Dermatophagoides pteronyssinus for the diagnosis of PVFM in subjects with known sensitization to this allergen. In total, 63 subjects with allergic rhinitis who had previously been shown to be sensitized to D. pteronyssinus and who had experienced one or more episodes of inspiratory shortness of breath underwent two spirometric tests, one before (pre-NPT) and another 15 minutes after the allergen-specific NPT (post-NPT). The forced inspiratory vital capacity (FIVC), forced inspiratory volume in 2 seconds (FIV2), and the ratio between the FIV in 1 second and FIVC (FIV1/FIVC) were measured by spirometry. The morphology of the post-NPT inspiratory loop was compared with the pre-NPT inspiratory loop. We found that 18 subjects (28.5%) showed alterations suggestive of PVFM on post-NPT spirometry (e.g., truncation and/or flattening of the inspiratory loop). The mean differences between the pre-NPT and post-NPT values for the whole group were significant using a two-tailed paired t-test for the FIVC (4.1; 95% confidence interval [CI95%], 1.4-6.8), FIV1/FIVC ratio (2.7; CI95%, 0.05-5.3), and FIV2 (7.2; CI95%, 3.4-11). Allergen-specific NPT combined with spirometry is useful to show allergen-specific laryngeal hyperresponsiveness in allergic subjects with PVFM. Brazilian clinical trial registry platform (Plataforma Brasil, CAAE 07971212.0.0000.5480).

  16. Grs 1915+105: a superluminal source in the Galaxy.

    Science.gov (United States)

    Rodríguez, L F; Mirabel, I F

    1995-01-01

    We present the results of additional observations of the high energy source GRS 1915+105, which produces ejecta with apparent superluminal motions. The observations reported here were carried out with the Very Large Array at 3.5 cm and 20 cm. The 3.5-cm observations made during 1994 May allowed us to continue following the proper motions of the bright 1994 March 19 ejecta, as well as those of a subsequent, fainter ejection. The proper motions of the 1994 March 19 ejecta continued to be ballistic (i.e., constant) over the period of about 75 days where they remained detectable. From the observations in 1994 March-May we have identified three ejections of pairs of plasma clouds moving ballistically in approximately the same direction on the sky with similar proper motions. The 20-cm observations made during 1994 November and December were used to search, yet unsuccessfully, for extended jets or lobes associated with GRS 1915+105. PMID:11607605

  17. Pair Production Constraints on Superluminal Neutrinos Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; Gardner, Susan; /Kentucky U.

    2012-02-16

    We revisit the pair creation constraint on superluminal neutrinos considered by Cohen and Glashow in order to clarify which types of superluminal models are constrained. We show that a model in which the superluminal neutrino is effectively light-like can evade the Cohen-Glashow constraint. In summary, any model for which the CG pair production process operates is excluded because such timelike neutrinos would not be detected by OPERA or other experiments. However, a superluminal neutrino which is effectively lightlike with fixed p{sup 2} can evade the Cohen-Glashow constraint because of energy-momentum conservation. The coincidence involved in explaining the SN1987A constraint certainly makes such a picture improbable - but it is still intrinsically possible. The lightlike model is appealing in that it does not violate Lorentz symmetry in particle interactions, although one would expect Hughes-Drever tests to turn up a violation eventually. Other evasions of the CG constraints are also possible; perhaps, e.g., the neutrino takes a 'short cut' through extra dimensions or suffers anomalous acceleration in matter. Irrespective of the OPERA result, Lorentz-violating interactions remain possible, and ongoing experimental investigation of such possibilities should continue.

  18. Superluminal localized structures of electromagnetic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Rozanov, Nikolai N [Research Institute for Laser Physics, St. Petersburg (Russian Federation)

    2005-02-28

    This paper analyzes localized invariable-form structures of electromagnetic radiation in vacuum and soliton-like light structures traveling superluminally in a nonlinear medium. Both types of structures are concluded to be unstable to small perturbations. (annus mirabilis. methodological notes)

  19. Apparent superluminal behavior in wave propagation

    NARCIS (Netherlands)

    Jackson, AD; Lande, A; Lautrup, B

    2001-01-01

    The apparent superluminal propagation of electromagnetic signals seen in recent experiments is shown to be the result of simple and robust properties of relativistic field equations. Although the wave front of a signal passing through a classically forbidden region can never move faster than light,

  20. Tunable superluminal propagation on a silicon microchip.

    Science.gov (United States)

    Manipatruni, Sasikanth; Dong, Po; Xu, Qianfan; Lipson, Michal

    2008-12-15

    We demonstrate tunable superluminal propagation in a silicon microphotonic device in a solid-state room-temperature device of tens of micrometers in dimension allowing easy integration with high-bandwidth room-temperature systems. We achieve tunable negative delays up to 85 ps and effective group indices tunable between -1158 and -312.

  1. On the Possibility of Superluminal Neutrino Propagation

    CERN Document Server

    Alexandre, Jean; Mavromatos, Nick E.

    2012-01-01

    We analyze the possibility of superluminal neutrino propagation delta v = (v - c)/c > 0 as indicated by OPERA data, in view of previous phenomenological constraints from supernova SN1987a and gravitational Cerenkov radiation. We argue that the SN1987a data rule out delta v ~ (E_\

  2. Causal ubiquity in quantum physics. A superluminal and local-causal physical ontology

    Energy Technology Data Exchange (ETDEWEB)

    Neelamkavil, Raphael

    2014-07-01

    A fixed highest criterial velocity (of light) in STR (special theory of relativity) is a convention for a layer of physical inquiry. QM (Quantum Mechanics) avoids action-at-a-distance using this concept, but accepts non-causality and action-at-a-distance in EPR (Einstein-Podolsky-Rosen-Paradox) entanglement experiments. Even in such allegedly [non-causal] processes, something exists processually in extension-motion, between the causal and the [non-causal]. If STR theoretically allows real-valued superluminal communication between EPR entangled particles, quantum processes become fully causal. That is, the QM world is sub-luminally, luminally and superluminally local-causal throughout, and the Law of Causality is ubiquitous in the micro-world. Thus, ''probabilistic causality'' is a merely epistemic term.

  3. VLBI monitoring of the superluminal quasar 3C 273, 1977-1982

    Science.gov (United States)

    Unwin, S. C.; Cohen, M. H.; Biretta, J. A.; Pearson, T. J.; Seielstad, G. A.; Walker, R. C.; Simon, R. S.; Linfield, R. P.

    1985-01-01

    The compact ratio structure of the quasar 3C 273 has been monitored with a VLBI array at 5.0 and 10.7 GHz at six-month intervals during 1977-1982. THe VLBI monitoring observations, data reduction, calibration, and mapping techniques are described, and hybrid maps from the monitoring program are presented along with a brief discussion of the main features. Results on the source kinematics (superluminal motion of the knots and their time evolution) are given, and synchro-Compton models of the knots are presented and limits to their Doppler factors (delta) derived from X-ray measurements. The constraints on jet geometry provided by the combined measurements of delta and v/c are considered. For the core, the inhomogeneous jet model of Koenigl (1981) is compared with the available data. The relation between 3C 273 and the similar superluminal source 3C 345 is discussed.

  4. Normal sensory and range of motion (ROM) responses during Thoracic Slump Test (ST) in asymptomatic subjects.

    Science.gov (United States)

    Joshi, Ketaki C; Eapen, Charu; Kumar, Senthil P

    2013-02-01

    The purpose of the study was to determine the normal sensory and range of motion (ROM) responses during the movement components of Thoracic Slump Test (Thoracic ST) in asymptomatic subjects. Sixty asymptomatic subjects were included in the study. Thoracic ST was performed in two sequences, proximal initiation, which was proximal to distal and distal initiation, which was distal to proximal. Subjects were randomized into four groups depending on the order of sequences and sides. Outcome measures of sensory responses (intensity, type, and location) and ROM responses were recorded after each sequence. Friedman's test was done to compare between sensory responses of the subjects. Between-component comparison for prevalence of sensory responses within each sequence was done using Kruskal-Wallis test and Wilcoxonsigned ranks test was used for between-component comparisons of intensity of symptoms within each sequence of testing. Independent t test was used to assess the ROM responses. Results show the prevalence of sensory responses, its nature, area and intensity. These sensory and ROM responses may be considered as normal response of Thoracic ST. The intensity of the symptoms of proximal initiation sequence (1.09±1.35 cm) was significant (PROM was significant (P<0.05) for distal initiation (7.55±4.51 degrees) when compared to proximal initiation (4.96±3.76 degrees). These normal responses may be used as a reference when using the Thoracic ST as an assessment technique.

  5. Head repositioning accuracy in patients with neck pain and asymptomatic subjects: concurrent validity, influence of motion speed, motion direction and target distance.

    Science.gov (United States)

    Dugailly, Pierre-Michel; De Santis, Roberta; Tits, Mathieu; Sobczak, Stéphane; Vigne, Anna; Feipel, Véronique

    2015-12-01

    Cervicocephalic kinesthetic deficiencies have been demonstrated in patients with chronic neck pain (NP). On the other hand, authors emphasized the use of different motion speeds for assessing functional impairment of the cervical spine. The objectives of this study were (1) to investigate the head repositioning accuracy in NP patients and control subjects and (2) to assess the influence of target distance, motion speed, motion direction and pain. Seventy-one subjects (36 healthy subjects and 35 NP patients; age 30-55 years) performed the head repositioning test (HRT) at two different speeds for horizontal and vertical movements and at two different distances. For each condition, six consecutive trials were sampled. The study showed the validity and reproducibility of the HRT, confirming a dysfunctional threshold of 4.5°. Normative values of head repositioning error up to 3.6° and 7.1° were identified for healthy and NP subjects, respectively. A distance of 180 cm from the target and a natural motion speed increased HRT accuracy. Repositioning after extension movement showed a significantly larger error in both groups. Intensity, duration of pain as well as pain level did not significantly alter head repositioning error. The assessment of proprioceptive performance in healthy and NP subjects allowed the validation of the HRT. The HRT is a simple, not expensive and fast test, easily implementable in daily practice to assess and monitor treatment and evolution of proprioceptive cervical deficits.

  6. Motion

    CERN Document Server

    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

  7. Motion Correction of Single-Voxel Spectroscopy by Independent Component Analysis Applied to Spectra From Nonanesthetized Pediatric Subjects

    DEFF Research Database (Denmark)

    de Nijs, Robin; Miranda, Maria J.; Hansen, Lars Kai

    2009-01-01

    For single-voxel spectroscopy, the acquisition of the spectrum is typically repeated n times and then combined with a factor in order to improve the signal-to-noise ratio. In practice, the acquisitions are not only affected by random noise but also by physiologic motion and subject movements. Since...... the influence of physiologic motion such as cardiac and respiratory motion on the data is limited, it can be compensated for without data loss. Individual acquisitions hampered by subject movements, on the other hand, need to be rejected if no correction or compensation is possible. If the individual...... acquisitions are stored, it is possible to identify and reject the motion-disturbed acquisitions before averaging. Several automatic algorithms were investigated using a dataset of spectra from nonanesthetized infants with a gestational age of 40 weeks. Median filtering removed most subject movement artifacts...

  8. Measurements of potential differences in human subjects induced by motion in a superconducting magnetic field.

    Science.gov (United States)

    Frinak, S; Knight, R A; Liboff, A R

    1992-01-01

    We have attempted to measure the electromotive forces (emfs) induced in human beings moving at a constant speed in a highly dense magnetic field. Experiments were initially conducted on a set of models, and then directly on human subjects. The models consisted of single circular loops of Tygon tubing (I.D., 0.635 cm; O.D., 0.9525 cm) filled with normal saline solution, with circumferences of 20, 40, 60, 80, and 100 cm. The models were connected to an amplifier via silver/silver-chloride electrodes. Each saline loop was mounted on a movable platform, with the plane of the loop perpendicular to the platform's axis; the platform was enabled to move at known constant speeds into and out of the bore of a 1.89-T magnet. The human subjects were then substituted for the saline loops, with the long axis parallel to the direction of motion, and with standard EKG electrodes placed at 180 degrees successively on the ankle, calf, lower thigh, upper thigh, chest, and head. In all cases, for human subjects and models, the peak induced voltage was directly proportional to the speed of movement and the square of the circumference of the bounded cross-sectional areas. Thus, for the saline loops, the correlation coefficient between induced voltage and circumference was .998, and for human subjects, .947. Under the loose assumption that for equal circumferences the bounded areas in human subjects were equal to those in the circular loops, the induced emfs in human subjects were consistently about 13% greater than those in the loops. At a mean speed of 1.18 m/s, the chest had a peak induced voltage of 260 mV, while the voltage at the ankle had a peak of 19.8 mV. The experimental data were used to estimate the corresponding induced-current density at the pericardium, 17 mA/m2. We conclude for a human subject moving at constant speed along the body's long axis into a magnetic field that Faraday's law is closely followed for various cross-sections of the body. Further, in those cases in

  9. Muscle Synergies Facilitate Computational Prediction of Subject-Specific Walking Motions

    Science.gov (United States)

    Meyer, Andrew J.; Eskinazi, Ilan; Jackson, Jennifer N.; Rao, Anil V.; Patten, Carolynn; Fregly, Benjamin J.

    2016-01-01

    Researchers have explored a variety of neurorehabilitation approaches to restore normal walking function following a stroke. However, there is currently no objective means for prescribing and implementing treatments that are likely to maximize recovery of walking function for any particular patient. As a first step toward optimizing neurorehabilitation effectiveness, this study develops and evaluates a patient-specific synergy-controlled neuromusculoskeletal simulation framework that can predict walking motions for an individual post-stroke. The main question we addressed was whether driving a subject-specific neuromusculoskeletal model with muscle synergy controls (5 per leg) facilitates generation of accurate walking predictions compared to a model driven by muscle activation controls (35 per leg) or joint torque controls (5 per leg). To explore this question, we developed a subject-specific neuromusculoskeletal model of a single high-functioning hemiparetic subject using instrumented treadmill walking data collected at the subject’s self-selected speed of 0.5 m/s. The model included subject-specific representations of lower-body kinematic structure, foot–ground contact behavior, electromyography-driven muscle force generation, and neural control limitations and remaining capabilities. Using direct collocation optimal control and the subject-specific model, we evaluated the ability of the three control approaches to predict the subject’s walking kinematics and kinetics at two speeds (0.5 and 0.8 m/s) for which experimental data were available from the subject. We also evaluated whether synergy controls could predict a physically realistic gait period at one speed (1.1 m/s) for which no experimental data were available. All three control approaches predicted the subject’s walking kinematics and kinetics (including ground reaction forces) well for the model calibration speed of 0.5 m/s. However, only activation and synergy controls could predict the

  10. Normal sensory and range of motion (ROM) responses during Thoracic Slump Test (ST) in asymptomatic subjects

    Science.gov (United States)

    Joshi, Ketaki C; Eapen, Charu; Kumar, Senthil P

    2013-01-01

    The purpose of the study was to determine the normal sensory and range of motion (ROM) responses during the movement components of Thoracic Slump Test (Thoracic ST) in asymptomatic subjects. Sixty asymptomatic subjects were included in the study. Thoracic ST was performed in two sequences, proximal initiation, which was proximal to distal and distal initiation, which was distal to proximal. Subjects were randomized into four groups depending on the order of sequences and sides. Outcome measures of sensory responses (intensity, type, and location) and ROM responses were recorded after each sequence. Friedman’s test was done to compare between sensory responses of the subjects. Between-component comparison for prevalence of sensory responses within each sequence was done using Kruskal–Wallis test and Wilcoxonsigned ranks test was used for between-component comparisons of intensity of symptoms within each sequence of testing. Independent t test was used to assess the ROM responses. Results show the prevalence of sensory responses, its nature, area and intensity. These sensory and ROM responses may be considered as normal response of Thoracic ST. The intensity of the symptoms of proximal initiation sequence (1.09±1.35 cm) was significant (P<0.05) when compared to distal initiation sequence (0.08±1.26 cm). The change in the ROM was significant (P<0.05) for distal initiation (7.55±4.51 degrees) when compared to proximal initiation (4.96±3.76 degrees). These normal responses may be used as a reference when using the Thoracic ST as an assessment technique. PMID:24421610

  11. Automated quantification of three-dimensional subject motion to monitor image quality in high-resolution peripheral quantitative computed tomography

    Science.gov (United States)

    Pauchard, Yves; Ayres, Fábio J.; Boyd, Steven K.

    2011-10-01

    Subject motion during acquisition of high-resolution peripheral quantitative computed tomography (HR-pQCT) results in image artifacts and interferes with quantification of bone architecture used to study bone-related diseases such as osteoporosis. We propose an automatic method to measure physical subject motion that frequently takes place during acquisition. Three measures derived from projection data are proposed to quantify motion artifacts: in-plane translation (εT) and in-plane rotation (εR) utilizing projection moments and longitudinal translation (εz) based on tracking projection profiles. Validation was performed using a phantom containing sections of distal human cadaver radii attached to a mechanical device to precisely control in-plane rotation and longitudinal translation that was intentionally performed during HR-pQCT data acquisition. Motion measured by the new automated technique was compared to the known applied motion, and related to percent errors in morphological parameters quantifying bone properties. It was determined that of the three proposed measures, εT best captured a quantified representation of image quality. εT linearly relates to true physical in-plane translational motion (r2 = 0.95, pmovements and combines well with εT to fully characterize physical motion artifacts. The magnitude of εT corresponds to morphological parameter error and is an excellent basis to select high-quality images. Morphological parameter errors from these experiments confirmed our earlier computer simulations which showed that increased subject motion resulted in artificially higher trabecular number, and artificially lower bone mineral density and cortical thickness. The magnitude and, notably, the uncertainty of the morphological errors increased with increased physical motion, and this impedes a direct linear compensation of parameter errors. The automated method presented provides a basis for consistent and objective quality assurance for HR

  12. Superluminal propagation: Light cone and Minkowski spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Mugnai, D. [' Nello Carrara' Institute of Applied Physics, CNR Florence Research Area, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy)]. E-mail: d.mugnai@ifac.cnr.it

    2007-05-14

    Superluminal behavior has been extensively studied in recent years, especially with regard to the topic of superluminality in the propagation of a signal. Particular interest has been devoted to Bessel-X waves propagation, since some experimental results showed that these waves have both phase and group velocities greater that light velocity c. However, because of the lack of an exact definition of signal velocity, no definite answer about the signal propagation (or velocity of information) has been found. The present Letter is a short note that deals in a general way with this vexed question. By analyzing the field of existence of the Bessel X-pulse in pseudo-Euclidean spacetime, it is possible to give a general description of the propagation, and to overcome the specific question related to a definition of signal velocity.

  13. Spectroscopy of superluminous supernova host galaxies

    DEFF Research Database (Denmark)

    Leloudas, G.; Kruehler, T.; Schulze, S

    2015-01-01

    Superluminous supernovae (SLSNe) are very bright explosions that were only discovered recently and that show a preference for occurring in faint dwarf galaxies. Understanding why stellar evolution yields different types of stellar explosions in these environments is fundamental in order to both...... uncover the elusive progenitors of SLSNe and to study star formation in dwarf galaxies. In this paper, we present the first results of our project to study SUperluminous Supernova Host galaxIES, focusing on the sample for which we have obtained spectroscopy. We show that SLSNe-I and SLSNe-R (hydrogen......-poor) often (~50% in our sample) occur in a class of galaxies that is known as Extreme Emission Line Galaxies (EELGs). The probability of this happening by chance is negligible and we therefore conclude that the extreme environmental conditions and the SLSN phenomenon are related. In contrast, SLSNe...

  14. On the possibility of superluminal neutrino propagation

    Energy Technology Data Exchange (ETDEWEB)

    Alexandre, Jean, E-mail: jean.alexandre@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Ellis, John; Mavromatos, Nick E. [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Theory Division, Department of Physics, CERN, CH 1211, Geneva 23 (Switzerland)

    2012-01-05

    We analyze the possibility of superluminal neutrino propagation {delta}v{identical_to}(v-c)/c>0 as indicated by OPERA data, in view of previous phenomenological constraints from supernova SN1987a and gravitational Cerenkov radiation. We argue that the SN1987a data rule out {delta}v{approx}(E{sub {nu}}/M{sub N}){sup N} for N Less-Than-Or-Slanted-Equal-To 2 and exclude, in particular, a Lorentz-invariant interpretation in terms of a 'conventional' tachyonic neutrino. We present two toy Lorentz-violating theoretical models, one a Lifshitz-type fermion model with superluminality depending quadratically on energy, and the other a Lorentz-violating modification of a massless Abelian gauge theory with axial-vector couplings to fermions. In the presence of an appropriate background field, fermions may propagate superluminally or subluminally, depending inversely on energy, and on direction. Reconciling OPERA with SN1987a would require this background field to depend on location.

  15. Superluminal periodic orbits in the Lorenz system

    Science.gov (United States)

    Algaba, A.; Merino, M.; Rodríguez-Luis, A. J.

    2016-10-01

    In this work we present, for the Lorenz system, analytical and numerical results on the existence of periodic orbits with unbounded amplitude and whose period tends to zero. Since a particle moving on these periodic orbits would be faster-than-light, we call them superluminal periodic orbits. To achieve this goal, we first find analytical expressions for the period in three different situations, where Hopf and Takens-Bogdanov bifurcations of infinite codimension occur. Thus, taking limit in the corresponding expressions allows to demonstrate the existence of superluminal periodic orbits for finite values of the parameter ρ (in a region where the other two parameters σ and b are negative). Moreover, we numerically show, in other two different cases of physical interest, that these orbits also exist when the parameter ρ tends to infinity. Finally, the presence of superluminal periodic orbits in the widely studied Chen and Lü systems follows directly from our results, taking into account that they are, generically, particular cases of the Lorenz system, as can be proved with a linear scaling in time and state variables.

  16. Envelope statistics of self-motion signals experienced by human subjects during everyday activities: Implications for vestibular processing.

    Science.gov (United States)

    Carriot, Jérome; Jamali, Mohsen; Cullen, Kathleen E; Chacron, Maurice J

    2017-01-01

    There is accumulating evidence that the brain's neural coding strategies are constrained by natural stimulus statistics. Here we investigated the statistics of the time varying envelope (i.e. a second-order stimulus attribute that is related to variance) of rotational and translational self-motion signals experienced by human subjects during everyday activities. We found that envelopes can reach large values across all six motion dimensions (~450 deg/s for rotations and ~4 G for translations). Unlike results obtained in other sensory modalities, the spectral power of envelope signals decreased slowly for low (2 Hz) temporal frequencies and thus was not well-fit by a power law. We next compared the spectral properties of envelope signals resulting from active and passive self-motion, as well as those resulting from signals obtained when the subject is absent (i.e. external stimuli). Our data suggest that different mechanisms underlie deviation from scale invariance in rotational and translational self-motion envelopes. Specifically, active self-motion and filtering by the human body cause deviation from scale invariance primarily for translational and rotational envelope signals, respectively. Finally, we used well-established models in order to predict the responses of peripheral vestibular afferents to natural envelope stimuli. We found that irregular afferents responded more strongly to envelopes than their regular counterparts. Our findings have important consequences for understanding the coding strategies used by the vestibular system to process natural second-order self-motion signals.

  17. Envelope statistics of self-motion signals experienced by human subjects during everyday activities: Implications for vestibular processing

    Science.gov (United States)

    Carriot, Jérome; Jamali, Mohsen; Cullen, Kathleen E.

    2017-01-01

    There is accumulating evidence that the brain’s neural coding strategies are constrained by natural stimulus statistics. Here we investigated the statistics of the time varying envelope (i.e. a second-order stimulus attribute that is related to variance) of rotational and translational self-motion signals experienced by human subjects during everyday activities. We found that envelopes can reach large values across all six motion dimensions (~450 deg/s for rotations and ~4 G for translations). Unlike results obtained in other sensory modalities, the spectral power of envelope signals decreased slowly for low (2 Hz) temporal frequencies and thus was not well-fit by a power law. We next compared the spectral properties of envelope signals resulting from active and passive self-motion, as well as those resulting from signals obtained when the subject is absent (i.e. external stimuli). Our data suggest that different mechanisms underlie deviation from scale invariance in rotational and translational self-motion envelopes. Specifically, active self-motion and filtering by the human body cause deviation from scale invariance primarily for translational and rotational envelope signals, respectively. Finally, we used well-established models in order to predict the responses of peripheral vestibular afferents to natural envelope stimuli. We found that irregular afferents responded more strongly to envelopes than their regular counterparts. Our findings have important consequences for understanding the coding strategies used by the vestibular system to process natural second-order self-motion signals. PMID:28575032

  18. Low-loss directional cloaks without superluminal velocity or magnetic response.

    Science.gov (United States)

    Urzhumov, Yaroslav; Smith, David R

    2012-11-01

    The possibility of making an optically large (many wavelengths in diameter) object appear invisible has been a subject of many recent studies. Exact invisibility scenarios for large (relative to the wavelength) objects involve (meta)materials with superluminal phase velocity [refractive index (RI) less than unity] and/or magnetic response. We introduce a new approximation applicable to certain device geometries in the eikonal limit: piecewise-uniform scaling of the RI. This transformation preserves the ray trajectories but leads to a uniform phase delay. We show how to take advantage of phase delays to achieve a limited (directional and wavelength-dependent) form of invisibility that does not require loss-ridden (meta)materials with superluminal phase velocities.

  19. [Measuring facial paralysis using the three-dimensional dynamic quantitative analysis system of facial motion: correlation with subjective grading systems].

    Science.gov (United States)

    Zhao, Y; Feng, G D; Wu, H Y; Zhuang, Y; Gao, Z Q

    2016-07-07

    The aim of this study was to measure the facial motion of patients with facial paralysis using a three-dimensional dynamic quantitative analysis system of facial motion (3D ASFM) and analyze its correlation with subjective grading systems. We included 30 healthy volunteers and 50 patients with unilateral facial paralysis. After placing landmarks on the faces, the facial motions of the patients were measured using the 3D ASFM. The regional symmetry ratios(SRs) and gross scores of different parameters were calculated. Then a comparison with four subjective grading systems(House-Brackmann, Sunnybrook, Facial Nerve Grading System 2.0, Fisch) was performed. The entire test could be completed within five minutes. The normal range of healthy volunteers were obtained, the gross score of which was 91.9±1.5. The SRs of the maximal moving distance(MMD) were most strongly correlated with regional subjective grading systems, followed by the SRs of the maximal moving velocity (MMV). The SRs of the maximal moving acceleration (MMA) were either poorly correlated or uncorrelated with the subjective grading systems. Moreover, the Spearman coefficients with four subjective grading systems were -0.630(House-Brackmann), -0.728(Facial Nerve Grading System 2.0), 0.697(Sunnybrook), and 0.617(Fisch)respectively(Pfacial paralysis. It not only overcomes the shortcomings of conventional subjective grading systems, but also correlates well with them.

  20. Transient radiation from a ring resonant medium excited by an ultrashort superluminal pulse

    Energy Technology Data Exchange (ETDEWEB)

    Arkhipov, R M [Humboldt University at Berlin (Germany); Arkhipov, M V; Tolmachev, Yu A [Department of Physics, Saint-Petersburg State University (Russian Federation); Babushkin, I V [Institute of Quantum Optics, Leibniz University Hannover, Welfengarten 1 30167, Hannover (Germany)

    2015-06-30

    We report some specific features of transient radiation from a periodic spatially modulated one-dimensional medium with a resonant response upon excitation by an ultrashort pulse. The case of ring geometry (with particle density distributed along the ring according to the harmonic law) is considered. It is shown that the spectrum of scattered radiation contains (under both linear and nonlinear interaction), along with the frequency of intrinsic resonance of the medium, a new frequency, which depends on the pulse velocity and the spatial modulation period. The case of superluminal motion of excitation, when the Cherenkov effect manifests itself, is also analysed. (laser applications and other topics in quantum electronics)

  1. Transient radiation from a ring resonant medium excited by an ultrashort superluminal pulse

    Science.gov (United States)

    Arkhipov, R. M.; Arkhipov, M. V.; Babushkin, I. V.; Tolmachev, Yu A.

    2015-06-01

    We report some specific features of transient radiation from a periodic spatially modulated one-dimensional medium with a resonant response upon excitation by an ultrashort pulse. The case of ring geometry (with particle density distributed along the ring according to the harmonic law) is considered. It is shown that the spectrum of scattered radiation contains (under both linear and nonlinear interaction), along with the frequency of intrinsic resonance of the medium, a new frequency, which depends on the pulse velocity and the spatial modulation period. The case of superluminal motion of excitation, when the Cherenkov effect manifests itself, is also analysed.

  2. Causal ubiquity in quantum physics a superluminal and local-causal physical ontology

    CERN Document Server

    Neelamkavil, Raphael

    2014-01-01

    A fixed highest criterial velocity (of light) in STR (special theory of relativity) is a convention for a layer of physical inquiry. QM (Quantum Mechanics) avoids action-at-a-distance using this concept, but accepts non-causality and action-at-a-distance in EPR (Einstein-Podolsky-Rosen-Paradox) entanglement experiments. Even in such allegedly non-causal processes, something exists processually in extension-motion, between the causal and the non-causal. If STR theoretically allows real-valued superluminal communication between EPR entangled particles, quantum processes become fully causal. That

  3. Interaction of linear and angular vestibulo-ocular reflexes of human subjects in response to transient motion.

    Science.gov (United States)

    Anastasopoulos, D; Gianna, C C; Bronstein, A M; Gresty, M A

    1996-08-01

    The possibility of synergistic interaction between the canal and otolith components of the horizontal vestibulo-ocular reflex (VOR) was evaluated in human subjects by subtracting the response to pure angular rotation (AVOR) from the response to combined angular and translational motion (ALVOR) and comparing this difference with the VOR to isolated linear motion (LVOR). Assessments were made with target fixation at 60 cm and in darkness. Linear stimuli were acceleration steps attaining 0.25 g in less than 80 ms. To elicit responses to combined translational and angular head movements, the subjects were seated on a Barany chair with the head displaced forwards 40 cm from the axis of rotation. The chair was accelerated at approximately 300 deg/s2 to 127 deg/s peak angular velocity, the tangential acceleration of the head being comparable with that of isolated translation. Estimates of the contribution of smooth pursuit to responses in the light were made from comparisons of isolated pursuit of similar target trajectories. In the dark the slow phase eye movements evoked by combined canal-otolith stimuli were higher in magnitude by approximately a third than the sum of those produced by translation and rotation alone. In the light, the relative target displacement during isolated linear motion was similar to the difference in relative target displacements during eccentric and centred rotation. However, the gain of the translational component of compensatory eye movement during combined translational and angular motion was approximately unity, in contrast to the gain of the response to isolated linear motion, which was approximately a half. Pursuit performance was always poorer than target following during self-motion. The LVOR responses in the light were greater than the sum of the LVOR responses in the dark with pursuit eye movements. We conclude that, in response to transient motion, there is a synergistic enhancement of the translational VOR with concurrent canal

  4. Entropic Movement Complexity Reflects Subjective Creativity Rankings of Visualized Hand Motion Trajectories

    Science.gov (United States)

    Peng, Zhen; Braun, Daniel A.

    2015-01-01

    In a previous study we have shown that human motion trajectories can be characterized by translating continuous trajectories into symbol sequences with well-defined complexity measures. Here we test the hypothesis that the motion complexity individuals generate in their movements might be correlated to the degree of creativity assigned by a human observer to the visualized motion trajectories. We asked participants to generate 55 novel hand movement patterns in virtual reality, where each pattern had to be repeated 10 times in a row to ensure reproducibility. This allowed us to estimate a probability distribution over trajectories for each pattern. We assessed motion complexity not only by the previously proposed complexity measures on symbolic sequences, but we also propose two novel complexity measures that can be directly applied to the distributions over trajectories based on the frameworks of Gaussian Processes and Probabilistic Movement Primitives. In contrast to previous studies, these new methods allow computing complexities of individual motion patterns from very few sample trajectories. We compared the different complexity measures to how a group of independent jurors rank ordered the recorded motion trajectories according to their personal creativity judgment. We found three entropic complexity measures that correlate significantly with human creativity judgment and discuss differences between the measures. We also test whether these complexity measures correlate with individual creativity in divergent thinking tasks, but do not find any consistent correlation. Our results suggest that entropic complexity measures of hand motion may reveal domain-specific individual differences in kinesthetic creativity. PMID:26733896

  5. Entropic movement complexity reflects subjective creativity rankings of visualized hand motion trajectories

    Directory of Open Access Journals (Sweden)

    Zhen ePeng

    2015-12-01

    Full Text Available In a previous study we have shown that human motion trajectories can be characterized by translating continuous trajectories into symbol sequences with well-defined complexity measures. Here we test the hypothesis that the motion complexity individuals generate in their movements might be correlated to the degree of creativity assigned by a human observer to the visualized motion trajectories. We asked participants to generate fifty-five novel hand movement patterns in virtual reality, where each pattern had to be repeated ten times in a row to ensure reproducibility. This allowed us to estimate a probability distribution over trajectories for each pattern. We assessed motion complexity not only by the previously proposed complexity measures on symbolic sequences, but we also propose two novel complexity measures that can be directly applied to the distributions over trajectories based on the frameworks of Gaussian Processes and Probabilistic Movement Primitives. In contrast to previous studies, these new methods allow computing complexities of individual motion patterns from very few sample trajectories. We compared the different complexity measures to how a group of independent jurors rank ordered the recorded motion trajectories according to their personal creativity judgment. We found three entropic complexity measures that correlate significantly with human creativity judgment and discuss differences between the measures. We also test whether these complexity measures correlate with individual creativity in divergent thinking tasks, but do not find any consistent correlation. Our results suggest that entropic complexity measures of hand motion may reveal domain-specific individual differences in kinesthetic creativity.

  6. An investigation into the validity of cervical spine motion palpation using subjects with congenital block vertebrae as a 'gold standard'

    Directory of Open Access Journals (Sweden)

    Peterson Cynthia K

    2004-06-01

    Full Text Available Abstract Background Although the effectiveness of manipulative therapy for treating back and neck pain has been demonstrated, the validity of many of the procedures used to detect joint dysfunction has not been confirmed. Practitioners of manual medicine frequently employ motion palpation as a diagnostic tool, despite conflicting evidence regarding its utility and reliability. The introduction of various spinal models with artificially introduced 'fixations' as an attempt to introduce a 'gold standard' has met with frustration and frequent mechanical failure. Because direct comparison against a 'gold standard' allows the validity, specificity and sensitivity of a test to be calculated, the identification of a realistic 'gold standard' against which motion palpation can be evaluated is essential. The objective of this study was to introduce a new, realistic, 'gold standard', the congenital block vertebra (CBV to assess the validity of motion palpation in detecting a true fixation. Methods Twenty fourth year chiropractic students examined the cervical spines of three subjects with single level congenital block vertebrae, using two commonly employed motion palpation tests. The examiners, who were blinded to the presence of congenital block vertebrae, were asked to identify the most hypomobile segment(s. The congenital block segments included two subjects with fusion at the C2–3 level and one with fusion at C5-6. Exclusion criteria included subjects who were frankly symptomatic, had moderate or severe degenerative changes in their cervical spines, or displayed signs of cervical instability. Spinal levels were marked on the subject's skin overlying the facet joints from C1 to C7 bilaterally and the motion segments were then marked alphabetically with 'A' corresponding to C1-2. Kappa coefficients (K were calculated to determine the validity of motion palpation to detect the congenitally fused segments as the 'most hypomobile' segments. Sensitivity

  7. Superluminous Supernovae in the Dark Energy Survey

    Science.gov (United States)

    D'Andrea, Christopher; Smith, Mathew; Sullivan, Mark; Nichol, Bob; Pan, Yen-Chen; Thomas, Ben; Prajs, Szymon; Angus, Charlotte; Dark Energy Survey

    2018-01-01

    The Dark Energy Survey Supernova Program (DES-SN) has begun its fifth and final season of operations. With a six-day cadence over 27 deg2 in each 6-month observing season and griz depths of 23.5-24.5 mag (AB), DES-SN presents an impressive data set for obtaining high-quality superluminous supernova (SLSN) light curves. I present highlights of the discoveries of DES SLSNe to date. These include at least 18 spectroscopically-classified SLSNe over a redshift range 0.2 2 SLSNe which should be well above the limiting magnitude of the DES-SN data.

  8. Radiation of superluminal sources in vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Bolotovskii, B.M. [P.N. Lebedev Physical Institute, Leninsky prospect 53, Moscow 119991 (Russian Federation)]. E-mail: bolot@lpi.ru; Serov, A.V. [P.N. Lebedev Physical Institute, Leninsky prospect 53, Moscow 119991 (Russian Federation)]. E-mail: serov@x4u.levedev.ru

    2006-08-15

    Vavilov-Cherenkov radiation is emitted by a charged body uniformly moving in a medium when the body velocity exceeds that of light in the medium. Therefore, it was believed that Vavilov-Cherenkov radiation is impossible in vacuum, because the velocity of any material body cannot exceed the light velocity in vacuum. However, it is possible to realize distributions of charges and currents which propagate with any given velocity. Such a superluminal distribution can be used as a source of Vavilov-Cherenkov radiation in vacuum.

  9. Optics (communication arising): mechanism for 'superluminal' tunnelling.

    Science.gov (United States)

    Winful, Herbert G

    2003-08-07

    In their discussion of a mechanism that I proposed to explain the apparent superluminal (that is, faster than light) tunnelling of light pulses observed in photonic barrier experiments, Büttiker and Washburn used an old 'reshaping' argument that is at variance with my model and is not supported by the bulk of the experimental tunnelling evidence. The mechanism I proposed agrees with experiment and resolves a long-standing paradox - namely, the lack of dependence of tunnelling time on barrier length for thick barriers (the Hartman effect).

  10. Superluminal light propagation assisted by Zeeman coherence.

    Science.gov (United States)

    He, Huijuan; Hu, Zhengfeng; Wang, Yuzhu; Wang, Ligang; Zhu, Shiyao

    2006-08-15

    We have observed a dispersionlike absorption (or gain) spectrum at the D1 transition in a Rb vapor cell filled with a buffer gas, due to Zeeman coherence of the ground states in a double Lambda configuration. Meanwhile, we have also observed superluminal pulse propagation. It is experimentally demonstrated that the front speed of a light pulse still equals the light speed c in vacuum, although the group velocity of the light pulse is(-2.2+/-0.6) x 10(4) m/s.

  11. Multi-frequency response of a cylinder subjected to vortex shedding and support motions

    Energy Technology Data Exchange (ETDEWEB)

    Vikestad, Kyrre

    1998-12-31

    This thesis deals with an experimental investigation of vortex induced vibrations of a circular cylinder. The purpose of the experiment was to identify the influence from a controlled disturbance of the cylinder motions on the response caused by vortex shedding. The cylinder investigated is 2 m long and the diameter is 10 cm. The cylinder is elastically mounted in an apparatus using springs, where the foundation of one of the springs can have a harmonic motion. The apparatus is placed on a carriage in a 25 m long towing tank. Towing velocities are varied between 0.140 m/s and 0.655 m/s corresponding to reduced velocity range from 2.8 to 13.2. The still water natural frequency is 0.497 Hz, and the natural frequency in air is 0.634 Hz. The cylinder is only able to oscillate in the cross-flow direction. The support motion frequency was varied between 0.26 Hz and 1.01 Hz, and the force motion amplitude was varied using 2, 4 and 6 cm support amplitudes. Three sets of experiments were carried out: (1) Still water oscillations due to harmonic support motion excitation, support amplitude and frequencies varied, (2) Towing tests with no support motion, the velocity is varied, (3) Combined excitation: Towing tests with support motion. All possible combinations of experiments (1) and (2) are carried out. The two first experiments provide reference values for the combined excitation experiments and for verification purposes. The results reveal the ability of the external disturbance to influence the vortex shedding process both regarding frequency and the resulting response amplitudes. Results for added mass, in-line drag and damping are also obtained. The work may be of use in deep water floating petroleum production. 81 refs., 73 figs., 6 tabs.

  12. A cannonball model of gamma-ray bursts superluminal signatures

    CERN Document Server

    Dar, Arnon; Dar, Arnon; Rujula, Alvaro De

    2000-01-01

    Recent observations suggest that the long-duration gamma ray bursts (GRBs) and their afterglows are produced by highly relativistic jets emitted in supernova explosions. We propose that the result of the event is not just a compact object plus the ejecta: within a day, a fraction of the parent star falls back to produce a thick accretion disk. The subsequent accretion generates jets and constitutes the GRB ``engine'', as in the observed ejection of relativistic ``cannonballs'' of plasma by microquasars and active galactic nuclei. The GRB is produced as the jetted cannonballs exit the supernova shell reheated by the collision, re-emitting their own radiation and boosting the light of the shell. They decelerate by sweeping up interstellar matter, which is accelerated to cosmic-ray energies and emits synchrotron radiation: the afterglow. We emphasize here a smoking-gun signature of this model of GRBs: the superluminal motion of the afterglow, that can be searched for ---the sooner the better--- in the particular...

  13. Price for Environmental Neutrino-Superluminality

    CERN Document Server

    Dvali, Gia

    2012-01-01

    We ask whether the resent OPERA results on neutrino superluminality could be an environmental effect characteristic of the local neighborhood of our planet, without the need of violation of the Poincar\\'e-invariance at a fundamental level. This explanation requires the existence of a new spin-2 field of a planetary Compton wave-length that is coupled to neutrinos and the rest of the matter asymmetrically, both in the magnitude and in the sign. Sourced by the earth this field creates an effective metric on which neutrinos propagate superluminally, whereas other species are much less sensitive to the background. Such a setup, at an effective field theory level, passes all immediate phenomenological tests and its natural prediction is an inevitable appearance of a testable long-range gravity-type fifth force. We then prove that under the assumption of the weakly-coupled Poincar\\'e-invariant physics, the asymmetrically-coupled second massive graviton is the only possible environmental explanation. Despite phonemo...

  14. Superluminal warp drives are semiclassically unstable

    Energy Technology Data Exchange (ETDEWEB)

    Finazzi, S; Liberati, S [SISSA, via Beirut 2-4, Trieste 34151, Italy and INFN sezione di Trieste (Italy); Barcelo, C, E-mail: finazzi@sissa.i, E-mail: liberati@sissa.i, E-mail: carlos@iaa.e [Instituto de Astrofisica de AndalucIa, CSIC, Camino Bajo de Huetor 50, 18008 Granada (Spain)

    2010-04-01

    Warp drives are very interesting configurations of General Relativity: they provide a way to travel at superluminal speeds, albeit at the cost of requiring exotic matter to build them. Even if one succeeded in providing the necessary exotic matter, it would still be necessary to check whether they would survive to the switching on of quantum effects. Semiclassical corrections to warp-drive geometries created out of an initially flat spacetime have been analyzed in a previous work by the present authors in special locations, close to the wall of the bubble and in its center. Here, we present an exact numerical analysis of the renormalized stress-energy tensor (RSET) in the whole bubble. We find that the the RSET will exponentially grow in time close to the front wall of the superluminal bubble, after some transient terms have disappeared, hence strongly supporting our previous conclusion that the warp-drive geometries are unstable against semiclassical back-reaction. This result seems to implement the chronology protection conjecture, forbiddig the set up of a structure potentially dangerous for causality.

  15. Could dynamical Lorentz symmetry breaking induce the superluminal neutrinos?

    Energy Technology Data Exchange (ETDEWEB)

    Nojiri, Shin' ichi [Nagoya University, Department of Physics, Nagoya (Japan); Nagoya University, Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya (Japan); Odintsov, Sergei D. [Facultat de Ciencies, Institucio Catalana de Recerca i Estudis Avancats (ICREA) and Institut de Ciencies de l' Espai (IEEC-CSIC), Campus UAB, Bellaterra (Barcelona) (Spain); Tomsk State Pedagogical University, Tomsk (Russian Federation)

    2011-11-15

    A toy fermion model coupled to the Lagrange multiplier constraint field is proposed. The possibility of superluminal neutrino propagation as a result of dynamical Lorentz symmetry breaking is studied. (orig.)

  16. The hypothesis of superluminal neutrinos: Comparing OPERA with other data

    DEFF Research Database (Denmark)

    Drago, A.; Masina, I.; Pagliara, G.

    2012-01-01

    The OPERA Collaboration reported evidence for muonic neutrinos traveling slightly faster than light in vacuum. While waiting further checks from the experimental community, here we aim at exploring some theoretical consequences of the hypothesis that muonic neutrinos are superluminal, considering...

  17. Motion planning of mobile multi-limb robotic systems subject to force and friction constraints

    Science.gov (United States)

    Madhani, Akhil; Dubowsky, Steven

    1992-01-01

    A method is presented to generate motions for a class of multilimb robotic systems enabling them to apply large static forces over large ranges of motion without saturating actuator effort limits, system-environment friction constraints, kinematic joint limits, or geometric workspace obstacles. The approach, termed the force-workspace (FW) approach, maps these constraints into the system C-space to form constraint obstacles using a recursive subdivision process. To generate motions along which actuator efforts can be specified without violating system constraints, paths are planned that avoid these constraint obstacles. The method permits the shape of the paths to be controlled using any configuration-dependent performance criterion. The FW approach was applied to a proposed three-limb planar climbing robot whose task is to climb upwards between two vertical walls by pushing outwards to generate frictional support. Motions were planned automatically within the system FW, enabling it to lift itself upwards using two limbs at a time, and a gait was planned to enable it to switch limbs and climb continuously.

  18. Apparent superluminal motion in the quasar NRAO 140

    Science.gov (United States)

    Marscher, A. P.; Broderick, J. J.

    1982-01-01

    Very long baseline interferometer (VLBI) measurements of the compact radio structure in the quasar NRAO 140 (z = 1.258) have been obtained at three epochs at a wavelength of 2.8 cm. These observations indicate that the two most compact radio components are separating at an angular rate of 0.10-0.14 milli-arcsec per year. For cosmological distances H sub 0 = 50 and q sub 0 = 0, this corresponds to a velocity of separation (in the quasar's rest frame) of 10 + or - 2 times the speed of light, c; for H sub 0 = 100 and q sub 0 = 1, the value is (3.1 + or - 0.6) c. Other interpretations of the temporal changes in correlated flux density and closure phase are discussed and are considered unlikely. The derived velocities are consistent with an earlier prediction that the separation velocity should be greater than about 4 c. Extrapolation back to the epoch of zero separation indicates that the expansion originated between late 1963 and late 1968 (under the assumption of constant velocity). This range includes the beginning of an isolated outburst in flux density at 2.8 cm. These results cannot be used to make any statements concerning the validity of cosmological interpretations of QSO redshifts.

  19. A note on Lorentz-like transformations and superluminal motion

    Science.gov (United States)

    Jin, C.; Lazar, M.

    2015-07-01

    In this extended note a critical discussion of an extension of the Lorentz transformations for velocities faster than the speed of light given recently by Hill and Cox is provided. The presented approach reveals the connection between faster-than-light speeds and the issue of isotropy of space. It is shown if the relative speed between the two inertial frames $v$ is greater than the speed of light, the condition of isotropy of space cannot be retained. It further specifies the respective transformations applying to $-\\infty

  20. On the Superluminal Motion of Radio-Loud AGNs

    Indian Academy of Sciences (India)

    Author Affiliations. Zhi-Bin Zhang1 2 Yi-Zhen Zhang1 2. College of Science, Guizhou University, Guiyang, Guizhou 550025, China. The Joint Research Center for Astronomy Sponsored by GZU and NAOC, Guiyang, China.

  1. Towards long-distance superluminal propagation in optical fibers via cascaded Brillouin lasing resonators

    Science.gov (United States)

    Zhan, Li; Zhang, Liang; Wang, Tantan; Qin, Minglei; Liu, Jinmei

    2015-03-01

    Long distance superluminal propagation in optical fibers via cascaded Brillouin lasing oscillation is proposed and experimentally demonstrated. The Gaussian pulses experience negative group-velocity superluminal propagation with the advancement of ~300ns in 20-m single mode fiber.

  2. Acceleration by synchrotron absorption and superluminal sources

    Energy Technology Data Exchange (ETDEWEB)

    Ghisellini, G.; Bodo, G.; Trussoni, E.; Rees, M.J. (Torino Osservatorio Astronomico, Turin (Italy) Cambridge Univ. (England))

    1990-10-01

    A magnetized blob, containing relativistic electrons, can absorb, by the synchrotron process, low-frequency photons emitted by an underlying source. The momentum of the adsorbed photons can accelerate the blob to relativistic velocities. The final bulk Lorentz factor can be as large as required by observations of superluminal sources even if only the low-frequency part of the spectrum of a sub-Eddington central source is used for the acceleration process, and even if the blob contains an equal number of protons and electrons. This is mainly due to the large absorption cross section of the synchrotron process with respect to the electron scattering cross section, but partly because strongly aberrated photons are seen blueshifted in the rest frame of the blob and are less efficiently absorbed, reducing the importance of the braking force due to the radiation drag. 12 refs.

  3. Null energy condition and superluminal propagation

    CERN Document Server

    Dubovsky, S; Nicolis, A; Rattazzi, R

    2006-01-01

    We study whether a violation of the null energy condition necessarily implies the presence of instabilities. We prove that this is the case in a large class of situations, including isotropic solids and fluids relevant for cosmology. On the other hand we present several counter-examples of consistent effective field theories possessing a stable background where the null energy condition is violated. Two necessary features of these counter-examples are the lack of isotropy of the background and the presence of superluminal modes. We argue that many of the properties of massive gravity can be understood by associating it to a solid at the edge of violating the null energy condition. We briefly analyze the difficulties of mimicking $\\dot H>0$ in scalar tensor theories of gravity.

  4. Motion Control Design for an Omnidirectional Mobile Robot Subject to Velocity Constraints

    Directory of Open Access Journals (Sweden)

    Ollin Peñaloza-Mejía

    2015-01-01

    Full Text Available A solution to achieve global asymptotic tracking with bounded velocities in an omnidirectional mobile robot is proposed in this paper. It is motivated by the need of having a useful in-practice motion control scheme, which takes into account the physical limits of the velocities. To this end, a passive nonlinear controller is designed and combined with a tracking controller in a negative feedback connection structure. By using Lyapunov theory and passivity tools, global asymptotic tracking with desired bounded velocities is proved. Simulations and experimental results are provided to show the effectiveness of the proposal.

  5. Superluminal optical solitons in a four-level tripod atomic system

    Energy Technology Data Exchange (ETDEWEB)

    Han Dingan [Department of Physics, Foshan University, Foshan 528000 (China); Zeng, Yaguang [Department of Physics, Foshan University, Foshan 528000 (China); Bai Yanfeng [Key Laboratory for Quantum Optics and Center for Cold Atom Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Huang Chunqing [Department of Physics, Foshan University, Foshan 528000 (China)

    2006-07-28

    With one weak probe field and two strong pumping fields, superluminal optical solitons are formed in a lifetime-broadened four-level tripod atomic medium. With proper parameters, both dark and bright solitons can occur in the highly resonant medium. The corresponding group velocity of the solitons can be superluminal. Meanwhile, the conditions for superluminal solitons occurrence are given.

  6. Undershooting of a neutral reference position by asymptomatic subjects after cervical motion in the sagittal plane.

    Science.gov (United States)

    Hallgren, Richard C; Andary, Michael T

    2008-09-01

    The objective of this study was to determine if blindfolded, asymptomatic subjects undershoot or overshoot a self-selected neutral reference position (NRP) when performing a full-cycle, head repositioning accuracy test in the sagittal plane. An asymptomatic group of subjects, consisting of 7 men and 5 women with no history of head and neck pain, were recruited for the study. Subjects, performing a full-cycle series of head/neck movements in the sagittal plane, attempted to return to a self-selected NRP, defined at the beginning of the movement sequence, without benefit of visual clues. Data were collected for each subject, and repositioning errors were calculated. The sign of the error was used to determine if undershooting or overshooting of the NRP had occurred. Subjects undershot a self-selected NRP at statistically significant levels (P < .01) when performing the head repositioning accuracy test while blindfolded. Subjects undershot the NRP 83% of the time when moving from flexion to the NRP and undershot the NRP 92% of the time when moving from extension to the NRP. A Fisher exact test showed no significant difference between the number of times subjects undershot the NRP when moving from either flexion to the NRP or from extension to the NRP. To our knowledge, neither undershooting nor overshooting of an NRP has previously been reported for asymptomatic subjects at statistically significant levels. Knowing that asymptomatic subjects undershoot an NRP may help to direct treatment and rehabilitation of patients who have experienced whiplash-type injuries and are shown to overshoot the NRP when performing the same test.

  7. Motion noise cancellation in seismocardiogram of ambulant subjects with dual sensors.

    Science.gov (United States)

    Chenxi Yang; Tavassolian, Negar

    2016-08-01

    This paper presents a dual-sensor method of extracting seismocardiographic (SCG) data from moving adult subjects using chest-worn wireless MEMS accelerometers. A digital signal processing (DSP) system including a normalized least means square (NLMS) adaptive filter is designed and tested in MATLAB. Data results from 10 subjects indicate a detection rate of 98.72% which outperforms our previously-proposed single-sensor scheme. Various sensor positons and possible failure mechanisms are also investigated to further evaluate the system performance. The results reveal that the quality of the SCG signal from moving subjects could be improved by integrating information from multiple sensors at the cost of increasing system complexity.

  8. Chain dynamics and nanoparticle motion in attractive polymer nanocomposites subjected to large deformations.

    Science.gov (United States)

    Senses, Erkan; Tyagi, Madhusudan; Natarajan, Bharath; Narayanan, Suresh; Faraone, Antonio

    2017-11-08

    The effect of large deformation on the chain dynamics in attractive polymer nanocomposites was investigated using neutron scattering techniques. Quasi-elastic neutron backscattering measurements reveal a substantial reduction of polymer mobility in the presence of attractive, well-dispersed nanoparticles. In addition, large deformations are observed to cause a further slowing down of the Rouse rates at high particle loadings, where the interparticle spacings are slightly smaller than the chain dimensions, i.e. in the strongly confined state. No noticeable change, however, was observed for a lightly confined system. The reptation tube diameter, measured by neutron spin echo, remained unchanged after shear, suggesting that the level of chain-chain entanglements is not significantly affected. The shear-induced changes in the interparticle bridging reflect the slow nanoparticle motion measured by X-ray photon correlation spectroscopy. These results provide a first step for understanding how large shear can significantly affect the segmental motion in nanocomposites and open up new opportunities for designing mechanically responsive soft materials.

  9. Highly accurate analytic formulae for projectile motion subjected to quadratic drag

    Science.gov (United States)

    Turkyilmazoglu, Mustafa

    2016-05-01

    The classical phenomenon of motion of a projectile fired (thrown) into the horizon through resistive air charging a quadratic drag onto the object is revisited in this paper. No exact solution is known that describes the full physical event under such an exerted resistance force. Finding elegant analytical approximations for the most interesting engineering features of dynamical behavior of the projectile is the principal target. Within this purpose, some analytical explicit expressions are derived that accurately predict the maximum height, its arrival time as well as the flight range of the projectile at the highest ascent. The most significant property of the proposed formulas is that they are not restricted to the initial speed and firing angle of the object, nor to the drag coefficient of the medium. In combination with the available approximations in the literature, it is possible to gain information about the flight and complete the picture of a trajectory with high precision, without having to numerically simulate the full governing equations of motion.

  10. PROBABILISTIC SEISMIC ASSESSMENT OF BASE-ISOLATED NPPS SUBJECTED TO STRONG GROUND MOTIONS OF TOHOKU EARTHQUAKE

    Directory of Open Access Journals (Sweden)

    AHMER ALI

    2014-10-01

    Full Text Available The probabilistic seismic performance of a standard Korean nuclear power plant (NPP with an idealized isolation is investigated in the present work. A probabilistic seismic hazard analysis (PSHA of the Wolsong site on the Korean peninsula is performed by considering peak ground acceleration (PGA as an earthquake intensity measure. A procedure is reported on the categorization and selection of two sets of ground motions of the Tohoku earthquake, i.e. long-period and common as Set A and Set B respectively, for the nonlinear time history response analysis of the base-isolated NPP. Limit state values as multiples of the displacement responses of the NPP base isolation are considered for the fragility estimation. The seismic risk of the NPP is further assessed by incorporation of the rate of frequency exceedance and conditional failure probability curves. Furthermore, this framework attempts to show the unacceptable performance of the isolated NPP in terms of the probabilistic distribution and annual probability of limit states. The comparative results for long and common ground motions are discussed to contribute to the future safety of nuclear facilities against drastic events like Tohoku.

  11. Nonlocal Quantum Information Transfer Without Superluminal Signalling and Communication

    Science.gov (United States)

    Walleczek, Jan; Grössing, Gerhard

    2016-09-01

    It is a frequent assumption that—via superluminal information transfers—superluminal signals capable of enabling communication are necessarily exchanged in any quantum theory that posits hidden superluminal influences. However, does the presence of hidden superluminal influences automatically imply superluminal signalling and communication? The non-signalling theorem mediates the apparent conflict between quantum mechanics and the theory of special relativity. However, as a `no-go' theorem there exist two opposing interpretations of the non-signalling constraint: foundational and operational. Concerning Bell's theorem, we argue that Bell employed both interpretations, and that he finally adopted the operational position which is associated often with ontological quantum theory, e.g., de Broglie-Bohm theory. This position we refer to as "effective non-signalling". By contrast, associated with orthodox quantum mechanics is the foundational position referred to here as "axiomatic non-signalling". In search of a decisive communication-theoretic criterion for differentiating between "axiomatic" and "effective" non-signalling, we employ the operational framework offered by Shannon's mathematical theory of communication, whereby we distinguish between Shannon signals and non-Shannon signals. We find that an effective non-signalling theorem represents two sub-theorems: (1) Non-transfer-control (NTC) theorem, and (2) Non-signification-control (NSC) theorem. Employing NTC and NSC theorems, we report that effective, instead of axiomatic, non-signalling is entirely sufficient for prohibiting nonlocal communication. Effective non-signalling prevents the instantaneous, i.e., superluminal, transfer of message-encoded information through the controlled use—by a sender-receiver pair —of informationally-correlated detection events, e.g., in EPR-type experiments. An effective non-signalling theorem allows for nonlocal quantum information transfer yet—at the same time

  12. Stochastic vibration of the vehicle-bridge system subject to non-uniform ground motions

    Science.gov (United States)

    Zhu, D. Y.; Zhang, Y. H.; Kennedy, D.; Williams, F. W.

    2014-03-01

    A study of a train moving along a cable-stayed bridge is performed by considering both the stationary track irregularity and a non-stationary earthquake. A detailed bridge model with 3972 degrees of freedom is established while the train model consists of two locomotives and eight carriages. The equations of motion of the coupled system are obtained by using the displacement continuous condition at the contact, with track irregularities. The earthquake is assumed to occur once the train has entered the bridge. The pseudo-excitation method is used to find the random responses of the coupled system, and the results indicate that the effect of the earthquake is much greater than that of the track irregularities. The paper discusses the influence of the intensity of the earthquake, the wave propagation velocity, the speed of the train, and the dynamic interaction between the vehicles and the bridge.

  13. The Origin of Ekman Flow in a Cavity Subject to Impulsive Rotational Motions

    Directory of Open Access Journals (Sweden)

    Wen-Jei Yang

    2001-01-01

    Full Text Available An experimental study is performed to disclose the origin of Ekman flow on the surfaces of a rotating drum resulting from fluid-structure interaction after an impulsive start of motion (referred to as the spin-up process or an impulsive stop (the spin-down process. Laser Doppler velocimetry (LDV is employed to determine instantaneous distribution of both the radial and angular velocity components in the flow field inside the rotating drum. From these results, the secondary flow and the time history of the Ekman boundary layer thickness are determined. The tracer/light sheet method is also engaged to enable real-time visualization of flow patterns. Fluid viscosity, drum size and rotational speed are varied to determine their effects on fluid-structure interactions. Results may be applied to cavity flow in rotating machinery.

  14. Subject-specific liver motion modeling in MRI: a feasibility study on spatiotemporal prediction

    Science.gov (United States)

    Noorda, Yolanda H.; Bartels, Lambertus W.; Viergever, Max A.; Pluim, Josien P. W.

    2017-04-01

    A liver motion model based on registration of dynamic MRI data, as previously proposed by the authors, was extended with temporal prediction and respiratory signal data. The potential improvements of these extensions with respect to the original model were investigated. Additional evaluations were performed to investigate the limitations of the model regarding temporal prediction and extreme breathing motion. Data were acquired of four volunteers, with breathing instructions and a respiratory belt. The model was built from these data using spatial prediction only and using temporal forward prediction of 300 ms to 1200 ms, using the extended Kalman filter. From temporal prediction of 0 ms to 1200 ms ahead, the Dice coefficient of liver overlap decreased with 0.85%, the median liver surface distance increased with 20.6% and the vessel misalignment increased with 20%. The mean vessel misalignment was 2.9 mm for the original method, 3.42 mm for spatial prediction with a respiratory signal and 4.01 mm for prediction of 1200 ms ahead with a respiratory signal. Although the extension of the model to temporal prediction yields a decreased prediction accuracy, the results are still acceptable. The use of the breathing signal as input to the model is feasible. Sudden changes in the breathing pattern can yield large errors. However, these errors only persist during a short time interval, after which they can be corrected automatically. Therefore, this model could be useful in a clinical setting.

  15. Superluminal propagation of light pulses: A result of interference.

    Science.gov (United States)

    Wang, Li-Gang; Liu, Nian-Hua; Lin, Qiang; Zhu, Shi-Yao

    2003-12-01

    The propagation of pulses through dispersive media was investigated by solving Maxwell's equations without any approximation. We show that the superluminal propagation of pulses through anomalous dispersive media is a result of the interference of different frequency components composed of the pulse. The coherence of the pulse plays an important role for the superluminal propagation. With the decrease of the coherence of the pulse, the propagation changes from superluminal to subluminal. We have shown that the anomalous dispersion (the real part of the susceptibility) not the amplification (the imaginary part of the susceptibility) plays the essential role in the superluminal propagation. Although the superluminality always exists as long as the spectrum of the coherent pulse is within the anomalously dispersive region, both the energy propagation velocity and the frontal velocity never exceed the light speed in the vacuum. The output pulse through the medium is not the original pulse; instead it carries the information of the original pulse and the information of the prepared medium.

  16. Decisions in Motion: Decision Dynamics during Intertemporal Choice reflect Subjective Evaluation of Delayed Rewards

    Science.gov (United States)

    O'Hora, Denis; Carey, Rachel; Kervick, Aoife; Crowley, David; Dabrowski, Maciej

    2016-02-01

    People tend to discount rewards or losses that occur in the future. Such delay discounting has been linked to many behavioral and health problems, since people choose smaller short-term gains over greater long-term gains. We investigated whether the effect of delays on the subjective value of rewards is expressed in how people move when they make choices. Over 600 patrons of the RISK LAB exhibition hosted by the Science Gallery DublinTM played a short computer game in which they used a computer mouse to choose between amounts of money at various delays. Typical discounting effects were observed and decision dynamics indicated that choosing smaller short-term rewards became easier (i.e., shorter response times, tighter trajectories, less vacillation) as the delays until later rewards increased. Based on a sequence of choices, subjective values of delayed outcomes were estimated and decision dynamics during initial choices predicted these values. Decision dynamics are affected by subjective values of available options and thus provide a means to estimate such values.

  17. Subjectivity

    Directory of Open Access Journals (Sweden)

    Jesús Vega Encabo

    2015-11-01

    Full Text Available In this paper, I claim that subjectivity is a way of being that is constituted through a set of practices in which the self is subject to the dangers of fictionalizing and plotting her life and self-image. I examine some ways of becoming subject through narratives and through theatrical performance before others. Through these practices, a real and active subjectivity is revealed, capable of self-knowledge and self-transformation. 

  18. Tachyons, Lamb Shifts and Superluminal Chaos

    CERN Document Server

    Tomaschitz, R

    2000-01-01

    An elementary account on the origins of cosmic chaos in an open and multiply connected universe is given; there is a finite region in the open 3-space in which the world-lines of galaxies are chaotic, and the mixing taking place in this chaotic nucleus of the universe provides a mechanism to create equidistribution. The galaxy background defines a distinguished frame of reference and a unique cosmic time order; in this context superluminal signal transfer is studied. Tachyons are described by a real Proca field with negative mass square, coupled to a current of subluminal matter. Estimates on tachyon mixing in the geometric optics limit are derived. The potential of a static point source in this field theory is a damped periodic function. We treat this tachyon potential as a perturbation of the Coulomb potential, and study its effects on energy levels in hydrogenic systems. By comparing the induced level shifts to high-precision Lamb shift measurements and QED calculations, we suggest a tachyon mass of 2.1 ke...

  19. Superluminal Travel Made Possible (in two dimensions)

    CERN Document Server

    Dubovsky, Sergei

    2008-01-01

    We argue that superluminal signal propagation is possible in consistent Poincare invariant quantum field theories in two space-time dimensions, provided spatial parity is broken. This happens due to existence of the ``instantaneous'' causal structure, with one of the light cone variables being a global time. In two dimensions this causal structure is invariant under the Poincare group if one gives up the spatial parity. As a non-trivial example of a consistent interacting quantum field theory with this causal structure we discuss a non-linear SO(1,1) sigma-model, where SO(1,1) is the Lorentz symmetry. We show that this theory is asymptotically free and argue that this model is also well defined non-perturbatively, at least for some values of parameters. It provides an example of a microscopic Poincare invariant quantum field theory with local action, but non-local physical properties. Being coupled to gravity this ``instantaneous'' theory mixes with the Liouville field. If proves to be consistent, the resulti...

  20. Radio emission from embryonic superluminous supernova remnants

    Science.gov (United States)

    Omand, Conor M. B.; Kashiyama, Kazumi; Murase, Kohta

    2018-02-01

    It has been widely argued that Type-I superluminous supernovae (SLSNe-I) are driven by powerful central engines with a long-lasting energy injection after the core-collapse of massive progenitors. One of the popular hypotheses is that the hidden engines are fast-rotating pulsars with a magnetic field of B ˜ 1013-1015 G. Murase, Kashiyama & Mészáros proposed that quasi-steady radio/submm emission from non-thermal electron-positron pairs in nascent pulsar wind nebulae can be used as a relevant counterpart of such pulsar-driven supernovae (SNe). In this work, focusing on the nascent SLSN-I remnants, we examine constraints that can be placed by radio emission. We show that the Atacama Large Millimeter/submillimetre Array can detect the radio nebula from SNe at DL ˜ 1 Gpc in a few years after the explosion, while the Jansky Very Large Array can also detect the counterpart in a few decades. The proposed radio follow-up observation could solve the parameter degeneracy in the pulsar-driven SN model for optical/UV light curves, and could also give us clues to young neutron star scenarios for SLSNe-I and fast radio bursts.

  1. Testing the OPERA Superluminal Neutrino Anomaly at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Davoudiasl, Hooman; /Brookhaven; Rizzo, Thomas G.; /SLAC

    2012-03-15

    The OPERA collaboration has reported the observation of superluminal muon neutrinos, whose speed v{sub {nu}} exceeds that of light c, with (v{sub {nu}}-c)/c {approx_equal} 2.5 x 10{sup -5}. In a recent work, Cohen and Glashow (CG) have refuted this claim by noting that such neutrinos will lose energy, by pair-emission of particles, at unacceptable rates. Following the CG arguments, we point out that pair-emissions consistent with the OPERA anomaly can lead to detectable signals for neutrinos originating from decays of highly boosted top quarks at the LHC, allowing an independent test of the superluminal neutrino hypothesis.

  2. Gain-assisted Superluminal Propagation in Coupled Optical Resonators

    Science.gov (United States)

    Chang, Hongrok; Smith, David D.

    2005-01-01

    We predict transparent superluminal pulse propagation in co-resonant coupled optical resonators, when a gain element is placed in the resonator closest to the excitation waveguide, provided the structure is over-coupled, but the resonator farthest from the excitation waveguide is under-coupled sufficiently to avoid lasing at the split modes. The effective steady-state absorptive and dispersive response of coupled resonators is derived, and the coupled-mode approximation is used to determine the conditions for transparent superluminal pulse propagation in these systems.

  3. Testing the OPERA superluminal neutrino anomaly at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Davoudiasl H.; Rizzo, T.

    2011-11-28

    The OPERA Collaboration has reported the observation of superluminal muon neutrinos, whose speed v{sub v} exceeds that of light c, with (v{sub v}-c)/c {approx_equal} 2.5 x 10{sup -5}. In a recent work, Cohen and Glashow have refuted this claim by noting that such neutrinos will lose energy, by pair emission of particles, at unacceptable rates. Following the Cohen and Glashow arguments, we point out that pair emissions consistent with the OPERA anomaly can lead to detectable signals for neutrinos originating from decays of highly boosted top quarks at the LHC, allowing an independent test of the superluminal neutrino hypothesis.

  4. On the possibility of nonlinear quantum evolution and superluminal communication

    Science.gov (United States)

    Gao, Shan

    2014-09-01

    A possible mechanism of nonlinear quantum evolution is introduced and its implications for quantum communication are investigated. First, it is argued that an appropriate combination of wavefunction collapse and the consciousness of observer may permit the observer to distinguish nonorthogonal quantum states in principle, and thus consciousness will introduce certain nonlinearity into quantum dynamics. Next, it is shown that the distinguishability of nonorthogonal states can be used to achieve quantum superluminal communication, by which information can be transmitted nonlocally and faster than the speed of light. Finally, the issue of apparent incompatibility between superluminal communication and special relativity is briefly addressed.

  5. A Blind Pilot: Who is a Super-Luminal Observer?

    Directory of Open Access Journals (Sweden)

    Rabounski D.

    2008-04-01

    Full Text Available This paper discusses the nature of a hypothetical super-luminal observer who, as well as a real (sub-light speed observer, perceives the world by light waves. This consideration is due to that fact that the theory of relativity permits different frames of reference, including light-like and super-luminal reference frames. In analogy with a blind pilot on board a supersonic jet aeroplane (or missile, perceived by blind people, it is concluded that the light barrier is observed in the framework of only the light signal exchange experiment.

  6. Assessment of tidal volume and thoracoabdominal motion using volume and flow-oriented incentive spirometers in healthy subjects

    Directory of Open Access Journals (Sweden)

    V.F. Parreira

    2005-07-01

    Full Text Available The objective of the present study was to evaluate incentive spirometers using volume- (Coach and Voldyne and flow-oriented (Triflo II and Respirex devices. Sixteen healthy subjects, 24 ± 4 years, 62 ± 12 kg, were studied. Respiratory variables were obtained by respiratory inductive plethysmography, with subjects in a semi-reclined position (45º. Tidal volume, respiratory frequency, minute ventilation, inspiratory duty cycle, mean inspiratory flow, and thoracoabdominal motion were measured. Statistical analysis was performed with Kolmogorov-Smirnov test, t-test and ANOVA. Comparison between the Coach and Voldyne devices showed that larger values of tidal volume (1035 ± 268 vs 947 ± 268 ml, P = 0.02 and minute ventilation (9.07 ± 3.61 vs 7.49 ± 2.58 l/min, P = 0.01 were reached with Voldyne, whereas no significant differences in respiratory frequency were observed (7.85 ± 1.24 vs 8.57 ± 1.89 bpm. Comparison between flow-oriented devices showed larger values of inspiratory duty cycle and lower mean inspiratory flow with Triflo II (0.35 ± 0.05 vs 0.32 ± 0.05 ml/s, P = 0.00, and 531 ± 137 vs 606 ± 167 ml/s, P = 0.00, respectively. Abdominal motion was larger (P < 0.05 during the use of volume-oriented devices compared to flow-oriented devices (52 ± 11% for Coach and 50 ± 9% for Voldyne; 43 ± 13% for Triflo II and 44 ± 14% for Respirex. We observed that significantly higher tidal volume associated with low respiratory frequency was reached with Voldyne, and that there was a larger abdominal displacement with volume-oriented devices.

  7. A Non-Mainstream Viewpoint on Apparent Superluminal ...

    Indian Academy of Sciences (India)

    Abstract. The group velocity of light in material around the AGN jet is acquiescently one (c as a unit), but this is only a hypothesis. Here, we re-derive apparent superluminal and Doppler formulas for the general case (it is assumed that the group velocity of light in the uniform and isotropic medium around a jet (a beaming ...

  8. A Non-Mainstream Viewpoint on Apparent Superluminal ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... The group velocity of light in material around the AGN jet is acquiescently one ( as a unit), but this is only a hypothesis. Here, we re-derive apparent superluminal and Doppler formulas for the general case (it is assumed that the group velocity of light in the uniform and isotropic medium around a jet (a ...

  9. Superluminous supernova progenitors have a half-solar metallicity threshold

    Science.gov (United States)

    Chen, Ting-Wan; Smartt, Stephen J.; Yates, Rob M.; Nicholl, Matt; Krühler, Thomas; Schady, Patricia; Dennefeld, Michel; Inserra, Cosimo

    2017-09-01

    Host galaxy properties provide strong constraints on the stellar progenitors of superluminous supernovae. By comparing a sample of 19 low-redshift (z explosion site is likely lower than the integrated host value. We found that superluminous supernova hosts do not always have star formation rates higher than typical star-forming galaxies of the same mass. However, we confirm that high absolute specific star formation rates are a feature of superluminous supernova host galaxies, but interpret this as simply a consequence of the anticorrelation between gas-phase metallicity and specific star formation rate and the requirement of on-going star formation to produce young, massive stars greater than ∼10-20 M⊙. Based on our sample, we propose an upper limit of ˜ 0.5 Z_{⊙} for forming superluminous supernova progenitors (assuming an N2 metallicity diagnostic and a solar oxygen abundance of 8.69). Finally, we show that if magnetar powering is the source of the extreme luminosity, then the required initial spins appear to be correlated with metallicity of the host galaxy. This correlation needs further work, but if it applies, it is a powerful link between the supernova parameters and nature of the progenitor population.

  10. Demonstration of superluminal effects in an absorptionless, nonreflective system.

    Science.gov (United States)

    Solli, D R; McCormick, C F; Ropers, C; Morehead, J J; Chiao, R Y; Hickmann, J M

    2003-10-03

    We present an experimental and theoretical study of a simple, passive system consisting of a birefringent, two-dimensional photonic crystal and a polarizer in series, and show that superluminal dispersive effects can arise even though no incident radiation is absorbed or reflected. We demonstrate that a vector formulation of the Kramers-Kronig dispersion relations facilitates an understanding of these counterintuitive effects.

  11. Quantum radiation from superluminal refractive-index perturbations.

    Science.gov (United States)

    Belgiorno, F; Cacciatori, S L; Ortenzi, G; Sala, V G; Faccio, D

    2010-04-09

    We analyze in detail photon production induced by a superluminal refractive-index perturbation in realistic experimental operating conditions. The interaction between the refractive-index perturbation and the quantum vacuum fluctuations of the electromagnetic field leads to the production of photon pairs.

  12. Superluminal Physics and Instantaneous Physics as New Trends in Research

    Directory of Open Access Journals (Sweden)

    Smarandache F.

    2012-01-01

    Full Text Available In a similar way as passing from Euclidean Geometry to Non-Euclidean Geometry, we can pass from Subluminal Physics to Superluminal Physics, and further to Instantaneous Physics. In the lights of two consecutive successful CERN experiments with superlumi- nal particles in the Fall of 2011, we believe that these two new fields of research should begin developing.

  13. Apparent superluminal advancement of a single photon far beyond its coherence length

    Energy Technology Data Exchange (ETDEWEB)

    Cialdi, Simone; Boscolo, Ilario; Castelli, Fabrizio; Petrillo, Vittoria [Istituto Nazionale di Fisica Nucleare and Dipartimento di Fisica, Universita di Milano, Via Celoria 16, 20133 Milano (Italy)], E-mail: fabrizio.castelli@mi.infn.it

    2009-02-15

    We present experimental results relative to superluminal propagation based on a single photon traversing an optical system, called a 4f-system, which acts singularly on the photon's spectral component phases. A single photon is created by a continuous wave (CW) laser light down-conversion process. The introduction of a linear spectral phase function will lead to the shift of the photon peak far beyond the coherence length of the photon itself (an apparent superluminal propagation of the photon). Superluminal group velocity detection is done by interferometric measurement of the temporally shifted photon with its correlated untouched reference. The observed superluminal photon propagation complies with causality. The operation of the optical system allows the origin of the apparent superluminal photon velocity to be elucidated. The experiment foresees a superluminal effect with single-photon wavepackets.

  14. Relativistic causality and superluminal signalling using X-shaped localized waves

    Energy Technology Data Exchange (ETDEWEB)

    Shaarawi, Amr M . [School of Science and Engineering, American University in Cairo, Cairo (Egypt); Besieris, Ioannis M. [Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA (United States)

    2000-10-13

    It has been established theoretically and experimentally that X-shaped localized waves have peaks that travel at superluminal speeds. A study of the excitation of such pulses has shown that their peaks undergo a delayed generation before they are launched. Consequently, these peaks travel at superluminal speeds for a finite distance beyond which they propagate at the speed of light. We demonstrate that this local superluminal propagation does not constitute a violation of the theory of special relativity in a global sense. The use of this local superluminality in signalling is investigated and implications pertaining to causality are discussed. (author)

  15. Euclid: Superluminous supernovae in the Deep Survey

    Science.gov (United States)

    Inserra, C.; Nichol, R. C.; Scovacricchi, D.; Amiaux, J.; Brescia, M.; Burigana, C.; Cappellaro, E.; Carvalho, C. S.; Cavuoti, S.; Conforti, V.; Cuillandre, J.-C.; da Silva, A.; De Rosa, A.; Della Valle, M.; Dinis, J.; Franceschi, E.; Hook, I.; Hudelot, P.; Jahnke, K.; Kitching, T.; Kurki-Suonio, H.; Lloro, I.; Longo, G.; Maiorano, E.; Maris, M.; Rhodes, J. D.; Scaramella, R.; Smartt, S. J.; Sullivan, M.; Tao, C.; Toledo-Moreo, R.; Tereno, I.; Trifoglio, M.; Valenziano, L.

    2018-01-01

    Context. In the last decade, astronomers have found a new type of supernova called superluminous supernovae (SLSNe) due to their high peak luminosity and long light-curves. These hydrogen-free explosions (SLSNe-I) can be seen to z 4 and therefore, offer the possibility of probing the distant Universe. Aims: We aim to investigate the possibility of detecting SLSNe-I using ESA's Euclid satellite, scheduled for launch in 2020. In particular, we study the Euclid Deep Survey (EDS) which will provide a unique combination of area, depth and cadence over the mission. Methods: We estimated the redshift distribution of Euclid SLSNe-I using the latest information on their rates and spectral energy distribution, as well as known Euclid instrument and survey parameters, including the cadence and depth of the EDS. To estimate the uncertainties, we calculated their distribution with two different set-ups, namely optimistic and pessimistic, adopting different star formation densities and rates. We also applied a standardization method to the peak magnitudes to create a simulated Hubble diagram to explore possible cosmological constraints. Results: We show that Euclid should detect approximately 140 high-quality SLSNe-I to z 3.5 over the first five years of the mission (with an additional 70 if we lower our photometric classification criteria). This sample could revolutionize the study of SLSNe-I at z > 1 and open up their use as probes of star-formation rates, galaxy populations, the interstellar and intergalactic medium. In addition, a sample of such SLSNe-I could improve constraints on a time-dependent dark energy equation-of-state, namely w(a), when combined with local SLSNe-I and the expected SN Ia sample from the Dark Energy Survey. Conclusions: We show that Euclid will observe hundreds of SLSNe-I for free. These luminous transients will be in the Euclid data-stream and we should prepare now to identify them as they offer a new probe of the high-redshift Universe for both

  16. List-Mode PET Motion Correction Using Markerless Head Tracking: Proof-of-Concept With Scans of Human Subject

    DEFF Research Database (Denmark)

    Olesen, Oline Vinter; Sullivan, Jenna M.; Mulnix, Tim

    2013-01-01

    was time-varying with long drift motions of up to 18 mm and regular step-wise motion of 1–6 mm. The evaluated measures were significantly better for motion-corrected images compared to no MC. The demonstrated system agreed with a commercial integrated system. Motion-corrected images were improved......A custom designed markerless tracking system was demonstrated to be applicable for positron emission tomography (PET) brain imaging. Precise head motion registration is crucial for accurate motion correction (MC) in PET imaging. State-of-the-art tracking systems applied with PET brain imaging rely...... on markers attached to the patient's head. The marker attachment is the main weakness of these systems. A healthy volunteer participating in a cigarette smoking study to image dopamine release was scanned twice for 2 h with $^{11}{\\rm C}$-racolopride on the high resolution research tomograph (HRRT) PET...

  17. The Seismic Response of High-Speed Railway Bridges Subjected to Near-Fault Forward Directivity Ground Motions Using a Vehicle-Track-Bridge Element

    Directory of Open Access Journals (Sweden)

    Chen Ling-kun

    2014-01-01

    Full Text Available Based on the Next Generation Attenuation (NGA project ground motion library, the finite element model of the high-speed railway vehicle-bridge system is established. The model was specifically developed for such system that is subjected to near-fault ground motions. In addition, it accounted for the influence of the rail irregularities. The vehicle-track-bridge (VTB element is presented to simulate the interaction between train and bridge, in which a train can be modeled as a series of sprung masses concentrated at the axle positions. For the short period railway bridge, the results from the case study demonstrate that directivity pulse effect tends to increase the seismic responses of the bridge compared with far-fault ground motions or nonpulse-like motions and the directivity pulse effect and high values of the vertical acceleration component can notably influence the hysteretic behaviour of piers.

  18. Comparison of in vivo segmental foot motion during walking and step descent in patients with midfoot arthritis and matched asymptomatic control subjects.

    Science.gov (United States)

    Rao, Smita; Baumhauer, Judith F; Tome, Josh; Nawoczenski, Deborah A

    2009-05-29

    The purpose of this study was to compare in vivo segmental foot motion during walking and step descent in patients with midfoot arthritis and asymptomatic control subjects. Segmental foot motion during walking and step descent was assessed using a multi-segment foot model in 30 patients with midfoot arthritis and 20 age, gender and BMI matched controls. Peak and total range of motion (ROM), referenced to subtalar neutral, were examined for each of the following dependent variables: 1st metatarso-phalangeal (MTP1) dorsiflexion, 1st metatarsal (MT1) plantarflexion, ankle dorsiflexion, calcaneal eversion and forefoot abduction. The results showed that, compared to level walking, step descent required greater MTP1 dorsiflexion (pplantarflexion (pdorsiflexion (pdorsiflexion (pdorsiflexion (pplantarflexion excursion compared to control subjects (p=0.03). However, during step descent, both groups showed similar MT1 plantarflexion excursion. During walking, patients with midfoot arthritis showed similar calcaneus eversion excursion compared to control subjects. However, during step descent, patients with midfoot arthritis showed significantly greater calcaneus eversion excursion compared to control subjects (p=0.03). Independently or in combination, these motions may contribute to articular stress and consequently to symptoms in patients with midfoot arthritis.

  19. On the impossibility of superluminal travel in Lorentz violating theories

    CERN Document Server

    Coutant, Antonin; Liberati, Stefano; Parentani, Renaud

    2011-01-01

    Warp drives are space-times allowing for superluminal travel. However, they are quantum mechanically unstable because they produce a Hawking-like radiation which is blue shifted at their front wall without any bound. We re-examine this instability when local Lorentz invariance is violated at ultra high energy by dispersion, as in some theories of quantum gravity. Interestingly, even though the ultraviolet divergence is now regulated, warp drives are still unstable. Moreover the type of instability is different whether one uses a subluminal or a superluminal dispersion relation. In the first case, a black-hole laser yields an exponential amplification of the emitted flux whereas, in the second, infrared effects produce a linear growth of that flux. These results suggest that chronology could still be protected when violating Lorentz invariance.

  20. Milliarcsecond polarization structure of the superluminal quasar 3C 273

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, D.H.; Kollgaard, R.I.; Brown, L.F.; Gabuzda, D.C.; Wardle, J.F. C. (Brandeis Univ., Waltham, MA (USA))

    1990-09-01

    A 2 x 10 marcsec-resolution determination is presented for the total intensity and linear polarization structures of the superluminal quasar 3C 273 at 5 GHz. Substantial polarized flux was detected from several superluminal components of the jet, whose fractional polarization increased symmetrically with distance from the core; the most distant component is highly polarized and exhibits a highly ordered magnetic field. Within a few marcsec of the core, the inferred magnetic field orientation varies rapidly with position along the jet. The primarily longitudinal magnetic field orientation is concluded to become established within 20 marcsec of the core. A highly disorganized magnetic field is the most plausible explanation for the low degree of polarization in the innermost regions of the jet. 48 refs.

  1. Sub- and Superluminal Velocities in Space with Vector Time

    CERN Document Server

    Barashenkov, V S

    2000-01-01

    Within the bounds of the known relativistic theory the hypothesis of superluminal velosities allows one to influence the Past what leads to acausal paradoxes. We should like tostress, however, that this conclusion is based on thecontradictory continuation of the customary Lorentz transformations after the light barrier. Since at present no other prohibitions forfaster-than-light signals carrying the energy and information are unknown, the answer on the question does exist such signals or not cannot be obtained only from an experiment or from amore general theory. As such a generalization of a theory with vector time is considered which allows one some superluminal phenomena compatible with the principles ofrelativity and causality. Spreading ofsignals in themultitime world is characterized by some peculiarities which can be used for an experimental determination of the time dimensionality ofour world.

  2. On the superluminal propagation of X-shaped localized waves

    Energy Technology Data Exchange (ETDEWEB)

    Shaarawi, Amr M. [School of Science and Engineering, American University in Cairo, Cairo (Egypt); Besieris, Ioannis M. [Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA (United States)

    2000-10-13

    The generation and propagation of superluminal X-shaped pulses is investigated. We demonstrate that such pulses can be modelled using a spectral approach that produces time-limited Bessel beams. Special attention is given to calculating the velocities of the modelled pulsed Bessel beams. The velocities of the peaks of the resulting pulses depend on the shapes of the spatio-temporal distributions of the applied time-windows. The generation of pulsed Bessel beams is investigated for various set-ups; including circular arrays, annular slits and axicons. It is shown that superluminal pulsed Bessel beams undergo a delayed generation before they are launched; henceforth, the peak of these pulses travels at speeds exceeding that of light. (author)

  3. Superluminal X-wave propagation: energy localization and velocity.

    Science.gov (United States)

    Mugnai, D; Mochi, I

    2006-01-01

    The electromagnetic propagation of a Bessel-X wave is analyzed on the basis of a vectorial treatment in order to obtain information about the propagation of energy flux and the velocity of the energy. Knowledge of these quantities is of great interest since they are connected to the production of localized electromagnetic energy and to the topic of superluminality, respectively. The electric and magnetic fields are obtained in the far-field approximation by considering a realistic situation able to generate a Bessel-X wave. The vectorial treatment confirms the capability of this kind of wave to localize energy, while, quite surprisingly, even if the group velocity is superluminal, the energy velocity is equal to the light speed.

  4. Multifrequency observations of the superluminal quasar 3C 345

    Science.gov (United States)

    Bregman, J. N.; Glassgold, A. E.; Huggins, P. J.; Neugebauer, G.; Soifer, B. T.; Matthews, K.; Roellig, T. P. L.; Bregman, J. D.; Witteborn, F. C.; Lester, D. F.

    1986-01-01

    Attention is given to the continuum properties of the superluminal quasar 3C 345, on the basis of radio, optical, IR, and X-ray frequency monitorings, as well as by means of simultaneous multifrequency spectra extending from the radio through the X-ray bands. Radio outbursts, which appear to follow IR-optical outbursts by about one year, first occur at the highest frequencies, as expected from optical depth effects; the peak flux is nevertheless often reached at several frequencies at once. The beginning of outbursts, as defined by mm-measurements, corresponds to the appearance of the three known 'superluminal' components. An increase in the X-ray flux during 1979-1980 corresponds to increased radio flux, while the IR flux changes in the opposite sense.

  5. Coherent population oscillations and superluminal light in a protein complex.

    Science.gov (United States)

    Yelleswarapu, Chandra S; Laoui, Samir; Philip, Reji; Rao, D V G L N

    2008-03-17

    We observed superluminal light in aqueous solution of the protein complex bacteriorhodopsin (bR) at 647.1 nm wavelength where it exhibits reverse saturable behavior, exploiting the technique of coherent population oscillations (CPO). With a modulation frequency of 10 Hz, the signal pulse through a 1 cm path cell is ahead by 3 msec relative to the reference pulse, corresponding to a group velocity of -3.3 m/sec. Following our early work on slow light in the same sample at the saturable wavelength 568.2 nm, we now explicitly observed the narrow spectral hole in the absorption band of the stable B state and further, demonstrated a close correlation between the profile of the hole and the corresponding pulse delay for various modulation frequencies. A similar behavior is observed for superluminal light versus antihole blown in the absorption band.

  6. Subluminal and superluminal pulse propagation influenced by strong nonlinear effects

    Science.gov (United States)

    Chang, Zengguang; Qi, Yihong; Niu, Yueping; Zhang, Jingtao; Gong, Shangqing

    2012-12-01

    A scheme is proposed for control of pulse propagation from subluminal to superluminal in a four-level Λ-type atomic system. With the relatively intense probe laser and the appropriate detuning of control field, the medium exhibits much lower absorption in the spectral ranges where the dispersion changes from normal to abnormal in the double electromagnetically induced transparency system than in the single electromagnetically induced transparency system. The transmission intensity can be enhanced by several times for the subluminal pulse propagation and by several orders of magnitude for the superluminal pulse propagation without the large distortion in the former compared with those in the latter. We attribute the dramatic absorption reduction to the enhanced nonlinear effects.

  7. Superluminal propagation of solitary kinklike waves in amplifying media.

    Science.gov (United States)

    Janowicz, Maciej; Mostowski, Jan

    2006-04-01

    It is shown that solitary-wave, kinklike structures can propagate superluminally in two- and four-level amplifying media with strongly damped oscillations of coherences. This is done by solving analytically the Maxwell-Bloch equations in the kinetic limit. It is also shown that the true wave fronts--unlike the pseudo wave fronts of the kinks--must propagate with velocity c, so that no violation of special relativity is possible. The conditions of experimental verification are discussed.

  8. Superluminal neutrinos from Lorentz-violating dimension-5 operators

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, C.A.G. [Universidade Federal da Paraiba, Departamento de Ciencias Exatas, Rio Tinto, Paraiba (Brazil); Anacleto, M.A.; Brito, F.A.; Passos, E. [Universidade Federal de Campina Grande, Departamento de Fisica, Caixa Postal 10071, Campina Grande, Paraiba (Brazil)

    2012-01-15

    We consider Lorentz- and CPT-violating dimension-5 operators to address the issue of superluminal neutrinos recently pointed out in OPERA experiments. We assume these operators in the photon and neutrino sectors to be coupled to Lorentz-violating backgrounds in a preferred frame defined by a time-like direction. We show that such operators can produce a curve with OPERA's slope that fits OPERA, MINOS and supernova SN1987a data. (orig.)

  9. Superluminal tunneling of microwaves in smoothly varying transmission lines.

    Science.gov (United States)

    Shvartsburg, A B; Marklund, M; Brodin, G; Stenflo, L

    2008-07-01

    Tunneling of microwaves through a smooth barrier in a transmission line is considered. In contrast to standard wave barriers, we study the case where the dielectric permittivity is positive, and the barrier is caused by the inhomogeneous dielectric profile. It is found that reflectionless, superluminal tunneling can take place for waves with a finite spectral width. The consequences of these findings are discussed, and an experimental setup testing our predictions is proposed.

  10. Linearly polarized superluminal electromagnetic solitons in cold relativistic plasmas.

    Science.gov (United States)

    Saxena, Vikrant; Sen, Abhijit; Kaw, Predhiman

    2009-07-01

    We investigate a special class of coupled nonlinear superluminal solitons arising from the interaction of an intense linearly polarized electromagnetic pulse with a cold plasma. These modulated envelope structures are obtained as numerical solutions of the classic Akhiezer-Polovin model equations [Sov. Phys. JETP 3, 696 (1956)]. We also present a multiple time scale perturbation analysis in the small amplitude limit that provides a close analytic description of these nonlinear solutions.

  11. Superluminal behavior in the near field of crossing microwave beams

    Energy Technology Data Exchange (ETDEWEB)

    Ranfagni, Anedio; Mugnai, Daniela

    2004-03-01

    Superluminal processes in wave propagation have been demonstrated in several cases, but whether this behavior can be extended to the signal velocity is still a debatable question. In this Letter, we present new experimental results on microwave propagation in open space, which show anomalous behavior in the near field range. We discuss their interpretation by considering a variety of mechanisms, including standard theories, as well as less canonical ones. This new experiment provides further opportunities to discuss this intriguing and debated topic.

  12. Superluminal plasmons with resonant gain in population inverted bilayer graphene

    KAUST Repository

    Low, Tony

    2017-12-28

    AB-stacked bilayer graphene with a tunable electronic bandgap in excess of the optical phonon energy presents an interesting active medium, and we consider such theoretical possibility in this work. We argue the possibility of a highly resonant optical gain in the vicinity of the asymmetry gap. Associated with this resonant gain are strongly amplified plasmons, plasmons with negative group velocity and superluminal effects, as well as directional leaky modes.

  13. Launching of non-dispersive sub- and superluminal beams

    Energy Technology Data Exchange (ETDEWEB)

    Barashenkov, V.S. [Dubna (Russian Federation). Joint Institute for Nuclear Research; Rodrigues jr, W.A. [Campinas, SP (Brazil). Institute of Mathematics, Statistics and Scientific Computation

    1998-03-01

    This paper analyze the physical meaning of sub- and superluminal soliton-like solutions (as the X-waves) of the relativistic wave equations and of some non-trivial solutions of the free Schrodinger equations for which the concepts of phase and group velocities have a different meaning than in the case of plane-wave solutions. If it is accepted the strict validity of the principle of relativity, such solutions describe objects of two essentially different nature: carrying energy wave packets and inertia-free proper phase vibrations. The speeds of the first-type objects can exceed the plane-wave velocity c{sub *} only inside media and are always less than the vacuum light speed c. Particularly, very fast sound pulses with speeds c{sub *}superluminal speed. If it is admitted the possibility of a breakdown of Lorentz invariance, pulses described, for example, by superluminal solutions of the Maxwell equations can be generated. Only experiment will give the final answer.

  14. The superluminal velocities as the consequence of non-classical states of electromagnetic field

    Science.gov (United States)

    Veklenko, B. A.

    2017-06-01

    It was shown within the framework of conventional quantum electrodynamics, and without using perturbation theory, the presence of superluminal signals, transferring the information, while investigating the scattering of quantum electromagnetic field by excited atom. The superluminal signals are impossible in the theory of free fields, but their existence is predicted by the theory of interacting fields.

  15. Superluminal localized solutions to Maxwell equations propagating along a waveguide: the finite-energy case.

    Science.gov (United States)

    Zamboni-Rached, Michel; Fontana, Flavio; Recami, Erasmo

    2003-03-01

    In a previous paper we have shown localized (nonevanescent) solutions to Maxwell equations to exist, which propagate without distortion with superluminal speed along normal-sized waveguides, and consist in trains of "X-shaped" beams. Those solutions possessed infinite energy. In this paper we show how to obtain, by contrast, finite-energy solutions, with the same localization and superluminality properties.

  16. The effect of superluminal phase velocity on electron acceleration in a powerful electromagnetic wave

    Science.gov (United States)

    Robinson, A. P. L.; Arefiev, A. V.; Khudik, V. N.

    2015-08-01

    In this paper, we examine the effect that electromagnetic dispersion has on the motion of an electron in a relativistically strong plane wave. We obtain an analytic solution for the electron momentum and check this solution against direct numerical integration of the equations of motion. The solution shows that even a relatively small difference between the phase velocity of the wave, vp, and the speed of light, c, can significantly alter the electron dynamics if the normalized wave amplitude a0 exceeds √{2 c /(vp-c ) } . At this amplitude, the maximum longitudinal electron momentum scales only linearly with a0, as opposed to a02 . We also show that at this amplitude the impact of an accelerating longitudinal electric field and electron pre-acceleration is negated by the superluminous phase velocity of the wave. This has implications for the potential of Direct Laser Acceleration of electrons. We point out that electromagnetic dispersion can arise from both propagation in a plasma and from propagating the laser in what is effectively a wave-guiding structure, and that this latter source of dispersion is likely to be more significant.

  17. Time-frequency dynamics of superluminal pulse transition to the subluminal regime

    Science.gov (United States)

    Dorrah, Ahmed H.; Ramakrishnan, Abhinav; Mojahedi, Mo

    2015-03-01

    Spectral reshaping and nonuniform phase delay associated with an electromagnetic pulse propagating in a temporally dispersive medium may lead to interesting observations in which the group velocity becomes superluminal or even negative. In such cases, the finite bandwidth of the superluminal region implies the inevitable existence of a cutoff distance beyond which a superluminal pulse becomes subluminal. In this paper, we derive a closed-form analytic expression to estimate this cutoff distance in abnormal dispersive media with gain. Moreover, the method of steepest descent is used to track the time-frequency dynamics associated with the evolution of the center of mass of a superluminal pulse to the subluminal regime. This evolution takes place at longer propagation depths as a result of the subluminal components affecting the behavior of the pulse. Finally, the analysis presents the fundamental limitations of superluminal propagation in light of factors such as the medium depth, pulse width, and the medium dispersion strength.

  18. Effectiveness of slow motion video compared to real time video in improving the accuracy and consistency of subjective gait analysis in dogs

    Directory of Open Access Journals (Sweden)

    D.M. Lane

    2015-11-01

    Full Text Available Objective measures of canine gait quality via force plates, pressure mats or kinematic analysis are considered superior to subjective gait assessment (SGA. Despite research demonstrating that SGA does not accurately detect subtle lameness, it remains the most commonly performed diagnostic test for detecting lameness in dogs. This is largely because the financial, temporal and spatial requirements for existing objective gait analysis equipment makes this technology impractical for use in general practice. The utility of slow motion video as a potential tool to augment SGA is currently untested. To evaluate a more accessible way to overcome the limitations of SGA, a slow motion video study was undertaken. Three experienced veterinarians reviewed video footage of 30 dogs, 15 with a diagnosis of primary limb lameness based on history and physical examination, and 15 with no indication of limb lameness based on history and physical examination. Four different videos were made for each dog, demonstrating each dog walking and trotting in real time, and then again walking and trotting in 50% slow motion. For each video, the veterinary raters assessed both the degree of lameness, and which limb(s they felt represented the source of the lameness. Spearman’s rho, Cramer’s V, and t-tests were performed to determine if slow motion video increased either the accuracy or consistency of raters’ SGA relative to real time video. Raters demonstrated no significant increase in consistency or accuracy in their SGA of slow motion video relative to real time video. Based on these findings, slow motion video does not increase the consistency or accuracy of SGA values. Further research is required to determine if slow motion video will benefit SGA in other ways.

  19. Estimation of Pulmonary Motion in Healthy Subjects and Patients with Intrathoracic Tumors Using 3D-Dynamic MRI: Initial Results

    Energy Technology Data Exchange (ETDEWEB)

    Plathow, Christian; Schoebinger, Max; Meinzer, Heinz Peter [German Cancer Research Center, Heidelberg (Germany); Herth, Felix; Tuengerthal, Siegfried [Clinic of Thoracic Disease, Heidelberg (Germany); Kauczor, Hans Ulrich [University of Heidelberg, Heidelberg (Germany)

    2009-12-15

    To estimate a new technique for quantifying regional lung motion using 3D-MRI in healthy volunteers and to apply the technique in patients with intra- or extrapulmonary tumors. Intraparenchymal lung motion during a whole breathing cycle was quantified in 30 healthy volunteers using 3D-dynamic MRI (FLASH [fast low angle shot] 3D, TRICKS [time-resolved interpolated contrast kinetics]). Qualitative and quantitative vector color maps and cumulative histograms were performed using an introduced semiautomatic algorithm. An analysis of lung motion was performed and correlated with an established 2D-MRI technique for verification. As a proof of concept, the technique was applied in five patients with non-small cell lung cancer (NSCLC) and 5 patients with malignant pleural mesothelioma (MPM). The correlation between intraparenchymal lung motion of the basal lung parts and the 2D-MRI technique was significant (r = 0.89, p < 0.05). Also, the vector color maps quantitatively illustrated regional lung motion in all healthy volunteers. No differences were observed between both hemithoraces, which was verified by cumulative histograms. The patients with NSCLC showed a local lack of lung motion in the area of the tumor. In the patients with MPM, there was global diminished motion of the tumor bearing hemithorax, which improved significantly after chemotherapy (CHT) (assessed by the 2D- and 3D-techniques) (p < 0.01). Using global spirometry, an improvement could also be shown (vital capacity 2.9 {+-} 0.5 versus 3.4 L {+-} 0.6, FEV1 0.9 {+-} 0.2 versus 1.4 {+-} 0.2 L) after CHT, but this improvement was not significant. A 3D-dynamic MRI is able to quantify intraparenchymal lung motion. Local and global parenchymal pathologies can be precisely located and might be a new tool used to quantify even slight changes in lung motion (e.g. in therapy monitoring, follow-up studies or even benign lung diseases)

  20. Optimizing preprocessing and analysis pipelines for single-subject fMRI. I. Standard temporal motion and physiological noise correction methods.

    Science.gov (United States)

    Churchill, Nathan W; Oder, Anita; Abdi, Hervé; Tam, Fred; Lee, Wayne; Thomas, Christopher; Ween, Jon E; Graham, Simon J; Strother, Stephen C

    2012-03-01

    Subject-specific artifacts caused by head motion and physiological noise are major confounds in BOLD fMRI analyses. However, there is little consensus on the optimal choice of data preprocessing steps to minimize these effects. To evaluate the effects of various preprocessing strategies, we present a framework which comprises a combination of (1) nonparametric testing including reproducibility and prediction metrics of the data-driven NPAIRS framework (Strother et al. [2002]: NeuroImage 15:747-771), and (2) intersubject comparison of SPM effects, using DISTATIS (a three-way version of metric multidimensional scaling (Abdi et al. [2009]: NeuroImage 45:89-95). It is shown that the quality of brain activation maps may be significantly limited by sub-optimal choices of data preprocessing steps (or "pipeline") in a clinical task-design, an fMRI adaptation of the widely used Trail-Making Test. The relative importance of motion correction, physiological noise correction, motion parameter regression, and temporal detrending were examined for fMRI data acquired in young, healthy adults. Analysis performance and the quality of activation maps were evaluated based on Penalized Discriminant Analysis (PDA). The relative importance of different preprocessing steps was assessed by (1) a nonparametric Friedman rank test for fixed sets of preprocessing steps, applied to all subjects; and (2) evaluating pipelines chosen specifically for each subject. Results demonstrate that preprocessing choices have significant, but subject-dependant effects, and that individually-optimized pipelines may significantly improve the reproducibility of fMRI results over fixed pipelines. This was demonstrated by the detection of a significant interaction with motion parameter regression and physiological noise correction, even though the range of subject head motion was small across the group (≪ 1 voxel). Optimizing pipelines on an individual-subject basis also revealed brain activation patterns

  1. A simple probabilistic model of initiation of motion of poorly-sorted granular mixtures subjected to a turbulent flow

    Science.gov (United States)

    Ferreira, Rui M. L.; Ferrer-Boix, Carles; Hassan, Marwan

    2015-04-01

    Initiation of sediment motion is a classic problem of sediment and fluid mechanics that has been studied at wide range of scales. By analysis at channel scale one means the investigation of a reach of a stream, sufficiently large to encompass a large number of sediment grains but sufficiently small not to experience important variations in key hydrodynamic variables. At this scale, and for poorly-sorted hydraulically rough granular beds, existing studies show a wide variation of the value of the critical Shields parameter. Such uncertainty constitutes a problem for engineering studies. To go beyond Shields paradigm for the study of incipient motion at channel scale this problem can be can be cast in probabilistic terms. An empirical probability of entrainment, which will naturally account for size-selective transport, can be calculated at the scale of the bed reach, using a) the probability density functions (PDFs) of the flow velocities {{f}u}(u|{{x}n}) over the bed reach, where u is the flow velocity and xn is the location, b) the PDF of the variability of competent velocities for the entrainment of individual particles, {{f}{{up}}}({{u}p}), where up is the competent velocity, and c) the concept of joint probability of entrainment and grain size. One must first divide the mixture in into several classes M and assign a correspondent frequency p_M. For each class, a conditional PDF of the competent velocity {{f}{{up}}}({{u}p}|M) is obtained, from the PDFs of the parameters that intervene in the model for the entrainment of a single particle: [ {{u}p}/√{g(s-1){{di}}}={{Φ }u}( { {{C}k} },{{{φ}k}},ψ,{{u}p/{di}}{{{ν}(w)}} )) ] where { Ck } is a set of shape parameters that characterize the non-sphericity of the grain, { φk} is a set of angles that describe the orientation of particle axes and its positioning relatively to its neighbours, ψ is the skin friction angle of the particles, {{{u}p}{{d}i}}/{{{ν}(w)}} is a particle Reynolds number, di is the sieving

  2. Dizziness and Motion Sickness

    Science.gov (United States)

    ... Find an ENT Doctor Near You Dizziness and Motion Sickness Dizziness and Motion Sickness Patient Health Information ... other respiratory infections If you are subject to motion sickness: •Do not read while traveling •Avoid sitting ...

  3. Conditions for Lorentz-invariant superluminal information transfer without signaling

    Science.gov (United States)

    Grössing, G.; Fussy, S.; Mesa Pascasio, J.; Schwabl, H.

    2016-03-01

    We understand emergent quantum mechanics in the sense that quantum mechanics describes processes of physical emergence relating an assumed sub-quantum physics to macroscopic boundary conditions. The latter can be shown to entail top-down causation, in addition to usual bottom-up scenarios. With this example it is demonstrated that definitions of “realism” in the literature are simply too restrictive. A prevailing manner to define realism in quantum mechanics is in terms of pre-determination independent of the measurement. With our counter-example, which actually is ubiquitous in emergent, or self-organizing, systems, we argue for realism without pre-determination. We refer to earlier results of our group showing how the guiding equation of the de Broglie-Bohm interpretation can be derived from a theory with classical ingredients only. Essentially, this corresponds to a “quantum mechanics without wave functions” in ordinary 3-space, albeit with nonlocal correlations. This, then, leads to the central question of how to deal with the nonlocality problem in a relativistic setting. We here show that a basic argument discussing the allegedly paradox time ordering of events in EPR-type two-particle experiments falls short of taking into account the contextuality of the experimental setup. Consequently, we then discuss under which circumstances (i.e. physical premises) superluminal information transfer (but not signaling) may be compatible with a Lorentz-invariant theory. Finally, we argue that the impossibility of superluminal signaling - despite the presence of superluminal information transfer - is not the result of some sort of conspiracy (á la “Nature likes to hide”), but the consequence of the impossibility to exactly reproduce in repeated experimental runs a state's preparation, or of the no-cloning theorem, respectively.

  4. The Effect of Dry Needling on Range of Motion of Neck Lateral Flexion in Subjects With Active Trigger Point in Upper Trapezius Muscle

    Directory of Open Access Journals (Sweden)

    Ziaeifar

    2014-12-01

    Full Text Available Background Myofascial trigger point is one of the most common causes of musculoskeletal disorders. Myofascial trigger point in upper trapezius has been reported as a symptom in patients with neck and upper thoracic pain. Objectives The purpose of this study was to investigate the effect of dry needling compared with ischemic pressure on trigger point in upper trapezius muscle. Materials and Methods 28 subjects with myofascial trigger point in upper trapezius participated in this study. The subjects were randomly assigned to two groups: dry needling (n = 13 and ischemic pressure (n = 15. The neck lateral flexion range of motion was measured before and after treatment in both groups using a standard goniometer. Paired t-test was used to determine any significant difference in range of motion after treatment sessions compared with pre-treatment score in control and experimental group. Analysis of Covariance (ANCOVA was calculated to determine the significance of differences between the control and experimental groups in post-test scores, with pre-treatment scores used as covariates in the analysis. Results Statistical analysis (paired t-test revealed significant increase in neck lateral flexion range of motion in contra-lateral side after treatment sessions in control and experimental group compared with pre-treatment score (P < 0.05. However, only dry needling was effective in increase of range of motion in Ipsi-lateral side (P = 0.001. In the ANCOVA, controlling for pre-test scores, no significant difference was found between the two groups in the after treatment sessions (P = 0.06 and (P = 0.15. Conclusions The application of DN produces an improvement in ILF and CLF can be prescribed for subjects with MTP in UT muscles.

  5. Superluminal propagation of evanescent modes as a quantum effect

    Energy Technology Data Exchange (ETDEWEB)

    Xion, C.D. [School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); He, B. [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, NY 10021 (United States); Wang, Z.Y.

    2008-05-15

    Contrary to mechanical waves, the two-slit interference experiment of single photons shows that the behavior of classical electromagnetic waves corresponds to the quantum mechanical one of single photons, which is also different from the quantum-field-theory behavior such as the creations and annihilations of photons, the vacuum fluctuations, etc. Owing to a purely quantum effect, quantum tunneling particles including tunneling photons (evanescent modes) can propagate over a spacelike interval. With this picture we conclude that the superluminality of evanescent modes is a quantum mechanical rather than a classical phenomenon. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  6. A GPU-based framework for modeling real-time 3D lung tumor conformal dosimetry with subject-specific lung tumor motion

    Energy Technology Data Exchange (ETDEWEB)

    Min Yugang; Santhanam, Anand; Ruddy, Bari H [University of Central Florida, FL (United States); Neelakkantan, Harini; Meeks, Sanford L [M D Anderson Cancer Center Orlando, FL (United States); Kupelian, Patrick A, E-mail: anand.santhanam@orlandohealth.co [Department of Radiation Oncology, University of California, Los Angeles, CA (United States)

    2010-09-07

    In this paper, we present a graphics processing unit (GPU)-based simulation framework to calculate the delivered dose to a 3D moving lung tumor and its surrounding normal tissues, which are undergoing subject-specific lung deformations. The GPU-based simulation framework models the motion of the 3D volumetric lung tumor and its surrounding tissues, simulates the dose delivery using the dose extracted from a treatment plan using Pinnacle Treatment Planning System, Phillips, for one of the 3DCTs of the 4DCT and predicts the amount and location of radiation doses deposited inside the lung. The 4DCT lung datasets were registered with each other using a modified optical flow algorithm. The motion of the tumor and the motion of the surrounding tissues were simulated by measuring the changes in lung volume during the radiotherapy treatment using spirometry. The real-time dose delivered to the tumor for each beam is generated by summing the dose delivered to the target volume at each increase in lung volume during the beam delivery time period. The simulation results showed the real-time capability of the framework at 20 discrete tumor motion steps per breath, which is higher than the number of 4DCT steps (approximately 12) reconstructed during multiple breathing cycles.

  7. Superluminal propagation of pulsed pseudo-thermal light in atomic vapor.

    Science.gov (United States)

    Bae, In-Ho; Cho, Young-Wook; Lee, Hee Jung; Kim, Yoon-Ho; Moon, Han Seb

    2010-09-13

    We report an experimental demonstration of slow and superluminal propagation of pseudo-thermal (chaotic) light in the Λ-type system of the 5S(1/2)-5P(1/2) transition of (87)Rb atom. The slowed propagation of pulsed pseudo-thermal light was demonstrated in an electromagnetically-induced transparency medium while the superluminal propagation was demonstrated with the enhanced absorption scheme where the coupling field takes the form of a standing wave.We have also demonstrated that the photon number statistics of the pseudo-thermal light is preserved for both the subluminal and superluminal cases.

  8. Design of a superluminal ring laser gyroscope using multilayer optical coatings with huge group delay.

    Science.gov (United States)

    Qu, Tianliang; Yang, Kaiyong; Han, Xiang; Wu, Suyong; Huang, Yun; Luo, Hui

    2014-11-18

    We propose and analyze a superluminal ring laser gyroscope (RLG) using multilayer optical coatings with huge group delay (GD). This GD assisted superluminal RLG can measure the absolute rotation with a giant sensitivity-enhancement factor of ~10(3); while, the broadband FWHM of the enhancement factor can reach 20 MHz. This superluminal RLG is based on a traditional RLG with minimal re-engineering, and beneficial for miniaturization according to theoretical calculation. The idea of using GD coatings as a fast-light medium will shed lights on the design and application of fast-light sensors.

  9. Superluminal two-color light in a multiple Raman gain medium

    KAUST Repository

    Kudriašov, V.

    2014-09-17

    We investigate theoretically the formation of two-component light with superluminal group velocity in a medium controlled by four Raman pump fields. In such an optical scheme only a particular combination of the probe fields is coupled to the matter and exhibits superluminal propagation; the orthogonal combination is uncoupled. The individual probe fields do not have a definite group velocity in the medium. Calculations demonstrate that this superluminal component experiences an envelope advancement in the medium with respect to the propagation in vacuum.

  10. Evaluation of a motion artifacts removal approach on breath-hold cine-magnetic resonance images of hypertrophic cardiomyopathy subjects

    Science.gov (United States)

    Betancur, Julián.; Simon, Antoine; Schnell, Frédéric; Donal, Erwan; Hernández, Alfredo; Garreau, Mireille

    2013-11-01

    The acquisition of ECG-gated cine magnetic resonance images of the heart is routinely performed in apnea in order to suppress the motion artifacts caused by breathing. However, many factors including the 2D nature of the acquisition and the use of di erent beats to acquire the multiple-view cine images, cause this kind of artifacts to appear. This paper presents the qualitative evaluation of a method aiming to remove motion artifacts in multipleview cine images acquired on patients with hypertrophic cardiomyopathy diagnosis. The approach uses iconic registration to reduce for in-plane artifacts in long-axis-view image stacks and in-plane and out-of-plane motion artifacts in sort-axis-view image stack. Four similarity measures were evaluated: the normalized correlation, the normalized mutual information, the sum of absolute voxel di erences and the Slomka metric proposed by Slomka et al. The qualitative evaluation assessed the misalignment of di erent anatomical structures of the left ventricle as follows: the misalignment of the interventricular septum and the lateral wall for short-axis-view acquisitions and the misalignment between the short-axis-view image and long-axis-view images. Results showed the correction using the normalized correlation as the most appropriated with an 80% of success.

  11. Superluminal light attenuated by strong dispersion of complex refractive index

    Science.gov (United States)

    Abdurahman, Ahmed Yonis; Vadim Nickolaevich, Mal'nev; Belayneh Mesfin, Ali

    2016-02-01

    The propagation of narrow packets of electromagnetic waves (EMWs) in frequency dispersive medium with the consideration of the complex refractive index is studied. It is shown that counting in the dispersion of the complex refractive index within the context of the conventional expression of the group velocity of narrow wave packets of EMWs propagating in a dispersive medium results in the appearance of additional constraints on the group velocity, which dictates that the physically acceptable group velocity can only be realized in the case of a negligible imaginary part of the group index. In this paper, the conditions that allow one to realize the physically acceptable group velocity are formulated and analyzed numerically for the relevant model of the refractive index of a system of two-level atoms in the optical frequency range. It is shown that in the frequency band where superluminal light propagation is expected, there is a strong dispersion of the refractive index that is accompanied with strong absorption, resulting in a strongly attenuated superluminal light.

  12. Refraction angles and transmission rates of polarized superluminal radiation

    Energy Technology Data Exchange (ETDEWEB)

    Tomaschitz, Roman, E-mail: tom@geminga.or [Department of Physics, Hiroshima University, 1-3-1 Kagami-yama, Higashi-Hiroshima 739-8526 (Japan)

    2009-05-01

    The propagation of superluminal waves in dispersive media is investigated, in particular the refraction at surfaces of discontinuity in layered dielectrics. The negative mass-square of the tachyonic modes is manifested in the transmission and reflection coefficients, and the polarization of the incident waves (TE, TM, or longitudinal) can be determined from the refraction angles. The conditions for total internal reflection in terms of polarization and tachyon mass are derived. Brewster angles can be used to discriminate longitudinal from transversal incidence. Superluminal transmission through dielectric boundary layers is studied, and the dependence of the intensity maxima on the transversal and longitudinal refractive indices of the layer is analyzed. Estimates of the tachyonic plasma frequency and permittivity of metals are given. The integral version of the tachyonic Maxwell equations is stated, boundary conditions at the surfaces of discontinuity are derived for transversal and longitudinal wave propagation, and singular surface fields and currents are pointed out. The spectral maps of three TeV gamma-ray sources associated with supernova remnants, which have recently been obtained with imaging atmospheric Cherenkov detectors, are fitted with tachyonic cascade spectra. The transversal and longitudinal polarization components are disentangled in the spectral maps, and the thermodynamic parameters of the shock-heated ultra-relativistic electron plasma generating the tachyon flux are extracted from the cascade fits.

  13. Comparison of Physical Therapy with Energy Healing for Improving Range of Motion in Subjects with Restricted Shoulder Mobility

    Science.gov (United States)

    Linda Baldwin, Ann; Schwartz, Gary E.

    2013-01-01

    Two forms of energy healing, Reconnective Healing (RH) and Reiki, which involve light or no touch, were tested for efficacy against physical therapy (PT) for increasing limited range of motion (ROM) of arm elevation in the scapular plane. Participants were assigned to one of 5 groups: PT, Reiki, RH, Sham Healing, or no treatment. Except for no treatment, participants were blinded as to grouping. Range of Motion, self-reported pain, and heart rate variability (HRV) were assessed before and after a 10-minute session. On average, for PT, Reiki, RH, Sham Healing, and no treatment, respectively, ROM increased by 12°, 20°, 26°, 0.6°, and 3° and pain score decreased by 11.5%, 10.1%, 23.9%, 15.4%, and 0%. Physical therapy, Reiki, and RH were more effective than Sham Healing for increasing ROM (PT: F = 8.05, P = 0.008; Reiki: F = 10.48, P = 0.003; RH: F = 30.19, P Reiki, and RH. It is the authors' opinion that the accompanying pain relief is a placebo effect. PMID:24327820

  14. Comparison of Physical Therapy with Energy Healing for Improving Range of Motion in Subjects with Restricted Shoulder Mobility

    Directory of Open Access Journals (Sweden)

    Ann Linda Baldwin

    2013-01-01

    Full Text Available Two forms of energy healing, Reconnective Healing (RH and Reiki, which involve light or no touch, were tested for efficacy against physical therapy (PT for increasing limited range of motion (ROM of arm elevation in the scapular plane. Participants were assigned to one of 5 groups: PT, Reiki, RH, Sham Healing, or no treatment. Except for no treatment, participants were blinded as to grouping. Range of Motion, self-reported pain, and heart rate variability (HRV were assessed before and after a 10-minute session. On average, for PT, Reiki, RH, Sham Healing, and no treatment, respectively, ROM increased by 12°, 20°, 26°, 0.6°, and 3° and pain score decreased by 11.5%, 10.1%, 23.9%, 15.4%, and 0%. Physical therapy, Reiki, and RH were more effective than Sham Healing for increasing ROM (PT: , ; Reiki: , ; RH: , . It is possible that this improvement was not mediated by myofascial release because the subjects’ HRV did not change, suggesting no significant increase in vagal activity. Sham treatment significantly reduced pain compared to no treatment (, and was just as effective as PT, Reiki, and RH. It is the authors’ opinion that the accompanying pain relief is a placebo effect.

  15. Superluminal Kinematics in the Milne Universe Causality in the Cosmic Time Order

    CERN Document Server

    Tomaschitz, R

    2000-01-01

    The causality of superluminal signal transfer in the galaxy background is scrutinized. The cosmic time of the comoving galaxy frame determines a distinguished time order for events connected by superluminal signals. Every observer can relate his rest frame to the galaxy frame, and compare so the time order of events in his proper time to the cosmic time order. In this way all observers arrive at identical conclusions on the causality of events connected by superluminal signals. The energy of tachyons (superluminal particles) is defined in the comoving galaxy frame analogous to the energy of subluminal particles. It is positive in the galaxy frame and bounded from below in the rest frames of geodesically moving observers, so that particle-tachyon interactions can be based on energy-momentum conservation. We study tachyons in a Robertson-Walker cosmology with linear expansion factor and open, negatively curved 3-space (Milne universe). This cosmology admits globally geodesic rest frames for uniformly moving obs...

  16. Ultra-slow and superluminal light propagation in solids at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Bigelow, M S; Lepeshkin, N N; Boyd, R W [Institute of Optics, University of Rochester, Rochester, NY 14627 (United States)

    2004-11-24

    Slow and superluminal group velocities can be observed in any material that has large normal or anomalous dispersion. While this fact has been known for more than a century, recent experiments have shown that the dispersion can be very large without dramatically deforming a pulse. As a result, the significance and nature of pulse velocity is being reevaluated. In this review, we discuss some of the current techniques used for generating ultra-slow, superluminal, and even stopped light. While ultra-slow and superluminal group velocities have been observed in complicated systems, from an applications point of view it is highly desirable to do have this done in a solid that can operate at room temperature. We describe how coherent population oscillations can produce ultra-slow and superluminal light under these conditions. (topical review)

  17. ?erenkov-based radiation from superluminal excitation in microdroplets by ultrashort pulses.

    Science.gov (United States)

    Brunel, M; Mess, L; Gouesbet, G; Gréhan, G

    2001-10-15

    We demonstrate from a generalized Lorenz-Mie theory that ultrashort pulses can induce superluminal excitation in microdroplets. A ?erenkov-like effect can thus be expected for sufficiently intense ultrashort pulses.

  18. Measurements of entanglement over a kilometric distance to test superluminal models of Quantum Mechanics: preliminary results.

    Science.gov (United States)

    Cocciaro, B.; Faetti, S.; Fronzoni, L.

    2017-08-01

    As shown in the EPR paper (Einstein, Podolsky e Rosen, 1935), Quantum Mechanics is a non-local Theory. The Bell theorem and the successive experiments ruled out the possibility of explaining quantum correlations using only local hidden variables models. Some authors suggested that quantum correlations could be due to superluminal communications that propagate isotropically with velocity vt > c in a preferred reference frame. For finite values of vt and in some special cases, Quantum Mechanics and superluminal models lead to different predictions. So far, no deviations from the predictions of Quantum Mechanics have been detected and only lower bounds for the superluminal velocities vt have been established. Here we describe a new experiment that increases the maximum detectable superluminal velocities and we give some preliminary results.

  19. Neutrino superluminality without Cherenkov-like processes in Finslerian special relativity

    Science.gov (United States)

    Chang, Zhe; Li, Xin; Wang, Sai

    2012-04-01

    Recently, Cohen and Glashow [A.G. Cohen, S.L. Glashow, Phys. Rev. Lett. 107 (2011) 181803] pointed out that the superluminal neutrinos reported by the OPERA would lose their energy rapidly via the Cherenkov-like process. The Cherenkov-like process for the superluminal particles would be forbidden if the principle of special relativity holds in any frame instead violated with a preferred frame. We have proposed that the Finslerian special relativity could account for the data of the neutrino superluminality (arxiv:arXiv:1110.6673 [hep-ph]). The Finslerian special relativity preserves the principle of special relativity and involves a preferred direction while consists with the causality. In this Letter, we prove that the energy-momentum conservation is preserved and the energy-momentum is well defined in Finslerian special relativity. The Cherenkov-like process is forbidden in the Finslerian special relativity. Thus, the superluminal neutrinos would not lose energy in their distant propagation.

  20. A comparison of lumbopelvic motion patterns and erector spinae behavior between asymptomatic subjects and patients with recurrent low back pain during pain-free periods.

    Science.gov (United States)

    Sánchez-Zuriaga, Daniel; López-Pascual, Juan; Garrido-Jaén, David; García-Mas, Maria Amparo

    2015-02-01

    The purpose of this study was to determine the patterns of lumbopelvic motion and erector spinae (ES) activity during trunk flexion-extension movements and to compare these patterns between patients with recurrent low back pain (LBP) in their pain-free periods and matched asymptomatic subjects. Thirty subjects participated (15 patients with disc herniation and recurrent LBP in their pain-free periods and 15 asymptomatic control subjects). A 3-dimensional videophotogrammetric system and surface electromyography (EMG) were used to record the angular displacements of the lumbar spine and hip in the sagittal plane and the EMG activity of the ES during standardized trunk flexion-extension cycles. Variables were maximum ranges of spine and hip flexion; percentages of maximum lumbar and hip flexion at the start and end of ES relaxation; average percentages of EMG activity during flexion, relaxation, and extension; and flexion-extension ratio of myoelectrical activity. Recurrent LBP patients during their pain-free period showed significantly greater ES activation both in flexion and extension, with a higher flexion-extension ratio than controls. Maximum ranges of lumbar and hip flexion showed no differences between controls and patients, although patients spent less time with their lumbar spine maximally flexed. This study showed that reduced maximum ranges of motion and absence of ES flexion-relaxation phenomenon were not useful to identify LBP patients in the absence of acute pain. However, these patients showed subtle alterations of their lumbopelvic motion and ES activity patterns, which may have important clinical implications. Copyright © 2015 National University of Health Sciences. Published by Elsevier Inc. All rights reserved.

  1. Superluminal solutions to the Klein-Gordon equation and a causality problem

    Energy Technology Data Exchange (ETDEWEB)

    Borghardt, A.A.; Belogolovskii, M.A.; Karpenko, D.Ya

    2003-11-17

    We present a new axially symmetric monochromatic free-space solution to the Klein-Gordon equation propagating with a superluminal group velocity and show that it gives rise to an imaginary part of the causal propagator outside the light cone. We address the question about causality of the spacelike paths and argue that the signal with a well-defined wavefront formed by the superluminal modes would propagate in vacuum with the light speed.

  2. Subluminal and superluminal propagation of light in an N-type medium

    Energy Technology Data Exchange (ETDEWEB)

    Han Dingan [CREAM Group, Laboratory of Light Transmission Optics, South China Normal University, Guangzhou 510631 (China) and CREAM Group, Key Laboratory for Quantum Information and Measurements of Ministry of Education, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China)]. E-mail: handingan@163.com; Guo Hong [CREAM Group, Laboratory of Light Transmission Optics, South China Normal University, Guangzhou 510631 (China) and CREAM Group, Key Laboratory for Quantum Information and Measurements of Ministry of Education, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China)]. E-mail: hongguo@pku.edu.cn; Bai Yanfeng [CREAM Group, Laboratory of Light Transmission Optics, South China Normal University, Guangzhou 510631 (China); CREAM Group, Key Laboratory for Quantum Information and Measurements of Ministry of Education, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China); Sun Hui [CREAM Group, Laboratory of Light Transmission Optics, South China Normal University, Guangzhou 510631 (China)

    2005-01-10

    For a three-level electromagnetically induced transparency (EIT) atomic system, we show that, adding a third driving field coupled to a fourth state, the properties of the weak probe light propagation are greatly changed. Due to the increase of the driving field, when the driving and the coupling detunings are zero, the light propagation can be changed from subluminal to superluminal. Also, the analytical solution exhibiting superluminal group velocity is given at the zero probe detuning.

  3. Practical Considerations on the Multi-layer Mirrors for Superluminal Ring Laser Gyroscopes

    Science.gov (United States)

    Wang, Zhiguo; Yuan, Baolun

    2015-07-01

    We have created a simple model to analyze the restrictions on superluminal ring laser gyroscopes arising from the absorption of coating materials. For a ring laser gyroscope with a cavity length of 15 cm, the scale factor enhancement is nearly impossible due to absorption from the high dispersion mirror. In order to obtain a practical superluminal ring laser gyroscope, the extinction coefficient of coating materials should be less than 1E-10, which is a challenge at present.

  4. Absorption-Free Sub- and Super-Luminal Light Propagation via Quantum Interference

    Science.gov (United States)

    Wu, Jian-Chun; Liu, Zheng-Dong; Zheng, Jun

    2012-10-01

    We investigate the dispersive and absorptive properties of an N-type four-level atomic system in three coherent fields, and consider the susceptibility mathematically. It is shown that the group velocity of the probe field exhibits sub- and super-luminal under some conditions, meanwhile the absorption coefficient keeps zero during the occurrence and transition process of sub- and super-luminal pulses.

  5. Constraints and tests of the OPERA superluminal neutrinos.

    Science.gov (United States)

    Bi, Xiao-Jun; Yin, Peng-Fei; Yu, Zhao-Huan; Yuan, Qiang

    2011-12-09

    The superluminal neutrinos detected by OPERA indicate Lorentz invariance violation (LIV) of the neutrino sector at the order of 10(-5). We study the implications of the result in this work. We find that such a large LIV implied by OPERA data will make the neutrino production process π → μ + ν(μ) kinematically forbidden for a neutrino energy greater than about 5 GeV. The OPERA detection of neutrinos at 40 GeV can constrain the LIV parameter to be smaller than 3×10(-7). Furthermore, the neutrino decay in the LIV framework will modify the neutrino spectrum greatly. The atmospheric neutrino spectrum measured by the IceCube Collaboration can constrain the LIV parameter to the level of 10(-12). The future detection of astrophysical neutrinos of galactic sources is expected to be able to give an even stronger constraint on the LIV parameter of neutrinos.

  6. Superluminal blazars and the extragalactic gamma ray background

    Energy Technology Data Exchange (ETDEWEB)

    Xinyu Chi; Young, Enoch C.M. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    1997-07-01

    The detection of a few dozen extragalactic gamma ray blazars of extremely high luminosity by the EGRET instrument on board the Compton Gamma Ray Observatory appears to suggest that blazars make the overwhelming contribution to the cosmic gamma ray background in the energy range 100 MeV - 10 GeV. In this paper we point out that the superluminal effect which boosts and beams the gamma ray emission in the jets of blazars will flatten the source count in the low flux part. Consequently, the unresolved blazars would not be expected to make much contribution to the gamma ray background. From our direct modelling of the source count, we conclude that the contribution of the unresolved blazars to the gamma ray background is only 10% of the latest estimate of the EGRET data. The implication for the cosmological evolution of the blazars is discussed. (author)

  7. Superluminal and slow light in eye-like ring resonator

    Science.gov (United States)

    Zhang, Yundong; Ma, Kai; Wu, Yongfeng; Su, Huaiyin; Li, Hui; Yuan, Ping

    2017-02-01

    We investigate the phase and group delay in eye-like ring resonator with the effect of different coupling coefficients and attenuation factors. The eye-like structure is composed of two bus waveguides coupling with the outer ring and the two rings coupling together which have the same perimeters. The eye-like ring resonator has two outputs which have different transmission characteristics. In this paper, we measure the group delay of the two outputs through changing the coupling coefficients and the attenuation factors of the inner and the outer ring. The result shows that the two outputs have reverse group delay (superluminal and slow light) which will have potential use in slow light fiber, optical buffers and optical switches.

  8. Superluminal neutrinos at OPERA confront pion decay kinematics.

    Science.gov (United States)

    Cowsik, Ramanath; Nussinov, Shmuel; Sarkar, Utpal

    2011-12-16

    Violation of Lorentz invariance (VLI) has been suggested as an explanation of the superluminal velocities of muon neutrinos reported by OPERA. In this Letter, we show that the amount of VLI required to explain this result poses severe difficulties with the kinematics of the pion decay, extending its lifetime and reducing the momentum carried away by the neutrinos. We show that the OPERA experiment limits α=(ν(ν)-c)/c<4×10(-6). We then take recourse to cosmic-ray data on the spectrum of muons and neutrinos generated in Earth's atmosphere to provide a stronger bound on VLI: (ν-c)/c<10(-12). © 2011 American Physical Society

  9. MERLIN observations of the unusual superluminal quasar 3C395

    Energy Technology Data Exchange (ETDEWEB)

    Saikia, D.J. (Nuffield Radio Astronomy Labs., Jodrell Bank (UK) Tata Inst. of Fundamental Research, Poona Univ. Campus, Pune (India)); Muxlow, T.W.B. (Nuffield Radio Astronomy Labs., Jodrell Bank (UK)); Junor, W. (National Radio Astronomy Observatory, Socorro, NM (USA))

    1990-08-01

    We present MERLIN observations at 73, 18 and 6 cm of the quasar 3C395 (1901 + 319) which has a superluminal component moving towards a stationary knot located at a distance of 15.8 mas from the VLBI core. The observations help to clarify the radiostructure of 3C395 on scales ranging from a few tens to a few hundreds of milliarcsec. They show evidence of a highly curved jet-like structure extending beyond the stationary VLBI component. The radio images of 3C395 are consistent with a two-sided structure inclined at a small angle to the line-of-sight, with the approaching jet being decelerated and distorted within {approx} 15 mas of the nucleus. (author).

  10. Superluminal light propagation via quantum interference in decay channels

    Science.gov (United States)

    Arun, R.

    2016-10-01

    We examine the propagation of a weak probe light through a coherently driven Y -type system. Under the condition that the excited atomic levels decay via the same vacuum modes, the effects of quantum interference in decay channels are considered. It is found that the interference in decay channels results in a lossless anomalous dispersion between two gain peaks. We demonstrate that the probe pulse propagation can, in principle, be switched from subluminal to superluminal due to the decay-induced interference. We also show that the system exhibits a high index of refraction with negligible absorption for the driving fields. A dressed-state picture of the atom-light interaction is described to explain the numerical results.

  11. PROPAGATION AND STABILITY OF SUPERLUMINAL WAVES IN PULSAR WINDS

    Energy Technology Data Exchange (ETDEWEB)

    Mochol, Iwona; Kirk, John G., E-mail: iwona.mochol@mpi-hd.mpg.de, E-mail: john.kirk@mpi-hd.mpg.de [Max-Planck-Institut fuer Kernphysik, Postfach 10 39 80, D-69029 Heidelberg (Germany)

    2013-07-01

    Nonlinear electromagnetic waves with superluminal phase velocity can propagate in the winds around isolated pulsars, and around some pulsars in binary systems. Using a short-wavelength approximation, we find and analyze an integrable system of equations that govern their evolution in spherical geometry. A confined mode is identified that stagnates to finite pressure at large radius and can form a precursor to the termination shock. Using a simplified criterion, we find this mode is stable for most isolated pulsars, but may be unstable if the external pressure is high, such as in the pulsar wind nebulae in starburst galaxies and in W44. Pulsar winds in eccentric binary systems, such as PSR 1259-63, may go through phases with stable and unstable electromagnetic precursors, as well as phases in which the density is too high for these modes to propagate.

  12. Quark Nova Signatures in Super-luminous Supernovae

    Science.gov (United States)

    Kostka, M.; Koning, N.; Leahy, D.; Ouyed, R.; Steffen, W.

    2014-10-01

    Recent observational surveys have uncovered the existence of super-luminous supernovae (SLSNe). In this work we study the light curves of eight SLSNe in the context of dual-shock quark novae. We find that progenitor stars in the range of 25 - 35 M⊙ provide ample energy to power each light curve. An examination into the effects of varying the physical properties of a dual-shock quark nova on light curve composition is undertaken. We conclude that the wide variety of SLSN light curve morphologies can be explained predominantly by variations in the length of time between supernova and quark nova. Our analysis shows that a singular H alpha spectral profile found in three SLSNe can be naturally described in the dual-shock quark nova scenario. Predictions of spectral signatures unique to the dual-shock quark nova are presented.

  13. Radiation Hydrodynamical Models for Type I Superluminous Supernovae

    Science.gov (United States)

    Nomoto, Ken'ichi; Sorokina, Elena; Blinnikov, Sergei; Tolstov, Alexey; Bersten, Melina; Quimby, Robert

    The physical origin of Type I superluminous supernovae (SLSNe-I), whose luminosities are 10 to 100 times brighter than normal core-collapse supernovae, remains still unknown. Radioactive-decays, magnetars, and circumstellar interactions have been proposed for the power source the light curves, although no definitive conclusions have been reached yet. Since most of light curve studies have been based on simplified semi-analytic models, we have constructed detailed light curve models for various mass of stars including very massive ones and large amount of mass loss with radiation hydrodynamical calculations. Here we focus on the magnetar and circumstellar interaction models and compare their rising time, peak luminosity, width, decline rate of the light curves with observations which show quite a large diversities. We then discuss how to discriminate these models, relevant models parameters, their evolutionary origins, possible roles of chemical enrichment of the early universe, and implications for the identifications of first stars.

  14. Cosmic evolution and metal aversion in superluminous supernova host galaxies

    Science.gov (United States)

    Schulze, S.; Krühler, T.; Leloudas, G.; Gorosabel, J.; Mehner, A.; Buchner, J.; Kim, S.; Ibar, E.; Amorín, R.; Herrero-Illana, R.; Anderson, J. P.; Bauer, F. E.; Christensen, L.; de Pasquale, M.; de Ugarte Postigo, A.; Gallazzi, A.; Hjorth, J.; Morrell, N.; Malesani, D.; Sparre, M.; Stalder, B.; Stark, A. A.; Thöne, C. C.; Wheeler, J. C.

    2018-01-01

    The SUperluminous Supernova Host galaxIES survey aims to provide strong new constraints on the progenitors of superluminous supernovae (SLSNe) by understanding the relationship to their host galaxies. We present the photometric properties of 53 H-poor and 16 H-rich SLSN host galaxies out to z ∼ 4. We model their spectral energy distributions to derive physical properties, which we compare with other galaxy populations. At low redshift, H-poor SLSNe are preferentially found in very blue, low-mass galaxies with high average specific star formation rates. As redshift increases, the host population follows the general evolution of star-forming galaxies towards more luminous galaxies. After accounting for secular evolution, we find evidence for differential evolution in galaxy mass, but not in the B band and the far-ultraviolet luminosity (3σ confidence). Most remarkable is the scarcity of hosts with stellar masses above 1010 M⊙ for both classes of SLSNe. In case of H-poor SLSNe, we attribute this to a stifled production efficiency above ∼0.4 solar metallicity. However, we argue that, in addition to low metallicity, a short-lived stellar population is also required to regulate the SLSN production. H-rich SLSNe are found in a very diverse population of star-forming galaxies. Still, the scarcity of massive hosts suggests a stifled production efficiency above ∼0.8 solar metallicity. The large dispersion of the H-rich SLSNe host properties is in stark contrast to those of gamma-ray burst, regular core-collapse SN, and H-poor SLSNe host galaxies. We propose that multiple progenitor channels give rise to this subclass.

  15. Inverse Compton X-ray emission from the superluminal quasar 3C 345

    Science.gov (United States)

    Unwin, S. C.; Wehrle, A. E.; Urry, C. M.; Gilmore, D. M.; Barton, E. J.; Kjerulf, B. C.; Zensus, J. A.; Rabaca, C. R.

    1994-01-01

    In quasars with strong radio cores, the inverse-Compton process is believed to be the dominant source X-ray emission. For objects with parsec-scale radio jets, simple models have predicted that components in the jet emerging from the quasar nucleus generate the observed X-ray emission. We have tested this hypothesis in detail for the quasar 3C 345 using a ROSAT X-ray observation in 1990 July, together with quasi-simultaneous very long base interferometry (VLBI) imaging of the parsec-scale jet at five frequencies. The ROSAT spectrum is well fitted by a power law with index alpha = -0.96 +/- -0.13, consistent with models in which the X-ray emission results from inverse-Compton scattering of radio radiation from high-energy electrons in compact components. We show that the radio properties of brightest `knot' in the jet (`C5') can be fitted with a homogeneous sphere model whose parameters require bulk relativistic motion of the emitting material; otherwise the predicted model whose parameters require bulk relativistic motion of the emitting material; otherwise the predicted inverse-Compton X-ray emission exceeds the observed flux. If C5 is the origin of the X-ray emission, then it has a Doppler factor delta = 7.5((sup +3 sub -2)). If the nucleus or other components contribute to the X-ray emission, then this becomes a firm lower limit to delta. The inhomogeneous jet model of Koenigl is a good fit both to the barely resolved (less than 1 pc) flat-spectrum nucleus in the radio, and also to the ROSAT X-ray spectrum. The synchrotron and inverse-Compton emitting fluid moves down a narrow cone (opening angle 2 phi approximately 5 deg) nucleus relativistically, with delta approximately 4.6. Doppler factors for the nucleus and C5, derived from our ROSAT observation, provide evidence for bulk relativistic motion in the jet. By combining these constraints with well-known superluminal motion of jet components, we can deduce geometry. For epoch 1990.5 we infer the Lorentz factor

  16. Cervical flexion-rotation test and physiological range of motion - A comparative study of patients with myogenic temporomandibular disorder versus healthy subjects.

    Science.gov (United States)

    Greenbaum, Tzvika; Dvir, Zeevi; Reiter, Shoshana; Winocur, Ephraim

    2017-02-01

    Temporomandibular Disorders (TMD) refer to several common clinical disorders which involve the masticatory muscles, the temporomandibular joint (TMJ) and the adjacent structures. Although neck signs and symptoms are found with higher prevalence in TMD patients compared to the overall population, whether limitation of cervical mobility is an additional positive finding in this cohort is still an open question. To compare the physiological cervical range of motion (CROM) and the extent of rotation during cervical flexion (flexion-rotation test, FRT) in people with TMD (muscular origin) and healthy control subjects. The range of motion of the neck and FRT was measured in 20 women with myogenic TMD and 20 age matched healthy controls. Women with myogenic TMD had significantly lower FRT scores compared to their matched healthy women. No difference was found between groups in CROM in any of the planes of movement. The FRT was positive (less than 32°) in 90% of the TMD participants versus 5% in the healthy control but the findings were not correlated with TMD severity. The results point out a potential involvement of the upper cervical joints (c1-c2) in women with myogenic TMD. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Gain-assisted superluminal propagation and rotary drag of photon and surface plasmon polaritons

    Science.gov (United States)

    Khan, Naveed; Amin Bacha, Bakht; Iqbal, Azmat; Ur Rahman, Amin; Afaq, A.

    2017-07-01

    Superluminal propagation of light is a well-established phenomenon and has motivated immense research interest that has led to state-of-the-art knowledge and potential applications in the emerging technology of quantum optics and photonics. This study presents a theoretical analysis of the gain-assisted superluminal light propagation in a four-level N -type atomic system by exploiting the scheme of electromagnetically induced gain and superluminal propagation of surface plasmon polaritons (SPPs) along the gain-assisted atomic-metal interface simultaneously. In addition, a theoretical demonstration is presented on the comparison between Fresnel's rotary photon drag and SPP drag in view of light polarization state rotation by rotating the coherent atomic medium and the atomic-metal interface, respectively. Analogous to photon drag in the superluminal anomalous dispersion region where light polarization rotation occurs opposite the rotation of the gain-assisted atomic medium, the rotation of the atomic-metal interface also rotates the polarization state of SPPs opposite the rotation of the interface. This further confirms the superluminal nature of SPPs propagating along the interface with negative group velocity. Rabi frequencies of the control and pump fields considerably modify both photon and SPP drag coefficients. Metal conductivity also controls SPP propagation.

  18. Time-resolved Polarimetry of the Superluminous SN 2015bn with the Nordic Optical Telescope

    DEFF Research Database (Denmark)

    Leloudas, Giorgos; Maund, Justyn R.; Gal-Yam, Avishay

    2017-01-01

    We present imaging polarimetry of the superluminous supernova SN 2015bn, obtained over nine epochs between -20 and +46 days with the Nordic Optical Telescope. This was a nearby, slowly evolving Type I superluminous supernova that has been studied extensively and for which two epochs of spectropol......We present imaging polarimetry of the superluminous supernova SN 2015bn, obtained over nine epochs between -20 and +46 days with the Nordic Optical Telescope. This was a nearby, slowly evolving Type I superluminous supernova that has been studied extensively and for which two epochs...... of spectropolarimetry are also available. Based on field stars, we determine the interstellar polarization in the Galaxy to be negligible. The polarization of SN 2015bn shows a statistically significant increase during the last epochs, confirming previous findings. Our well-sampled imaging polarimetry series allows us......, to a more aspherical inner core, dominated by freshly nucleosynthesized material. This two-layered model might account for the characteristic appearance and properties of Type I superluminous supernovae....

  19. Semi-Automated Analysis of Diaphragmatic Motion with Dynamic Magnetic Resonance Imaging in Healthy Controls and Non-Ambulant Subjects with Duchenne Muscular Dystrophy

    Directory of Open Access Journals (Sweden)

    Courtney A. Bishop

    2018-01-01

    Full Text Available Subjects with Duchenne Muscular Dystrophy (DMD suffer from progressive muscle damage leading to diaphragmatic weakness that ultimately requires ventilation. Emerging treatments have generated interest in better characterizing the natural history of respiratory impairment in DMD and responses to therapy. Dynamic (cine Magnetic Resonance Imaging (MRI may provide a more sensitive measure of diaphragm function in DMD than the commonly used spirometry. This study presents an analysis pipeline for measuring parameters of diaphragmatic motion from dynamic MRI and its application to investigate MRI measures of respiratory function in both healthy controls and non-ambulant DMD boys. We scanned 13 non-ambulant DMD boys and 10 age-matched healthy male volunteers at baseline, with a subset (n = 10, 10, 8 of the DMD subjects also assessed 3, 6, and 12 months later. Spirometry-derived metrics including forced vital capacity were recorded. The MRI-derived measures included the lung cross-sectional area (CSA, the anterior, central, and posterior lung lengths in the sagittal imaging plane, and the diaphragm length over the time-course of the dynamic MRI. Regression analyses demonstrated strong linear correlations between lung CSA and the length measures over the respiratory cycle, with a reduction of these correlations in DMD, and diaphragmatic motions that contribute less efficiently to changing lung capacity in DMD. MRI measures of pulmonary function were reduced in DMD, controlling for height differences between the groups: at maximal inhalation, the maximum CSA and the total distance of motion of the diaphragm were 45% and 37% smaller. MRI measures of pulmonary function were correlated with spirometry data and showed relationships with disease progression surrogates of age and months non-ambulatory, suggesting that they provide clinically meaningful information. Changes in the MRI measures over 12 months were consistent with weakening of

  20. Noninvasive detection of coronary artery wall thickening with age in healthy subjects using high resolution MRI with beat-to-beat respiratory motion correction.

    Science.gov (United States)

    Scott, Andrew D; Keegan, Jennifer; Mohiaddin, Raad H; Firmin, David N

    2011-10-01

    To demonstrate coronary artery wall thickening with age in a small healthy cohort using a highly efficient, reliable, and reproducible high-resolution MR technique. A 3D cross-sectional MR vessel wall images (0.7 × 0.7 × 3 mm resolution) with retrospective beat-to-beat respiratory motion correction (B2B-RMC) were obtained in the proximal right coronary artery of 21 healthy subjects (age, 22-62 years) with no known cardiovascular disease. Lumen and outer wall (lumen + vessel wall) areas were measured in one central slice from each subject and average wall thickness and wall area/outer wall area ratio (W/OW) calculated. Imaging was successful in 18 (86%) subjects with average respiratory efficiency 99.3 ± 1.7%. Coronary vessel wall thickness and W/OW significantly correlate with subject age, increasing by 0.088 mm and 0.031 per decade respectively (R = 0.53, P = 0.024 and R = 0.48, P = 0.046). No relationship was found between lumen area and vessel wall thickness (P = NS), but outer wall area increased significantly with vessel wall thickness at 19 mm(2) per mm (P = 0.046). This is consistent with outward vessel wall remodeling. Despite the small size of our healthy cohort, using high-resolution MR imaging and B2B-RMC, we have demonstrated increasing coronary vessel wall thickness and W/OW with age. The results obtained are consistent with outward vessel wall remodeling. Copyright © 2011 Wiley-Liss, Inc.

  1. Transition between superluminal and subluminal light propagation in photorefractive Bi12SiO20 crystals.

    Science.gov (United States)

    Bo, Fang; Zhang, Guoquan; Xu, Jingjun

    2005-10-03

    We demonstrated superluminal light propagation with a negative group velocity of -5.7 m/s in a photorefractive Bi 12SiO20 crystal by using the dispersive phase coupling effect in a nondegenerate two-wave mixing process. To the best of our knowledge, this is the first experimental demonstration of superluminal light propagation at room temperature in solids by using a classical wave mixing technique. In addition, we showed the tunability of the group velocity of light between the negative (superluminal light) and the positive (subluminal light) by simply tuning the experimental conditions such as the frequency of the coupling beam, the incident intensity, and the externally applied electric fields.

  2. Localized X-shaped field generated by a superluminal electric charge.

    Science.gov (United States)

    Recami, Erasmo; Zamboni-Rached, Michel; Dartora, César A

    2004-02-01

    It is now well known that Maxwell equations admit of wavelet-type solutions endowed with arbitrary group velocities (0< v(g)< infinity). Some of them, which are rigidly moving and have been called localized solutions, attracted large attention. In particular, much work has been done with regard to the superluminal localized solutions (SLSs), the most interesting of which are the "X-shaped" ones. The SLSs have been actually produced in a number of experiments, always by suitable interference of ordinary-speed waves. In this paper we show, by contrast, that even a superluminal charge creates an electromagnetic X-shaped wave: namely, on the basis of Maxwell equations, we are able to evaluate the field associated with a superluminal charge (under the approximation of pointlikeness): it results in constituting a very simple example of a true X wave.

  3. Comment on: Gain-assisted superluminal light propagation through a Bose-Einstein condensate cavity system

    Science.gov (United States)

    Macke, Bruno; Ségard, Bernard

    2016-09-01

    In a recent theoretical article [S.H. Kazemi, S. Ghanbari, M. Mahmoudi, Eur. Phys. J. D 70, 1 (2016)], Kazemi et al. claim to have demonstrated superluminal light transmission in an optomechanical system where a Bose-Einstein condensate serves as the mechanical oscillator. In fact the superluminal propagation is only inferred from the existence of a minimum of transmission of the system at the probe frequency. This condition is not sufficient and we show that, in all the cases where superluminal propagation is claimed by Kazemi et al., the propagation is in reality subluminal. Moreover, we point out that the system under consideration is not minimum-phase-shift. The Kramers-Kronig relations then only fix a lower limit to the group delay and we show that these two quantities have sometimes opposite signs.

  4. Subluminal and superluminal pulse propagation in inhomogeneous media of nonspherical particles

    Energy Technology Data Exchange (ETDEWEB)

    Ma Yu [Department of Physics, Suzhou University, Suzhou 215006 (China); Gao Lei [CCAST (World Laboratory), P.O. Box 8730, Beijing 100080 (China) and Department of Physics, Suzhou University, Suzhou 215006 (China)]. E-mail: lgaophys@pub.sz.jsinfo.net

    2006-07-10

    We study the pulse propagation through a metal/dielectric composites of nonspherical particles enclosed by two gold mirrors. To account for the shape effect, we first adopt Maxwell-Garnett type approximation to obtain the effective dielectric function of composites. Based on the group index, phase time and pulse shape calculations, we find that the particles' shape (characterized by the depolarization factor) plays an important role in determining the subluminal and superluminal pulse propagations through the system. When the inclusions' shape is not spherical, it is possible to observe significant superluminal behavior of the pulse propagation, although the volume fraction is the same. The shape-dependent critical volume fraction is predicted, above which superluminal propagation appears. Furthermore, the Hartman effect in such a system is also investigated.

  5. A note on observational signatures in superluminal unified dark matter models

    Energy Technology Data Exchange (ETDEWEB)

    Urakawa, Yuko; Kobayashi, Tsutomu, E-mail: yuko@gravity.phys.waseda.ac.jp, E-mail: tsutomu@gravity.phys.waseda.ac.jp [Department of Physics, Waseda University, Okubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan)

    2010-07-01

    We explore the possibility that the dark matter and dark energy are mimicked by a single fluid or by a single k-essence-like scalar field. The so called Chaplygin gas unified dark matter models can reproduce the observed matter power spectrum by adding a baryon component. It has been argued that the evolution of the baryon fluctuations is particularly favoured for the ''superluminal'' case where the sound speed of the Chaplygin gas exceeds the speed of light at late times, as well as for the models with the negligibly small sound speed. In this note we compute the integrated Sachs-Wolfe signal in the Chaplygin gas models, focusing on the superluminal case which has not been investigated before because of the premature understanding of causality. It is shown that the superluminal model leads to large enhancement of the integrated Sachs-Wolfe effect, which is inconsistent with the CMB measurements.

  6. Inverse Doppler shift and control field as coherence generators for the stability in superluminal light

    Science.gov (United States)

    Ghafoor, Fazal; Bacha, Bakht Amin; Khan, Salman

    2015-05-01

    A gain-based four-level atomic medium for the stability in superluminal light propagation using control field and inverse Doppler shift as coherence generators is studied. In regimes of weak and strong control field, a broadband and multiple controllable transparency windows are, respectively, identified with significantly enhanced group indices. The observed Doppler effect for the class of high atomic velocity of the medium is counterintuitive in comparison to the effect of the class of low atomic velocity. The intensity of each of the two pump fields is kept less than the optimum limit reported in [M. D. Stenner and D. J. Gauthier, Phys. Rev. A 67, 063801 (2003), 10.1103/PhysRevA.67.063801] for stability in the superluminal light pulse. Consequently, superluminal stable domains with the generated coherence are explored.

  7. Interlaminar shear stresses and laminae separation in a disc. Finite element analysis of the L3-L4 motion segment subjected to axial compressive loads.

    Science.gov (United States)

    Goel, V K; Monroe, B T; Gilbertson, L G; Brinckmann, P

    1995-03-15

    This study analyzed interlaminar shear stresses across the laminae of a ligamentous L3-L4 motion segment. A three-dimensional finite element model of the motion segment was developed and its response in axial compression mode was predicted. The contributions of "mechanical" factors in producing laminae separation in a disc are not well understood, especially when the nucleus is still gel-like in appearance (stage 1 of disc degeneration). All types of stresses are likely to contribute to laminae separation. The authors believe it is partially due to the interlaminar shear stresses at the laminae interfaces in specific regions of an intact disc because the disc is a composite structure. The effects of anular tears on the interlaminar shear stresses were also investigated. These tears can be circumferential or radial in nature, and commonly occur in the aged, degenerated disc. A large number of biomechanical studies dealing with the role of the disc vis-a-vis other spinal components have been reported in the literature. The role of mechanical factors, however, in producing laminae separation, especially when the nucleus is still gel-like in appearance (stage 1 of disc degeneration), is not entirely clear. A three-dimensional nonlinear finite element model of an intact L3-L4 lumbar motion segment, based on the use of a special type of element for the disc anulus, was created to investigate the interlaminar shear stresses in the anulus. The effects of radial "out-in," radial "in-out," and "circumferential" injuries were analyzed. Injury was modeled as element removal in the posterolateral portion of the disc. Models subjected to axial compressive loads, ranging from 200 N to 2000 N, were analyzed. In addition to the interlaminar shear stresses, disc bulge, and displacements including coupled motions were predicted. The theoretical disc bulge predictions for the radial in-out injury case were in agreement with the disc bulge data obtained experimentally. Displacements

  8. Revealing the Environmental Dependence in Superluminous Supernovae Diversity

    Science.gov (United States)

    D'Andrea, Chris

    2017-08-01

    Superluminous Supernovae (SLSNe) are a rare, exotic new class of transients, 50 times brighter than classical supernovae, that have only been identified within the past decade. Little is known about the nature of the progenitors of these massive explosions. To date fewer than 100 of these have been discovered, and most have single-band photometry, poor light-curve coverage, and are at low to moderate redshift. The Dark Energy Survey (DES) has spectroscopically-classified 17 SLSNe from 0.2 global star-formation rates (SFRs), and morphology and compactness of the galaxy. These observations will double the existing sample of SLSNe at z>0.5 for which these host-galaxy properties can be determined. We will then use this information to conduct the first systematic study of host-galaxy correlations with SLSN light-curve properties. By tying environmental constraints to observed characteristics of the explosion, this study will get to the heart of the SLSN progenitor question.

  9. The Trails of Superluminal Jet Components in 3C 111

    Science.gov (United States)

    Kadler, M.; Ros, E.; Perucho, M.; Kovalev, Y. Y.; Homan, D. C.; Agudo, I.; Kellermann, K. I.; Aller, M. F.; Aller, H. D.; Lister, M. L.; hide

    2007-01-01

    The parsec-scale radio jet of the broad-line radio galaxy 3C 111 has been monitored since 1995 as part of the 2cm Survey and MOJAVE monitoring observations conducted with the VLBA. Here, we present results from 18 epochs of VLBA observations of 3C 111 and from 18 years of radio flux density monitoring observations conducted at the University of Michigan. A major radio flux-density outburst of 3C 111 occurred in 1996 and was followed by a particularly bright plasma ejection associated with a superluminal jet component. This major event allows us to study a variety of processes associated with outbursts of radio-loud AGN in much greater detail than possible in other cases: the primary perturbation gives rise to the formation of a forward and a backward-shock, which both evolve in characteristically different ways and allow us to draw conclusions about the workflow of jet-production events; the expansion, acceleration and recollimation of the ejected jet plasma in an environment with steep pressure and density gradients are revealed; trailing components are formed in the wake of the primary perturbation as a result of Kelvin- Helmholtz instabilities from the interaction of the jet with the external medium. The jet-medium interaction is further scrutinized by the linear-polarization signature of jet components traveling along the jet and passing a region of steep pressure/density gradients.

  10. Possible Superluminal Components in the Nearest Tidal Disruption Event

    Science.gov (United States)

    Perlman, Eric S.; Meyer, Eileen T.; Wang, Daniel; Yuan, Qiang; Irwin, Judith; Henriksen, Richard N.

    2017-01-01

    Tidal disruption events (TDEs) are believed to occur when a star or sub-stellar objects pass close enough to a supermassive black hole for the object to be disrupted by tidal forces. NGC 4845 (d=17 Mpc) was host to a TDE, IGR J12580+0134, that was detected by INTEGRAL in the X-rays and later in the radio by the JVLA. Its proximity offers us a so far unique close-up of the TDE and its aftermath. Here we discuss new VLBA and JVLA observations, obtained in 2015, which show that the radio flux from the active nucleus created by the TDE has decayed in a manner consistent with predictions from a jet-circumnuclear interaction model. But more excitingly, they also contain evidence of ejecta, in the form of a resolved component located 52 milliarcsec (4.1 pc) from the nucleus which, if ejected in 2010 as a result at the TDE, is moving superluminally at 2.4c. The milliarcsecond-scale core is seen to be circularly polarized in our L-band observations only. We discuss the implications of these observations.

  11. Astronomy. ASASSN-15lh: A highly super-luminous supernova.

    Science.gov (United States)

    Dong, Subo; Shappee, B J; Prieto, J L; Jha, S W; Stanek, K Z; Holoien, T W-S; Kochanek, C S; Thompson, T A; Morrell, N; Thompson, I B; Basu, U; Beacom, J F; Bersier, D; Brimacombe, J; Brown, J S; Bufano, F; Chen, Ping; Conseil, E; Danilet, A B; Falco, E; Grupe, D; Kiyota, S; Masi, G; Nicholls, B; Olivares E, F; Pignata, G; Pojmanski, G; Simonian, G V; Szczygiel, D M; Woźniak, P R

    2016-01-15

    We report the discovery of ASASSN-15lh (SN 2015L), which we interpret as the most luminous supernova yet found. At redshift z = 0.2326, ASASSN-15lh reached an absolute magnitude of Mu ,AB = -23.5 ± 0.1 and bolometric luminosity Lbol = (2.2 ± 0.2) × 10(45) ergs s(-1), which is more than twice as luminous as any previously known supernova. It has several major features characteristic of the hydrogen-poor super-luminous supernovae (SLSNe-I), whose energy sources and progenitors are currently poorly understood. In contrast to most previously known SLSNe-I that reside in star-forming dwarf galaxies, ASASSN-15lh appears to be hosted by a luminous galaxy (MK ≈ -25.5) with little star formation. In the 4 months since first detection, ASASSN-15lh radiated (1.1 ± 0.2) × 10(52) ergs, challenging the magnetar model for its engine. Copyright © 2016, American Association for the Advancement of Science.

  12. RAPIDLY RISING TRANSIENTS IN THE SUPERNOVA—SUPERLUMINOUS SUPERNOVA GAP

    Energy Technology Data Exchange (ETDEWEB)

    Arcavi, Iair; Howell, D. Andrew [Las Cumbres Observatory Global Telescope, 6740 Cortona Dr., Suite 102, Goleta, CA 93111 (United States); Wolf, William M. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Bildsten, Lars; McCully, Curtis; Valenti, Stefano [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States); Leloudas, Giorgos; Gal-Yam, Avishay; Katz, Boaz [Department of Particle Physics and Astrophysics, The Weizmann Institute of Science, Rehovot, 76100 (Israel); Hardin, Delphine; Astier, Pierre; Balland, Cristophe [LPNHE, CNRS-IN2P3 and University of Paris VI and VII, F-75005 Paris (France); Prajs, Szymon; Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Perley, Daniel A. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Svirski, Gilad [Racah Institute for Physics, The Hebrew University, Jerusalem 91904 (Israel); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Lidman, Chris [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); Carlberg, Ray G. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H8 (Canada); Conley, Alex, E-mail: iarcavi@lcogt.net [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309-389 (United States); and others

    2016-03-01

    We present observations of four rapidly rising (t{sub rise} ≈ 10 days) transients with peak luminosities between those of supernovae (SNe) and superluminous SNe (M{sub peak} ≈ −20)—one discovered and followed by the Palomar Transient Factory (PTF) and three by the Supernova Legacy Survey. The light curves resemble those of SN 2011kl, recently shown to be associated with an ultra-long-duration gamma-ray burst (GRB), though no GRB was seen to accompany our SNe. The rapid rise to a luminous peak places these events in a unique part of SN phase space, challenging standard SN emission mechanisms. Spectra of the PTF event formally classify it as an SN II due to broad Hα emission, but an unusual absorption feature, which can be interpreted as either high velocity Hα (though deeper than in previously known cases) or Si ii (as seen in SNe Ia), is also observed. We find that existing models of white dwarf detonations, CSM interaction, shock breakout in a wind (or steeper CSM), and magnetar spin down cannot readily explain the observations. We consider the possibility that a “Type 1.5 SN” scenario could be the origin of our events. More detailed models for these kinds of transients and more constraining observations of future such events should help to better determine their nature.

  13. Superluminal X-shaped beams propagating without distortion along a coaxial guide.

    Science.gov (United States)

    Zamboni-Rached, Michel; Nóbrega, K Z; Recami, Erasmo; Hernández-Figueroa, Hugo Enrique

    2002-10-01

    In a previous paper we showed that localized superluminal solutions to the Maxwell equations exist, which propagate down (nonevanescence) regions of a metallic cylindrical waveguide. In this paper we construct analogous nondispersive waves propagating along coaxial cables. Such new solutions, in general, consist in trains of (undistorted) superluminal "X-shaped" pulses. Particular attention is paid to the construction of finite total energy solutions. Any results of this kind may find application in the other fields in which an essential role is played by a wave equation (like acoustics, geophysics, etc.).

  14. Superluminal and slow light propagation in a room-temperature solid.

    Science.gov (United States)

    Bigelow, Matthew S; Lepeshkin, Nick N; Boyd, Robert W

    2003-07-11

    We have observed both superluminal and ultraslow light propagation in an alexandrite crystal at room temperature. Group velocities as slow as 91 meters per second to as fast as -800 meters per second were measured and attributed to the influence of coherent population oscillations involving chromium ions in either mirror or inversion sites within the crystal lattice. Namely, ions in mirror sites are inversely saturable and cause superluminal light propagation, whereas ions in inversion sites experience conventional saturable absorption and produce slow light. This technique for producing large group indices is considerably easier than the existing methods to implement and is therefore suitable for diverse applications.

  15. Superluminal propagation at negative group velocity in optical fibers based on Brillouin lasing oscillation.

    Science.gov (United States)

    Zhang, Liang; Zhan, Li; Qian, Kai; Liu, Jinmei; Shen, Qishun; Hu, Xiao; Luo, Shouyu

    2011-08-26

    We report superluminal propagation in optical fibers using Brillouin lasing oscillation in a ring cavity. Negative group velocity propagation through a 10-m single mode fiber has been experimentally demonstrated. An advancement of 221.2 ns was observed before the input signal, which was achieved with a very high slope efficiency of 211.3  ns/dB. This indicates that this way is suitable for long-distance low-loss superluminal propagation via optical fibers. Correspondingly, the group velocity is -0.151c and the group index is -6.636-the highest group velocity ever reported for optical fibers. © 2011 American Physical Society

  16. Measurement of superluminal optical tunneling times in double-barrier photonic band gaps.

    Science.gov (United States)

    Longhi, S; Laporta, P; Belmonte, M; Recami, E

    2002-04-01

    Tunneling of optical pulses at 1.5 microm wavelength through double-barrier periodic fiber Bragg gratings is experimentally investigated in this paper. Tunneling time measurements as a function of the barrier distance show that, far from resonances of the structure, the transit time is paradoxically short--implying superluminal propagation--and almost independent of the barrier distance. This result is in agreement with theoretical predictions based on phase-time analysis and provides, in the optical context, an experimental evidence of the analogous phenomenon in quantum mechanics of nonresonant superluminal tunneling of particles across two successive potential barriers.

  17. Potential Usefulness of Flash-Induced Superluminal Light-Echo Pairs

    Science.gov (United States)

    Nemiroff, Robert J.; Zhong, Qi

    2016-01-01

    Astronomical flashes can create transient light-echo pair phenomena that have never yet been seen but might result in useful information, if found. Toward this end, it is first proven that all light-echo spots are intrinsically superluminal. The radial component of spot speeds toward an observer, however, may be subluminal, and spot pair creation and annihilation events will be observable, in theory, when spots cross the radial superluminal speed boundary. If found, these light-echo pairs could connect angular speeds to spatial speeds, which in turn could result in the recovery of absolute sizes, three-dimensional spatial orientations, and distances to astronomical objects. A hypothetical example is given.

  18. Superluminal pulse reflection in asymmetric one-dimensional photonic band gaps.

    Science.gov (United States)

    Longhi, S

    2001-09-01

    Superluminal pulse reflection is shown to occur in a class of one-dimensional asymmetric photonic band gaps in which a spectral window inside the gap is opened. By means of a coupled-mode equation analysis, we describe in detail two possible realizations of superluminal pulse reflection that can be achieved using fiber Bragg gratings. The former method is based on the introduction of a defect into the otherwise periodic dielectric structure, whereas the latter one exploits the interference of two closely-spaced resonance modes and simulates the dispersion properties of an inverted medium possessing a doublet line.

  19. Model dependence of the bremsstrahlung effects from the superluminal neutrino at OPERA

    CERN Document Server

    Bezrukov, Fedor

    2012-01-01

    We revisit the bremsstrahlung process of a superluminal neutrino motivated by OPERA results. From a careful analysis of the plane wave solutions of the superluminal neutrino, we find that the squared matrix elements contain additional terms from Lorentz violation due to the modified spin sum for the neutrino. We point out that the coefficients of the decay rate and the energy loss rate significantly depend on the details of the model, although the results are parametrically similar to the ones obtained by Cohen and Glashow [1]. We illustrate this from the modified neutral current interaction of neutrino with Lorentz violation of the same order as in the modified dispersion relation.

  20. Superluminal pulse propagation through one-dimensional photonic crystals with a dispersive defect.

    Science.gov (United States)

    Liu, Nian-Hua; Zhu, Shi-Yao; Chen, Hong; Wu, Xiang

    2002-04-01

    The propagation of a pulse through one-dimensional photonic crystals that contain a dispersive and absorptive defect layer doped with two-level atoms is discussed. The dynamical evolution of the pulse inside the photonic crystal is presented. Superluminal negative group velocity (the peak appears at the exit end before it reaches the input end) is discovered. Although the group velocity is larger than c and even negative, the velocity of energy propagation never exceeds the vacuum light speed. The appearance of the superluminal advance or subluminal delay of the pulse peak inside the photonic crystal or at the exit end is due to the wave interference from Bragg reflections.

  1. Copropagating superluminal and slow light manifested by electromagnetically assisted nonlinear optical processes.

    Science.gov (United States)

    Zhang, Jiepeng; Hernandez, Gessler; Zhu, Yifu

    2006-09-01

    We report an experimental observation of nonlinear optical gain and loss assisted by electromagnetically induced transparency (EIT) and simultaneous superluminal and subluminal light propagations. Two circular components of a linearly polarized light initiate third-order nonlinear processes in which one circular component is attenuated while the other component is amplified in a three-level EIT system. Near the atomic resonance, the attenuated circular component experiences steep normal dispersion and propagates with a slow group velocity, while the amplified circular component experiences steep anomalous dispersion and propagates with a superluminal group velocity.

  2. Theory of frustrated total internal reflection: Superluminal singularities of optical waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Perel' man, Mark E. [Racah Institute of Physics, Hebrew University, Jerusalem (Israel)], E-mail: m.e.perelman@gmail.com

    2009-02-02

    Classical approach to frustrated total internal reflection (FTIR) does not describe its temporal properties, that are additionally considered and their superluminal singularity is shown. The transition to quantum electrodynamics shows that momenta of photons are reduced at FTIR relative to energy, i.e. it is the tunnel process, the nonlocal manifestation of near field. The tunneling consists in the instantaneous jump of excitations (virtual photons) onto definite distance, and can be described by equation having certain instanton features. Thus, the possibility of signal transfer with superluminal group velocity via optical fibers is substantiated that conforms to certain supervisions. Such properties of FTIR near field may explain, in principle, some other observed phenomena.

  3. The superluminal radio source 4c 39. 25 as relativistic jet prototype. El cuasar superluminal 4C 93. 25 como prototipo de jet relativistia

    Energy Technology Data Exchange (ETDEWEB)

    Alberdi, A.; Gomez, J.L.; Marcaide, J.M.

    1993-01-01

    We have developed a numerical code which solves the synchrotron radiation transfer equations to compute the total and polarized emission of bent shocked relativistic jets, and we have applied it to reproduce the compact structure, kinematic evolution of the superluminal radio source 4C 39.25 contains a bent relativistic jet which is misaligned relative to the observer near the core region, leading to a relatively low core brightness. (Author) 12 refs.

  4. Olber's paradox for superluminal neutrinos: constraining extreme neutrino speeds at TeV–ZeV energies with the diffuse neutrino background

    Energy Technology Data Exchange (ETDEWEB)

    Lacki, Brian C., E-mail: brianlacki@ias.edu [Jansky Fellow, National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, Virginia (United States)

    2012-01-01

    The only invariant speed in special relativity is c; therefore, if some neutrinos travel at even tiny speeds above c, normal special relativity is incomplete and any superluminal speed may be possible. I derive a limit on superluminal neutrino speeds v >> c at high energies by noting that such speeds would increase the size of the neutrino horizon. The increased volume of the Universe visible leads to a brighter astrophysical neutrino background. The nondetection of ''guaranteed'' neutrino backgrounds from star-forming galaxies and ultrahigh energy cosmic rays (UHECRs) constrains v/c at TeV–ZeV energies. I find that v/c∼<820 at 60 TeV from the nondetection of neutrinos from star-forming galaxies. The nondetection of neutrinos from UHECRs constrains v/c to be less than 2500 at 0.1 EeV in a pessimistic model and less than 4.6 at 4 EeV in an optimistic model. The UHECR neutrino background nondetection is strongly inconsistent with a naive quadratic extrapolation of the OPERA results to EeV energies. The limits apply subject to some caveats, particularly that the expected pionic neutrino backgrounds exist and that neutrinos travel faster than c when they pass the detector. They could be improved substantially as the expected neutrino backgrounds are better understood and with new experimental neutrino background limits. I also point out that extremely subluminal speeds would result in a much smaller neutrino background intensity than expected.

  5. Infrared spectroscopy of the superluminal Galactic source GRS 1915+105 during the 1994 September outburst

    DEFF Research Database (Denmark)

    CastroTirado, A.J.; Geballe, T.R.; Lund, Niels

    1996-01-01

    We have obtained K-band IR spectra of the superluminal Galactic source GRS 1915+105 on two different dates. The second spectrum, obtained immediately after a bright X-ray outburst in 1994 September, has shown prominent H and He emission lines. The lines are not Doppler shifted, as are those obser...

  6. Superluminal neutrinos and extra dimensions: Constraints from the null energy condition

    Energy Technology Data Exchange (ETDEWEB)

    Gubser, Steven S., E-mail: ssgubser@princeton.edu [Joseph Henry Laboratories, Princeton University, Princeton, NJ 08544 (United States)

    2011-11-11

    In light of the recent results from the OPERA Collaboration, indicating that neutrinos can travel superluminally, I review a simple extra-dimensional strategy for accommodating such behavior; and I also explain why it is hard in this strategy to avoid violating the null energy condition somewhere in the extra dimensions.

  7. THE ROLE OF SUPERLUMINAL ELECTROMAGNETIC WAVES IN PULSAR WIND TERMINATION SHOCKS

    Energy Technology Data Exchange (ETDEWEB)

    Amano, Takanobu [Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033 (Japan); Kirk, John G., E-mail: amano@eps.s.u-tokyo.ac.jp [Max-Planck-Institut fuer Kernphysik, Postfach 103980, D-69029 Heidelberg (Germany)

    2013-06-10

    The dynamics of a standing shock front in a Poynting-flux-dominated relativistic flow is investigated by using a one-dimensional, relativistic, two-fluid simulation. An upstream flow containing a circularly polarized, sinusoidal magnetic shear wave is considered, mimicking a wave driven by an obliquely rotating pulsar. It is demonstrated that this wave is converted into large-amplitude electromagnetic waves with superluminal phase speeds by interacting with the shock when the shock-frame frequency of the wave exceeds the proper plasma frequency. The superluminal waves propagate in the upstream, modify the shock structure substantially, and form a well-developed precursor region ahead of a subshock. Dissipation of Poynting flux occurs in the precursor as well as in the downstream region through a parametric instability driven by the superluminal waves. The Poynting flux remaining in the downstream region is carried entirely by the superluminal waves. The downstream plasma is therefore an essentially unmagnetized, relativistically hot plasma with a non-relativistic flow speed, as suggested by observations of pulsar wind nebulae.

  8. Passive system with tunable group velocity for propagating electrical pulses from sub- to superluminal velocities.

    Science.gov (United States)

    Haché, Alain; Essiambre, Sophie

    2004-05-01

    We report an observation of tunable group velocity from sub-luminal to superluminal in a completely passive system. Electric pulses are sent along a spatially periodic conducting medium containing a punctual nonlinearity, and the resulting amplitude-dependent phase shift allows us to control dispersion and the propagation velocity at the stop band frequency.

  9. Measurement of the superluminal group velocity of an ultrashort Bessel beam pulse.

    Science.gov (United States)

    Alexeev, I; Kim, K Y; Milchberg, H M

    2002-02-18

    The superluminal group velocity of an ultrashort optical Bessel beam pulse is measured over its entire depth of field, corresponding to approximately 2x10(4) optical wavelengths. The method used is to measure the traveling ionization front induced by the pulse.

  10. Particular features of the emission of radiation by a superluminally excited Raman-active medium

    Science.gov (United States)

    Arkhipov, R. M.

    2016-05-01

    Particular features of the emission of radiation by a Raman-active medium excited by a sequence of ultrashort superluminal pulses have been studied theoretically. It is shown that such an excitation gives rise to the possibility of obtaining unipolar rectangular videopulses the duration and amplitude of which depend on the velocity of propagation of the excitation over the medium.

  11. On the nature of hydrogen-rich superluminous supernovae

    Science.gov (United States)

    Inserra, C.; Smartt, S. J.; Gall, E. E. E.; Leloudas, G.; Chen, T.-W.; Schulze, S.; Jerkstrand, A.; Nicholl, M.; Anderson, J. P.; Arcavi, I.; Benetti, S.; Cartier, R. A.; Childress, M.; Della Valle, M.; Flewelling, H.; Fraser, M.; Gal-Yam, A.; Gutiérrez, C. P.; Hosseinzadeh, G.; Howell, D. A.; Huber, M.; Kankare, E.; Krühler, T.; Magnier, E. A.; Maguire, K.; McCully, C.; Prajs, S.; Primak, N.; Scalzo, R.; Schmidt, B. P.; Smith, M.; Smith, K. W.; Tucker, B. E.; Valenti, S.; Wilman, M.; Young, D. R.; Yuan, F.

    2018-03-01

    We present two hydrogen-rich superluminous supernovae (SLSNe): SN2103hx and PS15br. These objects, together with SN2008es, are the only SLSNe showing a distinct, broad H α feature during the photospheric phase; also, they show no sign of strong interaction between fast moving ejecta and circumstellar shells in their early spectra. Despite the fact that the peak luminosity of PS15br is fainter than that of the other two objects, the spectrophotometric evolution is similar to SN2103hx and different from any other supernova in a similar luminosity space. We group all of them as SLSNe II and hence they are distinct from the known class of SLSN IIn. Both transients show a strong, multicomponent H α emission after 200 d past maximum, which we interpret as an indication of the interaction of the ejecta with an asymmetric, clumpy circumstellar material. The spectra and photometric evolution of the two objects are similar to Type II supernovae, although they have much higher luminosity and evolve on slower time-scales. This is qualitatively similar to how SLSNe I compare with normal type Ic, in that the former are brighter and evolve more slowly. We apply a magnetar and an interaction semi-analytical code to fit the light curves of our two objects and SN2008es. The overall observational data set would tend to favour the magnetar, or central engine, model as the source of the peak luminosity, although the clear signature of late-time interaction indicates that interaction can play a role in the luminosity evolution of SLSNe II at some phases.

  12. Superluminal and negative delay times in isotropic-anisotropic one-dimensional photonic crystal

    Science.gov (United States)

    Ouchani, N.; El Moussaouy, A.; Aynaou, H.; El Hassouani, Y.; El Boudouti, E. H.; Djafari-Rouhani, B.

    2017-11-01

    In this work, we investigate the possibility of superluminal and negative delay times for electromagnetic wave propagation in a linear and passive periodic structure consisting of alternating isotropic and anisotropic media. This phenomenon is due to the birefringence of the anisotropic layers of the structure. By adjusting the orientations of these layers, the delay times of transmitted waves can be controlled from subluminality to superluminality and vice versa. Numerical results indicate that the apparent superluminal propagation of light occurs inside the photonic band-gaps when the principal axes of the anisotropic layers are parallel or perpendicular to the fixed axes. For other orientations of these layers, tunneling and superluminal regimes appear inside the photonic bandgaps and in the allowed bands for frequencies close to the transmission minima. The effect of the number of unit cells of the photonic crystal structure on the propagation of light with superluminal and negative delay times is also investigated. We show that the structure exhibits the Hartman effect in which the tunneling delay time of the electromagnetic wave through the photonic band-gap of the structure converges asymptotically to a finite value with increasing the number of layers. The Green's function approach has been used to derive the transmission and reflection coefficients, the density of states, and the delay times of electromagnetic waves propagating through the structure. The control of the magnitude and the sign of the delay time of light propagation represent a key point in slow and fast light technologies. The proposed structure in this study represents a new system for controlling the delay times of wave propagation without a need of active or non-linear media as well as lossy or asymmetric periodic structures.

  13. Subluminal and superluminal parametric doppler effects in the case of light reflection from a moving smooth medium inhomogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Rozanov, N. N., E-mail: nrosanov@yahoo.com [Vavilov State Optical Institute (Russian Federation)

    2012-12-15

    The reflection of test radiation from a smooth inhomogeneity of medium characteristics propagating with a subluminal or superluminal velocity is analyzed. The equations describing the propagation of the forward- and counter-propagating waves in such an inhomogeneous medium are derived. Quasi-phase conjugation is demonstrated in the case of superluminal inhomogeneities. The Bragg resonance conditions are formulated and the conditions for increasing the reflection coefficient of radiation from an inhomogeneity are discussed.

  14. Sub- and super-luminal light propagation using a Rydberg state

    CERN Document Server

    Bharti, Vineet

    2016-01-01

    We present a theoretical study to investigate sub- and super-luminal light propagation in a rubidium atomic system consisting of a Rydberg state by using density matrix formalism. The analysis is performed in a 4-level vee+ladder system interacting with a weak probe, and strong control and switching fields. The dispersion and absorption profiles are shown for stationary atoms as well as for moving atoms by carrying out Doppler averaging at room temperature. We also present the group index variation with control Rabi frequency and observe that a transparent medium can be switched from sub- to super-luminal propagation in the presence of switching field. Finally, the transient response of the medium is discussed, which shows that the considered 4-level scheme has potential applications in absorptive optical switching.

  15. Gain-assisted superluminal light propagation through a Bose-Einstein condensate cavity system

    Science.gov (United States)

    Hamide Kazemi, S.; Ghanbari, S.; Mahmoudi, M.

    2016-01-01

    The propagation of a probe laser field in a cavity optomechanical system with a Bose-Einstein condensate is studied. The transmission properties of the system are investigated and it is shown that the group velocity of the probe pulse field can be controlled by Rabi frequency of the pump laser field. The effect of the decay rate of the cavity photons on the group velocity is studied and it is demonstrated that for small values of the decay rates, the light propagation switches from subluminal to superluminal just by changing the Rabi frequency of the pump field. Then, the gain-assisted superluminal light propagation due to the cross-Kerr nonlinearity is established in cavity optomechanical system with a Bose-Einstein condensate. Such behavior can not appear in the pump-probe two-level atomic systems in the normal phase. We also find that the amplification is achieved without inversion in the population of the quantum energy levels.

  16. Manipulation of slow and superluminal light based on a graphene nanoribbon resonator

    Science.gov (United States)

    Chen, Hua-Jun; Sun, Bian-Bian; Wu, Hong-Wei; Fang, Xian-Wen

    2017-03-01

    We theoretically investigate the phenomena of slow and superluminal light based on a doubly clamped Z-shaped graphene nanoribbon (GNR) nanomechanical resonator driven by two-tone fields. Superluminal and ultraslow probe light without absorption can be obtained via manipulating the pump laser on- and off-resonant with the exciton frequency, respectively. The results indicate that the above phenomena cannot occur without the coupling between graphene resonator and excition in the system. Further, the all-optical schemes for determining the graphene resonator frequency and the coupling strength of excition-resonator in the Z-shaped GNR system are also proposed. The all-optical device based on graphene resonator may have potential application in optical networks and engineering in nanoscale.

  17. A unified view to Cologne and Florence experiments on superluminal photon propagation

    Energy Technology Data Exchange (ETDEWEB)

    Cardone, Fabio; Mignani, Roberto

    2003-01-13

    We show that two of the first performed experiments on superluminal photon propagation, namely, the 1992 Cologne experiment on the tunneling of evanescent waves in an undersized waveguide, and the 1993 Florence experiment on the microwave propagation in vacuum between two horn antennas, do admit a common interpretation. Precisely, both experimental devices behave as a high-pass filter. We get this result by two different methods, one based on the Friis law (which yields the efficiency of a transmitting device), and the other on the deformation of the Minkowski space-time. This allows us to set intriguing connections between these two (a priori different) classes of experiments. In particular, in either case the superluminal propagation can be described as a tunneling and is related to evanescent waves.

  18. Superluminal optical pulse propagation at 1.5 microm in periodic fiber Bragg gratings.

    Science.gov (United States)

    Longhi, S; Marano, M; Laporta, P; Belmonte, M

    2001-11-01

    We report on the experimental observation of superluminal tunneling of picosecond optical pulses in a periodic fiber Bragg grating. Optical pulses of 380-ps duration, generated by an externally-modulated single-frequency erbium-ytterbium laser operating near 1.5-microm wavelength, were propagated at a group velocity greater than approximately 1.97 times the speed of light in vacuum across a 2-cm long fiber grating. Owing to the very large ratio between the thickness of the barrier (2 cm) and the wavelength of probing optical pulses ( approximately 1.5 microm), our experiment allows for the observation of superluminal tunneling in the optical region by direct optoelectronic time-domain measurements.

  19. Controlling the Radiation Parameters of a Resonant Medium Excited by a Sequence of Ultrashort Superluminal Pulses

    Science.gov (United States)

    Arkhipov, R. M.; Arkhipov, M. V.; Belov, P. A.; Babushkin, I.; Tolmachev, Yu. A.

    2016-03-01

    We investigate the possibility of controlling the radiation parameters of a spatially periodic one-dimensional medium consisting of classical harmonic oscillators by means of a sequence of ultrashort pulses that propagate through the medium with a superluminal velocity. We show that, in the spectrum of the transient process, in addition to the radiation at a resonant frequency of oscillators, new frequencies arise that depend on the period of the spatial distribution of the oscillator density, the excitation velocity, and the angle of observation. We have examined in detail the case of excitation of the medium by a periodic sequence of ultrashort pulses that travel with a superluminal velocity. We show that it is possible to excite oscillations of complex shapes and to control the radiation parameters of the resonant medium by changing the relationship between the pulse repetition rate, the medium resonant frequency, and the new frequency.

  20. Apparatus and method for phase fronts based on superluminal polarization current

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, John [Los Alamos, NM; Ardavan, Houshang [Cambridge, GB; Ardavan, Arzhang [Cambridge, GB

    2012-02-28

    An apparatus and method for a radiation source involving phase fronts emanating from an accelerated, oscillating polarization current whose distribution pattern moves superluminally (that is, faster than light in vacuo). Theoretical predictions and experimental measurements using an existing prototype superluminal source show that the phase fronts from such a source can be made to be very complex. Consequently, it will be very difficult for an aircraft imaged by such a radiation to detect where this radiation has come from. Moreover, the complexity of the phase fronts makes it almost impossible for electronics on an aircraft to synthesize a rogue reflection. A simple directional antenna and timing system should, on the other hand, be sufficient for the radar operators to locate the aircraft, given knowledge of their own source's speed and modulation pattern.

  1. RADIATIVE DAMPING AND EMISSION SIGNATURES OF STRONG SUPERLUMINAL WAVES IN PULSAR WINDS

    Energy Technology Data Exchange (ETDEWEB)

    Mochol, Iwona; Kirk, John G., E-mail: iwona.mochol@mpi-hd.mpg.de, E-mail: john.kirk@mpi-hd.mpg.de [Max-Planck-Institut für Kernphysik, Postfach 10 39 80, D-69029 Heidelberg (Germany)

    2013-10-10

    We analyze the damping of strong, superluminal electromagnetic waves by radiation reaction and Compton drag in the context of pulsar winds. The associated radiation signature is found by estimating the efficiency and the characteristic radiation frequencies. Applying these estimates to the gamma-ray binary containing PSR B1259–63, we show that the GeV flare observed by the Fermi Large Area Telescope can be understood as inverse-Compton emission by particles scattering photons from the companion star, if the pulsar wind termination shock acquires a precursor of superluminal waves roughly 30 days after periastron. This requirement constrains the mass-loading factor of the wind μ=L/ N-dot mc{sup 2}, where L is the luminosity and N-dot is the rate of loss of electrons and positrons, to be roughly 6 × 10{sup 4}.

  2. Model dependence of the bremsstrahlung effects from the superluminal neutrino at OPERA

    Science.gov (United States)

    Bezrukov, Fedor; Lee, Hyun Min

    2012-02-01

    We revisit the bremsstrahlung process of a superluminal neutrino motivated by OPERA results. From a careful analysis of the plane-wave solutions of the superluminal neutrino, we find that the squared matrix elements contain additional terms from Lorentz violation due to the modified spin sum for the neutrino. We point out that the coefficients of the decay rate and the energy loss rate significantly depend on the details of the model, although the results are parametrically similar to the ones obtained by Cohen and Glashow [A. G. Cohen and S. L. Glashow, Phys. Rev. Lett. 107, 181803 (2011).PRLTAO0031-900710.1103/PhysRevLett.107.181803]. We illustrate this from the modified neutral current interaction of neutrino with Lorentz violation of the same order as in the modified dispersion relation.

  3. Superluminal media formed by photonic crystals for transformation optics-based invisibility cloaks

    Science.gov (United States)

    Semouchkina, Elena; Duan, Ran; Gandji, Navid P.; Jamilan, Saeid; Semouchkin, George; Pandey, Ravi

    2016-04-01

    We have developed an approach to building superluminal medium for transformation optics-based devices, including invisibility cloaks, from photonic crystals. Analysis of dispersion diagrams of 2D arrays composed from dielectric rods has shown that at frequencies corresponding to the second bands formed due to bandgap opening at increase of rod permittivity, the medium formed by arrays exhibits refractive indices providing for superluminal phase velocities of propagating waves. It is further demonstrated that rod arrays with various lattice constants could be used for realizing a range of superluminal index values prescribed by transformation optics for cylindrical cloaks at arbitrary chosen operating frequency. The performed studies allowed for solving a row of problems with employment rod arrays in the cloak medium: in particular, formulating transformation optics-based prescriptions for refractive index dispersion in the cloaking shell, defining the dimensions of array fragments capable of responding similar to infinite arrays, finding optimal distribution of linear arrays sets at their coiling to form concentric material layers in the cloaking shell, and employing interaction between neighboring array sets with various lattice constants to assist the realization of prescribed index dispersion. The performance of the superluminal medium formed by rod array sets was demonstrated on an example of a cloaking shell developed for microwave frequency range. In contrast to metamaterial-based cloak media, the developed media requires neither material homogenization, nor obtaining the effective parameters with peculiar values and Lorentz’s type resonances in rods. Combination of these advantages and low losses makes photonic crystals perspective materials for invisibility cloaks operating in THz and optical ranges.

  4. Modulation-frequency-controlled change from sub- to superluminal regime in highly doped erbium fibers.

    Science.gov (United States)

    Melle, Sonia; Calderón, Oscar G; Caro, Cesar E; Cabrera-Granado, E; Antón, M A; Carreño, F

    2008-04-15

    We report a change from sub- to superluminal propagation upon increasing the modulation frequency of an amplitude-modulated 1,550 nm signal when propagating through highly doped erbium fibers pumped at 980 nm. We show that the interplay between the pump absorption and the pump-power broadening of the spectral hole induced by coherent population oscillations may drastically affect the fractional advancement or delay of the signal for the considered fibers.

  5. Observation of superluminal wave-front propagation at the shadow area behind an opaque disk.

    Science.gov (United States)

    Vasnetsov, M; Pas'ko, V; Khoroshun, A; Slyusar, V; Soskin, M

    2007-07-01

    We demonstrate in theory and experiment superluminal properties of optical field propagation in the shadow area behind an opaque disk (Poisson's spot). The wave front of the field in the shadow zone is initially delayed with respect to the unperturbed field. This phase shift gradually diminishes along the optical path and therefore ensures variation of the phase velocity of the field at the axis. A resulting excess of about cx10(-5) was detected.

  6. Direct measurement of superluminal group velocity and signal velocity in an optical fiber.

    Science.gov (United States)

    Brunner, Nicolas; Scarani, Valerio; Wegmüller, Mark; Legré, Matthieu; Gisin, Nicolas

    2004-11-12

    We present an easy way of observing superluminal group velocities using a birefringent optical fiber and other standard devices. In the theoretical analysis, we show that the optical properties of the setup can be described using the notion of "weak value." The experiment shows that the group velocity can indeed exceed c in the fiber; and we report the first direct observation of the so-called "signal velocity," the speed at which information propagates and that cannot exceed c.

  7. Possibility of high performance quantum computation by superluminal evanescent photons in living systems.

    Science.gov (United States)

    Musha, Takaaki

    2009-06-01

    Penrose and Hameroff have suggested that microtubules in living systems function as quantum computers by utilizing evanescent photons. On the basis of the theorem that the evanescent photon is a superluminal particle, the possibility of high performance computation in living systems has been studied. From the theoretical analysis, it is shown that the biological brain can achieve large quantum bits computation compared with the conventional processors at room temperature.

  8. Superluminal and stopped light due to mode coupling in confined hyperbolic metamaterial waveguides

    Science.gov (United States)

    Neira, Andres D.; Wurtz, Gregory A.; Zayats, Anatoly V.

    2015-12-01

    Anisotropic metamaterials with hyperbolic dispersion can be used to design waveguides with unusual properties. We show that, in contrast to planar waveguides, geometric confinement leads to coupling of ordinary (forward) and extraordinary (backward) modes and formation of hybrid waveguided modes, which near the crossing point may exhibit slow, stopped or superluminal behavior accompanied by very strong group velocity dispersion. These modes can be used for designing stopped-light nanolasers for nanophotonic applications and dispersion-facilitated signal reshaping in telecom applications.

  9. Simultaneous observation of superluminal and slow light propagation in a nested fiber ring resonator.

    Science.gov (United States)

    Wang, Jinfang; Zhang, Yundong; Zhang, Jing; Cai, Yuanxue; Zhang, Xuenan; Yuan, Ping

    2010-06-07

    We observe both superluminal and slow light propagation simultaneously in a nested fiber ring resonator. The two outputs of the resonator exhibit different absorption characteristics that produce opposite dispersion performance. The transmission spectra of two outputs are demonstrated experimentally for a variety of coupler settings. In particular, the group delays of the resonator for various values of the coupling coefficients are demonstrated theoretically and experimentally. We also discuss potential applications of the resonator.

  10. Fundamental role of the retarded potential in the electrodynamics of superluminal sources.

    Science.gov (United States)

    Ardavan, Houshang; Ardavan, Arzhang; Singleton, John; Fasel, Joseph; Schmidt, Andrea

    2008-03-01

    We calculate the gradient of the radiation field generated by a polarization current with a superluminally rotating distribution pattern and show that the absolute value of this gradient increases as R(7/2) with distance R, within the sharply focused subbeams that constitute the overall radiation beam from such a source. In addition to supporting the earlier finding that the azimuthal and polar widths of these subbeams become narrower (as R(-3) and R(-1), respectively) with distance from the source, this result implies that the boundary contribution to the solution of the wave equation governing the radiation field does not always vanish in the limit where the boundary tends to infinity (as is commonly assumed in textbooks and the published literature). While the boundary contribution to the retarded solution for the potential can always be rendered equal to zero by means of a gauge transformation that preserves the Lorenz condition, the boundary contribution to the retarded solution of the wave equation for the field may be neglected only if it diminishes with distance faster than the contribution of the source density. In the case of a rotating superluminal source, however, the boundary term in the retarded solution for the field is by a factor of the order of R(1/2)larger than the source term of this solution, in the limit where the boundary tends to infinity. This result explains why an argument based on the solution of the wave equation governing the field in which the boundary term is neglected [such as that presented by Hannay, J. Opt. Soc. A 23, 1530 (2006)] misses the nonspherical decay of the field that is generated by a rotating superluminal source. The only way one can calculate the free-space radiation field of an accelerated superluminal source is via the retarded solution for the potential. Our findings have implications also for the observations of the pulsar emission: The more distant a pulsar, the narrower and brighter its giant pulses should be.

  11. Sub- and superluminal propagation of intense pulses in media with saturated and reverse absorption.

    Science.gov (United States)

    Agarwal, G S; Dey, Tarak Nath

    2004-05-21

    We develop models for the propagation of intense pulses in solid state media which can have either saturated absorption or reverse absorption. We model subluminal propagation in ruby and superluminal propagation in alexandrite as three and four level systems, respectively, coupled to Maxwell's equations. We present results well beyond the traditional pump-probe approach and explain the experiments of Bigelow et al. [Phys. Rev. Lett. 90, 113903 (2003)]Science 301, 200 (2003)

  12. Gain-assisted superluminal propagation in tellurite glass fiber based on stimulated Brillouin scattering.

    Science.gov (United States)

    Song, Kwang Yong; Abedin, Kazi S; Hotate, Kazuo

    2008-01-07

    We demonstrate superluminal propagation of optical pulses with amplification in optical fibers based on stimulated Brillouin scattering. A triple gain peak configuration is used for the generation of narrowband anomalous dispersion in 2 m tellurite glass fiber, where the group index change as much as -1.19 is achieved with 6.9 dB amplification in 34 ns Gaussian pulses, leading to the group index of 0.84.

  13. Anomalous dispersion and superluminal group velocity in a coaxial photonic crystal: theory and experiment.

    Science.gov (United States)

    Haché, A; Poirier, L

    2002-03-01

    We demonstrate that coaxial cables with a periodic impedance exhibit dispersion properties specific to photonic crystals, albeit on a much lower frequency scale. Highly superluminal (>2c) pulse propagation is observed near the photonic band gap at 10 MHz. The influence of group velocity dispersion and crystal length on the traveling speed and shape of a Gaussian pulse are discussed. Results compare favorably with a simple multilayer theory and a coupled-mass model of the structure.

  14. Fundamental role of the retarded potential in the electrodynamics of superluminal sources: reply to comment

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, John [Los Alamos National Laboratory; Fasel, Joseph H [Los Alamos National Laboratory; Schmidt, Andrea C [Los Alamos National Laboratory; Ardavan, Houshang [UNIV OF CAMBRIDGE; Ardavan, Arzhang [UNIV OF OXFORD

    2009-01-01

    Neither Eq. (6.52) of Jackson [Classical Electrodynamics, 3rd ed. (Wiley, 1999)], or Hannay's derivation of that dquation in the preceding Comment [J. Opt. Soc. Am. A, ... (2009)], are applicable to a source whose distribution pattern moves faster than light in vacuo with nonzero acceleration. It is assumed in Hannay's derivation that the retarded distribution of the density of any moving source would be smooth and differentiable if its rest-frame distribution is. By working out an explicit example of a rotating superluminal source with a bounded and smooth density profile, we show that this assumption is erroneous. The retarded distribution of a rotating source with a moderate superluminal speed is, in general, spread over three disjoint volumes (differing in shape from each other and from the volume occupied by the source in its rest frame) whose boundaries depend on the spacetime position of the observer. Hannay overlooks the fact that the limits of integration in his expression for the retarded potential (which delineate the boundaries of the retarded distribution of the source) are not differentiable functions of the coordinates of the observer at those points on the source boundary that approach the observer, along the radiation direction, with the speed of light at the retarded time. In the superluminal regime, derivatives of the integral representing the retarded potential are well defined only as generalized functions.

  15. The principle of relativity, superluminality and EPR experiments. "Riserratevi sotto coverta ..."

    Science.gov (United States)

    Cocciaro, B.

    2015-07-01

    The principle of relativity claims the invariance of the results for experiments carried out in inertial reference frames if the system under examination is not in interaction with the outside world. In this paper it is analysed a model suggested by J. S. Bell, and later developed by P. H. Eberhard, D. Bohm and B. Hiley on the basis of which the EPR correlations would be due to superluminal exchanges between the various parts of the entangled system under examination. In the model the existence of a privileged reference frame (PF) for the propagation of superluminal signals is hypothesized so that these superluminal signals may not give rise to causal paradoxes. According to this model, in an EPR experiment, the entangled system interacts with the outer world since the result of the experiment depends on an entity (the reference frame PF) that is not prepared by the experimenter. The existence of this privileged reference frame makes the model non invariant for Lorentz transformations. In this paper, in opposition to what claimed by the authors mentioned above, the perfect compatibility of the model with the theory of relativity is strongly maintained since, as already said, the principle of relativity does not require that the results of experiments carried out on systems interacting with the outside world should be invariant.

  16. The Effect of Carrying out Writing to Learn Activities on Academic Success of Fifth Grade Students in Secondary School on the Subject of "Force and Motion"

    Science.gov (United States)

    Seven, Sabriye; Koksal, Asiye Pinar; Kocak, Gulsen

    2017-01-01

    The aim of this study is to investigate the impact of writing poems and keeping a journal as writing-to-learn activities on the academic achievement of students in teaching the Force and Motion unit in the Science class of fifth grade students in secondary school. Sample of the study consists of 50 students who study in the fifth grade of two…

  17. Relativistic effects in superluminal jets and neutron star winds

    Energy Technology Data Exchange (ETDEWEB)

    Abramowicz, M.A.; Ellis, G.F.R.; Lanza, A. (International Centre for Theoretical Physics, Trieste (Italy) Chicago Univ., IL (USA) Scuola Internazionale Superiore di Studi Avanzati, Trieste (Italy) Cape Town Univ., Rondebosch (South Africa) International Center for Theoretical Physics, Trieste (Italy))

    1990-10-01

    A complete solution is given for the problem of radial motion of a test particle through the combined gravitational and radiation field of a spherical star. The star is assumed to radiate isotropically from each point of its surface. The radiative force acting on the particle is assumed not to depend on the frequency of radiation. There is no feedback from the particle motion to the background radiation field. All the effects of special and general relativity are included with no approximation. 29 refs.

  18. A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS

    CERN Document Server

    Antonello, M.; Baibussinov, B.; Baldo Ceolin, M.; Benetti, P.; Calligarich, E.; Canci, N.; Carbonara, F.; Centro, S.; Cesana, A.; Cieslik, K.; Cline, D.B.; Cocco, A.G.; Dabrowska, A.; Dequal, D.; Dermenev, A.; Dolfini, R.; Farnese, C.; Fava, A.; Ferrari, A.; Fiorillo, G.; Gibin, D.; Gigli Berzolari, A.; Gninenko, S.; Guglielmi, A.; Haranczyk, M.; Holeczek, J.; Ivashkin, A.; Kisiel, J.; Kochanek, I.; Lagoda, J.; Mania, S.; Mannocchi, G.; Menegolli, A.; Meng, G.; Montanari, C.; Otwinowski, S.; Periale, L.; Piazzoli, A.; Picchi, P.; Pietropaolo, F.; Plonski, P.; Rappoldi, A.; Raselli, G.L.; Rossella, M.; Rubbia, C.; Sala, P.R.; Scantamburlo, E.; Scaramelli, A.; Segreto, E.; Sergiampietri, F.; Stefan, D.; Stepaniak, J.; Sulej, R.; Szarska, M.; Terrani, M.; Varanini, F.; Ventura, S.; Vignoli, C.; Wang, H.; Yang, X.; Zalewska, A.; Zaremba, K.; Cohen, A.

    2012-01-01

    The OPERA collaboration [1] has claimed evidence of superluminal propagation between CERN and the LNGS with . We find that the neutrino energy distribution of the ICARUS events in LAr agrees with the expectations from the Monte Carlo predictions from an unaffected energy distribution of beam from CERN. Our results therefore refute a superluminal interpretation of the OPERA result according to the Cohen and Glashow prediction [2] for a weak currents analog to Cherenkov radiation. In particular no events with a superluminal Cherenkov like e+e- pair or gamma emission have been directly observed inside the fiducial volume of the "bubble chamber like" ICARUS TPC-LAr detector, setting much stricter limits to the value of delta comparable with the one due to the observations from the SN1987A.

  19. Measurement of visual motion

    Energy Technology Data Exchange (ETDEWEB)

    Hildreth, E.C.

    1984-01-01

    This book examines the measurement of visual motion and the use of relative movement to locate the boundaries of physical objects in the environment. It investigates the nature of the computations that are necessary to perform this analysis by any vision system, biological or artificial. Contents: Introduction. Background. Computation of the Velocity Field. An Algorithm to Compute the Velocity Field. The Computation of Motion Discontinuities. Perceptual Studies of Motion Measurement. The Psychophysics of Discontinuity Detection. Neurophysiological Studies of Motion. Summary and Conclusions. References. Author and Subject Indexes.

  20. Response of Seismically Isolated Steel Frame Buildings with Sustainable Lead-Rubber Bearing (LRB Isolator Devices Subjected to Near-Fault (NF Ground Motions

    Directory of Open Access Journals (Sweden)

    Jong Wan Hu

    2014-12-01

    Full Text Available Base isolation has been used as one of the most wildly accepted seismic protection systems that should substantially dissociate a superstructure from its substructure resting on a shaking ground, thereby sustainably preserving entire structures against earthquake forces as well as inside non-structural integrities. Base isolation devices can operate very effectively against near-fault (NF ground motions with large velocity pulses and permanent ground displacements. In this study, comparative advantages for using lead-rubber bearing (LRB isolation systems are mainly investigated by performing nonlinear dynamic time-history analyses with NF ground motions. The seismic responses with respects to base shears and inter-story drifts are compared according to the installation of LRB isolation systems in the frame building. The main function of the base LRB isolator is to extend the period of structural vibration by increasing lateral flexibility in the frame structure, and thus ground accelerations transferred into the superstructure can dramatically decrease. Therefore, these base isolation systems are able to achieve notable mitigation in the base shear. In addition, they make a significant contribution to reducing inter-story drifts distributed over the upper floors. Finally, the fact that seismic performance can be improved by installing isolation devices in the frame structure is emphasized herein through the results of nonlinear dynamic analyses.

  1. VizieR Online Data Catalog: Swift obs. of the superluminous SNI ASASSN-15lh (Brown+, 2016)

    Science.gov (United States)

    Brown, P. J.; Yang, Y.; Cooke, J.; Olaes, M.; Quimby, R. M.; Baade, D.; Gehrels, N.; Hoeflich, P.; Maund, J.; Mould, J.; Wang, L.; Wheeler, J. C.

    2016-11-01

    ASASSN-15lh, was discovered by the ASAS-SN on UT 2015 June 14.25 (MJD 57187.25). Observations with Swift began 2015 June 24 00:37:49 (MJD 57197). The early UVOT data were reported by Dong+ (2016Sci...351..257D). We triggered our Swift Guest Investigator programs "Ultraviolet Properties of Superluminous Supernovae over Ten Billion Years" (PI: Brown) to obtain UV/optical photometry with Swift/UVOT and "Late-time X-Rays from Superluminous Supernovae: How Hard Could it Be?" (PI: Quimby). We have reduced all of the data obtained through 2016 April 1. (2 data files).

  2. Radiation of a resonant medium excited by few-cycle optical pulses at superluminal velocity

    Science.gov (United States)

    Arkhipov, R. M.; Pakhomov, A. V.; Arkhipov, M. V.; Babushkin, I.; Tolmachev, Yu A.; Rosanov, N. N.

    2017-05-01

    Recent progress in generation of optical pulses of durations comparable to one optical cycle has presented great opportunities for studies of the fundamental processes in matter as well as time-resolved spectroscopy of ultrafast processes in nonlinear media. It opened up a new area of research in modern ultrafast nonlinear optics and led to appearance of the attosecond science. In parallel, a new research area related to emission from resonant media excited by superluminally propagating ultrashort bursts of electromagnetic radiation has been actively developed over the last few years. In this paper, we review our recent results on theoretical analysis of the Cherenkov-type radiation of a resonant medium excited by few-cycle optical pulses propagating at superluminal velocity. This situation can be realized when an electromagnetic pulse with a plane wavefront incidents on a straight string of resonant atoms or a spot of light rotates at very large angular frequency and excites a distant circular string of resonant dipoles. Theoretical analysis revealed some unusual and remarkable features of the Cherenkov radiation generated in this case. This radiation arises in a transient regime which leads to the occurrence of new frequencies in the radiation spectrum. Analysis of the characteristics of this radiation can be used for the study of the resonant structure properties. In addition, a nonlinear resonant medium excited at superluminal velocity can emit unipolar optical pulses, which can be important in ultrafast control of wave-packet dynamics of matter. Specifics of the few-cycle pulse-driven optical response of a resonant medium composed of linear and nonlinear oscillators is discussed.

  3. Complexity in the light curves and spectra of slow-evolving superluminous supernovae

    Science.gov (United States)

    Inserra, C.; Nicholl, M.; Chen, T.-W.; Jerkstrand, A.; Smartt, S. J.; Krühler, T.; Anderson, J. P.; Baltay, C.; Della Valle, M.; Fraser, M.; Gal-Yam, A.; Galbany, L.; Kankare, E.; Maguire, K.; Rabinowitz, D.; Smith, K.; Valenti, S.; Young, D. R.

    2017-07-01

    A small group of the newly discovered superluminous supernovae show broad and slow-evolving light curves. Here we present extensive observational data for the slow-evolving superluminous supernova LSQ14an, which brings this group of transients to four in total in the low-redshift Universe (z focus on the optical and near-infrared evolution during the period from 50 d up to 400 d from peak, showing that they are all fairly similar in their light curve and spectral evolution. LSQ14an shows broad, blueshifted [O III] λλ4959, 5007 lines, as well as a blueshifted [O II] λλ7320, 7330 and [Ca II] λλ7291, 7323. Furthermore, the sample of these four objects shows common features. Semi-forbidden and forbidden emission lines appear surprisingly early at 50-70 d and remain visible with almost no variation up to 400 d. The spectra remain blue out to 400 d. There are small, but discernible light-curve fluctuations in all of them. The light curve of each shows a faster decline than 56Co after 150 d and it further steepens after 300 d. We also expand our analysis presenting X-ray limits for LSQ14an and SN 2015bn and discuss their diagnostic power. These features are quite distinct from the faster evolving superluminous supernovae and are not easily explained in terms of only a variation in ejecta mass. While a central engine is still the most likely luminosity source, it appears that the ejecta structure is complex, with multiple emitting zones and at least some interaction between the expanding ejecta and surrounding material.

  4. Slowly fading super-luminous supernovae that are not pair-instability explosions.

    Science.gov (United States)

    Nicholl, M; Smartt, S J; Jerkstrand, A; Inserra, C; McCrum, M; Kotak, R; Fraser, M; Wright, D; Chen, T-W; Smith, K; Young, D R; Sim, S A; Valenti, S; Howell, D A; Bresolin, F; Kudritzki, R P; Tonry, J L; Huber, M E; Rest, A; Pastorello, A; Tomasella, L; Cappellaro, E; Benetti, S; Mattila, S; Kankare, E; Kangas, T; Leloudas, G; Sollerman, J; Taddia, F; Berger, E; Chornock, R; Narayan, G; Stubbs, C W; Foley, R J; Lunnan, R; Soderberg, A; Sanders, N; Milisavljevic, D; Margutti, R; Kirshner, R P; Elias-Rosa, N; Morales-Garoffolo, A; Taubenberger, S; Botticella, M T; Gezari, S; Urata, Y; Rodney, S; Riess, A G; Scolnic, D; Wood-Vasey, W M; Burgett, W S; Chambers, K; Flewelling, H A; Magnier, E A; Kaiser, N; Metcalfe, N; Morgan, J; Price, P A; Sweeney, W; Waters, C

    2013-10-17

    Super-luminous supernovae that radiate more than 10(44) ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1-4. Some evolve slowly, resembling models of 'pair-instability' supernovae. Such models involve stars with original masses 140-260 times that of the Sun that now have carbon-oxygen cores of 65-130 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron-positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of (56)Ni are synthesized; this isotope decays to (56)Fe via (56)Co, powering bright light curves. Such massive progenitors are expected to have formed from metal-poor gas in the early Universe. Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova. Here we report observations of two slow-to-fade super-luminous supernovae that show relatively fast rise times and blue colours, which are incompatible with pair-instability models. Their late-time light-curve and spectral similarities to supernova 2007bi call the nature of that event into question. Our early spectra closely resemble typical fast-declining super-luminous supernovae, which are not powered by radioactivity. Modelling our observations with 10-16 solar masses of magnetar-energized ejecta demonstrates the possibility of a common explosion mechanism. The lack of unambiguous nearby pair-instability events suggests that their local rate of occurrence is less than 6 × 10(-6) times that of the core-collapse rate.

  5. Light bullets in waveguide arrays: spacetime-coupling, spectral symmetry breaking and superluminal decay [Invited].

    Science.gov (United States)

    Eilenberger, Falk; Minardi, Stefano; Szameit, Alexander; Röpke, Ulrich; Kobelke, Jens; Schuster, Kay; Bartelt, Hartmut; Nolte, Stefan; Tünnermann, Andreas; Pertsch, Thomas

    2011-11-07

    We investigate the effects of the space-time coupling (STC) on the nonlinear formation and propagation of Light Bullets, spatiotemporal solitons in which dispersion and diffraction along all dimensions are balanced by nonlinearity, through periodic media with a weak transverse modulation of the refractive index, i.e. waveguide arrays. The STC arises from wavelength dependence of the strength of inter-waveguide coupling and can be tuned by variation of the array geometry. We show experimentally and numerically that the STC breaks the spectral symmetry of Light Bullets to a considerable degree and modifies their group velocity, leading to superluminal propagation when the Light Bullets decay.

  6. Emission of radiation by a resonance medium excited with a variable superluminal velocity

    Science.gov (United States)

    Arkhipov, R. M.; Pakhomov, A. V.

    2017-05-01

    Specific properties of the radiation emitted by a spatially modulated resonance medium excited by an ultrashort light pulse propagating through the medium at a variable superluminal velocity are analyzed. In so doing, frequencies different from that of the resonance transition of the medium may appear in the emission spectrum. It is demonstrated that, in contrast to an earlier studied case of medium excitation at constant velocity, variation of the excitation velocity leads to generation of a spectral continuum, the boundaries of which are determined by the range of variation of the medium-excitation velocity.

  7. Slow to superluminal light waves in thin 3D photonic crystals.

    Science.gov (United States)

    Galisteo-López, J F; Galli, M; Balestreri, A; Patrini, M; Andreani, L C; López, C

    2007-11-12

    Phase measurements on self-assembled three-dimensional photonic crystals show that the group velocity of light can flip from small positive (slow) to negative (superluminal) values in samples of a few mum size. This phenomenon takes place in a narrow spectral range around the second-order stop band and follows from coupling to weakly dispersive photonic bands associated with multiple Bragg diffraction. The observations are well accounted for by theoretical calculations of the phase delay and of photonic states in the finite-sized systems.

  8. Precise control of superluminal and slow light propagation by transverse phase modulation.

    Science.gov (United States)

    Guedes, I; Misoguti, L; Zilio, S C

    2006-06-26

    We have used a heterodyne Z-scan technique to produce both superluminal and slow light propagation in media that present either thermal or Kerr nonlinearities. The sample position determines the magnitude and sign of the group velocity and this property was used to control it, with an experimental setup much simpler than those previously reported in similar investigations. The observed effect is attributed to the transverse phase modulation produced by a focused Gaussian beam, and is capable of producing both positive and negative group velocities in the range 1.5 m/s < |upsilon(g)| < c.

  9. Visualization of superluminal pulses inside a white light cavity using plane wave spatio temporal transfer functions.

    Science.gov (United States)

    Yum, H N; Jang, Y J; Liu, X; Shahriar, M S

    2012-08-13

    In a white light cavity (WLC), the group velocity is superluminal over a finite bandwidth. For a WLC-based data buffering system we recently proposed, it is important to visualize the behavior of pulses inside such a cavity. The conventional plane wave transfer functions, valid only over space that is translationally invariant, cannot be used for the space inside WLC or any cavity, which is translationally variant. Here, we develop the plane wave spatio temporal transfer function (PWSTTF) method to solve this problem, and produce visual representations of a Gaussian input pulse incident on a WLC, for all times and positions.

  10. Superluminality effect for laser pulse propagation in medium containing nanorods under the two-photon luminescence

    Science.gov (United States)

    Trofimov, Vyacheslav A.; Lysak, Tatyana M.

    2016-10-01

    We investigate the possibility for superluminality effects at the femtosecond pulse propagation in the medium with nanorods, if second harmonic generation (SGH) and two-photon luminescence (TPL) take place. On basis of semiclassical approach, we derive a set of equations, which describe the atomic states and electric fields dynamics. We show the possibility of light acceleration and soliton formation, if nanorod aspect ratio changing occurs due to their reshaping because two photon absorption (TPA) of optical energy, and investigate TPL and SHG in the medium with nanorods under sequential one-photon absorptions.

  11. Diffraction effects in microwave propagation at the origin of superluminal behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Ranfagni, A. [Istituto di Fisica Applicata ' Nello Carrara' , Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Firenze (Italy); Ricci, A.M. [Istituto per le Telecomunicazioni e l' Elettronica della Marina Militare ' Giancarlo Vallauri' (Mariteleradar), Viale Italia 72, 57100 Livorno (Italy); Ruggeri, R. [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Sezione di Firenze, Firenze (Italy)], E-mail: rocco.ruggeri@isc.cnr.it; Agresti, A. [Dipartimento di Fisica dell' Universita di Firenze, Firenze (Italy)

    2008-10-27

    Superluminal behaviors, as evidenced by the presence of forerunners, in advanced position with respect to the main luminal peak, have been revealed in microwave propagation experiments by using a radar technique. The results are interpreted on the basis of (fast) complex waves, usually considered only in the near-field region, but still surviving beyond this limit. Consideration of further diffraction effects, as due to geometrical limitations of the experimental set-up, allows for the obtainment of a plausible description of the results.

  12. EFFECTS OF KINESIOTAPING ALONG WITH QUADRICEPS STRENGTHENING EXERCISES ON PAIN, JOINT RANGE OF MOTION AND FUNCTIONAL ACTIVITIES OF KNEE IN SUBJECTS WITH PATELLOFEMORAL OSTEOARTHRITIS

    Directory of Open Access Journals (Sweden)

    M. Harshitha

    2014-08-01

    Full Text Available Background: Patello femoral Osteoarthritis is the most common degenerative disease in older age group, causing pain, physical disability, and decreased quality of life.As many treatment options available, kinesiotaping is an efficacious treatment for management of pain & disability in patellofemoral joint osteoarthritis. Previous studies have shown that kinesiotaping as well as quadriceps strengthening significantly yields functional benefits. But there is lack of evidence revealing combined effectiveness & effects of kinesiotaping along with quadriceps strengthening in subjects with patellofemoral joint osteoarthritis. Methods: 30 subjects with symptoms of patellofemoral osteoarthritis fulfilled the inclusion criteria were randomly assigned into 2 groups of 15 in each group. Taping along with quadriceps strengthening program is compared to the quadriceps strengthening program alone. Pain were measured by Visual Analogue Scale (VAS, knee ROM were measured by Goniometer, Functional status were measured by Western Ontario McMaster Universities index (WOMAC, score. Measurements were taken pre & post intervention. Results: The results indicated that kinesiotaping along with quadriceps strengthening exercises showed there was statistically significant improvement in pain (<0.05, knee ROM (<0.05 and functional activities (<0.05 after 6 weeks compared to quadriceps strengthening alone. Conclusion: Subjects with kinesiotaping along with quadriceps strengthening showed significant improvement in reducing pain, in improving ROM & functional activities at the end of 6th week treatment when compared to subjects with patellofemoral osteoarthritis underwent quadriceps strengthening exercises alone.

  13. Tachyon motion in a black hole gravitational field

    CERN Document Server

    Lipunov, V M

    2013-01-01

    The motion of superluminal particles in the gravitational field of a non-rotating black hole is analyzed. The relativistic Hamilton-Jacobi equation is solved for particles with imaginary rest mass. It is shown that there are no stable circular orbits and generally no finite motions for tachyons in the Schwarzschild metric and that all unstable circular tachyon orbits lie in a region extending from the gravitational radius to 1.5 times that radius. The particles with speeds exceeding the speed of light are noticed to be able to escape from the space limited by the gravitational radius. The results also indicate that low-energy tachyons near a black hole may acquire higher energies and that this in turn may lead to observable effects.

  14. Extensions of Born’s rule to non-linear quantum mechanics, some of which do not imply superluminal communication

    Science.gov (United States)

    Helou, Bassam; Chen, Yanbei

    2017-08-01

    Nonlinear modifications of quantum mechanics have a troubled history. They were initially studied for many promising reasons: resolving the measurement problem, formulating a theory of quantum mechanics and gravity, and understanding the limits of standard quantum mechanics. However, certain non-linear theories have been experimentally tested and failed. More significantly, it has been shown that, in general, deterministic non-linear theories can be used for superluminal communication. We highlight another serious issue: the distribution of measurement results predicted by non-linear quantum mechanics depends on the formulation of quantum mechanics. In other words, Born’s rule cannot be uniquely extended to non-linear quantum mechanics. We present these generalizations of Born’s rule, and then examine whether some exclude superluminal communication. We determine that a large class do not allow for superluminal communication, but many lack a consistent definition. Nonetheless, we find a single extension of Born’s rule with a sound operational definition, and that does not exhibit superluminal communication. The non-linear time-evolution leading to a certain measurement event is driven by the state conditioned on measurements that lie within the past light cone of that event.

  15. EFFECTIVENESS OF NEURAL TISSUE MOBILISATION ON PAIN, PAIN FREE PASSIVE SLR RANGE OF MOTION AND FUNCTIONAL DISABILITY IN LOW BACK ACHE SUBJECTS WITH SCIATICA

    Directory of Open Access Journals (Sweden)

    V. B. Geethika

    2015-10-01

    Full Text Available Background: Low back pain is a common, benign, and self-limiting disease that affects almost all persons, with a lifetime prevalence of up to 84%. In contrast, sciatica affects only 40 % of all persons in the Western industrialized countries. In sciatica, pain radiates down the legs, below the knee along the distribution of sciatic nerve. Nerve root compression is the most common cause of sciatica. Neuro dynamics or Neural Tissue Mobilization is relatively new approach in treatment of neuro musculoskeletal disorders. The aim of the study to determine the effectiveness of Neural Tissue mobilization on pain, pain free passive SLR ROM &functional disability in LBA subjects with Sciatica. Objective of the study is to study and compare the effectiveness of Neural tissue mobilization in LBA subjects with sciatica in terms of pain, pain free SLR ROM and Oswestry Disability Index. Methods: 30 subjects were selected by simple random sampling and assigned in to Control(n=15 &Experimental group(n=15.The subjects in control group were given conventional physiotherapy and those in Experimental group were given Neural Tissue Mobilization in addition to conventional therapy. All the participants were assessed with VAS, ODI and pain free passive SLR ROM. Results: After the analysis, the results were found to be significant improvement in pain, pain free SLR ROM, ODI in both groups (p< 0.00.But there is a high significance in Experimental group when compared to control group. Conclusion: Results suggest that NEURAL TISSUE MOBILIZATION along with conventional therapy is more effective in reducing pain, decreasing disability and improving SLR ROM.

  16. Using subject-specific three-dimensional (3D) anthropometry data in digital human modelling: case study in hand motion simulation.

    Science.gov (United States)

    Tsao, Liuxing; Ma, Liang

    2016-11-01

    Digital human modelling enables ergonomists and designers to consider ergonomic concerns and design alternatives in a timely and cost-efficient manner in the early stages of design. However, the reliability of the simulation could be limited due to the percentile-based approach used in constructing the digital human model. To enhance the accuracy of the size and shape of the models, we proposed a framework to generate digital human models using three-dimensional (3D) anthropometric data. The 3D scan data from specific subjects' hands were segmented based on the estimated centres of rotation. The segments were then driven in forward kinematics to perform several functional postures. The constructed hand models were then verified, thereby validating the feasibility of the framework. The proposed framework helps generate accurate subject-specific digital human models, which can be utilised to guide product design and workspace arrangement. Practitioner Summary: Subject-specific digital human models can be constructed under the proposed framework based on three-dimensional (3D) anthropometry. This approach enables more reliable digital human simulation to guide product design and workspace arrangement.

  17. Background-dependent Lorentz violation: natural solutions to the theoretical challenges of the superluminal neutrino propagation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tianjun [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing (China); Texas A and M University, George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, College Station, TX (United States); Nanopoulos, Dimitri V. [Texas A and M University, George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, College Station, TX (United States); Houston Advanced Research Center (HARC), Astroparticle Physics Group, Woodlands, TX (United States); Academy of Athens, Division of Natural Sciences, Athens (Greece)

    2012-06-15

    To explain both the possible superluminal neutrino propagation and all the known phenomenological constraints/observations on Lorentz violation, the background-dependent Lorentz violation (BDLV) has been proposed. We study the BDLV in a model-independent way. Assuming that the Lorentz violation on the Earth is much larger than those on the interstellar scale, we automatically escape all the astrophysical constraints on Lorentz violation. For the BDLV from the effective field theory, we present a simple model and discuss the possible solutions to the theoretical challenges of the superluminal neutrino propagation such as the Bremsstrahlung effects for muon neutrinos and the pion decays. Also, we address the Lorentz violation constraints from the LEP and KamLAMD experiments. For the BDLV from the Type IIB string theory with D3-branes and D7-branes, we point out that the D3-branes are flavour blind, and all the SM particles are the conventional particles as in the traditional SM when they do not interact with the D3-branes. Thus, we not only can naturally avoid all the known phenomenological constraints on Lorentz violation, but also can naturally explain all the theoretical challenges. Interestingly, the energy-dependent photon velocities may be tested at the experiments. (orig.)

  18. Superluminal propagation and information transfer: A statistical approach in the microwave domain

    Energy Technology Data Exchange (ETDEWEB)

    Dorrah, Ahmed H., E-mail: Ahmed.Dorrah@mail.utoronto.ca; Kayili, Levent; Mojahedi, Mo

    2014-09-12

    Signal velocity is calculated in a medium with negative group delay (NGD). By accounting for the medium and the detector noise sources, the time varying probability of error at the detector [Pe(t)] is evaluated in the NGD channel and a normal dispersion channel. The scheme in which Pe(t) falls below a threshold at earlier time, implies faster information transfer. It is found that the signal velocity depends on the detector type and the relative noise strength of the detector with respect to the channel. Finally, it is shown that NGD channels can be useful in applications that are limited by the detector noise. - Highlights: • Information is described probabilistically by the temporal error probability Pe(t). • Pe(t) is calculated in superluminal medium versus a positive group delay medium. • Pe(t) is studied in three different detectors with three different noise profiles. • Signal latency is reduced in superluminal media limited by the detector noise. • Signal latency cannot be reduced in certain detection schemes despite its noise.

  19. Spectral properties of the nonspherically decaying radiation generated by a rotating superluminal source.

    Science.gov (United States)

    Ardavan, Houshang; Ardavan, Arzhang; Singleton, John; Fasel, Joseph; Schmidt, Andrea

    2008-03-01

    The focusing of the radiation generated by a polarization current with a superluminally rotating distribution pattern is of a higher order in the plane of rotation than in other directions. Consequently, our previously published [J. Opt. Soc. Am. A24, 2443 (2007)] asymptotic approximation to the value of this field outside the equatorial plane breaks down as the line of sight approaches a direction normal to the rotation axis, i.e., is nonuniform with respect to the polar angle. Here we employ an alternative asymptotic expansion to show that, though having a rate of decay with frequency (mu) that is by a factor of order mu(2/3) slower, the equatorial radiation field has the same dependence on distance as the nonspherically decaying component of the generated field in other directions: It, too, diminishes as the inverse square root of the distance from its source. We also briefly discuss the relevance of these results to the giant pulses received from pulsars: The focused, nonspherically decaying pulses that arise from a superluminal polarization current in a highly magnetized plasma have a power-law spectrum (i.e., a flux density S infinity mu(alpha)) whose index (alpha) is given by one of the values -2/3, -2, -8/3, or -4.

  20. Superluminal pulse reflection and transmission in a slab system doped with dispersive materials.

    Science.gov (United States)

    Wang, Li-Gang; Chen, Hong; Zhu, Shi-Yao

    2004-12-01

    The reflection and transmission of a pulse through a slab which is doped with two-level or three-level atoms are investigated theoretically. The doped atoms can be passive (absorptive) or active (gain). We find that both the reflected and transmitted pulses can be superluminal simultaneously for the slab doped with absorptive two-level atoms at the slab thickness equal to (2m+1) lambda(0) /4 sqrt[epsilon(b)] (where lambda(0) is the center wavelength of the incident pulse, and epsilon(b) is the background dielectric constant of the slab) or with active three-level atoms at any thickness. By adjusting the thickness or background dielectric constant of the slab, the reflected pulse can be controlled from superluminal to subluminal or vice versa for the slab doped with absorptive two-level or absorptive three-level atoms. The energy percentage in the reflected pulse can also be controlled by changing the thickness of the slab, and the doped atoms.

  1. Morphology of the nonspherically decaying radiation beam generated by a rotating superluminal source.

    Science.gov (United States)

    Ardavan, Houshang; Ardavan, Arzhang; Singleton, John; Fasel, Joseph; Schmidt, Andrea

    2007-08-01

    We consider the nonspherically decaying radiation field that is generated by a polarization current with a superluminally rotating distribution pattern in vacuum, a field that decays with the distance R(P) from its source as R(P)(-1/2), instead of R(P)(-1). It is shown (i) that the nonspherical decay of this emission remains in force at all distances from its source independently of the frequency of the radiation, (ii) that the part of the source that makes the main contribution toward the value of the nonspherically decaying field has a filamentary structure whose radial and azimuthal widths become narrower (as R(P)(-2) and R(P)(-3), respectively) the farther the observer is from the source, (iii) that the loci on which the waves emanating from this filament interfere constructively delineate a radiation subbeam that is nondiffracting in the polar direction, (iv) that the cross-sectional area of each nondiffracting subbeam increases as R(P), instead of R(P)(2), so that the requirements of conservation of energy are met by the nonspherically decaying radiation automatically, and (v) that the overall radiation beam within which the field decays nonspherically consists, in general, of the incoherent superposition of such coherent nondiffracting subbeams. These findings are related to the recent construction and use of superluminal sources in the laboratory and numerical models of the emission from them. We also briefly discuss the relevance of these results to the giant pulses received from pulsars.

  2. Superluminal radio sources - What does X-ray emission tell us?

    Science.gov (United States)

    Worrall, Diana M.

    1987-01-01

    In a study on superluminal radio sources, statistical relationships between X-ray, optical, and radio luminosities among different categories of active galactic nuclei are compared to search for common energy mechanisms. The X-ray versus optical and X-ray versus radio correlations of radio-loud QSOs and superluminal radio sources are found to be similar, arguing against a model in which the emission in only one or two of the three wave bands is relativistically boosted. A regression analysis shows that highly polarized QSOs and optically violently variable QSOs are more similar to other flat-spectrum, radio-loud QSOs than to BL Lac objects, and it is reasonable to assume that self-Compton emission dominates the X-ray emission from at least half of the sources in this class. The X-ray versus radio correlation for BL Lac objects is poor, and there is support for the hypothesis that their X-ray emission is dominated by an isotropic component which is not directly related to relativistically boosted radio emission.

  3. Effect of multiorder harmonics in a double-Raman pumped gain medium for a superluminal laser

    Science.gov (United States)

    Wang, Ye; Zhou, Zifan; Yablon, Joshua; Shahriar, Selim

    2015-05-01

    Use of a double-Raman pump applied to a three-level system is a convenient method for generating negative dispersion. When the gain at the center is high enough, such a system can be used to realize a superluminal laser, which in turn can be used to enhance the sensitivity of rotation sensors. For this condition, it is often necessary to apply strong pumps that are closely spaced in frequency. Accurate modeling of this system thus requires taking into account interference between the two pumps. We present such an analysis where we allow for an arbitrary number of harmonics that result from this interference, and investigate the behavior of the gain profile under a wide range of conditions. We also describe an experimental study of double-Raman gain in a Rb vapor cell, and find close agreement between the experimental result and the theoretical model. The technique reported here can be used in developing a quantitative model of a superluminal laser under wide-ranging conditions.

  4. Self-accelerating massive gravity: Superluminality, Cauchy surfaces, and strong coupling

    Science.gov (United States)

    Motloch, Pavel; Hu, Wayne; Joyce, Austin; Motohashi, Hayato

    2015-08-01

    Self-accelerating solutions in massive gravity provide explicit, calculable examples that exhibit the general interplay between superluminality, the well-posedness of the Cauchy problem, and strong coupling. For three particular classes of vacuum solutions, one of which is new to this work, we construct the conformal diagram for the characteristic surfaces on which isotropic stress-energy perturbations propagate. With one exception, all solutions necessarily possess spacelike characteristics, indicating perturbative superluminality. Foliating the spacetime with these surfaces gives a pathological frame where kinetic terms of the perturbations vanish, confusing the Hamiltonian counting of degrees of freedom. This frame dependence distinguishes the vanishing of kinetic terms from strong coupling of perturbations or an ill-posed Cauchy problem. We give examples where spacelike characteristics do and do not originate from a point where perturbation theory breaks down and where spacelike surfaces do or do not intersect all characteristics in the past light cone of a given observer. The global structure of spacetime also reveals issues that are unique to theories with two metrics: in all three classes of solutions, the Minkowski fiducial space fails to cover the entire de Sitter spacetime allowing worldlines of observers to end in finite proper time at determinant singularities. Characteristics run tangent to these surfaces requiring ad hoc rules to establish continuity across singularities.

  5. On the possibility of superluminal energy propagation in a hyperbolic metamaterial of metal-dielectric layers

    Science.gov (United States)

    Luan, Pi-Gang; Wu, Jie-Luen

    2018-01-01

    The energy propagation of electromagnetic fields in the effective medium of a one-dimensional photonic crystal consisting of dielectric and metallic layers is investigated. We show that the medium behaves like Drude and Lorentz medium, respectively, when the electric field is parallel and perpendicular to the layers. For arbitrary time-varying electromagnetic fields in this medium, the energy density formula is derived. We prove rigorously that the group velocity of any propagating mode obeying the hyperbolic dispersion must be slower than the speed of light in vacuum, taking into account the frequency dependence of the permittivity tensor. That is, it is not possible to have superluminal propagation in this dispersive hyperbolic medium consisting of real dielectric and metallic material layers. The propagation velocity of a wave packet is also studied numerically. This packet velocity is very close to the velocity of the propagating mode having the central frequency and central wave vector of the wave packet. When the frequency spread of the wave packet is not narrow enough, small discrepancy between these two velocities manifests, which is caused by the non-penetration effect of the evanescent modes. This work reveals that no superluminal phenomenon can happen in a dispersive anisotropic metamaterial medium made of real materials.

  6. Motion Sickness

    Science.gov (United States)

    Motion sickness is a common problem in people traveling by car, train, airplanes, and especially boats. Anyone ... children, pregnant women, and people taking certain medicines. Motion sickness can start suddenly, with a queasy feeling ...

  7. Manual therapy for the management of pain and limited range of motion in subjects with signs and symptoms of temporomandibular disorder: a systematic review of randomised controlled trials.

    Science.gov (United States)

    Calixtre, L B; Moreira, R F C; Franchini, G H; Alburquerque-Sendín, F; Oliveira, A B

    2015-11-01

    There is a lack of knowledge about the effectiveness of manual therapy (MT) on subjects with temporomandibular disorders (TMD). The aim of this systematic review is to synthetise evidence regarding the isolated effect of MT in improving maximum mouth opening (MMO) and pain in subjects with signs and symptoms of TMD. MEDLINE(®) , Cochrane, Web of Science, SciELO and EMBASE(™) electronic databases were consulted, searching for randomised controlled trials applying MT for TMD compared to other intervention, no intervention or placebo. Two authors independently extracted data, PEDro scale was used to assess risk of bias, and GRADE (Grading of Recommendations Assessment, Development and Evaluation) was applied to synthetise overall quality of the body of evidence. Treatment effect size was calculated for pain, MMO and pressure pain threshold (PPT). Eight trials were included, seven of high methodological quality. Myofascial release and massage techniques applied on the masticatory muscles are more effective than control (low to moderate evidence) but as effective as toxin botulinum injections (moderate evidence). Upper cervical spine thrust manipulation or mobilisation techniques are more effective than control (low to high evidence), while thoracic manipulations are not. There is moderate-to-high evidence that MT techniques protocols are effective. The methodological heterogeneity across trials protocols frequently contributed to decrease quality of evidence. In conclusion, there is widely varying evidence that MT improves pain, MMO and PPT in subjects with TMD signs and symptoms, depending on the technique. Further studies should consider using standardised evaluations and better study designs to strengthen clinical relevance. © 2015 John Wiley & Sons Ltd.

  8. Motion control systems

    CERN Document Server

    Sabanovic, Asif

    2011-01-01

    "Presents a unified approach to the fundamental issues in motion control, starting from the basics and moving through single degree of freedom and multi-degree of freedom systems In Motion Control Systems, Šabanovic and Ohnishi present a unified approach to very diverse issues covered in motion control systems, offering know-how accumulated through work on very diverse problems into a comprehensive, integrated approach suitable for application in high demanding high-tech products. It covers material from single degree of freedom systems to complex multi-body non-redundant and redundant systems. The discussion of the main subject is based on original research results and will give treatment of the issues in motion control in the framework of the acceleration control method with disturbance rejection technique. This allows consistent unification of different issues in motion control ranging from simple trajectory tracking to topics related to haptics and bilateral control without and with delay in the measure...

  9. Motion sickness

    NARCIS (Netherlands)

    Bles, W.; Bos, J.E.; Kruit, H.

    2000-01-01

    The number of recently published papers on motion sickness may convey the impression that motion sickness is far from being understood. The current review focusses on a concept which tends to unify the different manifestations and theories of motion sickness. The paper highlights the relations

  10. Age-Related and Degenerative Changes in the Osseous Anatomy, Alignment, and Range of Motion of the Cervical Spine: A Comparative Study of Radiographic Data From 1016 Patients With Cervical Spondylotic Myelopathy and 1230 Asymptomatic Subjects.

    Science.gov (United States)

    Machino, Masaaki; Yukawa, Yasutsugu; Imagama, Shiro; Ito, Keigo; Katayama, Yoshito; Matsumoto, Tomohiro; Inoue, Taro; Ouchida, Jun; Tomita, Keisuke; Ishiguro, Naoki; Kato, Fumihiko

    2016-03-01

    A prospective comparative study. This study aimed to establish cervical spine morphometry, alignment, and range of motion (ROM) and to clarify the impact of these age-related and degenerative changes. There are no studies that have evaluated differences in the results of cervical spine radiographs between a large series of cervical spondylotic myelopathy (CSM) patients and healthy subjects. We enrolled 1016 consecutive CSM patients who underwent laminoplasty. CSM patients were also divided based on each decade of life between the fourth and ninth decades. We also enrolled a total of 1230 healthy volunteers as asymptomatic subjects in this study. There were at least 100 men and 100 women in each decade of life between the third and eighth decades. Cervical sagittal alignment on neutral and flexion-extension views was measured by the Cobb method at C2-7. ROM was assessed by measuring the difference in alignment between flexion and extension. Cervical lordosis in the neutral position increased gradually with age in both groups. CSM patients showed significantly smaller lordotic angles compared with those shown by asymptomatic subjects within each decade. The total ROM decreased with increasing age in both groups. The total ROM of females was larger than males. The ROM of CSM patients was significantly smaller than asymptomatic subjects. The flexion ROM did not change with aging in either group. There was no significant difference in the flexion ROM between males and females in the two groups. However, the extension ROM decreased gradually in both groups. The extension ROM of CSM patients was significantly smaller than asymptomatic subjects. Age-related and degenerative changes in the cervical spine, alignment, and ROM in each decade of life were established between CSM patients and asymptomatic subjects.

  11. Ball's motion, sliding friction, and internal load distribution in a high-speed ball bearing subjected to a combined radial, thrust, and moment load, applied to the inner ring's center of mass: Numerical procedure

    Science.gov (United States)

    César Ricci, Mário

    2015-10-01

    In a companion paper of this was introduced a set of non-linear algebraic equations for ball's motion, sliding friction and internal loading distribution computation in a high-speed, single-row, angular-contact ball bearing, subjected to a known combined radial, thrust and moment load, which must be applied to the inner ring's center of mass. It was shown there that it is required the iterative solution of 9Z + 3 simultaneous non-linear equations - where Z is the number of balls - to yield exact solution for contact angles, ball attitude angles, rolling radii, normal contact deformations and axial, radial, and angular deflections of the inner ring with respect the outer ring. The Newton-Rhapson method is to be used to solve the problem. This paper deals with the numerical procedure description. The numerical results derived from the described procedure shall be published later.

  12. Reversibility of stress-echo induced ST-segment depression by long-term oral n-3 PUFA supplementation in subjects with chest pain syndrome, normal wall motion at stress-echo and normal coronary angiogram

    Directory of Open Access Journals (Sweden)

    Ziacchi Vigilio

    2004-03-01

    Full Text Available Abstract Background Normal coronary arteries may coexist with abnormal coronary and systemic endothelial function in patients with chest pain. Recent work by the renowned Pisa echo-group elegantly suggests that isolated ST-segment depression during stress-echo (SE can be used as a marker of coronary endothelial dysfunction, in the absence of stress-inducible wall motion abnormalities and in the absence of angiographically-significant coronary artery disease (CAD. The long chain n-3 polyunsaturated fatty acids (PUFAs have been reported to possess several properties that may positively influence vascular function. The present study's hypothesis is that a 4 month-course of oral supplementation with n-3 PUFAs can reverse endothelial dysfunction. Methods Subjects were selected on the basis of the following criteria: 1 reported chest pain syndrome, 2 significant ST-segment depression during an otherwise normal SE, 3 absence of angiographically-significant CAD. Subjects underwent a 4-month course of oral supplementation with commercially available n-3 PUFA, 1 g once a day. Normalization of endothelial dysfunction was defined, at the end of the supplementation period, by the absence of significant ST-segment depression during repeat SE. We tested the aforementioned hypothesis in a very small series of consecutive subjects, with the intent to produce a hypothesis-generating study. Results Seven out of the total nine subjects enrolled (77.8% had normal ST-segment during repeat SE performed after the 4 month course of therapy. Conclusions A striking rate of reversion of SE-induced ST-segment depression after oral n-3 PUFAs suggests reversion of coronary endothelial dysfunction; nonetheless these data need to be validated in larger, placebo-controlled studies.

  13. Arbitrarily copropagating superluminal and slow light by controllable one-photon detuning in trapped cold atoms.

    Science.gov (United States)

    Zhao, Yanting; Ma, Jie; Zhang, Xianli; Wang, Lirong; Xiao, Liantuan; Jia, Suotang

    2008-03-31

    Absorption spectra of cold cesium atoms confined in a magneto-optical trap are observed around the D2 transition line (6S(1/2), F=4-->6P(3/2), F'=5) with the probe laser frequency detuned near the trapping laser frequency. We observe the dispersion-like profile resulted from the stimulated Raman processes with the sub-natural linewidth, and study the behavior of the group velocity of light in trapped cold atoms. By only changing the blue and red detuning of the probe frequency from the trapping laser frequency, we are able to arbitrarily control the speed of a light pulse from subluminal to superluminal velocity.

  14. Experimental demonstration of superluminal space-to-time mapping in long period gratings.

    Science.gov (United States)

    Ashrafi, Reza; Li, Ming; Belhadj, Nezih; Dastmalchi, Mansour; LaRochelle, Sophie; Azaña, José

    2013-05-01

    We experimentally demonstrate a superluminal space-to-time mapping process in grating-assisted (GA) codirectional coupling devices, particularly fiber long period gratings (LPGs). Through this process, the grating complex (amplitude and phase) apodization profile is directly mapped into the device's temporal impulse response. In contrast to GA counterdirectional couplers, e.g., Bragg gratings, this mapping occurs with a space-to-time scaling factor that is much higher than the propagation speed of light in vacuum. This phenomenon has been used for synthesizing customized complex optical pulse data sequences with femtosecond features (3.5 Tbit/s data rate) using readily feasible fiber LPG designs, e.g., with subcentimeter resolutions.

  15. Superluminal effects and negative group delays in electronics, and their applications.

    Science.gov (United States)

    Solli, Daniel; Chiao, R Y; Hickmann, J M

    2002-11-01

    The causality principle does not forbid negative group delays of analytic signals in electronic circuits; in particular, the peak of a pulse can leave the exit port of a circuit before it enters the input port. Furthermore, pulse distortion for these "superluminal" analytic signals can be negligible in both the optical and electronic domains. Here we suggest a possible extension of these ideas to microelectronics. The underlying principle is that negative feedback can be used to produce negative group delays. Such negative group delays can be used to cancel out the positive group delays introduced by transistor latency, as well as the propagation delays due to the interconnections between transistors. Using this principle, it may be possible to speed up computer systems.

  16. BeppoSAX observation of the superluminal galactic source GRS1915+105

    Energy Technology Data Exchange (ETDEWEB)

    Feroci, Marco; Costa, Enrico; Matt, Giorgio; Belloni, Tomaso; Tavani, Marco

    1999-01-01

    We report on TOO BeppoSAX observations of the superluminal galactic source GRS1915+105 in its high flux state. The TOO was triggered by the Wide Field Cameras, and the source was then followed up for about a month with a long (100 ksec) observation and a set of nine 10 ksec snapshots. The source exhibited strong flux and spectral variability over the whole energy range (0.1-300 keV). We present here the spectral analysis carried out on a portion of the longer observation. The low energy (0.1-10 keV) spectrum taken in a phase of lack of spectral variability can be reasonably well fitted with an absorbed power law plus a multicolor blackbody. Clear evidence for a Fe K{alpha} emission line at 6.7 keV is also found, which an intensity that may be not directly correlated with continuum flux variation.

  17. Experimental observation of superluminal pulse reflection in a double-Lorentzian photonic band gap.

    Science.gov (United States)

    Longhi, S; Marano, M; Laporta, P; Belmonte, M; Crespi, P

    2002-04-01

    We report on the experimental observation of superluminal reflection of picosecond optical pulses at 1.5 microm using a specially designed 30-cm-long fiber Bragg grating (FBG) that realizes a spectral reflectivity profile given by the superposition of two closely spaced Lorentzian lines. Probing pulses of 380 ps duration tuned midway between the two Lorentzian lines are reflected without appreciable distortion with a measured peak pulse advancement of approximately 60 ps. The achievement of the negative group delay is due to the interference of the two resonance modes of the FBG structure and has a close connection to the phenomenon of negative group velocity for pulse propagation in an inverted medium possessing a doublet line.

  18. Gain-assisted slow to superluminal group velocity manipulation in nanowaveguides.

    Science.gov (United States)

    Govyadinov, Alexander A; Podolskiy, Viktor A

    2006-12-01

    We study the energy propagation in subwavelength waveguides and demonstrate that the mechanism of material gain, previously suggested for loss compensation, is also a powerful tool to manipulate dispersion and propagation characteristics of electromagnetic pulses at the nanoscale. We show theoretically that the group velocity in lossy nanowaveguides can be controlled from slow to superluminal values by the material gain and waveguide geometry and develop an analytical description of the relevant physics. We utilize the developed formalism to show that gain-assisted dispersion management can be used to control the transition between "photonic-funnel" and "photonic-compressor" regimes in tapered nanowaveguides. The phenomenon of strong modulation of group velocity in subwavelength structures can be realized in waveguides with different geometries and is present for both volume and surface modes.

  19. Resonant gain suppression and superluminal group velocity in a multilevel system.

    Science.gov (United States)

    Cui, Cui-Li; Fu, Chang-Bao; Yang, Hong; Bao, Qian-Qian; Xu, Huai-Liang; Wu, Jin-Hui

    2012-05-07

    We investigate the interaction of an open (N + 1)-level extended V-type atomic system (i.e. a closed (N + 2)-level atomic system) with N coherent laser fields and one incoherent pumping field through both analytical and numerical calculations. Our results show that the system can exhibit multiple resonant gain suppressions via perfect quantum destructive interference, which is usually believed to be absent in closed three-level V system and its extended versions involving more atomic levels, with at most N - 1 transparency windows associated with very steep anomalous dispersions occurring in the system. The superluminal group velocity of the probe-laser pulse with at most N - 1 negative values can also be generated and controlled with little gain or absorption.

  20. Time evolution of electromagnetic wave packets through superlattices: evidence for superluminal velocities.

    Science.gov (United States)

    Pereyra, Pedro; Simanjuntak, Herbert P

    2007-05-01

    We study the space-time evolution of electromagnetic wave packets through optical superlattices. We present rigorous analytical solutions describing the multiple-scattering processes of Gaussian wave packets defined in the band gap and in the resonant energy regions. Following their space-time evolution, we obtain the Maxwell equations prediction for the time spent inside the superlattice. From a close and careful observation of the reflected and transmitted parts of Gaussian packets in a photonic band gap, we conclude unambiguously that the superluminal transmission and the Hartman effect are inherent properties of the electromagnetic theory. It is also shown that the theoretical predictions for the time spent inside an optical superlattice are in good agreement with the experimental results and the phase time predictions.

  1. Stimulated generation of superluminal light pulses via four-wave mixing.

    Science.gov (United States)

    Glasser, Ryan T; Vogl, Ulrich; Lett, Paul D

    2012-04-27

    We report on the four-wave mixing of superluminal pulses, in which both the injected and generated pulses involved in the process propagate with negative group velocities. Generated pulses with negative group velocities of up to v(g)=-1/880c are demonstrated, corresponding to the generated pulse's peak exiting the 1.7 cm long medium ≈50 ns earlier than if it had propagated at the speed of light in vacuum, c. We also show that in some cases the seeded pulse may propagate with a group velocity larger than c, and that the generated conjugate pulse peak may exit the medium even earlier than the amplified seed pulse peak. We can control the group velocities of the two pulses by changing the seed detuning and the input seed power.

  2. Subluminal and superluminal terahertz radiation in metamaterials with electromagnetically induced transparency.

    Science.gov (United States)

    Bai, Zhengyang; Hang, Chao; Huang, Guoxiang

    2013-07-29

    We propose a scheme to design a new type of optical metamaterial that can mimic the functionality of four-state atomic systems of N-type energy-level configuration with electromagnetically induced transparency (EIT). We show that in such metamaterial a transition from a single EIT to a double EIT of terahertz radiation may be easily achieved by actively tuning the intensity of the infrared pump field or passively tuning the geometrical parameters of resonator structures. In addition, the group velocity of the terahertz radiation can be varied from subluminal to superluminal by changing the pump field intensity. The scheme suggested here may be used to construct chip-scale slow and fast light devices and to realize rapidly responded switching of terahertz radiation at room temperature.

  3. Light propagation from subluminal to superluminal in a three-level {lambda}-type system

    Energy Technology Data Exchange (ETDEWEB)

    Sun Hui [CREAM Group, Key Laboratory for Quantum Information and Measurements of Ministry of Education, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China); CREAM Group, Laboratory of Light Transmission Optics, South China Normal University, Guangzhou 510631 (China); Guo Hong [CREAM Group, Key Laboratory for Quantum Information and Measurements of Ministry of Education, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China) and CREAM Group, Laboratory of Light Transmission Optics, South China Normal University, Guangzhou 510631 (China)]. E-mail: hongguo@pku.edu.cn; Bai, Yanfeng [CREAM Group, Key Laboratory for Quantum Information and Measurements of Ministry of Education, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China); Han Dingan [CREAM Group, Laboratory of Light Transmission Optics, South China Normal University, Guangzhou 510631 (China); Fan Shuangli [CREAM Group, Laboratory of Light Transmission Optics, South China Normal University, Guangzhou 510631 (China); Chen Xuzong [CREAM Group, Key Laboratory for Quantum Information and Measurements of Ministry of Education, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China)

    2005-01-31

    We show that the group velocity of a weak electromagnetic pulse can be manipulated by adjusting the relative phase of the probing and the pumping fields applied to a {lambda}-type three-level system, whose two lower states are coupled by an external control magnetic field. Such control field can, in principle, cause the light propagation to be changed from subluminal to superluminal by modulating the relative phase. The same effect can be obtained by varying the intensities of the pumping and the control magnetic fields, but it is different with Agarwal's [Phys. Rev. A 64 (2001) 053809]. The effect of Doppler broadening on the dispersion is also investigated.

  4. Apparent superluminal neutrino propagation caused by nonlinear coherent interactions in matter

    Energy Technology Data Exchange (ETDEWEB)

    Brustein, Ram, E-mail: ramyb@bgu.ac.il [Department of Physics, Ben-Gurion University, Beer-Sheva 84105 (Israel); APC, 10 rue Alice Domon et Leonie Duquet, F-75205 Paris Cedex 13 (France); CAS, Ludwig-Maximilians-Universitaet Muenchen, 80333 Muenchen (Germany); Semikoz, Dmitri, E-mail: dmitri.semikoz@apc.univ-paris7.fr [APC, 10 rue Alice Domon et Leonie Duquet, F-75205 Paris Cedex 13 (France); INR RAS, 60th October Anniversary pr. 7a, 117312 Moscow (Russian Federation)

    2012-01-05

    Quantum coherence can significantly increase the strength of the forward scattering of neutrinos propagating through the Earth and interacting with matter. The index of refraction of the neutrinos propagating in a medium and hence their phase velocity is determined by the forward scattering. So, depending on the nature of the interaction of neutrinos with matter, their phase velocity can be larger than the speed of light in vacuum. We show that such effects can explain the apparent superluminal propagation of muon neutrinos found recently by the OPERA experiment. Our proposal explains why the neutrino oscillations and the propagation of neutrinos from supernova 1987A are unaffected. It can be verified by changing the amount of neutrino coherence or by changing the composition of matter in which they propagate.

  5. Sub- and superluminal kink-like waves in the kinetic limit of Maxwell-Bloch equations

    Energy Technology Data Exchange (ETDEWEB)

    Janowicz, Maciej [Instytut Fizyki Polskiej Akademii Nauk, Aleja Lotnikow 32/46, 02-668 Warszawa (Poland); Holthaus, Martin, E-mail: mjanow@ifpan.edu.pl [Institut fuer Physik, Carl von Ossietzky Universitaet, D-26111 Oldenburg (Germany)

    2011-01-14

    Running-wave solutions to three systems of partial differential equations describing wave propagation in atomic media in the kinetic limit have been obtained. Those systems include approximations to (i) standard two-level Maxwell-Bloch equations; (ii) equations describing processes with saturated absorption in three-level systems and (iii) equations describing processes with reversed saturation in four-level systems. It has been shown that in all three cases kink-like solitary waves can emerge if the dynamical equation for the intensity includes a linear contribution to the Lambert-Beer law. Those solitary waves can propagate with either sub- or superluminal velocity of the edge of the kink, and in a direction which can be either the same as or opposite to that of the carrier wave. In addition, simple qualitative information about the behaviour of waves near the wavefronts has been obtained.

  6. Switching freely between superluminal and subluminal light propagation in a monolayer MoS2 nanoresonator.

    Science.gov (United States)

    Li, Jian-Bo; Xiao, Si; Liang, Shan; He, Meng-Dong; Kim, Nam-Chol; Luo, Yongfeng; Luo, Jian-Hua; Chen, Li-Qun

    2017-06-12

    We theoretically propose a feasible scheme to advance or slow the propagation of light in a monolayer MoS2 nanoresonator (NR). The scheme allows one to easily turn on or off the fast (superluminal) and slow (subluminal) light effects and switch freely between fast and slow light propagation by only adjusting the frequency or intensity of the pump field. As the exciton interacts strongly with the phonons in MoS2, the slow light effect will appear along with a large dispersion with a very steep negative slope and a sharp absorption peak. Especially, the maximal group velocity index of the slow light in the monolayer MoS2 NR can reach two orders of magnitude larger than that in a carbon nanotube resonator. These results provide a new way to measure the exciton-phonon coupling strength and may prove useful in device applications such as optical switching and optical signal processing.

  7. Influence of nanorod absorption spectrum width on superluminality effect for laser pulse propagation

    Science.gov (United States)

    Trofimov, Vyacheslav A.; Lysak, Tatiana M.

    2016-03-01

    We investigate the influence of the finite absorption spectrum width on the soliton formation and superluminality phenomenon at a femtosecond pulse propagation in a medium with noble nanoparticles. These effects take place if a positive phase-amplitude grating is induced by laser radiation. We take into account the two-photon absorption (TPA) of laser radiation by nanorods, and time-dependent nanorod aspect ratio changing due to their melting or reshaping because of laser energy absorption, and the nanorod absorption spectrum width. On the basis of computer simulation we demonstrate these effects in a medium with positive phase-amplitude grating, induced by laser radiation, if a weak laser energy absorption takes place on the laser pulse dispersion length.

  8. Ultraviolet Light Curves of Gaia16apd in Superluminous Supernova Models

    Energy Technology Data Exchange (ETDEWEB)

    Tolstov, Alexey; Zhiglo, Andrey; Nomoto, Ken’ichi; Blinnikov, Sergei [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Sorokina, Elena [Sternberg Astronomical Institute, M.V.Lomonosov Moscow State University, 119234 Moscow (Russian Federation); Kozyreva, Alexandra, E-mail: alexey.tolstov@ipmu.jp [The Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel)

    2017-08-10

    Observations of Gaia16apd revealed extremely luminous ultraviolet emission among superluminous supernovae (SLSNe). Using radiation hydrodynamics simulations, we perform a comparison of UV light curves, color temperatures, and photospheric velocities between the most popular SLSN models: pair-instability supernova, magnetar, and interaction with circumstellar medium. We find that the interaction model is the most promising to explain the extreme UV luminosity of Gaia16apd. The differences in late-time UV emission and in color evolution found between the models can be used to link an observed SLSN event to the most appropriate model. Observations at UV wavelengths can be used to clarify the nature of SLSNe and more attention should be paid to them in future follow-up observations.

  9. Subluminal and superluminal light propagation in a superconducting quantum circuit via Josephson coupling energy

    Energy Technology Data Exchange (ETDEWEB)

    Hamedi, H.R., E-mail: hamid.r.hamedi@gmail.com

    2015-05-15

    We investigate the dispersion-group index, as well as the transmission coefficient properties of a weak probe field in a superconducting quantum circuit with a tunable V-type artificial molecule constructed by two superconducting Josephson charge qubits coupled with each other through a superconducting quantum interference device. It is realized that the slope of dispersion can be changed from negative to positive or vice versa through the ratio of the Josephson coupling energy to the capacitive coupling strength which provides an extra controlling parameter for controlling the slope of dispersion. The temporal behavior of the probe dispersion and the required switching time for switching the superluminal light propagation to the subluminal light propagation are also discussed. The results may be useful for understanding the switching feature of slow light-based systems and have potential application in optical information processing.

  10. Subluminal and superluminal light propagation in a superconducting quantum circuit via Josephson coupling energy

    Science.gov (United States)

    Hamedi, H. R.

    2015-05-01

    We investigate the dispersion-group index, as well as the transmission coefficient properties of a weak probe field in a superconducting quantum circuit with a tunable V-type artificial molecule constructed by two superconducting Josephson charge qubits coupled with each other through a superconducting quantum interference device. It is realized that the slope of dispersion can be changed from negative to positive or vice versa through the ratio of the Josephson coupling energy to the capacitive coupling strength which provides an extra controlling parameter for controlling the slope of dispersion. The temporal behavior of the probe dispersion and the required switching time for switching the superluminal light propagation to the subluminal light propagation are also discussed. The results may be useful for understanding the switching feature of slow light-based systems and have potential application in optical information processing.

  11. Holographic View of the Brain Memory Mechanism Based on Evanescent Superluminal Photons

    Directory of Open Access Journals (Sweden)

    Takaaki Musha

    2012-08-01

    Full Text Available D. Pollen and M. Trachtenberg proposed the holographic brain theory to help explain the existence of photographic memories in some people. They suggested that such individuals had more vivid memories because they somehow could access a very large region of their memory holograms. Hameroff suggested in his paper that cylindrical neuronal microtubule cavities, or centrioles, function as waveguides for the evanescent photons for quantum signal processing. The supposition is that microtubular structures of the brain function as a coherent fiber bundle set used to store holographic images, as would a fiber-optic holographic system. In this paper, the author proposes that superluminal photons propagating inside the microtubules via evanescent waves could provide the access needed to record or retrieve a quantum coherent entangled holographic memory.

  12. Detection of a possible superluminous supernova in the epoch of reionization

    Science.gov (United States)

    Mould, Jeremy; Abbott, Tim; Cooke, Jeff; Curtin, Chris; Katsiani, Antonios; Koekemoer, Anton; Tescari, Edoardo; Uddin, Syed; Wang, Lifan; Wyithe, Stuaet

    2017-04-01

    An interesting transient has been detected in one of our three Dark Energy Camera deep fields. Observations of these deep fields take advantage of the high red sensitivity of DECam on the Cerro Tololo Interamerican Observatory Blanco telescope. The survey includes the Y band with rest wavelength 1430{Å} at z = 6. Survey fields (the Prime field 0555-6130, the 16hr field 1600-75 and the SUDSS New Southern Field) are deeper in Y than other infrared surveys. They are circumpolar, allowing all night to be used efficiently, exploiting the moon tolerance of 1 micron observations to minimize conflict with the Dark Energy Survey. As an i-band dropout (meaning that the flux decrement shortward of Lyman alpha is in the i bandpass), the transient we report here is a supernova candidate with z 6, with a luminosity comparable to the brightest known current epoch superluminous supernova (i.e., 2 x 10^11 solar luminosities).

  13. Ultraviolet Light Curves of Gaia16apd in Superluminous Supernova Models

    Science.gov (United States)

    Tolstov, Alexey; Zhiglo, Andrey; Nomoto, Ken'ichi; Sorokina, Elena; Kozyreva, Alexandra; Blinnikov, Sergei

    2017-08-01

    Observations of Gaia16apd revealed extremely luminous ultraviolet emission among superluminous supernovae (SLSNe). Using radiation hydrodynamics simulations, we perform a comparison of UV light curves, color temperatures, and photospheric velocities between the most popular SLSN models: pair-instability supernova, magnetar, and interaction with circumstellar medium. We find that the interaction model is the most promising to explain the extreme UV luminosity of Gaia16apd. The differences in late-time UV emission and in color evolution found between the models can be used to link an observed SLSN event to the most appropriate model. Observations at UV wavelengths can be used to clarify the nature of SLSNe and more attention should be paid to them in future follow-up observations.

  14. Two-dimensional radiation hydrodynamics simulations of superluminous interacting supernovae of Type IIn

    Science.gov (United States)

    Vlasis, Alkiviadis; Dessart, Luc; Audit, Edouard

    2016-05-01

    Some interacting supernovae (SNe) of Type IIn show a sizeable continuum polarization suggestive of a large-scale asymmetry in the circumstellar medium (CSM) and/or the SN ejecta. Here, we extend the recent work of Dessart et al. on superluminous SNe IIn and perform axially-symmetric (I.e. 2D) multigroup radiation hydrodynamics simulations to explore the impact of an imposed large-scale density asymmetry. When the CSM is asymmetric, the latitudinal variation of the radial optical depth τ introduces a strong flux redistribution from the higher density CSM regions, where the shock luminosity is larger, towards the lower density CSM regions where photons escape more freely - this redistribution ceases when τ ≲ 1. Along directions where the CSM density is larger, the shock deceleration is stronger and its progression slower, producing a non-spherical cold-dense shell (CDS). For an oblate CSM density distribution, the photosphere (CDS) has an oblate (prolate) morphology when τ ≳ 1. When the CSM is symmetric and the ejecta asymmetric, the flux redistribution within the CSM now tends to damp the latitudinal variation of the luminosity at the shock. It then requires a larger ejecta asymmetry to produce a sizeable latitudinal variation in the emergent flux. When the interaction is between a SN ejecta and a relic disc, the luminosity boost at early times scales with the disc opening angle - forming a superluminous SN IIn this way requires an unrealistically thick disc. In contrast, interaction with a disc of modest thickness/mass can yield a power that rivals radioactive decay of a standard SN II at nebular times.

  15. Giant Kerr nonlinearity and weak-light superluminal optical solitons in a four-state atomic system with gain doublet.

    Science.gov (United States)

    Hang, Chao; Huang, Guoxiang

    2010-02-01

    We consider an active-Raman-gain scheme for realizing giant Kerr nonlinearity and superluminal optical solitons in a four-state atomic system with a gain doublet. We show that this scheme, which is fundamentally different from those based on electromagnetically induced transparency (EIT), is capable of working at room temperature and eliminating nearly all attenuation and distortion.We demonstrate that, due to the appearance of a gain spectrum hole induced by the quantum interference effect induced by a signal field, a significant enhancement of Kerr nonlinearity of probe field can be realized effectively, which can be more than ten times larger than that arrived by the EIT-based scheme with the same energy-level configuration. Based on these important features, we obtain a giant cross-phase modulation effect and hence a stable long-distance propagation of optical solitons, which have superluminal propagating velocity and very low generating power.

  16. Soliton Formation and Superluminality Effect due to Nonlinear Absorption of Femtosecond Laser Pulse Energy by the Medium Containing Nanorods

    Science.gov (United States)

    Trofimov, Vyacheslav A.; Lysak, Tatiana M.

    2016-02-01

    We investigate a femtosecond pulse propagation in a medium, containing nanorods, with taking into account the dependence of multi-photon absorption from the aspect ratio of nanorods. Nanorods melting due to the laser energy absorption leads to the non-stationary interaction of laser pulse with the medium and time-dependent nanorod aspect ratio changing. Under certain conditions, we found out the soliton-like mode of a laser pulse propagation and the superluminality effect: acceleration of light (fast light) in comparison with light propagation in a linear medium. We discuss a physical mechanism of superluminality effect for considering laser pulse propagation. Using spatio-temporal analogy, one can see the similarity between the pulse centre evolution along longitudinal coordinate and the beam centre evolution under the infrared optical radiation propagation in a cloud, or fog, which moves across the beam, with taking into account its thermal blooming.

  17. Green's function of a massless scalar field in curved space-time and superluminal phase velocity of the retarded potential

    Science.gov (United States)

    Dai, De-Chang; Stojkovic, Dejan

    2012-10-01

    We study a retarded potential solution of a massless scalar field in curved space-time. In a special ansatz for a particle at rest whose magnitude of the (scalar) charge is changing with time, we found an exact analytic solution. The solution indicates that the phase velocity of the retarded potential of a nonmoving scalar charge is position-dependent and may easily be greater than the speed of light at a given point. In the case of the Schwarzschild space-time, at the horizon, the phase velocity becomes infinitely faster than the coordinate speed of light at that point. Superluminal phase velocity is a relatively common phenomenon, with the phase velocity of the massive Klein-Gordon field as the best known example. We discuss why it is possible to have modes with superluminal phase velocity even for a massless field.

  18. DES15E2mlf: a spectroscopically confirmed superluminous supernova that exploded 3.5 Gyr after the big bang

    Science.gov (United States)

    Pan, Y.-C.; Foley, R. J.; Smith, M.; Galbany, L.; D'Andrea, C. B.; González-Gaitán, S.; Jarvis, M. J.; Kessler, R.; Kovacs, E.; Lidman, C. Nichol, R. C.; Papadopoulos, A.; Sako, M.; Sullivan, M.; Abbott, T. M. C.; Abdalla, F. B.; Annis, J.; Bechtol, K.; Benoit-Lévy, A.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; Cunha, C. E.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Doel, P.; Eifler, T. F.; Finley, D. A.; Flaugher, B.; Frieman, J.; García-Bellido, J.; Goldstein, D. A.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; James, D. J.; Kim, A. G.; Krause, E.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Marshall, J. L.; Martini, P.; Miquel, R.; Nugent, P.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Thomas, R. C.; Walker, A. R.; DES Collaboration

    2017-10-01

    We present the Dark Energy Survey (DES) discovery of DES15E2mlf, the most distant superluminous supernova (SLSN) spectroscopically confirmed to date. The light curves and Gemini spectroscopy of DES15E2mlf indicate that it is a Type I superluminous supernova (SLSN-I) at z = 1.861 (a lookback time of ˜10 Gyr) and peaking at MAB = -22.3 ± 0.1 mag. Given the high redshift, our data probe the rest-frame ultraviolet (1400-3500 Å) properties of the SN, finding velocity of the C III feature changes by ˜5600 km s- 1 over 14 d around maximum light. We find the host galaxy of DES15E2mlf has a stellar mass of 3.5^{+3.6}_{-2.4} × 109 M⊙, which is more massive than the typical SLSN-I host galaxy.

  19. The control of superluminal group velocity in a system equivalent to the Y-type four-level atomic system

    Energy Technology Data Exchange (ETDEWEB)

    Li Luming [CREAM Group, Key Laboratory for Quantum Information and Measurements of Ministry of Education, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China)]. E-mail: lilum@pku.org.cn; Guo Hong [CREAM Group, Key Laboratory for Quantum Information and Measurements of Ministry of Education, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China)]. E-mail: hongguo@pku.edu.cn; Xiao Feng [CREAM Group, Key Laboratory for Quantum Information and Measurements of Ministry of Education, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China); Peng Xiang [CREAM Group, Key Laboratory for Quantum Information and Measurements of Ministry of Education, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China); Chen Xuzong [CREAM Group, Key Laboratory for Quantum Information and Measurements of Ministry of Education, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China)]. E-mail: xuzongchen@pku.edu.cn

    2005-01-10

    We study a new way to control the superluminal group velocity of light pulse in hot atomic gases with the five-level atomic configuration. The model of an equivalent Y-type four-level is applied and shows that the light goes faster by using an additional incoherent pumping field. The experiment is performed and shows in good agreement with our theoretical predictions.

  20. Superluminal motion in NRAO 140 and a possible future method for constraining H/0/ and q/0/. [of quasars

    Science.gov (United States)

    Marscher, A. P.; Broderick, J. J.

    1982-01-01

    In order to test the prediction that the compact components in NRAO 140 should appear to separate at a speed exceeding about 4c, further VLBI observations of NRAO 140 at 2.8 cm were obtained in February 1981 and June 1981. The correlated flux densities and closure phases show clear, systematic changes compared with April 1980 data that are modeled very well by an increase in the separation of the compact components corresponding to velocities of separation ranging from 6.7c to 12c for cosmological distances and H(0) = 50 and q(0) = 0. When H(0) = 100 and q(0) = 1, the range is 2.1c to 3.7c. From these results, a prescription for the determination of upper limits to the cosmological parameters H(0) and q(0) is outlined.

  1. Comparing motion induction in lateral motion and motion in depth

    OpenAIRE

    Harris, Julie; German, KJ

    2008-01-01

    Induced motion, the apparent motion of an object when a nearby object moves, has been shown to occur in a variety of different conditions, including motion in depth. Here we explore whether similar patterns of induced motion result from induction in a lateral direction (frontoparallel motion) or induction in depth. We measured the magnitude of induced motion in a stationary target for: (a) binocularly viewed lateral motion of a pair of inducers, where the angular motion is in the same directi...

  2. Superluminal sources

    OpenAIRE

    1995-01-01

    Predictions for the apparent velocity statistics under simple beaming models are presented and compared to the observations. The potential applications for tests of unification models and for cosmology (source counts, measurements of the Hubble constant H0 and the deceleration parameter q0) are discussed. First results from a large homogeneous survey are presented. The data do not show compelling evidence for the existence of intrinsically different populations of galaxies, BL Lacertae object...

  3. OPTICAL PROPER MOTION MEASUREMENTS OF THE M87 JET: NEW RESULTS FROM THE HUBBLE SPACE TELESCOPE

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Eileen T.; Sparks, W. B.; Biretta, J. A.; Anderson, Jay; Sohn, Sangmo Tony; Van der Marel, Roeland P.; Norman, Colin [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Nakamura, Masanori, E-mail: meyer@stsci.edu [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China)

    2013-09-10

    We report new results from a Hubble Space Telescope archival program to study proper motions in the optical jet of the nearby radio galaxy M87. Using over 13 yr of archival imaging, we reach accuracies below 0.1c in measuring the apparent velocities of individual knots in the jet. We confirm previous findings of speeds up to 4.5c in the inner 6'' of the jet, and report new speeds for optical components in the outer part of the jet. We find evidence of significant motion transverse to the jet axis on the order of 0.6c in the inner jet features, and superluminal velocities parallel and transverse to the jet in the outer knot components, with an apparent ordering of velocity vectors possibly consistent with a helical jet pattern. Previous results suggested a global deceleration over the length of the jet in the form of decreasing maximum speeds of knot components from HST-1 outward, but our results suggest that superluminal speeds persist out to knot C, with large differentials in very nearby features all along the jet. We find significant apparent accelerations in directions parallel and transverse to the jet axis, along with evidence for stationary features in knots D, E, and I. These results are expected to place important constraints on detailed models of kiloparsec-scale relativistic jets.

  4. Long wavelength superluminal pulse propagation in a defect slab doped with GaAs/AlGaAs multiple quantum well nanostructure

    Science.gov (United States)

    Panahi, M.; Solookinejad, G.; Sangachin, E. Ahmadi; Asadpour, S. H.

    2015-12-01

    In this paper, long wavelength superluminal and subluminal properties of pulse propagation in a defect slab medium doped with four-level GaAs/AlGaAs multiple quantum wells (MQWs) with 15 periods of 17.5 nm GaAs wells and 15 nm Al0.3Ga0.7As barriers is theoretically discussed. It is shown that exciton spin relaxation (ESR) between excitonic states in MQWs can be used for controlling the superluminal and subluminal light transmissions and reflections at different wavelengths. We also show that reflection and transmission coefficients depend on the thickness of the slab for the resonance and nonresonance conditions. Moreover, we found that the ESR for nonresonance condition lead to superluminal light transmission and subluminal light reflection.

  5. Sunspots and Their Simple Harmonic Motion

    Science.gov (United States)

    Ribeiro, C. I.

    2013-01-01

    In this paper an example of a simple harmonic motion, the apparent motion of sunspots due to the Sun's rotation, is described, which can be used to teach this subject to high-school students. Using real images of the Sun, students can calculate the star's rotation period with the simple harmonic motion mathematical expression.

  6. Spatially Resolved MaNGA Observations of the Host Galaxy of Superluminous Supernova 2017egm

    Science.gov (United States)

    Chen, Ting-Wan; Schady, Patricia; Xiao, Lin; Eldridge, J. J.; Schweyer, Tassilo; Lee, Chien-Hsiu; Yu, Po-Chieh; Smartt, Stephen J.; Inserra, Cosimo

    2017-11-01

    Superluminous supernovae (SLSNe) are found predominantly in dwarf galaxies, indicating that their progenitors have a low metallicity. However, the most nearby SLSN to date, SN 2017egm, occurred in the spiral galaxy NGC 3191, which has a relatively high stellar mass and correspondingly high metallicity. In this Letter, we present detailed analysis of the nearby environment of SN 2017egm using MaNGA IFU data, which provides spectral data on kiloparsec scales. From the velocity map we find no evidence that SN 2017egm occurred within some intervening satellite galaxy, and at the SN position most metallicity diagnostics yield a solar and above solar metallicity (12+{log}({{O}}/{{H}})˜ 8.8{--}9.1). Additionally, we measure a small Hα equivalent width (EW) at the SN position of just 34 Å, which is one of the lowest EWs measured at any SLSN or gamma-ray burst position, and indicative of the progenitor star being comparatively old. We also compare the observed properties of NGC 3191 with other SLSN host galaxies. The solar-metallicity environment at the position of SN 2017egm presents a challenge to our theoretical understanding, and our spatially resolved spectral analysis provides further constraints on the progenitors of SLSNe.

  7. Resolving the Connection Between Superluminous Supernovae and Star Formation in Dwarf Galaxies

    Science.gov (United States)

    Lunnan, Ragnhild

    2017-08-01

    Hydrogen-poor superluminous supernovae (SLSN-I) are a rare class of transients with peak luminosities 10-100x those of ordinary SNe and unique spectra. Now a decade after their first discoveries (and even with > 50 objects found), fundamental questions like their energy sources and progenitors are still unknown. A strong clue comes from their host galaxy environments: SLSN-I show an overwhelming preference for low-mass, low-metallicity dwarf galaxies, many of which are also undergoing a starburst. Whether this is purely a metallicity effect or also require extreme star formation conditions is debated, but the latter scenario predicts a correlation between the local SN environments and the host galaxy star formation as traced by UV light. This prediction is testable with resolved HST imaging and precise astrometry, though initial studies have been inconclusive due to small number statistics. Here we propose to remedy this by obtaining resolved rest-frame UV imaging of 22 SLSN-I host galaxies from the Palomar Transient Factory SLSN sample, which will nearly triple the sample with HST imaging compared to previous studies and allow this question to be settled with robust statistics. At the current discovery rate of SLSNe, a similar improvement will not be possible until the LSST era.

  8. Superluminal space-to-time mapping in grating-assisted co-directional couplers.

    Science.gov (United States)

    Ashrafi, Reza; Li, Ming; LaRochelle, Sophie; Azaña, José

    2013-03-11

    A superluminal space-to-time mapping process is reported and numerically validated in grating-assisted (GA) co-directional couplers, e.g. fiber/waveguide long-period gratings (LPGs). We demonstrate that under weak-coupling conditions, the amplitude and phase of the grating complex apodization profile of a GA co-directional coupling device can be directly mapped into the device's temporal impulse response. In contrast to GA counter-directional couplers, this mapping occurs with a space-to-time scaling factor that is much higher than the propagation speed of light in vacuum. This phenomenon opens up a promising new avenue to overcome the fundamental time-resolution limitations of present in-fiber and on-chip optical waveform generation (shaping) and processing devices, which are intrinsically limited by the achievable spatial resolution of fabrication technologies. We numerically demonstrate the straightforward application of the phenomenon for synthesizing customized femtosecond-regime complex optical waveforms using readily feasible fiber LPG designs, e.g. with sub-centimeter resolutions.

  9. Light reversing and folding based on a superluminal flying mirror in a plasma with increasing density

    Science.gov (United States)

    Bu, Zhigang; Shen, Baifei; Huang, Shan; Li, Shun; Zhang, Hao

    2016-07-01

    A superluminal flying mirror (SFM) is proposed using the electron density spike in the tail of a wake-field excited in a plasma with an increasing density profile. The wavelength of the wake-field is shrunk in the direction of the increasing plasma density, which increases the phase velocity of the wake wave—namely the flying mirror velocity—in excess of the speed of light. The SFM exhibits some novel characteristics. When it up-shifts the light frequency, just as with a normal flying mirror, because the velocity of the SFM is quicker than light, the reflected light penetrates the electron density spike and propagates behind it. The transmitted light can gain extra energy from the wake wave so that the transmission coefficient is higher than one. Most interestingly, the reflected light may be reversed or folded in time during the reflection, if the SFM velocity gradually decreases and goes through the speed of light. The proposed SFM mechanism can provide potential applications in the production of high-frequency ultrashort pulses.

  10. Compared propagation characteristics of superluminal and slow light in SOA and EDFA based on rectangle signals

    Science.gov (United States)

    Wang, Fu; Wang, Zhi; Wu, Chongqing; Sun, Zhenchao; Mao, Yaya; Liu, Lanlan; Li, Qiang

    2015-10-01

    Based on the general mechanism of the coherent population oscillations (CPO) in the Semiconductor optical amplifiers (SOA) and Erbium doped fiber amplifiers (EDFA), the group time delay of rectangle signal propagating in the active media is deduced. Compared with the sinusoidal signal, the time delay difference between the fundamental harmonics (FHFD: fundamental harmonic fractional delay) is first investigated in detail for the rectangle signal which is more popularly used in the digital signal systems. The plenty of simulations based on the propagation equations and some experiments for the sinusoidal and rectangle signals are used to analyze the differences and evaluate the slow and superluminal light effects. Furthermore, the time delay/advance always takes place accompanying with the signal distortion, which is evaluated by the total harmonic distortion (THD). The distortion caused by the SOA is smaller than that by the EDFA. A factor Q which is defined to evaluate the trade-off between the FHFD and the THD, shows that higher input power or higher optical gain is better for optical signal processing and optical telecommunications, and the SOA is more suitable for the higher modulation frequency (>10 GHz).

  11. Superluminality phenomenon at a femtosecond laser pulse propagation in a medium containing nanorods

    Science.gov (United States)

    Trofimov, Vyacheslav A.; Lysak, Tatiana M.

    2017-04-01

    We show a possibility for soliton formation and superluminality phenomenon at a femtosecond pulse propagation in a medium with noble nanorods. These effects take place if a positive phase grating is induced by laser radiation. We take into account the dependence of two- or one-photon absorption [single-photon absorption (SPA)] on the nanorod aspect ratio and time-dependent nanorod aspect ratio changing due to nanorods reshaping (or melting) because of laser energy absorption. We demonstrate that a fast light propagation mode occurs for various detuning between wave packet carrier frequency and nanorod resonance frequency, which is a key parameter for practical observation of fast or slow light in a physical experiment. We also developed analytical approaches for explanation of laser pulse propagation peculiarities in a medium with nanorods. In particular, in the framework of nonlinear geometric optics approximation, we derived the laws for the pulse intensity and instantaneous frequency evolution if a phase grating is induced by laser radiation in a medium with SPA. We also developed an approximate analytical soliton and derived the chirped soliton amplitude, duration and homogeneous shift evolution, carrier frequency changing, and pulse chirp evolution. The results of analytical consideration are confirmed by computer simulation results.

  12. Comments on Musha's theorem that an evanescent photon in the microtubule is a superluminal particle.

    Science.gov (United States)

    Hari, Syamala D

    2014-07-01

    Takaaki Musha's research of high performance quantum computation in living systems is motivated by the theories of Penrose and Hameroff that microtubules in the brain function as quantum computers, and by those of Jibu and Yasue that the quantum states of microtubules depend upon boson condensates of evanescent photons. His work is based on the assumption that the evanescent photons described by Jibu et al. are superluminal and that they are tachyons defined and discussed by well-known physicists such as Sudarshan, Feinberg and Recami. Musha gives a brief justification for the assumption and sometimes calls it a theorem. However, the assumption is not valid because Jibu et al. stated that the evanescent photons have transmission speed smaller than that of light and that their mass is real and momentum is imaginary whereas a tachyon's mass is imaginary and momentum is real. We show here that Musha's proof of the "theorem" has errors and hence his theorem/assumption is not valid. This article is not meant to further discuss any biological aspects of the brain but only to comment on the consistency of the quantum-physical aspects of earlier work by Musha et al. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  13. Batse Triggered Observations of Galactic Superluminal Sources GROJ1655-40

    Science.gov (United States)

    Zhang, Shuang Nan

    2002-01-01

    We have analyzed multiwavelength data of galactic superluminal sources including GROJ1655-40. Currently there are thirteen X-ray binaries, in which the masses of the invisible and compact objects have been determined to be much higher than three solar masses, the well-known upper limit to the mass of a neutron star. Because no stable and compact objects are believed to exist above this limit, these compact objects are consequently considered as stellar mass black holes, though clean evidence of strong gravity effects around the assumed black holes is very rare. From optical and radio observations, their system inclination angles have been determined to range between 25 degrees and 80 degrees, but peaked between 60-70 degrees. This peak is not explained in the frame work of Newtonian gravity in these systems. However, this peak is reproduced naturally if we model the observed X-ray radiation as being produced in the accretion disks very close to the black hole horizons, where the extremely strong general and special relativistic effects, caused by the extremely strong gravity near the black hole horizons, modify the local radiation significantly as the X-rays propagate to the remote observer.

  14. Constraining the Late-Time Light Curve Behavior of Three Diverse Superluminous Supernovae

    Science.gov (United States)

    Blanchard, Peter

    2017-08-01

    The current generation of untargeted optical time-domain surveys have led to the discovery of rare and extreme transients such as superluminous supernovae (SLSNe). The mechanism that powers the hydrogen-poor Type I SLSNe remains elusive, though models such as a magnetar central engine and interaction with a hydrogen-poor circumstellar medium are both major contenders. One of the most promising observational methods available to test these models is to track the light curve evolution to very late times where model predictions diverge. We propose to obtain ACS/WFC imaging of three Type I SLSNe (PS16aqv, PS16fgt, and Gaia16apd) at greater than 500 rest-frame days after peak brightness when only HST provides the required sensitivity. These events span the diversity of decline timescales and colors exhibited by Type I SLSNe and will allow us to compare the late-time evolution of a diverse sample of events among themselves and with model predictions. These HST observation will be the latest ever of Type I SLSNe and will help to address important questions regarding their power source and diversity.

  15. Determining the explosion mechanism of a superluminous supernova through the deepest ever late-time study

    Science.gov (United States)

    Nicholl, Matt

    2017-08-01

    The superluminous supernova (SLSN) SN 2015bn is one of the three nearest objects of its kind to date, and is now the best studied. However, despite a wealth of observations within 1 year of peak light, the explosion mechanism remains elusive. Here we propose to distinguish between the popular scenarios of magnetar spin-down, circumstellar interaction and pair-instability explosion, by obtaining the latest and deepest ever images of a SLSN at around 2 years after explosion. At this phase, competing models predict robust colour differences, which we can detect in 3 orbits of HST+ACS observations (with 3 more orbits in the following cycle required for host galaxy template subtraction, also leading to a detailed host analysis). In the decade or so since the first SLSNe were discovered, no event has had the combination of late-time luminosity, proximity and a sufficiently faint host to be able to follow to such a late phase. We stress that these observations are new, timely, and only possible for 1 SLSN per decade. Furthermore, we have a robust magnitude prediction based on extensive data, and the colour test we wish to perform is powerful yet relatively straightforward, and only possible using HST.

  16. On the break down of reality at superluminal velocities, Quantum entanglement and Singularities (Complex Universe)

    Science.gov (United States)

    Estakhr, Ahmad Reza

    2017-09-01

    In the real world nothing can move faster than the speed of light. But what convinces you that our world is all real? I realized that reality break down at superluminal velocities (By studying the physics of tachyonic neutrinos), Quantum entanglement and Singularities of Black Holes, I realized that infact our world is complex and has two parts, one part of the world is real (the part that nothing can move faster than the speed of light) but the other part of the world is imaginary. z = a + ib Einstein was wrong because he thought our world is completely real (Of course he was not alone in this belief almost all physicists believe that our world is completely real) Eventually his false interpretation of reality censored imaginary part of the universe. Einstein's Second Postulate of special theory of relativity was a misleading guide to the true nature of reality. He `expected' the true nature of reality will follow to his (false) postulate, But the true nature of reality is unlike what anyone ever `expected'!. Einstein twist facts to suit his theory of relativity instead of theories to suit facts!. This is a dramatic revisions to our conception of the theory of relativity, Reality is complex but We always perceive its real part.

  17. Radiation Hydrodynamical Models for Type I Superluminous Supernovae: Constraints on Progenitors and Explosion Mechanisms

    Science.gov (United States)

    Nomoto, Ken&'Ichi; Tolstov, Alexey; Sorokina, Elena; Blinnikov, Sergei; Bersten, Melina; Suzuki, Tomoharu

    2017-11-01

    The physical origin of Type-I (hydrogen-less) superluminous supernovae (SLSNe-I), whose luminosities are 10 to 500 times higher than normal core-collapse supernovae, remains still unknown. Thanks to their brightness, SLSNe-I would be useful probes of distant Universe. For the power source of the light curves of SLSNe-I, radioactive-decays, magnetars, and circumstellar interactions have been proposed, although no definitive conclusions have been reached yet. Since most of light curve studies have been based on simplified semi-analytic models, we have constructed multi-color light curve models by means of detailed radiation hydrodynamical calculations for various mass of stars including very massive ones and large amount of mass loss. We compare the rising time, peak luminosity, width, and decline rate of the model light curves with observations of SLSNe-I and obtain constraints on their progenitors and explosion mechanisms. We particularly pay attention to the recently reported double peaks of the light curves. We discuss how to discriminate three models, relevant models parameters, their evolutionary origins, and implications for the early evolution of the Universe.

  18. Pulsational Pair-instability Model for Superluminous Supernova PTF12dam: Interaction and Radioactive Decay

    Science.gov (United States)

    Tolstov, Alexey; Nomoto, Ken'ichi; Blinnikov, Sergei; Sorokina, Elena; Quimby, Robert; Baklanov, Petr

    2017-02-01

    Being a superluminous supernova, PTF12dam can be explained by a 56Ni-powered model, a magnetar-powered model, or an interaction model. We propose that PTF12dam is a pulsational pair-instability supernova, where the outer envelope of a progenitor is ejected during the pulsations. Thus, it is powered by a double energy source: radioactive decay of 56Ni and a radiative shock in a dense circumstellar medium. To describe multicolor light curves and spectra, we use radiation-hydrodynamics calculations of the STELLA code. We found that light curves are well described in the model with 40 M⊙ ejecta and 20-40 M⊙ circumstellar medium. The ejected 56Ni mass is about 6 M⊙, which results from explosive nucleosynthesis with large explosion energy (2-3) × 1052 erg. In comparison with alternative scenarios of pair-instability supernova and magnetar-powered supernova, in the interaction model, all the observed main photometric characteristics are well reproduced: multicolor light curves, color temperatures, and photospheric velocities.

  19. Circumstellar Interaction Models for the Bolometric Light Curve of Type I Superluminous SN 2017egm

    Science.gov (United States)

    Wheeler, J. Craig; Chatzopoulos, Emmanouil; Vinkó, Jozsef; Tuminello, Richard

    2017-12-01

    We explore simple semi-analytic fits to the bolometric light curve of Gaia17biu/SN 2017egm, the most nearby hydrogen-deficient superluminous supernova (SLSN I) yet discovered. SN 2017egm has a quasi-bolometric light curve that is uncharacteristic of other SLSN I by having a nearly linear rise to maximum and decline from peak, with a very sharp transition. Magnetar models have difficulty explaining the sharp peak and may tend to be too bright 20 days after maximum. Light curves powered only by radioactive decay of 56Ni fail on similar grounds and because they demand greater nickel mass than ejecta mass. Simple models based on circumstellar interaction (CSI) do have a sharp peak corresponding to the epoch when the forward shock breaks out of the optically thick circumstellar medium or the reverse shock reaches the inside of the ejecta. We find that models based on CSI with a constant-density shell provide an interesting fit to the bolometric light curve from 15 days before to 15 days after peak light of SN 2017egm and that both magnetar and radioactive decay models fail to fit the sharp peak. Future photometric observations should easily discriminate basic CSI models from basic magnetar models. The implications of a CSI model are briefly discussed.

  20. High-order nonlinear Schrödinger equation and weak-light superluminal solitons in active Raman gain media with two control fields.

    Science.gov (United States)

    Zhu, Chengjie; Huang, Guoxiang

    2011-01-31

    We propose a scheme to generate superluminal optical solitons in a four-level atomic system with two control fields via an active Raman gain. We derive a modified nonlinear Schrödinger equation with high-order corrections contributed from linear and differential absorption, nonlinear dispersion, and delay response of nonlinear refractive index of the system. We predict various optical solitons in different regimes of system parameters, and show that these optical solitons have superluminal propagating velocity and very low generation power.

  1. Roll motion stimuli : sensory conflict, perceptual weighting and motion sickness

    NARCIS (Netherlands)

    Graaf, B. de; Bles, W.; Bos, J.E.

    1998-01-01

    In an experiment with seventeen subjects interactions of visual roll motion stimuli and vestibular body tilt stimuli were examined in determining the subjective vertical. Interindi-vidual differences in weighting the visual information were observed, but in general visual and vestibular responses

  2. THE HOST GALAXY OF THE SUPER-LUMINOUS SN 2010gx AND LIMITS ON EXPLOSIVE {sup 56}Ni PRODUCTION

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ting-Wan; Smartt, Stephen J.; Kotak, Rubina; McCrum, Matt; Fraser, Morgan [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Bresolin, Fabio; Kudritzki, Rolf-Peter [Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Pastorello, Andrea [INAF-Osservatorio Astronomico di Padova, vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Valenti, Stefano [Las Cumbres Observatory Global Telescope Network, Inc., Santa Barbara, CA 93117 (United States)

    2013-02-01

    Super-luminous supernovae have a tendency to occur in faint host galaxies which are likely to have low mass and low metallicity. While these extremely luminous explosions have been observed from z = 0.1 to 1.55, the closest explosions allow more detailed investigations of their host galaxies. We present a detailed analysis of the host galaxy of SN 2010gx (z = 0.23), one of the best studied super-luminous type Ic supernovae. The host is a dwarf galaxy (M{sub g} = -17.42 {+-} 0.17) with a high specific star formation rate. It has a remarkably low metallicity of 12 + log (O/H) = 7.5 {+-} 0.1 dex as determined from the detection of the [O III] {lambda}4363 line. This is the first reliable metallicity determination of a super-luminous stripped-envelope supernova host. We collected deep multi-epoch imaging with Gemini + GMOS between 240 and 560 days after explosion to search for any sign of radioactive {sup 56}Ni, which might provide further insights on the explosion mechanism and the progenitor's nature. We reach griz magnitudes of m{sub AB} {approx} 26, but do not detect SN 2010gx at these epochs. The limit implies that any {sup 56}Ni production was similar to or below that of SN 1998bw (a luminous type Ic SN that produced around 0.4 M{sub Sun} of {sup 56}Ni). The low volumetric rates of these supernovae ({approx}10{sup -4} of the core-collapse population) could be qualitatively matched if the explosion mechanism requires a combination of low-metallicity (below 0.2 Z{sub Sun }), high progenitor mass (>60 M{sub Sun }) and high rotation rate (fastest 10% of rotators).

  3. A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS

    Science.gov (United States)

    ICARUS Collaboration; Antonello, M.; Aprili, P.; Baibussinov, B.; Baldo Ceolin, M.; Benetti, P.; Calligarich, E.; Canci, N.; Carbonara, F.; Centro, S.; Cesana, A.; Cieslik, K.; Cline, D. B.; Cocco, A. G.; Dabrowska, A.; Dequal, D.; Dermenev, A.; Dolfini, R.; Farnese, C.; Fava, A.; Ferrari, A.; Fiorillo, G.; Gibin, D.; Gigli Berzolari, A.; Gninenko, S.; Guglielmi, A.; Haranczyk, M.; Holeczek, J.; Ivashkin, A.; Kisiel, J.; Kochanek, I.; Lagoda, J.; Mania, S.; Mannocchi, G.; Menegolli, A.; Meng, G.; Montanari, C.; Otwinowski, S.; Periale, L.; Piazzoli, A.; Picchi, P.; Pietropaolo, F.; Plonski, P.; Rappoldi, A.; Raselli, G. L.; Rossella, M.; Rubbia, C.; Sala, P. R.; Scantamburlo, E.; Scaramelli, A.; Segreto, E.; Sergiampietri, F.; Stefan, D.; Stepaniak, J.; Sulej, R.; Szarska, M.; Terrani, M.; Varanini, F.; Ventura, S.; Vignoli, C.; Wang, H.; Yang, X.; Zalewska, A.; Zaremba, K.; Cohen, A.

    2012-05-01

    The OPERA Collaboration (2011) [1] has reported evidence of superluminal νμ propagation between CERN and the LNGS. Cohen and Glashow (2011) [2] argued that such neutrinos should lose energy by producing photons and e+e- pairs, through Z0 mediated processes analogous to Cherenkov radiation. In terms of the parameter δ≡(vν2-vc2)/vc2, the OPERA result corresponds to δ≈5ṡ10-5. For this value (note that (vν-vc)/vc≈δ2≈2.5ṡ10-5) of δ, a very significant deformation of the neutrino energy spectrum and an abundant production of photons and e+e- pairs should be observed at LNGS. We present an analysis based on the 2010 and part of the 2011 data sets from the ICARUS experiment, located at Gran Sasso National Laboratory and using the same neutrino beam from CERN. We find that the rates and deposited energy distributions of neutrino events in ICARUS agree with the expectations for an unperturbed spectrum of the CERN neutrino beam, as also reported by OPERA. Our results therefore refute a superluminal interpretation of the OPERA result according to the Cohen and Glashow (2011) prediction [2] for a weak current analog to Cherenkov radiation. In a dedicated search, no superluminal Cherenkov-like e+e- pair or γ emission event has been directly observed inside the fiducial volume of the "bubble chamber-like" ICARUS TPC-LAr detector, setting the much stricter limit of δ<2.5ṡ10-8 at the 90% confidence level, comparable with the one due to the observations from the SN1987a (M.J. Longo, 1987 [4]). The observations of high energy neutrino events by Super-Kamiokande and IceCube are also pointing to a much stricter limit on δ.

  4. Switching from subluminal to superluminal light propagation via a coherent pump field in a four-level atomic system

    Energy Technology Data Exchange (ETDEWEB)

    Kuang Shangqi [College of Physics, Jilin University, Changchun 130023 (China); Key Lab of Coherent Light, Atomic and Molecular Spectroscopy, Educational Ministry of China, Changchun 130021 (China); Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Wan Rengang; Kou Jun; Jiang Yun; Gao Jinyue [College of Physics, Jilin University, Changchun 130023 (China); Key Lab of Coherent Light, Atomic and Molecular Spectroscopy, Educational Ministry of China, Changchun 130021 (China)

    2009-12-15

    We theoretically investigate the influence of a coherent pump field on the propagation of a weak light pulse of a probe field in a four-level atomic system. Due to the modulation of the pump field, the light pulse can be manipulated from subluminal to superluminal with negligible distortion. This scheme can be realized in both the ultracold and Doppler-broadened atomic systems. We also demonstrate that the spectral linewidth with an anomalous dispersion is reduced by thermal averaging; therefore, one can obtain a larger negative group refractive index in room-temperature vapor than the largest value achieved in ultracold atomic gas.

  5. Subluminal and superluminal propagation in a three-level atom in the radiative limit based on coherent population oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalo, Isabel [Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Ciudad Universitaria, 28040 Madrid (Spain)], E-mail: igonzalo@fis.ucm.es; Anton, M.A.; Carreno, F.; Calderon, Oscar G. [Escuela Universitaria de Optica, Universidad Complutense de Madrid, Arcos de Jalon, 28037 Madrid (Spain)

    2008-10-13

    We investigate a three-level atomic system in the radiative limit to control the light propagation from the subluminal regime to the superluminal one. Here the three levels are connected between them by radiative transitions. We show that depending on the decay rates, this scheme, which is based on coherent population oscillations, allows to switch from one regime to the other by changing the Rabi frequencies of the driving fields. We also show that this scheme is also capable of producing absorptionless self-phase modulation.

  6. Cherenkov emission of terahertz surface plasmon polaritons from a superluminal optical spot on a structured metal surface.

    Science.gov (United States)

    Bakunov, M I; Tsarev, M V; Hangyo, M

    2009-05-25

    We propose to launch terahertz surface plasmon polaritons on a structured metal surface by using a femtosecond laser pulse obliquely incident on a strip of an electro-optic material deposited on the surface. The laser pulse creates a nonlinear polarization that moves along the strip with a superluminal velocity and emits surface terahertz waves via the Cherenkov radiation mechanism. We calculate the radiated fields and frequency distribution of the radiated energy for a grooved perfect-conductor surface with a GaAs strip illuminated by Ti:sapphire laser. This technique can be used to perform surface terahertz spectroscopy.

  7. Group velocity manipulation in active fibers using mutually modulated cross-gain modulation: from ultraslow to superluminal propagation.

    Science.gov (United States)

    Qian, K; Zhan, L; Zhang, L; Zhu, Z Q; Peng, J S; Gu, Z C; Hu, X; Luo, S Y; Xia, Y X

    2011-06-15

    We propose and experimentally demonstrate the propagation of slow/fast light in an erbium-doped fiber (EDF) using mutually modulated cross-gain modulation. The group velocity of the light signal can be manipulated by the effect of gain cross-saturation modulation by a saturating light at an arbitrary wavelength in the gain bandwidth of the EDF. The ultraslow propagation with a small group velocity of 5.6 × 10⁻³c (c is the light speed in free space) and superluminal propagation with a negative group velocity of -1.1 × 10⁻³c has been observed under different modulation phases.

  8. Superluminal propagation in a poly-chromatically driven gain assisted four-level N-type atomic system

    Science.gov (United States)

    Amin Bacha, Bakht; Ahmad, Iftikhar; Ullah, Arif; Ali, Hazrat

    2013-10-01

    We investigate the behavior of light propagation in an N-type four-level gain assisted model (Agarwal and Dasgupta 2004 Phys. Rev. A 70 023802) under poly-chromatic pump fields. The system exhibits interesting results of multiple controllable pairs of the gain doublet profile with changes in the intensity of the control field. We observe multiple anomalous dispersive regions for superluminal propagation in the medium. A negative group velocity of -37.50 m s-1 with a negative time delay of -8 ms is observed between each gain doublet in anomalous dispersive regions. This generalized model and its predictions can be tested with existing experimental setups.

  9. Experimental demonstration of emission from a superluminal polarization current - a new class of solid-state source for MHz-THz and beyond

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, J. M. (John M.); Ardavan, A.; Ardavan, H.; Fopma, J.; Halliday, D.; Hayes, William

    2004-01-01

    We describe the Polarization Synchrotron, an experimental implementation of a superluminal (faster than light in vacuo) polarization current distribution that both oscillates and undergoes centripetal acceleration. The prototype machine produces tightly-beamed monochromatic radiation in the 100s of MHz range. The technique should also have applications as it broad-band GHz-THz source.

  10. Spatially resolved analysis of superluminous supernovae PTF 11hrq and PTF 12dam host galaxies

    Science.gov (United States)

    Cikota, Aleksandar; De Cia, Annalisa; Schulze, Steve; Vreeswijk, Paul M.; Leloudas, Giorgos; Gal-Yam, Avishay; Perley, Daniel A.; Cikota, Stefan; Kim, Sam; Patat, Ferdinando; Lunnan, Ragnhild; Quimby, Robert; Yaron, Ofer; Yan, Lin; Mazzali, Paolo A.

    2017-08-01

    Superluminous supernovae (SLSNe) are the most luminous supernovae in the Universe. They are found in extreme star-forming galaxies and are probably connected with the death of massive stars. One hallmark of very massive progenitors would be a tendency to explode in very dense, UV-bright and blue regions. In this paper, we investigate the resolved host galaxy properties of two nearby hydrogen-poor SLSNe, PTF 11hrq and PTF 12dam. For both galaxies Hubble Space Telescope multifilter images were obtained. Additionally, we perform integral field spectroscopy of the host galaxy of PTF 11hrq using the Very Large Telescope Multi Unit Spectroscopic Explorer (VLT/MUSE), and investigate the line strength, metallicity and kinematics. Neither PTF 11hrq nor PTF 12dam occurred in the bluest part of their host galaxies, although both galaxies have overall blue UV-to-optical colours. The MUSE data reveal a bright starbursting region in the host of PTF 11hrq, although far from the SN location. The SN exploded close to a region with disturbed kinematics, bluer colour, stronger [O iii] and lower metallicity. The host galaxy is likely interacting with a companion. PTF 12dam occurred in one of the brightest pixels, in a starbursting galaxy with a complex morphology and a tidal tail, where interaction is also very likely. We speculate that SLSN explosions may originate from stars generated during star formation episodes triggered by interaction. High-resolution imaging and integral field spectroscopy are fundamental for a better understanding of SLSNe explosion sites and how star formation varies across their host galaxies.

  11. Generalised Einstein mass-variation formulae: II Superluminal relative frame velocities

    Directory of Open Access Journals (Sweden)

    James M. Hill

    Full Text Available In part I of this paper we have deduced generalised Einstein mass variation formulae assuming relative frame velocities vc. We again use the notion of the residual mass m0(v which for v>c is defined by the equation m(v=m0(v[(v/c2-1]-1/2 for the actual mass m(v. The residual mass is essentially the actual mass with the Einstein factor removed, and we emphasise that we make no restrictions on m0(v. Using this formal device we deduce corresponding new mass variation formulae applicable to superluminal relative frame velocities, assuming only the extended Lorentz transformations and their consequences, and two invariants that are known to apply in special relativity. The present authors have previously speculated a dual framework such that both the rest mass m0∗ and the residual mass at infinite velocity m∞∗ (by which we mean p∞∗/c, assuming finite momentum at infinity are equally important parameters in the specification of mass as a function of its velocity, and the two arbitrary constants can be so determined. The new formulae involving two arbitrary constants may also be exploited so that the mass remains finite at the speed of light, and two distinct mass profiles are determined as functions of their velocity with the rest mass assumed to be alternatively prescribed at the origin of either frame. The two profiles so obtained (M(U,m(u and (M∗(U,m∗(u although distinct have a common ratio M(U/M∗(U=m(u/m∗(u that is a function of v>c, indicating that observable mass depends upon the frame in which the rest mass is prescribed. Keywords: Special relativity, Einstein mass variation, New formulae

  12. Studies of the Jet in Bl Lacertae. II. Superluminal Alfvén Waves

    Science.gov (United States)

    Cohen, M. H.; Meier, D. L.; Arshakian, T. G.; Clausen-Brown, E.; Homan, D. C.; Hovatta, T.; Kovalev, Y. Y.; Lister, M. L.; Pushkarev, A. B.; Richards, J. L.; Savolainen, T.

    2015-04-01

    We study the kinematics of ridge lines on the parsec-scale jet of the active galactic nucleus BL Lacertae. We show that the ridge lines display transverse patterns that move superluminally downstream, and that the moving patterns are analogous to waves on a whip. Their apparent speeds β app (units of c) range from 3.9 to 13.5, corresponding to {β }{wave}{gal}=0.981-0.998 in the galaxy frame. We show that the magnetic field in the jet is well ordered with a strong transverse component, and assume that it is helical and that the transverse patterns are Alfvén waves propagating downstream on the longitudinal component of the magnetic field. The wave-induced transverse speed of the jet is non-relativistic ({β }{tr}{gal}≲ 0.09). In 2010 the wave activity subsided and the jet then displayed a mild wiggle that had a complex oscillatory behavior. The Alfvén waves appear to be excited by changes in the position angle of the recollimation shock, in analogy to exciting a wave on a whip by shaking the handle. A simple model of the system with plasma sound speed β s = 0.3 and apparent speed of a slow MHD wave β app, S = 4 yields Lorentz factor of the beam Γbeam ∼ 4.5, pitch angle of the helix (in the beam frame) α ∼ 67°, Alfvén speed β A ∼ 0.64, and magnetosonic Mach number M ms ∼ 4.7. This describes a plasma in which the magnetic field is dominant and in a rather tight helix, and Alfvén waves are responsible for the moving transverse patterns.

  13. Generalised Einstein mass-variation formulae: II Superluminal relative frame velocities

    Science.gov (United States)

    Hill, James M.; Cox, Barry J.

    In part I of this paper we have deduced generalised Einstein mass variation formulae assuming relative frame velocities v c . We again use the notion of the residual mass m0 (v) which for v > c is defined by the equation m (v) =m0 (v)[(v / c)2 - 1 ]1/2 for the actual mass m (v) . The residual mass is essentially the actual mass with the Einstein factor removed, and we emphasise that we make no restrictions on m0 (v) . Using this formal device we deduce corresponding new mass variation formulae applicable to superluminal relative frame velocities, assuming only the extended Lorentz transformations and their consequences, and two invariants that are known to apply in special relativity. The present authors have previously speculated a dual framework such that both the rest mass m0∗ and the residual mass at infinite velocity m∞∗ (by which we mean p∞∗ / c , assuming finite momentum at infinity) are equally important parameters in the specification of mass as a function of its velocity, and the two arbitrary constants can be so determined. The new formulae involving two arbitrary constants may also be exploited so that the mass remains finite at the speed of light, and two distinct mass profiles are determined as functions of their velocity with the rest mass assumed to be alternatively prescribed at the origin of either frame. The two profiles so obtained (M (U), m (u)) and (M∗ (U),m∗ (u)) although distinct have a common ratio M (U) /M∗ (U) = m (u) /m∗ (u) that is a function of v > c , indicating that observable mass depends upon the frame in which the rest mass is prescribed.

  14. Superluminal paradox’ in wave packet propagation and its quantum mechanical resolution

    Energy Technology Data Exchange (ETDEWEB)

    Sokolovski, D., E-mail: dgsokol15@gmail.com [Department of Physical Chemistry, University of the Basque Country, Leioa, Bizkaia (Spain); IKERBASQUE, Basque Foundation for Science, 48011, Bilbao (Spain); Akhmatskaya, E. [Basque Center for Applied Mathematics (BCAM), Alameda de Mazarredo, 14 48009, Bilbao Bizkaia (Spain)

    2013-12-15

    We analyse in detail the reshaping mechanism leading to apparently ‘superluminal’ advancement of a wave packet traversing a classically forbidden region. In the coordinate representation, a barrier is shown to act as an effective beamsplitter, recombining envelopes of the freely propagating pulse with various spacial shifts. Causality ensures that none of the constituent envelopes are advanced with respect to free propagation, yet the resulting pulse is advanced due to a peculiar interference effect, similar to the one responsible for ‘anomalous’ values which occur in Aharonov’s ‘weak measurements’. In the momentum space, the effect is understood as a bandwidth phenomenon, where the incident pulse probes local, rather than global, analytical properties of the transmission amplitude T(p). The advancement is achieved when T(p) mimics locally an exponential behaviour, similar to the one occurring in Berry’s ‘superoscillations’. Seen in a broader quantum mechanical context, the ‘paradox’ is but a consequence of an attempt to obtain ‘which way?’ information without destroying the interference between the pathways of interest. This explains, to a large extent, the failure to adequately describe tunnelling in terms of a single ‘tunnelling time’. -- Highlights: •Apparent superluminality is described in the language of quantum measurements. •A barrier acts as a beamsplitter delaying copies of the initial pulse. •In the coordinate space the effect is similar to what occurs in ‘weak measurements’. •In the momentum space it relies on superoscillations in the transmission amplitude. •It is an interference effect, unlikely to be explained in simpler physical terms.

  15. Are Superluminous Supernovae and Long GRBs the Products of Dynamical Processes in Young Dense Star Clusters?

    Science.gov (United States)

    van den Heuvel, E. P. J.; Portegies Zwart, S. F.

    2013-12-01

    Superluminous supernovae (SLSNe) occur almost exclusively in small galaxies (Small/Large Magellanic Cloud (SMC/LMC)-like or smaller), and the few SLSNe observed in larger star-forming galaxies always occur close to the nuclei of their hosts. Another type of peculiar and highly energetic supernovae are the broad-line Type Ic SNe (SN Ic-BL) that are associated with long-duration gamma-ray bursts (LGRBs). Also these have a strong preference for occurring in small (SMC/LMC-like or smaller) star-forming galaxies, and in these galaxies LGRBs always occur in the brightest spots. Studies of nearby star-forming galaxies that are similar to the hosts of LGRBs show that these brightest spots are giant H II regions produced by massive dense young star clusters with many hundreds of O- and Wolf-Rayet-type stars. Such dense young clusters are also found in abundance within a few hundred parsecs from the nucleus of larger galaxies like our own. We argue that the SLSNe and the SNe Ic-BL/LGRBs are exclusive products of two types of dynamical interactions in dense young star clusters. In our model the high angular momentum of the collapsing stellar cores required for the engines of an SN Ic-BL results from the post-main-sequence mergers of dynamically produced cluster binaries with almost equal-mass components. The merger produces a critically rotating single helium star with sufficient angular momentum to produce an LGRB; the observed "metal aversion" of LGRBs is a natural consequence of the model. We argue that, on the other hand, SLSNe could be the products of runaway multiple collisions in dense clusters, and we present (and quantize) plausible scenarios of how the different types of SLSNe can be produced.

  16. Are superluminous supernovae and long GRBs the products of dynamical processes in young dense star clusters?

    Energy Technology Data Exchange (ETDEWEB)

    Van den Heuvel, E. P. J. [Astronomical Institute Anton Pannekoek, University of Amsterdam, P.O. Box 94249, 1090 GE Amsterdam (Netherlands); Portegies Zwart, S. F. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)

    2013-12-20

    Superluminous supernovae (SLSNe) occur almost exclusively in small galaxies (Small/Large Magellanic Cloud (SMC/LMC)-like or smaller), and the few SLSNe observed in larger star-forming galaxies always occur close to the nuclei of their hosts. Another type of peculiar and highly energetic supernovae are the broad-line Type Ic SNe (SN Ic-BL) that are associated with long-duration gamma-ray bursts (LGRBs). Also these have a strong preference for occurring in small (SMC/LMC-like or smaller) star-forming galaxies, and in these galaxies LGRBs always occur in the brightest spots. Studies of nearby star-forming galaxies that are similar to the hosts of LGRBs show that these brightest spots are giant H II regions produced by massive dense young star clusters with many hundreds of O- and Wolf-Rayet-type stars. Such dense young clusters are also found in abundance within a few hundred parsecs from the nucleus of larger galaxies like our own. We argue that the SLSNe and the SNe Ic-BL/LGRBs are exclusive products of two types of dynamical interactions in dense young star clusters. In our model the high angular momentum of the collapsing stellar cores required for the engines of an SN Ic-BL results from the post-main-sequence mergers of dynamically produced cluster binaries with almost equal-mass components. The merger produces a critically rotating single helium star with sufficient angular momentum to produce an LGRB; the observed 'metal aversion' of LGRBs is a natural consequence of the model. We argue that, on the other hand, SLSNe could be the products of runaway multiple collisions in dense clusters, and we present (and quantize) plausible scenarios of how the different types of SLSNe can be produced.

  17. Analyzing the Largest Spectroscopic Data Set of Hydrogen-poor Super-luminous Supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yu-Qian; Modjaz, Maryam; Bianco, Federica B., E-mail: YL1260@nyu.edu, E-mail: mmodjaz@nyu.edu [Center for Cosmology and Particle Physics, New York University, 4 Washington Place, New York, NY 10003 (United States)

    2017-08-10

    Super-luminous supernovae (SLSNe) are tremendously luminous explosions whose power sources and progenitors are highly debated. Broad-lined SNe Ic (SNe Ic-bl) are the only type of SNe that are connected with long-duration gamma-ray bursts (GRBs). Studying the spectral similarity and difference between the populations of hydrogen-poor SLSNe (SLSNe Ic) and of hydrogen-poor stripped-envelope core-collapse SNe, in particular SNe Ic and SNe Ic-bl, can provide crucial observations to test predictions of theories based on various power source models and progenitor models. In this paper, we collected all of the published optical spectra of 32 SLSNe Ic, 21 SNe Ic-bl, as well as 17 SNe Ic, quantified their spectral features, constructed average spectra, and compared them in a systematic way using new tools we have developed. We find that SLSNe Ic and SNe Ic-bl, including those connected with GRBs, have comparable widths for their spectral features and average absorption velocities at all phases. Thus, our findings strengthen the connection between SLSNe Ic and GRBs. In particular, SLSNe Ic have average Fe ii λ 5169 absorption velocities of −15,000 ± 2600 km s{sup −1} at 10 days after peak, which are higher than those of SNe Ic by ∼7000 km s{sup −1} on average. SLSNe Ic also have significantly broader Fe ii λ 5169 lines than SNe Ic. Moreover, we find that such high absorption and width velocities of SLSNe Ic may be hard to explain with the interaction model, and none of the 13 SLSNe Ic with measured absorption velocities spanning over 10 days has a convincing flat velocity evolution, which is inconsistent with the magnetar model in one dimension. Lastly, we compare SN 2011kl, the first SN connected with an ultra-long GRB, with the mean spectrum of SLSNe Ic and of SNe Ic-bl.

  18. On the Early-Time Excess Emission in Hydrogen-Poor Superluminous Supernovae

    Science.gov (United States)

    Vreeswijk, Paul M.; Leloudas, Giorgos; Gal-Yam, Avishay; De Cia, Annalisa; Perley, Daniel A.; Quimby, Robert M.; Waldman, Roni; Sullivan, Mark; Yan, Lin; Ofek, Eran O.; hide

    2017-01-01

    We present the light curves of the hydrogen-poor super-luminous supernovae (SLSNe I) PTF 12dam and iPTF 13dcc, discovered by the (intermediate) Palomar Transient Factory. Both show excess emission at early times and a slowly declining light curve at late times. The early bump in PTF 12dam is very similar in duration (approximately 10 days) and brightness relative to the main peak (23 mag fainter) compared to that observed in other SLSNe I. In contrast, the long-duration (greater than 30 days) early excess emission in iPTF 13dcc, whose brightness competes with that of the main peak, appears to be of a different nature. We construct bolometric light curves for both targets, and fit a variety of light-curve models to both the early bump and main peak in an attempt to understand the nature of these explosions. Even though the slope of the late-time decline in the light curves of both SLSNe is suggestively close to that expected from the radioactive decay of 56Ni and 56Co, the amount of nickel required to power the full light curves is too large considering the estimated ejecta mass. The magnetar model including an increasing escape fraction provides a reasonable description of the PTF 12dam observations. However, neither the basic nor the double-peaked magnetar model is capable of reproducing the light curve of iPTF 13dcc. A model combining a shock breakout in an extended envelope with late-time magnetar energy injection provides a reasonable fit to the iPTF 13dcc observations. Finally, we find that the light curves of both PTF 12dam and iPTF 13dcc can be adequately fit with the model involving interaction with the circumstellar medium.

  19. Analyzing the Largest Spectroscopic Data Set of Hydrogen-poor Super-luminous Supernovae

    Science.gov (United States)

    Liu, Yu-Qian; Modjaz, Maryam; Bianco, Federica B.

    2017-08-01

    Super-luminous supernovae (SLSNe) are tremendously luminous explosions whose power sources and progenitors are highly debated. Broad-lined SNe Ic (SNe Ic-bl) are the only type of SNe that are connected with long-duration gamma-ray bursts (GRBs). Studying the spectral similarity and difference between the populations of hydrogen-poor SLSNe (SLSNe Ic) and of hydrogen-poor stripped-envelope core-collapse SNe, in particular SNe Ic and SNe Ic-bl, can provide crucial observations to test predictions of theories based on various power source models and progenitor models. In this paper, we collected all of the published optical spectra of 32 SLSNe Ic, 21 SNe Ic-bl, as well as 17 SNe Ic, quantified their spectral features, constructed average spectra, and compared them in a systematic way using new tools we have developed. We find that SLSNe Ic and SNe Ic-bl, including those connected with GRBs, have comparable widths for their spectral features and average absorption velocities at all phases. Thus, our findings strengthen the connection between SLSNe Ic and GRBs. In particular, SLSNe Ic have average Fe ii λ5169 absorption velocities of -15,000 ± 2600 km s-1 at 10 days after peak, which are higher than those of SNe Ic by ˜7000 km s-1 on average. SLSNe Ic also have significantly broader Fe ii λ5169 lines than SNe Ic. Moreover, we find that such high absorption and width velocities of SLSNe Ic may be hard to explain with the interaction model, and none of the 13 SLSNe Ic with measured absorption velocities spanning over 10 days has a convincing flat velocity evolution, which is inconsistent with the magnetar model in one dimension. Lastly, we compare SN 2011kl, the first SN connected with an ultra-long GRB, with the mean spectrum of SLSNe Ic and of SNe Ic-bl.

  20. On the Early-time Excess Emission in Hydrogen-poor Superluminous Supernovae

    Science.gov (United States)

    Vreeswijk, Paul M.; Leloudas, Giorgos; Gal-Yam, Avishay; De Cia, Annalisa; Perley, Daniel A.; Quimby, Robert M.; Waldman, Roni; Sullivan, Mark; Yan, Lin; Ofek, Eran O.; Fremling, Christoffer; Taddia, Francesco; Sollerman, Jesper; Valenti, Stefano; Arcavi, Iair; Howell, D. Andrew; Filippenko, Alexei V.; Cenko, S. Bradley; Yaron, Ofer; Kasliwal, Mansi M.; Cao, Yi; Ben-Ami, Sagi; Horesh, Assaf; Rubin, Adam; Lunnan, Ragnhild; Nugent, Peter E.; Laher, Russ; Rebbapragada, Umaa D.; Woźniak, Przemysław; Kulkarni, Shrinivas R.

    2017-01-01

    We present the light curves of the hydrogen-poor superluminous supernovae (SLSNe I) PTF 12dam and iPTF 13dcc, discovered by the (intermediate) Palomar Transient Factory. Both show excess emission at early times and a slowly declining light curve at late times. The early bump in PTF 12dam is very similar in duration (˜10 days) and brightness relative to the main peak (2-3 mag fainter) compared to that observed in other SLSNe I. In contrast, the long-duration (>30 days) early excess emission in iPTF 13dcc, whose brightness competes with that of the main peak, appears to be of a different nature. We construct bolometric light curves for both targets, and fit a variety of light-curve models to both the early bump and main peak in an attempt to understand the nature of these explosions. Even though the slope of the late-time decline in the light curves of both SLSNe is suggestively close to that expected from the radioactive decay of 56Ni and 56Co, the amount of nickel required to power the full light curves is too large considering the estimated ejecta mass. The magnetar model including an increasing escape fraction provides a reasonable description of the PTF 12dam observations. However, neither the basic nor the double-peaked magnetar model is capable of reproducing the light curve of iPTF 13dcc. A model combining a shock breakout in an extended envelope with late-time magnetar energy injection provides a reasonable fit to the iPTF 13dcc observations. Finally, we find that the light curves of both PTF 12dam and iPTF 13dcc can be adequately fit with the model involving interaction with the circumstellar medium.

  1. Superluminal pulse propagation and amplification without inversion of microwave radiation via four-wave mixing in superconducting phase quantum circuits

    Science.gov (United States)

    Amini Sabegh, Z.; Vafafard, A.; Maleki, M. A.; Mahmoudi, M.

    2015-08-01

    We study the interaction of the microwave fields with an array of superconducting phase quantum circuits. It is shown that the different four-level configurations i.e. cascade, N-type, diamond, Y-type and inverted Y-type systems can be obtained in the superconducting phase quantum circuits by keeping the third order of the Josephson junction potential expansion whereas by dropping the third order term, just the cascade configuration can be established. We study the propagation and amplification of a microwave field in a four-level cascade quantum system, which is realized in an array of superconducting phase quantum circuits. We find that by increasing the microwave pump tones feeding the system, the normal dispersion switches to the anomalous and the gain-assisted superluminal microwave propagation is obtained in an array of many superconducting phase quantum circuits. Moreover, it is demonstrated that the stimulated microwave field is generated via four-wave mixing without any inversion population in the energy levels of the system (amplification without inversion) and the group velocity of the generated pulse can be controlled by the external oscillating magnetic fluxes. We also show that in some special set of parameters, the absorption-free superluminal generated microwave propagation is obtained in superconducting phase quantum circuit system.

  2. Net electron energy gain induced by superluminal phase velocity and subluminal group velocity of a laser in a plasma channel

    Science.gov (United States)

    Cheng, Li-Hong; Yao, Zheng-Wei; Zhang, Xiao-Bo; Xue, Ju-Kui

    2017-08-01

    We examine electron dynamics induced by laser-plasma interaction in a two-dimensional plasma channel, taking into action the laser phase velocity as well as the group velocity. The coupled effects of phase velocity, group velocity, and plasma channel on electron dynamics are discussed in detail. The superluminal phase velocity and the corresponding subluminal group velocity of the laser result in rich and complex electron dynamics, which are depicted in the plane of the phase velocity and plasma charge density. For weak superluminosity of the phase velocity, the effects of the phase velocity and the group velocity can be neglected. For moderate superluminosity of the phase velocity, a cross-over region can exist, where the highly energetic electron could be found and the net energy gain is several times greater than the energy gain in vacuum. For strong superluminosity of the phase velocity, the dephasing rate increases and thus limits the electron energy gain from the laser. However, the asymmetric laser pulse, attributed by the superluminal phase velocity and the subluminal group velocity, results in the electron getting adjustable net energy gain from the laser. The electron oscillations are no longer limited by the charge density threshold and the electron can always get net energy from the laser. These electron dynamics can also be modified by adjusting the polarization of the laser.

  3. Fano line-shape control and superluminal light using cavity quantum electrodynamics with a partially transmitting element

    Science.gov (United States)

    Li, Jiahua; Yu, Rong; Liu, Jiuyang; Ding, Chunling; Wu, Ying

    2016-05-01

    We study the probe-field transmission in cavity quantum electrodynamics (cavity-QED) systems with a partially transmitting element (PTE), where the PTE is used to control and tune the amplitude of the weak probe field propagating along a single waveguide channel in the structure. We derive analytic formulas utilized to determine the transmission coefficient of the probe field within the framework of quantum optics. Using experimentally accessible parameters, it is clearly shown that the asymmetric Fano-resonance line shape can be formed and manipulated by means of the added PTE. Furthermore, we reveal that there exists superluminal light with large intensity transmission in the transport spectrum of the waveguide-coupled cavity-QED system. This superluminal-light propagation effect, which exhibits the anomalous phase shift and is characterized by the negative group delay, can be enhanced by properly choosing the system parameters. The obtained results may be used for designing switching, modulation, and sensing for nanophotonic applications and ultrafast on-chip signal processing in telecom applications.

  4. Helmholtz theorem and the v-gauge in the problem of superluminal and instantaneous signals in classical electrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Chubykalo, Andrew; Espinoza, Augusto; Flores, Rolando Alvarado; Rodriguez, Alejandro Gutierrez [Universidad Autonoma de Zacatecas (Mexico). Unidad Academica de Fisica

    2011-07-01

    In this work we substantiate the applying of the Helmholtz vector decomposition theorem (H-theorem) to vector fields in classical electrodynamics. Using the H-theorem, within the framework of the two-parameter Lorentz-like gauge (so called V-gauge), we show that two kinds of magnetic vector potentials exist: one of them (solenoidal) can act exclusively with the velocity of light C and the other one (irrotational) with an arbitrary finite velocity V (including a velocity more than C). We show also that the irrotational component of the electric field has a physical meaning and can propagate exclusively instantaneously. We provide a theoretical rationale (within the framework of classical electrodynamics) of a series of well-known recent experiments, which detected superluminal signals. Finally, we affirm that applying the Helmholtz theorem to classical electrodynamics allows to conclude that in classical electrodynamics so called instantaneous action at a distance with the infinite velocity of interaction can take place as well as (within the framework of the v-gauge-theory) the superluminal action with a finite velocity of interaction. (author)

  5. Motion correction in MRI of the brain

    Science.gov (United States)

    Godenschweger, F; Kägebein, U; Stucht, D; Yarach, U; Sciarra, A; Yakupov, R; Lüsebrink, F; Schulze, P; Speck, O

    2016-01-01

    Subject motion in MRI is a relevant problem in the daily clinical routine as well as in scientific studies. Since the beginning of clinical use of MRI, many research groups have developed methods to suppress or correct motion artefacts. This review focuses on rigid body motion correction of head and brain MRI and its application in diagnosis and research. It explains the sources and types of motion and related artefacts, classifies and describes existing techniques for motion detection, compensation and correction and lists established and experimental approaches. Retrospective motion correction modifies the MR image data during the reconstruction, while prospective motion correction performs an adaptive update of the data acquisition. Differences, benefits and drawbacks of different motion correction methods are discussed. PMID:26864183

  6. Limiting Superluminal Electron and Neutrino Velocities Using the 2010 Crab Nebula Flare and the IceCube PeV Neutrino Events

    Science.gov (United States)

    Stecker, Floyd W.

    2014-01-01

    The observation of two PetaelectronVolt (PeV)-scale neutrino events reported by Ice Cube allows one to place constraints on Lorentz invariance violation (LIV) in the neutrino sector. After first arguing that at least one of the PetaelectronVolt IceCube events was of extragalactic origin, I derive an upper limit for the difference between putative superluminal neutrino and electron velocities of less than or equal to approximately 5.6 x 10(exp -19) in units where c = 1, confirming that the observed PetaelectronVolt neutrinos could have reached Earth from extragalactic sources. I further derive a new constraint on the superluminal electron velocity, obtained from the observation of synchrotron radiation from the Crab Nebula flare of September, 2010. The inference that the greater than 1 GigaelectronVolt gamma-rays from synchrotron emission in the flare were produced by electrons of energy up to approx. 5.1 PetaelectronVolt indicates the nonoccurrence of vacuum Cerenkov radiation by these electrons. This implies a new, strong constraint on superluminal electron velocities delta(sub e) less than or equal to approximately 5 x 10(exp -21). It immediately follows that one then obtains an upper limit on the superluminal neutrino velocity alone of delta(sub v) less than or equal to approximately 5.6 x 10(exp -19), many orders of magnitude better than the time-of-flight constraint from the SN1987A neutrino burst. However, if the electrons are subluminal the constraint on the absolute value of delta(sub e) less than or equal to approximately 8 x 10(exp -17), obtained from the Crab Nebula gamma-ray spectrum, places a weaker constraint on superluminal neutrino velocity of delta(sub v) less than or equal to approximately 8 x 10(exp -17).

  7. Visual and Non-Visual Contributions to the Perception of Object Motion during Self-Motion

    Science.gov (United States)

    Fajen, Brett R.; Matthis, Jonathan S.

    2013-01-01

    Many locomotor tasks involve interactions with moving objects. When observer (i.e., self-)motion is accompanied by object motion, the optic flow field includes a component due to self-motion and a component due to object motion. For moving observers to perceive the movement of other objects relative to the stationary environment, the visual system could recover the object-motion component – that is, it could factor out the influence of self-motion. In principle, this could be achieved using visual self-motion information, non-visual self-motion information, or a combination of both. In this study, we report evidence that visual information about the speed (Experiment 1) and direction (Experiment 2) of self-motion plays a role in recovering the object-motion component even when non-visual self-motion information is also available. However, the magnitude of the effect was less than one would expect if subjects relied entirely on visual self-motion information. Taken together with previous studies, we conclude that when self-motion is real and actively generated, both visual and non-visual self-motion information contribute to the perception of object motion. We also consider the possible role of this process in visually guided interception and avoidance of moving objects. PMID:23408983

  8. Far-UV HST Spectroscopy of An Unusual Hydrogen Poor Superluminous Supernova: SN2017egm

    Science.gov (United States)

    Yan, Lin; Perley, Daniel; Quimby, Robert; De Cia, Annalisa; Brown, Peter

    2018-01-01

    SN2017egm is the closest (z=0.03) H-poor superluminous supernova (SLSN-I) detected to date, and a rare example of an SLSN in a massive and metal-rich galaxy. Here we present the HST UV & optical spectra covering (1000 - 5500)A taken at +3day relative to the peak. Our data reveal two sets of absorption systems, separated by 235km/s, at redshifts matching NGC3191 and its companion galaxy 73arcsec apart. A weakly damped Lyman-alpha absorption line (sub-DLA) is also detected with a total column density of N(HI) ~(6^{+3}_{-1})e+19}cm^-2. This is an order of magnitude smaller than HI column densities in nearby massive disk galaxies (>10^{10}Msun) and suggests that SN2017egm is on the near side of the galaxy mid-plane and its local environment on a 5 parsec is highly ionized due to photo-ionization by SN2017egm. The low HI column density also implies a low host dust extinction for SN2017egm, E(B-V) of 0.007. We constrain the gas metallicity using unsaturated absorption lines (SII1253 and FeII1629). Taking into account of ionization and dust depletion corrections, we find that the metal abundances for both sets of absorbers are close to be 1Zsun or more, and our data can rule out metallicity below 0.5Zsun. We make a comparative analysis of high-quality, early-time UV spectra of four SLSNe-I, SN2017egm, Gaia16apd, PTF12dam and iPTF13ajg. We find that although they have similar blackbody temperatures, the shape of their UV continuum (1000 - 3000A) varies significantly, with the 1400A to 2800A continuum ratio of 1.5 for Gaia16apd to 0.4 for iPTF13ajg. This variation can not be explained by the magnetar power alone as claimed before, and is likely to do with sizes and compositions of the photosphere. We conclude that a single UV SED is not sufficient when modeling SLSN-I light curves. In addition, there are a common set of seven UV absorption features between 1000A and 2800A, including three new ones in the far-UV spectra of SN2017egm and Gaia16apd. Using syn++ synthetic

  9. A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS

    Energy Technology Data Exchange (ETDEWEB)

    Antonello, M.; Aprili, P. [Laboratori Nazionali del Gran Sasso dell' INFN, Assergi (AQ) (Italy); Baibussinov, B.; Baldo Ceolin, M. [Dipartimento di Fisica e INFN, Universita di Padova, Via Marzolo 8, I-35131 Padova (Italy); Benetti, P.; Calligarich, E. [Dipartimento di Fisica Nucleare e Teorica e INFN, Universita di Pavia, Via Bassi 6, I-27100 Pavia (Italy); Canci, N. [Laboratori Nazionali del Gran Sasso dell' INFN, Assergi (AQ) (Italy); Carbonara, F. [Dipartimento di Scienze Fisiche, INFN e Universita Federico II, Napoli (Italy); Centro, S. [Dipartimento di Fisica e INFN, Universita di Padova, Via Marzolo 8, I-35131 Padova (Italy); Cesana, A. [INFN, Sezione di Milano e Politecnico, Via Celoria 16, I-20133 Milano (Italy); Cieslik, K. [The Henryk Niewodniczanski, Institute of Nuclear Physics, Polish Academy of Science, Krakow (Poland); Cline, D.B. [Department of Physics and Astronomy, University of California, Los Angeles, CA (United States); Cocco, A.G. [Dipartimento di Scienze Fisiche, INFN e Universita Federico II, Napoli (Italy); Dabrowska, A. [The Henryk Niewodniczanski, Institute of Nuclear Physics, Polish Academy of Science, Krakow (Poland); Dequal, D. [Dipartimento di Fisica e INFN, Universita di Padova, Via Marzolo 8, I-35131 Padova (Italy); Dermenev, A. [INR RAS, prospekt 60-letiya Oktyabrya 7a, Moscow 117312 (Russian Federation); Dolfini, R. [Dipartimento di Fisica Nucleare e Teorica e INFN, Universita di Pavia, Via Bassi 6, I-27100 Pavia (Italy); Farnese, C.; Fava, A. [Dipartimento di Fisica e INFN, Universita di Padova, Via Marzolo 8, I-35131 Padova (Italy); Ferrari, A., E-mail: alfredo.ferrari@cern.ch [CERN, CH-1211 Geneve 23 (Switzerland); and others

    2012-05-15

    The OPERA Collaboration (2011) has reported evidence of superluminal {nu}{sub {mu}} propagation between CERN and the LNGS. Cohen and Glashow (2011) argued that such neutrinos should lose energy by producing photons and e{sup +}e{sup -} pairs, through Z{sup 0} mediated processes analogous to Cherenkov radiation. In terms of the parameter {delta}{identical_to}(v{sub {nu}}{sup 2}-v{sub c}{sup 2})/v{sub c}{sup 2}, the OPERA result corresponds to {delta}=5 Dot-Operator 10{sup -5}. For this value (note that (v{sub {nu}}-v{sub c})/v{sub c}={delta})/2 =2.5 Dot-Operator 10{sup -5}) of {delta}, a very significant deformation of the neutrino energy spectrum and an abundant production of photons and e{sup +}e{sup -} pairs should be observed at LNGS. We present an analysis based on the 2010 and part of the 2011 data sets from the ICARUS experiment, located at Gran Sasso National Laboratory and using the same neutrino beam from CERN. We find that the rates and deposited energy distributions of neutrino events in ICARUS agree with the expectations for an unperturbed spectrum of the CERN neutrino beam, as also reported by OPERA. Our results therefore refute a superluminal interpretation of the OPERA result according to the Cohen and Glashow (2011) prediction for a weak current analog to Cherenkov radiation. In a dedicated search, no superluminal Cherenkov-like e{sup +}e{sup -} pair or {gamma} emission event has been directly observed inside the fiducial volume of the 'bubble chamber-like' ICARUS TPC-LAr detector, setting the much stricter limit of {delta}<2.5 Dot-Operator 10{sup -8} at the 90% confidence level, comparable with the one due to the observations from the SN1987a (M.J. Longo, 1987 ). The observations of high energy neutrino events by Super-Kamiokande and IceCube are also pointing to a much stricter limit on {delta}.

  10. Auditory motion capturing ambiguous visual motion

    Directory of Open Access Journals (Sweden)

    Arjen eAlink

    2012-01-01

    Full Text Available In this study, it is demonstrated that moving sounds have an effect on the direction in which one sees visual stimuli move. During the main experiment sounds were presented consecutively at four speaker locations inducing left- or rightwards auditory apparent motion. On the path of auditory apparent motion, visual apparent motion stimuli were presented with a high degree of directional ambiguity. The main outcome of this experiment is that our participants perceived visual apparent motion stimuli that were ambiguous (equally likely to be perceived as moving left- or rightwards more often as moving in the same direction than in the opposite direction of auditory apparent motion. During the control experiment we replicated this finding and found no effect of sound motion direction on eye movements. This indicates that auditory motion can capture our visual motion percept when visual motion direction is insufficiently determinate without affecting eye movements.

  11. Influence of Visual Motion, Suggestion, and Illusory Motion on Self-Motion Perception in the Horizontal Plane.

    Directory of Open Access Journals (Sweden)

    Steven David Rosenblatt

    Full Text Available A moving visual field can induce the feeling of self-motion or vection. Illusory motion from static repeated asymmetric patterns creates a compelling visual motion stimulus, but it is unclear if such illusory motion can induce a feeling of self-motion or alter self-motion perception. In these experiments, human subjects reported the perceived direction of self-motion for sway translation and yaw rotation at the end of a period of viewing set visual stimuli coordinated with varying inertial stimuli. This tested the hypothesis that illusory visual motion would influence self-motion perception in the horizontal plane. Trials were arranged into 5 blocks based on stimulus type: moving star field with yaw rotation, moving star field with sway translation, illusory motion with yaw, illusory motion with sway, and static arrows with sway. Static arrows were used to evaluate the effect of cognitive suggestion on self-motion perception. Each trial had a control condition; the illusory motion controls were altered versions of the experimental image, which removed the illusory motion effect. For the moving visual stimulus, controls were carried out in a dark room. With the arrow visual stimulus, controls were a gray screen. In blocks containing a visual stimulus there was an 8s viewing interval with the inertial stimulus occurring over the final 1s. This allowed measurement of the visual illusion perception using objective methods. When no visual stimulus was present, only the 1s motion stimulus was presented. Eight women and five men (mean age 37 participated. To assess for a shift in self-motion perception, the effect of each visual stimulus on the self-motion stimulus (cm/s at which subjects were equally likely to report motion in either direction was measured. Significant effects were seen for moving star fields for both translation (p = 0.001 and rotation (p0.1 for both. Thus, although a true moving visual field can induce self-motion, results of this

  12. Motion control report

    CERN Document Server

    2013-01-01

    Please note this is a short discount publication. In today's manufacturing environment, Motion Control plays a major role in virtually every project.The Motion Control Report provides a comprehensive overview of the technology of Motion Control:* Design Considerations* Technologies* Methods to Control Motion* Examples of Motion Control in Systems* A Detailed Vendors List

  13. Superluminal sheath-field expansion and fast-electron-beam divergence measurements in laser-solid interactions.

    Science.gov (United States)

    Ridgers, C P; Sherlock, M; Evans, R G; Robinson, A P L; Kingham, R J

    2011-03-01

    We show that including a sufficient description of the target's rear surface significantly affects the interpretation of a wide range of laser-solid experiments. A simple Debye sheath model will be shown to be adequate. From this the sheath field responsible for ion acceleration has been shown to expand at superluminal speeds, leading to very large ion-emission regions on the target's rear surface; a new explanation for the dynamics of the ion-accelerating sheath field accounts for this observation and demonstrates the inaccuracy of measuring the angular divergence of the injected electron beam, crucial to fast ignition, from the lateral extent of the ion emission. However, it is shown that on careful probing the sheath field can provide unique insight into details of the fast electron's distribution function. The relative merits of probing other physical quantities has been examined. The width of the background temperature spot overestimates the divergence by a factor of 2 unless electron recirculation is prevented.

  14. Direct observation of a pulse peak using a peak-removed Gaussian optical pulse in a superluminal medium.

    Science.gov (United States)

    Tomita, Makoto; Amano, Heisuke; Masegi, Seiji; Talukder, Aminul I

    2014-03-07

    A series of experiments is performed to examine the arrival of a pulse peak, using a Gaussian-shaped temporal wave packet as the input pulse and truncating it at various positions on or before the peak of the packet. When the truncating point is within the negative group delay limit of the fast light medium, a smooth Gaussian peak is observed at the exit port, despite the absence of an input pulse peak. The experimental results explicitly demonstrate that the superluminal propagation of a smooth Gaussian-shaped pulse peak is an analytic continuation over time of the earlier portion of the input pulse envelope. To investigate the physical meaning of the pulse peak further, we also examine the propagation of triangular-shaped pulses, for which the pulse peak can be recognized as a nonanalytical point.

  15. Low threshold optical bistability and superluminal light propagation using a dielectric slab via inter-dot tunneling

    Science.gov (United States)

    Taherzadeh, S.; Nasehi, R.; Mahmoudi, Mohammad

    2015-04-01

    The optical bistability (OB) behavior of a dielectric slab doped with quantum dot (QD) molecules is investigated in the presence of the inter-dot tunneling effect. It is shown that the threshold point of OB reduces by increasing inter-dot tunneling as well as by reducing the slab thickness. It is worth noting that the threshold of OB in a slab doped with QD molecules is smaller, by at least one order of magnitude, in respect to free QD molecules. We find that the inter-dot tunneling induces a negative group delay to the reflected pulse and it propagates in the superluminal region. Such simple control can be used in all optical switching.

  16. Giant Kerr nonlinearity and superluminal and subluminal polaritonic solitons in a Bose-Einstein condensate via superradiant scattering

    Science.gov (United States)

    Hang, Chao; Gabadadze, Gregory; Huang, Guoxiang

    2015-09-01

    We propose a setup to generate giant Kerr nonlinearity and polaritonic solitons via matter-wave superradiant scattering. The system we consider is a long cigar-shaped Bose-Einstein condensate (BEC), pumped by a red-detuned laser field with a space-dependent intensity distribution in transverse directions. The pump and the scattered fields propagate along the longitudinal direction. We show that by means of the atom-photon and atom-atom interactions in the system it is possible to produce a giant nonlinear optical effect. We further show that a backward scattering of the laser field from the BEC is favorable for the formation and stable propagation of polaritonic solitons, which are collective nonlinear excitations of the BEC coupled with the scattered laser field. In the case of backward Stokes (anti-Stokes) scattering the system may support robust bright (dark) polaritonic solitons propagating with superluminal (subluminal) velocity.

  17. Superluminous Transients at AGN Centers from Interaction between Black Hole Disk Winds and Broad-line Region Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Moriya, Takashi J.; Tanaka, Masaomi; Ohsuga, Ken [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Morokuma, Tomoki, E-mail: takashi.moriya@nao.ac.jp [Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

    2017-07-10

    We propose that superluminous transients that appear at central regions of active galactic nuclei (AGNs) such as CSS100217:102913+404220 (CSS100217) and PS16dtm, which reach near- or super-Eddington luminosities of the central black holes, are powered by the interaction between accretion-disk winds and clouds in broad-line regions (BLRs) surrounding them. If the disk luminosity temporarily increases by, e.g., limit–cycle oscillations, leading to a powerful radiatively driven wind, strong shock waves propagate in the BLR. Because the dense clouds in the AGN BLRs typically have similar densities to those found in SNe IIn, strong radiative shocks emerge and efficiently convert the ejecta kinetic energy to radiation. As a result, transients similar to SNe IIn can be observed at AGN central regions. Since a typical black hole disk-wind velocity is ≃0.1 c , where c is the speed of light, the ejecta kinetic energy is expected to be ≃10{sup 52} erg when ≃1 M {sub ⊙} is ejected. This kinetic energy is transformed to radiation energy in a timescale for the wind to sweep up a similar mass to itself in the BLR, which is a few hundred days. Therefore, both luminosities (∼10{sup 44} erg s{sup −1}) and timescales (∼100 days) of the superluminous transients from AGN central regions match those expected in our interaction model. If CSS100217 and PS16dtm are related to the AGN activities triggered by limit–cycle oscillations, they become bright again in coming years or decades.

  18. DES14X3taz: A TYPE I SUPERLUMINOUS SUPERNOVA SHOWING A LUMINOUS, RAPIDLY COOLING INITIAL PRE-PEAK BUMP

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.; Sullivan, M.; D’Andrea, C. B.; Castander, F. J.; Casas, R.; Prajs, S.; Papadopoulos, A.; Nichol, R. C.; Karpenka, N. V.; Bernard, S. R.; Brown, P.; Cartier, R.; Cooke, J.; Curtin, C.; Davis, T. M.; Finley, D. A.; Foley, R. J.; Gal-Yam, A.; Goldstein, D. A.; González-Gaitán, S.; Gupta, R. R.; Howell, D. A.; Inserra, C.; Kessler, R.; Lidman, C.; Marriner, J.; Nugent, P.; Pritchard, T. A.; Sako, M.; Smartt, S.; Smith, R. C.; Spinka, H.; Thomas, R. C.; Wolf, R. C.; Zenteno, A.; Abbott, T. M. C.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; Costa, L. N. da; Desai, S.; Diehl, H. T.; Doel, P.; Estrada, J.; Evrard, A. E.; Flaugher, B.; Fosalba, P.; Frieman, J.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Li, T. S.; Marshall, J. L.; Martini, P.; Miller, C. J.; Miquel, R.; Nord, B.; Ogando, R.; Plazas, A. A.; Reil, K.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Walker, A. R.; Wester, W.

    2016-02-03

    We present DES14X3taz, a new hydrogen-poor superluminous supernova (SLSN-I) discovered by the Dark Energy Survey (DES) supernova program, with additional photometric data provided by the Survey Using DECam for Superluminous Supernovae. Spectra obtained using Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy on the Gran Telescopio CANARIAS show DES14X3taz is an SLSN-I at z = 0.608. Multi-color photometry reveals a double-peaked light curve: a blue and relatively bright initial peak that fades rapidly prior to the slower rise of the main light curve. Our multi-color photometry allows us, for the first time, to show that the initial peak cools from 22,000 to 8000 K over 15 rest-frame days, and is faster and brighter than any published core-collapse supernova, reaching 30% of the bolometric luminosity of the main peak. No physical Ni-56-powered model can fit this initial peak. We show that a shock-cooling model followed by a magnetar driving the second phase of the light curve can adequately explain the entire light curve of DES14X3taz. Models involving the shock-cooling of extended circumstellar material at a distance of similar or equal to 400 R-circle dot are preferred over the cooling of shock-heated surface layers of a stellar envelope. We compare DES14X3taz to the few double-peaked SLSN-I events in the literature. Although the rise. times and characteristics of these initial peaks differ, there exists the tantalizing possibility that they can be explained by one physical interpretation

  19. Dynamics of Droplet Collision and Flamefront Motion

    National Research Council Canada - National Science Library

    Law, Chung K

    2005-01-01

    ... of air bubbles entrained upon coalescence of the colliding droplets. (3) The dynamics of droplet-film collision, especially on the influence of the film thickness in effecting droplet bouncing versus absorption. (4) The dynamics of flame motion when it is subjected to the combined hydrodynamic and body-force instabilities and freestream vortical motion.

  20. X-ray Dips Followed by Superluminal Ejections as Evidence for An Accretion Disc Feeding the Jet in A Radio Galaxy

    Science.gov (United States)

    Marscher, Alan P.; Jorstad, Svetlana G.; Gomez, Jose-Luis; Aller, Margo F.; Terasranta, Harri; Lister, Matthew L.; Stirling, Alastair, M.

    2002-01-01

    Accretion onto black holes is thought to power the relativistic jets and other high-energy phenomena in both active galactic nuclei (AGNs) and the "microquasar" binary systems located in our Galaxy. However, until now there has been insufficient multifrequency monitoring to establish a direct observational link between the black hole and the jet in an AGE. This contrasts with the case of microquasars, in which superluminal features appear and propagate down the radio jet shortly after sudden decreases in the X-ray flux. Such an X-ray dip is most likely caused by the disappearance of a section of the inner accretion disc, part of which falls past the event horizon and the remainder of which is injected into the jet. This infusion of energy generates a disturbance that propagates down the jet, creating the appearance of a superluminal bright spot. Here we report the results of three years of intensive monitoring of the X-ray and radio emission of the Seyfert-like radio galaxy 3C 120. As in the case of microquasars, dips in the X-ray emission are followed by ejections of bright superluminal knots in the radio jet. Comparison of the characteristic length and time scales allows us to infer that the rotational states of the black holes in these two objects are different.

  1. Wave motion in elastic solids

    CERN Document Server

    Graff, Karl F

    1991-01-01

    This highly useful textbook presents comprehensive intermediate-level coverage of nearly all major topics of elastic wave propagation in solids. The subjects range from the elementary theory of waves and vibrations in strings to the three-dimensional theory of waves in thick plates. The book is designed not only for a wide audience of engineering students, but also as a general reference for workers in vibrations and acoustics. Chapters 1-4 cover wave motion in the simple structural shapes, namely strings, longitudinal rod motion, beams and membranes, plates and (cylindrical) shells. Chapter

  2. Motion in radiotherapy

    DEFF Research Database (Denmark)

    Korreman, Stine Sofia

    2012-01-01

    This review considers the management of motion in photon radiation therapy. An overview is given of magnitudes and variability of motion of various structures and organs, and how the motion affects images by producing artifacts and blurring. Imaging of motion is described, including 4DCT and 4DPE...

  3. 2 NEW CANDIDATE SUPERLUMINAL QUASARS - 4C 28.45 AND 4C 21.35

    NARCIS (Netherlands)

    HOOIMEYER, JRA; SCHILIZZI, RT; MILEY, GK; BARTHEL, PD

    Multi-epoch VLBI observations are presented of two large double-lobed quasars, 4C 28.45 (1830 + 285) and 4C 21.35 (1222 + 216). On mas-scales, both quasars contain a multi-component asymmetric radio structure. In 4C 28.45 the nuclear emission was seen to expand, the observed proper motions

  4. The "motion silencing" illusion results from global motion and crowding.

    Science.gov (United States)

    Turi, Marco; Burr, David

    2013-04-18

    Suchow and Alvarez (2011) recently devised a striking illusion, where objects changing in color, luminance, size, or shape appear to stop changing when they move. They refer to the illusion as "motion silencing of awareness to visual change." Here we present evidence that the illusion results from two perceptual processes: global motion and crowding. We adapted Suchow and Alvarez's stimulus to three concentric rings of dots, a central ring of "target dots" flanked on either side by similarly moving flanker dots. Subjects had to identify in which of two presentations the target dots were continuously changing (sinusoidally) in size, as distinct from the other interval in which size was constant. The results show: (a) Motion silencing depends on target speed, with a threshold around 0.2 rotations per second (corresponding to about 10°/s linear motion). (b) Silencing depends on both target-flanker spacing and eccentricity, with critical spacing about half eccentricity, consistent with Bouma's law. (c) The critical spacing was independent of stimulus size, again consistent with Bouma's law. (d) Critical spacing depended strongly on contrast polarity. All results imply that the "motion silencing" illusion may result from crowding.

  5. Motion Transplantation Techniques: A Survey

    NARCIS (Netherlands)

    van Basten, Ben|info:eu-repo/dai/nl/30484800X; Egges, Arjan|info:eu-repo/dai/nl/304822779

    2012-01-01

    During the past decade, researchers have developed several techniques for transplanting motions. These techniques transplant a partial auxiliary motion, possibly defined for a small set of degrees of freedom, on a base motion. Motion transplantation improves motion databases' expressiveness and

  6. Modeling Human Control of Self-Motion Direction With Optic Flow and Vestibular Motion.

    Science.gov (United States)

    Zaal, Peter M T; Nieuwenhuizen, Frank M; van Paassen, Marinus M; Mulder, Max

    2013-04-01

    In this paper, we investigate the effects of visual and motion stimuli on the manual control of one's direction of self-motion. In a flight simulator, subjects conducted an active target-following disturbance-rejection task, using a compensatory display. Simulating a vehicular control task, the direction of vehicular motion was shown on the outside visual display in two ways: an explicit presentation using a symbol and an implicit presentation, namely, through the focus of radial outflow that emerges from optic flow. In addition, the effects of the relative strength of congruent vestibular motion cues were investigated. The dynamic properties of human visual and vestibular motion perception paths were modeled using a control-theoretical approach. As expected, improved tracking performance was found for the configurations that explicitly showed the direction of self-motion. The human visual time delay increased with approximately 150 ms for the optic flow conditions, relative to explicit presentations. Vestibular motion, providing higher order information on the direction of self-motion, allowed subjects to partially compensate for this visual perception delay, improving performance. Parameter estimates of the operator control model show that, with vestibular motion, the visual feedback becomes stronger, indicating that operators are more confident to act on optic flow information when congruent vestibular motion cues are present.

  7. Light physical activity determined by a motion sensor decreases insulin resistance, improves lipid homeostasis and reduces visceral fat in high-risk subjects: PreDiabEx study RCT.

    Science.gov (United States)

    Herzig, K-H; Ahola, R; Leppäluoto, J; Jokelainen, J; Jämsä, T; Keinänen-Kiukaanniemi, S

    2014-08-01

    To examine physical activity (PA) thresholds affecting glucose, insulin and lipid concentrations and body fat composition in high-risk patients for type 2 diabetes (T2D). A total of 113 subjects of both genders having abnormal glucose levels in the oral glucose tolerance test were contacted. A total of 78 subjects with age 58.8±10.4 years and body mass index 31.7±5.3 kg m(-2) were randomly assigned to intervention and control groups. INTERVENTION consisted of a supervised walking (60 min three times weekly) for 3 months. All the subjects received standard care for PA and weight reduction and wore an accelerometer during the whole wakeful time. Over 80% of the daily steps clustered at an acceleration level of 0.3-0.7 g (2-3 km h(-1) of walking) and were 5870 in the intervention and 4434 in the control group (P<0.029). Between 0 and 3 months no significant changes were observed in fasting and 2-h glucose, body weight or maximal oxygen uptake. In contrast, changes in fasting and 2-h insulin (-3.4 mU l(-1), P=0.035 and -26.6, P=0.003, respectively), homeostasis model assessment-estimated insulin resistance (-1.0, P=0.036), total cholesterol (-0.55 mmol l(-1), P=0.041), low-density lipoprotein (LDL) cholesterol (-0.36 mmol l(-1), P=0.008) and visceral fat area (-5.5 cm(2), P=0.030) were significantly greater in the intervention than in control subjects. The overall effects of PA were analyzed by quartiles of daily steps of all subjects. There were significant reductions in total and LDL cholesterol and visceral fat area between the highest (daily steps over 6520) and the lowest quartile (1780-2810 daily steps). The changes associated with PA remained significant after adjustments of baseline, sex, age and body weight change. Habitual and structured PAs with the acceleration levels of 0.3-0.7 g and daily steps over 6520, equivalent to walking at 2-3 km h(-1) for 90 min daily, standing for the relative PA intensity of 30-35% of the

  8. Macro motion vector quantization

    Science.gov (United States)

    Lee, Yoon Y.; Woods, John W.

    1995-04-01

    A new algorithm is developed for reducing the bit rate required for motion vectors. This algorithm is a generalization of block matching motion estimation in which the search region is represented as a codebook of motion vectors. The new algorithm, called macro motion vector quantization (MMVQ), generalized our earlier MVQ by coding a group of motion vectors. The codebook is a set of macro motion vectors which represent the block locations of the small neighboring blocks in the previous frame. We develop an interative design algorithm for the codebook. Our experiments show that the variances of displaced frame differences (DFDs) are reduced significantly compared to block matching algorithm (BMA) with the macroblock size.

  9. Expanding subjectivities

    DEFF Research Database (Denmark)

    Lundgaard Andersen, Linda; Soldz, Stephen

    2012-01-01

    A major theme in recent psychoanalytic thinking concerns the use of therapist subjectivity, especially “countertransference,” in understanding patients. This thinking converges with and expands developments in qualitative research regarding the use of researcher subjectivity as a tool to understa...

  10. Proper Motions of Jets on the Kiloparsec Scale: New Results with HST

    Directory of Open Access Journals (Sweden)

    Eileen T. Meyer

    2017-01-01

    Full Text Available The Hubble Space Telescope recently celebrated 25 years of operation. Some of the first images of extragalactic optical jets were taken by HST in the mid-1990s; with time baselines on the order of 20 years and state-of-the-art astrometry techniques, we are now able to reach accuracies in proper-motion measurements on the order of a tenth of a milliarcsecond per year. We present the results of a recent HST program to measure the kiloparsec-scale proper motions of eleven nearby optical jets with Hubble, the first sample of its kind. When paired with VLBI proper-motion measurements on the parsec scale, we are now able to map the full velocity profile of these jets from near the black hole to the final deceleration as they extend out into and beyond the host galaxy. We see convincing evidence that weak-flavor jets (i.e., FR Is have a slowly increasing jet speed up to 100 pc from the core, where superluminal components are first seen.

  11. [THE EFFECT OF THE APPLICATION OF THE KINESIOLOGY TAPING TECHNIQUE FOR MUSCLE RANGE OF MOTION OF THE LUMBAR SPINE, AND THE SUBJECTIVE PERCEPTION OF PAIN INTENSITY IN PATIENTS WITH BACK PAIN].

    Science.gov (United States)

    Garczyński, Wojciech; Lubkowska, Anna; Dobek, Aleksandra; Andryszczyk, Marek

    2014-01-01

    In an era of ubiquitous computing, a considerable part of the population, regardless of age group, spend more time in a sitting position. Long-term, static loading of the spine increases muscle tension, leading to the occurrence of pain. Physiotherapy is recommended as primary and secondary prevention of spinal pain symptoms. The Kinesiology Taping Method is one of the many special methods of physiotherapy which is used during the episodes of back pain in the lumbosacral region. This method consists in sticking on a special tape, which is made of stretch cotton similar to human skin, using a variety of techniques for patch application. The present study evaluated the effect of the application of the Kinesiology Taping technique for muscle mobility in the lumbar spine and the subjective perception of pain intensity. The study group consisted of 100 patients (89 women and 11 men) who experienced pain in the lumbar spine. To assess the mobility of the lumbar spine the Schober test was used. The subjective sensation of pain was assessed using the VAS (visual analogue scale). Measurements were taken four times: before gluing applications, immediately after taping, 7 days after application of the patch, and immediately after its removal. In response to the use of therapy, an increase of mobility of the lumbar spine in flexion front and back, and reduced pain was shown. Application of the muscle kinesiology taping technique is an effective method in reducing pain and increasing mobility of the lumbar spine.

  12. Haptically Induced Illusory Self-motion and the Influence of Context of Motion

    DEFF Research Database (Denmark)

    Nilsson, Niels Christian; Nordahl, Rolf; Sikström, Erik

    2012-01-01

    with the intention of investigating how different virtual environments – contexts of motion – influences self-motion illusions induced through haptic stimulation of the feet. A concurrent goal was to determine whether horizontal self-motion illusions can be induced through stimulation of the supporting areas...... of the feet. The experiment was based on the a within-subjects design and included four conditions, each representing one context of motion: an elevator, a train compartment, a bathroom, and a completely dark environment. The audiohaptic stimuli was identical across all conditions. The participants’ sensation...

  13. Subluminal to superluminal propagation of an optical pulse in an f-deformed Bose-Einstein condensate

    Energy Technology Data Exchange (ETDEWEB)

    Haghshenasfard, Z; Naderi, M H; Soltanolkotabi, M [Quantum Optics Group, Department of Physics, University of Isfahan, Hezar Jerib, 81746-73441 Isfahan (Iran, Islamic Republic of)], E-mail: zhaghshenas@hotmail.com, E-mail: mhnaderi2001@yahoo.com, E-mail: soltan@sci.ui.ac.ir

    2008-08-28

    In this paper, we investigate the propagation of a weak optical probe pulse in an f-deformed Bose-Einstein condensate of a gas with the {lambda}-type three-level atoms in the electromagnetically induced transparency regime. We use an f-deformed generalization of an effective two-level quantum model of the three-level {lambda} configuration in which Gardiner's phonon operators for Bose-Einstein condensates are deformed by an operator-valued function, f(n-circumflex), of the particle-number operator n-circumflex. By making use of the quantum approach of the angular momentum theory, we obtain the eigenvalues and eigenfunctions of the system up to a first-order approximation. We consider the collisions between the atoms as a special kind of f-deformation. The collision rate {kappa} is regarded as the deformation parameter and light propagation in the deformed Bose-Einstein condensate is analysed. In particular, we show that the absorptive and dispersive properties of the deformed condensate can be controlled effectively by changing the deformation parameter {kappa} and the total number of atoms. We find that by increasing the value of {kappa} the group velocity of the probe pulse changes, through deformed condensate, from subluminal to superluminal.

  14. Antireflection coating of barriers to enhance electron tunnelling: exploring the matter wave analogy of superluminal optical phase velocity.

    Science.gov (United States)

    Zhao, Zijun C; McKenzie, David R

    2017-10-06

    The tunnelling of electrons through barriers is important in field emission sources and in interconnects within electronic devices. Here we use the analogy between the electromagnetic wave equation and the Schrodinger equation to find potential barriers that, when added before an existing barrier, increase the transmission probability. A single pre-barrier of negative potential behaves as a dielectric "antireflection coating", as previously reported. However, we obtain an unexpected and much greater enhancement of transmission when the pre-barrier has a positive potential of height smaller than the energy of the incident electron, an unfamiliar optical case, corresponding to media with superluminal phase velocities as in dilute free electron media and anomalous dispersion at X-ray frequencies. We use a finite difference time domain algorithm to evaluate the transmission through a triangular field emission barrier with a pre-barrier that meets the new condition. We show that the transmission is enhanced for an incident wavepacket, producing a larger field emission current than for an uncoated barrier. Examples are given of available materials to enhance transmission in practical applications. The results are significant for showing how to increase electron transmission in field emission and at interconnects between dissimilar materials in all types of electronic devices.

  15. Quark-novae Occurring in Massive Binaries : A Universal Energy Source in Superluminous Supernovae with Double-peaked Light Curves

    Science.gov (United States)

    Ouyed, Rachid; Leahy, Denis; Koning, Nico

    2016-02-01

    A quark-nova (QN; the sudden transition from a neutron star into a quark star), which occurs in the second common envelope (CE) phase of a massive binary, gives excellent fits to superluminous, hydrogen-poor, supernovae (SLSNe) with double-peaked light curves, including DES13S2cmm, SN 2006oz, and LSQ14bdq (http://www.quarknova.ca/LCGallery.html). In our model, the H envelope of the less massive companion is ejected during the first CE phase, while the QN occurs deep inside the second, He-rich, CE phase after the CE has expanded in size to a radius of a few tens to a few thousands of solar radii; this yields the first peak in our model. The ensuing merging of the quark star with the CO core leads to black hole formation and accretion, explaining the second long-lasting peak. We study a sample of eight SLSNe Ic with double-humped light curves. Our model provides good fits to all of these, with a universal explosive energy of 2 × 1052 erg (which is the kinetic energy of the QN ejecta) for the first hump. The late-time emissions seen in iPTF13ehe and LSQ14bdq are fit with a shock interaction between the outgoing He-rich (I.e., second) CE and the previously ejected H-rich (I.e., first) CE.

  16. QUARK-NOVAE OCCURRING IN MASSIVE BINARIES: A UNIVERSAL ENERGY SOURCE IN SUPERLUMINOUS SUPERNOVAE WITH DOUBLE-PEAKED LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Ouyed, Rachid; Leahy, Denis; Koning, Nico, E-mail: rouyed@ucalgary.ca [Department of Physics and Astronomy, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4 (Canada)

    2016-02-10

    A quark-nova (QN; the sudden transition from a neutron star into a quark star), which occurs in the second common envelope (CE) phase of a massive binary, gives excellent fits to superluminous, hydrogen-poor, supernovae (SLSNe) with double-peaked light curves, including DES13S2cmm, SN 2006oz, and LSQ14bdq (http://www.quarknova.ca/LCGallery.html). In our model, the H envelope of the less massive companion is ejected during the first CE phase, while the QN occurs deep inside the second, He-rich, CE phase after the CE has expanded in size to a radius of a few tens to a few thousands of solar radii; this yields the first peak in our model. The ensuing merging of the quark star with the CO core leads to black hole formation and accretion, explaining the second long-lasting peak. We study a sample of eight SLSNe Ic with double-humped light curves. Our model provides good fits to all of these, with a universal explosive energy of 2 × 10{sup 52} erg (which is the kinetic energy of the QN ejecta) for the first hump. The late-time emissions seen in iPTF13ehe and LSQ14bdq are fit with a shock interaction between the outgoing He-rich (i.e., second) CE and the previously ejected H-rich (i.e., first) CE.

  17. The effects of the Mulligan Sustained Natural Apophyseal Glide (SNAG mobilisation in the lumbar flexion range of asymptomatic subjects as measured by the Zebris CMS20 3-D motion analysis system

    Directory of Open Access Journals (Sweden)

    Strimpakos Nikolaos

    2008-10-01

    Full Text Available Abstract Background Mulligan's mobilisation techniques are thought to increase the range of movement (ROM in patients with low back pain. The primary aim of this study was to investigate the application of the Mulligan's Sustained Natural Apophyseal Glide (SNAG technique on lumbar flexion ROM. The secondary aim was to measure the intra- and inter-day reliability of lumbar ROM employing the same procedure. Methods 49 asymptomatic volunteers participated in this double-blinded study. Subjects were randomly assigned to receive either SNAG mobilisation (n = 25, or a sham mobilisation (n = 24. The SNAG technique was applied at the L3and L4 spinal levels with active flexion in sitting by an experienced manual therapist. Three sets of 10 repetitions at each of the two spinal levels were performed. The sham mobilisation was similar to the SNAG but did not apply the appropriate direction or force. Lumbar ROM was measured by a three dimensional electronic goniometer (Zebris CMS20, before and after each technique. For the reliability, five measurements in two different days (one week apart were performed in 20 healthy subjects. Results When both interventions were compared, independent t tests yielded no statistically significant results in ROM between groups (p = 0.673. Furthermore no significant within group differences were observed: SNAG (p = 0.842, sham (p = 0.169. Intra- and inter-day reliability of flexion measurements was high (ICC1,1 > 0.82, SEM Conclusion While the Zebris proved to be a reliable device for measuring lumbar flexion ROM, SNAG mobilisation did not demonstrate significant differences in flexion ROM when compared to sham mobilisation. Trial registration Current Controlled Trials NCT00678093.

  18. Objects in Motion

    Science.gov (United States)

    Damonte, Kathleen

    2004-01-01

    One thing scientists study is how objects move. A famous scientist named Sir Isaac Newton (1642-1727) spent a lot of time observing objects in motion and came up with three laws that describe how things move. This explanation only deals with the first of his three laws of motion. Newton's First Law of Motion says that moving objects will continue…

  19. Human joint motion estimation for electromyography (EMG)-based dynamic motion control.

    Science.gov (United States)

    Zhang, Qin; Hosoda, Ryo; Venture, Gentiane

    2013-01-01

    This study aims to investigate a joint motion estimation method from Electromyography (EMG) signals during dynamic movement. In most EMG-based humanoid or prosthetics control systems, EMG features were directly or indirectly used to trigger intended motions. However, both physiological and nonphysiological factors can influence EMG characteristics during dynamic movements, resulting in subject-specific, non-stationary and crosstalk problems. Particularly, when motion velocity and/or joint torque are not constrained, joint motion estimation from EMG signals are more challenging. In this paper, we propose a joint motion estimation method based on muscle activation recorded from a pair of agonist and antagonist muscles of the joint. A linear state-space model with multi input single output is proposed to map the muscle activity to joint motion. An adaptive estimation method is proposed to train the model. The estimation performance is evaluated in performing a single elbow flexion-extension movement in two subjects. All the results in two subjects at two load levels indicate the feasibility and suitability of the proposed method in joint motion estimation. The estimation root-mean-square error is within 8.3% ∼ 10.6%, which is lower than that being reported in several previous studies. Moreover, this method is able to overcome subject-specific problem and compensate non-stationary EMG properties.

  20. ASCA Observation of the Superluminal Jet Source GRO J1655-40 in the 1997 Outburst

    Science.gov (United States)

    Yamaoka, Kazutaka; Ueda, Yoshihiro; Hajime, Inoue; Nagase, Fumiski; Ebisawa, Ken; Kotani, Taro; Tanaka, Yasuo; Zhang, Shang Nan

    2001-01-01

    We report on the results of an ASCA observation of the Galactic jet source GRO 51655-40 performed from 1997 February 25 to February 28 covering a full orbital period (2.62 d). The averaged 2-10 keV flux was about 1.1 Crab. An absorption line feature centered at 6.8 keV was detected both in the GIS and SIS spectra. We interpret this as a blend of two resonance-absorption K alpha lines from H-like and He-like iron ions. We can consistently explain both the ASCA spectra and the simultaneous RXTE/PCA spectrum by a combination of K-absorption lines and K-absorption edges of iron ions. The fact that the absorption line is stably present over the whole orbital phase implies that the distribution of the highly ionized plasma is not affected by the companion star, which is consistent with its presence around the black hole. A curve of growth analysis shows that the plasma contains velocity dispersion along the line-of-sight larger than 300 km/s attributed to bulk motions. It is probably a part of a geometrically thick accretion flow in turbulent motions with velocities of 500-1600 km/s at an estimated radius of sim 10(exp 10)/cm.

  1. Robot Motion Planning Among Moving Obstacles

    Science.gov (United States)

    Fiorini, P.; Shiller, Z.

    1995-01-01

    An on-line method is presented for computing the motion of a robot in a dynamic environment subject to the robot dynamics and its actuator constraints. This method is based on the concept of Velocity Obstacle that defines the set of robot velocities that would result in a collision between the robot and a moving obstacle. The problem of motion planning in dynamic environments is addressed.

  2. Analysis of motion in speed skating

    Science.gov (United States)

    Koga, Yuzo; Nishimura, Tetsu; Watanabe, Naoki; Okamoto, Kousuke; Wada, Yuhei

    1997-03-01

    A motion on sports has been studied by many researchers from the view of the medical, psychological and mechanical fields. Here, we try to analyze a speed skating motion dynamically for an aim of performing the best record. As an official competition of speed skating is performed on the round rink, the skating motion must be studied on the three phases, that is, starting phase, straight and curved course skating phase. It is indispensable to have a visual data of a skating motion in order to analyze kinematically. So we took a several subject's skating motion by 8 mm video cameras in order to obtain three dimensional data. As the first step, the movement of the center of gravity of skater (abbreviate to C. G.) is discussed in this paper, because a skating motion is very complicated. The movement of C. G. will give an information of the reaction force to a skate blade from the surface of ice. We discuss the discrepancy of several skating motion by studied subjects. Our final goal is to suggest the best skating form for getting the finest record.

  3. Rolling Shutter Motion Deblurring

    KAUST Repository

    Su, Shuochen

    2015-06-07

    Although motion blur and rolling shutter deformations are closely coupled artifacts in images taken with CMOS image sensors, the two phenomena have so far mostly been treated separately, with deblurring algorithms being unable to handle rolling shutter wobble, and rolling shutter algorithms being incapable of dealing with motion blur. We propose an approach that delivers sharp and undis torted output given a single rolling shutter motion blurred image. The key to achieving this is a global modeling of the camera motion trajectory, which enables each scanline of the image to be deblurred with the corresponding motion segment. We show the results of the proposed framework through experiments on synthetic and real data.

  4. Modeling depth from motion parallax with the motion/pursuit ratio

    Directory of Open Access Journals (Sweden)

    Mark eNawrot

    2014-10-01

    Full Text Available The perception of unambiguous scaled depth from motion parallax relies on both retinal image motion and an extra-retinal pursuit eye movement signal. The motion/pursuit ratio represents a dynamic geometric model linking these two proximal cues to the ratio of depth to viewing distance. An important step in understanding the visual mechanisms serving the perception of depth from motion parallax is to determine the relationship between these stimulus parameters and empirically determined perceived depth magnitude. Observers compared perceived depth magnitude of dynamic motion parallax stimuli to static binocular disparity comparison stimuli at three different viewing distances, in both head-moving and head-stationary conditions. A stereo-viewing system provided ocular separation for stereo stimuli and monocular viewing of parallax stimuli. For each motion parallax stimulus, a point of subjective equality was estimated for the amount of binocular disparity that generates the equivalent magnitude of perceived depth from motion parallax. Similar to previous results, perceived depth from motion parallax had significant foreshortening. Head-moving conditions produced even greater foreshortening due to the differences in the compensatory eye movement signal. An empirical version of motion/pursuit law, termed the empirical motion/pursuit ratio, which models perceived depth magnitude from these stimulus parameters, is proposed.

  5. Smoothing Motion Estimates for Radar Motion Compensation.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-07-01

    Simple motion models for complex motion environments are often not adequate for keeping radar data coherent. Eve n perfect motion samples appli ed to imperfect models may lead to interim calculations e xhibiting errors that lead to degraded processing results. Herein we discuss a specific i ssue involving calculating motion for groups of pulses, with measurements only available at pulse-group boundaries. - 4 - Acknowledgements This report was funded by General A tomics Aeronautical Systems, Inc. (GA-ASI) Mission Systems under Cooperative Re search and Development Agre ement (CRADA) SC08/01749 between Sandia National Laboratories and GA-ASI. General Atomics Aeronautical Systems, Inc. (GA-ASI), an affilia te of privately-held General Atomics, is a leading manufacturer of Remotely Piloted Aircraft (RPA) systems, radars, and electro-optic and rel ated mission systems, includin g the Predator(r)/Gray Eagle(r)-series and Lynx(r) Multi-mode Radar.

  6. Relativistic jet with shock waves like model of superluminal radio source. Jet relativista con ondas de choque como modelo de radio fuentes superluminales

    Energy Technology Data Exchange (ETDEWEB)

    Alberdi, A.; Gomez, J.L.; Marcaide, J.M.

    1993-01-01

    The structure of the compact radio sources at milliarcsecond angular resolution can be explained in terms of shock waves propagating along bent jets. These jets consist of narrow-angle cones of plasma flowing at bulk relativistic velocities, within tangled magnetic fields, emitting synchrotron radiation. We have developed a numerical code which solves the synchrotron radiation transfer equations to compute the total and polarized emission of bent shocked relativistic jets, and we have applied it to reproduce the compact structure, kenimatic evolution and time flux density evolution of the superluminal radio source 4C 39.25 and to obtain its jet physical parameters. (Author) 23 ref.

  7. Structural motion engineering

    CERN Document Server

    Connor, Jerome

    2014-01-01

    This innovative volume provides a systematic treatment of the basic concepts and computational procedures for structural motion design and engineering for civil installations. The authors illustrate the application of motion control to a wide spectrum of buildings through many examples. Topics covered include optimal stiffness distributions for building-type structures, the role of damping in controlling motion, tuned mass dampers, base isolation systems, linear control, and nonlinear control. The book's primary objective is the satisfaction of motion-related design requirements, such as restrictions on displacement and acceleration. The book is ideal for practicing engineers and graduate students. This book also: ·         Broadens practitioners' understanding of structural motion control, the enabling technology for motion-based design ·         Provides readers the tools to satisfy requirements of modern, ultra-high strength materials that lack corresponding stiffness, where the motion re...

  8. Human Perception of Ambiguous Inertial Motion Cues

    Science.gov (United States)

    Zhang, Guan-Lu

    2010-01-01

    Human daily activities on Earth involve motions that elicit both tilt and translation components of the head (i.e. gazing and locomotion). With otolith cues alone, tilt and translation can be ambiguous since both motions can potentially displace the otolithic membrane by the same magnitude and direction. Transitions between gravity environments (i.e. Earth, microgravity and lunar) have demonstrated to alter the functions of the vestibular system and exacerbate the ambiguity between tilt and translational motion cues. Symptoms of motion sickness and spatial disorientation can impair human performances during critical mission phases. Specifically, Space Shuttle landing records show that particular cases of tilt-translation illusions have impaired the performance of seasoned commanders. This sensorimotor condition is one of many operational risks that may have dire implications on future human space exploration missions. The neural strategy with which the human central nervous system distinguishes ambiguous inertial motion cues remains the subject of intense research. A prevailing theory in the neuroscience field proposes that the human brain is able to formulate a neural internal model of ambiguous motion cues such that tilt and translation components can be perceptually decomposed in order to elicit the appropriate bodily response. The present work uses this theory, known as the GIF resolution hypothesis, as the framework for experimental hypothesis. Specifically, two novel motion paradigms are employed to validate the neural capacity of ambiguous inertial motion decomposition in ground-based human subjects. The experimental setup involves the Tilt-Translation Sled at Neuroscience Laboratory of NASA JSC. This two degree-of-freedom motion system is able to tilt subjects in the pitch plane and translate the subject along the fore-aft axis. Perception data will be gathered through subject verbal reports. Preliminary analysis of perceptual data does not indicate that

  9. Identification of the Subject-Specific Parameters of a Hill-type Muscle-tendon Model for Simulations of Human Motion (Identificatie van subject-specifieke parameters van een Hill-type spier-pees model voor de simulatie van menselijke beweging)

    OpenAIRE

    Van Campen, Anke

    2014-01-01

    This thesis contributes to subject-specific modeling in biomechanical an alysis by (i) designing an experimental setup to obtain a more accurate subject-specific angle-moment relationship of the knee joint (chapters 4 and 5), (ii) developing an algorithm for the estimation of the muscle-t endon parameters of the actuators of the knee joint in a simulation envi ronment and comparing its performance to the performance of the algorith m of Garner and Pandy (2003), and (iii) validating the outcom...

  10. SUBJECT INDEX

    Indian Academy of Sciences (India)

    Subject Index. Variation of surface electric field during geomagnetic disturbed period at Maitri, Antarctica. 1721. Geomorphology. A simple depression-filling method for raster and irregular elevation datasets. 1653. Decision Support System integrated with Geographic. Information System to target restoration actions in water-.

  11. System and method for generating motion corrected tomographic images

    Science.gov (United States)

    Gleason, Shaun S [Knoxville, TN; Goddard, Jr., James S.

    2012-05-01

    A method and related system for generating motion corrected tomographic images includes the steps of illuminating a region of interest (ROI) to be imaged being part of an unrestrained live subject and having at least three spaced apart optical markers thereon. Simultaneous images are acquired from a first and a second camera of the markers from different angles. Motion data comprising 3D position and orientation of the markers relative to an initial reference position is then calculated. Motion corrected tomographic data obtained from the ROI using the motion data is then obtained, where motion corrected tomographic images obtained therefrom.

  12. Quark-Novae in massive binaries: a model for double-humped, hydrogen-poor, superluminous Supernovae

    Science.gov (United States)

    Ouyed, Rachid; Leahy, Denis; Koning, Nico

    2015-12-01

    LSQ14bdq and SN 2006oz are superluminous, hydrogen-poor, SNe with double-humped light curves. We show that a Quark-Nova (QN; explosive transition of the Neutron Star - NS - to a quark star -QS) occurring in a massive binary, experiencing two Common Envelope (CE) phases, can quantitatively explain the light curves of LSQ14bdq and SN 2006oz. The more massive component (A) explodes first as a normal SN, yielding a NS which ejects the hydrogen envelope of the companion when the system enters its first CE phase. During the second CE phase, the NS spirals into and inflates the second He-rich CE. In the process it gains mass and triggers a QN, outside of the CO core, leaving behind a QS. The first hump in our model is the QN shock re-energizing the expanded He-rich CE. The QN occurs when the He-rich envelope is near maximum size (˜1000 R⊙) and imparts enough energy to unbind and eject the envelope. Subsequent merging of the QS with the CO core of component B, driven by gravitational radiation, turns the QS to a black hole. The ensuing black hole accretion provides sufficient power for the second brighter and long lasting hump. Our model suggests a possible connection between SLSNe-I and type Ic-BL SNe which occur when the QN is triggered inside the CO core. We estimate the rate of QNe in massive binaries during the second CE phase to be ˜5 × 10-5 of that of core-collapse SNe.

  13. Millisecond Magnetar Birth Connects FRB 121102 to Superluminous Supernovae and Long-duration Gamma-Ray Bursts

    Energy Technology Data Exchange (ETDEWEB)

    Metzger, Brian D.; Margalit, Ben [Columbia Astrophysics Laboratory, New York, NY 10027 (United States); Berger, Edo [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2017-05-20

    Subarcsecond localization of the repeating fast radio burst FRB 121102 revealed its coincidence with a dwarf host galaxy and a steady (“quiescent”) nonthermal radio source. We show that the properties of the host galaxy are consistent with those of long-duration gamma-ray bursts (LGRB) and hydrogen-poor superluminous supernovae (SLSNe-I). Both LGRBs and SLSNe-I were previously hypothesized to be powered by the electromagnetic spin-down of newly formed, strongly magnetized neutron stars with millisecond birth rotation periods (“millisecond magnetars”). This motivates considering a scenario whereby the repeated bursts from FRB 121102 originate from a young magnetar remnant embedded within a young hydrogen-poor supernova (SN) remnant. Requirements on the gigahertz free–free optical depth through the expanding SN ejecta (accounting for photoionization by the rotationally powered magnetar nebula), energetic constraints on the bursts, and constraints on the size of the quiescent source all point to an age of less than a few decades. The quiescent radio source can be attributed to synchrotron emission from the shock interaction between the fast outer layer of the supernova ejecta with the surrounding wind of the progenitor star, or the radio source can from deeper within the magnetar wind nebula as outlined in Metzger et al. Alternatively, the radio emission could be an orphan afterglow from an initially off-axis LGRB jet, though this might require the source to be too young. The young age of the source can be tested by searching for a time derivative of the dispersion measure and the predicted fading of the quiescent radio source. We propose future tests of the SLSNe-I/LGRB/FRB connection, such as searches for FRBs from nearby SLSNe-I/LGRBs on timescales of decades after their explosions.

  14. Hydrogen-poor Superluminous Supernovae with Late-time Hα Emission: Three Events From the Intermediate Palomar Transient Factory

    Science.gov (United States)

    Yan, Lin; Lunnan, R.; Perley, D. A.; Gal-Yam, A.; Yaron, O.; Roy, R.; Quimby, R.; Sollerman, J.; Fremling, C.; Leloudas, G.; Cenko, S. B.; Vreeswijk, P.; Graham, M. L.; Howell, D. A.; De Cia, A.; Ofek, E. O.; Nugent, P.; Kulkarni, S. R.; Hosseinzadeh, G.; Masci, F.; McCully, C.; Rebbapragada, U. D.; Woźniak, P.

    2017-10-01

    We present observations of two new hydrogen-poor superluminous supernovae (SLSN-I), iPTF15esb and iPTF16bad, showing late-time Hα emission with line luminosities of (1{--}3)× {10}41 erg s‑1 and velocity widths of (4000–6000) km s‑1. Including the previously published iPTF13ehe, this makes up a total of three such events to date. iPTF13ehe is one of the most luminous and the slowest evolving SLSNe-I, whereas the other two are less luminous and fast decliners. We interpret this as a result of the ejecta running into a neutral H-shell located at a radius of ∼1016 cm. This implies that violent mass loss must have occurred several decades before the supernova explosion. Such a short time interval suggests that eruptive mass loss could be common shortly before core collapse, and more importantly helium is unlikely to be completely stripped off the progenitor and could be present in the ejecta. It is a mystery why helium features are not detected, even though nonthermal energy sources, capable of ionizing He, may exist as suggested by the O ii absorption series in the early-time spectra. Our late-time spectra (+240 days) appear to have intrinsically lower [O i] 6300 Å luminosities than that of SN2015bn and SN2007bi, which is possibly an indication of less oxygen (light curve (LC) with three peaks separated from one another by ∼22 days. The LC undulation is stronger in bluer bands. One possible explanation is ejecta-circumstellar medium interaction.

  15. Lung respiration motion modeling: a sparse motion field presentation method using biplane x-ray images

    Science.gov (United States)

    Chen, Dong; Xie, Hongzhi; Zhang, Shuyang; Gu, Lixu

    2017-10-01

    Respiration-introduced tumor location uncertainty is a challenge in the precise lung biopsy for lung lesions. Current statistical modeling approaches hardly capture the complex local respiratory motion information. In this study, we formulate a statistical respiratory motion model using biplane x-ray images to improve the accuracy of motion field estimation by efficiently preserving local motion details for specific patients. Given CT data sets of 18 healthy subjects at end-expiratory and end-inspiratory breathing phases, the respiratory motion field is constructed based on deformation vector fields which are extracted from these CT data sets, and a lung contour motion repository respiratory is generated dependent on displacements of boundary control points. By varying the sparse weight coefficients of the statistical sparse motion field presentation (SMFP) method, the newly-input motion field is approximately presented by a sparse linear combination of a subset of the motion repository. The SMFP method is employed twice in the coefficient optimization process. Finally, these non-zero coefficients are fine-tuned to maximize the similarity between the projection image of reconstructed volumetric images and the current x-ray image. We performed the proposed method for estimating respiratory motion field on ten subject datasets and compared the result with the PCA method. The maximum average target registration error of the PCA-based and the SMFP-based respiratory motion field estimation are 3.1(2.0) and 2.9(1.6) mm, respectively. The maximum average symmetric surface distance of two methods are 2.5(1.6) and 2.4(1.3) mm, respectively.

  16. Motion and relativity

    CERN Document Server

    Infeld, Leopold

    1960-01-01

    Motion and Relativity focuses on the methodologies, solutions, and approaches involved in the study of motion and relativity, including the general relativity theory, gravitation, and approximation.The publication first offers information on notation and gravitational interaction and the general theory of motion. Discussions focus on the notation of the general relativity theory, field values on the world-lines, general statement of the physical problem, Newton's theory of gravitation, and forms for the equation of motion of the second kind. The text then takes a look at the approximation meth

  17. Brain Image Motion Correction

    DEFF Research Database (Denmark)

    Jensen, Rasmus Ramsbøl; Benjaminsen, Claus; Larsen, Rasmus

    2015-01-01

    The application of motion tracking is wide, including: industrial production lines, motion interaction in gaming, computer-aided surgery and motion correction in medical brain imaging. Several devices for motion tracking exist using a variety of different methodologies. In order to use such devices...... offset and tracking noise in medical brain imaging. The data are generated from a phantom mounted on a rotary stage and have been collected using a Siemens High Resolution Research Tomograph for positron emission tomography. During acquisition the phantom was tracked with our latest tracking prototype...

  18. Human motion correction and representation method from motion camera

    Directory of Open Access Journals (Sweden)

    Hong-Bo Zhang

    2017-06-01

    Full Text Available Motion estimation is a basic issue for many computer vision tasks, such as human–computer interaction, motion objection detection and intelligent robot. In many practical scenes, the object movement goes with camera motion. Generally, motion descriptors directly based on optical flow are inaccurate and have low discrimination power. To this end, a novel motion correction method is proposed and a novel motion feature descriptor called the motion difference histogram (MDH for recognising human action is proposed in this study. Motion estimation results are corrected by background motion estimation and MDH encodes the motion difference between the background and the objects. Experimental results on video shot with camera motion show that the proposed motion correction method is effective and the recognition accuracy of MDH is better than that of the state-of-the-art motion descriptor.

  19. Teaching Projectile Motion

    Science.gov (United States)

    Summers, M. K.

    1977-01-01

    Described is a novel approach to the teaching of projectile motion of sixth form level. Students are asked to use an analogue circuit to observe projectile motion and to graph the experimental results. Using knowledge of basic dynamics, students are asked to explain the shape of the curves theoretically. (Author/MA)

  20. Smoothing of respiratory motion traces for motion-compensated radiotherapy.

    Science.gov (United States)

    Ernst, Floris; Schlaefer, Alexander; Schweikard, Achim

    2010-01-01

    The CyberKnife system has been used successfully for several years to radiosurgically treat tumors without the need for stereotactic fixation or sedation of the patient. It has been shown that tumor motion in the lung, liver, and pancreas can be tracked with acceptable accuracy and repeatability. However, highly precise targeting for tumors in the lower abdomen, especially for tumors which exhibit strong motion, remains problematic. Reasons for this are manifold, like the slow tracking system operating at 26.5 Hz, and using the signal from the tracking camera "as is." Since the motion recorded with the camera is used to compensate for system latency by prediction and the predicted signal is subsequently used to infer the tumor position from a correlation model based on x-ray imaging of gold fiducials around the tumor, camera noise directly influences the targeting accuracy. The goal of this work is to establish the suitability of a new smoothing method for respiratory motion traces used in motion-compensated radiotherapy. The authors endeavor to show that better prediction--With a lower rms error of the predicted signal--and/or smoother prediction is possible using this method. The authors evaluated six commercially available tracking systems (NDI Aurora, PolarisClassic, Polaris Vicra, MicronTracker2 H40, FP5000, and accuTrack compact). The authors first tracked markers both stationary and while in motion to establish the systems' noise characteristics. Then the authors applied a smoothing method based on the a trous wavelet decomposition to reduce the devices' noise level. Additionally, the smoothed signal of the moving target and a motion trace from actual human respiratory motion were subjected to prediction using the MULIN and the nLMS2 algorithms. The authors established that the noise distribution for a static target is Gaussian and that when the probe is moved such as to mimic human respiration, it remains Gaussian with the exception of the FP5000 and the

  1. Coordinated Control of Wave Energy Converters Subject to Motion Constraints

    National Research Council Canada - National Science Library

    Wang, Liguo; Engström, Jens; Leijon, Mats; Isberg, Jan

    2016-01-01

    ...) damping of each wave energy converter in the frequency domain in each sea state. In a case study, a wave energy farm consisting of four converters based on the concept developed by Uppsala University is studied...

  2. Perception-Aware Motion Planning via Multiobjective Search on GPUs

    OpenAIRE

    Ichter, Brian; Landry, Benoit; Schmerling, Edward; Pavone, Marco

    2017-01-01

    In this paper we describe a framework towards computing well-localized, robust motion plans through the perception-aware motion planning problem, whereby we seek a low-cost motion plan subject to a separate constraint on perception localization quality. To solve this problem we introduce the Multiobjective Perception-Aware Planning (MPAP) algorithm which explores the state space via a multiobjective search, considering both cost and a perception heuristic. This framework can accommodate a lar...

  3. Measurement and Quantification of Gross Human Shoulder Motion

    Directory of Open Access Journals (Sweden)

    Jeremy T. Newkirk

    2013-01-01

    Full Text Available The shoulder girdle plays an important role in the large pointing workspace that humans enjoy. The goal of this work was to characterize the human shoulder girdle motion in relation to the arm. The overall motion of the human shoulder girdle was characterized based on motion studies completed on test subjects during voluntary (natural/unforced motion. The collected data from the experiments were used to develop surface fit equations that represent the position and orientation of the glenohumeral joint for a given humeral pointing direction. These equations completely quantify gross human shoulder girdle motion relative to the humerus. The equations are presented along with goodness-of-fit results that indicate the equations well approximate the motion of the human glenohumeral joint. This is the first time the motion has been quantified for the entire workspace, and the equations provide a reference against which to compare future work.

  4. Registration of Large Motion Blurred CMOS Images

    Science.gov (United States)

    2017-08-28

    any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information   if it does not display a...Comprehensive comparisons with state-of-the art methods reveal that their approach not only exhibits significant computational gains and unconstrained...functionality but also leads to improved performance. 15. SUBJECT TERMS Image Processing, Motion Blur, charge-coupled device, complementary metal-oxide

  5. A Motion-Adaptive Deinterlacer via Hybrid Motion Detection and Edge-Pattern Recognition

    Directory of Open Access Journals (Sweden)

    He-Yuan Lin

    2008-03-01

    Full Text Available A novel motion-adaptive deinterlacing algorithm with edge-pattern recognition and hybrid motion detection is introduced. The great variety of video contents makes the processing of assorted motion, edges, textures, and the combination of them very difficult with a single algorithm. The edge-pattern recognition algorithm introduced in this paper exhibits the flexibility in processing both textures and edges which need to be separately accomplished by line average and edge-based line average before. Moreover, predicting the neighboring pixels for pattern analysis and interpolation further enhances the adaptability of the edge-pattern recognition unit when motion detection is incorporated. Our hybrid motion detection features accurate detection of fast and slow motion in interlaced video and also the motion with edges. Using only three fields for detection also renders higher temporal correlation for interpolation. The better performance of our deinterlacing algorithm with higher content-adaptability and less memory cost than the state-of-the-art 4-field motion detection algorithms can be seen from the subjective and objective experimental results of the CIF and PAL video sequences.

  6. A Motion-Adaptive Deinterlacer via Hybrid Motion Detection and Edge-Pattern Recognition

    Directory of Open Access Journals (Sweden)

    Li Hsin-Te

    2008-01-01

    Full Text Available Abstract A novel motion-adaptive deinterlacing algorithm with edge-pattern recognition and hybrid motion detection is introduced. The great variety of video contents makes the processing of assorted motion, edges, textures, and the combination of them very difficult with a single algorithm. The edge-pattern recognition algorithm introduced in this paper exhibits the flexibility in processing both textures and edges which need to be separately accomplished by line average and edge-based line average before. Moreover, predicting the neighboring pixels for pattern analysis and interpolation further enhances the adaptability of the edge-pattern recognition unit when motion detection is incorporated. Our hybrid motion detection features accurate detection of fast and slow motion in interlaced video and also the motion with edges. Using only three fields for detection also renders higher temporal correlation for interpolation. The better performance of our deinterlacing algorithm with higher content-adaptability and less memory cost than the state-of-the-art 4-field motion detection algorithms can be seen from the subjective and objective experimental results of the CIF and PAL video sequences.

  7. The hydrogen-poor superluminous supernova iPTF 13ajg and its host galaxy in absorption and emission

    Energy Technology Data Exchange (ETDEWEB)

    Vreeswijk, Paul M.; Gal-Yam, Avishay; De Cia, Annalisa; Rubin, Adam; Yaron, Ofer; Tal, David; Ofek, Eran O. [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 7610001 (Israel); Savaglio, Sandra [Max Planck Institute for Extraterrestrial Physics, D-85748 Garching bei München (Germany); Quimby, Robert M. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, The University of Tokyo 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8583 (Japan); Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Cenko, S. Bradley; Filippenko, Alexei V.; Clubb, Kelsey I. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Perley, Daniel A.; Cao, Yi [Astronomy Department, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Taddia, Francesco; Sollerman, Jesper; Leloudas, Giorgos [Department of Astronomy, The Oskar Klein Center, Stockholm University, AlbaNova 10691 Stockholm (Sweden); Arcavi, Iair [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States); Kasliwal, Mansi M., E-mail: paul.vreeswijk@weizmann.ac.il [The Observatories, Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); and others

    2014-12-10

    We present imaging and spectroscopy of a hydrogen-poor superluminous supernova (SLSN) discovered by the intermediate Palomar Transient Factory, iPTF 13ajg. At a redshift of z = 0.7403, derived from narrow absorption lines, iPTF 13ajg peaked at an absolute magnitude of M {sub u,} {sub AB} = –22.5, one of the most luminous supernovae to date. The observed bolometric peak luminosity of iPTF 13ajg is 3.2 × 10{sup 44} erg s{sup –1}, while the estimated total radiated energy is 1.3 × 10{sup 51} erg. We detect narrow absorption lines of Mg I, Mg II, and Fe II, associated with the cold interstellar medium in the host galaxy, at two different epochs with X-shooter at the Very Large Telescope. From Voigt profile fitting, we derive the column densities log N(Mg I) =11.94 ± 0.06, log N(Mg II) =14.7 ± 0.3, and log N(Fe II) =14.25 ± 0.10. These column densities, as well as the Mg I and Mg II equivalent widths of a sample of hydrogen-poor SLSNe taken from the literature, are at the low end of those derived for gamma-ray bursts (GRBs) whose progenitors are also thought to be massive stars. This suggests that the environments of hydrogen-poor SLSNe and GRBs are different. From the nondetection of Fe II fine-structure absorption lines, we derive a lower limit on the distance between the supernova and the narrow-line absorbing gas of 50 pc. The neutral gas responsible for the absorption in iPTF 13ajg exhibits a single narrow component with a low velocity width, ΔV = 76 km s{sup –1}, indicating a low-mass host galaxy. No host galaxy emission lines are detected, leading to an upper limit on the unobscured star formation rate (SFR) of SFR{sub [O} {sub II]}<0.07M{sub ⊙}yr{sup −1}. Late-time imaging shows the iPTF 13ajg host galaxy to be faint, with g {sub AB} ≈ 27.0 and R {sub AB} ≥ 26.0 mag, corresponding to M {sub B,} {sub Vega} ≳ –17.7 mag.

  8. Quantitative analysis of facial motion components: anatomic and nonanatomic motion in normal persons and in patients with complete facial paralysis.

    Science.gov (United States)

    Bajaj-Luthra, A; Mueller, T; Johnson, P C

    1997-06-01

    The maximal static response assay of facial motion, described in 1994, enables the simultaneous measurement of multiple facial motions by tracking the positions of specific facial points. While the maximal static response assay provides accurate measurement of facial motion, the analysis of these data lacks the simplicity of a single-number scale such as the House-Brackmann system, a subjective scale traditionally used to classify facial function. The purpose of this study was to develop a simplified numerical index capable of summarizing the data generated by the maximal static response assay in a clinically meaningful way. We also wanted to develop a method whereby only anatomic motion or nonanatomic motion in the paralyzed face could be quantitated. Anatomic motion is the motion of the specific facial points studied by the maximal static response assay that can be attributed solely to the pull of the regional facial muscles that govern the movement of those points. Nonanatomic motion is motion that is secondary to the pull of the unaffected contralateral muscles that is transmitted to the paralyzed hemiface. Thirty-four patients with complete facial paralysis were studied. The maximal static response assay was performed on all patients on presentation to the Facial Nerve Center at the University of Pittsburgh Medical Center or after development of complete facial palsy postoperatively. The data from these patients were compared with maximal static response assay data from 26 unaffected controls. The anatomic index of facial motion and the nonanatomic index of facial motion were calculated for all study participants. The anatomic index of facial motion measures anatomic facial motion, and the nonanatomic index of facial motion measures nonanatomic facial motion. To calculate the anatomic index of facial motion, the vector magnitudes of the supraorbital, infraorbital, and modiolar motions during brow lift, eye closure, and smile are summed. The anatomic index of

  9. High School Students' Understanding of Projectile Motion Concepts

    Science.gov (United States)

    Dilber, Refik; Karaman, Ibrahim; Duzgun, Bahattin

    2009-01-01

    The aim of this study was to investigate the effectiveness of conceptual change-based instruction and traditionally designed physics instruction on students' understanding of projectile motion concepts. Misconceptions related to projectile motion concepts were determined by related literature on this subject. Accordingly, the Projectile Motion…

  10. Horizontal and vertical projectile motion in a resistant medium ...

    African Journals Online (AJOL)

    A study of projectile motion in a resistant medium subject to varying path angles and speed was carried out. Solutions to the governing equations of motion is developed employing double integration. Analysis of the results shows that the path of the particle in a resistant medium is affected by both increase in path angle and ...

  11. Effect of ship motion on spinal loading during manual lifting

    NARCIS (Netherlands)

    Faber, G.S.; Kingma, I.; Delleman, N.; Dieën, J. van

    2008-01-01

    This study investigated the effects of ship motion on peak spinal loading during lifting. All measurements were done on a ship at sea. In 1-min trials, which were repeated over a wide range of sailing conditions, subjects lifted an 18 kg box five times. Ship motion, whole body kinematics, ground

  12. Method through motion

    DEFF Research Database (Denmark)

    Steijn, Arthur

    2016-01-01

    Contemporary scenography often consists of video-projected motion graphics. The field is lacking in academic methods and rigour: descriptions and models relevant for the creation as well as in the analysis of existing works. In order to understand the phenomenon of motion graphics in a scenographic...... context, I have been conducting a practice-led research project. Central to the project is construction of a design model describing sets of procedures, concepts and terminology relevant for design and studies of motion graphics in spatial contexts. The focus of this paper is the role of model...

  13. Analysis and Modelling of Muscles Motion during Whole Body Vibration

    Directory of Open Access Journals (Sweden)

    La Gatta A

    2010-01-01

    Full Text Available The aim of the study is to characterize the local muscles motion in individuals undergoing whole body mechanical stimulation. In this study we aim also to evaluate how subject positioning modifies vibration dumping, altering local mechanical stimulus. Vibrations were delivered to subjects by the use of a vibrating platform, while stimulation frequency was increased linearly from 15 to 60 Hz. Two different subject postures were here analysed. Platform and muscles motion were monitored using tiny MEMS accelerometers; a contra lateral analysis was also presented. Muscle motion analysis revealed typical displacement trajectories: motion components were found not to be purely sinusoidal neither in phase to each other. Results also revealed a mechanical resonant-like behaviour at some muscles, similar to a second-order system response. Resonance frequencies and dumping factors depended on subject and his positioning. Proper mechanical stimulation can maximize muscle spindle solicitation, which may produce a more effective muscle activation.

  14. Motion Alters Color Appearance

    Science.gov (United States)

    Hong, Sang-Wook; Kang, Min-Suk

    2016-01-01

    Chromatic induction compellingly demonstrates that chromatic context as well as spectral lights reflected from an object determines its color appearance. Here, we show that when one colored object moves around an identical stationary object, the perceived saturation of the stationary object decreases dramatically whereas the saturation of the moving object increases. These color appearance shifts in the opposite directions suggest that normalization induced by the object’s motion may mediate the shift in color appearance. We ruled out other plausible alternatives such as local adaptation, attention, and transient neural responses that could explain the color shift without assuming interaction between color and motion processing. These results demonstrate that the motion of an object affects both its own color appearance and the color appearance of a nearby object, suggesting a tight coupling between color and motion processing. PMID:27824098

  15. Projectile Motion with Mathematica.

    Science.gov (United States)

    de Alwis, Tilak

    2000-01-01

    Describes how to use the computer algebra system (CAS) Mathematica to analyze projectile motion with and without air resistance. These experiments result in several conjectures leading to theorems. (Contains 17 references.) (Author/ASK)

  16. Projectile Motion Details.

    Science.gov (United States)

    Schnick, Jeffrey W.

    1994-01-01

    Presents an exercise that attempts to correct for the common discrepancies between theoretical and experimental predictions concerning projectile motion using a spring-loaded projectile ball launcher. Includes common correction factors for student use. (MVL)

  17. A Projectile Motion Bullseye.

    Science.gov (United States)

    Lamb, William G.

    1985-01-01

    Explains a projectile motion experiment involving a bow and arrow. Procedures to measure "muzzle" velocity, bow elastic potential energy, range, flight time, wind resistance, and masses are considered. (DH)

  18. Molecular Motion Machine

    Science.gov (United States)

    Shourd, Melvin L.

    1977-01-01

    Describes the construction of an inexpensive apparatus which utilizes the oscillatory motion of 60 cycle AC current in conjunction with an electromagnetic to illustrate various principles and processes in geology. (SL)

  19. Toying with Motion.

    Science.gov (United States)

    Galus, Pamela J.

    2002-01-01

    Presents a variety of activities that support the development of an understanding of Newton's laws of motion. Activities use toy cars, mobile roads, and a seat-of-nails. Includes a scoring rubric. (DDR)

  20. Travelers' Health: Motion Sickness

    Science.gov (United States)

    ... motion by sea, car, train, air, and virtual reality immersion. Given sufficient stimulus all people with functional ... retching Sweating Cold sweats Excessive salivation Apathy Hyperventilation Increased sensitivity to odors Loss of appetite Headache Drowsiness ...

  1. Motion of a Pendulum

    Directory of Open Access Journals (Sweden)

    Jared Wynn

    2010-01-01

    Full Text Available The objective of this project is to derive and solve the equation of motion for a pendulum swinging at small angles in one dimension. The pendulum may be either a simple pendulum like a ball hanging from a string or a physical pendulum like a pendulum on a clock. For simplicity, we only considered small rotational angles so that the equation of motion becomes a harmonic oscillator.

  2. Superluminal advanced transmission of X waves undergoing frustrated total internal reflection: the evanescent fields and the Goos-Hänchen effect.

    Science.gov (United States)

    Shaarawi, Amr M; Tawfik, Bassem H; Besieris, Ioannis M

    2002-10-01

    A study of X waves undergoing frustrated total internal reflection at a planar slab is provided. This is achieved by choosing the spectral plane wave components of the incident X wave to fall on the upper interface at angles greater than the critical angle. Thus, evanescent fields are generated in the slab and the peak of the field tunneling through the slab appears to be transmitted at a superluminal speed. Furthermore, it is shown that for deep barrier penetration, the peak of the transmitted field emerges from the rear interface of the slab before the incident peak reaches the front interface. To understand this advanced transmission of the peak of the pulse, a detailed study of the behavior of the evanescent fields in the barrier region is undertaken. The difference in tunneling behavior between deep and shallow barrier penetrations is shown to be influenced by the sense of the Goos-Hänchen shift.

  3. The Superluminous SN DES13S2cmm as a Signature of a Quark-nova in a He-HMXB System

    Science.gov (United States)

    Ouyed, Rachid; Leahy, Denis; Koning, Nico

    2015-08-01

    We show that by appealing to a Quark-Nova (QN) (the explosive transition of a neutron star (NS) to a quark star (QS)) occurring in a helium-high-mass X-ray binary (He-HMXB) system we can account for the lightcurve of the first superluminous SN, DES13S2cmm, discovered by the Dark-energy Survey. The NS’s explosive conversion is triggered as a result of accretion during the He-HMXB’s second common envelope (CE) phase. The dense, relativistic, QN ejecta in turn energizes the extended He-rich CE in an inside-out shock heating process. We find an excellent fit (reduced χ2 of 1.09) to the bolometric light curve of SN DES13S2cmm including the late time emission, which we attribute to black hole accretion following the conversion of the QS to a black hole.

  4. Perpetual Motion Machine

    Directory of Open Access Journals (Sweden)

    D. Tsaousis

    2008-01-01

    Full Text Available Ever since the first century A.D. there have been relative descriptions of known devices as well as manufactures for the creation of perpetual motion machines. Although physics has led, with two thermodynamic laws, to the opinion that a perpetual motion machine is impossible to be manufactured, inventors of every age and educational level appear to claim that they have invented something «entirely new» or they have improved somebody else’s invention, which «will function henceforth perpetually»! However the fact of the failure in manufacturing a perpetual motion machine till now, it does not mean that countless historical elements for these fictional machines become indifferent. The discussion on every version of a perpetual motion machine on the one hand gives the chance to comprehend the inventor’s of each period level of knowledge and his way of thinking, and on the other hand, to locate the points where this «perpetual motion machine» clashes with the laws of nature and that’s why it is impossible to have been manufactured or have functioned. The presentation of a new «perpetual motion machine» has excited our interest to locate its weak points. According to the designer of it the machine functions with the work produced by the buoyant force

  5. Motion planning for gantry mounted manipulators

    DEFF Research Database (Denmark)

    Olsen, Anders Lau; Petersen, Henrik Gordon

    2007-01-01

    We present a roadmap based planner for finding robot motions for gantry mounted manipulators for a line welding application at Odense Steel Shipyard (OSS). The robot motions are planned subject to constraints on when the gantry may be moved. We show that random sampling of gantry configurations...... is a viable technique for positioning the manipulator and present a pruning technique for managing the growth of the roadmap. We discuss results from simulations and from applications at the shipyard, where a similar planner has now been implemented for production....

  6. Accretion Disk Spectra of the Ultra-Luminous X-Ray Sources in Nearby Spiral Galaxies and Galactic Superluminal Jet Sources

    Energy Technology Data Exchange (ETDEWEB)

    Mizuno, T

    2003-12-11

    Ultra-luminous Compact X-ray Sources (ULXs) in nearby spiral galaxies and Galactic superluminal jet sources share the common spectral characteristic that they have unusually high disk temperatures which cannot be explained in the framework of the standard optically thick accretion disk in the Schwarzschild metric. On the other hand, the standard accretion disk around the Kerr black hole might explain the observed high disk temperature, as the inner radius of the Kerr disk gets smaller and the disk temperature can be consequently higher. However, we point out that the observable Kerr disk spectra becomes significantly harder than Schwarzschild disk spectra only when the disk is highly inclined. This is because the emission from the innermost part of the accretion disk is Doppler-boosted for an edge-on Kerr disk, while hardly seen for a face-on disk. The Galactic superluminal jet sources are known to be highly inclined systems, thus their energy spectra may be explained with the standard Kerr disk with known black hole masses. For ULXs, on the other hand, the standard Kerr disk model seems implausible, since it is highly unlikely that their accretion disks are preferentially inclined, and, if edge-on Kerr disk model is applied, the black hole mass becomes unreasonably large (> 300 M{sub solar}). Instead, the slim disk (advection dominated optically thick disk) model is likely to explain the observed super-Eddington luminosities, hard energy spectra, and spectral variations of ULXs. We suggest that ULXs are accreting black holes with a few tens of solar mass, which is not unexpected from the standard stellar evolution scenario, and that their X-ray emission is from the slim disk shining at super-Eddington luminosities.

  7. Accretion Disk Spectra of the Ultra-luminous X-ray Sources in Nearby Spiral Galaxies and Galactic Superluminal Jet Sources

    Science.gov (United States)

    White, Nicholas E. (Technical Monitor); Ebisawa, Ken; Zycki, Piotr; Kubota, Aya; Mizuno, Tsunefumi; Watarai, Ken-ya

    2003-01-01

    Ultra-luminous Compact X-ray Sources (ULXs) in nearby spiral galaxies and Galactic superluminal jet sources share the common spectral characteristic that they have unusually high disk temperatures which cannot be explained in the framework of the standard optically thick accretion disk in the Schwarzschild metric. On the other hand, the standard accretion disk around the Kerr black hole might explain the observed high disk temperature, as the inner radius of the Kerr disk gets smaller and the disk temperature can be consequently higher. However, we point out that the observable Kerr disk spectra becomes significantly harder than Schwarzschild disk spectra only when the disk is highly inclined. This is because the emission from the innermost part of the accretion disk is Doppler-boosted for an edge-on Kerr disk, while hardly seen for a face-on disk. The Galactic superluminal jet sources are known to be highly inclined systems, thus their energy spectra may be explained with the standard Kerr disk with known black hole masses. For ULXs, on the other hand, the standard Kerr disk model seems implausible, since it is highly unlikely that their accretion disks are preferentially inclined, and, if edge-on Kerr disk model is applied, the black hole mass becomes unreasonably large (greater than or approximately equal to 300 Solar Mass). Instead, the slim disk (advection dominated optically thick disk) model is likely to explain the observed super- Eddington luminosities, hard energy spectra, and spectral variations of ULXs. We suggest that ULXs are accreting black holes with a few tens of solar mass, which is not unexpected from the standard stellar evolution scenario, and their X-ray emission is from the slim disk shining at super-Eddington luminosities.

  8. Tactile cueing in detecting and controlling pitch and roll motion.

    Science.gov (United States)

    Bouak, Fethi; Kline, Julianne; Cheung, Bob

    2011-10-01

    Tactile cueing has been explored primarily for the detection of linear motion such as vertical, longitudinal, and lateral translation in the laboratory and in flight. The usefulness of tactile cues in detecting roll and pitch motion has not been fully investigated. There were 12 subjects (21-56 yr) who were exposed to controlled pitch and roll motion generated by a motion platform with and without tactile cueing. The tactile system consists of a torso vest with 24 electromechanical tactors and a tactor on each shoulder and under each thigh harness, respectively. While devoid of visual and auditory cues, each subject performed three tasks: 1) indicate motion perception without tactile cues (C1); 2) return to vertical from an offset angle (C2); and 3) maintain straight and level while the platform was continuously in motion (C3). Our results indicated that in the absence of visual and auditory cues, subjects reported that the tactile system was useful in the execution of C2 and C3 maneuvers. Specifically, the presence of tactile cues had a significant impact on the accuracy, duration, and perceived workload. In addition, tactile cueing also increased the accuracy in returning to neutral from an offset position and in maintaining the neutral position while the platform was in continuous motion. Tactile cueing appears to be effective in detecting roll and pitch motion and has the potential to reduce the workload and risks of high stress and time sensitive air operations.

  9. Effects of Vibrotactile Feedback on Human Learning of Arm Motions

    Science.gov (United States)

    Bark, Karlin; Hyman, Emily; Tan, Frank; Cha, Elizabeth; Jax, Steven A.; Buxbaum, Laurel J.; Kuchenbecker, Katherine J.

    2015-01-01

    Tactile cues generated from lightweight, wearable actuators can help users learn new motions by providing immediate feedback on when and how to correct their movements. We present a vibrotactile motion guidance system that measures arm motions and provides vibration feedback when the user deviates from a desired trajectory. A study was conducted to test the effects of vibrotactile guidance on a subject’s ability to learn arm motions. Twenty-six subjects learned motions of varying difficulty with both visual (V), and visual and vibrotactile (VVT) feedback over the course of four days of training. After four days of rest, subjects returned to perform the motions from memory with no feedback. We found that augmenting visual feedback with vibrotactile feedback helped subjects reduce the root mean square (rms) angle error of their limb significantly while they were learning the motions, particularly for 1DOF motions. Analysis of the retention data showed no significant difference in rms angle errors between feedback conditions. PMID:25486644

  10. Anthropomorphic “Motion Design” on Non-Holonomic Vehicle for Intuitive Interface

    Directory of Open Access Journals (Sweden)

    Sho Yokota

    2012-11-01

    Full Text Available In the case of operating a vehicle, if the interface extracts human intention correctly and naturally, and if the vehicle moves like a human, then the human feels this operation to be intuitive. For realizing intuitive operation, this paper proposes motion design which makes vehicle motion anthropomorphic. The strategy of this motion design is: for making anthropomorphic motion, a certain normative motion for the vehicle is needed. Thus, we measure several subjects' motion in order to create normative motion. But these motions are different due to individual characteristics, because human motions are described in the time domain. Therefore, the human motion in the time domain is plotted to the phase plane. In the phase plane each subjects' motion was almost the same ellipse and then we fitted these ellipses to one ellipse by the least square method. Thus, we adopt this fitted ellipse as normative motion and call it “standard human motion”. The standard human motion is implemented on the actual non-holonomic vehicle and evaluated by the Semantic Differential (SD method. From the results, we discovered that our motion design can create anthropomorphic vehicle motion.

  11. Spatial and temporal EEG dynamics of motion sickness.

    Science.gov (United States)

    Chen, Yu-Chieh; Duann, Jeng-Ren; Chuang, Shang-Wen; Lin, Chun-Ling; Ko, Li-Wei; Jung, Tzyy-Ping; Lin, Chin-Teng

    2010-02-01

    This study investigates motion-sickness-related brain responses using a VR-based driving simulator on a motion platform with six degrees of freedom, which provides both visual and vestibular stimulations to induce motion sickness in a manner that is close to that in daily life. Subjects' brain dynamics associated with motion sickness were measured using a 32-channel EEG system. Their degree of motion sickness was simultaneously and continuously reported using an onsite joystick, providing non-stop behavioral references to the recorded EEG changes. The acquired EEG signals were parsed by independent component analysis (ICA) into maximally independent processes. The decomposition enables the brain dynamics that are induced by the motion of the platform and motion sickness to be disassociated. Five MS-related brain processes with equivalent dipoles located in the left motor, the parietal, the right motor, the occipital and the occipital midline areas were consistently identified across all subjects. The parietal and motor components exhibited significant alpha power suppression in response to vestibular stimuli, while the occipital components exhibited MS-related power augmentation in mainly theta and delta bands; the occipital midline components exhibited a broadband power increase. Further, time series cross-correlation analysis was employed to evaluate relationships between the spectral changes associated with different brain processes and the degree of motion sickness. According to our results, it is suggested both visual and vestibular stimulations should be used to induce motion sickness in brain dynamic studies. Copyright (c) 2009 Elsevier Inc. All rights reserved.

  12. PROMOTIONS: PROper MOTION Software

    Science.gov (United States)

    Caleb Wherry, John; Sahai, R.

    2009-05-01

    We report on the development of a software tool (PROMOTIONS) to streamline the process of measuring proper motions of material in expanding nebulae. Our tool makes use of IDL's widget programming capabilities to design a unique GUI that is used to compare images of the objects from two epochs. The software allows us to first orient and register the images to a common frame of reference and pixel scale, using field stars in each of the images. We then cross-correlate specific morphological features in order to determine their proper motions, which consist of the proper motion of the nebula as a whole (PM-neb), and expansion motions of the features relative to the center. If the central star is not visible (quite common in bipolar nebulae with dense dusty waists), point-symmetric expansion is assumed and we use the average motion of high-quality symmetric pairs of features on opposite sides of the nebular center to compute PM-neb. This is then subtracted out to determine the individual movements of these and additional features relative to the nebular center. PROMOTIONS should find wide applicability in measuring proper motions in astrophysical objects such as the expanding outflows/jets commonly seen around young and dying stars. We present first results from using PROMOTIONS to successfully measure proper motions in several pre-planetary nebulae (transition objects between the red giant and planetary nebula phases), using images taken 7-10 years apart with the WFPC2 and ACS instruments on board HST. The authors are grateful to NASA's Undergradute Scholars Research Program (USRP) for supporting this research.

  13. Elementary motion perception interferes with Film-induced emotions

    Directory of Open Access Journals (Sweden)

    Alhadi Chafi

    2014-01-01

    Full Text Available Many authors showed that dynamism in images increases emotional responses whether they were objectively or subjectively measured (Simons, Detenber, Reiss, & Shults, 2000; Ravaja, 2004. The aim was to investigate the effects of three elementary motions on emotional films’ perception, given that these motions involved changes in the perception of static emotional images (Chafi, Schiaratura, & Rusinek, 2012 and in the memorization of emotional words (Podevin, Chafi, Rusinek, & Békaert, 2012. Participants were shown short films validated by Schaefer, Nils, Sanchez, and Philippot (2010 in which were inlaid motion patterns from Chafi 'et al.' (2012. Results indicated that a wave-like, translational and parabolic motion do not have the same effects on emotional self-reports. More precisely, data suggest that the translational motion increased positive film-induced feelings of happiness and agitation compared to the parabolic motion. Further research shall be directed towards more objective ways of investigation.

  14. Measuring Behavior using Motion Capture

    NARCIS (Netherlands)

    Fikkert, F.W.; van der Kooij, Herman; Ruttkay, Z.M.; van Welbergen, H.; Spink, A.J.; Ballintijn, M.R.; Bogers, N.D.; Grieco, F; Loijens, L.W.S.; Noldus, L.P.J.J.; Smit, G; Zimmerman, P.H.

    2008-01-01

    Motion capture systems, using optical, magnetic or mechanical sensors are now widely used to record human motion. Motion capture provides us with precise measurements of human motion at a very high recording frequency and accuracy, resulting in a massive amount of movement data on several joints of

  15. Geologically current plate motions

    Science.gov (United States)

    DeMets, Charles; Gordon, Richard G.; Argus, Donald F.

    2010-04-01

    We describe best-fitting angular velocities and MORVEL, a new closure-enforced set of angular velocities for the geologically current motions of 25 tectonic plates that collectively occupy 97 per cent of Earth's surface. Seafloor spreading rates and fault azimuths are used to determine the motions of 19 plates bordered by mid-ocean ridges, including all the major plates. Six smaller plates with little or no connection to the mid-ocean ridges are linked to MORVEL with GPS station velocities and azimuthal data. By design, almost no kinematic information is exchanged between the geologically determined and geodetically constrained subsets of the global circuit-MORVEL thus averages motion over geological intervals for all the major plates. Plate geometry changes relative to NUVEL-1A include the incorporation of Nubia, Lwandle and Somalia plates for the former Africa plate, Capricorn, Australia and Macquarie plates for the former Australia plate, and Sur and South America plates for the former South America plate. MORVEL also includes Amur, Philippine Sea, Sundaland and Yangtze plates, making it more useful than NUVEL-1A for studies of deformation in Asia and the western Pacific. Seafloor spreading rates are estimated over the past 0.78 Myr for intermediate and fast spreading centres and since 3.16 Ma for slow and ultraslow spreading centres. Rates are adjusted downward by 0.6-2.6mmyr-1 to compensate for the several kilometre width of magnetic reversal zones. Nearly all the NUVEL-1A angular velocities differ significantly from the MORVEL angular velocities. The many new data, revised plate geometries, and correction for outward displacement thus significantly modify our knowledge of geologically current plate motions. MORVEL indicates significantly slower 0.78-Myr-average motion across the Nazca-Antarctic and Nazca-Pacific boundaries than does NUVEL-1A, consistent with a progressive slowdown in the eastward component of Nazca plate motion since 3.16 Ma. It also

  16. MACHINE MOTION EQUATIONS

    Directory of Open Access Journals (Sweden)

    Florian Ion Tiberiu Petrescu

    2015-09-01

    Full Text Available This paper presents the dynamic, original, machine motion equations. The equation of motion of the machine that generates angular speed of the shaft (which varies with position and rotation speed is deduced by conservation kinetic energy of the machine. An additional variation of angular speed is added by multiplying by the coefficient dynamic D (generated by the forces out of mechanism and or by the forces generated by the elasticity of the system. Kinetic energy conservation shows angular speed variation (from the shaft with inertial masses, while the dynamic coefficient introduces the variation of w with forces acting in the mechanism. Deriving the first equation of motion of the machine one can obtain the second equation of motion dynamic. From the second equation of motion of the machine it determines the angular acceleration of the shaft. It shows the distribution of the forces on the mechanism to the internal combustion heat engines. Dynamic, the velocities can be distributed in the same way as forces. Practically, in the dynamic regimes, the velocities have the same timing as the forces. Calculations should be made for an engine with a single cylinder. Originally exemplification is done for a classic distribution mechanism, and then even the module B distribution mechanism of an Otto engine type.

  17. Motion verb sentences activate left posterior middle temporal cortex despite static context

    DEFF Research Database (Denmark)

    Wallentin, M; Ellegaard Lund, Torben; Østergaard, Svend

    2005-01-01

    middle temporal region than sentences in which the motion can be applied to the subject noun. We speculate that the left posterior middle temporal region activity in fictive motion sentences reflects the fact that the hearer applies motion to the depicted scenario by scanning it egocentrically...

  18. A model-based time-reversal of left ventricular motion improves cardiac motion analysis using tagged MRI data

    Directory of Open Access Journals (Sweden)

    Cook Larry T

    2008-05-01

    Full Text Available Abstract Background Myocardial motion is an important observable for the assessment of heart condition. Accurate estimates of ventricular (LV wall motion are required for quantifying myocardial deformation and assessing local tissue function and viability. Harmonic Phase (HARP analysis was developed for measuring regional LV motion using tagged magnetic resonance imaging (tMRI data. With current computer-aided postprocessing tools including HARP analysis, large motions experienced by myocardial tissue are, however, often intractable to measure. This paper addresses this issue and provides a solution to make such measurements possible. Methods To improve the estimation performance of large cardiac motions while analyzing tMRI data sets, we propose a two-step solution. The first step involves constructing a model to describe average systolic motion of the LV wall within a subject group. The second step involves time-reversal of the model applied as a spatial coordinate transformation to digitally relax the contracted LV wall in the experimental data of a single subject to the beginning of systole. Cardiac tMRI scans were performed on four healthy rats and used for developing the forward LV model. Algorithms were implemented for preprocessing the tMRI data, optimizing the model parameters and performing the HARP analysis. Slices from the midventricular level were then analyzed for all systolic phases. Results The time-reversal operation derived from the LV model accounted for the bulk portion of the myocardial motion, which was the average motion experienced within the overall subject population. In analyzing the individual tMRI data sets, removing this average with the time-reversal operation left small magnitude residual motion unique to the case. This remaining residual portion of the motion was estimated robustly using the HARP analysis. Conclusion Utilizing a combination of the forward LV model and its time reversal improves the performance of

  19. Full-motion video analysis for improved gender classification

    Science.gov (United States)

    Flora, Jeffrey B.; Lochtefeld, Darrell F.; Iftekharuddin, Khan M.

    2014-06-01

    The ability of computer systems to perform gender classification using the dynamic motion of the human subject has important applications in medicine, human factors, and human-computer interface systems. Previous works in motion analysis have used data from sensors (including gyroscopes, accelerometers, and force plates), radar signatures, and video. However, full-motion video, motion capture, range data provides a higher resolution time and spatial dataset for the analysis of dynamic motion. Works using motion capture data have been limited by small datasets in a controlled environment. In this paper, we explore machine learning techniques to a new dataset that has a larger number of subjects. Additionally, these subjects move unrestricted through a capture volume, representing a more realistic, less controlled environment. We conclude that existing linear classification methods are insufficient for the gender classification for larger dataset captured in relatively uncontrolled environment. A method based on a nonlinear support vector machine classifier is proposed to obtain gender classification for the larger dataset. In experimental testing with a dataset consisting of 98 trials (49 subjects, 2 trials per subject), classification rates using leave-one-out cross-validation are improved from 73% using linear discriminant analysis to 88% using the nonlinear support vector machine classifier.

  20. Current techniques for measuring motion.

    Science.gov (United States)

    Atha, J

    1984-12-01

    The sports scientist and the ergonomist, although sharing a common disciplinary background, pursue fundamentally different goals. The patterns of approach to the analysis of movement they adopt are, nevertheless, similar and a model of this approach is presented. Some potential sources of error associated with each stage of the process are identified. In measuring motion in sport, cinematography has played a dominant role. The method has obvious advantages; but analysing film is a slow, pedestrian task, and subject to human error. Where an investigator is experienced and understands his problem clearly he can often achieve his aims with a limited number of measurement variables. This may also mean he can adopt automatic and specific techniques of acquiring information. Such methods include alternative photographic techniques, but also involve the specialised transducers and automatic analysers that are now burgeoning in the field. Some of these techniques are discussed.