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Sample records for superluminal weak speed

  1. Superluminal pulse reflection from a weakly absorbing dielectric slab

    CERN Document Server

    Wang, L G; Wang, Li-Gang; Zhu, Shi-Yao

    2006-01-01

    Group delay for a reflected light pulse from a weakly absorbing dielectric slab is theoretically investigated, and large negative group delay is found for weak absorption near a resonance of the slab ($Re(kd)=m\\pi$). The group delays for both the reflected and transmitted pulses will be saturated with the increase of the absorption.

  2. Speed of the CERN Neutrinos released on 22.9.2011 - Was stated superluminality due to neglecting General Relativity?

    CERN Document Server

    Kundt, Wolfgang

    2011-01-01

    During the years 2009 to 2011, neutrino beams were fired repeatedly from CERN towards a detector in Italy's Gran Sasso tunnel, some 4 deg south and 7 deg east of CERN, at a distance of 730.5 km, in the shape of short bunches of particles. Their time of flight (2.5 msec) was measured at high accuracy (nsec) with caesium clocks (Reich 2011). Remarkably, the CNGS team found a deficit of 61 nsec compared with propagation at the speed of light, and concluded at superluminal speeds, of order 10$^{-4.6}$. In this communication, I will argue that this is the first experiment to test Einstein's theory for the (weak) gravity field of Earth, with the result that the neutrinos propagated (just) luminally.

  3. 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.

  4. 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.

  5. Superluminal Recession Velocities

    CERN Document Server

    Davis, T M; Davis, Tamara M.; Lineweaver, Charles H.

    2000-01-01

    Hubble's Law, v=HD (recession velocity is proportional to distance), is a theoretical result derived from the Friedmann-Robertson-Walker metric. v=HD applies at least as far as the particle horizon and in principle for all distances. Thus, galaxies with distances greater than D=c/H are receding from us with velocities greater than the speed of light and superluminal recession is a fundamental part of the general relativistic description of the expanding universe. This apparent contradiction of special relativity (SR) is often mistakenly remedied by converting redshift to velocity using SR. Here we show that galaxies with recession velocities faster than the speed of light are observable and that in all viable cosmological models, galaxies above a redshift of three are receding superluminally.

  6. Gamow's bicycle: The Appearance of Bodies at Relativistic Speeds and Apparent Superluminal Velocities

    CERN Document Server

    Nowojewski, A

    2005-01-01

    A human creates an image basing on the information delivered by photons that arrived at his retina simultaneously. Due to finite and constant velocity of light these photons left the moving body at different times, since not all points of the body are equidistant. In other words its image represents the body as it was in several different times i.e. it is distorted and does not correspond to its real appearance. The useful experimental arrangement is set and then used to derive the general expression that transforms two-dimensional stationary shapes to their apparent forms, which could be photographed once they are set in motion. It is then used to simulate the so-called Gamow's bicycle combined out of circles and straight lines. The simulation outlines two important aspects of bike's motion: apparent distance of two points and apparent velocity which are then discussed thoroughly. It is found that the approaching body is elongated and its apparent speed is greater than its real one (under certain conditions ...

  7. 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.

  8. 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...

  9. 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.

  10. OPERA superluminal neutrinos and Kinematics in Finsler spacetime

    CERN Document Server

    Chang, Zhe; Wang, Sai

    2011-01-01

    The OPERA collaboration recently reported that muon neutrinos could be superluminal. More recently, Cohen and Glashow pointed that such superluminal neutrinos would be suppressed since they lose their energies rapidly via bremsstrahlung. In this Letter, we propose that Finslerian nature of spacetime could account for the superluminal phenomena of particles. The Finsler spacetime permits the existence of superluminal behavior of particles while the casuality still holds. A new dispersion relation is obtained in a class of Finsler spacetime. It is shown that the superluminal speed is linearly dependent on the energy per unit mass of the particle. We find that such a superluminal speed formula is consistent with data of OPERA, MINOS and Fermilab-1979 neutrino experiments as well as observations on neutrinos from SN1987a.

  11. Nonlinearity without Superluminality

    CERN Document Server

    Kent, A

    2002-01-01

    Quantum theory is compatible with special relativity. In particular, though measurements on entangled systems are correlated in a way that cannot be reproduced by local hidden variables, they cannot be used for superluminal signalling. As Gisin and Polchinski first pointed out, this is not true for general nonlinear modifications of the Schroedinger equation. Excluding superluminal signalling has thus been taken to rule out most nonlinear versions of quantum theory. The no superluminal signalling constraint has also been used for alternative derivations of the optimal fidelities attainable for imperfect quantum cloning and other operations. These results apply to theories satisfying the rule that their predictions for widely separated and slowly moving entangled systems can be approximated by non-relativistic equations of motion with respect to a preferred time coordinate. This paper describes a natural way in which this rule might fail to hold. In particular, it is shown that quantum readout devices which di...

  12. High-speed demodulation system of identical weak FBGs based on FDML wavelength swept laser

    Science.gov (United States)

    Wang, Yiming; Liu, Quan; Wang, Honghai; Hu, Chenchen; Zhang, Chun; Li, Zhengying

    2017-04-01

    An identical weak reflection FBGs demodulation system based on a FDML laser is proposed. The laser is developed to output a continuous wavelength-swept spectrum in the scanning frequency of 120 kHz over a spectral range of more than 10nm at 1.54 μm. Based on this high-speed wavelength-swept light and the optical transmission delay effect, the demodulation system obtains the location and wavelength information of all identical weak FBGs by the reflected spectrum within each scanning cycle. By accessing to a high-speed FPGA processing module, continuous demodulation of 120 kHz is realized. The system breakthroughs the bandwidth of the laser to expand the sensors capacity and greatly improves the demodulation speed of a TDM sensing network. The experiments show the system can distinguish and demodulate the identical weak FBGs and measure the 4 kHz vibration at 120 kHz demodulation speed.

  13. 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.

  14. Field signature for apparently superluminal particle motion

    CERN Document Server

    Land, Martin

    2016-01-01

    In the context of Stueckelberg's covariant symplectic mechanics, Horwitz and Aharonovich 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.

  15. Cosmology with Superluminous Supernovae

    CERN Document Server

    Scovacricchi, Dario; Bacon, David; Sullivan, Mark; Prajs, Szymon

    2015-01-01

    We predict cosmological constraints for forthcoming surveys using Superluminous Supernovae (SLSNe) as standardisable candles. Due to their high peak luminosity, these events can be observed to high redshift (z~3), opening up new possibilities to probe the Universe in the deceleration epoch. We describe our methodology for creating mock Hubble diagrams for the Dark Energy Survey (DES), the "Search Using DECam for Superluminous Supernovae" (SUDSS) and a sample of SLSNe possible from the Large Synoptic Survey Telescope (LSST), exploring a range of standardisation values for SLSNe. We include uncertainties due to gravitational lensing and marginalise over possible uncertainties in the magnitude scale of the observations (e.g. uncertain absolute peak magnitude, calibration errors). We find that the addition of only ~100 SLSNe from SUDSS to 3800 Type Ia Supernovae (SNe Ia) from DES can improve the constraints on w and Omega_m by at least 20% (assuming a flat wCDM universe). Moreover, the combination of DES SNe Ia a...

  16. Superluminal Spot Pair Events in Astronomical Settings: Sweeping Beams

    CERN Document Server

    Nemiroff, Robert J

    2014-01-01

    Sweeping beams of light can cast spots moving with superluminal speeds across scattering surfaces. Such faster-than-light speeds are well-known phenomena that do not violate special relativity. It is shown here that under certain circumstances, superluminal spot pair creation and annihilation events can occur that provide unique information to observers. These spot pair events are {\\it not} particle pair events -- they are the sudden creation or annihilation of a pair of relatively illuminated spots on a scattering surface. Real spot pair illumination events occur unambiguously on the scattering surface when spot speeds diverge, while virtual spot pair events are observer dependent and perceived only when real spot radial speeds cross the speed of light. Specifically, a virtual spot pair creation event will be observed when a real spot's speed toward the observer drops below $c$, while a virtual spot pair annihilation event will be observed when a real spot's radial speed away from the observer rises above $c...

  17. Superluminal radiation by uniformly moving charges

    Science.gov (United States)

    Tomaschitz, Roman

    2003-03-01

    The emission of superluminal quanta (tachyons) by freely propagating particles is scrutinized. Estimates are derived for spontaneous superluminal radiation from electrons moving close to the speed of the Galaxy in the microwave background. This is the threshold velocity for tachyon radiation to occur, a lower bound. Quantitative estimates are also given for the opposite limit, tachyon radiation emitted by ultra-relativistic electrons in linear colliders and supernova shock waves. The superluminal energy flux is studied and the spectral energy density of the radiation is derived, classically as well as in second quantization. There is a transversal bosonic and a longitudinal fermionic component of the radiation. We calculate the power radiated, its angular dependence, the mean energy of the radiated quanta, absorption and emission rates, as well as tachyonic number counts. We explain how the symmetry of the Einstein /A-coefficients connects to time-symmetric wave propagation and to the Wheeler-Feynman absorber theory. A relation between the tachyon mass and the velocity of the Local Group of galaxies is suggested.

  18. Superluminal Black Holes

    CERN Document Server

    Dolgov, D S

    1993-01-01

    The new solution of the Einstein equations in empty space is presented. The solution is constructed using Schwarzschild solution but essentially differs from it. The basic properties of the solution are: the existence of a horizon which is a hyperboloid of one sheet moving along its axis with superluminal velocity, right signature of the metric outside the horizon and Minkovsky-flatness of it at infinity outside the horizon. There is also a discussion in the last chapter, including comparing with recent astronomical observations.

  19. Superluminality and UV Completion

    CERN Document Server

    Shore, G M

    2007-01-01

    The idea that the existence of a consistent UV completion satisfying the fundamental axioms of local quantum field theory or string theory may impose positivity constraints on the couplings of the leading irrelevant operators in a low-energy effective field theory is critically discussed. Violation of these constraints implies superluminal propagation, in the sense that the low-frequency limit of the phase velocity $v_{\\rm ph}(0)$ exceeds $c$. It is explained why causality is related not to $v_{\\rm ph}(0)$ but to the high-frequency limit $v_{\\rm ph}(\\infty)$ and how these are related by the Kramers-Kronig dispersion relation, depending on the sign of the imaginary part of the refractive index $\\Ima n(\\w)$ which is normally assumed positive. Superluminal propagation and its relation to UV completion is investigated in detail in three theories: QED in a background electromagnetic field, where the full dispersion relation for $n(\\w)$ is evaluated numerically for the first time and the role of the null energy con...

  20. 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.

  1. Jet Stability and the Generation of Superluminal and Stationary Components

    Science.gov (United States)

    Agudo, Ivan; Gomez, Jose-Luis; Marti, Jose-Maria; Ibanez, Jose-Maria; Marscher, Alan P.; Alberdi, Antonio; Aloy, Miguel-Angel; Hardee, Philip E.

    2001-01-01

    We present a numerical simulation of the response of an expanding relativistic jet to the ejection of a superluminal component. The simulation has been performed with a relativistic time-dependent hydrodynamical code from which simulated radio maps are computed by integrating the transfer equations for synchrotron radiation. The interaction of the superluminal component with the underlying jet results in the formation of multiple conical shocks behind the main perturbation. These trailing components can be easily distinguished because they appear to be released from the primary superluminal component instead of being ejected from the core. Their oblique nature should also result in distinct polarization properties. Those appearing closer to the core show small apparent motions and a very slow secular decrease in brightness and could be identified as stationary components. Those appearing farther downstream are weaker and can reach superluminal apparent motions. The existence of these trailing components indicates that not all observed components necessarily represent major perturbations at the jet inlet; rather, multiple emission components can be generated by a single disturbance in the jet. While the superluminal component associated with the primary perturbation exhibits a rather stable pattern speed, trailing components have velocities that increase with distance from the core but move at less than the jet speed. The trailing components exhibit motion and structure consistent with the triggering of pinch modes by the superluminal component. The increase in velocity of the trailing components is an indirect consequence of the acceleration of the expanding fluid, which is assumed to be relativistically hot; if observed, such accelerations would therefore favor an electron-positron (as opposed to proton rest mass) dominated jet.

  2. Superluminal Neutrinos and Monopoles

    CERN Document Server

    Wang, Peng; 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 braking (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 causes effective metric to the neutrinos, different from the Minkovski one. We find that the monopoles have influences on neutrinos only within the range about $10^3$ cm. Neutrinos always arrive earlier than photons by the same amount of time, once there exists a monopole on or close to their trajectories. This result reconciles the contradiction between OPERA and supernova neutrinos.

  3. Cosmology with superluminous supernovae

    Science.gov (United States)

    Scovacricchi, D.; Nichol, R. C.; Bacon, D.; Sullivan, M.; Prajs, S.

    2016-02-01

    We predict cosmological constraints for forthcoming surveys using superluminous supernovae (SLSNe) as standardizable candles. Due to their high peak luminosity, these events can be observed to high redshift (z ˜ 3), opening up new possibilities to probe the Universe in the deceleration epoch. We describe our methodology for creating mock Hubble diagrams for the Dark Energy Survey (DES), the `Search Using DECam for Superluminous Supernovae' (SUDSS) and a sample of SLSNe possible from the Large Synoptic Survey Telescope (LSST), exploring a range of standardization values for SLSNe. We include uncertainties due to gravitational lensing and marginalize over possible uncertainties in the magnitude scale of the observations (e.g. uncertain absolute peak magnitude, calibration errors). We find that the addition of only ≃100 SLSNe from SUDSS to 3800 Type Ia Supernovae (SNe Ia) from DES can improve the constraints on w and Ωm by at least 20 per cent (assuming a flat wCDM universe). Moreover, the combination of DES SNe Ia and 10 000 LSST-like SLSNe can measure Ωm and w to 2 and 4 per cent, respectively. The real power of SLSNe becomes evident when we consider possible temporal variations in w(a), giving possible uncertainties of only 2, 5 and 14 per cent on Ωm, w0 and wa, respectively, from the combination of DES SNe Ia, LSST-like SLSNe and Planck. These errors are competitive with predicted Euclid constraints, indicating a future role for SLSNe for probing the high-redshift Universe.

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

    CERN Document Server

    Borghardt, A A; Karpenko, D Y

    2003-01-01

    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.

  5. Challenges Confronting Superluminal Neutrino Models

    Science.gov (United States)

    Evslin, Jarah

    2012-12-01

    This talk opens the CosPA2011 session on OPERA's superluminal neutrino claim. I summarize relevant observations and constraints from OPERA, MINOS, ICARUS, KamLAND, IceCube and LEP as well as observations of SN1987A. I selectively review some models of neutrino superluminality which have been proposed since OPERA's announcement, focusing on a neutrino dark energy model. Powerful theoretical constraints on these models arise from Cohen-Glashow bremsstrahlung and from phase space requirements for the initial neutrino production. I discuss these constraints and how they might be evaded in models in which the maximum velocities of both neutrinos and charged leptons are equal but only superluminal inside of a dense medium.

  6. Challenges Confronting Superluminal Neutrino Models

    CERN Document Server

    Evslin, Jarah

    2011-01-01

    This talk opens the CosPA2011 session on OPERA's superluminal neutrino claim. I summarize relevant observations and constraints from OPERA, MINOS, ICARUS, KamLAND, IceCube and LEP as well as observations of SN1987A. I selectively review some models of neutrino superluminality which have been proposed since OPERA's announcement, focusing on a neutrino dark energy model. Powerful theoretical constraints on these models arise from Cohen-Glashow bremsstrahlung and from phase space requirements for the initial neutrino production. I discuss these constraints and how they might be evaded in models in which the maximum velocities of both neutrinos and charged leptons are equal but only superluminal inside of a dense medium.

  7. Progress on a Taylor weak statement finite element algorithm for high-speed aerodynamic flows

    Science.gov (United States)

    Baker, A. J.; Freels, J. D.

    1989-01-01

    A new finite element numerical Computational Fluid Dynamics (CFD) algorithm has matured to the point of efficiently solving two-dimensional high speed real-gas compressible flow problems in generalized coordinates on modern vector computer systems. The algorithm employs a Taylor Weak Statement classical Galerkin formulation, a variably implicit Newton iteration, and a tensor matrix product factorization of the linear algebra Jacobian under a generalized coordinate transformation. Allowing for a general two-dimensional conservation law system, the algorithm has been exercised on the Euler and laminar forms of the Navier-Stokes equations. Real-gas fluid properties are admitted, and numerical results verify solution accuracy, efficiency, and stability over a range of test problem parameters.

  8. Superluminal light propagation via quantum interference in decay channels

    OpenAIRE

    Arun, R.

    2016-01-01

    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 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 ...

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

    CERN Document Server

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

    2015-01-01

    The invariance of the speed of light implies a series of consequences related to our perception of simultaneity and of time itself. Whilst these consequences are experimentally well studied for subluminal speeds, the kinematics of superluminal motion lack direct evidence. Using high temporal resolution imaging techniques, we demonstrate that if a source approaches an observer at superluminal speeds, the temporal ordering of events is inverted and its image appears to propagate backwards. If the source changes its speed, crossing the interface between sub- and super-luminal propagation, we observe image pair annihilation and creation. These results show that it is not possible to unambiguously determine the kinematics of an event from imaging and time-resolved measurements alone.

  10. A note on superluminal neutrinos

    Science.gov (United States)

    Cutolo, A.

    2012-05-01

    Although characterized by a possible experimental error, the first results of the Opera experiment at CERN have opened up a hot discussion on the possibility of superluminal neutrinos already observed in some space events. In particular, Cohen and Glashow (CG) have considered it simply an error justifying their position on the basis of the bremsstrahlung of electron-positron pairs. In this paper, we would like to discuss this position also in view of the recent derivation of the superluminal limit as a consequence of the classical causality principle. Even if the final answer is related only to the review of all the experimental results, we believe that neutral particles (neutrinos, photons, etc.) might exhibit superluminal behavior also in view of the fact that the analysis performed by Cohen and Glashow does not contain any absolute limit, like that present in the case of the Cherenkov effect in vacuum, which is absolutely impossible, as its violation would require an infinite energy amount. CG conclusions are not in contrast with superluminal neutrinos, which, in turn, are fully compatible with the theoretical analysis reported as well.

  11. Popper's Experiment and Superluminal Communication

    CERN Document Server

    Gerjuoy, E; Gerjuoy, Edward; Sessler, Andrew M.

    2005-01-01

    We comment on Tabesh Qureshi, "Understanding Popper's Experiment," AJP 73, 541 (June 2005), in particular on the implications of its section IV. We show, in the situation envisaged by Popper, that analysis solely with conventional non-relativistic quantum mechanics suffices to exclude the possibility of superluminal communication.

  12. Probing Superluminal Neutrinos Via Refraction

    OpenAIRE

    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...

  13. Neutrino oscillations and superluminal propagation

    CERN Document Server

    Magueijo, Joao

    2011-01-01

    We digress on the implications of recent claims of superluminal neutrino propagation. No matter how we turn it around such behaviour is very odd and sits uncomfortably even within "far-fetched" theories. In the context of non-linear realizations of the Lorentz group (where superluminal misbehaviour is run of the mill) one has to accept rather contrived constructions to predict superluminal properties for the neutrino. The simplest explanation is to require that at least one of the mass states be tachyonic. We show that due to neutrino mixing, the flavor energy does not suffer from the usual runaway pathologies of tachyons. For non-tachyonic mass states the theories become more speculative. A neutrino specific dispersion relation is exhibited, rendering the amplitude of the effect reasonable for a standard Planck energy. This uses the fact that the beam energy is close to the geometrical average of the neutrino and Planck mass; or, seen in another way, the beam energy is unexceptional but its gamma factor is v...

  14. The superluminal neutrino hypothesis

    CERN Document Server

    Ehrlich, Robert

    2012-01-01

    This paper summarizes five observations suggesting that one of the neutrinos is consistent with being a tachyon. The five observations include: (1) Experiments measuring the neutrino speed, (2) Mass eigenstates claimed for SN 1987A neutrinos, (3) ${m}^2$ values of flavor eigenstates, (4) The shape of the high energy cosmic ray spectrum, and (5) Neutral hadrons in the cosmic rays from Cygnus X-3.

  15. The Shape of Superluminous Supernovae

    Science.gov (United States)

    Kohler, Susanna

    2016-11-01

    What causes the tremendous explosions of superluminous supernovae? New observations reveal the geometry of one such explosion, SN 2015bn, providing clues as to its source.A New Class of ExplosionsImage of a type Ia supernova in the galaxy NGC 4526. [NASA/ESA]Supernovae are powerful explosions that can briefly outshine the galaxies that host them. There are several different classifications of supernovae, each with a different physical source such as thermonuclear instability in a white dwarf, caused by accretion of too much mass, or the exhaustion of fuel in the core of a massive star, leading to the cores collapse and expulsion of its outer layers.In recent years, however, weve detected another type of supernovae, referred to as superluminous supernovae. These particularly energetic explosions last longer months instead of weeks and are brighter at their peaks than normal supernovae by factors of tens to hundreds.The physical cause of these unusual explosions is still a topic of debate. Recently, however, a team of scientists led by Cosimo Inserra (Queens University Belfast) has obtained new observations of a superluminous supernova that might help address this question.The flux and the polarization level (black lines) along the dominant axis of SN 2015bn, 24 days before peak flux (left) and 28 days after peak flux (right). Blue lines show the authors best-fitting model. [Inserra et al. 2016]Probing GeometryInserra and collaborators obtained two sets of observations of SN 2015bn one roughly a month before and one a month after the superluminous supernovas peak brightness using a spectrograph on the Very Large Telescope in Chile. These observations mark the first spectropolarimetric data for a superluminous supernova.Spectropolarimetry is the practice of obtaining information about the polarization of radiation from an objects spectrum. Polarization carries information about broken spatial symmetries in the object: only if the object is perfectly symmetric can it

  16. Superluminality in the Bi- and Multi Galileon

    CERN Document Server

    de Fromont, Paul; Heisenberg, Lavinia; Matas, Andrew

    2013-01-01

    We re-explore the Bi- and Multi-Galileon models with trivial asymptotic conditions at infinity and show that propagation of superluminal fluctuations is a common and unavoidable feature of these theories, unlike previously claimed in the literature. We show that all Multi-Galileon theories containing a Cubic Galileon term exhibit superluminalities at large distances from a point source, and that even if the Cubic Galileon is not present one can always find sensible matter distributions in which there are superluminal modes at large distances. In the Bi-Galileon case we explicitly show that there are always superluminal modes around a point source even if the Cubic Galileon is not present. Finally, we briefly comment on the possibility of avoiding superluminalities by modifying the asymptotic conditions at infinity.

  17. Space-time measures for subluminal and superluminal motions

    CERN Document Server

    Calvo-Mozo, Benjam\\'\\in

    2014-01-01

    In present work we examine the implications on both, space-time measures and causal structure, of a generalization of the local causality postulate by asserting its validity to all motion regimes, the subluminal and superluminal ones. The new principle implies the existence of a denumerable set of metrical null cone speeds, \\{$c_k\\}$, where $c_1$ is the speed of light in vacuum, and $c_k/c \\simeq \\epsilon^{-k+1}$ for $k\\geq2$, where $\\epsilon^2$ is a tiny dimensionless constant which we introduce to prevent the divergence of the $x, t$ measures in Lorentz transformations, such that their generalization keeps $c_k$ invariant and as the top speed for every regime of motion. The non divergent factor $\\gamma_k$ equals $k\\epsilon^{-1}$ at speed $c_k$. We speak then of $k-$timelike and $k-$null intervals and of k-timelike and k-null paths on space-time, and construct a causal structure for each regime. We discuss also the possible transition of a material particle from the subluminal to the first superluminal regim...

  18. 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.

  19. Real-time weak signal detecting using FPGA-based Duffing oscillator with auto-damping and high speed ADC

    Science.gov (United States)

    Shen, Zhongtao; Feng, Changqing

    2017-05-01

    In this paper, a hardware real-time weak signal detection method using Field-Programmable Gate Array (FPGA) Duffing Oscillator (DUOS) and high speed Analog-to-Digital Converter (ADC) is presented. In the design, the Xilinx Kintex-7 FPGA is chosen as the controller and the DUOS weak signal detecting algorithm is implemented in it with single floating precision. The ADS5409, a dual-channel, 12-bit, 900 MSPS ADC of TI, is used for data acquisition. Besides, to guarantee the same detection Signal-Noise Ratio (SNR) for signals of different amplitudes, a signal auto-damping strategy is adopted in the FPGA, which can adjust the amplitudes of the input signals automatically. The method introduced in this paper achieves not only the ability of efficient weak signal detection in noisy environment but also the advantages of hardware processing such as real-time, low power and so on.

  20. Adaptive Voltage Control Strategy for Variable-Speed Wind Turbine Connected to a Weak Network

    DEFF Research Database (Denmark)

    Abulanwar, Elsayed; Hu, Weihao; Chen, Zhe

    2016-01-01

    Significant voltage fluctuations and power quality issues pose considerable constraints on the efficient integration of remotely located wind turbines into weak networks. Besides, 3p oscillations arising from the wind shear and tower shadow effects induce further voltage perturbations during...... continuous operation. This study investigates and analyses the repercussions raised by integrating a doubly-fed induction generator wind turbine into an ac network of different parameters and very weak conditions. An adaptive voltage control (AVC) strategy is proposed to retain voltage constancy...

  1. 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.

  2. On the impossibility of superluminal travel: the warp drive lesson

    CERN Document Server

    Barceló, Carlos; Liberati, Stefano

    2010-01-01

    The question of whether it is possible or not to surpass the speed of light is already centennial. The special theory of relativity took the existence of a speed limit as a principle, the light postulate, which has proven to be enormously predictive. Here we discuss some of its twists and turns when general relativity and quantum mechanics come into play. In particular, we discuss one of the most interesting proposals for faster than light travel: warp drives. Even if one succeeded in creating such spacetime structures, it would be still necessary to check whether they would survive to the switching on of quantum matter effects. Here, we show that the quantum back-reaction to warp-drive geometries, created out of an initially flat spacetime, inevitably lead to their destabilization whenever superluminal speeds are attained. We close this investigation speculating the possible significance of this further success of the speed of light postulate.

  3. Extended Linear and Nonlinear Lorentz Transformations and Superluminality

    Directory of Open Access Journals (Sweden)

    Dara Faroughy

    2013-01-01

    Full Text Available Two broad scenarios for extended linear Lorentz transformations (ELTs are modeled in Section 2 for mixing subluminal and superluminal sectors resulting in standard or deformed energy-momentum dispersions. The first scenario is elucidated in the context of four diverse realizations of a continuous function f ( v , with 0 ≤ f ( v ≤ 1 and f ( 0 = f ( c = 1 , which is fitted in the ELT. What goes in the making of the ELT in this scenario is not the boost speed v , as ascertained by two inertial observers in uniform relative motion (URM, but v × f ( v . The second scenario infers the preexistence of two rest-mass-dependent superluminal speeds whereby the ELTs are finite at the light speed c . Particle energies are evaluated in this scenario at c for several particles, including the neutrinos, and are auspiciously found to be below the GKZ energy cutoff and in compliance with a host of worldwide ultrahigh energy cosmic ray data. Section 3 presents two broad scenarios involving a number of novel nonlinear LTs (NLTs featuring small Lorentz invariance violations (LIVs, as well as resurrecting the notion of simultaneity for limited spacetime events as perceived by two observers in URM. These inquiries corroborate that NLTs could be potent tools for investigating LIVs past the customary LTs.

  4. Wave Scattering by Superluminal Spacetime Slab

    CERN Document Server

    Deck-Léger, Zoé-Lise

    2016-01-01

    Spacetime media offers new opportunities for wave manipulation. Here we study superluminal slabs, and show that the amplitudes of the reflected waves are controlled by the velocity of the medium. In addition, the backward wave continuously scans from the specular to the collinear angle. A diagrammatic method is provided for insight into the deflection angles. A fundamental symmetry between sub- and superluminal scattering is derived from this diagrammatic description.

  5. Is OPERA Neutrino Superluminal Propagation similar to Gain-Assisted Superluminal Light Propagation

    CERN Document Server

    Pankovic, Vladan

    2011-01-01

    In this work we consider a possible conceptual similarity between recent, amazing OPERA experiment of the superluminal propagation of neutrino and experiment of the gain-assisted superluminal light propagation realized about ten years ago. Last experiment refers on the propagation of the light, precisely laser pulse through a medium, precisely caesium atomic gas, with characteristic anomalous dispersion and corresponding negative group-velocity index that implies superluminal propagation of the light through this medium. Nevertheless all this, at it has been pointed out by authors, "is not at odds with causality or special relativity", since it simply represents "a direct consequence of the classical interference between ... different frequency components". We observe that OPERA experiment is in many aspects conceptually very similar to the gain-assisted superluminal light propagation, including superposition of the neutrinos component and superluminality magnitudes. For this reason we suppose that OPERA expe...

  6. Superluminal Motion Found In Milky Way

    Science.gov (United States)

    1994-08-01

    Researchers using the Very Large Array (VLA) have discovered that a small, powerful object in our own cosmic neighborhood is shooting out material at nearly the speed of light -- a feat previously known to be performed only by the massive cores of entire galaxies. In fact, because of the direction in which the material is moving, it appears to be traveling faster than the speed of light -- a phenomenon called "superluminal motion." This is the first superluminal motion ever detected within our Galaxy. During March and April of this year, Dr. Felix Mirabel of the Astrophysics Section of the Center for Studies at Saclay, France, and Dr. Luis Rodriguez of the Institute of Astronomy at the National Autonomous University in Mexico City and NRAO, observed "a remarkable ejection event" in which the object shot out material in opposite directions at 92 percent of the speed of light, or more than 171,000 miles per second. This event ejected a mass equal to one-third that of the moon with the power of 100 million suns. Such powerful ejections are well known in distant galaxies and quasars, millions and billions of light-years away, but the object Mirabel and Rodriguez observed is within our own Milky Way Galaxy, only 40,000 light-years away. The object also is much smaller and less massive than the core of a galaxy, so the scientists were quite surprised to find it capable of accelerating material to such speeds. Mirabel and Rodriguez believe that the object is likely a double-star system, with one of the stars either an extremely dense neutron star or a black hole. The neutron star or black hole is the central object of the system, with great mass and strong gravitational pull. It is surrounded by a disk of material orbiting closely and being drawn into it. Such a disk is known as an accretion disk. The central object's powerful gravity, they believe, is pulling material from a more-normal companion star into the accretion disk. The central object is emitting jets of

  7. The Phantom of the OPERA: Superluminal Neutrinos

    CERN Document Server

    Ma, Bo-Qiang

    2011-01-01

    This report presents a brief review on the experimental measurements of the muon neutrino velocities from the OPERA, Fermilab and MINOS experiments and that of the (anti)-electron neutrino velocities from the supernova SN1987a, and consequently on the theoretical aspects to attribute the data as signals for superluminality of neutrinos. Different scenarios on how to understand and treat the background fields in the standard model extension frameworks are pointed out. Challenges on interpreting the OPERA result as a signal of neutrino superluminality are briefly reviewed and discussed. It is also pointed out that a covariant scenario of Lorentz violation can avoid the refutation on the OPERA experiment.

  8. 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...

  9. On the Lorentz Factor of Superluminal Sources

    CERN Document Server

    Onuchukwu, Chika Christian

    2013-01-01

    We investigate the properties of features seen within superluminal sources often referred to as components. Our result indicates a fairly strong correlation of r=0.6 for quasars, r=0.4 for galaxies, and r=0.8 for BL Lac objects in our sample between component sizes and distances from the stationary core. Assumption of free adiabatic expanding plasma enabled us to constrain in general the Lorentz factor for superluminal sources. Ourestimated Lorentz factor of 7 - 17 for quasars, 6 - 13 for galaxies and 4- 9 for BL Lac objects indicate that BL Lac have the lowest range of Lorentz factor.

  10. Aspects of Quantum Non-Locality I: Superluminal Signalling, Action-at-a-Distance, Non-Separability and Holism

    Science.gov (United States)

    Berkovitz, Joseph

    In this paper and its sequel, I consider the significance of Jarrett's and Shimony's analyses of the so-called factorisability (Bell-locality) condition for clarifying the nature of quantum non-locality. In this paper, I focus on four types of non-locality: superluminal signalling, action-at-a-distance, non-separability and holism. In the second paper, I consider a fifth type of non-locality: superluminal causation according to 'logically weak' concepts of causation, where causal dependence requires neither action nor signalling. In this connection, I pay special attention to the difficulties that superluminal causation raises in relativistic space-time. I conclude by evaluating the relevance of Jarrett's and Shimony's analyses for clarifying the question of the compatibility of quantum non-locality with relativity theory. My main conclusions are, first: these analyses are significant for clarifying the questions of superluminal signalling in quantum phenomena and for the compatibility of these phenomena with relativity. But, second, by contrast: these analyses are not very significant for the study of action-at-a distance, superluminal causation, non-separability and holism in quantum phenomena.

  11. 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.

  12. Superluminality, Black Holes and Effective Field Theory

    CERN Document Server

    Goon, Garrett

    2016-01-01

    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-per...

  13. "OPERA superluminal neutrinos explained by spontaneous emission and stimulated absorption"

    CERN Document Server

    Torrealba, Rafael

    2011-01-01

    In this work it is shown, that for short 3ns neutrino pulses reported by OPERA, a relativistic shape deforming effect of the neutrino distribution function due to spontaneous emission, produces an earlier arrival of 65.8ns in agreement with the reported 62.1ns\\pm 3.7ns, with a RMS of 16.4ns explaining the apparent superluminal effect. It is also shown, that early arrival of long 10500ns neutrinos pulse to Gran Sasso, by 57.8ns with respect to the speed of light, could be explained by a shape deforming effect due to a combination of stimulated absorption and spontaneous emission, while traveling by the decay tunnel that acts as a LASER tube.

  14. Symmetry, causal structure and superluminality in Finsler spacetime

    CERN Document Server

    Chang, Zhe; Wang, Sai

    2012-01-01

    The superluminal behaviors of neutrinos were reported by the OPERA collaboration recently. It was also noticed by Cohen and Glashow that, in standard quantum field theory, the superluminal neutrinos would lose their energy via the Cherenkov-like process rapidly. Finslerian special relativity may provide a framework to cooperate with the OPERA neutrino superluminality without Cherenkov-like process. We present clearly the symmetry, causal structure and superluminality in Finsler spacetime. The principle of relativity and the causal law are preserved. The energy and momentum are well defined and conserved in Finslerian special relativity. The Cherenkov-like process is proved to be forbidden kinematically and the superluminal neutrinos would not lose energy in their distant propagations from CERN to the Gran Sasso Laboratory. The energy dependence of neutrino superluminality is studied based on the reported data of the OPERA collaboration as well as other groups.

  15. 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.

  16. On the Lorentz factor of superluminal sources

    Institute of Scientific and Technical Information of China (English)

    Chika Christian Onuchukwu; Augustine A.Ubachukwu

    2013-01-01

    We investigate the properties of features seen within superluminal sources often referred to as components.Our result indicates a fairly strong correlation of r ~ 0.5 for quasars,r ~ 0.4 for galaxies and r ~ 0.7 for BL Lac objects in our sample between component sizes and distances from the stationary core.The assumption of free adiabatic expanding plasma enables us to constrain the Lorentz factor for superluminal sources.Our estimated Lorentz factor of γ ~ 9-13 for quasars,γ ~ 7-11for galaxies and γ ~ 4-9 for BL Lac objects indicates that BL Lacs have the lowest range of Lorentz factors.

  17. 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.

  18. On the propagation speed of evanescent modes

    Energy Technology Data Exchange (ETDEWEB)

    Barbero, A.P.L. [State Univ. of Campinas, Campinas (Brazil)]|[Universidad Federal Fluminense (Brazil); Hernandez Figueroa, H.E. [State Univ. of Campinas, Campinas (Brazil); Recami, E. [Istituto Nazionale di Fisica Nucleare, Milan (Italy)]|[Bergamo Univ., Bergamo (Italy). Fac. di Ingegneria]|[State Univ. of Campinas, Campinas (Brazil)

    2000-03-01

    The group velocity of evanescent waves (in undersized waveguides, for instance) was theoretically predicted, and has been experimentally verified, to be superluminal. By contrast, it is known that the precursor speed in vacuum cannot be larger than c. This paper, by computer simulations based on Maxwell equations only, shows the existence of both phenomena and verifies the actual possibility of superluminal group velocities, without violating the so-called (naive) Einstein causality.

  19. Resolving 7 problems with OPERA's superluminal neutrino experiment

    CERN Document Server

    Ehrlich, Robert

    2011-01-01

    Physicists have raised many troubling inconsistencies with the OPERA claim of superluminal neutrinos that cast doubt on its validity. This paper examines ways that 7 of these inconsistencies can be resolved. It also discusses evidence that the electron neutrino is superluminal, based on previously published cosmic ray observations, and secondarily a re-examination of tritium beta decay data.

  20. On the Superluminal Motion of Radio-Loud AGNs

    Indian Academy of Sciences (India)

    Zhi-Bin Zhang; Yi-Zhen Zhang

    2011-03-01

    Apparent superluminal motion of different radio-loud AGNs are similarly related with beaming effect. The cosmological expanding effect would play no part in the superluminal motion of radio galaxies, BL Lacertae objects as well as quasars.Meanwhile, we confirm that estimates for apparent velocity app and Doppler boosting factor based on multi-wavelength combination and variability are comparable.

  1. Superluminality in the Bi- and Multi-Galileon

    Science.gov (United States)

    de Fromont, Paul; de Rham, Claudia; Heisenberg, Lavinia; Matas, Andrew

    2013-07-01

    We re-explore the Bi- and Multi-Galileon models with trivial asymptotic conditions at infinity and show that propagation of superluminal fluctuations is a common and unavoidable feature of these theories, unlike previously claimed in the literature. We show that all Multi-Galileon theories containing a Cubic Galileon term exhibit superluminalities at large distances from a point source, and that even if the Cubic Galileon is not present one can always find sensible matter distributions in which there are superluminal modes at large distances. In the Bi-Galileon case we explicitly show that there are always superluminal modes around a point source even if the Cubic Galileon is not present. Finally, we briefly comment on the possibility of avoiding superluminalities by modifying the asymptotic conditions at infinity.

  2. Has superluminal light propagation been observed?

    OpenAIRE

    Zhang, Yuan-Zhong

    2000-01-01

    It says in the report$^1$ by Wang et al. that a negative group velocity $u=-c/310$ is obtained and that a pulse advancement shift 62-ns is measured. The authors claim that the negative group velocity is associated with superluminal light propagation and that the pulse advancement is not at odds with causality or special relativity. However, it is shown here that their conclusions above are not true. Furthermore, I give some suggestion concerning a re-definition of group-velocity and a new exp...

  3. Green's function of a massless scalar field in curved space-time and superluminal phase velocity of the retarded potential

    CERN Document Server

    Dai, De-Chang

    2012-01-01

    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 non-moving 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 relatively common phenomenon, with the 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.

  4. 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.

  5. SGC Switching Between Subluminal to Superluminal Propagation in V-Type Atom

    Institute of Scientific and Technical Information of China (English)

    HAN Ding-An; GUO Hong; BAI Yan-Feng; SUN Hui; ZENG Ya-Guang

    2006-01-01

    For a V-type three-level atomic system with two closely spaced upper levels, we investigate the light pulse propagation properties with only one laser field. Due to spontaneously generated coherence, the group velocity of the light pulse can be changed from subluminal to superluminal. The effects of the field intensity and the two-upper level splitting on the group velocity are also shown. At last, an analytical expression for the group velocity is given in the case of a weak field.

  6. 超光速佯谬和中微子%Superluminal Paradox and Neutrino

    Institute of Scientific and Technical Information of China (English)

    倪光炯

    2002-01-01

    爱因斯坦的狭义相对论和因果原理意味着任何运动物体的速度不能超过光在真空中的速度.然而,有许多讨论超光速运动粒子的尝试,这些讨论或者是在狭义相对论的框架下进行的,或者是超越了狭义相对论.这些讨论都遇到一系列难以克服的困难,即"超光速佯谬".文中详细分析了这种佯谬,并证明它在与狭义相对论兼容的量子理论中显然是不出现的.在实在世界中,中微子最可能是一种超光速粒子.%Einstein′s theory of special relativity (SR) and the principle of causality imply that the speed of any moving object can not exceed that of light in a vacuum (c). However, there were many attempts in literature discussing the particle moving with speed u>c(called as superluminal particle or tachyon) either in the scheme of SR or beyond it. These theories all encountered a series of insurmountable difficulties which will be named "superluminal paradox"in this paper. We will analyze it in some detail and then prove that the paradox disappears unambiguously in quantum theory, which is compatible with SR. Most likely, the superluminal particle in real world is just a kind of known particle, the neutrino.

  7. On Superluminal Particles and the Extended Relativity Theories

    Science.gov (United States)

    Castro, Carlos

    2012-09-01

    Superluminal particles are studied within the framework of the Extended Relativity theory in Clifford spaces ( C-spaces). In the simplest scenario, it is found that it is the contribution of the Clifford scalar component π of the poly-vector-valued momentum which is responsible for the superluminal behavior in ordinary spacetime due to the fact that the effective mass {M} = sqrt{ M2 - π2 } is imaginary (tachyonic). However, from the point of view of C-space, there is no superluminal (tachyonic) behavior because the true physical mass still obeys M 2>0. Therefore, there are no violations of the Clifford-extended Lorentz invariance and the extended Relativity principle in C-spaces. It is also explained why the charged muons (leptons) are subluminal while its chargeless neutrinos may admit superluminal propagation. A Born's Reciprocal Relativity theory in Phase Spaces leads to modified dispersion relations involving both coordinates and momenta, and whose truncations furnish Lorentz-violating dispersion relations which appear in Finsler Geometry, rainbow-metrics models and Double (deformed) Special Relativity. These models also admit superluminal particles. A numerical analysis based on the recent OPERA experimental findings on alleged superluminal muon neutrinos is made. For the average muon neutrino energy of 17 GeV, we find a value for the magnitude |{M } | = 119.7 MeV that, coincidentally, is close to the mass of the muon m μ =105.7 MeV.

  8. Study of the volumetric properties of weakly associated alcohols by means of high-pressure speed of sound measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Salgado, D. [Departamento de Fisica Aplicada, Universidad de Vigo, Facultad de Ciencias del Campus de Ourense, 32004 Ourense (Spain); Troncoso, J. [Departamento de Fisica Aplicada, Universidad de Vigo, Facultad de Ciencias del Campus de Ourense, 32004 Ourense (Spain); Plantier, F. [Laboratoire des Fluides Complexes, Groupe Haute Pression, Universite de Pau et des Pays de l' Adour, BP 1155, 64013 Pau (France)]. E-mail: frederic.plantier@univ-pau.fr; Daridon, J.L. [Laboratoire des Fluides Complexes, Groupe Haute Pression, Universite de Pau et des Pays de l' Adour, BP 1155, 64013 Pau (France); Bessieres, D. [Laboratoire des Fluides Complexes, Groupe Haute Pression, Universite de Pau et des Pays de l' Adour, BP 1155, 64013 Pau (France)

    2006-07-15

    The speed of sound in the temperature (303.15 to 373.15) K and pressure range (0.1 to 100) MPa was measured for the liquid 3-pentanol, 3-methyl 3-pentanol, and 3-ethyl-3-pentanol. These results combined with the densities and isobaric heat capacity at atmospheric pressure obtained from the literature were used to calculate the density, and the isentropic and isothermal compressibilities in the same range of pressure and in the temperature interval (303.15 to 368.15) K by means of a predictor-corrector algorithm.

  9. Weakly Bound Free Radicals in Combustion: "Prompt" Dissociation of Formyl Radicals and Its Effect on Laminar Flame Speeds

    Energy Technology Data Exchange (ETDEWEB)

    Labbe, Nicole J.; Sivaramakrishnan, Raghu; Goldsmith, C. Franklin; Georgievskii, Yuri; Miller, James A.; Klippenstein, Stephen J.

    2016-01-07

    Weakly bound free radicals have low-dissociation thresholds such that at high temperatures, timescales for dissociation and collisional relaxation become comparable, leading to significant dissociation during the vibrational-rotational relaxation process. Here we characterize this “prompt” dissociation of formyl (HCO), an important combustion radical, using direct dynamics calculations for OH + CH2O and H + CH2O (key HCO-forming reactions). For all other HCO-forming reactions, presumption of a thermal incipient HCO distribution was used to derive prompt dissociation fractions. Inclusion of these theoretically derived HCO prompt dissociation fractions into combustion kinetics models provides an additional source for H-atoms that feeds chain branching reactions. Simulations using these updated combustion models are therefore shown to enhance flame propagation in 1,3,5-trioxane and acetylene. The present results suggest that HCO prompt dissociation should be included when simulating flames of hydrocarbons and oxygenated molecules and that prompt dissociations of other weakly bound radicals may also impact combustion simulations

  10. Weakly Bound Free Radicals in Combustion: "Prompt" Dissociation of Formyl Radicals and Its Effect on Laminar Flame Speeds.

    Science.gov (United States)

    Labbe, Nicole J; Sivaramakrishnan, Raghu; Goldsmith, C Franklin; Georgievskii, Yuri; Miller, James A; Klippenstein, Stephen J

    2016-01-01

    Weakly bound free radicals have low-dissociation thresholds such that at high temperatures, time scales for dissociation and collisional relaxation become comparable, leading to significant dissociation during the vibrational-rotational relaxation process. Here we characterize this "prompt" dissociation of formyl (HCO), an important combustion radical, using direct dynamics calculations for OH + CH2O and H + CH2O (key HCO-forming reactions). For all other HCO-forming reactions, presumption of a thermal incipient HCO distribution was used to derive prompt dissociation fractions. Inclusion of these theoretically derived HCO prompt dissociation fractions into combustion kinetics models provides an additional source for H-atoms that feeds chain-branching reactions. Simulations using these updated combustion models are therefore shown to enhance flame propagation in 1,3,5-trioxane and acetylene. The present results suggest that HCO prompt dissociation should be included when simulating flames of hydrocarbons and oxygenated molecules and that prompt dissociations of other weakly bound radicals may also impact combustion simulations.

  11. 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.

  12. Universe of superluminal velocities: tests of astrophysics, from dogma-to reality

    Science.gov (United States)

    Chechelnitsky, A.

    The Barrier of speed of light is the most chained and, perhaps, the most unreasonable Interdiction of the standard (astro) physics and cosmology. Its theoretical bases are speculative and unconvincing, and it actually has not been proved by observations from the very beginning of its promulgations. Moreover, it is gradually increase a stream of the observational data frankly contradicting to the Barrier. This monumental Dogma substantially holds down the initiative of researchers and development of sciences about the Universe. Resolving proofs of absence of the Barrier and real existence of superluminal velocities can come, most likely, from the side of observational astrophysics, when appear fair predictions, based on the alternative theory. Predictions and observational Tests, in particular, are those. The advanced astrophysical researches will lead to accumulation of the precision data and construction of histograms of the velocities observable in the Universe (in the centers of galaxies, AGN, blazàrs, BL Lac, etc), which will show: i) Distribution of the transversal (in a picture plane) superluminal velocities has distinct peaks near to the values specified by the alternative theory: (in G[ -6] Shell) β =v/c: 1.77; 1.48; 1.25; 1.05; 0.88; 0.74; 0.62; 0.52; 0.44; (G[ -7] Shell) β =v/c:: 6.48 ; 5.45; 4.58; 3.85; 3.24; 2.72; 2.29; 1.92; 1.62; (G[ -8] Shell) β =v/c: 23.79; 20.00; 16.82; 14.14; 11.89; 10.00; 8.41; 7.07; 5.95 ii) The same peaks are available (already now, - and it can be shown on the basis of the spectroscopic data) in distribution (histograms) of beam (radial) superluminal velocities (with the same multiplicator M = 2 = 1.1892). iii) The predicted property of discreteness, quantization of superluminal velocities (as well as subluminal) velocities is the exclusive pattern, essentially distinguishing alternative representations (Wave Universe Concept [Chechelnitsky 1980-2004]; see, in particular, the bibliography in Advances in Space Research, v

  13. 超光速:可能与不可能%On the Superluminal Movement:Possible and Impossible?

    Institute of Scientific and Technical Information of China (English)

    黄政新

    2012-01-01

    The OPERA experimental results indicate that neutrinos move even faster than the speed of light,which triggers extensive skepticism with regards of Einstein's assertion that superluminal movement does not exists in nature.This paper first makes a brief review to the history of tachyon(faster-than-light particle) research home and abroad in the past half-century.It then points out that:(1) there is no solid and sufficient reason in Einstein's assertion that superluminal movement does not exists in nature;(2) so far there is no solid experimental foundation for those currently established superluminal theories;(3) a correct superluminal theory should return to special relativity under extreme conditions(i.e.when the velocity approaches the speed of light).%"奥佩拉"(OPERA)实验结果显示中微子运动得比光速还快。这引起许多人对爱因斯坦关于自然界不存在超光速运动这一断言的怀疑。本文回顾了半个世纪以来国内外快子(超光速粒子)研究的简要历史。接着,本文指出:(1)爱因斯坦断言自然界不存在超光速运动是没有充分理由的;(2)所有已建立的超光速理论都没有坚实的实验基础;(3)一个正确的超光理论在极限条件下(当速度趋于光速时)时应当回归狭义相对论。

  14. 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

  15. Superluminal Motion and Polarization in Blazars

    Institute of Scientific and Technical Information of China (English)

    Jun-Hui Fan; Yong-Jiu Wang; Jiang-He Yang; Cheng-Yue Su

    2004-01-01

    A relativistic beaming model has been successfully used to explain the observed properties of active galactic nuclei (AGNs). In this model there are two emission components, a boosted one and an unbeamed one, shown up in the radio band as the core and lobe components. The luminosity ratio of the core to the lobe is defined as the core-dominance parameter (R = LCore/LLobe) The de-beamed radio luminosity (Ldbjet) in the jet is assumed to be proportional to the unbeamed luminosity (Lub) in the co-moving frame, i.e., f = Ldbjet/Lub and f is determined in our previous paper. We further discuss the relationship between BL Lacertae objects(BLs) and flat spectrum radio quasars (FSRQs), which are subclasses of blazars with different degrees of polarization, using the calculated values of the ratio f for a sample of superluminal blazars. We found 1) that the BLs show smaller averaged Doppler factors and Lorentz factors, larger viewing angles and higher coredominance parameters than do the FSRQs, and 2) that in the polarization-core dominance parameter plot (P - log R) the BLs and FSRQs occupy a scattered region, but in a revised plot (logP/c(m) - logR), they gather around two different lines, suggesting that they have some different intrinsic properties.

  16. Spectrum formation in Superluminous Supernovae (Type I)

    CERN Document Server

    Mazzali, P A; Pian, E; Greiner, J; Kann, D A; ARI-LJMU,; UK,; Garching, MPA; Germany,; Southampton, Univ; INAF-IASFBO,; Italy,; Pisa, SNS; Garching, MPE; Tautenburg,; Germany),

    2016-01-01

    The near-maximum spectra of most superluminous supernovae that are not dominated by interaction with a H-rich CSM (SLSN-I) are characterised by a blue spectral peak and a series of absorption lines which have been identified as OII. SN2011kl, associated with the ultra-long gamma-ray burst GRB111209A, also had a blue peak but a featureless optical/UV spectrum. Radiation transport methods are used to show that the spectra (not including SN2007bi, which has a redder spectrum at peak, like ordinary SNe Ic) can be explained by a rather steep density distribution of the ejecta, whose composition appears to be typical of carbon-oxygen cores of massive stars which can have low metal content. If the photospheric velocity is ~10000-15000 km/s, several lines form in the UV. OII lines, however, arise from very highly excited lower levels, which require significant departures from Local Thermodynamic Equilibrium to be populated. These SLSNe are not thought to be powered primarily by 56Ni decay. An appealing scenario is th...

  17. Super-luminous supernovae from PESSTO

    CERN Document Server

    Nicholl, M; Jerkstrand, A; Inserra, C; Chen, T -W; Kotak, R; Valenti, S; Howell, D A; McCrum, M; Margheim, S; Rest, A; Benetti, S; Fraser, M; Gal-Yam, A; Smith, K W; Sullivan, M; Young, D R; Baltay, C; Hadjiyska, E; McKinnon, R; Rabinowitz, D; Walker, E S; Feindt, U; Nugent, P; Lawrence, A; Mead, A; Anderson, J P; Sollerman, J; Taddia, F; Leloudas, G; Mattila, S; Elias-Rosa, N

    2014-01-01

    We present optical spectra and light curves for three hydrogen-poor super-luminous supernovae followed by the Public ESO Spectroscopic Survey of Transient Objects (PESSTO). Time series spectroscopy from a few days after maximum light to 100 days later shows them to be fairly typical of this class, with spectra dominated by Ca II, Mg II, Fe II and Si II, which evolve slowly over most of the post-peak photospheric phase. We determine bolometric light curves and apply simple fitting tools, based on the diffusion of energy input by magnetar spin-down, \\Ni decay, and collision of the ejecta with an opaque circumstellar shell. We investigate how the heterogeneous light curves of our sample (combined with others from the literature) can help to constrain the possible mechanisms behind these events. We have followed these events to beyond 100-200 days after peak, to disentangle host galaxy light from fading supernova flux and to differentiate between the models, which predict diverse behaviour at this phase. Models p...

  18. Superluminous Supernovae: No Threat from Eta Carinae

    Science.gov (United States)

    Thomas, Brian; Melott, A. L.; Fields, B. D.; Anthony-Twarog, B. J.

    2008-05-01

    Recently Supernova 2006gy was noted as the most luminous ever recorded, with a total radiated energy of 1044 Joules. It was proposed that the progenitor may have been a massive evolved star similar to η Carinae, which resides in our own galaxy at a distance of about 2.3 kpc. η Carinae appears ready to detonate. Although it is too distant to pose a serious threat as a normal supernova, and given its rotation axis is unlikely to produce a Gamma-Ray Burst oriented toward the Earth, η Carinae is about 30,000 times nearer than 2006gy, and we re-evaluate it as a potential superluminous supernova. We find that given the large ratio of emission in the optical to the X-ray, atmospheric effects are negligible. Ionization of the atmosphere and concomitant ozone depletion are unlikely to be important. Any cosmic ray effects should be spread out over 104 y, and similarly unlikely to produce any serious perturbation to the biosphere. We also discuss a new possible effect of supernovae, endocrine disruption induced by blue light near the peak of the optical spectrum. This is a possibility for nearby supernovae at distances too large to be considered "dangerous” for other reasons. However, due to reddening and extinction by the interstellar medium, η Carinae is unlikely to trigger such effects to any significant degree.

  19. Superluminous supernovae: No threat from Eta Carinae

    CERN Document Server

    Thomas, Brian C; Fields, Brian D; Anthony-Twarog, Barbara J

    2007-01-01

    Recently Supernova 2006gy was noted as the most luminous ever recorded, with a total radiated energy of ~10^44 Joules. It was proposed that the progenitor may have been a massive evolved star similar to Eta Carinae, which resides in our own galaxy at a (poorly determined) distance of ~2.5 kpc. Eta Carinae appears ready to detonate, and in fact had an outburst in 1843. Although it is too distant to pose a serious threat as a normal supernova, and given its rotation axis is unlikely to produce a Gamma Ray Burst oriented toward the Earth, Eta Carinae is about 30,000 times nearer than 2006gy, and we re-evaluate it as a potential superluminous supernova. We find that given the large ratio of emission in the optical to the X-ray, atmospheric effects are negligible. Ionization of the atmosphere and concomitant ozone depletion are unlikely to be important. Any cosmic ray effects should be spread out over ~10^4 y, and similarly unlikely to produce any serious perturbation to the biosphere. We also discuss a new possib...

  20. First stars, hypernovae, and superluminous supernovae

    Science.gov (United States)

    Nomoto, Ken'Ichi

    2016-07-01

    After the big bang, production of heavy elements in the early universe takes place starting from the formation of the first (Pop III) stars, their evolution, and explosion. The Pop III supernova (SN) explosions have strong dynamical, thermal, and chemical feedback on the formation of subsequent stars and evolution of galaxies. However, the nature of Pop III stars/supernovae (SNe) have not been well-understood. The signature of nucleosynthesis yields of the first SN can be seen in the elemental abundance patterns observed in extremely metal-poor (EMP) stars. We show that the abundance patterns of EMP stars, e.g. the excess of C, Co, Zn relative to Fe, are in better agreement with the yields of hyper-energetic explosions (Hypernovae, (HNe)) rather than normal supernovae. We note the large variation of the abundance patterns of EMP stars propose that such a variation is related to the diversity of the GRB-SNe and posssibly superluminous supernovae (SLSNe). For example, the carbon-enhanced metal-poor (CEMP) stars may be related to the faint SNe (or dark HNe), which could be the explosions induced by relativistic jets. Finally, we examine the various mechanisms of SLSNe.

  1. Tachyons, Lamb shifts and superluminal chaos

    Science.gov (United States)

    Tomaschitz, R.

    2000-10-01

    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 keV/c2 and estimate the tachyonic coupling strength to subluminal matter. The impact of the tachyon field on ground state hyperfine transitions in hydrogen and muonium is investigated. Bounds on atomic transition rates effected by tachyon radiation as well as estimates on the spectral energy density of a possible cosmic tachyon background radiation are derived.

  2. Extended Lorentz code of a superluminal particle

    CERN Document Server

    Ter-Kazarian, G

    2012-01-01

    While the OPERA experimental scrutiny is ongoing in the community, in the present article we construct a toy model of {\\it extended Lorentz code} (ELC) of the uniform motion, which will be a well established consistent and unique theoretical framework to explain the apparent violations of the standard Lorentz code (SLC), the possible manifestations of which arise in a similar way in all particle sectors. We argue that in the ELC-framework the propagation of the superluminal particle, which implies the modified dispersion relation, could be consistent with causality. Furthermore, in this framework, we give a justification of forbiddance of Vavilov-Cherenkov (VC)-radiation/or analog processes in vacuum. To be consistent with the SN1987A and OPERA data, we identify the neutrinos from SN1987A and the light as so-called {\\it 1-th type} particles carrying the {\\it individual Lorentz motion code} with the velocity of light $c_{1}\\equiv c$ in vacuum as maximum attainable velocity for all the 1-th type particles. Ther...

  3. 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.

  4. Superluminal motion in a compact steep spectrum radio source 3C 138

    CERN Document Server

    Shen, Z Q; Kameno, S; Chen, Y J

    2001-01-01

    We present the results of 5 GHz VLBI observations of a compact steep spectrum source 3C 138. The data are consistent with the western end being the location of the central activity. The observed offset between different frequencies in the central region of 3C 138 can be accounted for by a frequency dependent shift of the synchrotron self-absorbed core. Our new measurements confirm the existence of a superluminal motion, but its apparent velocity of 3.3c is three times slower than the reported one. This value is consistent with the absence of parsec-scale counter-jet emission in the inner region, but seems still too high to allow the overall counter-jet to be seen in terms of Doppler boosting of an intrinsically identical jet. Either an interaction of jet with central dense medium, or an intrinsically asymmetrical jet must be invoked to reconcile the detected superluminal speed with the observed large scale asymmetry in 3C 138.

  5. Control of superluminal transit through a heterogeneous medium

    CERN Document Server

    Kulkarni, M; Rao, V S C Manga; Gupta, S Dutta

    2004-01-01

    We consider pulse propagation through a two component composite medium (metal inclusions in a dielectric host) with or without cavity mirrors. We show that a very thin slab of such a medium, under conditions of localized plasmon resonance, can lead to significant superluminality with detectable levels of transmitted pulse. A cavity containing the heterogeneous medium is shown to lead to subluminal-to-superluminal transmission depending on the volume fraction of the metal inclusions. The predictions of phase time calculations are verified by explicit calculations of the transmitted pulse shapes. We also demonstrate the independence of the phase time on system width and the volume fraction under specific conditions.

  6. Statistics of Superluminal Motion in Active Galactic Nuclei

    Institute of Scientific and Technical Information of China (English)

    Yong-Wei Zhang; Jun-Hui Fan

    2008-01-01

    We have collected an up-to-date sample of 123 superluminal sources (84 quasars, 27 BL Lac objects and 12 galaxies) and calculated the apparent velocities (βapp) for 224 components in the sources with the A-CDM model. We checked the relationships between their proper motions, redshifts,βapp and 5 GHz flux densities. Our analysis shows that the radio emission is strongly boosted by the Doppler effect. The superluminal motion and the relativistic beaming boosting effect are, to some extent, the same in active galactic nuclei.

  7. There is Neither Classical Bug with a Superluminal Shadow Nor Quantum Absolute Collapse Nor (Subquantum) Superluminal Hidden Variable

    CERN Document Server

    Pankovic, V; Krmar, M; Radovanovic, M; Pankovic, Vladan; Predojevic, Milan; Krmar, Miodrag; Radovanovic, Milan

    2005-01-01

    In this work we analyse critically Griffiths's example of the classical superluminal motion of a bug shadow. Griffiths considers that this example is conceptually very close to quantum nonlocality or superluminality,i.e. quantum breaking of the famous Bell inequality. Or, generally, he suggests implicitly an absolute asymmetric duality (subluminality vs. superluminality) principle in any fundamental physical theory.It, he hopes, can be used for a natural interpretation of the quantum mechanics too. But we explain that such Griffiths's interpretation retires implicitly but significantly from usual, Copenhagen interpretation of the standard quantum mechanical formalism. Within Copenhagen interpretation basic complementarity principle represents, in fact, a dynamical symmetry principle (including its spontaneous breaking, i.e. effective hiding by measurement). Similarly, in other fundamental physical theories instead of Griffiths's absolute asymmetric duality principle there is a dynamical symmetry (including it...

  8. Spectrum formation in superluminous supernovae (Type I)

    Science.gov (United States)

    Mazzali, P. A.; Sullivan, M.; Pian, E.; Greiner, J.; Kann, D. A.

    2016-06-01

    The near-maximum spectra of most superluminous supernovae (SLSNe) that are not dominated by interaction with a H-rich circum-stellar medium (SLSN-I) are characterized by a blue spectral peak and a series of absorption lines which have been identified as O II. SN 2011kl, associated with the ultra-long gamma-ray burst GRB111209A, also had a blue peak but a featureless optical/ultraviolet (UV) spectrum. Radiation transport methods are used to show that the spectra (not including SN 2007bi, which has a redder spectrum at peak, like ordinary SNe Ic) can be explained by a rather steep density distribution of the ejecta, whose composition appears to be typical of carbon-oxygen cores of massive stars which can have low metal content. If the photospheric velocity is ˜10 000-15 000 km s-1, several lines form in the UV. O II lines, however, arise from very highly excited lower levels, which require significant departures from local thermodynamic equilibrium to be populated. These SLSNe are not thought to be powered primarily by 56Ni decay. An appealing scenario is that they are energized by X-rays from the shock driven by a magnetar wind into the SN ejecta. The apparent lack of evolution of line velocity with time that characterizes SLSNe up to about maximum is another argument in favour of the magnetar scenario. The smooth UV continuum of SN 2011kl requires higher ejecta velocities (˜20 000 km s-1): line blanketing leads to an almost featureless spectrum. Helium is observed in some SLSNe after maximum. The high-ionization near-maximum implies that both He and H may be present but not observed at early times. The spectroscopic classification of SLSNe should probably reflect that of SNe Ib/c. Extensive time coverage is required for an accurate classification.

  9. 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.

  10. 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.

  11. Negative and Superluminal Group Velocity Propagation with Narrow Pulse in a Coaxial Photonic Crystal

    Institute of Scientific and Technical Information of China (English)

    OU Xiao-Juan; ZHOU Wei; LI Lin; TENG Li-Hu; FENG Bao-Ying; ZHENG Sheng-Feng; WANG Feng-Wei

    2007-01-01

    We investigate the propagation of electric signal along a spatially periodic impedance mismatched transmission line group. Anomalous dispersion is caused by the periodically mismatched impedance structure and a forbidden band appears near 8 MHz in transmission. The group velocity of the amplitude-modulated signal is augmented up to infinity, even -3.89c (c the speed of light in vacuum) in the forbidden region with the amplitude of the modulated signal increasing. When the carrier sinusoid signal is modulated in amplitude by the modulating sinusoid signal, of which the peak is superimposed with a narrow pulse at fivefold frequency, the superluminal group velocity also occurs. The experiment failed to show whether the propagation velocity of narrow pulse exceeds c or not.

  12. 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.

  13. 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...... in particular the tachyonic and the Coleman-Glashow cases. We show that a tachyonic interpretation is not only hardly reconciled with OPERA data on energy dependence, but that it clashes with neutrino production from pion and with neutrino oscillations. A Coleman-Glashow superluminal neutrino beam would also...... have problems with pion decay kinematics for the OPERA setup; it could be easily reconciled with SN1987a data, but then it would be very problematic to account for neutrino oscillations. Copyright (C) EPLA, 2012...

  14. 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...... in particular the tachyonic and the Coleman-Glashow cases. We show that a tachyonic interpretation is not only hardly reconciled with OPERA data on energy dependence, but that it clashes with neutrino production from pion and with neutrino oscillations. A Coleman-Glashow superluminal neutrino beam would also...... have problems with pion decay kinematics for the OPERA setup; it could be easily reconciled with SN1987a data, but then it would be very problematic to account for neutrino oscillations. Copyright (C) EPLA, 2012...

  15. Multi-Epoch Spectroscopy of Hydrogen-Poor Superluminous Supernovae

    Science.gov (United States)

    Quimby, Robert; De Cia, Annalisa; Gal-Yam, Avishay; Leloudas, Giorgos; Lunnan, Ragnhild; Perley, Daniel A.; Vreeswijk, Paul; Yan, Lin

    2016-06-01

    A growing sample of intrinsically rare supernovae is being uncovered by wide-field synoptic surveys, such as the Palomar Transient Factory (PTF). A fraction of these events have been labeled "superluminous supernovae" due to their peak luminosities, which can exceed normal supernovae by factors of 10 to 100. The power sources for these events and thus their connection to normal luminosity supernovae remains uncertain. Here we present results from 134 spectroscopic observations of 17 hydrogen-poor superluminous supernovae (SLSN-I) discovered by PTF. We select our targets from the full PTF sample using only spectroscopic information; we do not employ the traditional cut in absolute magnitude (e.g. M physical insights into the nature of these explosions offered by this unique dataset.

  16. Subluminal and Superluminal Phenomena in a Four-Level Atom

    Institute of Scientific and Technical Information of China (English)

    HAN Ding-An; ZENG Ya-Guang; CAO Hui

    2008-01-01

    In a four-level atomic system,we investigate the light pulse propagation properties interacting with only one laser field.It is shown that in the steady state,the group velocity of the light pulse can be changed from subluminal to superluminal by varying the field detuning.Meanwhile,the effects of the field intensity on the group velocity are also shown.At last,with special parameters,the analytical solution for the group index is also obtained.

  17. 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.

  18. An Infinitesimally Superluminal Neutrino is Left-Handed, Conserves Lepton Number and Solves the Autobahn Paradox (Illustrative Discussion)

    CERN Document Server

    Jentschura, U D

    2012-01-01

    Consider a gedanken experiment in which a massive left-handed neutrino, traveling on an autobahn at a speed of v=0.999c is overtaken by a tuned-up Cagiva V-Raptor 1000 traveling at a speed of 0.999999c. The biker, looking back, would see a right-handed neutrino. Unless one invokes exotic mechanisms like a sterile neutrino, this "autobahn paradox" implies that a massive subluminal (tardyonic) neutrino necessarily has to be a Majorana particle, i.e, equal to its own antiparticle. In turn, this would require us to assign the same lepton number to charged leptons and antileptons, essentially voiding the concept of lepton number. By contrast, an infinitesimally superluminal (tachyonic) neutrino is not equal to its own antiparticle and allows us to assign proper lepton number, just as if the neutrino were a Weyl particle. Furthermore, if Lorentz symmetry holds, then an infinitesimally tachyonic neutrino remains superluminal upon Lorentz transformation, which implies that it is impossible to overtake it in a gedanke...

  19. 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,

  20. Weak values obtained from mass-energy equivalence

    Science.gov (United States)

    Zhang, Miao

    2017-01-01

    Quantum weak measurement, measuring some observable quantities within the selected subensemble of the entire quantum ensemble, can produce many interesting results such as the superluminal phenomena. An outcome of such a measurement is the weak value which has been applied to amplify some weak signals of quantum interactions in lots of previous references. Here, we apply the weak measurement to the system of relativistic cold atoms. According to mass-energy equivalence, the internal energy of an atom will contribute its rest mass and consequently the external momentum of center of mass. This implies a weak coupling between the internal and external degrees of freedom of atoms moving in the free space. After a duration of this coupling, a weak value can be obtained by post-selecting an internal state of atoms. We show that the weak value can change the momentum uncertainty of atoms and consequently help us to experimentally measure the weak effects arising from mass-energy equivalence.

  1. Studies of the Jet in BL Lacertae. II. Superluminal Alfv\\'en Waves

    CERN Document Server

    Cohen, M H; 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

    2014-01-01

    Ridge lines on the pc-scale jet of the active galactic nucleus BL Lac display transverse patterns that move superluminally downstream. The patterns are not ballistic, but are analogous to waves on a whip. Their apparent speeds $\\beta_\\mathrm{app}$ (units of $c$) range from 4.2 to 13.5, corresponding to $\\beta_\\mathrm{wave}^\\mathrm{gal}= 0.981 - 0.998$ 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 longitudinal Alfv\\'en waves. The wave-induced transverse speed of the jet is non-relativistic ($\\beta_\\mathrm{tr}^\\mathrm{gal}\\sim 0.09$) and in agreement with our assumption of low-amplitude waves. In 2010 the wave activity subsided and the jet displayed a mild wiggle that had a complex oscillatory behavior. The waves are excited by changes in the position angle of the recollimation shock, in analogy to exciting a wave on a whip by shaking it. Simple models of the system are presen...

  2. Would Superluminal Influences Violate the Principle of Relativity?

    CERN Document Server

    Peacock, Kent A

    2013-01-01

    It continues to be alleged that superluminal influences of any sort would be inconsistent with special relativity for the following three reasons: (i) they would imply the existence of a distinguished' frame; (ii) they would allow the detection of absolute motion; and (iii) they would violate the relativity of simultaneity. This paper shows that the first two objections rest upon very elementary misunderstandings of Minkowski geometry and lingering Newtonian intuitions about instantaneity. The third objection has a basis, but rather than invalidating the notion of faster than light influences it points the way to more general conceptions of simultaneity that could allow for quantum nonlocality in a natural way.

  3. 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).

  4. Extreme Supernova Models for the Superluminous Transient ASASSN-15lh

    CERN Document Server

    Chatzopoulos, E; Vinko, J; Nagy, A P; Wiggins, B K; Even, W P

    2016-01-01

    The recent discovery of the unprecedentedly superluminous transient ASASSN-15lh (or SN 2015L) challenges all the power-input models that have been proposed for superluminous supernovae. Here we examine some of the few viable interpretations of ASASSN-15lh in the context of a stellar explosion, involving combinations of one or more power inputs. We model the lightcurve of ASASSN-15lh with a hybrid model that includes contributions from magnetar spin-down energy and hydrogen-poor circumstellar interaction. We also investigate models of pure circumstellar interaction with a massive hydrogen-deficient shell and discuss about the lack of interaction features in the observed spectra. We find that ASASSN-15lh can be best modeled by the energetic core-collapse of a ~40 Msun supernova interacting with a hydrogen-poor shell of ~20 Msun. The circumstellar shell and progenitor mass are consistent with a rapidly rotating pulsational pair-instability supernova progenitor as required for strong interaction following the fin...

  5. 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.

  6. 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

    2014-01-01

    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.

  7. SN 2015bn: a detailed multi-wavelength view of a nearby superluminous supernova

    CERN Document Server

    Nicholl, M; Smartt, S J; Margutti, R; Kamble, A; Alexander, K D; Chen, T -W; Inserra, C; Arcavi, I; Blanchard, P K; Cartier, R; Chambers, K C; Childress, M J; Chornock, R; Cowperthwaite, P S; Drout, M; Flewelling, H A; Fraser, M; Gal-Yam, A; Galbany, L; Harmanen, J; Holoien, T W -S; Hosseinzadeh, G; Howell, D A; Huber, M E; Jerkstrand, A; Kankare, E; Kochanek, C S; Lin, Z -Y; Lunnan, R; Magnier, E A; Maguire, K; McCully, C; McDonald, M; Metzger, B D; Milisavljevic, D; Mitra, A; Reynolds, T; Saario, J; Shappee, B J; Smith, K W; Valenti, S; Villar, V A; Waters, C; Young, D R

    2016-01-01

    We present observations of SN 2015bn (= PS15ae = CSS141223-113342+004332 = MLS150211-113342+004333), a Type I superluminous supernova (SLSN) at $z=0.1136$. As well as being one of the closest SLSNe, it is intrinsically brighter ($M_U\\approx-23.1$) and in a fainter host ($M_B\\approx-16.0$) than other SLSNe at $z\\sim0.1$. We collected the most extensive dataset for an SLSN I to date, including spectroscopy and UV to NIR photometry from $-$50 to +250 d from maximum light. SN 2015bn is a slowly-declining SLSN, but exhibits surprising undulations in the light curve on a timescale of 30-50 d, which are more pronounced in the UV. The spectrum resembles other SLSNe, but our well-sampled data reveal extraordinarily slow evolution except for a rapid transformation between +7 and +30 d. We detect weak features that we tentatively suggest may be hydrogen and helium. At late times, blue colours and a trio of lines around 6000 \\AA\\ seem to distinguish slowly-declining SLSNe from faster ones. We derive physical properties i...

  8. Thermal expansion of the earth and the speed of neutrinos

    CERN Document Server

    Unnikrishnan, C S

    2011-01-01

    It is pointed out that one of the systematic effects that can affect the measurement of the speed of neutrinos significantly is the variability of the unaveraged measurement of the distance between two points on the earth due to thermal expansion. Possible difference between estimates done with surface GPS apparatus and the true underground baseline can change substantially the statistical significance of the result of superluminal speed of neutrinos, reported recently.

  9. 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.

  10. Experimental demonstration of a new radiation mechanism: emission by an oscillating, accelerated, superluminal polarization current

    CERN Document Server

    Ardavan, A; Ardavan, H; Fopma, J; Halliday, D; Hayes, W

    2004-01-01

    We describe the experimental implementation of a superluminal ({\\it i.e.} faster than light {\\it in vacuo}) polarization current distribution that both oscillates and undergoes centripetal acceleration. Theoretical treatments lead one to expect that the radiation emitted from each volume element of such a polarization current will comprise a \\v{C}erenkov-like envelope with two sheets that meet along a cusp. The emission from the experimental machine is in good agreement with these expectations, the combined effect of the volume elements leading to tightly-defined beams of a well-defined geometry, determined by the source speed and trajectory. In addition, over a restricted range of angles, we detect the presence of cusps in the emitted radiation. These are due to the detection over a short time period (in the laboratory frame) of radiation emitted over a considerably longer period of source time. Consequently, the intensity of the radiation at these angles was observed to decline more slowly with increasing d...

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

    CERN Document Server

    Chang, Zhe; Wang, Sai; 10.1016/j.physletb.2012.03.002

    2012-01-01

    Recently, Cohen and Glashow [A.G. Cohen, S.L. Glashow, Phys. Rev. Lett. {\\bf 107}, 181803 (2011)] 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: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 paper, 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.

  12. Bessel-X waves: superluminal propagation and the Minkowski space-time

    OpenAIRE

    Mugnai, D.

    2006-01-01

    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) h...

  13. 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.

  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. Selective determination of ammonium ions by high-speed ion-exclusion chromatography on a weakly basic anion-exchange resin column.

    Science.gov (United States)

    Mori, Masanobu; Tanaka, Kazuhiko; Helaleh, Murad I H; Xu, Qun; Ikedo, Mikaru; Ogura, Yutaka; Sato, Shinji; Hu, Wenzhi; Hasebe, Kiyoshi

    2003-05-16

    This paper describes an ion-exclusion chromatographic system for the rapid and selective determination of ammonium ion. The optimized ion-exclusion chromatographic system was established with a polymethacrylate-based weakly basic anion-exchange resin column (TSKgel DEAE-5PW) as the separation column, an aqueous solution containing 0.05 mM tetramethylammonium hydroxide (pH 9.10) as eluent with conductimetric detection for the analyte determination. Under the optimum chromatographic conditions, ammonium ion was determined within 2.3 min with a detection limit (S/N=3) better than 0.125 microM. Ammonium ion in rain and river waters was precisely determined using this ion-exclusion chromatographic system.

  16. Two parameters describing a superluminal neutrino%二参量描述的超光速中微子述的超光速中微子

    Institute of Scientific and Technical Information of China (English)

    倪光炯; 张操

    2002-01-01

    Based on the experimental data that the mass-square of neutrino might be negative, a quantum theory for superluminal neutrino is proposed. Two Weyl equations coupled together via a mass term respecting the maximum parity violation lead to a new equation which describes the superluminal motion of neutrino with permanent helicity. Various strange features of subluminal and superluminal particles can be ascribed to the relative variation of two contradictory fields superposing coherently inside the particle with the change of its speed u in the whole range (0<u<∞). Being compatible with the theory of special relativity, this theory may have various applications.%根据中微子质量平方是负值的实验数据,提出了一个关于超光速中微子的量子理论.用一个和最大宇称破坏相关的质量项将两个Weyl方程耦合在一起,得到一个描述具有永久螺旋度且超光速运动的中微子的新方程.超光速粒子的速度在 (0,∞)范围内变化,其内部相干迭加的两个矛盾场的相对变化导致亚光速粒子和超光速粒子的各种奇异特性.这个理论和狭义相对论是兼容的,因而可以有多方面的应用.

  17. Weak Convergence and Weak Convergence

    Directory of Open Access Journals (Sweden)

    Narita Keiko

    2015-09-01

    Full Text Available In this article, we deal with weak convergence on sequences in real normed spaces, and weak* convergence on sequences in dual spaces of real normed spaces. In the first section, we proved some topological properties of dual spaces of real normed spaces. We used these theorems for proofs of Section 3. In Section 2, we defined weak convergence and weak* convergence, and proved some properties. By RNS_Real Mizar functor, real normed spaces as real number spaces already defined in the article [18], we regarded sequences of real numbers as sequences of RNS_Real. So we proved the last theorem in this section using the theorem (8 from [25]. In Section 3, we defined weak sequential compactness of real normed spaces. We showed some lemmas for the proof and proved the theorem of weak sequential compactness of reflexive real Banach spaces. We referred to [36], [23], [24] and [3] in the formalization.

  18. A sub-solar metallicity is required for superluminous supernova progenitors

    CERN Document Server

    Chen, T -W; Yates, R M; Nicholl, M; Krühler, T; Schady, P; Dennefeld, M; Inserra, C

    2016-01-01

    Host galaxy properties provide strong constraints on the stellar progenitors of superluminous supernovae. By comparing a sample of 18 low-redshift superluminous supernova hosts to a volume-limited galaxy population in the local Universe, we show that sub-solar metallici- ties seems to be a requirement. All superluminous supernovae in hosts with high measured gas-phase metallicities are found to explode at large galactocentric radii, indicating that the metallicity at the explosion site is likely lower than the integrated host value. We also confirm that high specific star-formation rates are a feature of superluminous supernova host galaxies, but interpret this as simply a consequence of the anti-correlation between gas-phase metallic- ity and specific star-formation rate and the requirement of on-going star formation to produce young, massive stars greater than ~ 10-20 M_sun . Based on our sample, we propose an upper limit of ~ 0.5 Z_sun for forming superluminous supernova progenitors (assuming an N2 metal- ...

  19. Superluminal reflection and transmission of light pulses via resonant four-wave mixing in cesium vapor.

    Science.gov (United States)

    Jiang, Qichang; Zhang, Yan; Wang, Dan; Ahrens, Sven; Zhang, Junxiang; Zhu, Shiyao

    2016-10-17

    We report the experimental manipulation of the group velocities of reflected and transmitted light pulses in a degenerate two-level atomic system driven by a standing wave, which is created by two counter-propagating light beams of equal frequencies but variable amplitudes. It is shown that the light pulse is reflected with superluminal group velocity while the transmitted pulse propagates from subluminal to superluminal velocities via changing the power of the backward coupling field. We find that the simultaneous superluminal light reflection and transmission can be reached when the power of the backward field becomes closer or equal to the forward power, in this case the periodical absorption modulation for photonic structure is established in atoms. The theoretical discussion shows that the anomalous dispersion associated with a resonant absorption dip within the gain peak due to four-wave mixing leads to the superluminal reflection, while the varying dispersion from normal to anomalous at transparency, transparency within absorption, and electromagnetically induced absorption windows leads to the subluminal to superluminal transmission.

  20. 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.

  1. The unexpected, long-lasting, UV rebrightening of the superluminous supernova ASASSN-15lh

    Science.gov (United States)

    Godoy-Rivera, D.; Stanek, K. Z.; Kochanek, C. S.; Chen, Ping; Dong, Subo; Prieto, J. L.; Shappee, B. J.; Jha, S. W.; Foley, R. J.; Pan, Y.-C.; Holoien, T. W.-S.; Thompson, Todd. A.; Grupe, D.; Beacom, J. F.

    2017-04-01

    Given its peak luminosity and early-time spectra, ASASSN-15lh was classified as the most luminous supernova ever discovered. Here, we report a UV rebrightening of ASASSN-15lh observed with Swift during our follow-up campaign. The rebrightening began at t ≃ 90 d (observer frame) after the primary peak and was followed by a ∼120-d long plateau in the bolometric luminosity, before starting to fade again at t ≃ 210 d. ASASSN-15lh rebrightened in the Swift UV bands by ΔmUVW2 ≃ -1.75 mag, ΔmUVM2 ≃ -1.25 mag and ΔmUVW1 ≃ -0.8 mag, but did not rebrighten in the optical bands. Throughout its initial decline, subsequent rebrightening and renewed decline, the spectra did not show evidence of interactions between the ejecta and circumstellar medium such as narrow emission lines. There are hints of weak Hα emission at late-times, but Margutti et al. have shown that it is narrow line emission consistent with star formation in the host nucleus. By fitting a blackbody, we find that during the rebrightening, the effective photospheric temperature increased from TBB ≃ 11 000 K to TBB ≃ 18 000 K. Over the ∼ 550 d since its detection, ASASSN-15lh has radiated ∼1.7 -1.9 × 1052 erg. Although its physical nature remains uncertain, the evolution of ASASSN-15lh's photospheric radius, its radiated energy and the implied event rate, are all more similar to those of H-poor superluminous supernovae than to tidal disruption events.

  2. ANALYTICAL LIGHT CURVE MODELS OF SUPERLUMINOUS SUPERNOVAE: {chi}{sup 2}-MINIMIZATION OF PARAMETER FITS

    Energy Technology Data Exchange (ETDEWEB)

    Chatzopoulos, E.; Wheeler, J. Craig; Vinko, J. [Department of Astronomy, University of Texas at Austin, Austin, TX (United States); Horvath, Z. L.; Nagy, A., E-mail: manolis@astro.as.utexas.edu [Department of Optics and Quantum Electronics, University of Szeged (Hungary)

    2013-08-10

    We present fits of generalized semi-analytic supernova (SN) light curve (LC) models for a variety of power inputs including {sup 56}Ni and {sup 56}Co radioactive decay, magnetar spin-down, and forward and reverse shock heating due to supernova ejecta-circumstellar matter (CSM) interaction. We apply our models to the observed LCs of the H-rich superluminous supernovae (SLSN-II) SN 2006gy, SN 2006tf, SN 2008am, SN 2008es, CSS100217, the H-poor SLSN-I SN 2005ap, SCP06F6, SN 2007bi, SN 2010gx, and SN 2010kd, as well as to the interacting SN 2008iy and PTF 09uj. Our goal is to determine the dominant mechanism that powers the LCs of these extraordinary events and the physical conditions involved in each case. We also present a comparison of our semi-analytical results with recent results from numerical radiation hydrodynamics calculations in the particular case of SN 2006gy in order to explore the strengths and weaknesses of our models. We find that CS shock heating produced by ejecta-CSM interaction provides a better fit to the LCs of most of the events we examine. We discuss the possibility that collision of supernova ejecta with hydrogen-deficient CSM accounts for some of the hydrogen-deficient SLSNe (SLSN-I) and may be a plausible explanation for the explosion mechanism of SN 2007bi, the pair-instability supernova candidate. We characterize and discuss issues of parameter degeneracy.

  3. The Unexpected, Long-Lasting, UV Rebrightening of the Super-Luminous Supernova ASASSN-15lh

    Science.gov (United States)

    Godoy-Rivera, D.; Stanek, K. Z.; Kochanek, C. S.; Chen, Ping; Dong, Subo; Prieto, J. L.; Shappee, B. J.; Jha, S. W.; Foley, R. J.; Pan, Y.-C.; Holoien, T. W.-S.; Thompson, Todd. A.; Grupe, D.; Beacom, J. F.

    2017-01-01

    Given its peak luminosity and early-time spectra, ASASSN-15lh was classified as the most luminous supernova (SN) ever discovered (Dong et al. 2016).. Here we report a UV rebrightening of ASASSN-15lh observed with Swift during our follow-up campaign. The rebrightening began at t ≃ 90 days (observer frame) after the primary peak and was followed by a ˜120-day long plateau in the bolometric luminosity, before starting to fade again at t ≃ 210 days. ASASSN-15lh rebrightened in the Swift UV bands by ΔmUVW2 ≃ -1.75 mag, ΔmUVM2 ≃ -1.25 mag, and ΔmUVW1 ≃ -0.8 mag, but did not rebrighten in the optical bands. Throughout its initial decline, subsequent rebrightening, and renewed decline, the spectra did not show evidence of interactions between the ejecta and circumstellar medium (CSM) such as narrow emission lines. There are hints of weak Hα emission at late-times, but Margutti et al. (2016) have shown that it is narrow line emission consistent with star formation in the host nucleus. By fitting a blackbody we find that during the rebrightening the effective photospheric temperature increased from TBB ≃ 11000 K to TBB ≃ 18000 K. Over the ˜ 550 days since its detection, ASASSN-15lh has radiated ˜1.7 - -1.9 × 1052 ergs. Although its physical nature remains uncertain, the evolution of ASASSN-15lh's photospheric radius, its radiated energy, and the implied event rate, are all more similar to those of H-poor superluminous supernovae (SLSNe-I) than to tidal disruption events (TDEs).

  4. Super-luminous supernovae: 56Ni power versus magnetar radiation

    CERN Document Server

    Dessart, Luc; Waldman, Roni; Livne, Eli; Blondin, Stephane

    2012-01-01

    Much uncertainty surrounds the origin of super-luminous supernovae (SNe). Motivated by the discovery of the Type Ic SN2007bi, we study its proposed association with a pair-instability SN (PISN). We compute stellar-evolution models for primordial ~200Msun stars, simulating the implosion/explosion due to the pair-production instability, and use them as inputs for detailed non-LTE time-dependent radiative-transfer simulations that include non-local energy deposition and non-thermal processes. We retrieve the basic morphology of PISN light curves from red-supergiant, blue-supergiant, and Wolf-Rayet (WR) star progenitors. Although we confirm that a progenitor 100Msun helium core (PISN model He100) fits well the SN2007bi light curve, the low ratios of its kinetic energy and 56Ni mass to the ejecta mass, similar to standard core-collapse SNe, conspire to produce cool photospheres, red spectra subject to strong line blanketing, and narrow line profiles, all conflicting with SN2007bi observations. He-core models of in...

  5. Rapidly Rising Transients in the Supernova - Superluminous Supernova Gap

    CERN Document Server

    Arcavi, Iair; Howell, D Andrew; Bildsten, Lars; Leloudas, Giorgos; Hardin, Delphine; Prajs, Szymon; Perley, Daniel A; Svirski, Gilad; Gal-Yam, Avishay; Katz, Boaz; McCully, Curtis; Cenko, S Bradley; Lidman, Chris; Sullivan, Mark; Valenti, Stefano; Astier, Pierre; Balland, Cristophe; Carlberg, Ray G; Conley, Alex; Fouchez, Dominique; Guy, Julien; Pain, Reynald; Palanque-Delabrouille, Nathalie; Perrett, Kathy; Pritchet, Chris J; Regnault, Nicolas; Rich, James; Ruhlmann-Kleider, Vanina

    2015-01-01

    We present observations of four rapidly rising (t_{rise}~10d) transients with peak luminosities between those of supernovae (SNe) and superluminous SNe (M_{peak}~-20) - one discovered and followed by the Palomar Transient Factory (PTF) and three by the Supernova Legacy Survey (SNLS). 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 a Type II SN due to broad Halpha emission, but an unusual absorption feature, which can be interpreted as either high velocity Halpha (though deeper than in previously known cases) or Si II (as seen in Type Ia SNe), is also observed. We find that existing models of white dwarf detonations, CSM interaction, shock breakout in a wind (or steeper CSM) and magnetar spindown can not r...

  6. Spectropolarimetry of Superluminous Supernovae: Insight into Their Geometry

    Science.gov (United States)

    Inserra, C.; Bulla, M.; Sim, S. A.; Smartt, S. J.

    2016-11-01

    We present the first spectropolarimetric observations of a hydrogen-free superluminous supernova (SLSN) at z = 0.1136, namely SN 2015bn. The transient shows significant polarization at both of the observed epochs: one 24 days before maximum light in the rest-frame, and the other at 27 days after peak luminosity. Analysis of the Q - U plane suggests the presence of a dominant axis and no physical departure from the main axis at either epoch. The polarization spectrum along the dominant axis is characterized by a strong wavelength dependence and an increase in the signal from the first to the second epoch. We use a Monte Carlo code to demonstrate that these properties are consistent with a simple toy model that adopts an axisymmetric ellipsoidal configuration for the ejecta. We find that the wavelength dependence of the polarization is possibly due to a strong wavelength dependence in the line opacity, while the higher level of polarization at the second epoch is a consequence of the increase in the asphericity of the inner layers of the ejecta or the fact that the photosphere recedes into less spherical layers. The geometry of the SLSN is similar to that of stripped-envelope core-collapse SNe connected to GRB, while the overall evolution of the ejecta shape could be consistent with a central engine.

  7. Spectral evolution of superluminal components in parsec-scale jets

    CERN Document Server

    Mimica, P; Agudo, I; Martí, J M; Gómez, J L; Miralles, J A

    2008-01-01

    (Abridged) We present numerical simulations of the spectral evolution and radio emission of superluminal components in relativistic jets. We have developed an algorithm (SPEV) for the transport of a population of non-thermal particles (NTPs). For very large values of the ratio of gas pressure to magnetic field energy density ($\\sim 6\\times 10^4$), quiescent over-pressured jet models show substantial spectral evolution compared to models whithout radiative losses. Larger values of the magnetic field yield much shorter jets. Larger magnetic fields result in shorter losses-dominated regimes, with a rapid and intense radiation of energy. We also show that jets with a positive photon spectral index may result if the lower limit $\\gamma_min$ of the NTP energy distribution is placed close or above a threshold $\\gamma_M$, where the synchrotron function R has its maximum. A temporary increase of the Lorentz factor at the jet inlet produces a traveling perturbation that appears in the synthetic maps as a radio componen...

  8. 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.; Zensus, J. A.

    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.

  9. The Trails of Superluminal Jet Components in 3C111

    CERN Document Server

    Kadler, M; Perucho, M; Kovalev, Y Y; Homan, D C; Agudo, I; Kellermann, K I; Aller, M F; Aller, H D; Lister, M L; Zensus, J A

    2008-01-01

    In 1996, a major radio flux-density outburst occured in the broad-line radio galaxy 3C111. It was followed by a particularly bright plasma ejection associated with a superluminal jet component, which has shaped the parsec-scale structure of 3C111 for almost a decade. Here, we present results from 18 epochs of Very Long Baseline Array (VLBA) observations conducted since 1995 as part of the VLBA 2 cm Survey and MOJAVE monitoring programs. This major event allows us to study a variety of processes associated with outbursts of radio-loud AGN in much greater detail than has been possible in other cases: the primary perturbation gives rise to the formation of a leading and a following component, which are interpreted as a forward and a backward-shock. Both components evolve in characteristically different ways and allow us to draw conclusions about the work flow of jet-production events; the expansion, acceleration and recollimation of the ejected jet plasma in an environment with steep pressure and density gradien...

  10. Zooming In on the Progenitors of Superluminous Supernovae With HST

    CERN Document Server

    Lunnan, R; Berger, E; Rest, A; Fong, W; Scolnic, D; Jones, D; Soderberg, A M; Challis, P M; Drout, M R; Foley, R J; Huber, M E; Kirshner, R P; Leibler, C; Marion, G H; McCrum, M; Milisavljevic, D; Narayan, G; Sanders, N E; Smartt, S J; Smith, K W; Tonry, J L; Burgett, W S; Chambers, K C; Flewelling, H; Kudritzki, R -P; Wainscoat, R J; Waters, C

    2014-01-01

    We present Hubble Space Telescope rest-frame ultraviolet imaging of the host galaxies of 16 hydrogen-poor superluminous supernovae (SLSNe), including 11 events from the Pan-STARRS Medium Deep Survey. Taking advantage of the superb angular resolution of HST, we characterize the galaxies' morphological properties, sizes and star formation rate densities. We determine the SN locations within the host galaxies through precise astrometric matching, and measure physical and host-normalized offsets, as well as the SN positions within the cumulative distribution of UV light pixel brightness. We find that the host galaxies of H-poor SLSNe are irregular, compact dwarf galaxies, with a median half-light radius of just 0.9 kpc. The UV-derived star formation rate densities are high ( ~ 0.1 M_sun/yr/kpc^2), suggesting that SLSNe form in overdense environments. Their locations trace the UV light of their host galaxies, with a distribution intermediate between that of LGRBs (which are strongly clustered on the brightest regi...

  11. On the nature of Hydrogen-rich Superluminous Supernovae

    CERN Document Server

    Inserra, C; Gall, E E E; Leloudas, G; Chen, T -W; Schulze, S; Jerkstarnd, 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; Gutierrez, C P; Hosseinzadeh, G; Howell, D A; Huber, M; Kankare, E; Magnier, E A; Maguire, K; McCully, C; Prajs, S; Primak, N; Scalzo, R; Schmidt, B P; Smith, K W; Tucker, B E; Valenti, S; Wilman, M; Young, D R; Yuan, F

    2016-01-01

    We present observational data for two hydrogen-rich superluminous supernovae (SLSNe), namely SN 2013hx and PS15br. These objects, together with SN 2008es are the only SLSNe showing a distinct, broad H$\\alpha$ feature during the photospheric phase and also do not show any clear sign of interaction between fast moving ejecta and circumstellar shells in their early spectra. Therefore we classify them as SLSN II as distinct from the known class of SLSN IIn. Both transients show a slow decline at later times, and monitoring of SN 2013hx out to 300 days after explosion indicates that the luminosity in this later phase does have a contribution from interaction. We detect strong, multi-component H$\\alpha$ emission at 240 days past maximum which we interpret as an indication of interaction of the ejecta with an asymmetric, clumpy circumstellar material. The spectra and photometric evolution of the two objects are similar to some bright type II (or type IIL) supernovae, although they have much higher luminosity and evo...

  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. Spectropolarimetry of superluminous supernovae: insight into their geometry

    CERN Document Server

    Inserra, C; Sim, S A; Smartt, S J

    2016-01-01

    We present the first spectropolarimetric observations of a hydrogen-free superluminous supernova at z=0.1136, namely SN 2015bn. The transient shows significant polarization at both the observed epochs: one 24 days before maximum light in the rest-frame, and the subsequent at 27 days after peak luminosity. Analysis of the Q-U plane suggests the presence of a dominant axis and no physical departure from the main axis at either epoch. The polarization spectrum along the dominant axis is characterized by a strong wavelength dependence and an increase in the signal from the first to the second epoch. We use a Monte Carlo code to demonstrate that these properties are consistent with a simple toy model that adopts an axi-symmetric ellipsoidal configuration for the ejecta. We find that the wavelength dependence of the polarisation is possibly due to a strong wavelength dependence in the line opacity, while the higher level of polarisation at the second epoch is a consequence of the increase in the asphericity of the ...

  14. 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.

  15. Long-duration superluminous supernovae at late times

    CERN Document Server

    Jerkstrand, A; Inserra, C; Nicholl, M; Chen, T -W; Krühler, T; Sollerman, J; Taubenberger, S; Gal-Yam, A; Kankare, E; Maguire, K; Fraser, M; Valenti, S; Sullivan, M; Cartier, R; Young, D R

    2016-01-01

    We present nebular-phase observations and spectral models of Type Ic superluminous supernovae. LSQ14an and SN 2015bn both display late-time spectra similar to SN 2007bi, and the class shows strong similarity with broad-lined Type Ic SNe such as SN 1998bw. Near-infrared observations of SN 2015bn at +315d show a strong Ca II triplet, O I 9263, O I 1.13 micron and Mg I 1.50 micron, but no strong He, Si, or S emission. The high Ca II NIR/[Ca II] 7291, 7323 ratio of 2 indicates a high electron density of n_e >~ 10^8 cm^{-3}. Spectral models of oxygen-zone emission are investigated to put constraints on the emitting region. Models require M(O) >~ 10 Msun to produce enough [O I] 6300, 6364 luminosity to match observed levels, irrespective of the powering situation and the density. This is an argument against shell collisions from pair-instability pulsations for explaining the powering, as these shells are limited to a few solar masses in published models. The high oxygen-zone mass, supported by high estimated magnes...

  16. The Volumetric Rate of Superluminous Supernovae at z~1

    CERN Document Server

    Prajs, S; Smith, M; Levan, A; Karpenka, N V; Edwards, T D P; Walker, C R; Wolf, W M; Balland, C; Carlberg, R; Howell, A; Lidman, C; Pain, R; Pritchet, C; Ruhlmann-Kleider, V

    2016-01-01

    We present a measurement of the volumetric rate of superluminous supernovae (SLSNe) at z~1, measured using archival data from the first four years of the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). We develop a method for the photometric classification of SLSNe to construct our sample. Our sample includes two previously spectroscopically-identified objects, and a further new candidate selected using our classification technique. We use the point-source recovery efficiencies from Perrett et.al. (2010) and a Monte Carlo approach to calculate the rate based on our SLSN sample. We find that the three identified SLSNe from SNLS give a rate of 91 (+76/-36) SNe/Yr/Gpc^3 at a volume-weighted redshift of z=1.13. This is equivalent to 2.2 (+1.8/-0.9) x10^-4 of the volumetric core collapse supernova rate at the same redshift. When combined with other rate measurements from the literature, we show that the rate of SLSNe increases with redshift in a manner consistent with that of the cosmic star formati...

  17. Rates of Superluminous Supernovae at z~0.2

    CERN Document Server

    Quimby, Robert M; Akerlof, Car; Wheeler, J Craig

    2013-01-01

    We calculate the volumetric rate of superluminous supernovae (SLSNe) based on 5 events discovered with the ROTSE-IIIb telescope. We gather light curves of 19 events from the literature and our own unpublished data and employ crude k-corrections to constrain the pseudo-absolute magnitude distributions in the rest frame ROTSE-IIIb (unfiltered) band pass for both the hydrogen poor (SLSN-I) and hydrogen rich (SLSN-II) populations. We find that the peak magnitudes of the available SLSN-I are narrowly distributed ($M = -21.7 \\pm 0.4$) in our unfiltered band pass and may suggest an even tighter intrinsic distribution when the effects of dust are considered, although the sample may be skewed by selection and publication biases. The presence of OII features near maximum light may uniquely signal a high luminosity event, and we suggest further observational and theoretical work is warranted to assess the possible utility of such SN 2005ap-like SLSN-I as distance indicators. Using the pseudo-absolute magnitude distribut...

  18. 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.

  19. What do the remnants of superluminous supernovae look like?

    Science.gov (United States)

    Leloudas, G.

    2016-06-01

    The remnants of core-collapse supernovae often present significant asymmetries while those of thermonuclear supernovae are, more or less, spherically symmetric. As superluminous supernovae (SLSN) do not occur in Milky Way-type galaxies (they prefer metal-poor starburst dwarfs), our chances of studying directly a SLSN remnant are very limited, except perhaps in the Magellanic clouds. Therefore, the only way of probing the SLSN geometry, and thus identifying potential SLSN remnant candidates, is through polarimetry of the explosions themselves. I will present the first polarimetric observations of SLSNe obtained through a dedicated ToO program at the VLT. LSQ14mo is a SLSN-I that showed only a very limited degree of polarisation (P = 0.52%), which corresponds to an upper limit of 10% in the photosphere asphericity. In addition, this signal can be entirely due to interstellar polarisation in the host galaxy. This is perhaps surprising as the leading models for H-poor SLSNe involve a magnetar or CSM interaction, i.e. configurations that are not expected to be spherically symmetric. Observations of a SLSN-II yielded a more significant degree of polarisation, while preliminary analysis for a SLSN-R reveals similarly low levels of asphericity as for LSQ14mo.

  20. 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.

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

    CERN Document Server

    Macke, Bruno

    2016-01-01

    In a recent theoretical article [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.

  2. Superluminal motions? A bird-eye view of the experimental situation

    CERN Document Server

    Recami, E

    2001-01-01

    In this article (after some brief theoretical considerations) a bird-eye view is presented -with the help of nine figures- of the various experimental sectors of physics in which Superluminal motions seem to appear. In particular, a panorama is presented of the experiments with evanescent waves and/or tunnelling photons, and with the "localized Superluminal solutions" to the Maxwell equations (e.g., with the so-called X-shaped ones). The present paper is sketchy, but is followed by a large enough bibliography to allow the interested reader deepening the preferred topic.

  3. Discussions of the Quantum Superluminality%论量子超光速性

    Institute of Scientific and Technical Information of China (English)

    黄志洵

    2012-01-01

    A.Einstein held an opposite attitude towards Quantum Mechanics(QM),which first appeared in 1926 and reached the top in 1935 when he,together with B.Podolsky,N.Rosen published the EPR thesis and it promotes science development in an opposite side.The EPR thesis is based on Special Relativity(SR).Both SR and EPR deny the possibility of faster-than-light.But QM allows the existence of faster-than-light,agreeing to non-locality of QM is the premise of researching in faster-than light.In 1965,during the interview John Bell confided that his unequality was the outcome of EPR thinking,which denied ultra-space effect under EPR thesis,conditions resulted in quite peculiar correlations that QM predicted.The results of Aspect’s experiments were within expectation that QM has never been wrong now and will not in the future despite of strict requirements.Undoubtedly,the experiments proved that Einstein’s ideas didn’t hold water.In Bell’s opinion,to get rid of the difficulties after the announcement of the Aspect’s experiments,it intends to go back to Lorentz and Poincarè,and assume that ether existed as a referential system in which matters went faster than light.Bell repeatedly pointed out that be wanted to go back to ether because EPR had predicted there was something faster than light in the background.…… Since 1992,it is reported that there have been many successful faster than light experiments.Some of them are based on quantum tunneling effect;some are based on classic physical phenomena such as evanescent waves,anomalous dispersion.And in 2008,D.Salart et.al.performed a experiment using entangled photons between two villages separated by 18km.In conclusion,the speed of the influence of quantum entanglement would have to exceed than of light by at least four orders of magnitude,i.e.10 4 c ~ 10 7 c.Anyway,this experiment was the summation of discussions about the EPR thesis for a long time.For the past 25 years Quantum Superluminality was one subject of my

  4. Weak Force

    CERN Multimedia

    Without the weak force, the sun wouldn't shine. The weak force causes beta decay, a form of radioactivity that triggers nuclear fusion in the heart of the sun. The weak force is unlike other forces: it is characterised by disintegration. In beta decay, a down quark transforms into an up quark and an electron is emitted. Some materials are more radioactive than others because the delicate balance between the strong force and the weak force varies depending on the number of particles in the atomic nucleus. We live in the midst of a natural radioactive background that varies from region to region. For example, in Cornwall where there is a lot of granite, levels of background radiation are much higher than in the Geneva region. Text for the interactive: Move the Geiger counter to find out which samples are radioactive - you may be surprised. It is the weak force that is responsible for the Beta radioactivity here. The electrons emitted do not cross the plastic cover. Why do you think there is some detected radioa...

  5. The volumetric rate of superluminous supernovae at z ˜ 1

    Science.gov (United States)

    Prajs, S.; Sullivan, M.; Smith, M.; Levan, A.; Karpenka, N. V.; Edwards, T. D. P.; Walker, C. R.; Wolf, W. M.; Balland, C.; Carlberg, R.; Howell, D. A.; Lidman, C.; Pain, R.; Pritchet, C.; Ruhlmann-Kleider, V.

    2017-01-01

    We present a measurement of the volumetric rate of superluminous supernovae (SLSNe) at z ˜ 1.0, measured using archival data from the first four years of the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). We develop a method for the photometric classification of SLSNe to construct our sample. Our sample includes two previously spectroscopically identified objects, and a further new candidate selected using our classification technique. We use the point-source recovery efficiencies from Perrett et al. and a Monte Carlo approach to calculate the rate based on our SLSN sample. We find that the three identified SLSNe from SNLS give a rate of 91^{+76}_{-36} SNe yr-1 Gpc-3 at a volume-weighted redshift of z = 1.13. This is equivalent to 2.2^{+1.8}_{-0.9}× 10^{-4} of the volumetric core-collapse supernova rate at the same redshift. When combined with other rate measurements from the literature, we show that the rate of SLSNe increases with redshift in a manner consistent with that of the cosmic star formation history. We also estimate the rate of ultra-long gamma-ray bursts based on the events discovered by the Swift satellite, and show that it is comparable to the rate of SLSNe, providing further evidence of a possible connection between these two classes of events. We also examine the host galaxies of the SLSNe discovered in SNLS, and find them to be consistent with the stellar-mass distribution of other published samples of SLSNe.

  6. 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.

  7. Study on the Superluminal Group Velocity in a Coaxial Photonic Crystal

    Institute of Scientific and Technical Information of China (English)

    LuGuizhen; HuangZhixun; GuanJian

    2004-01-01

    In this paper, the superluminal group velocity in a coaxial photonic crystal is studied. The simulation of the effective refraction index in coaxial photonic crystal is performed. The group velocity is calculated based on the transmission line equations and compared with experimental results.

  8. Revealing the binary origin of Type Ic superluminous supernovae through nebular hydrogen emission

    Science.gov (United States)

    Moriya, Takashi J.; Liu, Zheng-Wei; Mackey, Jonathan; Chen, Ting-Wan; Langer, Norbert

    2015-12-01

    We propose that nebular Hα emission, as detected in the Type Ic superluminous supernova iPTF13ehe, stems from matter that is stripped from a companion star when the supernova ejecta collide with it. The temporal evolution, the line broadening, and the overall blueshift of the emission are consistent with this interpretation. We scale the nebular Hα luminosity predicted for Type Ia supernovae in single-degenerate systems to derive the stripped mass required to explain the Hα luminosity of iPTF13ehe. We find a stripped mass of 0.1-0.9 solar masses, assuming that the supernova luminosity is powered by radioactivity or magnetar spin down. Because a central heating source is required to excite the Hα emission, an interaction-powered model is not favored for iPTF13ehe if the Hα emission is from stripped matter. We derive a companion mass of more than 20 solar masses and a binary separation of less than about 20 companion radii based on the stripping efficiency during the collision, indicating that the supernova progenitor and the companion formed a massive close binary system. If Type Ic superluminous supernovae generally occur in massive close binary systems, the early brightening observed previously in several Type Ic superluminous supernovae may also be due to the collision with a close companion. Observations of nebular hydrogen emission in future Type Ic superluminous supernovae will enable us to test this interpretation.

  9. 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...

  10. Superluminal neutrinos and extra dimensions: constraints from the null energy condition

    OpenAIRE

    Gubser, Steven S.

    2011-01-01

    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.

  11. 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

  12. High-speed ion-exclusion chromatography of dissolved carbon dioxide on a small weakly acidic cation-exchange resin column with ion-exchange enhancement columns of conductivity detection.

    Science.gov (United States)

    Mori, Masanobu; Ikedo, Mikaru; Hu, Wenzhi; Helaleh, Murad I H; Xu, Qun; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2005-10-28

    The high-speed ion-exclusion chromatographic determination of dissolved carbon dioxide, i.e., carbonic acid, hydrogencarbonate or carbonate, with conductivity detection was obtained using a small column packed with a weakly acidic cation-exchange resin in the H+-form (40 mm long x 4.6 mm i.d., 3 microm-particle and 0.1 meq./ml-capacity). Two different ion-exchange resin columns, which were a strongly acidic cation-exchange resin in the K+-form and a strongly basic anion-exchange resin in the OH- -form, were connected after the separation column. The sequence of columns could convert dissolved carbon dioxide to KOH having high conductivity response. The enhancement effect for dissolved carbon dioxide could retain even on the vast chromatographic runs, by using the enhancement columns with high ion-exchange capacity above 1.0 meq./ml. The retention time was in 60 s at flow-rate of 1.2 ml/min. The calibration graph of dissolved carbon dioxide estimated as H2CO3- was linear in the range of 0.005-10 mM. The detection limit at signal to noise of 3 was 0.15 microM as H2CO3-. This method was applicable to several rainwater and tap water samples.

  13. 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.

  14. Weak relativity

    CERN Document Server

    Selleri, Franco

    2015-01-01

    Weak Relativity is an equivalent theory to Special Relativity according to Reichenbach’s definition, where the parameter epsilon equals to 0. It formulates a Neo-Lorentzian approach by replacing the Lorentz transformations with a new set named “Inertial Transformations”, thus explaining the Sagnac effect, the twin paradox and the trip from the future to the past in an easy and elegant way. The cosmic microwave background is suggested as a possible privileged reference system. Most importantly, being a theory based on experimental proofs, rather than mutual consensus, it offers a physical description of reality independent of the human observation.

  15. Discussions of the Quantum Superluminality%论量子超光速性

    Institute of Scientific and Technical Information of China (English)

    黄志洵

    2012-01-01

    , the experiments proved that Einstein' s ideas didn' t hold water. In Bell' s opinion, to get rid of the difficulties after the announce- ment of the Aspect' s experiments, it intends to go back to Lorentz and Poincare, and assume that ether existed as a referential system in which matters went faster than light. Bell repeatedly pointed out that be wanted to go back to ether because EPR had predicted there was something faster than light in the back- ground. …… Since 1992, it is reported that there have been many successful faster than light experi-ments. Some of them are based on quantum tunneling effect;some are based on classic physical phenome- na such as evanescent waves, anomalous dispersion. And in 2008, D. Salart et. al. performed a experiment using entangled photons between two villages separated by 18km. In conclusion ,the speed of the influence of quantum entanglement would have to exceed than of light by at least four orders of magnitude, i. e. 10^4c 10^7c. Anyway, this experiment was the summation of discussions about the EPR thesis for a long time. For the past 25 years Quantum Superluminality was one subject of my chief study. In 1985 ,we pro- posed the model of quantum potential barrier equivalent circuit. In 1991, we first indicated that there could be the wave velocity vp 〈 0 and vg 〈 0 in the evanescent waves mode of the waveguide below cut off and the book "An Introduction to the Theory of waveguide Below Cut -off " made me get the First Na- tional Scientific and Technology Book Award of China. Moreover, in 2003 we through an experiment in the coaxial photonic crystal, a superluminal group velocity of ( 1.5 - 2.4) c are observed in the stop - band of frequency. In 2005, we suggested the term of General Information Velocity (GIV) ;and in 2010, we sugges- ted the term of Quantum Superluminality ( QS), and also suggested remodel the existing accelerator to dis- cover the superluminal strange electron. Now,this paper discusses some problems of

  16. A Non-Mainstream Viewpoint on Apparent Superluminal Phenomena in AGN Jet

    Indian Academy of Sciences (India)

    Wen-Po Liu; Li-Yan Liu; Chun-Cheng Wang

    2014-09-01

    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 beaming model) is not necessarily equal to one, e.g., Araudo et al. (2010) thought that there may be dense clouds around AGN jet base), and show that the group velocity of light close to one could seriously affect apparent superluminal phenomena and Doppler effect in the AGN jet (when the viewing angle and Lorentz factor take some appropriate values).

  17. Diffusion Simulation of Outer Radiation Belt Electron Dynamics Induced by Superluminous L-O Mode Waves

    Institute of Scientific and Technical Information of China (English)

    XIAO Fu-Liang; HE Zhao-Guo; ZHANG Sai; SU Zhen-Peng; CHEN Liang-Xu

    2011-01-01

    Temporal evolution of outer radiation belt electron dynamics resulting from superluminous L-O mode waves is simulated at L=6.5. Diffusion rates are evaluated and then used as inputs to solve a 2D momentum-pitch-angle diffusion equation, particularly with and without cross diffusion terms. Simulated results demonstrate that phase space density(PSD) of energetic electrons due to L-O mode waves can enhance significantly within 24 h, covering a broader pitch-angle range in the absence of cross terms than that in the presence of cross terms. PSD evolution is also determined by the peak wave frequency, particularly at high kinetic energies. This result indicates that superluminous waves can be a potential candidate responsible for outer radiation belt electron dynamics.

  18. Dynamic evolution of outer radiation belt electrons driven by superluminous R-X mode waves

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We present initial results on the temporal evolution of the phase space density (PSD) of the outer radiation belt energetic electrons driven by the superluminous R-X mode waves. We calculate diffusion rates in pitch angle and momentum assuming the standard Gaussian distributions in both wave frequency and wave normal angle at the location L=6.5. We solve a 2D momentum-pitch-angle Fokker-Planck equation using those diffusion rates as inputs. Numerical results show that R-X mode can produce significant acceleration of relativistic electrons around geostationary orbit,supporting previous findings that superluminous waves potentially contribute to dramatic variation in the outer radiation belt electron dynamics.

  19. Emission of correlated photon pairs from superluminal perturbations in dispersive media

    CERN Document Server

    Piazza, Francesco Dalla; Cacciatori, Sergio Luigi; Faccio, Daniel

    2012-01-01

    We develop a perturbative theory that describes a superluminal refractive perturbation propagating in a dispersive medium and the subsequent excitation of the quantum vacuum zero-point fluctuations. We find a process similar to the anomalous Doppler effect: photons are emitted in correlated pairs and mainly within a Cerenkov-like cone, one on the forward and the other in backward directions. The number of photon pairs emitted from the perturbation increases strongly with the degree of superluminality and under realizable experimental conditions, it can reach up to ~0.01 photons per pulse. Moreover, it is in principle possible to engineer the host medium so as to modify the effective group refractive index. In the presence of "fast light" media, e.g. a with group index smaller than unity, a further ~10x enhancement may be achieved and the photon emission spectrum is characterized by two sharp peaks that, in future experiments would clearly identify the correlated emission of photon pairs.

  20. 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.

  1. 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.

  2. Self-accelerating Massive Gravity: Superluminality, Cauchy Surfaces and Strong Coupling

    CERN Document Server

    Motloch, Pavel; Joyce, Austin; Motohashi, Hayato

    2015-01-01

    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 inte...

  3. Muscle Weakness

    Science.gov (United States)

    Al Kaissi, Ali; Ryabykh, Sergey; Ochirova, Polina; Kenis, Vladimir; Hofstätter, Jochen G.; Grill, Franz; Ganger, Rudolf; Kircher, Susanne Gerit

    2017-01-01

    Marked ligamentous hyperlaxity and muscle weakness/wasting associated with awkward gait are the main deficits confused with the diagnosis of myopathy. Seven children (6 boys and 1 girl with an average age of 8 years) were referred to our department because of diverse forms of skeletal abnormalities. No definitive diagnosis was made, and all underwent a series of sophisticated investigations in other institutes in favor of myopathy. We applied our methodology through the clinical and radiographic phenotypes followed by targeted genotypic confirmation. Three children (2 boys and 1 girl) were compatible with the diagnosis of progressive pseudorheumatoid chondrodysplasia. The genetic mutation was correlated with the WISP 3 gene actively expressed by articular chondrocytes and located on chromosome 6. Klinefelter syndrome was the diagnosis in 2 boys. Karyotyping confirmed 47,XXY (aneuploidy of Klinefelter syndrome). And 2 boys were finally diagnosed with Morquio syndrome (MPS type IV A) as both showed missense mutations in the N-acetylgalactosamine-sulfate sulfatase gene. Misdiagnosis can lead to the initiation of a long list of sophisticated investigations. PMID:28210640

  4. Geometry of Superluminal Light-Echo Pair Events

    Science.gov (United States)

    Nemiroff, Robert J.

    2017-01-01

    Light echoes, shadows, and ionization fronts can and do move faster than light, both in the lab and out in the cosmos. In general, though, a single observer cannot tell the speed of such echoes without distance information -- unless a very specific geometry arises: the radial component crosses c. The observer then sees this crossing location as the site where a pair of bright light echoes is created or annihilated. This pair event tells the observer that a precise speed occurs, a speed that does not scale with distance and so can potentially be leveraged to reveal geometry and distance information. A few simple scattering surface geometries are shown illuminated by a point flash, including linear and circular filaments. In practice, useful astronomical flash sources include novae and supernovae, although in theory any uniquely varying source of stellar variability could be sufficient.

  5. On determination of the geometric cosmological constant from the OPERA experiment of superluminal neutrinos

    OpenAIRE

    Yan, Mu-Lin; Hu, Sen; Huang, Wei; Xiao, Neng-Chao

    2011-01-01

    The recent OPERA experiment of superluminal neutrinos has deep consequences in cosmology. In cosmology a fundamental constant is the cosmological constant. From observations one can estimate the effective cosmological constant $\\Lambda_{eff}$ which is the sum of the quantum zero point energy $\\Lambda_{dark energy}$ and the geometric cosmological constant $\\Lambda$. The OPERA experiment can be applied to determine the geometric cosmological constant $\\Lambda$. It is the first time to distingui...

  6. Swift and LT UV and optical observations of type IIn superluminous supernova 2017gir

    Science.gov (United States)

    Cano, Zach; Kuin, Paul; Chandra, Poonam; Ashall, Chris; Malesani, Daniele; Pastorello, Andrea

    2017-09-01

    We observed the field of the type IIn superluminous supernova 2017gir (ATLAS17jsb, Tonry et al. 2017; Lyman et al. 2017, ATel 10674) with Swift via a target-of-opportunity for three epochs (6th, 16th and 19th of September, 2017) in the three UVOT UV filters (w1, m1, w2). The SN is clearly detected in all three filters, and it is seen that its brightness fades over this timescale.

  7. Properties of Magnetars Mimicking 56Ni-powered Light Curves in Type IC Superluminous Supernovae

    Science.gov (United States)

    Moriya, Takashi J.; Chen, Ting-Wan; Langer, Norbert

    2017-02-01

    Many Type Ic superluminous supernovae have light-curve decline rates after their luminosity peak, which are close to the nuclear decay rate of {}56{Co}, consistent with the interpretation that they are powered by {}56{Ni} and possibly pair-instability supernovae. However, their rise times are typically shorter than those expected from pair-instability supernovae, and Type Ic superluminous supernovae are often suggested to be powered by magnetar spin-down. If magnetar spin-down is actually a major mechanism to power Type Ic superluminous supernovae, it should be able to produce decline rates similar to the {}56{Co} decay rate rather easily. In this study, we investigate the conditions for magnetars under which their spin-down energy input can behave like the {}56{Ni} nuclear decay energy input. We find that an initial magnetic field strength within a certain range is sufficient to keep the magnetar energy deposition within a factor of a few of the {}56{Co} decay energy for several hundreds of days. Magnetar spin-down needs to be by almost pure dipole radiation with the braking index close to three to mimic {}56{Ni} in a wide parameter range. Not only late-phase {}56{Co}-decay-like light curves, but also rise time and peak luminosity of most {}56{Ni}-powered light curves can be reproduced by magnetars. Bolometric light curves for more than 700 days are required to distinguish the two energy sources solely by them. We expect that more slowly declining superluminous supernovae with short rise times should be found if they are mainly powered by magnetar spin-down.

  8. Superluminal Neutrinos from Special Relativity with de Sitter Space-time Symmetry

    OpenAIRE

    Yan, Mu-Lin; Xiao, Neng-Chao; Huang, Wei; Hu, Sen

    2011-01-01

    We explore the recent OPERA experiment of superluminal neutrinos in the framework of Special Relativity with de Sitter space-time symmetry (dS-SR). According to Einstein a photon is treated as a massless particle in the framework of Special Relativity. In Special Relativity (SR) we have the universal parameter $c$, the photon velocity $c_{photon}$ and the phase velocity of a light wave in vacuum $c_{wave}=\\lambda\

  9. Considerations about the apparent ''superluminal expansions'' observed in astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Recami, E.; Castellino, A.; Maccarrone, G.D.; Rodono, M.

    1986-06-11

    The orthodox models devised to explain the apparent ''superluminal expansions'' observed in astrophysics - and here briefly summarized and discussed together with the experimental data - do not seem to be too much successful, especially when confronted with the most recent observations, suggesting complicated expansion patterns, even with possible accelerations. At this point it may be, therefore, of some interest to explore the possible alternative models in which actual Superluminal motions take place. To prepare the ground, we start from a variational principle, introduce the elements of a tachyon mechanics within special relativity, and argue about the expected behaviour of tachyonic objects when interacting (gravitationally, for instance) among themselves or with ordinary matter. We then review and develop the simplet ''Superluminal models'', paying particular attention to the observations which they would give rise to. We conclude that some of them appear to be physically acceptable and are statistically favoured with respect to the orthodox ones.

  10. Weak measurements and supraluminal communication

    CERN Document Server

    Belinsky, A V

    2016-01-01

    There is suggested a version of the experiment with a correlated pair of particles in the entangled state. The experiment demonstrates that, in the case of weak and/or non-demolition measurements of one of the particles, it is possible to transmit information with a speed not limited by velocity of light.

  11. A proposal for a feasible quantum-optical scheme to test for the existence of superluminal signals via quantum mechanical entanglement

    CERN Document Server

    Kalamidas, Demetrios A

    2011-01-01

    Motivated by a proposal from Greenberger [Physica Scripta T76, p.57 (1998) ] for superluminal signaling, and inspired by an experiment from Mandel [Phys. Rev. Lett. 67, p.318 (1991) ] showing interference effects within multi-particle entanglement without coincidence detection, we propose a feasible quantum-optical scheme that purports to manifest the capacity for superluminal transfer of information between distant parties.

  12. 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.

    2013-10-01

    Super-luminous supernovae that radiate more than 1044 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 56Ni are synthesized; this isotope decays to 56Fe via 56Co, 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.

  13. 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.

  14. Enhanced Sensitivity in a Superluminal Single Mode DPAL Cavity at Room Temperature

    Science.gov (United States)

    Abi-Salloum, Tony; Yablon, Joshua; Tseng, Shih; Shahriar, Selim

    2012-06-01

    The note beat between two counter-propagating beams in a cavity is used to measure the effective change of the length of the cavity or interferometer for applications such as optical gyroscopes, vibrometers, and gravitational wave detectors. We show in this talk how a superluminal single mode laser cavity can enhance the measured note beat dramatically. We consider the inhomogeneous broadening case and study the dependence of the enhancement factor on few key parameters. We also show how Diode Pump Alkali Lasers (DPAL) are excellent candidates for such devices. Using a Rubidium based DPAL, we study the characteristics of these lasers and their effect on the proposed enhanced sensitivity.

  15. Closed timelike curves, superluminal signals, and "free will" in universal quantum mechanics

    CERN Document Server

    Nikolic, H

    2010-01-01

    We explore some implications of the hypothesis that quantum mechanics (QM) is universal, i.e., that QM does not merely describe information accessible to observers, but that it also describes the observers themselves. From that point of view, "free will" (FW) - the ability of experimentalists to make free choices of initial conditions - is merely an illusion. As a consequence, by entangling a part of brain (responsible for the illusion of FW) with a distant particle, one may create nonlocal correlations that can be interpreted as superluminal signals. In addition, if FW is an illusion, then QM on a closed timelike curve can be made consistent even without the Deutch nonlinear consistency constraint.

  16. Superluminal Energy Transmission in the Goos-Hanchen Shift of Total Reflection

    CERN Document Server

    Wang, Z Y

    2011-01-01

    This paper is to give a counter example for the theory of relativity. Firstly, the dispersion relation of surface electromagnetic waves is corresponding to that of a tachyon where the coefficient of proportionality is the squared Planck constant. Then we prove the energy flow velocity S/w of the Goos-Hanchen shift in vacuum is cn.sinI>c as well according to electrodynamics. These two different ways lead to a same conclusion that energy transport in the Goos-Hanchen effect of total reflection is faster than light. It is also helpful to study the tachyon of particle physics and superluminal motion observed in astronomy,etc.

  17. On determination of the geometric cosmological constant from the OPERA experiment of superluminal neutrinos

    CERN Document Server

    Yan, Mu-Lin; Huang, Wei; Xiao, Neng-Chao

    2011-01-01

    The recent OPERA experiment of superluminal neutrinos has deep consequences in cosmology. In cosmology a fundamental constant is the cosmological constant. From observations one can estimate the effective cosmological constant $\\Lambda_{eff}$ which is the sum of the quantum zero point energy $\\Lambda_{dark energy}$ and the geometric cosmological constant $\\Lambda$. The OPERA experiment can be applied to determine the geometric cosmological constant $\\Lambda$. It is the first time to distinguish the contributions of $\\Lambda$ and $\\Lambda_{dark energy}$ from each other by experiment. The determination is based on an explanation of the OPERA experiment in the framework of Special Relativity with de Sitter space-time symmetry.

  18. Superluminal Neutrinos from Special Relativity with de Sitter Space-time Symmetry

    CERN Document Server

    Yan, Mu-Lin; Huang, Wei

    2011-01-01

    We explore the recent OPERA experiment of superluminal neutrinos in the framework of Special Relativity with de Sitter space-time symmetry (dS-SR). According to Einstein, the photon is treated as the massless particle in the SR mechanics. The meanings of the universal parameter $c$ and the photon velocity $c_{photon}$ in SR have been analyzed. $c$ can be determined by means of the velocity-composition law in SR kinematically. And $c_{photon}$ is determined by the dispersion relations of SR. It is revealed that $c=c_{photon}$ in Einstein's Special Relativity (E-SR), but $c\

  19. 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

  20. 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.

  1. 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.

  2. Weak Galois and Weak Cocleft Coextensions

    Institute of Scientific and Technical Information of China (English)

    J.N. Alonso (A)lvarez; J.M. Fernández Vilaboa; R. González Rodríguez; A.B. Rodríguez Raposo

    2007-01-01

    For a weak entwining structure (A, C,ψ) living in a braided monoidal category with equalizers and coequalizers, we formulate the notion of weak A-Galois coextension with normal basis and we show that these Galois coextensions are equivalent to the weak A-cocleft coextensions introduced by the authors.

  3. The superluminous supernova PS1-11ap: bridging the gap between low and high redshift

    CERN Document Server

    McCrum, M; Kotak, R; Rest, A; Jerkstrand, A; Inserra, C; Rodney, S A; Chen, T -W; Howell, D A; Huber, M E; Pastorello, A; Tonry, J L; Bresolin, F; Kudritzki, R -P; Chornock, R; Berger, E; Smith, K; Botticella, M T; Foley, R J; Fraser, M; Milisavljevic, D; Nicholl, M; Riess, A G; Stubbs, C W; Valenti, S; Wood-Vasey, W M; Wright, D; Young, D R; Drout, M; Czekala, I; Burgett, W S; Chambers, K C; Draper, P; Flewelling, H; Hodapp, K W; Kaiser, N; Magnier, E A; Metcalfe, N; Sweeney, W; Wainscoat, R J

    2013-01-01

    We present optical photometric and spectroscopic coverage of the superluminous supernova (SLSN) PS1-11ap, discovered with the Pan-STARRS1 Medium Deep Survey at z = 0.524. This intrinsically blue transient rose slowly to reach a peak magnitude of M_u = -21.4 mag and bolometric luminosity of 8 x 10^43 ergs^-1 before settling onto a relatively shallow gradient of decline. The observed decline is significantly slower than those of the superluminous type Ic SNe which have been the focus of much recent attention. Spectroscopic similarities with the lower redshift SN2007bi and a decline rate similar to 56Co decay timescale initially indicated that this transient could be a candidate for a pair instability supernova (PISN) explosion. Overall the transient appears quite similar to SN2007bi and the lower redshift object PTF12dam. The extensive data set, from 30 days before peak to 230 days after, allows a detailed and quantitative comparison with published models of PISN explosions. We find that the PS1-11ap data do no...

  4. Propagation of Superluminous L-O Mode Waves During Geomagnetic Activities

    Institute of Scientific and Technical Information of China (English)

    XIAO Fuliang; CHEN Lunjin; ZHENG Huinan; ZHOU Qinghua; WANG Shui

    2008-01-01

    The effect of the azimuthal angle ψ of the wave vector k on the propagation characteristics of the superluminous L-O mode waves (together with a case of the R-X mode) during different geomagnetic activities using a three-dimensional (3D) ray-tracing method is investigated.This work is primarily an extension of our previous two-dimensional study in which the wave azimuthal angle was not considered.We present numerical simulations for this mode which is generated in the source cavity along a 70° night geomagnetic field line at the specific altitude of 1.5RE (where RE is the Earth's radius).It is found that,as in the two-dimensional case,the trajectory of L-O mode starting in the source meridian plane (or the wave azimuthal angle ψ=180°) can reach the lowest latitude;whereas it basically stays at relatively higher latitudes starting off the source meridian plane (or ψ≠180°).The results reveal that under appropriate conditions,the superluminous L-O mode waves may exist in the radiation belts of the Earth,but this remains to be supplemented by observational data.

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

    CERN Document Server

    Nicholl, M; 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

    2013-01-01

    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 65-30 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 56Ni are synthesized; this isotope decays to 56Fe via 56Co, 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...

  6. The evolution of superluminous supernova LSQ14mo and its interacting host galaxy system

    CERN Document Server

    Chen, T -W; Smartt, S J; Mazzali, P A; Yates, R M; Moriya, T J; Inserra, C; Langer, N; Kruehler, T; Pan, Y -C; Kotak, R; Galbany, L; Schady, P; Wiseman, P; Greiner, J; Schulze, S; Man, A W S; Jerkstrand, A; Smith, K W; Dennefeld, M; Baltay, C; Bolmer, J; Kankare, E; Knust, F; Maguire, K; Rabinowitz, D; Rostami, S; Sullivan, M; Young, D R

    2016-01-01

    We present and analyse an extensive dataset of the superluminous supernova LSQ14mo (z = 0.256), consisting of a multi-colour lightcurve from -30 d to +70 d in the rest-frame and a series of 6 spectra from PESSTO covering -7 d to +50 d. This is among the densest spectroscopic coverage, and best-constrained rising lightcurve, for a fast-declining hydrogen-poor superluminous supernova. The bolometric lightcurve can be reproduced with a millisecond magnetar model with ~ 4 M_sol ejecta mass, and the temperature and velocity evolution is also suggestive of a magnetar as the power source. Spectral modelling indicates that the SN ejected ~ 6 M_sol of CO-rich material with a kinetic energy of ~ 7 x 10^51 erg, and suggests a partially thermalised additional source of luminosity between -2 d and +22 d. This may be due to interaction with a shell of material originating from pre-explosion mass loss. We further present a detailed analysis of the host galaxy system of LSQ14mo. PESSTO and GROND imaging show three spatially ...

  7. Predictions for signatures of the quark-nova in superluminous supernovae

    CERN Document Server

    Ouyed, Rachid; Jaikumar, Prashanth

    2009-01-01

    [Abridged] Superluminous Supernovae (SN2006gy, SN2005gj, SN2005ap, SN2008fz, SN2003ma) have been a challenge to explain by standard models. We present an alternative scenario involving a quark-nova (QN), an explosive transition of the newly born neutron star to a quark star in which a second explosion (delayed) occurs inside the already expanding ejecta of a normal SN. The reheated SN ejecta can radiate at higher levels for longer periods of time primarily due to reduced adiabatic expansion losses, unlike the standard SN case. Our model is successfully applied to SN2006gy, SN2005gj, SN2005ap, SN2008fz, SN2003ma with encouraging fits to the lightcurves. There are four predictions in our model: (i) superluminous SNe optical lightcurves should show a double-hump with the SN hump at weaker magnitudes occurring days to weeks before the QN; (ii) Two shock breakouts should be observed vis-a-vis one for a normal SN. Depending on the time delay, this would manifest as two distinct spikes in the X-ray region or a broad...

  8. ASASSN-15lh: A Superluminous Ultraviolet Rebrightening Observed by Swift and Hubble

    CERN Document Server

    Brown, Peter J; Cooke, Jeff; Olaes, Melanie; Quimby, Robert M; Baade, Dietrich; Gehrels, Neil; Hoeflich, Peter; Maund, Justyn; Mould, Jeremy; Patat, Ferdinando; Wang, Lifan; Wheeler, J Craig

    2016-01-01

    We present and discuss ultraviolet (UV) and optical photometry from the Ultraviolet/Optical Telescope (UVOT) and X-ray limits from the X-Ray Telescope on Swift and imaging polarimetry and UV/optical spectroscopy with the Hubble Space Telescope (HST) of ASASSN-15lh. It has been classified as a hydrogen-poor superluminous supernova (SLSN I) more luminous than any other supernova observed. From the polarimetry we determine that the explosion was only mildly asymmetric. We find the flux of ASASSN-15lh to increase strongly into the UV, with a UV luminosity a hundred times greater than the hydrogen-rich, UV-bright SLSN II SN~2008es. A late rebrightening -- most prominent at shorter wavelengths -- is seen about two months after the peak brightness, which by itself is as bright as a superluminous supernova. ASASSN-15lh is not detected in the X-rays in individual observations or when the data are summed into two separate bins for the early phase and the rebrightening. The HST UV spectrum during the rebrightening is do...

  9. Two superluminous supernovae from the early universe discovered by the Supernova Legacy Survey

    CERN Document Server

    Howell, D A; Lidman, C; Sullivan, M; Conley, A; Astier, P; Carlberg, C Balland R G; Fouchez, D; Guy, J; Hardin, D; Pain, R; Palanque-Delabrouille, N; Perrett, K; Pritchet, C J; Regnault, N; Rich, J; Ruhlmann-Kleider, V

    2013-01-01

    We present spectra and lightcurves of SNLS 06D4eu and SNLS 07D2bv, two hydrogen-free superluminous supernovae discovered by the Supernova Legacy Survey. At z = 1.588, SNLS 06D4eu is the highest redshift superluminous SN with a spectrum, at M_U = -22.7 is one of the most luminous SNe ever observed, and gives a rare glimpse into the restframe ultraviolet where these supernovae put out their peak energy. SNLS 07D2bv does not have a host galaxy redshift, but based on the supernova spectrum, we estimate it to be at z ~ 1.5. Both supernovae have similar observer-frame griz lightcurves, which map to restframe lightcurves in the U-band and UV, rising in ~ 20 restframe days or longer, and declining over a similar timescale. The lightcurves peak in the shortest wavelengths first, consistent with an expanding blackbody starting near 15,000 K and steadily declining in temperature. We compare the spectra to theoretical models, and identify lines of C II, C III, Fe III, and Mg II in the spectrum of SNLS 06D4eu and SCP 06F6...

  10. 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.

  11. Superluminal Radio Features in the M87 Jet and the Site of Flaring TeV Gamma-ray Emission

    CERN Document Server

    Cheung, C C; Stawarz, L

    2007-01-01

    Superluminal motion is a common feature of radio jets in powerful gamma-ray emitting active galactic nuclei. Conventionally, the variable emission is assumed to originate near the central supermassive black-hole where the jet is launched on parsec scales or smaller. Here, we report the discovery of superluminal radio features within a distinct flaring X-ray emitting region in the jet of the nearby radio galaxy M87 with the Very Long Baseline Array. This shows that these two phenomenological hallmarks -- superluminal motion and high-energy variability -- are associated, and we place this activity much further (>=120 pc) from the ``central engine'' in M87 than previously thought in relativistic jet sources. We argue that the recent excess very high-energy TeV emission from M87 reported by the H.E.S.S. experiment originates from this variable superluminal structure, thus providing crucial insight into the production region of gamma-ray emission in more distant blazars.

  12. Speeding Up

    Institute of Scientific and Technical Information of China (English)

    YU SHUJUN

    2010-01-01

    In the wake of the global financial crisis, China has amazed the world with the speed of its economic recovery. But what has been even more surprising is the speed of its railway evolution. The unveiling of the 1,069-km Wuhan-Guangzhou High-speed Railway on December 26, 2009 pushed China's high-speed rail sys-tem-the total mileage, the average speed and the technology-to rank first in the world almost overnight.

  13. On Weak Regular *-semigroups

    Institute of Scientific and Technical Information of China (English)

    Yong Hua LI; Hai Bin KAN; Bing Jun YU

    2004-01-01

    In this paper, a special kind of partial algebras called projective partial groupoids is defined.It is proved that the inverse image of all projections of a fundamental weak regular *-semigroup under the homomorphism induced by the maximum idempotent-separating congruence of a weak regular *-semigroup has a projective partial groupoid structure. Moreover, a weak regular *-product which connects a fundamental weak regular *-semigroup with corresponding projective partial groupoid is defined and characterized. It is finally proved that every weak regular *-product is in fact a weak regular *-semigroup and any weak regular *-semigroup is constructed in this way.

  14. 3D Simulations of Relativistic Precessing Jets Probing the Structure of Superluminal Sources

    CERN Document Server

    Aloy, M A; Gómez, J L; Agudo, I; Müller, E; Ibanyez, J M; Aloy, Miguel Angel; Marti, Jose Maria; Gomez, Jose Luis; Agudo, Ivan; Mueller, Ewald; Ibanyez, Jose Maria

    2003-01-01

    We present the results of a three-dimensional, relativistic, hydrodynamic simulation of a precessing jet into which a compact blob of matter is injected. A comparison of synthetic radio maps computed from the hydrodynamic model, taking into account the appropriate light travel time delays, with those obtained from observations of actual superluminal sources shows that the variability of the jet emission is the result of a complex combination of phase motions, viewing angle selection effects, and non-linear interactions between perturbations and the underlying jet and/or the external medium. These results question the hydrodynamic properties inferred from observed apparent motions and radio structures, and reveal that shock-in-jet models may be overly simplistic.

  15. Superluminal Propagation Caused by Radiative Corrections in a Uniform Electromagnetic Field

    CERN Document Server

    Shiba, Noburo

    2012-01-01

    We consider the effect of radiative corrections on the maximum velocity of propagation of neutral scalar fields in a uniform electromagnetic field. The propagator of neutral scalar fields interacting with charged fields depends on the electromagnetic field through charged particle loops. The kinetic terms of the scalar fields are corrected and the maximum velocity of the scalar particle becomes greater or less than unity. We show that the maximum velocity becomes greater than unity in a simple example, a neutral scalar field coupled with two charged Dirac fields by Yukawa interaction. The maximum velocity depends on the frame of reference and causality is not violated. We discuss the possibility of this superluminal propagation in the Standard Model.

  16. Superluminal Neutrinos and a Curious Phenomenon in the Relativistic Quantum Hamilton-Jacobi Equation

    CERN Document Server

    Matone, Marco

    2011-01-01

    OPERA's results, if confirmed, pose the question of superluminal neutrinos. We investigate the kinematics defined by the quantum version of the relativistic Hamilton-Jacobi equation, i.e. E^2=p^2c^2+m^2c^4+2mQc^2, with Q the quantum potential of the free particle. The key point is that the quantum version of the Hamilton-Jacobi equation is a third-order differential equation, so that it has integration constants which are missing in the Schr\\"odinger and Klein-Gordon equations. In particular, a non-vanishing imaginary part of an integration constant leads to a quantum correction to the expression of the velocity which is curiously in agreement with OPERA's results.

  17. `Superluminal' Photon Propagation in QED in Curved Spacetime is Dispersive and Causal

    CERN Document Server

    Hollowood, Timothy J

    2010-01-01

    It is now well-known that vacuum polarisation in QED can lead to superluminal low-frequency phase velocities for photons propagating in curved spacetimes. In a series of papers, we have shown that this quantum phenomenon is dispersive and have calculated the full frequency dependence of the refractive index, explaining in detail how causality is preserved and various familiar results from quantum field theory such as the Kramers-Kronig dispersion relation and the optical theorem are realised in curved spacetime. These results have been criticised in a recent paper by Akhoury and Dolgov arXiv:1003.6110 [hep-th], who assert that photon propagation is neither dispersive nor necessarily causal. In this note, we point out a series of errors in their work which have led to this false conclusion.

  18. Can pair-instability supernova models match the observations of superluminous supernovae?

    CERN Document Server

    Kozyreva, Alexandra

    2015-01-01

    An increasing number of so-called superluminous supernovae (SLSNe) are discovered. It is believed that at least some of them with slowly fading light curves originate in stellar explosions induced by the pair instability mechanism. Recent stellar evolution models naturally predict pair instability supernovae (PISNe) from very massive stars at wide range of metallicities (up to Z=0.006, Yusof et al. 2013). In the scope of this study we analyse whether PISN models can match the observational properties of SLSNe with various light curve shapes. Specifically, we explore the influence of different degrees of macroscopic chemical mixing in PISN explosive products on the resulting observational properties. We artificially apply mixing to the 250 Msun PISN evolutionary model from Kozyreva et al. (2014) and explore its supernova evolution with the one-dimensional radiation hydrodynamics code STELLA. The greatest success in matching SLSN observations is achieved in the case of an extreme macroscopic mixing, where all r...

  19. 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.

  20. COMMENT: Evaluation of a proposed test of the weak equivalence principle using Earth-orbiting bodies in high-speed co-rotation: re-establishing the physical bases

    Science.gov (United States)

    Nobili, A. M.; Bramanti, D.; Polacco, E.; Catastini, G.; Anselmi, A.; Portigliotti, S.; Lenti, A.; di Giamberardino, P.; Monaco, S.; Ronchini, R.

    1999-04-01

    Test masses coupled by weak mechanical suspensions are sensitive to differential forces such as the force due to a possible violation of the equivalence principle (EP). If in addition they are put in rapid rotation, the differential signal is modulated at high frequency, which is beneficial for noise reduction. Galileo Galilei (GG) is a proposed space experiment for testing the equivalence principle to 1 part in 0264-9381/16/4/032/img8 based on these concepts. A recent paper by Jafry and Weinberger (1998 Class. Quantum Grav. 15 481-500) claims that GG can only reach 0264-9381/16/4/032/img9. We show that the analysis of this paper is flawed (by several orders of magnitude) because of two misconceptions: one on the physical nature of mechanical damping and the other on active control methods for the stabilization of spinning bodies.

  1. SN 2012au: A GOLDEN LINK BETWEEN SUPERLUMINOUS SUPERNOVAE AND THEIR LOWER-LUMINOSITY COUNTERPARTS

    Energy Technology Data Exchange (ETDEWEB)

    Milisavljevic, Dan; Soderberg, Alicia M.; Margutti, Raffaella; Drout, Maria R.; Marion, G. Howie; Sanders, Nathan E.; Lunnan, Ragnhild; Chornock, Ryan; Berger, Edo; Foley, Ryan J.; Challis, Pete; Kirshner, Robert P.; Dittmann, Jason; Bieryla, Allyson; Kamble, Atish; Chakraborti, Sayan [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hsiao, Eric Y. [Carnegie Observatories, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile); Fesen, Robert A.; Parrent, Jerod T. [6127 Wilder Lab, Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States); Levesque, Emily M., E-mail: dmilisav@cfa.harvard.edu [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); and others

    2013-06-20

    We present optical and near-infrared observations of SN 2012au, a slow-evolving supernova (SN) with properties that suggest a link between subsets of energetic and H-poor SNe and superluminous SNe. SN 2012au exhibited conspicuous Type-Ib-like He I lines and other absorption features at velocities reaching Almost-Equal-To 2 Multiplication-Sign 10{sup 4} km s{sup -1} in its early spectra, and a broad light curve that peaked at M{sub B} = -18.1 mag. Models of these data indicate a large explosion kinetic energy of {approx}10{sup 52} erg and {sup 56}Ni mass ejection of M{sub Ni} Almost-Equal-To 0.3 M{sub Sun} on par with SN 1998bw. SN 2012au's spectra almost one year after explosion show a blend of persistent Fe II P-Cyg absorptions and nebular emissions originating from two distinct velocity regions. These late-time emissions include strong [Fe II], [Ca II], [O I], Mg I], and Na I lines at velocities {approx}> 4500 km s{sup -1}, as well as O I and Mg I lines at noticeably smaller velocities {approx}< 2000 km s{sup -1}. Many of the late-time properties of SN 2012au are similar to the slow-evolving hypernovae SN 1997dq and SN 1997ef, and the superluminous SN 2007bi. Our observations suggest that a single explosion mechanism may unify all of these events that span -21 {approx}< M{sub B} {approx}< -17 mag. The aspherical and possibly jetted explosion was most likely initiated by the core collapse of a massive progenitor star and created substantial high-density, low-velocity Ni-rich material.

  2. Extreme Supernova Models for the Super-luminous Transient ASASSN-15lh

    Science.gov (United States)

    Chatzopoulos, E.; Wheeler, J. C.; Vinko, J.; Nagy, A. P.; Wiggins, B. K.; Even, W. P.

    2016-09-01

    The recent discovery of the unprecedentedly super-luminous transient ASASSN-15lh (or SN 2015L) with its UV-bright secondary peak challenges all the power-input models that have been proposed for super-luminous supernovae. Here we examine some of the few viable interpretations of ASASSN-15lh in the context of a stellar explosion, involving combinations of one or more power inputs. We model the light curve of ASASSN-15lh with a hybrid model that includes contributions from magnetar spin-down energy and hydrogen-poor circumstellar interaction. We also investigate models of pure circumstellar interaction with a massive hydrogen-deficient shell and discuss the lack of interaction features in the observed spectra. We find that, as a supernova, ASASSN-15lh can be best modeled by the energetic core-collapse of an ˜40 M ⊙ star interacting with a hydrogen-poor shell of ˜20 M ⊙. The circumstellar shell and progenitor mass are consistent with a rapidly rotating pulsational pair-instability supernova progenitor as required for strong interaction following the final supernova explosion. Additional energy injection by a magnetar with an initial period of 1-2 ms and magnetic field of 0.1-1 × 1014 G may supply the excess luminosity required to overcome the deficit in single-component models, but this requires more fine-tuning and extreme parameters for the magnetar, as well as the assumption of efficient conversion of magnetar energy into radiation. We thus favor a single-input model where the reverse shock formed in a strong SN ejecta-circumstellar matter interaction following a very powerful core-collapse SN explosion can supply the luminosity needed to reproduce the late-time UV-bright plateau.

  3. A plausible (overlooked) super-luminous supernova in the Sloan digital sky survey stripe 82 data

    Energy Technology Data Exchange (ETDEWEB)

    Kostrzewa-Rutkowska, Zuzanna; Kozłowski, Szymon; Wyrzykowski, Łukasz [Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa (Poland); Djorgovski, S. George; Mahabal, Ashish A. [California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125 (United States); Glikman, Eilat [Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208121, New Haven, CT 06520-8121 (United States); Koposov, Sergey, E-mail: zkostrzewa@astrouw.edu.pl, E-mail: simkoz@astrouw.edu.pl, E-mail: wyrzykow@astrouw.edu.pl [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2013-12-01

    We present the discovery of a plausible super-luminous supernova (SLSN), found in the archival data of Sloan Digital Sky Survey (SDSS) Stripe 82, called PSN 000123+000504. The supernova (SN) peaked at m {sub g} < 19.4 mag in the second half of 2005 September, but was missed by the real-time SN hunt. The observed part of the light curve (17 epochs) showed that the rise to the maximum took over 30 days, while the decline time lasted at least 70 days (observed frame), closely resembling other SLSNe of SN 2007bi type. The spectrum of the host galaxy reveals a redshift of z = 0.281 and the distance modulus of μ = 40.77 mag. Combining this information with the SDSS photometry, we found the host galaxy to be an LMC-like irregular dwarf galaxy with an absolute magnitude of M{sub B} = –18.2 ± 0.2 mag and an oxygen abundance of 12+log [O/H]=8.3±0.2; hence, the SN peaked at M {sub g} < –21.3 mag. Our SLSN follows the relation for the most energetic/super-luminous SNe exploding in low-metallicity environments, but we found no clear evidence for SLSNe to explode in low-luminosity (dwarf) galaxies only. The available information on the PSN 000123+000504 light curve suggests the magnetar-powered model as a likely scenario of this event. This SLSN is a new addition to a quickly growing family of super-luminous SNe.

  4. Cofinitely weak supplemented modules

    OpenAIRE

    Alizade, Rafail; Büyükaşık, Engin

    2003-01-01

    We prove that a module M is cofinitely weak supplemented or briefly cws (i.e., every submodule N of M with M/N finitely generated, has a weak supplement) if and only if every maximal submodule has a weak supplement. If M is a cws-module then every M-generated module is a cws-module. Every module is cws if and only if the ring is semilocal. We study also modules, whose finitely generated submodules have weak supplements.

  5. GENERALIZED WEAK FUNCTIONS

    Institute of Scientific and Technical Information of China (English)

    丁夏畦; 罗佩珠

    2004-01-01

    In this paper the authors introduce some new ideas on generalized numbers and generalized weak functions. They prove that the product of any two weak functions is a generalized weak function. So in particular they solve the problem of the multiplication of two generalized functions.

  6. Gain-assisted superluminal microwave pulse propagation via four-wave mixing in superconducting phase quantum circuits

    CERN Document Server

    Sabegh, Z Amini; Maleki, M A; Mahmoudi, M

    2015-01-01

    We study the propagation and amplification of a microwave field in a four-level cascade quantum system which is realized in a superconducting phase quantum circuit. It is shown 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 this system. 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.

  7. Photon trajectories, anomalous velocities, and weak measurements: A classical interpretation

    CERN Document Server

    Bliokh, Konstantin Y; Nori, Franco

    2013-01-01

    Recently, Kocsis et al. reported the observation of "average trajectories of single photons" in a two-slit interference experiment [Science 332, 1170 (2011)]. This was possible by using the quantum weak-measurements method, which implies averaging over many events, i.e., in fact, a multi-photon limit of classical optics. We give a classical-optics interpretation to this experiment and other related problems. It appears that weak measurements of the local momentum of photons made by Kocsis et al. represent measurements of the Poynting vector in an optical field. We consider both the real and imaginary parts of the local momentum, and show that their measurements have been realized in classical optics using small probe particles. We also examine the appearance of "anomalous" values of the local momentum: either negative (backflow) or exceeding the wavenumber (superluminal propagation). These features appear to be closely related to vortices and evanescent waves. Finally, we revisit a number of older works and f...

  8. Latest Progress on Propagation Characteristics of Superluminous Waves and their Gyroresonance with Energetic Particles%超光速电磁波的传播特性及与高能粒子相互作用研究的新进展

    Institute of Scientific and Technical Information of China (English)

    肖伏良; 何兆国; 陈良旭; 贺艺华; 杨昶

    2011-01-01

    超光速(相速度大于光速)电磁波是广泛存在于空间等离子中的高频电磁波,总结了超光速电磁波的产生机制-回旋微波激射不稳定性,介绍了超光速波在地球磁层中的传播特性,分析了其从高纬极光源区传播到低纬区域的基本原因:磁暴时由于等离子层硕压缩,超光速波传播时不会遇上反射,从而能向下传播.重点介绍了超光速波产生的地球辐射带区域高能电子的随机加速与投掷角扩散过程.发现超光速波能量扩散过程一般大于投掷角扩散过程,在合适的条件下超光速波对高投掷角的高能电子主要起随机加速作用,而对低投掷角的高能电子主要起投掷角扩散作用.这些最新进展有助于进一步了解超光速电磁波的激发与传播特性,以及地球辐射带高能电子的动力学行为.%Superluminous (the phase speed higher than the speed of light) electromagnetic waves are widely present in the space plasma with high frequencies. Here, we briefly introduce their generation mechanism-Cyclotron Maser Instability ( CMI). We present discussion on the propagating characteristics of superluminous waves in the Earth's magnetosphere. During high geomagnetic activity, since the plasmapause position moves inward closer to the Earth, the superluminous waves can propagate from their source cavity downward and even through the equatorial plane due to no reflection. We focus on pitch angle scattering and stochastic acceleration of energetic electrons induced by superluminous waves in the radiation belts. Current works show that energy diffusion resulting from such waves is generally higher than pitch angle scattering. Under appropriate conditions, superluminous waves may contribute to both the stochastic acceleration of electrons with larger pitch angle and the loss process of electrons with smaller pitch angles. These recent progresses provide further understanding of the instability and propagation of

  9. Two superluminous supernovae from the early universe discovered by the supernova legacy survey

    Energy Technology Data Exchange (ETDEWEB)

    Howell, D. A. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States); Kasen, D. [Departments of Physics and Astronomy, University of California, Berkeley, Berkeley, CA 94720-7300 (United States); Lidman, C. [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); Sullivan, M. [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Conley, A. [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309-389 (United States); Astier, P.; Balland, C.; Guy, J.; Hardin, D.; Pain, R.; Regnault, N. [LPNHE, CNRS-IN2P3 and University of Paris VI and VII, F-75005 Paris (France); Carlberg, R. G. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H8 (Canada); Fouchez, D. [CPPM, CNRS-IN2P3 and University Aix Marseille II, Case 907, F-13288 Marseille Cedex 9 (France); Palanque-Delabrouille, N.; Rich, J.; Ruhlmann-Kleider, V. [DSM/IRFU/SPP, CEA-Saclay, F-91191 Gif-sur-Yvette (France); Perrett, K. [DRDC Ottawa, 3701 Carling Avenue, Ottawa, ON K1A 0Z4 (Canada); Pritchet, C. J. [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, BC V8W 3P6 (Canada)

    2013-12-20

    We present spectra and light curves of SNLS 06D4eu and SNLS 07D2bv, two hydrogen-free superluminous supernovae (SNe) discovered by the Supernova Legacy Survey. At z = 1.588, SNLS 06D4eu is the highest redshift superluminous SN with a spectrum, at M{sub U} = –22.7 it is one of the most luminous SNe ever observed, and it gives a rare glimpse into the rest-frame ultraviolet where these SNe put out their peak energy. SNLS 07D2bv does not have a host galaxy redshift, but on the basis of the SN spectrum, we estimate it to be at z ∼ 1.5. Both SNe have similar observer-frame griz light curves, which map to rest-frame light curves in the U band and UV, rising in ∼20 rest-frame days or longer and declining over a similar timescale. The light curves peak in the shortest wavelengths first, consistent with an expanding blackbody starting near 15,000 K and steadily declining in temperature. We compare the spectra with theoretical models, and we identify lines of C II, C III, Fe III, and Mg II in the spectra of SNLS 06D4eu and SCP 06F6 and find that they are consistent with an expanding explosion of only a few solar masses of carbon, oxygen, and other trace metals. Thus, the progenitors appear to be related to those suspected for SNe Ic. A high kinetic energy, 10{sup 52} erg, is also favored. Normal mechanisms of powering core-collapse or thermonuclear SNe do not seem to work for these SNe. We consider models powered by {sup 56}Ni decay and interaction with circumstellar material, but we find that the creation and spin-down of a magnetar with a period of 2 ms, a magnetic field of 2 × 10{sup 14} G, and a 3 M {sub ☉} progenitor provides the best fit to the data.

  10. On Weakly Semicommutative Rings*

    Institute of Scientific and Technical Information of China (English)

    CHEN WEI-XING; CUI SHU-YING

    2011-01-01

    A ring R is said to be weakly scmicommutative if for any a, b ∈ R,ab = 0 implies aRb C_ Nil(R), where Nil(R) is the set of all nilpotcnt elements in R.In this note, we clarify the relationship between weakly semicommutative rings and NI-rings by proving that the notion of a weakly semicommutative ring is a proper generalization of NI-rings. We say that a ring R is weakly 2-primal if the set of nilpotent elements in R coincides with its Levitzki radical, and prove that if R is a weakly 2-primal ring which satisfies oα-condition for an endomorphism α of R (that is, ab = 0 (←→) aα(b) = 0 where a, b ∈ R) then the skew polynomial ring R[π; αα]is a weakly 2-primal ring, and that if R is a ring and I is an ideal of R such that I and R/I are both weakly semicommutative then R is weakly semicommutative.Those extend the main results of Liang et al. 2007 (Taiwanese J. Math., 11(5)(2007),1359-1368) considerably. Moreover, several new results about weakly semicommutative rings and NI-rings are included.

  11. Revealing the binary origin of Type Ic superluminous supernovae through nebular hydrogen emission

    CERN Document Server

    Moriya, Takashi J; Mackey, Jonathan; Chen, Ting-Wan; Langer, Norbert

    2015-01-01

    We propose that nebular Halpha emission as detected in the Type Ic superluminous supernova iPTF13ehe stems from matter which is stripped from a companion star when the supernova ejecta collide with it. The temporal evolution, the line broadening, and the overall blueshift of the emission are consistent with this interpretation. We scale the nebular Halpha luminosity predicted for Type Ia supernovae in single-degenerate systems to derive the stripped mass required to explain the Halpha luminosity of iPTF13ehe. We find a stripped mass of 0.1 - 0.9 solar masses, assuming that the supernova luminosity is powered by radioactivity or magnetar spin down. Because a central heating source is required to excite the Halpha emission, an interaction-powered model is not favored for iPTF13ehe. We derive a companion mass of more than 20 solar masses and a binary separation of less than about 20 companion radii based on the stripping efficiency during the collision, indicating that the supernova progenitor and the companion ...

  12. A plausible (overlooked) super-luminous supernova in the SDSS Stripe 82 data

    CERN Document Server

    Kostrzewa-Rutkowska, Zuzanna; Wyrzykowski, Lukasz; Djorgovski, S George; Glikman, Eilat; Mahabal, Ashish A

    2013-01-01

    We present the discovery of a plausible super-luminous supernova (SLSN), found in the archival data of Sloan Digital Sky Survey (SDSS) Stripe 82, called PSN 000123+000504. The supernova peaked at M_g<-21.3 mag in the second half of September 2005, but was missed by the real-time supernova hunt. The observed part of the light curve (17 epochs) showed that the rise to the maximum took over 30 days, while the decline time lasted at least 70 days (observed frame), closely resembling other SLSNe of SN2007bi type. Spectrum of the host galaxy reveals a redshift of z=0.281 and the distance modulus of \\mu=40.77 mag. Combining this information with the SDSS photometry, we found the host galaxy to be an LMC-like irregular dwarf galaxy with the absolute magnitude of M_B=-18.2+/-0.2 mag and the oxygen abundance of 12+log[O/H]=8.3+/-0.2. Our SLSN follows the relation for the most energetic/super-luminous SNe exploding in low-metallicity environments, but we found no clear evidence for SLSNe to explode in low-luminosity ...

  13. On the early-time excess emission in hydrogen-poor superluminous supernovae

    CERN Document Server

    Vreeswijk, Paul M; 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

    2016-01-01

    We present the light curves of the hydrogen-poor superluminous supernovae (SLSNe-I) PTF12dam and iPTF13dcc, 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 PTF12dam is very similar in duration (~10 days) and brightness relative to the main peak (2-3 mag fainter) compared to those observed in other SLSNe-I, such as SN2006oz, LSQ14bdq and DES14X3taz. In contrast, the long-duration (>30 days) early excess emission in iPTF13dcc, 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 light-curve decline in both SLSNe is suggestively close to that expected from the radioactive decay of $^{56}$Ni and $^{56}$Co, the amount of nickel req...

  14. Superluminal non-ballistic jet swing in the quasar NRAO 150 revealed by mm-VLBI

    CERN Document Server

    Agudo, I; Krichbaum, T P; Marscher, A P; Gonidakis, I; Diamond, P J; Perucho, M; Alef, W; Graham, D A; Witzel, A; Zensus, J A; Bremer, M; Acosta-Pulido, J A; Barrena, R

    2007-01-01

    NRAO 150 -a compact and bright radio to mm source showing core/jet structure- has been recently identified as a quasar at redshift z=1.52 through a near-IR spectral observation. To study the jet kinematics on the smallest accessible scales and to compute the first estimates of its basic physical properties, we have analysed the ultra-high-resolution images from a new monitoring program at 86 GHz and 43 GHz with the GMVA and the VLBA, respectively. An additional archival and calibration VLBA data set, covering from 1997 to 2007, has been used. Our data shows an extreme projected counter-clock-wise jet position angle swing at an angular rate of up to ~11 deg./yr within the inner ~31 pc of the jet, which is associated with a non-ballistic superluminal motion of the jet within this region. The results suggest that the magnetic field could play an important role in the dynamics of the jet in NRAO 150, which is supported by the large values of the magnetic field strength obtained from our first estimates. The extre...

  15. An extreme ultraviolet excess in the superluminous supernova Gaia16apd reveals a powerful central engine

    CERN Document Server

    Nicholl, M; Margutti, R; Blanchard, P K; Milisavljevic, D; Challis, P; Metzger, B D; Chornock, R

    2016-01-01

    Since the discovery of superluminous supernovae (SLSNe) in the last decade, it has been known that these events exhibit bluer spectral energy distributions than other supernova subtypes, with significant output in the ultraviolet. However, the event Gaia16apd seems to outshine even the other SLSNe at rest-frame wavelengths below $\\sim 3000$ \\AA. Yan et al (2016) have recently presented HST UV spectra and attributed the UV flux to low metallicity and hence reduced line blanketing. Here we present UV and optical light curves over a longer baseline in time, revealing a rapid decline at UV wavelengths despite a typical optical evolution. Combining the published UV spectra with our own optical data, we demonstrate that Gaia16apd has a much hotter continuum than virtually any SLSN at maximum light, but it cools rapidly thereafter and is indistinguishable from the others by $\\sim 10$-15 days after peak. Comparing the equivalent widths of UV absorption lines with those of other events, we show that the excess UV cont...

  16. Gaia16apd -- a link between fast-and slowly-declining type I superluminous supernovae

    CERN Document Server

    Kangas, T; Mattila, S; Lundqvist, P; Fraser, M; Hardy, L K; Stritzinger, M D; Cappellaro, E; Elias-Rosa, N; Harmanen, J; Hsiao, E Y; Kankare, E; Nielsen, M B; Reynolds, T M; Rhodes, L; Somero, A; Wyrzykowski, L

    2016-01-01

    We present ultraviolet, optical and infrared photometry and optical spectroscopy of the type Ic superluminous supernova (SLSN) Gaia16apd, covering its evolution from 27 d before the $g$-band peak to the nebular phase, including the latest spectrum ever obtained for a fast-declining type Ic SLSN at 150.9 d. Gaia16apd is one of the closest SLSNe known ($z = 0.102\\pm0.001$), with detailed optical and \\emph{Swift} ultraviolet (UV) band observations covering the peak. Gaia16apd is a spectroscopically typical type Ic SLSN, exhibiting the characteristic blue early spectra with O {\\sc ii} absorption, and reaches a peak $M_{g} = -21.8 \\pm 0.1$ mag. However, photometrically it exhibits an evolution intermediate between the fast- and slowly-declining type Ic SLSNe, with an early evolution closer to the fast-declining events. It is unusually UV-bright even for a SLSN, reaching a non-$K$-corrected $M_{uvm2} \\simeq -23.2$ mag, the only other type Ic SLSN with similar UV brightness being SN 2010gx. This event highlights the...

  17. An Extended Model for Interaction Between Left-hand Superluminous Waves and Magnetospheric Electrons

    Institute of Scientific and Technical Information of China (English)

    Xiao Fuliang; Zheng Huinan; Wang Shui

    2005-01-01

    The left-hand superluminous electromagnetic waves, L-O mode and L-X mode, can be excited and observed in the auroral cavity of the Earth during the magnetic storms. The two modes can propagate into outer radiation zone and encounter enhanced resonant interactions with the trapped energetic electrons over a wide range of magnetosphere. A current first-order resonant model is extended to evaluate the stochastic acceleration of electrons by the L-O mode and L-X mode at the higher-order resonance. Similar to the first-order resonance, L-O mode can produce significant acceleration of electrons at the higher harmonic resonances over a wide range of wave normal angles and spatial regions. However, the higher harmonic resonance's contribution for significant electron acceleration by L-X mode is less than that of the first order resonance,with the requirement of higher minimum energies, e.g., ~1 MeV in the outer radiation belt. This indicates that L-O mode may be one of the efficient mechanisms for the stochastic acceleration of electrons within the outer radiation zone.

  18. H i Absorption in the Steep-Spectrum Superluminal Quasar 3C 216.

    Science.gov (United States)

    Pihlström; Vermeulen; Taylor; Conway

    1999-11-01

    The search for H i absorption in strong compact steep-spectrum sources is a natural way to probe the neutral gas contents in young radio sources. In turn, this may provide information about the evolution of powerful radio sources. The recently improved capabilities of the Westerbork Synthesis Radio Telescope have made it possible to detect a 0.31% (19 mJy) deep neutral atomic hydrogen absorption line associated with the steep-spectrum superluminal quasar 3C 216. The redshift (z=0.67) of the source shifts the frequency of the 21 cm line down to the ultra-high-frequency (UHF) band (850 MHz). The exact location of the H i-absorbing gas remains to be determined by spectral line VLBI observations at 850 MHz. We cannot exclude that the gas might be extended on galactic scales, but we think it is more likely to be located in the central kiloparsec. Constraints from the lack of X-ray absorption probably rule out obscuration of the core region, and we argue that the most plausible site for the H i absorption is in the jet-cloud interaction observed in this source.

  19. Polarimetry of the Superluminous Supernova LSQ14mo: No Evidence for Significant Deviations from Spherical Symmetry

    Science.gov (United States)

    Leloudas, Giorgos; Patat, Ferdinando; Maund, Justyn R.; Hsiao, Eric; Malesani, Daniele; Schulze, Steve; Contreras, Carlos; de Ugarte Postigo, Antonio; Sollerman, Jesper; Stritzinger, Maximilian D.; Taddia, Francesco; Wheeler, J. Craig; Gorosabel, Javier

    2015-12-01

    We present the first polarimetric observations of a Type I superluminous supernova (SLSN). LSQ14mo was observed with VLT/FORS2 at five different epochs in the V band, with the observations starting before maximum light and spanning 26 days in the rest frame (z = 0.256). During this period, we do not detect any statistically significant evolution (\\lt 2σ ) in the Stokes parameters. The average values we obtain, corrected for interstellar polarization in the Galaxy, are Q = -0.01% (±0.15%) and U = -0.50% (±0.14%). This low polarization can be entirely due to interstellar polarization in the SN host galaxy. We conclude that, at least during the period of observations and at the optical depths probed, the photosphere of LSQ14mo does not present significant asymmetries, unlike most lower-luminosity hydrogen-poor SNe Ib/c. Alternatively, it is possible that we may have observed LSQ14mo from a special viewing angle. Supporting spectroscopy and photometry confirm that LSQ14mo is a typical SLSN I. Further studies of the polarization of Type I SLSNe are required to determine whether the low levels of polarization are a characteristic of the entire class and to also study the implications for the proposed explosion models.

  20. Host-Galaxy Properties of 32 Low-Redshift Superluminous Supernovae from the Palomar Transient Factory

    CERN Document Server

    Perley, Daniel A; Yan, Lin; Vreeswijk, Paul; De Cia, Annalisa; Lunnan, Ragnhild; Gal-Yam, Avishay; Yaron, Ofer; Filippenko, Alexei V; Graham, Melissa L; Nugent, Peter E

    2016-01-01

    We present ultraviolet through near-infrared photometry and spectroscopy of the host galaxies of all superluminous supernovae (SLSNe) discovered by the Palomar Transient Factory prior to 2013, and derive measurements of their luminosities, star-formation rates, stellar masses, and gas-phase metallicities. We find that Type I (hydrogen-poor) SLSNe are found almost exclusively in low-mass (M 0.5 Z_sun. Extremely low metallicities are not required, and indeed provide no further increase in the relative SLSN rate. Several SLSN-I hosts are undergoing vigorous starbursts, but this may simply be a side effect of metallicity dependence: dwarf galaxies tend to have bursty star-formation histories. Type-II (hydrogen-rich) SLSNe are found over the entire range of galaxy masses and metallicities, and their integrated properties do not suggest a strong preference for (or against) low-mass/low-metallicity galaxies. Two hosts exhibit unusual properties: PTF 10uhf is a Type I SLSN in a massive, luminous infrared galaxy at re...

  1. SN 2012aa - a transient between Type Ibc core-collapse and superluminous supernovae

    CERN Document Server

    Roy, R; Silverman, J M; Pastorello, A; Fransson, C; Drake, A; Taddia, F; Fremling, C; Kankare, E; Kumar, B; Cappellaro, E; Bose, S; Benetti, S; Filippenko, A V; Valenti, S; Nyholm, A; Ergon, M; Sutaria, F; Kumar, B; Pandey, S B; Nicholl, M; Garcia-Alvarez, D; Tomasella, L; Karamehmetoglu, E; Migotto, K

    2016-01-01

    Context: Research on supernovae (SNe) over the past decade has confirmed that there is a distinct class of events which are much more luminous (by $\\sim2$ mag) than canonical core-collapse SNe (CCSNe). These events with visual peak magnitudes $\\lesssim-21$ are called superluminous SNe (SLSNe). Aims: There are a few intermediate events which have luminosities between these two classes. Here we study one such object, SN 2012aa. Methods: The optical photometric and spectroscopic follow-up observations of the event were conducted over a time span of about 120 days. Results: With V_abs at peak ~-20 mag, the SN is an intermediate-luminosity transient between regular SNe Ibc and SLSNe. It also exhibits an unusual secondary bump after the maximum in its light curve. We interpret this as a manifestation of SN-shock interaction with the CSM. If we would assume a $^{56}$Ni-powered ejecta, the bolometric light curve requires roughly 1.3 M_sun of $^{56}$Ni and an ejected mass of ~14 M_sun. This would also imply a high kin...

  2. Polarimetry of the superluminous supernova LSQ14mo: no evidence for significant deviations from spherical symmetry

    CERN Document Server

    Leloudas, Giorgos; Maund, Justyn R; Hsiao, Eric; Malesani, Daniele; Schulze, Steve; Contreras, Carlos; Postigo, Antonio de Ugarte; Sollerman, Jesper; Stritzinger, Maximilian D; Taddia, Francesco; Wheeler, J Craig; Gorosabel, Javier

    2015-01-01

    We present the first polarimetric observations of a Type I superluminous supernova (SLSN). LSQ14mo was observed with VLT/FORS2 at 5 different epochs in the V band, observations starting before maximum light and spanning 26 days in the rest-frame (z=0.256). During this period, we do not detect any statistically significant evolution (< 2$\\sigma$) in the Stokes parameters. The average values we obtain, corrected for interstellar polarisation in the Galaxy, are Q = -0.01% ($\\pm$ 0.15%) and U = - 0.50% ($\\pm$ 0.14%). This low polarisation can be entirely due to interstellar polarisation in the SN host galaxy. We conclude that, at least during the period of observations and at the optical depths probed, the photosphere of LSQ14mo does not present significant asymmetries, unlike most lower-luminosity hydrogen-poor SNe Ib/c. Alternatively, it is possible that we may have observed LSQ14mo from a special viewing angle. Supporting spectroscopy and photometry confirm that LSQ14mo is a typical SLSN I. Further studies ...

  3. 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.

  4. 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).

  5. Constraining the ellipticity of strongly magnetized neutron stars powering superluminous supernovae

    Science.gov (United States)

    Moriya, Takashi J.; Tauris, Thomas M.

    2016-07-01

    Superluminous supernovae (SLSNe) have been suggested to be powered by strongly magnetized, rapidly rotating neutron stars which are often called magnetars. In this process, rotational energy of the magnetar is radiated via magnetic dipole radiation and heats the supernova ejecta. However, if magnetars are highly distorted in their geometric shape, rotational energy is mainly lost as gravitational wave radiation and thus such magnetars cannot power SLSNe. By simply comparing electromagnetic and gravitational wave emission time-scales, we constrain upper limits to the ellipticity of magnetars by assuming that they power the observed SLSNe. We find that their ellipticity typically needs to be less than about a few 10-3. This indicates that the toroidal magnetic field strengths in these magnetars are typically less than a few 1016 G so that their distortions remain small. Because light-curve modelling of SLSNe shows that their dipole magnetic field strengths are of the order of 1014 G, the ratio of poloidal to toroidal magnetic field strengths is found to be larger than ˜0.01 in magnetars powering SLSNe.

  6. Constraining the ellipticity of strongly-magnetized neutron stars powering superluminous supernovae

    CERN Document Server

    Moriya, Takashi J

    2016-01-01

    Superluminous supernovae (SLSNe) have been suggested to be powered by strongly-magnetized, rapidly-rotating neutron stars which are often called magnetars. In this process, rotational energy of the magnetar is radiated via magnetic dipole radiation and heats the supernova ejecta. However, if magnetars are highly distorted in their geometric shape, rotational energy is mainly lost as gravitational wave radiation and thus such magnetars cannot power SLSNe. By simply comparing electromagnetic and gravitational wave emission timescales, we constrain upper limits to the ellipticity of magnetars by assuming that they power the observed SLSNe. We find that their ellipticity typically needs to be less than about a few 1e-3. This indicates that the toroidal magnetic field strengths in these magnetars are typically less than a few 1e16 G so that their distortions remain small. Because light-curve modeling of SLSNe shows that their dipole magnetic field strengths are of the order of 1e14 G, the ratio of poloidal to toro...

  7. A Triple-energy-source Model for Superluminous Supernova iPTF13ehe

    Science.gov (United States)

    Wang, S. Q.; Liu, L. D.; Dai, Z. G.; Wang, L. J.; Wu, X. F.

    2016-09-01

    Almost all superluminous supernovae (SLSNe) whose peak magnitudes are ≲ -21 mag can be explained by the 56Ni-powered model, the magnetar-powered (highly magnetized pulsar) model, or the ejecta-circumstellar medium (CSM) interaction model. Recently, iPTF13ehe challenged these energy-source models, because the spectral analysis shows that ˜ 2.5{M}⊙ of 56Ni have been synthesized, but are inadequate to power the peak bolometric emission of iPTF13ehe, while the rebrightening of the late-time light curve (LC) and the Hα emission lines indicate that the ejecta-CSM interaction must play a key role in powering the late-time LC. Here we propose a triple-energy-source model, in which a magnetar together with some amount (≲ 2.5{M}⊙ ) of 56Ni may power the early LC of iPTF13ehe, while the late-time rebrightening can be quantitatively explained by an ejecta-CSM interaction. Furthermore, we suggest that iPTF13ehe is a genuine core-collapse supernova rather than a pulsational pair-instability supernova candidate. Further studies on similar SLSNe in the future would eventually shed light on their explosion and energy-source mechanisms.

  8. DES13S2cmm: The First Superluminous Supernova from the Dark Energy Survey

    CERN Document Server

    Papadopoulos, A; Sullivan, M; Nichol, R C; Barbary, K; Biswas, R; Brown, P J; Covarrubias, R A; Finley, D A; Fischer, J A; Foley, R F; Goldstein, D; Gupta, R R; Kessler, R; Kovacs, E; Kuhlmann, S E; Lidman, C; March, M; Nugent, P E; Sako, M; Smith, R C; Spinka, H; Wester, W; Abbott, T M C; Abdalla, F; Allam, S S; Banerji, M; Bernstein, J P; Bernstein, R A; Carnero, A; da Costa, L N; DePoy, D L; Desai, S; Diehl, H T; Eifler, T; Evrard, A E; Flaugher, B; Frieman, J A; Gerdes, D; Gruen, D; Honscheid, K; James, D; Kuehn, K; Kuropatkin, N; Lahav, O; Maia, M A G; Makler, M; Marshall, J L; Merritt, K W; Miller, C J; Miquel, R; Ogando, R; Plazas, A A; Roe, N A; Romer, A K; Rykoff, E; Sanchez, E; Santiago, B X; Scarpine, V; Schubnell, M; Sevilla, I; Santos, M Soares-; Suchyta, E; Swanson, M; Tarle, G; Thaler, J; Tucker, D L; Wechsler, R H; Zuntz, J

    2015-01-01

    We present DES13S2cmm, the first spectroscopically-confirmed superluminous supernova (SLSN) from the Dark Energy Survey (DES). We briefly discuss the data and search algorithm used to find this event in the first year of DES operations, and outline the spectroscopic data obtained from the European Southern Observatory (ESO) Very Large Telescope to confirm its redshift (z = 0.663 +/- 0.001 based on the host-galaxy emission lines) and likely spectral type (type I). Using this redshift, we find M_U_peak = -21.05 +0.10 -0.09 for the peak, rest-frame U-band absolute magnitude, and find DES13S2cmm to be located in a faint, low metallicity (sub-solar), low stellar-mass host galaxy (log(M/M_sun) = 9.3 +/- 0.3); consistent with what is seen for other SLSNe-I. We compare the bolometric light curve of DES13S2cmm to fourteen similarly well-observed SLSNe-I in the literature and find it possesses one of the slowest declining tails (beyond +30 days rest frame past peak), and is the faintest at peak. Moreover, we find the b...

  9. Idiopathic isolated orbicularis weakness

    Science.gov (United States)

    MacVie, O P; Majid, M A; Husssin, H M; Ung, T; Manners, R M; Ormerod, I; Pawade, J; Harrad, R A

    2012-01-01

    Purpose Orbicularis weakness is commonly associated with seventh nerve palsy or neuromuscular and myopathic conditions such as myotonic dystrophy and myasethenia gravis. We report four cases of idiopathic isolated orbicularis weakness. Methods All four cases were female and the presenting symptoms of ocular irritation and epiphora had been present for over 7 years in three patients. All patients had lagophthalmos and three had ectropion. Three patients underwent full investigations which excluded known causes of orbicularis weakness. Two patients underwent oribularis oculi muscle biopsy and histological confirmation of orbicularis atrophy. Results All patients underwent surgery to specifically address the orbicularis weakness with satisfactory outcomes and alleviation of symptoms in all cases. Isolated orbicularis weakness may be a relatively common entity that is frequently overlooked. Conclusion Early recognition of this condition may lead to better management and prevent patients undergoing unnecessary surgical procedures. PMID:22322997

  10. Weak layer fracture: facets and depth hoar

    Directory of Open Access Journals (Sweden)

    I. Reiweger

    2013-05-01

    Full Text Available Understanding the fracture behavior of weak snow layers is essential for modeling and predicting dry-snow slab avalanches. We therefore performed laboratory experiments with snow samples containing a weak layer consisting of either faceted crystals or depth hoar. During these experiments the samples were loaded with different loading rates and at various tilt angles until fracture. The strength of the samples decreased with increasing loading rate and increasing tilt angle. Additionally, we took pictures of the side of the samples with a high-speed video camera and calculated the displacement using a particle image velocimetry (PIV algorithm. The fracture process within the weak layer could thus be studied in detail. We found a fracture in shear immediately followed by a collapse of the weak layer.

  11. Breaking the light speed barrier

    CERN Document Server

    Chashchina, O I

    2011-01-01

    As it is well known, classical special relativity allows the existence of three different kinds of particles: bradyons, luxons and tachyons. Bradyons have non-zero mass and hence always travel slower than light. Luxons are particles with zero mass, like the photon, and they always travel with invariant velocity. Tachyons are hypothetical superluminal particles that always move faster than light. The existence of bradyons and luxons is firmly established, while the tachyons were never reliably observed. In quantum field theory, the appearance of tachyonic degrees of freedom indicates vacuum instability rather than a real existence of the faster-than-light particles. However, recent controversial claims of the OPERA experiment about superluminal neutrinos triggered a renewed interest in superluminal particles. Driven by a striking analogy of the old Frenkel-Kontorova model of a dislocation dynamics to the theory of relativity, we conjecture in this note a remarkable possibility of existence of the fourth type o...

  12. Weak decays. [Lectures, phenomenology

    Energy Technology Data Exchange (ETDEWEB)

    Wojcicki, S.

    1978-11-01

    Lectures are given on weak decays from a phenomenological point of view, emphasizing new results and ideas and the relation of recent results to the new standard theoretical model. The general framework within which the weak decay is viewed and relevant fundamental questions, weak decays of noncharmed hadrons, decays of muons and the tau, and the decays of charmed particles are covered. Limitation is made to the discussion of those topics that either have received recent experimental attention or are relevant to the new physics. (JFP) 178 references

  13. Weakly asymptotically hyperbolic manifolds

    CERN Document Server

    Allen, Paul T; Lee, John M; Allen, Iva Stavrov

    2015-01-01

    We introduce a class of "weakly asymptotically hyperbolic" geometries whose sectional curvatures tend to $-1$ and are $C^0$, but are not necessarily $C^1$, conformally compact. We subsequently investigate the rate at which curvature invariants decay at infinity, identifying a conformally invariant tensor which serves as an obstruction to "higher order decay" of the Riemann curvature operator. Finally, we establish Fredholm results for geometric elliptic operators, extending the work of Rafe Mazzeo and John M. Lee to this setting. As an application, we show that any weakly asymptotically hyperbolic metric is conformally related to a weakly asymptotically hyperbolic metric of constant negative curvature.

  14. 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).

  15. Strange Weak Values

    CERN Document Server

    Hosoya, Akio

    2010-01-01

    We develop a formal theory of the weak values with emphasis on the consistency conditions and a probabilistic interpretation in the counter-factual processes. We present the condition for the choice of the post-selected state to give a negative weak value of a given projection operator and strange values of an observable in general. The general framework is applied to Hardy's paradox and the spin $1/2$ system to explicitly address the issues of counter-factuality and strange weak values. The counter-factual arguments which characterize the paradox specifies the pre-selected state and a complete set of the post-selected states clarifies how the strange weak values emerge.

  16. Some Viable Techniques for Assessing and Counselling Cognitive Processing Weakness

    Science.gov (United States)

    Haruna, Abubakar Sadiq

    2016-01-01

    Cognitive Processing weakness (CPW) is a psychological problem that impedes students' ability to learn effectively in a normal school setting. Such weakness may include; auditory, visual, conceptual, sequential, speed and attention processing. This paper therefore examines the basic assessment or diagnostic approaches such as Diagnosis by…

  17. Beyond the speed of light on Finsler spacetimes

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, Christian, E-mail: christian.pfeifer@desy.de [II. Institut fuer Theoretische Physik und Zentrum fuer Mathematische Physik, Universtitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Wohlfarth, Mattias N.R., E-mail: mattias.wohlfarth@desy.de [II. Institut fuer Theoretische Physik und Zentrum fuer Mathematische Physik, Universtitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

    2012-06-06

    As a prototypical massive field theory we study the scalar field on the recently introduced Finsler spacetimes. We show that particle excitations exist that propagate faster than the speed of light recognized as the boundary velocity of observers. This effect appears already in Finsler spacetime geometries with very small departures from Lorentzian metric geometry. It switches on for a sufficiently large ratio of the particle four-momentum and mass, and is the consequence of a modified version of the Coleman-Glashow velocity dispersion relation. The momentum dispersion relation on Finsler spacetimes is shown to be the same as on metric spacetimes, which differs from many quantum gravity models. If similar relations resulted for fermions on Finsler spacetimes, these generalized geometries could explain the potential observation of superluminal neutrinos claimed by the Opera Collaboration.

  18. Beyond the speed of light on Finsler spacetimes

    Science.gov (United States)

    Pfeifer, Christian; Wohlfarth, Mattias N. R.

    2012-06-01

    As a prototypical massive field theory we study the scalar field on the recently introduced Finsler spacetimes. We show that particle excitations exist that propagate faster than the speed of light recognized as the boundary velocity of observers. This effect appears already in Finsler spacetime geometries with very small departures from Lorentzian metric geometry. It switches on for a sufficiently large ratio of the particle four-momentum and mass, and is the consequence of a modified version of the Coleman-Glashow velocity dispersion relation. The momentum dispersion relation on Finsler spacetimes is shown to be the same as on metric spacetimes, which differs from many quantum gravity models. If similar relations resulted for fermions on Finsler spacetimes, these generalized geometries could explain the potential observation of superluminal neutrinos claimed by the Opera Collaboration.

  19. The superluminous supernova PS1-11ap: bridging the gap between low and high redshift

    Science.gov (United States)

    McCrum, M.; Smartt, S. J.; Kotak, R.; Rest, A.; Jerkstrand, A.; Inserra, C.; Rodney, S. A.; Chen, T.-W.; Howell, D. A.; Huber, M. E.; Pastorello, A.; Tonry, J. L.; Bresolin, F.; Kudritzki, R.-P.; Chornock, R.; Berger, E.; Smith, K.; Botticella, M. T.; Foley, R. J.; Fraser, M.; Milisavljevic, D.; Nicholl, M.; Riess, A. G.; Stubbs, C. W.; Valenti, S.; Wood-Vasey, W. M.; Wright, D.; Young, D. R.; Drout, M.; Czekala, I.; Burgett, W. S.; Chambers, K. C.; Draper, P.; Flewelling, H.; Hodapp, K. W.; Kaiser, N.; Magnier, E. A.; Metcalfe, N.; Price, P. A.; Sweeney, W.; Wainscoat, R. J.

    2014-01-01

    We present optical photometric and spectroscopic coverage of the superluminous supernova (SLSN) PS1-11ap, discovered with the Pan-STARRS1 Medium Deep Survey at z = 0.524. This intrinsically blue transient rose slowly to reach a peak magnitude of Mu = -21.4 mag and bolometric luminosity of 8 × 1043 erg s-1 before settling on to a relatively shallow gradient of decline. The observed decline is significantly slower than those of the SLSNe-Ic which have been the focus of much recent attention. Spectroscopic similarities with the lower redshift SN2007bi and a decline rate similar to 56Co decay time-scale initially indicated that this transient could be a candidate for a pair instability supernova (PISN) explosion. Overall the transient appears quite similar to SN2007bi and the lower redshift object PTF12dam. The extensive data set, from 30 d before peak to 230 d after, allows a detailed and quantitative comparison with published models of PISN explosions. We find that the PS1-11ap data do not match these model explosion parameters well, supporting the recent claim that these SNe are not pair instability explosions. We show that PS1-11ap has many features in common with the faster declining SLSNe-Ic, and the light-curve evolution can also be quantitatively explained by the magnetar spin-down model. At a redshift of z = 0.524, the observer-frame optical coverage provides comprehensive rest-frame UV data and allows us to compare it with the SLSNe recently found at high redshifts between z = 2 and 4. While these high-z explosions are still plausible PISN candidates, they match the photometric evolution of PS1-11ap and hence could be counterparts to this lower redshift transient.

  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.; 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.

  1. An Ultraviolet Excess in the Superluminous Supernova Gaia16apd Reveals a Powerful Central Engine

    Science.gov (United States)

    Nicholl, M.; Berger, E.; Margutti, R.; Blanchard, P. K.; Milisavljevic, D.; Challis, P.; Metzger, B. D.; Chornock, R.

    2017-01-01

    Since the discovery of superluminous supernovae (SLSNe) in the last decade, it has been known that these events exhibit bluer spectral energy distributions than other supernova subtypes, with significant output in the ultraviolet. However, the event Gaia16apd seems to outshine even the other SLSNe at rest-frame wavelengths below ∼3000 Å. Yan et al. have recently presented HST UV spectra and attributed the UV flux to low iron-group abundance in the outer ejecta, and hence reduced line blanketing. Here, we present UV and optical light curves over a longer baseline in time, revealing a rapid decline at UV wavelengths despite a typical optical evolution. Combining the published UV spectra with our own optical data, we demonstrate that Gaia16apd has a much hotter continuum than virtually any SLSN at maximum light, but it cools rapidly thereafter and is indistinguishable from the others by ∼10–15 days after peak. Comparing the equivalent widths of UV absorption lines with those of other events, we show that the excess UV continuum is a result of a more powerful central power source, rather than a lack of UV absorption relative to other SLSNe or an additional component from interaction with the surrounding medium. These findings strongly support the central-engine hypothesis for hydrogen-poor SLSNe. An explosion ejecting Mej = 4.8(0.2/κ) M⊙, where κ is the opacity in cm2 g‑1, and forming a magnetar with spin period P = 2 ms, and B = 2 × 1014 G (lower than other SLSNe with comparable rise times) can consistently explain the light curve evolution and high temperature at peak. The host metallicity, Z = 0.18 Z⊙, is comparable to other SLSNe.

  2. SN 2015BN: A Detailed Multi-wavelength View of a Nearby Superluminous Supernova

    Science.gov (United States)

    Nicholl, M.; Berger, E.; Smartt, S. J.; Margutti, R.; Kamble, A.; Alexander, K. D.; Chen, T.-W.; Inserra, C.; Arcavi, I.; Blanchard, P. K.; Cartier, R.; Chambers, K. C.; Childress, M. J.; Chornock, R.; Cowperthwaite, P. S.; Drout, M.; Flewelling, H. A.; Fraser, M.; Gal-Yam, A.; Galbany, L.; Harmanen, J.; Holoien, T. W.-S.; Hosseinzadeh, G.; Howell, D. A.; Huber, M. E.; Jerkstrand, A.; Kankare, E.; Kochanek, C. S.; Lin, Z.-Y.; Lunnan, R.; Magnier, E. A.; Maguire, K.; McCully, C.; McDonald, M.; Metzger, B. D.; Milisavljevic, D.; Mitra, A.; Reynolds, T.; Saario, J.; Shappee, B. J.; Smith, K. W.; Valenti, S.; Villar, V. A.; Waters, C.; Young, D. R.

    2016-07-01

    We present observations of SN 2015bn (=PS15ae = CSS141223-113342+004332 = MLS150211-113342+004333), a Type I superluminous supernova (SLSN) at redshift z = 0.1136. As well as being one of the closest SLSNe I yet discovered, it is intrinsically brighter ({M}U≈ -23.1) and in a fainter galaxy ({M}B≈ -16.0) than other SLSNe at z˜ 0.1. We used this opportunity to collect the most extensive data set for any SLSN I to date, including densely sampled spectroscopy and photometry, from the UV to the NIR, spanning -50 to +250 days from optical maximum. SN 2015bn fades slowly, but exhibits surprising undulations in the light curve on a timescale of 30-50 days, especially in the UV. The spectrum shows extraordinarily slow evolution except for a rapid transformation between +7 and +20-30 days. No narrow emission lines from slow-moving material are observed at any phase. We derive physical properties including the bolometric luminosity, and find slow velocity evolution and non-monotonic temperature and radial evolution. A deep radio limit rules out a healthy off-axis gamma-ray burst, and places constraints on the pre-explosion mass loss. The data can be consistently explained by a ≳ 10 M {}⊙ stripped progenitor exploding with ˜ {10}51 erg kinetic energy, forming a magnetar with a spin-down timescale of ˜20 days (thus avoiding a gamma-ray burst) that reheats the ejecta and drives ionization fronts. The most likely alternative scenario—interaction with ˜20 M {}⊙ of dense, inhomogeneous circumstellar material—can be tested with continuing radio follow-up.

  3. SUPERLUMINOUS SUPERNOVAE POWERED BY MAGNETARS: LATE-TIME LIGHT CURVES AND HARD EMISSION LEAKAGE

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S. Q.; Wang, L. J.; Dai, Z. G. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Wu, X. F., E-mail: dzg@nju.edu.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2015-01-20

    Recently, research performed by two groups has revealed that the magnetar spin-down energy injection model with full energy trapping can explain the early-time light curves of SN 2010gx, SN 2013dg, LSQ12dlf, SSS120810, and CSS121015 but fails to fit the late-time light curves of these superluminous supernovae (SLSNe). These results imply that the original magnetar-powered model is challenged in explaining these SLSNe. Our paper aims to simultaneously explain both the early- and late-time data/upper limits by considering the leakage of hard emissions. We incorporate quantitatively the leakage effect into the original magnetar-powered model and derive a new semianalytical equation. Comparing the light curves reproduced by our revised magnetar-powered model with the observed data and/or upper limits of these five SLSNe, we found that the late-time light curves reproduced by our semianalytical equation are in good agreement with the late-time observed data and/or upper limits of SN 2010gx, CSS121015, SN 2013dg, and LSQ12dlf and the late-time excess of SSS120810, indicating that the magnetar-powered model might be responsible for these SLSNe and that the gamma-ray and X-ray leakages are unavoidable when the hard photons were down-Comptonized to softer photons. To determine the details of the leakage effect and unveil the nature of SLSNe, more high-quality bolometric light curves and spectra of SLSNe are required.

  4. Host-galaxy Properties of 32 Low-redshift Superluminous Supernovae from the Palomar Transient Factory

    Science.gov (United States)

    Perley, D. A.; Quimby, R. M.; Yan, L.; Vreeswijk, P. M.; De Cia, A.; Lunnan, R.; Gal-Yam, A.; Yaron, O.; Filippenko, A. V.; Graham, M. L.; Laher, R.; Nugent, P. E.

    2016-10-01

    We present ultraviolet through near-infrared photometry and spectroscopy of the host galaxies of all superluminous supernovae (SLSNe) discovered by the Palomar Transient Factory prior to 2013 and derive measurements of their luminosities, star formation rates, stellar masses, and gas-phase metallicities. We find that Type I (hydrogen-poor) SLSNe (SLSNe I) are found almost exclusively in low-mass ({M}* \\lt 2× {10}9 {M}ȯ ) and metal-poor (12 + log10[O/H] \\lt 8.4) galaxies. We compare the mass and metallicity distributions of our sample to nearby galaxy catalogs in detail and conclude that the rate of SLSNe I as a fraction of all SNe is heavily suppressed in galaxies with metallicities ≳ 0.5 {Z}ȯ . Extremely low metallicities are not required and indeed provide no further increase in the relative SLSN rate. Several SLSN I hosts are undergoing vigorous starbursts, but this may simply be a side effect of metallicity dependence: dwarf galaxies tend to have bursty star formation histories. Type II (hydrogen-rich) SLSNe (SLSNe II) are found over the entire range of galaxy masses and metallicities, and their integrated properties do not suggest a strong preference for (or against) low-mass/low-metallicity galaxies. Two hosts exhibit unusual properties: PTF 10uhf is an SLSN I in a massive, luminous infrared galaxy at redshift z = 0.29, while PTF 10tpz is an SLSN II located in the nucleus of an early-type host at z = 0.04.

  5. Speed mathematics

    CERN Document Server

    Handley, Bill

    2012-01-01

    This new, revised edition of the bestselling Speed Mathematics features new chapters on memorising numbers and general information, calculating statistics and compound interest, square roots, logarithms and easy trig calculations. Written so anyone can understand, this book teaches simple strategies that will enable readers to make lightning-quick calculations. People who excel at mathematics use better strategies than the rest of us; they are not necessarily more intelligent. With Speed Mathematics you'll discover methods to make maths easy and fun. This book is perfect for stud

  6. Coherence for weak units

    CERN Document Server

    Joyal, André

    2009-01-01

    We define weak units in a semi-monoidal 2-category $\\CC$ as cancellable pseudo-idempotents: they are pairs $(I,\\alpha)$ where $I$ is an object such that tensoring with $I$ from either side constitutes a biequivalence of $\\CC$, and $\\alpha: I \\tensor I \\to I$ is an equivalence in $\\CC$. We show that this notion of weak unit has coherence built in: Theorem A: $\\alpha$ has a canonical associator 2-cell, which automatically satisfies the pentagon equation. Theorem B: every morphism of weak units is automatically compatible with those associators. Theorem C: the 2-category of weak units is contractible if non-empty. Finally we show (Theorem E) that the notion of weak unit is equivalent to the notion obtained from the definition of tricategory: $\\alpha$ alone induces the whole family of left and right maps (indexed by the objects), as well as the whole family of Kelly 2-cells (one for each pair of objects), satisfying the relevant coherence axioms.

  7. 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)

  8. Superluminous supernova 2015bn in the nebular phase: evidence for the engine-powered explosion of a stripped massive star

    CERN Document Server

    Nicholl, M; Margutti, R; Chornock, R; Blanchard, P K; Jerkstrand, A; Smartt, S J; Arcavi, I; Challis, P; Chambers, K C; Chen, T -W; Cowperthwaite, P S; Gal-Yam, A; Hosseinzadeh, G; Howell, D A; Inserra, C; Kankare, E; Magnier, E A; Maguire, K; Mazzali, P A; McCully, C; Milisavljevic, D; Smith, K W; Taubenberger, S; Valenti, S; Wainscoat, R J; Yaron, O; Young, D R

    2016-01-01

    We present nebular-phase imaging and spectroscopy for the hydrogen-poor superluminous supernova SN 2015bn, at redshift z=0.1136, spanning +250-400 d after maximum light. The light curve exhibits a steepening in the decline rate from 1.4 mag/(100 d) to 1.7 mag/(100 d), suggestive of a significant decrease in the opacity. This change is accompanied by a transition from a blue continuum superposed with photospheric absorption lines to a nebular spectrum dominated by emission lines of oxygen, calcium and magnesium. There are no obvious signatures of circumstellar interaction or large nickel mass. We show that the spectrum at +400 d is virtually identical to a number of energetic Type Ic supernovae such as SN 1997dq, SN 2012au, and SN 1998bw, indicating similar core conditions and strengthening the link between `hypernovae'/long gamma-ray bursts and superluminous supernovae. A single explosion mechanism may unify these events that span absolute magnitudes of -22 < M_B < -17. Both the light curve and spectrum...

  9. Spectroscopy of superluminous supernova host galaxies. A preference of hydrogen-poor events for extreme emission line galaxies

    CERN Document Server

    Leloudas, G; Kruehler, T; Gorosabel, J; Christensen, L; Mehner, A; Postigo, A de Ugarte; Amorin, R; Thoene, C C; Anderson, J P; Bauer, F E; Gallazzi, A; Helminiak, K G; Hjorth, J; Ibar, E; Malesani, D; Morell, N; Vinko, J; Wheeler, J C

    2014-01-01

    Superluminous supernovae (SLSNe) were only discovered recently due to their 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 (SUSHIES), 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-II (hydrogen-rich) occur in more massive, more metal-rich galaxies with softer radiation fields. Therefore, if SLSNe-II constitute a uniform class, th...

  10. Weak layer fracture: facets and depth hoar

    Directory of Open Access Journals (Sweden)

    I. Reiweger

    2013-09-01

    Full Text Available Understanding failure initiation within weak snow layers is essential for modeling and predicting dry-snow slab avalanches. We therefore performed laboratory experiments with snow samples containing a weak layer consisting of either faceted crystals or depth hoar. During these experiments the samples were loaded with different loading rates and at various tilt angles until fracture. The strength of the samples decreased with increasing loading rate and increasing tilt angle. Additionally, we took pictures of the side of four samples with a high-speed video camera and calculated the displacement using a particle image velocimetry (PIV algorithm. The fracture process within the weak layer could thus be observed in detail. Catastrophic failure started due to a shear fracture just above the interface between the depth hoar layer and the underlying crust.

  11. WEAK CONVERGENCE OF SOME SERIES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper continues the study of [1] on weak functions.The weak convergence theory is investigated in complex analysis,Fourier transform and Mellin transform.A Mobius inverse formula of weak functions is obtained.

  12. On Weak Markov's Principle

    DEFF Research Database (Denmark)

    Kohlenbach, Ulrich Wilhelm

    2002-01-01

    We show that the so-called weak Markov's principle (WMP) which states that every pseudo-positive real number is positive is underivable in E-HA + AC. Since allows one to formalize (atl eastl arge parts of) Bishop's constructive mathematics, this makes it unlikely that WMP can be proved within the...

  13. On closed weak supplemented modules

    Institute of Scientific and Technical Information of China (English)

    ZENG Qing-yi; SHI Mei-hua

    2006-01-01

    A module M is called closed weak supplemented if for any closed submodule N of M, there is a submodule K of M such that M=K+N and K(c)N<<M. Any direct summand of closed weak supplemented module is also closed weak supplemented.Any nonsingular image of closed weak supplemented module is closed weak supplemented. Nonsingular V-rings in which all nonsingular modules are closed weak supplemented are characterized in Section 4.

  14. Relativistic Jets in the Radio Reference Frame Image Database. 1. Apparent Speeds From the First 5 Years of Data

    Science.gov (United States)

    2007-02-11

    simulations by Agudo et al. (2001) suggested that multiple slowly moving conical shocks formed from the interaction of superluminal components with the under...from zero up to this bulk flow speed. A scenario such as this would be consistent with jet simulations such as those of Agudo et al. (2001), in which...Science Award from Research Corporation. REFERENCES Agudo , I., Gomez, J.-L., Martı́, J.-M., Ibáñez, J.-M., Marscher, A. P., Alberdi, A., Aloy, M.-A

  15. 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).

  16. SN 2012aa: A transient between Type Ibc core-collapse and superluminous supernovae

    Science.gov (United States)

    Roy, R.; Sollerman, J.; Silverman, J. M.; Pastorello, A.; Fransson, C.; Drake, A.; Taddia, F.; Fremling, C.; Kankare, E.; Kumar, B.; Cappellaro, E.; Bose, S.; Benetti, S.; Filippenko, A. V.; Valenti, S.; Nyholm, A.; Ergon, M.; Sutaria, F.; Kumar, B.; Pandey, S. B.; Nicholl, M.; Garcia-Álvarez, D.; Tomasella, L.; Karamehmetoglu, E.; Migotto, K.

    2016-12-01

    Context. Research on supernovae (SNe) over the past decade has confirmed that there is a distinct class of events which are much more luminous (by 2 mag) than canonical core-collapse SNe (CCSNe). These events with visual peak magnitudes ≲-21 are called superluminous SNe (SLSNe). The mechanism that powers the light curves of SLSNe is still not well understood. The proposed scenarios are circumstellar interaction, the emergence of a magnetar after core collapse, or disruption of a massive star through pair production. Aims: There are a few intermediate events which have luminosities between these two classes. They are important for constraining the nature of the progenitors of these two different populations and their environments and powering mechanisms. Here we study one such object, SN 2012aa. Methods: We observed and analysed the evolution of the luminous Type Ic SN 2012aa. The event was discovered by the Lick Observatory Supernova Search in an anonymous galaxy (z ≈ 0.08). The optical photometric and spectroscopic follow-up observations were conducted over a time span of about 120 days. Results: With an absolute V-band peak of - 20 mag, the SN is an intermediate-luminosity transient between regular SNe Ibc and SLSNe. SN 2012aa also exhibits an unusual secondary bump after the maximum in its light curve. For SN 2012aa, we interpret this as a manifestation of SN-shock interaction with the circumstellar medium (CSM). If we assume a 56Ni-powered ejecta, the quasi-bolometric light curve requires roughly 1.3 M⊙ of 56Ni and an ejected mass of 14M⊙. This also implies a high kinetic energy of the explosion, 5.4 × 1051 erg. On the other hand, the unusually broad light curve along with the secondary peak indicate the possibility of interaction with CSM. The third alternative is the presence of a central engine releasing spin energy that eventually powers the light curve over a long time. The host of SN 2012aa is a star-forming Sa/Sb/Sbc galaxy. Conclusions

  17. Superluminous Supernovae as Standardizable Candles and High-redshift Distance Probes

    Science.gov (United States)

    Inserra, C.; Smartt, S. J.

    2014-12-01

    We investigate the use of type Ic superluminous supernovae (SLSN Ic) as standardizable candles and distance indicators. Their appeal as cosmological probes stems from their remarkable peak luminosities, hot blackbody temperatures, and bright rest-frame ultraviolet emission. We present a sample of 16 published SLSN, from redshifts 0.1 to 1.2, and calculate accurate K corrections to determine uniform magnitudes in 2 synthetic rest-frame filter bandpasses with central wavelengths at 400 nm and 520 nm. At 400 nm, we find an encouragingly low scatter in their uncorrected, raw mean magnitudes with M(400) = -21.86 ± 0.35 mag for the full sample of 16 objects. We investigate the correlation between their decline rates and peak magnitude and find that the brighter events appear to decline more slowly. In a manner similar to the Phillips relation for type Ia SNe (SNe Ia), we define a ΔM 20 decline relation. This correlates peak magnitude and decline over 20 days and can reduce the scatter in standardized peak magnitudes to ±0.22 mag. We further show that M(400) appears to have a strong color dependence. Redder objects are fainter and also become redder faster. Using this peak magnitudecolor evolution relation, a surprisingly low scatter of between ±0.08 mag and ±0.13 mag can be found in peak magnitudes, depending on sample selection. However, we caution that only 8 to 10 objects currently have enough data to test this peak magnitudecolor evolution relation. We conclude that SLSN Ic are promising distance indicators in the high-redshift universe in regimes beyond those possible with SNe Ia. Although the empirical relationships are encouraging, the unknown progenitor systems, how they may evolve with redshift, and the uncertain explosion physics are of some concern. The two major measurement uncertainties are the limited numbers of low-redshift, well-studied objects available to test these relationships and internal dust extinction in the host galaxies.

  18. DES13S2cmm: the first superluminous supernova from the Dark Energy Survey

    Energy Technology Data Exchange (ETDEWEB)

    Papadopoulos, A.; D’Andrea, C. B.; Sullivan, M; Nichol, R. C.; Barbary, K.; Biswas, R.; Brown, P. J.; Covarrubias, R. A.; Finley, D. A.; Fischer, J. A.; Gupta, R. R.; Kovacs, E.; Kuhlmann, S. E.; Spinka, H.; Bernstein, J. P.

    2015-05-11

    We present DES13S2cmm, the first spectroscopically-confirmed superluminous supernova (SLSN) from the Dark Energy Survey (DES). We briefly discuss the data and search algorithm used to find this event in the first year of DES operations, and outline the spectroscopic data obtained from the European Southern Observatory (ESO) Very Large Telescope to confirm its redshift (z = 0.663 +/- 0.001 based on the host-galaxy emission lines) and likely spectral type (Type I). Using this redshift, we find M-U(peak) = -21.05(-0.09)(+0.10) for the peak, rest-frame U-band absolute magnitude, and find DES13S2cmm to be located in a faint, low-metallicity (subsolar), low stellar-mass host galaxy (log (M/M-circle dot) = 9.3 +/- 0.3), consistent with what is seen for other SLSNe-I. We compare the bolometric light curve of DES13S2cmm to 14 similarly well-observed SLSNe-I in the literature and find that it possesses one of the slowest declining tails (beyond +30 d rest-frame past peak), and is the faintest at peak. Moreover, we find the bolometric light curves of all SLSNe-I studied herein possess a dispersion of only 0.2-0.3 mag between +25 and +30 d after peak (rest frame) depending on redshift range studied; this could be important for 'standardizing' such supernovae, as is done with the more common Type Ia. We fit the bolometric light curve of DES13S2cmm with two competing models for SLSNe-I-the radioactive decay of Ni-56, and a magnetar - and find that while the magnetar is formally a better fit, neither model provides a compelling match to the data. Although we are unable to conclusively differentiate between these two physical models for this particular SLSN-I, further DES observations of more SLSNe-I should break this degeneracy, especially if the light curves of SLSNe-I can be observed beyond 100 d in the rest frame of the supernova.

  19. Weak Polarized Electron Scattering

    CERN Document Server

    Erler, Jens; Mantry, Sonny; Souder, Paul A

    2014-01-01

    Scattering polarized electrons provides an important probe of the weak interactions. Precisely measuring the parity-violating left-right cross section asymmetry is the goal of a number of experiments recently completed or in progress. The experiments are challenging, since A_{LR} is small, typically between 10^(-4) and 10^(-8). By carefully choosing appropriate targets and kinematics, various pieces of the weak Lagrangian can be isolated, providing a search for physics beyond the Standard Model. For other choices, unique features of the strong interaction are studied, including the radius of the neutron density in heavy nuclei, charge symmetry violation, and higher twist terms. This article reviews the theory behind the experiments, as well as the general techniques used in the experimental program.

  20. Composite weak bosons

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, M.

    1988-04-01

    Dynamical mechanism of composite W and Z is studied in a 1/N field theory model with four-fermion interactions in which global weak SU(2) symmetry is broken explicitly by electromagnetic interaction. Issues involved in such a model are discussed in detail. Deviation from gauge coupling due to compositeness and higher order loop corrections are examined to show that this class of models are consistent not only theoretically but also experimentally.

  1. SIMULATION OF SUBGRADE EMBANKMENT ON WEAK BASE

    Directory of Open Access Journals (Sweden)

    V. D. Petrenko

    2015-08-01

    Full Text Available Purpose. This article provides: the question of the sustainability of the subgrade on a weak base is considered in the paper. It is proposed to use the method of jet grouting. Investigation of the possibility of a weak base has an effect on the overall deformation of the subgrade; the identification and optimization of the parameters of subgrade based on studies using numerical simulation. Methodology. The theoretical studies of the stress-strain state of the base and subgrade embankment by modeling in the software package LIRA have been conducted to achieve this goal. Findings. After making the necessary calculations perform building fields of a subsidence, borders cramped thickness, bed’s coefficients of Pasternak and Winkler. The diagrams construction of vertical stress performs at any point of load application. Also, using the software system may perform peer review subsidence, rolls railroad tracks in natural and consolidated basis. Originality. For weak soils is the most appropriate nonlinear model of the base with the existing areas of both elastic and limit equilibrium, mixed problem of the theory of elasticity and plasticity. Practical value. By increasing the load on the weak base as a result of the second track construction, adds embankment or increasing axial load when changing the rolling stock process of sedimentation and consolidation may continue again. Therefore, one of the feasible and promising options for the design and reconstruction of embankments on weak bases is to strengthen the bases with the help of jet grouting. With the expansion of the railway infrastructure, increasing speed and weight of the rolling stock is necessary to ensure the stability of the subgrade on weak bases. LIRA software package allows you to perform all the necessary calculations for the selection of a proper way of strengthening weak bases.

  2. The Weak Haagerup Property II

    DEFF Research Database (Denmark)

    Haagerup, Uffe; Knudby, Søren

    2015-01-01

    The weak Haagerup property for locally compact groups and the weak Haagerup constant were recently introduced by the second author [27]. The weak Haagerup property is weaker than both weak amenability introduced by Cowling and the first author [9] and the Haagerup property introduced by Connes [6......] and Choda [5]. In this paper, it is shown that a connected simple Lie group G has the weak Haagerup property if and only if the real rank of G is zero or one. Hence for connected simple Lie groups the weak Haagerup property coincides with weak amenability. Moreover, it turns out that for connected simple...... Lie groups the weak Haagerup constant coincides with the weak amenability constant, although this is not true for locally compact groups in general. It is also shown that the semidirect product R2 × SL(2,R) does not have the weak Haagerup property....

  3. Weak martingale Hardy spaces and weak atomic decompositions

    Institute of Scientific and Technical Information of China (English)

    HOU; Youliang; REN; Yanbo

    2006-01-01

    In this paper we define some weak martingale Hardy spaces and three kinds of weak atoms. They are the counterparts of martingale Hardy spaces and atoms in the classical martingale Hp-theory. And then three atomic decomposition theorems for martingales in weak martingale Hardy spaces are proved. With the help of the weak atomic decompositions of martingale, a sufficient condition for a sublinear operator defined on the weak martingale Hardy spaces to be bounded is given. Using the sufficient condition, we obtain a series of martingale inequalities with respect to the weak Lp-norm, the inequalities of weak (p ,p)-type and some continuous imbedding relationships between various weak martingale Hardy spaces. These inequalities are the weak versions of the basic inequalities in the classical martingale Hp-theory.

  4. Do not mess with time: Probing faster than light travel and chronology protection with superluminal warp drives

    CERN Document Server

    Liberati, Stefano

    2016-01-01

    While General Relativity ranks undoubtedly among the best physics theories ever developed, it is also among those with the most striking implications. In particular, General Relativity admits solutions which allow faster than light motion and consequently time travel. Here we shall consider a "pre-emptive" chronology protection mechanism that destabilises superluminal warp drives via quantum matter back-reaction and hence forbids even the conceptual possibility to use these solutions for building a time machine. This result will be considered both in standard quantum field theory in curved spacetime as well as in the case of a quantum field theory with Lorentz invariance breakdown at high energies. Some lessons and future perspectives will be finally discuss.

  5. Inversion assuming weak scattering

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Gerstoft, Peter; Mosegaard, Klaus

    2013-01-01

    The study of weak scattering from inhomogeneous media or interface roughness has long been of interest in sonar applications. In an acoustic backscattering model of a stationary field of volume inhomogeneities, a stochastic description of the field is more useful than a deterministic description...... due to the complex nature of the field. A method based on linear inversion is employed to infer information about the statistical properties of the scattering field from the obtained cross-spectral matrix. A synthetic example based on an active high-frequency sonar demonstrates that the proposed...

  6. The Weak Neutral Current

    CERN Document Server

    Erler, Jens

    2013-01-01

    This is a review of electroweak precision physics with particular emphasis on low-energy precision measurements in the neutral current sector of the electroweak theory and includes future experimental prospects and the theoretical challenges one faces to interpret these observables. Within the minimal Standard Model they serve as determinations of the weak mixing angle which are competitive with and complementary to those obtained near the Z-resonance. In the context of new physics beyond the Standard Model these measurements are crucial to discriminate between models and to reduce the allowed parameter space within a given model. We illustrate this for the minimal supersymmetric Standard Model with or without R-parity.

  7. Measurement of weak radioactivity

    CERN Document Server

    Theodorsson , P

    1996-01-01

    This book is intended for scientists engaged in the measurement of weak alpha, beta, and gamma active samples; in health physics, environmental control, nuclear geophysics, tracer work, radiocarbon dating etc. It describes the underlying principles of radiation measurement and the detectors used. It also covers the sources of background, analyzes their effect on the detector and discusses economic ways to reduce the background. The most important types of low-level counting systems and the measurement of some of the more important radioisotopes are described here. In cases where more than one type can be used, the selection of the most suitable system is shown.

  8. Weakly broken galileon symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Pirtskhalava, David [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy); Santoni, Luca; Trincherini, Enrico [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy); INFN, Sezione di Pisa, Piazza dei Cavalieri 7, 56126 Pisa (Italy); Vernizzi, Filippo [Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS, Gif-sur-Yvette cédex, F-91191 (France)

    2015-09-01

    Effective theories of a scalar ϕ invariant under the internal galileon symmetryϕ→ϕ+b{sub μ}x{sup μ} have been extensively studied due to their special theoretical and phenomenological properties. In this paper, we introduce the notion of weakly broken galileon invariance, which characterizes the unique class of couplings of such theories to gravity that maximally retain their defining symmetry. The curved-space remnant of the galileon’s quantum properties allows to construct (quasi) de Sitter backgrounds largely insensitive to loop corrections. We exploit this fact to build novel cosmological models with interesting phenomenology, relevant for both inflation and late-time acceleration of the universe.

  9. Weak Decay of Hypernuclei

    CERN Document Server

    Alberico, W M

    2004-01-01

    The focus of these Lectures is on the weak decay modes of hypernuclei, with special attention to Lambda-hypernuclei. The subject involves many fields of modern theoretical and experimental physics, from nuclear structure to the fundamental constituents of matter and their interactions. The various weak decay modes of Lambda-hypernuclei are described: the mesonic mode and the non-mesonic ones. The latter are the dominant decay channels of medium--heavy hypernuclei, where, on the contrary, the mesonic decay is disfavoured by Pauli blocking effect on the outgoing nucleon. In particular, one can distinguish between one-body and two-body induced decays. Theoretical models employed to evaluate the (partial and total) decay widths of hypernuclei are illustrated, and their results compared with existing experimental data. Open problems and recent achievements are extensively discussed, in particular the determination of the ratio Gamma_n/Gamma_p, possible tests of the Delta I=1/2 rule in non-mesonic decays and the pu...

  10. ICU-Acquired Weakness.

    Science.gov (United States)

    Jolley, Sarah E; Bunnell, Aaron E; Hough, Catherine L

    2016-11-01

    Survivorship after critical illness is an increasingly important health-care concern as ICU use continues to increase while ICU mortality is decreasing. Survivors of critical illness experience marked disability and impairments in physical and cognitive function that persist for years after their initial ICU stay. Newfound impairment is associated with increased health-care costs and use, reductions in health-related quality of life, and prolonged unemployment. Weakness, critical illness neuropathy and/or myopathy, and muscle atrophy are common in patients who are critically ill, with up to 80% of patients admitted to the ICU developing some form of neuromuscular dysfunction. ICU-acquired weakness (ICUAW) is associated with longer durations of mechanical ventilation and hospitalization, along with greater functional impairment for survivors. Although there is increasing recognition of ICUAW as a clinical entity, significant knowledge gaps exist concerning identifying patients at high risk for its development and understanding its role in long-term outcomes after critical illness. This review addresses the epidemiologic and pathophysiologic aspects of ICUAW; highlights the diagnostic challenges associated with its diagnosis in patients who are critically ill; and proposes, to our knowledge, a novel strategy for identifying ICUAW. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

  11. Weak Quantum Ergodicity

    CERN Document Server

    Kaplan, L

    1998-01-01

    We examine the consequences of classical ergodicity for the localization properties of individual quantum eigenstates in the classical limit. We note that the well known Schnirelman result is a weaker form of quantum ergodicity than the one implied by random matrix theory. This suggests the possibility of systems with non-gaussian random eigenstates which are nonetheless ergodic in the sense of Schnirelman and lead to ergodic transport in the classical limit. These we call "weakly quantum ergodic.'' Indeed for a class of "slow ergodic" classical systems, it is found that each eigenstate becomes localized to an ever decreasing fraction of the available state space, in the semiclassical limit. Nevertheless, each eigenstate in this limit covers phase space evenly on any classical scale, and long-time transport properties betwen individual quantum states remain ergodic due to the diffractive effects which dominate quantum phase space exploration.

  12. Neutrino and the Possibility of Superluminal Phenomenon%中微子和超光速现象的可能性

    Institute of Scientific and Technical Information of China (English)

    韩锋

    2012-01-01

    If the rest mass of the neutrino is not zero, it is required that neutrino be superluminal in order to explain the two - component neutrino theory of parity non - conservation. In the light of this, the paper discusses the superluminal phenomenon under the guidance of the theory of relativity and also the possibility of the existence of tachyon.%如果中微子静止质量不为零,那么为了解释宇称不守恒的二分量中微子理论就要求中微子是超光速的。讨论了在相对论框架内对这种超光速现象的理解,以及存在"快子"的可能性。

  13. Weak 'Antigravity' Fields in General Relativity

    CERN Document Server

    Felber, F S

    2005-01-01

    Within the weak-field approximation of general relativity, new exact solutions are derived for the gravitational field of a mass moving with arbitrary velocity and acceleration. Owing to an inertial-pushing effect, a mass having a constant velocity greater than 3^-1/2 times the speed of light gravitationally repels other masses at rest within a narrow cone. At high Lorentz factors (gamma >> 1), the force of repulsion in the forward direction is about -8(gamma^5) times the Newtonian force, offering opportunities for laboratory tests of gravity at extreme velocities.

  14. 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.

  15. Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects Connection between Superluminal Ejections and Gamma-Ray Flares in Blazars

    CERN Document Server

    Jorstad, S G; Mattox, J R; Aller, M F; Aller, H D; Wehrle, A E; Bloom, S D; Jorstad, Svetlana G; Marscher, Alan P; Mattox, John R; Aller, Margo F; Aller, Hugh D; Wehrle, Ann E; Bloom, Steven D

    2001-01-01

    We examine the coincidence of times of high $\\gamma$-ray flux and ejections of superluminal components from the core in EGRET blazars based on a VLBA monitoring program at 22 and 43 GHz from November 1993 to July 1997. In 23 cases of $\\gamma$-ray flares for which sufficient VLBA data exist, 16 of the flares (in 14 objects) fall within 3$\\sigma$ and 9 of these within 1$\\sigma$ uncertainties of the extrapolated epoch of zero separation from the core of a superluminal radio component. In each of two sources (0528+134 and 1730-130) two successive $\\gamma$-ray flares were followed by the appearance of new superluminal components. We carried out statistical simulations which show that if the number of coincidences $\\ge$ 7 the radio and $\\gamma$-ray events are associated with each other at >99.999% confidence. Our analysis of the observed behavior, including variability of the polarized radio flux, of the sources before, during, and after the $\\gamma$-ray flares suggests that the $\\gamma$-ray events occur in the sup...

  16. "Superluminal" FITS File Processing on Multiprocessors: Zero Time Endian Conversion Technique

    Science.gov (United States)

    Eguchi, Satoshi

    2013-05-01

    The FITS is the standard file format in astronomy, and it has been extended to meet the astronomical needs of the day. However, astronomical datasets have been inflating year by year. In the case of the ALMA telescope, a ~TB-scale four-dimensional data cube may be produced for one target. Considering that typical Internet bandwidth is tens of MB/s at most, the original data cubes in FITS format are hosted on a VO server, and the region which a user is interested in should be cut out and transferred to the user (Eguchi et al. 2012). The system will equip a very high-speed disk array to process a TB-scale data cube in 10 s, and disk I/O speed, endian conversion, and data processing speeds will be comparable. Hence, reducing the endian conversion time is one of issues to solve in our system. In this article, I introduce a technique named "just-in-time endian conversion", which delays the endian conversion for each pixel just before it is really needed, to sweep out the endian conversion time; by applying this method, the FITS processing speed increases 20% for single threading and 40% for multi-threading compared to CFITSIO. The speedup tightly relates to modern CPU architecture to improve the efficiency of instruction pipelines due to break of "causality", a programmed instruction code sequence.

  17. Weak Cat-Operads

    CERN Document Server

    Dosen, K

    2010-01-01

    An operad (this paper deals with non-symmetric operads) may be conceived as a partial algebra with a family of insertion operations, Gerstenhaber's circle-i products, which satisfy two kinds of associativity, one of them involving commutativity. A Cat-operad is an operad enriched over the category Cat of small categories, as a 2-category with small hom-categories is a category enriched over Cat. The notion of weak Cat-operad is to the notion of Cat-operad what the notion of bicategory is to the notion of 2-category. The equations of operads like associativity of insertions are replaced by isomorphisms in a category. The goal of this paper is to formulate conditions concerning these isomorphisms that ensure coherence, in the sense that all diagrams of canonical arrows commute. This is the sense in which the notions of monoidal category and bicategory are coherent. The coherence proof in the paper is much simplified by indexing the insertion operations in a context-independent way, and not in the usual manner. ...

  18. Weak Total Resolvability In Graphs

    Directory of Open Access Journals (Sweden)

    Casel Katrin

    2016-02-01

    Full Text Available A vertex v ∈ V (G is said to distinguish two vertices x, y ∈ V (G of a graph G if the distance from v to x is di erent from the distance from v to y. A set W ⊆ V (G is a total resolving set for a graph G if for every pair of vertices x, y ∈ V (G, there exists some vertex w ∈ W − {x, y} which distinguishes x and y, while W is a weak total resolving set if for every x ∈ V (G−W and y ∈ W, there exists some w ∈ W −{y} which distinguishes x and y. A weak total resolving set of minimum cardinality is called a weak total metric basis of G and its cardinality the weak total metric dimension of G. Our main contributions are the following ones: (a Graphs with small and large weak total metric bases are characterised. (b We explore the (tight relation to independent 2-domination. (c We introduce a new graph parameter, called weak total adjacency dimension and present results that are analogous to those presented for weak total dimension. (d For trees, we derive a characterisation of the weak total (adjacency metric dimension. Also, exact figures for our parameters are presented for (generalised fans and wheels. (e We show that for Cartesian product graphs, the weak total (adjacency metric dimension is usually pretty small. (f The weak total (adjacency dimension is studied for lexicographic products of graphs.

  19. Tunable THz Generation by the Interaction of a Super-luminous Laser Pulse with Biased Semiconductor Plasma

    Science.gov (United States)

    Papadopoulos, K.; Zigler, A.

    2006-01-01

    Terahertz (THz) radiation is electromagnetic radiation in the range between several hundred and a few thousand GHz. It covers the gap between fast-wave electronics (millimeter waves) and optics (infrared). This spectral region offers enormous potential for detection of explosives and chemical/biological agents, non-destructive testing of non-metallic structural materials and coatings of aircraft structures, medical imaging, bio-sensing of DNA stretching modes and high-altitude secure communications. The development of these applications has been hindered by the lack of powerful, tunable THz sources with controlled waveform. The need for such sources is accentuated by the strong, but selective absorption of THz radiation during transmission through air with high vapor content. The majority of the current experimental work relies on time-domain spectroscopy using fast electrically biased photoconductive sources in conjunction with femto-second mode-locked Ti:Sapphire lasers. These sources known as Large Aperture Photoconductive Antennas (LAPA) have very limited tunability, relatively low upper bound of power and no bandwidth control. The paper presents a novel source of THz radiation known as Miniature Photoconductive Capacitor Array (MPCA). Experiments demonstrated tunability between .1 - 2 THz, control of the relative bandwidth Δf/f between .5-.01, and controlled pulse length and pulse waveform (temporal shape, chirp, pulse-to-pulse modulation etc.). Direct scaling from the current device indicates efficiency in excess of 30% at 1 THz with 1/f2 scaling at higher frequencies, peak power of 100 kW and average power between .1-1 W. The physics underlying the MPCA is the interaction of a super-luminous ionization front generated by the oblique incidence of a Ti:Sapphire laser pulse on a semiconductor crystal (ZnSe) biased with an alternating electrostatic field, similar to that of a frozen wave generator. It is shown theoretically and experimentally that the

  20. Weak compactness of biharmonic maps

    Directory of Open Access Journals (Sweden)

    Shenzhou Zheng

    2012-10-01

    Full Text Available This article shows that if a sequence of weak solutions of a perturbed biharmonic map satisfies $Phi_ko 0$ in $(W^{2,2}^*$ and $u_kightharpoonup u$ weakly in $W^{2,2}$, then $u$ is a biharmonic map. In particular, we show that the space of biharmonic maps is sequentially compact under the weak-$W^{2,2}$ topology.

  1. Numerical Tests of Fast Reconnection in Weakly Stochastic Magnetic Fields

    CERN Document Server

    Kowal, G; Vishniac, E T; Otmianowska-Mazur, K

    2009-01-01

    We study the effects of turbulence on magnetic reconnection using 3D numerical simulations. This is the first attempt to test a model of fast magnetic reconnection in the presence of weak turbulence proposed by Lazarian & Vishniac (1999). This model predicts that weak turbulence, generically present in most of astrophysical systems, enhances the rate of reconnection by reducing the transverse scale for reconnection events and by allowing many independent flux reconnection events to occur simultaneously. As a result the reconnection speed becomes independent of Ohmic resistivity and is determined by the magnetic field wandering induced by turbulence. To quantify the reconnection speed we use both an intuitive definition, i.e. the speed of the reconnected flux inflow, as well as a more sophisticated definition based on a formally derived analytical expression. Our results confirm the predictions of the Lazarian & Vishniac model. In particular, we find that Vrec Pinj^(1/2), as predicted by the model. The...

  2. NUMERICAL STUDIES OF WEAKLY STOCHASTIC MAGNETIC RECONNECTION

    Directory of Open Access Journals (Sweden)

    G. Kowal

    2009-01-01

    Full Text Available We study the e ects of turbulence on magnetic reconnection using three-dimensional numerical simulations.This is the rst attempt to test the model of fast magnetic reconnection proposed by Lazarian & Vishniac (1999, which assumes the presence of weak, small-scale magnetic eld structure near the current sheet. This a ects the rate of reconnection by reducing the transverse scale for reconnection ows and by allowing many independent ux reconnection events to occur simultaneously. We performed a number of simulations to test the dependencies of the reconnection speed, de ned as the ratio of the in ow velocity to the Alfv n speed, on the turbulence power, the injection scale and resistivity. Our results show that turbulence signi cantly a ects the topology of magnetic eld near the di usion region and increases the thickness of the out ow region. We con rm the predictions of the Lazarian & Vishniac model. In particular, we report the growth of the reconnection speed proportional to V 2 l , where Vl is the amplitude of velocity at the injection scale. It depends on the injection scale linj as (linj=L2=3, where L is the size of the system, which is somewhat faster but still roughly consistent with the theoretical expectations. We also show that for 3D reconnection the Ohmic resistivity is important in the local reconnection events only, and the global reconnection rate in the presence of turbulence does not depend on it.

  3. LSQ14bdq: A Type Ic super-luminous supernova with a double-peaked light curve

    CERN Document Server

    Nicholl, M; Jerkstrand, A; Sim, S A; Inserra, C; Anderson, J P; Baltay, C; Benetti, S; Chambers, K; Chen, T -W; Elias-Rosa, N; Feindt, U; Flewelling, H A; Fraser, M; Gal-Yam, A; Galbany, L; Huber, M E; Kangas, T; Kankare, E; Kotak, R; Krühler, T; Maguire, K; McKinnon, R; Rabinowitz, D; Rostami, S; Schulze, S; Smith, K W; Sullivan, M; Tonry, J L; Valenti, S; Young, D R

    2015-01-01

    We present data for LSQ14bdq, a hydrogen-poor super-luminous supernova (SLSN) discovered by the La Silla QUEST survey and classified by the Public ESO Spectroscopic Survey of Transient Objects. The spectrum and light curve are very similar to slow-declining SLSNe such as PTF12dam. However, detections within $\\sim1$ day after explosion show a bright and relatively fast initial peak, lasting for $\\sim15$ days, prior to the usual slow rise to maximum light. The broader, main peak can be fit with either central engine or circumstellar interaction models. We discuss the implications of the precursor peak in the context of these models. It is too bright and narrow to be explained as a normal \\Ni-powered SN, and we suggest that interaction models may struggle to fit the precursor and main peak simultaneously. We propose that the initial peak is from the post-shock cooling of an extended stellar envelope, and reheating by a central engine drives the second peak. In this picture, we show that an explosion energy of $\\...

  4. Selecting superluminous supernovae in faint galaxies from the first year of the Pan-STARRS1 Medium Deep Survey

    CERN Document Server

    McCrum, M; Rest, A; Smith, K; Kotak, R; Rodney, S A; Young, D R; Chornock, R; Berger, E; Foley, R J; Fraser, M; Wright, D; Scolnic, D; Tonry, J L; Urata, Y; Huang, K; Pastorello, A; Botticella, M T; Valenti, S; Mattila, S; Kankare, E; Farrow, D J; Huber, M E; Stubbs, C W; Kirshner, R P; Bresolin, F; Burgett, W S; Chambers, K C; Draper, P W; Flewelling, H; Jedicke, R; Kaiser, N; Magnier, E A; Metcalfe, N; Morgan, J S; Price, P A; Sweeney, W; Wainscoat, R J; Waters, C

    2014-01-01

    The Pan-STARRS1 (PS1) survey has obtained imaging in 5 bands (grizy_P1) over 10 Medium Deep Survey (MDS) fields covering a total of 70 square degrees. This paper describes the search for apparently hostless supernovae (SNe) within the first year of PS1 MDS data with an aim of discovering new superluminous supernovae (SLSNe). A total of 249 hostless transients were discovered down to a limiting magnitude of M_AB ~ 23.5, of which 75 were classified as Type Ia SNe. There were 58 SNe with complete light curves that are likely core-collapse SNe (CCSNe) or SLSNe and 13 of these have had spectra taken. Of these 13 hostless, non-Type Ia SNe, 9 were SLSNe of Type I at redshifts between 0.5-1.4. Thus one can maximise the discovery rate of Type I SLSNe by concentrating on hostless transients and removing normal SNe Ia. We present data for three new possible SLSNe; PS1-10pm (z = 1.206), PS1-10ahf (z = 1.16) and PS1-11acn (z ~ 0.61), and estimate the rate of SLSNe-I to be between 0.6pm0.3 * 10^-4 and 1.0pm0.3 * 10^-4 of t...

  5. The hydrogen-poor superluminous supernova iPTF13ajg and its host galaxy in absorption and emission

    CERN Document Server

    Vreeswijk, Paul M; Gal-Yam, Avishay; De Cia, Annalisa; Quimby, Robert M; Sullivan, Mark; Cenko, S Bradley; Perley, Daniel A; Filippenko, Alexei V; Clubb, Kelsey I; Taddia, Francesco; Sollerman, Jesper; Leloudas, Giorgos; Arcavi, Iair; Rubin, Adam; Kasliwal, Mansi M; Cao, Yi; Yaron, Ofer; Tal, David; Ofek, Eran O; Capone, John; Kutyrev, Alexander S; Toy, Vicki; Nugent, Peter E; Laher, Russ; Surace, Jason; Kulkarni, Shrinivas R

    2014-01-01

    We present imaging and spectroscopy of a hydrogen-poor superluminous supernova (SLSN) discovered by the intermediate Palomar Transient Factory: iPTF13ajg. At a redshift of z=0.7403, derived from narrow absorption lines, iPTF13ajg peaked at an absolute magnitude M(u,AB)=-22.5, one of the most luminous supernovae to date. The uBgRiz light curves, obtained with the P48, P60, NOT, DCT, and Keck telescopes, and the nine-epoch spectral sequence secured with the Keck and the VLT (covering 3 rest-frame months), are tied together photometrically to provide an estimate of the flux evolution as a function of time and wavelength. The observed bolometric peak luminosity of iPTF13ajg is 3.2x10^44 erg/s, while the estimated total radiated energy is 1.3x10^51 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 VLT. From Voigt-profile fitting, we derive the column densities log N(Mg I)=11.94+-0.06, log ...

  6. Ionization Break-Out from Millisecond Pulsar Wind Nebulae: an X-ray Probe of the Origin of Superluminous Supernovae

    CERN Document Server

    Metzger, Brian D; Hascoet, Romain; Beloborodov, Andrei M

    2013-01-01

    Magnetic spin-down of a millisecond neutron star has been proposed as the power source of hydrogen-poor "superluminous" supernovae (SLSNe-I). However, producing an unambiguous test that can distinguish this model from alternatives, such as circumstellar interaction, has proven challenging. After the supernova explosion, the pulsar wind inflates a hot cavity behind the expanding stellar ejecta: the nascent millisecond pulsar wind nebula. Electron/positron pairs injected by the wind cool through inverse Compton scattering and synchrotron emission, producing a pair cascade and hard X-ray spectrum inside the nebula. These X-rays ionize the inner exposed side of the ejecta, driving an ionization front that propagates outwards with time. Under some conditions this front can breach the ejecta surface within months after the optical supernova peak, allowing ~0.1-1 keV photons to escape the nebula unattenuated with a characteristic luminosity L_X ~ 1e43-1e45 erg/s. This "ionization break-out" may explain the luminous ...

  7. PS1-14bj: A Hydrogen-Poor Superluminous Supernova With a Long Rise and Slow Decay

    CERN Document Server

    Lunnan, R; Berger, E; Milisavljevic, D; Jones, D O; Rest, A; Fong, W; Fransson, C; Margutti, R; Drout, M R; Blanchard, P K; Challis, P; Cowperthwaite, P S; Foley, R J; Kirshner, R P; Morell, N; Riess, A G; Roth, K C; Scolnic, D; Smartt, S J; Smith, K W; Villar, V A; Chambers, K C; Draper, P W; Huber, M E; Kaiser, N; Kudritzki, R -P; Magnier, E A; Metcalfe, N; Waters, C

    2016-01-01

    We present photometry and spectroscopy of PS1-14bj, a hydrogen-poor superluminous supernova (SLSN) at redshift $z=0.5215$ discovered in the last months of the Pan-STARRS1 Medium Deep Survey. PS1-14bj stands out by its extremely slow evolution, with an observed rise to maximum light $\\gtrsim 125$ days in the rest frame, and exponential decline out to $\\sim 250$ days past peak at a measured rate of $9.75\\times 10^{-3}$ mag day$^{-1}$, consistent with fully-trapped $^{56}$Co decay. This is the longest rise time measured in a SLSN to date, and the first SLSN to show a rise time consistent with pair-instability supernova (PISN) models. Compared to other slowly-evolving SLSNe, it is spectroscopically similar to the prototype SN 2007bi at maximum light, though somewhat lower in luminosity ($L_{\\rm peak} \\simeq 4.4 \\times 10^{43}~{\\rm erg~s}^{-1}$) and with a flatter peak than previous events. In addition to its slow evolution, PS1-14bj shows a number of peculiar properties, including a near-constant color temperatur...

  8. DES14X3taz: A Type I Superluminous Supernova Showing a Luminous, Rapidly Cooling Initial Pre-Peak Bump

    CERN Document Server

    Smith, 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; Wolf, R C; Zentano, A; Abbott, T M C; Benoit-Lévy, A; Brooks, D; Buckley-Geer, E; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Crocce, M; Cunha, C E; da Costa, L N; 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; Ogando, R; Plazas, A A; 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; Thomas, R C; Walker, A R; Wester, W

    2015-01-01

    We present DES14X3taz, a new hydrogen-poor super luminous 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 (SUDSS). Spectra obtained using OSIRIS on the Gran Telescopio CANARIAS (GTC) show DES14X3taz is a 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 22,000K to 8,000K 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-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 light curve of DES14X3taz, with the coolin...

  9. Far-Ultraviolet to Near-Infrared Spectroscopy of A Nearby Hydrogen Poor Superluminous Supernova Gaia16apd

    CERN Document Server

    Yan, Lin; Gal-Yam, A; Brown, P; Blagorodnova, N; Ofek, E O; Lunnan, R; Cooke, J; Cenko, S B; Jencson, J; Kasliwal, M

    2016-01-01

    We report the first maximum-light far-Ultraviolet to near-infrared spectra (1000A - 1.62um, rest) of a H-poor superluminous supernova, Gaia16apd. At z=0.1018, it is one of the closest and the UV brightest such events, with 17.4 (AB) magnitude in Swift UV band (1928A) at -11days pre-maximum. Assuming an exponential form, we derived the rise time of 33days and the peak bolometric luminosity of 3x10^{44}ergs^-1. At maximum light, the estimated photospheric temperature and velocity are 17,000K and 14,000kms^-1 respectively. The inferred radiative and kinetic energy are roughly 1x10^{51} and 2x10^{52}erg. Gaia16apd is extremely UV luminous, emitting 50% of its total luminosity at 1000 - 2500A. Compared to the UV spectra (normalized at 3100A) of well studied SN1992A (Ia), SN2011fe(Ia), SN1999em (IIP) and SN1993J (IIb), it has orders of magnitude more far-UV emission. This excess is interpreted primarily as a result of weaker metal line blanketing due to much lower abundance of iron-group elements in the outer eject...

  10. Environmental fifth-force hypothesis for the OPERA superluminal neutrino phenomenology: constraints from orbital motions around the Earth

    CERN Document Server

    Iorio, Lorenzo

    2011-01-01

    It has been recently suggested by Dvali and Vikman [arXiv:1109.5685] that the superluminal neutrino phenomenology of the OPERA experiment may be due to an environmental feature of the Earth, naturally yielding a long-range fifth force of gravitational origin. Its scale length l should not be smaller than one Earth's radius Re, while its upper bound is expected to be slightly smaller than the Earth-Moon distance (60 Re). We analytically work out some orbital effects of a Yukawa-type fifth force for a test particle moving in the modified field of a central body. Our results are quite general since they are not restricted to any particular size of l; moreover, they are valid for an arbitrary orbital configuration of the particle, i.e. for any value of its eccentricity e. We find that the dimensionless strength coupling parameter a is constrained to |a| <= 5\\times10-10 for 1 Re <= l <= 4 Re by the laser data of the Earth's artificial satellite LAGEOS II. The Moon perigee allows to obtain |a| <= 3\\time...

  11. [Systemic lupus erythematosus and weakness].

    Science.gov (United States)

    Vinagre, Filipe; Santos, Maria José; da Silva, José Canas

    2006-01-01

    We report a case of a 13-year old young girl, with Juvenile Systemic Lupus Erythematosus and recent onset of muscle weakness. Investigations lead to the diagnosis of Myasthenia Gravis. The most important causes of muscle weakness in lupus patients are discussed.

  12. "Superluminal" FITS File Processing on Multiprocessors: Zero Time Endian Conversion Technique

    CERN Document Server

    Eguchi, Satoshi

    2013-01-01

    The FITS is the standard file format in astronomy, and it has been extended to agree with astronomical needs of the day. However, astronomical datasets have been inflating year by year. In case of ALMA telescope, a ~ TB scale 4-dimensional data cube may be produced for one target. Considering that typical Internet bandwidth is a few 10 MB/s at most, the original data cubes in FITS format are hosted on a VO server, and the region which a user is interested in should be cut out and transferred to the user (Eguchi et al., 2012). The system will equip a very high-speed disk array to process a TB scale data cube in a few 10 seconds, and disk I/O speed, endian conversion and data processing one will be comparable. Hence to reduce the endian conversion time is one of issues to realize our system. In this paper, I introduce a technique named "just-in-time endian conversion", which delays the endian conversion for each pixel just before it is really needed, to sweep out the endian conversion time; by applying this met...

  13. Hole-burning in an Autler-Townes doublet and in superluminal (subluminal) Electromagnetically induced transparency of a light pulse via a joint nonlinear coherent Kerr effect and Doppler broadening

    CERN Document Server

    Bacha, Bakhtt A; Ahmad, Iftikhar

    2013-01-01

    We investigate the behavior of light pulse propagation in a 4-level double Lambda atomic system under condition of electromagnetically induced transparency. The Fano type interference effect and spectral hole burning appears in the the dynamics of the absorption-dispersion spectra caused by the joint nonlinear coherence Kerr effect and Doppler broadening. The coherent Kerr effect exhibits an enhancement (reduction) in superluminal (subluminal) in negative (in positive) group index while the Doppler broadening generates multiple hole burning in the Autler-Townes like spectra of this system. The hole burning in addition with coherent Kerr effect on the spectral profile influences the dynamics of subluminal and superluminal of the probe pulse through the medium. The characteristics of superluminality and subluminality modified by considering cold-Kerr-free medium and hot-Kerr-dependent mediums. The light pulse delays and advances in different regions of dispersion medium with the Doppler broadening and coherent ...

  14. Measures for speed management.

    NARCIS (Netherlands)

    2009-01-01

    Measures for speed management are essential for limiting the negative effects of driving too fast and at inappropriate speeds. To begin with, safe and credible speed limits need to be determined. Dynamic and variable speed limits that take into account the current circumstances, such as weather cond

  15. High speed data converters

    CERN Document Server

    Ali, Ahmed MA

    2016-01-01

    This book covers high speed data converters from the perspective of a leading high speed ADC designer and architect, with a strong emphasis on high speed Nyquist A/D converters. For our purposes, the term 'high speed' is defined as sampling rates that are greater than 10 MS/s.

  16. 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.

  17. Strong and Weak Property of Travelling Wave Front Solutions for a Class of Degenerate Parabolic Equations

    Institute of Scientific and Technical Information of China (English)

    LI Zheng-yuan; LIU Ying-dong; YE Qi-xiao

    2001-01-01

    In this paper we study the strong and weak property of travelling wave front solutions for a class of degenerate parabolic equations. How the strong and weak property changes under the effects of wave speed and reaction-diffusion terms are showed.

  18. Analytical Light Curve Models of Super-Luminous Supernvae: chi^2-Minimizations of Parameter Fits

    CERN Document Server

    Chatzopoulos, E; Vinko, J; Horvath, Z L; Nagy, A

    2013-01-01

    We present fits of generalized semi-analytic supernova (SN) light curve (LC) models for a variety of power inputs including Ni-56 and Co-56 radioactive decay, magnetar spin-down, and forward and reverse shock heating due to supernova ejecta-circumstellar matter (CSM) interaction. We apply our models to the observed LCs of the H-rich Super Luminous Supernovae (SLSN-II) SN 2006gy, SN 2006tf, SN 2008am, SN 2008es, CSS100217, the H-poor SLSN-I SN 2005ap, SCP06F6, SN 2007bi, SN 2010gx and SN 2010kd as well as to the interacting SN 2008iy and PTF09uj. Our goal is to determine the dominant mechanism that powers the LCs of these extraordinary events and the physical conditions involved in each case. We also present a comparison of our semi-analytical results with recent results from numerical radiation hydrodynamics calculations in the particular case of SN 2006gy in order to explore the strengths and weaknesses of our models. We find that CS shock heating produced by ejecta-CSM interaction provides a better fit to t...

  19. The Unexpected, Long-Lasting, UV Rebrightening of the Super-Luminous Supernova ASASSN-15lh

    CERN Document Server

    Godoy-Rivera, D; Kochanek, C S; Chen, Ping; Dong, Subo; Prieto, J L; Shappee, B J; Jha, S W; Foley, R J; Pan, Y -C; Holoien, T W -S; Thompson, Todd A; Grupe, D; Beacom, J F

    2016-01-01

    ASASSN-15lh is the most luminous supernova (SN) ever discovered (Dong et al. 2016), based on its peak bolometric luminosity. Here we report a UV rebrightening of ASASSN-15lh observed with {\\it Swift} during our follow-up photometric campaign. The rebrightening began at $t \\simeq 90$ days (observer frame) after the primary peak and was followed by a $\\sim 120$-day long plateau in the bolometric luminosity, before starting to fade again at $t\\simeq 210$ days. The SN rebrightened in the {\\it Swift} UV bands by $\\Delta m_{UVW2} \\simeq -1.75$ mag, $\\Delta m_{UVM2} \\simeq -1.25$ mag, and $\\Delta m_{UVW1} \\simeq -0.8$ mag, but did not rebrighten in the optical bands. Throughout its initial decline, subsequent rebrightening, and renewed decline, the spectra of ASASSN-15lh did not show evidence of interactions between the ejecta and circumstellar medium (CSM) such as narrow emission lines. There are hints of weak, broad, transient H$\\alpha$ emission at late times, but the feature could also be an artifact. By fitting ...

  20. PS1-10bzj: A FAST, HYDROGEN-POOR SUPERLUMINOUS SUPERNOVA IN A METAL-POOR HOST GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Lunnan, R.; Chornock, R.; Berger, E.; Milisavljevic, D.; Drout, M.; Sanders, N. E.; Challis, P. M.; Czekala, I.; Foley, R. J.; Fong, W.; Kirshner, R. P.; Leibler, C.; Marion, G. H.; Narayan, G. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Huber, M. E. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); McCrum, M.; Smartt, S. J. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Rest, A. [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Roth, K. C. [Gemini Observatory, 670 N. Aohoku Place, Hilo, HI 96720 (United States); Scolnic, D., E-mail: rlunnan@cfa.harvard.edu [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); and others

    2013-07-10

    We present observations and analysis of PS1-10bzj, a superluminous supernova (SLSN) discovered in the Pan-STARRS Medium Deep Survey at a redshift z = 0.650. Spectroscopically, PS1-10bzj is similar to the hydrogen-poor SLSNe 2005ap and SCP 06F6, though with a steeper rise and lower peak luminosity (M{sub bol} {approx_equal} -21.4 mag) than previous events. We construct a bolometric light curve, and show that while PS1-10bzj's energetics were less extreme than previous events, its luminosity still cannot be explained by radioactive nickel decay alone. We explore both a magnetar spin-down and circumstellar interaction scenario and find that either can fit the data. PS1-10bzj is located in the Extended Chandra Deep Field South and the host galaxy is imaged in a number of surveys, including with the Hubble Space Telescope. The host is a compact dwarf galaxy (M{sub B} Almost-Equal-To -18 mag, diameter {approx}< 800 pc), with a low stellar mass (M{sub *} Almost-Equal-To 2.4 Multiplication-Sign 10{sup 7} M{sub Sun }), young stellar population ({tau}{sub *} Almost-Equal-To 5 Myr), and a star formation rate of {approx}2-3 M{sub Sun} yr{sup -1}. The specific star formation rate is the highest seen in an SLSN host so far ({approx}100 Gyr{sup -1}). We detect the [O III] {lambda}4363 line, and find a low metallicity: 12 + (O/H) = 7.8 {+-} 0.2 ({approx_equal} 0.1 Z{sub Sun }). Together, this indicates that at least some of the progenitors of SLSNe come from young, low-metallicity populations.

  1. Taking stock of superluminous supernovae and long gamma-ray burst host galaxy comparison using a complete sample of LGRBs

    Science.gov (United States)

    Japelj, J.; Vergani, S. D.; Salvaterra, R.; Hunt, L. K.; Mannucci, F.

    2016-10-01

    Long gamma-ray bursts (LGRBs) and superluminous supernovae (SLSNe) are both explosive transients with very massive progenitor stars. Clues about the nature of the progenitors can be found by investigating environments in which such transients occur. While studies of LGRB host galaxies have a long history, dedicated observational campaigns have only recently resulted in a high enough number of photometrically and spectroscopically observed SLSN hosts to allow statistically significant analysis of their properties. In this paper we make a comparison of the host galaxies of hydrogen-poor (H-poor) SLSNe and the Swift/BAT6 sample of LGRBs. In contrast to previous studies, we use a complete sample of LGRBs and we pay special attention to the comparison methodology and the selection of SLSN sample whose data have been compiled from the available literature. At intermediate redshifts (0.3 < z < 0.7) the two classes of transients select galaxies whose properties (stellar mass, luminosity, star formation rate, specific star formation rate and metallicity) do not differ significantly. Moreover, the host galaxies of both classes of objects follow the fundamental metallicity relation and the fundamental plane of metallicity. In contrast to previous studies we show that at intermediate redshifts the emission line equivalent widths of the two populations are essentially the same and that the previous claims regarding the higher fraction of SLSN hosts among the extreme emission line galaxies with respect to LGRBs are mostly due to a larger fraction of strong-line emitters among SLSN hosts at z < 0.3, where samples of LGRB hosts are small and poorly defined.

  2. Hydrogen-poor superluminous supernovae and long-duration gamma-ray bursts have similar host galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Lunnan, R.; Chornock, R.; Berger, E.; Laskar, T.; Fong, W.; Sanders, N. E.; Challis, P. M.; Drout, M. R.; Foley, R. J.; Kirshner, R. P.; Leibler, C.; Marion, G. H.; Milisavljevic, D.; Narayan, G. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Rest, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Huber, M. E. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); McCrum, M.; Smartt, S. J.; Smith, K. W. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Scolnic, D., E-mail: rlunnan@cfa.harvard.edu [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); and others

    2014-06-01

    We present optical spectroscopy and optical/near-IR photometry of 31 host galaxies of hydrogen-poor superluminous supernovae (SLSNe), including 15 events from the Pan-STARRS1 Medium Deep Survey. Our sample spans the redshift range 0.1 ≲ z ≲ 1.6, and is the first comprehensive host galaxy study of this specific subclass of cosmic explosions. Combining the multi-band photometry and emission-line measurements, we determine the luminosities, stellar masses, star formation rates, and metallicities. We find that, as a whole, the hosts of SLSNe are a low-luminosity ((M{sub B} ) ≈ –17.3 mag), low stellar mass ((M {sub *}) ≈ 2 × 10{sup 8} M {sub ☉}) population, with a high median specific star formation rate ((sSFR) ≈ 2 Gyr{sup –1}). The median metallicity of our spectroscopic sample is low, 12 + log (O/H) ≈ 8.35 ≈ 0.45 Z {sub ☉}, although at least one host galaxy has solar metallicity. The host galaxies of H-poor SLSNe are statistically distinct from the hosts of GOODS core-collapse SNe (which cover a similar redshift range), but resemble the host galaxies of long-duration gamma-ray bursts (LGRBs) in terms of stellar mass, SFR, sSFR, and metallicity. This result indicates that the environmental causes leading to massive stars forming either SLSNe or LGRBs are similar, and in particular that SLSNe are more effectively formed in low metallicity environments. We speculate that the key ingredient is large core angular momentum, leading to a rapidly spinning magnetar in SLSNe and an accreting black hole in LGRBs.

  3. Precision Metrology Using Weak Measurements

    Science.gov (United States)

    Zhang, Lijian; Datta, Animesh; Walmsley, Ian A.

    2015-05-01

    Weak values and measurements have been proposed as a means to achieve dramatic enhancements in metrology based on the greatly increased range of possible measurement outcomes. Unfortunately, the very large values of measurement outcomes occur with highly suppressed probabilities. This raises three vital questions in weak-measurement-based metrology. Namely, (Q1) Does postselection enhance the measurement precision? (Q2) Does weak measurement offer better precision than strong measurement? (Q3) Is it possible to beat the standard quantum limit or to achieve the Heisenberg limit with weak measurement using only classical resources? We analyze these questions for two prototypical, and generic, measurement protocols and show that while the answers to the first two questions are negative for both protocols, the answer to the last is affirmative for measurements with phase-space interactions, and negative for configuration space interactions. Our results, particularly the ability of weak measurements to perform at par with strong measurements in some cases, are instructive for the design of weak-measurement-based protocols for quantum metrology.

  4. Precision metrology using weak measurements.

    Science.gov (United States)

    Zhang, Lijian; Datta, Animesh; Walmsley, Ian A

    2015-05-29

    Weak values and measurements have been proposed as a means to achieve dramatic enhancements in metrology based on the greatly increased range of possible measurement outcomes. Unfortunately, the very large values of measurement outcomes occur with highly suppressed probabilities. This raises three vital questions in weak-measurement-based metrology. Namely, (Q1) Does postselection enhance the measurement precision? (Q2) Does weak measurement offer better precision than strong measurement? (Q3) Is it possible to beat the standard quantum limit or to achieve the Heisenberg limit with weak measurement using only classical resources? We analyze these questions for two prototypical, and generic, measurement protocols and show that while the answers to the first two questions are negative for both protocols, the answer to the last is affirmative for measurements with phase-space interactions, and negative for configuration space interactions. Our results, particularly the ability of weak measurements to perform at par with strong measurements in some cases, are instructive for the design of weak-measurement-based protocols for quantum metrology.

  5. Acute muscular weakness in children

    Directory of Open Access Journals (Sweden)

    Ricardo Pablo Javier Erazo Torricelli

    Full Text Available ABSTRACT Acute muscle weakness in children is a pediatric emergency. During the diagnostic approach, it is crucial to obtain a detailed case history, including: onset of weakness, history of associated febrile states, ingestion of toxic substances/toxins, immunizations, and family history. Neurological examination must be meticulous as well. In this review, we describe the most common diseases related to acute muscle weakness, grouped into the site of origin (from the upper motor neuron to the motor unit. Early detection of hyperCKemia may lead to a myositis diagnosis, and hypokalemia points to the diagnosis of periodic paralysis. Ophthalmoparesis, ptosis and bulbar signs are suggestive of myasthenia gravis or botulism. Distal weakness and hyporeflexia are clinical features of Guillain-Barré syndrome, the most frequent cause of acute muscle weakness. If all studies are normal, a psychogenic cause should be considered. Finding the etiology of acute muscle weakness is essential to execute treatment in a timely manner, improving the prognosis of affected children.

  6. Possible Origin Of The Neutrino Speed Anomaly Reported By OPERA

    CERN Document Server

    Dado, Shlomo

    2011-01-01

    Recently the OPERA collaboration reported a measurement of a superluminal speed of muon neutrinos travelling through the Earth's crust between their production site at CERN and their detection site under Gran Sasso, ~730 km away. The measurement was based on the assumption that the pulse shape of the neutrinos from the decay of parent mesons produced in proton-target collisions is the same as that of the incident protons. Here we argue that the effective column density of the target along the beam direction decreases with time during the 10.5 microseconds duration of the proton pulse. This is because of the thermal expansion and expulsion of target material along the beam by the energy-momentum deposition during the 10.5 microseconds pulse. The progresive reduction in the effective column density during the pulse decreases the neutrino production rate per incident proton. It could have advanced the mean production time of the detected neutrinos relative to that calculated from the proton pulse-shape, by an am...

  7. Weakness

    Science.gov (United States)

    ... stroke After injury to a nerve During a flare-up of multiple sclerosis (MS) You may feel ... Duchenne) Myotonic dystrophy POISONING Botulism Poisoning ( insecticides , nerve gas) Shellfish poisoning OTHER Not enough healthy red blood ...

  8. Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects Superluminal Motion of Gamma-Ray Bright Blazars

    CERN Document Server

    Jorstad, S G; Mattox, J R; Wehrle, A E; Bloom, S D; Yurchenko, A V; Jorstad, Svetlana G; Marscher, Alan P; Mattox, John R; Wehrle, Ann E; Bloom, Steven D; Yurchenko, Alexei V

    2001-01-01

    We present the results of a program to monitor the structure of the radio emission in 42 $\\gamma$-ray bright blazars (31 quasars and 11 BL Lac objects) with the VLBA at 43, 22, and occasionally 15 and 8.4 GHz, over the period from November 1993 to July 1997. We determine proper motions in 33 sources and find that the apparent superluminal motions in $\\gamma$-ray sources are much faster than for the general population of bright compact radio sources. This follows the strong dependence of the $\\gamma$-ray flux on the level of relativistic beaming for both external-radiation Compton and synchrotron self-Compton emission. There is a positive correlation (correlation coefficient $r$=0.45) between the flux density of the VLBI core and the $\\gamma$-ray flux and a moderate correlation (partial correlation coefficient $r$=0.31) between $\\gamma$-ray apparent luminosity and superluminal velocities of jet components, as expected if the $\\gamma$-ray emission originates in a very compact region of the relativistic jet and ...

  9. Peripheral facial weakness (Bell's palsy).

    Science.gov (United States)

    Basić-Kes, Vanja; Dobrota, Vesna Dermanović; Cesarik, Marijan; Matovina, Lucija Zadro; Madzar, Zrinko; Zavoreo, Iris; Demarin, Vida

    2013-06-01

    Peripheral facial weakness is a facial nerve damage that results in muscle weakness on one side of the face. It may be idiopathic (Bell's palsy) or may have a detectable cause. Almost 80% of peripheral facial weakness cases are primary and the rest of them are secondary. The most frequent causes of secondary peripheral facial weakness are systemic viral infections, trauma, surgery, diabetes, local infections, tumor, immune disorders, drugs, degenerative diseases of the central nervous system, etc. The diagnosis relies upon the presence of typical signs and symptoms, blood chemistry tests, cerebrospinal fluid investigations, nerve conduction studies and neuroimaging methods (cerebral MRI, x-ray of the skull and mastoid). Treatment of secondary peripheral facial weakness is based on therapy for the underlying disorder, unlike the treatment of Bell's palsy that is controversial due to the lack of large, randomized, controlled, prospective studies. There are some indications that steroids or antiviral agents are beneficial but there are also studies that show no beneficial effect. Additional treatments include eye protection, physiotherapy, acupuncture, botulinum toxin, or surgery. Bell's palsy has a benign prognosis with complete recovery in about 80% of patients, 15% experience some mode of permanent nerve damage and severe consequences remain in 5% of patients.

  10. Warping the Weak Gravity Conjecture

    Directory of Open Access Journals (Sweden)

    Karta Kooner

    2016-08-01

    Full Text Available The Weak Gravity Conjecture, if valid, rules out simple models of Natural Inflation by restricting their axion decay constant to be sub-Planckian. We revisit stringy attempts to realise Natural Inflation, with a single open string axionic inflaton from a probe D-brane in a warped throat. We show that warped geometries can allow the requisite super-Planckian axion decay constant to be achieved, within the supergravity approximation and consistently with the Weak Gravity Conjecture. Preliminary estimates of the brane backreaction suggest that the probe approximation may be under control. However, there is a tension between large axion decay constant and high string scale, where the requisite high string scale is difficult to achieve in all attempts to realise large field inflation using perturbative string theory. We comment on the Generalized Weak Gravity Conjecture in the light of our results.

  11. Interpolation for weak Orlicz spaces with condition

    Institute of Scientific and Technical Information of China (English)

    JIAO Yong; PENG LiHua; LIU PeiDe

    2008-01-01

    An interpolation theorem for weak Orlicz spaces generalized by N-functions satisfying M△ condition is given.It is proved to be true for weak Orlicz martingale spaces by weak atomic decomposition of weak Hardy martingale spaces.And applying the interpolation theorem,we obtain some embedding relationships among weak Orlicz martingale spaces.

  12. Electromagnetism in nonleptonic weak interactions

    Energy Technology Data Exchange (ETDEWEB)

    Ecker, G. E-mail: ecker@doppler.thp.univie.ac.at; Isidori, G.; Mueller, G.; Neufeld, H.; Pich, A

    2000-12-18

    We construct a low-energy effective field theory that permits the complete treatment of isospin-breaking effects in nonleptonic weak interactions to next-to-leading order. To this end, we enlarge the chiral Lagrangian describing strong and {delta}S=1 weak interactions by including electromagnetic terms with the photon as additional dynamical degree of freedom. The complete and minimal list of local terms at next-to-leading order is given. We perform the one-loop renormalization at the level of the generating functional and specialize to K{yields}{pi}{pi} decays.

  13. Cosmology and the weak interaction

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, D.N. (Fermi National Accelerator Lab., Batavia, IL (USA)):(Chicago Univ., IL (USA))

    1989-12-01

    The weak interaction plays a critical role in modern Big Bang cosmology. This review will emphasize two of its most publicized cosmological connections: Big Bang nucleosynthesis and Dark Matter. The first of these is connected to the cosmological prediction of Neutrino Flavours, N{sub {nu}} {approximately} 3 which is now being confirmed at SLC and LEP. The second is interrelated to the whole problem of galaxy and structure formation in the universe. This review will demonstrate the role of the weak interaction both for dark matter candidates and for the problem of generating seeds to form structure. 87 refs., 3 figs., 5 tabs.

  14. Weak disorder in Fibonacci sequences

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Naim, E [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Krapivsky, P L [Department of Physics and Center for Molecular Cybernetics, Boston University, Boston, MA 02215 (United States)

    2006-05-19

    We study how weak disorder affects the growth of the Fibonacci series. We introduce a family of stochastic sequences that grow by the normal Fibonacci recursion with probability 1 - {epsilon}, but follow a different recursion rule with a small probability {epsilon}. We focus on the weak disorder limit and obtain the Lyapunov exponent that characterizes the typical growth of the sequence elements, using perturbation theory. The limiting distribution for the ratio of consecutive sequence elements is obtained as well. A number of variations to the basic Fibonacci recursion including shift, doubling and copying are considered. (letter to the editor)

  15. The cohomology group of weak entwining structure

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, we reveal that a weak entwining structure admits a rich cohomology theory. As an application we compute the cohomology of a weak entwining structure associated to a weak coalgebra-Galois extension.

  16. DETECTION OF BROAD Hα EMISSION LINES IN THE LATE-TIME SPECTRA OF A HYDROGEN-POOR SUPERLUMINOUS SUPERNOVA

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Lin; Masci, F. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Quimby, R. [Department of Astronomy, San Diego State University, San Diego, CA 92182 (United States); Ofek, E.; Gal-Yam, A.; Vreeswijk, P. M.; Leloudas, G.; Cia, A. de; Yaron, O. [Department of Particle Physics and Astrophysics, Faculty of Physics, The Weizmann Institute of Science, Rehovot 76100 (Israel); Mazzali, P. [Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Perley, D. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Cenko, S. B. [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Cao, Y.; Kulkarni, S. R. [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Nugent, P. E. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Rebbapragada, Umaa D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Woźniak, P. R., E-mail: lyan@ipac.caltech.edu [Space and Remote Sensing, ISR-2, MS-B244 Los Alamos National Laboratory Los Alamos, NM 87545 (United States)

    2015-12-01

    iPTF13ehe is a hydrogen-poor superluminous supernova (SLSN) at z = 0.3434, with a slow-evolving light curve and spectral features similar to SN2007bi. It rises in 83–148 days to reach a peak bolometric luminosity of ∼1.3 × 10{sup 44} erg s{sup −1}, then decays slowly at 0.015 mag day{sup −1}. The measured ejecta velocity is ∼ 13,000 km s{sup −1}. The inferred explosion characteristics, such as the ejecta mass (70–220 M{sub ⊙}), and the total radiative and kinetic energy (E{sub rad} ∼ 10{sup 51} erg, E{sub kin} ∼ 2 × 10{sup 53} erg), are typical of slow-evolving H-poor SLSN events. However, the late-time spectrum taken at +251 days (rest, post-peak) reveals a Balmer Hα emission feature with broad and narrow components, which has never been detected before among other H-poor SLSNe. The broad component has a velocity width of ∼4500 km s{sup −1} and a ∼300 km s{sup −1} blueward shift relative to the narrow component. We interpret this broad Hα emission with a luminosity of ∼2 × 10{sup 41} erg s{sup −1} as resulting from the interaction between the supernova ejecta and a discrete H-rich shell, located at a distance of ∼4 × 10{sup 16} cm from the explosion site. This interaction causes the rest-frame r-band LC to brighten at late times. The fact that the late-time spectra are not completely absorbed by the shock-ionized H-shell implies that its Thomson scattering optical depth is likely ≤1, thus setting upper limits on the shell mass ≤30 M{sub ⊙}. Of the existing models, a Pulsational Pair Instability supernova model can naturally explain the observed 30 M{sub ⊙} H-shell, ejected from a progenitor star with an initial mass of (95–150) M{sub ⊙} about 40 years ago. We estimate that at least ∼15% of all SLSNe-I may have late-time Balmer emission lines.

  17. 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.

  18. Speed in Acquisitions

    DEFF Research Database (Denmark)

    Meglio, Olimpia; King, David R.; Risberg, Annette

    2017-01-01

    The advantage of speed is often invoked by academics and practitioners as an essential condition during post-acquisition integration, frequently without consideration of the impact earlier decisions have on acquisition speed. In this article, we examine the role speed plays in acquisitions across...... the acquisition process using research organized around characteristics that display complexity with respect to acquisition speed. We incorporate existing research with a process perspective of acquisitions in order to present trade-offs, and consider the influence of both stakeholders and the pre......-deal-completion context on acquisition speed, as well as the organization’s capabilities to facilitating that speed. Observed trade-offs suggest both that acquisition speed often requires longer planning time before an acquisition and that associated decisions require managerial judgement. A framework for improving...

  19. Second threshold in weak interactions

    NARCIS (Netherlands)

    Veltman, M.J.G.

    1977-01-01

    The point of view that weak interactions must have a second threshold below 300 – 600 GeV is developed. Above this threshold new physics must come in. This new physics may be the Higgs system, or some other nonperturbative system possibly having some similarities to the Higgs system. The limit of la

  20. Beam splitting on weak illumination.

    Science.gov (United States)

    Snyder, A W; Buryak, A V; Mitchell, D J

    1998-01-01

    We demonstrate, in both two and three dimensions, how a self-guided beam in a non-Kerr medium is split into two beams on weak illumination. We also provide an elegant physical explanation that predicts the universal character of the observed phenomenon. Possible applications of our findings to guiding light with light are also discussed.

  1. On Weak-BCC-Algebras

    Science.gov (United States)

    Thomys, Janus; Zhang, Xiaohong

    2013-01-01

    We describe weak-BCC-algebras (also called BZ-algebras) in which the condition (x∗y)∗z = (x∗z)∗y is satisfied only in the case when elements x, y belong to the same branch. We also characterize ideals, nilradicals, and nilpotent elements of such algebras. PMID:24311983

  2. Eldercare at Home: Bone Weakness

    Science.gov (United States)

    ... socialize. This can make exercising fun. If you don't exercise, your bones and muscles will become weak and your chances of falling will increase. Let’s exercise together. I will pick you up and we will go to the mall and walk for a little ...

  3. Submanifolds Weakly Associated with Graphs

    Indian Academy of Sciences (India)

    A Carriazo; L M Fernández; A Rodríguez-Hidalgo

    2009-06-01

    We establish an interesting link between differential geometry and graph theory by defining submanifolds weakly associated with graphs. We prove that, in a local sense, every submanifold satisfies such an association, and other general results. Finally, we study submanifolds associated with graphs either in low dimensions or belonging to some special families.

  4. On the weak project construction cost management

    Institute of Scientific and Technical Information of China (English)

    高守刚; 姜婧; 李玲

    2013-01-01

    the weak cost management is the most talked about topics in the weak industry, but also the basis of the weak construction business management and focus. With the increasingly fierce market competition, weak construction enterprises, the competition among enterprises wil gradual y transition from product quality competition to price competition. To strengthen the management of the weak construction enterprises cost, cut public spending ef iciency, improve market competitiveness, wil be the main way most weak construction corporate earnings and long-term business strategy. Based on the to weak project construction cost management based on analysis of the type of project construction costs, and further proposed the weak project construction cost management measures.

  5. 46 CFR 154.1864 - Vessel speed within speed reduction.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Vessel speed within speed reduction. 154.1864 Section... Vessel speed within speed reduction. The master shall ensure that the speed of the vessel is not greater than the posted speed reduction....

  6. The Weak Scale from BBN

    CERN Document Server

    Hall, Lawrence J; Ruderman, Joshua T

    2014-01-01

    The measured values of the weak scale, $v$, and the first generation masses, $m_{u,d,e}$, are simultaneously explained in the multiverse, with all these parameters scanning independently. At the same time, several remarkable coincidences are understood. Small variations in these parameters away from their measured values lead to the instability of hydrogen, the instability of heavy nuclei, and either a hydrogen or a helium dominated universe from Big Bang Nucleosynthesis. In the 4d parameter space of $(m_u,m_d,m_e,v)$, catastrophic boundaries are reached by separately increasing each parameter above its measured value by a factor of $(1.4,1.3,2.5,\\sim5)$, respectively. The fine-tuning problem of the weak scale in the Standard Model is solved: as $v$ is increased beyond the observed value, it is impossible to maintain a significant cosmological hydrogen abundance for any values of $m_{u,d,e}$ that yield both hydrogen and heavy nuclei stability. For very large values of $v$ a new regime is entered where weak in...

  7. Speed enforcement in Norway

    DEFF Research Database (Denmark)

    Elvik, Rune

    2015-01-01

    This paper probes the relationship between changes in the risk of apprehension for speeding in Norway and changes in the amount of speeding. The paper is based on a game-theoretic model of how the rate of violations and the amount of enforcement is determined by the interaction between drivers...

  8. Speed and income

    DEFF Research Database (Denmark)

    Fosgerau, Mogens

    2005-01-01

    between speed and income is found again in the empirical analysis of a cross-sectional dataset comprising 60,000 observations of car trips. This is used to perform regressions of speed on income, distance travelled, and a number of controls. The results are clearly statistically significant and indicate...

  9. More Than Just Speed

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The 1,318-km Beijing-Shanghai High-Speed Railway will finally come into operation at the end of June.Since construction began three years ago,the speedy railway has grabbed worldwide attention because of its design as the world’s longest and fastesthigh-speed rail line utilizing the most advanced technology.

  10. Effectiveness of Motorcycle speed controlled by speed hump

    Directory of Open Access Journals (Sweden)

    Pornsiri Urapa

    2014-09-01

    Full Text Available Speed humps are one of the traffic calming measures widely accepted to control vehicle speed in the local road. Humps standards from the western countries are designed mainly for the passenger car. This study, therefore, aims to reveal the effectiveness of speed hump to control the motorcycle speed. This study observes the free-flow speed of the riders at the total of 20 speed bumps and humps. They are 0.3-14.8 meter in width and 5-18 centimeter in height. The results reveal that the 85th percentile speeds reduce 15-65 percent when crossing the speed bumps and speed humps. Besides, this study develops the speed model to predict the motorcycle mean speed and 85th percentile speed. It is found that speed humps follow the ITE standard can control motorcycle crossing speeds to be 25-30 Kph which are suitable to travel on the local road.

  11. Strengths, weaknesses, opportunities and threats

    DEFF Research Database (Denmark)

    Bull, J. W.; Jobstvogt, N.; Böhnke-Henrichs, A.;

    2016-01-01

    environmental awareness. Threats include resistance to change, and difficulty with interdisciplinary collaboration. Consideration of SWOT themes suggested five strategic areas for developing and implementing ES.The ES concept could improve decision-making related to natural resource use, and interpretation...... facilitate interdisciplinary research, ensuring decision-making that supports sustainable development........ Such an assessment could form the basis for improving ES thinking, further embedding it into environmental decisions and management.The Young Ecosystem Services Specialists (YESS) completed a Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis of ES through YESS member surveys. Strengths include the approach...

  12. Weak Precedence Story Parsing Grammar

    Institute of Scientific and Technical Information of China (English)

    张松懋

    1995-01-01

    Story understanding is one of the important branches of natural language understanding research in AI techniques.The story understanding approach based on Story Parsing Grammar (SPG) involves that SPG is used to represent different abstracting processes of stories with different levels in story understanding and that the story understanding process is converted to the recognition process of stories using the syntactic parser of SPG.This kind of story understanding is called story parsing.In this paper,firstly a subclass of SPG,called Weak Precedence SPG(WPSPG),is defined.Afterwards the syntactic parsing algorithm of WPSPG is studied.An example of story parsing is also given.

  13. Weakly distributive domains(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    JIANG Ying; ZHANG Guo-Qiang

    2007-01-01

    In our previous work(Inform.and Comput.,2005,202:87-103),we have shown that for any ω-algebraic meet-cpo D,if all higher-order stable function spaces built from D are ω-algebraic,then D is finitary.This accomplishes the first of a possible,two-step process in solving the problem raised(LNCS,1991,530:16-33;Domainsand lambda-calculi,Cambridge Univ.Press,1998)whetherthe category of stable bifinite domains of Amadio-Droste-G(o)bel(LNCS,1991,530:16-33;Theor.Comput.Sci.,1993,111:89-101)is the largest cartesian closed full subcategory within the category of ω-algebraic meet-cpos with stable functions.This paper presents the results of the second step,which is to show that for any ω-algebraic meet-cpo D satisfying axioms M and I to be contained in a cartesian closed full sub-category using ω-algebraic meet-cpos with stable functions,it must not violate M I∞.We introduce a new class of domains called weakly distributive domains and show that for these domains to be in a cartesian closed category using ω-algebraic meet-cpos,property M I must not be violated.Further,we demonstrate that principally distributive domains(those for which each principle ideal is distributive)form a proper subclass of weakly distributive domains,and Birkhoff's M3 and N5(Introduction to Lattices and order,Cambridge Univ.Press,2002)are weakly distributive(but non-distributive).Then,we establish characterization results for weakly distributive domains.We also introduce the notion of meet-generators in constructing stable functions and show that if an ω-algebraic meet-cpo D contains an infinite number of meet-generators,then[D→D]fails I.However,the original problem of Amadio and Curien remains open.

  14. Speed and structure of turbulent fronts in pipe flow

    CERN Document Server

    Song, Baofang; Hof, Björn; Avila, Marc

    2016-01-01

    The dynamics of laminar-turbulent fronts in pipe flow is investigated for Reynolds numbers between Re=1900 and Re=5500 using extensive direct numerical simulations. In this range the flow undergoes a continuous transition from localised puffs to weakly expanding and ultimately to strongly expanding turbulent slugs (Barkley et al. 2015). We here investigate the physical distinction between these two types of slug by analysing time-resolved statistics of their downstream fronts in the frame moving at the bulk turbulent advection speed. While weak fronts travel slower than the bulk turbulent advection speed, implying local relaminarisation, strong fronts travel faster and so feed on the laminar flow ahead. At Re$\\approx$2900 the downstream front speed becomes faster than the advection speed, marking the onset of strong fronts. We argue that large temporal fluctuations of production and dissipation at the laminar-turbulent interface drive the dynamical switches between the two types of front observed up to Re$\\si...

  15. Superluminous Spiral Galaxies

    CERN Document Server

    Ogle, Patrick M; Nader, Cyril; Helou, George

    2015-01-01

    We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster galaxies, with r-band monochromatic luminosity L_r=8-14L* (4.3-7.5E44 erg/s). These super spiral galaxies are also giant and massive, with diameter D=57-134 kpc and stellar mass M_stars=0.3-3.4E11 M_sun. We find 53 super spirals out of a complete sample of 1,616 SDSS galaxies with redshift z8L*. The closest example is found at z=0.089. We use existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS and WISE colors are consistent with normal star-forming spirals on the blue sequence. However, the extreme masses and rapid SFRs of 5-65 M_sun/yr place super spirals in a sparsely populated region of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a diverse range of environments, from isolation to cluster centers. We find four super spiral galaxy systems that are late-stage major mergers--a possible clue to their formation. We su...

  16. SUPERLUMINOUS SPIRAL GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Ogle, Patrick M.; Lanz, Lauranne; Nader, Cyril; Helou, George, E-mail: ogle@ipac.caltech.edu [IPAC, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91125 (United States)

    2016-02-01

    We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster galaxies, with r-band monochromatic luminosity L{sub r} = 8–14L* (4.3–7.5 × 10{sup 44} erg s{sup −1}). These super spiral galaxies are also giant and massive, with diameter D = 57–134 kpc and stellar mass M{sub stars} = 0.3–3.4 × 10{sup 11}M{sub ⊙}. We find 53 super spirals out of a complete sample of 1616 SDSS galaxies with redshift z < 0.3 and L{sub r} > 8L*. The closest example is found at z = 0.089. We use existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS and Wide-field Infrared Survey Explorer colors are consistent with normal star-forming spirals on the blue sequence. However, the extreme masses and rapid SFRs of 5–65 M{sub ⊙} yr{sup −1} place super spirals in a sparsely populated region of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a diverse range of environments, from isolation to cluster centers. We find four super spiral galaxy systems that are late-stage major mergers—a possible clue to their formation. We suggest that super spirals are a remnant population of unquenched, massive disk galaxies. They may eventually become massive lenticular galaxies after they are cut off from their gas supply and their disks fade.

  17. Blazar Jets Push Closer to Cosmic Speed Limit

    Science.gov (United States)

    2005-01-01

    the three blazars as having potentially very high jet speeds based on VLBA observations in the mid-1990s. Piner and his colleagues observed the blazars again in 2002 and 2003 with much longer observations, and were able to confirm the high-speed motions in the faint blazar jets. Their measurements showed that features in the blazar jets were moving at apparent speeds more than 25 times greater than that of light. This phenomenon, called superluminal motion, is not real, but rather is an illusion caused by the fact that the material in the jet is moving at nearly the speed of light almost directly toward the observer. Because the jet features are moving toward Earth at almost the same speed as the radio waves they emit, they can appear to move across the sky at faster-than-light speeds. Scientists can correct for this geometrical effect to calculate a lower limit to the true speed of the features. "We typically see apparent speeds in blazar jets that are about five times the speed of light, and that corresponds to a true speed of more than 98 percent of light speed," Piner said. "Now, based on independent confirmation by two groups of astronomers, we see these three blazars with apparent speeds greater than 25 times that of light," Piner added. That apparent speed, the scientists said, corresponds to a true speed of greater than 99.9 percent of light speed, which is 186,282 miles per second. Based on other properties of blazars, the scientists believe that their interpretation of the data is accurate and that they have measured the extremely fast speeds in the three blazar jets. However, "we do have to be somewhat careful in interpreting these results, because it is possible that the observed motions represent the motion of some propagating disturbance in the plasma rather than the plasma itself, in the same way that a water wave can move across the surface of the ocean without physically transporting the water," Piner said. The VLBA is a system of ten radio

  18. Weakly circadian cells improve resynchrony.

    Directory of Open Access Journals (Sweden)

    Alexis B Webb

    Full Text Available The mammalian suprachiasmatic nuclei (SCN contain thousands of neurons capable of generating near 24-h rhythms. When isolated from their network, SCN neurons exhibit a range of oscillatory phenotypes: sustained or damping oscillations, or arrhythmic patterns. The implications of this variability are unknown. Experimentally, we found that cells within SCN explants recover from pharmacologically-induced desynchrony by re-establishing rhythmicity and synchrony in waves, independent of their intrinsic circadian period We therefore hypothesized that a cell's location within the network may also critically determine its resynchronization. To test this, we employed a deterministic, mechanistic model of circadian oscillators where we could independently control cell-intrinsic and network-connectivity parameters. We found that small changes in key parameters produced the full range of oscillatory phenotypes seen in biological cells, including similar distributions of period, amplitude and ability to cycle. The model also predicted that weaker oscillators could adjust their phase more readily than stronger oscillators. Using these model cells we explored potential biological consequences of their number and placement within the network. We found that the population synchronized to a higher degree when weak oscillators were at highly connected nodes within the network. A mathematically independent phase-amplitude model reproduced these findings. Thus, small differences in cell-intrinsic parameters contribute to large changes in the oscillatory ability of a cell, but the location of weak oscillators within the network also critically shapes the degree of synchronization for the population.

  19. Optimal Weak Lensing Skewness Measurements

    CERN Document Server

    Zhang, T J; Zhang, P; Dubinski, J; Zhang, Tong-Jie; Pen, Ue-Li; Zhang, Pengjie; Dubinski, John

    2003-01-01

    Weak lensing measurements are entering a precision era to statistically map the distribution of matter in the universe. The most common measurement has been of the variance of the projected surface density of matter, which corresponds to the induced correlation in alignments of background galaxies. This measurement of the fluctuations is insensitive to the total mass content, like using waves on the ocean to measure its depths. But when the depth is shallow as happens near a beach, waves become skewed. Similarly, a measurement of skewness in the projected matter distribution directly measures the total matter content of the universe. While skewness has already been convincingly detected, its constraint on cosmology is still weak. We address optimal analyses for the CFHT Legacy Survey in the presence of noise. We show that a compensated Gaussian filter with a width of 2.5 arc minutes optimizes the cosmological constraint, yielding $\\Delta \\Omega_m/\\Omega_m\\sim 10%$. This is significantly better than other filt...

  20. The weak scale from BBN

    Science.gov (United States)

    Hall, Lawrence J.; Pinner, David; Ruderman, Joshua T.

    2014-12-01

    The measured values of the weak scale, v, and the first generation masses, m u, d, e , are simultaneously explained in the multiverse, with all these parameters scanning independently. At the same time, several remarkable coincidences are understood. Small variations in these parameters away from their measured values lead to the instability of hydrogen, the instability of heavy nuclei, and either a hydrogen or a helium dominated universe from Big Bang Nucleosynthesis. In the 4d parameter space of ( m u , m d , m e , v), catastrophic boundaries are reached by separately increasing each parameter above its measured value by a factor of (1.4, 1.3, 2.5, ˜ 5), respectively. The fine-tuning problem of the weak scale in the Standard Model is solved: as v is increased beyond the observed value, it is impossible to maintain a significant cosmological hydrogen abundance for any values of m u, d, e that yield both hydrogen and heavy nuclei stability.

  1. Weak Quasielastic Production of Hyperons

    CERN Document Server

    Athar, M Sajjad; Alam, M Rafi; Chauhan, S; Singh, S K

    2016-01-01

    We present the results for antineutrino induced quasielastic hyperon production from nucleon and nuclear targets \\cite{Alam:2014bya,Singh:2006xp}. The inputs are the nucleon-hyperon(N--Y) transition form factors determined from the analysis of neutrino-nucleon scattering and semileptonic decays of neutron and hyperons using SU(3) symmetry. The calculations for the nuclear targets are done in local density approximation. The nuclear medium effects(NME) like Fermi motion, Pauli blocking and final state interaction(FSI) effects due to hyperon-nucleon scattering have been taken into account. The hyperons giving rise to pions through weak decays also contribute to the weak pion production in addition to the $\\Delta$ excitation mechanism which dominates in the energy region of $<$ 0.7 GeV. We also present the results of longitudinal and perpendicular components of polarization of final hyperon \\cite{Akbar:2016awk}. These measurements in the future accelerator experiments with antineutrinos may give some informat...

  2. Weak lensing and cosmological investigation

    CERN Document Server

    Acquaviva, V

    2005-01-01

    In the last few years the scientific community has been dealing with the challenging issue of identifying the dark energy component. We regard weak gravitational lensing as a brand new, and extremely important, tool for cosmological investigation in this field. In fact, the features imprinted on the cosmic microwave background radiation by the lensing from the intervening distribution of matter represent a pretty unbiased estimator, and can thus be used for putting constraints on different dark energy models. This is true in particular for the magnetic-type B-modes of CMB polarization, whose unlensed spectrum at large multipoles (l approximately=1000) is very small even in presence of an amount of gravitational waves as large as currently allowed by the experiments: therefore, on these scales the lensing phenomenon is the only responsible for the observed power, and this signal turns out to be a faithful tracer of the dark energy dynamics. We first recall the formal apparatus of the weak lensing in extended t...

  3. Political corruption and weak state

    Directory of Open Access Journals (Sweden)

    Stojiljković Zoran

    2013-01-01

    Full Text Available The author starts from the hypothesis that it is essential for the countries of the region to critically assess the synergy established between systemic, political corruption and a selectively weak, “devious” nature of the state. Moreover, the key dilemma is whether the expanded practice of political rent seeking supports the conclusion that the root of all corruption is in the very existence of the state - particularly in excessive, selective and deforming state interventions and benefits that create a fertile ground for corruption? The author argues that the destructive combination of weak government and rampant political corruption is based on scattered state intervention, while also rule the parties cartel in the executive branch subordinate to parliament, the judiciary and the police. Corrupt exchange takes place with the absence of strong institutional framework and the precise rules of the political and electoral games, control of public finances and effective political and anti-monopoly legislation and practice included. Exit from the current situation can be seen in the realization of effective anti­corruption strategy that integrates preventive and repressive measures and activities and lead to the establishment of principles of good governance. [Projekat Ministarstva nauke Republike Srbije, br. 179076: Politički identitet Srbije u regionalnom i globalnom kontekstu

  4. Time—periodic weak solutions

    Directory of Open Access Journals (Sweden)

    Eliana Henriques de Brito

    1990-01-01

    Full Text Available In continuing from previous papers, where we studied the existence and uniqueness of the global solution and its asymptotic behavior as time t goes to infinity, we now search for a time-periodic weak solution u(t for the equation whose weak formulation in a Hilbert space H isddt(u′,v+δ(u′,v+αb(u,v+βa(u,v+(G(u,v=(h,vwhere: ′=d/dt; (′ is the inner product in H; b(u,v, a(u,v are given forms on subspaces U⊂W, respectively, of H; δ>0, α≥0, β≥0 are constants and α+β>0; G is the Gateaux derivative of a convex functional J:V⊂H→[0,∞ for V=U, when α>0 and V=W when α=0, hence β>0; v is a test function in V; h is a given function of t with values in H.

  5. Slowly moving matter-wave gap soliton propagation in weak random nonlinear potential

    Institute of Scientific and Technical Information of China (English)

    Zhang Ming-Rui; Zhang Yong-Liang; Jiang Xun-Ya; Zi Jian

    2008-01-01

    We systematically investigate the motion of slowly moving matter-wave gap solitons in a nonlinear potential, produced by the weak random spatial variation of the atomic scattering length. With the weak randomness, we construct an effective-particle theory to study the motion of gap solitons. Based on the effective-particle theory, the effect of the randomness on gap solitous is obtained, and the motion of gap solitons is finally solved. Moreover, the analytic results for the general behaviours of gap soliton motion, such as the ensemble-average speed and the reflection probability depending on the weak randomness are obtained. We find that with the increase of the random strength the ensemble-average speed of gap solitons decreases slowly where the reduction is proportional to the variance of the weak randomness, and the reflection probability becomes larger. The theoretical results are in good agreement with the numerical simulations based on the Gross-Pitaevskii equation.

  6. Traffic speed management

    Directory of Open Access Journals (Sweden)

    Subotić Jovana Lj.

    2014-01-01

    Full Text Available Speed, and vehicles themselves, affect the level of service and road safety, quality of life, noise from traffic, the environment, health, air pollution, emission of carbon dioxide, global warming, the economy and consumption of non-renewable energy such as oil. Therefore, the speed management of the traffic of multiple significance and that should be primarily to provide effective and economical conditions of the modern and preventive protection of human life as the greatest treasure and then the material resources. The way to accomplish this is by using various (different measures such as: appropriate planning and projecting roads and streets, speed control, the legislation, enforcement, campaigns, education, advanced technologies (ITS.

  7. Gas speed flow transducer

    Directory of Open Access Journals (Sweden)

    Godovaniouk V. N.

    2011-08-01

    Full Text Available The design of a gas speed flow transducer using the coupling of gas speed and heat streams within the transducer itself is proposed. To maintain the heat balance between two thermoresistors under gas stream at different temperatures, it provides energy consumption monitoring. The detailed combined planar technology for the transducer production is presented. The worked-out measurement procedure allows to make measurements in the temperature range. Information enough to organize production of cheap, reliable and precise gas speed flow transducers is given.

  8. A Taylor weak-statement algorithm for hyperbolic conservation laws

    Science.gov (United States)

    Baker, A. J.; Kim, J. W.

    1987-01-01

    Finite element analysis, applied to computational fluid dynamics (CFD) problem classes, presents a formal procedure for establishing the ingredients of a discrete approximation numerical solution algorithm. A classical Galerkin weak-statement formulation, formed on a Taylor series extension of the conservation law system, is developed herein that embeds a set of parameters eligible for constraint according to specification of suitable norms. The derived family of Taylor weak statements is shown to contain, as special cases, over one dozen independently derived CFD algorithms published over the past several decades for the high speed flow problem class. A theoretical analysis is completed that facilitates direct qualitative comparisons. Numerical results for definitive linear and nonlinear test problems permit direct quantitative performance comparisons.

  9. Quantum Butterfly Effect in Weakly Interacting Diffusive Metals

    Science.gov (United States)

    Patel, Aavishkar A.; Chowdhury, Debanjan; Sachdev, Subir; Swingle, Brian

    2017-07-01

    We study scrambling, an avatar of chaos, in a weakly interacting metal in the presence of random potential disorder. It is well known that charge and heat spread via diffusion in such an interacting disordered metal. In contrast, we show within perturbation theory that chaos spreads in a ballistic fashion. The squared anticommutator of the electron-field operators inherits a light-cone-like growth, arising from an interplay of a growth (Lyapunov) exponent that scales as the inelastic electron scattering rate and a diffusive piece due to the presence of disorder. In two spatial dimensions, the Lyapunov exponent is universally related at weak coupling to the sheet resistivity. We are able to define an effective temperature-dependent butterfly velocity, a speed limit for the propagation of quantum information that is much slower than microscopic velocities such as the Fermi velocity and that is qualitatively similar to that of a quantum critical system with a dynamical critical exponent z >1 .

  10. On the Weak Computability of Continuous Real Functions

    Directory of Open Access Journals (Sweden)

    Matthew S. Bauer

    2010-06-01

    Full Text Available In computable analysis, sequences of rational numbers which effectively converge to a real number x are used as the (rho- names of x. A real number x is computable if it has a computable name, and a real function f is computable if there is a Turing machine M which computes f in the sense that, M accepts any rho-name of x as input and outputs a rho-name of f(x for any x in the domain of f. By weakening the effectiveness requirement of the convergence and classifying the converging speeds of rational sequences, several interesting classes of real numbers of weak computability have been introduced in literature, e.g., in addition to the class of computable real numbers (EC, we have the classes of semi-computable (SC, weakly computable (WC, divergence bounded computable (DBC and computably approximable real numbers (CA. In this paper, we are interested in the weak computability of continuous real functions and try to introduce an analogous classification of weakly computable real functions. We present definitions of these functions by Turing machines as well as by sequences of rational polygons and prove these two definitions are not equivalent. Furthermore, we explore the properties of these functions, and among others, show their closure properties under arithmetic operations and composition.

  11. Fast weak-lensing simulations with halo model

    Science.gov (United States)

    Giocoli, Carlo; Di Meo, Sandra; Meneghetti, Massimo; Jullo, Eric; de la Torre, Sylvain; Moscardini, Lauro; Baldi, Marco; Mazzotta, Pasquale; Metcalf, R. Benton

    2017-09-01

    Full ray-tracing maps of gravitational lensing, constructed from N-body simulations, represent a fundamental tool to interpret present and future weak-lensing data. However, the limitation of computational resources and storage capabilities severely restricts the number of realizations that can be performed in order to accurately sample both the cosmic shear models and covariance matrices. In this paper, we present a halo model formalism for weak gravitational lensing that alleviates these issues by producing weak-lensing mocks at a reduced computational cost. Our model takes as input the halo population within a desired light cone and the linear power spectrum of the underlined cosmological model. We examine the contribution given by the presence of substructures within haloes to the cosmic shear power spectrum and quantify it to the percent level. Our method allows us to reconstruct high-resolution convergence maps, for any desired source redshifts, of light cones that realistically trace the matter density distribution in the universe, account for masked area and sample selections. We compare our analysis on the same large-scale structures constructed using ray-tracing techniques and find very good agreements in both the linear and non-linear regimes up to few percent levels. The accuracy and speed of our method demonstrate the potential of our halo model for weak-lensing statistics and the possibility to generate a large sample of convergence maps for different cosmological models as needed for the analysis of large galaxy redshift surveys.

  12. Casimir torque in weak coupling

    CERN Document Server

    Milton, Kimball A; Long, William

    2013-01-01

    In this paper, dedicated to Johan H{\\o}ye on the occasion of his 70th birthday, we examine manifestations of Casimir torque in the weak-coupling approximation, which allows exact calculations so that comparison with the universally applicable, but generally uncontrolled, proximity force approximation may be made. In particular, we examine Casimir energies between planar objects characterized by $\\delta$-function potentials, and consider the torque that arises when angles between the objects are changed. The results agree very well with the proximity force approximation when the separation distance between the objects is small compared with their sizes. In the opposite limit, where the size of one object is comparable to the separation distance, the shape dependence starts becoming irrelevant. These calculations are illustrative of what to expect for the torques between, for example, conducting planar objects, which eventually should be amenable to both improved theoretical calculation and experimental verific...

  13. New Weak Keys in RSA

    Institute of Scientific and Technical Information of China (English)

    WANG Baocang; LIU Shuanggen; HU Yupu

    2006-01-01

    The security of the RSA system with the prime pairs of some special form is investigated. A new special-purpose algorithm for factoring RSA numbers is proposed. The basic idea of the method is to factor RSA numbers by factoring a well-chosen quadratic polynomial with integral coefficients. When viewed as a general-purpose algorithm, the new algorithm has a high computational complexity. It is shown that the RSA number n=pq can be easily factored if p and q have the special form of p=as+b, q=cs+d, where a, b, c, d are relatively small numbers. Such prime pairs (p, q) are the weak keys of RSA, so when we generate RSA modulus, we should avoid using such prime pairs (p, q).

  14. Wind_Speeds_Master

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set included wind speeds for each subregion in the study (Georges Bank, Gulf of Maine, Southern New England, Middle Atlantic Bight) . The data came from...

  15. Speeding up Transportation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ 2007 was an excellent year for the transportation industry, marked by high speed railway transportation, development of the national expressway network and launch of the Chang'e lunar probe satellite.

  16. High speed heterostructure devices

    CERN Document Server

    Beer, Albert C; Willardson, R K; Kiehl, Richard A; Sollner, T C L Gerhard

    1994-01-01

    Volume 41 includes an in-depth review of the most important, high-speed switches made with heterojunction technology. This volume is aimed at the graduate student or working researcher who needs a broad overview andan introduction to current literature. Key Features * The first complete review of InP-based HFETs and complementary HFETs, which promise very low power and high speed * Offers a complete, three-chapter review of resonant tunneling * Provides an emphasis on circuits as well as devices.

  17. Police enforcement and driving speed.

    NARCIS (Netherlands)

    2008-01-01

    Speed limits are violated frequently in the Netherlands. As speed is an important factor in road crashes, the surveillance of driving speeds is one of the spearheads in the policy plans of the Dutch police. Different methods of speed enforcement have proved to be effective in reducing speed and cras

  18. Acceleration of weakly collisional solar-type winds

    CERN Document Server

    Zouganelis, I; Landi, S; Maksimovic, M; Pantellini, F

    2005-01-01

    One of the basic properties of the solar wind, that is the high speed of the fast wind, is still not satisfactorily explained. This is mainly due to the theoretical difficulty of treating weakly collisional plasmas. The fluid approach implies that the medium is collision dominated and that the particle velocity distributions are close to Maxwellians. However the electron velocity distributions observed in the solar wind depart significantly from Maxwellians. Recent kinetic collisionless models (called exospheric) using velocity distributions with a suprathermal tail have been able to reproduce the high speeds of the fast solar wind. In this letter we present new developments of these models by generalizing them over a large range of corona conditions. We also present new results obtained by numerical simulations that include collisions. Both approaches calculate the heat flux self-consistently without any assumption on the energy transport. We show that both approaches - the exospheric and the collisional one...

  19. Calculating Speed of Sound

    Science.gov (United States)

    Bhatnagar, Shalabh

    2017-01-01

    Sound is an emerging source of renewable energy but it has some limitations. The main limitation is, the amount of energy that can be extracted from sound is very less and that is because of the velocity of the sound. The velocity of sound changes as per medium. If we could increase the velocity of the sound in a medium we would be probably able to extract more amount of energy from sound and will be able to transfer it at a higher rate. To increase the velocity of sound we should know the speed of sound. If we go by the theory of classic mechanics speed is the distance travelled by a particle divided by time whereas velocity is the displacement of particle divided by time. The speed of sound in dry air at 20 °C (68 °F) is considered to be 343.2 meters per second and it won't be wrong in saying that 342.2 meters is the velocity of sound not the speed as it's the displacement of the sound not the total distance sound wave covered. Sound travels in the form of mechanical wave, so while calculating the speed of sound the whole path of wave should be considered not just the distance traveled by sound. In this paper I would like to focus on calculating the actual speed of sound wave which can help us to extract more energy and make sound travel with faster velocity.

  20. On fuzzy weakly-closed sets

    OpenAIRE

    Mahanta, J.; P. K. Das

    2012-01-01

    A new class of fuzzy closed sets, namely fuzzy weakly closed set in a fuzzy topological space is introduced and it is established that this class of fuzzy closed sets lies between fuzzy closed sets and fuzzy generalized closed sets. Alongwith the study of fundamental results of such closed sets, we define and characterize fuzzy weakly compact space and fuzzy weakly closed space.

  1. Twisting theory for weak Hopf algebras

    Institute of Scientific and Technical Information of China (English)

    CHEN Ju-zhen; ZHANG Yan; WANG Shuan-hong

    2008-01-01

    The main aim of this paper is to study the twisting theory of weak Hopf algebras and give an equivalence between the (braided) monoidal categories of weak Hopf bimodules over the original and the twisted weak Hopf algebra to generalize the result from Oeckl (2000).

  2. Reconstruction of weak quasi-Hopf algebras

    CERN Document Server

    Häring, Reto Andreas

    1995-01-01

    All rational semisimple braided tensor categories are representation categories of weak quasi Hopf algebras. To proof this result we construct for any given category of this kind a weak quasi tensor functor to the category of finite dimensional vector spaces. This allows to reconstruct a weak quasi Hopf algebra with the given category as its representation category.

  3. Fingerprinting Dark Energy II: weak lensing and galaxy clustering tests

    CERN Document Server

    Sapone, Domenico; Amendola, Luca

    2010-01-01

    The characterization of dark energy is a central task of cosmology. To go beyond a cosmological constant, we need to introduce at least an equation of state and a sound speed and consider observational tests that involve perturbations. If dark energy is not completely homogeneous on observable scales then the Poisson equation is modified and dark matter clustering is directly affected. One can then search for observational effects of dark energy clustering using dark matter as a probe. In this paper we exploit an analytical approximate solution of the perturbation equations in a general dark energy cosmology to analyze the performance of next-decade large scale surveys in constraining equation of state and sound speed. We find that tomographic weak lensing and galaxy redshift surveys can constrain the sound speed of the dark energy only if the latter is small, of the order of $c_{s}\\lesssim0.01$ (in units of $c$). For larger sound speeds the error grows to 100% and more. We conclude that large scale structure...

  4. Weakly Distributive Modules. Applications to Supplement Submodules

    Indian Academy of Sciences (India)

    Engin Büyükaşik; Yilmaz M Demirci

    2010-11-01

    In this paper, we define and study weakly distributive modules as a proper generalization of distributive modules. We prove that, weakly distributive supplemented modules are amply supplemented. In a weakly distributive supplemented module every submodule has a unique coclosure. This generalizes a result of Ganesan and Vanaja. We prove that -projective duo modules, in particular commutative rings, are weakly distributive. Using this result we obtain that in a commutative ring supplements are unique. This generalizes a result of Camillo and Lima. We also prove that any weakly distributive $\\oplus$-supplemented module is quasi-discrete.

  5. Weakly relativistic dispersion of Bernstein waves

    Science.gov (United States)

    Robinson, P. A.

    1988-01-01

    Weakly relativistic effects on the dispersion of Bernstein waves are investigated for waves propagating nearly perpendicular to a uniform magnetic field in a Maxwellian plasma. Attention is focused on those large-wave-vector branches that are either weakly damped or join continuously onto weakly damped branches since these are the modes of most interest in applications. The transition between dispersion at perpendicular and oblique propagation is examined and major weakly relativistic effects can dominate even in low-temperature plasmas. A number of simple analytic criteria are obtained which delimit the ranges of harmonic number and propagation angle within which various types of weakly damped Bernstein modes can exist.

  6. Weakly relativistic dispersion of Bernstein waves

    Science.gov (United States)

    Robinson, P. A.

    1988-01-01

    Weakly relativistic effects on the dispersion of Bernstein waves are investigated for waves propagating nearly perpendicular to a uniform magnetic field in a Maxwellian plasma. Attention is focused on those large-wave-vector branches that are either weakly damped or join continuously onto weakly damped branches since these are the modes of most interest in applications. The transition between dispersion at perpendicular and oblique propagation is examined and major weakly relativistic effects can dominate even in low-temperature plasmas. A number of simple analytic criteria are obtained which delimit the ranges of harmonic number and propagation angle within which various types of weakly damped Bernstein modes can exist.

  7. Variable Speed Rotor System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Variable speed rotors will give helicopters several advantages: higher top speed, greater fuel efficiency, momentary emergency over-power, resonance detuning...

  8. A Universe without Weak Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Harnik, Roni; Kribs, Graham D.; Perez, Gilad

    2006-04-07

    A universe without weak interactions is constructed that undergoes big-bang nucleosynthesis, matter domination, structure formation, and star formation. The stars in this universe are able to burn for billions of years, synthesize elements up to iron, and undergo supernova explosions, dispersing heavy elements into the interstellar medium. These definitive claims are supported by a detailed analysis where this hypothetical ''Weakless Universe'' is matched to our Universe by simultaneously adjusting Standard Model and cosmological parameters. For instance, chemistry and nuclear physics are essentially unchanged. The apparent habitability of the Weakless Universe suggests that the anthropic principle does not determine the scale of electroweak breaking, or even require that it be smaller than the Planck scale, so long as technically natural parameters may be suitably adjusted. Whether the multi-parameter adjustment is realized or probable is dependent on the ultraviolet completion, such as the string landscape. Considering a similar analysis for the cosmological constant, however, we argue that no adjustments of other parameters are able to allow the cosmological constant to raise up even remotely close to the Planck scale while obtaining macroscopic structure. The fine-tuning problems associated with the electroweak breaking scale and the cosmological constant therefore appear to be qualitatively different from the perspective of obtaining a habitable universe.

  9. A universe without weak interactions

    Science.gov (United States)

    Harnik, Roni; Kribs, Graham D.; Perez, Gilad

    2006-08-01

    A universe without weak interactions is constructed that undergoes big-bang nucleosynthesis, matter domination, structure formation, and star formation. The stars in this universe are able to burn for billions of years, synthesize elements up to iron, and undergo supernova explosions, dispersing heavy elements into the interstellar medium. These definitive claims are supported by a detailed analysis where this hypothetical “weakless universe” is matched to our Universe by simultaneously adjusting standard model and cosmological parameters. For instance, chemistry and nuclear physics are essentially unchanged. The apparent habitability of the weakless universe suggests that the anthropic principle does not determine the scale of electroweak breaking, or even require that it be smaller than the Planck scale, so long as technically natural parameters may be suitably adjusted. Whether the multiparameter adjustment is realized or probable is dependent on the ultraviolet completion, such as the string landscape. Considering a similar analysis for the cosmological constant, however, we argue that no adjustments of other parameters are able to allow the cosmological constant to raise up even remotely close to the Planck scale while obtaining macroscopic structure. The fine-tuning problems associated with the electroweak breaking scale and the cosmological constant therefore appear to be qualitatively different from the perspective of obtaining a habitable universe.

  10. Weak homology of elliptical galaxies

    CERN Document Server

    Bertin, G; Principe, M D

    2002-01-01

    We start by studying a small set of objects characterized by photometric profiles that have been pointed out to deviate significantly from the standard R^{1/4} law. For these objects we confirm that a generic R^{1/n} law, with n a free parameter, can provide superior fits (the best-fit value of n can be lower than 2.5 or higher than 10), better than those that can be obtained by a pure R^{1/4} law, by an R^{1/4}+exponential model, and by other dynamically justified self--consistent models. Therefore, strictly speaking, elliptical galaxies should not be considered homologous dynamical systems. Still, a case for "weak homology", useful for the interpretation of the Fundamental Plane of elliptical galaxies, could be made if the best-fit parameter n, as often reported, correlates with galaxy luminosity L, provided the underlying dynamical structure also follows a systematic trend with luminosity. We demonstrate that this statement may be true even in the presence of significant scatter in the correlation n(L). Pr...

  11. Testing the weak equivalence principle

    Science.gov (United States)

    Nobili, Anna M.; Comandi, Gian Luca; Pegna, Raffaello; Bramanti, Donato; Doravari, Suresh; Maccarone, Francesco; Lucchesi, David M.

    2010-01-01

    The discovery of Dark Energy and the fact that only about 5% of the mass of the universe can be explained on the basis of the current laws of physics have led to a serious impasse. Based on past history, physics might indeed be on the verge of major discoveries; but the challenge is enormous. The way to tackle it is twofold. On one side, scientists try to perform large scale direct observations and measurements - mostly from space. On the other, they multiply their efforts to put to the most stringent tests ever the physical theories underlying the current view of the physical world, from the very small to the very large. On the extremely small scale very exciting results are expected from one of the most impressive experiments in the history of mankind: the Large Hadron Collider. On the very large scale, the universe is dominated by gravity and the present impasse undoubtedly calls for more powerful tests of General Relativity - the best theory of gravity to date. Experiments testing the Weak Equivalence Principle, on which General Relativity ultimately lies, have the strongest probing power of them all; a breakthrough in sensitivity is possible with the “Galileo Galilei” (GG) satellite experiment to fly in low Earth orbit.

  12. The Geometry And Significance Of Weak Energy

    CERN Document Server

    Parks, A D

    2000-01-01

    Summary: The theory of weak values for quantum mechanical observables has come to serve as a useful basis for contemporary discussions concerning such varied topics as the tunnelling-time controversy and quantum stochastic processes. An intrinsic complex-valued weak energy has recently been observed experimentally and reported in the literature. In this paper it is shown that: (a) the real and imaginary valued parts of this weak energy have geometric interpretations related to a phase acquired from parallel transport in Hilbert space and the variational dynamics occurring in the associated projective Hilbert space, respectively; (b) the weak energy defines functions which translate correlation amplitudes and probabilities in time; (c) correlation probabilities can be controlled by manipulating the weak energy and there exists a condition of weak stationarity that guarantees their time invariance; and (d) a time-weak energy uncertainty relation of the usual form prevails when a suitable set of dynamical constr...

  13. PERSONALITY AND SPEEDING

    Directory of Open Access Journals (Sweden)

    Richard TAY

    2003-01-01

    Full Text Available While there has been extensive research on the effect of sensation seeking on risky driving, relatively little research has been conducted on Type-A personality. The motivations for speeding are likely to be different for each group and these differences have important implications for the design, implementation and expected efficacy of road safety countermeasures. This paper examines the influence of sensation seeking and Type-A behavior pattern on speeding behaviour. A sample of 139 staff and students in an Australian university were surveyed in July 2001 to gather information on their gender, age, personality and self-reported speeding behaviour. The data were analysed using correlations and analysis of variance procedures. Finally, some implications for road safety are discussed.

  14. Weak* convergence of operator means

    Energy Technology Data Exchange (ETDEWEB)

    Romanov, Alexandr V [Moscow State Institute of Electronics and Mathematics (Technical University), Moscow (Russian Federation)

    2011-12-31

    For a linear operator U with ||U'n||{<=}const on a Banach space X we discuss conditions for the convergence of ergodic operator nets T{sub {alpha}} corresponding to the adjoint operator U* of U in the W*O-topology of the space EndX*. The accumulation points of all possible nets of this kind form a compact convex set L in EndX*, which is the kernel of the operator, where {Gamma}{sub 0}={l_brace}U{sub n}*, n{>=}0{r_brace}. It is proved that all ergodic nets T{sub {alpha}} weakly* converge if and only if the kernel L consists of a single element. In the case of X=C({Omega}) and the shift operator U generated by a continuous transformation {phi} of a metrizable compactum {Omega} we trace the relationships among the ergodic properties of U, the structure of the operator semigroups L, G and {Gamma}={Gamma}-bar{sub 0}, and the dynamical characteristics of the semi-cascade ({phi},{Omega}). In particular, if cardL=1, then a) for any {omega} element of {Omega} the closure of the trajectory {l_brace}{phi}{sup n}{omega}, n{>=}0{r_brace} contains precisely one minimal set m, and b) the restriction ({phi},m) is strictly ergodic. Condition a) implies the W*O-convergence of any ergodic sequence of operators T{sub n} element of EndX* under the additional assumption that the kernel of the enveloping semigroup E({phi},{Omega}) contains elements obtained from the 'basis' family of transformations {l_brace}{phi}{sup n}, n{>=}0{r_brace} of the compact set {Omega} by using some transfinite sequence of sequential passages to the limit.

  15. Spindle picker harvest speed effects

    Science.gov (United States)

    The gear drive of a modern John Deere Pro 16 picker unit was modified so that spindle speed was reduced without changing the drum speed. Three 1-row picking units were used in the study, one with the standard drive speeds, one with 25% reduction in spindle drive speed, and one with 50% reduction in...

  16. Speeding Up Innovation

    DEFF Research Database (Denmark)

    Sørensen, Flemming; Mattsson, Jan

    2016-01-01

    Minimisation of time-to-market strategies can provide companies with a competitive advantage in dynamic and competitive environments. Using parallel innovation processes has been emphasised as one strategy to speed up innovation processes and consequently minimise the time-to-market of innovations...

  17. More Than Just Speed

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Following more than 10 years of deliberation and planning,construc- tion of the 1,320-km Beijing-Shanghai High-speed Railway began in mid- April.Following the world’s most elevated Qinghai-Tibet Railway,which

  18. Variable speed generators

    CERN Document Server

    Boldea, Ion

    2005-01-01

    With the deregulation of electrical energy production and distribution, says Boldea (Polytechnical Institute, Timisoara, Romania) producers are looking for ways to tailor their electricity for different markets. Variable-speed electric generators are serving that purpose, up to the 400 megavolt ampere unit size, in Japan since 1996 and Germany sinc

  19. Cloud speed sensor

    Directory of Open Access Journals (Sweden)

    V. Fung

    2013-10-01

    Full Text Available Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system that measures cloud motion vectors to estimate power plant ramp rates and provide short term solar irradiance forecasts is presented. The Cloud Speed Sensor (CSS is constructed using an array of luminance sensors and high-speed data acquisition to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground measured irradiance (Linear Cloud Edge, LCE, and a UC San Diego Sky Imager (USI. The CSS detected artificial shadow directions and speeds to within 15 and 6% accuracy, respectively. The CSS detected (real cloud directions and speeds without average bias and with average weighted root mean square difference of 22° and 1.9 m s−1 when compared to USI and 33° and 1.5 m s−1 when compared to LCE results.

  20. Speed mathematics simplified

    CERN Document Server

    Stoddard, Edward

    1994-01-01

    Entertaining, easy-to-follow suggestions for developing greater speed and accuracy in doing mathematical calculations. Surefire methods for multiplying without carrying, dividing with half the pencil work of long division, plus advice on how to add and subtract rapidly, master fractions, work quickly with decimals, handle percentages, and much more.

  1. Weak turbulence theory for rotating magnetohydrodynamics and planetary dynamos

    CERN Document Server

    Galtier, Sebastien

    2014-01-01

    A weak turbulence theory is derived for magnetohydrodynamics under rapid rotation and in the presence of a large-scale magnetic field. The angular velocity $\\Omega_0$ is assumed to be uniform and parallel to the constant Alfv\\'en speed ${\\bf b_0}$. Such a system exhibits left and right circularly polarized waves which can be obtained by introducing the magneto-inertial length $d \\equiv b_0/\\Omega_0$. In the large-scale limit ($kd \\to 0$; $k$ being the wave number), the left- and right-handed waves tend respectively to the inertial and magnetostrophic waves whereas in the small-scale limit ($kd \\to + \\infty$) pure Alfv\\'en waves are recovered. By using a complex helicity decomposition, the asymptotic weak turbulence equations are derived which describe the long-time behavior of weakly dispersive interacting waves {\\it via} three-wave interaction processes. It is shown that the nonlinear dynamics is mainly anisotropic with a stronger transfer perpendicular ($\\perp$) than parallel ($\\parallel$) to the rotating a...

  2. iPTF13ehe in the context of Quark-Novae in massive binaries: double-humped, hydrogen-poor, superluminous Supernovae as standard candles

    CERN Document Server

    Ouyed, Rachid; Koning, Nico

    2015-01-01

    A Quark-Nova (QN; the explosive transition of a Neutron star to a Quark star) occurring in the second common envelope (CE) phase of a massive binary, as described in Ouyed et al. (2015a&b), gives excellent fits to super-luminous, hydrogen-poor, Supernovae (SLSNe) with double-humped light curves including DES13S2cmm, SN 2006oz and LSQ14bdq (see {\\it http://www.quarknova.ca/LCGallery.html}). In our model, the hydrogen envelope of the less massive companion is ejected during the first CE phase while the QN explosion occurs deep inside the He-rich second CE phase after it has expanded to its equilibrium configuration at ~1200Rsun; this yields the first hump in our model. The subsequent merging of the quark star with the CO core leads to black hole formation and accretion explaining the second long-lasting hump in our model, while the collision of the QN-ejected He-rich CE with the H-rich (i.e. first) CE accounts for late emission. Here we show that our model provides an excellent fit to the recently discovere...

  3. Detection of Broad H$\\alpha$ Emission Lines in the Late-time Spectra of a Hydrogen-poor Superluminous Supernova

    CERN Document Server

    Yan, Lin; Ofek, E; Gal-Yam, A; Mazzali, P; Perley, D; Vreeswijk, P; Leloudas, G; de Cia, A; Masci, F; Cenko, S B; Cao, Y; Kulkarni, S R; Nugent, P E; Rebbapragada, Umaa D; Woźniak, P R; Yaron, O

    2015-01-01

    iPTF13ehe is a hydrogen-poor superluminous supernova (SLSN) at z=0.3434, with properties similar to SN2007bi. It rises within (83-148)days (rest-frame) to reach a peak bolometric luminosity of 1.3x$10^{44}$erg/s, then decays very slowly at 0.015mag. per day. The measured ejecta velocity is 13000km/s. The inferred explosion characteristics, such as the ejecta mass (67-220$M_\\odot$), the total radiative and kinetic energy ($10^{51}$ & 2x$10^{53}$erg respectively), is typical of SLSN-R events. However, the late-time spectrum taken at +251days reveals a Balmer Halpha emission feature with broad and narrow components, which has never been detected before among other H-poor SLSNe. The broad component has a velocity width of ~4500km/s and has a ~300km/s blue-ward shift relative to the narrow component. We interpret this broad Halpha emission line as the interaction between the supernova ejecta and a H-rich circumstellar medium (CSM) shell, located at a distance of ~4x$10^{16}$cm from the explosion site. This eje...

  4. Highly Luminous Supernovae associated with Gamma-Ray Bursts I.: GRB 111209A/SN 2011kl in the Context of Stripped-Envelope and Superluminous Supernovae

    CERN Document Server

    Kann, D A; E., F Olivares; Klose, S; Rossi, A; Perley, D A; Krühler, T; Greiner, J; Guelbenzu, A Nicuesa; Elliott, J; Knust, F; Filgas, R; Pian, E; Mazzali, P; Fynbo, J P U; Leloudas, G; Afonso, P M J; Delvaux, C; Graham, J F; Rau, A; Schmidl, S; Schulze, S; Tanga, M; Updike, A C; Varela, K

    2016-01-01

    We address the question whether GRB 111209A was a special event beyond its extreme duration alone, and whether it is a classical GRB or another kind of high-energy transient. Furthermore, we place SN 2011kl into the context of large samples of SNe, addressing in more detail the question of whether it could be radioactively powered. We present afterglow photometry obtained in seven bands with the GROND imager as well as in further seven bands with the UVOT telescope on-board \\emph{Swift}. The light curve is analysed by multi-band modelling and joint fitting with power-laws and broken power-laws. We model SN 2011kl using SN 1998bw as a template and derive a bolometric light curve including near-infrared data. We compare the optical afterglow and the properties of SN 2011kl to large ensembles we have analysed in earlier works, additional GRB-SNe analysed here, as well as literature results on stripped-envelope and superluminous supernovae. We find a strong, chromatic rebrightening event at $\\approx0.8$ days afte...

  5. Superluminous Supernova SN 2015bn in the Nebular Phase: Evidence for the Engine-powered Explosion of a Stripped Massive Star

    Science.gov (United States)

    Nicholl, M.; Berger, E.; Margutti, R.; Chornock, R.; Blanchard, P. K.; Jerkstrand, A.; Smartt, S. J.; Arcavi, I.; Challis, P.; Chambers, K. C.; Chen, T.-W.; Cowperthwaite, P. S.; Gal-Yam, A.; Hosseinzadeh, G.; Howell, D. A.; Inserra, C.; Kankare, E.; Magnier, E. A.; Maguire, K.; Mazzali, P. A.; McCully, C.; Milisavljevic, D.; Smith, K. W.; Taubenberger, S.; Valenti, S.; Wainscoat, R. J.; Yaron, O.; Young, D. R.

    2016-09-01

    We present nebular-phase imaging and spectroscopy for the hydrogen-poor superluminous supernova (SLSN) SN 2015bn, at redshift z = 0.1136, spanning +250-400 days after maximum light. The light curve exhibits a steepening in the decline rate from 1.4 mag (100 days)-1 to 1.7 mag (100 days)-1, suggestive of a significant decrease in the opacity. This change is accompanied by a transition from a blue continuum superposed with photospheric absorption lines to a nebular spectrum dominated by emission lines of oxygen, calcium, and magnesium. There are no obvious signatures of circumstellar interaction or large 56Ni mass. We show that the spectrum at +400 days is virtually identical to a number of energetic SNe Ic such as SN 1997dq, SN 2012au, and SN 1998bw, indicating similar core conditions and strengthening the link between “hypernovae”/long gamma-ray bursts and SLSNe. A single explosion mechanism may unify these events that span absolute magnitudes of -22 < M B < -17. Both the light curve and spectrum of SN 2015bn are consistent with an engine-driven explosion ejecting 7-30 M ⊙ of oxygen-dominated ejecta (for reasonable choices in temperature and opacity). A strong and relatively narrow O i λ7774 line, seen in a number of these energetic events but not in normal supernovae, may point to an inner shell that is the signature of a central engine.

  6. Weakly and Strongly Regular Near-rings

    Institute of Scientific and Technical Information of China (English)

    N.Argac; N.J.Groenewald

    2005-01-01

    In this paper, we prove some basic properties of left weakly regular near-rings.We give an affirmative answer to the question whether a left weakly regular near-ring with left unity and satisfying the IFP is also right weakly regular. In the last section, we use among others left 0-prime and left completely prime ideals to characterize strongly regular near-rings.

  7. WEAK CONVERGENCE OF HENSTOCK INTEGRABLE SEQUENCES

    Institute of Scientific and Technical Information of China (English)

    LuisaDiPiazza

    1994-01-01

    Some relationships between pointwise and weak convergence of a sequence of Henstock integrable functions are studied, In particular it is provided an example of a sequence of Henstock integrable functions whose pointwise limit is different from the weak one. By introducing an asymptotic version of the Henstock equiintegrability notion it is given a necessary and sufficient condition in order that a pointwisely convergent sequence of Henstock integrable functions is weakly convergent to its pointwise limit.

  8. Transversality theorems for the weak topology

    OpenAIRE

    2011-01-01

    In his 1979 paper Trotman proves, using the techniques of the Thom transversality theorem, that under some conditions on the dimensions of the manifolds under consideration, openness of the set of maps transverse to a stratification in the strong (Whitney) topology implies that the stratification is $(a)$-regular. Here we first discuss the Thom transversality theorem for the weak topology and then give a similiar kind of result for the weak topology, under very weak hypotheses. Recently sever...

  9. Spin effects in the weak interaction

    Energy Technology Data Exchange (ETDEWEB)

    Freedman, S.J. (Argonne National Lab., IL (USA) Chicago Univ., IL (USA). Dept. of Physics Chicago Univ., IL (USA). Enrico Fermi Inst.)

    1990-01-01

    Modern experiments investigating the beta decay of the neutron and light nuclei are still providing important constraints on the theory of the weak interaction. Beta decay experiments are yielding more precise values for allowed and induced weak coupling constants and putting constraints on possible extensions to the standard electroweak model. Here we emphasize the implications of recent experiments to pin down the strengths of the weak vector and axial vector couplings of the nucleon.

  10. On Weakly P.P. Rings

    Institute of Scientific and Technical Information of China (English)

    Xiang Yue-ming; Ouyang Lun-qun; Wang Shu-gui

    2015-01-01

    We introduce, in this paper, the right weakly p.p. rings as the generaliza-tion of right p.p. rings. It is shown that many properties of the right p.p. rings can be extended onto the right weakly p.p. rings. Relative examples are constructed. As applications, we also characterize the regular rings and the semisimple rings in terms of the right weakly p.p. rings.

  11. Weak measurements with a qubit meter

    DEFF Research Database (Denmark)

    Wu, Shengjun; Mølmer, Klaus

    2009-01-01

    We derive schemes to measure the so-called weak values of quantum system observables by coupling of the system to a qubit meter system. We highlight, in particular, the meaning of the imaginary part of the weak values, and show how it can be measured directly on equal footing with the real part...... of the weak value. We present compact expressions for the weak value of single qubit observables and of product observables on qubit pairs. Experimental studies of the results are suggested with cold trapped ions....

  12. Improving speed behaviour : the potential of in-car speed assistance and speed limit credibility.

    NARCIS (Netherlands)

    Nes, C.N. van Houtenbos, M. & Schagen, I.N.L.G. van

    2009-01-01

    Speeding is still a common practice on many roads and it contributes to a significant number of crashes. Two new approaches to solve speeding issues are focused on: intelligent speed assistance systems (ISA) and speed limit credibility. Research has indicated that ISA is promising with respect to im

  13. Weak Fault Diagnosis of Wind Turbine Gearboxes Based on MED-LMD

    Directory of Open Access Journals (Sweden)

    Zhijian Wang

    2017-06-01

    Full Text Available In view of the problem that the fault signal of the rolling bearing is weak and the fault feature is difficult to extract in the strong noise environment, a method based on minimum entropy deconvolution (MED and local mean deconvolution (LMD is proposed to extract the weak fault features of the rolling bearing. Through the analysis of the simulation signal, we find that LMD has many limitations for the feature extraction of weak signals under strong background noise. In order to eliminate the noise interference and extract the characteristics of the weak fault, MED is employed as the pre-filter to remove noise. This method is applied to the weak fault feature extraction of rolling bearings; that is, using MED to reduce the noise of the wind turbine gearbox test bench under strong background noise, and then using the LMD method to decompose the denoised signals into several product functions (PFs, and finally analyzing the PF components that have strong correlation by a cyclic autocorrelation function. The finding is that the failure of the wind power gearbox is generated from the micro-bending of the high-speed shaft and the pitting of the #10 bearing outer race at the output end of the high-speed shaft. This method is compared with LMD, which shows the effectiveness of this method. This paper provides a new method for the extraction of multiple faults and weak features in strong background noise.

  14. Do speed cameras reduce speeding in urban areas?

    Science.gov (United States)

    Oliveira, Daniele Falci de; Friche, Amélia Augusta de Lima; Costa, Dário Alves da Silva; Mingoti, Sueli Aparecida; Caiaffa, Waleska Teixeira

    2015-11-01

    This observational study aimed to estimate the prevalence of speeding on urban roadways and to analyze associated factors. The sample consisted of 8,565 vehicles circulating in areas with and without fixed speed cameras in operation. We found that 40% of vehicles 200 meters after the fixed cameras and 33.6% of vehicles observed on roadways without speed cameras were moving over the speed limit (p cameras, more women drivers were talking on their cell phones and wearing seatbelts when compared to men (p < 0.05 for both comparisons), independently of speed limits. The results suggest that compliance with speed limits requires more than structural interventions.

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

    CERN Document Server

    Yang, J; Gurvits, L I; Campbell, R M; Giannios, D; An, T; Komossa, S

    2016-01-01

    The first-known tidal disruption event (TDE) with strong evidence for a relativistic jet -- based on extensive multi-wavelength 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 utilise 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 micro-arcsecond (68 % 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 %. This tight limit is d...

  16. 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.

  17. Hadronic Equation of State and Speed of Sound in Thermal and Dense Medium

    CERN Document Server

    Tawfik, A

    2012-01-01

    The equation of state and squared speed of sound $c_s^2$ are studied in grand canonical ensemble of all hadron resonances having masses $\\leq 2\\,$GeV. The ensemble is divided into strange and non-strange hadron resonances. Furthermore, pionic, bosonic and femeionic sectors are considered, separately. It is found that $c_s^2$ calculated in the QCD matter below $T_c$ is obviously causal. There is no sign for superluminal phenomena. It is found that the lightest Goldstone bosons, the pions, represent the main contributors to $c_s^2$ at low temperatures. At this temperature scale, they determine the hadronic thermodynamics including the equation of state, almost entirely. The comparison of the barotropic dependence of the pressure calculated in the hadron resonance gas (HRG) with that of full lattice QCD at vanishing and finite chemical potential is excellent. Nevertheless, the comparison of $c_s^2$ at vanishing chemical potential is not that good. But, when switching on the chemical potential, HRG $c_s^2$ and th...

  18. Speed Rotating Components

    Directory of Open Access Journals (Sweden)

    S. Wittig

    1998-01-01

    Full Text Available Cooling of high speed rotating components is a typical situation found in turbomachinery as well as in automobile engines. Accurate knowledge of discharge coefficients and heat transfer of related components is essential for the high performance of the whole engine. This can be achieved by minimized cooling air flows and avoidance of hot spots. In high speed rotating clutches for example aerodynamic investigations improving heat transfer have not been considered in the past. Advanced concepts of modern plate design try to reduce thermal loads by convective cooling methods. Therefore, secondary cooling air flows have to be enhanced by an appropriate design of the rotor stator system with orifices. CFD modelling is used to improve the basic understanding of the flow field in typical geometries used in these systems.

  19. High Speed Video Insertion

    Science.gov (United States)

    Janess, Don C.

    1984-11-01

    This paper describes a means of inserting alphanumeric characters and graphics into a high speed video signal and locking that signal to an IRIG B time code. A model V-91 IRIG processor, developed by Instrumentation Technology Systems under contract to Instrumentation Marketing Corporation has been designed to operate in conjunction with the NAC model FHS-200 High Speed Video Camera which operates at 200 fields per second. The system provides for synchronizing the vertical and horizontal drive signals such that the vertical sync precisely coincides with five millisecond transitions in the IRIG time code. Additionally, the unit allows for the insertion of an IRIG time message as well as other data and symbols.

  20. Forecasting Solar Wind Speeds

    CERN Document Server

    Suzuki, T K

    2006-01-01

    By explicitly taking into account effects of Alfven waves, I derive from a simple energetics argument a fundamental relation which predicts solar wind (SW) speeds in the vicinity of the earth from physical properties on the sun. Kojima et al. recently found from their observations that a ratio of surface magnetic field strength to an expansion factor of open magnetic flux tubes is a good indicator of the SW speed. I show by using the derived relation that this nice correlation is an evidence of the Alfven wave which accelerates SW in expanding flux tubes. The observations further require that fluctuation amplitudes of magnetic field lines at the surface should be almost universal in different coronal holes, which needs to be tested by future observations.

  1. Variable speed controller

    Science.gov (United States)

    Estes, Christa; Spiggle, Charles; Swift, Shannon; Vangeffen, Stephen; Younger, Frank

    1992-01-01

    This report details a new design for a variable speed controller which can be used to operate lunar machinery without the astronaut using his or her upper body. In order to demonstrate the design, a treadle for an industrial sewing machine was redesigned to be used by a standing operator. Since the invention of an electrically powered sewing machine, the operator has been seated. Today, companies are switching from sit down to stand up operation involving modular stations. The old treadle worked well with a sitting operator, but problems have been found when trying to use the same treadle with a standing operator. Emphasis is placed on the ease of use by the operator along with the ergonomics involved. Included with the design analysis are suggestions for possible uses for the speed controller in other applications.

  2. Monitoring speed before and during a speed publicity campaign.

    Science.gov (United States)

    van Schagen, Ingrid; Commandeur, Jacques J F; Goldenbeld, Charles; Stipdonk, Henk

    2016-12-01

    Driving speeds were monitored during a period of 16 weeks encompassing different stages of an anti-speeding campaign in the Netherlands. This campaign targeted speed limit violations in built-up areas. The observation periods differed in terms of intensity and media used for the campaign. Small road-side radars, mounted in light poles, were used and registered the speeds on 20 locations in built-up areas. Speeds of over 10 million vehicles were measured. Ten locations had a posted speed limit of 50km/h; the other ten had a posted speed limit of 30km/h. Posters were placed at half of each group of locations to remind drivers of the speed limit. The average speed on the 50km/h roads was 46.2km/h, and 36.1km/h on the 30km/h roads. The average proportions of vehicles exceeding the speed limit were 33.3% and 70.1% respectively. For the 30km/h roads, the data shows differences in speed and speeding behaviour between the six distinguished observation periods, but overall these differences cannot be logically linked to the contents of the phases and, hence, cannot be explained as an effect of the campaign. The only exception was an effect of local speed limit reminders on the 30km/h roads. This effect, however, was temporary and had disappeared within a week.

  3. High speed multiphoton imaging

    Science.gov (United States)

    Li, Yongxiao; Brustle, Anne; Gautam, Vini; Cockburn, Ian; Gillespie, Cathy; Gaus, Katharina; Lee, Woei Ming

    2016-12-01

    Intravital multiphoton microscopy has emerged as a powerful technique to visualize cellular processes in-vivo. Real time processes revealed through live imaging provided many opportunities to capture cellular activities in living animals. The typical parameters that determine the performance of multiphoton microscopy are speed, field of view, 3D imaging and imaging depth; many of these are important to achieving data from in-vivo. Here, we provide a full exposition of the flexible polygon mirror based high speed laser scanning multiphoton imaging system, PCI-6110 card (National Instruments) and high speed analog frame grabber card (Matrox Solios eA/XA), which allows for rapid adjustments between frame rates i.e. 5 Hz to 50 Hz with 512 × 512 pixels. Furthermore, a motion correction algorithm is also used to mitigate motion artifacts. A customized control software called Pscan 1.0 is developed for the system. This is then followed by calibration of the imaging performance of the system and a series of quantitative in-vitro and in-vivo imaging in neuronal tissues and mice.

  4. Weak interaction: past answers, present questions

    Energy Technology Data Exchange (ETDEWEB)

    Ne' eman, Y.

    1977-02-01

    A historical sketch of the weak interaction is presented. From beta ray to pion decay, the V-A theory of Marshak and Sudarshan, CVC principle of equivalence, universality as an algebraic condition, PCAC, renormalized weak Hamiltonian in the rehabilitation of field theory, and some current issues are considered in this review. 47 references. (JFP)

  5. On modeling weak sinks in MODPATH

    Science.gov (United States)

    Abrams, Daniel B.; Haitjema, Henk; Kauffman, Leon J.

    2012-01-01

    Regional groundwater flow systems often contain both strong sinks and weak sinks. A strong sink extracts water from the entire aquifer depth, while a weak sink lets some water pass underneath or over the actual sink. The numerical groundwater flow model MODFLOW may allow a sink cell to act as a strong or weak sink, hence extracting all water that enters the cell or allowing some of that water to pass. A physical strong sink can be modeled by either a strong sink cell or a weak sink cell, with the latter generally occurring in low resolution models. Likewise, a physical weak sink may also be represented by either type of sink cell. The representation of weak sinks in the particle tracing code MODPATH is more equivocal than in MODFLOW. With the appropriate parameterization of MODPATH, particle traces and their associated travel times to weak sink streams can be modeled with adequate accuracy, even in single layer models. Weak sink well cells, on the other hand, require special measures as proposed in the literature to generate correct particle traces and individual travel times and hence capture zones. We found that the transit time distributions for well water generally do not require special measures provided aquifer properties are locally homogeneous and the well draws water from the entire aquifer depth, an important observation for determining the response of a well to non-point contaminant inputs.

  6. Spin Seebeck effect in a weak ferromagnet

    Science.gov (United States)

    Arboleda, Juan David; Arnache Olmos, Oscar; Aguirre, Myriam Haydee; Ramos, Rafael; Anadon, Alberto; Ibarra, Manuel Ricardo

    2016-06-01

    We report the observation of room temperature spin Seebeck effect (SSE) in a weak ferromagnetic normal spinel Zinc Ferrite (ZFO). Despite the weak ferromagnetic behavior, the measurements of the SSE in ZFO show a thermoelectric voltage response comparable with the reported values for other ferromagnetic materials. Our results suggest that SSE might possibly originate from the surface magnetization of the ZFO.

  7. CP Violation, Neutral Currents, and Weak Equivalence

    Science.gov (United States)

    Fitch, V. L.

    1972-03-23

    Within the past few months two excellent summaries of the state of our knowledge of the weak interactions have been presented. Correspondingly, we will not attempt a comprehensive review but instead concentrate this discussion on the status of CP violation, the question of the neutral currents, and the weak equivalence principle.

  8. Towards a classification of weak hand holds

    NARCIS (Netherlands)

    Kimmelman, V.; Sáfár, A.; Crasborn, O.

    2016-01-01

    The two symmetrical manual articulators (the hands) in signed languages are a striking modalityspecific phonetic property. The weak hand can maintain the end position of an articulation while the other articulator continues to produce additional signs. This weak hand spreading (hold) has been

  9. Revisiting Weak Simulation for Substochastic Markov Chains

    DEFF Research Database (Denmark)

    Jansen, David N.; Song, Lei; Zhang, Lijun

    2013-01-01

    The spectrum of branching-time relations for probabilistic systems has been investigated thoroughly by Baier, Hermanns, Katoen and Wolf (2003, 2005), including weak simulation for systems involving substochastic distributions. Weak simulation was proven to be sound w.r.t. the liveness fragment...

  10. S-parameters for weakly excited slots

    DEFF Research Database (Denmark)

    Albertsen, Niels Christian

    1999-01-01

    A simple approach to account for parasitic effects in weakly excited slots cut in the broad wall of a rectangular waveguide is proposed......A simple approach to account for parasitic effects in weakly excited slots cut in the broad wall of a rectangular waveguide is proposed...

  11. Weakly exact categories and the snake lemma

    CERN Document Server

    Jafari, Amir

    2009-01-01

    We generalize the notion of an exact category and introduce weakly exact categories. A proof of the snake lemma in this general setting is given. Some applications are given to illustrate how one can do homological algebra in a weakly exact category.

  12. Strong Connections and Invertible Weak Entwining Structures

    Institute of Scientific and Technical Information of China (English)

    J.N.ALONSO (A)LVAREZ; J.M.FERN(A)NDEZ VILABOA; R.GONZ(A)LEZ RODR(I)GUEZ

    2012-01-01

    In this paper we obtain a criterion under which the bijectivity of the canonical morphism of a weak Galois extension associated to a weak invertible entwining structure is equivalent to the existence of a strong connection form.Also we obtain an explicit formula for a strong connection under equivariant projective conditions or under coseparability conditions.

  13. Weakly tight functions and their decomposition

    Directory of Open Access Journals (Sweden)

    Mona Khare

    2005-01-01

    Full Text Available The present paper deals with the study of a weakly tight function and its relation to tight functions. We obtain a Jordan-decomposition-type theorem for a locally bounded weakly tight real-valued function defined on a sublattice of IX, followed by the notion of a total variation.

  14. Cohomology of Weakly Reducible Maximal Triangular Algebras

    Institute of Scientific and Technical Information of China (English)

    董浙; 鲁世杰

    2000-01-01

    In this paper, we introduce the concept of weakly reducible maximal triangular algebras φwhich form a large class of maximal triangular algebras. Let B be a weakly closed algebra containing 5φ, we prove that the cohomology spaces Hn(φ, B) (n≥1) are trivial.

  15. Fixed points of occasionally weakly biased mappings

    Directory of Open Access Journals (Sweden)

    Y. Mahendra Singh, M. R. Singh

    2012-09-01

    Full Text Available Common fixed point results due to Pant et al. [Pant et al., Weak reciprocal continuity and fixed point theorems, Ann Univ Ferrara, 57(1, 181-190 (2011] are extended to a class of non commuting operators called occasionally weakly biased pair[ N. Hussain, M. A. Khamsi A. Latif, Commonfixed points for JH-operators and occasionally weakly biased pairs under relaxed conditions, Nonlinear Analysis, 74, 2133-2140 (2011]. We also provideillustrative examples to justify the improvements. Abstract. Common fixed point results due to Pant et al. [Pant et al., Weakreciprocal continuity and fixed point theorems, Ann Univ Ferrara, 57(1, 181-190 (2011] are extended to a class of non commuting operators called occasionally weakly biased pair[ N. Hussain, M. A. Khamsi A. Latif, Common fixed points for JH-operators and occasionally weakly biased pairs under relaxed conditions, Nonlinear Analysis, 74, 2133-2140 (2011]. We also provide illustrative examples to justify the improvements.

  16. Self-Dual Weak Hopf Algebras

    Institute of Scientific and Technical Information of China (English)

    Munir AHMED; Fang LI

    2008-01-01

    In this paper, we define the notion of self-dual graded weak Hopf algebra and self-dual semilattice graded weak Hopf algebra. We give characterization of finite-dimensional such algebras when they are in structually simple forms in the sense of E. L. Green and E. N. Morcos. We also give the definition of self-dual weak Hopf quiver and apply these types of quivers to classify the finite-dimensional self-dual semilattice graded weak Hopf algebras. Finally, we prove partially the conjecture given by N. Andruskiewitsch and H.-J. Schneider in the case of finite-dimensional pointed semilattice graded weak Hopf algebra H when grH is self-dual.

  17. Atomic homodyne detection of weak atomic transitions.

    Science.gov (United States)

    Gunawardena, Mevan; Elliott, D S

    2007-01-26

    We have developed a two-color, two-pathway coherent control technique to detect and measure weak optical transitions in atoms by coherently beating the transition amplitude for the weak transition with that of a much stronger transition. We demonstrate the technique in atomic cesium, exciting the 6s(2)S(1/2) --> 8s(2)S(1/2) transition via a strong two-photon transition and a weak controllable Stark-induced transition. We discuss the enhancement in the signal-to-noise ratio for this measurement technique over that of direct detection of the weak transition rate, and project future refinements that may further improve its sensitivity and application to the measurement of other weak atomic interactions.

  18. Pay as You Speed, ISA with incentives for not speeding

    DEFF Research Database (Denmark)

    Lahrmann, Harry; Agerholm, Niels; Tradisauskas, Nerius

    2012-01-01

    The Intelligent Speed Adaptation (ISA) project we describe in this article is based on Pay as You Drive principles. These principles assume that the ISA equipment informs a driver of the speed limit, warns the driver when speeding and calculates penalty points. Each penalty point entails the redu...

  19. Monitoring speed before and during a speed publicity campaign.

    NARCIS (Netherlands)

    Schagen, I.N.L.G. van Commandeur, J.J.F. Goldenbeld, C. & Stipdonk, H.

    2016-01-01

    Driving speeds were monitored during a period of 16 weeks encompassing different stages of an anti-speeding campaign in the Netherlands. This campaign targeted speed limit violations in built-up areas. The observation periods differed in terms of intensity and media used for the campaign. Small road

  20. The role of visual processing speed in reading speed development.

    Directory of Open Access Journals (Sweden)

    Muriel Lobier

    Full Text Available A steady increase in reading speed is the hallmark of normal reading acquisition. However, little is known of the influence of visual attention capacity on children's reading speed. The number of distinct visual elements that can be simultaneously processed at a glance (dubbed the visual attention span, predicts single-word reading speed in both normal reading and dyslexic children. However, the exact processes that account for the relationship between the visual attention span and reading speed remain to be specified. We used the Theory of Visual Attention to estimate visual processing speed and visual short-term memory capacity from a multiple letter report task in eight and nine year old children. The visual attention span and text reading speed were also assessed. Results showed that visual processing speed and visual short term memory capacity predicted the visual attention span. Furthermore, visual processing speed predicted reading speed, but visual short term memory capacity did not. Finally, the visual attention span mediated the effect of visual processing speed on reading speed. These results suggest that visual attention capacity could constrain reading speed in elementary school children.

  1. Relative entropies, suitable weak solutions, and weak strong uniqueness for the compressible Navier-Stokes system

    CERN Document Server

    Feireisl, Eduard; Novotny, Antonin

    2011-01-01

    We introduce the notion of relative entropy for the weak solutions of the compressible Navier-Stokes system. We show that any finite energy weak solution satisfies a relative entropy inequality for any pair of sufficiently smooth test functions. As a corollary we establish weak-strong uniqueness principle for the compressible Navier-Stokes system.

  2. The speed of a cyclist

    Science.gov (United States)

    Hennekam, Wim

    1990-05-01

    The author illustrates an interesting application of physics teaching. The effect of a few laws of mechanics on bicycle speed are examined, and some improvements to increase bicycle speed are considered.

  3. A Construction of Weakly Inverse Semigroups

    Institute of Scientific and Technical Information of China (English)

    Bing Jun YU; Yan LI

    2009-01-01

    Let S° be an inverse semigroup with semilattice biordered set E° of idempotents and E a weakly inverse biordered set with a subsemilattice Ep = { e ∈ E |(V) f ∈ E, S(f , e)(C) w(e) } isomorphic to E° by θ:Ep→E°. In this paper, it is proved that if(V)f, g∈E, f ←→ ,g(→) f°θ (ζ)s° g°θand there exists a mapping φ from Ep into the symmetric weakly inverse semigroup (ζξ)(E ∪S°) satisfying six appropriate conditions, then a weakly inverse semigroup ∑ can be constructed in (ζξ)(S°), called the weakly inverse hull of a weakly inverse system (S°, E, θ, φ) with I(∑) ≌ S°, E(∑) (≌) E. Conversely,every weakly inverse semigroup can be constructed in this way. Furthermore, a sufficient and necessary condition for two weakly inverse hulls to be isomorphic is also given.

  4. Ultra-small phase estimation via weak measurement with postselection: A comparison of joint weak measurement and weak value amplification

    CERN Document Server

    Fang, Chen; Yu, Yang; Li, Qin-Zheng; Zeng, Guihua

    2015-01-01

    We derive a general theory for the joint weak measurement with arbitrary postselection and employ it in the time-delay measurement. Especially, we study two special cases, i.e., the balanced and unbalanced postselection regimes, and present an experiment to verify the theoretical results. The experimental results show that under similar conditions, the signal-to-noise ratio of using joint weak measurement scheme remains higher than 12 dB when the measured time-delay is smaller the ultimate precision limit of the weak-value amplification scheme. Moreover, the joint weak measurement scheme is robust to the misalignment errors and the wavelength-dependency of optical components, which indicates its advantage of improving the measurement precision with convenient laboratory equipments.

  5. High speed flywheel

    Science.gov (United States)

    McGrath, Stephen V.

    1991-01-01

    A flywheel for operation at high speeds utilizes two or more ringlike coments arranged in a spaced concentric relationship for rotation about an axis and an expansion device interposed between the components for accommodating radial growth of the components resulting from flywheel operation. The expansion device engages both of the ringlike components, and the structure of the expansion device ensures that it maintains its engagement with the components. In addition to its expansion-accommodating capacity, the expansion device also maintains flywheel stiffness during flywheel operation.

  6. The Optimum Speed Limit.

    Science.gov (United States)

    1981-05-01

    time eases the interpretation: U2 Lx -4-- where VT is the value of time (dollars (1975) per hour) V is the value of a life (dollars (1975) per L person...that for an individual, the optimal speed depends positively on his value of time and negatively on his valuation of his own life, his subjective...turn to equation (1) once again and solve for the ratio of the value of a life to the value of time , or 1 P s 2 GaS VL SP VT VT az as Rearranging

  7. Thermodynamics of gravity favours Weak Censorship Conjecture

    CERN Document Server

    Acquaviva, Giovanni; Hamid, Aymen I M; Maharaj, Sunil D

    2015-01-01

    We use the formulation of thermodynamics of gravity as proposed by Clifton, Ellis and Tavakol on the gravitational collapse of dustlike matter, that violates the strong or weak cosmic censorship conjecture depending on the initial data. We transparently demonstrate that the gravitational entropy prefers the scenario where the stronger version is violated but the weak censorship conjecture is satisfied. This is a novel result, showing the weak cosmic censorship and hence the future asymptotically simple structure of spacetime, is being validated by the nature of gravity, without imposing any extra constraint on the form of matter.

  8. Weak, strong, and uniform quantum simulations

    Science.gov (United States)

    Wang, Dong-Sheng

    2015-01-01

    In this work, we introduce different types of quantum simulations according to different operator topologies on a Hilbert space, namely, uniform, strong, and weak quantum simulations. We show that they have the same computational power that the efficiently solvable problems are in bounded-error quantum polynomial time. For the weak simulation, we formalize a general weak quantum simulation problem and construct an algorithm which is valid for all instances. Also, we analyze the computational power of quantum simulations by proving the query lower bound for simulating a general quantum process.

  9. Structural features of sequential weak measurements

    Science.gov (United States)

    Diósi, Lajos

    2016-07-01

    We discuss the abstract structure of sequential weak measurement (WM) of general observables. In all orders, the sequential WM correlations without postselection yield the corresponding correlations of the Wigner function, offering direct quantum tomography through the moments of the canonical variables. Correlations in spin-1/2 sequential weak measurements coincide with those in strong measurements, they are constrained kinematically, and they are equivalent with single measurements. In sequential WMs with postselection, an anomaly occurs, different from the weak value anomaly of single WMs. In particular, the spread of polarization σ ̂ as measured in double WMs of σ ̂ will diverge for certain orthogonal pre- and postselected states.

  10. Weak Gauge Boson Radiation in Parton Showers

    CERN Document Server

    Christiansen, Jesper Roy

    2014-01-01

    The emission of W and Z gauge boson is included in a traditional QCD + QED shower. The unitarity of the shower algorithm links the real radiation of the weak gauge bosons to the negative weak virtual corrections. The shower evolution process leads to a competition between QCD, QED and weak radiation, and allows for W and Z boson production inside jets. Various effects on LHC physics are studied, both at low and high transverse momenta, and effects at higher-energy hadron colliders are outlined.

  11. Guidelines for setting speed limits

    CSIR Research Space (South Africa)

    Wium, DJW

    1986-02-01

    Full Text Available A method is described for setting the speed limit for a particular road section. Several speed limits based on different criteria are described for each of nine traffic and road factors. The most appropriate speed limit for each relevant factor...

  12. Are vortices in rotating superfluids breaking the Weak Equivalence Principle?

    CERN Document Server

    de Matos, Clovis Jacinto

    2009-01-01

    Due to the breaking of gauge symmetry in rotating superfluid Helium, the inertial mass of a vortex diverges with the vortex size. The vortex inertial mass is thus much higher than the classical inertial mass of the vortex core. An equal increase of the vortex gravitational mass is questioned. The possibility that the vortices in a rotating superfluid could break the weak equivalence principle in relation with a variable speed of light in the superfluid vacuum is debated. Experiments to test this possibility are investigated on the bases that superfluid Helium vortices would not fall, under the single influence of a uniform gravitational field, at the same rate as the rest of the superfluid Helium mass.

  13. Totally Corrective Multiclass Boosting with Binary Weak Learners

    CERN Document Server

    Hao, Zhihui; Barnes, Nick; Wang, Bo

    2010-01-01

    In this work, we propose a new optimization framework for multiclass boosting learning. In the literature, AdaBoost.MO and AdaBoost.ECC are the two successful multiclass boosting algorithms, which can use binary weak learners. We explicitly derive these two algorithms' Lagrange dual problems based on their regularized loss functions. We show that the Lagrange dual formulations enable us to design totally-corrective multiclass algorithms by using the primal-dual optimization technique. Experiments on benchmark data sets suggest that our multiclass boosting can achieve a comparable generalization capability with state-of-the-art, but the convergence speed is much faster than stage-wise gradient descent boosting. In other words, the new totally corrective algorithms can maximize the margin more aggressively.

  14. Weak Markov Processes as Linear Systems

    CERN Document Server

    Gohm, Rolf

    2012-01-01

    A noncommutative Fornasini-Marchesini system (a multi-variable version of a linear system) can be realized within a weak Markov process (a model for quantum evolution). For a discrete time parameter this is worked out systematically as a theory of representations of structure maps of a system by a weak process. We introduce subprocesses and quotient processes which can be described naturally by a suitable category of weak processes. A corresponding notion of cascade for processes induces a represented cascade of systems. We study the control theoretic notion of observability which turns out to be particularly interesting in connection with a cascade structure. As an application we gain new insights into stationary Markov chains where observability for the system is closely related to asymptotic completeness in the scattering theory of the chain. This motivates a general definition of asymptotic completeness in the category of weak processes.

  15. Weak Lensing Simulations for the SKA

    CERN Document Server

    Patel, Prina; Makhathini, Sphesihle; Abdalla, Filipe; Bacon, David; Brown, Michael L; Heywood, Ian; Jarvis, Matt; Smirnov, Oleg

    2015-01-01

    Weak gravitational lensing measurements are traditionally made at optical wavelengths where many highly resolved galaxy images are readily available. However, the Square Kilometre Array (SKA) holds great promise for this type of measurement at radio wavelengths owing to its greatly increased sensitivity and resolution over typical radio surveys. The key to successful weak lensing experiments is in measuring the shapes of detected sources to high accuracy. In this document we describe a simulation pipeline designed to simulate radio images of the quality required for weak lensing, and will be typical of SKA observations. We provide as input, images with realistic galaxy shapes which are then simulated to produce images as they would have been observed with a given radio interferometer. We exploit this pipeline to investigate various stages of a weak lensing experiment in order to better understand the effects that may impact shape measurement. We first show how the proposed SKA1-Mid array configurations perfor...

  16. Vibration diagnostics of weak base embankments

    Institute of Scientific and Technical Information of China (English)

    Evgenij Ashpiz; Vladimir Kapustin; Svetlana Klepikova; Maxim Shirobokov

    2013-01-01

    In this paper the theoretical background was analyzed for vibration diagnostics method and experience in its application for weak base embankments. General schemes of survey and recommendations on hardware systems and further prospective development are outlined.

  17. Weak entropy inequalities and entropic convergence

    Institute of Scientific and Technical Information of China (English)

    GAO FuQing; LI LiNa

    2008-01-01

    A criterion for algebraic convergence of the entropy is presented and an algebraic convergence result for the entropy of an exclusion process is improved.A weak entropy inequality is considered and its relationship to entropic convergence is discussed.

  18. Weak entropy inequalities and entropic convergence

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A criterion for algebraic convergence of the entropy is presented and an algebraic convergence result for the entropy of an exclusion process is improved. A weak entropy inequality is considered and its relationship to entropic convergence is discussed.

  19. The Sloan Nearby Cluster Weak Lensing Survey

    CERN Document Server

    Kubo, Jeffrey M; Hardin, Frances Mei; Kubik, Donna; Lawhorn, Kelsey; Lin, Huan; Nicklaus, Liana; Nelson, Dylan; Reis, Ribamar R R; Seo, Hee-Jong; Soares-Santos, Marcelle; Stebbins, Albert; Yunker, Tony

    2009-01-01

    We describe and present initial results of a weak lensing survey of nearby ($\\rm{z}\\lesssim0.1$) galaxy clusters in the Sloan Digital Sky Survey (SDSS). In this first study, galaxy clusters are selected from the SDSS spectroscopic galaxy cluster catalogs of \\citet{miller05} and \\citet{berlind06}. We report a total of seven individual low redshift cluster weak lensing measurements which include: A2048, A1767, A2244, A1066, A2199, and two clusters specifically identified with the C4 algorithm. Our program of weak lensing of nearby galaxy clusters in the SDSS will eventually reach $\\sim 200$ clusters, making it the largest weak lensing survey of individual galaxy clusters to date.

  20. Electromagnetic and Weak transitions in light nuclei

    Energy Technology Data Exchange (ETDEWEB)

    M. Viviani; L.E. Marcucci; A. Kievsky; S. Rosati; R. Schiavilla

    2002-09-01

    Recent advances in the study of the p -- d radiative and mu -- {sup 3}He weak capture processes by our group are presented and discussed. The trinucleon bound and scattering states have been obtained from variational calculations by expanding the corresponding wave functions in terms of correlated hyper-spherical harmonic functions. The electromagnetic and weak transition currents include one- and two-body operators. The accuracy achieved in these calculations allows for interesting comparisons with experimental data.

  1. Model reduction of strong-weak neurons

    OpenAIRE

    Steven James Cox; Bosen eDu; Danny eSorensen

    2014-01-01

    We consider neurons with large dendritic trees that are weakly excitable in the sense that back propagating action potentials are severly attenuated as they travel from the small, strongly excitable, spike initiation zone. In previous work we have shown that the computational size of weakly excitable cell models may be reduced by two or more orders of magnitude, and that the size of strongly excitable models may be reduced by at least one order of magnitude, without sacrificing the spatio–tem...

  2. Agile Software Methodologies: Strength and Weakness

    OpenAIRE

    Dr. Adel Hamdan Mohammad; Dr. Tariq Alwada’n; Dr. Jafar "M.Ali" Ababneh

    2013-01-01

    Agile methodologies are great software development methodologies. No doubt that these methodologies have widespread reputation. The core of agile methodologies is people. Customer and each team member in agiledevelopment teams are the key success or failure factor in agile process. In this paper authors demonstrate strength and weakness points in agile methodologies. Also authors demonstrate how strength and weakness factors can affect the overall results of agile development process.

  3. Weak measurement and the traversal time problem

    OpenAIRE

    Iannaccone, G.

    1996-01-01

    The theory of weak measurement, proposed by Aharonov and coworkers, has been applied by Steinberg to the long-discussed traversal time problem. The uncertainty and ambiguity that characterize this concept from the perspective of von Neumann measurement theory apparently vanish, and joint probabilities and conditional averages become meaningful concepts. We express the Larmor clock and some other well-known methods in the weak measurement formalism. We also propose a method to determine higher...

  4. Drift waves in a weakly ionized plasma

    DEFF Research Database (Denmark)

    Popovic, M.; Melchior, H.

    1968-01-01

    A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated.......A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated....

  5. The minimal habitat size for spreading in a weak competition system with two free boundaries

    Science.gov (United States)

    Wu, Chang-Hong

    2015-08-01

    In this paper, we focus on the dynamics for a Lotka-Volterra type weak competition system with two free boundaries, where free boundaries which may intersect each other as time evolves are used to describe the spreading of two competing species, respectively. In the weak competition case, the dynamics of this model can be classified into four cases, which forms a spreading-vanishing quartering. The notion of the minimal habitat size for spreading is introduced to determine if species can always spread. Some sufficient conditions for spreading and vanishing are established. Also, when spreading occurs, some rough estimates for spreading speed and the long-time behavior of solutions are established.

  6. Quantum Butterfly Effect in Weakly Interacting Diffusive Metals

    Directory of Open Access Journals (Sweden)

    Aavishkar A. Patel

    2017-09-01

    Full Text Available We study scrambling, an avatar of chaos, in a weakly interacting metal in the presence of random potential disorder. It is well known that charge and heat spread via diffusion in such an interacting disordered metal. In contrast, we show within perturbation theory that chaos spreads in a ballistic fashion. The squared anticommutator of the electron-field operators inherits a light-cone-like growth, arising from an interplay of a growth (Lyapunov exponent that scales as the inelastic electron scattering rate and a diffusive piece due to the presence of disorder. In two spatial dimensions, the Lyapunov exponent is universally related at weak coupling to the sheet resistivity. We are able to define an effective temperature-dependent butterfly velocity, a speed limit for the propagation of quantum information that is much slower than microscopic velocities such as the Fermi velocity and that is qualitatively similar to that of a quantum critical system with a dynamical critical exponent z>1.

  7. Strength and Weakness of Animal Vaccine Industry in China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Based on the introduction of the status of animal vaccine industry in China,the strength,weakness,opportunity and threat of animal vaccine industry are analyzed by SWOT. Among them,strength is mainly reflected in the broad market,and the favorable industrial policy and development environment. Weakness is the irrational structure of product,the nonstandard production inspection,and the irregular market. Opportunity is mainly reflected in improving government’s emphasis on animal security,expanding the scope of compulsory immunization,increasing the proportion of scale breeding,upgrading animal vaccine in China,speeding up industry consolidation and improving market concentration. Threat is manifested mainly in the poor market consciousness due to the long-term planned economy. And animal vaccine enterprises in China are at a relatively disadvantage position during the competition with international companies. Based on these,countermeasures to promote the development of animal vaccine enterprises in China are put forward from the aspects of both government and enterprise. On the one hand,government should improve the laws and regulations and promote the healthy development of vaccine industry,strengthen the manufacturers’ consciousness of quality and biological safety,and create a favorable environment for market competition. On the other hand,enterprises should adjust the product structure and strengthen research and innovation,improve the brand competitiveness,take the road of common development,enhance the management capacity of the enterprises,and promote customer service.

  8. HIGH SPEED CAMERA

    Science.gov (United States)

    Rogers, B.T. Jr.; Davis, W.C.

    1957-12-17

    This patent relates to high speed cameras having resolution times of less than one-tenth microseconds suitable for filming distinct sequences of a very fast event such as an explosion. This camera consists of a rotating mirror with reflecting surfaces on both sides, a narrow mirror acting as a slit in a focal plane shutter, various other mirror and lens systems as well as an innage recording surface. The combination of the rotating mirrors and the slit mirror causes discrete, narrow, separate pictures to fall upon the film plane, thereby forming a moving image increment of the photographed event. Placing a reflecting surface on each side of the rotating mirror cancels the image velocity that one side of the rotating mirror would impart, so as a camera having this short a resolution time is thereby possible.

  9. In situ local shock speed and transit shock speed

    Directory of Open Access Journals (Sweden)

    S. Watari

    Full Text Available A useful index for estimating the transit speeds was derived by analyzing interplanetary shock observations. This index is the ratio of the in situ local shock speed and the transit speed; it is 0.6–0.9 for most observed shocks. The local shock speed and the transit speed calculated for the results of the magnetohydrodynamic simulation show good agreement with the observations. The relation expressed by the index is well explained by a simplified propagation model assuming a blast wave. For several shocks the ratio is approximately 1.2, implying that these shocks accelerated during propagation in slow-speed solar wind. This ratio is similar to that for the background solar wind acceleration.

    Keywords. Interplanetary physics (Flare and stream dynamics; Interplanetary shocks; Solar wind plasma

  10. Speed-calming measures and their Effect on driving speed

    DEFF Research Database (Denmark)

    Agerholm, Niels; Knudsen, Daniel; Variyeswaran, Kajan

    2017-01-01

    Speeding increases the risk and severity of accidents, especially for vulnerable road users. Hence, minimisation of speeding in built-up areas is vital. Some countries widely use speed-calming measures (SCs). Documentation shows that SCs reduce speeding considerably although various types...... and designs of SCs affect this reduction. This paper includes studies of the effects from establishment of sinus speed humps of height 10 cm and length 950 cm and chicanes (with a free carriageway width of 5,30 cm and a length between the 0.5 m wide obstacles of 18 m) as a before/after study where the speed...... pattern after establishing SCs is compared with the one before. Floating Car Data used for analyses includes 3,216 trips passing one/more SCs. The main results are that the effect from SCs decreases with the distance from the SCs and that a clear pattern is hard to establish above 75 m from the SC...

  11. Enhancing QKD security with weak measurements

    Science.gov (United States)

    Farinholt, Jacob M.; Troupe, James E.

    2016-10-01

    Publisher's Note: This paper, originally published on 10/24/2016, was replaced with a corrected/revised version on 11/8/2016. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance. In the late 1980s, Aharonov and colleagues developed the notion of a weak measurement of a quantum observable that does not appreciably disturb the system.1, 2 The measurement results are conditioned on both the pre-selected and post-selected state of the quantum system. While any one measurement reveals very little information, by making the same measurement on a large ensemble of identically prepared pre- and post-selected (PPS) states and averaging the results, one may obtain what is known as the weak value of the observable with respect to that PPS ensemble. Recently, weak measurements have been proposed as a method of assessing the security of QKD in the well-known BB84 protocol.3 This weak value augmented QKD protocol (WV-QKD) works by additionally requiring the receiver, Bob, to make a weak measurement of a particular observable prior to his strong measurement. For the subset of measurement results in which Alice and Bob's measurement bases do not agree, the weak measurement results can be used to detect any attempt by an eavesdropper, Eve, to correlate her measurement results with Bob's. Furthermore, the well-known detector blinding attacks, which are known to perfectly correlate Eve's results with Bob's without being caught by conventional BB84 implementations, actually make the eavesdropper more visible in the new WV-QKD protocol. In this paper, we will introduce the WV-QKD protocol and discuss its generalization to the 6-state single qubit protocol. We will discuss the types of weak measurements that are optimal for this protocol, and compare the predicted performance of the 6- and 4-state WV-QKD protocols.

  12. Speed control at low wind speeds for a variable speed fixed pitch wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Rosmin, N.; Watson, S.J.; Tompson, M. [Loughborough Univ., Loughborough, Leicestershire (United Kingdom)

    2010-03-09

    The maximum power regulation below rated wind speed is regulated by changing the rotor/generator speed at large frequency range in a fixed pitch, variable speed, stall-regulated wind turbine. In order to capture the power at a maximum value the power coefficient is kept at maximum peak point by maintaining the tip speed ratio at its optimum value. The wind industry is moving from stall regulated fixed speed wind turbines to newer improved innovative versions with better reliability. While a stall regulated fixed pitch wind turbine is among the most cost-effective wind turbine on the market, its problems include noise, severe vibrations, high thrust loads and low power efficiency. Therefore, in order to improve such drawbacks, the rotation of the generator speed is made flexible where the rotation can be controlled in variable speed. This paper discussed the development of a simulation model which represented the behaviour of a stall regulated variable speed wind turbine at low wind speed control region by using the closed loop scalar control with adjustable speed drive. The paper provided a description of each sub-model in the wind turbine system and described the scalar control of the induction machine. It was concluded that by using a constant voltage/frequency ratio of the generator's stator side control, the generator speed could be regulated and the generator torque could be controlled to ensure the power coefficient could be maintained close to its maximum value. 38 refs., 1 tab., 10 figs.

  13. The Role of Visual Processing Speed in Reading Speed Development

    OpenAIRE

    Muriel Lobier; Matthieu Dubois; Sylviane Valdois

    2013-01-01

    A steady increase in reading speed is the hallmark of normal reading acquisition. However, little is known of the influence of visual attention capacity on children's reading speed. The number of distinct visual elements that can be simultaneously processed at a glance (dubbed the visual attention span), predicts single-word reading speed in both normal reading and dyslexic children. However, the exact processes that account for the relationship between the visual attention span and reading s...

  14. Experimental noiseless linear amplification using weak measurements

    Science.gov (United States)

    Ho, Joseph; Boston, Allen; Palsson, Matthew; Pryde, Geoff

    2016-09-01

    The viability of quantum communication schemes rely on sending quantum states of light over long distances. However, transmission loss can degrade the signal strength, adding noise. Heralded noiseless amplification of a quantum signal can provide a solution by enabling longer direct transmission distances and by enabling entanglement distillation. The central idea of heralded noiseless amplification—a conditional modification of the probability distribution over photon number of an optical quantum state—is suggestive of a parallel with weak measurement: in a weak measurement, learning partial information about an observable leads to a conditional back-action of a commensurate size. Here we experimentally investigate the application of weak, or variable-strength, measurements to the task of heralded amplification, by using a quantum logic gate to weakly couple a small single-optical-mode quantum state (the signal) to an ancilla photon (the meter). The weak measurement is carried out by choosing the measurement basis of the meter photon and, by conditioning on the meter outcomes, the signal is amplified. We characterise the gain of the amplifier as a function of the measurement strength, and use interferometric methods to show that the operation preserves the coherence of the signal.

  15. Weak crystallization theory of metallic alloys

    Science.gov (United States)

    Martin, Ivar; Gopalakrishnan, Sarang; Demler, Eugene A.

    2016-06-01

    Crystallization is one of the most familiar, but hardest to analyze, phase transitions. The principal reason is that crystallization typically occurs via a strongly first-order phase transition, and thus rigorous treatment would require comparing energies of an infinite number of possible crystalline states with the energy of liquid. A great simplification occurs when crystallization transition happens to be weakly first order. In this case, weak crystallization theory, based on unbiased Ginzburg-Landau expansion, can be applied. Even beyond its strict range of validity, it has been a useful qualitative tool for understanding crystallization. In its standard form, however, weak crystallization theory cannot explain the existence of a majority of observed crystalline and quasicrystalline states. Here we extend the weak crystallization theory to the case of metallic alloys. We identify a singular effect of itinerant electrons on the form of weak crystallization free energy. It is geometric in nature, generating strong dependence of free energy on the angles between ordering wave vectors of ionic density. That leads to stabilization of fcc, rhombohedral, and icosahedral quasicrystalline (iQC) phases, which are absent in the generic theory with only local interactions. As an application, we find the condition for stability of iQC that is consistent with the Hume-Rothery rules known empirically for the majority of stable iQC; namely, the length of the primary Bragg-peak wave vector is approximately equal to the diameter of the Fermi sphere.

  16. Weak KAM theory for a weakly coupled system of Hamilton–Jacobi equations

    KAUST Repository

    Figalli, Alessio

    2016-06-23

    Here, we extend the weak KAM and Aubry–Mather theories to optimal switching problems. We consider three issues: the analysis of the calculus of variations problem, the study of a generalized weak KAM theorem for solutions of weakly coupled systems of Hamilton–Jacobi equations, and the long-time behavior of time-dependent systems. We prove the existence and regularity of action minimizers, obtain necessary conditions for minimality, extend Fathi’s weak KAM theorem, and describe the asymptotic limit of the generalized Lax–Oleinik semigroup. © 2016, Springer-Verlag Berlin Heidelberg.

  17. High-speed AC motors

    Energy Technology Data Exchange (ETDEWEB)

    Jokinen, T.; Arkkio, A. [Helsinki University of Technology Laboratory of Electromechanics, Otaniemi (Finland)

    1997-12-31

    The paper deals with various types of highspeed electric motors, and their limiting powers. Standard machines with laminated rotors can be utilised if the speed is moderate. The solid rotor construction makes it possible to reach higher power and speed levels than those of laminated rotors. The development work on high-speed motors done at Helsinki University of Technology is presented, too. (orig.) 12 refs.

  18. Uniform and weak stability of Bresse system with two infinite memories

    Science.gov (United States)

    Guesmia, Aissa; Kirane, Mokhtar

    2016-10-01

    In this paper, we consider one-dimensional linear Bresse systems in a bounded open domain under Dirichlet-Neumann-Neumann boundary conditions with two infinite memories acting only on two equations. First, we establish the well-posedness in the sense of semigroup theory. Then, we prove two (uniform and weak) decay estimates depending on the speeds of wave propagations, the smoothness of initial data and the arbitrarily growth at infinity of the two relaxation functions.

  19. The CABARET method for a weakly compressible fluid flows in one- and two-dimensional implementations

    Science.gov (United States)

    Kulikov, Yu M.; Son, E. E.

    2016-11-01

    The CABARET method implementation for a weakly compressible fluid flow is in the focus of present paper. Testing both one-dimensional pressure balancing problem and a classical plane Poiseuille flow, we analyze this method in terms of discontinuity resolution, dispersion and dissipation. The method is proved to have an adequate convergence to an analytical solution for a velocity profile. We also show that a flow formation process represents a set of self-similar solutions under varying pressure differential and sound speed.

  20. Weakly isolated horizon information loss paradox

    CERN Document Server

    Chen, Ge-Rui

    2014-01-01

    In this paper we investigate the information loss paradox of weakly isolated horizon(WIH) based on the Parikh and Wilczek's tunneling spectrum. We find that there are correlations among Hawking radiations from weakly isolated horizon, the information can be carried out in terms of correlations between sequential emissions, and the radiation is an entropy conservation process. We generalize Refs.[11-13]' results to a more general spacetime. Through revisiting the calculation of tunneling of weakly isolated horizon, we find that Ref.[12]'s requirement that radiating particles have the same angular momenta of unit mass as that of black hole is not needed, and the energy and angular momenta of emitting particles are very arbitrary, which should be restricted only by keeping the cosmic censorship of black hole.

  1. Revealed Quantum Information in Weak Interaction Processes

    CERN Document Server

    Hiesmayr, B C

    2014-01-01

    We analyze the achievable limits of the quantum information processing of the weak interaction revealed by hyperons with spin. We find that the weak decay process corresponds to an interferometric device with a fixed visibility and fixed phase difference for each hyperon. Nature chooses rather low visibilities expressing a preference to parity conserving or violating processes (except for the decay $\\Sigma^+\\longrightarrow p \\pi^0$). The decay process can be considered as an open quantum channel that carries the information of the hyperon spin to the angular distribution of the momentum of the daughter particles. We find a simple geometrical information theoretic interpretation of this process: two quantization axes are chosen spontaneously with probabilities $\\frac{1\\pm\\alpha}{2}$ where $\\alpha$ is proportional to the visibility times the real part of the phase shift. Differently stated the weak interaction process corresponds to spin measurements with an imperfect Stern-Gerlach apparatus. Equipped with this...

  2. Respiratory muscle weakness in peripheral neuropathies.

    Science.gov (United States)

    Burakgazi, Ahmet Z; Höke, Ahmet

    2010-12-01

    Common peripheral neuropathies do not usually cause diaphragmatic weakness and subsequent respiratory compromise. However, respiratory involvement is relatively common in Guillain-Barré syndrome (GBS). Experience in GBS has led to a standardized approach to manage respiratory problems in peripheral neuropathies. Diaphragmatic weakness is not common in chronic inflammatory demyelinating polyneuropathy and extremely rare in multifocal motor neuropathy. The linkage has been described between certain subtypes of Charcot-Marie-Tooth (CMT) disease such as CMT2C and CMT4B1 and diaphragmatic weakness. A correlation usually has not been found between electrophysiologic findings and clinical respiratory signs or spirometric abnormalities in peripheral neuropathies except in amplitudes of evoked phrenic nerve responses. Careful and frequent assessment of respiratory function by a qualified team of healthcare professionals and physicians is essential. Criteria established for mechanical ventilation in GBS cases may be applied to other peripheral neuropathies with respiratory compromise as necessary.

  3. Evidence for a Lattice Weak Gravity Conjecture

    CERN Document Server

    Heidenreich, Ben; Rudelius, Tom

    2016-01-01

    The Weak Gravity Conjecture postulates the existence of superextremal charged particles, i.e. those with mass smaller than or equal to their charge in Planck units. We present further evidence for our recent observation that in known examples a much stronger statement is true: an infinite tower of superextremal particles of different charges exists. We show that effective Kaluza-Klein field theories and perturbative string vacua respect the Sublattice Weak Gravity Conjecture, namely that a finite index sublattice of the full charge lattice exists with a superextremal particle at each site. In perturbative string theory we show that this follows from modular invariance. However, we present counterexamples to the stronger possibility that a superextremal state exists at every lattice site, including an example in which the lightest charged state is subextremal. The Sublattice Weak Gravity Conjecture has many implications both for abstract theories of quantum gravity and for real-world physics. For instance, it ...

  4. Weak lensing in the Dark Energy Survey

    Science.gov (United States)

    Troxel, Michael

    2016-03-01

    I will present the current status of weak lensing results from the Dark Energy Survey (DES). DES will survey 5000 square degrees in five photometric bands (grizY), and has already provided a competitive weak lensing catalog from Science Verification data covering just 3% of the final survey footprint. I will summarize the status of shear catalog production using observations from the first year of the survey and discuss recent weak lensing science results from DES. Finally, I will report on the outlook for future cosmological analyses in DES including the two-point cosmic shear correlation function and discuss challenges that DES and future surveys will face in achieving a control of systematics that allows us to take full advantage of the available statistical power of our shear catalogs.

  5. The strong side of weak topological insulators

    Science.gov (United States)

    Kraus, Yaacov; Ringel, Zohar; Stern, Ady

    2012-02-01

    Three-dimensional topological insulators are classified into ``strong'' (STI) and ``weak'' (WTI) according to the nature of their surface states. While the surface states of the STI are topologically protected, in the WTI they are believed to be very fragile to disorder. In this work we show that the WTI surface states are actually protected from any random perturbation which does not break time-reversal symmetry, and does not close the bulk energy gap. Consequently, the conductivity of metallic surfaces in the clean system will remain finite even in the presence of strong disorder of this type. In the weak disorder limit the surfaces are perfect metals, and strong surface disorder only acts to push them inwards. We find that WTI's differ from STI's primarily in their anisotropy, and that the anisotropy is not a sign of their weakness but rather of their richness.

  6. No-Hair Theorem for Weak Pulsar

    CERN Document Server

    Gruzinov, Andrei

    2015-01-01

    It is proposed that there exists a class of pulsars, called weak pulsars, for which the large-scale magnetosphere, and hence the gamma-ray emission, are independent of the detailed pattern of plasma production. The weak pulsar magnetosphere and its gamma-ray emission are uniquely determined by just three parameters: spin, dipole, and the spin-dipole angle. We calculate this supposedly unique pulsar magnetosphere in the axisymmetric case. The magnetosphere is found to be very close to (although interestingly not fully identical with) the magnetosphere we have previously calculated, explaining the phenomenological success of the old calculation. We offer only a highly tentative proof of this "Pulsar No-Hair Theorem". Our analytics, while convincing in its non-triviality, is incomplete, and counts only as a plausibility argument. Our numerics, while complete, is dubious. The plasma flow in the weak pulsar magnetosphere turns out to be even more intricate than what we have previously proposed: some particles, aft...

  7. Phase slips in superconducting weak links

    Energy Technology Data Exchange (ETDEWEB)

    Kimmel, Gregory; Glatz, Andreas; Aranson, Igor S.

    2017-01-01

    Superconducting vortices and phase slips are primary mechanisms of dissipation in superconducting, superfluid, and cold-atom systems. While the dynamics of vortices is fairly well described, phase slips occurring in quasi-one- dimensional superconducting wires still elude understanding. The main reason is that phase slips are strongly nonlinear time-dependent phenomena that cannot be cast in terms of small perturbations of the superconducting state. Here we study phase slips occurring in superconducting weak links. Thanks to partial suppression of superconductivity in weak links, we employ a weakly nonlinear approximation for dynamic phase slips. This approximation is not valid for homogeneous superconducting wires and slabs. Using the numerical solution of the time-dependent Ginzburg-Landau equation and bifurcation analysis of stationary solutions, we show that the onset of phase slips occurs via an infinite period bifurcation, which is manifested in a specific voltage-current dependence. Our analytical results are in good agreement with simulations.

  8. Pay as You Speed, ISA with incentive for not speeding: results and interpretation of speed data.

    Science.gov (United States)

    Lahrmann, Harry; Agerholm, Niels; Tradisauskas, Nerius; Berthelsen, Kasper K; Harms, Lisbeth

    2012-09-01

    To simulate a market introduction of Intelligent Speed Adaptation (ISA) and to study the effect of a Pay as You Speed (PAYS) concept, a field trial with 153 drivers was conducted during 2007-2009. The participants drove under PAYS conditions for a shorter or a longer period. The PAYS concept consisted of informative ISA linked with economic incentive for not speeding, measured through automatic count of penalty points whenever the speed limit was exceeded. The full incentive was set to 30% of a participant's insurance premium. The participants were exposed to different treatments, with and without incentive crossed with informative ISA present or absent. The results showed that ISA is an efficient tool for reducing speeding particularly on rural roads. The analysis of speed data demonstrated that the proportion of distance driven above the speed where the ISA equipment responded (PDA) was a sensitive measure for reflecting the effect of ISA, whereas mean free flow speed and the 85th percentile speed, were less sensitive to ISA effects. The PDA increased a little over time but still remained at a low level; however, when ISA was turned off, the participants' speeding relapsed to the baseline level. Both informative ISA and incentive ISA reduced the PDA, but there was no statistically significant interaction. Informative reduced it more than the incentive.

  9. Interpolation for weak Orlicz spaces with M_Δ condition

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An interpolation theorem for weak Orlicz spaces generalized by N-functions satisfying MΔ condition is given. It is proved to be true for weak Orlicz martingale spaces by weak atomic decomposition of weak Hardy martingale spaces. And applying the interpolation theorem, we obtain some embedding relationships among weak Orlicz martingale spaces.

  10. Wind speed perception and risk.

    Directory of Open Access Journals (Sweden)

    Duzgun Agdas

    Full Text Available BACKGROUND: How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human-wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. METHOD: We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. RESULTS: Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk. The number of tropical cyclones people had experienced moderated the strength of the actual-perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. CONCLUSION: These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters.

  11. Wind Speed Perception and Risk

    Science.gov (United States)

    Agdas, Duzgun; Webster, Gregory D.; Masters, Forrest J.

    2012-01-01

    Background How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human–wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. Method We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s) winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. Results Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk). The number of tropical cyclones people had experienced moderated the strength of the actual–perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. Conclusion These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters. PMID:23226230

  12. High Speed Viterbi Decoder Architecture

    DEFF Research Database (Denmark)

    Paaske, Erik; Andersen, Jakob Dahl

    1998-01-01

    The fastest commercially available Viterbi decoders for the (171,133) standard rate 1/2 code operate with a decoding speed of 40-50 Mbit/s (net data rate). In this paper we present a suitable architecture for decoders operating with decoding speeds of 150-300 Mbit/s.......The fastest commercially available Viterbi decoders for the (171,133) standard rate 1/2 code operate with a decoding speed of 40-50 Mbit/s (net data rate). In this paper we present a suitable architecture for decoders operating with decoding speeds of 150-300 Mbit/s....

  13. Weak Acid Ionization Constants and the Determination of Weak Acid-Weak Base Reaction Equilibrium Constants in the General Chemistry Laboratory

    Science.gov (United States)

    Nyasulu, Frazier; McMills, Lauren; Barlag, Rebecca

    2013-01-01

    A laboratory to determine the equilibrium constants of weak acid negative weak base reactions is described. The equilibrium constants of component reactions when multiplied together equal the numerical value of the equilibrium constant of the summative reaction. The component reactions are weak acid ionization reactions, weak base hydrolysis…

  14. Weak Acid Ionization Constants and the Determination of Weak Acid-Weak Base Reaction Equilibrium Constants in the General Chemistry Laboratory

    Science.gov (United States)

    Nyasulu, Frazier; McMills, Lauren; Barlag, Rebecca

    2013-01-01

    A laboratory to determine the equilibrium constants of weak acid negative weak base reactions is described. The equilibrium constants of component reactions when multiplied together equal the numerical value of the equilibrium constant of the summative reaction. The component reactions are weak acid ionization reactions, weak base hydrolysis…

  15. Dixon's extended bodies and weak gravitational waves

    CERN Document Server

    Bini, Donato; Geralico, Andrea; Ortolan, Antonello

    2009-01-01

    General relativity considers Dixon's theory as the standard theory to deal with the motion of extended bodies in a given gravitational background. We discuss here the features of the "reaction" of an extended body to the passage of a weak gravitational wave. We find that the body acquires a dipolar moment induced by its quadrupole structure. Furthermore, we derive the "world function" for the weak field limit of a gravitational wave background and use it to estimate the deviation between geodesics and the world lines of structured bodies. Measuring such deviations, due to the existence of cumulative effects, should be favorite with respect to measuring the amplitude of the gravitational wave itself.

  16. Landau Weak Crystallization Theory and its Applications

    Science.gov (United States)

    Kats, E. I.

    Aim of this lecture is to explain main features and ingredients of weak first order phase transitions between liquid-like (uniform in space) and solid-like (non-uniform with characteristic wave vector q0) states. We illustrate how this theory (traditionally termed as Landau weak crystallization theory) works. We consider two examples describing universal temperature dependence of shear viscosity in liquids, and so-called main phase transition in membranes. Our results are in a good qualitative agreement with experimental data, offering a deeper understanding of this kind of phase transitions. We discuss also why and where predicted universal effects can be masked.

  17. Simple understanding of quantum weak values

    Science.gov (United States)

    Qin, Lupei; Feng, Wei; Li, Xin-Qi

    2016-02-01

    In this work we revisit the important and controversial concept of quantum weak values, aiming to provide a simplified understanding to its associated physics and the origin of anomaly. Taking the Stern-Gerlach setup as a working system, we base our analysis on an exact treatment in terms of quantum Bayesian approach. We also make particular connection with a very recent work, where the anomaly of the weak values was claimed from the pure statistics in association with “disturbance” and “post-selection”, rather than the unique quantum nature. Our analysis resolves the related controversies through a clear and quantitative way.

  18. Critical level statistics for weakly disordered graphene.

    Science.gov (United States)

    Amanatidis, E; Kleftogiannis, I; Katsanos, D E; Evangelou, S N

    2014-04-16

    In two dimensions chaotic level statistics with the Wigner spacing distribution P(S) is expected for massless fermions in the Dirac region. The obtained P(S) for weakly disordered finite graphene samples with zigzag edges turns out, however, to be neither chaotic (Wigner) nor localized (Poisson). It is similar to the intermediate statistics at the critical point of the Anderson metal-insulator transition. The quantum transport of finite graphene for weak disorder, with critical level statistics can occur via edge states as in topological insulators, and for strong disorder, graphene behaves as an ordinary Anderson insulator with Poisson statistics.

  19. A Weakly Homomorphic Encryption with LDN

    Directory of Open Access Journals (Sweden)

    Chao Feng

    2014-06-01

    Full Text Available As an effective solution to protect the privacy of the data, homomorphic encryption has become a hot research topic. Existing homomorphic schemes are not truly practical due to their huge key size. In this paper, we present a simple weakly homomorphic encryption scheme using only elementary modular arithmetic over the integers rather than working with ideal lattices. Compared with DGHV’s construction, the proposed scheme has shorter public key and ciphertext size. The main appeal of our approach is the conceptual simplicity. We reduce the security of weakly homomorphic scheme to “learning divisor with noise (LDN”

  20. Charged current weak electroproduction of $\\Delta$ resonance

    CERN Document Server

    Alvarez-Ruso, L; Vacas, M J V

    1998-01-01

    We study the weak production of $\\Delta$ (i.e. $e^{-} + p \\to \\Delta^{0}+ energy range corresponding to the Mainz and TJNAF electron accelerators. The differential cross sections $\\sigma(\\theta)$ are found to be of the order of $ 10^{-39}$ cm$^2$/sr, over a range of angles which increases with energy. The possibility of observing these reactions with the high luminosities available at these accelerators, and studying the weak N-$\\Delta$ transition form factors through these reactions is discussed. The production cross section of N$^*(1440)$ in the kinematic region of $\\Delta$ production is also estimated and found to be small.

  1. Students’ Weakness Detective in Traditional Class

    Directory of Open Access Journals (Sweden)

    Fatimah Altuhaifa

    2016-10-01

    Full Text Available In Artificial Intelligent in Education in learning contexts and domains, the traditional classroom is tough to find students’ weakness during lecture due to the student’s number and because the instruction is busy with explaining the lesson. According to that, choosing teaching style that can improve student talent or skills to performs better in their classes or professional life would not be an easy task. This system is going to detect the average of students’ weakness and find either a solution for this or instruction a style that can increase students’ ability and skills by filtering the collection data, understanding the problem. After that, it provides a teaching style.

  2. Compressive wavefront sensing with weak values.

    Science.gov (United States)

    Howland, Gregory A; Lum, Daniel J; Howell, John C

    2014-08-11

    We demonstrate a wavefront sensor that unites weak measurement and the compressive-sensing, single-pixel camera. Using a high-resolution spatial light modulator (SLM) as a variable waveplate, we weakly couple an optical field's transverse-position and polarization degrees of freedom. By placing random, binary patterns on the SLM, polarization serves as a meter for directly measuring random projections of the wavefront's real and imaginary components. Compressive-sensing optimization techniques can then recover the wavefront. We acquire high quality, 256 × 256 pixel images of the wavefront from only 10,000 projections. Photon-counting detectors give sub-picowatt sensitivity.

  3. From Suitable Weak Solutions to Entropy Viscosity

    KAUST Repository

    Guermond, Jean-Luc

    2010-12-16

    This paper focuses on the notion of suitable weak solutions for the three-dimensional incompressible Navier-Stokes equations and discusses the relevance of this notion to Computational Fluid Dynamics. The purpose of the paper is twofold (i) to recall basic mathematical properties of the three-dimensional incompressible Navier-Stokes equations and to show how they might relate to LES (ii) to introduce an entropy viscosity technique based on the notion of suitable weak solution and to illustrate numerically this concept. © 2010 Springer Science+Business Media, LLC.

  4. Weak interactions at high energies. [Lectures, review

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, J.

    1978-08-01

    Review lectures are presented on the phenomenological implications of the modern spontaneously broken gauge theories of the weak and electromagnetic interactions, and some observations are made about which high energy experiments probe what aspects of gauge theories. Basic quantum chromodynamics phenomenology is covered including momentum dependent effective quark distributions, the transverse momentum cutoff, search for gluons as sources of hadron jets, the status and prospects for the spectroscopy of fundamental fermions and how fermions may be used to probe aspects of the weak and electromagnetic gauge theory, studies of intermediate vector bosons, and miscellaneous possibilities suggested by gauge theories from the Higgs bosons to speculations about proton decay. 187 references. (JFP)

  5. Measuring the dark side (with weak lensing)

    CERN Document Server

    Amendola, Luca; Sapone, Domenico

    2007-01-01

    We introduce a convenient parametrization of dark energy models that is general enough to include several modified gravity models and generalized forms of dark energy. In particular we take into account the linear perturbation growth factor, the anisotropic stress and the modified Poisson equation. We discuss the sensitivity of large scale weak lensing surveys like the proposed DUNE satellite to these parameters. We find that a large-scale weak-lensing tomographic survey is able to easily distinguish the Dvali-Gabadadze-Porrati model from LCDM and to determine the perturbation growth index to an absolute error of 0.02-0.03.

  6. Weak Lie symmetry and extended Lie algebra

    Energy Technology Data Exchange (ETDEWEB)

    Goenner, Hubert [Institute for Theoretical Physics, Friedrich-Hund-Platz 1, University of Goettingen, D-37077 Gottingen (Germany)

    2013-04-15

    The concept of weak Lie motion (weak Lie symmetry) is introduced. Applications given exhibit a reduction of the usual symmetry, e.g., in the case of the rotation group. In this context, a particular generalization of Lie algebras is found ('extended Lie algebras') which turns out to be an involutive distribution or a simple example for a tangent Lie algebroid. Riemannian and Lorentz metrics can be introduced on such an algebroid through an extended Cartan-Killing form. Transformation groups from non-relativistic mechanics and quantum mechanics lead to such tangent Lie algebroids and to Lorentz geometries constructed on them (1-dimensional gravitational fields).

  7. A Continuation Method for Weakly Kannan Maps

    Directory of Open Access Journals (Sweden)

    Ariza-Ruiz David

    2010-01-01

    Full Text Available The first continuation method for contractive maps in the setting of a metric space was given by Granas. Later, Frigon extended Granas theorem to the class of weakly contractive maps, and recently Agarwal and O'Regan have given the corresponding result for a certain type of quasicontractions which includes maps of Kannan type. In this note we introduce the concept of weakly Kannan maps and give a fixed point theorem, and then a continuation method, for this class of maps.

  8. PS1-10afx AT z = 1.388: PAN-STARRS1 DISCOVERY OF A NEW TYPE OF SUPERLUMINOUS SUPERNOVA

    Energy Technology Data Exchange (ETDEWEB)

    Chornock, R.; Berger, E.; Milisavljevic, D.; Lunnan, R.; Foley, R. J.; Soderberg, A. M.; Challis, P.; Czekala, I.; Drout, M.; Fong, W.; Kirshner, R. P.; McLeod, B.; Marion, G. H.; Narayan, G. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Rest, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Smartt, S. J. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast, BT7 1NN (United Kingdom); Burgasser, A. J. [Center for Astrophysics and Space Science, University of California San Diego, La Jolla, CA 92093 (United States); Chomiuk, L. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Huber, M. E. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Leibler, C., E-mail: rchornock@cfa.harvard.edu [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95060 (United States); and others

    2013-04-20

    We present the Pan-STARRS1 discovery of PS1-10afx, a unique hydrogen-deficient superluminous supernova (SLSN) at redshift z = 1.388. The light curve peaked at z{sub P1} = 21.7 mag, making PS1-10afx comparable to the most luminous known SNe, with M{sub u} = -22.3 mag. Our extensive optical and near-infrared observations indicate that the bolometric light curve of PS1-10afx rose on the unusually fast timescale of {approx}12 days to the extraordinary peak luminosity of 4.1 Multiplication-Sign 10{sup 44} erg s{sup -1} (M{sub bol} = -22.8 mag) and subsequently faded rapidly. Equally important, the spectral energy distribution is unusually red for an SLSN, with a color temperature of {approx}6800 K near maximum light, in contrast to previous hydrogen-poor SLSNe, which are bright in the ultraviolet (UV). The spectra more closely resemble those of a normal SN Ic than any known SLSN, with a photospheric velocity of {approx}11, 000 km s{sup -1} and evidence for line blanketing in the rest-frame UV. Despite the fast rise, these parameters imply a very large emitting radius ({approx}> 5 Multiplication-Sign 10{sup 15} cm). We demonstrate that no existing theoretical model can satisfactorily explain this combination of properties: (1) a nickel-powered light curve cannot match the combination of high peak luminosity with the fast timescale; (2) models powered by the spindown energy of a rapidly rotating magnetar predict significantly hotter and faster ejecta; and (3) models invoking shock breakout through a dense circumstellar medium cannot explain the observed spectra or color evolution. The host galaxy is well detected in pre-explosion imaging with a luminosity near L*, a star formation rate of {approx}15 M{sub Sun} yr{sup -1}, and is fairly massive ({approx}2 Multiplication-Sign 10{sup 10} M{sub Sun }), with a stellar population age of {approx}10{sup 8} yr, also in contrast to the young dwarf hosts of known hydrogen-poor SLSNe. PS1-10afx is distinct from known examples of

  9. OPERA超光速中微子与人类对时空观的认识历程%OPERA Superluminal Neutrinos and Evolutions of Spacetime Concepts

    Institute of Scientific and Technical Information of China (English)

    邵立晶; 马伯强

    2011-01-01

    The understanding of space and time is the most important aspect of theoretical physics, and the current foundation of modern physics is based upon Einstein's relativistic spacetime. However, OPERA collaboration recently published their finding that muon neutrinos might travel faster than light, if proved, which will present a big revolution of Einstein's spacetime concepts. In this paper, we discuss OPERA superluminal neutrinos from experimental discoveries, possible theoretical interpretations, its relationship to the concepts of spacetime, and possible directions for experimental and theoretical researches. Since the understanding of spacetime is extremely important, we expect further experimental evidence to support or falsify OPERA result, and improve our knowledge of spacetime.%物理学对于时间与空间的理解,是推动其发展的重要因素。而现代物理学的根基,则是建立在爱因斯坦的相对论时空观上的。最近,OPERA合作研究组却发现了存在超光速中微子的可能性.倘若其被证实,将是对相对论时空观的一次重大挑战。本文从实验发现,可能的理论解释,人们对于时空观的认识等方面入手,较为客观地讨论了OPERA的实验结果,指出了其可能的实验与理论的研究方向。由于对于时空观的认识是个极其重要的过程,所以我们期待更多的实验来证实或者证伪OPERA超光速中微子的结果,从而推动物理学对于时空观的认识。

  10. The Superluminous Supernova SN 2017egm in the Nearby Galaxy NGC 3191: A Metal-rich Environment Can Support a Typical SLSN Evolution

    Science.gov (United States)

    Nicholl, Matt; Berger, Edo; Margutti, Raffaella; Blanchard, Peter K.; Guillochon, James; Leja, Joel; Chornock, Ryan

    2017-08-01

    At redshift z = 0.03, the recently discovered SN 2017egm is the nearest Type I superluminous supernova (SLSN) to date and first near the center of a massive spiral galaxy (NGC 3191). Using SDSS spectra of NGC 3191, we find a metallicity ˜2 {Z}⊙ at the nucleus and ˜1.3 {Z}⊙ for a star-forming region at a radial offset similar to SN 2017egm. Archival radio-to-UV photometry reveals a star formation rate of ˜15 {M}⊙ yr-1 (with ˜70% dust obscured), which can account for a Swift X-ray detection and a stellar mass of ˜ {10}10.7 {M}⊙ . We model the early UV-optical light curves with a magnetar central-engine model, using the Bayesian light curve fitting tool MOSFiT. The fits indicate an ejecta mass of 2-4 {M}⊙ , a spin period of 4-6 ms, a magnetic field of (0.7{--}1.7)× {10}14 G, and a kinetic energy of 1{--}2× {10}51 erg. These parameters are consistent with the overall distributions for SLSNe, modeled by Nicholl et al., although the derived mass and spin are toward the low end, possibly indicating an enhanced loss of mass and angular momentum before explosion. This has two implications: (i) SLSNe can occur at solar metallicity, although with a low fraction of ˜10%, and (ii) metallicity has at most a modest effect on their properties. Both conclusions are in line with results for long gamma-ray bursts. Assuming a monotonic rise gives an explosion date of MJD 57889 ± 1. However, a short-lived excess in the data relative to the best-fitting models may indicate an early-time “bump.” If confirmed, SN 2017egm would be the first SLSN with a spectrum during the bump phase; this shows the same O ii lines seen at maximum light, which may be an important clue for explaining these bumps.

  11. Pay as You Speed, ISA with incentive for not speeding

    DEFF Research Database (Denmark)

    Lahrmann, Harry; Agerholm, Niels; Tradisauskas, Nerius

    2012-01-01

    To simulate a market introduction of Intelligent Speed Adaptation (ISA) and to study the effect of a Pay as You Speed (PAYS) concept, a field trial with 153 drivers was conducted during 2007–2009. The participants drove under PAYS conditions for a shorter or a longer period. The PAYS concept cons...

  12. A weak balance: the contribution of muscle weakness to postural instability and falls.

    NARCIS (Netherlands)

    Horlings, C.G.; Engelen, B.G.M. van; Allum, J.H.; Bloem, B.R.

    2008-01-01

    Muscle strength is a potentially important factor contributing to postural control. In this article, we consider the influence of muscle weakness on postural instability and falling. We searched the literature for research evaluating muscle weakness as a risk factor for falls in community-dwelling e

  13. What Weak Measurements and Weak Values Really Mean: Reply to Kastner

    Science.gov (United States)

    Cohen, Eliahu

    2017-06-01

    Despite their important applications in metrology and in spite of numerous experimental demonstrations, weak measurements are still confusing for part of the community. This sometimes leads to unjustified criticism. Recent papers have experimentally clarified the meaning and practical significance of weak measurements, yet in Kastner (Found Phys 47:697-707, 2017), Kastner seems to take us many years backwards in the the debate, casting doubt on the very term "weak value" and the meaning of weak measurements. Kastner appears to ignore both the basics and frontiers of weak measurements and misinterprets the weak measurement process and its outcomes. In addition, she accuses the authors of Aharonov et al. (Ann Phys 355:258-268, 2015) in statements completely opposite to the ones they have actually made. There are many points of disagreement between Kastner and us, but in this short reply I will leave aside the ontology (which is indeed interpretational and far more complex than that described by Kastner) and focus mainly on the injustice in her criticism. I shall add some general comments regarding the broader theory of weak measurements and the two-state-vector formalism, as well as supporting experimental results. Finally, I will point out some recent promising results, which can be proven by (strong) projective measurements, without the need of employing weak measurements.

  14. Weak monotonicity inequality and partial regularity for harmonic maps

    Institute of Scientific and Technical Information of China (English)

    沈尧天; 严树森

    1999-01-01

    The notion of locally weak monotonicity inequality for weakly harmonic maps is introduced and various results on this class of maps are obtained. For example, the locally weak monotonicity inequality is nearly equivalent to the ε-regularity.

  15. Higgs Boson Production and Weak Boson Structure

    OpenAIRE

    1995-01-01

    The influence of the QCD structure of the weak bosons on the Higgs boson production in $e$-$p$ scattering is studied. The energy and Higgs boson mass dependence of the cross-section, following from the new contributions, is calculated.

  16. Fermi and the Theory of Weak Interactions

    CERN Document Server

    Rajasekaran, G

    2014-01-01

    The history of weak interactions starting with Fermi's creation of the beta decay theory and culminating in its modern avatar in the form of the electroweak gauge theory is described. Discoveries of parity violation, matter-antimatter asymmetry, W and Z bosons and neutrino mass are highlighted.

  17. Studying dark matter haloes with weak lensing

    NARCIS (Netherlands)

    Velander, Malin Barbro Margareta

    2012-01-01

    Our Universe is comprised not only of normal matter but also of unknown components: dark matter and dark energy. This Thesis recounts studies of dark matter haloes, using a technique known as weak gravitational lensing, in order to learn more about the nature of these dark components. The haloes

  18. Modeling, Measuring, and Compensating Color Weak Vision.

    Science.gov (United States)

    Oshima, Satoshi; Mochizuki, Rika; Lenz, Reiner; Chao, Jinhui

    2016-06-01

    We use methods from Riemann geometry to investigate transformations between the color spaces of color-normal and color-weak observers. The two main applications are the simulation of the perception of a color weak observer for a color-normal observer, and the compensation of color images in a way that a color-weak observer has approximately the same perception as a color-normal observer. The metrics in the color spaces of interest are characterized with the help of ellipsoids defined by the just-noticeable-differences between the colors which are measured with the help of color-matching experiments. The constructed mappings are the isometries of Riemann spaces that preserve the perceived color differences for both observers. Among the two approaches to build such an isometry, we introduce normal coordinates in Riemann spaces as a tool to construct a global color-weak compensation map. Compared with the previously used methods, this method is free from approximation errors due to local linearizations, and it avoids the problem of shifting locations of the origin of the local coordinate system. We analyze the variations of the Riemann metrics for different observers obtained from new color-matching experiments and describe three variations of the basic method. The performance of the methods is evaluated with the help of semantic differential tests.

  19. Modelling, Measuring and Compensating Color Weak Vision.

    Science.gov (United States)

    Oshima, Satoshi; Mochizuki, Rika; Lenz, Reiner; Chao, Jinhui

    2016-03-08

    We use methods from Riemann geometry to investigate transformations between the color spaces of color-normal and color weak observers. The two main applications are the simulation of the perception of a color weak observer for a color normal observer and the compensation of color images in a way that a color weak observer has approximately the same perception as a color normal observer. The metrics in the color spaces of interest are characterized with the help of ellipsoids defined by the just-noticable-differences between color which are measured with the help of color-matching experiments. The constructed mappings are isometries of Riemann spaces that preserve the perceived color-differences for both observers. Among the two approaches to build such an isometry, we introduce normal coordinates in Riemann spaces as a tool to construct a global color-weak compensation map. Compared to previously used methods this method is free from approximation errors due to local linearizations and it avoids the problem of shifting locations of the origin of the local coordinate system. We analyse the variations of the Riemann metrics for different observers obtained from new color matching experiments and describe three variations of the basic method. The performance of the methods is evaluated with the help of semantic differential (SD) tests.

  20. TRANSPORTATION INEQUALITIES FOR WEAKLY DEPENDENT SEQUENCES

    Institute of Scientific and Technical Information of China (English)

    Ma Yutao

    2011-01-01

    In[3],they gave necessary and sufficient condition for T1C and then as applications T1C for weakly dependent sequences was established.In this note,based on Gozlan-Léonard characterization for W1H-inequalities,we extends this result to W1Hinequalities.