WorldWideScience

Sample records for gravitationally induced processes

  1. Extracting gravitational waves induced by plasma turbulence in the early Universe through an averaging process

    International Nuclear Information System (INIS)

    Garrison, David; Ramirez, Christopher

    2017-01-01

    This work is a follow-up to the paper, ‘Numerical relativity as a tool for studying the early Universe’. In this article, we determine if cosmological gravitational waves can be accurately extracted from a dynamical spacetime using an averaging process as opposed to conventional methods of gravitational wave extraction using a complex Weyl scalar. We calculate the normalized energy density, strain and degree of polarization of gravitational waves produced by a simulated turbulent plasma similar to what was believed to have existed shortly after the electroweak scale. This calculation is completed using two numerical codes, one which utilizes full general relativity calculations based on modified BSSN equations while the other utilizes a linearized approximation of general relativity. Our results show that the spectrum of gravitational waves calculated from the nonlinear code using an averaging process is nearly indistinguishable from those calculated from the linear code. This result validates the use of the averaging process for gravitational wave extraction of cosmological systems. (paper)

  2. On the Induced Gravitational Collapse

    Directory of Open Access Journals (Sweden)

    M. Becerra Laura

    2018-01-01

    Full Text Available The induced gravitational collapse (IGC paradigm has been applied to explain the long gamma ray burst (GRB associated with type Ic supernova, and recently the Xray flashes (XRFs. The progenitor is a binary systems of a carbon-oxygen core (CO and a neutron star (NS. The CO core collapses and undergoes a supernova explosion which triggers the hypercritical accretion onto the NS companion (up to 10-2 M⊙s-1. For the binary driven hypernova (BdHNe, the binary system is enough bound, the NS reach its critical mass, and collapse to a black hole (BH with a GRB emission characterized by an isotropic energy Eiso > 1052 erg. Otherwise, for binary systems with larger binary separations, the hypercritical accretion onto the NS is not sufficient to induced its gravitational collapse, a X-ray flash is produced with Eiso < 1052 erg. We’re going to focus in identify the binary parameters that limits the BdHNe systems with the XRFs systems.

  3. Radiatively-induced gravitational leptogenesis

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, J.I., E-mail: pymcdonald@swansea.ac.uk; Shore, G.M., E-mail: g.m.shore@swansea.ac.uk

    2015-12-17

    We demonstrate how loop effects in gravitational backgrounds lead to a difference in the propagation of matter and antimatter, and show this is forbidden in flat space due to CPT and translation invariance. This mechanism, which is naturally present in beyond the standard model (BSM) theories exhibiting C and CP violation, generates a curvature-dependent chemical potential for leptons in the low-energy effective Lagrangian, allowing a matter–antimatter asymmetry to be generated in thermodynamic equilibrium, below the BSM scale.

  4. Radiatively-induced gravitational leptogenesis

    Directory of Open Access Journals (Sweden)

    J.I. McDonald

    2015-12-01

    Full Text Available We demonstrate how loop effects in gravitational backgrounds lead to a difference in the propagation of matter and antimatter, and show this is forbidden in flat space due to CPT and translation invariance. This mechanism, which is naturally present in beyond the standard model (BSM theories exhibiting C and CP violation, generates a curvature-dependent chemical potential for leptons in the low-energy effective Lagrangian, allowing a matter–antimatter asymmetry to be generated in thermodynamic equilibrium, below the BSM scale.

  5. Induced forces in the gravitational field

    International Nuclear Information System (INIS)

    Voracek, P.

    1979-01-01

    In this paper the expression for the magnitude of the so-called induced force, acting on a mass particle, is deduced. The origin of this force is causally connected to the increase of the rest mass of the particle in the gravitational field. (orig.)

  6. Optical-Gravitation Nonlinearity: A Change of Gravitational Coefficient G induced by Gravitation Field

    OpenAIRE

    R. Vlokh; M. Kostyrko

    2006-01-01

    Nonlinear effect of the gravitation field of spherically symmetric mass on the gravitational coefficient G has been analysed. In frame of the approaches of parametric optics and gravitation nonlinearity we have shown that the gravitation field of spherically symmetric mass can lead to changes in the gravitational coefficient G.

  7. Gravitationally self-induced phase transition

    International Nuclear Information System (INIS)

    Novello, M.; Duque, S.L.S.

    1990-01-01

    We propose a new mechanism by means of which a phase transition can be stimulated by self-gravitating matter. We suggest that this model could be used to explain the observed isotropy of the Universe. (orig.)

  8. HYPERCRITICAL ACCRETION, INDUCED GRAVITATIONAL COLLAPSE, AND BINARY-DRIVEN HYPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Fryer, Chris L. [CCS-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Rueda, Jorge A.; Ruffini, Remo [ICRANet, Piazza della Repubblica 10, I-65122 Pescara (Italy)

    2014-10-01

    The induced gravitational collapse (IGC) paradigm has been successfully applied to the explanation of the concomitance of gamma-ray bursts (GRBs) with supernovae (SNe) Ic. The progenitor is a tight binary system composed of a carbon-oxygen (CO) core and a neutron star (NS) companion. The explosion of the SN leads to hypercritical accretion onto the NS companion, which reaches the critical mass, hence inducing its gravitational collapse to a black hole (BH) with consequent emission of the GRB. The first estimates of this process were based on a simplified model of the binary parameters and the Bondi-Hoyle-Lyttleton accretion rate. We present here the first full numerical simulations of the IGC phenomenon. We simulate the core-collapse and SN explosion of CO stars to obtain the density and ejection velocity of the SN ejecta. We follow the hydrodynamic evolution of the accreting material falling into the Bondi-Hoyle surface of the NS all the way up to its incorporation in the NS surface. The simulations go up to BH formation when the NS reaches the critical mass. For appropriate binary parameters, the IGC occurs in short timescales ∼10{sup 2}-10{sup 3} s owing to the combined effective action of the photon trapping and the neutrino cooling near the NS surface. We also show that the IGC scenario leads to a natural explanation for why GRBs are associated only with SNe Ic with totally absent or very little helium.

  9. Gravitationally induced neutrino oscillation phases in static spacetimes

    International Nuclear Information System (INIS)

    Bhattacharya, T.; Habib, S.; Mottola, E.

    1999-01-01

    We critically examine the recent claim of a 'new effect' of gravitationally induced quantum mechanical phases in neutrino oscillations. Because this claim has generated some discussion in the literature we present here a straightforward calculation of the phase and clarify some of the conceptual issues involved, particularly in relation to the equivalence principle. When expressed in terms of the asymptotic energy of the neutrinos E and Schwarzschild radial coordinates r, the lowest order at which such a gravitational effect appears is (GMΔm 4 /ℎE 3 )ln(r B /r A ). copyright 1999 The American Physical Society

  10. Gravitational Zero Point Energy induces Physical Observables

    OpenAIRE

    Garattini, Remo

    2010-01-01

    We consider the contribution of Zero Point Energy on the induced Cosmological Constant and on the induced Electric/Magnetic charge in absence of matter fields. The method is applicable to every spherically symmetric background. Extensions to a generic $f(R) $ theory are also allowed. Only the graviton appears to be fundamental to the determination of Zero Point Energy.

  11. High-Frequency Gravitational Wave Induced Nuclear Fusion

    International Nuclear Information System (INIS)

    Fontana, Giorgio; Baker, Robert M. L. Jr.

    2007-01-01

    Nuclear fusion is a process in which nuclei, having a total initial mass, combine to produce a single nucleus, having a final mass less than the total initial mass. Below a given atomic number the process is exothermic; that is, since the final mass is less than the combined initial mass and the mass deficit is converted into energy by the nuclear fusion. On Earth nuclear fusion does not happen spontaneously because electrostatic barriers prevent the phenomenon. To induce controlled, industrial scale, nuclear fusion, only a few methods have been discovered that look promising, but net positive energy production is not yet possible because of low overall efficiency of the systems. In this paper we propose that an intense burst of High Frequency Gravitational Waves (HFGWs) could be focused or beamed to a target mass composed of appropriate fuel or target material to efficiently rearrange the atomic or nuclear structure of the target material with consequent nuclear fusion. Provided that efficient generation of HFGW can be technically achieved, the proposed fusion reactor could become a viable solution for the energy needs of mankind and alternatively a process for beaming energy to produce a source of fusion energy remotely - even inside solid materials

  12. Gravitation

    CERN Document Server

    Misner, Charles W; Wheeler, John Archibald

    2017-01-01

    First published in 1973, Gravitation is a landmark graduate-level textbook that presents Einstein’s general theory of relativity and offers a rigorous, full-year course on the physics of gravitation. Upon publication, Science called it “a pedagogic masterpiece,” and it has since become a classic, considered essential reading for every serious student and researcher in the field of relativity. This authoritative text has shaped the research of generations of physicists and astronomers, and the book continues to influence the way experts think about the subject. With an emphasis on geometric interpretation, this masterful and comprehensive book introduces the theory of relativity; describes physical applications, from stars to black holes and gravitational waves; and portrays the field’s frontiers. The book also offers a unique, alternating, two-track pathway through the subject. Material focusing on basic physical ideas is designated as Track 1 and formulates an appropriate one-semester graduate-level...

  13. Gravitation

    International Nuclear Information System (INIS)

    Fennelly, A.J.

    1978-01-01

    Investigations of several problems of gravitation are discussed. The question of the existence of black holes is considered. While black holes like those in Einstein's theory may not exist in other gravity theories, trapped surfaces implying such black holes certainly do. The theories include those of Brans-Dicke, Lightman-Lee, Rosen, and Yang. A similar two-tensor theory of Yilmaz is investigated and found inconsistent and nonviable. The Newman-Penrose formalism for Riemannian geometries is adapted to general gravity theories and used to implement a search for twisting solutions of the gravity theories for empty and nonempty spaces. The method can be used to find the gravitational fields for all viable gravity theories. The rotating solutions are of particular importance for strong field interpretation of the Stanford/Marshall gyroscope experiment. Inhomogeneous cosmologies are examined in Einstein's theory as generalizations of homogeneous ones by raising the dimension of the invariance groups by one more parameter. The nine Bianchi classifications are extended to Rosen's theory of gravity for homogeneous cosmological models

  14. The Hall-induced stability of gravitating fluids

    Science.gov (United States)

    Karmakar, P. K.; Goutam, H. P.

    2018-05-01

    We analyze the stability behavior of low-density partially ionized self-gravitating magnetized unbounded dusty plasma fluid in the presence of the Hall diffusion effects (HDEs) in the non-ideal magnetohydrodynamic (MHD) equilibrium framework. The effects of inhomogeneous self-gravity are methodically included in the basic model tapestry. Application of the Fourier plane-wave perturbative treatment decouples the structuration representative parameters into a linear generalized dispersion relation (sextic) in a judicious mean-fluid approximation. The dispersion analysis shows that the normal mode, termed as the gravito-magneto-acoustic (GMA) mode, is drastically modified due to the HDEs. This mode is highly dispersive, and driven unstable by the Hall current resulting from the symmetry-breaking of electrons and ions relative to the magnetic field. The mode feature, which is derived from a modified induction with the positive Hall, is against the ideal MHD. It is further demonstrated that the HDEs play stabilizing roles by supporting the cloud against gravitational collapse. Provided that the HDEs are concurrently switched off, the collapse occurs on the global spatial scale due to enhanced inward accretion of the gravitating dust constituents. It is seen explicitly that the enhanced dust-charge leads to stabilizing effects. Besides, the Hall-induced fluctuations, as propagatory wave modes, exhibit both normal and anomalous dispersions. The reliability checkup of the entailed results as diverse corollaries and special cases are illustratively discussed in the panoptic light of the earlier paradigmatic predictions available in the literature.

  15. Thermodynamics of gravitationally induced particle creation scenario in DGP braneworld

    Energy Technology Data Exchange (ETDEWEB)

    Jawad, Abdul; Rani, Shamaila; Rafique, Salman [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan)

    2018-01-15

    In this paper, we discuss the thermodynamical analysis for gravitationally induced particle creation scenario in the framework of DGP braneworld model. For this purpose, we consider apparent horizon as the boundary of the universe. We take three types of entropy such as Bakenstein entropy, logarithmic corrected entropy and power law corrected entropy with ordinary creation rate Γ. We analyze the first law and generalized second law of thermodynamics analytically for these entropies which hold under some constraints. The behavior of total entropy in each case is also discussed which implies the validity of generalized second law of thermodynamics. Also, we check the thermodynamical equilibrium condition for two phases of creation rate, that is constant and variable Γ and found its vitality in all cases of entropy. (orig.)

  16. Thermodynamics of gravitationally induced particle creation scenario in DGP braneworld

    International Nuclear Information System (INIS)

    Jawad, Abdul; Rani, Shamaila; Rafique, Salman

    2018-01-01

    In this paper, we discuss the thermodynamical analysis for gravitationally induced particle creation scenario in the framework of DGP braneworld model. For this purpose, we consider apparent horizon as the boundary of the universe. We take three types of entropy such as Bakenstein entropy, logarithmic corrected entropy and power law corrected entropy with ordinary creation rate Γ. We analyze the first law and generalized second law of thermodynamics analytically for these entropies which hold under some constraints. The behavior of total entropy in each case is also discussed which implies the validity of generalized second law of thermodynamics. Also, we check the thermodynamical equilibrium condition for two phases of creation rate, that is constant and variable Γ and found its vitality in all cases of entropy. (orig.)

  17. Thermodynamic implications of the gravitationally induced particle creation scenario

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Subhajit [Indian Institute of Science Education and Research Kolkata, Department of Physical Sciences, Mohanpur, West Bengal (India); Mondal, Anindita [S N Bose National Centre for Basic Sciences, Department of Astrophysics and Cosmology, Kolkata, West Bengal (India)

    2017-03-15

    A rigorous thermodynamic analysis has been done as regards the apparent horizon of a spatially flat Friedmann-Lemaitre-Robertson-Walker universe for the gravitationally induced particle creation scenario with constant specific entropy and an arbitrary particle creation rate Γ. Assuming a perfect fluid equation of state p = (γ - 1)ρ with (2)/(3) ≤ γ ≤ 2, the first law, the generalized second law (GSL), and thermodynamic equilibrium have been studied, and an expression for the total entropy (i.e., horizon entropy plus fluid entropy) has been obtained which does not contain Γ explicitly. Moreover, a lower bound for the fluid temperature T{sub f} has also been found which is given by T{sub f} ≥ 8 (((3γ)/(2)-1)/((2)/(γ)-1)) H{sup 2}. It has been shown that the GSL is satisfied for (Γ)/(3H) ≤ 1. Further, when Γ is constant, thermodynamic equilibrium is always possible for (1)/(2) < (Γ)/(3H) < 1, while for (Γ)/(3H) ≤ min {(1)/(2), (2γ-2)/(3γ-2)} and (Γ)/(3H) ≥ 1, equilibrium can never be attained. Thermodynamic arguments also lead us to believe that during the radiation phase, Γ ≤ H. When Γ is not a constant, thermodynamic equilibrium holds if H ≥ (27)/(4) γ{sup 2}H{sup 3} (1-(Γ)/(3H)){sup 2}, however, such a condition is by no means necessary for the attainment of equilibrium. (orig.)

  18. Thermodynamic implications of the gravitationally induced particle creation scenario

    International Nuclear Information System (INIS)

    Saha, Subhajit; Mondal, Anindita

    2017-01-01

    A rigorous thermodynamic analysis has been done as regards the apparent horizon of a spatially flat Friedmann-Lemaitre-Robertson-Walker universe for the gravitationally induced particle creation scenario with constant specific entropy and an arbitrary particle creation rate Γ. Assuming a perfect fluid equation of state p = (γ - 1)ρ with (2)/(3) ≤ γ ≤ 2, the first law, the generalized second law (GSL), and thermodynamic equilibrium have been studied, and an expression for the total entropy (i.e., horizon entropy plus fluid entropy) has been obtained which does not contain Γ explicitly. Moreover, a lower bound for the fluid temperature T f has also been found which is given by T f ≥ 8 (((3γ)/(2)-1)/((2)/(γ)-1)) H 2 . It has been shown that the GSL is satisfied for (Γ)/(3H) ≤ 1. Further, when Γ is constant, thermodynamic equilibrium is always possible for (1)/(2) < (Γ)/(3H) < 1, while for (Γ)/(3H) ≤ min {(1)/(2), (2γ-2)/(3γ-2)} and (Γ)/(3H) ≥ 1, equilibrium can never be attained. Thermodynamic arguments also lead us to believe that during the radiation phase, Γ ≤ H. When Γ is not a constant, thermodynamic equilibrium holds if H ≥ (27)/(4) γ 2 H 3 (1-(Γ)/(3H)) 2 , however, such a condition is by no means necessary for the attainment of equilibrium. (orig.)

  19. Scalar field vacuum expectation value induced by gravitational wave background

    Science.gov (United States)

    Jones, Preston; McDougall, Patrick; Ragsdale, Michael; Singleton, Douglas

    2018-06-01

    We show that a massless scalar field in a gravitational wave background can develop a non-zero vacuum expectation value. We draw comparisons to the generation of a non-zero vacuum expectation value for a scalar field in the Higgs mechanism and with the dynamical Casimir vacuum. We propose that this vacuum expectation value, generated by a gravitational wave, can be connected with particle production from gravitational waves and may have consequences for the early Universe where scalar fields are thought to play an important role.

  20. Backwards time travel induced by combined magnetic and gravitational fields

    International Nuclear Information System (INIS)

    Novello, M.; Svaiter, N.F.; Guimaraes, M.E.X.

    1990-01-01

    We analyse the behaviour of an elementary microscopic particle submitted to combined Magnetic and Gravitational Fields on Goedel's Universe. The exam is made in a local Gaussian system of coordinates. (author)

  1. Erratum: Erratum to: Thermodynamic implications of the gravitationally induced particle creation scenario

    Science.gov (United States)

    Saha, Subhajit; Mondal, Anindita

    2018-04-01

    We would like to rectify an error regarding the validity of the first law of thermodynamics (FLT) on the apparent horizon of a spatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) universe for the gravitationally induced particle creation scenario with constant specific entropy and an arbitrary particle creation rate (see Sect. 3.1 of original article)

  2. How to detect the gravitationally induced phase shift of electromagnetic waves by optical-fiber interferometry

    International Nuclear Information System (INIS)

    Tanaka, K.

    1983-01-01

    Attention is called to a laboratory experiment of an optical-fiber interferometer which can show the gravitationally induced phase shift of optical waves. A phase shift of approx.10 -6 rad is anticipated for the Earth's gravitational potential difference of 1 m when a He-Ne laser and two multiple-turn optical-fiber loops of length 5 km are used. The phase shift can be varied by rotating the loops about an axis parallel to the Earth's surface. This order of phase shifts can be detected by current optical-fiber interferometric techniques

  3. Gravitational Field effects on the Decoherence Process and the Quantum Speed Limit.

    Science.gov (United States)

    Dehdashti, Sh; Avazzadeh, Z; Xu, Z; Shen, J Q; Mirza, B; Wang, H

    2017-11-08

    In this paper we use spinor transformations under local Lorentz transformations to investigate the curvature effect on the quantum-to-classical transition, described in terms of the decoherence process and of the quantum speed limit. We find that gravitational fields (introduced adopting the Schwarzschild and anti-de Sitter geometries) affect both the decoherence process and the quantum speed limit of a quantum particle with spin-1/2. In addition, as a tangible example, we study the effect of the Earth's gravitational field, characterized by the Rindler space-time, on the same particle. We find that the effect of the Earth's gravitational field on the decoherence process and quantum speed limit is very small, except when the mean speed of the quantum particle is comparable to the speed of light.

  4. Neutrino Oscillations within the Induced Gravitational Collapse Paradigm of Long Gamma-Ray Bursts

    Science.gov (United States)

    Becerra, L.; Guzzo, M. M.; Rossi-Torres, F.; Rueda, J. A.; Ruffini, R.; Uribe, J. D.

    2018-01-01

    The induced gravitational collapse paradigm of long gamma-ray bursts associated with supernovae (SNe) predicts a copious neutrino–antineutrino (ν \\bar{ν }) emission owing to the hypercritical accretion process of SN ejecta onto a neutron star (NS) binary companion. The neutrino emission can reach luminosities of up to 1057 MeV s‑1, mean neutrino energies of 20 MeV, and neutrino densities of 1031 cm‑3. Along their path from the vicinity of the NS surface outward, such neutrinos experience flavor transformations dictated by the neutrino-to-electron-density ratio. We determine the neutrino and electron on the accretion zone and use them to compute the neutrino flavor evolution. For normal and inverted neutrino mass hierarchies and within the two-flavor formalism ({ν }e{ν }x), we estimate the final electronic and nonelectronic neutrino content after two oscillation processes: (1) neutrino collective effects due to neutrino self-interactions where the neutrino density dominates, and (2) the Mikheyev–Smirnov–Wolfenstein effect, where the electron density dominates. We find that the final neutrino content is composed by ∼55% (∼62%) of electronic neutrinos, i.e., {ν }e+{\\bar{ν }}e, for the normal (inverted) neutrino mass hierarchy. The results of this work are the first step toward the characterization of a novel source of astrophysical MeV neutrinos in addition to core-collapse SNe and, as such, deserve further attention.

  5. Gravitationally induced particle production and its impact on the WIMP abundance

    Directory of Open Access Journals (Sweden)

    I. Baranov

    2015-12-01

    Full Text Available A large set of independent astronomical observations have provided a strong evidence for nonbaryonic dark matter in the Universe. One of the most investigated candidates is an unknown long-lived Weakly Interacting Massive Particle (WIMP which was in thermal equilibrium with the primeval plasma. Here we investigate the WIMP abundance based on the relativistic kinetic treatment for gravitationally induced particle production recently proposed in the literature (Lima and Baranov, 2014 [16]. The new evolution equation is deduced and solved both numerically and through a semi-analytical approach. The predictions of the WIMP observables are discussed and compared with the ones obtained in the standard approach.

  6. Gravitationally induced adiabatic particle production: from big bang to de Sitter

    Science.gov (United States)

    de Haro, Jaume; Pan, Supriya

    2016-08-01

    In the background of a flat homogeneous and isotropic space-time, we consider a scenario of the Universe driven by the gravitationally induced ‘adiabatic’ particle production with constant creation rate. We have shown that this Universe attains a big bang singularity in the past and at late-time it asymptotically becomes de Sitter. To clarify this model Universe, we performed a dynamical analysis and found that the Universe attains a thermodynamic equilibrium in this late de Sitter phase. Finally, for the first time, we have discussed the possible effects of ‘adiabatic’ particle creations in the context of loop quantum cosmology.

  7. Gravitationally induced adiabatic particle production: from big bang to de Sitter

    International Nuclear Information System (INIS)

    Haro, Jaume de; Pan, Supriya

    2016-01-01

    In the background of a flat homogeneous and isotropic space–time, we consider a scenario of the Universe driven by the gravitationally induced ‘adiabatic’ particle production with constant creation rate. We have shown that this Universe attains a big bang singularity in the past and at late-time it asymptotically becomes de Sitter. To clarify this model Universe, we performed a dynamical analysis and found that the Universe attains a thermodynamic equilibrium in this late de Sitter phase. Finally, for the first time, we have discussed the possible effects of ‘adiabatic’ particle creations in the context of loop quantum cosmology. (paper)

  8. Systemic determinants of modern gravitational processes in the geo-economic space

    Directory of Open Access Journals (Sweden)

    Zoryana Lutsyshyn

    2015-12-01

    Full Text Available From the compositional point of view, research on this topic has revealed two main directions: (1 an analysis of global development asymmetry that has activated gravitational processes in geo-economic space; and (2 a direction that focuses on the profound study of the causes for heterogeneity in geo-economic space and divergence in global development under the influence of gravitational factors of nature on the endogenousexogenous axis. Systemic determinants of gravitational processes are revealed in geo- economic space and the asymmetry of global activate ravitional processes in geo-economic space are observed, and methodological interconnectedness coinfluence of two complementary determinants of global development – convergence and divergence and the contradiction between them are examined, which at the same time underlie the inevitable internal contradictions of the process, creating conditions for further configuration of the «new globalization community», which is built on the principles of nonlinear dynamics and logic gravitational processes in geo-economic space.Taking into account the relevant uncertainties, the attention is focused on the isolation of several myths around which the debate that has important methodological significance in the context of the current global inter-system transformations is held. Geostrategic matrix divergence of global development is produced,which is based on techniques which incorporated cluster analysisthat are built on linguistic variables and integrated analysis of the key trends of country and global development geostrategic position of Ukraine in geo-economic space in the projection on the issues of global inter-system transformations isoutlined .It is proved that the level of gravity load increases in the deepening of the global asymmetries , and that the current global transformation is not yet complete, and polycentric new architecture geospace is not formed. In the near future we should

  9. Gravitational waves from gravitational collapse

    Energy Technology Data Exchange (ETDEWEB)

    Fryer, Christopher L [Los Alamos National Laboratory; New, Kimberly C [Los Alamos National Laboratory

    2008-01-01

    Gravitational wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.

  10. Gravitational Waves from Gravitational Collapse

    Directory of Open Access Journals (Sweden)

    Chris L. Fryer

    2011-01-01

    Full Text Available Gravitational-wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion-induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.

  11. Gravitational Waves from Gravitational Collapse.

    Science.gov (United States)

    Fryer, Chris L; New, Kimberly C B

    2011-01-01

    Gravitational-wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion-induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars. Supplementary material is available for this article at 10.12942/lrr-2011-1.

  12. Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy.

    Science.gov (United States)

    Afach, S; Ayres, N J; Ban, G; Bison, G; Bodek, K; Chowdhuri, Z; Daum, M; Fertl, M; Franke, B; Griffith, W C; Grujić, Z D; Harris, P G; Heil, W; Hélaine, V; Kasprzak, M; Kermaidic, Y; Kirch, K; Knowles, P; Koch, H-C; Komposch, S; Kozela, A; Krempel, J; Lauss, B; Lefort, T; Lemière, Y; Mtchedlishvili, A; Musgrave, M; Naviliat-Cuncic, O; Pendlebury, J M; Piegsa, F M; Pignol, G; Plonka-Spehr, C; Prashanth, P N; Quéméner, G; Rawlik, M; Rebreyend, D; Ries, D; Roccia, S; Rozpedzik, D; Schmidt-Wellenburg, P; Severijns, N; Thorne, J A; Weis, A; Wursten, E; Wyszynski, G; Zejma, J; Zenner, J; Zsigmond, G

    2015-10-16

    We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a |B0|=1  μT magnetic field. We have demonstrated that the analysis of UCN spin-echo resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons. The method takes advantage of the relative dephasing of spins arising from a gravitationally induced striation of stored UCNs of different energies, and also permits an improved determination of the vertical magnetic-field gradient with an exceptional accuracy of 1.1  pT/cm. This novel combination of a well-known nuclear resonance method and gravitationally induced vertical striation is unique in the realm of nuclear and particle physics and should prove to be invaluable for the assessment of systematic effects in precision experiments such as searches for an electric dipole moment of the neutron or the measurement of the neutron lifetime.

  13. Gravitational decoherence

    International Nuclear Information System (INIS)

    Bassi, Angelo; Großardt, André; Ulbricht, Hendrik

    2017-01-01

    We discuss effects of loss of coherence in low energy quantum systems caused by or related to gravitation, referred to as gravitational decoherence. These effects, resulting from random metric fluctuations, for instance, promise to be accessible by relatively inexpensive table-top experiments, way before the scales where true quantum gravity effects become important. Therefore, they can provide a first experimental view on gravity in the quantum regime. We will survey models of decoherence induced both by classical and quantum gravitational fluctuations; it will be manifest that a clear understanding of gravitational decoherence is still lacking. Next we will review models where quantum theory is modified, under the assumption that gravity causes the collapse of the wave functions, when systems are large enough. These models challenge the quantum-gravity interplay, and can be tested experimentally. In the last part we have a look at the state of the art of experimental research. We will review efforts aiming at more and more accurate measurements of gravity ( G and g ) and ideas for measuring conventional and unconventional gravity effects on nonrelativistic quantum systems. (topical review)

  14. Parametric optimization of ultrasonic machining process using gravitational search and fireworks algorithms

    Directory of Open Access Journals (Sweden)

    Debkalpa Goswami

    2015-03-01

    Full Text Available Ultrasonic machining (USM is a mechanical material removal process used to erode holes and cavities in hard or brittle workpieces by using shaped tools, high-frequency mechanical motion and an abrasive slurry. Unlike other non-traditional machining processes, such as laser beam and electrical discharge machining, USM process does not thermally damage the workpiece or introduce significant levels of residual stress, which is important for survival of materials in service. For having enhanced machining performance and better machined job characteristics, it is often required to determine the optimal control parameter settings of an USM process. The earlier mathematical approaches for parametric optimization of USM processes have mostly yielded near optimal or sub-optimal solutions. In this paper, two almost unexplored non-conventional optimization techniques, i.e. gravitational search algorithm (GSA and fireworks algorithm (FWA are applied for parametric optimization of USM processes. The optimization performance of these two algorithms is compared with that of other popular population-based algorithms, and the effects of their algorithm parameters on the derived optimal solutions and computational speed are also investigated. It is observed that FWA provides the best optimal results for the considered USM processes.

  15. A Fast MHD Code for Gravitationally Stratified Media using Graphical Processing Units: SMAUG

    Science.gov (United States)

    Griffiths, M. K.; Fedun, V.; Erdélyi, R.

    2015-03-01

    Parallelization techniques have been exploited most successfully by the gaming/graphics industry with the adoption of graphical processing units (GPUs), possessing hundreds of processor cores. The opportunity has been recognized by the computational sciences and engineering communities, who have recently harnessed successfully the numerical performance of GPUs. For example, parallel magnetohydrodynamic (MHD) algorithms are important for numerical modelling of highly inhomogeneous solar, astrophysical and geophysical plasmas. Here, we describe the implementation of SMAUG, the Sheffield Magnetohydrodynamics Algorithm Using GPUs. SMAUG is a 1-3D MHD code capable of modelling magnetized and gravitationally stratified plasma. The objective of this paper is to present the numerical methods and techniques used for porting the code to this novel and highly parallel compute architecture. The methods employed are justified by the performance benchmarks and validation results demonstrating that the code successfully simulates the physics for a range of test scenarios including a full 3D realistic model of wave propagation in the solar atmosphere.

  16. Primordial gravitational waves induced by magnetic fields in an ekpyrotic scenario

    Directory of Open Access Journals (Sweden)

    Asuka Ito

    2017-08-01

    Full Text Available Both inflationary and ekpyrotic scenarios can account for the origin of the large scale structure of the universe. It is often said that detecting primordial gravitational waves is the key to distinguish both scenarios. We show that this is not true if the gauge kinetic function is present in the ekpyrotic scenario. In fact, primordial gravitational waves sourced by the gauge field can be produced in an ekpyrotic universe. We also study scalar fluctuations sourced by the gauge field and show that it is negligible compared to primordial gravitational waves. This comes from the fact that the fast roll condition holds in ekpyrotic models.

  17. Higher-order geodesic deviation for charged particles and resonance induced by gravitational waves

    Science.gov (United States)

    Heydari-Fard, M.; Hasani, S. N.

    We generalize the higher-order geodesic deviation for the structure-less test particles to the higher-order geodesic deviation equations of the charged particles [R. Kerner, J. W. van Holten and R. Colistete Jr., Class. Quantum Grav. 18 (2001) 4725]. By solving these equations for charged particles moving in a constant magnetic field in the spacetime of a gravitational wave, we show for both cases when the gravitational wave is parallel and perpendicular to the constant magnetic field, a magnetic resonance appears at wg = Ω. This feature might be useful to detect the gravitational wave with high frequencies.

  18. Optimization of Nano-Process Deposition Parameters Based on Gravitational Search Algorithm

    Directory of Open Access Journals (Sweden)

    Norlina Mohd Sabri

    2016-06-01

    Full Text Available This research is focusing on the radio frequency (RF magnetron sputtering process, a physical vapor deposition technique which is widely used in thin film production. This process requires the optimized combination of deposition parameters in order to obtain the desirable thin film. The conventional method in the optimization of the deposition parameters had been reported to be costly and time consuming due to its trial and error nature. Thus, gravitational search algorithm (GSA technique had been proposed to solve this nano-process parameters optimization problem. In this research, the optimized parameter combination was expected to produce the desirable electrical and optical properties of the thin film. The performance of GSA in this research was compared with that of Particle Swarm Optimization (PSO, Genetic Algorithm (GA, Artificial Immune System (AIS and Ant Colony Optimization (ACO. Based on the overall results, the GSA optimized parameter combination had generated the best electrical and an acceptable optical properties of thin film compared to the others. This computational experiment is expected to overcome the problem of having to conduct repetitive laboratory experiments in obtaining the most optimized parameter combination. Based on this initial experiment, the adaptation of GSA into this problem could offer a more efficient and productive way of depositing quality thin film in the fabrication process.

  19. Evolution of an electron-positron plasma produced by induced gravitational collapse in binary-driven hypernovae

    Directory of Open Access Journals (Sweden)

    Melon Fuksman J. D.

    2018-01-01

    Full Text Available The binary-driven hypernova (BdHN model has been introduced in the past years, to explain a subfamily of gamma-ray bursts (GRBs with energies Eiso ≥ 1052 erg associated with type Ic supernovae. Such BdHNe have as progenitor a tight binary system composed of a carbon-oxigen (CO core and a neutron star undergoing an induced gravitational collapse to a black hole, triggered by the CO core explosion as a supernova (SN. This collapse produces an optically-thick e+e- plasma, which expands and impacts onto the SN ejecta. This process is here considered as a candidate for the production of X-ray flares, which are frequently observed following the prompt emission of GRBs. In this work we follow the evolution of the e+e- plasma as it interacts with the SN ejecta, by solving the equations of relativistic hydrodynamics numerically. Our results are compatible with the Lorentz factors estimated for the sources that produce the flares, of typically Γ ≲ 4.

  20. High performance direct gravitational N-body simulations on graphics processing units II: An implementation in CUDA

    NARCIS (Netherlands)

    Belleman, R.G.; Bédorf, J.; Portegies Zwart, S.F.

    2008-01-01

    We present the results of gravitational direct N-body simulations using the graphics processing unit (GPU) on a commercial NVIDIA GeForce 8800GTX designed for gaming computers. The force evaluation of the N-body problem is implemented in "Compute Unified Device Architecture" (CUDA) using the GPU to

  1. Gravitationally Induced Entanglement between Two Massive Particles is Sufficient Evidence of Quantum Effects in Gravity.

    Science.gov (United States)

    Marletto, C; Vedral, V

    2017-12-15

    All existing quantum-gravity proposals are extremely hard to test in practice. Quantum effects in the gravitational field are exceptionally small, unlike those in the electromagnetic field. The fundamental reason is that the gravitational coupling constant is about 43 orders of magnitude smaller than the fine structure constant, which governs light-matter interactions. For example, detecting gravitons-the hypothetical quanta of the gravitational field predicted by certain quantum-gravity proposals-is deemed to be practically impossible. Here we adopt a radically different, quantum-information-theoretic approach to testing quantum gravity. We propose witnessing quantumlike features in the gravitational field, by probing it with two masses each in a superposition of two locations. First, we prove that any system (e.g., a field) mediating entanglement between two quantum systems must be quantum. This argument is general and does not rely on any specific dynamics. Then, we propose an experiment to detect the entanglement generated between two masses via gravitational interaction. By our argument, the degree of entanglement between the masses is a witness of the field quantization. This experiment does not require any quantum control over gravity. It is also closer to realization than detecting gravitons or detecting quantum gravitational vacuum fluctuations.

  2. Supernovae theory: study of electro-weak processes during gravitational collapse of massive stars

    International Nuclear Information System (INIS)

    Fantina, A.F.

    2010-01-01

    The physics of supernova requires the understanding of both the complex hydrodynamical phenomena (such as transfer of energy, neutrino transport, shock) as well as the microphysics related to the dense and hot matter. In the framework of type II Supernovae theory, currently most of numerical simulations that simulate the supernova core collapse up to the formation and propagation of the shock wave fail to reproduce the observed explosion of the outer layers of massive stars. The reason for that could be due both to hydrodynamical phenomena such as rotation, convection, and general relativity, and to some micro-physical processes involved in the picture and not yet completely understood. The aim of this work is to investigate some of these micro-physical inputs, namely the electro-weak processes, that play a crucial role during the gravitational collapse and to analyse their effects by means of hydrodynamical simulations. Among nuclear processes which occur in core-collapse supernova, the most important electro-weak process taking place during the collapse is the electron capture; it occurs both on free protons and on protons bound in nuclei. This capture is essential to determine the evolution of the lepton fraction of the core during the neutronization phase. It affects the efficiency of the bounce and, as a consequence, the strength of the shock wave. Moreover, both the equation of state of supernova matter and electron capture rates in nuclei are modified by the effective mass of nucleons in nuclei, induced by many-body correlations in the dense medium, and its temperature dependence. In the first part of the thesis, a nuclear model aimed at studying the nuclear effective mass is presented. We show how we have included in a energy density functional (EDF) approach a surface-peaked nucleon effective mass to mimic some effects beyond Hartree-Fock. We have added a term to the Skyrme functional, in order to reproduce the enhancement of the effective mass at the

  3. Detecting free-mass common-mode motion induced by incident gravitational waves

    Science.gov (United States)

    Tobar, Michael Edmund; Suzuki, Toshikazu; Kuroda, Kazuaki

    1999-05-01

    In this paper we show that information on both the differential and common mode free-mass response to a gravitational wave can provide important information on discriminating the direction of the gravitational wave source and between different theories of gravitation. The conventional Michelson interferometer scheme only measures the differential free-mass response. By changing the orientation of the beam splitter, it is possible to configure the detector so it is sensitive to the common-mode of the free-mass motion. The proposed interferometer is an adaptation of the Fox-Smith interferometer. A major limitation to the new scheme is its enhanced sensitivity to laser frequency fluctuations over the conventional, and we propose a method of cancelling these fluctuations. The configuration could be used in parallel to the conventional differential detection scheme with a significant sensitivity and bandwidth.

  4. Effects of coconut granular activated carbon pretreatment on membrane filtration in a gravitational driven process to improve drinking water quality.

    Science.gov (United States)

    da Silva, Flávia Vieira; Yamaguchi, Natália Ueda; Lovato, Gilselaine Afonso; da Silva, Fernando Alves; Reis, Miria Hespanhol Miranda; de Amorim, Maria Teresa Pessoa Sousa; Tavares, Célia Regina Granhen; Bergamasco, Rosângela

    2012-01-01

    This study evaluates the performance of a polymeric microfiltration membrane, as well as its combination with a coconut granular activated carbon (GAC) pretreatment, in a gravitational filtration module, to improve the quality of water destined to human consumption. The proposed membrane and adsorbent were thoroughly characterized using instrumental techniques, such as contact angle, Brunauer-Emmett-Teller) and Fourier transform infrared spectroscopy analyses. The applied processes (membrane and GAC + membrane) were evaluated regarding permeate flux, fouling percentage, pH and removal of Escherichia coli, colour, turbidity and free chlorine. The obtained results for filtrations with and without GAC pretreatment were similar in terms of water quality. GAC pretreatment ensured higher chlorine removals, as well as higher initial permeate fluxes. This system, applying GAC as a pretreatment and a gravitational driven membrane filtration, could be considered as an alternative point-of-use treatment for water destined for human consumption.

  5. Gravitational Waves

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Jonah Maxwell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-18

    This report has slides on Gravitational Waves; Pound and Rebka: A Shocking Fact; Light is a Ruler; Gravity is the Curvature of Spacetime; Gravitational Waves Made Simple; How a Gravitational Wave Affects Stuff Here; LIGO; This Detection: Neutron Stars; What the Gravitational Wave Looks Like; The Sound of Merging Neutron Stars; Neutron Star Mergers: More than GWs; The Radioactive Cloud; The Kilonova; and finally Summary, Multimessenger Astronomy.

  6. Gravitational, erosional and depositional processes on volcanic ocean islands: Insights from the submarine morphology of Madeira Archipelago

    Science.gov (United States)

    Quartau, Rui; Ramalho, Ricardo S.; Madeira, José; Santos, Rúben; Rodrigues, Aurora; Roque, Cristina; Carrara, Gabriela; Brum da Silveira, António

    2018-01-01

    The submarine flanks of volcanic ocean islands are shaped by a variety of physical processes. Whilst volcanic constructional processes are relatively well understood, the gravitational, erosional and depositional processes that lead to the establishment of large submarine tributary systems are still poorly comprehended. Until recently, few studies have offered a comprehensive source-to-sink approach, linking subaerial morphology with near-shore shelf, slope and far-field abyssal features. In particular, few studies have addressed how different aspects of the subaerial part of the system (island height, climate, volcanic activity, wave regime, etc.) may influence submarine flank morphologies. We use multibeam bathymetric and backscatter mosaics of an entire archipelago - Madeira - to investigate the development of their submarine flanks. Crucially, this dataset extends from the nearshore to the deep sea, allowing a solid correlation between submarine morphologies with the physical and geological setting of the islands. In this study we also established a comparison with other island settings, which allowed us to further explore the wider implications of the observations. The submarine flanks of the Madeira Archipelago are deeply dissected by large landslides, most of which also affected the subaerial edifices. Below the shelf break, landslide chutes extend downslope forming poorly defined depositional lobes. Around the islands, a large tributary system composed of gullies and channels has formed where no significant rocky/ridge outcrops are present. In Madeira Island these were likely generated by turbidity currents that originated as hyperpycnal flows, whilst on Porto Santo and Desertas their origin is attributed to storm-induced offshore sediment transport. At the lower part of the flanks (-3000 to -4300 m), where seafloor gradients decrease to 0.5°-3°, several scour and sediment wave fields are present, with the former normally occurring upslope of the latter

  7. Induced gravity with Higgs potential. Elementary interactions and quantum processes

    Energy Technology Data Exchange (ETDEWEB)

    Bezares Roder, Nils Manuel

    2010-07-01

    This work is intended to first serve as introduction in fundamental subjects of physics in order to be then able to review the mechanism of symmetry breakdown and its essential character in physics. It introduces the concept of scalar-tensor theories of gravity based on Bergmann-Wagoner models with a Higgs potential. The main physical context aimed is the problem of Dark Matter and Dark Energy. On the one hand, there is gravitation. Within this context, we have Dark Matter as an especially relevant concept. This work entails the following main contributions: - General features of Einstein's theory are introduced together with generalities of the different elementary interactions of physics from which the concepts of dark sectors and Higgs Mechanism are derived. - The concept of symmetry breaking and especially the Higgs Mechanism of mass generation are discussed in their relevance for the most different subjects of physics, especially in relation to the Standard Model of elementary particle physics with elementary Higgs fields. - Scalar-Tensor Theories are introduced in order to build in them the process of Higgs Mechanism. This is then fulfilled with a theory of induced gravity with a Higgs potential which seems renormalizable according to deWitt's power counting criterion, and with mass-generating Higgs fields which only couple gravitationally as well as with Higgs fields which act analogously to cosmon fields. - Further, the energy density of the gravitational field is derived for the specific model of induced gravity from an analogy to electrodynamics. It is shown that a nonvanishing value of pressure related to the scalar field is necessary in order to reproduce standard linear solar-relativistic dynamics. Within astrophysical considerations for flat rotation curves of galaxies, a possible dark-matter behavior is concluded within spherical symmetry. The scalar field and the dark-matter profile of total energy density are derived. An analogous

  8. Induced gravity with Higgs potential. Elementary interactions and quantum processes

    International Nuclear Information System (INIS)

    Bezares Roder, Nils Manuel

    2010-01-01

    This work is intended to first serve as introduction in fundamental subjects of physics in order to be then able to review the mechanism of symmetry breakdown and its essential character in physics. It introduces the concept of scalar-tensor theories of gravity based on Bergmann-Wagoner models with a Higgs potential. The main physical context aimed is the problem of Dark Matter and Dark Energy. On the one hand, there is gravitation. Within this context, we have Dark Matter as an especially relevant concept. This work entails the following main contributions: - General features of Einstein's theory are introduced together with generalities of the different elementary interactions of physics from which the concepts of dark sectors and Higgs Mechanism are derived. - The concept of symmetry breaking and especially the Higgs Mechanism of mass generation are discussed in their relevance for the most different subjects of physics, especially in relation to the Standard Model of elementary particle physics with elementary Higgs fields. - Scalar-Tensor Theories are introduced in order to build in them the process of Higgs Mechanism. This is then fulfilled with a theory of induced gravity with a Higgs potential which seems renormalizable according to deWitt's power counting criterion, and with mass-generating Higgs fields which only couple gravitationally as well as with Higgs fields which act analogously to cosmon fields. - Further, the energy density of the gravitational field is derived for the specific model of induced gravity from an analogy to electrodynamics. It is shown that a nonvanishing value of pressure related to the scalar field is necessary in order to reproduce standard linear solar-relativistic dynamics. Within astrophysical considerations for flat rotation curves of galaxies, a possible dark-matter behavior is concluded within spherical symmetry. The scalar field and the dark-matter profile of total energy density are derived. An analogous relation between

  9. Imprint of accretion disk-induced migration on gravitational waves from extreme mass ratio inspirals.

    Science.gov (United States)

    Yunes, Nicolás; Kocsis, Bence; Loeb, Abraham; Haiman, Zoltán

    2011-10-21

    We study the effects of a thin gaseous accretion disk on the inspiral of a stellar-mass black hole into a supermassive black hole. We construct a phenomenological angular momentum transport equation that reproduces known disk effects. Disk torques modify the gravitational wave phase evolution to detectable levels with LISA for reasonable disk parameters. The Fourier transform of disk-modified waveforms acquires a correction with a different frequency trend than post-Newtonian vacuum terms. Such inspirals could be used to detect accretion disks with LISA and to probe their physical parameters. © 2011 American Physical Society

  10. Long-term evolution and gravitational wave radiation of neutron stars with differential rotation induced by r-modes

    International Nuclear Information System (INIS)

    Yu Yunwei; Cao Xiaofeng; Zheng Xiaoping

    2009-01-01

    In a second-order r-mode theory, Sa and Tome found that the r-mode oscillation in neutron stars (NSs) could induce stellar differential rotation, which naturally leads to a saturated state of the oscillation. Based on a consideration of the coupling of the r-modes and the stellar spin and thermal evolution, we carefully investigate the influences of the differential rotation on the long-term evolution of isolated NSs and NSs in low-mass X-ray binaries, where the viscous damping of the r-modes and its resultant effects are taken into account. The numerical results show that, for both kinds of NSs, the differential rotation can significantly prolong the duration of the r-modes. As a result, the stars can keep nearly a constant temperature and constant angular velocity for over a thousand years. Moreover, the persistent radiation of a quasi-monochromatic gravitational wave would also be predicted due to the long-term steady r-mode oscillation and stellar rotation. This increases the detectability of gravitational waves from both young isolated and old accreting NSs. (research papers)

  11. Testing the gravitational instability hypothesis?

    Science.gov (United States)

    Babul, Arif; Weinberg, David H.; Dekel, Avishai; Ostriker, Jeremiah P.

    1994-01-01

    We challenge a widely accepted assumption of observational cosmology: that successful reconstruction of observed galaxy density fields from measured galaxy velocity fields (or vice versa), using the methods of gravitational instability theory, implies that the observed large-scale structures and large-scale flows were produced by the action of gravity. This assumption is false, in that there exist nongravitational theories that pass the reconstruction tests and gravitational theories with certain forms of biased galaxy formation that fail them. Gravitational instability theory predicts specific correlations between large-scale velocity and mass density fields, but the same correlations arise in any model where (a) structures in the galaxy distribution grow from homogeneous initial conditions in a way that satisfies the continuity equation, and (b) the present-day velocity field is irrotational and proportional to the time-averaged velocity field. We demonstrate these assertions using analytical arguments and N-body simulations. If large-scale structure is formed by gravitational instability, then the ratio of the galaxy density contrast to the divergence of the velocity field yields an estimate of the density parameter Omega (or, more generally, an estimate of beta identically equal to Omega(exp 0.6)/b, where b is an assumed constant of proportionality between galaxy and mass density fluctuations. In nongravitational scenarios, the values of Omega or beta estimated in this way may fail to represent the true cosmological values. However, even if nongravitational forces initiate and shape the growth of structure, gravitationally induced accelerations can dominate the velocity field at late times, long after the action of any nongravitational impulses. The estimated beta approaches the true value in such cases, and in our numerical simulations the estimated beta values are reasonably accurate for both gravitational and nongravitational models. Reconstruction tests

  12. Gravitational perturbation of the BTZ black hole induced by test particles and weak cosmic censorship in AdS spacetime

    International Nuclear Information System (INIS)

    Rocha, Jorge V.; Cardoso, Vitor

    2011-01-01

    We analyze the gravitational perturbations induced by particles falling into a three dimensional, asymptotically AdS black hole geometry. More specifically, we solve the linearized perturbation equations obtained from the geodesic motion of a ringlike distribution of test particles in the BTZ background. This setup ensures that the U(1) symmetry of the background is preserved. The nonasymptotic flatness of the background raises difficulties in attributing the significance of energy and angular momentum to the conserved quantities of the test particles. This issue is well known but, to the best of our knowledge, has never been addressed in the literature. We confirm that the naive expressions for energy and angular momentum are the correct definitions. Finally, we put an asymptotically AdS version of the weak cosmic censorship to a test: by attempting to overspin the BTZ black hole with test particles it is found that the black hole cannot be spun-up past its extremal limit.

  13. Gravitation Waves

    CERN Multimedia

    CERN. Geneva

    2005-01-01

    We will present a brief introduction to the physics of gravitational waves and their properties. We will review potential astrophysical sources of gravitational waves, and the physics and astrophysics that can be learned from their study. We will survey the techniques and technologies for detecting gravitational waves for the first time, including bar detectors and broadband interferometers, and give a brief status report on the international search effort, with special emphasis on the LIGO detectors and search results.

  14. Dirichlet Process Gaussian-mixture model: An application to localizing coalescing binary neutron stars with gravitational-wave observations

    Science.gov (United States)

    Del Pozzo, W.; Berry, C. P. L.; Ghosh, A.; Haines, T. S. F.; Singer, L. P.; Vecchio, A.

    2018-06-01

    We reconstruct posterior distributions for the position (sky area and distance) of a simulated set of binary neutron-star gravitational-waves signals observed with Advanced LIGO and Advanced Virgo. We use a Dirichlet Process Gaussian-mixture model, a fully Bayesian non-parametric method that can be used to estimate probability density functions with a flexible set of assumptions. The ability to reliably reconstruct the source position is important for multimessenger astronomy, as recently demonstrated with GW170817. We show that for detector networks comparable to the early operation of Advanced LIGO and Advanced Virgo, typical localization volumes are ˜104-105 Mpc3 corresponding to ˜102-103 potential host galaxies. The localization volume is a strong function of the network signal-to-noise ratio, scaling roughly ∝ϱnet-6. Fractional localizations improve with the addition of further detectors to the network. Our Dirichlet Process Gaussian-mixture model can be adopted for localizing events detected during future gravitational-wave observing runs, and used to facilitate prompt multimessenger follow-up.

  15. Inferences About the Distribution, Merger Rate, and Evolutionary Processes of Compact Binaries From Gravitational Wave Observations

    Science.gov (United States)

    Wysocki, Daniel

    We are living through the dawn of the era of gravitational wave astronomy. Our first glances through this new window upon the sky has revealed a new population of objects. Since it first began observing in late 2015, the advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) has detected gravitational waves three times, along with an additional strong candidate - and there shall be orders of magnitude more in the years to come. In all four cases, the waveform's signature is consistent with general relativity's predictions for the merging of two black holes. Through parameter estimation studies, estimates on features such as the black holes' masses and spins have been determined. At least two of the black hole pairs lie above the mass range spanned by comparable black holes observed through traditional means. This suggests they constitute a separate population, either too elusive or rare to be found with traditional telescopes. The most natural questions to ask about these black holes - how did they form, how many of them are there, and how can they be categorized - remain open ended. We know black holes can form when massive stars die, so it's most natural to claim stars as their progenitors. Since we now know black holes merge into larger black holes, could it be the case that they formed from previous mergers? Were the two black holes part of a binary from their birth, or did they become coupled later on in life? The measurements provided by LIGO can help answer these questions and more. Throughout this thesis, I will describe and demonstrate results from a number of novel methods whose purpose is to better understand these black holes and their progenitors. At their heart, these methods give answers to a few, critical questions. a) What is the overall rate at which these objects merge? b) What is the range of values these objects' properties can take, and how are they distributed? c) Given a number of physical models, how can we evaluate the

  16. Elementary process theory: a formal axiomatic system with a potential application as a foundational framework for physics supporting gravitational repulsion of matter and antimatter

    International Nuclear Information System (INIS)

    Cabbolet, M.J.T.F.

    2010-01-01

    Theories of modern physics predict that antimatter having rest mass will be attracted by the earth's gravitational field, but the actual coupling of antimatter with gravitation has not been established experimentally. The purpose of the present research was to identify laws of physics that would govern the universe if antimatter having rest mass would be repulsed by the earth's gravitational field. As a result, a formalized axiomatic system was developed together with interpretation rules for the terms of the language: the intention is that every theorem of the system yields a true statement about physical reality. Seven non-logical axioms of this axiomatic system form the elementary process theory (EPT): this is then a scheme of elementary principles describing the dynamics of individual processes taking place at supersmall scale. It is demonstrated how gravitational repulsion functions in the universe of the EPT, and some observed particles and processes have been formalized in the framework of the EPT. Incompatibility of quantum mechanics (QM) and General Relativity (GR) with the EPT is proven mathematically; to demonstrate applicability to real world problems to which neither QM nor GR applies, the EPT has been applied to a theory of the Planck era of the universe. The main conclusions are that a completely formalized framework for physics has been developed supporting the existence of gravitational repulsion and that the present results give rise to a potentially progressive research program. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  17. Gravitational influences on the liquid-state homogenization and solidification of aluminum antimonide. [space processing of solar cell material

    Science.gov (United States)

    Ang, C.-Y.; Lacy, L. L.

    1979-01-01

    Typical commercial or laboratory-prepared samples of polycrystalline AlSb contain microstructural inhomogeneities of Al- or Sb-rich phases in addition to the primary AlSb grains. The paper reports on gravitational influences, such as density-driven convection or sedimentation, that cause microscopic phase separation and nonequilibrium conditions to exist in earth-based melts of AlSb. A triple-cavity electric furnace is used to homogenize the multiphase AlSb samples in space and on earth. A comparative characterization of identically processed low- and one-gravity samples of commercial AlSb reveals major improvements in the homogeneity of the low-gravity homogenized material.

  18. Gravitational capture

    International Nuclear Information System (INIS)

    Bondi, H.

    1979-01-01

    In spite of the strength of gravitational focres between celestial bodies, gravitational capture is not a simple concept. The principles of conservation of linear momentum and of conservation of angular momentum, always impose severe constraints, while conservation of energy and the vital distinction between dissipative and non-dissipative systems allows one to rule out capture in a wide variety of cases. In complex systems especially those without dissipation, long dwell time is a more significant concept than permanent capture. (author)

  19. Simulation of the Processes of Formation of a Dust Cloud in a Vacuum and in the Absence of Gravitation

    Science.gov (United States)

    Avdeev, A. V.; Boreisho, A. S.; Ivakin, S. V.; Moiseev, A. A.; Savin, A. V.; Sokolov, E. I.; Smirnov, P. G.

    2018-01-01

    This article is devoted to the simulation of the processes of formation of dust clouds in the absence of gravitation, which is necessary for understanding the processes proceeding in dust clusters in outer space, upper planetary atmosphere, and on the surface of space objects, as well as for evaluating the possibilities of creating disperse structures with given properties. The chief aim of the simulation is to determine the general laws of the dynamics of the dust cloud at the initial stage of its formation. With the use of the original approach based on the particle-in-cell method that permits investigating the mechanics of large ensembles of particles on contemporary computational platforms, we consider the mechanics of a dusty medium in the process of its excitation in a closed container due to the vibration of the walls, and then in the process of particle scattering when the container opens in outer space. The main formation mechanisms of a dust formation have been elucidated, and the possibilities of mathematical simulation for predicting spatial and time characteristics of disperse structures have been shown.

  20. An introductory review on gravitational-deformation induced structures, fabrics and modeling

    Science.gov (United States)

    Jaboyedoff, Michel; Penna, Ivanna; Pedrazzini, Andrea; Baroň, Ivo; Crosta, Giovanni B.

    2013-10-01

    Recent studies have pointed out a similarity between tectonics and slope tectonic-induced structures. Numerous studies have demonstrated that structures and fabrics previously interpreted as of purely geodynamical origin are instead the result of large slope deformation, and this led in the past to erroneous interpretations. Nevertheless, their limit seems not clearly defined, but it is somehow transitional. Some studies point out continuity between failures developing at surface with upper crust movements. In this contribution, the main studies which examine the link between rock structures and slope movements are reviewed. The aspects regarding model and scale of observation are discussed together with the role of pre-existing weaknesses in the rock mass. As slope failures can develop through progressive failure, structures and their changes in time and space can be recognized. Furthermore, recognition of the origin of these structures can help in avoiding misinterpretations of regional geology. This also suggests the importance of integrating different slope movement classifications based on distribution and pattern of deformation and the application of structural geology techniques. A structural geology approach in the landslide community is a tool that can greatly support the hazard quantification and related risks, because most of the physical parameters, which are used for landslide modeling, are derived from geotechnical tests or the emerging geophysical approaches.

  1. Gravitational lensing

    CERN Document Server

    Dodelson, Scott

    2017-01-01

    Gravitational lensing is a consequence of general relativity, where the gravitational force due to a massive object bends the paths of light originating from distant objects lying behind it. Using very little general relativity and no higher level mathematics, this text presents the basics of gravitational lensing, focusing on the equations needed to understand the phenomena. It then applies them to a diverse set of topics, including multiply imaged objects, time delays, extrasolar planets, microlensing, cluster masses, galaxy shape measurements, cosmic shear, and lensing of the cosmic microwave background. This approach allows undergraduate students and others to get quickly up to speed on the basics and the important issues. The text will be especially relevant as large surveys such as LSST and Euclid begin to dominate the astronomical landscape. Designed for a one semester course, it is accessible to anyone with two years of undergraduate physics background.

  2. Discovery of two new gravitation lens systems

    International Nuclear Information System (INIS)

    Guertler, J.

    1988-01-01

    The discovery of new quasar and radio galaxy double images produced by the gravitation lens effect is reported. The light deflecting galaxies acting as gravitational lenses could be made visible by means of image processing procedures

  3. Investigation of influence of drying agent movement on the drying process effectiveness in the gravitational shelf dryer

    Directory of Open Access Journals (Sweden)

    N. O. Artyukhova

    2017-12-01

    Full Text Available The article stands for a research of the drying process efficiency of various approaches of reciprocal movement organization of drying agent and disperse material. It focuses on the results of shelf dryer investigation. The test condition was as follows: backflow of the drying agent and disperse material movement; backflow of the drying agent and disperse material movement with the drying agent recirculation; backflow of the drying agent and disperse material movement with the bypassing of drying agent and it’s putting on separate stage of gravitational shelf dryer. The influence of the drying agent movement organization on the characteristics of disperse material and drying agent, energy costs for this process and its efficiency is shown. The recommendations of usage of represented approaches of flows movement organization depending on the desired final moisture of the material as well as its physical and chemical properties are given. The proposed ways of reciprocal flows movement organization allow to reduce the costs of drying agent heating or to increase the efficiency of moisture removal at constant energy consumption.

  4. Gravitational Physics

    OpenAIRE

    Schäfer, G.; Schutz, B.

    1996-01-01

    Gravity is truly universal. It is the force that pulls us to the Earth, that keeps the planets and moons in their orbits, and that causes the tides on the Earth to ebb and flow. It even keeps the Sun shining. Yet on a laboratory scale gravity is extremely weak. The Coulomb force between two protons is 1039 times stronger than the gravitational force between them. Moreover, Newton's gravitational constant is the least accurately known of the fundamental constants: it has been measured to 1 par...

  5. Interaction of gravitational plane waves

    International Nuclear Information System (INIS)

    Ferrari, V.

    1988-01-01

    The mathematical theory of colliding, infinite-fronted, plane gravitational waves is presented. The process of focusing, the creation of singularities and horizons, due to the interaction, and the lens effect due to a beam-like gravitational wave are discussed

  6. Gravitational Grating

    Science.gov (United States)

    Rahvar, Sohrab

    2018-05-01

    In this work, we study the interaction of the electromagnetic wave (EW) from a distant quasar with the gravitational wave (GW) sourced by the binary stars. While in the regime of geometric optics, the light bending due to this interaction is negligible, we show that the phase shifting on the wavefront of an EW can produce the diffraction pattern on the observer plane. The diffraction of the light (with the wavelength of λe) by the gravitational wave playing the role of gravitational grating (with the wavelength of λg) has the diffraction angle of Δβ ˜ λe/λg. The relative motion of the observer, the source of gravitational wave and the quasar results in a relative motion of the observer through the interference pattern on the observer plane. The consequence of this fringe crossing is the modulation in the light curve of a quasar with the period of few hours in the microwave wavelength. The optical depth for the observation of this phenomenon for a Quasar with the multiple images strongly lensed by a galaxy where the light trajectory of some of the images crosses the lensing galaxy is τ ≃ 0.2. By shifting the time-delay of the light curves of the multiple images in a strong lensed quasar and removing the intrinsic variations of a quasar, our desired signals, as a new method for detection of GWs can be detected.

  7. Do Process Innovations Induce Product Ones?

    OpenAIRE

    Maria Rosa Battaggion; Piero Tedeschi

    2006-01-01

    We study the relationship between process and product innovations in vertically differentiated duopolies. A process innovation can lead two competing firms to improve the quality of their goods introducing a product innovation. In fact, a cost reducing innovation has two effects: it spurs production and it enhances price competition. The former effect induces both firms to increase quality. The latter encourages differentiation, inducing low quality firm to decrease it. Therefore, high qualit...

  8. On the gravitational radiation formula

    International Nuclear Information System (INIS)

    Schaefer, G.; Dehnen, H.

    1980-01-01

    For electromagnetically as well as gravitationally bound quantum mechanical many-body systems the coefficients of absorption and induced emission of gravitational radiation are calculated in the first-order approximation. The results are extended subsequently to systems with arbitrary non-Coulomb-like two-particle interaction potentials;it is shown explicitly that in all cases the perturbation of the binding potentials of the bound systems by the incident gravitational wave field itself must be taken into account. With the help of the thermodynamic equilibrium of gravitational radiation and quantised matter, the coefficients for spontaneous emission of gravitational radiation are derived and the gravitational radiation formula for emission of gravitational quadrupole radiation by bound quantum mechanical many-body systems is given. According to the correspondence principle the present result is completely identical with the well known classical radiation formula, by which recent criticism against this formula is refuted. Finally the quantum mechanical absorption cross section for gravitational quadrupole radiation is deduced and compared with the corresponding classical expressions. As a special example the vibrating two-mass quadrupole is treated explicitly. (author)

  9. Gravitational Casimir–Polder effect

    Directory of Open Access Journals (Sweden)

    Jiawei Hu

    2017-04-01

    Full Text Available The interaction due to quantum gravitational vacuum fluctuations between a gravitationally polarizable object modelled as a two-level system and a gravitational boundary is investigated. This quantum gravitational interaction is found to be position-dependent, which induces a force in close analogy to the Casimir–Polder force in the electromagnetic case. For a Dirichlet boundary, the quantum gravitational potential for the polarizable object in its ground-state is shown to behave like z−5 in the near zone, and z−6 in the far zone, where z is the distance to the boundary. For a concrete example, where a Bose–Einstein condensate is taken as a gravitationally polarizable object, the relative correction to the radius of the BEC caused by fluctuating quantum gravitational waves in vacuum is found to be of order 10−21. Although the correction is far too small to observe in comparison with its electromagnetic counterpart, it is nevertheless of the order of the gravitational strain caused by a recently detected black hole merger on the arms of the LIGO.

  10. Supersymmetry and gravitational duality

    International Nuclear Information System (INIS)

    Argurio, Riccardo; Dehouck, Francois; Houart, Laurent

    2009-01-01

    We study how the supersymmetry algebra copes with gravitational duality. As a playground, we consider a charged Taub-Newman-Unti-Tamburino(NUT) solution of D=4, N=2 supergravity. We find explicitly its Killing spinors, and the projection they obey provides evidence that the dual magnetic momenta necessarily have to appear in the supersymmetry algebra. The existence of such a modification is further supported using an approach based on the Nester form. In the process, we find new expressions for the dual magnetic momenta, including the NUT charge. The same expressions are then rederived using gravitational duality.

  11. Gravitational waves

    CERN Document Server

    Ciufolini, I; Moschella, U; Fre, P

    2001-01-01

    Gravitational waves (GWs) are a hot topic and promise to play a central role in astrophysics, cosmology, and theoretical physics. Technological developments have led us to the brink of their direct observation, which could become a reality in the coming years. The direct observation of GWs will open an entirely new field: GW astronomy. This is expected to bring a revolution in our knowledge of the universe by allowing the observation of previously unseen phenomena, such as the coalescence of compact objects (neutron stars and black holes), the fall of stars into supermassive black holes, stellar core collapses, big-bang relics, and the new and unexpected.With a wide range of contributions by leading scientists in the field, Gravitational Waves covers topics such as the basics of GWs, various advanced topics, GW detectors, astrophysics of GW sources, numerical applications, and several recent theoretical developments. The material is written at a level suitable for postgraduate students entering the field.

  12. Gravitational effects of global textures

    International Nuclear Information System (INIS)

    Noetzold, D.

    1990-03-01

    A solution for the dynamics of global textures is obtained. Their gravitational field during the collapse and the subsequent evolution is found to be given solely by a space-time dependent ''deficit solid angle.'' The frequency shift of photons traversing this gravitational field is calculated. The space-time dependent texture metric locally contracts the volume of three-space and thereby induces overdensities in homogeneous matter distributions. There are no gravitational forces unless matter has a nonzero angular momentum with respect to the texture origin which would be the case for moving textures

  13. Gravitation relativiste

    CERN Document Server

    Hakim, Rémi

    1994-01-01

    Il existe à l'heure actuelle un certain nombre de théories relativistes de la gravitation compatibles avec l'expérience et l'observation. Toutefois, la relativité générale d'Einstein fut historiquement la première à fournir des résultats théoriques corrects en accord précis avec les faits.

  14. The gravitational Schwinger effect and attenuation of gravitational waves

    Science.gov (United States)

    McDougall, Patrick Guarneri

    This paper will discuss the possible production of photons from gravitational waves. This process is shown to be possible by examining Feynman diagrams, the Schwinger Effect, and Hawking Radiation. The end goal of this project is to find the decay length of a gravitational wave and assert that this decay is due to photons being created at the expense of the gravitational wave. To do this, we first find the state function using the Klein Gordon equation, then find the current due to this state function. We then take the current to be directly proportional to the production rate per volume. This is then used to find the decay length that this kind of production would produce, gives a prediction of how this effect will change the distance an event creating a gravitational wave will be located, and shows that this effect is small but can be significant near the source of a gravitational wave.

  15. Frequency-dependent squeeze-amplitude attenuation and squeeze-angle rotation by electromagnetically induced transparency for gravitational-wave interferometers

    International Nuclear Information System (INIS)

    Mikhailov, Eugeniy E.; Goda, Keisuke; Corbitt, Thomas; Mavalvala, Nergis

    2006-01-01

    We study the effects of frequency-dependent squeeze-amplitude attenuation and squeeze-angle rotation by electromagnetically induced transparency (EIT) on gravitational-wave (GW) interferometers. We propose the use of low-pass, bandpass, and high-pass EIT filters, an S-shaped EIT filter, and an intracavity EIT filter to generate frequency-dependent squeezing for injection into the antisymmetric port of GW interferometers. We find that the EIT filters have several advantages over the previous filter designs with regard to optical losses, compactness, and the tunability of the filter linewidth

  16. Gravitational anomalies

    Energy Technology Data Exchange (ETDEWEB)

    Leutwyler, H; Mallik, S

    1986-12-01

    The effective action for fermions moving in external gravitational and gauge fields is analyzed in terms of the corresponding external field propagator. The central object in our approach is the covariant energy-momentum tensor which is extracted from the regular part of the propagator at short distances. It is shown that the Lorentz anomaly, the conformal anomaly and the gauge anomaly can be expressed in terms of the local polynomials which determine the singular part of the propagator. (There are no coordinate anomalies). Except for the conformal anomaly, for which we give explicit representations only in dless than or equal to4, we consider an arbitrary number of dimensions.

  17. GRAVITATIONAL RADIATION

    Directory of Open Access Journals (Sweden)

    Metin SALTIK

    1996-03-01

    Full Text Available According to classical electromagnetic theory, an accelerated charge or system of charges radiates electromagnetic waves. In a radio transmitter antenna charges are accelerated along the antenna and release electromagnetic waves, which is radiated at the velocity of light in the surrounding medium. All of the radio transmitters work on this principle today. In this study an analogy is established between the principles by which accelerated charge systems markes radiation and the accelerated mass system, and the systems cousing gravitational radiation are investigated.

  18. Gravitational lenses

    International Nuclear Information System (INIS)

    Turner, E.L.

    1989-01-01

    The author discusses how gravitational lens studies is becoming a major focus of extragalactic astronomy and cosmology. This review is organized into five parts: an overview of the observational situation, a look at the state of theoretical work on lenses, a detailed look at three recently discovered types of lensing phenomena (luminous arcs, radio rings, quasar-galaxy associations), a review of progress on two old problems in lens studies (deriving unique lens mass distribution models, measurements of differential time delays), and an attempt to look into the future of lens studies

  19. Study of the spheronization process of glass particles by the gravitational falling process for internal selective radiotherapy

    International Nuclear Information System (INIS)

    Barros Filho, E.C.; Martinelli, J.R.; Sene, F.F.

    2011-01-01

    The internal selective radiotherapy is an alternative to treat hepatocellular carcinoma. Glass microspheres containing β - emitter radionuclide are introduced in the liver, and they are housed preferentially in the region where the cancer cells are located. The microspheres are trapped in the arterioles which feed the tumors, and the β - particles annihilate the cancer cells. The glass particles must be spherical to avoid unnecessary bleeding, and the particle size must be restricted to a range which optimizes the blocking effect and avoid the migration to other parts of the human body. The particle size distribution of microspheres is not easily predicted since the variation of the aspect ratio and the presence of agglomerates can influence the resulting particle size distribution. In the present work, the spheronization process to obtain microspheres from irregular shape glass particles with suitable diameter and shape for radiotherapy treatment is studied. (author)

  20. Photoexcitation-induced processes in amorphous semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jai [School of Engineering and Logistics, Charles Darwin University, Darwin, NT 0909 (Australia)]. E-mail: jai.singh@cdu.edu.au

    2005-07-30

    Theories for the mechanism of photo-induced processes of photodarkening (PD), volume expansion (VE) in amorphous chalcogenides are presented. Rates of spontaneous emission of photons by radiative recombination of excitons in amorphous semiconductors are also calculated and applied to study the excitonic photoluminescence in a-Si:H. Results are compared with previous theories.

  1. Photoexcitation-induced processes in amorphous semiconductors

    International Nuclear Information System (INIS)

    Singh, Jai

    2005-01-01

    Theories for the mechanism of photo-induced processes of photodarkening (PD), volume expansion (VE) in amorphous chalcogenides are presented. Rates of spontaneous emission of photons by radiative recombination of excitons in amorphous semiconductors are also calculated and applied to study the excitonic photoluminescence in a-Si:H. Results are compared with previous theories

  2. Gravitational microlensing

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, Aleksandr F [Russian Federation State Scientific Center ' A.I. Alikhanov Institute for Theoretical and Experimental Physics' , Moscow (Russian Federation); Sazhin, Mikhail V [P.K. Shternberg State Astronomical Institute at the M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    1998-10-31

    The foundations of standard microlensing theory are discussed as applied to stars in the Galactic bulge, Magellanic Clouds or other nearby galaxies and gravitational microlenses assumed to lie in-between these stars and the terrestrial observer. In contrast to the review article by Gurevich et al. [48], microlensing by compact objects is mainly considered. Criteria for the identification of microlensing events are discussed as also are microlensing events not satisfying these criteria, such as non-symmetrical light curves and chromatic and polarization effects. The Large Magellanic Cloud (LMC) and Galactic bulge microlensing data of the MACHO group are discussed in detail and also the LMC data of EROS and the Galactic bulge data of OGLE are presented. A detailed comparison of theoretical predictions and observations is given. (reviews of topical problems)

  3. Gravitational microlensing

    International Nuclear Information System (INIS)

    Zakharov, Aleksandr F; Sazhin, Mikhail V

    1998-01-01

    The foundations of standard microlensing theory are discussed as applied to stars in the Galactic bulge, Magellanic Clouds or other nearby galaxies and gravitational microlenses assumed to lie in-between these stars and the terrestrial observer. In contrast to the review article by Gurevich et al. [48], microlensing by compact objects is mainly considered. Criteria for the identification of microlensing events are discussed as also are microlensing events not satisfying these criteria, such as non-symmetrical light curves and chromatic and polarization effects. The Large Magellanic Cloud (LMC) and Galactic bulge microlensing data of the MACHO group are discussed in detail and also the LMC data of EROS and the Galactic bulge data of OGLE are presented. A detailed comparison of theoretical predictions and observations is given. (reviews of topical problems)

  4. Gravitational Anomaly and Transport Phenomena

    International Nuclear Information System (INIS)

    Landsteiner, Karl; Megias, Eugenio; Pena-Benitez, Francisco

    2011-01-01

    Quantum anomalies give rise to new transport phenomena. In particular, a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational anomaly coefficient. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid.

  5. Nonequilibrium process of self-gravitating N-body systems and quasi-equilibrium structure using normalized q-expectation values for Tsallis' generalized entropy

    International Nuclear Information System (INIS)

    Komatsu, Nobuyoshi; Kiwata, Takahiro; Kimura, Shigeo

    2010-01-01

    To clarify the nonequilibrium processes of self-gravitating systems, we examine a system enclosed in a spherical container with reflecting walls, by N-body simulations. To simulate nonequilibrium processes, we consider loss of energy through the reflecting wall, i.e., a particle reflected at a non-adiabatic wall is cooled to mimic energy loss. We also consider quasi-equilibrium structures of stellar polytropes to compare with the nonequilibrium process, where the quasi-equilibrium structure is obtained from an extremum-state of Tsallis' entropy. Consequently, we numerically show that, with increasing cooling rates, the dependence of the temperature on energy, i.e., the ε-T curve, varies from that of microcanonical ensembles (or isothermal spheres) to a common curve. The common curve appearing in the nonequilibrium process agrees well with an ε-T curve for a quasi-equilibrium structure of the stellar polytrope, especially for the polytrope index n ∼ 5. In fact, for n > 5, the stellar polytrope within an adiabatic wall exhibits gravothermal instability [Taruya, Sakagami, Physica A, 322 (2003) 285]. The present study indicates that the stellar polytrope with n ∼ 5 likely plays an important role in quasi-attractors of the nonequilibrium process in self-gravitating systems with non-adiabatic walls.

  6. Heat pump processes induced by laser radiation

    Science.gov (United States)

    Garbuny, M.; Henningsen, T.

    1980-01-01

    A carbon dioxide laser system was constructed for the demonstration of heat pump processes induced by laser radiation. The system consisted of a frequency doubling stage, a gas reaction cell with its vacuum and high purity gas supply system, and provisions to measure the temperature changes by pressure, or alternatively, by density changes. The theoretical considerations for the choice of designs and components are dicussed.

  7. Understanding possible electromagnetic counterparts to loud gravitational wave events: Binary black hole effects on electromagnetic fields

    International Nuclear Information System (INIS)

    Palenzuela, Carlos; Lehner, Luis; Yoshida, Shin

    2010-01-01

    In addition to producing loud gravitational waves, the dynamics of a binary black hole system could induce emission of electromagnetic radiation by affecting the behavior of plasmas and electromagnetic fields in their vicinity. We study how the electromagnetic fields are affected by a pair of orbiting black holes through the merger. In particular, we show how the binary's dynamics induce a variability in possible electromagnetically induced emissions as well as an enhancement of electromagnetic fields during the late-merge and merger epochs. These time dependent features will likely leave their imprint in processes generating detectable emissions and can be exploited in the detection of electromagnetic counterparts of gravitational waves.

  8. Feed-Forward Neural Network Soft-Sensor Modeling of Flotation Process Based on Particle Swarm Optimization and Gravitational Search Algorithm

    Directory of Open Access Journals (Sweden)

    Jie-Sheng Wang

    2015-01-01

    Full Text Available For predicting the key technology indicators (concentrate grade and tailings recovery rate of flotation process, a feed-forward neural network (FNN based soft-sensor model optimized by the hybrid algorithm combining particle swarm optimization (PSO algorithm and gravitational search algorithm (GSA is proposed. Although GSA has better optimization capability, it has slow convergence velocity and is easy to fall into local optimum. So in this paper, the velocity vector and position vector of GSA are adjusted by PSO algorithm in order to improve its convergence speed and prediction accuracy. Finally, the proposed hybrid algorithm is adopted to optimize the parameters of FNN soft-sensor model. Simulation results show that the model has better generalization and prediction accuracy for the concentrate grade and tailings recovery rate to meet the online soft-sensor requirements of the real-time control in the flotation process.

  9. Propagation of waves in a gravitating and rotating anisotropic heat ...

    African Journals Online (AJOL)

    Bheema

    astrophysical plasmas. These plasmas are usually self-gravitating, rotating and embedded in a .... gravitational potential, and P denotes the anisotropic pressure tensor defined as. ൌ ୄ ൅ ሺ צǦ ..... Nonlinear Processes Geophysics, 11 :731.

  10. Fault propagation folds induced by gravitational failure and slumping of the Central Costa Rica volcanic range: Implications for large terrestrial and Martian volcanic edifices

    International Nuclear Information System (INIS)

    Borgia, A.; Burr, J.; Montero, W.; Morales, L.D.; Alvarado, G.E.

    1990-01-01

    Long sublinear ridges and related scarps located at the base of large volcanic structures are frequently interpreted as normal faults associated with extensional regional stress. In contrast, the ridges bordering the Central Costa Rica volcanic range (CCRVR) are the topographic expression of hanging wall asymmetric angular anticlines overlying low-angle thrust faults at the base of the range. These faults formed by gravitational failure and slumping of the flanks of the range due to the weight of the volcanic edifices and were perhaps triggered by the intrusion of magma over the past 20,000 years. These anticlines are hypothesized to occur along the base of the volcano, where the thrust faults ramp up toward the sea bottom. Ridges and scarps between 2,000 and 5,000 m below sea level are interpreted as the topographic expression of these folds. The authors further suggest that the scarps of the CCRVR and valid scaled terrestrial analogs of the perimeter scarp of the Martian volcano Olympus Mons. They suggest that the crust below Olympus Mons has failed under the load of the volcano, triggering the radial slumping of the flanks of the volcano on basal thrusts. The thrusting would have, in turn, formed the anticlinal ridges and scarps that surround the edifice. The thrust faults may extend all the way to the base of the Martian crust (about 40 km), and they may have been active until almost the end of the volcanic activity. They suggest that gravitational failure and slumping of the flanks of volcanoes is a process common to most large volcanic edifices. In the CCRVR this slumping of the flanks is a slow intermittent process, but it could evolve to rapid massive avalanching leading to catastrophic eruptions. Thus monitoring of uplift and displacement of the folds related to the slump tectonics could become an additional effective method for mitigating volcanic hazards

  11. The Newton constant and gravitational waves in some vector field adjusting mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Santillán, Osvaldo P. [IMAS (UBA-CONICET), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires 1428 (Argentina); Scornavacche, Marina, E-mail: firenzecita@hotmail.com, E-mail: marina.scorna@hotmail.com [Departamento de Física, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires 1428 (Argentina)

    2017-10-01

    At the present, there exist some Lorentz breaking scenarios which explain the smallness of the cosmological constant at the present era [1]–[2]. An important aspect to analyze is the propagation of gravitational waves and the screening or enhancement of the Newton constant G {sub N} in these models. The problem is that the Lorentz symmetry breaking terms may induce an unacceptable value of the Newton constant G {sub N} or introduce longitudinal modes in the gravitational wave propagation. Furthermore this breaking may spoil the standard dispersion relation ω= ck . In [3] the authors have presented a model suggesting that the behavior of the gravitational constant is correct for asymptotic times. In the present work, an explicit checking is made and we finally agree with these claims. Furthermore, it is suggested that the gravitational waves are also well behaved for large times. In the process, some new models with the same behavior are obtained, thus enlarging the list of possible adjustment mechanisms.

  12. Prevention of gravitational collapse

    International Nuclear Information System (INIS)

    Moffat, J.W.; Taylor, J.G.

    1981-01-01

    We apply a new theory of gravitation to the question of gravitational collapse to show that collapse is prevented in this theory under very reasonable conditions. This result also extends to prevent ultimate collapse of the Universe. (orig.)

  13. Underdevelopment’s gravitation

    Directory of Open Access Journals (Sweden)

    Marin Dinu

    2013-09-01

    Full Text Available The energy necessary to escape the gravitational pull of underdevelopment and to enter an evolutional trajectory dependent on the gravitational pull of development is unintelligible in economic terms.

  14. Irradiation-induced amorphization process in graphite

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Hiroaki [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1996-04-01

    Effects of the element process of irradiation damage on irradiation-induced amorphization processes of graphite was studied. High orientation thermal decomposed graphite was cut about 100 nm width and used as samples. The irradiation experiments are carried out under the conditions of electronic energy of 100-400 KeV, ion energy of 200-600 KeV, ionic species Xe, Ar, Ne, C and He and the irradiation temperature at from room temperature to 900 K. The critical dose ({phi}a) increases exponentially with increasing irradiation temperature. The displacement threshold energy of graphite on c-axis direction was 27 eV and {phi}a{sup e} = 0.5 dpa. dpa is the average number of displacement to atom. The critical dose of ion irradiation ({phi}a{sup i}) was 0.2 dpa at room temperature, and amorphous graphite was produced by less than half of dose of electronic irradiation. Amorphization of graphite depending upon temperature is discussed. (S.Y.)

  15. Gravitation in Material Media

    Science.gov (United States)

    Ridgely, Charles T.

    2011-01-01

    When two gravitating bodies reside in a material medium, Newton's law of universal gravitation must be modified to account for the presence of the medium. A modified expression of Newton's law is known in the literature, but lacks a clear connection with existing gravitational theory. Newton's law in the presence of a homogeneous material medium…

  16. Detection of gravitational radiation

    Energy Technology Data Exchange (ETDEWEB)

    Holten, J.W. van [ed.

    1994-12-31

    In this report the main contributions presented at the named symposium are collected. These concern astrophysical sources of gravitational radiation, ultracryogenic gravitational wave experiments, read out and data analysis of gravitational wave antennas, cryogenic aspects of large mass cooling to mK temperatures, and metallurgical and engineering aspects of large Cu structure manufacturing. (HSI).

  17. Detection of gravitational radiation

    International Nuclear Information System (INIS)

    Holten, J.W. van

    1994-01-01

    In this report the main contributions presented at the named symposium are collected. These concern astrophysical sources of gravitational radiation, ultracryogenic gravitational wave experiments, read out and data analysis of gravitational wave antennas, cryogenic aspects of large mass cooling to mK temperatures, and metallurgical and engineering aspects of large Cu structure manufacturing. (HSI)

  18. Relativity theory and gravitation

    International Nuclear Information System (INIS)

    Bondi, H.

    1986-01-01

    The paper on relativity theory and gravitation is presented as a preface to the first of the articles submitted to the Journal on general relativity. Newtonian gravitation and and observation, relativity, and the sources of the gravitational field, are all discussed. (UK)

  19. Relativistic gravitational instabilities

    International Nuclear Information System (INIS)

    Schutz, B.F.

    1987-01-01

    The purpose of these lectures is to review and explain what is known about the stability of relativistic stars and black holes, with particular emphases on two instabilities which are due entirely to relativistic effects. The first of these is the post-Newtonian pulsational instability discovered independently by Chandrasekhar (1964) and Fowler (1964). This effectively ruled out the then-popular supermassive star model for quasars, and it sets a limit to the central density of white dwarfs. The second instability was also discovered by Chandrasekhar (1970): the gravitational wave induced instability. This sets an upper bound on the rotation rate of neutron stars, which is near that of the millisecond pulsar PSR 1937+214, and which is beginning to constrain the equation of state of neutron matter. 111 references, 5 figures

  20. Gravitational Waves and Dark Energy

    Directory of Open Access Journals (Sweden)

    Peter L. Biermann

    2014-12-01

    Full Text Available The idea that dark energy is gravitational waves may explain its strength and its time-evolution. A possible concept is that dark energy is the ensemble of coherent bursts (solitons of gravitational waves originally produced when the first generation of super-massive black holes was formed. These solitons get their initial energy as well as keep up their energy density throughout the evolution of the universe by stimulating emission from a background, a process which we model by working out this energy transfer in a Boltzmann equation approach. New Planck data suggest that dark energy has increased in strength over cosmic time, supporting the concept here. The transit of these gravitational wave solitons may be detectable. Key tests include pulsar timing, clock jitter and the radio background.

  1. Magnetic-distortion-induced Ellipticity and Gravitational Wave Radiation of Neutron Stars: Millisecond Magnetars in Short GRBs, Galactic Pulsars, and Magnetars

    Energy Technology Data Exchange (ETDEWEB)

    Gao, He; Cao, Zhoujian [Department of Astronomy, Beijing Normal University, Beijing 100875 (China); Zhang, Bing, E-mail: gaohe@bnu.edu.cn [Department of Physics and Astronomy, University of Nevada Las Vegas, NV 89154 (United States)

    2017-08-01

    Neutron stars may sustain a non-axisymmetric deformation due to magnetic distortion and are potential sources of continuous gravitational waves (GWs) for ground-based interferometric detectors. With decades of searches using available GW detectors, no evidence of a GW signal from any pulsar has been observed. Progressively stringent upper limits of ellipticity have been placed on Galactic pulsars. In this work, we use the ellipticity inferred from the putative millisecond magnetars in short gamma-ray bursts (SGRBs) to estimate their detectability by current and future GW detectors. For ∼1 ms magnetars inferred from the SGRB data, the detection horizon is ∼30 Mpc and ∼600 Mpc for the advanced LIGO (aLIGO) and Einstein Telescope (ET), respectively. Using the ellipticity of SGRB millisecond magnetars as calibration, we estimate the ellipticity and GW strain of Galactic pulsars and magnetars assuming that the ellipticity is magnetic-distortion-induced. We find that the results are consistent with the null detection results of Galactic pulsars and magnetars with the aLIGO O1. We further predict that the GW signals from these pulsars/magnetars may not be detectable by the currently designed aLIGO detector. The ET detector may be able to detect some relatively low-frequency signals (<50 Hz) from some of these pulsars. Limited by its design sensitivity, the eLISA detector seems to not be suitable for detecting the signals from Galactic pulsars and magnetars.

  2. Theory of gravitational interactions

    CERN Document Server

    Gasperini, Maurizio

    2017-01-01

    This is the second edition of a well-received book that is a modern, self-contained introduction to the theory of gravitational interactions. The new edition includes more details on gravitational waves of cosmological origin, the so-called brane world scenario, and gravitational time-delay effects. The first part of the book follows the traditional presentation of general relativity as a geometric theory of the macroscopic gravitational field, while the second, more advanced part discusses the deep analogies (and differences) between a geometric theory of gravity and the “gauge” theories of the other fundamental interactions. This fills a gap within the traditional approach to general relativity which usually leaves students puzzled about the role of gravity. The required notions of differential geometry are reduced to the minimum, allowing room for aspects of gravitational physics of current phenomenological and theoretical interest, such as the properties of gravitational waves, the gravitational inter...

  3. Gravitational waves from inflation

    International Nuclear Information System (INIS)

    Guzzetti, M.C.; Bartolo, N.; Liguori, M.; Matarrese, S.

    2016-01-01

    The production of a stochastic background of gravitational waves is a fundamental prediction of any cosmological inflationary model. The features of such a signal encode unique information about the physics of the Early Universe and beyond, thus representing an exciting, powerful window on the origin and evolution of the Universe. We review the main mechanisms of gravitational-wave production, ranging from quantum fluctuations of the gravitational field to other mechanisms that can take place during or after inflation. These include e.g. gravitational waves generated as a consequence of extra particle production during inflation, or during the (p)reheating phase. Gravitational waves produced in inflation scenarios based on modified gravity theories and second-order gravitational waves are also considered. For each analyzed case, the expected power spectrum is given. We discuss the discriminating power among different models, associated with the validity/violation of the standard consistency relation between tensor-to-scalar ratio r and tensor spectral index ηT. In light of the prospects for (directly/indirectly) detecting primordial gravitational waves, we give the expected present-day gravitational radiation spectral energy-density, highlighting the main characteristics imprinted by the cosmic thermal history, and we outline the signatures left by gravitational waves on the Cosmic Microwave Background and some imprints in the Large-Scale Structure of the Universe. Finally, current bounds and prospects of detection for inflationary gravitational waves are summarized.

  4. Gravitationally induced zero modes of the Faddeev-Popov operator in the Coulomb gauge for Abelian gauge theories

    Science.gov (United States)

    Canfora, Fabrizio; Giacomini, Alex; Oliva, Julio

    2010-08-01

    It is shown that on curved backgrounds, the Coulomb gauge Faddeev-Popov operator can have zero modes even in the Abelian case. These zero modes cannot be eliminated by restricting the path integral over a certain region in the space of gauge potentials. The conditions for the existence of these zero modes are studied for static spherically symmetric spacetimes in arbitrary dimensions. For this class of metrics, the general analytic expression of the metric components in terms of the zero modes is constructed. Such expression allows one to find the asymptotic behavior of background metrics, which induce zero modes in the Coulomb gauge, an interesting example being the three-dimensional anti-de Sitter spacetime. Some of the implications for quantum field theory on curved spacetimes are discussed.

  5. Anisotropic gravitational instability

    International Nuclear Information System (INIS)

    Polyachenko, V.L.; Fridman, A.M.

    1988-01-01

    Exact solutions of stability problems are obtained for two anisotropic gravitational systems of different geometries - a layer of finite thickness at rest and a rotating cylinder of finite radius. It is shown that the anisotropic gravitational instability which develops in both cases is of Jeans type. However, in contrast to the classical aperiodic Jeans instability, this instability is oscillatory. The physics of the anisotropic gravitational instability is investigated. It is shown that in a gravitating layer this instability is due, in particular, to excitation of previously unknown interchange-Jeans modes. In the cylinder, the oscillatory Jeans instability is associated with excitation of a rotational branch, this also being responsible for the beam gravitational instability. This is the reason why this instability and the anisotropic gravitational instability have so much in common

  6. Gravitation Waves seminar

    CERN Multimedia

    CERN. Geneva HR-RFA

    2006-01-01

    We will present a brief introduction to the physics of gravitational waves and their properties. We will review potential astrophysical sources of gravitational waves, and the physics and astrophysics that can be learned from their study. We will survey the techniques and technologies for detecting gravitational waves for the first time, including bar detectors and broadband interferometers, and give a brief status report on the international search effort.

  7. Gravitational Wave Astronomy

    CERN Multimedia

    CERN. Geneva

    2006-01-01

    Gravitational wave astronomy is expected to become an observational field within the next decade. First direct detection of gravitational waves is possible with existing terrestrial-based detectors, and highly probable with proposed upgrades. In this three-part lecture series, we give an overview of the field, including material on gravitional wave sources, detection methods, some details of interferometric detectors, data analysis methods, and current results from observational data-taking runs of the LIGO and GEO projects.

  8. Gravitation in material media

    International Nuclear Information System (INIS)

    Ridgely, Charles T

    2011-01-01

    When two gravitating bodies reside in a material medium, Newton's law of universal gravitation must be modified to account for the presence of the medium. A modified expression of Newton's law is known in the literature, but lacks a clear connection with existing gravitational theory. Newton's law in the presence of a homogeneous material medium is herein derived on the basis of classical, Newtonian gravitational theory and by a general relativistic use of Archimedes' principle. It is envisioned that the techniques presented herein will be most useful to graduate students and those undergraduate students having prior experience with vector analysis and potential theory.

  9. Gravitation and relativity

    CERN Document Server

    Hoffmann, William F

    1964-01-01

    Remarks on the observational basis of general relativity ; Riemannian geometry ; gravitation as geometry ; gravitational waves ; Mach's principle and experiments on mass anisotropy ; the many faces of Mach ; the significance for the solar system of time-varying gravitation ; relativity principles and the role of coordinates in physics ; the superdense star and the critical nucleon number ; gravitation and light ; possible effects on the solar system of φ waves if they exist ; the Lyttleton-Bondi universe and charge equality ; quantization of general relativity ; Mach's principle as boundary condition for Einstein's equations.

  10. Direction-Specific Impairments in Cervical Range of Motion in Women with Chronic Neck Pain: Influence of Head Posture and Gravitationally Induced Torque.

    Science.gov (United States)

    Rudolfsson, Thomas; Björklund, Martin; Svedmark, Åsa; Srinivasan, Divya; Djupsjöbacka, Mats

    2017-01-01

    Cervical range of motion (ROM) is commonly assessed in clinical practice and research. In a previous study we decomposed active cervical sagittal ROM into contributions from lower and upper levels of the cervical spine and found level- and direction-specific impairments in women with chronic non-specific neck pain. The present study aimed to validate these results and investigate if the specific impairments can be explained by the neutral posture (defining zero flexion/extension) or a movement strategy to avoid large gravitationally induced torques on the cervical spine. Kinematics of the head and thorax was assessed in sitting during maximal sagittal cervical flexion/extension (high torque condition) and maximal protraction (low torque condition) in 120 women with chronic non-specific neck pain and 40 controls. We derived the lower and upper cervical angles, and the head centre of mass (HCM), from a 3-segment kinematic model. Neutral head posture was assessed using a standardized procedure. Previous findings of level- and direction-specific impairments in neck pain were confirmed. Neutral head posture was equal between groups and did not explain the direction-specific impairments. The relative magnitude of group difference in HCM migration did not differ between high and low torques conditions, lending no support for our hypothesis that impairments in sagittal ROM are due to torque avoidance behaviour. The direction- and level-specific impairments in cervical sagittal ROM can be generalised to the population of women with non-specific neck pain. Further research is necessary to clarify if torque avoidance behaviour can explain the impairments.

  11. Direction-Specific Impairments in Cervical Range of Motion in Women with Chronic Neck Pain: Influence of Head Posture and Gravitationally Induced Torque.

    Directory of Open Access Journals (Sweden)

    Thomas Rudolfsson

    Full Text Available Cervical range of motion (ROM is commonly assessed in clinical practice and research. In a previous study we decomposed active cervical sagittal ROM into contributions from lower and upper levels of the cervical spine and found level- and direction-specific impairments in women with chronic non-specific neck pain. The present study aimed to validate these results and investigate if the specific impairments can be explained by the neutral posture (defining zero flexion/extension or a movement strategy to avoid large gravitationally induced torques on the cervical spine.Kinematics of the head and thorax was assessed in sitting during maximal sagittal cervical flexion/extension (high torque condition and maximal protraction (low torque condition in 120 women with chronic non-specific neck pain and 40 controls. We derived the lower and upper cervical angles, and the head centre of mass (HCM, from a 3-segment kinematic model. Neutral head posture was assessed using a standardized procedure.Previous findings of level- and direction-specific impairments in neck pain were confirmed. Neutral head posture was equal between groups and did not explain the direction-specific impairments. The relative magnitude of group difference in HCM migration did not differ between high and low torques conditions, lending no support for our hypothesis that impairments in sagittal ROM are due to torque avoidance behaviour.The direction- and level-specific impairments in cervical sagittal ROM can be generalised to the population of women with non-specific neck pain. Further research is necessary to clarify if torque avoidance behaviour can explain the impairments.

  12. Accretion-induced spin-wandering effects on the neutron star in Scorpius X-1: Implications for continuous gravitational wave searches

    Science.gov (United States)

    Mukherjee, Arunava; Messenger, Chris; Riles, Keith

    2018-02-01

    The LIGO's discovery of binary black hole mergers has opened up a new era of transient gravitational wave astronomy. The potential detection of gravitational radiation from another class of astronomical objects, rapidly spinning nonaxisymmetric neutron stars, would constitute a new area of gravitational wave astronomy. Scorpius X-1 (Sco X-1) is one of the most promising sources of continuous gravitational radiation to be detected with present-generation ground-based gravitational wave detectors, such as Advanced LIGO and Advanced Virgo. As the sensitivity of these detectors improve in the coming years, so will power of the search algorithms being used to find gravitational wave signals. Those searches will still require integration over nearly year long observational spans to detect the incredibly weak signals from rotating neutron stars. For low mass X-ray binaries such as Sco X-1 this difficult task is compounded by neutron star "spin wandering" caused by stochastic accretion fluctuations. In this paper, we analyze X-ray data from the R X T E satellite to infer the fluctuating torque on the neutron star in Sco X-1. We then perform a large-scale simulation to quantify the statistical properties of spin-wandering effects on the gravitational wave signal frequency and phase evolution. We find that there are a broad range of expected maximum levels of frequency wandering corresponding to maximum drifts of between 0.3 - 50 μ Hz /sec over a year at 99% confidence. These results can be cast in terms of the maximum allowed length of a coherent signal model neglecting spin-wandering effects as ranging between 5-80 days. This study is designed to guide the development and evaluation of Sco X-1 search algorithms.

  13. Gravitational effects in field gravitation theory

    International Nuclear Information System (INIS)

    Denisov, V.I.; Logunov, A.A.; Mestvirishvili, M.A.; Vlasov, A.A.

    1979-01-01

    The possibilities to describe various gravitation effects of field gravitation theory (FGT) are considered. Past-Newtonian approximation of the FGT has been constructed and on the basis of this approximation it has been shown that the field theory allows one to describe the whole set of experimental facts. The comparison of post-Newtonian parameters in FGT with those in the Einstein's theory makes it clear that these two; theories are undistinguishable from the viewpoint of any experiments, realized with post-Newtonian accuracy. Gravitational field of an island type source with spherically symmetrical distribution of matter and unstationary homogeneous model of Universe, which allows to describe the effect of cosmological red shift, are considered

  14. Relativistic gravitation theory

    International Nuclear Information System (INIS)

    Logunov, A.A.; Mestvirishvili, M.A.

    1984-01-01

    On the basis of the special relativity and geometrization principle a relativistic gravitation theory (RGT) is unambiguously constructed with the help of a notion of a gravitational field as a physical field in Faraday-Maxwell spirit, which posesses energy momentum and spins 2 and 0. The source of gravitation field is a total conserved energy-momentum tensor for matter and for gravitation field in Minkowski space. In the RGT conservation laws for the energy momentum and angular momentum of matter and gravitational field hold rigorously. The theory explains the whole set of gravitation experiments. Here, due to the geometrization principle the Riemannian space is of a field origin since this space arises effectively as a result of the gravitation field origin since this space arises effectively as a result of the gravitation field action on the matter. The RGT astonishing prediction is that the Universe is not closed but ''flat''. It means that in the Universe there should exist a ''missing'' mass in some form of matter

  15. Those Elusive Gravitational Waves

    Science.gov (United States)

    MOSAIC, 1976

    1976-01-01

    The presence of gravitational waves was predicted by Einstein in his theory of General Relativity. Since then, scientists have been attempting to develop a detector sensitive enough to measure these cosmic signals. Once the presence of gravitational waves is confirmed, scientists can directly study star interiors, galaxy cores, or quasars. (MA)

  16. Gravitationally coupled electroweak monopole

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Y.M., E-mail: ymcho7@konkuk.ac.kr [Administration Building 310-4, Konkuk University, Seoul 143-701 (Korea, Republic of); School of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Kimm, Kyoungtae [Faculty of Liberal Education, Seoul National University, Seoul 151-747 (Korea, Republic of); Yoon, J.H. [Department of Physics, College of Natural Sciences, Konkuk University, Seoul 143-701 (Korea, Republic of)

    2016-10-10

    We present a family of gravitationally coupled electroweak monopole solutions in Einstein–Weinberg–Salam theory. Our result confirms the existence of globally regular gravitating electroweak monopole which changes to the magnetically charged black hole as the Higgs vacuum value approaches to the Planck scale. Moreover, our solutions could provide a more accurate description of the monopole stars and magnetically charged black holes.

  17. Physical processes of gravitions and gray quarks in the interior of cosomod and supergravity cosmic stellar entities

    International Nuclear Information System (INIS)

    Narayana, K.L.

    1986-01-01

    Supergravity theories indicate drastic modifications and entirely new thoughts of approach for study of the physical processes. In a separate paper, the author has emphasized the importance of SU(8) symmetric group within the frame work of a U(10,2) supergravity theory. This has also been cited in literature, subsequently, for a spinorial theoretic formulation of light and classification of photon and W-meson multiplets. The object of the present paper is to present an example of a specific gauge-gravity theory that employs SL(2,C) infinitesional group together with a SU(2) group. The reason of the choice is its close analogy with the Einstein's theory, that leads to automatically the important physical quantities. The difference, however, arises in a relevant version of quantized theory. At first, he emphasizes the basic structure of the model, discusses the symmetry breaking patterns which ensures ISL(2,C) X SU(2) as the low energy symmetry. He next points out the new interactions present in the extended framework and obtain the reasonable physical processes that may play an important role in the super gravity cosmic entities

  18. A gravitational entropy proposal

    International Nuclear Information System (INIS)

    Clifton, Timothy; Tavakol, Reza; Ellis, George F R

    2013-01-01

    We propose a thermodynamically motivated measure of gravitational entropy based on the Bel–Robinson tensor, which has a natural interpretation as the effective super-energy–momentum tensor of free gravitational fields. The specific form of this measure differs depending on whether the gravitational field is Coulomb-like or wave-like, and reduces to the Bekenstein–Hawking value when integrated over the interior of a Schwarzschild black hole. For scalar perturbations of a Robertson–Walker geometry we find that the entropy goes like the Hubble weighted anisotropy of the gravitational field, and therefore increases as structure formation occurs. This is in keeping with our expectations for the behaviour of gravitational entropy in cosmology, and provides a thermodynamically motivated arrow of time for cosmological solutions of Einstein’s field equations. It is also in keeping with Penrose’s Weyl curvature hypothesis. (paper)

  19. Gravitational, erosional and sedimentary processes on volcanic ocean islands: Insights from the submarine morphology of Madeira archipelago

    Science.gov (United States)

    Quartau, R.; Ramalho, R.; Madeira, J.; Santos, R.; Rodrigues, A.; Roque, C.; Carrara, G.; da Silveira, A. B.

    2017-12-01

    In this work we report detailed observations of high-resolution bathymetric and backscatter mosaics of Madeira archipelago covering from the nearshore to the deep sea and relate them with the physical and geological setting of the islands. Our observations reveal that the submarine flanks of the archipelago are deeply dissected by large landslide scars and that most of them have involved subaerial material. Below the shelf break, landslide chutes develop downslope forming poorly defined depositional lobes. Around the islands, a large tributary system composed of gullies and channels develop where no significant rocky/ridge outcrops are present. This system is likely formed by turbidity currents that are triggered by hyperpicnal flows in Madeira or by storm-induced offshore sediment transport on Porto Santo and Desertas islands. At the lower part of the flanks (-3000 to -4300 m), where seafloor gradients decrease to 0.5º-3º, several scour and sediment wave fields are present, with the former normally occurring upslope of the latter. Sediment waves are often associated with the depositional lobes of the landslides but also occur offshore poorly-developed tributary systems. Sediment wave fields and scours are mostly absent on areas where the tributary systems are well developed and/or are dominated by rocky outcrops. Our study suggests that scours and sediment wave fields are probably formed by turbidity currents that suffer hydraulic jumps where the seafloor gradients are significantly reduced and where the currents become unconfined. The largest scours were found in areas without upslope channel systems and independently of wave fields, although also related to unconfined turbidity currents. Our observations show that tributary systems are better developed in prominent and rainy islands such as Madeira. On low and dry islands such as Porto Santo and Desertas, these are poorly developed and unconfined turbidite currents favour the development of scours and sediment

  20. Thermal duality and gravitational collapse

    International Nuclear Information System (INIS)

    Hewitt, Michael

    2015-01-01

    Thermal duality is a relationship between the behaviour of heterotic string models of the E(8)×E(8) or SO(32) types at inversely related temperatures, a variant of T duality in the Euclidean regime. This duality would have consequences for the nature of the Hagedorn transition in these string models. We propose that the vacuum admits a family of deformations in situations where there are closed surfaces of constant area but high radial acceleration (a string regularized version of a Penrose trapped surface), such as would be formed in situations of extreme gravitational collapse. This would allow a radical resolution of the firewall paradox by allowing quantum effects to significantly modify the spacetime geometry around a collapsed object. A string bremsstrahlung process would convert the kinetic energy of infalling matter in extreme gravitational collapse to form a region of the deformed vacuum, which would be equivalent to forming a high temperature string phase. A heuristic criterion for the conversion process is presented, relating Newtonian gravity to the string tension, suggesting an upper limit to the strength of the gravitational interaction. This conversion process might have observable consequences for charged particles falling into a rotating collapsed object by producing high energy particles via a variant of the Penrose process. (paper)

  1. Mass splitting induced by gravitation

    International Nuclear Information System (INIS)

    Maia, M.D.

    1982-08-01

    The exact combination of internal and geometrical symmetries and the associated mass splitting problem is discussed. A 10-parameter geometrical symmetry is defined in a curved space-time in such a way that it is a combination of de Sitter groups. In the flat limit it reproduces the Poincare-group and its Lie algebra has a nilpotent action on the combined symmetry only in that limit. An explicit mass splitting expression is derived and an estimation of the order of magnitude for spin-zero mesons is made. (author)

  2. Particle production in a gravitational wave background

    Science.gov (United States)

    Jones, Preston; McDougall, Patrick; Singleton, Douglas

    2017-03-01

    We study the possibility that massless particles, such as photons, are produced by a gravitational wave. That such a process should occur is implied by tree-level Feynman diagrams such as two gravitons turning into two photons, i.e., g +g →γ +γ . Here we calculate the rate at which a gravitational wave creates a massless scalar field. This is done by placing the scalar field in the background of a plane gravitational wave and calculating the 4-current of the scalar field. Even in the vacuum limit of the scalar field it has a nonzero vacuum expectation value (similar to what occurs in the Higgs mechanism) and a nonzero current. We associate this with the production of scalar field quanta by the gravitational field. This effect has potential consequences for the attenuation of gravitational waves since the massless field is being produced at the expense of the gravitational field. This is related to the time-dependent Schwinger effect, but with the electric field replaced by the gravitational wave background and the electron/positron field quanta replaced by massless scalar "photons." Since the produced scalar quanta are massless there is no exponential suppression, as occurs in the Schwinger effect due to the electron mass.

  3. The radiation-induced fibroatrophic process: therapeutic perspective via the antioxidant pathway

    International Nuclear Information System (INIS)

    Delanian, Sylvie; Lefaix, Jean-Louis

    2004-01-01

    The radiation-induced fibroatrophic process (RIF) constitutes a late, local and unavoidable sequela to high-dose radiotherapy, traditionally considered irreversible. Today, this process is partly reversible, thanks to recent progress in understanding the physiopathology of the lesions it causes and the results of recent clinical trials using antioxidant therapy. This review includes a synthetic description of the static and dynamic features of the RIF process, as reflected by its clinical, instrumental and histopathological characteristics, and by its cellular and molecular regulation. Schematically, three successive clinical and histopathological phases can be distinguished: a pre-fibrotic aspecific inflammatory phase, a constitutive fibrotic cellular phase, and a matrix densification and remodelling phase, possibly ending in terminal tissular necrosis. The respective roles of the chief actors in the RIF process are defined, as well as their development with time. A fibroblastic stromal hypothesis is suggested revolving around a 'gravitational effect' exerted by the couple ROS (reactive oxygen species)--fibroblasts, and partly mediated by TGF-β1. A variety of strategies have been tested for the management of RIF. In the light of the mechanisms described, a curative procedure has been proposed via the antioxidant pathway. In particular, it was showed that superoxide dismutase and combined pentoxifylline-tocopherol treatment enables the process of established radiation-induced fibroatrophy to be greatly reduced or even reversed, both in clinical practice and animal experiments. The efficacy of combined pentoxifylline-tocopherol treatment in superficial RIF was confirmed in a randomised clinical trial, and then in successful phase II trials especially in uterine fibroatrophy and osteoradionecrosis. It is of critical importance to evaluate these new management approaches in larger clinical trials and to improve the recording of results for better outcome analysis

  4. The radiation-induced fibroatrophic process: therapeutic perspective via the antioxidant pathway.

    Science.gov (United States)

    Delanian, Sylvie; Lefaix, Jean-Louis

    2004-11-01

    The radiation-induced fibroatrophic process (RIF) constitutes a late, local and unavoidable sequela to high-dose radiotherapy, traditionally considered irreversible. Today, this process is partly reversible, thanks to recent progress in understanding the physiopathology of the lesions it causes and the results of recent clinical trials using antioxidant therapy. This review includes a synthetic description of the static and dynamic features of the RIF process, as reflected by its clinical, instrumental and histopathological characteristics, and by its cellular and molecular regulation. Schematically, three successive clinical and histopathological phases can be distinguished: a pre-fibrotic aspecific inflammatory phase, a constitutive fibrotic cellular phase, and a matrix densification and remodelling phase, possibly ending in terminal tissular necrosis. The respective roles of the chief actors in the RIF process are defined, as well as their development with time. A fibroblastic stromal hypothesis is suggested revolving around a 'gravitational effect' exerted by the couple ROS (reactive oxygen species)--fibroblasts, and partly mediated by TGF-beta1. A variety of strategies have been tested for the management of RIF. In the light of the mechanisms described, a curative procedure has been proposed via the antioxidant pathway. In particular, it was showed that superoxide dismutase and combined pentoxifylline-tocopherol treatment enables the process of established radiation-induced fibroatrophy to be greatly reduced or even reversed, both in clinical practice and animal experiments. The efficacy of combined pentoxifylline-tocopherol treatment in superficial RIF was confirmed in a randomised clinical trial, and then in successful phase II trials especially in uterine fibroatrophy and osteoradionecrosis. It is of critical importance to evaluate these new management approaches in larger clinical trials and to improve the recording of results for better outcome analysis

  5. Relativistic theory of gravitation

    International Nuclear Information System (INIS)

    Logunov, A.A.; Mestvirishvilli, M.A.

    1985-01-01

    In the present paper a relativistic theory of gravitation (RTG) is constructed in a unique way on the basis of the special relativity and geometrization principle. In this, a gravitational field is treated as the Faraday-Maxwell spin-2 and spin-0 physical field possessing energy and momentum. The source of a gravitational field is the total conserved energy-momentum tensor of matter and of a gravitational field in Minkowski space. In the RTG, the conservation laws are strictly fulfilled for the energy-momentum and for the angular momentum of matter and a gravitational field. The theory explains the whole available set of experiments on gravitation. In virtue of the geometrization principle, the Riemannian space in our theory is of field origin, since it appears as an effective force space due to the action of a gravitational field on matter. The RTg leads to an exceptionally strong prediction: The Universe is not closed but just ''flat''. This suggests that in the Universe a ''hidden mass'' should exist in some form of matter

  6. Gravitation and vacuum field

    International Nuclear Information System (INIS)

    Tevikyan, R.V.

    1986-01-01

    This paper presents equations that describe particles with spins s = 0, 1/2, 1 completely and which also describe 2s + 2 limiting fields as E → ∞. It is shown that the ordinary Hilbert-Einstein action for the gravitation field must be augmented by the action for the Bose vacuum field. This means that one must introduce in the gravitational equations a cosmological term proportional to the square of the strength of the Bose vacuum field. It is shown that the theory of gravitation describes three realities: matter, field, and vacuum field. A new form of matter--the vacuum field--is introduced into field theory

  7. Gravitational radiation reaction

    International Nuclear Information System (INIS)

    Tanaka, Takahiro

    2006-01-01

    We give a short personally-biased review on the recent progress in our understanding of gravitational radiation reaction acting on a point particle orbiting a black hole. The main motivation of this study is to obtain sufficiently precise gravitational waveforms from inspiraling binary compact starts with a large mass ratio. For this purpose, various new concepts and techniques have been developed to compute the orbital evolution taking into account the gravitational self-force. Combining these ideas with a few supplementary new ideas, we try to outline a path to our goal here. (author)

  8. Presenting Newtonian gravitation

    International Nuclear Information System (INIS)

    Counihan, Martin

    2007-01-01

    The basic principles of the Newtonian theory of gravitation are presented in a way which students may find more logically coherent, mathematically accessible and physically interesting than other approaches. After giving relatively simple derivations of the circular hodograph and the elliptical orbit from the inverse-square law, the concept of gravitational energy is developed from vector calculus. It is argued that the energy density of a gravitational field may reasonably be regarded as -g 2 /8πG, and that the inverse-square law may be replaced by a Schwarzschild-like force law without the need to invoke non-Euclidean geometry

  9. Relativistic Photon Induced Processes of Composite Particles

    International Nuclear Information System (INIS)

    Ribeiro-Silva, C.I; Curado, E. M. F.; Rego-Monteiro, M. A.

    2007-01-01

    We consider a complex quantum field theory based on a generalized Heisenberg[1] algebra, which describes at the space-time a spin less composite particle. We compute the perturbative series and the cross section of the scattering process 2 γ→φ - , φ + up to second order in the coupling constant and we find a further contribution due to the structure of the composite pion which is described here phenomenologically by the generalized algebra. We compare the results of this study with available experimental data. (Author)

  10. Gravitational Instabilities in Circumstellar Disks

    Science.gov (United States)

    Kratter, Kaitlin; Lodato, Giuseppe

    2016-09-01

    Star and planet formation are the complex outcomes of gravitational collapse and angular momentum transport mediated by protostellar and protoplanetary disks. In this review, we focus on the role of gravitational instability in this process. We begin with a brief overview of the observational evidence for massive disks that might be subject to gravitational instability and then highlight the diverse ways in which the instability manifests itself in protostellar and protoplanetary disks: the generation of spiral arms, small-scale turbulence-like density fluctuations, and fragmentation of the disk itself. We present the analytic theory that describes the linear growth phase of the instability supplemented with a survey of numerical simulations that aim to capture the nonlinear evolution. We emphasize the role of thermodynamics and large-scale infall in controlling the outcome of the instability. Despite apparent controversies in the literature, we show a remarkable level of agreement between analytic predictions and numerical results. In the next part of our review, we focus on the astrophysical consequences of the instability. We show that the disks most likely to be gravitationally unstable are young and relatively massive compared with their host star, Md/M*≥0.1. They will develop quasi-stable spiral arms that process infall from the background cloud. Although instability is less likely at later times, once infall becomes less important, the manifestations of the instability are more varied. In this regime, the disk thermodynamics, often regulated by stellar irradiation, dictates the development and evolution of the instability. In some cases the instability may lead to fragmentation into bound companions. These companions are more likely to be brown dwarfs or stars than planetary mass objects. Finally, we highlight open questions related to the development of a turbulent cascade in thin disks and the role of mode-mode coupling in setting the maximum angular

  11. Gravitation and source theory

    International Nuclear Information System (INIS)

    Yilmaz, H.

    1975-01-01

    Schwinger's source theory is applied to the problem of gravitation and its quantization. It is shown that within the framework of a flat-space the source theory implementation leads to a violation of probability. To avoid the difficulty one must introduce a curved space-time hence the source concept may be said to necessitate the transition to a curved-space theory of gravitation. It is further shown that the curved-space theory of gravitation implied by the source theory is not equivalent to the conventional Einstein theory. The source concept leads to a different theory where the gravitational field has a stress-energy tensor t/sup nu//sub mu/ which contributes to geometric curvatures

  12. Gravitational lensing of quasars

    CERN Document Server

    Eigenbrod, Alexander

    2013-01-01

    The universe, in all its richness, diversity and complexity, is populated by a myriad of intriguing celestial objects. Among the most exotic of them are gravitationally lensed quasars. A quasar is an extremely bright nucleus of a galaxy, and when such an object is gravitationally lensed, multiple images of the quasar are produced – this phenomenon of cosmic mirage can provide invaluable insights on burning questions, such as the nature of dark matter and dark energy. After presenting the basics of modern cosmology, the book describes active galactic nuclei, the theory of gravitational lensing, and presents a particular numerical technique to improve the resolution of astronomical data. The book then enters the heart of the subject with the description of important applications of gravitational lensing of quasars, such as the measurement of the famous Hubble constant, the determination of the dark matter distribution in galaxies, and the observation of the mysterious inner parts of quasars with much higher r...

  13. Gravitational Waves and Neutrinos

    OpenAIRE

    Sturani, Riccardo

    2018-01-01

    We give an overview about the recent detection of gravitational waves by the Advanced LIGO first and second observing runs and by Advanced Virgo, with emphasis on the prospects for multi-messenger astronomy involving neutrinos detections.

  14. Gravitational wave astronomy

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    In the past year, the LIGO-Virgo Collaboration announced the first secure detection of gravitational waves. This discovery heralds the beginning of gravitational wave astronomy: the use of gravitational waves as a tool for studying the dense and dynamical universe. In this talk, I will describe the full spectrum of gravitational waves, from Hubble-scale modes, through waves with periods of years, hours and milliseconds. I will describe the different techniques one uses to measure the waves in these bands, current and planned facilities for implementing these techniques, and the broad range of sources which produce the radiation. I will discuss what we might expect to learn as more events and sources are measured, and as this field matures into a standard part of the astronomical milieu.

  15. Radiation induced processes in moss cells

    International Nuclear Information System (INIS)

    Doehren, R. v.

    1975-01-01

    The moss F.h. shows apical growth in the protonema cells which spread radially from the spor. Every apical daughter cell during the state of 'Caulonema' and just before in the state of 'Caulonema Primanen' initiates cell division as soon as more than twice the length of the mother cell is reached. All this allows to follow radiation effects in single cells conveniently. UV irradiation on the range of 254 nm and 280 nm delivered at different parts of the cell area delays cell division markedly may suppress it, and is able to stop the process of growing in relation to the delivered dose and to the irradiated area as well. In case of irradiation of the area next to where the membrane is just being formed - that is to say next to the phragmoplast - the new membrane will be wrongly oriented. In particular giant cells are occurring in the case of nucleus irradiation during early prophase. (orig./GSE) [de

  16. Listening music of gravitation

    International Nuclear Information System (INIS)

    Anon.

    2001-01-01

    Achievements of precision experiments in Japan (TAMA project) and USA (LIGO Laboratory) in the field of registration of gravitation waves using interferometric gravitational wave detectors are described. Works of the GEO groups in Hannover (Germany) and Vigro (Italy) are noted. Interferometer operation in synchronization during 160 hours demonstrating viability of the technique and its reliability is recorded. Advances in the field of the data analysis with the aim of recording of cosmic signal from noise of the interferometer are noted [ru

  17. Bunge on gravitational waves

    OpenAIRE

    Romero, Gustavo E.

    2017-01-01

    I discuss the recent claims made by Mario Bunge on the philosophical implications of the discovery of gravitational waves. I think that Bunge is right when he points out that the detection implies the materiality of spacetime, but I reject his identification of spacetime with the gravitational field. I show that Bunge's analysis of the spacetime inside a hollow sphere is defective, but this in no way affects his main claim.

  18. Gravitation and Electricity

    Directory of Open Access Journals (Sweden)

    Stavroulakis N.

    2008-04-01

    Full Text Available The equations of gravitation together with the equations of electromagnetism in terms of the General Theory of Relativity allow to conceive an interdependence between the gravitational field and the electromagnetic field. However the technical difficulties of the relevant problems have precluded from expressing clearly this interdependence. Even the simple problem related to the field generated by a charged spherical mass is not correctly solved. In the present paper we reexamine from the outset this problem and propose a new solution.

  19. Gravitationally confined relativistic neutrinos

    Science.gov (United States)

    Vayenas, C. G.; Fokas, A. S.; Grigoriou, D.

    2017-09-01

    Combining special relativity, the equivalence principle, and Newton’s universal gravitational law with gravitational rather than rest masses, one finds that gravitational interactions between relativistic neutrinos with kinetic energies above 50 MeV are very strong and can lead to the formation of gravitationally confined composite structures with the mass and other properties of hadrons. One may model such structures by considering three neutrinos moving symmetrically on a circular orbit under the influence of their gravitational attraction, and by assuming quantization of their angular momentum, as in the Bohr model of the H atom. The model contains no adjustable parameters and its solution, using a neutrino rest mass of 0.05 eV/c2, leads to composite state radii close to 1 fm and composite state masses close to 1 GeV/c2. Similar models of relativistic rotating electron - neutrino pairs give a mass of 81 GeV/c2, close to that of W bosons. This novel mechanism of generating mass suggests that the Higgs mass generation mechanism can be modeled as a latent gravitational field which gets activated by relativistic neutrinos.

  20. Relativistic theory of gravitation

    International Nuclear Information System (INIS)

    Logunov, A.A.; Mestvirishvili, M.A.

    1986-01-01

    In the present paper a relativistic theory of gravitation (RTG) is unambiguously constructed on the basis of the special relativity and geometrization principle. In this a gravitational field is treated as the Faraday--Maxwell spin-2 and spin-0 physical field possessing energy and momentum. The source of a gravitational field is the total conserved energy-momentum tensor of matter and of a gravitational field in Minkowski space. In the RTG the conservation laws are strictly fulfilled for the energy-moment and for the angular momentum of matter and a gravitational field. The theory explains the whole available set of experiments on gravity. By virtue of the geometrization principle, the Riemannian space in our theory is of field origin, since it appears as an effective force space due to the action of a gravitational field on matter. The RTG leads to an exceptionally strong prediction: The universe is not closed but just ''flat.'' This suggests that in the universe a ''missing mass'' should exist in a form of matter

  1. Process-induced compositional changes of flaxseed.

    Science.gov (United States)

    Wanasundara, P K; Shahidi, F

    1998-01-01

    Flaxseed has been used as an edible grain in different parts of the world since ancient times. However, use of flaxseed oil has been limited due to its high content of polyunsaturated fatty acids. Nonetheless, alpha-linolenic acid, dietary fiber and lignans of flaxseed have regained attention. New varieties of flaxseed containing low levels of alpha-linolenic acid are available for edible oil extraction. Use of whole flaxseed in foods provides a means to utilise all of its nutrients and require minimum processing steps. However, the presence of cyanogenic glucosides and diglucosides in the seeds is a concern as they may release cyanide upon hydrolysis. In addition, the polyunsaturated fatty acids may undergo thermal or autooxidation when exposed to air or high temperatures that are used in food preparation. Studies todate on oxidation products of intact flaxseed lipids have not shown any harmful effects when flaxseed is included, up to 28%, in the baked products. Furthermore, cyanide levels produced as a result of autolysis are below the harmful limits to humans. However, the meals left after oil extraction require detoxification but, by solvent extraction, to reduce the harmful effects of cyanide when used in animal rations. Flaxseed meal is a good source of proteins; these could be isolated by complexation with sodium hexametaphosphate without changing their nutritional value or composition. In addition, the effect of germination on proteins, lipids, cyanogenic glycosides, and other minor constituents of flaxseed is discussed.

  2. Leading gravitational corrections and a unified universe

    DEFF Research Database (Denmark)

    Codello, Alessandro; Jain, Rajeev Kumar

    2016-01-01

    Leading order gravitational corrections to the Einstein-Hilbert action can lead to a consistent picture of the universe by unifying the epochs of inflation and dark energy in a single framework. While the leading local correction induces an inflationary phase in the early universe, the leading...... nonlocal term leads to an accelerated expansion of the universe at the present epoch. We argue that both the leading UV and IR terms can be obtained within the framework of a covariant effective field theory of gravity. The perturbative gravitational corrections therefore provide a fundamental basis...

  3. An experimental facility for microwave induced plasma processing of materials

    International Nuclear Information System (INIS)

    Patil, D.S.; Ramachandran, K.; Bhide, A.L.; Venkatramani, N.

    1997-01-01

    Microwave induced plasma processing offers many advantages over conventional processes. However this technology is in the development stage. This report gives a detailed information about a microwave plasma processing facility (2.45 GHz, 700 W) set up in the Laser and Plasma Technology Division. The equipment details and the results obtained on deposition of diamond like carbon (DLC) thin films and surface modification of polymer PET (polyethylene terephthalate) using this facility are given in this report. (author)

  4. Electromagnetic waves in gravitational wave spacetimes

    International Nuclear Information System (INIS)

    Haney, M.; Bini, D.; Ortolan, A.; Fortini, P.

    2013-01-01

    We have considered the propagation of electromagnetic waves in a space-time representing an exact gravitational plane wave and calculated the induced changes on the four-potential field Aμ of a plane electromagnetic wave. By choosing a suitable photon round-trip in a Michelson interferometer, we have been able to identify the physical effects of the exact gravitational wave on the electromagnetic field, i.e. phase shift, change of the polarization vector, angular deflection and delay. These results have been exploited to study the response of an interferometric gravitational wave detector beyond the linear approximation of the general theory of relativity. A much more detailed examination of this problem can be found in our paper recently published in Classical and Quantum Gravity (28 (2011) 235007).

  5. Gravitational waves and antennas

    CERN Multimedia

    CERN. Geneva

    2003-01-01

    Gravitational waves and their detection represent today a hot topic, which promises to play a central role in astrophysics, cosmology and theoretical physics. Technological developments have enabled the construction of such sensitive detectors that the detection of gravitational radiation and the start of a new astronomy could become a reality during the next few years. This is expected to bring a revolution in our knowledge of the universe by allowing the observation of hiterto unseen phenomena such as coalescence of compact objects (neutron stars and black holes) fall of stars into supermassive black holes, stellar core collapses, big bang relics and the new and unexpected. In these lectures I give a brief overview of this challenging field of modern physics. Topics : Basic properties of gravitational radiation. Astrophysical sources. Principle of operation of detectors. Interferometers (both ground based and space-based), bars and spheres. Present status of the experiments, their recent results and their f...

  6. Gravitation and spacetime

    CERN Document Server

    Ohanian, Hans C

    2013-01-01

    The third edition of this classic textbook is a quantitative introduction for advanced undergraduates and graduate students. It gently guides students from Newton's gravitational theory to special relativity, and then to the relativistic theory of gravitation. General relativity is approached from several perspectives: as a theory constructed by analogy with Maxwell's electrodynamics, as a relativistic generalization of Newton's theory, and as a theory of curved spacetime. The authors provide a concise overview of the important concepts and formulas, coupled with the experimental results underpinning the latest research in the field. Numerous exercises in Newtonian gravitational theory and Maxwell's equations help students master essential concepts for advanced work in general relativity, while detailed spacetime diagrams encourage them to think in terms of four-dimensional geometry. Featuring comprehensive reviews of recent experimental and observational data, the text concludes with chapters on cosmology an...

  7. Problems of generation and reception of gravitational waves

    International Nuclear Information System (INIS)

    Pisarev, A.F.

    1975-01-01

    The present day status of the problems of gravitation, wave radiation and reception is surveyed. The physical presentation and mathematical description of the processes of radiation, propagation and interaction of gravitation waves with matter and the electromagnetic field are given. The experiments on the search for gravitation waves of astophysical nature are analysed. The laboratory and cosmic sources of these waves and the methods of their reception are described. Special attention is drawn to the analysis of the proposals to perform a complete laboratory gravitation wave experiment

  8. Problems of generation and reception of gravitational waves. [Review

    Energy Technology Data Exchange (ETDEWEB)

    Pisarev, A F [Joint Inst. for Nuclear Research, Dubna (USSR)

    1975-01-01

    The present day status of the problems of gravitation, wave radiation and reception is surveyed. The physical presentation and mathematical description of the processes of radiation, propagation and interaction of gravitation waves with matter and the electromagnetic field are given. The experiments on the search for gravitation waves of astophysical nature are analysed. The laboratory and cosmic sources of these waves and the methods of their reception are described. Special attention is drawn to the analysis of the proposals to perform a complete laboratory gravitation wave experiment.

  9. Gravitational-Wave Astronomy

    Science.gov (United States)

    Kelly, Bernard J.

    2010-01-01

    Einstein's General Theory of Relativity is our best classical description of gravity, and informs modern astronomy and astrophysics at all scales: stellar, galactic, and cosmological. Among its surprising predictions is the existence of gravitational waves -- ripples in space-time that carry energy and momentum away from strongly interacting gravitating sources. In my talk, I will give an overview of the properties of this radiation, recent breakthroughs in computational physics allowing us to calculate the waveforms from galactic mergers, and the prospect of direct observation with interferometric detectors such as LIGO and LISA.

  10. Moduli destabilization via gravitational collapse

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Dong-il [Sogang Univ., Seoul (Korea, Republic of). Center for Quantum Spacetime; Pedro, Francisco G. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany). Theory Group; Yeom, Dong-han [Sogang Univ., Seoul (Korea, Republic of). Center for Quantum Spacetime; Kyoto Univ. (Japan). Yukawa Inst. for Theoretical Physics

    2013-06-15

    We examine the interplay between gravitational collapse and moduli stability in the context of black hole formation. We perform numerical simulations of the collapse using the double null formalism and show that the very dense regions one expects to find in the process of black hole formation are able to destabilize the volume modulus. We establish that the effects of the destabilization will be visible to an observer at infinity, opening up a window to a region in spacetime where standard model's couplings and masses can differ significantly from their background values.

  11. Einstein-Rosen gravitational waves

    International Nuclear Information System (INIS)

    Astefanoaei, Iordana; Maftei, Gh.

    2001-01-01

    In this paper we analyse the behaviour of the gravitational waves in the approximation of the far matter fields, considering the indirect interaction between the matter sources and the gravitational field, in a cosmological model based on the Einstein-Rosen solution, Because the properties of the gravitational waves obtained as the solutions of Einstein fields equations (the gravitational field equations) are most obvious in the weak gravitational fields we consider here, the gravitational field in the linear approximation. Using the Newman-Penrose formalism, we calculate in the null-tetradic base (e a ), the spin coefficients, the directional derivates and the tetradic components of Ricci and Weyl tensors. From the Einstein field equations we obtained the solution for b(z, t) what described the behaviour of gravitational wave in Einstein-Rosen Universe and in the particular case, when t → ∞, p(z, t) leads us to the primordial gravitational waves in the Einstein-Rosen Universe. (authors)

  12. Gravitational Waves: The Evidence Mounts

    Science.gov (United States)

    Wick, Gerald L.

    1970-01-01

    Reviews the work of Weber and his colleagues in their attempts at detecting extraterrestial gravitational waves. Coincidence events recorded by special detectors provide the evidence for the existence of gravitational waves. Bibliography. (LC)

  13. Membrane formation : diffusion induced demixing processes in ternary polymeric systems

    NARCIS (Netherlands)

    Reuvers, Albertus Johannes

    1987-01-01

    In this thesis the mechanism of membrane formation by means of immersion precipitation is studied. Immersion of a concentrated polymer solution film into a nonsolvent bath induces an exchange of solvent and nonsolvent in the film by means of diffusion. This process results in an asymmetric polymer

  14. Induced Current Characteristics Due to Laser Induced Plasma and Its Application to Laser Processing Monitoring

    International Nuclear Information System (INIS)

    Madjid, Syahrun Nur; Idris, Nasrullah; Kurniawan, Koo Hendrik; Kagawa, Kiichiro

    2011-01-01

    In laser processing, suitable conditions for laser and gas play important role in ensuring a high quality of processing. To determine suitable conditions, we employed the electromagnetic phenomena associated with laser plasma generation. An electrode circuit was utilised to detect induced current due to the fast electrons propelled from the material during laser material processing. The characteristics of induced current were examined by changing parameters such as supplied voltage, laser pulse energy, number of laser shots, and type of ambient gas. These characteristics were compared with the optical emission characteristics. It was shown that the induced current technique proposed in this study is much more sensitive than the optical method in monitoring laser processing, that is to determine the precise focusing condition, and to accurately determine the moment of completion of laser beam penetration. In this study it was also shown that the induced current technique induced by CW CO 2 laser can be applied in industrial material processing for monitoring the penetration completion in a stainless steel plate drilling process.

  15. Curvature bound from gravitational catalysis

    Science.gov (United States)

    Gies, Holger; Martini, Riccardo

    2018-04-01

    We determine bounds on the curvature of local patches of spacetime from the requirement of intact long-range chiral symmetry. The bounds arise from a scale-dependent analysis of gravitational catalysis and its influence on the effective potential for the chiral order parameter, as induced by fermionic fluctuations on a curved spacetime with local hyperbolic properties. The bound is expressed in terms of the local curvature scalar measured in units of a gauge-invariant coarse-graining scale. We argue that any effective field theory of quantum gravity obeying this curvature bound is safe from chiral symmetry breaking through gravitational catalysis and thus compatible with the simultaneous existence of chiral fermions in the low-energy spectrum. With increasing number of dimensions, the curvature bound in terms of the hyperbolic scale parameter becomes stronger. Applying the curvature bound to the asymptotic safety scenario for quantum gravity in four spacetime dimensions translates into bounds on the matter content of particle physics models.

  16. Process induced poling and plasma induced damage of thin films PZT

    NARCIS (Netherlands)

    Wang, J.; Houwman, Evert Pieter; Salm, Cora; Nguyen, Duc Minh; Vergeer, Kurt; Schmitz, Jurriaan

    2017-01-01

    This paper treats processing sequence induced changes on PZT. Two kinds of metal-PZT-metal capacitors are compared. The top surface and sidewall of PZT in one kind of capacitor is directly bombarded by energetic particles during ion milling process, whereas PZT in the other kind of capacitor is not.

  17. Gravitation radiation observations

    OpenAIRE

    Glass, E. N.

    2017-01-01

    The notion of gravitational radiation begins with electromagnetic radiation. In 1887 Heinrich Hertz, working in one room, generated and received electromagnetic radiation. Maxwell's equations describe the electromagnetic field. The quanta of electromagnetic radiation are spin 1 photons. They are fundamental to atomic physics and quantum electrodynamics.

  18. Alternative equations of gravitation

    International Nuclear Information System (INIS)

    Pinto Neto, N.

    1983-01-01

    It is shown, trough a new formalism, that the quantum fluctuation effects of the gravitational field in Einstein's equations are analogs to the effects of a continuum medium in Maxwell's Electrodynamics. Following, a real example of the applications of these equations is studied. Qunatum fluctuations effects as perturbation sources in Minkowski and Friedmann Universes are examined. (L.C.) [pt

  19. Glitches and gravitational waves

    Indian Academy of Sciences (India)

    A M Srivastava

    2017-10-09

    Oct 9, 2017 ... We also discuss gravitational wave production due to rapidly changing ... efficient source of energy loss during the cooling of the neutron star. ..... [3] U S Gupta, R K Mohapatra, A M Srivastava and V K. Tiwari, Phys. Rev. D 82 ...

  20. Extragalactic Gravitational Collapse

    Science.gov (United States)

    Rees, Martin J.

    After some introductory "numerology", routes towards black hole formation are briefly reviewed; some properties of black holes relevant to theories for active galactic nuclei are then described. Applications are considered to specific models for energy generation and the production of relativistic beams. The paper concludes with a discussion of extragalactic sources of gravitational waves.

  1. Gravitational-Wave Astronomy

    Indian Academy of Sciences (India)

    Keywords. General relativity; gravitational waves; astrophysics; interferometry. Author Affiliations. P Ajith1 K G Arun2. LIGO Laboratory and Theoretical Astrophysics California Institute of Technology MS 18-34, Pasadena CA 91125, USA. Chennai Mathematical Institute Plot H1, SIPCOT IT Park Siruseri, Padur Post Chennai ...

  2. Gauge theory and gravitation

    International Nuclear Information System (INIS)

    Kikkawa, Keiji; Nakanishi, Noboru; Nariai, Hidekazu

    1983-01-01

    These proceedings contain the articles presented at the named symposium. They deal with geometrical aspects of gauge theory and gravitation, special problems in gauge theories, quantum field theory in curved space-time, quantum gravity, supersymmetry including supergravity, and grand unification. See hints under the relevant topics. (HSI)

  3. A new theory of space-time and gravitation

    International Nuclear Information System (INIS)

    Denisov, V.I.; Logunov, A.A.

    1982-01-01

    Field theory of gravitation is constructed. It uses a symmetrical second rank tensor field in pseudoeuclidean space-time for describing the gravitational field. The theory is based on the condition of the presence of conservation laws for gravitational field and matter taken together and on the geometrization principle. The field theory of gravitation has the same post-newtonian parame-- ters as the general relativity theory (GRT) which implies that both theories are indistinguishable from the viewpoint of any post- newtonian experiment. The description of the effects in strong gravitational fields as well as properties of gravitational waves in the field theory of gravitation and GRT differ significantly from each other. The distinctions between two theories include also the itational red shifti curving of light trajectories and timabsence in the field theory of gravitation of the effects of grav.. delay/ in processes of propagation of gravitational waves in external fields. These distinctions made it possible to suggest a number of experiments with gravitational waves in which the predictions of the field theory of gravitation can be compared with those of the GRT. Model of the Universe in the field theory of gravitation makes it possible to describe the cosmological red shift of the frequency. Character of the evolution in this mode is determined by the delay parameter q 0 : at q 0 0 >4-3/2xα the ''expansion'' at some moment will ''change'' to contraction'' and the Universe will return to the singular state, where α=8πepsilon 0 /3M 2 (H is the Hubble constant) [ru

  4. Gravitational waves from self-ordering scalar fields

    International Nuclear Information System (INIS)

    Fenu, Elisa; Durrer, Ruth; Figueroa, Daniel G.; García-Bellido, Juan

    2009-01-01

    Gravitational waves were copiously produced in the early Universe whenever the processes taking place were sufficiently violent. The spectra of several of these gravitational wave backgrounds on subhorizon scales have been extensively studied in the literature. In this paper we analyze the shape and amplitude of the gravitational wave spectrum on scales which are superhorizon at the time of production. Such gravitational waves are expected from the self ordering of randomly oriented scalar fields which can be present during a thermal phase transition or during preheating after hybrid inflation. We find that, if the gravitational wave source acts only during a small fraction of the Hubble time, the gravitational wave spectrum at frequencies lower than the expansion rate at the time of production behaves as Ω GW (f) ∝ f 3 with an amplitude much too small to be observable by gravitational wave observatories like LIGO, LISA or BBO. On the other hand, if the source is active for a much longer time, until a given mode which is initially superhorizon (kη * 1, we find that the gravitational wave energy density is frequency independent, i.e. scale invariant. Moreover, its amplitude for a GUT scale scenario turns out to be within the range and sensitivity of BBO and marginally detectable by LIGO and LISA. This new gravitational wave background can compete with the one generated during inflation, and distinguishing both may require extra information

  5. Gravitational waves from axion monodromy

    Energy Technology Data Exchange (ETDEWEB)

    Hebecker, Arthur; Jaeckel, Joerg; Rompineve, Fabrizio; Witkowski, Lukas T. [Institute for Theoretical Physics, University of Heidelberg,Philosophenweg 19, 69120 Heidelberg (Germany)

    2016-11-02

    Large field inflation is arguably the simplest and most natural variant of slow-roll inflation. Axion monodromy may be the most promising framework for realising this scenario. As one of its defining features, the long-range polynomial potential possesses short-range, instantonic modulations. These can give rise to a series of local minima in the post-inflationary region of the potential. We show that for certain parameter choices the inflaton populates more than one of these vacua inside a single Hubble patch. This corresponds to a dynamical phase decomposition, analogously to what happens in the course of thermal first-order phase transitions. In the subsequent process of bubble wall collisions, the lowest-lying axionic minimum eventually takes over all space. Our main result is that this violent process sources gravitational waves, very much like in the case of a first-order phase transition. We compute the energy density and peak frequency of the signal, which can lie anywhere in the mHz-GHz range, possibly within reach of next-generation interferometers. We also note that this “dynamical phase decomposition' phenomenon and its gravitational wave signal are more general and may apply to other inflationary or reheating scenarios with axions and modulated potentials.

  6. Gravitational waves from cosmic bubble collisions

    International Nuclear Information System (INIS)

    Kim, Dong-Hoon; Lee, Bum-Hoon; Lee, Wonwoo; Yang, Jongmann; Yeom, Dong-han

    2015-01-01

    Cosmic bubbles are nucleated through the quantum tunneling process. After nucleation they would expand and undergo collisions with each other. In this paper, we focus in particular on collisions of two equal-sized bubbles and compute gravitational waves emitted from the collisions. First, we study the mechanism of the collisions by means of a real scalar field and its quartic potential. Then, using this model, we compute gravitational waves from the collisions in a straightforward manner. In the quadrupole approximation, time-domain gravitational waveforms are directly obtained by integrating the energy-momentum tensors over the volume of the wave sources, where the energy-momentum tensors are expressed in terms of the scalar field, the local geometry and the potential. We present gravitational waveforms emitted during (i) the initial-to-intermediate stage of strong collisions and (ii) the final stage of weak collisions: the former is obtained numerically, in full General Relativity and the latter analytically, in the flat spacetime approximation. We gain qualitative insights into the time-domain gravitational waveforms from bubble collisions: during (i), the waveforms show the non-linearity of the collisions, characterized by a modulating frequency and cusp-like bumps, whereas during (ii), the waveforms exhibit the linearity of the collisions, featured by smooth monochromatic oscillations. (orig.)

  7. GLINT. Gravitational-wave laser INterferometry triangle

    Science.gov (United States)

    Aria, Shafa; Azevedo, Rui; Burow, Rick; Cahill, Fiachra; Ducheckova, Lada; Holroyd, Alexa; Huarcaya, Victor; Järvelä, Emilia; Koßagk, Martin; Moeckel, Chris; Rodriguez, Ana; Royer, Fabien; Sypniewski, Richard; Vittori, Edoardo; Yttergren, Madeleine

    2017-11-01

    When the universe was roughly one billion years old, supermassive black holes (103-106 solar masses) already existed. The occurrence of supermassive black holes on such short time scales are poorly understood in terms of their physical or evolutionary processes. Our current understanding is limited by the lack of observational data due the limits of electromagnetic radiation. Gravitational waves as predicted by the theory of general relativity have provided us with the means to probe deeper into the history of the universe. During the ESA Alpach Summer School of 2015, a group of science and engineering students devised GLINT (Gravitational-wave Laser INterferometry Triangle), a space mission concept capable of measuring gravitational waves emitted by black holes that have formed at the early periods after the big bang. Morespecifically at redshifts of 15 big bang) in the frequency range 0.01 - 1 Hz. GLINT design strain sensitivity of 5× 10^{-24} 1/√ { {Hz}} will theoretically allow the study of early black holes formations as well as merging events and collapses. The laser interferometry, the technology used for measuring gravitational waves, monitors the separation of test masses in free-fall, where a change of separation indicates the passage of a gravitational wave. The test masses will be shielded from disturbing forces in a constellation of three geocentric orbiting satellites.

  8. Projective relativity, cosmology and gravitation

    International Nuclear Information System (INIS)

    Arcidiacono, G.

    1986-01-01

    This book describes the latest applications of projective geometry to cosmology and gravitation. The contents of the book are; the Poincare group and Special Relativity, the thermodynamics and electromagnetism, general relativity, gravitation and cosmology, group theory and models of universe, the special projective relativity, the Fantappie group and Big-Bang cosmology, a new cosmological projective mechanics, the plasma physics and cosmology, the projective magnetohydrodynamics field, projective relativity and waves propagation, the generalizations of the gravitational field, the general projective relativity, the projective gravitational field, the De Sitter Universe and quantum physics, the conformal relativity and Newton gravitation

  9. Neutron stars, magnetic fields, and gravitational waves

    International Nuclear Information System (INIS)

    Lamb, F.K.

    2001-01-01

    The r-modes of rapidly spinning young neutron stars have recently attracted attention as a promising source of detectable gravitational radiation. These neutron stars are expected to have magnetic fields ∼ 10 12 G. The r-mode velocity perturbation causes differential motion of the fluid in the star; this is a kinematic effect. In addition, the radiation-reaction associated with emission of gravitational radiation by r-waves drives additional differential fluid motions; this is a dynamic effect. These differential fluid motions distort the magnetic fields of neutron stars and may therefore play an important role in determining the structure of neutron star magnetic fields. If the stellar field is ∼ 10 16 (Ω/Ω B ) G or stronger, the usual r-modes are no longer normal modes of the star; here Ω and Ω B are the angular velocities of the star and at which mass shedding occurs. Much weaker magnetic fields can prevent gravitational radiation from amplifying the r-modes or damp existing r-mode oscillations on a relatively short timescale by extracting energy from the modes faster than gravitational wave emission can pump energy into them. The onset of proton superconductivity in the cores of newly formed magnetic neutron stars typically increases the effect on the r-modes of the magnetic field in the core by many orders of magnitude. Once the core has become superconducting, magnetic fields of the order of 10 12 G or greater are usually sufficient to damp r-modes that have been excited by emission of gravitational radiation and to suppress any further emission. A rapid drop in the strength of r-mode gravitational radiation from young neutron stars may therefore signal the onset of superconductivity in the core and provide a lower bound on the strength of the magnetic field there. Hence, measurements of r-mode gravitational waves from newly formed neutron stars may provide valuable diagnostic information about magnetic field strengths, cooling processes, and the

  10. Processed coffee alleviates DSS-induced colitis in mice

    Directory of Open Access Journals (Sweden)

    Bernd L. Fiebich

    2013-05-01

    Full Text Available ABSTRACTBackground: Coffee is one of the most widely consumed beverages in the world and it has been demonstrated that it has important therapeutic activities not only because of its caffeine content but also owing to the presence of other biologically active small molecules such as chlorogenic acid, trigonelline and cyclopentadiones. However, chlorogenic acid is degraded into catechol, pyrogallol and hydroxyhydroquinone, which are thought to induce irritation of the gastric mucosa. To reduce the content of irritant compounds processing methods have been developed prior to roasting the coffee beans.Objectives: The aim of this study was to study the anti-inflammatory and gastro-protective effects of processed coffee (Idee-Kaffee on in LPS-treated human primary monocytes and in a murine model of colon inflammation (IBD model.Results: In this study we have analyzed the effects on inflammatory events in cultured cells and in mice drinking a commercially available processed coffee. The processed coffee inhibited lipopolysaccharide (LPS-induced proinflammatory cytokines such as interleukin (IL-1, tumor necrosis factor (TNF, IL-6 and IL-8, and other inflammatory mediators such as prostaglandin (PGE2 and 8-isoprostane in cultured human primary monocytes. Oral administration of dissolved processed coffee, i.e., in its usual beverage form, improved greatly the adverse macroscopic and histological features of dextran sodium sulfate (DSS-induced colitis in mice in a dose-dependent manner. Processed coffee not only largely prevented DSS-induced colitis but also dramatically suppressed in vivo NF-B and STAT3 activities through inhibition of IB and STAT3 phosphorylation. Furthermore, this solubleFunctional Foods in Health and Disease 2013; 3(5:133-145coffee bean extract reduced the expression of proinflammatory cytokines TNF, IL-11, and IL-6 and the expression of cyclooxygenase (COX-2 in colonic tissues.Conclusions: This work identified

  11. Damage-induced DNA repair processes in Escherichia coli cells

    International Nuclear Information System (INIS)

    Slezarikova, V.

    1986-01-01

    The existing knowledge is summed up of the response of Escherichia coli cells to DNA damage due to various factors including ultraviolet radiation. So far, three inducible mechanisms caused by DNA damage are known, viz., SOS induction, adaptation and thermal shock induction. Greatest attention is devoted to SOS induction. Its mechanism is described and the importance of the lexA recA proteins is shown. In addition, direct or indirect role is played by other proteins, such as the ssb protein binding the single-strand DNA sections. The results are reported of a study of induced repair processes in Escherichia coli cells repeatedly irradiated with UV radiation. A model of induction by repeated cell irradiation discovered a new role of induced proteins, i.e., the elimination of alkali-labile points in the daughter DNA synthetized on a damaged model. The nature of the alkali-labile points has so far been unclear. In the adaptation process, regulation proteins are synthetized whose production is induced by the presence of alkylation agents. In the thermal shock induction, new proteins synthetize in cells, whose function has not yet been clarified. (E.S.)

  12. Processed Aloe vera Gel Ameliorates Cyclophosphamide-Induced Immunotoxicity

    Directory of Open Access Journals (Sweden)

    Sun-A Im

    2014-10-01

    Full Text Available The effects of processed Aloe vera gel (PAG on cyclophosphamide (CP-induced immunotoxicity were examined in mice. Intraperitoneal injection of CP significantly reduced the total number of lymphocytes and erythrocytes in the blood. Oral administration of PAG quickly restored CP-induced lymphopenia and erythropenia in a dose-dependent manner. The reversal of CP-induced hematotoxicity by PAG was mediated by the functional preservation of Peyer’s patch cells. Peyer’s patch cells isolated from CP-treated mice, which were administered PAG, produced higher levels of T helper 1 cytokines and colony-stimulating factors (CSF in response to concanavalin A stimulation as compared with those isolated from CP-treated control mice. PAG-derived polysaccharides directly activated Peyer’s patch cells isolated from normal mice to produce cytokines including interleukin (IL-6, IL-12, interferon-γ, granulocyte-CSF, and granulocyte-macrophage-CSF. The cytokines produced by polysaccharide-stimulated Peyer’s patch cells had potent proliferation-inducing activity on mouse bone marrow cells. In addition, oral administration of PAG restored IgA secretion in the intestine after CP treatment. These results indicated that PAG could be an effective immunomodulator and that it could prevent CP-induced immunotoxic side effects.

  13. The notions of mass in gravitational and particle physics

    Science.gov (United States)

    Castellani, Gianluca

    It is presently thought that the mass of all of the elementary particles is determined by the Higgs field. This scalar field couples directly into the trace of the energy momentum tensor of the elementary particles. The attraction between two or more masses arises from the exchange of gravitational quantum particles of spin 2, called gravitons. The gravitational field couples directly into the energy momentum tensor. Then there is a close connection between the Higgs field, that originates the mass, and the gravitational field that dictates how the masses interact. Our purpose in this thesis is to discuss this close connection in terms of fundamental definitions of inertial and gravitational masses. On a practical level we explore two properties of mass from the viewpoint of coupling into the Higgs field: (i) The coupling of the both the Higgs and gravity to the energy-pressure tensor allows for the decay of the Higgs particle into two gravitons. We use the self energy part of the Higgs propagator to calculate the electromagnetic, weak, fermionic and gravitational decay rate of the Higgs particle. We show that the former process appears to dominate the other decay modes. Since the gravitons are detectable with virtually zero probability, the number of Higgs particles with observable decay products will be much less than previously expected. (ii) Some new experimental results seem to indicate that the mass of the heavy elementary particles like the Z,W+,W- and especially the top quark, depends on the particle environment in which these particles are produced. The presence of a Higgs field due to neighboring particles could be responsible for induced mass shifts. Further measurements of mass shift effects might give an indirect proof of the Higgs particle. Such can be in principle done by re-analyzing some of the production data e +e- → ZZ (or W+W-) already collected at the LEP experiment. About the physical property of the top quark, it is too early to arrive at

  14. Regular cell design approach considering lithography-induced process variations

    OpenAIRE

    Gómez Fernández, Sergio

    2014-01-01

    The deployment delays for EUVL, forces IC design to continue using 193nm wavelength lithography with innovative and costly techniques in order to faithfully print sub-wavelength features and combat lithography induced process variations. The effect of the lithography gap in current and upcoming technologies is to cause severe distortions due to optical diffraction in the printed patterns and thus degrading manufacturing yield. Therefore, a paradigm shift in layout design is mandatory towards ...

  15. Global gravitational anomalies

    International Nuclear Information System (INIS)

    Witten, E.

    1985-01-01

    A general formula for global gauge and gravitational anomalies is derived. It is used to show that the anomaly free supergravity and superstring theories in ten dimensions are all free of global anomalies that might have ruined their consistency. However, it is shown that global anomalies lead to some restrictions on allowed compactifications of these theories. For example, in the case of O(32) superstring theory, it is shown that a global anomaly related to π 7 (O(32)) leads to a Dirac-like quantization condition for the field strength of the antisymmetric tensor field. Related to global anomalies is the question of the number of fermion zero modes in an instanton field. It is argued that the relevant gravitational instantons are exotic spheres. It is shown that the number of fermion zero modes in an instanton field is always even in ten dimensional supergravity. (orig.)

  16. Gravitational properties of antimatter

    International Nuclear Information System (INIS)

    Goldman, T.; Nieto, M.M.

    1985-01-01

    Quantum gravity is at the forefront of modern particle physics, yet there are no direct tests, for antimatter, of even the principle of equivalence. We note that modern descriptions of gravity, such as fibre bundles and higher dimensional spacetimes, allow violations of the commonly stated form of the principle of equivalence, and of CPT. We review both indirect arguments and experimental tests of the expected gravitational properties of CPT-conjugate states. We conclude that a direct experimental test of the gravitational properties of antimatter, at the 1% (or better) level, would be of great value. We identify some experimental reasons which make the antiproton a prime candidate for this test, and we strongly urge that such an experiment be done at LEAR. 21 references

  17. Gravitation and electromagnetism

    CERN Document Server

    Apsel, D

    1979-01-01

    Through an examination of the Bohm-Aharonov experiment, a new theory of gravitation and electromagnetism is proposed. The fundamental assumption of the theory is that the motion of a particle in a combination of gravitational and electromagnetic fields is determined from a variational principle of the form delta integral /sub A//sup B /d tau =0. The form of the physical time is determined from an examination of the Maxwell-Einstein action function. The field and motion equations are formally identical to those of Maxwell-Einstein theory. The theory predicts that even in a field-free region of space, electromagnetic potentials can alter the phase of a wave function and the lifetime of a charged particle. The phase alteration has been observed in the Bohm-Aharonov experiment. There is an indication that the lifetime alteration has shown up in a recent CERN storage ring experiment. Experimental tests are proposed. (11 refs).

  18. Spacetime and gravitation.

    Science.gov (United States)

    Kopczyński, W.; Trautman, A.

    This book is a revised translation of the Polish original "Czasoprzestrzeń i grawitacja", Warszawa (Poland), Państwowe Wydawnictwo Naukowe, 1984. Ideas about space and time are at the root of one's understanding of nature, both at the intuitive level of everyday experience and in the framework of sophisticated physical theories. These ideas have led to the development of geometry and its applications to physics. The contemporary physical theory of space and time, including its extention to the phenomena of gravitation, is Einstein's theory of relativity. The book is a short introduction to this theory. A great deal of emphasis is given to the geometrical aspects of relativity theory and its comparison with the Newtonian view of the world. There are short chapters on the origins of Einstein's theory, gravitational waves, cosmology, spinors and the Einstein-Cartan theory.

  19. Infinite order quantum-gravitational correlations

    Science.gov (United States)

    Knorr, Benjamin

    2018-06-01

    A new approximation scheme for nonperturbative renormalisation group equations for quantum gravity is introduced. Correlation functions of arbitrarily high order can be studied by resolving the full dependence of the renormalisation group equations on the fluctuation field (graviton). This is reminiscent of a local potential approximation in O(N)-symmetric field theories. As a first proof of principle, we derive the flow equation for the ‘graviton potential’ induced by a conformal fluctuation and corrections induced by a gravitational wave fluctuation. Indications are found that quantum gravity might be in a non-metric phase in the deep ultraviolet. The present setup significantly improves the quality of previous fluctuation vertex studies by including infinitely many couplings, thereby testing the reliability of schemes to identify different couplings to close the equations, and represents an important step towards the resolution of the Nielsen identity. The setup further allows one, in principle, to address the question of putative gravitational condensates.

  20. Chiral gravitational waves and baryon superfluid dark matter

    Science.gov (United States)

    Alexander, Stephon; McDonough, Evan; Spergel, David N.

    2018-05-01

    We develop a unified model of darkgenesis and baryogenesis involving strongly interacting dark quarks, utilizing the gravitational anomaly of chiral gauge theories. In these models, both the visible and dark baryon asymmetries are generated by the gravitational anomaly induced by the presence of chiral primordial gravitational waves. We provide a concrete model of an SU(2) gauge theory with two massless quarks. In this model, the dark quarks condense and form a dark baryon charge superfluid (DBS), in which the Higgs-mode acts as cold dark matter. We elucidate the essential features of this dark matter scenario and discuss its phenomenological prospects.

  1. Neutrinos from gravitational collapse

    International Nuclear Information System (INIS)

    Mayle, R.; Wilson, J.R.; Schramm, D.N.

    1986-05-01

    Detailed calculations are made of the neutrino spectra emitted during gravitational collapse events (Type II supernovae). Those aspects of the neutrino signal which are relatively independent of the collapse model and those aspects which are sensitive to model details are discussed. The easier-to-detect high energy tail of the emitted neutrinos has been calculated using the Boltzmann equation which is compared with the result of the traditional multi-group flux limited diffusion calculations. 8 figs., 28 refs

  2. Bimetric Machian gravitation

    Energy Technology Data Exchange (ETDEWEB)

    Goldoni, R

    1980-11-22

    A bimetric theory of gravitation within a Machian framework is developed on the basis of considerations which are completely divorced from Newton's theory. The theory is assumed to hold in any conceivable cosmos and possesses the Machian properties of being singular in the absence of matter and of explicitly incorporating the idea that properties of space-time are determined not only by local matter, but also by the average distribution of cosmological matter.

  3. Gravitation, Symmetry and Undergraduates

    Science.gov (United States)

    Jorgensen, Jamie

    2001-04-01

    This talk will discuss "Project Petrov" Which is designed to investigate gravitational fields with symmetry. Project Petrov represents a collaboration involving physicists, mathematicians as well as graduate and undergraduate math and physics students. An overview of Project Petrov will be given, with an emphasis on students' contributions, including software to classify and generate Lie algebras, to classify isometry groups, and to compute the isometry group of a given metric.

  4. Gravitational field mass

    International Nuclear Information System (INIS)

    Penrose, R.

    1986-01-01

    The author's definition for the mass-momentum/angular momentum surrounded by a spacelike 2-surface with S/sup 2/ topology is presented. This definition is motivated by some ideas from twistor theory in relation to linearized gravitational theory. The status of this definition is examined in relation to many examples which have been worked out. The reason for introducing a slight modification of the original definition is also presented

  5. General Relativity and Gravitation

    Science.gov (United States)

    Ehlers, J.; Murdin, P.

    2000-11-01

    The General Theory of Relativity (GR), created by Albert Einstein between 1907 and 1915, is a theory both of gravitation and of spacetime structure. It is based on the assumption that matter, via its energy-momentum, interacts with the metric of spacetime, which is considered (in contrast to Newtonian physics and SPECIAL RELATIVITY) as a dynamical field having degrees of freedom of its own (GRAVI...

  6. Fivebrane gravitational anomalies

    International Nuclear Information System (INIS)

    Becker, Katrin; Becker, Melanie

    2000-01-01

    Freed, Harvey, Minasian and Moore (FHMM) have proposed a mechanism to cancel the gravitational anomaly of the M-theory fivebrane coming from diffeomorphisms acting on the normal bundle. This procedure is based on a modification of the conventional M-theory Chern-Simons term. We apply the FHMM mechanism in the ten-dimensional type IIA theory. We then analyze the relation to the anomaly cancellation mechanism for the type IIA fivebrane proposed by Witten

  7. Nondissipative gravitational turbulence

    International Nuclear Information System (INIS)

    Gurevich, A.V.; Zybin, K.P.

    1988-01-01

    The nonlinear stage of development of the Jeans instability in a cold nondissipative gravitating gas is considered. It is shown that for a time exceeding the Jeans time a nondissipative gravitational singularity (NGS) is formed in the vicinity of a local density maximum. The NGS is a stationary dynamic structure, the basis of which is the singularity. The density of the gas at the center of the NGS (for r → 0) tends to infinity, and the field potential and the mean velocity of the trapped gas, possess a power singularity. The turbulent state arises as the result of development of the instability in the case of an irregular initial density distribution. It is an hierarchic structure consisting of nested moving NGS of various sizes, the NGS of smaller dimensions being trapped in the field of a NGS of larger dimensions. The scaling relations for each given NGS in this case hold for both the gas density and density of smaller size trapped NGS. A brief comparison with the observational data shows that the real hierarchic structure of the Universe ranging from scales pertaining to spherical stellar clusters up to those of rich galaxy clusters is apparently a developed gravitational turbulence

  8. Excitations of the gravitational field-I

    International Nuclear Information System (INIS)

    Novello, M.

    1978-01-01

    The geometry of spacetime is treated as a stochastic variable. Fluctuations induce a deviation from Einstein's system of equations for the average geometry. A model is presented to deal with the fluctuations by expanding the perturbations on a series in the average geometry. As a consequence, some qualitatively new features appear. The influences on galaxy formation and on the propagation of gravitational waves are analyzed [pt

  9. Detection of gravitational waves from inflation

    International Nuclear Information System (INIS)

    Kamionkowski, M.; Jaffe, A.H.

    2001-01-01

    Recent measurements of temperature fluctuations in the cosmic microwave background (CMB) indicate that the Universe is flat and that large-scale structure grew via gravitational infall from primordial adiabatic perturbations. Both of these observations seem to indicate that we are on the right track with inflation. But what is the new physics responsible for inflation? This question can be answered with observations of the polarization of the CMB. Inflation predicts robustly the existence of a stochastic background of cosmological gravitational waves with an amplitude proportional to the square of the energy scale of inflation. This gravitational-wave background induces a unique signature in the polarization of the CMB. If inflation took place at an energy scale much smaller than that of grand unification, then the signal will be too small to be detectable. However, if inflation had something to do with grand unification or Planck-scale physics, then the signal is conceivably detectable in the optimistic case by the Planck satellite, or if not, then by a dedicated post-Planck CMB polarization experiment. Realistic developments in detector technology as well as a proper scan strategy could produce such a post-Planck experiment that would improve on Planck's sensitivity to the gravitational-wave background by several orders of magnitude in a decade timescale. (author)

  10. Interplay of gravitation and linear superposition of different mass eigenstates

    International Nuclear Information System (INIS)

    Ahluwalia, D.V.

    1998-01-01

    The interplay of gravitation and the quantum-mechanical principle of linear superposition induces a new set of neutrino oscillation phases. These ensure that the flavor-oscillation clocks, inherent in the phenomenon of neutrino oscillations, redshift precisely as required by Einstein close-quote s theory of gravitation. The physical observability of these phases in the context of the solar neutrino anomaly, type-II supernova, and certain atomic systems is briefly discussed. copyright 1998 The American Physical Society

  11. Quantum gravitational optics in the field of a gravitomagnetic monopole

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadi, N [Department of Physics, North Karegar Avenue, University of Tehran, P O Box 14395-547, Tehran (Iran, Islamic Republic of); Khoeini-Moghaddam, S [Department of Physics, Sharif University of Technology, P O Box 19365-9161, Tehran (Iran, Islamic Republic of); Nouri-Zonoz, M [Department of Physics, North Karegar Avenue, University of Tehran, P O Box 14395-547, Tehran (Iran, Islamic Republic of)

    2007-05-15

    Vacuum polarization in QED in a background gravitational field induces interactions which effectively modify the classical picture of light rays as the null geodesies of spacetime. After a short introduction on the main aspects of the quantum gravitational optics, as a nontrivial example, we study this effect in the background of NUT space characterizing the spacetime of a spherical mass endowed with a gravitomagnetic monopole charge, the so called NUT factor.

  12. Effects of running with backpack loads during simulated gravitational transitions: Improvements in postural control

    Science.gov (United States)

    Brewer, Jeffrey David

    The National Aeronautics and Space Administration is planning for long-duration manned missions to the Moon and Mars. For feasible long-duration space travel, improvements in exercise countermeasures are necessary to maintain cardiovascular fitness, bone mass throughout the body and the ability to perform coordinated movements in a constant gravitational environment that is six orders of magnitude higher than the "near weightlessness" condition experienced during transit to and/or orbit of the Moon, Mars, and Earth. In such gravitational transitions feedback and feedforward postural control strategies must be recalibrated to ensure optimal locomotion performance. In order to investigate methods of improving postural control adaptation during these gravitational transitions, a treadmill based precision stepping task was developed to reveal changes in neuromuscular control of locomotion following both simulated partial gravity exposure and post-simulation exercise countermeasures designed to speed lower extremity impedance adjustment mechanisms. The exercise countermeasures included a short period of running with or without backpack loads immediately after partial gravity running. A novel suspension type partial gravity simulator incorporating spring balancers and a motor-driven treadmill was developed to facilitate body weight off loading and various gait patterns in both simulated partial and full gravitational environments. Studies have provided evidence that suggests: the environmental simulator constructed for this thesis effort does induce locomotor adaptations following partial gravity running; the precision stepping task may be a helpful test for illuminating these adaptations; and musculoskeletal loading in the form of running with or without backpack loads may improve the locomotor adaptation process.

  13. The process and promotion of radiation-induced cell death

    International Nuclear Information System (INIS)

    Sasaki, Hiroshi

    1998-01-01

    Radiation-induced cell death is divided into reproductive and interphase death, whose process can be revealed by time-lapse observations. Pedigree analyses of progenies derived from a surviving progenitor cell have shown that moribund cells appear in clusters among cells which are apparently undamaged (lethal sectoring). Sister cell fusion, which likely results from chromosome bridge, is the most frequently observed cell abnormality leading to reproductive death. While interphase death does not occur unless the dose exceeds 10 Gy for low LET radiation such as X-rays, high-LET radiation is very effective at inducing interphase death (RBE: ≅3 at 230 keV/μm). Expression or fixation of potentially lethal damage (PLD) is closely associated with cell cycle events and enhanced by inducing premature chromosome condensation (PCC) at a nonpermissive temperature in tsBN2 cells with a ts-defect in RCC1 protein (a regulator of chromatin condensation) which monitors the completion of DNA replication. Furthermore, higher-order structural changes in nuclear matrix such as induced by leptomycin B, an inhibitor of CRM1 (chromosome region maintenance) protein, also play an important role in the fixation of PLD. (author)

  14. Dark matter structures and emission of very long gravitational waves

    International Nuclear Information System (INIS)

    Bisnovatyi-Kogan, G.S.

    2005-01-01

    Formation of large structure in the Universe as a result of gravitational instability in cold dark matter is investigated in a simple analytical model. Collapse of the rotating spheroid is approximated by a system of ordinary differential equations describing its dynamics. The gravitational potential is approximated by the one of the uniform Maclaurin spheroid. Development of gravitational instability and collapse in the dark matter medium do not lead to any shock formation or radiation, but is characterized by non-collisional relaxation, which is accompanied by the mass and angular momentum losses. Phenomenological account of these processes is done in this model. Formation of the equilibrium configuration dynamics of collapse is investigated. A very long gravitational wave emission during the collapse is estimated, and their possible connection with the observed gravitational lenses is discussed

  15. Contributions to process monitoring by laser-induced breakdown spectroscopy

    Science.gov (United States)

    Rusak, David Alexander

    1998-12-01

    When a pulsed laser of sufficient energy and pulse duration is brought to a focus, multi-photon ionization creates free electrons in the focal volume. These electrons are accelerated in a process known as inverse Bremsstrahlung and cause collisional ionization of species in the focal volume. More charge carriers are produced and the process continues for the duration of the laser pulse. The manifestation of this process is a visible spark or plasma which typically lasts for tens of microseconds. This laser-induced plasma can serve as a source in an atomic emission experiment. Because the composition of the plasma is determined in large part by the environment in which it forms, elements in the laser target can be determined spectroscopically. The goal of a laser-induced breakdown spectroscopy (LIBS) experiment is to establish a relationship between the concentration of an element of interest in the target and the intensity of light emitted from the laser-induced plasma at a wavelength characteristic of that element. Because LIBS requires only optical access to the sample and can perform elemental determinations in solids, liquids, or gases with little sample preparation, there is interest in using it as an on-line technique for process monitoring in a number of industrial applications. However, before the technique becomes useful in industrial applications, many issues regarding instrumentation and data analysis need to be addressed in the lab. The first two chapters of this dissertation provide, respectively, the basics of the atomic emission experiment and a background of laser-induced breakdown spectroscopy. The next two chapters examine the effect of target water content on the laser-induced plasma and the use of LIBS for analysis of aqueous samples. Chapter 5 describes construction of a fiber optic LIBS probe and its use to study temporal electron number density evolution in plasmas formed on different metals. Chapter 6 is a study of excitation, vibrational

  16. On gravitational wave energy in Einstein gravitational theory

    International Nuclear Information System (INIS)

    Folomeshkin, V.N.; Vlasov, A.A.

    1978-01-01

    By the example of precise wave solutions for the Einstein equations it is shown that a standard commonly adopted formulation of energy-momentum problem with pseudotensors provides us either with a zero or sign-variable values for the energy of gravitational waves. It is shown that if in the Einstein gravitational theory a strict transition to the limits of weak fields is realised then the theory gives us an unambiguous zero result for weak gravitational waves. The well-known non-zero result arises due to incorrect transition to weak field approximation in the Einstein gravitation theory

  17. Process induced residual stresses and distortions in pultrusion

    DEFF Research Database (Denmark)

    Baran, Ismet; Tutum, Cem Celal; Nielsen, Michael Wenani

    2013-01-01

    In the present study, a coupled 3D transient Eulerian thermo-chemical analysis together with a 2D plane strain Lagrangian mechanical analysis of the pultrusion process, which has not been considered until now, is carried out. The development of the process induced residual stresses and strains...... together with the distortions are predicted during the pultrusion in which the cure hardening instantaneous linear elastic (CHILE) approach is implemented. At the end of the process, tension stresses prevail for the inner region of the composite since the curing rate is higher here as compared to the outer...... regions where compression stresses are obtained. The separation between the heating die and the part due to shrinkage is also investigated using a mechanical contact formulation at the die-part interface. The proposed approach is found to be efficient and fast for the calculation of the residual stresses...

  18. Neutron Induced Capture and Fission Processes on 238U

    Directory of Open Access Journals (Sweden)

    Oprea Cristiana

    2016-01-01

    Full Text Available Nuclear data on Uranium isotopes are of crucial interest for new generation of nuclear reactors. Processes of interest are the nuclear reactions induced by neutrons and in this work mainly the capture and the fission process on 238U will be analyzed in a wide energy interval. For slow and resonant neutrons the many levels Breit – Wigner formalism is necessary. In the case of fast and very fast neutrons up to 200 MeV the nuclear reaction mechanism implemented in Talys will be used. The present evaluations are necessary in order to obtain the field of neutrons in the design of nuclear reactors and they are compared with experimental data from literature obtained from capture and (n,xn processes.

  19. Desolvation Induced Origami of Photocurable Polymers by Digit Light Processing.

    Science.gov (United States)

    Zhao, Zeang; Wu, Jiangtao; Mu, Xiaoming; Chen, Haosen; Qi, H Jerry; Fang, Daining

    2017-07-01

    Self-folding origami is of great interest in current research on functional materials and structures, but there is still a challenge to develop a simple method to create freestanding, reversible, and complex origami structures. This communication provides a feasible solution to this challenge by developing a method based on the digit light processing technique and desolvation-induced self-folding. In this new method, flat polymer sheets can be cured by a light field from a commercial projector with varying intensity, and the self-folding process is triggered by desolvation in water. Folded origami structures can be recovered once immersed in the swelling medium. The self-folding process is investigated both experimentally and theoretically. Diverse 3D origami shapes are demonstrated. This method can be used for responsive actuators and the fabrication of 3D electronic devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Gravitational vacuum and energy release in microworld

    International Nuclear Information System (INIS)

    Mel'nikov, V.N.; Nikolaev, Yu.M.; Stanyukovich, K.P.

    1981-01-01

    It is shown that gravitati.onal interaction can be connected with the processes of energy release in microworld. Suggested is a planckeon model within the frames of which gradual production of the observed substance of the Universe during the whole evolution is explained. Burst processes in nuclei of the Galaxy are explained. It is concluded that the theory of gravitational vacuum creates preconditions for developing the general theory of the field explaining the basic peculiarities of the micro- and macroworld, reveals significant applications in the physics of elementary particles and atomic nucleus. The process of 235 U fission is considered for testing the hypothesis that the coefficient of energy release depends on the nature of the reaction in different processes of energy release in the micro- and macroworld [ru

  1. On the structure of translational gauge theories of gravitation

    International Nuclear Information System (INIS)

    Wallner, R.P.

    1982-01-01

    Guided by decoupling processes in general gauge theories, we examine the translation limit in U 4 -theories. It is shown that this leads to Einstein's gravity theory as the appropriate choice for a translational gauge theory of gravitation. (Author)

  2. Quantum Emulation of Gravitational Waves.

    Science.gov (United States)

    Fernandez-Corbaton, Ivan; Cirio, Mauro; Büse, Alexander; Lamata, Lucas; Solano, Enrique; Molina-Terriza, Gabriel

    2015-07-14

    Gravitational waves, as predicted by Einstein's general relativity theory, appear as ripples in the fabric of spacetime traveling at the speed of light. We prove that the propagation of small amplitude gravitational waves in a curved spacetime is equivalent to the propagation of a subspace of electromagnetic states. We use this result to propose the use of entangled photons to emulate the evolution of gravitational waves in curved spacetimes by means of experimental electromagnetic setups featuring metamaterials.

  3. Probing Positron Gravitation at HERA

    International Nuclear Information System (INIS)

    Gharibyan, Vahagn

    2015-07-01

    An equality of particle and antiparticle gravitational interactions holds in general relativity and is supported by indirect observations. Here I develop a method based on high energy Compton scattering to measure the gravitational interaction of accelerated charged particles. Within that formalism the Compton spectra measured at HERA rule out the positron's anti-gravity and hint for a positron's 1.3(0.2)% weaker coupling to the gravitational field relative to an electron.

  4. Probing Positron Gravitation at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Gharibyan, Vahagn

    2015-07-15

    An equality of particle and antiparticle gravitational interactions holds in general relativity and is supported by indirect observations. Here I develop a method based on high energy Compton scattering to measure the gravitational interaction of accelerated charged particles. Within that formalism the Compton spectra measured at HERA rule out the positron's anti-gravity and hint for a positron's 1.3(0.2)% weaker coupling to the gravitational field relative to an electron.

  5. Topics in gravitation and gauge fields

    International Nuclear Information System (INIS)

    Leen, T.K.

    1982-01-01

    The theoretical studies presented here address three distinct topics. The first deals with quantum-mechanical effects of classical gravitational radiation. Specifically, the use of the interstellar medium itself as a remote quantum-mechanical detector of gravitational waves is investigated. This study is motivated by the presumed existence of atomic hydrogen in the vicinity of astrophysical sources of gravitational radiation. Space-time curvature produces uniquely identifiable shifts in atomic hydrogen energy levels. The oscillating level shifts induced by a passing gravitational wave could conceivably be detected spectroscopically. Accordingly the level shifts for both low-lying and highly excited states of single electron atoms immersed in gravitational radiation have been studied. The second two topics deal with the theory of quantized fields on curved space-times. In the first of these studies, a naive model of cosmological baryon synthesis is examined. The model incorporates a hard CP violation as well as a baryon (and lepton) non-conserving interaction and is thus capable of generating an excess of matter over antimatter. The time dependent background geometry of the early universe drives the interaction producing net excess of baryon/lepton pairs. In the final topic, the question of renormalizability of non-Abelian gauge fields theories in a general curved space-time is addressed. All modern theories of elementary particle physics are gauge theories and one would like to know if their perturbative expansions continue to be well defined (i.e. renormalizable) on curved backgrounds. In general, one is interested in knowing if field theories renormalizable in Minkowski space remain so in a general curved space-time

  6. Long Term Monitoring of Microbial Induced Soil Strengthening Processes

    Science.gov (United States)

    Saneiyan, S.; Ntarlagiannis, D.; Werkema, D. D., Jr.; Colwell, F. S.; Ohan, J.

    2016-12-01

    Soil strengthening/stabilization processes are used to address some of soil quality issues. Microbial induced calcite precipitation (MICP) is a promising soil stabilization process that could offer long term solution by overcoming problems of commonly used methods (e.g. injecting cement slurry). MICP can be applied in larger spatial scales, allowing the enhanced soils to be maintained in an economic sustainable and environmental friendly way. Methods are sought for the long term monitoring of MICP enhanced soils. The spectral induced polarization (SIP) method is one promising method due to sensitivity on such processes and the ability for long term, even autonomous, operation as well as cost effectiveness. Previous laboratory tests showed the sensitivity of the SIP method on soil strengthening as a result of abiotic calcite precipitation. We extended this work to biotic calcite precipitation through MICP. Early results suggest that the MICP formed calcite is denser and could provide improved strengthening capabilities. Our results are supported by geophysical (SIP and shear-wave velocity), geo-chemical and microbiological monitoring. Destructive analysis and visualization (scanning electron imaging - SEM) is expected to provide conclusive evidence on the MICP long term effectiveness.

  7. Quantum phenomena in gravitational field

    Science.gov (United States)

    Bourdel, Th.; Doser, M.; Ernest, A. D.; Voronin, A. Yu.; Voronin, V. V.

    2011-10-01

    The subjects presented here are very different. Their common feature is that they all involve quantum phenomena in a gravitational field: gravitational quantum states of ultracold antihydrogen above a material surface and measuring a gravitational interaction of antihydrogen in AEGIS, a quantum trampoline for ultracold atoms, and a hypothesis on naturally occurring gravitational quantum states, an Eötvös-type experiment with cold neutrons and others. Considering them together, however, we could learn that they have many common points both in physics and in methodology.

  8. Quantum phenomena in gravitational field

    International Nuclear Information System (INIS)

    Bourdel, Th.; Doser, M.; Ernest, A.D.; Voronin, A.Y.; Voronin, V.V.

    2010-01-01

    The subjects presented here are very different. Their common feature is that they all involve quantum phenomena in a gravitational field: gravitational quantum states of ultracold anti-hydrogen above a material surface and measuring a gravitational interaction of anti-hydrogen in AEGIS, a quantum trampoline for ultracold atoms, and a hypothesis on naturally occurring gravitational quantum states, an Eoetvoes-type experiment with cold neutrons and others. Considering them together, however, we could learn that they have many common points both in physics and in methodology. (authors)

  9. Gravitational Physics Research

    Science.gov (United States)

    Wu, S. T.

    2000-01-01

    Gravitational physics research at ISPAE is connected with NASA's Relativity Mission (Gravity Probe B (GP-B)) which will perform a test of Einstein's General Relativity Theory. GP-B will measure the geodetic and motional effect predicted by General Relativity Theory with extremely stable and sensitive gyroscopes in an earth orbiting satellite. Both effects cause a very small precession of the gyroscope spin axis. The goal of the GP-B experiment is the measurement of the gyroscope precession with very high precision. GP-B is being developed by a team at Stanford University and is scheduled for launch in the year 2001. The related UAH research is a collaboration with Stanford University and MSFC. This research is focussed primarily on the error analysis and data reduction methods of the experiment but includes other topics concerned with experiment systems and their performance affecting the science measurements. The hydrogen maser is the most accurate and stable clock available. It will be used in future gravitational physics missions to measure relativistic effects such as the second order Doppler effect. The HMC experiment, currently under development at the Smithsonian Astrophysical Observatory (SAO), will test the performance and capability of the hydrogen maser clock for gravitational physics measurements. UAH in collaboration with the SAO science team will study methods to evaluate the behavior and performance of the HMC. The GP-B data analysis developed by the Stanford group involves complicated mathematical operations. This situation led to the idea to investigate alternate and possibly simpler mathematical procedures to extract the GP-B measurements form the data stream. Comparison of different methods would increase the confidence in the selected scheme.

  10. The future of focused electron beam-induced processing

    International Nuclear Information System (INIS)

    Hagen, C.W.

    2014-01-01

    A perspective is sketched for the field of focused electron beam-induced processing (FEBIP). The FEBIP lithography technique is compared to the very successful resist-based electron beam lithography (EBL) technique. The advantages of FEBIP over EBL are identified, the main advantage being its high spatial resolution. This will enable FEBIP to become an important lithography technique for the fabrication of devices with critical dimension in the range between 1 and 20 nm and serve as a complementary technique to EBL. It will be discussed what needs to be done to achieve this and what the potential applications are. (orig.)

  11. Systematics of quasi-elastic processes induced by heavy ions

    International Nuclear Information System (INIS)

    Baltz, A.J.

    1976-01-01

    An attempt is made to delineate the areas in the systematics of quasi-elastic processes induced by heavy ions that are well described theoretically from the specific features that seem not to be understood. One- and two-particle transfer reactions are considered. A general systematic seen in transfer angular distribution data and theory, some successes and failures of the DWBA and coupled-channels theories in describing heavy-ion-reaction data, and the specific example 232 Th( 40 Ar,K) and implications for deep inelastic reactions with even heavier projectiles such as Kr and Xe are considered

  12. Gravitational radiation from dust

    International Nuclear Information System (INIS)

    Isaacson, R.A.; Welling, J.S.; Winicour, J.

    1985-01-01

    A dust cloud is examined within the framework of the general relativistic characteristic initial value problem. Unique gravitational initial data are obtained by requiring that the space-time be quasi-Newtonian. Explicit calculations of metric and matter fields are presented, which include all post-Newtonian corrections necessary to discuss the major physical properties of null infinity. These results establish a curved space version of the Einstein quadrupole formula, in the form ''news function equals third time derivative of transverse quadrupole moment,'' for this system. However, these results imply that some weakened notion of asymptotic flatness is necessary for the description of quasi-Newtonian systems

  13. The earth's gravitational field

    Digital Repository Service at National Institute of Oceanography (India)

    Ramprasad, T.

    . But to say that gravity acts downwards is not correct. Gravity acts down, no matter where you stand on the Earth. It is better to say that on Earth gravity pulls objects towards the centre of the Earth. So no matter where you are on Earth all objects fall... pull than objects at the poles. In combination, the equatorial bulge and the effects of centrifugal force mean that sea-level gravitational acceleration increases from about 9.780 m/s² at the equator to about 9.832 m/s² at the poles, so an object...

  14. Superstatistics and Gravitation

    Directory of Open Access Journals (Sweden)

    Octavio Obregón

    2010-09-01

    Full Text Available We suggest to consider the spacetime as a non-equilibrium system with a long-term stationary state that possess as a spatio-temporally fluctuating quantity ß . These systems can be described by a superposition of several statistics, superstatistics. We propose a Gamma distribution for f(ß that depends on a parameter ρ1. By means of it the corresponding entropy is calculated, ρ1 is identified with the probability corresponding to this model. A generalized Newton’s law of gravitation is then obtained following the entropic force formulation. We discuss some of the difficulties to try to get an associated theory of gravity.

  15. The Effects of Gravitation on the Inter-Media Agenda-Setting Central Process: The Case of the Murder of Hrant Dink

    Directory of Open Access Journals (Sweden)

    Cem YAŞIN

    2014-02-01

    Full Text Available While the first level agenda setting researches focus on the transfer of issue salience from the media to public agenda, second level agenda setting researches interest in the attributes emphasized in the news and their affect on the public agenda. Some of these researches tends to analysis the media agenda. Influences of the news media on each other are studied by the inter-media agenda setting researches at at both the first and second levels. The same researches examine also the effects of different types of media on each other. However there is the problem of lack of a systematic theoretical model. This is caused by the differentiation in the aims of researchers and in their research objects. The other problem in the inter-media agenda setting researches is that there is no research on the agenda setting effects of the newspapers which have different ideological and political identities. This research aims to scrutinize the inter-media agenda-setting effects among various newspapers that have got different points of view. The research is designed to test the central gravitation effects of the mainstream news papers. Here the Murder of Hrant Dink is selected as a case study.

  16. The gravitational analog of Faraday's induction law

    Science.gov (United States)

    Zile, Daniel; Overduin, James

    2015-04-01

    Michael Faraday, the discoverer of electromagnetic induction, was convinced that there must also be a gravitational analog of this law, and he carried out drop-tower experiments in 1849 to look for the electric current induced in a coil by changes in gravitational flux through the coil. This work, now little remembered, was in some ways the first investigation of what we would now call a unified-field theory. We revisit Faraday's experiments in the light of current knowledge and ask what might be learned if they were to be performed today. We then review the gravitational analog for Faraday's law that arises within the vector (or gravito-electromagnetic) approximation to Einstein's theory of general relativity in the weak-field, low-velocity limit. This law relates spinning masses and induced ``mass currents'' rather than spinning charges and electric currents, but is otherwise remarkably similar to its electromagnetic counterpart. The predicted effects are completely unobservable in everyday settings like those envisioned by Faraday, but are thought to be relevant in astrophysical contexts like the accretion disks around collapsed stars, thus bearing out Faraday's remarkable intuition. Undergraduate student.

  17. Spectral induced polarization for monitoring electrokinetic remediation processes

    Science.gov (United States)

    Masi, Matteo; Losito, Gabriella

    2015-12-01

    Electrokinetic remediation is an emerging technology for extracting heavy metals from contaminated soils and sediments. This method uses a direct or alternating electric field to induce the transport of contaminants toward the electrodes. The electric field also produces pH variations, sorption/desorption and precipitation/dissolution of species in the porous medium during remediation. Since heavy metal mobility is pH-dependent, the accurate control of pH inside the material is required in order to enhance the removal efficiency. The common approach for monitoring the remediation process both in laboratory and in the field is the chemical analysis of samples collected from discrete locations. The purpose of this study is the evaluation of Spectral Induced Polarization as an alternative method for monitoring geochemical changes in the contaminated mass during remediation. The advantage of this technique applied to field-scale is to offer higher resolution mapping of the remediation site and lower cost compared to the conventional sampling procedure. We carried out laboratory-scale electrokinetic remediation experiments on fine-grained marine sediments contaminated by heavy metal and we made Spectral Induced Polarization measurements before and after each treatment. Measurements were done in the frequency range 10- 3-103 Hz. By the deconvolution of the spectra using the Debye Decomposition method we obtained the mean relaxation time and total chargeability. The main finding of this work is that a linear relationship exists between the local total chargeability and pH, with good agreement. The observed behaviour of chargeability is interpreted as a direct consequence of the alteration of the zeta potential of the sediment particles due to pH changes. Such relationship has a significant value for the interpretation of induced polarization data, allowing the use of this technique for monitoring electrokinetic remediation at field-scale.

  18. Gravitationally bound BCS state as dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, Stephon [Department of Physics, Brown University, Providence, RI 20912 (United States); Cormack, Sam, E-mail: stephon_alexander@brown.edu, E-mail: samuel.c.cormack.gr@dartmouth.edu [Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States)

    2017-04-01

    We explore the possibility that fermionic dark matter undergoes a BCS transition to form a superfluid. This requires an attractive interaction between fermions and we describe a possible source of this interaction induced by torsion. We describe the gravitating fermion system with the Bogoliubov-de Gennes formalism in the local density approximation. We solve the Poisson equation along with the equations for the density and gap energy of the fermions to find a self-gravitating, superfluid solution for dark matter halos. In order to produce halos the size of dwarf galaxies, we require a particle mass of ∼ 200 eV. We find a maximum attractive coupling strength before the halo becomes unstable. If dark matter halos do have a superfluid component, this raises the possibility that they contain vortex lines.

  19. Titan's Gravitational Field

    Science.gov (United States)

    Schubert, G.; Anderson, J. D.

    2013-12-01

    Titan's gravitational field is inferred from an analysis of archived radio Doppler data for six Cassini flybys. The analysis considers each flyby separately in contrast to the approach of lumping all the data together in a massive inversion. In this way it is possible to gain an improved understanding of the character of each flyby and its usefulness in constraining the gravitational coefficient C22 . Though our analysis is not yet complete and our final determination of C22 could differ from the result we report here by 1 or 2 sigma, we find a best-fit value of C22 equal to (13.21 × 0.17) × 10-6, significantly larger than the value of 10.0 × 10-6 obtained from an inversion of the lumped Cassini data. We also find no determination of the tidal Love number k2. The larger value of C22 implies a moment of inertia factor equal to 0.3819 × 0.0020 and a less differentiated Titan than is suggested by the smaller value. The larger value of C22 is consistent with an undifferentiated model of the satellite. While it is not possible to rule out either value of C22 , we prefer the larger value because its derivation results from a more hands on analysis of the data that extracts the weak hydrostatic signal while revealing the effects of gravity anomalies and unmodeled spacecraft accelerations on each of the six flybys.

  20. UCN gravitational spectrometer

    International Nuclear Information System (INIS)

    Kawabata, Yuji

    1988-01-01

    Concept design is carried out of two types of ultra cold neutron scallering equipment using the fall-focusing principle. One of the systems comprises a vertical gravitational spectrometer and the other includes a horizontal gravitation analyzer. A study is made of their performance and the following results are obtained. Fall-focusing type ultra cold neutron scattering equipment can achieve a high accuracy for measurement of energy and momentum. Compared with conventional neutron scattering systems, this type of equipment can use neutron very efficiently because scattered neutrons within a larger solid angle can be used. The maximum solid angle is nearly 4π and 2π for the vertical and horizontal type, respectively. Another feature is that the size of equipment can be reduced. In the present concept design, the equipment is spherical with a diameter of about 1 m, as compared with NESSIE which is 6.7 m in length and 4.85 m in height with about the same accuracy. Two horizontal analyzers and a vertical spectroscope are proposed. They are suitable for angle-dependent non-elastic scattering in the neutron velocity range of 6∼15 m/s, pure elastic scattering in the range of 4∼7 m/s, or angle-integration non-elastic scattering in the range of 4∼15 m/s. (N.K.)

  1. General Relativity and Gravitation

    Science.gov (United States)

    Ashtekar, Abhay; Berger, Beverly; Isenberg, James; MacCallum, Malcolm

    2015-07-01

    Part I. Einstein's Triumph: 1. 100 years of general relativity George F. R. Ellis; 2. Was Einstein right? Clifford M. Will; 3. Cosmology David Wands, Misao Sasaki, Eiichiro Komatsu, Roy Maartens and Malcolm A. H. MacCallum; 4. Relativistic astrophysics Peter Schneider, Ramesh Narayan, Jeffrey E. McClintock, Peter Mészáros and Martin J. Rees; Part II. New Window on the Universe: 5. Receiving gravitational waves Beverly K. Berger, Karsten Danzmann, Gabriela Gonzalez, Andrea Lommen, Guido Mueller, Albrecht Rüdiger and William Joseph Weber; 6. Sources of gravitational waves. Theory and observations Alessandra Buonanno and B. S. Sathyaprakash; Part III. Gravity is Geometry, After All: 7. Probing strong field gravity through numerical simulations Frans Pretorius, Matthew W. Choptuik and Luis Lehner; 8. The initial value problem of general relativity and its implications Gregory J. Galloway, Pengzi Miao and Richard Schoen; 9. Global behavior of solutions to Einstein's equations Stefanos Aretakis, James Isenberg, Vincent Moncrief and Igor Rodnianski; Part IV. Beyond Einstein: 10. Quantum fields in curved space-times Stefan Hollands and Robert M. Wald; 11. From general relativity to quantum gravity Abhay Ashtekar, Martin Reuter and Carlo Rovelli; 12. Quantum gravity via unification Henriette Elvang and Gary T. Horowitz.

  2. On geometrized gravitation theories

    International Nuclear Information System (INIS)

    Logunov, A.A.; Folomeshkin, V.N.

    1977-01-01

    General properties of the geometrized gravitation theories have been considered. Geometrization of the theory is realized only to the extent that by necessity follows from an experiment (geometrization of the density of the matter Lagrangian only). Aor a general case the gravitation field equations and the equations of motion for matter are formulated in the different Riemann spaces. A covariant formulation of the energy-momentum conservation laws is given in an arbitrary geometrized theory. The noncovariant notion of ''pseudotensor'' is not required in formulating the conservation laws. It is shown that in the general case (i.e., when there is an explicit dependence of the matter Lagrangian density on the covariant derivatives) a symmetric energy-momentum tensor of the matter is explicitly dependent on the curvature tensor. There are enlisted different geometrized theories that describe a known set of the experimental facts. The properties of one of the versions of the quasilinear geometrized theory that describes the experimental facts are considered. In such a theory the fundamental static spherically symmetrical solution has a singularity only in the coordinate origin. The theory permits to create a satisfactory model of the homogeneous nonstationary Universe

  3. Gravitating lepton bag model

    International Nuclear Information System (INIS)

    Burinskii, A.

    2015-01-01

    The Kerr–Newman (KN) black hole (BH) solution exhibits the external gravitational and electromagnetic field corresponding to that of the Dirac electron. For the large spin/mass ratio, a ≫ m, the BH loses horizons and acquires a naked singular ring creating two-sheeted topology. This space is regularized by the Higgs mechanism of symmetry breaking, leading to an extended particle that has a regular spinning core compatible with the external KN solution. We show that this core has much in common with the known MIT and SLAC bag models, but has the important advantage of being in accordance with the external gravitational and electromagnetic fields of the KN solution. A peculiar two-sheeted structure of Kerr’s gravity provides a framework for the implementation of the Higgs mechanism of symmetry breaking in configuration space in accordance with the concept of the electroweak sector of the Standard Model. Similar to other bag models, the KN bag is flexible and pliant to deformations. For parameters of a spinning electron, the bag takes the shape of a thin rotating disk of the Compton radius, with a ring–string structure and a quark-like singular pole formed at the sharp edge of this disk, indicating that the considered lepton bag forms a single bag–string–quark system

  4. Gravitational Waves - New Perspectives

    International Nuclear Information System (INIS)

    Biesiada, M.

    1999-01-01

    Laser interferometric experiments planned for 2002 will open up a new window onto the Universe. The first part of the paper gives a brief intuitive introduction to gravity waves, detection techniques and enumeration of main astrophysical sources and frequency bands to which they contribute. Then two more specific issues are discussed concerning cosmological perspectives of gravity waves detection. First one is the problem of gravitational lensing of the signal from inspiralling NS-NS binaries. The magnitude of the so called magnification bias is estimated and found non-negligible for some quite realistic lens models, but strongly model-dependent. The second problem is connected with estimates of galactic and extragalactic parts of the stochastic background. The main conclusion from these two examples is that in so far as the cosmological payoff of gravitational wave detection would be high, we should substantially deepen our understanding of basic astrophysical properties of galaxies and their clusters (in terms of mass distribution) in order to draw clear cosmological conclusions. (author)

  5. On synthetic gravitational waves from multi-field inflation

    Science.gov (United States)

    Ozsoy, Ogan

    2018-04-01

    We revisit the possibility of producing observable tensor modes through a continuous particle production process during inflation. Particularly, we focus on the multi-field realization of inflation where a spectator pseudoscalar σ induces a significant amplification of the U(1) gauge fields through the coupling propto σFμνtilde Fμν. In this model, both the scalar σ and the Abelian gauge fields are gravitationally coupled to the inflaton sector, therefore they can only affect the primordial scalar and tensor fluctuations through their mixing with gravitational fluctuations. Recent studies on this scenario show that the sourced contributions to the scalar correlators can be dangerously large to invalidate a large tensor power spectrum through the particle production mechanism. In this paper, we re-examine these recent claims by explicitly calculating the dominant contribution to the scalar power and bispectrum. Particularly, we show that once the current limits from CMB data are taken into account, it is still possible to generate a signal as large as r ≈ 10‑3 and the limitations on the model building are more relaxed than what was considered before.

  6. Secondary ionization processes in laser induced breakdown of electronegative gases

    International Nuclear Information System (INIS)

    Gamal Yosr, E.E.D.; Shafik, M.S.; Abdel-Moneim, H.M.

    1990-08-01

    This paper presents an investigation of the stepwise ionization processes which occur during the interaction of laser radiation with electronegative gases. Calculations are carried out adopting a modified version of the electron cascade model previously developed by Evans and Gamal. The modifications of the model are performed for the case of molecular oxygen to account for electron attachment losses. Particular attention is devoted to molecular oxygen at a pressure of 2.8 x 10 4 Torr irradiated by 10 ns pulse of Nd:YAG laser (λ=1.064 μm) at a peak intensity of 1.7x10 11 Wcm -2 . The calculations consider the effect of the secondary ionization processes on the electron energy distribution function and its parameters (evolution of the density of the excited molecules, electrons density as well as the electron mean energy during the laser flash). This analysis shows how the removal of slow electrons by attachment to oxygen molecules creates a strong competition between the stepwise ionization processes. These processes namely photoionization and collisional ionization deplete the electronic excited states and contribute eventually to the ionization growth rate in laser induced breakdown of electronegative gases. (author). 7 refs, 6 figs, 1 tab

  7. Numerical investigations of gravitational collapse

    Energy Technology Data Exchange (ETDEWEB)

    Csizmadia, Peter; Racz, Istvan, E-mail: iracz@rmki.kfki.h [RMKI, Budapest, Konkoly Thege Miklos ut 29-33, H-1121 (Hungary)

    2010-03-01

    Some properties of a new framework for simulating generic 4-dimensional spherically symmetric gravitating systems are discussed. The framework can be used to investigate spacetimes that undergo complete gravitational collapse. The analytic setup is chosen to ensure that our numerical method is capable to follow the time evolution everywhere, including the black hole region.

  8. To theory of gravitational interaction

    OpenAIRE

    Minkevich, A. V.

    2008-01-01

    Some principal problems of general relativity theory and attempts of their solution are discussed. The Poincare gauge theory of gravity as natural generalization of Einsteinian gravitation theory is considered. The changes of gravitational interaction in the frame of this theory leading to the solution of principal problems of general relativity theory are analyzed.

  9. Exact piecewise flat gravitational waves

    NARCIS (Netherlands)

    van de Meent, M.

    2011-01-01

    We generalize our previous linear result (van de Meent 2011 Class. Quantum Grav 28 075005) in obtaining gravitational waves from our piecewise flat model for gravity in 3+1 dimensions to exact piecewise flat configurations describing exact planar gravitational waves. We show explicitly how to

  10. Laboratory generation of gravitational waves

    International Nuclear Information System (INIS)

    Pinto, I.M.; Rotoli, G.

    1988-01-01

    The authors have performed calculations on the basic type of gravitational wave electromagnetic laboratory generators. Their results show that laboratory generations of gravitational wave is at limit of state-of-the-art of present-day giant electromagnetic field generation

  11. The gravitational properties of antimatter

    International Nuclear Information System (INIS)

    Goldman, T.; Hughes, R.J.; Nieto, M.M.

    1986-09-01

    It is argued that a determination of the gravitational acceleration of antimatter towards the earth is capable of imposing powerful constraints on modern quantum gravity theories. Theoretical reasons to expect non-Newtonian non-Einsteinian effects of gravitational strength and experimental suggestions of such effects are reviewed. 41 refs

  12. Critical Effects in Gravitational Collapse

    International Nuclear Information System (INIS)

    Chmaj, T.

    2000-01-01

    The models of gravitational collapse of a dynamical system are investigated by means of the Einstein equations. Different types conjunctions to gravitational field are analyzed and it is shown that in the case of week scalar field (low energy density) the system evaluated to flat space while in the case of strong field (high energy density) to black hole

  13. Conservation laws and gravitational radiation

    International Nuclear Information System (INIS)

    Rastall, P.

    1977-01-01

    A total stress-momentum is defined for gravitational fields and their sources. The Lagrangian density is slightly different from that in the previous version of the theory, and the field equations are considerably simplified. The post-Newtonian approximation of the theory is unchanged. The existence and nature of weak gravitational waves are discussed. (author)

  14. Vignettes in Gravitation and Cosmology

    CERN Document Server

    Sriramkumar, L

    2012-01-01

    This book comprises expository articles on different aspects of gravitation and cosmology that are aimed at graduate students. The topics discussed are of contemporary interest assuming only an elementary introduction to gravitation and cosmology. The presentations are to a certain extent pedagogical in nature, and the material developed is not usually found in sufficient detail in recent textbooks in these areas.

  15. Are the gravitational waves quantised?

    International Nuclear Information System (INIS)

    Lovas, Istvan

    1997-01-01

    If the gravitational waves are classical objects then the value of their correlation function is 1. If they are quantised, then there exist two possibilities: the gravitational waves are either completely coherent, then their correlation function is again 1, or they are only partially coherent, then their correlation function is expected to deviate from 1. Unfortunately such a deviation is not a sufficient proof for the quantised character of the gravitational waves. If the gravitational waves are quantised and generated by the change of the background metrical then they can be in a squeezed state. In a squeezed state there is a chance for the correlation between the phase of the wave and the quantum fluctuations. The observation of such a correlation would be a genuine proof of the quantised character of the gravitational wave

  16. Gravitational wave experiments

    CERN Document Server

    Hamilton, W O

    1993-01-01

    There were three oral sessions and one poster session for Workshop C1 on Gravitational Wave Experiments. There was also an informal experimental roundtable held one after- noon. The first two oral sessions were devoted mainly to progress reports from various interferometric and bar detector groups. A total of 15 papers were presented in these two sessions. The third session of Workshop C1 was devoted primarily to theoretical and experimental investigations associated with the proposed interferometric detectors. Ten papers were presented in this session. In addition, there were a total of 13 papers presented in the poster session. There was some overlap between the presentations in the third oral session and the posters since only two of the serious posters were devoted to technology not pertinent to interferometers. In general, the papers showed the increasing maturity of the experimental aspects of the field since most presented the results of completed investigations rather than making promises of wonderf...

  17. Atomic and gravitational clocks

    International Nuclear Information System (INIS)

    Canuto, V.M.; City Coll., New York; Goldman, I.

    1982-01-01

    Atomic and gravitational clocks are governed by the laws of electrodynamics and gravity respectively. While the strong equivalence principle (SEP) assumes that the two clocks have been synchronous at all times, recent planetary data seem to suggest a possible violation of the SEP. Past analysis of the implications of an SEP violation on different physical phenomena revealed no disagreement. However, these studies assumed that the two different clocks can be consistently constructed within the framework. The concept of scale invariance, and the physical meaning of different systems of units, are now reviewed and the construction of two clocks that do not remain synchronous-whose rates are related by a non-constant function βsub(a)-is demonstrated. The cosmological character of βsub(a) is also discussed. (author)

  18. Solar gravitational redshift

    International Nuclear Information System (INIS)

    Lopresto, J.C.; Chapman, R.D.

    1980-01-01

    Wavelengths of solar spectrum lines should be shifted toward the red by the Sun's gravitational field as predicted by metric theories of gravity according to the principle of equivalence. Photographic wavelengths of 738 solar Fe 1 lines and their corresponding laboratory wavelengths have been studied. The measured solar wavelength minus the laboratory wavelength (Δlambdasub(observed)) averaged for the strong lines agrees well with the theoretically predicted shift (Δlambdasub(theoretical)). Studies show that the departures depend on line strength. No dependence of the departures on wavelength was found within the existing data. By studying strong lines over a wide spectral range, velocity shifts caused by the complex motions in the solar atmosphere seem to affect the results in a minimal fashion. (orig.)

  19. Observations of gravitational lenses

    International Nuclear Information System (INIS)

    Fort, B.

    1990-01-01

    During the last tow years a burst of results has come from radio and optical surveys of ''galaxy lenses'' (where the main deflector is a galaxy). These are reviewed. On the other hand, in September 1985 we pointed out a very strange blue ring-like structure on a Charge-Coupled Device image of the cluster of galaxies Abell 370. This turned out to be Einstein arcs discovery. Following this discovery, new observational results have shown that many rich clusters of galaxies can produce numerous arclets: tangentially distorted images of an extremely faint galaxy population probably located at redshift larger than 1. This new class of gravitational lenses proves to be an important observational topic and this will be discussed in the second part of the paper. (author)

  20. Feynman Lectures on Gravitation

    International Nuclear Information System (INIS)

    Borcherds, P

    2003-01-01

    In the early 1960s Feynman lectured to physics undergraduates and, with the assistance of his colleagues Leighton and Sands, produced the three-volume classic Feynman Lectures in Physics. These lectures were delivered in the mornings. In the afternoons Feynman was giving postgraduate lectures on gravitation. This book is based on notes compiled by two students on that course: Morinigo and Wagner. Their notes were checked and approved by Feynman and were available at Caltech. They have now been edited by Brian Hatfield and made more widely available. The book has a substantial preface by John Preskill and Kip Thorne, and an introduction entitled 'Quantum Gravity' by Brian Hatfield. You should read these before going on to the lectures themselves. Preskill and Thorne identify three categories of potential readers of this book. 1. Those with a postgraduate training in theoretical physics. 2. 'Readers with a solid undergraduate training in physics'. 3. 'Admirers of Feynman who do not have a strong physics background'. The title of the book is perhaps misleading: readers in category 2 who think that this book is an extension of the Feynman Lectures in Physics may be disappointed. It is not: it is a book aimed mainly at those in category 1. If you want to get to grips with gravitation (and general relativity) then you need to read an introductory text first e.g. General Relativity by I R Kenyon (Oxford: Oxford University Press) or A Unified Grand Tour of Theoretical Physics by Ian D Lawrie (Bristol: IoP). But there is no Royal Road. As pointed out in the preface and in the introduction, the book represents Feynman's thinking about gravitation some 40 years ago: the lecture course was part of his attempts to understand the subject himself, and for readers in all three categories it is this that makes the book one of interest: the opportunity to observe how a great physicist attempts to tackle some of the hardest challenges of physics. However, the book was written 40

  1. Electromagnetically Induced Transparency in Four Wave Mixing Process

    International Nuclear Information System (INIS)

    Kucukkara, I.

    2008-01-01

    We have theoretically studied Four Wave Mixing (FWM) process in VUV (Vacuum Ultraviolet) region enhanced by Electromagnetically Induced Transparency in Krypton gas medium at room temperature. One of the mixing fields, in the ultraviolet region at 212.5 nm was in two-photon resonance with the 4p 6 1 S 0 -4p 5 5p[0,1/2] transition of Krypton and the second field (coupling field) at 759 nm was resonant with the 4p 5 5p[0,1/2]-4p 5 5s[1,1/2] transition in scheme. This coupling field produced an electromagnetically induced transparency and thus the efficiency of the generation of the field at 123.6 nm on the 4p 5 5s[1,1/2] to 4p 6 1 S 0 transition is enhanced. We modified the computer program previously written by changing some variables like pressure, interaction region length, UV energy, IR energy. As demonstrated by the intensity generated VUV light versus Krypton pressure graphic, the most efficient intensity value, which was approximately 4.2x10 1 6 arbitrary units, was obtained while IR energy was 3x10 - 4 J and the pressure was 2x10 - 3 bar

  2. Impairment induced by chronic occupational cadmium exposure during brazing process

    International Nuclear Information System (INIS)

    Anwar, S.M.; Aly, M.M.

    2002-01-01

    Cadmium (CD) is considered a metal of the 20 th century to which all inhabitants of develop societies are exposed. Long-term occupational and environmental exposure to CD often results in renal dysfunction as the kidney is considered the critical target organ. The aim of this work was to evalutate both resporatory and renal manifestations induced by occupational exposure to CD compounds during brazing process, and suggesting a protocol for prevention and control for CD- induced health effects. This study was conducted on 20 males occupationally exposed workers. They are divided into two groups: Group-1 included (10) exposed smokers and group-2 included (10) exposed non-smokers. Results of both groups were compared with those of 10 healthy age and sex matched non-smokers. All subjects were subjected to detailed history taking and laboratory investigations including blood and urinary CD, liver profile (SGOT, SGPT and alkline phosphates), kindey function tests (blood urea, creatinine and urinary beta 2 - microglobulin). The level of Cd in the atmosphere of the work plase air was also assessed to detect the degree of exposure as it was about 6 times greater than thesave level (1 mu /m 3 ). (1) This study demonstrated elevation levels of blood CD, urea, creatinine and urinary CD and beta 2 -microglobulin for both exposed worker groups than the controls. In additions no appreciable were noted for liver function tests, although the levels fell within normal range

  3. Magnetic reconnection processes induced by a CME expansion

    Directory of Open Access Journals (Sweden)

    A. Bemporad

    2008-10-01

    Full Text Available On 10–11 December 2005 a slow CME occurred in the Western Hemisphere in between two coronal streamers. SOHO/MDI magnetograms show a multipolar magnetic configuration at the photosphere: a complex of active regions located at the CME source and two bipoles at the base of the lateral coronal streamers. White light observations reveal that the CME expansion affects both of them and induces the release of plasma within or close to the nearby streamers. These transient phenomena are possibly due to magnetic reconnections induced by the CME expansion and occurring inside the streamer current sheet or between the CME flanks and the streamer. These events have been observed by the SOHO/UVCS with the spectrometer slit centered at 1.8 R⊙ over about a full day. In this work we focus on the interaction between the CME and the streamer: the UVCS spectral interval included UV lines from ions at different temperatures of maximum formation such as O VI, Si XIII and Al Xi. These data gave us the opportunity to infer the evolution of plasma temperature and density at the reconnection site and adjacent regions. These are relevant to characterize secondary reconnection processes occurring during a CME development.

  4. Mixing processes in the vitreous chamber induced by eye rotations

    Energy Technology Data Exchange (ETDEWEB)

    Stocchino, Alessandro [Department of Civil, Environmental and Architectural Engineering, University of Genoa (Italy); Repetto, Rodolfo [Department of Engineering of Structures, Water and Soil, University of L' Aquila (Italy); Siggers, Jennifer H [Department of Bioengineering, Imperial College London, London SW7 2AZ (United Kingdom)], E-mail: jorma@diam.unige.it

    2010-01-21

    In this paper, we study a model of flow in the vitreous humour in the posterior chamber of the human eye, induced by saccadic eye rotations. We concentrate on the effect of the shape of the chamber upon the mixing properties of the induced flows. We make particle image velocimetry measurements of the fluid velocity in a transparent plastic (Perspex) model of the posterior chamber during sinusoidal torsional oscillations about a vertical axis. We use a Newtonian fluid to model the vitreous humour, which is most realistic when either the vitreous humour is liquefied or has been replaced by purely viscous tamponade fluids. The model of the posterior chamber is a sphere with an indentation, representing the effect of the lens. In spite of the purely periodic forcing, a steady streaming flow is generated, which plays a fundamental role in the mixing processes in the domain. The streaming flow differs markedly from that in a perfect sphere, and its topological characteristics change substantially as the frequency of oscillation varies. We discuss the flow characteristics in detail and show that, for physiological parameter values, the Peclet number (based on a suitable measure of the steady streaming velocity) is large, suggesting that advection strongly dominates over diffusion for mass transport phenomena. We also compute particle trajectories based on the streaming velocity and use these to investigate the stirring properties of the flow.

  5. [Biomarkers of radiation-induced DNA repair processes].

    Science.gov (United States)

    Vallard, Alexis; Rancoule, Chloé; Guy, Jean-Baptiste; Espenel, Sophie; Sauvaigo, Sylvie; Rodriguez-Lafrasse, Claire; Magné, Nicolas

    2017-11-01

    The identification of DNA repair biomarkers is of paramount importance. Indeed, it is the first step in the process of modulating radiosensitivity and radioresistance. Unlike tools of detection and measurement of DNA damage, DNA repair biomarkers highlight the variations of DNA damage responses, depending on the dose and the dose rate. The aim of the present review is to describe the main biomarkers of radiation-induced DNA repair. We will focus on double strand breaks (DSB), because of their major role in radiation-induced cell death. The most important DNA repair biomarkers are DNA damage signaling proteins, with ATM, DNA-PKcs, 53BP1 and γ-H2AX. They can be analyzed either using immunostaining, or using lived cell imaging. However, to date, these techniques are still time and money consuming. The development of "omics" technologies should lead the way to new (and usable in daily routine) DNA repair biomarkers. Copyright © 2017 Société Française du Cancer. Published by Elsevier Masson SAS. All rights reserved.

  6. Mixing processes in the vitreous chamber induced by eye rotations

    International Nuclear Information System (INIS)

    Stocchino, Alessandro; Repetto, Rodolfo; Siggers, Jennifer H

    2010-01-01

    In this paper, we study a model of flow in the vitreous humour in the posterior chamber of the human eye, induced by saccadic eye rotations. We concentrate on the effect of the shape of the chamber upon the mixing properties of the induced flows. We make particle image velocimetry measurements of the fluid velocity in a transparent plastic (Perspex) model of the posterior chamber during sinusoidal torsional oscillations about a vertical axis. We use a Newtonian fluid to model the vitreous humour, which is most realistic when either the vitreous humour is liquefied or has been replaced by purely viscous tamponade fluids. The model of the posterior chamber is a sphere with an indentation, representing the effect of the lens. In spite of the purely periodic forcing, a steady streaming flow is generated, which plays a fundamental role in the mixing processes in the domain. The streaming flow differs markedly from that in a perfect sphere, and its topological characteristics change substantially as the frequency of oscillation varies. We discuss the flow characteristics in detail and show that, for physiological parameter values, the Peclet number (based on a suitable measure of the steady streaming velocity) is large, suggesting that advection strongly dominates over diffusion for mass transport phenomena. We also compute particle trajectories based on the streaming velocity and use these to investigate the stirring properties of the flow.

  7. Three-point statistics of cosmological stochastic gravitational waves

    International Nuclear Information System (INIS)

    Adshead, Peter; Lim, Eugene A.

    2010-01-01

    We consider the three-point function (i.e. the bispectrum or non-Gaussianity) for stochastic backgrounds of gravitational waves. We estimate the amplitude of this signal for the primordial inflationary background, gravitational waves generated during preheating, and for gravitational waves produced by self-ordering scalar fields following a global phase transition. To assess detectability, we describe how to extract the three-point signal from an idealized interferometric experiment and compute the signal to noise ratio as a function of integration time. The three-point signal for the stochastic gravitational wave background generated by inflation is unsurprisingly tiny. For gravitational radiation generated by purely causal, classical mechanisms we find that, no matter how nonlinear the process is, the three-point correlations produced vanish in direct detection experiments. On the other hand, we show that in scenarios where the B-mode of the cosmic microwave background is sourced by gravitational waves generated by a global phase transition, a strong three-point signal among the polarization modes is also produced. This may provide another method of distinguishing inflationary B-modes. To carry out this computation, we have developed a diagrammatic approach to the calculation of stochastic gravitational waves sourced by scalar fluids, which has applications beyond the present scenario.

  8. Gravitational waves from self-ordering scalar fields

    CERN Document Server

    Fenu, Elisa; Durrer, Ruth; Garcia-Bellido, Juan

    2009-01-01

    Gravitational waves were copiously produced in the early Universe whenever the processes taking place were sufficiently violent. The spectra of several of these gravitational wave backgrounds on subhorizon scales have been extensively studied in the literature. In this paper we analyze the shape and amplitude of the gravitational wave spectrum on scales which are superhorizon at the time of production. Such gravitational waves are expected from the self ordering of randomly oriented scalar fields which can be present during a thermal phase transition or during preheating after hybrid inflation. We find that, if the gravitational wave source acts only during a small fraction of the Hubble time, the gravitational wave spectrum at frequencies lower than the expansion rate at the time of production behaves as $\\Omega_{\\rm GW}(f) \\propto f^3$ with an amplitude much too small to be observable by gravitational wave observatories like LIGO, LISA or BBO. On the other hand, if the source is active for a much longer tim...

  9. Microstructure fabrication process induced modulations in CVD graphene

    Science.gov (United States)

    Matsubayashi, Akitomo; Zhang, Zhenjun; Lee, Ji Ung; LaBella, Vincent P.

    2014-12-01

    The systematic Raman spectroscopic study of a "mimicked" graphene device fabrication is presented. Upon photoresist baking, compressive stress is induced in the graphene which disappears after it is removed. The indirect irradiation from the electron beam (through the photoresist) does not significantly alter graphene characteristic Raman peaks indicating that graphene quality is preserved upon the exposure. The 2D peak shifts and the intensity ratio of 2D and G band, I(2D)/I(G), decreases upon direct metal deposition (Co and Py) suggesting that the electronic modulation occurs due to sp2 C-C bond weakening. In contrast, a thin metal oxide film deposited graphene does not show either the significant 2D and G peaks shift or I(2D)/I(G) decrease upon the metal deposition suggesting the oxide protect the graphene quality in the fabrication process.

  10. Microstructure fabrication process induced modulations in CVD graphene

    Energy Technology Data Exchange (ETDEWEB)

    Matsubayashi, Akitomo, E-mail: amatsubayashi@albany.edu; Zhang, Zhenjun; Lee, Ji Ung; LaBella, Vincent P., E-mail: vlabella@albany.edu [College of Nanoscale Science and Engineering, University at Albany, SUNY, Albany, New York 12203 (United States)

    2014-12-15

    The systematic Raman spectroscopic study of a “mimicked” graphene device fabrication is presented. Upon photoresist baking, compressive stress is induced in the graphene which disappears after it is removed. The indirect irradiation from the electron beam (through the photoresist) does not significantly alter graphene characteristic Raman peaks indicating that graphene quality is preserved upon the exposure. The 2D peak shifts and the intensity ratio of 2D and G band, I(2D)/I(G), decreases upon direct metal deposition (Co and Py) suggesting that the electronic modulation occurs due to sp{sup 2} C-C bond weakening. In contrast, a thin metal oxide film deposited graphene does not show either the significant 2D and G peaks shift or I(2D)/I(G) decrease upon the metal deposition suggesting the oxide protect the graphene quality in the fabrication process.

  11. Diffusion processes in bombardment-induced surface topography

    International Nuclear Information System (INIS)

    Robinson, R.S.

    1984-01-01

    The bombardment of surfaces with moderate energy ions can lead to the development of various micron-sized surface structures. These structures include ridges, ledges, flat planes, pits and cones. The causal phenomena in the production of these features are sputtering, ion reflection, redeposition of sputtered material, and surface diffusion of both impurity and target-atom species. The authors concentrate on the formation of ion bombardment-induced surface topography wherein surface diffusion is a dominant process. The most thoroughly understood aspect of this topography development is the generation of cone-like structures during sputtering. The formation of cones during sputtering has been attributed to three effects. These are: (1) the presence of asperities, defects, or micro-inclusions in the surface layers, (2) the presence of impurities on the surfaces, and (3) particular crystal orientations. (Auth.)

  12. Instrumental systematics and weak gravitational lensing

    International Nuclear Information System (INIS)

    Mandelbaum, R.

    2015-01-01

    We present a pedagogical review of the weak gravitational lensing measurement process and its connection to major scientific questions such as dark matter and dark energy. Then we describe common ways of parametrizing systematic errors and understanding how they affect weak lensing measurements. Finally, we discuss several instrumental systematics and how they fit into this context, and conclude with some future perspective on how progress can be made in understanding the impact of instrumental systematics on weak lensing measurements

  13. Formal identity of gravitational and weakly interacting recession

    International Nuclear Information System (INIS)

    Muheim, J.T.

    1982-01-01

    The author discusses the construction of models using the five elementary constants esub(s), h/2π, G, c and ksub(B) which can produce a macro or micro world with exacticity. All physical processes in nature determine the gravitational universe recession. A diagram is presented comparing the gravitational and weakly interacting recession. The Big-Bang model is discussed. (A.N.K.)

  14. Global gravitational anomalies and transport

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, Subham Dutta; David, Justin R. [Centre for High Energy Physics, Indian Institute of Science,C. V. Raman Avenue, Bangalore 560012 (India)

    2016-12-21

    We investigate the constraints imposed by global gravitational anomalies on parity odd induced transport coefficients in even dimensions for theories with chiral fermions, gravitinos and self dual tensors. The η-invariant for the large diffeomorphism corresponding to the T transformation on a torus constraints the coefficients in the thermal effective action up to mod 2. We show that the result obtained for the parity odd transport for gravitinos using global anomaly matching is consistent with the direct perturbative calculation. In d=6 we see that the second Pontryagin class in the anomaly polynomial does not contribute to the η-invariant which provides a topological explanation of this observation in the ‘replacement rule’. We then perform a direct perturbative calculation for the contribution of the self dual tensor in d=6 to the parity odd transport coefficient using the Feynman rules proposed by Gaumé and Witten. The result for the transport coefficient agrees with that obtained using matching of global anomalies.

  15. Weight, gravitation, inertia, and tides

    Science.gov (United States)

    Pujol, Olivier; Lagoute, Christophe; Pérez, José-Philippe

    2015-11-01

    This paper deals with the factors that influence the weight of an object near the Earth's surface. They are: (1) the Earth's gravitational force, (2) the centrifugal force due to the Earth's diurnal rotation, and (3) tidal forces due to the gravitational field of the Moon and Sun, and other solar system bodies to a lesser extent. Each of these three contributions is discussed and expressions are derived. The relationship between weight and gravitation is thus established in a direct and pedagogical manner readily understandable by undergraduate students. The analysis applies to the Newtonian limit of gravitation. The derivation is based on an experimental (or operational) definition of weight, and it is shown that it coincides with the Earth’s gravitational force modified by diurnal rotation around a polar axis and non-uniformity of external gravitational bodies (tidal term). Two examples illustrate and quantify these modifications, respectively the Eötvös effect and the oceanic tides; tidal forces due to differential gravitation on a spacecraft and an asteroid are also proposed as examples. Considerations about inertia are also given and some comments are made about a widespread, yet confusing, explanation of tides based on a centrifugal force. Finally, the expression of the potential energy of the tide-generating force is established rigorously in the appendix.

  16. Weight, gravitation, inertia, and tides

    International Nuclear Information System (INIS)

    Pujol, Olivier; Lagoute, Christophe; Pérez, José-Philippe

    2015-01-01

    This paper deals with the factors that influence the weight of an object near the Earth's surface. They are: (1) the Earth's gravitational force, (2) the centrifugal force due to the Earth's diurnal rotation, and (3) tidal forces due to the gravitational field of the Moon and Sun, and other solar system bodies to a lesser extent. Each of these three contributions is discussed and expressions are derived. The relationship between weight and gravitation is thus established in a direct and pedagogical manner readily understandable by undergraduate students. The analysis applies to the Newtonian limit of gravitation. The derivation is based on an experimental (or operational) definition of weight, and it is shown that it coincides with the Earth’s gravitational force modified by diurnal rotation around a polar axis and non-uniformity of external gravitational bodies (tidal term). Two examples illustrate and quantify these modifications, respectively the Eötvös effect and the oceanic tides; tidal forces due to differential gravitation on a spacecraft and an asteroid are also proposed as examples. Considerations about inertia are also given and some comments are made about a widespread, yet confusing, explanation of tides based on a centrifugal force. Finally, the expression of the potential energy of the tide-generating force is established rigorously in the appendix. (paper)

  17. Source modelling at the dawn of gravitational-wave astronomy

    Science.gov (United States)

    Gerosa, Davide

    2016-09-01

    The age of gravitational-wave astronomy has begun. Gravitational waves are propagating spacetime perturbations ("ripples in the fabric of space-time") predicted by Einstein's theory of General Relativity. These signals propagate at the speed of light and are generated by powerful astrophysical events, such as the merger of two black holes and supernova explosions. The first detection of gravitational waves was performed in 2015 with the LIGO interferometers. This constitutes a tremendous breakthrough in fundamental physics and astronomy: it is not only the first direct detection of such elusive signals, but also the first irrefutable observation of a black-hole binary system. The future of gravitational-wave astronomy is bright and loud: the LIGO experiments will soon be joined by a network of ground-based interferometers; the space mission eLISA has now been fully approved by the European Space Agency with a proof-of-concept mission called LISA Pathfinder launched in 2015. Gravitational-wave observations will provide unprecedented tests of gravity as well as a qualitatively new window on the Universe. Careful theoretical modelling of the astrophysical sources of gravitational-waves is crucial to maximize the scientific outcome of the detectors. In this Thesis, we present several advances on gravitational-wave source modelling, studying in particular: (i) the precessional dynamics of spinning black-hole binaries; (ii) the astrophysical consequences of black-hole recoils; and (iii) the formation of compact objects in the framework of scalar-tensor theories of gravity. All these phenomena are deeply characterized by a continuous interplay between General Relativity and astrophysics: despite being a truly relativistic messenger, gravitational waves encode details of the astrophysical formation and evolution processes of their sources. We work out signatures and predictions to extract such information from current and future observations. At the dawn of a revolutionary

  18. Induced polarization for characterizing and monitoring soil stabilization processes

    Science.gov (United States)

    Saneiyan, S.; Ntarlagiannis, D.; Werkema, D. D., Jr.

    2017-12-01

    Soil stabilization is critical in addressing engineering problems related to building foundation support, road construction and soil erosion among others. To increase soil strength, the stiffness of the soil is enhanced through injection/precipitation of a chemical agents or minerals. Methods such as cement injection and microbial induced carbonate precipitation (MICP) are commonly applied. Verification of a successful soil stabilization project is often challenging as treatment areas are spatially extensive and invasive sampling is expensive, time consuming and limited to sporadic points at discrete times. The geophysical method, complex conductivity (CC), is sensitive to mineral surface properties, hence a promising method to monitor soil stabilization projects. Previous laboratory work has established the sensitivity of CC on MICP processes. We performed a MICP soil stabilization projects and collected CC data for the duration of the treatment (15 days). Subsurface images show small, but very clear changes, in the area of MICP treatment; the changes observed fully agree with the bio-geochemical monitoring, and previous laboratory experiments. Our results strongly suggest that CC is sensitive to field MICP treatments. Finally, our results show that good quality data alone are not adequate for the correct interpretation of field CC data, at least when the signals are low. Informed data processing routines and the inverse modeling parameters are required to produce optimal results.

  19. Gravitation. [Book on general relativity

    Science.gov (United States)

    Misner, C. W.; Thorne, K. S.; Wheeler, J. A.

    1973-01-01

    This textbook on gravitation physics (Einstein's general relativity or geometrodynamics) is designed for a rigorous full-year course at the graduate level. The material is presented in two parallel tracks in an attempt to divide key physical ideas from more complex enrichment material to be selected at the discretion of the reader or teacher. The full book is intended to provide competence relative to the laws of physics in flat space-time, Einstein's geometric framework for physics, applications with pulsars and neutron stars, cosmology, the Schwarzschild geometry and gravitational collapse, gravitational waves, experimental tests of Einstein's theory, and mathematical concepts of differential geometry.

  20. Anisotropic solutions by gravitational decoupling

    Science.gov (United States)

    Ovalle, J.; Casadio, R.; da Rocha, R.; Sotomayor, A.

    2018-02-01

    We investigate the extension of isotropic interior solutions for static self-gravitating systems to include the effects of anisotropic spherically symmetric gravitational sources by means of the gravitational decoupling realised via the minimal geometric deformation approach. In particular, the matching conditions at the surface of the star with the outer Schwarzschild space-time are studied in great detail, and we describe how to generate, from a single physically acceptable isotropic solution, new families of anisotropic solutions whose physical acceptability is also inherited from their isotropic parent.

  1. Anisotropic solutions by gravitational decoupling

    Energy Technology Data Exchange (ETDEWEB)

    Ovalle, J. [Silesian University in Opava, Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Faculty of Philosophy and Science, Opava (Czech Republic); Universidad Simon Bolivar, Departamento de Fisica, Caracas (Venezuela, Bolivarian Republic of); Casadio, R. [Alma Mater Universita di Bologna, Dipartimento di Fisica e Astronomia, Bologna (Italy); Istituto Nazionale di Fisica Nucleare, Bologna (Italy); Rocha, R. da [Universidade Federal do ABC (UFABC), Centro de Matematica, Computacao e Cognicao, Santo Andre, SP (Brazil); Sotomayor, A. [Universidad de Antofagasta, Departamento de Matematicas, Antofagasta (Chile)

    2018-02-15

    We investigate the extension of isotropic interior solutions for static self-gravitating systems to include the effects of anisotropic spherically symmetric gravitational sources by means of the gravitational decoupling realised via the minimal geometric deformation approach. In particular, the matching conditions at the surface of the star with the outer Schwarzschild space-time are studied in great detail, and we describe how to generate, from a single physically acceptable isotropic solution, new families of anisotropic solutions whose physical acceptability is also inherited from their isotropic parent. (orig.)

  2. Gravitational radiation quadrupole formula is valid for gravitationally interacting systems

    International Nuclear Information System (INIS)

    Walker, M.; Will, C.M.

    1980-01-01

    An argument is presented for the validity of the quadrupole formula for gravitational radiation energy loss in the far field of nearly Newtonian (e.g., binary stellar) systems. This argument differs from earlier ones in that it determines beforehand the formal accuracy of approximation required to describe gravitationally self-interacting systems, uses the corresponding approximate equation of motion explicitly, and evaluate the appropriate asymptotic quantities by matching along the correct space-time light cones

  3. Particle transport model sensitivity on wave-induced processes

    Science.gov (United States)

    Staneva, Joanna; Ricker, Marcel; Krüger, Oliver; Breivik, Oyvind; Stanev, Emil; Schrum, Corinna

    2017-04-01

    Different effects of wind waves on the hydrodynamics in the North Sea are investigated using a coupled wave (WAM) and circulation (NEMO) model system. The terms accounting for the wave-current interaction are: the Stokes-Coriolis force, the sea-state dependent momentum and energy flux. The role of the different Stokes drift parameterizations is investigated using a particle-drift model. Those particles can be considered as simple representations of either oil fractions, or fish larvae. In the ocean circulation models the momentum flux from the atmosphere, which is related to the wind speed, is passed directly to the ocean and this is controlled by the drag coefficient. However, in the real ocean, the waves play also the role of a reservoir for momentum and energy because different amounts of the momentum flux from the atmosphere is taken up by the waves. In the coupled model system the momentum transferred into the ocean model is estimated as the fraction of the total flux that goes directly to the currents plus the momentum lost from wave dissipation. Additionally, we demonstrate that the wave-induced Stokes-Coriolis force leads to a deflection of the current. During the extreme events the Stokes velocity is comparable in magnitude to the current velocity. The resulting wave-induced drift is crucial for the transport of particles in the upper ocean. The performed sensitivity analyses demonstrate that the model skill depends on the chosen processes. The results are validated using surface drifters, ADCP, HF radar data and other in-situ measurements in different regions of the North Sea with a focus on the coastal areas. The using of a coupled model system reveals that the newly introduced wave effects are important for the drift-model performance, especially during extremes. Those effects cannot be neglected by search and rescue, oil-spill, transport of biological material, or larva drift modelling.

  4. Gravitational leptogenesis, C, CP and strong equivalence

    International Nuclear Information System (INIS)

    McDonald, Jamie I.; Shore, Graham M.

    2015-01-01

    The origin of matter-antimatter asymmetry is one of the most important outstanding problems at the interface of particle physics and cosmology. Gravitational leptogenesis (baryogenesis) provides a possible mechanism through explicit couplings of spacetime curvature to appropriate lepton (or baryon) currents. In this paper, the idea that these strong equivalence principle violating interactions could be generated automatically through quantum loop effects in curved spacetime is explored, focusing on the realisation of the discrete symmetries C, CP and CPT which must be broken to induce matter-antimatter asymmetry. The related issue of quantum corrections to the dispersion relation for neutrino propagation in curved spacetime is considered within a fully covariant framework.

  5. Gravitational leptogenesis, C, CP and strong equivalence

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, Jamie I.; Shore, Graham M. [Department of Physics, Swansea University,Swansea, SA2 8PP (United Kingdom)

    2015-02-12

    The origin of matter-antimatter asymmetry is one of the most important outstanding problems at the interface of particle physics and cosmology. Gravitational leptogenesis (baryogenesis) provides a possible mechanism through explicit couplings of spacetime curvature to appropriate lepton (or baryon) currents. In this paper, the idea that these strong equivalence principle violating interactions could be generated automatically through quantum loop effects in curved spacetime is explored, focusing on the realisation of the discrete symmetries C, CP and CPT which must be broken to induce matter-antimatter asymmetry. The related issue of quantum corrections to the dispersion relation for neutrino propagation in curved spacetime is considered within a fully covariant framework.

  6. Measuring Gravitational Flexion in ACS Clusters

    Science.gov (United States)

    Goldberg, David

    2005-07-01

    We propose measurement of the gravitational "Flexion" signal in ACS cluster images. The flexion, or "arciness" of a lensed background galaxy arises from variations in the lensing field. As a result, it is extremely sensitive to small scale perturbations in the field, and thus, to substructure in clusters. Moreover, because flexion represents gravitationally induced asymmetries in the lensed image, it is completely separable from traditional measurements of shear, which focus on the induced ellipticity of the image, and thus, the two signals may be extracted simultaneously. Since typical galaxies are roughly symmetric upon 180 degree rotation, even a small induced flexion can potentially produce a noticeable effect {Goldberg & Bacon, 2005}. We propose the measurement of substructure within approximately 4 clusters with high-quality ACS data, and will further apply a test of a new tomographic technique whereby comparisons of lensed arcs at different redshifts may be used to estimate the background cosmology, and thus place constraints on the equation of state of dark energy.

  7. Stochastic backgrounds of gravitational waves

    International Nuclear Information System (INIS)

    Maggiore, M.

    2001-01-01

    We review the motivations for the search for stochastic backgrounds of gravitational waves and we compare the experimental sensitivities that can be reached in the near future with the existing bounds and with the theoretical predictions. (author)

  8. Gravitational scattering of electromagnetic radiation

    Science.gov (United States)

    Brooker, J. T.; Janis, A. I.

    1980-01-01

    The scattering of electromagnetic radiation by linearized gravitational fields is studied to second order in a perturbation expansion. The incoming electromagnetic radiation can be of arbitrary multipole structure, and the gravitational fields are also taken to be advanced fields of arbitrary multipole structure. All electromagnetic multipole radiation is found to be scattered by gravitational monopole and time-varying dipole fields. No case has been found, however, in which any electromagnetic multipole radiation is scattered by gravitational fields of quadrupole or higher-order multipole structure. This lack of scattering is established for infinite classes of special cases, and is conjectured to hold in general. The results of the scattering analysis are applied to the case of electromagnetic radiation scattered by a moving mass. It is shown how the mass and velocity may be determined by a knowledge of the incident and scattered radiation.

  9. Highlights in gravitation and cosmology

    International Nuclear Information System (INIS)

    Iyer, B.R.; Kembhavi, Ajit; Narlikar, J.V.; Vishveshwara, C.V.

    1988-01-01

    This book assesses research into gravitation and cosmology by examining the subject from various viewpoints: the classical and quantum pictures, along with the cosmological and astrophysical applications. There are 35 articles by experts of international standing. Each defines the state of the art and contains a concise summary of our present knowledge of a facet of gravitational physics. These edited papers are based on those first given at an international conference held in Goa, India at the end of 1987. The following broad areas are covered: classical relativity, quantum gravity, cosmology, black holes, compact objects, gravitational radiation and gravity experiments. In this volume there are also summaries of discussions on the following special topics: exact solutions of cosmological equations, mathematical aspects of general relativity, the early universe, and quantum gravity. For research workers in cosmology and gravitation this reference book provides a broad view of present achievements and current problems. (author)

  10. A new theory of gravitation

    International Nuclear Information System (INIS)

    Logunov, A.A.

    1989-01-01

    The author believes that the General Relativity Theory (GRT) suffers from a substantial deficiency since it ignors the fundamental laws of conservation of energy. Einstein neglected the classical concept of the field due to his belief in the truth of the principle of equivalence between forces of inertid gravitation. This equivalence leads, as the author says, to nonequivalence of these forces, making GRT logically contradictory from the physical point of view. The author considers GRT as a certain stage in the course of the study of space-time and gravitation, and suggests a new theory called the Relativistic Theory of Gravitation (RTG) which obeys the fundamental laws of conservation, and which is justified in some of its aspects by astronomical observations. RTG does not suffer from some deficiencies met in Einsteins theory. One is nonunique predictions of gravitation effects within the boundaries of the solar system. Also, RTG refuses some hypothesis as that of black holes. 7 refs

  11. Are the gravitational waves quantised?

    International Nuclear Information System (INIS)

    Lovas, I.

    1998-01-01

    The question whether gravitational waves are quantised or not can be investigated by the help of correlation measurements. If the gravitational waves are classical objects then the value of their correlation function is 1. However, if they are quantised, then there exist two possibilities: the gravitational waves are either completely coherent, then the correlation function is again 1, or they are partially coherent, then the correlation function is expected to deviate from 1. If the gravitational waves are generated by the change of the background metrics then they can be in a squeezed state. In a squeezed state there is a chance for the correlation between the phase of the wave and the quantum fluctuations. (author)

  12. Heuristic introduction to gravitational waves

    International Nuclear Information System (INIS)

    Sandberg, V.D.

    1982-01-01

    The purpose of this article is to provide a rough and somewhat heuristic theoretical background and introduction to gravitational radiation, its generation, and its detection based on Einstein's general theory of relativity

  13. Academic Training: Gravitational Waves Astronomy

    CERN Multimedia

    2006-01-01

    2006-2007 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 16, 17, 18 October from 11:00 to 12:00 - Main Auditorium, bldg. 500 Gravitational Waves Astronomy M. LANDRY, LIGO Hanford Observatory, Richland, USA Gravitational wave astronomy is expected to become an observational field within the next decade. First direct detection of gravitational waves is possible with existing terrestrial-based detectors, and highly probable with proposed upgrades. In this three-part lecture series, we give an overview of the field, including material on gravitional wave sources, detection methods, some details of interferometric detectors, data analysis methods, and current results from observational data-taking runs of the LIGO and GEO projects. ENSEIGNEMENT ACADEMIQUE ACADEMIC TRAINING Françoise Benz 73127 academic.training@cern.ch If you wish to participate in one of the following courses, please tell to your supervisor and apply electronically from the course description pages that can be found on the Web at: http://www...

  14. Gravitational waves and electrodynamics: new perspectives.

    Science.gov (United States)

    Cabral, Francisco; Lobo, Francisco S N

    2017-01-01

    Given the recent direct measurement of gravitational waves (GWs) by the LIGO-VIRGO collaboration, the coupling between electromagnetic fields and gravity have a special relevance since it opens new perspectives for future GW detectors and also potentially provides information on the physics of highly energetic GW sources. We explore such couplings using the field equations of electrodynamics on (pseudo) Riemann manifolds and apply it to the background of a GW, seen as a linear perturbation of Minkowski geometry. Electric and magnetic oscillations are induced that propagate as electromagnetic waves and contain information as regards the GW which generates them. The most relevant results are the presence of longitudinal modes and dynamical polarization patterns of electromagnetic radiation induced by GWs. These effects might be amplified using appropriate resonators, effectively improving the signal to noise ratio around a specific frequency. We also briefly address the generation of charge density fluctuations induced by GWs and the implications for astrophysics.

  15. Gravitational waves and electrodynamics: new perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Cabral, Francisco; Lobo, Francisco S.N. [Faculdade de Ciencias da Universidade de Lisboa, Instituto de Astrofisica e Ciencias do Espaco, Lisbon (Portugal)

    2017-04-15

    Given the recent direct measurement of gravitational waves (GWs) by the LIGO-VIRGO collaboration, the coupling between electromagnetic fields and gravity have a special relevance since it opens new perspectives for future GW detectors and also potentially provides information on the physics of highly energetic GW sources. We explore such couplings using the field equations of electrodynamics on (pseudo) Riemann manifolds and apply it to the background of a GW, seen as a linear perturbation of Minkowski geometry. Electric and magnetic oscillations are induced that propagate as electromagnetic waves and contain information as regards the GW which generates them. The most relevant results are the presence of longitudinal modes and dynamical polarization patterns of electromagnetic radiation induced by GWs. These effects might be amplified using appropriate resonators, effectively improving the signal to noise ratio around a specific frequency. We also briefly address the generation of charge density fluctuations induced by GWs and the implications for astrophysics. (orig.)

  16. Shearfree cylindrical gravitational collapse

    International Nuclear Information System (INIS)

    Di Prisco, A.; Herrera, L.; MacCallum, M. A. H.; Santos, N. O.

    2009-01-01

    We consider diagonal cylindrically symmetric metrics, with an interior representing a general nonrotating fluid with anisotropic pressures. An exterior vacuum Einstein-Rosen spacetime is matched to this using Darmois matching conditions. We show that the matching conditions can be explicitly solved for the boundary values of metric components and their derivatives, either for the interior or exterior. Specializing to shearfree interiors, a static exterior can only be matched to a static interior, and the evolution in the nonstatic case is found to be given in general by an elliptic function of time. For a collapsing shearfree isotropic fluid, only a Robertson-Walker dust interior is possible, and we show that all such cases were included in Cocke's discussion. For these metrics, Nolan and Nolan have shown that the matching breaks down before collapse is complete, and Tod and Mena have shown that the spacetime is not asymptotically flat in the sense of Berger, Chrusciel, and Moncrief. The issues about energy that then arise are revisited, and it is shown that the exterior is not in an intrinsic gravitational or superenergy radiative state at the boundary.

  17. Quantum biological gravitational wave detectors

    International Nuclear Information System (INIS)

    Kopvillem, U.Kh.

    1985-01-01

    A possibility of producing biological detectors of gravitational waves is considered. High sensitivity of biological systems to outer effects can be ensured by existence of molecule subgroups in Dicke states. Existence of clusters in Dicke state-giant electric dipoles (GED) is supposed in the Froehlich theory. Comparison of biological and physical detectors shows that GED systems have unique properties for detection of gravitational waves if the reception range is narrow

  18. General relativity and gravitation, 1989

    International Nuclear Information System (INIS)

    Ashby, N.; Bartlett, D.F.; Wyss, W.

    1990-01-01

    This volume records the lectures and symposia of the 12th International Conference on General Relativity and Gravitation. Plenary lecturers reviewed the major advances since the previous conference in 1986. The reviews cover classical and quantum theory of gravity, colliding gravitational waves, gravitational lensing, relativistic effects on pulsars, tests of the inverse square law, numerical relativity, cosmic microwave background radiation, experimental tests of gravity theory, gravitational wave detectors, and cosmology. The plenary lectures are complemented by summaries of symposia, provided by the chairmen. Almost 700 contributed papers were presented at these and they cover an even wider range of topics than the plenary talks. The book provides a comprehensive guide to research activity in both experimental and theoretical gravitation and its applications in astrophysics and cosmology. It will be essential reading for research workers in these fields, as well as theoretical and experimental physicists, astronomers, and mathematicians who wish to be acquainted with modern developments in gravitational theory and general relativity. All the papers and summaries of the workshop sessions are indexed separately. (16 united talks, 20 workshop sessions). (author)

  19. Nuclear Quantum Gravitation - The Correct Theory

    Science.gov (United States)

    Kotas, Ronald

    2016-03-01

    Nuclear Quantum Gravitation provides a clear, definitive Scientific explanation of Gravity and Gravitation. It is harmonious with Newtonian and Quantum Mechanics, and with distinct Scientific Logic. Nuclear Quantum Gravitation has 10 certain, Scientific proofs and 21 more good indications. With this theory the Physical Forces are obviously Unified. See: OBSCURANTISM ON EINSTEIN GRAVITATION? http://www.santilli- Foundation.org/inconsistencies-gravitation.php and Einstein's Theory of Relativity versus Classical Mechanics http://www.newtonphysics.on.ca/einstein/

  20. Bipolar outflows as a repulsive gravitational phenomenon - Azimuthally Symmetric Theory of Gravitation (II)

    International Nuclear Information System (INIS)

    Nyambuya, Golden Gadzirayi

    2010-01-01

    This paper is part of a series on the Azimuthally Symmetric Theory of Gravitation (ASTG). This theory is built on Laplace-Poisson's well known equation and it has been shown that the ASTG is capable of explaining, from a purely classical physics standpoint, the precession of the perihelion of solar planets as a consequence of the azimuthal symmetry emerging from the spin of the Sun. This symmetry has and must have an influence on the emergent gravitational field. We show herein that the emergent equations from the ASTG, under some critical conditions determined by the spin, do possess repulsive gravitational fields in the polar regions of the gravitating body in question. This places the ASTG on an interesting pedestal to infer the origins of outflows as a repulsive gravitational phenomenon. Outflows are a ubiquitous phenomenon found in star forming systems and their true origin is a question yet to be settled. Given the current thinking on their origin, the direction that the present paper takes is nothing short of an asymptotic break from conventional wisdom; at the very least, it is a complete paradigm shift because gravitation is not at all associated with this process, but rather it is thought to be an all-attractive force that only tries to squash matter together onto a single point. Additionally, we show that the emergent Azimuthally Symmetric Gravitational Field from the ASTG strongly suggests a solution to the supposed Radiation Problem that is thought to be faced by massive stars in their process of formation. That is, at ∼ 8-10 M sun , radiation from the nascent star is expected to halt the accretion of matter. We show that in-falling material will fall onto the equatorial disk and from there, this material will be channeled onto the forming star via the equatorial plane, thus accretion of mass continues well past the value of ∼ 8-10 M sun , albeit via the disk. Along the equatorial plane, the net force (with the radiation force included) on any

  1. General projective relativity and the vector-tensor gravitational field

    International Nuclear Information System (INIS)

    Arcidiacono, G.

    1986-01-01

    In the general projective relativity, the induced 4-dimensional metric is symmetric in three cases, and we obtain the vector-tensor, the scalar-tensor, and the scalar-vector-tensor theories of gravitation. In this work we examine the vector-tensor theory, similar to the Veblen's theory, but with a different physical interpretation

  2. Electromagnetic Waves in a Uniform Gravitational Field and Planck's Postulate

    Science.gov (United States)

    Acedo, Luis; Tung, Michael M.

    2012-01-01

    The gravitational redshift forms the central part of the majority of the classical tests for the general theory of relativity. It could be successfully checked even in laboratory experiments on the earth's surface. The standard derivation of this effect is based on the distortion of the local structure of spacetime induced by large masses. The…

  3. Gravitational waves from rotating neutron stars and evaluation of fast chirp transform techniques

    CERN Document Server

    Strohmayer, T E

    2002-01-01

    X-ray observations suggest that neutron stars in low mass x-ray binaries (LMXB) are rotating with frequencies in the range 300-600 Hz. These spin rates are significantly less than the break-up rates for essentially all realistic neutron star equations of state, suggesting that some process may limit the spin frequencies of accreting neutron stars to this range. If the accretion-induced spin up torque is in equilibrium with gravitational radiation losses, these objects could be interesting sources of gravitational waves. I present a brief summary of current measurements of neutron star spins in LMXBs based on the observations of high-Q oscillations during thermonuclear bursts (so-called 'burst oscillations'). Further measurements of neutron star spins will be important in exploring the gravitational radiation hypothesis in more detail. To this end, I also present a study of fast chirp transform (FCT) techniques as described by Jenet and Prince (Prince T A and Jenet F A 2000 Phys. Rev. D 62 122001) in the conte...

  4. Gravitational wave background from reheating after hybrid inflation

    International Nuclear Information System (INIS)

    Garcia-Bellido, Juan; Figueroa, Daniel G.; Sastre, Alfonso

    2008-01-01

    The reheating of the Universe after hybrid inflation proceeds through the nucleation and subsequent collision of large concentrations of energy density in the form of bubblelike structures moving at relativistic speeds. This generates a significant fraction of energy in the form of a stochastic background of gravitational waves, whose time evolution is determined by the successive stages of reheating: First, tachyonic preheating makes the amplitude of gravity waves grow exponentially fast. Second, bubble collisions add a new burst of gravitational radiation. Third, turbulent motions finally sets the end of gravitational waves production. From then on, these waves propagate unimpeded to us. We find that the fraction of energy density today in these primordial gravitational waves could be significant for grand unified theory (GUT)-scale models of inflation, although well beyond the frequency range sensitivity of gravitational wave observatories like LIGO, LISA, or BBO. However, low-scale models could still produce a detectable signal at frequencies accessible to BBO or DECIGO. For comparison, we have also computed the analogous gravitational wave background from some chaotic inflation models and obtained results similar to those found by other groups. The discovery of such a background would open a new observational window into the very early universe, where the details of the process of reheating, i.e. the big bang, could be explored. Moreover, it could also serve in the future as a new experimental tool for testing the inflationary paradigm

  5. The impact of particle production on gravitational baryogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Lima, J.A.S., E-mail: jas.lima@iag.usp.br [Departamento de Astronomia, Universidade de São Paulo, Rua do Matão 1226, 05508-900, São Paulo (Brazil); Singleton, D., E-mail: dougs@csufresno.edu [Department of Physics, California State University Fresno, Fresno, CA 93740-8031 (United States); ICTP South American Institute for Fundamental Research, UNESP – Univ. Estadual Paulista, Rua Dr. Bento T. Ferraz 271, 01140-070, São Paulo, SP (Brazil); Institute of Experimental and Theoretical Physics Al-Farabi KazNU, Almaty, 050040 (Kazakhstan)

    2016-11-10

    Baryogenesis driven by curvature effects is investigated by taking into account gravitationally induced particle production in the very early Universe. In our scenario, the baryon asymmetry is generated dynamically during an inflationary epoch powered by ultra-relativistic particles. The adiabatic particle production rate provides both the needed negative pressure to accelerate the radiation dominated Universe and a non-zero chemical potential which distinguishes baryons and anti-baryons thereby producing a baryon asymmetry in agreement with the observed value. Reciprocally, the present day asymmetry may be used to determine the inflationary scale at early times. Successful gravitational baryogenesis is dynamically generated for many different choices of the relevant model parameters.

  6. On Assumptions in Development of a Mathematical Model of Thermo-gravitational Convection in the Large Volume Process Tanks Taking into Account Fermentation

    Directory of Open Access Journals (Sweden)

    P. M. Shkapov

    2015-01-01

    Full Text Available The paper provides a mathematical model of thermo-gravity convection in a large volume vertical cylinder. The heat is removed from the product via the cooling jacket at the top of the cylinder. We suppose that a laminar fluid motion takes place. The model is based on the NavierStokes equation, the equation of heat transfer through the wall, and the heat transfer equation. The peculiarity of the process in large volume tanks was the distribution of the physical parameters of the coordinates that was taken into account when constructing the model. The model corresponds to a process of wort beer fermentation in the cylindrical-conical tanks (CCT. The CCT volume is divided into three zones and for each zone model equations was obtained. The first zone has an annular cross-section and it is limited to the height by the cooling jacket. In this zone the heat flow from the cooling jacket to the product is uppermost. Model equation of the first zone describes the process of heat transfer through the wall and is presented by linear inhomogeneous differential equation in partial derivatives that is solved analytically. For the second and third zones description there was a number of engineering assumptions. The fluid was considered Newtonian, viscous and incompressible. Convective motion considered in the Boussinesq approximation. The effect of viscous dissipation is not considered. The topology of fluid motion is similar to the cylindrical Poiseuille. The second zone model consists of the Navier-Stokes equations in cylindrical coordinates with the introduction of a simplified and the heat equation in the liquid layer. The volume that is occupied by an upward convective flow pertains to the third area. Convective flows do not mix and do not exchange heat. At the start of the process a medium has the same temperature and a zero initial velocity in the whole volume that allows us to specify the initial conditions for the process. The paper shows the

  7. Addendum. Relation for the Light Absorption in the Presence of Gravitation Field

    OpenAIRE

    R.Vlokh; M.Kostyrko

    2005-01-01

    We argue for the validity of relation for electromagnetic wave electric field derived by us earlier. It includes an imaginary part responsible for the absorption induced by gravitation field of spherically symmetric mass.

  8. A new data-processing approach to study particle motion using ultrafast X-ray tomography scanner: case study of gravitational mass flow

    Science.gov (United States)

    Waktola, Selam; Bieberle, Andre; Barthel, Frank; Bieberle, Martina; Hampel, Uwe; Grudzień, Krzysztof; Babout, Laurent

    2018-04-01

    In most industrial products, granular materials are often required to flow under gravity in various kinds of silo shapes and usually through an outlet in the bottom. There are several interrelated parameters which affect the flow, such as internal friction, bulk and packing density, hopper geometry, and material type. Due to the low-spatial resolution of electrical capacitance tomography or scanning speed limitation of standard X-ray CT systems, it is extremely challenging to measure the flow velocity and possible centrifugal effects of granular materials flow effectively. However, ROFEX (ROssendorf Fast Electron beam X-ray tomography) opens new avenues of granular flow investigation due to its very high temporal resolution. This paper aims to track particle movements and evaluate the local grain velocity during silo discharging process in the case of mass flow. The study has considered the use of the Seramis material, which can also serve as a type of tracer particles after impregnation, due to its porous nature. The presented novel image processing and analysis approach allows satisfyingly measuring individual particle velocities but also tracking their lateral movement and three-dimensional rotations.

  9. A new geometrical gravitational theory

    International Nuclear Information System (INIS)

    Obata, T.; Chiba, J.; Oshima, H.

    1981-01-01

    A geometrical gravitational theory is developed. The field equations are uniquely determined apart from one unknown dimensionless parameter ω 2 . It is based on an extension of the Weyl geometry, and by the extension the gravitational coupling constant and the gravitational mass are made to be dynamical and geometrical. The fundamental geometrical objects in the theory are a metric gsub(μν) and two gauge scalars phi and psi. The theory satisfies the weak equivalence principle, but breaks the strong one generally. u(phi, psi) = phi is found out on the assumption that the strong one keeps holding good at least for bosons of low spins. Thus there is the simple correspondence between the geometrical objects and the gravitational objects. Since the theory satisfies the weak one, the inertial mass is also dynamical and geometrical in the same way as is the gravitational mass. Moreover, the cosmological term in the theory is a coscalar of power -4 algebraically made of psi and u(phi, psi), so it is dynamical, too. Finally spherically symmetric exact solutions are given. The permissible range of the unknown parameter ω 2 is experimentally determined by applying the solutions to the solar system. (author)

  10. Modified entropic gravitation in superconductors

    International Nuclear Information System (INIS)

    Matos, Clovis Jacinto de

    2012-01-01

    Verlinde recently developed a theoretical account of gravitation in terms of an entropic force. The central element in Verlinde’s derivation is information and its relation with entropy through the holographic principle. The application of this approach to the case of superconductors requires to take into account that information associated with superconductor’s quantum vacuum energy is not stored on Planck size surface elements, but in four volume cells with Planck-Einstein size. This has profound consequences on the type of gravitational force generated by the quantum vacuum condensate in superconductors, which is closely related with the cosmological repulsive acceleration responsible for the accelerated expansion of the Universe. Remarkably this new gravitational type force depends on the level of breaking of the weak equivalence principle for cooper pairs in a given superconducting material, which was previously derived by the author starting from similar principles. It is also shown that this new gravitational force can be interpreted as a surface force. The experimental detection of this new repulsive gravitational-type force appears to be challenging.

  11. Gravitational waves from supernova matter

    International Nuclear Information System (INIS)

    Scheidegger, S; Whitehouse, S C; Kaeppeli, R; Liebendoerfer, M

    2010-01-01

    We have performed a set of 11 three-dimensional magnetohydrodynamical (MHD) core-collapse supernova simulations in order to investigate the dependences of the gravitational wave signal on the progenitor's initial conditions. We study the effects of the initial central angular velocity and different variants of neutrino transport. Our models are started up from a 15M o-dot progenitor and incorporate an effective general relativistic gravitational potential and a finite temperature nuclear equation of state. Furthermore, the electron flavour neutrino transport is tracked by efficient algorithms for the radiative transfer of massless fermions. We find that non- and slowly rotating models show gravitational wave emission due to prompt- and lepton driven convection that reveals details about the hydrodynamical state of the fluid inside the protoneutron stars. Furthermore we show that protoneutron stars can become dynamically unstable to rotational instabilities at T/|W| values as low as ∼2% at core bounce. We point out that the inclusion of deleptonization during the postbounce phase is very important for the quantitative gravitational wave (GW) prediction, as it enhances the absolute values of the gravitational wave trains up to a factor of ten with respect to a lepton-conserving treatment.

  12. Relic gravitational waves and cosmology

    International Nuclear Information System (INIS)

    Grishchuk, Leonid P

    2005-01-01

    The paper begins with a brief recollection of interactions of the author with Ya B Zeldovich in the context of the study of relic gravitational waves. The principles and early results on the quantum-mechanical generation of cosmological perturbations are then summarized. The expected amplitudes of relic gravitational waves differ in various frequency windows, and therefore the techniques and prospects of their detection are distinct. One section of the paper describes the present state of efforts in direct detection of relic gravitational waves. Another section is devoted to indirect detection via the anisotropy and polarization measurements of the cosmic microwave background (CMB) radiation. It is emphasized throughout the paper that the inference about the existence and expected amount of relic gravitational waves is based on a solid theoretical foundation and the best available cosmological observations. It is also explained in great detail what went wrong with the so-called 'inflationary gravitational waves', whose amount is predicted by inflationary theorists to be negligibly small, thus depriving them of any observational significance. (reviews of topical problems)

  13. Inflationary gravitational waves in collapse scheme models

    Energy Technology Data Exchange (ETDEWEB)

    Mariani, Mauro, E-mail: mariani@carina.fcaglp.unlp.edu.ar [Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque S/N, 1900 La Plata (Argentina); Bengochea, Gabriel R., E-mail: gabriel@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC 67, Suc. 28, 1428 Buenos Aires (Argentina); León, Gabriel, E-mail: gleon@df.uba.ar [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria – Pab. I, 1428 Buenos Aires (Argentina)

    2016-01-10

    The inflationary paradigm is an important cornerstone of the concordance cosmological model. However, standard inflation cannot fully address the transition from an early homogeneous and isotropic stage, to another one lacking such symmetries corresponding to our present universe. In previous works, a self-induced collapse of the wave function has been suggested as the missing ingredient of inflation. Most of the analysis regarding the collapse hypothesis has been solely focused on the characteristics of the spectrum associated to scalar perturbations, and within a semiclassical gravity framework. In this Letter, working in terms of a joint metric-matter quantization for inflation, we calculate, for the first time, the tensor power spectrum and the tensor-to-scalar ratio corresponding to the amplitude of primordial gravitational waves resulting from considering a generic self-induced collapse.

  14. Gravitational waves: A challenge to theoretical astrophysics

    International Nuclear Information System (INIS)

    Ferrari, V.; Miller, J.C.; Rezzolla, L.

    2001-01-01

    During the 20th century, new windows on the Universe have been opened by the advent of radio astronomy and X-ray astronomy and these, together with the great advances in optical astronomy (both from the Earth's surface and from space), have revolutionized our understanding of the Universe and the way in which it works. Now, as we enter the twenty-first century, we await the opening of another new window - that provided by gravitational waves - which will allow us a closer 'view' of black holes and neutron stars, as well as providing a new probe of processes in the very early Universe. This is an exciting prospect but one which poses a serious challenge to theoretical astrophysics. The new generation of detectors (both laser interferometers and resonant detectors) require input from theoreticians regarding the possible mechanisms for generation of gravitational waves by astronomical sources and predictions of the waveforms produced. This input is essential in order both to tune the parameters of the detectors and to provide templates for use in extracting the tiny gravitational-wave signals from the ambient noise. Also, we need to understand how gravitational wave data, when it arrives, could be used in order to obtain information about the nature of the sources and about their dynamical evolution as well as, perhaps, giving deeper insights into some questions of fundamental physics by means of probing the state of matter under the extreme conditions of energy and pressure found in the interior of neutron stars and in the very early universe. This can provide opportunities beyond the capabilities of experiments carried out in terrestrial laboratories. For a week at the beginning of June 2000, 106 scientists from 28 countries came to Trieste for a meeting whose aim was to present a survey of the current status of the response of theoreticians to the challenge described above, as well as including progress reports on the different types of detector. The meeting was a

  15. Chirality and gravitational parity violation.

    Science.gov (United States)

    Bargueño, Pedro

    2015-06-01

    In this review, parity-violating gravitational potentials are presented as possible sources of both true and false chirality. In particular, whereas phenomenological long-range spin-dependent gravitational potentials contain both truly and falsely chiral terms, it is shown that there are models that extend general relativity including also coupling of fermionic degrees of freedom to gravity in the presence of torsion, which give place to short-range truly chiral interactions similar to that usually considered in molecular physics. Physical mechanisms which give place to gravitational parity violation together with the expected size of the effects and their experimental constraints are discussed. Finally, the possible role of parity-violating gravity in the origin of homochirality and a road map for future research works in quantum chemistry is presented. © 2015 Wiley Periodicals, Inc.

  16. Post-Newtonian gravitational bremsstrahlung

    International Nuclear Information System (INIS)

    Turner, M.; Will, C.M.

    1978-01-01

    We present formulae and numerical results for the gravitational radiation emitted during a low-deflection encounter between two massive bodies (''gravitational bremsstrahlung''). Our results are valid through post-Newtonian order within general relativity. We discuss in detail the gravitational waveform (transverse-traceless part of the metric perturbation tensor), the toal luminosity and total emitted energy, the angular distribution of emitted energy (antenna pattern), and the frequency spectrum. We also present a method of ''boosting'' the accuracy of these quantities to post-3/2-Newtonian order. A numerical comparison of our results with those of Peters and of Kovacs and Thorne shows that the post-Newtonian method is reliable to better than 0.1% at v=0.1c, to a few percent at v=0.35c, and to 10--20% at v=0.5c. We also compare our results with those of Smarr

  17. Sparse representation of Gravitational Sound

    Science.gov (United States)

    Rebollo-Neira, Laura; Plastino, A.

    2018-03-01

    Gravitational Sound clips produced by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Massachusetts Institute of Technology (MIT) are considered within the particular context of data reduction. We advance a procedure to this effect and show that these types of signals can be approximated with high quality using significantly fewer elementary components than those required within the standard orthogonal basis framework. Furthermore, a local measure sparsity is shown to render meaningful information about the variation of a signal along time, by generating a set of local sparsity values which is much smaller than the dimension of the signal. This point is further illustrated by recourse to a more complex signal, generated by Milde Science Communication to divulge Gravitational Sound in the form of a ring tone.

  18. Experimental studies of the gravitational agglomeration of aerosols. Pt. 2

    International Nuclear Information System (INIS)

    Ball, M.H.E.; Longley, K.A.; Mitchell, J.P.; Ketchell, N.

    1990-12-01

    Experiments have been performed to investigate the influence of gravitational agglomeration as an aerosol depletion process in a small containment vessel. The resulting data will aid in the development of computer codes that describe aerosol transport processes following severe reactor accidents. (author)

  19. Coherent network detection of gravitational waves: the redundancy veto

    International Nuclear Information System (INIS)

    Wen Linqing; Schutz, Bernard F

    2005-01-01

    A network of gravitational wave detectors is called redundant if, given the direction to a source, the strain induced by a gravitational wave in one or more of the detectors can be fully expressed in terms of the strain induced in others in the network. Because gravitational waves have only two polarizations, any network of three or more differently oriented interferometers with similar observing bands is redundant. The three-armed LISA space interferometer has three outputs that are redundant at low frequencies. The two aligned LIGO interferometers at Hanford WA are redundant, and the LIGO detector at Livingston LA is nearly redundant with either of the Hanford detectors. Redundant networks have a powerful veto against spurious noise, a linear combination of the detector outputs that contains no gravitational wave signal. For LISA, this 'null' output is known as the Sagnac mode, and its use in discriminating between detector noise and a cosmological gravitational wave background is well understood. But the usefulness of the null veto for ground-based detector networks has been ignored until now. We show that it should make it possible to discriminate in a model-independent way between real gravitational waves and accidentally coincident non-Gaussian noise 'events' in redundant networks of two or more broadband detectors. It has been shown that with three detectors, the null output can even be used to locate the direction to the source, and then two other linear combinations of detector outputs give the optimal 'coherent' reconstruction of the two polarization components of the signal. We discuss briefly the implementation of such a detection strategy in realistic networks, where signals are weak, detector calibration is a significant uncertainty, and the various detectors may have different (but overlapping) observing bands

  20. Gravitational-wave mediated preheating

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, Stephon [Center for Cosmic Origins and Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States); Cormack, Sam, E-mail: samuel.c.cormack.gr@dartmouth.edu [Center for Cosmic Origins and Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States); Marcianò, Antonino [Center for Field Theory and Particle Physics & Department of Physics, Fudan University, 200433 Shanghai (China); Yunes, Nicolás [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States)

    2015-04-09

    We propose a new preheating mechanism through the coupling of the gravitational field to both the inflaton and matter fields, without direct inflaton–matter couplings. The inflaton transfers power to the matter fields through interactions with gravitational waves, which are exponentially enhanced due to an inflation–graviton coupling. One such coupling is the product of the inflaton to the Pontryagin density, as in dynamical Chern–Simons gravity. The energy scales involved are constrained by requiring that preheating happens fast during matter domination.

  1. Linear interaction of gravitational waves

    International Nuclear Information System (INIS)

    Ciubotariu, C.D.

    1992-01-01

    Starting with the linearized Einstein equations written in the same form as Maxwell equations, a damping term is found in the wave equation. The analogy with the propagation of the electromagnetic wave in ohmic media is obvious if we introduce an 'ohmic relation' for gravitational interaction. The possibility of the amplification of gravitational waves by a suitable choice of the velocity field of a dust ('dust with negative viscosity'), for example by the use of the free-electron laser principle, is indicated. (Author)

  2. Astrophysical sources of gravitational waves

    Energy Technology Data Exchange (ETDEWEB)

    Losurdo, G. E-mail: losurdo@galileo.pi.infn.it

    2000-05-01

    The interferometric detectors of gravitational waves (GW) (such as VIRGO and LIGO) will search for events in a frequency band within a few Hz and a few kHz, where several sources are expected to emit. In this talk we outline briefly the current theoretical knowledge on the emission of GW in events such as the coalescence of compact binaries, the gravitational collapse, the spinning of a neutron stars. Expected amplitudes are compared with the target sensitivity of the VIRGO/LIGO interferometric detectors.

  3. General relativity and gravitational waves

    CERN Document Server

    Weber, Johanna

    1961-01-01

    An internationally famous physicist and electrical engineer, the author of this text was a pioneer in the investigation of gravitational waves. Joseph Weber's General Relativity and Gravitational Waves offers a classic treatment of the subject. Appropriate for upper-level undergraduates and graduate students, this text remains ever relevant. Brief but thorough in its introduction to the foundations of general relativity, it also examines the elements of Riemannian geometry and tensor calculus applicable to this field.Approximately a quarter of the contents explores theoretical and experimenta

  4. The covariant entropy bound in gravitational collapse

    International Nuclear Information System (INIS)

    Gao, Sijie; Lemos, Jose P. S.

    2004-01-01

    We study the covariant entropy bound in the context of gravitational collapse. First, we discuss critically the heuristic arguments advanced by Bousso. Then we solve the problem through an exact model: a Tolman-Bondi dust shell collapsing into a Schwarzschild black hole. After the collapse, a new black hole with a larger mass is formed. The horizon, L, of the old black hole then terminates at the singularity. We show that the entropy crossing L does not exceed a quarter of the area of the old horizon. Therefore, the covariant entropy bound is satisfied in this process. (author)

  5. Black Holes and Gravitational Properties of Antimatter

    CERN Document Server

    Hajdukovic, D

    2006-01-01

    We speculate about impact of antigravity (i.e. gravitational repulsion between matter and antimatter) on the creation and emission of particles by a black hole. If antigravity is present a black hole made of matter may radiate particles as a black body, but this shouldn't be true for antiparticles. It may lead to radical change of radiation process predicted by Hawking and should be taken into account in preparation of the attempt to create and study mini black holes at CERN. Gravity, including antigravity is more than ever similar to electrodynamics and such similarity with a successfully quantized interaction may help in quantization of gravity.

  6. Morphosedimentary and hydrographic features of the northern Argentine margin: The interplay between erosive, depositional and gravitational processes and its conceptual implications

    Science.gov (United States)

    Preu, Benedict; Hernández-Molina, F. Javier; Violante, Roberto; Piola, Alberto R.; Paterlini, C. Marcelo; Schwenk, Tilmann; Voigt, Ines; Krastel, Sebastian; Spiess, Volkhard

    2013-05-01

    Bottom currents and their margin-shaping character became a central aspect in the research field of sediment dynamics and paleoceanography during the last decades due to their potential to form large contourite depositional systems (CDS), consisting of both erosive and depositional features. A major CDS at the northern Argentine continental margin was studied off the Rio de la Plata River by means of seismo- and hydro-acoustic methods including conventional and high-resolution seismic, parametric echosounder and single and swath bathymetry. Additionally, hydrographic data were considered allowing jointly interpretation of morphosedimentary features and the oceanographic framework, which is dominated by the presence of the dynamic and highly variable Brazil-Malvinas Confluence. We focus on three regional contouritic terraces identified on the slope in the vicinity of the Mar del Plata Canyon. The shallowest one, the La Plata Terrace (˜500 m), is located at the Brazil Current/Antarctic Intermediate Water interface characterized by its deep and distinct thermocline. In ˜1200 m water depth the Ewing Terrace correlates with the Antarctic Intermediate Water/Upper Circumpolar Deep Water interface. At the foot of the slope in ˜3500 m the Necochea Terrace marks the transition between Lower Circumpolar Deep Water and Antarctic Bottom Water during glacial times. Based on these correlations, a comprehensive conceptual model is proposed, in which the onset and evolution of contourite terraces is controlled by short- and long-term variations of water mass interfaces. We suggest that the terrace genesis is strongly connected to the turbulent current pattern typical for water mass interfaces. Furthermore, the erosive processes necessary for terrace formation are probably enhanced due to internal waves, which are generated along strong density gradients typical for water mass interfaces. The terraces widen through time due to locally focused, partly helical currents along the

  7. Mental imagery of gravitational motion.

    Science.gov (United States)

    Gravano, Silvio; Zago, Myrka; Lacquaniti, Francesco

    2017-10-01

    There is considerable evidence that gravitational acceleration is taken into account in the interaction with falling targets through an internal model of Earth gravity. Here we asked whether this internal model is accessed also when target motion is imagined rather than real. In the main experiments, naïve participants grasped an imaginary ball, threw it against the ceiling, and caught it on rebound. In different blocks of trials, they had to imagine that the ball moved under terrestrial gravity (1g condition) or under microgravity (0g) as during a space flight. We measured the speed and timing of the throwing and catching actions, and plotted ball flight duration versus throwing speed. Best-fitting duration-speed curves estimate the laws of ball motion implicit in the participant's performance. Surprisingly, we found duration-speed curves compatible with 0g for both the imaginary 0g condition and the imaginary 1g condition, despite the familiarity with Earth gravity effects and the added realism of performing the throwing and catching actions. In a control experiment, naïve participants were asked to throw the imaginary ball vertically upwards at different heights, without hitting the ceiling, and to catch it on its way down. All participants overestimated ball flight durations relative to the durations predicted by the effects of Earth gravity. Overall, the results indicate that mental imagery of motion does not have access to the internal model of Earth gravity, but resorts to a simulation of visual motion. Because visual processing of accelerating/decelerating motion is poor, visual imagery of motion at constant speed or slowly varying speed appears to be the preferred mode to perform the tasks. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. The 'gravitating' tensor in the dualistic theory

    International Nuclear Information System (INIS)

    Mahanta, M.N.

    1989-01-01

    The exact microscopic system of Einstein-type field equations of the dualistic gravitation theory is investigated as well as an analysis of the modified energy-momentum tensor or so called 'gravitating' tensor is presented

  9. The Theory of Vortical Gravitational Fields

    Directory of Open Access Journals (Sweden)

    Rabounski D.

    2007-04-01

    Full Text Available This paper treats of vortical gravitational fields, a tensor of which is the rotor of the general covariant gravitational inertial force. The field equations for a vortical gravitational field (the Lorentz condition, the Maxwell-like equations, and the continuity equation are deduced in an analogous fashion to electrodynamics. From the equations it is concluded that the main kind of vortical gravitational fields is “electric”, determined by the non-stationarity of the acting gravitational inertial force. Such a field is a medium for traveling waves of the force (they are different to the weak deformation waves of the space metric considered in the theory of gravitational waves. Standing waves of the gravitational inertial force and their medium, a vortical gravitational field of the “magnetic” kind, are exotic, since a non-stationary rotation of a space body (the source of such a field is a very rare phenomenon in the Universe.

  10. Merging Black Holes and Gravitational Waves

    Science.gov (United States)

    Centrella, Joan

    2009-01-01

    This talk will focus on simulations of binary black hole mergers and the gravitational wave signals they produce. Applications to gravitational wave detection with LISA, and electronagnetic counterparts, will be highlighted.

  11. Parametric mechanisms for detecting gravitational waves

    International Nuclear Information System (INIS)

    Pustovoit, V.I.; Chernozatonskii, L.A.

    1981-01-01

    An intense electromagnetic wave and a gravitational wave can interact to effectively generate electromagnetic waves at sum and difference frequencies. The self-effect of a monochromatic electromagnetic wave through a gravitational field leads to third-harmonic generation

  12. Resonant-bar gravitational radiation antennas

    International Nuclear Information System (INIS)

    Blair, D.G.

    1987-01-01

    This paper reviews the concept of gravitational radiation, and describes the worldwide research programme for the development of high-sensitivity resonant-bar antennas which are aimed at detecting gravitational radiation from astrophysical sources. (author)

  13. Potato tuber wounding induces responses associated with various healing processes

    Science.gov (United States)

    Wounding induces an avalanche of biological responses involved in the healing and protection of internal tuber tissues exposed by mechanical damage and seed cutting. Collectively, our studies have framed a portrait of the mechanisms and regulation of potato tuber wound-healing, but much more is req...

  14. Light-ion-induced multifragmentation. A fast, evolutionary process

    International Nuclear Information System (INIS)

    Viola, V.E.; Bracken, D.S.; Foxford, E.R.; Ginger, D.; Kwiatkowski, K.; Morley, K.B.; Hsi, W.C.; Wang, G.; Korteling, R.G.; Legrain, R.

    1996-09-01

    GeV light-ion-induced reactions offer a unique tool for preparing hot, dilute nuclear matter. Time evolution of nuclear multifragmentation in 3 He + nat Ag and 3 He + 197 Au reactions are investigated. Fragment-fragment correlations are studied in order to gain information on multifragmentation mechanism. (K.A.)

  15. Gravitational states of antihydrogen near material surface

    Energy Technology Data Exchange (ETDEWEB)

    Voronin, Alexei Yu., E-mail: dr.a.voronin@gmail.com [P.N. Lebedev Physical Institute (Russian Federation); Froelich, Piotr [Uppsala University, Department of Quantum Chemistry (Sweden); Nesvizhevsky, Valery V. [Institut Laue-Langevin (ILL) (France)

    2012-12-15

    We present a theoretical study of the motion of antihydrogen atoms in the Earth's gravitational field near a material surface. We predict the existence of long-living quasistationary states of antihydrogen in a superposition of the gravitational and Casimir-van der Waals potentials of the surface. We suggest an interferometric method of measuring the energy difference between such gravitational states, hence the gravitational mass of antihydrogen.

  16. Gravitational wave reception by a sphere

    International Nuclear Information System (INIS)

    Ashby, N.; Dreitlein, J.

    1975-01-01

    The reception of gravitational waves by an elastic self-gravitating spherical detector is studied in detail. The equations of motion of a detector driven by a gravitational wave are presented in the intuitively convenient coordinate system of Fermi. An exact analytic solution is given for the homogeneous isotropic sphere. Nonlinear effects of a massive self-gravitating system are computed for a body of mass equal to that of the earth, and are shown to be numerically important

  17. Vector-tensor interaction of gravitation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yuan-zhong; Guo han-ying

    1982-11-01

    In the paper, by using the equation of motion a particle, we show that the antigravity exist in the vector-tensor model of gravitation. Thus the motion of a particle deviates from the geodesic equation. In Newtonian approximation and weak gravitational field, acceleration of a particle in a spherically symmetric and astatic gravitation field is zero. The result is obviously not in agreement with gravitational phenomena.

  18. The Japanese space gravitational wave antenna; DECIGO

    OpenAIRE

    Kawamura, Seiji; Ando, Masaki; Nakamura, Takashi; Tsubono, Kimio; Tanaka, Takahiro; Funaki, Ikkoh; Seto, Naoki; Numata, Kenji; Sato, Shuichi; Ioka, Kunihito; Kanda, Nobuyuki; Takashima, Takeshi; Agatsuma, Kazuhiro; Akutsu, Tomotada; Akutsu, Tomomi

    2008-01-01

    DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. The goal of DECIGO is to detect gravitational waves from various kinds of sources mainly between 0.1 Hz and 10 Hz and thus to open a new window of observation for gravitational wave astronomy. DECIGO will consist of three drag-free spacecraft, 1000 km apart from each other, whose relative displacements are measured by a Fabry—Perot Michelson interferometer. We plan to lau...

  19. The Japanese space gravitational wave antenna - DECIGO

    OpenAIRE

    Kawamura, Seiji; Ando, Masaki; Nakamura, Takashi; Tsubono, Kimio; Tanaka, Takahiro; Funaki, Iklkoh; Seto, Naoki; Numata, Kenji; Sato, Shuichi; Ioka, Kunihito; Kanda, Nobuyuki; Takashima, Takeshi; Agatsuma, Kazuhiro; Akutsu, Tomotada; Akutsu, Tomomi

    2008-01-01

    DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. The goal of DECIGO is to detect gravitational waves from various kinds of sources mainly between 0.1 Hz and 10 Hz and thus to open a new window of observation for gravitational wave astronomy. DECIGO will consist of three drag-free spacecraft, 1000 km apart from each other, whose relative displacements are measured by a Fabry—Perot Michelson interferometer. We plan to lau...

  20. Effect of the Earth's gravitational field on the detection of gravitational waves

    International Nuclear Information System (INIS)

    Denisov, V.I.; Eliseev, V.A.

    1988-01-01

    We consider the laboratory detection of high-frequency gravitational waves in theories of gravitation based on a pseudo-Euclidean space-time. We analyze the effects due to the Earth's gravitational field on the propagation velocities of gravitational and electromagnetic waves in these theories. Experiments to test the predictions of this class of theories are discussed

  1. On quantum electrodynamics in an external gravitational field. Part 2. Discussion of the effects

    International Nuclear Information System (INIS)

    Lotze, K.H.

    1978-01-01

    The S matrix constructed in Part I of this work is evaluated for processes which it includes. Some of them are discussed in more detail: pair creation and scattering in an external gravitational field, pair creation by a photon and creation of an electron-positron pair and a photon in an external gravitational field. (author)

  2. Plausibility Arguments and Universal Gravitation

    Science.gov (United States)

    Cunha, Ricardo F. F.; Tort, A. C.

    2017-01-01

    Newton's law of universal gravitation underpins our understanding of the dynamics of the Solar System and of a good portion of the observable universe. Generally, in the classroom or in textbooks, the law is presented initially in a qualitative way and at some point during the exposition its mathematical formulation is written on the blackboard…

  3. Scientific visualization of gravitational lenses

    International Nuclear Information System (INIS)

    Magallon, M.

    1999-01-01

    Concepts related to gravitational lenses are discussed and applied to develop an interactive visualization tool that allow us to investigate them. Optimization strategies were performed to elaborate the tool. Some results obtained from the application of the tool are shown [es

  4. Wilson loops in Kerr gravitation

    International Nuclear Information System (INIS)

    Bollini, C.G.; Giambiagi, J.J.; Tiomno, J.

    1981-01-01

    The ordered integrals for several paths in Kerr gravitation is computed in a compact form. When the path is closed its relation with the angular parallel displacement is discussed and the corresponding Wilson loop is calculated. The validity of Mandelstam relations for gauge fields is also explicitly verified. (Author) [pt

  5. Gravitational lensing in plasmic medium

    Energy Technology Data Exchange (ETDEWEB)

    Bisnovatyi-Kogan, G. S., E-mail: gkogan@iki.rssi.ru; Tsupko, O. Yu., E-mail: tsupko@iki.rssi.ru [Russian Academy of Sciences, Space Research Institute (Russian Federation)

    2015-07-15

    The influence of plasma on different effects of gravitational lensing is reviewed. Using the Hamiltonian approach for geometrical optics in a medium in the presence of gravity, an exact formula for the photon deflection angle by a black hole (or another body with a Schwarzschild metric) embedded in plasma with a spherically symmetric density distribution is derived. The deflection angle in this case is determined by the mutual combination of different factors: gravity, dispersion, and refraction. While the effects of deflection by the gravity in vacuum and the refractive deflection in a nonhomogeneous medium are well known, the new effect is that, in the case of a homogeneous plasma, in the absence of refractive deflection, the gravitational deflection differs from the vacuum deflection and depends on the photon frequency. In the presence of a plasma nonhomogeneity, the chromatic refractive deflection also occurs, so the presence of plasma always makes gravitational lensing chromatic. In particular, the presence of plasma leads to different angular positions of the same image if it is observed at different wavelengths. It is discussed in detail how to apply the presented formulas for the calculation of the deflection angle in different situations. Gravitational lensing in plasma beyond the weak deflection approximation is also considered.

  6. Academic Training: Gravitational Waves Astronomy

    CERN Multimedia

    2006-01-01

    2006-2007 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 16, 17, 18 October from 11:00 to 12:00 - Main Auditorium, bldg. 500 Gravitational Waves Astronomy M. LANDRY, LIGO Hanford Observatory, Richland, USA Gravitational wave astronomy is expected to become an observational field within the next decade. First direct detection of gravitational waves is possible with existing terrestrial-based detectors, and highly probable with proposed upgrades. In this three-part lecture series, we give an overview of the field, including material on gravitional wave sources, detection methods, some details of interferometric detectors, data analysis methods, and current results from observational data-taking runs of the LIGO and GEO projects.ENSEIGNEMENT ACADEMIQUE ACADEMIC TRAINING Françoise Benz 73127 academic.training@cern.ch If you wish to participate in one of the following courses, please tell to your supervisor and apply electronically from the course description pages that can be found on the Web at: http://www.cern...

  7. Normalization of Gravitational Acceleration Models

    Science.gov (United States)

    Eckman, Randy A.; Brown, Aaron J.; Adamo, Daniel R.

    2011-01-01

    Unlike the uniform density spherical shell approximations of Newton, the con- sequence of spaceflight in the real universe is that gravitational fields are sensitive to the nonsphericity of their generating central bodies. The gravitational potential of a nonspherical central body is typically resolved using spherical harmonic approximations. However, attempting to directly calculate the spherical harmonic approximations results in at least two singularities which must be removed in order to generalize the method and solve for any possible orbit, including polar orbits. Three unique algorithms have been developed to eliminate these singularities by Samuel Pines [1], Bill Lear [2], and Robert Gottlieb [3]. This paper documents the methodical normalization of two1 of the three known formulations for singularity-free gravitational acceleration (namely, the Lear [2] and Gottlieb [3] algorithms) and formulates a general method for defining normalization parameters used to generate normalized Legendre Polynomials and ALFs for any algorithm. A treatment of the conventional formulation of the gravitational potential and acceleration is also provided, in addition to a brief overview of the philosophical differences between the three known singularity-free algorithms.

  8. Isolation of gravitational waves from displacement noise and utility of a time-delay device

    Energy Technology Data Exchange (ETDEWEB)

    Somiya, Kentaro [Max-Planck Institut fuer Gravitationsphysik, Am Muehlenberg 1, 14476 Potsdam (Germany); Goda, Keisuke [LIGO Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Chen, Yanbei [Max-Planck Institut fuer Gravitationsphysik, Am Muehlenberg 1, 14476 Potsdam (Germany); Mikhailov, Eugeniy E [Department of Physics, College of William and Mary, Williamsburg, VA 23187 (United States)

    2007-05-15

    Interferometers with kilometer-scale arms have been built for gravitational-wave detections on the ground; ones with much longer arms are being planned for space-based detection. One fundamental motivation for long baseline interferometry is from displacement noise. In general, the longer the arm length L, the larger the motion the gravitational-wave induces on the test masses, until L becomes comparable to the gravitational wavelength. Recently, schemes have been invented, in which displacement noise can be evaded by employing differences between the influence of test-mass motions and that of gravitational waves on light propagation. However, in these schemes, such differences only becomes significant when Lapproaches the gravitational wavelength. In this paper, we explore a use of artificial time delay in displacement-noise-free interferometers, which will shift the frequency band of the effect being significant and may improve their shot-noise-limited sensitivity at low frequencies.

  9. Isolation of gravitational waves from displacement noise and utility of a time-delay device

    International Nuclear Information System (INIS)

    Somiya, Kentaro; Goda, Keisuke; Chen, Yanbei; Mikhailov, Eugeniy E

    2007-01-01

    Interferometers with kilometer-scale arms have been built for gravitational-wave detections on the ground; ones with much longer arms are being planned for space-based detection. One fundamental motivation for long baseline interferometry is from displacement noise. In general, the longer the arm length L, the larger the motion the gravitational-wave induces on the test masses, until L becomes comparable to the gravitational wavelength. Recently, schemes have been invented, in which displacement noise can be evaded by employing differences between the influence of test-mass motions and that of gravitational waves on light propagation. However, in these schemes, such differences only becomes significant when Lapproaches the gravitational wavelength. In this paper, we explore a use of artificial time delay in displacement-noise-free interferometers, which will shift the frequency band of the effect being significant and may improve their shot-noise-limited sensitivity at low frequencies

  10. Spinor approach to gravitational motion and precession

    International Nuclear Information System (INIS)

    Hestenes, D.

    1986-01-01

    The translational and rotational equations of motion for a small rigid body in a gravitational field are combined in a single spinor equation. Besides its computational advantages, this unifies the description of gravitational interaction in classical and quantum theory. Explicit expressions for gravitational precession rates are derived. (author)

  11. On black holes and gravitational waves

    CERN Document Server

    Loinger, Angelo

    2002-01-01

    Black holes and gravitational waves are theoretical entities of today astrophysics. Various observed phenomena have been associated with the concept of black hole ; until now, nobody has detected gravitational waves. The essays contained in this book aim at showing that the concept of black holes arises from a misinterpretation of general relativity and that gravitational waves cannot exist.

  12. Detecting gravitational waves from accreting neutron stars

    NARCIS (Netherlands)

    Watts, A.L.; Krishnan, B.

    2009-01-01

    The gravitational waves emitted by neutron stars carry unique information about their structure and composition. Direct detection of these gravitational waves, however, is a formidable technical challenge. In a recent study we quantified the hurdles facing searches for gravitational waves from the

  13. Multiparticle production in the instanton-induced DIS processes

    International Nuclear Information System (INIS)

    Kashkan, V.I.; Kuvshinov, V.I.; Shulyakovsky, R.; Jenkovszky, L.L.

    2000-01-01

    Factorial, cumulant and H q -moments in dependence on their rank q for the instanton-induced deep inelastic scattering in the framework of QCD are calculated numerically and analyzed. Hadronization is taken into account by means of Monte Carlo simulation. The obtained correlation moments show specific behaviour, which can be considered as a new criterion of the QCD-instantons identification on experiment at HERA

  14. Effect of homopolymer in polymerization-induced microphase separation process

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jongmin; Saba, Stacey A.; Hillmyer, Marc A.; Kang, Dong-Chang; Seo, Myungeun (IBS-Korea); (KAIST); (UMMN)

    2017-09-01

    We report on the phase separation behaviors of polymerization mixtures containing a polylactide macro-chain transfer agent (PLA-CTA), styrene, divinylbenzene, hydroxyl-terminated PLA (PLA-OH), and a molecular chain transfer agent which enable the ability to tune the pore size of a cross-linked polymer monolith in a facile manner. Cross-linked monoliths were produced from the mixtures via reversible addition-fragmentation chain transfer (RAFT) polymerization and converted into cross-linked porous polymers by selective removal of PLA while retaining the parent morphology. We demonstrate that pore sizes are tunable over a wide range of length scales from the meso- to macroporous regimes by adjusting the ratio of PLA-CTA to PLA-OH in the reaction mixture which causes the phase separation mechanism to change from polymerization-induced microphase separation to polymerization-induced phase separation. The possibility of increasing porosity and inducing simultaneous micro- and macrophase separation was also realized by adjustments in the molar mass of PLA which enabled the synthesis of hierarchically meso- and macroporous polymers.

  15. New astrophysical school of thermodynamics. Space dynamics and gravitism

    Energy Technology Data Exchange (ETDEWEB)

    Gal-Or, B [Technion-Israel Inst. of Tech., Haifa. Dept. of Aeronautical Engineering

    1978-07-01

    Much verified information has been accumulated in recent years which shows that many fundamental concepts involving classical physics, thermodynamics, astrophysics and the general theory of relativity are strongly coupled together. This evidence is employed in this paper to explain principles of the astrophysical school of thermodynamics; a growing revolutionary school which deduces thermodynamics, energy dissipation, and time anisotropies from the Newtonian and Einsteinian theories of gravitation and from the dynamics of radiation in 'unsaturable' (intercluster) space. Accordingly, the density of radiation and the dynamics of ('unsaturable') outer space affect all processes in the galactic media, in the solar system, in the magnetosphere and on Earth. The origin of all observed irreversibilities in nature - of time, of all time anisotropics, of energy dissipation, of T-violations in 'elementary particles', of retarded potentials in electrodynamics, of the biological clocks, and of biological arrows of time - is one; it is the radiation unsaturability of space. But, since this unsaturability and gravitation are interconnected, the origin of asymmetries, structure, and thermodynamics is explained within the framework of the Newtonian and Einsteinian theories of gravitation. The theory presented here forms a part of a general approach called gravitism, which unifies some other disciplinary studies in the natural sciences with a unified approach to gravitation and the theory of time.

  16. Awareness of technology-induced errors and processes for identifying and preventing such errors.

    Science.gov (United States)

    Bellwood, Paule; Borycki, Elizabeth M; Kushniruk, Andre W

    2015-01-01

    There is a need to determine if organizations working with health information technology are aware of technology-induced errors and how they are addressing and preventing them. The purpose of this study was to: a) determine the degree of technology-induced error awareness in various Canadian healthcare organizations, and b) identify those processes and procedures that are currently in place to help address, manage, and prevent technology-induced errors. We identified a lack of technology-induced error awareness among participants. Participants identified there was a lack of well-defined procedures in place for reporting technology-induced errors, addressing them when they arise, and preventing them.

  17. Gravitational wave signals and cosmological consequences of gravitational reheating

    Science.gov (United States)

    Artymowski, Michał; Czerwińska, Olga; Lalak, Zygmunt; Lewicki, Marek

    2018-04-01

    Reheating after inflation can proceed even if the inflaton couples to Standard Model (SM) particles only gravitationally. However, particle production during the transition between de-Sitter expansion and a decelerating Universe is rather inefficient and the necessity to recover the visible Universe leads to a non-standard cosmological evolution initially dominated by remnants of the inflaton field. We remain agnostic to the specific dynamics of the inflaton field and discuss a generic scenario in which its remnants behave as a perfect fluid with a general barotropic parameter w. Using CMB and BBN constraints we derive the allowed range of inflationary scales. We also show that this scenario results in a characteristic primordial Gravitational Wave (GW) spectrum which gives hope for observation in upcoming runs of LIGO as well as in other planned experiments.

  18. Measurement of gravitational acceleration of antimatter

    International Nuclear Information System (INIS)

    Rouhani, S.

    1989-12-01

    The minute yet effective impact of gravitational potential in the central region of a long tube magnetic container of non-neutral plasmas can be utilized for the measurement of the gravitational acceleration of antimatter particles. The slight change in distribution of plasma particles along the gravitational field affects the internal electric field of the plasma, which in turn affects the frequency of the magnetron motion of its particles. Thus, a rather straightforward relation is established between the gravitational acceleration of the particles and their magnetron frequencies, which is measurable directly, determining the value of the gravitational acceleration. (author). 7 refs, 3 figs

  19. The Japanese space gravitational wave antenna - DECIGO

    International Nuclear Information System (INIS)

    Kawamura, S; Seto, N; Sato, S; Arai, K; Ando, M; Tsubono, K; Agatsuma, K; Akutsu, T; Akutsu, T; Arase, Y; Nakamura, T; Tanaka, T; Funaki, I; Takashima, T; Numata, K; Ioka, K; Kanda, N; Aoyanagi, Koh-Suke; Araya, A; Asada, H

    2008-01-01

    DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. The goal of DECIGO is to detect gravitational waves from various kinds of sources mainly between 0.1 Hz and 10 Hz and thus to open a new window of observation for gravitational wave astronomy. DECIGO will consist of three drag-free spacecraft, 1000 km apart from each other, whose relative displacements are measured by a Fabry-Perot Michelson interferometer. We plan to launch DECIGO pathfinder first to demonstrate the technologies required to realize DECIGO and, if possible, to detect gravitational waves from our galaxy or nearby galaxies

  20. Impurity-defect induced noncentrosymmetricity in nonlinear optical processes

    International Nuclear Information System (INIS)

    Miah, M. Idrish

    2009-01-01

    Noncentrosymmetric nanosize-material processes in cadmium iodide are formed by doping it with the impurity copper. The noncentrosymmetricity in the processes are probed by the observation of the second-order optical susceptibility χ ijk (2) . The value of χ ijk (2) is found to depend fashionably on the impurity content of the nanomaterials. The results also show that a significant enhancement in the noncentrosymmetric response is achieved in nanomaterials with reduced sizes and at low temperatures.

  1. Stochastic background of gravitational waves from hybrid preheating.

    Science.gov (United States)

    García-Bellido, Juan; Figueroa, Daniel G

    2007-02-09

    The process of reheating the Universe after hybrid inflation is extremely violent. It proceeds through the nucleation and subsequent collision of large concentrations of energy density in bubblelike structures, which generate a significant fraction of energy in the form of gravitational waves. We study the power spectrum of the stochastic background of gravitational waves produced at reheating after hybrid inflation. We find that the amplitude could be significant for high-scale models, although the typical frequencies are well beyond what could be reached by planned gravitational wave observatories. On the other hand, low-scale models could still produce a detectable stochastic background at frequencies accessible to those detectors. The discovery of such a background would open a new window into the very early Universe.

  2. Elemental process of amorphization induced by electron irradiation in Si

    International Nuclear Information System (INIS)

    Yamasaki, Jun; Takeda, Seiji; Tsuda, Kenji

    2002-01-01

    We recently found that amorphization is induced in Si by electron irradiation. Examining the amorphization systematically, we have established the diagram of steady states under electron irradiation, either amorphous Si (a-Si) or crystalline Si (c-Si) as a function of incident electron energy, electron dose, and irradiation temperature. Utilizing transmission electron microscopy, electron energy filtered diffraction and electron energy-loss spectroscopy, we have characterized the atomic structure, the electronic structure, and the thermal stability of a-Si induced by electron irradiation. Based on the experimental data, we have also concluded that the amorphization is caused by the accumulation of not point defects but small cascade damages. Analyzing the change in the intensity of halo diffraction rings during amorphization, we have clarified that the smallest cascade damage that contributes to amorphization includes only about four Si atoms. This presumably supports the amorphization mechanism that four self-interstitial atoms form the quasistable structure I4 in c-Si and it becomes an amorphous embryo

  3. Formation of black hole and emission of gravitational waves.

    Science.gov (United States)

    Nakamura, Takashi

    2006-12-01

    Numerical simulations were performed for the formation process of rotating black holes. It is suggested that Kerr black holes are formed for wide ranges of initial parameters. The nature of gravitational waves from a test particle falling into a Kerr black hole as well as the development of 3D numerical relativity for the coalescing binary neutron stars are discussed.

  4. Real-time Microseismic Processing for Induced Seismicity Hazard Detection

    Energy Technology Data Exchange (ETDEWEB)

    Matzel, Eric M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-31

    Induced seismicity is inherently associated with underground fluid injections. If fluids are injected in proximity to a pre-existing fault or fracture system, the resulting elevated pressures can trigger dynamic earthquake slip, which could both damage surface structures and create new migration pathways. The goal of this research is to develop a fundamentally better approach to geological site characterization and early hazard detection. We combine innovative techniques for analyzing microseismic data with a physics-based inversion model to forecast microseismic cloud evolution. The key challenge is that faults at risk of slipping are often too small to detect during the site characterization phase. Our objective is to devise fast-running methodologies that will allow field operators to respond quickly to changing subsurface conditions.

  5. Ultraviolet-light-induced processes in germanium-doped silica

    DEFF Research Database (Denmark)

    Kristensen, Martin

    2001-01-01

    A model is presented for the interaction of ultraviolet (UV) light with germanium-doped silica glass. It is assumed that germanium sites work as gates for transferring the excitation energy into the silica. In the material the excitation induces forbidden transitions to two different defect states...... which are responsible for the observed refractive index changes. Activation energies [1.85 +/-0.15 eV and 1.91 +/-0.15 eV] and rates [(2.7 +/-1.9) x 10(13) Hz and(7.2 +/-4.5) x 10(13) Hz] are determined for thermal elimination of these states. Good agreement is found with experimental results and new UV...

  6. Transient processes induced by heavy projectiles in silicon

    International Nuclear Information System (INIS)

    Lazanu, Ionel; Lazanu, Sorina

    2010-01-01

    The thermal spike model developed for the electronic stopping power regime is extended to consider both ionization and nuclear energy loss processes of the projectile as electronic and atomic heat distinct sources. The time and space dependencies of the lattice and electron temperatures near the projectile trajectory are calculated and discussed for different ions in silicon, at room and cryogenic temperatures, taking into account the peculiarities of electron-phonon interaction in both domains. The model developed contributes to the understanding of transient microscopic processes immediately after the projectile interaction in the target.

  7. Impurity-defect induced noncentrosymmetricity in nonlinear optical processes

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. Idrish, E-mail: m.miah@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

    2009-12-15

    Noncentrosymmetric nanosize-material processes in cadmium iodide are formed by doping it with the impurity copper. The noncentrosymmetricity in the processes are probed by the observation of the second-order optical susceptibility {chi}{sub ijk}{sup (2)}. The value of {chi}{sub ijk}{sup (2)} is found to depend fashionably on the impurity content of the nanomaterials. The results also show that a significant enhancement in the noncentrosymmetric response is achieved in nanomaterials with reduced sizes and at low temperatures.

  8. The Gravitational Million-Body Problem: A Multidisciplinary Approach to Star Cluster Dynamics

    International Nuclear Information System (INIS)

    Tremaine, Scott

    2003-01-01

    The gravitational N-body problem is to describe the evolution of an isolated system of N point masses interacting only through Newtonian gravitational forces. For N =2 the solution is due to Newton. For N =3 there is no general analytic solution, but the problem has occupied generations of illustrious physicists and mathematicians including Laplace, Lagrange, Gauss and Poincare, and inspired the modern subjects of nonlinear dynamics and chaos theory. The general gravitational N-body problem remains one of the oldest unsolved problems in physics. Many-body problems can be simpler than few-body problems, and many physicists have attempted to apply the methods of classical equilibrium statistical mechanics to the gravitational N-body problem for N >> 1. These applications have had only limited success, partly because the gravitational force is too strong at both small scales (the interparticle potential energy diverges) and large scales (energy is not extensive). Nevertheless, we now understand a rich variety of behaviour in large-N gravitating systems. These include the negative heat capacity of isolated, gravitationally bound systems, which is the basic reason why nuclear burning in the Sun is stable; Antonov's discovery that an isothermal, self-gravitating gas in a container is located at a saddle point, rather than a maximum, of the entropy when the gas is sufficiently dense and hence is unstable (the 'gravothermal catastrophe'); the process of core collapse, in which relaxation induces a self-similar evolution of the central core of the system towards (formally) infinite density in a finite time; and the remarkable phenomenon of gravothermal oscillations, in which the central density undergoes periodic oscillations by factors of a thousand or more on the relaxation timescale - but only if N ∼> 10 4 . The Gravitational Million-Body Problem is a monograph that describes our current understanding of the gravitational N-body problem. The authors have chosen to

  9. BOOK REVIEW: The Gravitational Million-Body Problem: A Multidisciplinary Approach to Star Cluster Dynamics

    Science.gov (United States)

    Heggie, D.; Hut, P.

    2003-10-01

    The gravitational N-body problem is to describe the evolution of an isolated system of N point masses interacting only through Newtonian gravitational forces. For N =2 the solution is due to Newton. For N =3 there is no general analytic solution, but the problem has occupied generations of illustrious physicists and mathematicians including Laplace, Lagrange, Gauss and Poincaré, and inspired the modern subjects of nonlinear dynamics and chaos theory. The general gravitational N-body problem remains one of the oldest unsolved problems in physics. Many-body problems can be simpler than few-body problems, and many physicists have attempted to apply the methods of classical equilibrium statistical mechanics to the gravitational N-body problem for N gg 1. These applications have had only limited success, partly because the gravitational force is too strong at both small scales (the interparticle potential energy diverges) and large scales (energy is not extensive). Nevertheless, we now understand a rich variety of behaviour in large-N gravitating systems. These include the negative heat capacity of isolated, gravitationally bound systems, which is the basic reason why nuclear burning in the Sun is stable; Antonov's discovery that an isothermal, self-gravitating gas in a container is located at a saddle point, rather than a maximum, of the entropy when the gas is sufficiently dense and hence is unstable (the 'gravothermal catastrophe'); the process of core collapse, in which relaxation induces a self-similar evolution of the central core of the system towards (formally) infinite density in a finite time; and the remarkable phenomenon of gravothermal oscillations, in which the central density undergoes periodic oscillations by factors of a thousand or more on the relaxation timescale - but only if N gtrsim 104. The Gravitational Million-Body Problem is a monograph that describes our current understanding of the gravitational N-body problem. The authors have chosen to

  10. Diffusion processes in bombardment-induced surface topography

    International Nuclear Information System (INIS)

    Robinson, R.S.

    1984-01-01

    A treatment is given of the problem of surface diffusion processes occurring during surface topography development, whenever a surface is simultaneously seeded with impurities and ion bombarded. The development of controllable topography and the importance of surface diffusion parameters, which can be obtained during these studies, are also analyzed. 101 refs.; 7 figs.; 2 tabs

  11. The processing of inter-item relations as a moderating factor of retrieval-induced forgetting

    OpenAIRE

    Tempel, Tobias; Wippich, Werner

    2012-01-01

    We investigated influences of item generation and emotional valence on retrieval-induced forgetting. Drawing on postulates of the three-factor theory of generation effects, generation tasks differentially affecting the processing of inter-item relations were applied. Whereas retrieval-induced forgetting of freely generated items was moderated by the emotional valence as well as retrieval-induced forgetting of read items, even though in the reverse direction (Experiment 1), fragment completion...

  12. Generalized equations of gravitational field

    International Nuclear Information System (INIS)

    Stanyukovich, K.P.; Borisova, L.B.

    1985-01-01

    Equations for gravitational fields are obtained on the basis of a generalized Lagrangian Z=f(R) (R is the scalar curvature). Such an approach permits to take into account the evolution of a gravitation ''constant''. An expression for the force Fsub(i) versus the field variability is obtained. Conservation laws are formulated differing from the standard ones by the fact that in the right part of new equations the value Fsub(i) is present that goes to zero at an ultimate passage to the standard Einstein theory. An equation of state is derived for cosmological metrics for a particular case, f=bRsup(1+α) (b=const, α=const)

  13. Gravitational lensing and extra dimensions

    International Nuclear Information System (INIS)

    He, X-G.; University of Melbourne, Parkville, VIC; Joshi, G.C.; McKellar, B.H.J.

    1999-08-01

    We study gravitational tensing and the bending of light in low energy scale (M s ) gravity theories with extra space-time dimensions 'n'. We find that due to the presence of spin-2 Kaluza-Klein states from compactification, a correction to the deflection angle with a strong quadratic dependence on the photon energy is introduced. No deviation from the Einstein General Relativity prediction for the deflection angle for photons grazing the Sun in the visible band with 15% accuracy (90% c.l.) implies that the scale M s has to be larger than 1.4(2/(n-2)) 1/4 TeV and approximately 4 TeV for n=2. This lower bound is comparable with that from collider physics constraints. Gravitational tensing experiments with higher energy photons can provide stronger constraints. (authors)

  14. New case of gravitational lensing

    Energy Technology Data Exchange (ETDEWEB)

    Surdej, J.; Swings, J.-P.; Magain, P.; Borgeest, U.; Kayser, R.; Refsdal, S.; Courvoisier, T.J.-L.; Kellermann, K.I.; Kuehr, H.

    1987-10-22

    The authors report a brief description of a gravitational lens system UM673 = Q0142 - 100 = PHL3703. It consists of two images, A and B, separated by 2.2 arc s at a redshift zsub(q) = 2.719. The lensing galaxy has also been found. It lies very near the line connecting the two QSO (quasi-stellar objects) images, approx. 0.8 arc s from the fainter one. Application of gravitational optometry to this system leads to a value Msub(o) or approx. = 2.4 x 10/sup 11/ M solar masses for the mass of the lensing galaxy and to ..delta..t approx. 7 weeks for the most likely travel-time difference between the two light paths to the QSO.

  15. Gravitating multidefects from higher dimensions

    CERN Document Server

    Giovannini, Massimo

    2007-01-01

    Warped configurations admitting pairs of gravitating defects are analyzed. After devising a general method for the construction of multidefects, specific examples are presented in the case of higher-dimensional Einstein-Hilbert gravity. The obtained profiles describe diverse physical situations such as (topological) kink-antikink systems, pairs of non-topological solitons and bound configurations of a kink and of a non-topological soliton. In all the mentioned cases the geometry is always well behaved (all relevant curvature invariants are regular) and tends to five-dimensional anti-de Sitter space-time for large asymptotic values of the bulk coordinate. Particular classes of solutions can be generalized to the framework where the gravity part of the action includes, as a correction, the Euler-Gauss-Bonnet combination. After scrutinizing the structure of the zero modes, the obtained results are compared with conventional gravitating configurations containing a single topological defect.

  16. Magnetic tension and gravitational collapse

    International Nuclear Information System (INIS)

    Tsagas, Christos G

    2006-01-01

    The gravitational collapse of a magnetized medium is investigated by studying qualitatively the convergence of a timelike family of non-geodesic worldlines in the presence of a magnetic field. Focusing on the field's tension, we illustrate how the winding of the magnetic forcelines due to the fluid's rotation assists the collapse, while shear-like distortions in the distribution of the field's gradients resist contraction. We also show that the relativistic coupling between magnetism and geometry, together with the tension properties of the field, lead to a magneto-curvature stress that opposes the collapse. This tension stress grows stronger with increasing curvature distortion, which means that it could potentially dominate over the gravitational pull of the matter. If this happens, a converging family of non-geodesic worldlines can be prevented from focusing without violating the standard energy conditions

  17. Bayesian Inference on Gravitational Waves

    Directory of Open Access Journals (Sweden)

    Asad Ali

    2015-12-01

    Full Text Available The Bayesian approach is increasingly becoming popular among the astrophysics data analysis communities. However, the Pakistan statistics communities are unaware of this fertile interaction between the two disciplines. Bayesian methods have been in use to address astronomical problems since the very birth of the Bayes probability in eighteenth century. Today the Bayesian methods for the detection and parameter estimation of gravitational waves have solid theoretical grounds with a strong promise for the realistic applications. This article aims to introduce the Pakistan statistics communities to the applications of Bayesian Monte Carlo methods in the analysis of gravitational wave data with an  overview of the Bayesian signal detection and estimation methods and demonstration by a couple of simplified examples.

  18. Topological quantization of gravitational fields

    International Nuclear Information System (INIS)

    Patino, Leonardo; Quevedo, Hernando

    2005-01-01

    We introduce the method of topological quantization for gravitational fields in a systematic manner. First we show that any vacuum solution of Einstein's equations can be represented in a principal fiber bundle with a connection that takes values in the Lie algebra of the Lorentz group. This result is generalized to include the case of gauge matter fields in multiple principal fiber bundles. We present several examples of gravitational configurations that include a gravitomagnetic monopole in linearized gravity, the C-energy of cylindrically symmetric fields, the Reissner-Nordstroem and the Kerr-Newman black holes. As a result of the application of the topological quantization procedure, in all the analyzed examples we obtain conditions implying that the parameters entering the metric in each case satisfy certain discretization relationships

  19. Post-Newtonian gravitational bremsstrahlung

    International Nuclear Information System (INIS)

    Turner, M.; Will, C.M.

    1977-07-01

    Formulae and numerical results are presented for the gravitational radiation emitted during a low-deflection encounter between two massive bodies. Results are valid through post-Newtonian order within general relativity. The gravitational waveform, the total luminosity and total emitted energy, the angular distribution of emitted energy, and the frequency spectrum are discussed in detail. A method boosting the accuracy of these quantities to post Newtonian order is also presented. A numerical comparison of results with those of Peters, and of Kovacs and Thorne shows that the post Newtonian method is reliable to better than 0.1 percent at v = 0.1 c, to a few percent at v = 0.35 c, and to 10 to 20 percent at v = 0.5 c

  20. Gravitational waves and dragging effects

    Science.gov (United States)

    Bičák, Jiří; Katz, Joseph; Lynden-Bell, Donald

    2008-08-01

    Linear and rotational dragging effects of gravitational waves on local inertial frames are studied in purely vacuum spacetimes. First, the linear dragging caused by a simple cylindrical pulse is investigated. Surprisingly strong transverse effects of the pulse are exhibited. The angular momentum in cylindrically symmetric spacetimes is then defined and confronted with some results in the literature. In the main part, a general procedure is developed for studying weak gravitational waves with translational but not axial symmetry which can carry angular momentum. After a suitable averaging the rotation of local inertial frames due to such rotating waves can be calculated explicitly and illustrated graphically. This is done in detail in the accompanying paper. Finally, the rotational dragging is given for strong cylindrical waves interacting with a rotating cosmic string with a small angular momentum.

  1. Nonlinear metric perturbation enhancement of primordial gravitational waves.

    Science.gov (United States)

    Bastero-Gil, M; Macias-Pérez, J; Santos, D

    2010-08-20

    We present the evolution of the full set of Einstein equations during preheating after inflation. We study a generic supersymmetric model of hybrid inflation, integrating fields and metric fluctuations in a 3-dimensional lattice. We take initial conditions consistent with Einstein's constraint equations. The induced preheating of the metric fluctuations is not large enough to backreact onto the fields, but preheating of the scalar modes does affect the evolution of vector and tensor modes. In particular, they do enhance the induced stochastic background of gravitational waves during preheating, giving an energy density in general an order of magnitude larger than that obtained by evolving the tensor fluctuations in an homogeneous background metric. This enhancement can improve the expectations for detection by planned gravitational wave observatories.

  2. On the gravitational constant change

    International Nuclear Information System (INIS)

    Milyukov, V.K.

    1986-01-01

    The nowadays viewpoint on the problem of G gravitational constant invariability is presented in brief. The methods and results of checking of the G dependence on the nature of substance (checking of the equivalence principle), G dependepce on distance (checking of Newton gravity law) and time (cosmological experiments) are presented. It is pointed out that all performed experiments don't give any reasons to have doubts in G constancy in space and time and G independence on the nature of the substance

  3. Galactic Structures from Gravitational Radii

    Directory of Open Access Journals (Sweden)

    Salvatore Capozziello

    2018-02-01

    Full Text Available We demonstrate that the existence of a Noether symmetry in f ( R theories of gravity gives rise to an additional gravitational radius, besides the standard Schwarzschild one, determining the dynamics at galactic scales. By this feature, it is possible to explain the baryonic Tully-Fisher relation and the rotation curve of gas-rich galaxies without the dark matter hypothesis. Furthermore, under the same standard, the Fundamental Plane of elliptical galaxies can be addressed.

  4. On neutron stars and gravitation

    International Nuclear Information System (INIS)

    Castagnino, M.A.

    1987-01-01

    From the variational principle for the total internal energy of a neutron star and some restrictions of the form of the metric coefficients, equations of structure which are valid for every metric theory of gravitation have been found. Some simple solutions of the structure equations to find the maximum mass of a neutron star are also presented. Finally it is studied this problem using a post post-Newtonian parametrization

  5. Cylindrical collapse and gravitational waves

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, L [Escuela de FIsica, Faculdad de Ciencias, Universidad Central de Venezuela, Caracas, Venezuela (Venezuela); Santos, N O [Universite Pierre et Marie Curie, CNRS/FRE 2460 LERMA/ERGA, Tour 22-12, 4eme etage, BoIte 142, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratorio Nacional de Computacao Cientifica, 25651-070 Petropolis RJ (Brazil); Centro Brasileiro de Pesquisas Fisicas, 22290-180 Rio de Janeiro RJ (Brazil)

    2005-06-21

    We study the matching conditions for a collapsing anisotropic cylindrical perfect fluid, and we show that its radial pressure is non-zero on the surface of the cylinder and proportional to the time-dependent part of the field produced by the collapsing fluid. This result resembles the one that arises for the radiation-though non-gravitational-in the spherically symmetric collapsing dissipative fluid, in the diffusion approximation.

  6. Field theory approach to gravitation

    International Nuclear Information System (INIS)

    Yilmaz, H.

    1978-01-01

    A number of authors considered the possibility of formulating a field-theory approach to gravitation with the claim that such an approach would uniquely lead to Einstein's theory of general relativity. In this article it is shown that the field theory approach is more generally applicable and uniqueness cannot be claimed. Theoretical and experimental reasons are given showing that the Einsteinian limit appears to be unviable

  7. Generalized field theory of gravitation

    International Nuclear Information System (INIS)

    Yilmaz, H.

    1976-01-01

    It is shown that if, on empirical grounds, one rules out the existence of cosmic fields of Dicke-Brans (scalar) and Will Nordvedt (vector, tensor) type, then the most general experimentally viable and theoretically reasonable theory of gravitation seems to be a LAMBDA-dependent generalization of Einstein and Yilmez theories, which reduces to the former for LAMBDA=0 and to the latter for LAMBDA=1

  8. On the linear conformal gravitation

    International Nuclear Information System (INIS)

    Pal'chik, M.Ya.; Fradkin, E.S.

    1984-01-01

    Conformal gravitation is analyzed under the assumption that its solution possesses the property of conformal symmetry. This assumption has sense in the case of small distances and only for definite types of matter fields, namely: at special choice of matter fields and their interactions, providing a lack of conformal anomalies; or at definite magnitudes of binding constants, coinciding with the zeroes of the Gell-Mann-Low function. The field equations, of the group-theoretical natura are obtained

  9. Gravitation and bilocal field theory

    International Nuclear Information System (INIS)

    Vollendorf, F.

    1975-01-01

    The starting point is the conjecture that a field theory of elementary particles can be constructed only in a bilocal version. Thus the 4-dimensional space time has to be replaced by the 8-dimensional manifold R 8 of all ordered pairs of space time events. With special reference to the Schwarzschild metric it is shown that the embedding of the time space into the manifold R 8 yields a description of the gravitational field. (orig.) [de

  10. Gravitation, Thermodynamics, and Quantum Theory

    OpenAIRE

    Wald, Robert M.

    1999-01-01

    During the past 30 years, research in general relativity has brought to light strong hints of a very deep and fundamental relationship between gravitation, thermodynamics, and quantum theory. The most striking indication of such a relationship comes from black hole thermodynamics, where it appears that certain laws of black hole mechanics are, in fact, simply the ordinary laws of thermodynamics applied to a system containing a black hole. This article will review the present status of black h...

  11. Accelerating Photons with Gravitational Radiation

    CERN Document Server

    Shore, Graham M

    2001-01-01

    The nature of superluminal photon propagation in the gravitational field describing radiation from a time-dependent, isolated source (the Bondi-Sachs metric) is considered in an effective theory which includes interactions which violate the strong equivalence principle. Such interactions are, for example, generated by vacuum polarisation in conventional QED in curved spacetime. The relation of the resulting light-cone modifications to the Peeling Theorem for the Bondi-Sachs spacetime is explained.

  12. Relic gravitational waves in the accelerating Universe

    International Nuclear Information System (INIS)

    Zhang Yang; Yuan Yefei; Zhao Wen; Chen Yingtian

    2005-01-01

    Recent observations have indicated that the Universe at the present stage is in an accelerating expansion, a process that has great implications. We evaluate the spectrum of relic gravitational waves in the current accelerating Universe and find that there are new features appearing in the resulting spectrum as compared to the decelerating models. In the low-frequency range the peak of the spectrum is now located at a frequency ν E ∼ (OMEGA m /OMEGA Λ ) 1/3 ν H , where ν H is the Hubble frequency, and there appears a new segment of spectrum between ν E and ν H . In all other intervals of frequencies ≥ν H , the spectral amplitude acquires an extra factor (OMEGA m /OMEGA Λ ), due to the current acceleration; otherwise the shape of the spectrum is similar to that in the decelerating models. The recent WMAP result of CMB anisotropies is used to normalize the amplitude for gravitational waves. The slope of the power spectrum depends sensitively on the scale factor a(τ) ∝ vertical bar τ vertical bar 1+β during the inflationary stage with β = -2 for the exact de Sitter space. With increasing β, the resulting spectrum is tilted to be flatter with more power at high frequencies, and the sensitivity of the second science run of the LIGO detectors puts a restriction on the parameter β ≤ -1.8. We also give a numerical solution which confirms these features

  13. The string soundscape at gravitational wave detectors

    Science.gov (United States)

    Garcia Garcia, Isabel; Krippendorf, Sven; March-Russell, John

    2018-04-01

    We argue that gravitational wave signals due to collisions of ultra-relativistic bubble walls may be common in string theory. This occurs due to a process of post-inflationary vacuum decay via quantum tunnelling. Though we study a specific string construction involving warped throats, we argue that our conclusions are more general. Many such transitions could have occurred in the post-inflationary Universe, as a large number of throats with exponentially different mass scales can be present in the string landscape, leading to several signals of widely different frequencies - a soundscape connected to the landscape of vacua. Detectors such as aLIGO/VIRGO, LISA, and pulsar timing observations with SKA and EPTA have the sensitivity to detect such signals. A distribution of primordial black holes is also a likely consequence, though reliable estimates of masses and their abundance require dedicated numerical simulations, as do the fine details of the gravitational wave spectrum due to the unusual nature of the transition.

  14. Reaction calorimetry for the development of ultrasound-induced polymerization processes in CO2-expanded fluids

    NARCIS (Netherlands)

    Kemmere, M.F.; Kuijpers, M.W.A.; Keurentjes, J.T.F.

    2007-01-01

    A strong viscosity increase upon polymn. hinders radical formation during an ultrasound-induced bulk polymn. Since CO2 acts as a strong anti-solvent for most polymers, it can be used to reduce the viscosity of the reaction mixt. In this work, a process for the ultrasound-induced polymn. in

  15. Looking towards gravitational wave detection

    Science.gov (United States)

    Barsotti, Lisa

    2009-05-01

    It is an exciting time in gravitational wave research. The first generation ground detectors, which aim to detect gravitational waves in the audio-frequency region, have been successfully operated at their design sensitivity. One integrated year of coincident data from the three LIGO interferometers in United States has been collected between 2005 and 2007, in partial coincidence with the two European detectors, VIRGO and GEO. All the detectors are currently being upgraded, and they will come back on-line in the next few months with a factor 2 better sensitivity. A major upgrade of LIGO and VIRGO, scheduled to happen immediately after their upcoming science runs, will bring on-line second generation detectors 4 years from now. Their sensitivity is designed to be 10 times better than the first generation detectors, resulting in an expected event rate of at least a few per year. Looking farther into the future, space-based detectors such as LISA propose to cover a lower range of frequencies which are inaccessible on Earth, enhancing the opportunity of understanding our Universe trough gravitational waves.

  16. Probing a gravitational cat state

    International Nuclear Information System (INIS)

    Anastopoulos, C; Hu, B L

    2015-01-01

    We investigate the nature of a gravitational two-state system (G2S) in the simplest setup in Newtonian gravity. In a quantum description of matter a single motionless massive particle can in principle be in a superposition state of two spatially separated locations. This superposition state in gravity, or gravitational cat state, would lead to fluctuations in the Newtonian force exerted on a nearby test particle. The central quantity of importance for this inquiry is the energy density correlation. This corresponds to the noise kernel in stochastic gravity theory, evaluated in the weak field nonrelativistic limit. In this limit quantum fluctuations of the stress–energy tensor manifest as the fluctuations of the Newtonian force. We describe the properties of such a G2S system and present two ways of measuring the cat state for the Newtonian force, one by way of a classical probe, the other a quantum harmonic oscillator. Our findings include: (i) mass density fluctuations persist even in single particle systems, and they are of the same order of magnitude as the mean; (ii) a classical probe generically records a non-Markovian fluctuating force; (iii) a quantum probe interacting with the G2S system may undergo Rabi oscillations in a strong coupling regime. This simple prototypical gravitational quantum system could provide a robust testing ground to compare predictions from alternative quantum theories, since the results reported here are based on standard quantum mechanics and classical gravity. (paper)

  17. Gravitational radiation from electromagnetic systems

    International Nuclear Information System (INIS)

    Nikishov, A.I.; Ritus, V.I.

    1989-01-01

    It is shown that the spectrum of gravitational radiation of a charge e with mass m, undergoing finite motion in an electromagnetic field, smoothly varying in the neighborhood of the orbit over a region of the order of the radius of curvature, differs in the ultrarelativistic limit from the spectrum of the charge's electromagnetic radiation. The difference consists of the frequency-independent coefficient 4πGm 2 Λ 2 /e 2 , where Λ is of the order of the Lorentz factor of the charge and depends on the direction of the wave vector and on the behavior of the field in the above-indicated region. For a plane-wave external field the gravitational and electromagnetic spectra are strictly proportional to each other for arbitrary velocities of the charge. Localization of the external forces near the orbit violates this proportionality of the spectra and weakens the gravitational radiation by an amount of the order of the square of the Lorentz factor

  18. Gravitational Bhabha scattering

    International Nuclear Information System (INIS)

    Santos, A F; Khanna, Faqir C

    2017-01-01

    Gravitoelectromagnetism (GEM) as a theory for gravity has been developed similar to the electromagnetic field theory. A weak field approximation of Einstein theory of relativity is similar to GEM. This theory has been quantized. Traditional Bhabha scattering, electron–positron scattering, is based on quantized electrodynamics theory. Usually the amplitude is written in terms of one photon exchange process. With the development of quantized GEM theory, the scattering amplitude will have an additional component based on an exchange of one graviton at the lowest order of perturbation theory. An analysis will provide the relative importance of the two amplitudes for Bhabha scattering. This will allow an analysis of the relative importance of the two amplitudes as the energy of the exchanged particles increases. (paper)

  19. Gravitational wave from dark sector with dark pion

    Energy Technology Data Exchange (ETDEWEB)

    Tsumura, Koji [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Yamada, Masatoshi [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); Yamaguchi, Yuya, E-mail: ko2@gauge.scphys.kyoto-u.ac.jp, E-mail: m.yamada@thphys.uni-heidelberg.de, E-mail: yy@particle.sci.hokudai.ac.jp [Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan)

    2017-07-01

    In this work, we investigate the spectra of gravitational waves produced by chiral symmetry breaking in dark quantum chromodynamics (dQCD) sector. The dark pion (π) can be a dark matter candidate as weakly interacting massive particle (WIMP) or strongly interacting massive particle (SIMP). For a WIMP scenario, we introduce the dQCD sector coupled to the standard model (SM) sector with classical scale invariance and investigate the annihilation process of the dark pion via the 2π → 2 SM process. For a SIMP scenario, we investigate the 3π → 2π annihilation process of the dark pion as a SIMP using chiral perturbation theory. We find that in the WIMP scenario the gravitational wave background spectra can be observed by future space gravitational wave antennas. On the other hand, when the dark pion is the SIMP dark matter with the constraints for the chiral perturbative limit and pion-pion scattering cross section, the chiral phase transition becomes crossover and then the gravitational waves are not produced.

  20. Simple Analytic Models of Gravitational Collapse

    Energy Technology Data Exchange (ETDEWEB)

    Adler, R.

    2005-02-09

    Most general relativity textbooks devote considerable space to the simplest example of a black hole containing a singularity, the Schwarzschild geometry. However only a few discuss the dynamical process of gravitational collapse, by which black holes and singularities form. We present here two types of analytic models for this process, which we believe are the simplest available; the first involves collapsing spherical shells of light, analyzed mainly in Eddington-Finkelstein coordinates; the second involves collapsing spheres filled with a perfect fluid, analyzed mainly in Painleve-Gullstrand coordinates. Our main goal is pedagogical simplicity and algebraic completeness, but we also present some results that we believe are new, such as the collapse of a light shell in Kruskal-Szekeres coordinates.

  1. Process-induced formation of imidazoles in selected foods.

    Science.gov (United States)

    Mottier, Pascal; Mujahid, Claudia; Tarres, Adrienne; Bessaire, Thomas; Stadler, Richard H

    2017-08-01

    The presence of 4-methylimidazole (4-MEI), 2-methylimidazole (2-MEI) and 2-acetyl-4-tetrahydroxybutylimidazole (THI) in some foods may result from the usage of caramel colorants E150c and E150d as food additives. This study demonstrates that alkylimidazoles are also byproducts formed from natural constituents in foods during thermal processes. A range of heat-processed foods that are known not to contain caramel colorants were analyzed by isotope dilution LC-MS/MS to determine the contamination levels. Highest 4-MEI concentrations (up to 466µg/kg) were observed in roasted barley, roasted malt and cocoa powders, with the concomitant presence of 2-MEI and/or THI in some cases, albeit at significantly lower levels. Low amounts of 4-MEI (foods such as breakfast cereals and bread toasted to a brown color (medium toasted). The occurrence of 4-MEI in certain processed foods is therefore not a reliable indicator of the presence of the additives E150c or E150d. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Prescription-induced jump distributions in multiplicative Poisson processes.

    Science.gov (United States)

    Suweis, Samir; Porporato, Amilcare; Rinaldo, Andrea; Maritan, Amos

    2011-06-01

    Generalized Langevin equations (GLE) with multiplicative white Poisson noise pose the usual prescription dilemma leading to different evolution equations (master equations) for the probability distribution. Contrary to the case of multiplicative Gaussian white noise, the Stratonovich prescription does not correspond to the well-known midpoint (or any other intermediate) prescription. By introducing an inertial term in the GLE, we show that the Itô and Stratonovich prescriptions naturally arise depending on two time scales, one induced by the inertial term and the other determined by the jump event. We also show that, when the multiplicative noise is linear in the random variable, one prescription can be made equivalent to the other by a suitable transformation in the jump probability distribution. We apply these results to a recently proposed stochastic model describing the dynamics of primary soil salinization, in which the salt mass balance within the soil root zone requires the analysis of different prescriptions arising from the resulting stochastic differential equation forced by multiplicative white Poisson noise, the features of which are tailored to the characters of the daily precipitation. A method is finally suggested to infer the most appropriate prescription from the data.

  3. Prescription-induced jump distributions in multiplicative Poisson processes

    Science.gov (United States)

    Suweis, Samir; Porporato, Amilcare; Rinaldo, Andrea; Maritan, Amos

    2011-06-01

    Generalized Langevin equations (GLE) with multiplicative white Poisson noise pose the usual prescription dilemma leading to different evolution equations (master equations) for the probability distribution. Contrary to the case of multiplicative Gaussian white noise, the Stratonovich prescription does not correspond to the well-known midpoint (or any other intermediate) prescription. By introducing an inertial term in the GLE, we show that the Itô and Stratonovich prescriptions naturally arise depending on two time scales, one induced by the inertial term and the other determined by the jump event. We also show that, when the multiplicative noise is linear in the random variable, one prescription can be made equivalent to the other by a suitable transformation in the jump probability distribution. We apply these results to a recently proposed stochastic model describing the dynamics of primary soil salinization, in which the salt mass balance within the soil root zone requires the analysis of different prescriptions arising from the resulting stochastic differential equation forced by multiplicative white Poisson noise, the features of which are tailored to the characters of the daily precipitation. A method is finally suggested to infer the most appropriate prescription from the data.

  4. Modelling Of Residual Stresses Induced By High Speed Milling Process

    International Nuclear Information System (INIS)

    Desmaison, Olivier; Mocellin, Katia; Jardin, Nicolas

    2011-01-01

    Maintenance processes used in heavy industries often include high speed milling operations. The reliability of the post-process material state has to be studied. Numerical simulation appears to be a very interesting way to supply an efficient residual stresses (RS) distribution prediction.Because the adiabatic shear band and the serrated chip shaping are features of the austenitic stainless steel high speed machining, a 2D high speed orthogonal cutting model is briefly presented. This finite element model, developed on Forge registered software, is based on data taken from Outeiro and al.'s paper [1]. A new behaviour law fully coupling Johnson-Cook's constitutive law and Latham and Cockcroft's damage model is detailed in this paper. It ensures results that fit those found in literature.Then, the numerical tools used on the 2D model are integrated to a 3D high speed milling model. Residual stresses distribution is analysed, on the surface and into the depth of the material. Various revolutions and passes of the two teeth hemispheric mill on the workpiece are simulated. Thus the sensitivity of the residual stresses generation to the cutting conditions can be discussed. In order to validate the 3D model, a comparison of the cutting forces measured by EDF R and D to those given by numerical simulations is achieved.

  5. Gravitational properties of monopole spacetimes near the black hole threshold

    International Nuclear Information System (INIS)

    Lue, Arthur; Weinberg, Erick J.

    2000-01-01

    Although nonsingular spacetimes and those containing black holes are qualitatively quite different, there are continuous families of configurations that connect the two. In this paper we use self-gravitating monopole solutions as tools for investigating the transition between these two types of spacetimes. We show how causally distinct regions emerge as the black hole limit is achieved, even though the measurements made by an external observer vary continuously. We find that near-critical solutions have a naturally defined entropy, despite the absence of a true horizon, and that this has a clear connection with the Hawking-Bekenstein entropy. We find that certain classes of near-critical solutions display naked black hole behavior, although they are not truly black holes at all. Finally, we present a numerical simulation illustrating how an incident pulse of matter can induce the dynamical collapse of a monopole into an extremal black hole. We discuss the implications of this process for the third law of black hole thermodynamics. (c) 2000 The American Physical Society

  6. Coherent network analysis technique for discriminating gravitational-wave bursts from instrumental noise

    International Nuclear Information System (INIS)

    Chatterji, Shourov; Lazzarini, Albert; Stein, Leo; Sutton, Patrick J.; Searle, Antony; Tinto, Massimo

    2006-01-01

    The sensitivity of current searches for gravitational-wave bursts is limited by non-Gaussian, nonstationary noise transients which are common in real detectors. Existing techniques for detecting gravitational-wave bursts assume the output of the detector network to be the sum of a stationary Gaussian noise process and a gravitational-wave signal. These techniques often fail in the presence of noise nonstationarities by incorrectly identifying such transients as possible gravitational-wave bursts. Furthermore, consistency tests currently used to try to eliminate these noise transients are not applicable to general networks of detectors with different orientations and noise spectra. In order to address this problem we introduce a fully coherent consistency test that is robust against noise nonstationarities and allows one to distinguish between gravitational-wave bursts and noise transients in general detector networks. This technique does not require any a priori knowledge of the putative burst waveform

  7. Stochastic Background of Relic Scalar Gravitational Waves tuned by Extended Gravity

    International Nuclear Information System (INIS)

    De Laurentis, Mariafelicia; Capozziello, Salvatore

    2009-01-01

    A stochastic background of relic gravitational waves is achieved by the so called adiabatically-amplified zero-point fluctuations process derived from early inflation. It provides a distinctive spectrum of relic gravitational waves. In the framework of scalar-tensor gravity, we discuss the scalar modes of gravitational waves and the primordial production of this scalar component which is generated beside tensorial one. Then analyze seven different viable f(R)-gravities towards the Solar System tests and stochastic gravitational waves background. It is demonstrated that seven viable f(R)-gravities under consideration not only satisfy the local tests, but additionally, pass the above PPN-and stochastic gravitational waves bounds for large classes of parameters.

  8. Defect-induced transitions in synchronous asymmetric exclusion processes

    International Nuclear Information System (INIS)

    Liu Mingzhe; Wang Ruili; Jiang Rui; Hu Maobin; Gao Yang

    2009-01-01

    The effects of a single local defect in synchronous asymmetric exclusion processes are investigated via theoretical analysis and Monte Carlo simulations. Our theoretical analysis shows that there are four possible stationary phases, i.e., the (low density, low density), (low density, high density), (high density, low density) and (high density, high density) in the system. In the (high density, low density) phase, the system can reach a maximal current which is determined by the local defect, but independent of boundary conditions. A phenomenological domain wall approach is developed to predict dynamic behavior at phase boundaries. The effects of defective hopping probability p on density profiles and currents are investigated. Our investigation shows that the value of p determines phase transitions when entrance rate α and exit rate β are fixed. Density profiles and currents obtained from theoretical calculations are in agreement with Monte Carlo simulations

  9. Characterization of lycopene hydrocolloidal structure induced by tomato processing.

    Science.gov (United States)

    Jazaeri, Sahar; Mohammadi, Abdorreza; Kermani, Amir Mehrabi Panah; Paliyath, Gopinadhan; Kakuda, Yukio

    2018-04-15

    Tomato juice and paste are special type of dispersions, composed of suspended particles (pulp) dispersed in a colloidal liquid medium (serum). The bright red appearance of soluble solid separated by high speed centrifugation denoted the presence of lycopene in this fraction. Since lycopene is a hydrophobic compound it is not expected to appear in the water soluble fraction. HPLC analysis indicated presence of substantial amount of lycopene in soluble fraction which was confirmed by the appearance of lycopene crystals when observed under Transmission Electron Microscope (TEM). Considerable amount of pectin in the soluble fraction led to hypothesis that pectin facilitated the formation of hydrocolloidal system of suspended lycopene during processing. Enzyme treatment confirmed this hypothesis when pectinase effectively disrupted colloidal system and precipitated lycopene. Necessity of the divalent ions to retain the suspension signified the electrostatic interactions in the matrix surrounding lycopene crystals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Nicotine Withdrawal Induces Neural Deficits in Reward Processing.

    Science.gov (United States)

    Oliver, Jason A; Evans, David E; Addicott, Merideth A; Potts, Geoffrey F; Brandon, Thomas H; Drobes, David J

    2017-06-01

    Nicotine withdrawal reduces neurobiological responses to nonsmoking rewards. Insight into these reward deficits could inform the development of targeted interventions. This study examined the effect of withdrawal on neural and behavioral responses during a reward prediction task. Smokers (N = 48) attended two laboratory sessions following overnight abstinence. Withdrawal was manipulated by having participants smoke three regular nicotine (0.6 mg yield; satiation) or very low nicotine (0.05 mg yield; withdrawal) cigarettes. Electrophysiological recordings of neural activity were obtained while participants completed a reward prediction task that involved viewing four combinations of predictive and reward-determining stimuli: (1) Unexpected Reward; (2) Predicted Reward; (3) Predicted Punishment; (4) Unexpected Punishment. The task evokes a medial frontal negativity that mimics the phasic pattern of dopaminergic firing in ventral tegmental regions associated with reward prediction errors. Nicotine withdrawal decreased the amplitude of the medial frontal negativity equally across all trial types (p nicotine dependence (p Nicotine withdrawal had equivocal impact across trial types, suggesting reward processing deficits are unlikely to stem from changes in phasic dopaminergic activity during prediction errors. Effects on tonic activity may be more pronounced. Pharmacological interventions directly targeting the dopamine system and behavioral interventions designed to increase reward motivation and responsiveness (eg, behavioral activation) may aid in mitigating withdrawal symptoms and potentially improving smoking cessation outcomes. Findings from this study indicate nicotine withdrawal impacts reward processing signals that are observable in smokers' neural activity. This may play a role in the subjective aversive experience of nicotine withdrawal and potentially contribute to smoking relapse. Interventions that address abnormal responding to both pleasant and

  11. Gravitational lensing of gravitational waves: a statistical perspective

    Science.gov (United States)

    Li, Shun-Sheng; Mao, Shude; Zhao, Yuetong; Lu, Youjun

    2018-05-01

    In this paper, we study the strong gravitational lensing of gravitational waves (GWs) from a statistical perspective, with particular focus on the high frequency GWs from stellar binary black hole coalescences. These are most promising targets for ground-based detectors such as Advanced Laser Interferometer Gravitational Wave Observatory (aLIGO) and the proposed Einstein Telescope (ET) and can be safely treated under the geometrical optics limit for GW propagation. We perform a thorough calculation of the lensing rate, by taking account of effects caused by the ellipticity of lensing galaxies, lens environments, and magnification bias. We find that in certain GW source rate scenarios, we should be able to observe strongly lensed GW events once per year (˜1 yr-1) in the aLIGO survey at its design sensitivity; for the proposed ET survey, the rate could be as high as ˜80 yr-1. These results depend on the estimate of GW source abundance, and hence can be correspondingly modified with an improvement in our understanding of the merger rate of stellar binary black holes. We also compute the fraction of four-image lens systems in each survey, predicting it to be ˜30 per cent for the aLIGO survey and ˜6 per cent for the ET survey. Finally, we evaluate the possibility of missing some images due to the finite survey duration, by presenting the probability distribution of lensing time delays. We predict that this selection bias will be insignificant in future GW surveys, as most of the lens systems ({˜ } 90{per cent}) will have time delays less than ˜1 month, which will be far shorter than survey durations.

  12. Gravitational wave emission from a bounded source: A treatment in the full nonlinear regime

    International Nuclear Information System (INIS)

    Oliveiral, H.P. de; Damiao Soares, I.

    2004-03-01

    The dynamics of a bounded gravitational collapsing configuration emitting gravitational waves is studied. The exterior spacetime is described by Robinson-Trautman geometries and have the Schwarzschild black hole as its final gravitational configuration, when the gravitational wave emission ceases. The full nonlinear regime is examined by using the Galerkin method that allows us to reduce the equations governing the dynamics to a finite-dimensional dynamical system, after a proper truncation procedure. Gravitational wave emission patterns from given initial configurations are exhibited for several phases of the collapse and the mass-loss ratio that characterizes the amount of mass extracted by the gravitational wave emission is evaluated. We obtain that the smaller initial mass M init of the configuration, the more rapidly the Schwarzschild solution is attained and a larger fraction of M init is lost in the process of gravitational wave emission. Within all our numerical experiments, the distribution of the mass fraction extracted by gravitational wave emission is shown to satisfy the distribution law of nonextensive statistics and this result is independent of the initial configurations considered. (author)

  13. Turbulence of Weak Gravitational Waves in the Early Universe.

    Science.gov (United States)

    Galtier, Sébastien; Nazarenko, Sergey V

    2017-12-01

    We study the statistical properties of an ensemble of weak gravitational waves interacting nonlinearly in a flat space-time. We show that the resonant three-wave interactions are absent and develop a theory for four-wave interactions in the reduced case of a 2.5+1 diagonal metric tensor. In this limit, where only plus-polarized gravitational waves are present, we derive the interaction Hamiltonian and consider the asymptotic regime of weak gravitational wave turbulence. Both direct and inverse cascades are found for the energy and the wave action, respectively, and the corresponding wave spectra are derived. The inverse cascade is characterized by a finite-time propagation of the metric excitations-a process similar to an explosive nonequilibrium Bose-Einstein condensation, which provides an efficient mechanism to ironing out small-scale inhomogeneities. The direct cascade leads to an accumulation of the radiation energy in the system. These processes might be important for understanding the early Universe where a background of weak nonlinear gravitational waves is expected.

  14. Hydrodynamics, fields and constants in gravitational theory

    International Nuclear Information System (INIS)

    Stanyukovich, K.P.; Mel'nikov, V.N.

    1983-01-01

    Results of original inveatigations into problems of standard gravitation theory and its generalizations are presented. The main attention is paid to the application of methods of continuous media techniques in the gravitation theory; to the specification of the gravitation role in phenomena of macro- and microworld, accurate solutions in the case, when the medium is the matter, assigned by hydrodynamic energy-momentum tensor; and to accurate solutions for the case when the medium is the field. GRT generalizations are analyzed, such as the new cosmologic hypothesis which is based on the gravitation vacuum theory. Investigations are performed into the quantization of cosmological models, effects of spontaneous symmetry violation and particle production in cosmology. Graeity theory with fundamental Higgs field is suggested in the framework of which in the atomic unit number one can explain possible variations of the effective gravitational bonds, and in the gravitation bond, variations of masses of all particles

  15. Gravitational waves from instabilities in relativistic stars

    International Nuclear Information System (INIS)

    Andersson, Nils

    2003-01-01

    This paper provides an overview of stellar instabilities as sources of gravitational waves. The aim is to put recent work on secular and dynamical instabilities in compact stars in context, and to summarize the current thinking about the detectability of gravitational waves from various scenarios. As a new generation of kilometre length interferometric detectors is now coming online this is a highly topical theme. The review is motivated by two key questions for future gravitational-wave astronomy: are the gravitational waves from various instabilities detectable? If so, what can these gravitational-wave signals teach us about neutron star physics? Even though we may not have clear answers to these questions, recent studies of the dynamical bar-mode instability and the secular r-mode instability have provided new insights into many of the difficult issues involved in modelling unstable stars as gravitational-wave sources. (topical review)

  16. Process-induced viscoelastic stress in composite laminates

    International Nuclear Information System (INIS)

    Stango, R.J.

    1985-01-01

    In recent years, considerable interest has developed in evaluating the stress response of composite laminates which is associated with cooling the material system from the cure temperature to room temperature. This research examines the fundamental nature of time-dependent residual-thermal stresses in composite laminates which are caused by the extreme temperature reduction encountered during the fabrication process. Viscoelastic stress in finite-width, symmetric composite laminates is examined on the basis of a formulation that employs an incremental hereditary integral approach in conjunction with a quasi-three dimensional finite element analysis. A consistent methodology is developed and employed for the characterization of lamina material properties. Special attention is given to the time-dependent stress response at ply-interface locations near the free-edge. In addition, the influence of cooling path on stress history is examined. Recently published material property data for graphite-epoxy lamina is employed in the analysis. Results of the investigation generally indicate that nominal differences between the thermoelastic and viscoelastic solutions are obtained. Slight changes of the final stress state are observed to result when different cooling paths are selected for the temperature history. The methodology employed is demonstrated to result in an accurate, efficient, and consistent approach for the viscoelastic analysis of advanced composite laminates

  17. High energy instanton induced processes in electroweak theory

    International Nuclear Information System (INIS)

    McLerran, L.

    1992-01-01

    It is well known that in electroweak theory, baryon plus lepton number is conserved by the classical equations of motion. This is of course consistent with the lack of experimental observation of such processes. It is a little less well known that when quantum corrections are included in electroweak theory, baryon plus lepton number is not conserved. This was first discovered as a consequence of the Adler-Bardeen-Bell-Jackiw triangle anomaly. It is perhaps most easily understood as a consequence of vacuum degeneracy, fermion energy level crossing and filling of the negative energy Dirac sea upon second quantization. To understand how baryon plus lepton number is not conserved upon second quantization, consider the situation shown in the energy of the system is shown as a function of a parameter which characterizes the gauge fields, the Chern-Simons charge. The Chern-Simons charge is a function only of the gauge fields, and the B + L change is equal to the change in Chern-Simons charge, ΔQ B+L = ΔQ CS

  18. Production of Purely Gravitational Dark Matter

    OpenAIRE

    Ema, Yohei; Nakayama, Kazunori; Tang, Yong

    2018-01-01

    In the purely gravitational dark matter scenario, the dark matter particle does not have any interaction except for gravitational one. We study the gravitational particle production of dark matter particle in such a minimal setup and show that correct amount of dark matter can be produced depending on the inflation model and the dark matter mass. In particular, we carefully evaluate the particle production rate from the transition epoch to the inflaton oscillation epoch in a realistic inflati...

  19. Compensation for gravitational sag of bent mirror

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Chengwen; Jiang, Hui; He, Yan; Liang, Dongxu; Lan, Xuying; Yan, Shuai [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, CAS, Shanghai 201800 (China); Shu, De-ming [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Li, Aiguo, E-mail: aiguo.li@sinap.ac.cn [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, CAS, Shanghai 201800 (China)

    2017-05-01

    The gravitational sag of aspheric bent mirrors with face-up or face-down geometry produces a nonnegligible optical error. As an effective compensation, width optimization is used to match the combined effects of the gravitational and bending moments. This method is described by analytical expressions and two calculation algorithms. The results of theoretical simulations and finite element analysis have proved that this method can reduce the slope error resulting from gravitational sag to the level of nano radians.

  20. Compensation for gravitational sag of bent mirror

    International Nuclear Information System (INIS)

    Mao, Chengwen; Jiang, Hui; He, Yan; Liang, Dongxu; Lan, Xuying; Yan, Shuai; Shu, De-ming; Li, Aiguo

    2017-01-01

    The gravitational sag of aspheric bent mirrors with face-up or face-down geometry produces a nonnegligible optical error. As an effective compensation, width optimization is used to match the combined effects of the gravitational and bending moments. This method is described by analytical expressions and two calculation algorithms. The results of theoretical simulations and finite element analysis have proved that this method can reduce the slope error resulting from gravitational sag to the level of nano radians.

  1. A radiometer for stochastic gravitational waves

    International Nuclear Information System (INIS)

    Ballmer, Stefan W

    2006-01-01

    The LIGO Scientific Collaboration recently reported a new upper limit on an isotropic stochastic background of gravitational waves obtained based on the data from the third LIGO science run (S3). Here I present a new method for obtaining directional upper limits on stochastic gravitational waves that essentially implements a gravitational wave radiometer. The LIGO Scientific Collaboration intends to use this method for future LIGO science runs

  2. Progress in gravitational wave detection: Interferometers

    International Nuclear Information System (INIS)

    Kuroda, Kazuaki

    2002-01-01

    A gravitational wave (GW) is a physical entity of space-time derived from Einstein's theory of general relativity. Challenging projects to observe gravitational waves are being conducted throughout the world. A Japanese project involving a 300 m baseline laser interferometer, TAMA, achieved 1000 hr of continuous observation with the best sensitivity in the world during the summer of 2001. After achieving promising results, the realization of LCGT (Large-scale Cryogenic Gravitational wave Telescope) will become possible in the near future

  3. Gravitational waves from Abelian gauge fields and cosmic strings at preheating

    International Nuclear Information System (INIS)

    Dufaux, Jean-Francois; Figueroa, Daniel G.; Garcia-Bellido, Juan

    2010-01-01

    Primordial gravitational waves provide a very important stochastic background that could be detected soon with interferometric gravitational wave antennas or indirectly via the induced patterns in the polarization anisotropies of the cosmic microwave background. The detection of these waves will open a new window into the early Universe, and therefore it is important to characterize in detail all possible sources of primordial gravitational waves. In this paper we develop theoretical and numerical methods to study the production of gravitational waves from out-of-equilibrium gauge fields at preheating. We then consider models of preheating after hybrid inflation, where the symmetry breaking field is charged under a local U(1) symmetry. We analyze in detail the dynamics of the system in both momentum and configuration space. We show that gauge fields leave specific imprints in the resulting gravitational wave spectra, mainly through the appearance of new peaks at characteristic frequencies that are related to the mass scales in the problem. We also show how these new features in the spectra correlate with stringlike spatial configurations in both the Higgs and gauge fields that arise due to the appearance of topological winding numbers of the Higgs around Nielsen-Olesen strings. We study in detail the time evolution of the spectrum of gauge fields and gravitational waves as these strings evolve and decay before entering a turbulent regime where the gravitational wave energy density saturates.

  4. Feasibility analysis of gravitational experiments in space

    Science.gov (United States)

    Everitt, C. W. F.

    1977-01-01

    Experiments on gravitation and general relativity suggested by different workers in the past ten or more years are reviewed, their feasibility examined, and the advantages of performing them in space were studied. The experiments include: (1) the gyro relativity experiment; (2) experiments to test the equivalence of gravitational and inertial mass; (3) an experiment to look for nongeodesic motion of spinning bodies in orbit around the earth; (4) experiments to look for changes of the gravitational constant G with time; (5) a variety of suggestions; laboratory tests of experimental gravity; and (6) gravitational wave experiments.

  5. Possible role of torsion in gravitational theories

    International Nuclear Information System (INIS)

    Nieh, H.T.

    1983-01-01

    Torsion is of interest in an indirect way, in that it has the potential of being an important ingredient in a future successful quantum theory of gravitation. Einstein's theory of gravitation, despite its simplicity and elegance, and its successes in large-scale gravitational phenomena, can only be regarded as a macroscopic classical theory. It is a non-renormalizable quantum field theory, and, therefore, lacks the status of a good microscopic theory. It is the search for a successful quantum field theory of gravitation that poses as one of the great challenges to theoretical physics today. (Auth.)

  6. Physics, Astrophysics and Cosmology with Gravitational Waves

    Directory of Open Access Journals (Sweden)

    Sathyaprakash B. S.

    2009-03-01

    Full Text Available Gravitational wave detectors are already operating at interesting sensitivity levels, and they have an upgrade path that should result in secure detections by 2014. We review the physics of gravitational waves, how they interact with detectors (bars and interferometers, and how these detectors operate. We study the most likely sources of gravitational waves and review the data analysis methods that are used to extract their signals from detector noise. Then we consider the consequences of gravitational wave detections and observations for physics, astrophysics, and cosmology.

  7. Observing a Gravitational Wave Background With Lisa

    National Research Council Canada - National Science Library

    Tinto, M; Armstrong, J; Estabrook, F

    2000-01-01

    ... formation of several observables. All are independent of lasers and frequency standard phase fluctuations, but have different couplings to gravitational waves and to the various LISA instrumental noises...

  8. Physics, Astrophysics and Cosmology with Gravitational Waves.

    Science.gov (United States)

    Sathyaprakash, B S; Schutz, Bernard F

    2009-01-01

    Gravitational wave detectors are already operating at interesting sensitivity levels, and they have an upgrade path that should result in secure detections by 2014. We review the physics of gravitational waves, how they interact with detectors (bars and interferometers), and how these detectors operate. We study the most likely sources of gravitational waves and review the data analysis methods that are used to extract their signals from detector noise. Then we consider the consequences of gravitational wave detections and observations for physics, astrophysics, and cosmology.

  9. Gravitational Wave Astrophysics: Opening the New Frontier

    Science.gov (United States)

    Centrella, Joan

    2012-01-01

    A new era in astronomy will begin when the gravitational wave window onto the universe opens in approx. 5 years, as ground-based detectors make the first detections in the high-frequency regime. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources - such as masses, spins, luminosity distances, and orbital parameters - through dense, obscured regions across cosmic time. This talk will explore gravitational waves as cosmic messengers, highlighting key sources and opportunities for multi-messenger astronomy across the gravitational wave spectrum.

  10. Actuality of the Einstein theory of gravitation

    International Nuclear Information System (INIS)

    Ivanenko, D.D.

    1982-01-01

    Problems of actuality of the Einstein theory of gravitation are lightened. The great Einstein theory of gravitation is shown to remain a reliable base of understanding of modern physical world pattern and its inevitable further inexhaustible precising. The main GRT difficulties are enumirated: determination of reference systems, presence of singularities in the theory, absence of consistent determination of the gravity energy, impossibility of accounting the relations between atomic, gravitational and cosmological characteristics. The attention is paid to gauge, twistor problems and to unified interaction theory. The great contribution of the soviet science in the theory of gravitation is stressed

  11. Astrophysical Gravitational Wave Sources Literature Catalog

    Data.gov (United States)

    National Aeronautics and Space Administration — Numerically-generated gravitational waveforms for circular inspiral into Kerr black holes. These waveforms were developed using Scott Hughes' black hole perturbation...

  12. Lattice Gauge Theories Have Gravitational Duals

    International Nuclear Information System (INIS)

    Hellerman, Simeon

    2002-01-01

    In this paper we examine a certain threebrane solution of type IIB string theory whose long-wavelength dynamics are those of a supersymmetric gauge theory in 2+1 continuous and 1 discrete dimension, all of infinite extent. Low-energy processes in this background are described by dimensional deconstruction, a strict limit in which gravity decouples but the lattice spacing stays finite. Relating this limit to the near-horizon limit of our solution we obtain an exact, continuum gravitational dual of a lattice gauge theory with nonzero lattice spacing. H-flux in this translationally invariant background encodes the spatial discreteness of the gauge theory, and we relate the cutoff on allowed momenta to a giant graviton effect in the bulk

  13. Conformal bootstrap, universality and gravitational scattering

    Directory of Open Access Journals (Sweden)

    Steven Jackson

    2015-12-01

    Full Text Available We use the conformal bootstrap equations to study the non-perturbative gravitational scattering between infalling and outgoing particles in the vicinity of a black hole horizon in AdS. We focus on irrational 2D CFTs with large c and only Virasoro symmetry. The scattering process is described by the matrix element of two light operators (particles between two heavy states (BTZ black holes. We find that the operator algebra in this regime is (i universal and identical to that of Liouville CFT, and (ii takes the form of an exchange algebra, specified by an R-matrix that exactly matches the scattering amplitude of 2+1 gravity. The R-matrix is given by a quantum 6j-symbol and the scattering phase by the volume of a hyperbolic tetrahedron. We comment on the relevance of our results to scrambling and the holographic reconstruction of the bulk physics near black hole horizons.

  14. Phenomenology and Astrophysics of Gravitationally-Bound Condensates of Axion-Like Particles

    Energy Technology Data Exchange (ETDEWEB)

    Eby, Joshua Armstrong [Univ. of Cincinnati, OH (United States)

    2017-01-01

    Light, spin-0 particles are ubiquitous in theories of physics beyond the Standard Model, and many of these make good candidates for the identity of dark matter. One very well-motivated candidate of this type is the axion. Due to their small mass and adherence to Bose statistics, axions can coalesce into heavy, gravitationally-bound condensates known as boson stars, also known as axion stars (in particular). In this work, we outline our recent progress in attempts to determine the properties of axion stars. We begin with a brief overview of the Standard Model, axions, and bosonic condensates in general. Then, in the context of axion stars, we will present our recent work, which includes: numerical estimates of the macroscopic properties (mass, radius, and particle number) of gravitationally stable axion stars; a calculation of their decay lifetime through number-changing interactions; an analysis of the gravitational collapse process for very heavy states; and an investigation of the implications of axion stars as dark matter. The basic conclusions of our work are that weakly-bound axion stars are only stable up to some calculable maximum mass, whereas states with larger masses collapse to a small radius, but do not form black holes. During collapse, a rapidly increasing binding energy implies a fast rate of decay to relativistic particles, giving rise to a Bosenova. Axion stars that are otherwise stable could be caused to collapse either by accretion of free particles to masses above the maximum, or through astrophysical collisions; in the latter case, we estimate the rate of collisions and the parameter space relevant to induced collapse.

  15. Effect of Earth gravitational field on the detection of gravitational waves

    International Nuclear Information System (INIS)

    Denisov, V.I.; Eliseev, V.A.

    1987-01-01

    Results of laboratory detection of high-frequency gravitational waves from the view point of gravitation theories formulated on the basis of pseudoeuclidean space-time are calculated. Peculiarities due to different effects of the Earth gravitational field on the rates of gravitational and electromagnetic wave propagation in these theories are analysed. Experiments on check of predictions of the given class of theories are suggested

  16. Numerical and semi-analytical modelling of the process induced distortions in pultrusion

    DEFF Research Database (Denmark)

    Baran, Ismet; Carlone, P.; Hattel, Jesper Henri

    2013-01-01

    , the transient distortions are inferred adopting a semi-analytical procedure, i.e. post processing numerical results by means of analytical methods. The predictions of the process induced distortion development using the aforementioned methods are found to be qualitatively close to each other...

  17. The Scales of Gravitational Lensing

    Directory of Open Access Journals (Sweden)

    Francesco De Paolis

    2016-03-01

    Full Text Available After exactly a century since the formulation of the general theory of relativity, the phenomenon of gravitational lensing is still an extremely powerful method for investigating in astrophysics and cosmology. Indeed, it is adopted to study the distribution of the stellar component in the Milky Way, to study dark matter and dark energy on very large scales and even to discover exoplanets. Moreover, thanks to technological developments, it will allow the measure of the physical parameters (mass, angular momentum and electric charge of supermassive black holes in the center of ours and nearby galaxies.

  18. Testing Fundamental Gravitation in Space

    Energy Technology Data Exchange (ETDEWEB)

    Turyshev, Slava G.

    2013-10-15

    General theory of relativity is a standard theory of gravitation; as such, it is used to describe gravity when the problems in astronomy, astrophysics, cosmology, and fundamental physics are concerned. The theory is also relied upon in many modern applications involving spacecraft navigation, geodesy, and time transfer. Here we review the foundations of general relativity and discuss its current empirical status. We describe both the theoretical motivation and the scientific progress that may result from the new generation of high-precision tests that are anticipated in the near future.

  19. General definition of gravitational tension

    International Nuclear Information System (INIS)

    Harmark, T.; Obers, N.A.

    2004-01-01

    In this note we give a general definition of the gravitational tension in a given asymptotically translationally-invariant spatial direction of a space-time. The tension is defined via the extrinsic curvature in analogy with the Hawking-Horowitz definition of energy. We show the consistency with the ADM tension formulas for asymptotically-flat space-times, in particular for Kaluza-Klein black hole solutions. Moreover, we apply the general tension formula to near-extremal branes, constituting a check for non-asymptotically flat space-times. (author)

  20. Primordial gravitational waves and cosmology.

    Science.gov (United States)

    Krauss, Lawrence M; Dodelson, Scott; Meyer, Stephan

    2010-05-21

    The observation of primordial gravitational waves could provide a new and unique window on the earliest moments in the history of the universe and on possible new physics at energies many orders of magnitude beyond those accessible at particle accelerators. Such waves might be detectable soon, in current or planned satellite experiments that will probe for characteristic imprints in the polarization of the cosmic microwave background, or later with direct space-based interferometers. A positive detection could provide definitive evidence for inflation in the early universe and would constrain new physics from the grand unification scale to the Planck scale.

  1. Gravitational field of relativistic gyratons

    Energy Technology Data Exchange (ETDEWEB)

    Frolov, Valeri P [Theoretical Physics Institute, Department of Physics, University of Alberta, Edmonton, AB, T6G 2J1 (Canada)

    2007-05-15

    A gyraton is an object moving with the speed of light and having finite energy and internal angular momentum (spin). First we derive the gravitational field of a gyraton in the linear approximation. After this we study solutions of the vacuum Einstein equations for gyratons. We demonstrate that these solutions in 4 and higher dimensions reduce to two linear problems in a Euclidean space. A similar reduction is also valid for gyraton solutions of the Einstein-Maxwell gravity and in supergravity. Namely, we demonstrate that in the both cases the solutions in 4 and higher dimensions reduce to linear problems in a Euclidean space.

  2. Gravitational polarizability of black holes

    International Nuclear Information System (INIS)

    Damour, Thibault; Lecian, Orchidea Maria

    2009-01-01

    The gravitational polarizability properties of black holes are compared and contrasted with their electromagnetic polarizability properties. The 'shape' or 'height' multipolar Love numbers h l of a black hole are defined and computed. They are then compared to their electromagnetic analogs h l EM . The Love numbers h l give the height of the lth multipolar 'tidal bulge' raised on the horizon of a black hole by faraway masses. We also discuss the shape of the tidal bulge raised by a test-mass m, in the limit where m gets very close to the horizon.

  3. Review on possible gravitational anomalies

    International Nuclear Information System (INIS)

    Amador, Xavier E

    2005-01-01

    This is an updated introductory review of 2 possible gravitational anomalies that has attracted part of the Scientific community: the Allais effect that occur during solar eclipses, and the Pioneer 10 spacecraft anomaly, experimented also by Pioneer 11 and Ulysses spacecrafts. It seems that, to date, no satisfactory conventional explanation exist to these phenomena, and this suggests that possible new physics will be needed to account for them. The main purpose of this review is to announce 3 other new measurements that will be carried on during the 2005 solar eclipses in Panama and Colombia (Apr. 8) and in Portugal (Oct.15)

  4. Gravitation

    CERN Document Server

    Prasanna, A R

    2017-01-01

    This book suitable for post graduates in Physics and Astrophysics aims at introducing the theory of general relativity as an important background for doing astrophysics. Starting from a detailed discussion of the various mathematical concepts for doing general relativity, the book introduces the geometric description of gravity. It gives a brief historical perspective to classical mechanics and electrodynamics making an attempt to establish the necessity of special relativity as propounded by Einstein extending to General Relativity. This book is a good starting point for post graduates wanting to pursue the modern topics of Cosmology, High energy astrophysics and related areas.

  5. Gravitational lensing of the SNLS supernovae

    International Nuclear Information System (INIS)

    Kronborg, T.

    2011-01-01

    Type Ia supernovae have become an essential tool of modern observational cosmology. By studying the distance-redshift relation of a large number of supernovae, the nature of dark energy can be unveiled. Distances to Type Ia SNe are however affected by gravitational lensing which can induce systematic effects in the measurement of cosmology. The majority of the supernovae is slightly de-magnified whereas a small fraction is significantly magnified due to the mass distribution along the line of sight. This causes naturally an additional dispersion in the observed magnitudes. There are two different ways to estimate the magnification of a supernova. A first method consists in comparing the supernova luminosity, which is measured to about 15% precision, to the mean SN luminosity at the same redshift. Another estimate can be obtained from predicting the magnification induced by the foreground matter density modeled from the measurements of the luminosity of the galaxies with an initial prior on the mass-luminosity relation of the galaxies. A correlation between these 2 estimates will make it possible to tune the initially used mass-luminosity relation resulting in an independent measurement of the dark matter clustering based on the luminosity of SNe Ia. Evidently, this measurement depends crucially on the detection of this correlation also referred to as the lensing signal. This thesis is dedicated to the measurement of the lensing signal in the SNLS 3-year sample. (author)

  6. Quantum gravitational corrections for spinning particles

    International Nuclear Information System (INIS)

    Fröb, Markus B.

    2016-01-01

    We calculate the quantum corrections to the gauge-invariant gravitational potentials of spinning particles in flat space, induced by loops of both massive and massless matter fields of various types. While the corrections to the Newtonian potential induced by massless conformal matter for spinless particles are well known, and the same corrections due to massless minimally coupled scalars http://dx.doi.org/10.1088/0264-9381/27/24/245008, massless non-conformal scalars http://dx.doi.org/10.1103/PhysRevD.87.104027 and massive scalars, fermions and vector bosons http://dx.doi.org/10.1103/PhysRevD.91.064047 have been recently derived, spinning particles receive additional corrections which are the subject of the present work. We give both fully analytic results valid for all distances from the particle, and present numerical results as well as asymptotic expansions. At large distances from the particle, the corrections due to massive fields are exponentially suppressed in comparison to the corrections from massless fields, as one would expect. However, a surprising result of our analysis is that close to the particle itself, on distances comparable to the Compton wavelength of the massive fields running in the loops, these corrections can be enhanced with respect to the massless case.

  7. Velocity structure of protostellar envelopes: gravitational collapse and rotation

    International Nuclear Information System (INIS)

    Belloche, Arnaud

    2002-01-01

    Stars form from the gravitational collapse of pre-stellar condensations in molecular clouds. The major aim of this thesis is to compare the predictions of collapse models with observations of both very young (class 0) protostars and starless condensations in millimeter molecular lines. We wish to understand what determines the masses of forming stars and whether the initial conditions have an effect on the dynamical evolution of a condensation. Using a Monte-Carlo radiative transfer code, we analyze rotation and infall spectroscopic signatures to study the velocity structure of a sample of protostellar condensations. We show that the envelope of the class 0 protostar IRAM 04191 in the Taurus molecular cloud is undergoing both extended, subsonic infall and fast, differential rotation. We propose that the inner part of the envelope is a magnetically supercritical core in the process of decoupling from the ambient cloud still supported by the magnetic field. We suggest that the kinematical properties observed for IRAM 04191 are representative of the physical conditions characterizing isolated protostars shortly after point mass formation. On the other hand, a similar study for the pre-stellar condensations of the Rho Ophiuchi proto-cluster yields mass accretion rates that are an order of magnitude higher than in IRAM 04191. This suggests that individual protostellar collapse in clusters is induced by external disturbances. Moreover, we show that the condensations do not have time to orbit significantly through the proto-cluster gas before evolving into protostars and pre-main-sequence stars. This seems inconsistent with models which resort to dynamical interactions and competitive accretion to build up a mass spectrum comparable to the stellar initial mass function. We conclude that protostellar collapse is nearly spontaneous in regions of isolated star formation such as the Taurus cloud but probably strongly induced in proto-clusters. (author) [fr

  8. Core-Collapse Supernovae, Neutrinos, and Gravitational Waves

    Energy Technology Data Exchange (ETDEWEB)

    Ott, C.D. [TAPIR, California Institute of Technology, Pasadena, California (United States); Kavli Institute for the Physics and Mathematics of the Universe, Kashiwa, Chiba (Japan); O' Connor, E.P. [Canadian Institute for Theoretical Astrophysics, Toronto, Ontario (Canada); Gossan, S.; Abdikamalov, E.; Gamma, U.C.T. [TAPIR, California Institute of Technology, Pasadena, California (United States); Drasco, S. [Grinnell College, Grinnell, Iowa (United States); TAPIR, California Institute of Technology, Pasadena, California (United States)

    2013-02-15

    Core-collapse supernovae are among the most energetic cosmic cataclysms. They are prodigious emitters of neutrinos and quite likely strong galactic sources of gravitational waves. Observation of both neutrinos and gravitational waves from the next galactic or near extragalactic core-collapse supernova will yield a wealth of information on the explosion mechanism, but also on the structure and angular momentum of the progenitor star, and on aspects of fundamental physics such as the equation of state of nuclear matter at high densities and low entropies. In this contribution to the proceedings of the Neutrino 2012 conference, we summarize recent progress made in the theoretical understanding and modeling of core-collapse supernovae. In this, our emphasis is on multi-dimensional processes involved in the explosion mechanism such as neutrino-driven convection and the standing accretion shock instability. As an example of how supernova neutrinos can be used to probe fundamental physics, we discuss how the rise time of the electron antineutrino flux observed in detectors can be used to probe the neutrino mass hierarchy. Finally, we lay out aspects of the neutrino and gravitational-wave signature of core-collapse supernovae and discuss the power of combined analysis of neutrino and gravitational wave data from the next galactic core-collapse supernova.

  9. Core-Collapse Supernovae, Neutrinos, and Gravitational Waves

    International Nuclear Information System (INIS)

    Ott, C.D.; O'Connor, E.P.; Gossan, S.; Abdikamalov, E.; Gamma, U.C.T.; Drasco, S.

    2013-01-01

    Core-collapse supernovae are among the most energetic cosmic cataclysms. They are prodigious emitters of neutrinos and quite likely strong galactic sources of gravitational waves. Observation of both neutrinos and gravitational waves from the next galactic or near extragalactic core-collapse supernova will yield a wealth of information on the explosion mechanism, but also on the structure and angular momentum of the progenitor star, and on aspects of fundamental physics such as the equation of state of nuclear matter at high densities and low entropies. In this contribution to the proceedings of the Neutrino 2012 conference, we summarize recent progress made in the theoretical understanding and modeling of core-collapse supernovae. In this, our emphasis is on multi-dimensional processes involved in the explosion mechanism such as neutrino-driven convection and the standing accretion shock instability. As an example of how supernova neutrinos can be used to probe fundamental physics, we discuss how the rise time of the electron antineutrino flux observed in detectors can be used to probe the neutrino mass hierarchy. Finally, we lay out aspects of the neutrino and gravitational-wave signature of core-collapse supernovae and discuss the power of combined analysis of neutrino and gravitational wave data from the next galactic core-collapse supernova

  10. Denoising of gravitational wave signals via dictionary learning algorithms

    Science.gov (United States)

    Torres-Forné, Alejandro; Marquina, Antonio; Font, José A.; Ibáñez, José M.

    2016-12-01

    Gravitational wave astronomy has become a reality after the historical detections accomplished during the first observing run of the two advanced LIGO detectors. In the following years, the number of detections is expected to increase significantly with the full commissioning of the advanced LIGO, advanced Virgo and KAGRA detectors. The development of sophisticated data analysis techniques to improve the opportunities of detection for low signal-to-noise-ratio events is, hence, a most crucial effort. In this paper, we present one such technique, dictionary-learning algorithms, which have been extensively developed in the last few years and successfully applied mostly in the context of image processing. However, to the best of our knowledge, such algorithms have not yet been employed to denoise gravitational wave signals. By building dictionaries from numerical relativity templates of both binary black holes mergers and bursts of rotational core collapse, we show how machine-learning algorithms based on dictionaries can also be successfully applied for gravitational wave denoising. We use a subset of signals from both catalogs, embedded in nonwhite Gaussian noise, to assess our techniques with a large sample of tests and to find the best model parameters. The application of our method to the actual signal GW150914 shows promising results. Dictionary-learning algorithms could be a complementary addition to the gravitational wave data analysis toolkit. They may be used to extract signals from noise and to infer physical parameters if the data are in good enough agreement with the morphology of the dictionary atoms.

  11. Vestibular nuclei and cerebellum put visual gravitational motion in context.

    Science.gov (United States)

    Miller, William L; Maffei, Vincenzo; Bosco, Gianfranco; Iosa, Marco; Zago, Myrka; Macaluso, Emiliano; Lacquaniti, Francesco

    2008-04-01

    Animal survival in the forest, and human success on the sports field, often depend on the ability to seize a target on the fly. All bodies fall at the same rate in the gravitational field, but the corresponding retinal motion varies with apparent viewing distance. How then does the brain predict time-to-collision under gravity? A perspective context from natural or pictorial settings might afford accurate predictions of gravity's effects via the recovery of an environmental reference from the scene structure. We report that embedding motion in a pictorial scene facilitates interception of gravitational acceleration over unnatural acceleration, whereas a blank scene eliminates such bias. Functional magnetic resonance imaging (fMRI) revealed blood-oxygen-level-dependent correlates of these visual context effects on gravitational motion processing in the vestibular nuclei and posterior cerebellar vermis. Our results suggest an early stage of integration of high-level visual analysis with gravity-related motion information, which may represent the substrate for perceptual constancy of ubiquitous gravitational motion.

  12. Binary star formation: gravitational fragmentation followed by capture

    Science.gov (United States)

    Turner, J. A.; Chapman, S. J.; Bhattal, A. S.; Disney, M. J.; Pongracic, H.; Whitworth, A. P.

    1995-11-01

    We describe in detail one of a sequence of numerical simulations which realize the mechanism of binary star formation proposed by Pringle. In these simulations, collisions between stable molecular cloud clumps produce dense shocked layers, which cool radiatively and fragment gravitationally. The resulting fragments then condense to form protostellar discs, which at the same time fall together and, as a result of tidal and viscous interactions, capture one another to form binary systems. We refer to this mechanism as shock-induced gravitational fragmentation followed by capture, or SGF+C. When the initial clumps are sufficiently massive and/or the Mach number of the collision is sufficiently high, a large number (>~10) of protostellar discs is produced; under these circumstances, the layer fragments first into filaments, and then into beads along the filaments. The marriage of two protostellar discs in this way is `arranged' in the sense that the protostellar discs involved do not form independently. First, they both condense out of the same layer, and probably also out of the same filament within this layer; this significantly increases the likelihood of them interacting dynamically. Secondly, there tends to be alignment between the orbital and spin angular momenta of the interacting protostellar discs, reflecting the fact that these angular momenta derive mainly from the systematic global angular momentum of the off-axis collision which produced the layer; this alignment of the various angular momenta pre-disposes the discs to very dissipative interactions, thereby increasing the probability of producing a strongly bound, long-lasting union. It is a marriage because the binary orbit stabilizes itself rather quickly. Any subsequent orbit evolution, as the protostellar discs `mop up' the surrounding residual gas and interact tidally, tends to harden the orbit. Therefore, as long as a third body does not intervene, the union is binding. Even if a third body does

  13. Applications of disorder-induced melting concept to critical-solute-accumulation processes

    International Nuclear Information System (INIS)

    Lam, N.Q.; Okamoto, P.R.; Heuer, J.K.

    2001-01-01

    A generalized version of the Lindemann melting criterion has recently been used to develop a unified thermodynamic description of disorder-induced amorphization and heat-induced melting. This concept of amorphization as a melting process is based on the fact that the melting temperature of a defective crystal driven far from equilibrium will decrease relative to that of its defect-free equilibrium state. The broader view of melting provides a new perspective of damage-accumulation processes such as radiation damage, ion implantation, ion beam mixing, plastic deformation, and fracture. For example, within this conceptual framework, disorder-induced amorphization is simply polymorphous melting of a critically disordered crystal at temperatures below the glass transition temperature. In the present communication, we discuss the application of the concept to two specific cases: amorphous phase formation during ion implantation and solute segregation-induced intergranular fracture

  14. An isomerization-induced cage-breaking process in a molecular glass former below Tg

    International Nuclear Information System (INIS)

    Teboul, V.; Saiddine, M.; Accary, J.-B.; Nunzi, J.-M.

    2011-01-01

    A recent experimental [P. Karageorgiev, D. Neher, B. Schulz, B. Stiller, U. Pietsch, M. Giersig, L. Brehmer, Nature Mater. 4, 699 (2005)] study has found liquidlike diffusion below the glass-transition temperature in azobenzene-containing materials under irradiation. This result suggests that the isomerization-induced massive mass transport that leads to surface relief gratings formation in these materials, is induced by this huge increase of the matrix diffusion coefficient around the probe. In order to investigate the microscopic origin of the increase of the diffusion, we use molecular dynamics simulations of the photoisomerization of probe dispersed red 1 molecules dispersed inside a glassy molecular matrix. Results show that the increased diffusion is due to an isomerization-induced cage-breaking process. A process that explains the induced cooperative motions recently observed in these photoactive materials.

  15. Interaction of gravitational waves with superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Inan, N.A.; Thompson, J.J. [University of California, Schools of Natural Sciences, Merced, CA (United States); Chiao, R.Y. [University of California, Schools of Natural Sciences and Engineering, Merced, CA (United States)

    2017-06-15

    Applying the Helmholtz Decomposition theorem to linearized General Relativity leads to a gauge-invariant formulation where the transverse-traceless part of the metric perturbation describes gravitational waves in matter. Gravitational waves incident on a superconductor can be described by a linear London-like constituent equation characterized by a ''gravitational shear modulus'' and a corresponding plasma frequency and penetration depth. Electric-like and magnetic-like gravitational tensor fields are defined in terms of the strain field of a gravitational wave. It is shown that in the DC limit, the magnetic-like tensor field is expelled from the superconductor in a gravitational Meissner-like effect. The Cooper pair density is described by the Ginzburg-Landau theory embedded in curved space-time. The ionic lattice is modeled by quantum harmonic oscillators coupled to gravitational waves and characterized by quasi-energy eigenvalues for the phonon modes. The formulation predicts the possibility of a dynamical Casimir effect since the zero-point energy of the ionic lattice phonons is found to be modulated by the gravitational wave, in a quantum analog of a ''Weber-bar effect.'' Applying periodic thermodynamics and the Debye model in the low-temperature limit leads to a free energy density for the ionic lattice. Lastly, we relate the gravitational strain of space to the strain of matter to show that the response to a gravitational wave is far less for the Cooper pair density than for the ionic lattice. This predicts a charge separation effect in the superconductor as a result of the gravitational wave. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Gravitational threshold corrections in non-supersymmetric heterotic strings

    Directory of Open Access Journals (Sweden)

    Ioannis Florakis

    2017-03-01

    Full Text Available We compute one-loop quantum corrections to gravitational couplings in the effective action of four-dimensional heterotic strings where supersymmetry is spontaneously broken by Scherk–Schwarz fluxes. We show that in both heterotic and type II theories of this class, no moduli dependent corrections to the Planck mass are generated. We explicitly compute the one-loop corrections to the R2 coupling and find that, despite the absence of supersymmetry, its contributions may still be organised into representations of subgroups of the modular group, and admit a universal form, determined uniquely by the multiplicities of the ground states of the theory. Moreover, similarly to the case of gauge couplings, also the gravitational sector may become strongly coupled in models which dynamically induce large volume for the extra dimensions.

  17. Lensing of 21-cm fluctuations by primordial gravitational waves.

    Science.gov (United States)

    Book, Laura; Kamionkowski, Marc; Schmidt, Fabian

    2012-05-25

    Weak-gravitational-lensing distortions to the intensity pattern of 21-cm radiation from the dark ages can be decomposed geometrically into curl and curl-free components. Lensing by primordial gravitational waves induces a curl component, while the contribution from lensing by density fluctuations is strongly suppressed. Angular fluctuations in the 21-cm background extend to very small angular scales, and measurements at different frequencies probe different shells in redshift space. There is thus a huge trove of information with which to reconstruct the curl component of the lensing field, allowing tensor-to-scalar ratios conceivably as small as r~10(-9)-far smaller than those currently accessible-to be probed.

  18. Relativity in Combinatorial Gravitational Fields

    Directory of Open Access Journals (Sweden)

    Mao Linfan

    2010-04-01

    Full Text Available A combinatorial spacetime $(mathscr{C}_G| uboverline{t}$ is a smoothly combinatorial manifold $mathscr{C}$ underlying a graph $G$ evolving on a time vector $overline{t}$. As we known, Einstein's general relativity is suitable for use only in one spacetime. What is its disguise in a combinatorial spacetime? Applying combinatorial Riemannian geometry enables us to present a combinatorial spacetime model for the Universe and suggest a generalized Einstein gravitational equation in such model. Forfinding its solutions, a generalized relativity principle, called projective principle is proposed, i.e., a physics law ina combinatorial spacetime is invariant under a projection on its a subspace and then a spherically symmetric multi-solutions ofgeneralized Einstein gravitational equations in vacuum or charged body are found. We also consider the geometrical structure in such solutions with physical formations, and conclude that an ultimate theory for the Universe maybe established if all such spacetimes in ${f R}^3$. Otherwise, our theory is only an approximate theory and endless forever.

  19. Relativité et gravitation

    CERN Document Server

    Tourrenc, Philippe

    1992-01-01

    La relativité générale a cessé d'être une pure théorie justifiée par les "trois tests classiques" disponibles il y a trente ans. Des pulsars, vrais laboratoires de gravitation relativiste, ont été découverts et étudiés. A l'automne 1991 les Etats-Unis ont pris la décision de construire deux détecteurs interférométriques d'ondes gravitationnelles. Au début de l'été 1992, le ministre français de la Recherche et de l'Espace a pris un engagement de même nature concernant le projet VIRGO, projet franco-italien de construction d'une antenne interférométrique. La gravitation relativiste est devenue un riche domaine d'observation et d'expérimentation. Cet ouvrage est un manuel de physique dont les intentions et le contenu se veulent adaptés au contexte scientifique actuel. Il doit beaucoup aux divers enseignements donnés par l'auteur, principalement l'enseignement de relativité générale en maîtrise de physique à l'université Pierre et Marie Curie (Paris VI). Dans la première partie, l...

  20. The binary progenitors of short and long GRBs and their gravitational-wave emission

    Directory of Open Access Journals (Sweden)

    Rueda J. A.

    2018-01-01

    Full Text Available We have sub-classified short and long-duration gamma-ray bursts (GRBs into seven families according to the binary nature of their progenitors. Short GRBs are produced in mergers of neutron-star binaries (NS-NS or neutron star-black hole binaries (NS-BH. Long GRBs are produced via the induced gravitational collapse (IGC scenario occurring in a tight binary system composed of a carbon-oxygen core (COcore and a NS companion. The COcore explodes as type Ic supernova (SN leading to a hypercritical accretion process onto the NS: if the accretion is sufficiently high the NS reaches the critical mass and collapses forming a BH, otherwise a massive NS is formed. Therefore long GRBs can lead either to NS-BH or to NS-NS binaries depending on the entity of the accretion. We discuss for the above compact-object binaries: 1 the role of the NS structure and the nuclear equation of state; 2 the occurrence rates obtained from X and gamma-rays observations; 3 the predicted annual number of detections by the Advanced LIGO interferometer of their gravitational-wave emission.

  1. The binary progenitors of short and long GRBs and their gravitational-wave emission

    Science.gov (United States)

    Rueda, J. A.; Ruffini, R.; Rodriguez, J. F.; Muccino, M.; Aimuratov, Y.; Barres de Almeida, U.; Becerra, L.; Bianco, C. L.; Cherubini, C.; Filippi, S.; Kovacevic, M.; Moradi, R.; Pisani, G. B.; Wang, Y.

    2018-01-01

    We have sub-classified short and long-duration gamma-ray bursts (GRBs) into seven families according to the binary nature of their progenitors. Short GRBs are produced in mergers of neutron-star binaries (NS-NS) or neutron star-black hole binaries (NS-BH). Long GRBs are produced via the induced gravitational collapse (IGC) scenario occurring in a tight binary system composed of a carbon-oxygen core (COcore) and a NS companion. The COcore explodes as type Ic supernova (SN) leading to a hypercritical accretion process onto the NS: if the accretion is sufficiently high the NS reaches the critical mass and collapses forming a BH, otherwise a massive NS is formed. Therefore long GRBs can lead either to NS-BH or to NS-NS binaries depending on the entity of the accretion. We discuss for the above compact-object binaries: 1) the role of the NS structure and the nuclear equation of state; 2) the occurrence rates obtained from X and gamma-rays observations; 3) the predicted annual number of detections by the Advanced LIGO interferometer of their gravitational-wave emission.

  2. Micro-seismic waveform matching inversion based on gravitational search algorithm and parallel computation

    Science.gov (United States)

    Jiang, Y.; Xing, H. L.

    2016-12-01

    Micro-seismic events induced by water injection, mining activity or oil/gas extraction are quite informative, the interpretation of which can be applied for the reconstruction of underground stress and monitoring of hydraulic fracturing progress in oil/gas reservoirs. The source characterises and locations are crucial parameters that required for these purposes, which can be obtained through the waveform matching inversion (WMI) method. Therefore it is imperative to develop a WMI algorithm with high accuracy and convergence speed. Heuristic algorithm, as a category of nonlinear method, possesses a very high convergence speed and good capacity to overcome local minimal values, and has been well applied for many areas (e.g. image processing, artificial intelligence). However, its effectiveness for micro-seismic WMI is still poorly investigated; very few literatures exits that addressing this subject. In this research an advanced heuristic algorithm, gravitational search algorithm (GSA) , is proposed to estimate the focal mechanism (angle of strike, dip and rake) and source locations in three dimension. Unlike traditional inversion methods, the heuristic algorithm inversion does not require the approximation of green function. The method directly interacts with a CPU parallelized finite difference forward modelling engine, and updating the model parameters under GSA criterions. The effectiveness of this method is tested with synthetic data form a multi-layered elastic model; the results indicate GSA can be well applied on WMI and has its unique advantages. Keywords: Micro-seismicity, Waveform matching inversion, gravitational search algorithm, parallel computation

  3. Can observations inside the Solar System reveal the gravitational properties of the quantum vacuum?

    CERN Document Server

    Hajdukovic, Dragan Slavkov

    2013-01-01

    The understanding of the gravitational properties of the quantum vacuum might be the next scientific revolution.It was recently proposed that the quantum vacuum contains the virtual gravitational dipoles; we argue that this hypothesis might be tested within the Solar System. The key point is that quantum vacuum ("enriched" with the gravitational dipoles) induces a retrograde precession of the perihelion. It is obvious that this phenomenon might eventually be revealed by more accurate studies of orbits of planets and orbits of the artificial Earth satellites. However, we suggest that potentialy the best "laboratory" for the study of the gravitational properties of the quantum vacuum is the Dwarf Planet Eris and its satellite Dysnomia; the distance of nearly 100AU makes it the unique system in which the precession of the perihelion of Dysnomia (around Eris) is strongly dominated by the quantum vacuum.

  4. Phase transition and gravitational wave phenomenology of scalar conformal extensions of the Standard Model

    Energy Technology Data Exchange (ETDEWEB)

    Marzola, Luca; Racioppi, Antonio; Vaskonen, Ville [National Institute of Chemical Physics and Biophysics, Tallinn (Estonia)

    2017-07-15

    Thermal corrections in classically conformal models typically induce a strong first-order electroweak phase transition, thereby resulting in a stochastic gravitational background that could be detectable at gravitational wave observatories. After reviewing the basics of classically conformal scenarios, in this paper we investigate the phase transition dynamics in a thermal environment and the related gravitational wave phenomenology within the framework of scalar conformal extensions of the Standard Model. We find that minimal extensions involving only one additional scalar field struggle to reproduce the correct phase transition dynamics once thermal corrections are accounted for. Next-to-minimal models, instead, yield the desired electroweak symmetry breaking and typically result in a very strong gravitational wave signal. (orig.)

  5. Heat-processed ginseng saponin ameliorates the adenine-induced renal failure in rats

    OpenAIRE

    Kim, Eun Jin; Oh, Hyun-A; Choi, Hyuck Jai; Park, Jeong Hill; Kim, Dong-Hyun; Kim, Nam Jae

    2013-01-01

    To evaluate the effect of the saponin of heat-processed ginseng (Sun ginseng, SG), we investigated the protective effect of SG total saponin fraction against adenine-induced chronic renal failure in rats. SG saponin significantly decreased the levels of urea nitrogen and creatinine in the serum, but increased the urinary excretion of urea nitrogen and creatinine, indicating an improvement of renal function. SG saponin also inhibited adenine-induced kidney hypertrophy and edema. SG saponin red...

  6. A distinguishing gravitational property for gravitational equation in higher dimensions

    International Nuclear Information System (INIS)

    Dadhich, Naresh

    2016-01-01

    It is well known that Einstein gravity is kinematic (meaning that there is no non-trivial vacuum solution; i.e. the Riemann tensor vanishes whenever the Ricci tensor does so) in 3 dimension because the Riemann tensor is entirely given in terms of the Ricci tensor. Could this property be universalized for all odd dimensions in a generalized theory? The answer is yes, and this property uniquely singles out pure Lovelock (it has only one Nth order term in the action) gravity for which the Nth order Lovelock-Riemann tensor is indeed given in terms of the corresponding Ricci tensor for all odd, d = 2N + 1, dimensions. This feature of gravity is realized only in higher dimensions and it uniquely picks out pure Lovelock gravity from all other generalizations of Einstein gravity. It serves as a good distinguishing and guiding criterion for the gravitational equation in higher dimensions. (orig.)

  7. A distinguishing gravitational property for gravitational equation in higher dimensions

    Science.gov (United States)

    Dadhich, Naresh

    2016-03-01

    It is well known that Einstein gravity is kinematic (meaning that there is no non-trivial vacuum solution; i.e. the Riemann tensor vanishes whenever the Ricci tensor does so) in 3 dimension because the Riemann tensor is entirely given in terms of the Ricci tensor. Could this property be universalized for all odd dimensions in a generalized theory? The answer is yes, and this property uniquely singles out pure Lovelock (it has only one Nth order term in the action) gravity for which the Nth order Lovelock-Riemann tensor is indeed given in terms of the corresponding Ricci tensor for all odd, d=2N+1, dimensions. This feature of gravity is realized only in higher dimensions and it uniquely picks out pure Lovelock gravity from all other generalizations of Einstein gravity. It serves as a good distinguishing and guiding criterion for the gravitational equation in higher dimensions.

  8. The space-time outside a source of gravitational radiation: the axially symmetric null fluid

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, L. [Universidad Central de Venezuela, Escuela de Fisica, Facultad de Ciencias, Caracas (Venezuela, Bolivarian Republic of); Universidad de Salamanca, Instituto Universitario de Fisica Fundamental y Matematicas, Salamanca (Spain); Di Prisco, A. [Universidad Central de Venezuela, Escuela de Fisica, Facultad de Ciencias, Caracas (Venezuela, Bolivarian Republic of); Ospino, J. [Universidad de Salamanca, Departamento de Matematica Aplicada and Instituto Universitario de Fisica Fundamental y Matematicas, Salamanca (Spain)

    2016-11-15

    We carry out a study of the exterior of an axially and reflection symmetric source of gravitational radiation. The exterior of such a source is filled with a null fluid produced by the dissipative processes inherent to the emission of gravitational radiation, thereby representing a generalization of the Vaidya metric for axially and reflection symmetric space-times. The role of the vorticity, and its relationship with the presence of gravitational radiation is put in evidence. The spherically symmetric case (Vaidya) is, asymptotically, recovered within the context of the 1 + 3 formalism. (orig.)

  9. Stability of merons in gravitational models

    International Nuclear Information System (INIS)

    Akdeniz, K.G.; Hacinliyan, A.; Kalayci, J.

    1982-11-01

    The stability properties of merons are investigated in gravitational models by taking the DeAFF model as a theoretical laboratory. We find that in gravitational models containing Yang-Mills fields merons are unstable. Stability might be possible in N=4 supergravity models with Asub(μ)=0. (author)

  10. Gravitational Metric Tensor Exterior to Rotating Homogeneous ...

    African Journals Online (AJOL)

    The covariant and contravariant metric tensors exterior to a homogeneous spherical body rotating uniformly about a common φ axis with constant angular velocity ω is constructed. The constructed metric tensors in this gravitational field have seven non-zero distinct components.The Lagrangian for this gravitational field is ...

  11. Inertial reference frames and gravitational forces

    International Nuclear Information System (INIS)

    Santavy, I.

    1981-01-01

    The connection between different definitions of inertial, i.e. fundamental, reference frames and the corresponding characterisation of gravitational fields by gravitational forces are considered from the point of view of their possible interpretation in university introductory courses. The introduction of a special class of reference frames, denoted 'mixed reference frames' is proposed and discussed. (author)

  12. How Spherical Is a Cube (Gravitationally)?

    Science.gov (United States)

    Sanny, Jeff; Smith, David

    2015-01-01

    An important concept that is presented in the discussion of Newton's law of universal gravitation is that the gravitational effect external to a spherically symmetric mass distribution is the same as if all of the mass of the distribution were concentrated at the center. By integrating over ring elements of a spherical shell, we show that the…

  13. Neutrino bursts and gravitational waves experiments

    Energy Technology Data Exchange (ETDEWEB)

    Castagnoli, C; Galeotti, P; Saavedra, O [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica

    1978-05-01

    Several experiments have been performed in many countries to observe gravitational waves or neutrino bursts. Since their simultaneous emission may occur in stellar collapse, the authors evaluate the effect of neutrino bursts on gravitational wave antennas and suggest the usefulness of a time correlation among the different detectors.

  14. Amplification caused by gravitational bending of light

    International Nuclear Information System (INIS)

    Schneider, P.

    1985-01-01

    Gravitational bending of light may not only lead to multiple imaging (gravitational lens effect), but also affects the apparent luminosity of a source. It is shown here that a mass distribution near the line-of-sight to any source always increases the observable flux relative to the case in which the deflector is absent

  15. On the field theoretic description of gravitation

    NARCIS (Netherlands)

    Nieuwenhuizen, T.M.; Kleinert, H.; Jantzen, R.T.; Ruffini, R.

    2008-01-01

    Maxwell started to describe gravitation as a field in Minkowski space. Such an approach brought Babak and Grishchuk in 1999 the gravitational energy-momentum tensor. Simple manipulations allow the Einstein equations to take the form Aµν = (8πG/c4)Θµν, where A is the acceleration tensor and Θ, the

  16. Gravitational consequences of modern field theories

    Science.gov (United States)

    Horowitz, Gary T.

    1989-01-01

    Some gravitational consequences of certain extensions of Einstein's general theory of relativity are discussed. These theories are not alternative theories of gravity in the usual sense. It is assumed that general relativity is the appropriate description of all gravitational phenomena which were observed to date.

  17. Self-gravitation in Saturn's rings

    International Nuclear Information System (INIS)

    Salo, H.; Lukkari, J.

    1982-01-01

    In a ring-shaped collisional system self-gravitation reduces the equilibrium values of the geometric and optical thickness. In Saturn's rings both effects are appreciable. The previously found discrepancy between the calculated profile and the observed profile of the rings is chiefly caused by the omission of self-gravitation. (Auth.)

  18. Geodesics analysis of colliding gravitational shock waves

    International Nuclear Information System (INIS)

    Pozdeeva, E.

    2011-01-01

    Full text: (author)We consider collision of charged gravitational shock waves with infinite transverse extension (charged gravitational walls). We study the influence of the charges on the trapped surface formation in the charged walls collision. This consideration has applications in the in heavy ion collisions using a holographic approach in which the charge plays the role of the chemical potential

  19. Gravitational Waves from Oscillons with Cuspy Potentials.

    Science.gov (United States)

    Liu, Jing; Guo, Zong-Kuan; Cai, Rong-Gen; Shiu, Gary

    2018-01-19

    We study the production of gravitational waves during oscillations of the inflaton around the minimum of a cuspy potential after inflation. We find that a cusp in the potential can trigger copious oscillon formation, which sources a characteristic energy spectrum of gravitational waves with double peaks. The discovery of such a double-peak spectrum could test the underlying inflationary physics.

  20. Gravitational waves from binary black holes

    Indian Academy of Sciences (India)

    It is almost a century since Einstein predicted the existence of gravitational waves as one of the consequences of his general theory of relativity. A brief historical overview including Chandrasekhar's contribution to the subject is first presented. The current status of the experimental search for gravitational waves and the ...

  1. Physics of interferometric gravitational wave detectors

    Indian Academy of Sciences (India)

    The Caltech-MIT joint LIGO project is operating three long-baseline interferometers (one of 2 km and two of 4 km) in order to unambiguously measure the infinitesimal displacements of isolated test masses which convey the signature of gravitational waves from astrophysical sources. An interferometric gravitational wave ...

  2. Workshop on gravitational waves and relativistic astrophysics

    Indian Academy of Sciences (India)

    Discussions related to gravitational wave experiments viz. LIGO and LISA as well as to observations of supermassive black holes dominated the workshop sessions on gravitational waves and relativistic astrophysics in the ICGC-2004. A summary of seven papers that were presented in these workshop sessions has been ...

  3. Holographic entanglement entropy and gravitational anomalies

    NARCIS (Netherlands)

    Castro, A.; Detournay, S.; Iqbal, N.; Perlmutter, E.

    2014-01-01

    We study entanglement entropy in two-dimensional conformal field theories with a gravitational anomaly. In theories with gravity duals, this anomaly is holographically represented by a gravitational Chern-Simons term in the bulk action. We show that the anomaly broadens the Ryu-Takayanagi minimal

  4. Observing a Gravitational Wave Background With Lisa

    National Research Council Canada - National Science Library

    Tinto, M; Armstrong, J; Estabrook, F

    2000-01-01

    .... Comparison of the conventional Michelson interferometer observable with the fully-symmetric Sagnac data-type allows unambiguous discrimination between a gravitational wave background and instrumental noise. The method presented here can be used to detect a confusion-limited gravitational wave background.

  5. A generalized variational principle of gravitation

    International Nuclear Information System (INIS)

    El-Tahir, A.

    1987-09-01

    Generalized fourth order differential equations of gravitation are derived. Though similar to those earlier obtained by Lanczos, the present derivation is based on more general assumptions. The geometry-gravity dualism is discussed and the nonlinearity of gravitation is shown to be constrained by the curvature of space. (author). 5 refs

  6. Gravitational radiation and 3D numerical relativity

    International Nuclear Information System (INIS)

    Nakamura, T.

    1986-01-01

    Study of Numerical Relativity in Kyoto is reviewed. Main topics discussed are 2D rotating collapse, phase cancellation effects and perturbation calculation of the gravitational radiation from a particle falling into a black hole. New numerical results on 3D time evolution of pure gravitational waves are also presented

  7. Gravitational bending of light rays in plasma

    International Nuclear Information System (INIS)

    Tsupko, O. Yu.; Bisnovatyi-Kogan, G. S.

    2010-01-01

    We investigate the gravitational lensing effect in presence of plasma. We observe that in a homogeneous plasma the gravitational deflection angle differs from that in vacuum, and it depends on the frequency of the photon. We discuss observational consequences of this dependence for the point-mass lensing and estimate possibility of the observation of this effect by the planned project Radioastron.

  8. GRAVITATIONAL WAVE SIGNATURES OF HYPERACCRETING COLLAPSAR DISKS

    International Nuclear Information System (INIS)

    Kotake, Kei; Takiwaki, Tomoya; Harikae, Seiji

    2012-01-01

    By performing two-dimensional special relativistic (SR) magnetohydrodynamic simulations, we study possible signatures of gravitational waves (GWs) in the context of the collapsar model for long-duration gamma-ray bursts. In our SR simulations, the central black hole is treated as an absorbing boundary. By doing so, we focus on the GWs generated by asphericities in neutrino emission and matter motions in the vicinity of the hyperaccreting disks. We compute nine models by adding initial angular momenta and magnetic fields parametrically to a precollapse core of a 35 M ☉ progenitor star. As for the microphysics, a realistic equation of state is employed and the neutrino cooling is taken into account via a multi-flavor neutrino leakage scheme. To accurately estimate GWs produced by anisotropic neutrino emission, we perform a ray-tracing analysis in general relativity by a post-processing procedure. By employing a stress formula that includes contributions from both magnetic fields and SR corrections, we also study the effects of magnetic fields on the gravitational waveforms. We find that the GW amplitudes from anisotropic neutrino emission show a monotonic increase with time, whose amplitudes are much larger than those from matter motions of the accreting material. We show that the increasing trend of the neutrino GWs stems from the excess of neutrino emission in the direction near parallel to the spin axis illuminated from the hyperaccreting disks. We point out that a recently proposed future space-based interferometer like Fabry-Perot-type DECIGO would permit the detection of these GW signals within ≈100 Mpc.

  9. Study of the spheronization process of glass particles by the gravitational falling process for internal selective radiotherapy; Estudo do processo de esferolizacao por queda gravitacional de particulas vitreas visando a aplicacao em radioterapia interna seletiva

    Energy Technology Data Exchange (ETDEWEB)

    Barros Filho, E.C.; Martinelli, J.R., E-mail: eraldo.filho@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), SP (Brazil); Sene, F.F. [Centro Tecnologico da Marinha em Sao Paulo (CTMS), Sao Paulo, SP (Brazil)

    2011-07-01

    The internal selective radiotherapy is an alternative to treat hepatocellular carcinoma. Glass microspheres containing β{sup -} emitter radionuclide are introduced in the liver, and they are housed preferentially in the region where the cancer cells are located. The microspheres are trapped in the arterioles which feed the tumors, and the β{sup -} particles annihilate the cancer cells. The glass particles must be spherical to avoid unnecessary bleeding, and the particle size must be restricted to a range which optimizes the blocking effect and avoid the migration to other parts of the human body. The particle size distribution of microspheres is not easily predicted since the variation of the aspect ratio and the presence of agglomerates can influence the resulting particle size distribution. In the present work, the spheronization process to obtain microspheres from irregular shape glass particles with suitable diameter and shape for radiotherapy treatment is studied. (author)

  10. EM-induced processes in heavy ion collisions with the ATLAS detector at the LHC

    CERN Document Server

    Steinberg, Peter; The ATLAS collaboration

    2018-01-01

    Electromagnetic processes provide new tools for studying the partonic structure of nuclei, and possibly for directly probing the quark gluon plasma. Ultra-peripheral heavy ion collisions occur when the nuclei have large impact parameter and interact through photon-induced reactions. These include processes in which an energetic photon emitted by one nucleus resolves the partonic structure of the other and stimulates jet production. Much like deep inelastic scattering, such processes provide a clean probe of the nuclear parton distributions. Jet photo-production represents the most direct opportunity to study nuclear parton distributions until a future electron-ion collider is constructed. This talk presents measurements of ultra-peripheral jet photo-production in Pb+Pb collisions with the ATLAS detector at the LHC. It also presents another application of EM-induced processes, where dimuons produced by gamma-gamma processes are observed to show a centrality-dependent broadening in their opening angle, which ca...

  11. PRESSURE SHIFT AND GRAVITATIONAL REDSHIFT OF BALMER LINES IN WHITE DWARFS: REDISCUSSION

    Energy Technology Data Exchange (ETDEWEB)

    Halenka, Jacek; Olchawa, Wieslaw [Institute of Physics, University of Opole, ul. Oleska 48, 45-052, Opole (Poland); Madej, Jerzy [Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa (Poland); Grabowski, Boleslaw, E-mail: halenka@uni.opole.pl, E-mail: wolch@uni.opole.pl, E-mail: jm@astrouw.edu.pl, E-mail: bgrab@uni.opole.pl [Wroclaw School of Information Technology WWSIS “Horyzont,” ul. Wejherowska 28, 54-239 Wroclaw (Poland)

    2015-08-01

    The Stark-induced shift and asymmetry, the so-called pressure shift (PS) of H{sub α} and H{sub β} Balmer lines in spectra of DA white dwarfs (WDs), have been examined in detail as masking effects in measurements of the gravitational redshift in WDs. The results are compared with our earlier ones from a quarter of a century ago. In these earlier papers, the standard, symmetrical Stark line profiles, as a dominant constituent of the Balmer line profiles but shifted as a whole by the PS effect, were applied to all spectrally active layers of the WD atmosphere. At present, in each of the WD layers, the Stark line profiles (especially of H{sub β}) are inherently asymmetrical and shifted due to the effects of strong inhomogeneity of the perturbing fields in plasma. To calculate the Stark line profiles in successive layers of the WD atmosphere we used the modified Full Computer Simulation Method, able to take adequately into account the complexity of local elementary quantum processes in plasma. In the case of the H{sub α} line, the present value of Stark-induced shift of the synthetic H{sub α} line profile is about half the previous one and it is negligible in comparison with the gravitational redshift. In the case of the H{sub β} line, the present value of Stark-induced shift of the synthetic H{sub β} line profile is about twice the previous one. The source of this extra shift is the asymmetry of H{sub β} peaks.

  12. Gravitational Mass, Its Mechanics - What It Is; How It Operates

    OpenAIRE

    Ellman, Roger

    1999-01-01

    The earlier paper, Inertial Mass, Its Mechanics - What It Is; How It Operates, developed the mechanics of inertial mass. The present paper is for the purpose of equivalently developing gravitation. The behavior of gravitation is well known, as described by Newton's Law of Gravitation. But just what gravitational mass is, how gravitational behavior comes about, what in material reality produces the effects of gravitational mass, has been little understood. The only extant hypotheses involve th...

  13. Gravitational wave emission from oscillating millisecond pulsars

    Science.gov (United States)

    Alford, Mark G.; Schwenzer, Kai

    2015-02-01

    Neutron stars undergoing r-mode oscillation emit gravitational radiation that might be detected on the Earth. For known millisecond pulsars the observed spin-down rate imposes an upper limit on the possible gravitational wave signal of these sources. Taking into account the physics of r-mode evolution, we show that only sources spinning at frequencies above a few hundred Hertz can be unstable to r-modes, and we derive a more stringent universal r-mode spin-down limit on their gravitational wave signal. We find that this refined bound limits the gravitational wave strain from millisecond pulsars to values below the detection sensitivity of next generation detectors. Young sources are therefore a more promising option for the detection of gravitational waves emitted by r-modes and to probe the interior composition of compact stars in the near future.

  14. Sensitivity of a combined gravitational antenna

    International Nuclear Information System (INIS)

    Kulagin, V.V.; Rudenko, V.N.

    1986-01-01

    A modification of a combined optico-acoustic gravitational antenna: a long-base laser interferometer, where free masses are changed by Weber resonators, is suggested. The combined gravitational antenna can possess sensitivity h min ∼ 10 -18 without deep cooling of Weber resonators and h min ∼ 10 -19 at helium temperaure of the resonators. This antenna has the following new quantities: presence of three independent responses, that permits to a considerable extent to exclude non-gravitational effects; presence of responses of two separated Weber resonators, that permits to register the wave character of gravitational perturbation by measuring phase shift between relaxation ''tails''. It means that one may with certainty register the wave structure of gravitational radiation for perturbation of metrics h, exceeding the threshold sensitivity of the known detectors by an order

  15. Gravity's kiss the detection of gravitational waves

    CERN Document Server

    Collins, Harry

    2017-01-01

    Scientists have been trying to confirm the existence of gravitational waves for fifty years. Then, in September 2015, came a "very interesting event" (as the cautious subject line in a physicist's email read) that proved to be the first detection of gravitational waves. In Gravity's Kiss, Harry Collins -- who has been watching the science of gravitational wave detection for forty-three of those fifty years and has written three previous books about it -- offers a final, fascinating account, written in real time, of the unfolding of one of the most remarkable scientific discoveries ever made. Predicted by Einstein in his theory of general relativity, gravitational waves carry energy from the collision or explosion of stars. Dying binary stars, for example, rotate faster and faster around each other until they merge, emitting a burst of gravitational waves. It is only with the development of extraordinarily sensitive, highly sophisticated detectors that physicists can now confirm Einstein's prediction. This is...

  16. Theory and experiment in gravitational physics

    Science.gov (United States)

    Will, C. M.

    New technological advances have made it feasible to conduct measurements with precision levels which are suitable for experimental tests of the theory of general relativity. This book has been designed to fill a new need for a complete treatment of techniques for analyzing gravitation theory and experience. The Einstein equivalence principle and the foundations of gravitation theory are considered, taking into account the Dicke framework, basic criteria for the viability of a gravitation theory, experimental tests of the Einstein equivalence principle, Schiff's conjecture, and a model theory devised by Lightman and Lee (1973). Gravitation as a geometric phenomenon is considered along with the parametrized post-Newtonian formalism, the classical tests, tests of the strong equivalence principle, gravitational radiation as a tool for testing relativistic gravity, the binary pulsar, and cosmological tests.

  17. The confrontation between gravitation theory and experiment

    International Nuclear Information System (INIS)

    Will, C.M.

    1979-01-01

    After an introductory section, an analysis is given of the foundations of gravitation theory - principles of equivalence, the fundamental criteria for the viability of a gravitational theory, and the experiments that support those criteria. One of the principal conclusions is that the correct, viable theory of gravity must in all probability be a 'metric' theory. Attention is focussed on solar-system tests, using a 'theory of theories' known as the parametrized post-Newtonian formalism that encompasses most metric theories of gravity and that is ideally suited to the solar-system arena. Gravitational radiation is discussed as a possible tool for testing gravitational theory. The binary pulsar, a new , 'stellar-system' testing ground is studied. Tests of gravitation theory in a cosmic arena are described. (U.K.)

  18. Gravitational waves in cold dark matter

    Science.gov (United States)

    Flauger, Raphael; Weinberg, Steven

    2018-06-01

    We study the effects of cold dark matter on the propagation of gravitational waves of astrophysical and primordial origin. We show that the dominant effect of cold dark matter on gravitational waves from astrophysical sources is a small frequency dependent modification of the propagation speed of gravitational waves. However, the magnitude of the effect is too small to be detected in the near future. We furthermore show that the spectrum of primordial gravitational waves in principle contains detailed information about the properties of dark matter. However, depending on the wavelength, the effects are either suppressed because the dark matter is highly nonrelativistic or because it contributes a small fraction of the energy density of the universe. As a consequence, the effects of cold dark matter on primordial gravitational waves in practice also appear too small to be detectable.

  19. Fundamentals of interferometric gravitational wave detectors

    CERN Document Server

    Saulson, Peter R

    2017-01-01

    LIGO's recent discovery of gravitational waves was headline news around the world. Many people will want to understand more about what a gravitational wave is, how LIGO works, and how LIGO functions as a detector of gravitational waves.This book aims to communicate the basic logic of interferometric gravitational wave detectors to students who are new to the field. It assumes that the reader has a basic knowledge of physics, but no special familiarity with gravitational waves, with general relativity, or with the special techniques of experimental physics. All of the necessary ideas are developed in the book.The first edition was published in 1994. Since the book is aimed at explaining the physical ideas behind the design of LIGO, it stands the test of time. For the second edition, an Epilogue has been added; it brings the treatment of technical details up to date, and provides references that would allow a student to become proficient with today's designs.

  20. Age and gravitational separation of the stratospheric air over Indonesia

    Directory of Open Access Journals (Sweden)

    S. Sugawara

    2018-02-01

    Full Text Available The gravitational separation of major atmospheric components, in addition to the age of air, would provide additional useful information about stratospheric circulation. However, observations of the age of air and gravitational separation are still geographically sparse, especially in the tropics. In order to address this issue, air samples were collected over Biak, Indonesia in February 2015 using four large plastic balloons, each loaded with two compact cryogenic samplers. With a vertical resolution of better than 2 km, air samples from seven different altitudes were analyzed for CO2 and SF6 mole fractions, δ15N of N2, δ18O of O2, and δ(Ar∕N2 to examine the vertically dependent age and gravitational separation of air in the tropical tropopause layer (TTL and the equatorial stratosphere. By comparing their measured mole fractions with aircraft observations in the upper tropical troposphere, we have found that CO2 and SF6 ages increase gradually with increasing altitude from the TTL to 22 km, and then rapidly from there up to 29 km. The CO2 and SF6 ages agree well with each other in the TTL and in the lower stratosphere, but show a significant difference above 24 km. The average values of δ15N of N2, δ18O of O2, and δ(Ar∕N2 all show a small but distinct upward decrease due to the gravitational separation effect. Simulations with a two-dimensional atmospheric transport model indicate that the gravitational separation effect decreases as tropical upwelling is enhanced. From the model calculations with enhanced eddy mixing, it is also found that the upward increase in air age is magnified by horizontal mixing. These model simulations also show that the gravitational separation effect remains relatively constant in the lower stratosphere. The results of this study strongly suggest that the gravitational separation, combined with the age of air, can be used to diagnose air transport processes in the stratosphere.

  1. Competition of neutrino and gravitational radiation in neutron star formation

    International Nuclear Information System (INIS)

    Kazanas, D.; Schramm, D.N.

    1976-01-01

    The possibility is explored that neutrino radiation, rather than gravitational radiation, may be the dominant way by which non-radial pulsations are damped out in a collapsing star. If this is so it implies that hopes of detecting gravity waves from supernovae explosions are very optimistic. Neutron stars and black holes are probably the collapsed central remnants of a supernovae explosion. These objects presumably originate from collapse of the cores of sufficiently massive stars, following the cessation of thermonuclear burning. Although there is at present no completely consistent detailed theory as to how collapse of the core and the subsequent supernova explosion take place, a general model exists for the final stages of stellar evolution and supernovae explosions. According to this model the electrons of a sufficiently massive stellar core, due to the high density and temperature, become absorbed by the protons through the reaction p + e - → n + v. Very large numbers of neutrinos, resulting from this and other thermal processes, such as pair annihilation, plasma decay, and Bremsstrahlung, are emitted, taking away most of the gravitational energy of the collapse. These neutrinos possibly drive ejection of the overlying stellar mantle, whilst the neutron-rich core collapses further to a condensed remnant. Gravitational radiation comes into play only at very late stages of the collapse. All of this implies that neutrino radiation might contribute to the decay of the non-radial oscillations of the collapsing core and the newly formed neutron star, possibly damping out these oscillations much faster than gravitational radiation. In order to obtain a more quantitative answer to the question the effects of neutrino radiation on the non-radial oscillations are examined. The implication is that neutrino radiation, by more rapid damping of the non-radial oscillations of a newly formed neutron star in a supernova explosion, would hinder gravitational radiation and

  2. Modular Gravitational Reference Sensor (MGRS) For Astrophysics and Astronomy

    Science.gov (United States)

    Sun, Ke-Xun; Buchman, S.; Byer, R. L.; DeBra, D.; Goebel, J.; Allen, G.; Conklin, J.; Gerardi, D.; Higuchi, S.; Leindecker, N.; Lu, P.; Swank, A.; Torres, E.; Trillter, M.; Zoellner, A.

    2009-01-01

    The study of space-time for gravitational wave detection and cosmology beyond Einstein will be an important theme for astrophysics and astronomy in decades to come. Laser Interferometric Space Antenna (LISA) is designed for detecting gravitational wave in space. The Modular Gravitational Reference Sensor (MGRS) is developed as the next generation core instrument for space-time research, including gravitational wave detection beyond LISA, and an array of precision experiments in space. The MGRS provide a stable gravitational cardinal point in space-time by using a test sphere, which eliminates the need for orientation control, minimizing disturbances. The MGRS measures the space-time variation via a two step process: measurement between test mass and housing, and between housings of two spacecraft. Our Stanford group is conducting systematic research and development on the MGRS. Our initial objectives are to gain a system perspective of the MGRS, to develop component technologies, and to establish test platforms. We will review our recent progress in system technologies, optical displacement and angle sensing, diffractive optics, proof mass characterization, UV LED charge management system and space qualification, thermal control and sensor development. Some highlights of our recent results are: Demonstration of the extreme radiation hardness of UV LED which sustained 2 trillion protons per square centimeter; measurement of mass center offset down to 300 nm, and measurement of small angle 0.2 nrad per root hertz using a compact grating angular sensor. The Stanford MGRS program has made exceptional contribution to education of next generation scientists and engineers. We have undergraduate and graduate students in aeronautical and astronautic engineering, applied physics, cybernetics, electrical engineering, mechanical engineering, and physics. We have also housed a number of high school students in our labs for education and public outreach.

  3. Gravitational segregation of liquid slag in large ladle

    Directory of Open Access Journals (Sweden)

    J. Chen

    2012-04-01

    Full Text Available The process of gravitational segregation makes liquid steel slag components occur differentiation. And it shows that the upper part slag in the slag ladle contains higher CaO; and the lower part slag contains higher SiO2. The content of MgO (5,48 % in the upper part slag is higher than that of the lower part (2,50 %, and only Al2O3 content of the upper and the lower part slag is close to each other. The difference of chemical compositions in the slag ladle shows that there is gravitational segregation during slow solidification of liquid steel slag, which will has some impact of the steel slag processing on the large slag ladle.

  4. Gravitational lenses and cosmological evolution

    International Nuclear Information System (INIS)

    Peacock, J.A.

    1982-01-01

    The effect of gravitational lensing on the apparent cosmological evolution of extragalactic radio sources is investigated. Models for a lens population consisting of galaxies and clusters of galaxies are constructed and used to calculate the distribution of amplification factors caused by lensing. Although many objects at high redshifts are predicted to have flux densities altered by 10 to 20 per cent relative to a homogeneous universe, flux conservation implies that de-amplification is as common as amplification. The effects on cosmological evolution as inferred from source counts and redshift data are thus relatively small; the slope of the counts is not large enough for intrinsically rare lensing events of high amplitude to corrupt observed samples. Lensing effects may be of greater importance for optically selected quasars, where lenses of mass as low as approximately 10 -4 solar mass can cause large amplifications. (author)

  5. Gravitational effects of global strings

    International Nuclear Information System (INIS)

    Aryal, M.; Everett, A.E.

    1986-01-01

    We have obtained the gravitational field, in the weak-field approximation, of cosmic strings formed in a phase transition in which a global symmetry is broken (global strings). The effect of this field on light rays passing a global string is found, and the resulting formation of double images and production of discontinuities in the microwave background temperature compared with the corresponding results for gauge strings. There are some differences in the case of global strings, reflecting the fact that the space surrounding such strings is not purely conical. However, the differences between gauge and global strings with masses suitable to explain galaxy formation are small, and the task of distinguishing them observationally appears difficult at best

  6. An axisymmetric gravitational collapse code

    Energy Technology Data Exchange (ETDEWEB)

    Choptuik, Matthew W [CIAR Cosmology and Gravity Program, Department of Physics and Astronomy, University of British Columbia, Vancouver BC, V6T 1Z1 (Canada); Hirschmann, Eric W [Department of Physics and Astronomy, Brigham Young University, Provo, UT 84604 (United States); Liebling, Steven L [Southampton College, Long Island University, Southampton, NY 11968 (United States); Pretorius, Frans [Theoretical Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)

    2003-05-07

    We present a new numerical code designed to solve the Einstein field equations for axisymmetric spacetimes. The long-term goal of this project is to construct a code that will be capable of studying many problems of interest in axisymmetry, including gravitational collapse, critical phenomena, investigations of cosmic censorship and head-on black-hole collisions. Our objective here is to detail the (2+1)+1 formalism we use to arrive at the corresponding system of equations and the numerical methods we use to solve them. We are able to obtain stable evolution, despite the singular nature of the coordinate system on the axis, by enforcing appropriate regularity conditions on all variables and by adding numerical dissipation to hyperbolic equations.

  7. An axisymmetric gravitational collapse code

    International Nuclear Information System (INIS)

    Choptuik, Matthew W; Hirschmann, Eric W; Liebling, Steven L; Pretorius, Frans

    2003-01-01

    We present a new numerical code designed to solve the Einstein field equations for axisymmetric spacetimes. The long-term goal of this project is to construct a code that will be capable of studying many problems of interest in axisymmetry, including gravitational collapse, critical phenomena, investigations of cosmic censorship and head-on black-hole collisions. Our objective here is to detail the (2+1)+1 formalism we use to arrive at the corresponding system of equations and the numerical methods we use to solve them. We are able to obtain stable evolution, despite the singular nature of the coordinate system on the axis, by enforcing appropriate regularity conditions on all variables and by adding numerical dissipation to hyperbolic equations

  8. Detections of the Gravitational Waves

    Directory of Open Access Journals (Sweden)

    José Maria Filardo Bassalo

    2016-12-01

    Full Text Available On February 11, 2016, during a conference held at the National Science Foundation (NSF, in Washington, D.C., the American physicist David Reitze, Executive Director of the Laser Interferometer Gravitacional-Wave Observatory (LIGO announced that it had been observed on September 14, 2015 Gravitational Waves (GW. This event was named GW150914. A second observation was also done by the LIGO on December 26, 2015 named GW151226. The signals of these two events are similar and are due to the coalescence of a binary black holes (BH. The GW sources are distant, respectively, of ~ 410 Mpc and ~ 440 Mpc from the Earth. To understand the significance of this extraordinary events we will make a historical summary of the GW and the BH.

  9. An elementary approach to the gravitational Doppler shift

    International Nuclear Information System (INIS)

    Wörner, C H; Rojas, Roberto

    2017-01-01

    In college physics courses, treatment of the Doppler effect is usually done far from the first introduction to kinematics. This paper aims to apply a graphical treatment to describe the gravitational redshift, by considering the Doppler effect in two accelerated reference frames and exercising the equivalence principle. This approach seems appropriate to discuss with beginner students and could serve to enrich the didactic processes. (paper)

  10. Application of Compressive Sensing to Gravitational Microlensing Experiments

    Science.gov (United States)

    Korde-Patel, Asmita; Barry, Richard K.; Mohsenin, Tinoosh

    2016-01-01

    Compressive Sensing is an emerging technology for data compression and simultaneous data acquisition. This is an enabling technique for significant reduction in data bandwidth, and transmission power and hence, can greatly benefit spaceflight instruments. We apply this process to detect exoplanets via gravitational microlensing. We experiment with various impact parameters that describe microlensing curves to determine the effectiveness and uncertainty caused by Compressive Sensing. Finally, we describe implications for spaceflight missions.

  11. Studies of short and long memory in mining-induced seismic processes

    Science.gov (United States)

    Węglarczyk, Stanisław; Lasocki, Stanisław

    2009-09-01

    Memory of a stochastic process implies its predictability, understood as a possibility to gain information on the future above the random guess level. Here we search for memory in the mining-induced seismic process (MIS), that is, a process induced or triggered by mining operations. Long memory is investigated by means of the Hurst rescaled range analysis, and the autocorrelation function estimate is used to test for short memory. Both methods are complemented with result uncertainty analyses based on different resampling techniques. The analyzed data comprise event series from Rudna copper mine in Poland. The studies show that the interevent time and interevent distance processes have both long and short memory. MIS occurrences and locations are internally interrelated. Internal relations among the sizes of MIS events are apparently weaker than those of other two studied parameterizations and are limited to long term interactions.

  12. Influence of processing-induced phase transformations on the dissolution of theophylline tablets

    OpenAIRE

    Debnath, Smita; Suryanarayanan, Raj

    2004-01-01

    The object of this investigation was to evaluate the influence of (1) processing-induced decrease in drug crystallinity and (2) phase transformations during dissolution, on the per-formance of theophylline tablet formulations. Anhydrous theophylline underwent multiple transformations (anhydrate »hydrate»anhydrate) during processing. Although the crystallinity of the anhydrate obtained finally was lower than that of the unprocessed drug, it dissolved at a slower rate. This decrease in dissolut...

  13. Search for QCD Instanton-Induced Processes at HERA in the High-$Q^2$ Domain

    CERN Document Server

    Andreev, Vladimir; Begzsuren, Khurelbaatar; Belousov, Anatoli; Bolz, Arthur; Boudry, Vincent; Brandt, Gerhard; Brisson, Violette; Britzger, Daniel; Buniatyan, Armen; Bylinkin, Alexander; Bystritskaya, Lena; Campbell, Alan; Cantun Avila, Karla~Beatriz; Cerny, Karel; Chekelian, Vladimir; Contreras, Guillermo; Cvach, Jaroslav; Dainton, John; Daum, Karin; Diaconu, Cristinel; Dobre, Monica; Dodonov, Vitaliy; Eckerlin, Guenter; Egli, Stephan; Elsen, Eckhard; Favart, Laurent; Fedotov, Alexandre; Feltesse, Joel; Ferencei, Jozef; Fleischer, Manfred; Fomenko, Alexander; Gabathuler, Erwin; Gayler, Joerg; Ghazaryan, Samvel; Goerlich, Lidia; Gogitidze, Nelly; Gouzevitch, Maxime; Grab, Christoph; Grebenyuk, Anastasia; Greenshaw, Timothy; Grindhammer, Guenter; Haidt, Dieter; Henderson, Rob~CW; Hladky, Jan; Hoffmann, Dirk; Horisberger, Roland; Hreus, Tomas; Huber, Florian; Jacquet, Marie; Janssen, Xavier; Jung, Hannes; Kapichine, Mikhail; Katzy, Judith; Kiesling, Christian; Klein, Max; Kleinwort, Claus; Kogler, Roman; Kostka, Peter; Kretzschmar, Jan; Krücker, Dirk; Krüger, K.; Landon, Murrough; Lange, Wolfgang; Laycock, Paul; Lebedev, Andrei; Levonian, Sergey; Lipka, Katerina; List, Benno; List, Jenny; Lobodzinski, Bogdan; Malinovski, Evgenij; Martyn, Hans-Ulrich; Maxfield, Steve~J; Mehta, Andrew; Meyer, Andreas; Meyer, Hinrich; Meyer, Joachim; Mikocki, Stanislav; Morozov, Anatoly; Müller, Katharina; Naumann, Thomas; Newman, Paul~R; Niebuhr, Carsten; Nowak, Grazyna; Olsson, Jan~Erik; Ozerov, Dmitri; Pascaud, Christian; Patel, Girish; Perez, Emmanuelle; Petrukhin, Alexey; Picuric, Ivana; Pirumov, Hayk; Pitzl, Daniel; Placakyte, Ringaile; Pokorny, Boris; Polifka, Richard; Radescu, Voica; Raicevic, Natasa; Ravdandorj, Togoo; Reimer, Petr; Rizvi, Eram; Robmann, Peter; Roosen, Robert; Rostovtsev, Andrei; Rotaru, Marina; Rusakov, Serguei; Salek, David; Sankey, Dave~PC; Sauter, Michel; Sauvan, Emmanuel; Schmitt, Stefan; Schoeffel, Laurent; Schöning, Andre; Sefkow, Felix; Shushkevich, Stanislav; Soloviev, Yuri; Sopicki, Pawel; South, David; Spaskov, Vladimir; Specka, Arnd; Steder, Michael; Stella, Bruno; Straumann, Ulrich; Sykora, Tomas; Thompson, Paul; Traynor, Daniel; Truöl, Peter; Tsakov, Ivan; Tseepeldorj, Baatar; Turnau, Jacek; Valkarova, Alice; Vallee, Claude; Van Mechelen, Pierre; Vazdik, Iakov; Wegener, Dietrich; Wünsch, Eberhard; Zacek, Jozef; Zhang, Zhiqing; Zlebcik, Radek; Zohrabyan, Hamlet; Zomer, Fabian

    2016-07-07

    Signals of QCD instanton-induced processes are searched for in neutral current deep-inelastic scattering at the electron-proton collider HERA in the kinematic region defined by the Bjorken-scaling variable $x > 10^{-3}$, the inelasticity $0.2< y < 0.7$ and the photon virtuality $150 < Q^2 < 15000$ GeV$^2$. The search is performed using H1 data corresponding to an integrated luminosity of ~$351$ pb$^{-1}$. No evidence for the production of QCD instanton-induced events is observed. Upper limits on the cross section for instanton-induced processes between $1.5$~pb and $6$~pb, at $95\\%$~ confidence level, are obtained depending on the kinematic domain in which instantons could be produced. Compared to earlier publications, the limits are improved by an order of magnitude and for the first time are challenging theory predictions.

  14. Effect of microstructure on radiation-induced processes in Fe-34.7 at% Ni alloy

    International Nuclear Information System (INIS)

    Danilov, S.E.; Arbuzov, V.L.

    2009-01-01

    The method of residual resistivity was used to study processes of the radiation-induced decomposition of the solid solution in the Fe-34.7 at.% Ni alloy at different temperatures and in different initial states under electron irradiation. The comparison was made for alloys in the following states: quenched from 1373 K; aged at 780 K; deformed to 40%; deformed, but annealed at 573 K for elimination of vacancy clusters. Dose and temperature dependences were obtained. Isochronous annealing treatments were performed. It was shown that concentration inhomogeneities of the matrix in the aged alloy did not represent considerable sinks of point defects. Deformation considerably suppressed processes of the radiation-induced decomposition of the solid solution mainly on account of the dislocation structure. The effect of deformation-induced vacancy clusters vanished above 400 K

  15. Search for QCD instanton-induced processes at HERA in the high-Q2 domain

    International Nuclear Information System (INIS)

    Andreev, V.; Baghdasaryan, A.; Begzsuren, K.

    2016-03-01

    Signals of QCD instanton-induced processes are searched for in neutral current deep-inelastic scattering at the electron-proton collider HERA in the kinematic region defined by the Bjorken-scaling variable x>10 -3 , the inelasticity 0.2induced events is observed. Upper limits on the cross section for instanton-induced processes between 1.5 pb and 6 pb, at 95% confidence level, are obtained depending on the kinematic domain in which instantons could be produced. Compared to earlier publications, the limits are improved by an order of magnitude and for the first time are challenging theory predictions.

  16. Can gravitational instantons really constrain axion inflation?

    Energy Technology Data Exchange (ETDEWEB)

    Hebecker, Arthur; Mangat, Patrick [Institut für Theoretische Physik, Universität Heidelberg,Philosophenweg 19, D-69120 Heidelberg (Germany); Theisen, Stefan [Max-Planck-Institut für Gravitationsphysik,Albert-Einstein-Institut, 14476 Golm (Germany); Witkowski, Lukas T. [Institut für Theoretische Physik, Universität Heidelberg,Philosophenweg 19, D-69120 Heidelberg (Germany)

    2017-02-20

    Axions play a central role in inflationary model building and other cosmological applications. This is mainly due to their flat potential, which is protected by a global shift symmetry. However, quantum gravity is known to break global symmetries, the crucial effect in the present context being gravitational instantons or Giddings-Strominger wormholes. We attempt to quantify, as model-independently as possible, how large a scalar potential is induced by this general quantum gravity effect. We pay particular attention to the crucial issue which solutions can or cannot be trusted in the presence of a moduli-stabilisation and a Kaluza-Klein scale. An important conclusion is that, due to specific numerical prefactors, the effect is surprisingly small even in UV-completions with the highest possible scale offered by string theory. As we go along, we discuss in detail Euclidean wormholes, cored and extremal instantons, and how the latter arise from 5d Reissner-Nordström black holes. We attempt to dispel possible doubts that wormholes contribute to the scalar potential by an explicit calculation. We analyse the role of stabilised dilaton-like moduli. Finally, we argue that Euclidean wormholes may be the objects satisfying the Weak Gravity Conjecture extended to instantons.

  17. Prediction of process induced shape distortions and residual stresses in large fibre reinforced composite laminates

    DEFF Research Database (Denmark)

    Nielsen, Michael Wenani

    to their accuracy in predicting process induced strain and stress development in thick section laminates during curing, and more precisely regarding the evolution of the composite thermoset polymer matrix mechanical behaviour during the phase transitions experienced during curing. The different constitutive...

  18. Acute stress-induced cortisol elevations mediate reward system activity during subconscious processing of sexual stimuli

    NARCIS (Netherlands)

    Oei, N.Y.L.; Both, S.; van Heemst, D.; van der Grond, J.

    2014-01-01

    Stress is thought to alter motivational processes by increasing dopamine (DA) secretion in the brain's "reward system", and its key region, the nucleus accumbens (NAcc). However, stress studies using functional magnetic resonance imaging (fMRI), mainly found evidence for stress-induced decreases in

  19. The impact of urea-induced unfolding on the redox process of immobilised cytochrome c

    NARCIS (Netherlands)

    Monari, S.; Millo, D.; Ranieri, A.; di Rocco, G.; van der Zwan, G.; Gooijer, C.; Peressini, S.; Tavagnacco, C.; Hildebrandt, P.; Borsari, M.

    2010-01-01

    We have studied the effect of urea-induced unfolding on the electron transfer process of yeast iso-1-cytochrome c and its mutant K72AK73AK79A adsorbed on electrodes coated by mixed 11-mercapto-1-undecanoic acid/11-mercapto-1-undecanol self-assembled monolayers. Electrochemical measurements,

  20. Analysis of irradiation processes for laser-induced periodic surface structures

    NARCIS (Netherlands)

    Eichstädt, J.; Huis In 't Veld, A.J.

    2013-01-01

    The influence of errors on the irradiation process for laser-induced periodic surface structures (LIPSS) was studied theoretically with energy density simulations. Therefore an irradiation model has been extended by a selection of technical variations. The influence of errors has been found in a