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1

Gravity&MagneticsResearchConsortium CGEMaestro v.1.0  

E-Print Network [OSTI]

Gravity&MagneticsResearchConsortium CGEMaestro v.1.0 A potential fields software package developed at the Center for Gravity, Electrical & Magnetic Studies (CGEM) Department of Geophysics Colorado School of Mines Golden, CO 80401 http://geophysics.mines.edu/cgem Developed for the sponsors of the Gravity

2

Geologic interpretation of gravity and magnetic data in the Salida...  

Open Energy Info (EERE)

interpretation of gravity and magnetic data in the Salida region, Colorado Jump to: navigation, search OpenEI Reference LibraryAdd to library Report: Geologic interpretation of...

3

Rapid gravity and gravity gradiometry terrain correction via adaptive quadtree mesh discretization Kristofer Davis, M. Andy Kass, and Yaoguo Li, Center for Gravity, Electrical and Magnetic Studies, Colorado School  

E-Print Network [OSTI]

Rapid gravity and gravity gradiometry terrain correction via adaptive quadtree mesh discretization Kristofer Davis, M. Andy Kass, and Yaoguo Li, Center for Gravity, Electrical and Magnetic Studies, Colorado School of Mines SUMMARY We present a method for modeling the terrain response in gravity and gravity

5

Crustal structure of Guadeloupe Islands and the Lesser Antilles Arc from a new gravity and magnetic synthesis  

E-Print Network [OSTI]

the compilation and processing of available, on-land, airborne and marine, gravity and magnetic data acquired is associated with formations consistent with the low measured density and the underlying hydrothermal system

Paris-Sud XI, Université de

6

Processing gravity gradiometer data using an equivalent source technique Gravity and Magnetics Research Consortium, Department of Geophysics, Colorado School of Mines, Golden, CO  

E-Print Network [OSTI]

Processing gravity gradiometer data using an equivalent source technique Yaoguo Li Gravity The inherent relationship among the different components of gravity gradiometer data requires filtering operation on the constructed equivalent source. Introduction Gravity gradiometer data measure

7

Gravity and magnetic features and their relationship to the geothermal system in southwestern South Dakota  

SciTech Connect (OSTI)

An attempt is made to determine the sources that are responsible for producing geothermal anomalies observed within the southern Black Hills region. Lithologic and structural boundaries residing in the upper crust and their relationship to the geothermal system are discussed. A regional gravity survey was supplemented by a regional aeromagnetic survey.

Hildenbrand, T.G.; Kucks, R.P.

1981-01-01T23:59:59.000Z

8

Ph.D.Thesis Binary inversion of gravity  

E-Print Network [OSTI]

Ph.D.Thesis Binary inversion of gravity data for salt imaging Richard A. Krahenbuhl Center for Gravity, Electrical & Magnetic Studies Colorado School of Mines Department of Geophysics Colorado School of gravity data for salt imaging Richard A. Krahenbuhl Center for Gravity, Electrical & Magnetic Studies

9

Rapid gravity and gravity gradiometry terrain corrections via an adaptive quadtree mesh discretization  

E-Print Network [OSTI]

Rapid gravity and gravity gradiometry terrain corrections via an adaptive quadtree mesh discretization Kristofer Davis1,2 M. Andy Kass1 Yaoguo Li1 1 Center for Gravity, Electrical, and Magnetic Studies of gravity gradiometry surveys utilising an adaptive quadtree mesh discretization. The data- and terrain

10

Massive Gravity  

E-Print Network [OSTI]

We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali-Gabadadze-Porrati model, cascading gravity and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware-Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally we present alternative and related models of massive gravity such as new massive gravity, Lorentz-violating massive gravity and non-local massive gravity.

Claudia de Rham

2014-03-14T23:59:59.000Z

11

Application of magnetic amplitude inversion in exploration for natural gas in volcanics Yaoguo Li, Center for Gravity, Electrical, and Magnetic Studies, Colorado School of Mines  

E-Print Network [OSTI]

Application of magnetic amplitude inversion in exploration for natural gas in volcanics Yaoguo Li basins and have strong remanent magnetization. The appli- cation arises in exploration of natural gas identify the volcanic units at large depths. INTRODUCTION Exploration for natural gas hosted in volcanics

12

Liouville gravity from Einstein gravity  

E-Print Network [OSTI]

We show that Liouville gravity arises as the limit of pure Einstein gravity in 2+epsilon dimensions as epsilon goes to zero, provided Newton's constant scales with epsilon. Our procedure - spherical reduction, dualization, limit, dualizing back - passes several consistency tests: geometric properties, interactions with matter and the Bekenstein-Hawking entropy are as expected from Einstein gravity.

D. Grumiller; R. Jackiw

2007-12-28T23:59:59.000Z

13

Einstein Gravity from Conformal Gravity  

E-Print Network [OSTI]

We show that that four dimensional conformal gravity plus a simple Neumann boundary condition can be used to get the semiclassical (or tree level) wavefunction of the universe of four dimensional asymptotically de-Sitter or Euclidean anti-de Sitter spacetimes. This simple Neumann boundary condition selects the Einstein solution out of the more numerous solutions of conformal gravity. It thus removes the ghosts of conformal gravity from this computation. In the case of a five dimensional pure gravity theory with a positive cosmological constant we show that the late time superhorizon tree level probability measure, $|\\Psi [ g ]|^2$, for its four dimensional spatial slices is given by the action of Euclidean four dimensional conformal gravity.

Juan Maldacena

2011-06-09T23:59:59.000Z

14

Ground Gravity Survey At San Francisco Volcanic Field Area (Warpinski...  

Open Energy Info (EERE)

geologically mapped the target area, obtained rock samples for age dating and mineral chemistry, performed gravity and magnetic surveys, and integrated these results to identify...

15

Gravity brake  

DOE Patents [OSTI]

A mechanical gravity brake that prevents hoisted loads within a shaft from free-falling when a loss of hoisting force occurs. A loss of hoist lifting force may occur in a number of situations, for example if a hoist cable were to break, the brakes were to fail on a winch, or the hoist mechanism itself were to fail. Under normal hoisting conditions, the gravity brake of the invention is subject to an upward lifting force from the hoist and a downward pulling force from a suspended load. If the lifting force should suddenly cease, the loss of differential forces on the gravity brake in free-fall is translated to extend a set of brakes against the walls of the shaft to stop the free fall descent of the gravity brake and attached load.

Lujan, Richard E. (Santa Fe, NM)

2001-01-01T23:59:59.000Z

16

Is nonrelativistic gravity possible?  

SciTech Connect (OSTI)

We study nonrelativistic gravity using the Hamiltonian formalism. For the dynamics of general relativity (relativistic gravity) the formalism is well known and called the Arnowitt-Deser-Misner (ADM) formalism. We show that if the lapse function is constrained correctly, then nonrelativistic gravity is described by a consistent Hamiltonian system. Surprisingly, nonrelativistic gravity can have solutions identical to relativistic gravity ones. In particular, (anti-)de Sitter black holes of Einstein gravity and IR limit of Horava gravity are locally identical.

Kocharyan, A. A. [School of Mathematical Sciences, Monash University, Clayton 3800 (Australia)

2009-07-15T23:59:59.000Z

17

Stochastic Gravity  

E-Print Network [OSTI]

We give a summary of the status of current research in stochastic semiclassical gravity and suggest directions for further investigations. This theory generalizes the semiclassical Einstein equation to an Einstein-Langevin equation with a stochastic source term arising from the fluctuations of the energy-momentum tensor of quantum fields. We mention recent efforts in applying this theory to the study of black hole fluctuations and backreaction problems, linear response of hot flat space, and structure formation in inflationary cosmology. To explore the physical meaning and implications of this stochastic regime in relation to both classical and quantum gravity, we find it useful to take the view that semiclassical gravity is mesoscopic physics and that general relativity is the hydrodynamic limit of certain spacetime quantum substructures. Three basic issues - stochasticity, collectivity, correlations- and three processes - dissipation, fluctuations, decoherence- underscore the transformation from quantum micro structure and interaction to the emergence of classical macro structure and dynamics. We discuss ways to probe into the high energy activity from below and make two suggestions: via effective field theory and the correlation hierarchy. We discuss how stochastic behavior at low energy in an effective theory and how correlation noise associated with coarse-grained higher correlation functions in an interacting quantum field could carry nontrivial information about the high energy sector. Finally we describe processes deemed important at the Planck scale, including tunneling and pair creation, wave scattering in random geometry, growth of fluctuations and forms, Planck scale resonance states, and spacetime foams.

B. L. Hu

1999-02-22T23:59:59.000Z

18

Quantum Field Theory & Gravity  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Field Theory & Gravity Quantum Field Theory & Gravity Understanding discoveries at the Energy, Intensity, and Cosmic Frontiers Get Expertise Rajan Gupta (505) 667-7664 Email...

19

Specific Gravity Urobilinogen  

E-Print Network [OSTI]

Date Lot # Specific Gravity pH Leukocytes Nitrite Protein Glucose Ketone Urobilinogen Bilirubin®(Bilirubin): Lot # Protein (Sulfosalicylic Acid): Lot # Specific Gravity - Saline 0.85 Specific Gravity - H20 RBC AND DATA ENTRY FORMS #12;Date Lot # Specific Gravity pH Leukocytes Nitrite Protein Glucose Ketone

Rodriguez, Carlos

20

Specific Gravity Urobilinogen  

E-Print Network [OSTI]

Date Lot # Specific Gravity pH Leukocytes Nitrite Protein Glucose Ketone Urobilinogen Bilirubin®(Bilirubin): Lot # Protein (Sulfosalicylic Acid): Lot # Specific Gravity - Saline 0.85 Specific Gravity - H20 # Specific Gravity pH Leukocytes Nitrite Protein Glucose Ketone Urobilinogen Bilirubin Blood / Hemoglobin HCG

Rodriguez, Carlos

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Chiral Gravity, Log Gravity and Extremal CFT  

E-Print Network [OSTI]

We show that the linearization of all exact solutions of classical chiral gravity around the AdS3 vacuum have positive energy. Non-chiral and negative-energy solutions of the linearized equations are infrared divergent at second order, and so are removed from the spectrum. In other words, chirality is confined and the equations of motion have linearization instabilities. We prove that the only stationary, axially symmetric solutions of chiral gravity are BTZ black holes, which have positive energy. It is further shown that classical log gravity-- the theory with logarithmically relaxed boundary conditions --has finite asymptotic symmetry generators but is not chiral and hence may be dual at the quantum level to a logarithmic CFT. Moreover we show that log gravity contains chiral gravity within it as a decoupled charge superselection sector. We normally evaluate the Euclidean sum over geometries of chiral gravity and show that it gives precisely the holomorphic extremal CFT partition function. The modular invariance and integrality of the expansion coefficients of this partition function are consistent with the existence of an exact quantum theory of chiral gravity. We argue that the problem of quantizing chiral gravity is the holographic dual of the problem of constructing an extremal CFT, while quantizing log gravity is dual to the problem of constructing a logarithmic extremal CFT.

Alexander Maloney; Wei Song; Andrew Strominger

2009-03-26T23:59:59.000Z

22

Chiral gravity, log gravity, and extremal CFT  

SciTech Connect (OSTI)

We show that the linearization of all exact solutions of classical chiral gravity around the AdS{sub 3} vacuum have positive energy. Nonchiral and negative-energy solutions of the linearized equations are infrared divergent at second order, and so are removed from the spectrum. In other words, chirality is confined and the equations of motion have linearization instabilities. We prove that the only stationary, axially symmetric solutions of chiral gravity are BTZ black holes, which have positive energy. It is further shown that classical log gravity--the theory with logarithmically relaxed boundary conditions--has finite asymptotic symmetry generators but is not chiral and hence may be dual at the quantum level to a logarithmic conformal field theories (CFT). Moreover we show that log gravity contains chiral gravity within it as a decoupled charge superselection sector. We formally evaluate the Euclidean sum over geometries of chiral gravity and show that it gives precisely the holomorphic extremal CFT partition function. The modular invariance and integrality of the expansion coefficients of this partition function are consistent with the existence of an exact quantum theory of chiral gravity. We argue that the problem of quantizing chiral gravity is the holographic dual of the problem of constructing an extremal CFT, while quantizing log gravity is dual to the problem of constructing a logarithmic extremal CFT.

Maloney, Alexander [Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada); Song Wei [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190 (China); Center for the Fundamental Laws of Nature Jefferson Physical Laboratory, Harvard University, Cambridge, Massachusetts 02138 (United States); Strominger, Andrew [Center for the Fundamental Laws of Nature Jefferson Physical Laboratory, Harvard University, Cambridge, Massachusetts 02138 (United States)

2010-03-15T23:59:59.000Z

23

Towards noncommutative gravity  

E-Print Network [OSTI]

In this short article accessible for non-experts I discuss possible ways of constructing a non-commutative gravity paying special attention to possibilities of realizing the full diffeomorphism symmetry and to relations with 2D gravities.

D. V. Vassilevich

2009-02-17T23:59:59.000Z

24

Motion in Quantum Gravity  

E-Print Network [OSTI]

We tackle the question of motion in Quantum Gravity: what does motion mean at the Planck scale? Although we are still far from a complete answer we consider here a toy model in which the problem can be formulated and resolved precisely. The setting of the toy model is three dimensional Euclidean gravity. Before studying the model in detail, we argue that Loop Quantum Gravity may provide a very useful approach when discussing the question of motion in Quantum Gravity.

Karim Noui

2010-03-31T23:59:59.000Z

25

Stephen Hawking Quantum Gravity  

E-Print Network [OSTI]

Stephen Hawking and Quantum Gravity Matt Visser Physics Department Washington University Saint Louis USA Science Saturdays 4 Nov 2000 #12; Stephen Hawking and Quantum Gravity Abstract: Through research, Stephen Hawking has captured a place in the popular imagina- tion. Quantum gravity in its various

Visser, Matt

26

Quantum Physics Einstein's Gravity  

E-Print Network [OSTI]

Quantum Physics confronts Einstein's Gravity Matt Visser Physics Department Washington University Saint Louis USA Science Saturdays 13 October 2001 #12; Quantum Physics confronts Einstein's Gravity and with Einstein's theory of gravity (the general relativity) is still the single biggest theoretical problem

Visser, Matt

27

An astronomical search for evidence of new physics: Limits on gravity-induced birefringence from the magnetic white dwarf RE J0317-853  

E-Print Network [OSTI]

The coupling of the electromagnetic field directly with gravitational gauge fields leads to new physical effects that can be tested using astronomical data. Here we consider a particular case for closer scrutiny, a specific nonminimal coupling of torsion to electromagnetism, which enters into a metric-affine geometry of space-time. We show that under the assumption of this nonminimal coupling, spacetime is birefringent in the presence of such a gravitational field. This leads to the depolarization of light emitted from extended astrophysical sources. We use polarimetric data of the magnetic white dwarf ${RE J0317-853}$ to set strong constraints on the essential coupling constant for this effect, giving $k^2 \\lsim (19 {m})^2 $.

Oliver Preuss; Mark P. Haugan; Sami K. Solanki; Stefan Jordan

2004-05-26T23:59:59.000Z

28

Quantization of Emergent Gravity  

E-Print Network [OSTI]

Emergent gravity is based on a novel form of the equivalence principle known as the Darboux theorem or the Moser lemma in symplectic geometry stating that the electromagnetic force can always be eliminated by a local coordinate transformation as far as spacetime admits a symplectic structure, in other words, a microscopic spacetime becomes noncommutative (NC). If gravity emerges from U(1) gauge theory on NC spacetime, this picture of emergent gravity suggests a completely new quantization scheme where quantum gravity is defined by quantizing spacetime itself, leading to a dynamical NC spacetime. Therefore the quantization of emergent gravity is radically different from the conventional approach trying to quantize a phase space of metric fields. This approach for quantum gravity allows a background independent formulation where spacetime as well as matter fields is equally emergent from a universal vacuum of quantum gravity.

Hyun Seok Yang

2014-12-24T23:59:59.000Z

29

Einstein Gravity, Massive Gravity, Multi-Gravity and Nonlinear Realizations  

E-Print Network [OSTI]

The existence of a ghost free theory of massive gravity begs for an interpretation as a Higgs phase of General Relativity. We revisit the study of massive gravity as a Higgs phase. Absent a compelling microphysical model of spontaneous symmetry breaking in gravity, we approach this problem from the viewpoint of nonlinear realizations. We employ the coset construction to search for the most restrictive symmetry breaking pattern whose low energy theory will both admit the de Rham--Gabadadze--Tolley (dRGT) potentials and nonlinearly realize every symmetry of General Relativity, thereby providing a new perspective from which to build theories of massive gravity. In addition to the known ghost-free terms, we find a novel parity violating interaction which preserves the constraint structure of the theory, but which vanishes on the normal branch of the theory. Finally, the procedure is extended to the cases of bi-gravity and multi-vielbein theories. Analogous parity violating interactions exist here, too, and may be non-trivial for certain classes of multi-metric theories.

Garrett Goon; Kurt Hinterbichler; Austin Joyce; Mark Trodden

2014-12-18T23:59:59.000Z

30

Dark gravity and cosmology  

E-Print Network [OSTI]

The previous version of this article was a first attempt to confront the Dark Gravity theory to cosmological data. However, more recent developments lead to the conclusion that the cosmological principle is probably not valid in Dark Gravity so that this kind of analysis is at best very premature. A more recent and living review of the Dark Gravity theory can be found in gr-qc/0610079

F. Henry-Couannier; A. Tilquin; C. Tao; A. Ealet

2007-10-24T23:59:59.000Z

31

Extended gravity from noncommutativity  

E-Print Network [OSTI]

We review the first order theory of gravity (vierbein formulation) on noncommutative spacetime studied in [1, 2]. The first order formalism allows to couple the theory to fermions. This NC action is then reinterpreted (using the Seiberg-Witten map) as a gravity theory on commutative spacetime that contains terms with higher derivatives and higher powers of the curvature and depend on the noncommutativity parameter \\theta. When the noncommutativity is switched off we recover the usual gravity action coupled to fermions. The first nontrival corrections to the usual gravity action coupled to fermions are presented in a manifest Lorentz invariant form.

Paolo Aschieri

2012-07-20T23:59:59.000Z

32

Is Gravity an Interaction?  

E-Print Network [OSTI]

We consider a possibility that gravity is not an interaction but a manifestation of a symmetry based on a Galois field.

Felix M. Lev

2010-05-16T23:59:59.000Z

33

Gravity Train Project  

E-Print Network [OSTI]

Dec 7, 2013 ... Gravity Train Project. Same page in Romanian, Polish, and in French. Let us drill a straight tunnel from West Lafayette, IN to Paris, France:.

34

4D gravity monitoring of fluid movement at Delhi Field, LA: A feasibility study with seismic and well data  

E-Print Network [OSTI]

4D gravity monitoring of fluid movement at Delhi Field, LA: A feasibility study with seismic and well data Richard A. Krahenbuhl *, Yaoguo Li , & Tom Davis Center for Gravity, Electrical & Magnetic in a reservoir at various injection times using 4D micro-gravity method. Simulations are performed using

35

Particle Dynamics And Emergent Gravity  

E-Print Network [OSTI]

The emergent gravity proposal is examined within the framework of noncommutative QED/gravity correspondence from particle dynamics point of view.

Amir H. Fatollahi

2008-05-08T23:59:59.000Z

36

Counterterms in Lovelock Gravity  

E-Print Network [OSTI]

In this paper, we introduce the counterterms that remove the non-logarithmic divergences of the action in third order Lovelock gravity. We do this by defining the cosmological constant in such a way that the asymptotic form of the metric have the same form in Lovelock and Einstein gravities. Thus, we employ the counterterms of Einstein gravity and show that the power law divergences in the action of Lovelock gravity can be removed by suitable choice of coefficients. We find that the dependence of these coefficients on the dimension in Lovelock gravity is the same as in Einstein gravity. We also introduce the finite energy-momentum tensor and employ these counterterms to calculate the finite action and mass of the black hole solutions of third order Lovelock gravity. We calculate the thermodynamic quantities and show that the entropy calculated through the use of Gibbs-Duhem relation is consistent with the obtained entropy by Wald's formula. We, also, find that in contrast to Einstein gravity in which there ex...

Mehdizadeh, M R; Zangeneh, M Kord

2015-01-01T23:59:59.000Z

37

Ground Magnetics At San Francisco Volcanic Field Area (Warpinski...  

Open Energy Info (EERE)

geologically mapped the target area, obtained rock samples for age dating and mineral chemistry, performed gravity and magnetic surveys, and integrated these results to identify...

38

Selection Rules for the Nonlinear Interactions of Internal Gravity Waves and Inertia-Gravity Waves  

E-Print Network [OSTI]

Internal Gravity Waves . . . . . . . . . . . . . . 3.2.1 Twodimensional inertia-gravity wave physics . . . . . . . . .Three dimensional inertia-gravity wave physics . . . . . .

Jiang, Chung-Hsiang

2010-01-01T23:59:59.000Z

39

Gravitational lensing in metric theories of gravity  

E-Print Network [OSTI]

Gravitational lensing in metric theories of gravity is discussed. I introduce a generalized approximate metric element, inclusive of both post-post-Newtonian (ppN) contributions and gravito-magnetic field. Following Fermat's principle and standard hyphoteses, I derive the time delay function and deflection angle caused by an isolated mass distribution. Several astrophysical systems are considered. In most of the cases, the gravito-magnetic correction offers the best perspectives for an observational detection. Actual measurements distinguish only marginally different metric theories one from another.

M. Sereno

2003-01-15T23:59:59.000Z

40

Probability around the Quantum Gravity. Part 1: Planar Pure Gravity  

E-Print Network [OSTI]

Probability around the Quantum Gravity. Part 1: Planar Pure Gravity V.A.Malyshev \\Lambda September 17, 1998 Abstract In this paper we study stochastic dynamics which leaves quantum gravity equilibrium science and biology. At the same time the paper can serve an intro­ duction to quantum gravity

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Toroidal solutions in Horava Gravity  

E-Print Network [OSTI]

Recently a new four-dimensional non relativistic renormalizable theory of gravity was proposed by Horava. This gravity reduces to Einstein gravity at large distances. In this paper by using the new action for gravity we present different toroidal solutions to the equations of motion. Our solutions describe the near horizon geometry with slow rotating parameter.

Ahmad Ghodsi

2011-02-24T23:59:59.000Z

42

Gravity in Gauge Mediation  

E-Print Network [OSTI]

We investigate O'Raifeartaigh-type models for F-term supersymmetry breaking in gauge mediation scenarios in the presence of gravity. It is pointed out that the vacuum structure of those models is such that in metastable vacua gravity mediation contribution to scalar masses is always suppressed to the level below 1 percent, almost sufficient for avoiding FCNC problem. Close to that limit, gravitino mass can be in the range 10-100 GeV, opening several interesting possibilities for gauge mediation models, including Giudice-Masiero mechanism for mu and Bmu generation. Gravity sector can include stabilized moduli.

Zygmunt Lalak; Stefan Pokorski; Krzysztof Turzynski

2008-08-18T23:59:59.000Z

43

Center for Gravity, Electrical & Magnetic Studies  

E-Print Network [OSTI]

utility codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Examples 23 Salt body the code and speeding up the algorithms. We list here three of the main updates of interest to users

44

Causal Newton Gravity Law  

E-Print Network [OSTI]

The equations of the relativistic causal Newton gravity law for the planets of the solar system are studied in the approximation when the Sun rests at the coordinates origin and the planets do not iteract between each other.

Yury M. Zinoviev

2012-01-17T23:59:59.000Z

45

Why gravity is fundamental  

E-Print Network [OSTI]

It is argued that the existence of a minimum size of spacetime may imply the fundamental existence of gravity as a geometric property of spacetime described by general relativity.

Shan Gao

2011-07-16T23:59:59.000Z

46

On the no-gravity limit of gravity  

E-Print Network [OSTI]

We argue that Relative Locality may arise in the no gravity $G\\rightarrow0$ limit of gravity. In this limit gravity becomes a topological field theory of the BF type that, after coupling to particles, may effectively deform its dynamics. We briefly discuss another no gravity limit with a self dual ground state as well as the topological ultra strong $G\\rightarrow\\infty$ one.

J. Kowalski-Glikman; M. Szczachor

2012-12-21T23:59:59.000Z

47

Macroscopic quantization of gravity  

E-Print Network [OSTI]

The moon is receding from earth at an average rate of 3.8 cm/yr [6][7][9][12].This anomaly cannot be attributed to the well-known tidal exchange of angular momentum between earth and moon [8]. A secular change in the astronomical unit AU is definitely a concern, it is reportedly increasing by about 15 cm/yr [9][10], in this letter; the concept of macroscopic quantization of gravity is introduced to account for these anomalies on theoretical basis. Interestingly, it was found useful in measuring the speed of gravity! What is more interesting is the fact that this concept is based on solid well known classical physics with no modifications to any standard model. It was found that the speed of gravity cg is in the range 10^4 c < cg < 10^5 c.

M. Y. Amin

2010-01-09T23:59:59.000Z

48

Resummation of Massive Gravity  

SciTech Connect (OSTI)

We construct four-dimensional covariant nonlinear theories of massive gravity which are ghost-free in the decoupling limit to all orders. These theories resume explicitly all the nonlinear terms of an effective field theory of massive gravity. We show that away from the decoupling limit the Hamiltonian constraint is maintained at least up to and including quartic order in nonlinearities, hence excluding the possibility of the Boulware-Deser ghost up to this order. We also show that the same remains true to all orders in a similar toy model.

Rham, Claudia de [Department de Physique Theorique, Universite de Geneve, 24 Quai E. Ansermet, CH-1211 Geneve (Switzerland); Gabadadze, Gregory [Center for Cosmology and Particle Physics, Department of Physics, New York University, New York 10003 (United States); Tolley, Andrew J. [Department of Physics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106 (United States)

2011-06-10T23:59:59.000Z

49

Introduction to Loop Quantum Gravity  

E-Print Network [OSTI]

The questions I have been asked during the 5th International School on Field Theory and Gravitation, have compelled me to give an account of the premises that I consider important for a beginner's approach to Loop Quantum Gravity. After a description of some general arguments and an introduction to the canonical theory of gravity, I review the background independent approach to quantum gravity, giving only a brief survey of Loop Quantum Gravity.

Simone Mercuri

2010-01-08T23:59:59.000Z

50

5, 1102911054, 2005 Convective gravity  

E-Print Network [OSTI]

ACPD 5, 11029­11054, 2005 Convective gravity waves at mid-latitudes Y. G. Choi et al. Title Page Discussions Wind-profiler observations of gravity waves produced by convection at mid-latitudes Y. G. Choi1­11054, 2005 Convective gravity waves at mid-latitudes Y. G. Choi et al. Title Page Abstract Introduction

Paris-Sud XI, Université de

51

November 1984 Simplicial Quantum Gravity*  

E-Print Network [OSTI]

November 1984 Simplicial Quantum Gravity* Herbert W. Hamber Institute for Advanced Study Princeton, NJ 08540, USA ABSTRACT Quantum gravity on a lattice in a formulation due to Regge is reviewed in view of possible applications to renormalizable asymptoti­ cally free higher derivative theories of gravity. * Les

Hamber, Herbert W.

52

6, 19532001, 2006 Imaging gravity  

E-Print Network [OSTI]

ACPD 6, 1953­2001, 2006 Imaging gravity waves in lower stratospheric AMSU-A radiances S. D under a Creative Commons License. Atmospheric Chemistry and Physics Discussions Imaging gravity waves.eckermann@nrl.navy.mil) 1953 #12;ACPD 6, 1953­2001, 2006 Imaging gravity waves in lower stratospheric AMSU-A radiances S. D

Boyer, Edmond

53

CFT, Integrable Models Liouville Gravity  

E-Print Network [OSTI]

CFT, Integrable Models And Liouville Gravity Chernogolovka 2009 Sunday June 28, 2009. Conference as one of components of their L, A pairs. #12;CFT, Integrable Models And Liouville Gravity Chernogolovka Gravity Chernogolovka, 2009 Tuesday June 30, 2009. CONFERENCE HALL 09:30­10:10 Herman Boos (Wuppertal

Fominov, Yakov

54

Loop quantum gravity and observations  

E-Print Network [OSTI]

Quantum gravity has long been thought to be completely decoupled from experiments or observations. Although it is true that smoking guns are still missing, there are now serious hopes that quantum gravity phenomena might be tested. We review here some possible ways to observe loop quantum gravity effects either in the framework of cosmology or in astroparticle physics.

A. Barrau; J. Grain

2014-10-07T23:59:59.000Z

55

Even-dimensional topological gravity from Chern-Simons gravity  

E-Print Network [OSTI]

It is shown that the topological action for gravity in 2n-dimensions can be obtained from the 2n+1-dimensional Chern-Simons gravity genuinely invariant under the Poincare group. The 2n-dimensional topological gravity is described by the dynamics of the boundary of a 2n+1-dimensional Chern-Simons gravity theory with suitable boundary conditions. The field $\\phi^{a}$, which is necessary to construct this type of topological gravity in even dimensions, is identified with the coset field associated with the non-linear realizations of the Poincare group ISO(d-1,1).

Nelson Merino; Alfredo Perez; Patricio Salgado

2009-10-08T23:59:59.000Z

56

From Classical To Quantum Gravity: Introduction to Loop Quantum Gravity  

E-Print Network [OSTI]

We present an introduction to the canonical quantization of gravity performed in loop quantum gravity, based on lectures held at the 3rd quantum geometry and quantum gravity school in Zakopane in 2011. A special feature of this introduction is the inclusion of new proposals for coupling matter to gravity that can be used to deparametrize the theory, thus making its dynamics more tractable. The classical and quantum aspects of these new proposals are explained alongside the standard quantization of vacuum general relativity in loop quantum gravity.

Kristina Giesel; Hanno Sahlmann

2013-01-02T23:59:59.000Z

57

Isometrodynamics and Gravity  

E-Print Network [OSTI]

Isometrodynamics (ID), the gauge theory of the group of volume-preserving diffeomorphisms of an "inner" D-dimensional flat space, is tentatively interpreted as a fundamental theory of gravity. Dimensional analysis shows that the Planck length l_P - and through it \\hbar and \\Gamma - enters the gauge field action linking ID and gravity in a natural way. Noting that the ID gauge field couples solely through derivatives acting on "inner" space variables all ID fields are Taylor-expanded in "inner" space. Integrating out the "inner" space variables yields an effective field theory for the coefficient fields with l_P^2 emerging as the expansion parameter. For \\hbar goint to zero only the leading order field does not vanish. This classical field couples to the matter Noether currents and charges related to the translation invariance in "inner" space. A model coupling this leading order field to a matter point source is established and solved. Interpreting the matter Noether charge in terms of gravitational mass Newton's inverse square law is finally derived for a static gauge field source and a slowly moving test particle. Gravity emerges as potentially related to field variations over "inner" space and might microscopically be described by the ID gauge field or equivalently by an infinite string of coefficient fields only the leading term of which is related to the macroscopical effects of gravity.

Christian Wiesendanger

2009-07-25T23:59:59.000Z

58

Quantum Gravity and Turbulence  

E-Print Network [OSTI]

We apply recent advances in quantum gravity to the problem of turbulence. Adopting the AdS/CFT approach we propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov scalings in 2+1 dimensions. In the gravitational context, turbulence is intimately related to the properties of spacetime, or quantum, foam.

Vishnu Jejjala; Djordje Minic; Y. Jack Ng; Chia-Hsiung Tze

2010-05-18T23:59:59.000Z

59

Phenomenological Quantum Gravity  

E-Print Network [OSTI]

Planck scale physics represents a future challenge, located between particle physics and general relativity. The Planck scale marks a threshold beyond which the old description of spacetime breaks down and conceptually new phenomena must appear. In the last years, increased efforts have been made to examine the phenomenology of quantum gravity, even if the full theory is still unknown.

S. Hossenfelder

2006-11-01T23:59:59.000Z

60

Modified Theories of Gravity  

E-Print Network [OSTI]

The recent observational data in cosmology seem to indicate that the universe is currently expanding in an accelerated way. An intriguing interpretation of these data is that they may just be signalling that Einstein's General Relativity is not the correct description of gravity when we consider distances of the order of the present horizon of the universe. In this thesis we consider two models which modify General Relativity at very large distances, the Cascading DGP and the dRGT massive gravity, and investigate their phenomenological viability. We start with a general introduction to standard cosmology and we introduce the late time acceleration problem and the cosmological constant problem. We then provide a pedagogical introduction to the DGP model, of which the Cascading DGP is an extension, and to the dRGT massive gravity. Concerning the Cascading DGP, we show that the thin limit of the 4D brane inside the (already thin) 5D brane is well defined, at least for the class of configurations that we consider, and confirm that gravity is regularized in these set-ups. We give a geometrical interpretation of the presence of the critical tension, and comment on the difference between the results in the literature and our results, which we support with a numerical calculation. Regarding the dRGT massive gravity, we focus on the branch of solutions in which the Vainshtein mechanism can occur. We determine analytically the number and properties of local solutions which exist asymptotically on large scales (but still below the gravitational Compton wavelength), and of local (inner) solutions which exist on small scales. We characterize exactly the properties of global solutions in every point of the phase space, and characterize precisely in which regions the Vainshtein mechanism takes place. We also provide numerical solutions which confirm our analysis.

Fulvio Sbisa'

2014-07-09T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Ground Magnetics At Neal Hot Springs Geothermal Area (U.S. Geothermal...  

Open Energy Info (EERE)

Date 2007 - 2007 Usefulness not indicated DOE-funding Unknown Exploration Basis Gravity and Magnetic surveys were done as part of U.S. Geothermal's geophysical program for...

62

Gravity, Dimension, Equilibrium, & Thermodynamics  

E-Print Network [OSTI]

Is it actually possible to interpret gravitation as space's property in a pure classical way. Then, we note that extended self-gravitating system equilibrium depends directly on the number of dimension of the space in which it evolves. Given those precisions, we review the principal thermodynamical knowledge in the context of classical gravity with arbitrary dimension of space. Stability analyses for bounded 3D systems, namely the Antonov instability paradigm, are then rapproched to some amazing properties of globular clusters and galaxies.

Jerome Perez

2006-03-30T23:59:59.000Z

63

Massive Gravity from Higher Derivative Gravity with Boundary Conditions  

E-Print Network [OSTI]

With an appropriate choice of parameters, a higher derivative theory of gravity can describe a normal massive sector and a ghost massless sector. We show that, when defined on an asymptotically de Sitter spacetime with Dirichlet boundary conditions, such a higher derivative gravity can provide a framework for a unitary theory of massive gravity in four spacetime dimensions. The resulting theory is free not only of higher derivative ghosts but also of the Boulware-Deser mode.

Minjoon Park; Lorenzo Sorbo

2012-10-29T23:59:59.000Z

64

Modified Theories of Gravity  

E-Print Network [OSTI]

The recent observational data in cosmology seem to indicate that the universe is currently expanding in an accelerated way. An intriguing interpretation of these data is that they may just be signalling that Einstein's General Relativity is not the correct description of gravity when we consider distances of the order of the present horizon of the universe. In this thesis we consider two models which modify General Relativity at very large distances, the Cascading DGP and the dRGT massive gravity, and investigate their phenomenological viability. We start with a general introduction to standard cosmology and we introduce the late time acceleration problem and the cosmological constant problem. We then provide a pedagogical introduction to the DGP model, of which the Cascading DGP is an extension, and to the dRGT massive gravity. Concerning the Cascading DGP, we show that the thin limit of the 4D brane inside the (already thin) 5D brane is well defined, at least for the class of configurations that we consider...

Sbis, Fulvio

2014-01-01T23:59:59.000Z

65

Entropic Gravity in Rindler Space  

E-Print Network [OSTI]

We show that Rindler horizons are entropic screens and gravity is an entropic force in Rindler space by deriving the Verlinde entropy formula from the focusing of light due to a mass close to the horizon. Consequently, gravity is also entropic in the near horizon regions of Schwarzschild and de Sitter space-times. In different limits, the entropic nature of gravity in Rindler space leads to the Bekenstein entropy bound and the uncertainty principle.

Edi Halyo

2011-04-13T23:59:59.000Z

66

Dual gravity and E11  

E-Print Network [OSTI]

We consider the equation of motion in the gravity sector that arises from the non-linear realisation of the semi-direct product of E11 and its first fundamental representation, denoted by l1, in four dimensions. This equation is first order in derivatives and at low levels relates the usual field of gravity to a dual gravity field. When the generalised space-time is restricted to be the usual four dimensional space-time we show that this equation does correctly describe Einstein's theory at the linearised level. We also comment on previous discussions of dual gravity.

Peter West

2014-11-04T23:59:59.000Z

67

Born-Infeld Gravity Revisited  

E-Print Network [OSTI]

In this paper we investigate the behavior of linearized gravitational excitation in the Born-Infeld Gravity in $AdS_3$ space. We obtain the linearized equation of motion and show that this higher order gravity propagate two gravitons, massless and massive, on the $AdS_3$ background. In contrast to the $R^2$ models, such as TMG or NMG, Born-Infeld Gravity does not have a critical point for any regular choice of parameters. So the logarithmic solution is not a solution of this model, due to this one can not find a logarithmic conformal field theory as a dual model for Born-Infeld Gravity.

M. R. Setare; M. Sahraee

2014-04-22T23:59:59.000Z

68

Is Gravity an Entropic Force?  

E-Print Network [OSTI]

The remarkable connections between gravity and thermodynamics seem to imply that gravity is not fundamental but emergent, and in particular, as Verlinde suggested, gravity is probably an entropic force. In this paper, we will argue that the idea of gravity as an entropic force is debatable. It is shown that there is no convincing analogy between gravity and entropic force in Verlinde's example. Neither holographic screen nor test particle satisfies all requirements for the existence of entropic force in a thermodynamics system. Furthermore, we show that the entropy increase of the screen is not caused by its statistical tendency to increase entropy as required by the existence of entropic force, but in fact caused by gravity. Therefore, Verlinde's argument for the entropic origin of gravity is problematic. In addition, we argue that the existence of a minimum size of spacetime, together with the Heisenberg uncertainty principle in quantum theory, may imply the fundamental existence of gravity as a geometric property of spacetime. This may provide a further support for the conclusion that gravity is not an entropic force.

Shan Gao

2011-07-16T23:59:59.000Z

69

An Underlying Theory for Gravity  

E-Print Network [OSTI]

A new direction to understand gravity has recently been explored by considering classical gravity to be a derived interaction from an underlying theory. This underlying theory would involve new degrees of freedom at a deeper level and it would be structurally different from classical gravitation. It may conceivably be a quantum theory or a non-quantum theory. The relation between this underlying theory and Einstein's gravity is similar to the connection between statistical mechanics and thermodynamics. We discuss the apparent lack of evidence of any quantum nature of gravity in this context.

Yuan K. Ha

2012-08-14T23:59:59.000Z

70

The structure of local gravity theories  

E-Print Network [OSTI]

We discuss the structure of local gravity theories as resulting from the idea that locally gravity must be physically characterized by tidal acceleration, and show how this relates to both Newtonian gravity and Einstein's general relativity.

Maurice J. Dupre

2014-03-12T23:59:59.000Z

71

The role of information in gravity  

E-Print Network [OSTI]

It is argued that particle-specific information on energy-momentum adjusts the strength of gravity. This form of gravity has no free parameters, preserves Einstein gravity locally and predicts 6 times stronger accelerations on galaxy scales.

M. Spaans

2009-07-24T23:59:59.000Z

72

Gravity wraps Higgs boson  

E-Print Network [OSTI]

It is shown that, under a conformal transformation with reference to the Higgs field, the Higgs boson can be completely decoupled from electroweak interactions with no apparent change in known properties of leptons, quarks and vector bosons. Higgs boson becomes part of a scalar-tensor gravity which can be relevant for Dark Energy. It interacts with matter sector via higher-dimensional terms (e.g. neutrino Majorana mass), and via the fields (of new physics) whose masses are not generated by the Higgs mechanism. Dark Matter and two-Higgs-doublet model are the simplest examples.

Durmus A. Demir

2011-12-11T23:59:59.000Z

73

Echoes of Gravity  

E-Print Network [OSTI]

The study of anisotropies in the Cosmic Microwave Background radiation is progressing at a phenomenal rate, both experimentally and theoretically. These anisotropies can teach us an enormous amount about the way that fluctuations were generated and the way they subsequently evolved into the clustered galaxies which are observed today. In particular, on sub-degree scales the rich structure in the anisotropy spectrum is the consequence of gravity-driven acoustic oscillations occurring before the matter in the universe became neutral. The frozen-in phases of these sound waves imprint a dependence on many cosmological parameters, that we may be on the verge of extracting.

Douglas Scott; Martin White

1995-05-22T23:59:59.000Z

74

Modes of log gravity  

SciTech Connect (OSTI)

The physical modes of a recently proposed D-dimensional 'critical gravity', linearized about its anti-de Sitter vacuum, are investigated. All 'log mode' solutions, which we categorize as 'spin-2' or 'Proca', arise as limits of the massive spin-2 modes of the noncritical theory. The linearized Einstein tensor of a spin-2 log mode is itself a 'nongauge' solution of the linearized Einstein equations whereas the linearized Einstein tensor of a Proca mode takes the form of a linearized general coordinate transformation. Our results suggest the existence of a holographically dual logarithmic conformal field theory.

Bergshoeff, Eric A.; Rosseel, Jan [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Hohm, Olaf [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Townsend, Paul K. [Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

2011-05-15T23:59:59.000Z

75

On Modified Gravity  

E-Print Network [OSTI]

We consider some aspects of nonlocal modified gravity, where nonlocality is of the type $R \\mathcal{F}(\\Box) R$. In particular, using ansatz of the form $\\Box R = c R^\\gamma,$ we find a few $R(t)$ solutions for the spatially flat FLRW metric. There are singular and nonsingular bounce solutions. For late cosmic time, scalar curvature R(t) is in low regime and scale factor a(t) is decelerated. R (t) = 0 satisfies all equations when k = -1.

Ivan Dimitrijevic; Branko Dragovich; Jelena Grujic; Zoran Rakic

2012-04-09T23:59:59.000Z

76

Fluid Gravity Engineering Rocket motor flow analysis  

E-Print Network [OSTI]

Fluid Gravity Engineering Capability · Rocket motor flow analysis -Internal (performance) -External young scientists/engineers Fluid Gravity Engineering Ltd #12;

Anand, Mahesh

77

Canonical Analysis of Unimodular Gravity  

E-Print Network [OSTI]

This short note is devoted to the Hamiltonian analysis of the Unimodular Gravity.We treat the unimodular gravity as General Relativity action with the unimodular constraint imposed with the help of Lagrange multiplier. We perform the canonical analysis of the resulting theory and determine its constraint structure.

J. Kluson

2014-10-07T23:59:59.000Z

78

Reduced models for quantum gravity  

E-Print Network [OSTI]

The preceding talks given at this conference have dealt mainly with general ideas for, main problems of and techniques for the task of quantizing gravity canonically. Since one of the major motivations to arrange for this meeting was that it should serve as a beginner's introduction to canonical quantum gravity, we regard it as important to demonstrate the usefulness of the formalism by means of applying it to simplified models of quantum gravity, here formulated in terms of Ashtekar's new variables. From the various, completely solvable, models that have been discussed in the literature we choose those that we consider as most suitable for our pedagogical reasons, namely 2+1 gravity and the spherically symmetric model. The former model arises from a dimensional, the latter from a Killing reduction of full 3+1 gravity. While 2+1 gravity is usually treated in terms of closed topologies without boundary of the initial data hypersurface, the toplogy for the spherically symmetric system is chosen to be asymptotically flat. Finally, 2+1 gravity is more suitably quantized using the loop representation while spherically symmetric gravity is easier to quantize via the self-dual representation. Accordingly, both types of reductions, both types of topologies and both types of representations that are mainly employed in the literature in the context of the new variables come into practice. What makes the discussion especially clear is the fact that for both models the reduced phase space turns out to be finitely dimensional.

T. Thiemann

1999-10-04T23:59:59.000Z

79

Lovelock gravity from entropic force  

E-Print Network [OSTI]

In this paper, we first generalize the formulation of entropic gravity to (n+1)-dimensional spacetime. Then, we propose an entropic origin for Gauss-Bonnet gravity and more general Lovelock gravity in arbitrary dimensions. As a result, we are able to derive Newton's law of gravitation as well as the corresponding Friedmann equations in these gravity theories. This procedure naturally leads to a derivation of the higher dimensional gravitational coupling constant of Friedmann/Einstein equation which is in complete agreement with the results obtained by comparing the weak field limit of Einstein equation with Poisson equation in higher dimensions. Our study shows that the approach presented here is powerful enough to derive the gravitational field equations in any gravity theory. PACS: 04.20.Cv, 04.50.-h, 04.70.Dy.

A. Sheykhi; H. Moradpour; N. Riazi

2012-10-03T23:59:59.000Z

80

Gravity Waves in the Sun  

E-Print Network [OSTI]

We present numerical simulations of penetrative convection and gravity wave excitation in the Sun. Gravity waves are self-consistently generated by a convective zone overlying a radiative interior. We produce power spectra for gravity waves in the radiative region as well as estimates for the energy flux of gravity waves below the convection zone. We calculate a peak energy flux in waves below the convection zone to be three orders of magnitude smaller than previous estimates for m=1. The simulations show that the linear dispersion relation is a good approximation only deep below the convective-radiative boundary. Both low frequency propagating gravity waves as well as higher frequency standing modes are generated; although we find that convection does not continually drive the standing g-mode frequencies.

Tamara M. Rogers; Gary A. Glatzmaier

2005-08-25T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Quantum Gravity and Inflation  

E-Print Network [OSTI]

We review some perturbative results obtained in quantum gravity in an accelerating cosmological background. We then describe a class of non-local, purely gravitational models which have the correct structure to reproduce the leading infrared logarithms of quantum gravitational back-reaction during the inflationary regime. These models end inflation in a distinctive phase of oscillations with slight and short violations of the weak energy condition and should, when coupled to matter, lead to rapid reheating. By elaborating this class of models we exhibit one that has the same behaviour during inflation, goes quiescent until the onset of matter domination, and induces a small, positive cosmological constant of about the right size thereafter. We also briefly comment on the primordial density perturbations that this class of models predict.

M. G. Romania; N. C. Tsamis; R. P. Woodard

2014-12-05T23:59:59.000Z

82

Duality in linearized gravity  

SciTech Connect (OSTI)

We show that duality transformations of linearized gravity in four dimensions, i.e., rotations of the linearized Riemann tensor and its dual into each other, can be extended to the dynamical fields of the theory so as to be symmetries of the action and not just symmetries of the equations of motion. Our approach relies on the introduction of two superpotentials, one for the spatial components of the spin-2 field and the other for their canonically conjugate momenta. These superpotentials are two-index, symmetric tensors. They can be taken to be the basic dynamical fields and appear locally in the action. They are simply rotated into each other under duality. In terms of the superpotentials, the canonical generator of duality rotations is found to have a Chern-Simons-like structure, as in the Maxwell case.

Henneaux, Marc; Teitelboim, Claudio [Physique Theorique et Mathematique and International Solvay Institutes, Universite Libre de Bruxelles, Campus Plaine C. P. 231, B-1050 Brussels (Belgium) and Centro de Estudios Cientificos (CECS), Valdivia (Chile); Centro de Estudios Cientificos (CECS), Valdivia (Chile)

2005-01-15T23:59:59.000Z

83

Entropy and quantum gravity  

E-Print Network [OSTI]

We give an account of the matter-gravity entanglement hypothesis which, unlike the standard approach to entropy based on coarse-graining, offers a definition for the entropy of a closed system as a real and objective quantity. We explain how this new approach offers an explanation for the Second Law of Thermodynamics in general and a non-paradoxical understanding of information loss during black hole formation and evaporation in particular. We also very briefly review some recent related work on the nature of equilibrium states involving quantum black holes and point out how it promises to resolve some puzzling issues in the current version of the string theory approach to black hole entropy.

Kay, Bernard S

2015-01-01T23:59:59.000Z

84

Intrusive gravity currents in two-layer  

E-Print Network [OSTI]

Intrusive gravity currents in two-layer stratified media Morris R. Flynn & Paul F. Linden Dept to as a gravity current · In contrast to waves, gravity currents transport significant mass (e.g. fluid parcels, sediment, insects, etc.) Introduction Gravity currents in the environment www

Flynn, Morris R.

85

Riding Gravity Away from Doomsday  

E-Print Network [OSTI]

The discovery that most of the energy density in the universe is stored in the form of dark energy has profound consequences for our future. In particular our current limited understanding of quantum theory of gravity indicates that some time in the future our universe will undergo a phase transition that will destroy us and everything else around us instantaneously. However the laws of gravity also suggest a way out -- some of our descendants could survive this catastrophe by riding gravity away from the danger. In this essay I describe the tale of this escape from doomsday.

Sen, Ashoke

2015-01-01T23:59:59.000Z

86

Inversion of marine gravity data  

E-Print Network [OSTI]

on the earth's gravity field and mapped the shape of the ocean surface to high accuracy (&I meter) with a horizontal resolution which averages less than 15km. Systems such as a tethered satellite attached to the Space Shuttle have been proposed to measure... for longer wavelength. The study of short wavelength isostasy requires detailed gravity and bathymetry at wavelengths of 10-50km. As the objective of this study is to infer the shape of sea floor at short wavelengths, arrays of short wavelength of gravity...

Shih, Chung-Chi

1982-01-01T23:59:59.000Z

87

PPN-limit of Fourth Order Gravity inspired by Scalar-Tensor Gravity  

E-Print Network [OSTI]

Based on the {\\it dynamical} equivalence between higher order gravity and scalar-tensor gravity the PPN-limit of fourth order gravity is discussed. We exploit this analogy developing a fourth order gravity version of the Eddington PPN-parameters. As a result, Solar System experiments can be reconciled with higher order gravity, if physical constraints descending from experiments are fulfilled.

S. Capozziello; A. Troisi

2005-08-01T23:59:59.000Z

88

Gravity's Cosmic ShadowsGravity's Cosmic Shadows A Mathematical UnveilingA Mathematical Unveiling  

E-Print Network [OSTI]

Gravity's Cosmic ShadowsGravity's Cosmic Shadows A Mathematical UnveilingA Mathematical Unveiling of gravity on light SUNSUN #12;Gravitational Lensing - action of gravity on light SUNSUN #12;Gravitational Lensing - action of gravity on light SUNSUN nn 1801: Johann von1801: Johann von SoldnerSoldner (Newtonian

Weinberger, Hans

89

Holographic Fluids with Vorticity and Analogue Gravity  

E-Print Network [OSTI]

We study holographic three-dimensional fluids with vorticity in local equilibrium and discuss their relevance to analogue gravity systems. The Fefferman-Graham expansion leads to the fluid's description in terms of a comoving and rotating Papapetrou-Randers frame. A suitable Lorentz transformation brings the fluid to the non-inertial Zermelo frame, which clarifies its interpretation as moving media for light/sound propagation. We apply our general results to the Lorentzian Kerr-AdS_4 and Taub-NUT-AdS_4 geometries that describe fluids in cyclonic and vortex flows respectively. In the latter case we associate the appearance of closed timelike curves to analogue optical horizons. In addition, we derive the classical rotational Hall viscosity of three-dimensional fluids with vorticity. Our formula remarkably resembles the corresponding result in magnetized plasmas.

Robert G. Leigh; Anastasios C. Petkou; P. Marios Petropoulos

2012-05-28T23:59:59.000Z

90

Spin-gravity coupling and gravity-induced quantum phases  

E-Print Network [OSTI]

External gravitational fields induce phase factors in the wave functions of particles. The phases are exact to first order in the background gravitational field, are manifestly covariant and gauge invariant and provide a useful tool for the study of spin-gravity coupling and of the optics of particles in gravitational or inertial fields. We discuss the role that spin-gravity coupling plays in particular problems.

Giorgio Papini

2007-09-06T23:59:59.000Z

91

Gravity Currents in Aquatic Canopies  

E-Print Network [OSTI]

A lock exchange experiment is used to investigate the propagation of gravity currents through a random array of rigid, emergent cylinders which represents a canopy of aquatic plants. As canopy drag increases, the propagating ...

Tanino, Yukie

92

Observational Tests of Modified Gravity  

E-Print Network [OSTI]

Modified gravity theories have richer observational consequences for large-scale structure than conventional dark energy models, in that different observables are not described by a single growth factor even in the linear regime. We examine the relationships between perturbations in the metric potentials, density and velocity fields, and discuss strategies for measuring them using gravitational lensing, galaxy cluster abundances, galaxy clustering/dynamics and the ISW effect. We show how a broad class of gravity theories can be tested by combining these probes. A robust way to interpret observations is by constraining two key functions: the ratio of the two metric potentials, and the ratio of the Gravitational ``constant'' in the Poisson equation to Newton's constant. We also discuss quasilinear effects that carry signatures of gravity, such as through induced three-point correlations. Clustering of dark energy can mimic features of modified gravity theories and thus confuse the search for distinct signatures of such theories. It can produce pressure perturbations and anisotropic stresses, which breaks the equality between the two metric potentials even in general relativity. With these two extra degrees of freedom, can a clustered dark energy model mimic modified gravity models in all observational tests? We show with specific examples that observational constraints on both the metric potentials and density perturbations can in principle distinguish modifications of gravity from dark energy models. We compare our result with other recent studies that have slightly different assumptions (and apparently contradictory conclusions).

Bhuvnesh Jain; Pengjie Zhang

2007-09-17T23:59:59.000Z

93

Gravity's smoking gun?  

E-Print Network [OSTI]

We present a new constraint on the biased galaxy formation picture. Gravitational instability theory predicts that the two-point mass density correlation function, \\xi(r), has an inflection point at the separation r=r_0, corresponding to the boundary between the linear and nonlinear regime of clustering, \\xi = 1. We show how this feature can be used to constrain the square of the biasing parameter, b^2 = \\xi_g / \\xi on scales r = r_0, where \\xi_g is the galaxy-galaxy correlation function, allowed to differ from \\xi. We apply our method to real data: the \\xi_g(r), estimated from the APM galaxy survey. Our results suggest that the APM galaxies trace the mass at separations r > 5 Mpc/h, where h is the Hubble constant in units of 100 km/s Mpc. The present results agree with earlier studies, based on comparing higher order correlations in the APM with weakly non-linear perturbation theory. Both approaches constrain the "b" factor to be within 20% of unity. If the existence of the feature we identified in the APM \\xi_g(r) -- the inflection point near \\xi_g = 1 -- is confirmed by more accurate surveys, we may have discovered gravity's smoking gun: the long awaited ``shoulder'' in \\xi, predicted by Gott and Rees 25 years ago.

E. Gaztanaga; R. Juszkiewicz

2001-08-21T23:59:59.000Z

94

Energy bounds in designer gravity  

SciTech Connect (OSTI)

We consider asymptotically anti-de Sitter gravity coupled to tachyonic scalar fields with mass at or slightly above the Breitenlohner-Freedman bound in d{>=}4 spacetime dimensions. The boundary conditions in these ''designer gravity'' theories are defined in terms of an arbitrary function W. We give a general argument that the Hamiltonian generators of asymptotic symmetries for such systems will be finite, and proceed to construct these generators using the covariant phase space method. The direct calculation confirms that the generators are finite and shows that they take the form of the pure gravity result plus additional contributions from the scalar fields. By comparing the generators to the spinor charge, we derive a lower bound on the gravitational energy when W has a global minimum and the Breitenlohner-Freedman bound is not saturated.

Amsel, Aaron J.; Marolf, Donald [Physics Department, UCSB, Santa Barbara, California 93106 (United States)

2006-09-15T23:59:59.000Z

95

Counterterms, critical gravity and holography  

E-Print Network [OSTI]

We consider counterterms for odd dimensional holographic CFTs. These counterterms are derived by demanding cut-off independence of the CFT partition function on $S^d$ and $S^1 \\times S^{d-1}$. The same choice of counterterms leads to a cut-off independent Schwarzschild black hole entropy. When treated as independent actions, these counterterm actions resemble critical theories of gravity, i.e., higher curvature gravity theories where the additional massive spin-2 modes become massless. Equivalently, in the context of AdS/CFT, these are theories where at least one of the central charges associated with the trace anomaly vanishes. Connections between these theories and logarithmic CFTs are discussed. For a specific choice of parameters, the theories arising from counterterms are non-dynamical and resemble a DBI generalization of gravity. For even dimensional CFTs, analogous counterterms cancel log-independent cut-off dependence.

Kallol Sen; Aninda Sinha; Nemani V. Suryanarayana

2012-05-18T23:59:59.000Z

96

New Models of f(R) Theories of Gravity  

E-Print Network [OSTI]

We introduce new models of f(R) theories of gravity that are generalization of Horava-Lifshitz gravity.

J. Kluson

2009-11-04T23:59:59.000Z

97

Lovelock-Brans-Dicke gravity  

E-Print Network [OSTI]

According to Lovelock's theorem, the Hilbert-Einstein and the Lovelock actions are indistinguishable from their field equations. However, they have different scalar-tensor counterparts, which correspond to the Brans-Dicke and the \\emph{Lovelock-Brans-Dicke} (LBD) gravities, respectively. In this paper the LBD model of alternative gravity with the Lagrangian density $\\mathscr{L}_{\\text{LBD}}=\\frac{1}{16\\pi}[\\phi(R+\\frac{a}{\\sqrt{-g}}{}^*RR + b\\mathcal{G})-\\frac{\\omega_{\\text L}}{\\phi}\

David Wenjie Tian; Ivan Booth

2015-03-02T23:59:59.000Z

98

Lovelock-Brans-Dicke gravity  

E-Print Network [OSTI]

According to Lovelock's theorem, the Hilbert-Einstein and the Lovelock actions are indistinguishable from their field equations. However, they have different scalar-tensor counterparts, which correspond to the Brans-Dicke and the \\emph{Lovelock-Brans-Dicke} (LBD) gravities, respectively. In this paper the LBD model of alternative gravity with the Lagrangian density $\\mathscr{L}_{\\text{LBD}}=\\frac{1}{16\\pi}\\left[\\phi\\left(R+\\frac{a}{\\sqrt{-g}}{}^*RR + b\\mathcal{G}\\right)-\\frac{\\omega_{\\text L}}{\\phi}\

Tian, David Wenjie

2015-01-01T23:59:59.000Z

99

Astrophysical Tests of Modified Gravity  

E-Print Network [OSTI]

Chameleon and similar (symmetron and dilation) theories of gravity can exhibit new and interesting features on cosmological scales whilst screening the modifications on small scales thereby satisfying solar system tests of general relativity. This thesis explores the regime between these two scales: astrophysics. The majority of this thesis is focused on discerning new and novel astrophysical probes of chameleon gravity in the form of stellar structure and oscillation tests. These are used to place new constraints on the theory parameters and the implications of these are discussed, as are the future prospects for improving them using planned future surveys. The final two chapters review supersymmetric completions of these theories.

Sakstein, Jeremy

2015-01-01T23:59:59.000Z

100

Variable Mass Theories of Gravity  

E-Print Network [OSTI]

Several attempts to construct theories of gravity with variable mass are considered. The theoretical impacts of allowing the rest mass to vary with respect to time or an appropriate curve parameter are examined in the framework of Newtonian and Einsteinian gravity theories. In further steps, scalar-tensor theories are examined with respect to their relation to the variation of the mass and in an ultimate step, an additional coordinate is introduced and its possible relation to the mass is examined, yielding a five dimensional space-time-matter theory.

M. Leclerc

2002-12-03T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Gravity Capillary Standing Water Waves Pietro Baldi  

E-Print Network [OSTI]

Gravity Capillary Standing Water Waves Pietro Baldi Universit`a di Napoli Federico II Joint work with Thomas Alazard (ENS Paris) Pienza, 29 October 2014 Pietro Baldi Gravity Capillary Standing Water Waves, with gravity and capillarity (WW) t = G() t = -g - 1 2 2 x + (G() + xx)2 2(1 + 2 x) + xx (1 + 2 x)3/2 We

Thomann, Laurent

102

Gravity Transform for Input Conditioning in  

E-Print Network [OSTI]

Gravity Transform for Input Conditioning in Brain Machine Interfaces António R. C. Paiva, José C. Motivation 2. Methods i. Gravity Transform ii. Modeling and output sensitivity analysis 3. Data Analysis #12;3 Outline 1. Motivation 2. Methods i. Gravity Transform ii. Modeling and output sensitivity analysis 3. Data

Paiva, António R. C.

103

Spin-stabilized magnetic levitation without vertical axis of rotation  

DOE Patents [OSTI]

The symmetry properties of a magnetic levitation arrangement are exploited to produce spin-stabilized magnetic levitation without aligning the rotational axis of the rotor with the direction of the force of gravity. The rotation of the rotor stabilizes perturbations directed parallel to the rotational axis.

Romero, Louis (Albuquerque, NM); Christenson, Todd (Albuquerque, NM); Aaronson, Gene (Albuquerque, NM)

2009-06-09T23:59:59.000Z

104

Antimatter, the SME, and Gravity  

E-Print Network [OSTI]

A general field-theoretic framework for the analysis of CPT and Lorentz violation is provided by the Standard-Model Extension (SME). This work discusses a number of SME-based proposals for tests of CPT and Lorentz symmetry, including antihydrogen spectroscopy and antimatter gravity tests.

Jay D. Tasson

2012-12-07T23:59:59.000Z

105

Antimatter, the SME, and Gravity  

E-Print Network [OSTI]

A general field-theoretic framework for the analysis of CPT and Lorentz violation is provided by the Standard-Model Extension (SME). This work discusses a number of SME-based proposals for tests of CPT and Lorentz symmetry, including antihydrogen spectroscopy and antimatter gravity tests.

Tasson, Jay D

2012-01-01T23:59:59.000Z

106

Cosmological structures in generalized gravity  

E-Print Network [OSTI]

In a class of generalized gravity theories with general couplings between the scalar field and the scalar curvature in the Lagrangian, we describe the quantum generation and the classical evolution processes of both the scalar and tensor structures in a simple and unified manner.

J. Hwang

1997-11-28T23:59:59.000Z

107

Quantum Gravity and Precision Tests  

E-Print Network [OSTI]

This article provides a cartoon of the quantization of General Relativity using the ideas of effective field theory. These ideas underpin the use of General Relativity as a theory from which precise predictions are possible, since they show why quantum corrections to standard classical calculations are small. Quantum corrections can be computed controllably provided they are made for the weakly-curved geometries associated with precision tests of General Relativity, such as within the solar system or for binary pulsars. They also bring gravity back into the mainstream of physics, by showing that its quantization (at low energies) exactly parallels the quantization of other, better understood, non-renormalizable field theories which arise elsewhere in physics. Of course effective field theory techniques do not solve the fundamental problems of quantum gravity discussed elsewhere in these pages, but they do helpfully show that these problems are specific to applications on very small distance scales. They also show why we may safely reject any proposals to modify gravity at long distances if these involve low-energy problems (like ghosts or instabilities), since such problems are unlikely to be removed by the details of the ultimate understanding of gravity at microscopic scales.

C. P. Burgess

2006-06-24T23:59:59.000Z

108

Overlap Fermion in External Gravity  

E-Print Network [OSTI]

On a lattice, we construct an overlap Dirac operator which describes the propagation of a Dirac fermion in external gravity. The local Lorentz symmetry is manifestly realized as a lattice gauge symmetry, while the general coordinate invariance is expected to be restored only in the continuum limit. The lattice index density in the presence of a gravitational field is calculated.

Hiroto So; Masashi Hayakawa; Hiroshi Suzuki

2006-12-12T23:59:59.000Z

109

Gravity and the Fermion Mass  

E-Print Network [OSTI]

It is shown that gravity generates mass for the fermion. It does so by coupling directly with the spinor field. The coupling term is invariant with respect to the electroweak gauge group $ U(1) \\otimes SU(2)_L. $ It replaces the fermion mass term $ m\\bar{\\psi} \\psi $.

Kenneth Dalton

2010-06-11T23:59:59.000Z

110

Perspectives on Quantum Gravity Phenomenology  

E-Print Network [OSTI]

The idea that quantum gravity manifestations would be associated with a violation of Lorentz invariance is very strongly bounded and faces serious theoretical challenges. Other related ideas seem to be drowning in interpretational quagmires. This leads us to consider alternative lines of thought for such phenomenological search. We discuss the underlying viewpoints and briefly mention their possible connections with other current theoretical ideas.

Daniel Sudarsky

2005-12-01T23:59:59.000Z

111

High-gravity central stars  

E-Print Network [OSTI]

NLTE spectral analyses of high-gravity central stars by means of state-of-the-art model atmosphere techniques provide information about the precursor AGB stars. The hydrogen-deficient post-AGB stars allow investigations on the intershell matter which is apparently exhibited at the stellar surface. We summarize recent results from imaging, spectroscopy, and spectropolarimetry.

Thomas Rauch

2006-07-11T23:59:59.000Z

112

Multiple Ising Spins Coupled to 2d Quantum Gravity  

E-Print Network [OSTI]

We study a model in which p independent Ising spins are coupled to 2d quantum gravity (in the form of dynamical planar phi-cubed graphs). Consideration is given to the p tends to infinity limit in which the partition function becomes dominated by certain graphs; we identify most of these graphs. A truncated model is solved exactly providing information about the behaviour of the full model in the limit of small beta. Finally, we derive a bound for the critical value of the coupling constant, beta_c and examine the magnetization transition in the limit p tends to zero.

M. G. Harris; J. F. Wheater

1994-04-28T23:59:59.000Z

113

The Dark Gravity model predictions for Gravity Probe B  

E-Print Network [OSTI]

The previous version of this article gave erroneous predictions. The correct uptodate predictions can be found in the section devoted to gravitomagnetism in the living review of the Dark Gravity theory: gr-qc/0610079 The most natural prediction is zero frame dragging and the same geodetic effect as predicted by GR. However, a straightforward extension of the theory could lead to the same frame-dragging as in GR.

Frederic Henry-Couannier

2007-10-23T23:59:59.000Z

114

On the support of neutrals against gravity in solar prominences  

E-Print Network [OSTI]

Cool and dense prominences found in the solar atmosphere are known to be partially ionized because of their relative low temperature. In this Letter, we address the long-standing problem of how the neutral component of the plasma in prominences is supported against gravity. Using the multiple fluid approach we solve the time-dependent equations in two dimensions considering the frictional coupling between the neutral and ionized components of the magnetized plasma representative of a solar prominence embedded in a hot coronal environment. We demonstrate that given an initial density enhancement in the two fluids, representing the body of the prominence, the system is able to relax in the vicinity of magnetic dips to a stationary state in which both neutrals and ionized species are dynamically suspended above the photosphere. Two different coupling processes are considered in this study, collisions between ions and neutrals and charge exchange interactions. We find that for realistic conditions ions are essent...

Terradas, J; Oliver, R; Ballester, J L

2015-01-01T23:59:59.000Z

115

Axions in gravity with torsion  

E-Print Network [OSTI]

We study a scenario allowing a solution of the strong CP-problem via the Peccei-Quinn mechanism, implemented in gravity with torsion. In this framework there appears a torsion-related pseudoscalar field known as Kalb-Ramond axion. We compare it with the so called Barbero-Immirzi axion recently proposed in the literature also in the context of the gravity with torsion. We show that they are equivalent from the view point of the effective theory. The phenomenology of these torsion-descended axions is completely determined by the Planck scale without any additional model parameters. These axions are very light and very weakly interacting with ordinary matter. We briefly comment on their astrophysical and cosmological implications in view of the recent BICEP2 and Planck data.

Castillo-Felisola, Oscar; Kovalenko, Sergey; Schmidt, Ivan; Lyubovitskij, Valery E

2015-01-01T23:59:59.000Z

116

Black holes in massive gravity  

E-Print Network [OSTI]

We review the black hole solutions of the ghost-free massive gravity theory and its bimetric extension and outline the main results on the stability of these solutions against small perturbations. Massive (bi)-gravity accommodates exact black hole solutions, analogous to those of General Relativity. In addition to these solutions, hairy black holes -- solutions with no correspondent in General Relativity -- have been found numerically, whose existence is a natural consequence of the absence of the Birkhoff's theorem in these theories. The existence of extra propagating degrees of freedom, makes the stability properties of these black holes richer and more complex than those of General Relativity. In particular, the bi-Schwarzschild black hole exhibits an unstable spherically symmetric mode, while the bi-Kerr geometry is also generically unstable, both against the spherical mode and against superradiant instabilities. If astrophysical black holes are described by these solutions, the superradiant instability o...

Babichev, Eugeny

2015-01-01T23:59:59.000Z

117

Quantum Gravity at the LHC  

E-Print Network [OSTI]

It has recently been shown that if there is a large hidden sector in Nature, the scale of quantum gravity could be much lower than traditionally expected. We study the production of massless gravitons at the LHC and compare our results to those obtained in extra dimensional models. The signature in both cases is missing energy plus jets. In case of non observation, the LHC could be used to put the tightest limit to date on the value of the Planck mass.

Xavier Calmet; Priscila de Aquino

2009-10-08T23:59:59.000Z

118

Gravity Techniques | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of InspectorConcentrating Solar Power BasicsGermany: Energy Resources JumpEnergyGoltryOhio: EnergyGravity

119

Dynamical 3-Space: Emergent Gravity  

E-Print Network [OSTI]

The laws of gravitation devised by Newton, and by Hilbert and Einstein, have failed many experimental and observational tests, namely the bore hole g anomaly, flat rotation curves for spiral galaxies, supermassive black hole mass spectrum, uniformly expanding universe, cosmic filaments, laboratory G measurements, galactic EM bending, precocious galaxy formation,.. The response has been the introduction of the new epicycles: ``dark matter", ``dark energy", and others. To understand gravity we must restart with the experimental discoveries by Galileo, and following a heuristic argument we are led to a uniquely determined theory of a dynamical 3-space. That 3-space exists has been missed from the beginning of physics, although it was 1st directly detected by Michelson and Morley in 1887. Uniquely generalising the quantum theory to include this dynamical 3-space we deduce the response of quantum matter and show that it results in a new account of gravity, and explains the above anomalies and others. The dynamical theory for this 3-space involves G, which determines the dissipation rate of space by matter, and alpha, which experiments and observation reveal to be the fine structure constant. For the 1st time we have a comprehensive account of space and matter and their interaction - gravity.

Reginald T Cahill

2011-02-16T23:59:59.000Z

120

Dynamical stability of Minkowski space in higher order gravity  

E-Print Network [OSTI]

We discuss the Minkowski stability problem in modified gravity by using dynamical system approach. The method to investigate dynamical stability of Minkowski space was proposed. This method was applied for a some modified gravity theories, such as $f(R)$ gravity, $f(R)+\\alpha R\\Box R$ gravity and scalar-tensor gravity models with non-minimal kinetic coupling.

Petr Tretyakov

2014-07-15T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Entropic Motion in Loop Quantum Gravity  

E-Print Network [OSTI]

Entropic forces result from an increase of the entropy of a thermodynamical physical system. It has been proposed that gravity is such a phenomenon and many articles have appeared on the literature concerning this problem. Loop quantum gravity has also considered such possibility. We propose a new method in loop quantum gravity which reproduces an entropic force. By considering the interaction between a fixed gravity state space and a particle state in loop quantum gravity, we show that it leads to a mathematical description of a random walk of such particle. The random walk in special situations, can be seen as an entropic motion in such a way that the particle will move towards a location where entropy increases. This may prove that such theory can reproduce gravity as it is expected.

J. Manuel Garcia-Islas

2015-02-19T23:59:59.000Z

122

Born-Infeld gravity in three dimensions  

SciTech Connect (OSTI)

In this paper we explore different aspects of three dimensional Born-Infeld as well as Born-Infeld-Chern-Simons gravity. We show that the models have anti-de Sitter and anti-de Sitter wave vacuum solutions. Moreover, we observe that although Born-Infeld-Chern-Simons gravity admits a logarithmic solution, Born-Infeld gravity does not, though it has a limiting logarithmic solution as we approach the critical point.

Alishahiha, Mohsen [School of physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Naseh, Ali [School of physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of); Soltanpanahi, Hesam [School of physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); School of Physics and Centre for Theoretical Physics, University of the Witwatersrand, WITS 2050 Johannesburg (South Africa)

2010-07-15T23:59:59.000Z

123

Gravity from the extension of spatial diffeomorphisms  

E-Print Network [OSTI]

The possibility of the extension of spatial diffeomorphisms to a larger family of symmetries in a class of classical field theories is studied. The generator of the additional local symmetry contains a quadratic kinetic term and a potential term which can be a general (not necessarily local) functional of the metric. From the perspective of the foundation of Einstein's gravity our results are positive: The extended constraint algebra is either that of Einstein's gravity, or ultralocal gravity. If our goal is a simple modification of Einstein's gravity that for example makes it perturbatively renormalizable, as has recently been suggested, then our results show that there is no such theory within this class.

Szilard Farkas; Emil J. Martinec

2010-02-24T23:59:59.000Z

124

Cosmological Acceleration: Dark Energy or Modified Gravity?  

E-Print Network [OSTI]

We review the evidence for recently accelerating cosmological expansion or "dark energy", either a negative pressure constituent in General Relativity (Dark Energy) or modified gravity (Dark Gravity), without any Dark Energy constituent. If constituent Dark Energy does not exist, so that our universe is now dominated by pressure-free matter, Einstein gravity must be modified at low curvature. The vacuum symmetry of any Robertson-Walker universe then characterizes Dark Gravity as low- or high-curvature modifications of Einstein gravity. The dynamics of either kind of "dark energy" cannot be derived from the homogeneous expansion alone, but requires also observing the growth of inhomogeneities. Present and projected observations are all consistent with a small fine tuned cosmological constant, with nearly static Dark Energy, or with gravity modified at cosmological scales. The growth of cosmological fluctuations will potentially distinguish static "dark energy" from dynamic "dark energy" with equation of state $w(z)$ either changing rapidly or tracking the background matter. But to cosmologically distinguish $\\Lambda$CDM from modified gravity will require a weak lensing shear survey more ambitious than any now projected. Dvali-Gabadadze-Porrati modifications of Einstein gravity may also be detected in refined bservations in the solar system or at the intermediate Vainstein scale. Dark Energy's epicyclic character, failure to explain the original Cosmic Coincidence ("Why now?") without fine tuning, inaccessibility to laboratory or solar system tests, along with braneworld theories, now motivate future precision solar system, Vainstein-scale and cosmological-scale studies of Dark Gravity.

Sidney Bludman

2006-06-12T23:59:59.000Z

125

Horizon entropy with loop quantum gravity methods  

E-Print Network [OSTI]

We show that the spherically symmetric isolated horizon can be described in terms of an SU(2) connection and a su(2) valued one form, obeying certain constraints. The horizon symplectic structure is precisely the one of 3d gravity in a first order formulation. We quantize the horizon degrees of freedom in the framework of loop quantum gravity, with methods recently developed for 3d gravity with non-vanishing cosmological constant. Bulk excitations ending on the horizon act very similar to particles in 3d gravity. The Bekenstein-Hawking law is recovered in the limit of imaginary Barbero-Immirzi parameter. Alternative methods of quantization are also discussed.

Daniele Pranzetti; Hanno Sahlmann

2014-12-23T23:59:59.000Z

126

Doubly Special Relativity and quantum gravity phenomenology  

E-Print Network [OSTI]

I review the conceptual, algebraical, and geometrical structure of Doubly Special Relativity. I also speculate about the possible relevance of DSR for quantum gravity phenomenology.

J. Kowalski-Glikman

2003-12-12T23:59:59.000Z

127

Gravity modeling of Cenozoic extensional basins, offshore Vietnam  

E-Print Network [OSTI]

(Yinggehai) basins. Gravity modeling results provide important clues to the controversial tectonic development of Southeast Asia during the Tertiary. Combined Bouguer and free-air gravity maps and residual gravity anomaly maps were generated for the study...

Mauri, Steven Joseph

1993-01-01T23:59:59.000Z

128

Quantum Geometry and Quantum Gravity  

E-Print Network [OSTI]

The purpose of this contribution is to give an introduction to quantum geometry and loop quantum gravity for a wide audience of both physicists and mathematicians. From a physical point of view the emphasis will be on conceptual issues concerning the relationship of the formalism with other more traditional approaches inspired in the treatment of the fundamental interactions in the standard model. Mathematically I will pay special attention to functional analytic issues, the construction of the relevant Hilbert spaces and the definition and properties of geometric operators: areas and volumes.

J. Fernando Barbero G.

2008-04-23T23:59:59.000Z

129

Universality in Pure Gravity Mediation  

E-Print Network [OSTI]

If low energy supersymmetry is realized in nature, the apparent discovery of a Higgs boson with mass around 125 GeV points to a supersymmetric mass spectrum in the TeV or multi-TeV range. Multi-TeV scalar masses are a necessary component of supersymmetric models with pure gravity mediation or in any model with strong moduli stabilization. Here, we show that full scalar mass universality remains viable as long as the ratio of Higgs vevs, tan beta is relatively small (\\lesssim 2.5). We discuss in detail the low energy (observable) consequences of these models.

Jason L. Evans; Masahiro Ibe; Keith A. Olive; Tsutomu T. Yanagida

2014-05-30T23:59:59.000Z

130

Negative mass solitons in gravity  

SciTech Connect (OSTI)

We first reconstruct the conserved (Abbott-Deser) charges in the spin-connection formalism of gravity for asymptotically (Anti)-de Sitter spaces, and then compute the masses of the AdS soliton and the recently found Eguchi-Hanson solitons in generic odd dimensions, unlike the previous result obtained for only five dimensions. These solutions have negative masses compared to the global AdS or AdS/Z{sub p} spacetimes. As a separate note, we also compute the masses of the recent even dimensional Taub-NUT-Reissner-Nordstroem metrics.

Cebeci, Hakan; Sarioglu, Oezguer; Tekin, Bayram [Anadolu University, Department of Physics, Yunus Emre Campus, 26470, Eskisehir (Turkey); Department of Physics, Faculty of Arts and Sciences, Middle East Technical University, 06531, Ankara (Turkey)

2006-03-15T23:59:59.000Z

131

Quantum Field Theory & Gravity  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 -the Mid-Infrared at 278, 298, and 323 K. |Quantum Field Theory & Gravity

132

Asymptotically (anti)-de Sitter solutions in Gauss-Bonnet gravity without a cosmological constant  

SciTech Connect (OSTI)

In this paper I show that one can have asymptotically de Sitter, anti-de Sitter (AdS), and flat solutions in Gauss-Bonnet gravity without a cosmological constant term in field equations. First, I introduce static solutions whose three surfaces at fixed r and t have constant positive (k=1), negative (k=-1), or zero (k=0) curvature. I show that for k={+-}1 one can have asymptotically de Sitter, AdS, and flat spacetimes, while for the case of k=0, one has only asymptotically AdS solutions. Some of these solutions present naked singularities, while some others are black hole or topological black hole solutions. I also find that the geometrical mass of these five-dimensional spacetimes is m+2{alpha}|k|, which is different from the geometrical mass m of the solutions of Einstein gravity. This feature occurs only for the five-dimensional solutions, and is not repeated for the solutions of Gauss-Bonnet gravity in higher dimensions. Second, I add angular momentum to the static solutions with k=0, and introduce the asymptotically AdS charged rotating solutions of Gauss-Bonnet gravity. Finally, I introduce a class of solutions which yields an asymptotically AdS spacetime with a longitudinal magnetic field, which presents a naked singularity, and generalize it to the case of magnetic rotating solutions with two rotation parameters.

Dehghani, M.H. [Physics Department and Biruni Observatory, Shiraz University, Shiraz 71454, Iran (Iran, Islamic Republic of); Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Research Institute for Astrophysics and Astronomy of Maragha, P.O. Box 55134-441, Maragha (Iran, Islamic Republic of)

2004-09-15T23:59:59.000Z

133

Ground Gravity Survey At Neal Hot Springs Geothermal Area (Colwell...  

Open Energy Info (EERE)

Technique Ground Gravity Survey Activity Date 2011 - 2011 Usefulness not indicated DOE-funding Unknown Exploration Basis Gravity surveys were conducted to gain a better...

134

Integration of Full Tensor Gravity and ZTEM Passive Low Frequency...  

Broader source: Energy.gov (indexed) [DOE]

Integration of Full Tensor Gravity and ZTEM Passive Low Frequency EM Instruments for Simultaneous Data Acquisition Integration of Full Tensor Gravity and ZTEM Passive Low Frequency...

135

Reduced Gravity Education Flight Opportunity for Students at...  

Broader source: Energy.gov (indexed) [DOE]

Reduced Gravity Education Flight Opportunity for Students at Minority Serving Institutions Reduced Gravity Education Flight Opportunity for Students at Minority Serving...

136

airborne gravity survey: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Gravity CERN Preprints Summary: Modified gravity theories may provide an alternative to dark energy to explain cosmic acceleration. We argue that the observational program...

137

Quantum Gravity Phenomenology and Lorentz Violation  

E-Print Network [OSTI]

If quantum gravity violates Lorentz symmetry, the prospects for observational guidance in understanding quantum gravity improve considerably. This article briefly reviews previous work on Lorentz violation (LV) and discusses aspects of the effective field theory framework for parametrizing LV effects. Current observational constraints on LV are then summarized, focusing on effects in QED at order E/M_Planck.

Ted Jacobson; Stefano Liberati; David Mattingly

2004-04-15T23:59:59.000Z

138

Gravity in Complex Hermitian Space-Time  

E-Print Network [OSTI]

A generalized theory unifying gravity with electromagnetism was proposed by Einstein in 1945. He considered a Hermitian metric on a real space-time. In this work we review Einstein's idea and generalize it further to consider gravity in a complex Hermitian space-time.

Ali H. Chamseddine

2006-10-09T23:59:59.000Z

139

Fractional Exact Solutions and Solitons in Gravity  

E-Print Network [OSTI]

We survay our recent results on fractional gravity theory. It is also provided the Main Theorem on encoding of geometric data (metrics and connections in gravity and geometric mechanics) into solitonic hierarchies. Our approach is based on Caputo fractional derivative and nonlinear connection formalism.

Dumitru Baleanu; Sergiu I. Vacaru

2010-08-02T23:59:59.000Z

140

Scale-Free Growing Networks and Gravity  

E-Print Network [OSTI]

We propose a possible relation between complex networks and gravity. Our guide in our proposal is the power-law distribution of the node degree in network theory and the information approach to gravity. The established bridge may allow us to carry geometric mathematical structures, which are considered in gravitational theories, to probabilistic aspects studied in the framework of complex networks and vice versa.

J. A. Nieto

2012-11-29T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

The Superheavy Elements and Anti-Gravity  

SciTech Connect (OSTI)

The essence of any propulsion concept is to overcome gravity. Anti-gravity is a natural means to achieve this. Thus, the technology to pursue anti-gravity, by using superheavy elements, may provide a new propulsion paradigm. The theory of superluminal relativity provides a hypothesis for existence of elements with atomic number up to Z = 145, some of which may possess anti-gravity properties. Analysis results show that curved space-time exists demonstrating both gravitic and anti-gravitic properties not only around nuclei but inside the nuclei as well. Two groups of elements (Z < 64 and 63 < Z <145) exist that demonstrate these capabilities. The nuclei of the first group of elements have the masses with only the property of gravity. The nuclei of the elements of the second group have the masses with both properties: gravity and anti-gravity in two different ranges of curved space-time around the nuclei.. The hypothetical element with Z = 145 is the unique among all elements whose nucleus has only anti-gravity property. It is proposed that this element be named Hawking, in honour of Stephen W. Hawking.

Anastasovski, Petar K. [Department of Physics, Faculty of Technology and Metallurgy, Saints Cyril and Methodius University, Skopje (Macedonia, The Former Yugoslav Republic of)

2004-02-04T23:59:59.000Z

142

Quantum Gravity Phenomenology, Lorentz Invariance and Discreteness  

E-Print Network [OSTI]

Quantum Gravity Phenomenology, Lorentz Invariance and Discreteness Fay Dowker #3; , Joe Henson y invariant, and we recall the reasons why. For illustration, we introduce a phenomenological model of massive { LLI violating phenomenological e#11;ects of quantum gravity { has grown up around this idea

Sorkin, Rafael Dolnick

143

Dual Accretion Disks in Alternate Gravity Theories  

E-Print Network [OSTI]

The interior of gravitationally collapsed objects in alternate theories of gravity in which event horizons and singularities do not occur in strong field gravity were generically investigated. These objects, called red holes, were found to contain dynamic configurations of matter, radiation and spacetime similar to inside out accretion disks well inside the photon orbit. Applications to astrophysical phenomena are briefly described.

James S. Graber

1997-12-15T23:59:59.000Z

144

Reconstruction of Einstein-Aether Gravity from other Modified Gravity Models  

E-Print Network [OSTI]

We briefly describe the modified Friedmann equations for Einstein-Aether gravity theory and we find the effective density and pressure. The purpose of our present work is to reconstruction of Einstein-Aether Gravity from other modified gravities like $f(T)$, $f(R)$, $f(G)$, $f(R,T)$ and $f(R,G)$ and check its viability. The scale factor is chosen in power law form. The free function $F(K)$ for Einstein-Aether gravity (where $K$ is proportional to $H^{2}$) have been found in terms for $K$ by the correspondence between Einstein-Aether gravity and other modified gravities and the nature of $F(K)$ vs $K$ have been shown graphically for every cases. Finally, we analyzed the stability of each reconstructed Einstein-Aether gravity model.

Chayan Ranjit; Ujjal Debnath

2014-09-08T23:59:59.000Z

145

Ground Magnetic Data for west-central Colorado  

SciTech Connect (OSTI)

Ground Magnetic Data for west-central Colorado Modeled ground magnetic data was extracted from the Pan American Center for Earth and Environmental Studies database at http://irpsrvgis08.utep.edu/viewers/Flex/GravityMagnetic/GravityMagnetic_CyberShare/ on 2/29/2012. The downloaded text file was then imported into an Excel spreadsheet. This spreadsheet data was converted into an ESRI point shapefile in UTM Zone 13 NAD27 projection, showing location and magnetic field strength in nano-Teslas. This point shapefile was then interpolated to an ESRI grid using an inverse-distance weighting method, using ESRI Spatial Analyst. The grid was used to create a contour map of magnetic field strength. This dataset includes the raw spreadsheet data, an ESRI point shapefile showing magnetic sample locations and magnetic field strength, and an ESRI line shapefile showing magnetic contours. Projection: UTM Zone 13 NAD27 Magnetic Contour Shapefile Extent: West -108.698836 East -105.283977 North 41.048206 South 36.950086 Magnetic Point Shapefile Extent: West -108.698832 East -105.283908 North 41.048142 South 36.950086

Zehner, Richard

2012-03-08T23:59:59.000Z

146

Gravity's Rainbow induces Topology Change  

E-Print Network [OSTI]

In this work, we explore the possibility that quantum fluctuations induce a topology change, in the context of Gravity's Rainbow. A semi-classical approach is adopted, where the graviton one-loop contribution to a classical energy in a background spacetime is computed through a variational approach with Gaussian trial wave functionals. The energy density of the graviton one-loop contribution, or equivalently the background spacetime, is then let to evolve, and consequently the classical energy is determined. More specifically, the background metric is fixed to be Minkowskian in the equation governing the quantum fluctuations, which behaves essentially as a backreaction equation, and the quantum fluctuations are let to evolve; the classical energy, which depends on the evolved metric functions, is then evaluated. Analysing this procedure, a natural ultraviolet (UV) cutoff is obtained, which forbids the presence of an interior spacetime region, and may result in a multipy-connected spacetime. Thus, in the context of Gravity's Rainbow, this process may be interpreted as a change in topology, and in principle results in the presence of a Planckian wormhole.

Remo Garattini; Francisco S. N. Lobo

2014-08-20T23:59:59.000Z

147

Solar System constraints to nonminimally coupled gravity  

E-Print Network [OSTI]

We extend the analysis of Chiba, Smith and Erickcek \\cite{CSE} of Solar System constraints on $f(R)$ gravity to a class of nonminimally coupled (NMC) theories of gravity. These generalize $f(R)$ theories by replacing the action functional of General Relativity (GR) with a more general form involving two functions $f^1(R)$ and $f^2(R)$ of the Ricci scalar curvature $R$. While the function $f^1(R)$ is a nonlinear term in the action, analogous to $f(R)$ gravity, the function $f^2(R)$ yields a NMC between the matter Lagrangian density $\\LL_m$ and the scalar curvature. The developed method allows for obtaining constraints on the admissible classes of functions $f^1(R)$ and $f^2(R)$, by requiring that predictions of NMC gravity are compatible with Solar System tests of gravity. We apply this method to a NMC model which accounts for the observed accelerated expansion of the Universe.

Orfeu Bertolami; Riccardo March; Jorge Pramos

2013-06-05T23:59:59.000Z

148

Dimensional Reduction in Quantum Gravity  

E-Print Network [OSTI]

The requirement that physical phenomena associated with gravitational collapse should be duly reconciled with the postulates of quantum mechanics implies that at a Planckian scale our world is not 3+1 dimensional. Rather, the observable degrees of freedom can best be described as if they were Boolean variables defined on a two-dimensional lattice, evolving with time. This observation, deduced from not much more than unitarity, entropy and counting arguments, implies severe restrictions on possible models of quantum gravity. Using cellular automata as an example it is argued that this dimensional reduction implies more constraints than the freedom we have in constructing models. This is the main reason why so-far no completely consistent mathematical models of quantum black holes have been found. Essay dedicated to Abdus Salam.

G. 't Hooft

2009-03-20T23:59:59.000Z

149

Hamiltonian structure of Horava gravity  

E-Print Network [OSTI]

The Hamiltonian formulation of Horava gravity is derived. In a closed universe the Hamiltonian is a sum of generators of gauge symmetries, the foliation-preserving diffeomorphisms, and vanishes on shell. The scalar constraint is second class, except for a global, first-class part that generates time reparametrizations. A reduced phase space formulation is given in which the local part of the scalar constraint is solved formally for the lapse as a function of the 3 metric and its conjugate momentum. In the infrared limit the scalar constraint is linear in the square root of the lapse. For asymptotically flat boundary conditions the Hamiltonian is a sum of bulk constraints plus a boundary term that gives the total energy. This energy expression is identical to the one for Einstein-aether theory which, for static spherically symmetric solutions, is the usual Arnowitt-Deser-Misner energy of general relativity with a rescaled Newton constant.

William Donnelly; Ted Jacobson

2012-01-16T23:59:59.000Z

150

Nonlinear Fluid Dynamics from Gravity  

E-Print Network [OSTI]

Black branes in AdS5 appear in a four parameter family labeled by their velocity and temperature. Promoting these parameters to Goldstone modes or collective coordinate fields -- arbitrary functions of the coordinates on the boundary of AdS5 -- we use Einstein's equations together with regularity requirements and boundary conditions to determine their dynamics. The resultant equations turn out to be those of boundary fluid dynamics, with specific values for fluid parameters. Our analysis is perturbative in the boundary derivative expansion but is valid for arbitrary amplitudes. Our work may be regarded as a derivation of the nonlinear equations of boundary fluid dynamics from gravity. As a concrete application we find an explicit expression for the expansion of this fluid stress tensor including terms up to second order in the derivative expansion.

Sayantani Bhattacharyya; Veronika E Hubeny; Shiraz Minwalla; Mukund Rangamani

2008-04-02T23:59:59.000Z

151

Testing Relativistic Gravity with Radio Pulsars  

E-Print Network [OSTI]

Before the 1970s, precision tests for gravity theories were constrained to the weak gravitational fields of the Solar system. Hence, only the weak-field slow-motion aspects of relativistic celestial mechanics could be investigated. Testing gravity beyond the first post-Newtonian contributions was for a long time out of reach. The discovery of the first binary pulsar by Russell Hulse and Joseph Taylor in the summer of 1974 initiated a completely new field for testing the relativistic dynamics of gravitationally interacting bodies. For the first time the back reaction of gravitational wave emission on the binary motion could be studied. Furthermore, the Hulse-Taylor pulsar provided the first test bed for the orbital dynamics of strongly self-gravitating bodies. To date there are a number of pulsars known, which can be utilized for precision test of gravity. Depending on their orbital properties and their companion, these pulsars provide tests for various different aspects of relativistic dynamics. Besides tests of specific gravity theories, like general relativity or scalar-tensor gravity, there are pulsars that allow for generic constraints on potential deviations of gravity from general relativity in the quasi-stationary strong-field and the radiative regime. This article presents a brief overview of this modern field of relativistic celestial mechanics, reviews some of the highlights of gravity tests with radio pulsars, and discusses their implications for gravitational physics and astronomy, including the upcoming gravitational wave astronomy.

Norbert Wex

2014-02-23T23:59:59.000Z

152

Newtonian gravity, red shift, confinement, asymptotic freedom and quarks oscillations  

E-Print Network [OSTI]

Quarks oscillations give the Newtonian gravity law, the red shift, the confinement and the asymptotic freedom.

G. Quznetsov

2008-10-18T23:59:59.000Z

153

Gravity Recovery And Climate Experiment Hydrology, Earth Science and Climate  

E-Print Network [OSTI]

GRACE Gravity Recovery And Climate Experiment Hydrology, Earth Science and Climate Ole Baltazar of blood cell Delivers 10-Day / Monthly gravity field From 2002 Onwards Study gravity field changes | side 6 Range responds to Gravity #12;GRACE science results | 28. November 2007 | OA | side 7 Variations

Mosegaard, Klaus

154

Loop Quantum Gravity 1. Classical framework : Ashtekar-Barbero connection  

E-Print Network [OSTI]

gravity Why Quantum Gravity ? Gravitation vs. Quantum Physics : the two infinities Gravitation : large Quantum Gravity ? Gravitation vs. Quantum Physics : the two infinities Gravitation : large scales-perturbative renormalization Gravity is not a fundamental theory but it is effective (law energy) · it has to be modified

Sart, Remi

155

Evolution of Structures in Generalized Gravity Theories  

E-Print Network [OSTI]

A broad class of generalized Einstein's gravity can be cast into Einstein's gravity with a minimally coupled scalar field using suitable conformal rescaling of the metric. Using this conformal equivalence between the theories, we derive the equations for the background and the perturbations, and the general asymptotic solutions for the perturbations in the generalized Einstein's gravity from the simple results known in the minimally coupled scalar field. Results for the scalar and tensor perturbations can be presented in unified forms. The large scale evolutions for both modes are characterized by corresponding conserved quantities. We also present the normalization condition for canonical quantization.

J. Hwang

1996-05-12T23:59:59.000Z

156

Gravity as BF theory plus potential  

E-Print Network [OSTI]

Spin foam models of quantum gravity are based on Plebanski's formulation of general relativity as a constrained BF theory. We give an alternative formulation of gravity as BF theory plus a certain potential term for the B-field. When the potential is taken to be infinitely steep one recovers general relativity. For a generic potential the theory still describes gravity in that it propagates just two graviton polarizations. The arising class of theories is of the type amenable to spin foam quantization methods, and, we argue, may allow one to come to terms with renormalization in the spin foam context.

Kirill Krasnov

2009-07-23T23:59:59.000Z

157

Gauge Gravity and Space-Time  

E-Print Network [OSTI]

When we discuss problems on gravity, we can not avoid some fundamental physical problems, such as space-time, inertia, and inertial reference frame. The goal of this paper is to discuss the logic system of gravity theory and the problems of space-time, inertia, and inertial reference frame. The goal of this paper is to set up the theory on space-time in gauge theory of gravity. Based on this theory, it is possible for human kind to manipulate physical space-time on earth, and produce a machine which can physically prolong human's lifetime.

Ning Wu

2012-07-11T23:59:59.000Z

158

Fractal Structure of Loop Quantum Gravity  

E-Print Network [OSTI]

In this paper we have calculated the spectral dimension of loop quantum gravity (LQG) using simple arguments coming from the area spectrum at different length scales. We have obtained that the spectral dimension of the spatial section runs from 2 to 3, across a 1.5 phase, when the energy of a probe scalar field decrees from high to low energy. We have calculated the spectral dimension of the space-time also using results from spin-foam models, obtaining a 2-dimensional effective manifold at hight energy. Our result is consistent with other two approach to non perturbative quantum gravity: causal dynamical triangulation and asymptotic safety quantum gravity.

Leonardo Modesto

2008-12-11T23:59:59.000Z

159

CDT meets Horava-Lifshitz gravity  

E-Print Network [OSTI]

The theory of causal dynamical triangulations (CDT) attempts to define a nonperturbative theory of quantum gravity as a sum over space-time geometries. One of the ingredients of the CDT framework is a global time foliation, which also plays a central role in the quantum gravity theory recently formulated by Ho\\v{r}ava. We show that the phase diagram of CDT bears a striking resemblance with the generic Lifshitz phase diagram appealed to by Ho\\v{r}ava. We argue that CDT might provide a unifying nonperturbative framework for anisotropic as well as isotropic theories of quantum gravity.

J. Ambjorn; A. Gorlich; S. Jordan; J. Jurkiewicz; R. Loll

2010-04-06T23:59:59.000Z

160

Gravity Waves in a Horizontal Shear Flow. Part II: Interaction between Gravity Waves and Potential Vorticity Perturbations  

E-Print Network [OSTI]

Gravity Waves in a Horizontal Shear Flow. Part II: Interaction between Gravity Waves and Potential perturbations and propagating internal gravity waves in a horizon- tally sheared zonal flow is investigated. In the strong stratification limit, an initial vorticity perturbation weakly excites two propagating gravity

Farrell, Brian F.

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

The Branching of Graphs in 2-d Quantum Gravity  

E-Print Network [OSTI]

The branching ratio is calculated for three different models of 2d gravity, using dynamical planar phi-cubed graphs. These models are pure gravity, the D=-2 Gaussian model coupled to gravity and the single spin Ising model coupled to gravity. The ratio gives a measure of how branched the graphs dominating the partition function are. Hence it can be used to estimate the location of the branched polymer phase for the multiple Ising model coupled to 2d gravity.

M. G. Harris

1996-07-16T23:59:59.000Z

162

Antimatter-Gravity Couplings, and Lorentz Symmetry  

E-Print Network [OSTI]

Implications of possible CPT and Lorentz violation for antimatter-gravity experiments as well as other antimatter tests are considered in the context of the general field-theory-based framework of the Standard-Model Extension (SME).

Tasson, Jay D

2015-01-01T23:59:59.000Z

163

Antimatter-Gravity Couplings, and Lorentz Symmetry  

E-Print Network [OSTI]

Implications of possible CPT and Lorentz violation for antimatter-gravity experiments as well as other antimatter tests are considered in the context of the general field-theory-based framework of the Standard-Model Extension (SME).

Jay D. Tasson

2015-01-27T23:59:59.000Z

164

Test particle motion in modified gravity theories  

E-Print Network [OSTI]

We derive the equations of motion of an electrically neutral test particle for modified gravity theories in which the covariant divergence of the ordinary matter energy-momentum tensor dose not vanish (i.e. $\

Mahmood Roshan

2013-02-05T23:59:59.000Z

165

Probes of strong-field gravity  

E-Print Network [OSTI]

In this thesis, I investigate several ways to probe gravity in the strong-field regime. These investigations focus on observables from the gravitational dynamics, i.e. when time derivatives are large: thus I focus on sources ...

Stein, Leo Chaim

2012-01-01T23:59:59.000Z

166

Earthlings : humanity's essential relationship with gravity  

E-Print Network [OSTI]

A realm of serious scientific questions about gravity's role in biology is being researched in labs around the world, from NASA's Dryden Research Laboratories in the Mohave Desert, to Japan's Radioisotope Center at the ...

Vargas Medina, Iris Mnica

2009-01-01T23:59:59.000Z

167

Bounds on quantum communication via Newtonian gravity  

E-Print Network [OSTI]

Newtonian gravity yields specific observable consequences, the most striking of which is the emergence of a $1/r^2$ force. In so far as communication can arise via such interactions between distant particles, we can ask what would be expected for a theory of gravity that only allows classical communication. Many heuristic suggestions for gravity-induced decoherence have this restriction implicitly or explicitly in their construction. Here we show that communication via a $1/r^2$ force has a minimum noise induced in the system when the communication cannot convey quantum information, in a continuous time analogue to Bell's inequalities. Our derived noise bounds provide tight constraints from current experimental results on any theory of gravity that does not allow quantum communication.

D. Kafri; G. J. Milburn; J. M. Taylor

2014-10-08T23:59:59.000Z

168

Energy conditions in f(R)-gravity  

E-Print Network [OSTI]

In order to shed some light on the current discussion about f(R)-gravity theories we derive and discuss the bounds imposed by the energy conditions on a general f(R) functional form. The null and strong energy conditions in this framework are derived from the Raychaudhuri's equation along with the requirement that gravity is attractive, whereas the weak and dominant energy conditions are stated from a comparison with the energy conditions that can be obtained in a direct approach via an effective energy-momentum tensor for f(R)-gravity. As a concrete application of the energy conditions to locally homogeneous and isotropic f(R)-cosmology, the recent estimated values of the deceleration and jerk parameters are used to examine the bounds from the weak energy condition on the parameters of two families of f(R)-gravity theories.

J. Santos; J. S. Alcaniz; M. J. Reboucas; F. C. Carvalho

2007-09-06T23:59:59.000Z

169

Gravity Recovery and Interior Laboratory (GRAIL) Launch  

E-Print Network [OSTI]

Gravity Recovery and Interior Laboratory (GRAIL) Launch Press Kit/AUGUst 2011 #12;http of its four channels to AC-3, making each channel's secondary audio MPEG 1 Layer II. For digital downlink

170

The Shape of a Gravity Finger  

SciTech Connect (OSTI)

A new gravity finger model was proposed in this report in the absence of interfacial tension but in the presence of gravities. This model considered differences in density and viscosity of the two fluids. Thus, it was able to represent both stable and unstable displacements, and the finger development along either the upper or the bottom walls of a channel. This solution recovers the Saffman - Taylar solution if gravity is neglected. The results of the solution are very similar to the solutions proposed by Brener et al. for the gravity number up to 10. The solution provided in this work only has one free parameter while the solution of Brener et al. has three.

Zhan, Lang; Yortsos, Yanis

2000-09-11T23:59:59.000Z

171

Relativistic Gravity With a Dynamical Preferred Frame  

E-Print Network [OSTI]

While general relativity possesses local Lorentz invariance, both canonical quantum gravity and string theory suggest that Lorentz invariance may be broken at high energies. Broken Lorentz invariance has also been postulated as an explanation for astrophysical anomalies such as the missing GZK cutoff. Therefore, we seek an effective field theory description of gravity where Lorentz invariance is broken. We will construct a candidate theory and then briefly discuss some of the implications.

David Mattingly; Ted Jacobson

2001-12-07T23:59:59.000Z

172

Testing Modified Gravity with Gravitational Wave Astronomy  

E-Print Network [OSTI]

The emergent area of gravitational wave astronomy promises to provide revolutionary discoveries in the areas of astrophysics, cosmology, and fundamental physics. One of the most exciting possibilities is to use gravitational-wave observations to test alternative theories of gravity. In this contribution we describe how to use observations of extreme-mass-ratio inspirals by the future Laser Interferometer Space Antenna to test a particular class of theories: Chern-Simons modified gravity.

Carlos F. Sopuerta; Nicolas Yunes

2010-10-01T23:59:59.000Z

173

2D dilaton gravity made compact  

E-Print Network [OSTI]

We show that the equations of motion of two-dimensional dilaton gravity conformally coupled to a scalar field can be reduced to a single non-linear second-order partial differential equation when the coordinates are chosen to coincide with the two scalar fields, the matter field $f$ and the dilaton $\\phi$, which are present in the theory. This result may help solve and understand two- and higher-dimensional classical and quantum gravity.

M. Navarro

1998-05-18T23:59:59.000Z

174

The shape dynamics description of gravity  

E-Print Network [OSTI]

Classical gravity can be described as a relational dynamical system without ever appealing to spacetime or its geometry. This description is the so-called shape dynamics description of gravity. The existence of relational first principles from which the shape dynamics description of gravity can be derived is a motivation to consider shape dynamics (rather than GR) as the fundamental description of gravity. Adopting this point of view leads to the question: What is the role of spacetime in the shape dynamics description of gravity? This question contains many aspects: Compatibility of shape dynamics with the description of gravity in terms of spacetime geometry, the role of local Minkowski space, universality of spacetime geometry and the nature of quantum particles, which can no longer be assumed to be irreducible representations of the Poincare group. In this contribution I derive effective spacetime structures by considering how matter fluctuations evolve along with shape dynamics. This evolution reveals an "experienced spacetime geometry." This leads (in an idealized approximation) to local Minkowski space and causal relations. The small scale structure of the emergent geometric picture depends on the specific probes used to experience spacetime, which limits the applicability of effective spacetime to describe shape dynamics. I conclude with discussing the nature of quantum fluctuations (particles) in shape dynamics and how local Minkowski spacetime emerges from the evolution of quantum particles.

Tim Koslowski

2015-01-13T23:59:59.000Z

175

Magnetic investigations  

SciTech Connect (OSTI)

Air and ground magnetic anomalies in the Climax stock area of the NTS help define the gross configuration of the stock and detailed configuration of magnetized rocks at the Boundary and Tippinip faults that border the stock. Magnetizations of geologic units were evaluated by measurements of magnetic properties of drill core, minimum estimates of magnetizations from ground magnetic anomalies for near surface rocks, and comparisons of measured anomalies with anomalies computed by a three-dimensional forward program. Alluvial deposits and most sedimentary rocks are nonmagnetic, but drill core measurements reveal large and irregular changes in magnetization for some quartzites and marbles. The magnetizations of quartz monzonite and granodiorite near the stock surface are weak, about 0.15 A/m, and increase at a rate of 0.00196 A/m/m to 1.55 A/m, at depths greater than 700 m (2300 ft). The volcanic rocks of the area are weakly magnetized. Aeromagnetic anomalies 850 m (2800 ft) above the stock are explained by a model consisting of five vertical prisms. Prisms 1, 2, and 3 represent the near surface outline of the stock, prism 4 is one of the models developed by Whitehill (1973), and prism 5 is modified from the model developed by Allingham and Zietz (1962). Most of the anomaly comes from unsampled and strongly-magnetized deep sources that could be either granite or metamorphosed sedimentary rocks. 48 refs., 23 figs., 3 tabs.

Bath, G.D.; Jahren, C.E.; Rosenbaum, J.G. [Geological Survey, Denver, CO (USA); Baldwin, M.J. [Fenix and Scisson, Inc., Mercury, NV (USA)

1983-12-31T23:59:59.000Z

176

Quantum gravity and inventory accumulation  

E-Print Network [OSTI]

We begin by studying inventory accumulation at a LIFO (last-in-first-out) retailer with two products. In the simplest version, the following occur with equal probability at each time step: first product ordered, first product produced, second product ordered, second product produced. The inventory thus evolves as a simple random walk on Z^2. In more interesting versions, a p fraction of customers orders the "freshest available" product regardless of type. We show that the corresponding random walks scale to Brownian motions with diffusion matrices depending on p. We then turn our attention to the critical Fortuin-Kastelyn random planar map model, which gives, for each q>0, a probability measure on random (discretized) two-dimensional surfaces decorated by loops, related to the q-state Potts model. A longstanding open problem is to show that as the discretization gets finer, the surfaces converge in law to a limiting (loop-decorated) random surface. The limit is expected to be a Liouville quantum gravity surface decorated by a conformal loop ensemble, with parameters depending on q. Thanks to a bijection between decorated planar maps and inventory trajectories (closely related to bijections of Bernardi and Mullin), our results about the latter imply convergence of the former in a particular topology. A phase transition occurs at p = 1/2, q=4.

Scott Sheffield

2011-08-10T23:59:59.000Z

177

Universality of Gravity from Entanglement  

E-Print Network [OSTI]

The entanglement "first law" in conformal field theories relates the entanglement entropy for a ball-shaped region to an integral over the same region involving the expectation value of the CFT stress-energy tensor, for infinitesimal perturbations to the CFT vacuum state. In recent work, this was exploited at leading order in $N$ in the context of large N holographic CFTs to show that any geometry dual to a perturbed CFT state must satisfy Einstein's equations linearized about pure AdS. In this note, we investigate the implications of the leading 1/N correction to the exact CFT result. We show that these corrections give rise to the source term for the gravitational equations: for semiclassical bulk states, the expectation value of the bulk stress-energy tensor appears as a source in the linearized equations. In particular, the CFT first law leads to Newton's Law of gravitation and the fact that all sources of stress-energy source the gravitational field. In our derivation, this universality of gravity comes directly from the universality of entanglement (the fact that all degrees of freedom in a subsystem contribute to entanglement entropy).

Brian Swingle; Mark Van Raamsdonk

2014-05-12T23:59:59.000Z

178

Strange Magnetism  

E-Print Network [OSTI]

We present an analytic and parameter-free expression for the momentum dependence of the strange magnetic form factor of the nucleon and its corresponding radius which has been derived in Heavy Baryon Chiral Perturbation Theory. We also discuss a model-independent relation between the isoscalar magnetic and the strange magnetic form factors of the nucleon based on chiral symmetry and SU(3) only. These limites are used to derive bounds on the strange magnetic moment of the proton from the recent measurement by the SAMPLE collaboration.

Thomas R. Hemmert; Ulf-G. Meissner; Sven Steininger

1998-11-09T23:59:59.000Z

179

Magnetic Field Safety Magnetic Field Safety  

E-Print Network [OSTI]

Magnetic Field Safety Training #12;Magnetic Field Safety Strong Magnetic Fields exist around energized magnets. High magnetic fields alone are a recognized hazard only for personnel with certain medical conditions such as pacemakers, magnetic implants, or embedded shrapnel. In addition, high magnetic

McQuade, D. Tyler

180

Introduction to Modified Gravity: From the Cosmic Speedup Problem to Quantum Gravity Phenomenology  

E-Print Network [OSTI]

These notes represent a summary of the introductory part of a course on modified gravity delivered at several Spanish Universities (Granada, Valencia, and Valladolid), at the University of Wisconsin-Milwaukee (WI, USA), and at the Karl-Franzens Universitaet (Graz, Austria) during the period 2008-2011. We begin with a discussion of the classical Newtonian framework and how special relativity boosted the interest on new theories of gravity. Then we focus on Nordstrom's scalar theories of gravity and their influence on Einstein's theory of general relativity. We comment on the meaning of the Einstein equivalence principle and its implications for the construction of alternative theories of gravity. We present the cosmic speedup problem and how $f(R)$ theories can be constrained attending to their weak-field behavior. We conclude by showing that Palatini f(R) and f(R,Q) theories can be used to address different aspects of quantum gravity phenomenology and singularity problems.

Gonzalo J. Olmo

2011-12-09T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Gravity and Anti-gravity of Fermions: the Unification of Dark Matter and Dark Energy  

E-Print Network [OSTI]

Massive gravity with second and fourth derivatives is shown to give both attractive and repulsive gravity between fermions. In contrast to the attractive gravity correlated with energy-momentum tensor, the repulsive gravity is proportional to the graviton mass. Therefore, weakly interacting fermions with energy smaller than the graviton mass are both dark matter and dark energy: Their overall gravity is attractive with normal matter but repulsive among themselves. Detailed analyses reveal that this unified dark scenario can properly account for the observed dark matter/energy phenomena: galaxy rotation curves, transition from early cosmic deceleration to recent acceleration; and naturally overcome other dark scenarios' difficulties: the substructure and cuspy core problems, the difference of dark halo distributions in galaxies and clusters, and the cosmic coincidence.

Chen, X S

2005-01-01T23:59:59.000Z

182

A Kinetic Theory Approach to Quantum Gravity  

E-Print Network [OSTI]

We describe a kinetic theory approach to quantum gravity -- by which we mean a theory of the microscopic structure of spacetime, not a theory obtained by quantizing general relativity. A figurative conception of this program is like building a ladder with two knotted poles: quantum matter field on the right and spacetime on the left. Each rung connecting the corresponding knots represent a distinct level of structure. The lowest rung is hydrodynamics and general relativity; the next rung is semiclassical gravity, with the expectation value of quantum fields acting as source in the semiclassical Einstein equation. We recall how ideas from the statistical mechanics of interacting quantum fields helped us identify the existence of noise in the matter field and its effect on metric fluctuations, leading to the establishment of the third rung: stochastic gravity, described by the Einstein-Langevin equation. Our pathway from stochastic to quantum gravity is via the correlation hierarchy of noise and induced metric fluctuations. Three essential tasks beckon: 1) Deduce the correlations of metric fluctuations from correlation noise in the matter field; 2) Reconstituting quantum coherence -- this is the reverse of decoherence -- from these correlation functions 3) Use the Boltzmann-Langevin equations to identify distinct collective variables depicting recognizable metastable structures in the kinetic and hydrodynamic regimes of quantum matter fields and how they demand of their corresponding spacetime counterparts. This will give us a hierarchy of generalized stochastic equations -- call them the Boltzmann-Einstein hierarchy of quantum gravity -- for each level of spacetime structure, from the macroscopic (general relativity) through the mesoscopic (stochastic gravity) to the microscopic (quantum gravity).

B. L. Hu

2002-04-22T23:59:59.000Z

183

Newton-Cartan Gravity in Noninertial Reference Frames  

E-Print Network [OSTI]

We study properties of Newton-Cartan gravity under transformations into all noninertial, nonrelativistic reference frames. The set of these transformations has the structure of an infinite dimensional Lie group, called the Galilean line group, which contains as a subgroup the Galilei group. We show that the fictitious forces of noninertial reference frames are naturally encoded in the Cartan connection transformed under the Galilean line group. These noninertial forces, which are coordinate effects, do not contribute to the Ricci tensor which describes the curvature of Newtonian spacetime. We show that only the $00$-component of the Ricci tensor is non-zero and equal to ($4\\pi$ times) the matter density in any inertial or noninetial reference frame and that it leads to what may be called Newtonian ADM mass. While the Ricci field equation and Gauss law are both fulfilled by the same physical matter density in inertial and linearly accelerating reference frames, there appears a discrepancy between the two in rotating reference frames in that Gauss law holds for an effective mass density that differs from the physical matter density. This effective density has its origin in the simulated magnetic field that appears in rotating frames, highlighting a rather striking difference between linearly and rotationally accelerating reference frames. We further show that the dynamical equations that govern the simulated gravitational and magnetic fields have the same form as Maxwell's equations, a surprising conclusion given that these equations are well-known to obey special relativity (and $U(1)$-gauge symmetry), rather than Galilean symmetry.

Leo Rodriguez; James St. Germaine-Fuller; Sujeev Wickramasekara

2014-12-26T23:59:59.000Z

184

Magnetic shielding  

DOE Patents [OSTI]

A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines.

Kerns, J.A.; Stone, R.R.; Fabyan, J.

1985-02-12T23:59:59.000Z

185

Magnetic nanotubes  

DOE Patents [OSTI]

A magnetic nanotube includes bacterial magnetic nanocrystals contacted onto a nanotube which absorbs the nanocrystals. The nanocrystals are contacted on at least one surface of the nanotube. A method of fabricating a magnetic nanotube includes synthesizing the bacterial magnetic nanocrystals, which have an outer layer of proteins. A nanotube provided is capable of absorbing the nanocrystals and contacting the nanotube with the nanocrystals. The nanotube is preferably a peptide bolaamphiphile. A nanotube solution and a nanocrystal solution including a buffer and a concentration of nanocrystals are mixed. The concentration of nanocrystals is optimized, resulting in a nanocrystal to nanotube ratio for which bacterial magnetic nanocrystals are immobilized on at least one surface of the nanotubes. The ratio controls whether the nanocrystals bind only to the interior or to the exterior surfaces of the nanotubes. Uses include cell manipulation and separation, biological assay, enzyme recovery, and biosensors.

Matsui, Hiroshi (Glen Rock, NJ); Matsunaga, Tadashi (Tokyo, JP)

2010-11-16T23:59:59.000Z

186

Holographic Superconductors in Quasi-topological Gravity  

E-Print Network [OSTI]

In this paper we study (3+1) dimensional holographic superconductors in quasi-topological gravity which is recently proposed by R. Myers {\\it et.al.}. Through both analytical and numerical analysis, we find in general the condensation becomes harder with the increase of coupling parameters of higher curvature terms. In particular, comparing with those in ordinary Gauss-Bonnet gravity, we find that positive cubic corrections in quasi-topological gravity suppress the condensation while negative cubic terms make it easier. We also calculate the conductivity numerically for various coupling parameters. It turns out that the universal relation of $\\omega_g/T_c\\simeq 8$ is unstable and this ratio becomes larger with the increase of the coupling parameters. A brief discussion on the condensation from the CFT side is also presented.

Xiao-Mei Kuang; Wei-Jia Li; Yi Ling

2010-12-05T23:59:59.000Z

187

Solar system constraints on alternative gravity theories  

E-Print Network [OSTI]

The perihelion precession of planetary orbits and the bending angle of null geodesics are estimated for different gravity theories in string-inspired models. It is shown that, for dilaton coupled gravity, the leading order measure in the angle of bending of light comes purely from vacuum expectation value of the dilaton field which may be interpreted as an indicator of a dominant stringy effect over the curvature effect. We arrive at similar results for spherically symmetric solution in quadratic gravity. We also present the perihelion shift and bending of light in the Einstein-Maxwell-Gauss-Bonnet theory with special reference to the Casimir effect and Damour-Polyakov mechanism. Numerical bounds to different coupling parameters in these models are estimated.

Sumanta Chakraborty; Soumitra Sengupta

2014-01-14T23:59:59.000Z

188

Nonlinear cosmological power spectra in Einstein's gravity  

E-Print Network [OSTI]

Is Newton's gravity sufficient to handle the weakly nonlinear evolution stages of the cosmic large-scale structures? Here we resolve the issue by analytically deriving the density and velocity power spectra to the second order in the context of Einstein's gravity. The recently found pure general relativistic corrections appearing in the third-order perturbation contribute to power spectra to the second order. In this work the complete density and velocity power spectra to the second order are derived. The power transfers among different scales in the density power spectrum are estimated in the context of Einstein's gravity. The relativistic corrections in the density power spectrum are estimated to be smaller than the Newtonian one to the second order, but these could be larger than higher-order nonlinear Newtonian terms.

Hyerim Noh; Jai-chan Hwang

2008-05-13T23:59:59.000Z

189

Stable, Accelerating Universes in Modified Gravity  

E-Print Network [OSTI]

Modifications to gravity that add additional functions of the Ricci curvature to the Einstein-Hilbert action -- collectively known as $f(R)$ theories -- have been studied in great detail. When considered as complete theories of gravity they can generate non-perturbative deviations from the general relativistic predictions in the solar system, and the simplest models show instabilites on cosmological scales. Here we show that it is possible to treat $f(R)=R\\pm\\mu^4/R$ gravity in a perturbative fashion such that it shows no instabilities on cosmological scales and, in the solar system, is consistent with measurements of the PPN parameters. We show that such a theory produces a spatially flat, accelerating universe, even in the absence of dark energy and when the matter density is too small to close the universe in the general relativistic case.

Simon DeDeo; Dimitrios Psaltis

2008-11-13T23:59:59.000Z

190

Gauge theory of gravity and supergravity  

SciTech Connect (OSTI)

We present a formulation of gravity in terms of a theory based on complex SU(2) gauge fields with a general coordinate invariant action functional quadratic in the field strength. Self-duality or anti-self-duality of the field strength emerges as a constraint from the equations of motion of this theory. This in turn leads to Einstein gravity equations for a dilaton and an axion conformally coupled to gravity for the self-dual constraint. The analysis has also been extended to N=1 and 2 super Yang-Mills theory of complex SU(2) gauge fields. This leads to, besides other equations of motion, self-duality/anti-self-duality of generalized supercovariant field strengths. The self-dual case is then shown to yield as its solutions N=1, 2 supergravity equations, respectively.

Kaul, Romesh K. [Institute of Mathematical Sciences, Chennai 600 113 (India)

2006-03-15T23:59:59.000Z

191

Emergence in Holographic Scenarios for Gravity  

E-Print Network [OSTI]

'Holographic' relations between theories have become an important theme in quantum gravity research. These relations entail that a theory without gravity is equivalent to a gravitational theory with an extra spatial dimension. The idea of holography was first proposed in 1993 by Gerard 't Hooft on the basis of his studies of evaporating black holes. Soon afterwards the holographic 'AdS/CFT' duality was introduced, which since has been intensively studied in the string theory community and beyond. Recently, Erik Verlinde has proposed that even Newton's law of gravitation can be related holographically to the 'thermodynamics of information' on screens. We discuss these scenarios, with special attention to the status of the holographic relation in them and to the question of whether they make gravity and spacetime emergent. We conclude that only Verlinde's scheme straightfowardly instantiates emergence. However, assuming a non-standard interpretation of AdS/CFT may create room for the emergence of spacetime and ...

Dieks, Dennis; de Haro, Sebastian

2015-01-01T23:59:59.000Z

192

Passive magnetic bearing element with minimal power losses  

DOE Patents [OSTI]

Systems employing passive magnetic bearing elements having minimal power losses are provided. Improved stabilizing elements are shown, employing periodic magnet arrays and inductively loaded circuits, but with improved characteristics compared to the elements disclosed in US Patent No. 5,495,221 entitled ``Dynamically Stable Magnetic Suspension/Bearing System.`` The improvements relate to increasing the magnitude of the force derivative, while at the same time reducing the power dissipated during the normal operation of the bearing system, to provide a passive bearing system that has virtually no losses under equilibrium conditions, that is, when the supported system is not subject to any accelerations except those of gravity. 8 figs.

Post, R.F.

1998-12-08T23:59:59.000Z

193

Passive magnetic bearing element with minimal power losses  

DOE Patents [OSTI]

Systems employing passive magnetic bearing elements having minimal power losses are provided. Improved stabilizing elements are shown, employing periodic magnet arrays and inductively loaded circuits, but with improved characteristics compared to the elements disclosed in U.S. Patent No. 5,495,221 entitled "Dynamically Stable Magnetic Suspension/Bearing System." The improvements relate to increasing the magnitude of the force derivative, while at the same time reducing the power dissipated during the normal operation of the bearing system, to provide a passive bearing system that has virtually no losses under equilibrium conditions, that is, when the supported system is not subject to any accelerations except those of gravity.

Post, Richard F. (Walnut Creek, CA)

1998-01-01T23:59:59.000Z

194

Standard Model and Gravity from Spinors  

E-Print Network [OSTI]

We propose to unify the Gravity and Standard Model gauge groups by using algebraic spinors of the standard four-dimensional Clifford algebra, in left-right symmetric fashion. This generates exactly a Standard Model family of fermions, and a Pati-Salam unification group emerges, at the Planck scale, where (chiral) self-dual gravity decouples. As a remnant of the unification, isospin-triplets spin-two particles may naturally appear at the weak scale, providing a striking signal at the LHC.

F. Nesti

2008-06-20T23:59:59.000Z

195

Differential geometry, Palatini gravity and reduction  

SciTech Connect (OSTI)

The present article deals with a formulation of the so called (vacuum) Palatini gravity as a general variational principle. In order to accomplish this goal, some geometrical tools related to the geometry of the bundle of connections of the frame bundle LM are used. A generalization of Lagrange-Poincar reduction scheme to these types of variational problems allows us to relate it with the Einstein-Hilbert variational problem. Relations with some other variational problems for gravity found in the literature are discussed.

Capriotti, S., E-mail: santiago.capriotti@uns.edu.ar [Departamento de Matemtica, Universidad Nacional del Sur, 8000 Baha Blanca (Argentina)

2014-01-15T23:59:59.000Z

196

Geodesic distances in Liouville quantum gravity  

E-Print Network [OSTI]

In order to study the quantum geometry of random surfaces in Liouville gravity, we propose a definition of geodesic distance associated to a Gaussian free field on a regular lattice. This geodesic distance is used to numerically determine the Hausdorff dimension associated to shortest cycles of 2d quantum gravity on the torus coupled to conformal matter fields, showing agreement with a conjectured formula by Y. Watabiki. Finally, the numerical tools are put to test by quantitatively comparing the distribution of lengths of shortest cycles to the corresponding distribution in large random triangulations.

Jan Ambjorn; Timothy Budd

2014-11-12T23:59:59.000Z

197

New Spin Foam Models of Quantum Gravity  

E-Print Network [OSTI]

We give a brief and a critical review of the Barret-Crane spin foam models of quantum gravity. Then we describe two new spin foam models which are obtained by direct quantization of General Relativity and do not have some of the drawbacks of the Barret-Crane models. These are the model of spin foam invariants for the embedded spin networks in loop quantum gravity and the spin foam model based on the integration of the tetrads in the path integral for the Palatini action.

A. Mikovic

2005-01-28T23:59:59.000Z

198

Holographic superconductors from the massive gravity  

E-Print Network [OSTI]

A holographic superconductor is constructed in the background of a massive gravity theory. In the normal state without condensation, the conductivity exhibits a Drude peak that approaches a delta function in the massless gravity limit as studied by David Vegh. In the superconducting state, besides the infinite DC conductivity, the AC conductivity has Drude behavior at low frequency followed by a power law-fall. These results are in agreement with that found earlier by Horowitz and Santos, who studied a holographic superconductor with an implicit periodic potential beyond the probe limit. The results also agree with measurements on some cuprates.

Hua Bi Zeng; Jian-Pin Wu

2014-09-24T23:59:59.000Z

199

Testing a Dilaton Gravity Model using Nucleosynthesis  

E-Print Network [OSTI]

Big Bang Nucleosynthesis (BBN) offers one of the most strict evidences for the Lambda-CDM cosmology at present, as well as the Cosmic Microwave Background (CMB) radiation. In this work, our main aim is to present the outcomes of our calculations related to primordial abundances of light elements, in the context of higher dimensional steady-state universe model in the dilaton gravity. Our results show that abundances of light elements (primordial D, 3He, 4He, T, 7Li) are significantly different for some cases, and a comparison is given between a particular dilaton gravity model and Lambda-CDM in the light of the astrophysical observations.

Sibel Boran; Emre Onur Kahya

2014-09-05T23:59:59.000Z

200

Inertia and gravitation in teleparallel gravity  

E-Print Network [OSTI]

Using the fact that teleparallel gravity allows a separation between gravitation and inertia, explicit expressions for the gravitational and the inertial energy-momentum densities are obtained. It is shown that, like all other fields of nature, gravitation alone has a tensorial energy-momentum density which in a general frame is conserved in the covariant sense. Together with the inertial energy-momentum density, they form a pseudotensor which is conserved in the ordinary sense. An analysis of the role played by the gravitational and the inertial densities in the computation of the total energy and momentum of gravity is presented.

R. Aldrovandi; Tiago Gribl Lucas; J. G. Pereira

2009-08-14T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Confirmation of the Secondary Constraint and Absence of Ghost in Massive Gravity and Bimetric Gravity  

E-Print Network [OSTI]

In massive gravity and in bimetric theories of gravity, two constraints are needed to eliminate the two phase-space degrees of freedom of the Boulware-Deser ghost. For recently proposed non-linear theories, a Hamiltonian constraint has been shown to exist and an associated secondary constraint was argued to arise as well. In this paper we explicitly demonstrate the existence of the secondary constraint. Thus the Boulware-Deser ghost is completely absent from these non-linear massive gravity theories and from the corresponding bimetric theories.

S. F. Hassan; Rachel A. Rosen

2011-11-08T23:59:59.000Z

202

Exact solutions of three dimensional black holes: Einstein gravity vs F(R) gravity  

E-Print Network [OSTI]

In this paper, we consider Einstein gravity in the presence of a class of nonlinear electrodynamics, called power Maxwell invariant (PMI). We take into account $(2+1)$-dimensional spacetime in Einstein-PMI gravity and obtain its black hole solutions. Then, we regard pure $F(R)$ gravity as well as $F(R)$-conformally invariant Maxwell theory to obtain exact solutions of the field equations with black hole interpretation. Finally, we investigate the conserved and thermodynamic quantities and discuss about the first law of thermodynamics for the mentioned gravitational models.

S. H. Hendi; B. Eslam Panah; R. Saffari

2014-10-28T23:59:59.000Z

203

One Loop Beta Functions in Topologically Massive Gravity  

E-Print Network [OSTI]

We calculate the running of the three coupling constants in cosmological, topologically massive 3d gravity. We find that \

R. Percacci; E. Sezgin

2010-02-15T23:59:59.000Z

204

Komar Integrals in Higher (and Lower) Derivative Gravity  

E-Print Network [OSTI]

The Komar integral relation of Einstein gravity is generalized to Lovelock theories of gravity. This includes, in particular, a new boundary integral for the Komar mass in Einstein gravity with a nonzero cosmological constant, which has a finite result for asymptotically AdS black holes, without the need for an infinite background subtraction. Explicit computations of the Komar mass are given for black holes in pure Lovelock gravities of all orders and in general Gauss-Bonnet theories.

David Kastor

2008-04-24T23:59:59.000Z

205

Microporous Magnets  

SciTech Connect (OSTI)

Combining porosity and magnetic ordering in a single material presents a significant challenge since magnetic exchange generally requires short bridges between the spin carriers, whereas porosity usually relies on the use of long diamagnetic connecting ligands. Despite this apparent incompatibility, notable successes have been achieved of late in generating truly microporous solids with high magnetic ordering temperatures. In this critical review, we give an overview of this emerging class of multifunctional materials, with particular emphasis on synthetic strategies and possible routes to new materials with improved properties (149 references).

Dechambenoit, Pierre; Long, Jeffrey R.

2011-01-01T23:59:59.000Z

206

Localisation of Galilean symmetry and Horava-Lifshitz gravity  

E-Print Network [OSTI]

We derive the projectable version of Horava-Lifshitz gravity from the localisation of the Galilean symmetry. Specifically we provide a dynamical realisation of the metric that reproduces the transformations of the physical variables - lapse, shift and spatial component of the metric. Also, the measure defining the action is reproduced. The connection of Newton's gravity with Horava-Lifshitz gravity is elucidated.

Banerjee, Rabin

2015-01-01T23:59:59.000Z

207

Gravity Waves in Shear and Implications for Organized Convection  

E-Print Network [OSTI]

Gravity Waves in Shear and Implications for Organized Convection Samuel N. Stechmann Department, Los Angeles, CA 90095­1555. E-mail: stechmann@math.ucla.edu #12;ABSTRACT It is known that gravity, the gravity waves can create a more favorable environment on one side of preexisting convection than the other

Stechmann, Samuel N.

208

Minimal Liouville Gravity on the Torus via Matrix Models  

E-Print Network [OSTI]

In this paper we use recent results on resonance relations between the matrix models and the minimal Liouville gravity to compute the torus correlation numbers in (3,p) minimal Liouville gravity. Namely, we calculate the torus generating partition function of the (3,p) matrix models and use it to obtain the one- and two-point correlation numbers in the minimal Liouville gravity.

Lev Spodyneiko

2014-07-14T23:59:59.000Z

209

Tomo-gravity How to ComputeHow to Compute  

E-Print Network [OSTI]

Tomo-gravity How to ComputeHow to Compute Accurate Traffic Matrices forAccurate Traffic MatricesStanford Shannon LabShannon Lab #12;Tomo-gravity Want to know demands from source to destination ProblemProblem Have link traffic measurements (from SNMP) A B C #12;Tomo-gravity Example App: reliability analysis

Roughan, Matthew

210

INTERNAL GRAVITY WAVES FROM ATMOSPHERIC JETS AND FRONTS  

E-Print Network [OSTI]

INTERNAL GRAVITY WAVES FROM ATMOSPHERIC JETS AND FRONTS Riwal Plougonven1 and Fuqing Zhang2 consistently highlighted jet exit regions as a favored locus for intense gravity waves, the mechanisms need for improving parameterizations of nonorographic gravity waves in climate models that include

Plougonven, Riwal

211

Recent Results Regarding A#ne Quantum Gravity  

E-Print Network [OSTI]

Recent Results Regarding A#ne Quantum Gravity John R. Klauder Department of Physics and Department perturbation analysis. After a brief review of both the scalar field story and the a#ne quantum gravity program implies that a#ne quantum gravity is not plagued by divergences that arise in a standard perturbation

212

Conformal gravity from the AdS/CFT mechanism  

SciTech Connect (OSTI)

We explicitly calculate the induced gravity theory at the boundary of an asymptotically anti-de Sitter five dimensional Einstein gravity. We also display the action that encodes the dynamics of radial diffeomorphisms. It is found that the induced theory is a four dimensional conformal gravity plus a scalar field. This calculation confirms some previous results found by a different approach.

Aros, Rodrigo; Romo, Mauricio; Zamorano, Nelson [Departamento de Ciencias Fisicas, Universidad Andres Bello, Av. Republica 252, Santiago (Chile); Departamento de Fisica, Facultad de Ciencias Fisicas y Matematicas, Universidad de Chile, Avda Blanco Encalada 2008, Santiago (Chile)

2007-03-15T23:59:59.000Z

213

Quantum Gravity in Three Dimensions from Higher-Spin Holography  

E-Print Network [OSTI]

Higher Spin Anti-de Sitter Gravity, JHEP 1012, 007 (2010)gravity in three dimensions from the per- spective of higher-spin holography in anti-gravity in three dimen- sions in the framework of higher-spin holography in anti-

Tan, Hai Siong

2013-01-01T23:59:59.000Z

214

Observing ocean heat content using satellite gravity and altimetry  

E-Print Network [OSTI]

: ocean heat content, altimetry, satellite gravity, steric height, remote sensing Citation: Jayne, S. RObserving ocean heat content using satellite gravity and altimetry Steven R. Jayne1,2 and John M with satellite measurements of the Earth's time-varying gravity to give improved estimates of the ocean's heat

Jayne, Steven

215

HoravaLifshitz gravity Victoria University of Wellington  

E-Print Network [OSTI]

Abstract Horava­Lifshitz gravity Victoria University of Wellington Te Whare W¯ananga o te ¯Upoko o Vancouver Tuesday 25 August 2009 Matt Visser Who's afraid of Lorentz symmetry breaking? #12;Abstract Horava­Lifshitz gravity Horava­Lifshitz gravity: As of 23 August 2009 Spires reports that this topic has generated: 3

Visser, Matt

216

Low dimensional magnetism  

E-Print Network [OSTI]

Magnetism in Ultracold Gases 4 Magnetic phase diagram of aMagnetism . . . . . . . . . . . .1.3 Magnetism in condensedIntroduction 1 Brief introduction to magnetism 1.1 Classic

Kjall, Jonas Alexander

2012-01-01T23:59:59.000Z

217

Electric-Magnetic Duality and Topological Insulators  

SciTech Connect (OSTI)

We work out the action of the SL(2,Z) electric-magnetic duality group for an insulator with a nontrivial permittivity, permeability, and theta angle. This theory has recently been proposed to be the correct low-energy effective action for topological insulators. As applications, we give manifestly SL(2,Z) covariant expressions for the Faraday rotation at orthogonal incidence at the interface of two such materials, as well as for the induced magnetic and electric charges, slightly clarifying the meaning of expressions previously derived in the literature. We also use electric-magnetic duality to find a gravitational dual for a strongly coupled version of this theory using the gauge/gravity correspondence.

Karch, A. [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States)

2009-10-23T23:59:59.000Z

218

The Mars Gravity Biosatellite as an innovative partial gravity research platform  

E-Print Network [OSTI]

The Mars Gravity Biosatellite is an unprecedented independent spaceflight platform for gravitational biology research. With a projected first launch after 2010, the low Earth orbit satellite will support a cohort of fifteen ...

Fulford-Jones, Thaddeus R. F

2008-01-01T23:59:59.000Z

219

Controlling Magnetism at the Nanoscale  

E-Print Network [OSTI]

Manipulation of Magnetism - External148 Conclusion A The Magnetism Cheat Sheet A.1 Magnetic157 A.2 Magnetism Unit Conversion

Wong, Jared

2012-01-01T23:59:59.000Z

220

Schwarzschild solution in extended teleparallel gravity  

E-Print Network [OSTI]

Tetrad field, with two unknown functions of radial coordinate and an angle $\\Phi$ which is the polar angle $\\phi$ times a function of the redial coordinate, is applied to the field equation of modified theory of gravity. Exact vacuum solution is derived whose scalar torsion, $T ={T^\\alpha}_{\\mu \

G. G. L. Nashed

2015-01-05T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Explicit versus Spontaneous Diffeomorphism Breaking in Gravity  

E-Print Network [OSTI]

Gravitational theories with fixed background fields break local Lorentz and diffeomorphism invariance either explicitly or spontaneously. In the case of explicit breaking it is known that conflicts can arise between the dynamics and geometrical constraints, while spontaneous breaking evades this problem. It is for this reason that in the gravity sector of the Standard-Model Extension (SME) it is assumed that the background fields (SME coefficients) originate from spontaneous symmetry breaking. However, in other examples, such as Chern-Simons gravity and massive gravity, diffeomorphism invariance is explicitly broken by the background fields, and the potential conflicts between the dynamics and geometry can be avoided in most cases. An analysis of how this occurs is given, and the conditions that are placed on the metric tensor and gravitational structure as a result of the presence of an explicit-breaking background are described. The gravity sector of the SME is then considered for the case of explicit breaking. However, it is found that a useful post-Newtonian limit is only obtained when the symmetry breaking is spontaneous.

Robert Bluhm

2015-04-02T23:59:59.000Z

222

Einstein-aether gravity: a status report  

E-Print Network [OSTI]

This paper reviews the theory, phenomenology, and observational constraints on the coupling parameters of Einstein-aether gravity, i.e. General Relativity coupled to a dynamical unit timelike vector field. A discussion of open questions concerning both phenomenology and fundamental issues is included.

Ted Jacobson

2008-03-09T23:59:59.000Z

223

MODIFIED GRAVITY SPINS UP GALACTIC HALOS  

SciTech Connect (OSTI)

We investigate the effect of modified gravity on the specific angular momentum of galactic halos by analyzing the halo catalogs at z = 0 from high-resolution N-body simulations for a f(R) gravity model that meets the solar-system constraint. It is shown that the galactic halos in the f(R) gravity model tend to acquire significantly higher specific angular momentum than those in the standard {Lambda}CDM model. The largest difference in the specific angular momentum distribution between these two models occurs for the case of isolated galactic halos with mass less than 10{sup 11} h {sup -1} M {sub Sun }, which are likely least shielded by the chameleon screening mechanism. As the specific angular momentum of galactic halos is rather insensitive to other cosmological parameters, it can in principle be an independent discriminator of modified gravity. We speculate a possibility of using the relative abundance of low surface brightness galaxies (LSBGs) as a test of general relativity given that the formation of the LSBGs occurs in fast spinning dark halos.

Lee, Jounghun [Astronomy Program, Department of Physics and Astronomy, FPRD, Seoul National University, Seoul 151-747 (Korea, Republic of)] [Astronomy Program, Department of Physics and Astronomy, FPRD, Seoul National University, Seoul 151-747 (Korea, Republic of); Zhao, Gong-Bo [National Astronomy Observatories, Chinese Academy of Science, Beijing 100012 (China)] [National Astronomy Observatories, Chinese Academy of Science, Beijing 100012 (China); Li, Baojiu [Institute of Computational Cosmology, Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)] [Institute of Computational Cosmology, Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Koyama, Kazuya, E-mail: jounghun@astro.snu.ac.kr [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom)] [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom)

2013-01-20T23:59:59.000Z

224

Black Hole Solutions in $R^2$ Gravity  

E-Print Network [OSTI]

We find static spherically symmetric solutions of scale invariant $R^2$ gravity. The latter has been shown to be equivalent to General Relativity with a positive cosmological constant and a scalar mode. Therefore, one expects that solutions of the $R^2$ theory will be identical to that of Einstein theory. Indeed, we find that the solutions of $R^2$ gravity are in one-to-one correspondence with solutions of General Relativity in the case of non-vanishing Ricci scalar. However, scalar-flat $R=0$ solutions are global minima of the $R^2$ action and they cannot in general be mapped to solutions of the Einstein theory. As we will discuss, the $R=0$ solutions arise in Einstein gravity as solutions in the tensionless, strong coupling limit $M_P\\rightarrow 0$. As a further result, there is no corresponding Birkhoff theorem and the Schwarzschild black hole is by no means unique in this framework. In fact, $R^2$ gravity has a rich structure of vacuum static spherically symmetric solutions partially uncovered here. We al...

Kehagias, Alex; Lust, Dieter; Riotto, Antonio

2015-01-01T23:59:59.000Z

225

Attraction and Repulsion in Conformal Gravity  

E-Print Network [OSTI]

We use numerical integration to solve the field equations of conformal gravity, assuming a metric that is static and spherically symmetric. Our solution is an extension of that found by Mannheim and Kazanas; it indicates, as expected, that gravitation in this model should be attractive on small scales and repulsive on large ones.

Phillips, Peter R

2015-01-01T23:59:59.000Z

226

Motion in Bimetric Type Theories of Gravity  

E-Print Network [OSTI]

The problem of motion for different test particles, charged and spinning objects of constant spinning tensor in different versions of bimetric theory of gravity is obtained by deriving their corresponding path and path deviation equations, using a modified Bazanski in presence of Riemannian geometry. This method enables us to find path and path deviation equations of different objects orbiting very strong gravitational fields.

Kahil, M E

2015-01-01T23:59:59.000Z

227

Scale invariance, unimodular gravity and dark energy  

E-Print Network [OSTI]

We demonstrate that the combination of the ideas of unimodular gravity, scale invariance, and the existence of an exactly massless dilaton leads to the evolution of the universe supported by present observations: inflation in the past, followed by the radiation and matter dominated stages and accelerated expansion at present. All mass scales in this type of theories come from one and the same source.

Mikhail Shaposhnikov; Daniel Zenhausern

2008-12-16T23:59:59.000Z

228

Ultrasonic hydrometer. [Specific gravity of electrolyte  

DOE Patents [OSTI]

The disclosed ultrasonic hydrometer determines the specific gravity (density) of the electrolyte of a wet battery, such as a lead-acid battery. The hydrometer utilizes a transducer that when excited emits an ultrasonic impulse that traverses through the electrolyte back and forth between spaced sonic surfaces. The transducer detects the returning impulse, and means measures the time t between the initial and returning impulses. Considering the distance d between the spaced sonic surfaces and the measured time t, the sonic velocity V is calculated with the equation V = 2d/t. The hydrometer also utilizes a thermocouple to measure the electrolyte temperature. A hydrometer database correlates three variable parameters including sonic velocity in and temperature and specific gravity of the electrolyte, for temperature values between 0 and 40/sup 0/C and for specific gravity values between 1.05 and 1.30. Upon knowing two parameters (the calculated sonic velocity and the measured temperature), the third parameter (specific gravity) can be uniquely found in the database. The hydrometer utilizes a microprocessor for data storage and manipulation.

Swoboda, C.A.

1982-03-09T23:59:59.000Z

229

Infrared fixed point in quantum Einstein gravity  

E-Print Network [OSTI]

We performed the renormalization group analysis of the quantum Einstein gravity in the deep infrared regime for different types of extensions of the model. It is shown that an attractive infrared point exists in the broken symmetric phase of the model. It is also shown that due to the Gaussian fixed point the IR critical exponent $\

S. Nagy; J. Krizsan; K. Sailer

2012-06-28T23:59:59.000Z

230

The diffeomorphism algebra approach to quantum gravity  

E-Print Network [OSTI]

The representation theory of non-centrally extended Lie algebras of Noether symmetries, including spacetime diffeomorphisms and reparametrizations of the observer's trajectory, has recently been developped. It naturally solves some long-standing problems in quantum gravity, e.g. the role of diffeomorphisms and the causal structure, but some new questions also arise.

T. A. Larsson

1999-09-13T23:59:59.000Z

231

Landscape versus Swampland for Higher Derivative Gravity  

E-Print Network [OSTI]

We survey recent studies of Gauss-Bonnet gravity and its dual conformal field theories, including their relation to the violation of the Kovtun-Starinets-Son viscosity bound. Via holography, we can also study properties such as microcausality and unitarity of boundary field theory duals. Such studies in turn supply constraints on bulk gravitational theories, consigning some of them to the swampland.

Sho Yaida

2009-02-10T23:59:59.000Z

232

A New Model of Nonlocal Modified Gravity  

E-Print Network [OSTI]

We consider a new modified gravity model with nonlocal term of the form $R^{-1} \\mathcal{F}(\\Box) R. $ This kind of nonlocality is motivated by investigation of applicability of a few unusual ans\\"atze to obtain some exact cosmological solutions. In particular, we find attractive and useful quadratic ansatz $\\Box R = q R^{2}.$

Ivan Dimitrijevic; Branko Dragovich; Jelena Grujic; Zoran Rakic

2014-11-18T23:59:59.000Z

233

Gravity and the Quantum: Are they Reconcilable?  

E-Print Network [OSTI]

General relativity and quantum mechanics are conflicting theories. The seeds of discord are the fundamental principles on which these theories are grounded. General relativity, on one hand, is based on the equivalence principle, whose strong version establishes the local equivalence between gravitation and inertia. Quantum mechanics, on the other hand, is fundamentally based on the uncertainty principle, which is essentially nonlocal in the sense that a particle does not follow one trajectory, but infinitely many trajectories, each one with a different probability. This difference precludes the existence of a quantum version of the strong equivalence principle, and consequently of a quantum version of general relativity. Furthermore, there are compelling experimental evidences that a quantum object in the presence of a gravitational field violates the weak equivalence principle. Now it so happens that, in addition to general relativity, gravitation has an alternative, though equivalent description, given by teleparallel gravity, a gauge theory for the translation group. In this theory torsion, instead of curvature, is assumed to represent the gravitational field. These two descriptions lead to the same classical results, but are conceptually different. In general relativity, curvature geometrizes the interaction, while torsion in teleparallel gravity acts as a force, similar to the Lorentz force of electrodynamics. Because of this peculiar property, teleparallel gravity describes the gravitational interaction without requiring any of the equivalence principles. The replacement of general relativity by teleparallel gravity may, in consequence, lead to a conceptual reconciliation of gravitation with quantum mechanics.

R. Aldrovandi; J. G. Pereira; K. H. Vu

2005-09-14T23:59:59.000Z

234

Energy definition for quadratic curvature gravities  

E-Print Network [OSTI]

A conserved current for generic quadratic curvature gravitational models is defined, and it is shown that, at the linearized level, it corresponds to the Deser-Tekin charges. An explicit expression for the charge for new massive gravity in three dimensions is given. Some implications of the linearized equations are discussed.

Ahmet Baykal

2012-12-03T23:59:59.000Z

235

Topological Black Holes in Quantum Gravity  

E-Print Network [OSTI]

We derive the black hole solutions with horizons of non-trivial topology and investigate their properties in the framework of an approach to quantum gravity being an extension of Bohm's formulation of quantum mechanics. The solutions we found tend asymptotically (for large $r$) to topological black holes. We also analyze the thermodynamics of these space-times.

J. Kowalski-Glikman; D. Nowak-Szczepaniak

2000-07-31T23:59:59.000Z

236

Approaches to Quantum Gravity, Clermont-Ferrand, Jan. 6, 2014 Fractal dimensions of 2d quantum gravity  

E-Print Network [OSTI]

Approaches to Quantum Gravity, Clermont-Ferrand, Jan. 6, 2014 Fractal dimensions of 2d quantum gravity Timothy Budd Niels Bohr Institute, Copenhagen. budd@nbi.dk, http://www.nbi.dk/~budd/ #12;Outline Introduction to 2d gravity Fractal dimensions Hausdorff dimension dh "Teichm¨uller deformation dimension" d

Sart, Remi

237

The Chern-Simons diffusion rate from higher curvature gravity  

E-Print Network [OSTI]

An important transport coefficient in the study of non-Abelian plasmas is the Chern-Simons diffusion rate, which parameterizes the rate of transition among the degenerate vacua of a gauge theory. We compute this quantity at strong coupling, via holography, using two theories of gravity with higher curvature corrections, namely Gauss-Bonnet gravity and quasi-topological gravity. We find that these corrections may either increase or decrease the result obtained from Einstein's gravity, depending on the value of the couplings. The Chern-Simons diffusion rate for Gauss-Bonnet gravity decreases as the shear viscosity over entropy ratio is increased.

Viktor Jahnke; Anderson Seigo Misobuchi; Diego Trancanelli

2014-03-13T23:59:59.000Z

238

On the z=4 Horava-Lifshitz Gravity  

E-Print Network [OSTI]

We consider z=4 Horava-Lifshitz gravity in both 3+1 and 4+1 dimensions. We find black hole solutions in the IR region for a kind of z=4 Horava-Lifshitz gravity which is inherited from the new massive gravity in three dimensions and an analog of the new massive gravity in four dimensions through the quantum inheritance principle. We analyze thermodynamic properties for the black hole solutions for z=4 Horava-Lifshitz gravity. We also write out the Friedmann equation in 3+1 dimensions for cosmological solutions.

Rong-Gen Cai; Yan Liu; Ya-Wen Sun

2009-06-04T23:59:59.000Z

239

Neutrino magnetic moment in a magnetized plasma  

E-Print Network [OSTI]

The contribution of a magnetized plasma to the neutrino magnetic moment is calculated. It is shown that only part of the additional neutrino energy in magnetized plasma connecting with its spin and magnetic field strength defines the neutrino magnetic moment. It is found that the presence of magnetized plasma does not lead to the considerable increase of the neutrino magnetic moment in contrast to the results presented in literature previously.

N. V. Mikheev; E. N. Narynskaya

2010-11-08T23:59:59.000Z

240

Taub-NUT Black Holes in Third order Lovelock Gravity  

E-Print Network [OSTI]

We consider the existence of Taub-NUT solutions in third order Lovelock gravity with cosmological constant, and obtain the general form of these solutions in eight dimensions. We find that, as in the case of Gauss-Bonnet gravity and in contrast with the Taub-NUT solutions of Einstein gravity, the metric function depends on the specific form of the base factors on which one constructs the circle fibration. Thus, one may say that the independence of the NUT solutions on the geometry of the base space is not a robust feature of all generally covariant theories of gravity and is peculiar to Einstein gravity. We find that when Einstein gravity admits non-extremal NUT solutions with no curvature singularity at $r=N$, then there exists a non-extremal NUT solution in third order Lovelock gravity. In 8-dimensional spacetime, this happens when the metric of the base space is chosen to be $\\Bbb{CP}^{3}$. Indeed, third order Lovelock gravity does not admit non-extreme NUT solutions with any other base space. This is another property which is peculiar to Einstein gravity. We also find that the third order Lovelock gravity admits extremal NUT solution when the base space is $T^{2}\\times T^{2}\\times T^{2}$ or $S^{2}\\times T^{2}\\times T^{2}$. We have extended these observations to two conjectures about the existence of NUT solutions in Lovelock gravity in any even-dimensional spacetime.

S. H. Hendi; M. H. Dehghani

2008-08-05T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

The equilibrium of dense plasma in a gravity field  

E-Print Network [OSTI]

The equilibrium of dense plasma in a gravity field and problem of a gravity-induced electric polarization in this matter are discussed. The calculation for metals performed before shows that both - the gravity-induced compressive strain and the gravity-induced electric field - are inversely proportional to their Young moduli. The calculation for high dense plasma, where Young modulus is equal to zero, shows that there is another effect: each cell of this plasma inside a celestial body in own gravity field obtains the small positive electric charge. It happens as heavy ions sag on to light electron clouds. A celestial body stays electrically neutral as a whole, because the negative electric charge concentrates on its surface. The gravity-induced positive volume charge is very small, its order of magnitude equals to $10^{-18}e$ per atom only. But it is sufficient for the complete conterbalancing of the gravity force.

B. V. Vasiliev

2000-10-31T23:59:59.000Z

242

Dynamically stable magnetic suspension/bearing system  

DOE Patents [OSTI]

A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw's Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements.

Post, Richard F. (Walnut Creek, CA)

1996-01-01T23:59:59.000Z

243

Dynamically stable magnetic suspension/bearing system  

DOE Patents [OSTI]

A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw`s Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements. 32 figs.

Post, R.F.

1996-02-27T23:59:59.000Z

244

Patterned Magnetic Nanostructures and Quantized Magnetic Disks  

E-Print Network [OSTI]

, opens up new opportunities for engineering innovative magnetic materials and devices, developing ultra of magnetic nanostructures as small as 10 nm; 2) engineering of unique magnetic properties (such as domainPatterned Magnetic Nanostructures and Quantized Magnetic Disks STEPHEN Y. CHOU Invited Paper

245

Petroglyphs, Lighting, and Magnetism  

E-Print Network [OSTI]

1950 Electricity and Magnetism: Theory and Applications.I Petroglyphs, Lightning, and Magnetism | Walker Figure 8.I Petroglyphs, Lightning, and Magnetism | Walker Figure IL

Walker, Merle F

2007-01-01T23:59:59.000Z

246

Correlation Functions in the Multiple Ising Model Coupled to Gravity  

E-Print Network [OSTI]

The model of p Ising spins coupled to 2d gravity, in the form of a sum over planar phi-cubed graphs, is studied and in particular the two-point and spin-spin correlation functions are considered. We first solve a toy model in which only a partial summation over spin configurations is performed and, using a modified geodesic distance, various correlation functions are determined. The two-point function has a diverging length scale associated with it. The critical exponents are calculated and it is shown that all the standard scaling relations apply. Next the full model is studied, in which all spin configurations are included. Many of the considerations for the toy model apply for the full model, which also has a diverging geometric correlation length associated with the transition to a branched polymer phase. Using a transfer function we show that the two-point and spin-spin correlation functions decay exponentially with distance. Finally, by assuming various scaling relations, we make a prediction for the critical exponents at the transition between the magnetized and branched polymer phases in the full model.

M. G. Harris; J. Ambjorn

1996-02-06T23:59:59.000Z

247

The effective sigma-model of multidimensional gravity  

E-Print Network [OSTI]

The properties of the effective sigma-model for D-dimensional Einstein gravity based on multidimensional geometries is analyzed. Besides pure geometry, additional minimally coupled scalars and (p+2)-forms are considered which yield an extended target space after reduction to the effective D_0-dimensional geometry. In any case the target space is a homogeneous space. The orthobrane condition guarantees the existence of exact solutions. Geometrically, it makes the target space a locally symmetric one. New solutions with scalar fields are found, which may inflate not only in time-like but in also in additional spatial directions of the effective geometry. Static spherically symmetric solutions with a particular configuration of intersecting electric and magnetic branes are investigated both, for the orthobrane case and for degenerated charges. In both cases T_H depends critically on the intersection dimension of the p-branes. Finally, the role of the Einstein frame for 4-geometries is addressed, and the physical frame transformation for cosmological geometries is given.

M. Rainer

1999-05-28T23:59:59.000Z

248

In quantum gravity, summing is refining  

E-Print Network [OSTI]

In perturbative QED, the approximation is improved by summing more Feynman graphs; in non-perturbative QCD, by refining the lattice. Here we observe that in quantum gravity the two procedures may well be the same. We outline the combinatorial structure of spinfoam quantum gravity, define the continuum limit, and show that under general conditions refining foams is the same as summing over them. The conditions bear on the cylindrical consistency of the spinfoam amplitudes and on the presence of appropriate combinatorial factors, related to the implementation of diffeomorphisms invariance. Intuitively, the sites of the lattice are points of space: these are themselves quanta of the gravitational field, and thus a lattice discretization is also a Feynman history of quanta.

Carlo Rovelli; Matteo Smerlak

2011-05-03T23:59:59.000Z

249

The Origin of Structures in Generalized Gravity  

E-Print Network [OSTI]

In a class of generalized gravity theories with general couplings between the scalar field and the scalar curvature in the Lagrangian, we can describe the quantum generation and the classical evolution of both the scalar and tensor structures in a simple and unified manner. An accelerated expansion phase based on the generalized gravity in the early universe drives microscopic quantum fluctuations inside a causal domain to expand into macroscopic ripples in the spacetime metric on scales larger than the local horizon. Following their generation from quantum fluctuations, the ripples in the metric spend a long period outside the causal domain. During this phase their evolution is characterized by their conserved amplitudes. The evolution of these fluctuations may lead to the observed large scale structures of the universe and anisotropies in the cosmic microwave background radiation.

J. Hwang

1997-11-21T23:59:59.000Z

250

Phenomenology of Irreversible Processes from Gravity  

E-Print Network [OSTI]

We propose that the space-time evolution of strongly coupled matter formed by ultra-relativistic heavy ion collisions can be modelled by phenomenological equations involving the energy-momentum tensor and conserved currents alone. These equations can describe the late stage of local chemical and thermal equilibration of the matter formed after collisions, and its subsequent transition to hydrodynamic expansion in an unified framework. The full set of equations include local energy, momentum and charge conservation; but also additional equations for evolution of non-equilibrium variables. These equations with precisely determined phenomenological parameters can be obtained by the AdS/CFT correspondence. On the gravity side of this correspondence, for vanishing chemical potentials, these phenomenological equations give all solutions of pure gravity in AdS which have regular future horizons. We also discuss field-theoretic grounds for validity of these phenomenological equations.

Ramakrishnan Iyer; Ayan Mukhopadhyay

2011-11-17T23:59:59.000Z

251

Holographic studies of quasi-topological gravity  

E-Print Network [OSTI]

Quasi-topological gravity is a new gravitational theory including curvature-cubed interactions and for which exact black hole solutions were constructed. In a holographic framework, classical quasi-topological gravity can be thought to be dual to the large $N_c$ limit of some non-supersymmetric but conformal gauge theory. We establish various elements of the AdS/CFT dictionary for this duality. This allows us to infer physical constraints on the couplings in the gravitational theory. Further we use holography to investigate hydrodynamic aspects of the dual gauge theory. In particular, we find that the minimum value of the shear-viscosity-to-entropy-density ratio for this model is $\\eta/s \\simeq 0.4140/(4\\pi)$.

Robert C. Myers; Miguel F. Paulos; Aninda Sinha

2010-06-09T23:59:59.000Z

252

Black holes in Asymptotically Safe Gravity  

E-Print Network [OSTI]

Black holes are among the most fascinating objects populating our universe. Their characteristic features, encompassing spacetime singularities, event horizons, and black hole thermodynamics, provide a rich testing ground for quantum gravity ideas. In this note we observe that the renormalization group improved Schwarzschild black holes constructed by Bonanno and Reuter within Weinberg's asymptotic safety program constitute a prototypical example of a Hayward geometry used to model non-singular black holes within quantum gravity phenomenology. Moreover, they share many features of a Planck star: their effective geometry naturally incorporates the one-loop corrections found in the effective field theory framework, their Kretschmann scalar is bounded, and the black hole singularity is replaced by a regular de Sitter patch. The role of the cosmological constant in the renormalization group improvement process is briefly discussed.

Saueressig, Frank; D'Odorico, Giulio; Vidotto, Francesca

2015-01-01T23:59:59.000Z

253

Elliptic Genera and 3d Gravity  

E-Print Network [OSTI]

We describe general constraints on the elliptic genus of a 2d supersymmetric conformal field theory which has a gravity dual with large radius in Planck units. We give examples of theories which do and do not satisfy the bounds we derive, by describing the elliptic genera of symmetric product orbifolds of $K3$, product manifolds, certain simple families of Calabi-Yau hypersurfaces, and symmetric products of the "Monster CFT." We discuss the distinction between theories with supergravity duals and those whose duals have strings at the scale set by the AdS curvature. Under natural assumptions we attempt to quantify the fraction of (2,2) supersymmetric conformal theories which admit a weakly curved gravity description, at large central charge.

Benjamin, Nathan; Kachru, Shamit; Moore, Gregory W; Paquette, Natalie M

2015-01-01T23:59:59.000Z

254

Chaotic inflation in higher derivative gravity theories  

E-Print Network [OSTI]

In this paper, we investigate chaotic inflation from scalar field subjected to potential in the framework of $f(R^2, P, Q)$-gravity, where we add a correction to Einstein's gravity based on a function of the square of the Ricci scalar $R^2$, the contraction of the Ricci tensor $P$, and the contraction of the Riemann tensor $Q$. The Gauss-Bonnet case is also discussed. We give the general formalism of inflation, deriving the slow-roll parameters, the $e$-folds number, and the spectral indexes. Several explicit examples are furnished, namely we will consider the cases of massive scalar field and scalar field with quartic potential and some power-law function of the curvature invariants under investigation in the gravitational action of the theory. Viable inflation according with observations is analyzed.

Myrzakul, Shynaray; Sebastiani, Lorenzo

2015-01-01T23:59:59.000Z

255

Propagation of gravitational waves in multimetric gravity  

E-Print Network [OSTI]

We discuss the propagation of gravitational waves in a recently discussed class of theories containing N >= 2 metric tensors and a corresponding number of standard model copies. Using the formalism of gauge-invariant linear perturbation theory we show that all gravitational waves propagate at the speed of light. We then employ the Newman-Penrose formalism to show that two to six polarizations of gravitational waves may exist, depending on the parameters entering the equations of motion. This corresponds to E(2) representations N_2, N_3, III_5 and II_6. We finally apply our general discussion to a recently presented concrete multimetric gravity model and show that it is of class N_2, i.e., it allows only two tensor polarizations, as it is the case for general relativity. Our results provide the theoretical background for tests of multimetric gravity theories using the upcoming gravitational wave experiments.

Manuel Hohmann

2012-04-22T23:59:59.000Z

256

Detecting individual gravity modes in the Sun  

E-Print Network [OSTI]

Many questions are still open regarding the structure and the dynamics of the solar core. By constraining more this region in the solar evolution models, we can reduce the incertitudes on some physical processes and on momentum transport mechanisms. A first big step was made with the detection of the signature of the dipole-gravity modes in the Sun, giving a hint of a faster rotation rate inside the core. A deeper analysis of the GOLF/SoHO data unveils the presence of a pattern of peaks that could be interpreted as dipole gravity modes. In that case, those modes can be characterized, thus bringing better constraints on the rotation of the core as well as some structural parameters such as the density at these very deep layers of the Sun interior.

Garcia, R A; Eff-Darwich, A; Garrido, R; Jimenez, A; Mathis, S; Moya, A; Palle, P L; Regulo, C; Salabert, D; Suarez, J C; Turck-Chieze, S

2009-01-01T23:59:59.000Z

257

Quantum gravity at a Lifshitz point  

SciTech Connect (OSTI)

We present a candidate quantum field theory of gravity with dynamical critical exponent equal to z=3 in the UV. (As in condensed-matter systems, z measures the degree of anisotropy between space and time.) This theory, which at short distances describes interacting nonrelativistic gravitons, is power-counting renormalizable in 3+1 dimensions. When restricted to satisfy the condition of detailed balance, this theory is intimately related to topologically massive gravity in three dimensions, and the geometry of the Cotton tensor. At long distances, this theory flows naturally to the relativistic value z=1, and could therefore serve as a possible candidate for a UV completion of Einstein's general relativity or an infrared modification thereof. The effective speed of light, the Newton constant and the cosmological constant all emerge from relevant deformations of the deeply nonrelativistic z=3 theory at short distances.

Horava, Petr [Berkeley Center for Theoretical Physics and Department of Physics, University of California, Berkeley, California, 94720-7300 (United States) and Physics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720-8162 (United States)

2009-04-15T23:59:59.000Z

258

Hydrogen atom in Palatini theories of gravity  

E-Print Network [OSTI]

We study the effects that the gravitational interaction of $f(R)$ theories of gravity in Palatini formalism has on the stationary states of the Hydrogen atom. We show that the role of gravity in this system is very important for lagrangians $f(R)$ with terms that grow at low curvatures, which have been proposed to explain the accelerated expansion rate of the universe. We find that new gravitationally induced terms in the atomic Hamiltonian generate a strong backreaction that is incompatible with the very existence of bound states. In fact, in the 1/R model, Hydrogen disintegrates in less than two hours. The universe that we observe is, therefore, incompatible with that kind of gravitational interaction. Lagrangians with high curvature corrections do not lead to such instabilities.

Gonzalo J. Olmo

2008-06-03T23:59:59.000Z

259

Non-metric gravity: A status report  

E-Print Network [OSTI]

We review the status of a certain (infinite) class of four-dimensional generally covariant theories propagating two degrees of freedom that are formulated without any direct mention of the metric. General relativity itself (in its Plebanski formulation) belongs to the class, so these theories are examples of modified gravity. We summarize the current understanding of the nature of the modification, of the renormalizability properties of these theories, of their coupling to matter fields, and describe some of their physical properties.

Kirill Krasnov

2007-11-05T23:59:59.000Z

260

The Hausdorff dimension in polymerized quantum gravity  

E-Print Network [OSTI]

We calculate the Hausdorff dimension, $d_H$, and the correlation function exponent, $\\eta$, for polymerized two dimensional quantum gravity models. If the non-polymerized model has correlation function exponent $\\eta_0 >3$ then $d_H=\\gamma^{-1}$ where $\\gamma$ is the susceptibility exponent. This suggests that these models may be in the same universality class as certain non-generic branched polymer models.

Martin G. Harris; John F. Wheater

1998-11-24T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

A Thermodynamic Sector of Quantum Gravity  

E-Print Network [OSTI]

The connection between gravity and thermodynamics is explored. Examining a perfect fluid in gravitational equilibrium we find that the entropy is extremal only if Einstein's equations are satisfied. Conversely, one can derive part of Einstein's equations from ordinary thermodynamical considerations. This allows the theory of this system to be recast in such a way that a sector of general relativity is purely thermodynamical and should not be quantized.

J. Oppenheim

2001-12-04T23:59:59.000Z

262

Redshift Distortions as a Probe of Gravity  

E-Print Network [OSTI]

Redshift distortion measurements from galaxy surveys include sensitivity to the gravitational growth index distinguishing other theories from Einstein gravity. This gravitational sensitivity is substantially free from uncertainty in the effective equation of state of the cosmic expansion history. We also illustrate the bias in the traditional application to matter density determination using f=Omega_m(a)^{0.6}, and how to avoid it.

Eric V. Linder

2007-09-07T23:59:59.000Z

263

Gravity controlled anti-reverse rotation device  

DOE Patents [OSTI]

A gravity assisted anti-reverse rotation device for preventing reverse rotation of pumps and the like. A horizontally mounted pawl is disposed to mesh with a fixed ratchet preventing reverse rotation when the pawl is advanced into intercourse with the ratchet by a vertically mounted lever having a lumped mass. Gravitation action on the lumped mass urges the pawl into mesh with the ratchet, while centrifugal force on the lumped mass during forward, allowed rotation retracts the pawl away from the ratchet.

Dickinson, Robert J. (Shaler Township, Allegheny County, PA); Wetherill, Todd M. (Lower Burrell, PA)

1983-01-01T23:59:59.000Z

264

Holographic Superconductors in Horava-Lifshitz Gravity  

E-Print Network [OSTI]

We consider holographic superconductors related to the Schwarzschild black hole in the low energy limit of Ho\\v{r}ava-Lifshitz spacetime. The non-relativistic electromagnetic and scalar fields are introduced to construct a holographic superconductor model in Ho\\v{r}ava-Lifshitz gravity and the results show that the $\\alpha_2$ term plays an important role, modifying the conductivity curve line by means of an attenuation the conductivity.

Kai Lin; Elcio Abdalla; Anzhong Wang

2014-06-18T23:59:59.000Z

265

Exact Gravity Dual of a Gapless Superconductor  

E-Print Network [OSTI]

A model of an exact gravity dual of a gapless superconductor is presented in which the condensate is provided by a charged scalar field coupled to a bulk black hole of hyperbolic horizon in asymptotically AdS spacetime. Below a critical temperature, the black hole acquires its hair through a phase transition while an electromagnetic perturbation of the background Maxwell field determines the conductivity of the boundary theory.

George Koutsoumbas; Eleftherios Papantonopoulos; George Siopsis

2009-06-17T23:59:59.000Z

266

Holographic Superconductivity with Gauss-Bonnet gravity  

E-Print Network [OSTI]

I review recent work on holographic superconductivity with Einstein-Gauss-Bonnet gravity, and show how the critical temperature of the superconductor depends on both gravitational backreaction and the Gauss-Bonnet parameter, using both analytic and numerical arguments. I also review computations of the conductivity, finding the energy gap, and demonstrating that there is no universal gap ratio, $\\omega_g/T_c$, for these superconductors.

Ruth Gregory

2010-12-07T23:59:59.000Z

267

Magnetic Catalysis vs Magnetic Inhibition  

E-Print Network [OSTI]

We discuss the fate of chiral symmetry in an extremely strong magnetic field B. We investigate not only quark fluctuations but also neutral meson effects. The former would enhance the chiral-symmetry breaking at finite B according to the Magnetic Catalysis, while the latter would suppress the chiral condensate once B exceeds the scale of the hadron structure. Using a chiral model we demonstrate how neutral mesons are subject to the dimensional reduction and the low dimensionality favors the chiral-symmetric phase. We point out that this effect, the Magnetic Inhibition, can be a feasible explanation for recent lattice-QCD data indicating the decreasing behavior of the chiral-restoration temperature with increasing B.

Kenji Fukushima; Yoshimasa Hidaka

2012-09-06T23:59:59.000Z

268

Magnetic Stereoscopy  

E-Print Network [OSTI]

The space mission STEREO will provide images from two viewpoints. An important aim of the STEREO mission is to get a 3D view of the solar corona. We develop a program for the stereoscopic reconstruction of 3D coronal loops from images taken with the two STEREO spacecraft. A pure geometric triangulation of coronal features leads to ambiguities because the dilute plasma emissions complicates the association of features in image 1 with features in image 2. As a consequence of these problems the stereoscopic reconstruction is not unique and multiple solutions occur. We demonstrate how these ambiguities can be resolved with the help of different coronal magnetic field models (potential, linear and non-linear force-free fields). The idea is that, due to the high conductivity in the coronal plasma, the emitting plasma outlines the magnetic field lines. Consequently the 3D coronal magnetic field provides a proxy for the stereoscopy which allows to eliminate inconsistent configurations. The combination of stereoscopy and magnetic modelling is more powerful than one of these tools alone. We test our method with the help of a model active region and plan to apply it to the solar case as soon as STEREO data become available.

Thomas Wiegelmann; Bernd Inhester

2006-12-21T23:59:59.000Z

269

Cosmology with Coupled Gravity and Dark Energy  

E-Print Network [OSTI]

Dark energy is a fundamental constituent of our universe, its status in the cosmological field equation should be equivalent to that of gravity. Here we construct a dark energy and matter gravity coupling (DEMC) model of cosmology in a way that dark energy and gravity are introduced into the cosmological field equation in parallel with each other from the beginning. The DEMC universe possesses a composite symmetry from global Galileo invariance and local Lorentz invariance. The observed evolution of the universe expansion rate at redshift z>1 is in tension with the standard LCDM model, but can be well predicted by the DEMC model from measurements of only nearby epochs. The so far most precise measured expansion rate at high z is quite a bit slower than the expectations from LCDM, but remarkably consistent with that from DEMC. It is hoped that the DEMC scenario can also help to solve other existing challenges to cosmology: large scale anomalies in CMB maps and large structures up to about 10^3 Mpc of a quasar group. The DEMC universe is a well defined mechanical system. From measurements we can quantitatively evaluate its total rest energy, present absolute radius and expanding speed.

Ti-Pei Li

2015-01-13T23:59:59.000Z

270

Abelian-Higgs strings in Rastall gravity  

E-Print Network [OSTI]

In this paper we analyze Abelian-Higgs strings in a phenomenological model that takes quantum effects in curved space-time into account. This model, first introduced by Rastall, cannot be derived from an action principle. We formulate phenomenological equations of motion under the guiding principle of minimal possible deformation of the standard equations. We construct string solutions that asymptote to a flat space-time with a deficit angle by solving the set of coupled non-linear ordinary differential equations numerically. Decreasing the Rastall parameter from its Einstein gravity value we find that the deficit angle of the space-time increases and becomes equal to $2\\pi$ at some critical value of this parameter that depends on the remaining couplings in the model. For smaller values the resulting solutions are supermassive string solutions possessing a singularity at a finite distance from the string core. Assuming the Higgs boson mass to be on the order of the gauge boson mass we find that also in Rastall gravity this happens only when the symmetry breaking scale is on the order of the Planck mass. We also observe that for specific values of the parameters in the model the energy per unit length becomes proportional to the winding number, i.e. the degree of the map $S^1 \\rightarrow S^1$. Unlike in the BPS limit in Einstein gravity, this is, however, not connect to an underlying mathematical structure, but rather constitutes a would-be-BPS bound.

Eugenio R. Bezerra de Mello; Julio C. Fabris; Betti Hartmann

2015-04-02T23:59:59.000Z

271

Superconducting Magnet Division  

E-Print Network [OSTI]

Superconducting Magnet Division DOE NP Program Review - July 06 1 Brookhaven Magnet Division - Nuclear Physics Program Support Activities Superconducting Magnet Program RHIC Operations Support Spin Summary Peter Wanderer, DOE review, July 25, 2006 Acting Head, Superconducting Magnet Division #12

272

Solar System experiments do not yet veto modified gravity models  

E-Print Network [OSTI]

The dynamical equivalence between modified and scalar-tensor gravity theories is revisited and it is concluded that it breaks down in the limit to general relativity. A gauge-independent analysis of cosmological perturbations in both classes of theories lends independent support to this conclusion. As a consequence, the PPN formalism of scalar-tensor gravity and Solar System experiments do not veto modified gravity, as previously thought.

Valerio Faraoni

2006-07-05T23:59:59.000Z

273

AdS waves as exact solutions to quadratic gravity  

SciTech Connect (OSTI)

We give an exact solution of the quadratic gravity in D dimensions. The solution is a plane-fronted wave metric with a cosmological constant. This metric solves not only the full quadratic gravity field equations but also the linearized ones which include the linearized equations of the recently found critical gravity. A subset of the solutions change the asymptotic structure of the anti-de Sitter space due to their logarithmic behavior.

Guellue, Ibrahim; Sisman, Tahsin Cagri; Tekin, Bayram [Department of Physics, Middle East Technical University, 06531 Ankara (Turkey); Guerses, Metin [Department of Mathematics, Faculty of Sciences Bilkent University, 06800 Ankara (Turkey)

2011-04-15T23:59:59.000Z

274

Using precision gravity data in geothermal reservoir engineering modeling studies  

SciTech Connect (OSTI)

Precision gravity measurements taken at various times over a geothermal field can be used to derive information about influx into the reservoir. Output from a reservoir simulation program can be used to compute surface gravity fields and time histories. Comparison of such computer results with field-measured gravity data can add confidence to simulation models, and provide insight into reservoir processes. Such a comparison is made for the Bulalo field in the Philippines.

Atkinson, Paul G.; Pederseen, Jens R.

1988-01-01T23:59:59.000Z

275

Gravity Survey of the Carson Sink - Data and Maps  

SciTech Connect (OSTI)

A detailed gravity survey was carried out for the entire Carson Sink in western Nevada (Figure 1) through a subcontract to Zonge Engineering, Inc. The Carson Sink is a large composite basin containing three known, blind high?temperature geothermal systems (Fallon Airbase, Stillwater, and Soda Lake). This area was chosen for a detailed gravity survey in order to characterize the gravity signature of the known geothermal systems and to identify other potential blind systems based on the structural setting indicated by the gravity data. Data: Data were acquired at approximately 400, 800, and 1600 meter intervals for a total of 1,243 stations. The project location and station location points are presented in Figure 14. The station distribution for this survey was designed to complete regional gravity coverage in the Carson Sink area without duplication of available public and private gravity coverage. Gravity data were acquired using a Scintrex CG?5 gravimeter and a LaCoste and Romberg (L&R) Model?G gravimeter. The CG?5 gravity meter has a reading resolution of 0.001 milligals and a typical repeatability of less than 0.005 milligals. The L&R gravity meter has a reading resolution of 0.01 milligals and a typical repeatability of 0.02 milligals. The basic processing of gravimeter readings to calculate through to the Complete Bouguer Anomaly was made using the Gravity and Terrain Correction software version 7.1 for Oasis Montaj by Geosoft LTD. Results: The gravity survey of the Carson Sink yielded the following products. Project location and station location map (Figure 14). Complete Bouguer Anomaly @ 2.67 gm/cc reduction density. Gravity Complete Bouguer Anomaly at 2.50 g/cc Contour Map (Figure 15). Gravity Horizontal Gradient Magnitude Shaded Color Contour Map. Gravity 1st Vertical Derivative Color Contour Map. Interpreted Depth to Mesozoic Basement (Figure 16), incorporating drill?hole intercept values. Preliminary Interpretation of Results: The Carson Sink is a complex composite basin with several major depocenters (Figures 15 and 16). Major depocenters are present in the south?central, east?central, and northeastern parts of the basin. The distribution of gravity anomalies suggests a complex pattern of faulting in the subsurface of the basin, with many fault terminations, step?overs, and accommodation zones. The pattern of faulting implies that other, previously undiscovered blind geothermal systems are likely in the Carson Sink. The gravity survey was completed near the end of this project. Thus, more thorough analysis of the data and potential locations of blind geothermal systems is planned for future work.

Faulds, James E.

2013-12-31T23:59:59.000Z

276

Detecting gravity modes in the solar $^8B$ neutrino flux  

E-Print Network [OSTI]

The detection of gravity modes produced in the solar radiative zone has been a challenge in modern astrophysics for more than 30 yr and their amplitude in the core is not yet determined. In this Letter, we develop a new strategy to look for standing gravity modes through solar neutrino fluxes. We note that due to a resonance effect, the gravity modes of low degree and low order have the largest impact on the $^{8}B$ neutrino flux. The strongest effect is expected to occur for the dipole mode with radial order $2$, corresponding to periods of about 1.5 hr. These standing gravity waves produce temperature fluctuations that are amplified by a factor of 170 in the boron neutrino flux for the corresponding period, in consonance with the gravity modes. From current neutrino observations, we determine that the maximum temperature variation due to the gravity modes in the Sun's core is smaller than $5.8\\times 10^{-4}$. This study clearly shows that due to their high sensitivity to the temperature, the $^8B$ neutrino flux time series is an excellent tool to determine the properties of gravity modes in the solar core. Moreover, if gravity mode footprints are discovered in the $^{8}B$ neutrino flux, this opens a new line of research to probe the physics of the solar core as non-standing gravity waves of higher periods cannot be directly detected by helioseismology but could leave their signature on boron neutrino or on other neutrino fluxes.

Ildio Lopes; Sylvaine Turck-Chize

2014-08-28T23:59:59.000Z

277

Lessons from (2+1)-dimensional quantum gravity  

E-Print Network [OSTI]

Proposals that quantum gravity gives rise to non-commutative spacetime geometry and deformations of Poincare symmetry are examined in the context of (2+1)-dimensional quantum gravity. The results are expressed in five lessons, which summarise how the gravitational constant, Planck's constant and the cosmological constant enter the non-commutative and non-cocommutative structures arising in (2+1)-dimensional quantum gravity. It is emphasised that the much studied bicrossproduct kappa-Poincare algebra does not arise directly in (2+1)-dimensional quantum gravity.

B. J. Schroers

2007-10-31T23:59:59.000Z

278

Ground Gravity Survey At Dixie Valley Geothermal Area (Allis...  

Open Energy Info (EERE)

Activity Details Location Dixie Valley Geothermal Area Exploration Technique Ground Gravity Survey Activity Date 1999 - 2000 Usefulness not indicated DOE-funding Unknown...

279

Ground Gravity Survey At Kilauea East Rift Geothermal Area (Broyles...  

Open Energy Info (EERE)

to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Kilauea East Rift Geothermal Area (Broyles, Et Al., 1979) Exploration...

280

Bouguer gravity anomalies, depth to bedrock, and shallow temperature...  

Open Energy Info (EERE)

Bouguer gravity anomalies, depth to bedrock, and shallow temperature in the Humboldt House geothermal area, Pershing County, Nevada Jump to: navigation, search OpenEI Reference...

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Ground Gravity Survey At Kilauea East Rift Geothermal Area (Leslie...  

Open Energy Info (EERE)

Details Location Kilauea East Rift Geothermal Area Exploration Technique Ground Gravity Survey Activity Date 1998 - 1998 Usefulness useful DOE-funding Unknown Exploration...

282

Integration of Full Tensor Gravity and ZTEM Passive Low Frequency...  

Broader source: Energy.gov (indexed) [DOE]

Full Tensor Gravity and ZTEM Passive Low Frequency EM Instruments for Simultaneous Data Acquisition Scott Wieberg Bell Geospace, Inc. Track Name Project Officer: Ava Coy: Total...

283

Ground Gravity Survey At Neal Hot Springs Geothermal Area (U...  

Open Energy Info (EERE)

to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Neal Hot Springs Geothermal Area (U.S. Geothermal Inc., 2007) Exploration...

284

Ground Gravity Survey At Kilauea East Rift Geothermal Area (FURUMOTO...  

Open Energy Info (EERE)

Details Location Kilauea East Rift Geothermal Area Exploration Technique Ground Gravity Survey Activity Date 1974 - 1974 Usefulness useful DOE-funding Unknown Exploration...

285

Ground Gravity Survey At Mt Princeton Hot Springs Geothermal...  

Open Energy Info (EERE)

to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Mt Princeton Hot Springs Geothermal Area (Case, Et Al., 1984) Exploration...

286

Ground Gravity Survey At Baltazor Hot Springs Area (Isherwood...  

Open Energy Info (EERE)

to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Baltazor Hot Springs Area (Isherwood & Mabey, 1978) Exploration Activity...

287

Ground Gravity Survey At Roosevelt Hot Springs Geothermal Area...  

Open Energy Info (EERE)

Details Location Roosevelt Hot Springs Geothermal Area Exploration Technique Ground Gravity Survey Activity Date 1985 - 1985 Usefulness useful DOE-funding Unknown Exploration...

288

Ground Gravity Survey At Blue Mountain Geothermal Area (Fairbank...  

Open Energy Info (EERE)

Fairbank Engineering Ltd, 2003) Exploration Activity Details Location Blue Mountain Geothermal Area Exploration Technique Ground Gravity Survey Activity Date Usefulness not...

289

Lessons in quantum gravity from quantum field theory  

SciTech Connect (OSTI)

This paper reviews advances in the understanding of quantum gravity based on field theory calculations in the AdS/CFT correspondence.

Berenstein, David [Department of Physics, University of California at Santa Barbara, CA 93106 (United States); Institute for Advanced Study, School of Natural Science, Princeton, NJ 08540 (United States)

2010-12-07T23:59:59.000Z

290

Ground Gravity Survey At Under Steamboat Springs Area (Warpinski...  

Open Energy Info (EERE)

Area (Warpinski, Et Al., 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Under Steamboat Springs Area (Warpinski,...

291

Ground Gravity Survey At Valles Caldera - Sulphur Springs Geothermal...  

Open Energy Info (EERE)

Survey Activity Date - 1986 Usefulness not indicated DOE-funding Unknown Notes A computer program capable of two-dimensional modeling of gravity data was used in interpreting...

292

Summary of Session A6: Alternative Theories of Gravity  

E-Print Network [OSTI]

This is a summary of the workshop A.6 on Alternative Theories of Gravity, prepared for the proceedings for the GR15 conference.

R. B. Mann

1998-03-13T23:59:59.000Z

293

asymptotically safe gravity: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

at high energies. Elisa Manrique; Stefan Rechenberger; Frank Saueressig 2011-02-24 2 Fractal Spacetime Structure in Asymptotically Safe Gravity General Relativity & Quantum...

294

Ground Gravity Survey At Lake City Hot Springs Area (Warpinski...  

Open Energy Info (EERE)

Lake City Hot Springs Area (Warpinski, Et Al., 2004) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Lake City Hot...

295

Unification of Gravity and Electromagnetism II A Geometric Theory  

E-Print Network [OSTI]

It is shown that unification of gravity and electromagnetism can be achieved using an affine non-symmetric connection $\\Gamma^\\lambda_{\\mu\

Partha Ghose

2014-08-05T23:59:59.000Z

296

atmospheric gravity waves: Topics by E-print Network  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

gravity waves (AGWs). Satellite imagery shows evidence the characteristics of these waves. The favorable wave propagation conditions in 12;this region are illustrated 5...

297

Exercise protocols during short-radius centrifugation for artificial gravity  

E-Print Network [OSTI]

Long-duration spaceflight results in severe physiological deconditioning, threatening the success of interplanetary travel. Exercise combined with artificial gravity provided by centrifugation may be the comprehensive ...

Edmonds, Jessica Leigh

2008-01-01T23:59:59.000Z

298

Ground Gravity Survey At Long Valley Caldera Geothermal Area...  

Open Energy Info (EERE)

Battaglia, Et Al., 2003) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Ground Gravity Survey At Long Valley Caldera Geothermal Area (Battaglia,...

299

The Ising Model on a Dynamically Triangulated Disk with a Boundary Magnetic Field  

E-Print Network [OSTI]

We use Monte Carlo simulations to study a dynamically triangulated disk with Ising spins on the vertices and a boundary magnetic field. For the case of zero magnetic field we show that the model possesses three phases. For one of these the boundary length grows linearly with disk area, while the other two phases are characterized by a boundary whose size is on the order of the cut-off. A line of continuous magnetic transitions separates the two small boundary phases. We determine the critical exponents of the continuous magnetic phase transition and relate them to predictions from continuum 2-d quantum gravity. This line of continuous transitions appears to terminate on a line of discontinuous phase transitions dividing the small boundary phases from the large boundary phase. We examine the scaling of bulk magnetization and boundary magnetization as a function of boundary magnetic field in the vicinity of this tricritical point.

Scott McGuire; Simon Catterall; Mark Bowick; Simeon Warner

2001-05-02T23:59:59.000Z

300

Magnetic Reconnection  

SciTech Connect (OSTI)

We review the fundamental physics of magnetic reconnection in laboratory and space plasmas, by discussing results from theory, numerical simulations, observations from space satellites, and the recent results from laboratory plasma experiments. After a brief review of the well-known early work, we discuss representative recent experimental and theoretical work and attempt to interpret the essence of significant modern findings. In the area of local reconnection physics, many significant findings have been made with regard to two- uid physics and are related to the cause of fast reconnection. Profiles of the neutral sheet, Hall currents, and the effects of guide field, collisions, and micro-turbulence are discussed to understand the fundamental processes in a local reconnection layer both in space and laboratory plasmas. While the understanding of the global reconnection dynamics is less developed, notable findings have been made on this issue through detailed documentation of magnetic self-organization phenomena in fusion plasmas. Application of magnetic reconnection physics to astrophysical plasmas is also brie y discussed.

Masaaki Yamada, Russell Kulsrud and Hantao Ji

2009-09-17T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

The JPL lunar gravity field to spherical harmonic degree 660 from the GRAIL Primary Mission  

E-Print Network [OSTI]

The lunar gravity field and topography provide a way to probe the interior structure of the Moon. Prior to the Gravity Recovery and Interior Laboratory (GRAIL) mission, knowledge of the lunar gravity was limited mostly to ...

Konopliv, Alex S.

302

Compositional modeling of threephase flow with gravity using higherorder finite element methods  

E-Print Network [OSTI]

Compositional modeling of threephase flow with gravity using higherorder finite element methods using higherorder finite element methods. Gravity poses complications in modeling multiphase processes flow with gravity using higherorder finite element methods, Water Resour. Res., 47, W05511, doi:10

Firoozabadi, Abbas

303

Eddy diffusivities of inertial particles under gravity  

E-Print Network [OSTI]

The large-scale/long-time transport of inertial particles of arbitrary mass density under gravity is investigated by means of a formal multiple-scale perturbative expansion in the scale-separation parametre between the carrier flow and the particle concentration field. The resulting large-scale equation for the particle concentration is determined, and is found to be diffusive with a positive-definite eddy diffusivity. The calculation of the latter tensor is reduced to the resolution of an auxiliary differential problem, consisting of a coupled set of two differential equations in a (6+1)-dimensional coordinate system (3 space coordinates plus 3 velocity coordinates plus time). Although expensive, numerical methods can be exploited to obtain the eddy diffusivity, for any desirable non-perturbative limit (e.g. arbitrary Stokes and Froude numbers). The aforementioned large-scale equation is then specialized to deal with two different relevant perturbative limits: i) vanishing of both Stokes time and sedimenting particle velocity; ii) vanishing Stokes time and finite sedimenting particle velocity. Both asymptotics lead to a greatly simplified auxiliary differential problem, now involving only space coordinates and thus easy to be tackled by standard numerical techniques. Explicit, exact expressions for the eddy diffusivities have been calculated, for both asymptotics, for the class of parallel flows, both static and time-dependent. This allows us to investigate analytically the role of gravity and inertia on the diffusion process by varying relevant features of the carrier flow, as e.g. the form of its temporal correlation function. Our results exclude a universal role played by gravity and inertia on the diffusive behaviour: regimes of both enhanced and reduced diffusion may exist, depending on the detailed structure of the carrier flow.

Marco Martins Afonso; Andrea Mazzino; Paolo Muratore-Ginanneschi

2011-03-29T23:59:59.000Z

304

Perturbations of Nested Branes With Induced Gravity  

E-Print Network [OSTI]

We study the behaviour of weak gravitational fields in models where a 4D brane is embedded inside a 5D brane equipped with induced gravity, which in turn is embedded in a 6D spacetime. We consider a specific regularization of the branes internal structures where the 5D brane can be considered thin with respect to the 4D one. We find exact solutions corresponding to pure tension source configurations on the thick 4D brane, and study perturbations at first order around these background solutions. To perform the perturbative analysis, we adopt a bulk-based approach and we express the equations in terms of gauge invariant and master variables using a 4D scalar-vector-tensor decomposition. We then propose an ansatz on the behaviour of the perturbation fields when the thickness of the 4D brane goes to zero, which corresponds to configurations where gravity remains finite everywhere in the thin limit of the 4D brane. We study the equations of motion using this ansatz, and show that they give rise to a consistent set of differential equations in the thin limit, from which the details of the internal structure of the 4D brane disappear. We conclude that the thin limit of the "ribbon" 4D brane inside the (already thin) 5D brane is well defined (at least when considering first order perturbations around pure tension configurations), and that the gravitational field on the 4D brane remains finite in the thin limit. We comment on the crucial role of the induced gravity term on the 5D brane.

Fulvio Sbisa'; Kazuya Koyama

2014-06-06T23:59:59.000Z

305

Wave Packets Propagation in Quantum Gravity  

E-Print Network [OSTI]

Wave packet broadening in usual quantum mechanics is a consequence of dispersion behavior of the medium which the wave propagates in it. In this paper, we consider the problem of wave packet broadening in the framework of Generalized Uncertainty Principle(GUP) of quantum gravity. New dispersion relations are derived in the context of GUP and it has been shown that there exists a gravitational induced dispersion which leads to more broadening of the wave packets. As a result of these dispersion relations, a generalized Klein-Gordon equation is obtained and its interpretation is given.

Kourosh Nozari; S. H. Mehdipour

2005-07-03T23:59:59.000Z

306

Conservation of energy and Gauss Bonnet gravity  

E-Print Network [OSTI]

It is shown how can be made the classification of all tensors constructed from the Riemann tensor that verify the conservation of gravitational energy momentum. More precisely we explain that there exists a unique tensor of degree n in the Riemann tensor and its contractions that verifies the conservation of energy. We show that this tensor, only because it obeys this degree n structure as well as energy conservation, two facts which are true in all dimensions, verifies in dimension 2n this striking particularity of being Euler gravity. We stick here to the case n=2 but explain briefly why the general case is similar.

Christophe Real

2007-11-07T23:59:59.000Z

307

Loop quantum gravity - a short review  

E-Print Network [OSTI]

In this article we review the foundations and the present status of loop quantum gravity. It is short and relatively non-technical, the emphasis is on the ideas, and the flavor of the techniques. In particular, we describe the kinematical quantization and the implementation of the Hamilton constraint, as well as the quantum theory of black hole horizons, semiclassical states, and matter propagation. Spin foam models and loop quantum cosmology are mentioned only in passing, as these will be covered in separate reviews to be published alongside this one.

Sahlmann, Hanno

2010-01-01T23:59:59.000Z

308

Gravity with a dynamical preferred frame  

E-Print Network [OSTI]

We study a generally covariant model in which local Lorentz invariance is broken "spontaneously" by a dynamical unit timelike vector field $u^a$---the "aether". Such a model makes it possible to study the gravitational and cosmological consequences of preferred frame effects, such as ``variable speed of light" or high frequency dispersion, while preserving a generally covariant metric theory of gravity. In this paper we restrict attention to an action for an effective theory of the aether which involves only the antisymmetrized derivative $\

Ted Jacobson; David Mattingly

2001-06-02T23:59:59.000Z

309

Cosmological Solutions of Emergent Noncommutative Gravity  

SciTech Connect (OSTI)

Matrix models of the Yang-Mills type lead to an emergent gravity theory, which does not require fine-tuning of a cosmological constant. We find cosmological solutions of the Friedmann-Robertson-Walker type. They generically have a big bounce, and an early inflationlike phase with graceful exit. The mechanism is purely geometrical; no ad hoc scalar fields are introduced. The solutions are stabilized through vacuum fluctuations and are thus compatible with quantum mechanics. This leads to a Milne-like universe after inflation, which appears to be in remarkably good agreement with observation and may provide an alternative to standard cosmology.

Klammer, Daniela; Steinacker, Harold [Fakultaet fuer Physik, Universitaet Wien, A-1090 Wien (Austria)

2009-06-05T23:59:59.000Z

310

Duality and KPZ in Liouville Quantum Gravity  

E-Print Network [OSTI]

We present a (mathematically rigorous) probabilistic and geometrical proof of the KPZ relation between scaling exponents in a Euclidean planar domain D and in Liouville quantum gravity. It uses the properly regularized quantum area measure d\\mu_\\gamma=\\epsilon^{\\gamma^2/2} e^{\\gamma h_\\epsilon(z)}dz, where dz is Lebesgue measure on D, \\gamma is a real parameter, 0\\leq \\gamma 2 is shown to be related to the quantum measure d\\mu_{\\gamma'}, \\gamma' < 2, by the fundamental duality \\gamma\\gamma'=4.

Bertrand Duplantier; Scott Sheffield

2009-01-02T23:59:59.000Z

311

Gravity duals for non-relativistic CFTs  

E-Print Network [OSTI]

We attempt to generalize the AdS/CFT correspondence to non-relativistic conformal field theories which are invariant under Galilean transformations. Such systems govern ultracold atoms at unitarity, nucleon scattering in some channels, and more generally, a family of universality classes of quantum critical behavior. We construct a family of metrics which realize these symmetries as isometries. They are solutions of gravity with negative cosmological constant coupled to pressureless dust. We discuss realizations of the dust, which include a bulk superconductor. We develop the holographic dictionary and compute some two-point correlators. A strange aspect of the correspondence is that the bulk geometry has two extra noncompact dimensions.

Koushik Balasubramanian; John McGreevy

2008-08-01T23:59:59.000Z

312

Thermodynamics of 5D dilaton-gravity  

SciTech Connect (OSTI)

We calculate the free energy, spatial string tension and Polyakov loop of the gluon plasma using the dilaton potential of Ref. [1] in the dilaton-gravity theory of AdS/QCD. The free energy is computed from the Black Hole solutions of the Einstein equations in two ways: first, from the Bekenstein-Hawking proportionality of the entropy with the area of the horizon, and secondly from the Page-Hawking computation of the free energy. The finite temperature behaviour of the spatial string tension and Polyakov loop follow from the corresponding string theory in AdS{sub 5}. Comparison with lattice data is made.

Megias, E. [Institute for Theoretical Physics, University of Heidelberg (Germany); Instituto de Fisica Teorica CSIC-UAM, Universidad Autonoma de Madrid (Spain)

2011-05-23T23:59:59.000Z

313

Holographic renormalization of new massive gravity  

SciTech Connect (OSTI)

We study holographic renormalization for three-dimensional new massive gravity. By studying the general falloff conditions for the metric allowed by the model at infinity, we show that at the critical point where the central charges of the dual conformal field theory (CFT) are zero, it contains a leading logarithmic behavior. In the context of AdS/CFT correspondence it can be identified as a source for an irrelevant operator in the dual CFT. The presence of the logarithmic falloff may be interpreted as the fact that the dual CFT would be a logarithmic conformal field theory.

Alishahiha, Mohsen [School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Naseh, Ali [School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of)

2010-11-15T23:59:59.000Z

314

Gravity dual of spatially modulated phase  

SciTech Connect (OSTI)

We show that the five-dimensional Maxwell theory with the Chern-Simons term is tachyonic in the presence of a constant electric field. When coupled to gravity, a sufficiently large Chern-Simons coupling causes instability of the Reissner-Nordstroem black holes in anti-de Sitter space. The instability happens only at nonvanishing momenta, suggesting a spatially modulated phase in the holographically dual quantum field theory in (3+1) dimensions, with spontaneous current generation in a helical configuration. The three-charge extremal black hole in the type IIB superstring theory on AdS{sub 5}xS{sup 5} barely satisfies the stability condition.

Nakamura, Shin [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Ooguri, Hirosi [California Institute of Technology, Pasadena, California 91125 (United States); IPMU, University of Tokyo, Kashiwa 277-8586 (Japan); Park, Chang-Soon [California Institute of Technology, Pasadena, California 91125 (United States)

2010-02-15T23:59:59.000Z

315

Apparent horizon in fluid-gravity duality  

SciTech Connect (OSTI)

This article develops a computational framework for determining the location of boundary-covariant apparent horizons in the geometry of conformal fluid-gravity duality in arbitrary dimensions. In particular, it is shown up to second order and conjectured to hold to all orders in the gradient expansion that there is a unique apparent horizon which is covariantly expressible in terms of fluid velocity, temperature, and boundary metric. This leads to the first explicit example of an entropy current defined by an apparent horizon and opens the possibility that in the near-equilibrium regime there is preferred foliation of apparent horizons for black holes in asymptotically anti-de Sitter spacetimes.

Booth, Ivan; Heller, Michal P.; Plewa, Grzegorz; Spalinski, Michal [Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, A1C 5S7 (Canada); Instituut voor Theoretische Fysica, Universiteit van Amsterdam, Science Park 904, 1090 GL Amsterdam (Netherlands); Soltan Institute for Nuclear Studies, Hoza 69, 00-681 Warsaw (Poland); Soltan Institute for Nuclear Studies, Hoza 69, 00-681 Warsaw (Poland) and Physics Department, University of Bialystok, 15-424 Bialystok (Poland)

2011-05-15T23:59:59.000Z

316

Seven-dimensional gravity with topological terms  

SciTech Connect (OSTI)

We construct new seven-dimensional gravity by adding two topological terms to the Einstein-Hilbert action. For a certain choice of the coupling constants, these terms exist naturally in seven-dimensional gauged supergravity from the S{sup 4} reduction of eleven-dimensional supergravity with the R{sup 4} corrections. We derive the full set of the equations of motion. We find that the static spherically-symmetric black holes are unmodified by the topological terms. We obtain squashed AdS{sub 7}, and also squashed seven spheres and Q{sup 111} spaces in Euclidean signature.

Lue, H. [China Economics and Management Academy Central, University of Finance and Economics, Beijing 100081 (China); Institute for Advanced Study, Shenzhen University, Nanhai Ave 3688, Shenzhen 518060 (China); Pang Yi [Key Laboratory of Frontiers in Theoretical Physics Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2010-04-15T23:59:59.000Z

317

Fractal Spacetime Structure in Asymptotically Safe Gravity  

E-Print Network [OSTI]

Four-dimensional Quantum Einstein Gravity (QEG) is likely to be an asymptotically safe theory which is applicable at arbitrarily small distance scales. On sub-Planckian distances it predicts that spacetime is a fractal with an effective dimensionality of 2. The original argument leading to this result was based upon the anomalous dimension of Newton's constant. In the present paper we demonstrate that also the spectral dimension equals 2 microscopically, while it is equal to 4 on macroscopic scales. This result is an exact consequence of asymptotic safety and does not rely on any truncation. Contact is made with recent Monte Carlo simulations.

O. Lauscher; M. Reuter

2005-08-26T23:59:59.000Z

318

Confronting Dilaton-exchange gravity with experiments  

E-Print Network [OSTI]

We study the experimental constraints on theories, where the equivalence principle is violated by dilaton-exchange contributions to the usual graviton-exchange gravity. We point out that in this case it is not possible to have any CPT violation and hence there is no constraint from the CPT violating measurements in the $K-$system. The most stringent bound is obtained from the $K_L - K_S$ mass difference. In contrast, neither neutrino oscillation experiments nor neutrinoless double beta decay imply significant constraints.

H. V. Klapdor-Kleingrothaus; H. Ps; U. Sarkar

2000-08-16T23:59:59.000Z

319

Gamma Ray Burst Neutrinos Probing Quantum Gravity  

E-Print Network [OSTI]

Very high energy, short wavelength, neutrinos may interact with the space-time foam predicted by theories of quantum gravity. They would propagate like light through a crystal lattice and be delayed, with the delay depending on the energy. This will appear to the observer as a violation of Lorenz invariance. Back of the envelope calculations imply that observations of neutrinos produced by gamma ray bursts may reach Planck-scale sensitivity. We revisit the problem considering two essential complications: the imprecise timing of the neutrinos associated with their poorly understood production mechanism in the source and the indirect nature of their energy measurement made by high energy neutrino telescopes.

M. C. Gonzalez-Garcia; F. Halzen

2006-11-28T23:59:59.000Z

320

Ground Gravity Survey | Open Energy Information  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 No revision hasInformation Earth's Heat Jump to:Photon Place:Net Jump to: navigation,2004)EnergyGround Gravity

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

E-Print Network 3.0 - absolute gravity measurements Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

gravity measurements Search Powered by Explorit Topic List Advanced Search Sample search results for: absolute gravity measurements Page: << < 1 2 3 4 5 > >> 1 PROCEEDINGS,...

322

Gravity effects on partially premixed flames: an experimental-numerical investigation  

E-Print Network [OSTI]

Gravity effects on partially premixed flames: an experimental-numerical investigation Andrew J and interactions between the various reaction zones are strongly influenced by gravity. The flames widen

Aggarwal, Suresh K.

323

E-Print Network 3.0 - artificial gravity reveals Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

line is required. This value is computed from the surface gravity... focuses on different error sources, which influence the gravity ... Source: Schuh, Harald - Institut fr...

324

Inverted gravity, not inverted shape impairs biological motion perception  

E-Print Network [OSTI]

Inverted gravity, not inverted shape impairs biological motion perception Nikolaus Trojetroje. Scrambling should therefore impair perception even more than inversion. Upright and inverted scrambled motion). Is the cause of the inversion effect inverted gravity? If this is the case upright scrambled motion should

Troje, Nikolaus

325

Remarks on Pure Spin Connection Formulations of Gravity  

E-Print Network [OSTI]

In the derivation of a pure spin connection action functional for gravity two methods have been proposed. The first starts from a first order lagrangian formulation, the second from a hamiltonian formulation. In this note we show that they lead to identical results for the specific cases of pure gravity with or without a cosmological constant.

Riccardo Capovilla; Ted Jacobson

1992-07-21T23:59:59.000Z

326

Mapping crustal thickness using marine gravity data: Methods and uncertainties  

E-Print Network [OSTI]

of petroleum systems within passive margins. However, direct measurements of crustal thickness are sparse geophysical data, to estimate crustal thickness. We evaluated alternative gravity inversion methodol- ogies, but economic considerations make gravity modeling a more practical approach for mapping crustal thickness over

Mller, Dietmar

327

Phenomenological Quantum Gravity: the birth of a new frontier?  

E-Print Network [OSTI]

In the last years a general consensus has emerged that, contrary to intuition, quantum-gravity effects may have relevant consequences for the propagation and interaction of high energy particles. This has given birth to the field of ``Phenomenological Quantum Gravity'' We review some of the aspects of this new, very exciting frontier of Physics.

R. Aloisio; P. Blasi; A. Galante; P. L. Ghia; A. F. Grillo; F. Mendez

2005-02-01T23:59:59.000Z

328

Constraints on Dark Energy Models from Weak Gravity Conjecture  

E-Print Network [OSTI]

We study the constraints on the dark energy model with constant equation of state parameter $w=p/\\rho$ and the holographic dark energy model by using the weak gravity conjecture. The combination of weak gravity conjecture and the observational data gives $wenergy model realized by a scalar field is in swampland.

Ximing Chen; Jie Liu; Yungui Gong

2008-06-15T23:59:59.000Z

329

Gravity waves excited by jets: Propagation versus generation R. Plougonven  

E-Print Network [OSTI]

Gravity waves excited by jets: Propagation versus generation R. Plougonven School of Mathematics imposed by the generation mechanism. In proceeding so, effects due to the propagation of the waves through simulations demonstrate that the propagation of inertia-gravity waves through horizontal deformation

Plougonven, Riwal

330

Perturbations of Nested Branes With Induced Gravity  

E-Print Network [OSTI]

We study the behaviour of weak gravitational fields in models where a 4D brane is embedded inside a 5D brane equipped with induced gravity, which in turn is embedded in a 6D spacetime. We consider a specific regularization of the branes internal structures where the 5D brane can be considered thin with respect to the 4D one. We find exact solutions corresponding to pure tension source configurations on the thick 4D brane, and study perturbations at first order around these background solutions. To perform the perturbative analysis, we adopt a bulk-based approach and we express the equations in terms of gauge invariant and master variables using a 4D scalar-vector-tensor decomposition. We then propose an ansatz on the behaviour of the perturbation fields when the thickness of the 4D brane goes to zero, which corresponds to configurations where gravity remains finite everywhere in the thin limit of the 4D brane. We study the equations of motion using this ansatz, and show that they give rise to a consistent set...

Sbisa', Fulvio

2014-01-01T23:59:59.000Z

331

A dynamical inconsistency of Horava gravity  

SciTech Connect (OSTI)

The dynamical consistency of the nonprojectable version of Horava gravity is investigated by focusing on the asymptotically flat case. It is argued that for generic solutions of the constraint equations the lapse must vanish asymptotically. We then consider particular values of the coupling constants for which the equations are tractable and in that case we prove that the lapse must vanish everywhere--and not only at infinity. Put differently, the Hamiltonian constraints are generically all second-class. We then argue that the same feature holds for generic values of the couplings, thus revealing a physical inconsistency of the theory. In order to cure this pathology, one might want to introduce further constraints but the resulting theory would then lose much of the appeal of the original proposal by Horava. We also show that there is no contradiction with the time-reparametrization invariance of the action, as this invariance is shown to be a so-called 'trivial gauge symmetry' in Horava gravity, hence with no associated first-class constraints.

Henneaux, Marc [Universite Libre de Bruxelles and International Solvay Institutes, ULB-Campus Plaine CP231, 1050 Brussels (Belgium); Centro de Estudios Cientificos (CECS), Casilla 1469, Valdivia (Chile); Kleinschmidt, Axel; Lucena Gomez, Gustavo [Universite Libre de Bruxelles and International Solvay Institutes, ULB-Campus Plaine CP231, 1050 Brussels (Belgium)

2010-03-15T23:59:59.000Z

332

Analogue model for quantum gravity phenomenology  

E-Print Network [OSTI]

So called "analogue models" use condensed matter systems (typically hydrodynamic) to set up an "effective metric" and to model curved-space quantum field theory in a physical system where all the microscopic degrees of freedom are well understood. Known analogue models typically lead to massless minimally coupled scalar fields. We present an extended "analogue space-time" programme by investigating a condensed-matter system - in and beyond the hydrodynamic limit - that is in principle capable of simulating the massive Klein-Gordon equation in curved spacetime. Since many elementary particles have mass, this is an essential step in building realistic analogue models, and an essential first step towards simulating quantum gravity phenomenology. Specifically, we consider the class of two-component BECs subject to laser-induced transitions between the components, and we show that this model is an example for Lorentz invariance violation due to ultraviolet physics. Furthermore our model suggests constraints on quantum gravity phenomenology in terms of the "naturalness problem" and "universality issue".

Silke Weinfurtner; Stefano Liberati; Matt Visser

2005-11-18T23:59:59.000Z

333

Bigravity and Lorentz-violating massive gravity  

SciTech Connect (OSTI)

Bigravity is a natural arena where a nonlinear theory of massive gravity can be formulated. If the interaction between the metrics f and g is nonderivative, spherically symmetric exact solutions can be found. At large distances from the origin, these are generically Lorentz-breaking bi-flat solutions (provided that the corresponding vacuum energies are adjusted appropriately). The spectrum of linearized perturbations around such backgrounds contains a massless as well as a massive graviton, with two physical polarizations each. There are no propagating vectors or scalars, and the theory is ghost free (as happens with certain massive gravities with explicit breaking of Lorentz invariance). At the linearized level, corrections to general relativity are proportional to the square of the graviton mass, and so there is no van Dam-Veltam-Zakharov discontinuity. Surprisingly, the solution of linear theory for a static spherically symmetric source does not agree with the linearization of any of the known exact solutions. The latter coincide with the standard Schwarzschild-(anti)-de Sitter solutions of general relativity, with no corrections at all. Another interesting class of solutions is obtained where f and g are proportional to each other. The case of bi-de Sitter solutions is analyzed in some detail.

Blas, D.; Garriga, J. [ICC, Departament de Fisica Fonamental, Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain); Deffayet, C. [APC, Batiment Condorcet, 10 rue Alice Domont et Leonie Duquet, 75205 Paris Cedex 13 (France); GReCO/IAP, 98 bis Boulevard Arago, 75014 Paris (France)

2007-11-15T23:59:59.000Z

334

Non-trivial 2+1-Dimensional Gravity  

E-Print Network [OSTI]

We analyze 2+1-dimensional gravity in the framework of quantum gauge theory. We find that Einstein gravity has a trivial physical subspace which reflects the fact that the classical solution in empty space is flat. Therefore we study massive gravity which is not trivial. In the limit of vanishing graviton mass we obtain a non-trivial massless theory different from Einstein gravity. We derive the interaction from descent equations and obtain the cosmological topologically massive gravity. However, in addition to Einstein and Chern-Simons coupling we need coupling to fermionic ghost and anti-ghost fields and to a vector-graviton field with the same mass as the graviton.

D. R. Grigore; G. Scharf

2010-08-07T23:59:59.000Z

335

Superconducting magnet  

DOE Patents [OSTI]

A superconducting magnet designed to produce magnetic flux densities of the order of 4 to 5 Webers per square meter is constructed by first forming a cable of a plurality of matrixed superconductor wires with each wire of the plurality insulated from each other one. The cable is shaped into a rectangular cross-section and is wound with tape in an open spiral to create cooling channels. Coils are wound in a calculated pattern in saddle shapes to produce desired fields, such as dipoles, quadrupoles, and the like. Wedges are inserted between adjacent cables as needed to maintain substantially radial placement of the long dimensions of cross sections of the cables. After winding, individual strands in each of the cables are brought out to terminals and are interconnected to place all of the strands in series and to maximize the propagation of a quench by alternating conduction from an inner layer to an outer layer and from top half to bottom half as often as possible. Individual layers are separated from others by spiraled aluminum spacers to facilitate cooling. The wound coil is wrapped with an epoxy tape that is cured by heat and then machined to an interference fit with an outer aluminum pipe which is then affixed securely to the assembled coil by heating it to make a shrink fit. In an alternate embodiment, one wire of the cable is made of copper or the like to be heated externally to propagate a quench.

Satti, John A. (Naperville, IL)

1980-01-01T23:59:59.000Z

336

Interface Magnetism in Multiferroics  

E-Print Network [OSTI]

1.2.1 Magnetism . . . . . . . . . . . . . . . . . . . 1.2.2domain walls . . . . . 3 Magnetism of domain walls in BiFeOof electrical control of magnetism in mixed phase BiFeO 3

He, Qing

2011-01-01T23:59:59.000Z

337

Nanostructured magnetic materials  

E-Print Network [OSTI]

Magnetism and Magnetic Materials Conference, Atlanta, GA (Nanostructured Magnetic Materials by Keith T. Chan Doctor ofinduced by a Si-based material occurs at a Si/Ni interface

Chan, Keith T.

2011-01-01T23:59:59.000Z

338

Testing Chern-Simons modified gravity with orbiting superconductive gravity gradiometers --- The non-dynamical formulation  

E-Print Network [OSTI]

High precision Superconductivity Gravity Gradiometers (SGG) are powerful tools for relativistic experiments. In this paper, we work out the tidal signals in non-dynamical Chern-Simons modified gravity, which could be measured by orbiting SGGs around Earth. We find that, with proper orientations of multi-axes SGGs, the tidal signals from the Chern-Simons modification can be isolated in the combined data of different axes. Furthermore, for three-axes SGGs, such combined data is the trace of the total tidal matrix, which is invariant under the rotations of SGG axes and thus free from axis pointing errors. Following nearly circular orbits, the tests of the parity-violating Chern-Simons modification and the measurements of the gravitomagnetic sector in parity-conserving metric theories can be carried out independently in the same time. A first step analysis on noise sources is also included.

Qiang, Li-E

2015-01-01T23:59:59.000Z

339

Testing Chern-Simons modified gravity with orbiting superconductive gravity gradiometers --- The non-dynamical formulation  

E-Print Network [OSTI]

High precision Superconductivity Gravity Gradiometers (SGG) are powerful tools for relativistic experiments. In this paper, we work out the tidal signals in non-dynamical Chern-Simons modified gravity, which could be measured by orbiting SGGs around Earth. We find that, with proper orientations of multi-axes SGGs, the tidal signals from the Chern-Simons modification can be isolated in the combined data of different axes. Furthermore, for three-axes SGGs, such combined data is the trace of the total tidal matrix, which is invariant under the rotations of SGG axes and thus free from axis pointing errors. Following nearly circular orbits, the tests of the parity-violating Chern-Simons modification and the measurements of the gravitomagnetic sector in parity-conserving metric theories can be carried out independently in the same time. A first step analysis on noise sources is also included.

Li-E Qiang; Peng Xu

2015-02-16T23:59:59.000Z

340

Gravity-anti-Gravity Symmetric Mini-Superspace: Quantum Entanglement and Cosmological Scale Factor Grid  

E-Print Network [OSTI]

A gravity-anti-gravity (GaG) odd linear dilaton action offers an eternal inflation evolution governed by the unified (cosmological constant plus radiation) equation of state $\\rho-3P=4\\Lambda$. At the mini superspace level, a 'two-particle' variant of the no-boundary proposal, notably 'one-particle' energy dependent, is encountered. While a GaG-odd wave function can only host a weak Big Bang boundary condition, albeit for any $k$, a strong Big Bang boundary condition requires a GaG-even entangled wave function, and singles out $k=0$ flat space. The locally most probable values for the cosmological scale factor and the dilaton field form a grid $\\{a^2,a\\phi\\}\\sim\\sqrt{4n_1+1}\\pm\\sqrt{4n_2+1}$.

Aharon Davidson; Tomer Ygael

2014-10-22T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

SUPERCONDUCTING MAGNETIC ENERGY STORAGE  

E-Print Network [OSTI]

Superconducting 30-MJ Energy Storage Coil", Proc. 19 80 ASC,Superconducting Magnetic Energy Storage Plant", IEEE Trans.SlIperconducting Magnetic Energy Storage Unit", in Advances

Hassenzahl, W.

2011-01-01T23:59:59.000Z

342

SUPERCONDUCTING MAGNETIC ENERGY STORAGE  

E-Print Network [OSTI]

Design of the BPA Superconducting 30-MJ Energy Storagefor a Utility Scale Superconducting Magnetic Energy Storagefor a Lnrge Scale Superconducting Magnetic Energy Storage

Hassenzahl, W.

2011-01-01T23:59:59.000Z

343

CONDITIONS FOR TRANSVERSE WAVES PROPAGATION ALONG THIN MAGNETIC FLUX TUBES ON THE SUN  

SciTech Connect (OSTI)

The propagation of kink waves in the thin gravity stratified flux tubes with a generalized magnetic field distribution model is considered in cylindrical geometry. The new kink wave equations for both wave variables are obtained. It is shown that the inclusion of the radial component of an unperturbed tube magnetic field sufficiently transforms the conditions for the propagation of transverse waves. It is demonstrated that, for the models of isothermal and polytropic atmosphere in the tube and its environment, the propagation of kink waves along thin magnetic flux tubes is cutoff-free.

Lopin, Igor [Ussuriisk Astrophysical Observatory, Russian Academy of Sciences, Ussuriisk (Russian Federation); Nagorny, Ivan, E-mail: lopin78@mail.ru [Institute of Automation and Control Processes FEB RAS, Vladivostok (Russian Federation)

2013-09-10T23:59:59.000Z

344

Semiclassical approximation to supersymmetric quantum gravity  

SciTech Connect (OSTI)

We develop a semiclassical approximation scheme for the constraint equations of supersymmetric canonical quantum gravity. This is achieved by a Born-Oppenheimer type of expansion, in analogy to the case of the usual Wheeler-DeWitt equation. The formalism is only consistent if the states at each order depend on the gravitino field. We recover at consecutive orders the Hamilton-Jacobi equation, the functional Schroedinger equation, and quantum gravitational correction terms to this Schroedinger equation. In particular, the following consequences are found: (i) the Hamilton-Jacobi equation and therefore the background spacetime must involve the gravitino, (ii) a (many-fingered) local time parameter has to be present on super Riem {sigma} (the space of all possible tetrad and gravitino fields) (iii) quantum supersymmetric gravitational corrections affect the evolution of the very early Universe. The physical meaning of these equations and results, in particular, the similarities to and differences from the pure bosonic case, are discussed.

Kiefer, Claus; Lueck, Tobias; Moniz, Paulo [Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Strasse 77, 50937 Cologne (Germany); Astronomy Unit, School of Mathematical Sciences, Queen Mary College, University of London, Mile End Road, London E1 4NS (United Kingdom)

2005-08-15T23:59:59.000Z

345

QCD thermodynamics using five-dimensional gravity  

SciTech Connect (OSTI)

We calculate the critical temperature and free energy of the gluon plasma using the dilaton potential [B. Galow, E. Megias, J. Nian, and H. J. Pirner, Nucl. Phys. B834, 330 (2010).] in the gravity theory of anti-de Sitter/QCD. The finite temperature observables are calculated in two ways: first, from the Page-Hawking computation of the free energy, and secondly using the Bekenstein-Hawking proportionality of the entropy with the area of the horizon. Renormalization is well defined, because the T=0 theory has asymptotic freedom. We further investigate the change of the critical temperature with the number of flavors induced by the change of the running coupling constant in the quenched theory. The finite temperature behavior of the speed of sound, spatial string tension and vacuum expectation value of the Polyakov loop follow from the corresponding string theory in AdS{sub 5}.

Megias, E.; Veschgini, K. [Institute for Theoretical Physics, University of Heidelberg (Germany); Pirner, H. J. [Institute for Theoretical Physics, University of Heidelberg (Germany); Max Planck Institute for Nuclear Physics, Heidelberg (Germany)

2011-03-01T23:59:59.000Z

346

More on massive 3D gravity  

SciTech Connect (OSTI)

We explore the space of static solutions of the recently discovered three-dimensional 'new massive gravity' (NMG), allowing for either sign of the Einstein-Hilbert term and a cosmological term parametrized by a dimensionless constant {lambda}. For {lambda}=-1 we find black hole solutions asymptotic (but not isometric) to the unique (anti) de Sitter [(A)dS] vacuum, including extremal black holes that interpolate between this vacuum and (A)dS{sub 2}xS{sup 1}. We also investigate unitarity of linearized NMG in (A)dS vacua. We find unitary theories for some dS vacua, but (bulk) unitarity in AdS implies negative central charge of the dual conformal field theories (CFT), except for {lambda}=3 where the central charge vanishes and the bulk gravitons are replaced by 'massive photons'. A similar phenomenon is found in the massless limit of NMG, for which the linearized equations become equivalent to Maxwell's equations.

Bergshoeff, Eric A.; Hohm, Olaf [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Townsend, Paul K. [Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

2009-06-15T23:59:59.000Z

347

Gravity dual of metastable dynamical supersymmetry breaking  

SciTech Connect (OSTI)

Metastable, supersymmetry-breaking configurations can be created in flux geometries by placing antibranes in warped throats. Via gauge/gravity duality, such configurations should have an interpretation as supersymmetry-breaking states in the dual field theory. In this paper, we perturbatively determine the asymptotic supergravity solutions corresponding to D3-brane probes placed at the tip of the cascading warped deformed conifold geometry, which is dual to an SU(N+M)xSU(N) gauge theory. The backreaction of the antibranes has the effect of introducing imaginary anti-self-dual flux, squashing the compact part of the space and forcing the dilaton to run. Using the generalization of holographic renormalization to cascading geometries, we determine the expectation values of operators in the dual field theory in terms of the asymptotic values of the supergravity fields.

DeWolfe, Oliver [Department of Physics, 390 UCB, University of Colorado, Boulder, Colorado 80309 (United States); Kachru, Shamit; Mulligan, Michael [Department of Physics and SLAC, Stanford University, Stanford, California 94305/94309 (United States)

2008-03-15T23:59:59.000Z

348

Brane f(R) gravity cosmologies  

SciTech Connect (OSTI)

By the application of the generalized Israel junction conditions we derive cosmological equations for the fourth-order f(R) brane gravity and study their cosmological solutions. We show that there exists a nonstatic solution which describes a four-dimensional de Sitter (dS{sub 4}) brane embedded in a five-dimensional anti-de Sitter (AdS{sub 5}) bulk for a vanishing Weyl tensor contribution. On the other hand, for the case of a nonvanishing Weyl tensor contribution, there exists a static brane solution only. We claim that in order to get some more general nonstatic f(R) brane configurations, one needs to admit a dynamical matter energy-momentum tensor in the bulk rather than just a bulk cosmological constant.

Balcerzak, Adam; DaPbrowski, Mariusz P. [Institute of Physics, University of Szczecin, Wielkopolska 15, 70-451 Szczecin (Poland)

2010-06-15T23:59:59.000Z

349

Flat Spacetime Vacuum in Loop Quantum Gravity  

E-Print Network [OSTI]

We construct a state in the loop quantum gravity theory with zero cosmological constant, which should correspond to the flat spacetime vacuum solution. This is done by defining the loop transform coefficients of a flat connection wavefunction in the holomorphic representation which satisfies all the constraints of quantum General Relativity and it is peaked around the flat space triads. The loop transform coefficients are defined as spin foam state sum invariants of the spin networks embedded in the spatial manifold for the SU(2) quantum group. We also obtain an expression for the vacuum wavefunction in the triad represntation, by defining the corresponding spin networks functional integrals as SU(2) quantum group state sums.

A. Mikovic

2004-04-06T23:59:59.000Z

350

Gravitational Waves in Ghost Free Bimetric Gravity  

E-Print Network [OSTI]

We obtain a set of exact gravitational wave solutions for the ghost free bimetric theory of gravity. With a flat reference metric, the theory admits the vacuum Brinkmann plane wave solution for suitable choices of the coefficients of different terms in the interaction potential. An exact gravitational wave solution corresponding to a massive scalar mode is also admitted for arbitrary choice of the coefficients with the reference metric being proportional to the spacetime metric. The proportionality factor and the speed of the wave are calculated in terms of the parameters of the theory. We also show that a F(R) extension of the theory admits similar solutions but in general is plagued with ghost instabilities.

Morteza Mohseni

2012-11-15T23:59:59.000Z

351

A length operator for canonical quantum gravity  

E-Print Network [OSTI]

We construct an operator that measures the length of a curve in four-dimensional Lorentzian vacuum quantum gravity. We work in a representation in which a $SU(2)$ connection is diagonal and it is therefore surprising that the operator obtained after regularization is densely defined, does not suffer from factor ordering singularities and does not require any renormalization. We show that the length operator admits self-adjoint extensions and compute part of its spectrum which like its companions, the volume and area operators already constructed in the literature, is purely discrete and roughly is quantized in units of the Planck length. The length operator contains full and direct information about all the components of the metric tensor which faciliates the construction of a new type of weave states which approximate a given classical 3-geometry.

T. Thiemann

1996-06-29T23:59:59.000Z

352

Bi-metric Gravity and "Dark Matter"  

E-Print Network [OSTI]

We present a bi-metric theory of gravity containing a length scale of galactic size. For distances less than this scale the theory satisfies the standard tests of General Relativity. For distances greater than this scale the theory yields an effective gravitational constant much larger than the locally observed value of Newton's constant. The transition from one regime to the other through the galactic scale can explain the observed rotation curves of galaxies and hence the effects normally attributed to the presence of dark matter. Phenomena on an extragalactic scale such as galactic clusters and the expansion of the universe are controlled by the enhanced gravitational coupling. This provides an explanation of the missing matter normally invoked to account for the observed value of Hubble's constant in relation to observed matter.

I. T. Drummond

2000-08-18T23:59:59.000Z

353

Solar system tests of Ho?ava-Lifshitz gravity  

E-Print Network [OSTI]

Recently, a renormalizable gravity theory with higher spatial derivatives in four dimensions was proposed by Ho\\v{r}ava. The theory reduces to Einstein gravity with a non-vanishing cosmological constant in IR, but it has improved UV behaviors. The spherically symmetric black hole solutions for an arbitrary cosmological constant, which represent the generalization of the standard Schwarzschild-(A)dS solution, has also been obtained for the Ho\\v{r}ava-Lifshitz theory. The exact asymptotically flat Schwarzschild type solution of the gravitational field equations in Ho\\v{r}ava gravity contains a quadratic increasing term, as well as the square root of a fourth order polynomial in the radial coordinate, and it depends on one arbitrary integration constant. The IR modified Ho\\v{r}ava gravity seems to be consistent with the current observational data, but in order to test its viability more observational constraints are necessary. In the present paper we consider the possibility of observationally testing Ho\\v{r}ava gravity at the scale of the Solar System, by considering the classical tests of general relativity (perihelion precession of the planet Mercury, deflection of light by the Sun and the radar echo delay) for the spherically symmetric black hole solution of Ho\\v{r}ava-Lifshitz gravity. All these gravitational effects can be fully explained in the framework of the vacuum solution of the gravity. Moreover, the study of the classical general relativistic tests also constrain the free parameter of the solution.

Tiberiu Harko; Zoltan Kovcs; Francisco S. N. Lobo

2010-10-28T23:59:59.000Z

354

On the condensed matter scheme for emergent gravity and interferometry  

E-Print Network [OSTI]

An increasingly popular approach to quantum gravity rests on the idea that gravity (and maybe electromagnetism and the other gauge fields) might be an 'emergent phenomenon', in the sense of representing a collective behaviour resulting from a very different microscopic physics. A prominent example of this approach is the condensed matter scheme for quantum gravity, which considers the possibility that gravity emerges as an effective low-energy phenomenon from the quantum vacuum in a way similar to the emergence of collective excitations in condensed matter systems. This condensed matter view of the quantum vacuum clearly hints that, while the term 'ether' has been discredited for about a century, quantum gravity holds many (if not all) of the characteristics that have led people in the past to label various hypothetical substances with the term 'ether'. Since the last burst of enthusiasm for an ether, at the end of the 19th century, was brought to the grave in part by the performance of a series of important experiments in interferometry, the suggestion then naturally arises that maybe interferometry could also play a role in the current discussion on quantum gravity. We will highlight some aspects of this suggestion in the context of the condensed matter scheme for emergent gravity.

G. Jannes

2008-11-10T23:59:59.000Z

355

The Electromagnetic Quantum Gravity Theory On Quantum Inertia and the Einstein Principle of Equivalence  

E-Print Network [OSTI]

On a new approach to quantum gravity called Electro-Magnetic Quantum Gravity (EMQG) which is manifestly compatible with Cellular Automata (CA) theory and is based on a new theory of inertia (ref. 5) proposed by R. Haisch, A. Rueda, and H. Puthoff (which we modified and called Quantum Inertia). Newtonian Inertia is due to the strictly local electrical force interactions of matter with the surrounding charged virtual particles of the quantum vacuum. The sum of all the tiny electrical forces originating from each charged particle in the mass with respect to the vacuum, is the source of the total inertial force of a mass which opposes accelerated motion in Newton's law 'F = MA'. The problems and paradoxes of accelerated motion introduced in Mach's principle are solved by suggesting that the state of acceleration of the charged virtual particles of the quantum vacuum (with respect to a mass) serves as Newton's universal reference frame for the mass. Einstein's principle of equivalence of inertial and gravitational...

Ostoma, T; Ostoma, Tom; Trushyk, Mike

1999-01-01T23:59:59.000Z

356

Gravity inversion using a binary formulation Richard A. Krahenbuhl* and Yaoguo Li  

E-Print Network [OSTI]

Gravity inversion using a binary formulation Richard A. Krahenbuhl* and Yaoguo Li Gravity contrast that gives rise to zero gravity response on the surface. As a result, part of the salt structure structure using gravity data can be divided into two general categories. The first are interface inversions

357

GRAVITY PERTURBED CRAPPER WAVES BENJAMIN F. AKERS, DAVID M. AMBROSE & J. DOUGLAS WRIGHT  

E-Print Network [OSTI]

GRAVITY PERTURBED CRAPPER WAVES BENJAMIN F. AKERS, DAVID M. AMBROSE & J. DOUGLAS WRIGHT Abstract for but gravity is neglected. For certain parameter values, Crapper waves are known to have multi-valued height by the effect of gravity, yielding the existence of gravity-capillary waves nearby to the Crapper waves

Wright, J. Douglas

358

Gravity observations and 3D structure of the Earth , F. Chambat  

E-Print Network [OSTI]

1 Gravity observations and 3D structure of the Earth Y. Ricard1 , F. Chambat Laboratoire des, Michigan-Ann Harbor University, USA. Short title: GRAVITY OBSERVATIONS AND 3D STRUCTURE OF THE EARTH 1. The determination of Earth's gravity field has benefited from various gravity missions that have been launched

359

Simulations of Solar System observations in alternative theories of gravity  

E-Print Network [OSTI]

In this communication, we focus on the possibility to test General Relativity (GR) with radioscience experiments. We present simulations of observables performed in alternative theories of gravity using a software that simulates Range/Doppler signals directly from the space time metric. This software allows one to get the order of magnitude and the signature of the modifications induced by an alternative theory of gravity on radioscience signals. As examples, we present some simulations for the Cassini mission in Post-Einsteinian gravity (PEG) and with Standard Model Extension (SME).

A. Hees; B. Lamine; S. Reynaud; M. -T. Jaekel; C. Le Poncin-Lafitte; V. Lainey; A. Fzfa; J. -M. Courty; V. Dehant; P. Wolf

2013-02-27T23:59:59.000Z

360

On the black hole singularity issue in loop quantum gravity  

E-Print Network [OSTI]

This paper presents a brief overview on the issue of singularity resolution in loop quantum gravity presented at the Theory Canada IV conference at the Centre de Recherches Math\\'{e}matiques at the Universit\\'{e} de Montr\\'{e}al (June 4-7, 2008). The intended audience is theoretical physicists who are non-specialist in the field and therefore much of the technical detail is omitted here. Instead, a brief review of loop quantum gravity is presented, followed by a survey of previous and current work on results concerning the resolution of the classical black hole singularity within loop quantum gravity.

A. DeBenedictis

2009-07-05T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Flat space (higher spin) gravity with chemical potentials  

E-Print Network [OSTI]

We introduce flat space spin-3 gravity in the presence of chemical potentials and discuss some applications to flat space cosmology solutions, their entropy, free energy and flat space orbifold singularity resolution. Our results include flat space Einstein gravity with chemical potentials as special case. We discover novel types of phase transitions between flat space cosmologies with spin-3 hair and show that the branch that continuously connects to spin-2 gravity becomes thermodynamically unstable for sufficiently large temperature or spin-3 chemical potential.

Michael Gary; Daniel Grumiller; Max Riegler; Jan Rosseel

2014-11-24T23:59:59.000Z

362

Particles on a Circle in Canonical Lineal Gravity  

E-Print Network [OSTI]

A description of the canonical formulation of lineal gravity minimally coupled to N point particles in a circular topology is given. The Hamiltonian is found to be equal to the time-rate of change of the extrinsic curvature multiplied by the proper circumference of the circle. Exact solutions for pure gravity and for gravity coupled to a single particle are obtained. The presence of a single particle significantly modifies the spacetime evolution by either slowing down or reversing the cosmological expansion of the circle, depending upon the choice of parameters.

R. B. Mann

2001-05-02T23:59:59.000Z

363

Three-dimensional geologic structures from inversion of gravity anomalies  

E-Print Network [OSTI]

from an analysis of the sampling interval. 39 100 80 z0= 7km p = 1gm/cra R, /R6= 2 ~ 10 60 mgal . ~ ~ Numerical Integration Parker Method 40 20 64 56 48 40 32 km 10 a) 24 16 8 mgal ! km 10b) 16 8 Figure 10. Gravity profile across.... The input was the gravity profile shown in Figure 5. The model parameters are the same used by Oldenburg (1974, Figure 2, p. 533) for the case Z =6km. . . . . . . . . . . . . . . . 33 Comparison of gravity profiles from the cosine model and from...

Hinson, Charles Alvin

2012-06-07T23:59:59.000Z

364

Collapse of Magnetized Singular Isothermal Toroids: II. Rotation and Magnetic Braking  

E-Print Network [OSTI]

We study numerically the collapse of rotating, magnetized molecular cloud cores, focusing on rotation and magnetic braking during the main accretion phase of isolated star formation. Motivated by previous numerical work and analytic considerations, we idealize the pre-collapse core as a magnetized singular isothermal toroid, with a constant rotational speed everywhere. The collapse starts from the center, and propagates outwards in an inside-out fashion, satisfying exact self-similarity in space and time. For rotation rates and field strengths typical of dense low-mass cores, the main feature remains the flattening of the mass distribution along field lines -- the formation of a pseudodisk, as in the nonrotating cases. The density distribution of the pseudodisk is little affected by rotation. On the other hand, the rotation rate is strongly modified by pseudodisk formation. Most of the centrally accreted material reaches the vicinity of the protostar through the pseudodisk. The specific angular momentum can be greatly reduced on the way, by an order of magnitude or more, even when the pre-collapse field strength is substantially below the critical value for dominant cloud support. The efficient magnetic braking is due to the pinched geometry of the magnetic field in the pseudodisk, which strengthens the magnetic field and lengthens the level arm for braking. Both effects enhance the magnetic transport of angular momentum from inside to outside. The excess angular momentum is carried away in a low-speed outflow that has, despite claims made by other workers, little in common with observed bipolar molecular outflows. We discuss the implications of our calculations for the formation of true disks that are supported against gravity by rotation.

A. Allen; Z. Y. Li; F. H. Shu

2003-11-17T23:59:59.000Z

365

Hydrodynamics with conserved current via AdS/CFT correspondence in the Maxwell-Gauss-Bonnet gravity  

SciTech Connect (OSTI)

Using the AdS/CFT correspondence, we study the hydrodynamics with conserved current from the dual Maxwell-Gauss-Bonnet gravity. After constructing the perturbative solution to the first order based on the boosted black brane solution in the bulk Maxwell-Gauss-Bonnet gravity, we extract the stress tensor and conserved current of the dual conformal fluid on its boundary, and also find the effect of the Gauss-Bonnet term on the dual conformal fluid. Our results show that the Gauss-Bonnet term can affect the parameters such as the shear viscosity {eta}, entropy density s, thermal conductivity {kappa} and electrical conductivity {sigma}. However, it does not affect the so-called Wiedemann-Franz law which relates {kappa} to {sigma}, while it affects the ratio {eta}/s. In addition, another interesting result is that {eta}/s can also be affected by the bulk Maxwell field in our case, which is consistent with some previous results predicted through the Kubo formula. Moreover, the anomalous magnetic and vortical effects by adding the Chern-Simons term are also considered in our case in the Maxwell-Gauss-Bonnet gravity.

Hu Yapeng; Sun Peng; Zhang Jianhui [Center for High-Energy Physics, Peking University, Beijing 100871 (China)

2011-06-15T23:59:59.000Z

366

Magnetic Imaging Wolfgang Kuch  

E-Print Network [OSTI]

Magnetic Imaging Wolfgang Kuch Freie Universit¨at Berlin, Institut f¨ur Experimentalphysik, Arnimallee 14, 14195 Berlin, Germany kuch@physik.fu-berlin.de Abstract. Imaging of magnetic domains has- ern techniques is used nowadays routinely for magnetic imaging of magnetic ma- terials

Kuch, Wolfgang

367

Superconducting Magnet Division  

E-Print Network [OSTI]

Superconducting Magnet Division Ramesh Gupta 20T Target Solenoid with HTS Insert Solenoid Capture Laboratory New York, USA http://www.bnl.gov/magnets/staff/gupta #12;Superconducting Magnet Division Ramesh of HTS may significantly reduce the amount of Tungsten shielding · Summary #12;Superconducting Magnet

McDonald, Kirk

368

Mixed convection and heat management in the Mars gravity biosatellite  

E-Print Network [OSTI]

The Mars Gravity Biosatellite will house fifteen mice in a low Earth orbit satellite spinning about its longitudinal axis. The satellite's payload thermal control system will reject heat through the base of the payload ...

Marsh, Jesse B. (Jesse Benjamin)

2007-01-01T23:59:59.000Z

369

Status of Matter-Gravity Couplings in the SME  

E-Print Network [OSTI]

Constraints on Lorentz violation in matter-gravity couplings are summarized along with existing proposals to obtain sensitivities that exceed current limits by up to 11 orders of magnitude.

Tasson, Jay D

2013-01-01T23:59:59.000Z

370

Status of Matter-Gravity Couplings in the SME  

E-Print Network [OSTI]

Constraints on Lorentz violation in matter-gravity couplings are summarized along with existing proposals to obtain sensitivities that exceed current limits by up to 11 orders of magnitude.

Jay D. Tasson

2013-08-06T23:59:59.000Z

371

Hyperbolic Equations for Vacuum Gravity Using Special Orthonormal Frames  

E-Print Network [OSTI]

By adopting Nester's higher dimensional special orthonormal frames (HSOF) the tetrad equations for vacuum gravity are put into first order symmetric hyperbolic (FOSH) form with constant coefficients, independent of any time slicing or coordinate specialization.

Frank B. Estabrook; R. Steve Robinson; Hugo D. Wahlquist

2004-09-29T23:59:59.000Z

372

Gravity wave turbulence revealed by horizontal vibrations of the container  

E-Print Network [OSTI]

We experimentally study the role of the forcing on gravity-capillary wave turbulence. Previous laboratory experiments using spatially localized forcing (vibrating blades) have shown that the frequency power-law exponent of the gravity wave spectrum depends on the forcing parameters. By horizontally vibrating the whole container, we observe a spectrum exponent that does not depend on the forcing parameters for both gravity and capillary regimes. This spatially extended forcing leads to a gravity spectrum exponent in better agreement with the theory than by using a spatially localized forcing. The role of the vessel shape has been also studied. Finally, the wave spectrum is found to scale linearly with the injected power for both regimes whatever the forcing type used.

Bruno Issenmann; Eric Falcon

2012-12-20T23:59:59.000Z

373

Vacua and instantons of ghost-free massive gravity  

E-Print Network [OSTI]

Recently discovered models of ghost-free massive gravity and bigravity are characterized by a non-trivial potential that gives rise to a rich vacuum structure. We review maximally symmetric vacua of the de Rham-Gabadadze-Tolley (dRGT) massive gravity and of the Hassan-Rosen (HR) bigravity, and discuss their perturbative stability. In particular, we discuss perturbations about self-accelerating vacua in HR bigravity, and argue that, analogously to what was found in the case of dRGT gravity, some of them contain strongly coupled modes. We then show that it is impossible to construct regular instantons connecting different classically stable vacua of dRGT gravity without violating energy conservation or the null energy condition.

Minjoon Park; Lorenzo Sorbo

2012-12-12T23:59:59.000Z

374

New Gravity Wave Treatments for GISS Climate Models  

E-Print Network [OSTI]

Previous versions of GISS climate models have either used formulations of Rayleigh drag to represent unresolved gravity wave interactions with the model-resolved flow or have included a rather complicated treatment of ...

Geller, Marvin A.

375

Regional Gravity Survey of the Northern Great Salt Lake Desert...  

Open Energy Info (EERE)

navigation, search OpenEI Reference LibraryAdd to library Journal Article: Regional Gravity Survey of the Northern Great Salt Lake Desert and Adjacent Areas in Utah, Nevada, and...

376

Application Of Gravity And Deep Dipole Geoelectrics In The Volcanic...  

Open Energy Info (EERE)

Gravity And Deep Dipole Geoelectrics In The Volcanic Area Of Mt Etna (Sicily) Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: Application Of...

377

Geodesic multiplication as a tool for classical and quantum gravity  

E-Print Network [OSTI]

Algebraic systems called the local geodesic loops and their tangent Akivis algebras are considered. Their possible role in theory of gravity is considered. Quantum conditions for the infinitesimal quantum events are proposed.

Piret Kuusk; Eugen Paal

2008-03-08T23:59:59.000Z

378

Quantized gauge-affine gravity in the superfiber bundle approach  

SciTech Connect (OSTI)

The quantization of gauge-affine gravity within the superfiber bundle formalism is proposed. By introducing an even pseudotensorial 1-superform over a principal superfiber bundle with superconnection, we obtain the geometrical Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST transformations of the fields occurring in such a theory. Reducing the four-dimensional general affine group double-covering GA(4,R) to the Poincare group double-covering ISO(1,3) we also find the BRST and anti-BRST transformations of the fields present in Einstein's gravity. Furthermore, we give a prescription leading to the construction of both BRST-invariant gauge-fixing action for gauge-affine gravity and Einstein's gravity.

Meziane, A.; Tahiri, M. [Laboratoire de Physique Theorique, Universite d'Oran Es-senia, 31100 Oran (Algeria)

2005-05-15T23:59:59.000Z

379

Errata to "Flat Spacetime Vacuum in Loop Quantum Gravity"  

E-Print Network [OSTI]

We give the correct expressions for the spin network evaluations proposed in Class. Quant. Grav. 21 (2004) 3909 as the coefficients of the quantum gravity vacuum wavefunction in the spin network basis.

A. Mikovic

2006-06-19T23:59:59.000Z

380

Constraining gravity using entanglement in AdS/CFT  

E-Print Network [OSTI]

We investigate constraints imposed by entanglement on gravity in the context of holography. First, by demanding that relative entropy is positive and using the Ryu-Takayanagi entropy functional, we find certain constraints at a nonlinear level for the dual gravity. Second, by considering Gauss-Bonnet gravity, we show that for a class of small perturbations around the vacuum state, the positivity of the two point function of the field theory stress tensor guarantees the positivity of the relative entropy. Further, if we impose that the entangling surface closes off smoothly in the bulk interior, we find restrictions on the coupling constant in Gauss-Bonnet gravity. We also give an example of an anisotropic excited state in an unstable phase with broken conformal invariance which leads to a negative relative entropy.

Shamik Banerjee; Arpan Bhattacharyya; Apratim Kaviraj; Kallol Sen; Aninda Sinha

2014-07-09T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Gravity and its Mysteries: Some Thoughts and Speculations  

E-Print Network [OSTI]

I gave a rambling talk about gravity and its many mysteries at Chen-Ning Yang's 85th Birthday Celebration held in November 2007. I don't have any answers.

A. Zee

2008-05-14T23:59:59.000Z

382

The evolution of miscible gravity currents in horizontal porous layers  

E-Print Network [OSTI]

Gravity currents of miscible fluids in porous media are important to understand because they occur in important engineering projects, such as enhanced oil recovery and geologic CO[subscript 2] sequestration. These flows ...

Szulczewski, Michael Lawrence

383

An alternative derivation of the Minimal massive 3D gravity  

E-Print Network [OSTI]

By using the algebra of exterior forms and the first order formalism with constraints, an alternative derivation of the field equations for the Minimal massive 3D gravity model is presented.

Ahmet Baykal

2014-08-22T23:59:59.000Z

384

Ground Gravity Survey At Dixie Valley Geothermal Area (Iovenitti...  

Open Energy Info (EERE)

project area. These data were used in conjunction with past gravity data reported in by Smith et al (2001) and Blackwell et al (2005). The analysis of these data had not been...

385

Dust-shell Universe in the modified gravity scenario  

E-Print Network [OSTI]

The dynamics of the dust-shell model of universe is exactly solved for the modified Schwarzschild solution. This solution is used to derive the cosmology corresponding to the modified gravity.

Michael Maziashvili

2005-04-15T23:59:59.000Z

386

Absence of scalar hair in scalar-tensor gravity  

E-Print Network [OSTI]

Stationary, asymptotically flat black holes in scalar-tensor theories of gravity are studied. It is shown that such black holes have no scalar hair and are the same as in General Relativity.

Valerio Faraoni; Thomas P. Sotiriou

2013-03-04T23:59:59.000Z

387

Gravity-free hydraulic jumps and metal femtocups  

E-Print Network [OSTI]

Hydraulic jumps created by gravity are seen every day in the kitchen sink. We show that at small scales a circular hydraulic jump can be created in the absence of gravity, by surface tension. The theory is motivated by our experimental finding of a height discontinuity in spreading submicron molten metal droplets created by pulsed-laser ablation. By careful control of initial conditions, we show that this leads to solid femtolitre cups of gold, silver, copper, niobium and tin.

Rama Govindarajan; Manikandan Mathur; Ratul DasGupta; N. R. Selvi; Neena Susan John; G. U. Kulkarni

2006-10-03T23:59:59.000Z

388

Gravity Effects on Antimatter in the Standard-Model Extension  

E-Print Network [OSTI]

The gravitational Standard-Model Extension (SME) is the general field-theory based framework for the analysis of CPT and Lorentz violation. In this work we summarize the implications of Lorentz and CPT violation for antimatter gravity in the context of the SME. Implications of various attempts to place indirect limits on anomalous antimatter gravity are considered in the context of SME-based models.

Jay D. Tasson

2015-01-30T23:59:59.000Z

389

Gravity Effects on Antimatter in the Standard-Model Extension  

E-Print Network [OSTI]

The gravitational Standard-Model Extension (SME) is the general field-theory based framework for the analysis of CPT and Lorentz violation. In this work we summarize the implications of Lorentz and CPT violation for antimatter gravity in the context of the SME. Implications of various attempts to place indirect limits on anomalous antimatter gravity are considered in the context of SME-based models.

Tasson, Jay D

2015-01-01T23:59:59.000Z

390

NUT-Charged Black Holes in Gauss-Bonnet Gravity  

E-Print Network [OSTI]

We investigate the existence of Taub-NUT/bolt solutions in Gauss-Bonnet gravity and obtain the general form of these solutions in $d$ dimensions. We find that for all non-extremal NUT solutions of Einstein gravity having no curvature singularity at $r=N$, there exist NUT solutions in Gauss-Bonnet gravity that contain these solutions in the limit that the Gauss-Bonnet parameter $\\alpha$ goes to zero. Furthermore there are no NUT solutions in Gauss-Bonnet gravity that yield non-extremal NUT solutions to Einstein gravity having a curvature singularity at $r=N$ in the limit $% \\alpha \\to 0$. Indeed, we have non-extreme NUT solutions in $2+2k$ dimensions with non-trivial fibration only when the $2k$-dimensional base space is chosen to be $\\mathbb{CP}^{2k}$. We also find that the Gauss-Bonnet gravity has extremal NUT solutions whenever the base space is a product of 2-torii with at most a 2-dimensional factor space of positive curvature. Indeed, when the base space has at most one positively curved two dimensional space as one of its factor spaces, then Gauss-Bonnet gravity admits extreme NUT solutions, even though there a curvature singularity exists at $r=N$. We also find that one can have bolt solutions in Gauss-Bonnet gravity with any base space with factor spaces of zero or positive constant curvature. The only case for which one does not have bolt solutions is in the absence of a cosmological term with zero curvature base space.

M. H. Dehghani; R. B. Mann

2005-11-30T23:59:59.000Z

391

Stochastic Quantization of the Ho?ava Gravity  

E-Print Network [OSTI]

The stochastic quantization method is applied to the recent proposal by Ho\\v{r}ava for gravity. We show that in contrast to General Relativity, the Ho\\v{r}ava's action, satisfying the detailed balance condition, has a stable, non-perturbative quantum vacuum when the DeWitt parameter $\\lambda$ is not greater than 1/3, providing a possible candidate for consistent quantum gravity.

Fu-Wen Shu; Yong-Shi Wu

2009-06-09T23:59:59.000Z

392

Solar system constraints on R$^n$ gravity  

E-Print Network [OSTI]

Recently, gravitational microlensing has been investigated in the framework of the weak field limit of fourth order gravity theory. However, solar system data (i.e. planetary periods and light bending) can be used to put strong constraints on the parameters of this class of gravity theories. We find that these parameters must be very close to those corresponding to the Newtonian limit of the theory.

A. F. Zakharov; A. A. Nucita; F. De Paolis; G. Ingrosso

2006-11-02T23:59:59.000Z

393

A bird's eye view of f(R)-gravity  

E-Print Network [OSTI]

We survey the landscape of $f(R)$ theories of gravity in their various formulations, which have been used to model the cosmic acceleration as alternatives to dark energy and dark matter. Besides, we take into account the problem of gravitational waves in such theories. We discuss some successes of $f(R)$-gravity (where $f(R)$ is a generic function of Ricci scalar $R$), theoretical and experimental challenges that they face in order to satisfy minimal criteria for viability.

S. Capozziello; M. De Laurentis; V. Faraoni

2009-10-02T23:59:59.000Z

394

Entropy and Area of Black Holes in Loop Quantum Gravity  

E-Print Network [OSTI]

Simple arguments related to the entropy of black holes strongly constrain the spectrum of the area operator for a Schwarzschild black hole in loop quantum gravity. In particular, this spectrum is fixed completely by the assumption that the black hole entropy is maximum. Within the approach discussed, one arrives in loop quantum gravity at a quantization rule with integer quantum numbers $n$ for the entropy and area of a black hole.

I. B. Khriplovich

2002-03-31T23:59:59.000Z

395

Finite field-dependent symmetries in perturbative quantum gravity  

SciTech Connect (OSTI)

In this paper we discuss the absolutely anticommuting nilpotent symmetries for perturbative quantum gravity in general curved spacetime in linear and non-linear gauges. Further, we analyze the finite field-dependent BRST (FFBRST) transformation for perturbative quantum gravity in general curved spacetime. The FFBRST transformation changes the gauge-fixing and ghost parts of the perturbative quantum gravity within functional integration. However, the operation of such symmetry transformation on the generating functional of perturbative quantum gravity does not affect the theory on physical ground. The FFBRST transformation with appropriate choices of finite BRST parameter connects non-linear CurciFerrari and Landau gauges of perturbative quantum gravity. The validity of the results is also established at quantum level using BatalinVilkovisky (BV) formulation. -- Highlights: The perturbative quantum gravity is treated as gauge theory. BRST and anti-BRST transformations are developed in linear and non-linear gauges. BRST transformation is generalized by making it finite and field dependent. Connection between linear and non-linear gauges is established. Using BV formulation the results are established at quantum level also.

Upadhyay, Sudhaker, E-mail: sudhaker@boson.bose.res.in

2014-01-15T23:59:59.000Z

396

Minimal Liouville Gravity correlation numbers from Douglas string equation  

E-Print Network [OSTI]

We continue the study of $(q,p)$ Minimal Liouville Gravity with the help of Douglas string equation. We generalize the results of \\cite{Moore:1991ir}, \\cite{Belavin:2008kv}, where Lee-Yang series $(2,2s+1)$ was studied, to $(3,3s+p_0)$ Minimal Liouville Gravity, where $p_0=1,2$. We demonstrate that there exist such coordinates $\\tau_{m,n}$ on the space of the perturbed Minimal Liouville Gravity theories, in which the partition function of the theory is determined by the Douglas string equation. The coordinates $\\tau_{m,n}$ are related in a non-linear fashion to the natural coupling constants $\\lambda_{m,n}$ of the perturbations of Minimal Lioville Gravity by the physical operators $O_{m,n}$. We find this relation from the requirement that the correlation numbers in Minimal Liouville Gravity must satisfy the conformal and fusion selection rules. After fixing this relation we compute three- and four-point correlation numbers when they are not zero. The results are in agreement with the direct calculations in Minimal Liouville Gravity available in the literature \\cite{Goulian:1990qr}, \\cite{Zamolodchikov:2005sj}, \\cite{Belavin:2006ex}.

Alexander Belavin; Boris Dubrovin; Baur Mukhametzhanov

2014-09-11T23:59:59.000Z

397

Loop Quantum Gravity Phenomenology: Linking Loops to Observational Physics  

E-Print Network [OSTI]

Research during the last decade demonstrates that effects originating on the Planck scale are currently being tested in multiple observational contexts. In this review we discuss quantum gravity phenomenological models and their possible links to loop quantum gravity. Particle frameworks, including kinematic models, broken and deformed Poincar\\'e symmetry, non-commutative geometry, relative locality and generalized uncertainty principle, and field theory frameworks, including Lorentz violating operators in effective field theory and non-commutative field theory, are discussed. The arguments relating loop quantum gravity to models with modified dispersion relations are reviewed, as well as, arguments supporting the preservation of local Lorentz invariance. The phenomenology related to loop quantum cosmology is briefly reviewed, with a focus on possible effects that might be tested in the near future. As the discussion makes clear, there remains much interesting work to do in establishing the connection between the fundamental theory of loop quantum gravity and these specific phenomenological models, in determining observational consequences of the characteristic aspects of loop quantum gravity, and in further refining current observations. Open problems related to these developments are highlighted. characteristic aspects of loop quantum gravity, and in further refining current observations. Open problems related to these developments are highlighted.

Florian Girelli; Franz Hinterleitner; Seth A. Major

2012-12-13T23:59:59.000Z

398

Testing Horava-Lifshitz gravity using thin accretion disk properties  

SciTech Connect (OSTI)

Recently, a renormalizable gravity theory with higher spatial derivatives in four dimensions was proposed by Horava. The theory reduces to Einstein gravity with a nonvanishing cosmological constant in IR, but it has improved UV behaviors. The spherically symmetric black hole solutions for an arbitrary cosmological constant, which represent the generalization of the standard Schwarzschild-(anti) de Sitter solution, have also been obtained for the Horava-Lifshitz theory. The exact asymptotically flat Schwarzschild-type solution of the gravitational field equations in Horava gravity contains a quadratic increasing term, as well as the square root of a fourth order polynomial in the radial coordinate, and it depends on one arbitrary integration constant. The IR-modified Horava gravity seems to be consistent with the current observational data, but in order to test its viability more observational constraints are necessary. In the present paper we consider the possibility of observationally testing Horava gravity by using the accretion disk properties around black holes. The energy flux, the temperature distribution, the emission spectrum, as well as the energy conversion efficiency are obtained, and compared to the standard general relativistic case. Particular signatures can appear in the electromagnetic spectrum, thus leading to the possibility of directly testing Horava gravity models by using astrophysical observations of the emission spectra from accretion disks.

Harko, Tiberiu; Kovacs, Zoltan; Lobo, Francisco S. N. [Department of Physics and Center for Theoretical and Computational Physics, University of Hong Kong, Pok Fu Lam Road (Hong Kong); Centro de Fisica Teorica e Computacional, Faculdade de Ciencias da Universidade de Lisboa, Avenida Professor Gama Pinto 2, P-1649-003 Lisboa (Portugal)

2009-08-15T23:59:59.000Z

399

The Search for a Primordial Magnetic Field  

E-Print Network [OSTI]

Magnetic fields appear wherever plasma and currents can be found. As such, they thread through all scales in Nature. It is natural, therefore, to suppose that magnetic fields might have been formed within the high temperature environments of the big bang. Such a primordial magnetic field (PMF) would be expected to arise from and/or influence a variety of cosmological phenomena such as inflation, cosmic phase transitions, big bang nucleosynthesis, the cosmic microwave background (CMB) temperature and polarization anisotropies, the cosmic gravity wave background, and the formation of large-scale structure. In this review, we summarize the development of theoretical models for analyzing the observational consequences of a PMF. We also summarize the current state of the art in the search for observational evidence of a PMF. In particular we review the framework needed to calculate the effects of a PMF power spectrum on the CMB and the development of large scale structure. We summarize the current constraints on the PMF amplitude $B_\\lambda$ and the power spectral index $n_B$ and discuss prospects for better determining these quantities in the near future.

Dai G. Yamazaki; Toshitaka Kajino; Grant J. Mathew; Kiyotomo Ichiki

2012-04-16T23:59:59.000Z

400

Anti-gravity and/or dark matter contributions from massive gravity  

E-Print Network [OSTI]

Recently, the static spherically symmetric solution of the gravitational field equations have been found in theories describing massive graviton with spontaneous breaking of the Lorentz invariance. These solutions, which show off two integration constants instead of one in General Relativity, are discussed. They are candidates for modified black holes provided they are stable against small perturbations. These solutions may have both attractive or repulsive behavior at large distances. Therefore, these modified black holes may mimics the presence of dark matter or be a source of anti-gravity.

Bebronne, Michael V

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Characterising Vainshtein Solutions in Massive Gravity  

E-Print Network [OSTI]

We study static, spherically symmetric solutions in a recently proposed ghost-free model of non-linear massive gravity. We focus on a branch of solutions where the helicity-0 mode can be strongly coupled within certain radial regions, giving rise to the Vainshtein effect. We truncate the analysis to scales below the gravitational Compton wavelength, and consider the weak field limit for the gravitational potentials, while keeping all non-linearities of the helicity-0 mode. We determine analytically the number and properties of local solutions which exist asymptotically on large scales, and of local (inner) solutions which exist on small scales. We find two kinds of asymptotic solutions, one of which is asymptotically flat, while the other one is not, and also two types of inner solutions, one of which displays the Vainshtein mechanism, while the other exhibits a self-shielding behaviour of the gravitational field. We analyse in detail in which cases the solutions match in an intermediate region. The asymptotically flat solutions connect only to inner configurations displaying the Vainshtein mechanism, while the non asymptotically flat solutions can connect with both kinds of inner solutions. We show furthermore that there are some regions in the parameter space where global solutions do not exist, and characterise precisely in which regions of the phase space the Vainshtein mechanism takes place.

Fulvio Sbisa'; Gustavo Niz; Kazuya Koyama; Gianmassimo Tasinato

2014-06-17T23:59:59.000Z

402

Symmetry and Evolution in Quantum Gravity  

E-Print Network [OSTI]

We propose an operator constraint equation for the wavefunction of the Universe that admits genuine evolution. While the corresponding classical theory is equivalent to the canonical decomposition of General Relativity, the quantum theory makes predictions that are distinct from Wheeler-DeWitt cosmology. Furthermore, the local symmetry principle - and corresponding observables - of the theory have a direct interpretation in terms of a conventional gauge theory, where the gauge symmetry group is that of spatial conformal diffeomorphisms (that preserve the spatial volume of the Universe). The global evolution is in terms of an arbitrary parameter that serves only as an unobservable label for successive states of the Universe. Our proposal follows unambiguously from a suggestion of York whereby the independently specifiable initial data in the action principle of General Relativity is given by a conformal geometry and the spatial average of the York time on the spacelike hypersurfaces that bound the variation. Remarkably, such a variational principle uniquely selects the form of the constraints of the theory so that we can establish a precise notion of both symmetry and evolution in quantum gravity.

Sean Gryb; Karim Thebault

2014-03-25T23:59:59.000Z

403

Infrared modified gravity with dynamical torsion  

SciTech Connect (OSTI)

We continue the recent study of the possibility of constructing a consistent infrared modification of gravity by treating the vierbein and connection as independent dynamical fields. We present the generalized Fierz-Pauli equation that governs the propagation of a massive spin-2 mode in a model of this sort in the backgrounds of arbitrary torsionless Einstein manifolds. We show explicitly that the number of propagating degrees of freedom in these backgrounds remains the same as in flat space-time. This generalizes the recent result that the Boulware-Deser phenomenon does not occur in de Sitter and anti-de Sitter backgrounds. We find that, at least for weakly curved backgrounds, there are no ghosts in the model. We also discuss the interaction of sources in flat background. It is generally believed that the spinning matter is the only source of torsion. Our flat space study shows that this is not the case. We demonstrate that an ordinary conserved symmetric energy-momentum tensor can also generate torsion fields and thus excite massive spin-2 degrees of freedom.

Nikiforova, V. [Physics Department, Moscow State University, Moscow, 119899 (Russian Federation); Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, Moscow, 117312 (Russian Federation); Randjbar-Daemi, S. [Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, I-34014, Trieste (Italy); Rubakov, V. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, Moscow, 117312 (Russian Federation)

2009-12-15T23:59:59.000Z

404

Quantization of neutron in Earth's gravity  

E-Print Network [OSTI]

Gravity is the weakest of all four known forces in the universe. Quantum states of an elementary particle due to such a weak field is certainly very shallow and would therefore be an experimental challenge to detect. Recently an experimental attempt was made by V. V. Nesvizhevsky et al., Nature 415, 297 (2002), to measure the quantum states of a neutron, which shows that ground state and few excited states are \\sim 10^{-12}eV. We show that the energy of the ground state of a neutron confined above Earth's surface should be \\sim 10^{-37}eV. The experimentally observed energy levels are 10^{25} times deeper than the actual energy levels it should be and thus certainly not due to gravitational effect of Earth. Therefore the correct interpretation for the painstaking experimental results of Ref. \\cite{nes1} is due to the confinement potential of a one dimensional box of length L \\sim 50\\mu m, generated from the experimental setup as commented before \\cite{hansoon}. Our results thus creates a new challenge to the experimentalist to resolve the shallow energy levels of the neutron in Earth's gravitational field in future.

Pulak Ranjan Giri

2007-08-22T23:59:59.000Z

405

Exploring Cartan gravity with dynamical symmetry breaking  

E-Print Network [OSTI]

It has been known for some time that General Relativity can be regarded as a Yang-Mills-type gauge theory in a symmetry broken phase. In this picture the gravity sector is described by an $SO(1,4)$ or $SO(2,3)$ gauge field $A^{a}_{\\phantom{a}b\\mu}$ and Higgs field $V^{a}$ which acts to break the symmetry down to that of the Lorentz group $SO(1,3)$. This symmetry breaking mirrors that of electroweak theory. However, a notable difference is that while the Higgs field $\\Phi$ of electroweak theory is taken as a genuine dynamical field satisfying a Klein-Gordon equation, the gauge independent norm $V^2\\equiv \\eta_{ab}V^{a}V^{b}$ of the Higgs-type field $V^a$ is typically regarded as non-dynamical. Instead, in many treatments $V^a$ does not appear explicitly in the formalism or is required to satisfy $V^2 = \\mathrm{const.} \

H. F. Westman; T. G. Zlosnik

2014-03-24T23:59:59.000Z

406

Magnetic infrasound sensor  

DOE Patents [OSTI]

A magnetic infrasound sensor is produced by constraining a permanent magnet inside a magnetic potential well above the surface of superconducting material. The magnetic infrasound sensor measures the position or movement of the permanent magnet within the magnetic potential well, and interprets the measurements. Infrasound sources can be located and characterized by combining the measurements from one or more infrasound sensors. The magnetic infrasound sensor can be tuned to match infrasound source types, resulting in better signal-to-noise ratio. The present invention can operate in frequency modulation mode to improve sensitivity and signal-to-noise ratio. In an alternate construction, the superconductor can be levitated over a magnet or magnets. The system can also be driven, so that time resolved perturbations are sensed, resulting in a frequency modulation version with improved sensitivity and signal-to-noise ratio.

Mueller, Fred M. (Los Alamos, NM); Bronisz, Lawrence (Los Alamos, NM); Grube, Holger (Los Alamos, NM); Nelson, David C. (Santa Fe, NM); Mace, Jonathan L. (Los Alamos, NM)

2006-11-14T23:59:59.000Z

407

Roche Lobe Shapes for testing MOND-like Modified Gravity  

E-Print Network [OSTI]

Dark Matter (DM) theories and mass-tracing-light theories like MOND are by construction nearly degenerate on galactic scales, but not when it comes to the predicted shapes of Roche Lobes of a two-body system (e.g., a globular cluster orbiting a host galaxy). We show that the flattening of the Roche lobe is sensitive to the function mu(g) in modification of the law of gravity. We generalise the analytical results obtained in the deep-MOND limit by Zhao (2005, astro-ph/0511713 and astro-ph/0512425), and consider a binary in the framework of a MOND-like gravity modification function mu(g) or a general non-Keplerian gravity g \\propto R^-\\zeta. We give analytical expressions for the inner Lagrange point and Robe lobe axis ratios. The Roche lobe volume is proven to scale linearly with the true mass ratio, which applies to any mu(g), hence mass-tracing light models would overpredict the Roche lobe of a DM-poor globular cluster in a DM-rich host galaxy, and underpredict the size of a DM-richer dwarf satellite. The lobes are squashed with the flattening ~ 0.4 in the strong gravity and ~ 0.6 in the weak gravity; a precise measurement of the flattening could be used to verify the anisotropic dilation effect which is generic to MOND-like gravity. We generalise these results for extended mass distribution, and compare predicted Roche radii in different gravity theories with limiting radii of observed globular clusters and dwarf galaxy satellites.

HongSheng Zhao; LanLan Tian

2006-02-02T23:59:59.000Z

408

Journal of Magnetism and Magnetic Materials ] (  

E-Print Network [OSTI]

magnetic properties were measured with a vibrating sample magnetometer. The mass-specific power loss.40.Rs Keywords: Nanocrystalline alloys; Amorphous alloys; Field annealing; Power loss; Soft magnets the hysteretic power loss while maintaining high-temperature operability [4]. Other goals have included studies

McHenry, Michael E.

409

Recent lunar magnetism  

E-Print Network [OSTI]

The magnetization of young lunar samples (magnetic fields (e.g. core dynamo and long-lived impact plasma fields) have not been present within the last 1.5 Ga. To better ...

Buz, Jennifer

2011-01-01T23:59:59.000Z

410

Magnetic assisted statistical assembly  

E-Print Network [OSTI]

The objective of this thesis is to develop a process using magnetic forces to assemble micro-components into recesses on silicon based integrated circuits. Patterned SmCo magnetic thin films at the bottom of recesses are ...

Cheng, Diana I

2008-01-01T23:59:59.000Z

411

Resonant detection of axion mediated forces with Nuclear Magnetic Resonance  

E-Print Network [OSTI]

We describe a method based on precision magnetometry that can extend the search for axion-mediated spin-dependent forces by several orders of magnitude. By combining techniques used in nuclear magnetic resonance and short-distance tests of gravity, our approach can substantially improve upon current experimental limits set by astrophysics, and probe deep into the theoretically interesting regime for the Peccei-Quinn (PQ) axion. Our method is sensitive to PQ axion decay constants between 10^9 and 10^12 GeV or axion masses between 10^-6 and 10^-3 eV, independent of the cosmic axion abundance.

Asimina Arvanitaki; Andrew A. Geraci

2014-03-05T23:59:59.000Z

412

Unscreening modified gravity in the matter power spectrum  

E-Print Network [OSTI]

Viable modifications of gravity that may produce cosmic acceleration need to be screened in high-density regions such as the Solar System, where general relativity is well tested. Screening mechanisms also prevent strong anomalies in the large-scale structure and limit the constraints that can be inferred on these gravity models from cosmology. We find that by suppressing the contribution of the screened high-density regions in the matter power spectrum, allowing a greater contribution of unscreened low densities, modified gravity models can be more readily discriminated from the concordance cosmology. Moreover, by variation of density thresholds, degeneracies with other effects may be dealt with more adequately. Specializing to chameleon gravity as a worked example for screening in modified gravity, employing N-body simulations of f(R) models and the halo model of chameleon theories, we demonstrate the effectiveness of this method. We find that a percent-level measurement of the clipped power at k Solar System tests or distance indicators in unscreened dwarf galaxies.

Lucas Lombriser; Fergus Simpson; Alexander Mead

2015-01-20T23:59:59.000Z

413

Unscreening modified gravity in the matter power spectrum  

E-Print Network [OSTI]

Viable modifications of gravity that may produce cosmic acceleration need to be screened in high-density regions such as the Solar System, where general relativity is well tested. Screening mechanisms also prevent strong anomalies in the large-scale structure and limit the constraints that can be inferred on these gravity models from cosmology. We find that by suppressing the contribution of the screened high-density regions in the matter power spectrum, allowing a greater contribution of unscreened low densities, modified gravity models can be more readily discriminated from the concordance cosmology. Moreover, by variation of density thresholds, degeneracies with other effects may be dealt with more adequately. Specializing to chameleon gravity as a worked example for screening in modified gravity, employing N-body simulations of f(R) models and the halo model of chameleon theories, we demonstrate the effectiveness of this method. We find that a percent-level measurement of the clipped power at k < 0.3 h...

Lombriser, Lucas; Mead, Alexander

2015-01-01T23:59:59.000Z

414

Waste Isolation Pilot Plant (WIPP) site gravity survey and interpretation  

SciTech Connect (OSTI)

A portion of the WIPP site has been extensively surveyed with high-precision gravity. The main survey (in T22S, R31E) covered a rectangular area 2 by 4-1/3 mi encompassing all of WIPP site Zone II and part of the disturbed zone to the north of the site. Stations were at 293-ft intervals along 13 north-south lines 880 ft apart. The data are considered accurate to within a few hundredths of a milligal. Long-wavelength gravity anomalies correlate well with seismic time structures on horizons below the Castile Formation. Both the gravity anomalies and the seismic time structures are interpreted as resulting from related density and velocity variations within the Ochoan Series. Shorter wavelength negative gravity anomalies are interpreted as resulting from bulk density alteration in the vicinity of karst conduits. The WIPP gravity survey was unable to resolve low-amplitude, long-wavelength anomalies that should result from the geologic structures within the disturbed zone. It did indicate the degree and character of karst development within the surveyed area.

Barrows, L.J.; Fett, J.D.

1983-04-01T23:59:59.000Z

415

Magnetic susceptibility in QCD  

E-Print Network [OSTI]

Magnetic susceptibility in the deconfined phase of QCD is calculated in a closed form using a recent general expression for the quark gas pressure in magnetic field. Quark selfenergies are entering the result via Polyakov line factors and ensure the total paramagnetic effect, increasing with temperature. A generalized form of magnetic susceptibility in nonzero magnetic field suitable for experimental and lattice measurements is derived, showing a good agreement with available lattice data.

V. D. Orlovsky; Yu. A. Simonov

2014-05-12T23:59:59.000Z

416

Magnetism Theory Group / POSTECH Magnetism Theory Group / POSTECH  

E-Print Network [OSTI]

Magnetism Theory Group / POSTECH #12;Magnetism Theory Group / POSTECH #12;Magnetism Theory Group / POSTECH #12;Magnetism Theory Group / POSTECH #12;Magnetism Theory Group / POSTECH J.H . Park et al. #12;'s of FeinCsm e tal The chargeandorbitalordering geom etryin YB a C o 2 O 5 S. K. Kwon etal .Magnetism Theory

Min, Byung Il

417

Magnetic nanohole superlattices  

DOE Patents [OSTI]

A magnetic material is disclosed including a two-dimensional array of carbon atoms and a two-dimensional array of nanoholes patterned in the two-dimensional array of carbon atoms. The magnetic material has long-range magnetic ordering at a temperature below a critical temperature Tc.

Liu, Feng

2013-05-14T23:59:59.000Z

418

Noble gas magnetic resonator  

DOE Patents [OSTI]

Precise measurements of a precessional rate of noble gas in a magnetic field is obtained by constraining the time averaged direction of the spins of a stimulating alkali gas to lie in a plane transverse to the magnetic field. In this way, the magnetic field of the alkali gas does not provide a net contribution to the precessional rate of the noble gas.

Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

2014-04-15T23:59:59.000Z

419

National High Magnetic Field Laboratory  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

ANNUAL REPORT RESEARCH HIGHLIGHTS: CONDENSED MATTER SCIENCE Technique development, graphene, magnetism & magnetic materials, topological insulators, quantum fl uids & solids,...

420

Magnetic and gravity signatures and structural history of the Tas-mantid Seamounts  

E-Print Network [OSTI]

area. Brisbane -6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000 3000 Meters Selected References Weissel

Watts, A. B. "Tony"

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421

Geologic interpretation of gravity and magnetic data in the Salida region,  

Open Energy Info (EERE)

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 No revision has beenFfe2fb55-352f-473b-a2dd-50ae8b27f0a6TheoreticalFuelCellGemini SolarAssetsofLane: 2.Hawaii

422

On the UV structure of quantum unimodular gravity  

E-Print Network [OSTI]

It is a well known result that any formulation of unimodular gravity is classically equivalent to General Relativity (GR), however a debate exists in the literature about this equivalence at the quantum level. In this work, we investigate the UV quantum structure of a diffeomorphism invariant formulation of unimodular gravity using functional renormalisation group methods in a Wilsonian context. We show that the effective action of the unimodular theory acquires essentially the same form with that of GR in the UV, as well as that both theories share similar UV completions within the framework of the asymptotic safety scenario for quantum gravity. Furthermore, we find that in this context the unimodular theory can appear to be non--predictive due to an increasing number of relevant couplings at high energies, and explain how this unwanted feature is in the end avoided.

Ippocratis D. Saltas

2014-12-13T23:59:59.000Z

423

Gravity Effects on Neutrino Masses in Split Supersymmetry  

E-Print Network [OSTI]

The mass differences and mixing angles of neutrinos can neither be explained by R-Parity violating split supersymmetry nor by flavor blind quantum gravity alone. It is shown that combining both effects leads, within the allowed parameter range, to good agreement with the experimental results. The atmospheric mass is generated by supersymmetry through mixing between neutrinos and neutralinos, while the solar mass is generated by gravity through flavor blind dimension five operators. Maximal atmospheric mixing forces the tangent squared of the solar angle to be equal to 1/2. The scale of the quantum gravity operator is predicted within a 5% error, implying that the reduced Planck scale should lie around the GUT scale. In this way, the model is very predictive and can be tested at future experiments.

Marco Aurelio Diaz; Benjamin Koch; Boris Panes

2009-06-26T23:59:59.000Z

424

New Massive Gravity and AdS{sub 4} Counterterms  

SciTech Connect (OSTI)

We show that the recently proposed Dirac-Born-Infeld extension of new massive gravity emerges naturally as a counterterm in four-dimensional anti-de Sitter space (AdS{sub 4}). The resulting on-shell Euclidean action is independent of the cutoff at zero temperature. We also find that the same choice of counterterm gives the usual area law for the AdS{sub 4} Schwarzschild black hole entropy in a cutoff-independent manner. The parameter values of the resulting counterterm action correspond to a c=0 theory in the context of the duality between AdS{sub 3} gravity and two-dimensional conformal field theory. We rewrite this theory in terms of the gauge field that is used to recast 3D gravity as a Chern-Simons theory.

Jatkar, Dileep P. [Harish-Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad, 211019 (India); Sinha, Aninda [Centre for High Energy Physics, Indian Institute of Science, C. V. Raman Avenue, Bangalore 560012 (India)

2011-04-29T23:59:59.000Z

425

Asymptotic safety of gravity and the Higgs boson mass  

E-Print Network [OSTI]

There are indications that gravity is asymptotically safe. The Standard Model (SM) plus gravity could be valid up to arbitrarily high energies. Supposing that this is indeed the case and assuming that there are no intermediate energy scales between the Fermi and Planck scales we address the question of whether the mass of the Higgs boson $m_H$ can be predicted. For a positive gravity induced anomalous dimension $A_\\lambda>0$ the running of the quartic scalar self interaction $\\lambda$ at scales beyond the Planck mass is determined by a fixed point at zero. This results in $m_H=m_{\\rm min}=126$ GeV, with only a few GeV uncertainty. This prediction is independent of the details of the short distance running and holds for a wide class of extensions of the SM as well. For $A_\\lambda 0$ is favored by explicit computations existing in the literature.

Mikhail Shaposhnikov; Christof Wetterich

2010-01-12T23:59:59.000Z

426

Rapidly rotating neutron stars in $R$-squared gravity  

E-Print Network [OSTI]

$f(R)$ theories of gravity are one of the most popular alternative explanations for dark energy and therefore studying the possible astrophysical implications of these theories is an important task. In the present paper we make a substantial advance in this direction by considering rapidly rotating neutron stars in $R^2$ gravity. The results are obtained numerically and the method we use is non-perturbative and self-consistent. The neutron star properties, such as mass, radius and moment of inertia, are studied in detail and the results show that rotation magnifies the deviations from general relativity and the maximum mass and moment of inertia can reach very high values. This observation is similar to previous studies of rapidly rotating neutron stars in other alternative theories of gravity, such as the scalar-tensor theories, and it can potentially lead to strong astrophysical manifestations.

Yazadjiev, Stoytcho S; Kokkotas, Kostas D

2015-01-01T23:59:59.000Z

427

Conformal Gravity and the Alcubierre Warp Drive Metric  

E-Print Network [OSTI]

We present an analysis of the classic Alcubierre metric based on conformal gravity, rather than standard general relativity. The main characteristics of the resulting warp drive remain the same as in the original study by Alcubierre, namely that effective super-luminal motion is a viable outcome of the metric. We show that for particular choices of the shaping function, the Alcubierre metric in the context of conformal gravity does not violate the weak energy condition, as was the case of the original solution. In particular, the resulting warp drive does not require the use of exotic matter. Therefore, if conformal gravity is a correct extension of general relativity, super-luminal motion via an Alcubierre metric might be a realistic solution, thus allowing faster-than-light interstellar travel.

Varieschi, Gabriele U

2012-01-01T23:59:59.000Z

428

Conformal Gravity and the Alcubierre Warp Drive Metric  

E-Print Network [OSTI]

We present an analysis of the classic Alcubierre metric based on conformal gravity, rather than standard general relativity. The main characteristics of the resulting warp drive remain the same as in the original study by Alcubierre, namely that effective super-luminal motion is a viable outcome of the metric. We show that for particular choices of the shaping function, the Alcubierre metric in the context of conformal gravity does not violate the weak energy condition, as was the case of the original solution. In particular, the resulting warp drive does not require the use of exotic matter. Therefore, if conformal gravity is a correct extension of general relativity, super-luminal motion via an Alcubierre metric might be a realistic solution, thus allowing faster-than-light interstellar travel.

Gabriele U. Varieschi; Zily Burstein

2012-08-17T23:59:59.000Z

429

Galactic space-times in modified theories of gravity  

E-Print Network [OSTI]

We study Bertrand space-times (BSTs), which have been proposed as viable models of space-times seeded by galactic dark matter, in modified theories of gravity. We first critically examine the issue of galactic rotation curves in General Relativity, and establish the usefulness of BSTs to fit experimental data in this context. We then study BSTs in metric $f(R)$ gravity and in Brans-Dicke theories. For the former, the nature of the Newtonian potential is established, and we also compute the effective equation of state and show that it can provide good fits to some recent experimental results. For the latter, we calculate the Brans-Dicke scalar analytically in some limits and numerically in general, and find interesting constraints on the parameters of the theory. Our results provide evidence for the physical nature of Bertrand space-times in modified theories of gravity.

Dipanjan Dey; Kaushik Bhattacharya; Tapobrata Sarkar

2014-07-01T23:59:59.000Z

430

Magnetically attached sputter targets  

DOE Patents [OSTI]

An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material is described. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly. 11 figures.

Makowiecki, D.M.; McKernan, M.A.

1994-02-15T23:59:59.000Z

431

E-Print Network 3.0 - auxin transport gravity Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

gravity Search Powered by Explorit Topic List Advanced Search Sample search results for: auxin transport gravity Page: << < 1 2 3 4 5 > >> 1 lDispatch 1589 Plant tropisms: The ins...

432

E-Print Network 3.0 - artificial gravity hope Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Powered by Explorit Topic List Advanced Search Sample search results for: artificial gravity hope Page: << < 1 2 3 4 5 > >> 1 Gravity currents in cold fresh water Department of...

433

Separating Dark Physics from Physical Darkness: Minimalist Modified Gravity vs. Dark Energy  

E-Print Network [OSTI]

Modified Gravity vs. Dark Energy Dragan Huterer 1 and EricModi?ed Gravity vs. Dark Energy Dragan Huterer 1 and Eric V.arising from a physical dark energy or a modi?ed Fried- mann

Huterer, Dragan

2009-01-01T23:59:59.000Z

434

Nonlinear force-free modeling of the solar coronal magnetic field  

E-Print Network [OSTI]

The coronal magnetic field is an important quantity because the magnetic field dominates the structure of the solar corona. Unfortunately direct measurements of coronal magnetic fields are usually not available. The photospheric magnetic field is measured routinely with vector magnetographs. These photospheric measurements are extrapolated into the solar corona. The extrapolated coronal magnetic field depends on assumptions regarding the coronal plasma, e.g. force-freeness. Force-free means that all non-magnetic forces like pressure gradients and gravity are neglected. This approach is well justified in the solar corona due to the low plasma beta. One has to take care, however, about ambiguities, noise and non-magnetic forces in the photosphere, where the magnetic field vector is measured. Here we review different numerical methods for a nonlinear force-free coronal magnetic field extrapolation: Grad-Rubin codes, upward integration method, MHD-relaxation, optimization and the boundary element approach. We briefly discuss the main features of the different methods and concentrate mainly on recently developed new codes.

T. Wiegelmann

2008-01-18T23:59:59.000Z

435

Neutron stars in f(R) gravity with perturbative constraints  

SciTech Connect (OSTI)

We study the structure of neutron stars in f(R) gravity theories with perturbative constraints. We derive the modified Tolman-Oppenheimer-Volkov equations and solve them for a polytropic equation of state. We investigate the resulting modifications to the masses and radii of neutron stars and show that observations of surface phenomena alone cannot break the degeneracy between altering the theory of gravity versus choosing a different equation of state of neutron-star matter. On the other hand, observations of neutron-star cooling, which depends on the density of matter at the stellar interior, can place significant constraints on the parameters of the theory.

Cooney, Alan; DeDeo, Simon; Psaltis, Dimitrios [Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States); Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501 (United States); Departments of Astronomy and Physics, University of Arizona, Tucson, Arizona 85721 (United States)

2010-09-15T23:59:59.000Z

436

Baryogenesis in $f(R)$-Theories of Gravity  

E-Print Network [OSTI]

$f(R)$-theories of gravity are reviewed in the context of the so called gravitational baryogenesis. The latter is a mechanism for generating the baryon asymmetry in the Universe, and relies on the coupling between the Ricci scalar curvature $R$ and the baryon current. Gravity Lagrangians of the form ${\\cal L}(R)\\sim R^n$, where $n$ differs from 1 (the case of the General Relativity) only for tiny deviations of a few percent, are consistent with the current bounds on the observed baryon asymmetry.

G. Lambiase; G. Scarpetta

2006-10-12T23:59:59.000Z

437

Thermodynamics on the apparent horizon in generalized gravity theories  

E-Print Network [OSTI]

We present a general procedure to construct the first law of thermodynamics on the apparent horizon and illustrate its validity by examining it in some extended gravity theories. Applying this procedure, we can describe the thermodynamics on the apparent horizon in Randall-Sundrum braneworld imbedded in a nontrivial bulk. We discuss the mass-like function which was used to link Friedmann equation to the first law of thermodynamics and obtain its special case which gives the generalized Misner-Sharp mass in Lovelock gravity.

Shao-Feng Wu; Bin Wang; Guo-Hong Yang

2008-01-17T23:59:59.000Z

438

Time machines and traversable wormholes in modified theories of gravity  

E-Print Network [OSTI]

We review recent work on wormhole geometries in the context of modified theories of gravity, in particular, in f(R) gravity and with a nonminimal curvature-matter coupling, and in the recently proposed hybrid metric-Palatini theory. In principle, the normal matter threading the throat can be shown to satisfy the energy conditions and it is the higher order curvatures terms that sustain these wormhole geometries. We also briefly review the conversion of wormholes into time-machines, explore several of the time travel paradoxes and possible remedies to these intriguing side-effects in wormhole physics.

Francisco S. N. Lobo

2012-12-05T23:59:59.000Z

439

Spherically symmetric static spacetimes in vacuum f(T) gravity  

SciTech Connect (OSTI)

We show that Schwarzschild geometry remains as a vacuum solution for those four-dimensional f(T) gravitational theories behaving as ultraviolet deformations of general relativity. In the gentler context of three-dimensional gravity, we also find that the infrared-deformed f(T) gravities, like the ones used to describe the late cosmic speed up of the Universe, have as the circularly symmetric vacuum solution a Deser-de Sitter or a Banados, Teitelboim and Zanelli-like spacetime with an effective cosmological constant depending on the infrared scale present in the function f(T).

Ferraro, Rafael [Instituto de Astronomia y Fisica del Espacio, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina); Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina); Fiorini, Franco [Instituto de Astronomia y Fisica del Espacio, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina)

2011-10-15T23:59:59.000Z

440

Some not-so-common ideas about gravity  

E-Print Network [OSTI]

Most of the approaches to the construction of a theory of quantum gravity share some principles which do not have specific experimental support up to date. Two of these principles are relevant for our discussion: (i) the gravitational field should have a quantum description in certain regime, and (ii) any theory of gravity containing general relativity should be relational. We study in general terms the possible implications of assuming deviations from these principles, their compatibility with current experimental knowledge, and how can they affect future experiments.

Carballo-Rubio, Ral; Garay, Luis J

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Dynamics of the Cosmological Apparent Horizon: Surface Gravity & Temperature  

E-Print Network [OSTI]

In the context of thermodynamics applied to our cosmological apparent horizon, we explicit in greater details our previous work which established the Friedmann Equations from projection of Hayward's Unified First Law. In particular, we show that the dynamical Hayward-Kodama surface gravity is perfectly well-defined and is suitable for this derivation. We then relate this surface gravity to a physical notion of temperature, and show this has constant, positive sign for any kind of past-inner trapping horizons. Hopefully this will clarify the choice of temperature in a dynamical Friedmann-Lema\\^itre-Roberston-Walker spacetime.

Helou, Alexis

2015-01-01T23:59:59.000Z

442

SU(5) Grand Unification in Pure Gravity Mediation  

E-Print Network [OSTI]

We discuss the proton lifetime in pure gravity mediation models with non-universal Higgs soft masses. Pure gravity mediation offers a simple framework for studying SU(5) grand unified theories with a split supersymmetry like spectra. We find that for much of the parameter space gauge coupling unification is quite good leading to rather long lifetimes for the proton. However, for $m_{3/2}\\sim 60$ TeV and $\\tan\\beta\\sim 4$, for which gauge coupling unification is also good, the proton lifetime is short enough that it could be in reach of future experiments.

Jason L. Evans; Natsumi Nagata; Keith A. Olive

2015-01-30T23:59:59.000Z

443

Angular momentum extraction by gravity waves in the Sun  

E-Print Network [OSTI]

We review the behavior of the oscillating shear layer produced by gravity waves below the surface convection zone of the Sun. We show that, under asymmetric filtering produced by this layer, gravity waves of low spherical order, which are stochastically excited at the base of the convection zone of late type stars, can extract angular momentum from their radiative interior. The time-scale for this momentum extraction in a Sun-like star is of the order of 10^7 years. The process is particularly efficient in the central region, and it could produce there a slowly rotating core.

Suzanne Talon; Pawan Kumar; Jean-Paul Zahn

2002-06-27T23:59:59.000Z

444

Geodesic Structure of the Schwarzschild Black Hole in Rainbow Gravity  

E-Print Network [OSTI]

In this paper we study the geodesic structure of the Schwarzschild black hole in rainbow gravity analyzing the behavior of null and time-like geodesic. We find that the structure of the geodesics essentially does not change when the semi-classical effects are included. However, we can distinguish different scenarios if we take into account the effects of rainbow gravity. Depending on the type of rainbow functions under consideration, inertial and external observers see very different situations in radial and non radial motion of a test particles.

Carlos Leiva; Joel Saavedra; Jose Villanueva

2008-12-09T23:59:59.000Z

445

Gravity Survey of the Carson Sink - Data and Maps  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

Preliminary Interpretation of Results: The Carson Sink is a complex composite basin with several major depocenters (Figures 15 and 16). Major depocenters are present in the south?central, east?central, and northeastern parts of the basin. The distribution of gravity anomalies suggests a complex pattern of faulting in the subsurface of the basin, with many fault terminations, step?overs, and accommodation zones. The pattern of faulting implies that other, previously undiscovered blind geothermal systems are likely in the Carson Sink. The gravity survey was completed near the end of this project. Thus, more thorough analysis of the data and potential locations of blind geothermal systems is planned for future work.

Faulds, James E.

446

Quantum-Gravity Phenomenology and the DSR Ether Theories  

E-Print Network [OSTI]

Guided primarily by versions of a theoretical framework called Doubly Special Relativity, or DSR, that are supposed to entail speeds of light that vary with energy while preserving the relativity of inertial frames, quantum-gravity phenomenologists have recently been seeking clues to quantum gravity, in hoped-for differing times of arrival, for light of differing energies, from cosmologically distant sources. However, it has long been known that signals, of arbitrarily high speed in opposing directions, could be used to observe the translational state of (absolute) rest, as could signals of a fixed speed different from c. Consequently, the above versions of DSR are nonviable.

Kenneth M. Sasaki

2010-09-20T23:59:59.000Z

447

Qualitative properties of scalar-tensor theories of Gravity  

E-Print Network [OSTI]

The qualitative properties of spatially homogeneous stiff perfect fluid and minimally coupled massless scalar field models within general relativity are discussed. Consequently, by exploiting the formal equivalence under conformal transformations and field redefinitions of certain classes of theories of gravity, the asymptotic properties of spatially homogeneous models in a class of scalar-tensor theories of gravity that includes the Brans-Dicke theory can be determined. For example, exact solutions are presented, which are analogues of the general relativistic Jacobs stiff perfect fluid solutions and vacuum plane wave solutions, which act as past and future attractors in the class of spatially homogeneous models in Brans-Dicke theory.

A. A. Coley

1999-10-21T23:59:59.000Z

448

Geological structures from downward continuation of gravity anomalies  

E-Print Network [OSTI]

operator and two grid spacings (2 and 4 km), the depth to the upper surface of the source is about 4 km, with the center of' mass located at about 8 km. Comparison of these results with those for a sphere yield a density contrast of 0. 3 g/cc . Both... km 18. Downward-continuation residual gravity map and profile at the depth of 6 km. Contours in mGals. Grid spacing 4 km by 4 km 19. Downward-continuation residual gravity map and profile at the depth of 8 km. Contours in mGals. Grid spacing 4 km...

Yao, Chia-Chi George

2012-06-07T23:59:59.000Z

449

On the new massive gravity and AdS/CFT  

E-Print Network [OSTI]

Demanding the existence of a simple holographic $c$-theorem, it is shown that a general (parity preserving) theory of gravity in 2+1 dimensions involving upto four derivative curvature invariants reduces to the new massive gravity theory. We consider extending the theory including upto six derivative curvature invariants. Black hole solutions are presented and consistency with 1+1 CFTs is checked. We present evidence that bulk unitarity is still in conflict with a positive CFT central charge for generic choice of parameters. However, for a special choice of parameters appearing in the four and six derivative terms reduces the linearized equations to be two derivative, thereby ameliorating the unitarity problem.

Aninda Sinha

2010-08-11T23:59:59.000Z

450

On Solutions of Minimal Massive 3D Gravity  

E-Print Network [OSTI]

We look at solutions of Minimal Massive Gravity (MMG), a generalisation of Topologically Massive Gravity (TMG) that improves upon its holographic properties. It is shown that generically (in MMG parameter space) all conformally flat solutions of vacuum MMG are locally isometric to one of the two (A)dS vacua of the theory. We then couple a scalar field, and find that domain wall solutions can only interpolate between these two vacua precisely when the bulk graviton is tachyonic. Finally, we find a non-BTZ AdS black hole solution satisfying Brown-Henneaux boundary conditions, which lies within the "bulk/ boundary unitarity region".

Arvanitakis, Alex S

2015-01-01T23:59:59.000Z

451

Complete Classification of 1+1 Gravity Solutions  

E-Print Network [OSTI]

A classification of the maximally extended solutions for 1+1 gravity models (comprising e.g. generalized dilaton gravity as well as models with non-trivial torsion) is presented. No restrictions are placed on the topology of the arising solutions, and indeed it is found that for generic models solutions on non-compact surfaces of arbitrary genus with an arbitrary non-zero number of holes can be obtained. The moduli space of classical solutions (solutions of the field equations with fixed topology modulo gauge transformations) is parametrized explicitly.

T. Kloesch; T. Strobl

1997-11-25T23:59:59.000Z

452

Classical and Quantum Aspects of 1+1 Gravity  

E-Print Network [OSTI]

We present a classification of all global solutions (with Lorentzian signature) for any general 2D dilaton gravity model. For generic choices of potential-like terms in the Lagrangian one obtains maximally extended solutions on arbitrary non-compact two-manifolds, including various black-hole and kink configurations. We determine all physical quantum states in a Dirac approach. In some cases the spectrum of the (black-hole) mass operator is found to be sensitive to the signature of the theory, which may be relevant in view of current attempts to implement a generalized Wick-rotation in 4D quantum gravity.

T. Kloesch; P. Schaller; T. Strobl

1996-08-02T23:59:59.000Z

453

Combined passive magnetic bearing element and vibration damper  

DOE Patents [OSTI]

A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium and dampen transversely directed vibrations. Mechanical stabilizers are provided to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. In a improvement over U.S. Pat. No. 5,495,221, a magnetic bearing element is combined with a vibration damping element to provide a single upper stationary dual-function element. The magnetic forces exerted by such an element, enhances levitation of the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations, and suppresses the effects of unbalance or inhibits the onset of whirl-type rotor-dynamic instabilities. Concurrently, this equilibrium is made stable against displacement-dependent drag forces of the rotating object from its equilibrium position.

Post, Richard F. (Walnut Creek, CA)

2001-01-01T23:59:59.000Z

454

A perturbative approach for the study of compatibility between nonminimally coupled gravity and Solar System experiments  

E-Print Network [OSTI]

We develop a framework for constraining a certain class of theories of nonminimally coupled (NMC) gravity with Solar System observations.

Orfeu Bertolami; Riccardo March; Jorge Pramos

2014-03-18T23:59:59.000Z

455

Modeling the benefits of an artificial gravity countermeasure coupled with exercise and vibration  

E-Print Network [OSTI]

aboard the International Space Station (ISS) have shown that anti-gravity muscle volume and peak power

Newman, Dava J.

456

An optimizing reduced order FDS for the tropical Pacific Ocean reduced gravity model  

E-Print Network [OSTI]

An optimizing reduced order FDS for the tropical Pacific Ocean reduced gravity model Zhendong Luoa) for the tropical Pacific Ocean reduced gravity model. Ensembles of data are compiled from transient solutions computed from the discrete equation system derived by FDS for the tropical Pacific Ocean reduced gravity

Aluffi, Paolo

457

On gravity currents in stratified ambients V. K. Birman and E. Meiburga  

E-Print Network [OSTI]

On gravity currents in stratified ambients V. K. Birman and E. Meiburga Department of Mechanical August 2007 Detailed numerical simulations were conducted of gravity currents released from a lock of Physics. DOI: 10.1063/1.2756553 I. INTRODUCTION Gravity currents represent a ubiquitous phenomenon

Meiburg, Eckart H.

458

GRAVITY WAVE DYNAMICS AND EFFECTS IN THE MIDDLE David C. Fritts and M. Joan Alexander  

E-Print Network [OSTI]

GRAVITY WAVE DYNAMICS AND EFFECTS IN THE MIDDLE ATMOSPHERE David C. Fritts and M. Joan Alexander gravity waves have been a subject of intense research activity in recent years because of their myriad. Theoretical, numerical, and observational studies have advanced our understanding of gravity waves on many

Alexander, M. Joan

459

GC GRAVITY Astrometry GYOTO Simulation Perspective Conclusion Testing strong-field general relativity at the  

E-Print Network [OSTI]

GC GRAVITY Astrometry GYOTO Simulation Perspective Conclusion Testing strong-field general relativity at the galactic center with the GRAVITY instrument Seminar - December 15th, 2010 Frédéric VINCENT1/34 Frédéric VINCENT Testing GR at the galactic center #12;GC GRAVITY Astrometry GYOTO Simulation Perspective

Gourgoulhon, Eric

460

Flares GRAVITY Relativistic simulations Conclusion Simulating observations to test GR at the  

E-Print Network [OSTI]

Flares GRAVITY Relativistic simulations Conclusion Simulating observations to test GR at the Galactic Center with GRAVITY GR19 Mexico Frédéric VINCENT1 Thibaut PAUMARD2 , Eric GOURGOULHON3 , Guy at the Galactic Center #12;Flares GRAVITY Relativistic simulations Conclusion 1 Sagittarius A* : a flaring black

Gourgoulhon, Eric

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Gravity currents in cold fresh water Department of Mathematical Sciences, Loughborough University,  

E-Print Network [OSTI]

Gravity currents in cold fresh water A. KAY Department of Mathematical Sciences, Loughborough.Kay@Lboro.ac.uk Abstract We consider surface gravity currents in fresh water where the temperatures of the current an empirical parametrisation of entrainment in lock-release gravity cur- rents, the distance travelled and time

462

Do Gravity Waves Transport Angular Momentum away from Tropical Cyclones? YUMIN MOON AND DAVID S. NOLAN  

E-Print Network [OSTI]

Do Gravity Waves Transport Angular Momentum away from Tropical Cyclones? YUMIN MOON AND DAVID S that gravity waves can transport a significantly large amount of angular momentum away from tropical cyclones-water equations to model gravity waves radiating outward from rapidly rotating inner-core asymmetries. This issue

Nolan, David S.

463

Gravity and tectonic patterns of Mercury: Effect of tidal deformation, spin-orbit resonance, nonzero  

E-Print Network [OSTI]

Gravity and tectonic patterns of Mercury: Effect of tidal deformation, spin-orbit resonance of spin-orbit resonance, nonzero eccentricity, despinning, and reorientation on Mercury's gravity and tectonic pattern. Large variations of the gravity and shape coefficients from the synchronous rotation

Nimmo, Francis

464

Gravity anomalies of the Northern Hawaiian Islands: Implications on the shield evolutions of Kauai and Niihau  

E-Print Network [OSTI]

Gravity anomalies of the Northern Hawaiian Islands: Implications on the shield evolutions of Kauai January 2010; accepted 16 March 2010; published 31 August 2010. [1] New land and marine gravity data reveal two positive residual gravity anomalies in the Northern Hawaiian Islands: one over Kaua

Ito, Garrett

465

GRAVITY ERROR COMPENSATION USING SECOND-ORDER GAUSS-MARKOV PROCESSES  

E-Print Network [OSTI]

AAS 11-502 GRAVITY ERROR COMPENSATION USING SECOND-ORDER GAUSS-MARKOV PROCESSES Jason M. Leonard the use of a second-order Gauss-Markov process to compensate for higher order spherical harmonic gravity an improvement in POD through the use of a second-order Gauss-Markov process (GMP2) for modeling J3 gravity

Born, George

466

Gravity currents propagating up a slope Larissa J. Marleau, Morris R. Flynn, and Bruce R. Sutherland  

E-Print Network [OSTI]

Gravity currents propagating up a slope Larissa J. Marleau, Morris R. Flynn, and Bruce R materials: The crucial effects of gravity and confining walls AIP Conf. Proc. 1542, 49 (2013); 10.1063/1.4811866 Gravity currents in non-rectangular cross-section channels: Analytical and numerical solutions of the one

Flynn, Morris R.

467

Gravity Based Autonomous Calibration for Robot Manipulators Donghai Ma, John M. Hollerbach and Yangming Xu  

E-Print Network [OSTI]

Gravity Based Autonomous Calibration for Robot Manipulators Donghai Ma, John M. Hollerbach, the gravity torque exerted on the joint varies sinusoidally with rotation angle. By means of sinusoidal curve. The gravity vec- tor, expressed in the defined base coordinates, can also be found. Thereafter we determine

Hollerbach, John M.

468

Gravity points in potential-field approaches to self organisation Aaron Sampson  

E-Print Network [OSTI]

Gravity points in potential-field approaches to self organisation Aaron Sampson School, among other applications. In this paper, we extend this approach by the addition of gravity points which]. In this paper, we extend this pattern by a notion of gravity points. These produce additional fields which

Smith, Graeme

469

The Trouble with Gravity Summary/Review Lecture 7: Spring 2009 Compton Lecture Series  

E-Print Network [OSTI]

energy, and the mass of the black hole decreases to compensate. This is "Hawking radiation of quantum mechanics. · Gravity affects the vacuum energy density ­ According to Newton, gravity affects anything with mass. But according to Einstein, mass is just one form of energy. It follows that gravity

470

Canonical quantization of a minisuperspace model for gravity using self-dual variables  

E-Print Network [OSTI]

The present article summarizes the work of the papers \\cite{1} dealing with the quantization of pure gravity and gravity coupled to a Maxwell field and a cosmological constant in presence of spherical symmetry. The class of models presented is intended as an interesting testing ground for the quantization of full 3+1 gravity. We are working in Ashtekar's self-dual representation.

T. Thiemann

1999-10-04T23:59:59.000Z

471

Complete Bouguer gravity map of the Nevada Test Site and vicinity, Nevada  

SciTech Connect (OSTI)

About 15,000 gravity stations were used to create the gravity map. Gravity studies at the Nevada Test Site were undertaken to help locate geologically favorable areas for underground nuclear tests and to help characterize potential high-level nuclear waste storage sites. 48 refs. (TEM)

Healey, D.L.; Harris, R.N.; Ponce, D.A.; Oliver, H.W.

1987-12-31T23:59:59.000Z

472

Primordial magnetic field amplification from turbulent reheating  

SciTech Connect (OSTI)

We analyze the possibility of primordial magnetic field amplification by a stochastic large scale kinematic dynamo during reheating. We consider a charged scalar field minimally coupled to gravity. During inflation this field is assumed to be in its vacuum state. At the transition to reheating the state of the field changes to a many particle/anti-particle state. We characterize that state as a fluid flow of zero mean velocity but with a stochastic velocity field. We compute the scale-dependent Reynolds number Re(k), and the characteristic times for decay of turbulence, t{sub d} and pair annihilation t{sub a}, finding t{sub a} << t{sub d}. We calculate the rms value of the kinetic helicity of the flow over a scale L and show that it does not vanish. We use this result to estimate the amplification factor of a seed field from the stochastic kinematic dynamo equations. Although this effect is weak, it shows that the evolution of the cosmic magnetic field from reheating to galaxy formation may well be more complex than as dictated by simple flux freezing.

Calzetta, Esteban [Departamento de Fsica, FCEyN-UBA and IFIBA-CONICET, Cdad. Universitaria, Buenos Aires (Argentina); Kandus, Alejandra, E-mail: calzetta@df.uba.ar, E-mail: kandus@uesc.br [LATO - DCET - UESC. Rodovia Ilhus-Itabuna, km 16 s/n, CEP: 45662-900, Salobrinho, Ilhus-BA (Brazil)

2010-08-01T23:59:59.000Z

473

Permanent magnet steam generator  

SciTech Connect (OSTI)

This patent describes a system for magnetic heating of a fluid by motor rotation of a permanent magnet rotor adjacent an assembly of ferro-magnetic condensing plate and of copper heat absorber plate with protrusions through the ferro-magnetic condensing plate into an enclosure with the fluid therein and having fluid inlet and fluid outlet. The assembly has a first shaft and a second shaft coaxially spaced therefrom, a respective the motor connected to the outer end of each shaft, and a respective the permanent magnet rotor connected to the inner end of each shaft, adjacent a the heat absorber plate. The improvement described here comprises: the enclosure including a steel boiler with a first the ferro-magnetic condensing plate closing off a first end thereof and a second the ferro-magnetic condensing plate closing off a second end thereof, a the copper heat absorbing plate affixed on each ferro-magnetic plate; means, free of pockets, for promoting turbulent flow of the fluid with uniformly good heat transfer including the protrusion being a plurality of heat sinks, each heat sink of the plurality of heat sinks comprising an integral elongate member with an alternately large diameter and smaller diameter portions regularly spaced therealong. The elongate members through the first the ferro-magnetic condensing plate are coaxially aligned with the elongate members through the second the ferro-magnetic condensing plate.

Gerard, F.; Gerard, F.J.

1986-09-30T23:59:59.000Z

474

Peeling and Multi-critical Matter Coupled to Quantum Gravity  

E-Print Network [OSTI]

We show how to determine the unknown functions arising when the peeling decomposition is applied to multi-critical matter coupled to two-dimensional quantum gravity and compute the loop-loop correlation functions. The results that $\\eta=2+2/(2K-3)$ and $\

Martin G. Harris; John F. Wheater

1999-11-24T23:59:59.000Z

475

Horizon surface gravity as 2d geodesic expansion  

E-Print Network [OSTI]

The surface gravity of any Killing horizon, in any spacetime dimension, can be interpreted as a local, two-dimensional expansion rate seen by freely falling observers when they cross the horizon. Any two-dimensional congruence of geodesics invariant under the Killing flow can be used to define this expansion, provided that the observers have unit Killing energy.

Ted Jacobson; Renaud Parentani

2008-08-13T23:59:59.000Z

476

1+1 Sector of 3+1 Gravity  

E-Print Network [OSTI]

The rank--1 sector of classical Ashtekar gravity is considered, motivated by the degeneracy of the metric along the Wilson lines in quantum loop states. It is found that the lines behave like 1+1 dimensional spacetimes with a pair of massless complex fields propagating along them. The inclusion of matter and extension to supergravity are also considered.

Ted Jacobson

1996-04-01T23:59:59.000Z

477

Entirely passive heat pipe apparatus capable of operating against gravity  

DOE Patents [OSTI]

The disclosure is directed to an entirely passive heat pipe apparatus capable of operating against gravity for vertical distances in the order of 3 to 7 meters and more. A return conduit into which an inert gas is introduced is used to lower the specific density of the working fluid so that it may be returned a greater vertical distance from condenser to evaporator.

Koenig, Daniel R. (Santa Fe, NM)

1982-01-01T23:59:59.000Z

478

Gravity and fault structures, Long Valley caldera, California  

SciTech Connect (OSTI)

The main and catastrophic phase of eruption in Long Valley occurred 0.73 m.y. ago with the eruption of over 600 km/sup 3/ of rhyolitic magma. Subsequent collapse of the roof rocks produced a caldera which is now elliptical in shape, 32 km east-west by 17 km north-south. The caldera, like other large Quarternary silicic ash-flow volcanoes that have been studied by various workers, has a nearly coincident Bouguer gravity low. Earlier interpretations of the gravity anomaly have attributed the entire anomaly to lower density rocks filling the collapsed structure. However, on the basis of many additional gravity stations and supporting subsurface data from several new holes, a much more complex and accurate picture has emerged of caldera structure. From a three-dimensional inversion of the residual Bouguer gravity data we can resolve discontinuities that seem to correlate with extensions of pre-caldera faults into the caldera and faults associated with the ring fracture. Some of these faults are believed related to the present-day hydrothermal upflow zone and the zone of youngest volcanic activity within the caldera.

Carle, S.F.; Goldstein, N.E.

1987-07-01T23:59:59.000Z

479

Kac-Moody algebras in gravity and M-theories  

SciTech Connect (OSTI)

The formulation of gravity and M-theories as very-extended Kac-Moody invariant theories is reviewed. Exact solutions describing intersecting extremal brane configurations smeared in all directions but one are presented. The intersection rules characterising these solutions are neatly encoded in the algebra. The existence of dualities for all G +++ and their group theoretical-origin are discussed.

Houart, Laurent [Service de Physique Theorique et Mathematique, Universite Libre de Bruxelles, Campus Plaine C.P. 231, Boulevard du Triomphe, B-1050 Brussels (Belgium); International Solvay Instiitutes, Campus Plaine C.P. 231, Boulevard du Triomphe, B-1050 Brussels (Belgium)

2006-06-19T23:59:59.000Z

480

Effective Matter Cosmologies of Massive Gravity: Physical Fluids  

E-Print Network [OSTI]

We derive new cosmological solutions of the ghost-free massive gravity with a general background metric in which the contribution of the mass sector to the metric one is modeled by an effective cosmological constant and an ideal fluid which obeys the first law of thermodynamics; thus it satisfies the ordinary energy-momentum conservation or continuity equation.

Nejat Tevfik Yilmaz

2014-12-16T23:59:59.000Z

Note: This page contains sample records for the topic "gravity magnetic electncal" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

2D dilaton-gravity from 5D Einstein equations  

E-Print Network [OSTI]

A semiclassical two-dimensional dilaton-gravity model is obtained by dimensional reduction of the spherically symmetric five-dimensional Einstein equations and used to investigate black hole evaporation. It is shown that this model prevents the formation of naked singularity and allows spacetime wormholes to contribute the process of formation and evaporation of black holes.

P. F. Gonzlez-Daz

1993-07-16T23:59:59.000Z

482

Gravity-related wave function collapse: Is superfluid He exceptional?  

E-Print Network [OSTI]

The gravity-related model of spontaneous wave function collapse, a longtime hypothesis, damps the massive Schr\\"odinger Cat states in quantum theory. We extend the hypothesis and assume that spontaneous wave function collapses are responsible for the emergence of Newton interaction. Superfluid helium would then show significant and testable gravitational anomalies.

Lajos Disi

2013-02-21T23:59:59.000Z

483

Gravity Surface Wave Bifurcation in a Highly Turbulent Swirling Flow  

E-Print Network [OSTI]

: The `base state' of Taylor-Couette flow. The slight asymmetry seen in this photo appears to undergo-Couette gravity wave, we used a capacitive height sensor that consists of a copper wire covered with a thin layer a Q/h 2 1 r dr (2) C = 2 ln (b/a) h (3) Therefore, our sensor turns the varying height

Witten, Thomas A.

484

ECOSMOG: An Efficient Code for Simulating Modified Gravity  

E-Print Network [OSTI]

We introduce a new code, ECOSMOG, to run N-body simulations for a wide class of modified gravity and dynamical dark energy theories. These theories generally have one or more new dynamical degrees of freedom, the dynamics of which are governed by their (usually rather nonlinear) equations of motion. Solving these non-linear equations has been a great challenge in cosmology. Our code is based on the RAMSES code, which solves the Poisson equation on adaptively refined meshes to gain high resolutions in the high-density regions. We have added a solver for the extra degree(s) of freedom and performed numerous tests for the f(R) gravity model as an example to show its reliability. We find that much higher efficiency could be achieved compared with other existing mesh/grid-based codes thanks to two new features of the present code: (1) the efficient parallelisation and (2) the usage of the multigrid relaxation to solve the extra equation(s) on both the regular domain grid and refinements, giving much faster convergence even under much more stringent convergence criteria. This code is designed for performing high-accuracy, high-resolution and large-volume cosmological simulations for modified gravity and general dark energy theories, which can be utilised to test gravity and the dark energy hypothesis using the upcoming and future deep and high-resolution galaxy surveys.

Baojiu Li; Gong-Bo Zhao; Romain Teyssier; Kazuya Koyama

2011-10-06T23:59:59.000Z

485

Generalized massive gravity in AdS{sub 3} spacetime  

SciTech Connect (OSTI)

In this note we investigate the generalized massive gravity in asymptotically AdS{sub 3} spacetime by combining the two mass terms of topological massive gravity and new massive gravity theory. We study the linearized excitations around the AdS{sub 3} background and find that at a specific value of a certain combination of the two mass parameters (chiral line), one of the massive graviton solutions becomes the left-moving massless mode. It is shown that the theory is chiral at this line under Brown-Henneaux boundary condition. Because of this degeneration of the gravitons the new log solution which has a logarithmic asymptotic behavior is also a solution to this gravity theory at the chiral line. The log boundary condition which was proposed to accommodate this log solution is proved to be consistent at this chiral line. The resulting theory is no longer chiral except at a special point on the chiral line, where another new solution with log-square asymptotic behavior exists. At this special point, we prove that a new kind of boundary condition called log-square boundary condition, which accommodates this new solution, can be consistent.

Liu Yan; Sun Yawen [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P. O. Box 2735, Beijing 100190 (China)

2009-06-15T23:59:59.000Z

486

No Open or Flat Bouncing Cosmologies in Einstein Gravity  

E-Print Network [OSTI]

We show that bouncing open or flat Friedmann-Robertson-Walker cosmologies are inconsistent with worldsheet string theory to first approximation. Specifically, the Virasoro constraint translates to the null energy condition in spacetime at leading order in the alpha-prime expansion. Thus one must go beyond minimally-coupled Einstein gravity in order to find bounce solutions.

Parikh, Maulik K

2015-01-01T23:59:59.000Z

487

Extra force in Kaluza-Klein gravity theory  

E-Print Network [OSTI]

In induced matter Kaluza-Klein gravity theory the solution of the dynamics equations for the test particle on null path leads to additional force in four-dimensional space-time. We find such force from five-dimensional geodesic line equations and apply this approach to analysis of the asymmetrically warped space-time.

W. B. Belayev

2007-06-18T23:59:59.000Z

488

Stiffness modeling of robotic manipulator with gravity compensator  

E-Print Network [OSTI]

to the stiffness modeling of a heavy industrial robot of the Kuka family. Key words: Stiffness modeling, gravity compensator, industrial robot. 1 Introduction Recently, in aerospace industry much attention is paid these requirements, industrial robots are more and more used to replace conventional CNC-machines, which are limited

Paris-Sud XI, Université de

489

Gravity Scaling of a Power Reactor Water Shield  

SciTech Connect (OSTI)

Water based reactor shielding is being considered as an affordable option for potential use on initial lunar surface reactor power systems. Heat dissipation in the shield from nuclear sources must be rejected by an auxillary thermal hydraulic cooling system. The mechanism for transferring heat through the shield is natural convection between the core surface and an array of thermosyphon radiator elements. Natural convection in a 100 kWt lunar surface reactor shield design has been previously evaluated at lower power levels (Pearson, 2006). The current baseline assumes that 5.5 kW are dissipated in the water shield, the preponderance on the core surface, but with some volumetric heating in the naturally circulating water as well. This power is rejected by a radiator located above the shield with a surface temperature of 370 K. A similarity analysis on a water-based reactor shield is presented examining the effect of gravity on free convection between a radiation shield inner vessel and a radiation shield outer vessel boundaries. Two approaches established similarity: 1) direct scaling of Rayleigh number equates gravity-surface heat flux products, 2) temperature difference between the wall and thermal boundary layer held constant on Earth and the Moon. Nussult number for natural convection (laminar and turbulent) is assumed of form Nu = CRa{sup n}. These combined results estimate similarity conditions under Earth and Lunar gravities. The influence of reduced gravity on the performance of thermosyphon heat pipes is also examined.

Reid, Robert S.; Pearson, J. Boise [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States)

2008-01-21T23:59:59.000Z

490

Gravity fields of eight north Pacific seamounts: implications for density  

E-Print Network [OSTI]

, gravity and other geophysical data used in this study on the following seamount survey cruises; KK780807, KK800715, KK80040Z, and KK81062602 during the period from 1978 to 1981. Additional data were obtained from the National Geophysical Data Center...

Freitag, Helen Clare

1987-01-01T23:59:59.000Z

491

math.QA/0006228 Combinatorial quantisation of Euclidean gravity  

E-Print Network [OSTI]

MS­00­007 math.QA/0006228 Combinatorial quantisation of Euclidean gravity in three dimensions B the combinatorial quantisation program developed for 1 address after 1.09.2000: Department of Mathematics, Heriot by Alekseev, Grosse and Schomerus, see [1][2] and also [3]. We shall show how to implement the main steps

Schroers, Bernd J.

492

Testing gravity with halo density profiles observed through gravitational lensing  

SciTech Connect (OSTI)

We present a new test of the modified gravity endowed with the Vainshtein mechanism with the density profile of a galaxy cluster halo observed through gravitational lensing. A scalar degree of freedom in the galileon modified gravity is screened by the Vainshtein mechanism to recover Newtonian gravity in high-density regions, however it might not be completely hidden on the outer side of a cluster of galaxies. Then the modified gravity might yield an observational signature in a surface mass density of a cluster of galaxies measured through gravitational lensing, since the scalar field could contribute to the lensing potential. We investigate how the transition in the Vainshtein mechanism affects the surface mass density observed through gravitational lensing, assuming that the density profile of a cluster of galaxies follows the original Navarro-Frenk-White (NFW) profile, the generalized NFW profile and the Einasto profile. We compare the theoretical predictions with observational results of the surface mass density reported recently by other researchers. We obtain constraints on the amplitude and the typical scale of the transition in the Vainshtein mechanism in a subclass of the generalized galileon model.

Narikawa, Tatsuya; Yamamoto, Kazuhiro, E-mail: narikawa@theo.phys.sci.hiroshima-u.ac.jp, E-mail: kazuhiro@hiroshima-u.ac.jp [Department of Physical Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan)

2012-05-01T23:59:59.000Z

493

Thermodynamic route to field equations in Lanczos-Lovelock gravity  

SciTech Connect (OSTI)

Spacetimes with horizons show a resemblance to thermodynamic systems and one can associate the notions of temperature and entropy with them. In the case of Einstein-Hilbert gravity, it is possible to interpret Einstein's equations as the thermodynamic identity TdS=dE+PdV for a spherically symmetric spacetime and thus provide a thermodynamic route to understand the dynamics of gravity. We study this approach further and show that the field equations for the Lanczos-Lovelock action in a spherically symmetric spacetime can also be expressed as TdS=dE+PdV with S and E given by expressions previously derived in the literature by other approaches. The Lanczos-Lovelock Lagrangians are of the form L=Q{sub a}{sup bcd}R{sup a}{sub bcd} with {nabla}{sub b}Q{sub a}{sup bcd}=0. In such models, the expansion of Q{sub a}{sup bcd} in terms of the derivatives of the metric tensor determines the structure of the theory and higher order terms can be interpreted as quantum corrections to Einstein gravity. Our result indicates a deep connection between the thermodynamics of horizons and the allowed quantum corrections to standard Einstein gravity, and shows that the relation TdS=dE+PdV has a greater domain of validity than Einstein's field equations.

Paranjape, Aseem; Sarkar, Sudipta; Padmanabhan, T. [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400 005 (India); IUCAA, Post Bag 4, Ganeshkhind, Pune-411 007 (India)

2006-11-15T23:59:59.000Z

494

Gravity monitoring of CO2 movement during sequestration: Model studies  

SciTech Connect (OSTI)

We examine the relative merits of gravity measurements as a monitoring tool for geological CO{sub 2} sequestration in three different modeling scenarios. The first is a combined CO{sub 2} enhanced oil recovery (EOR) and sequestration in a producing oil field, the second is sequestration in a brine formation, and the third is for a coalbed methane formation. EOR/sequestration petroleum reservoirs have relatively thin injection intervals with multiple fluid components (oil, hydrocarbon gas, brine, and CO{sub 2}), whereas brine formations usually have much thicker injection intervals and only two components (brine and CO{sub 2}). Coal formations undergoing methane extraction tend to be thin (3-10 m), but shallow compared to either EOR or brine formations. The injection of CO{sub 2} into the oil reservoir produced a bulk density decrease in the reservoir. The spatial pattern of the change in the vertical component of gravity (G{sub z}) is directly correlated with the net change in reservoir density. Furthermore, time-lapse changes in the borehole G{sub z} clearly identified the vertical section of the reservoir where fluid saturations are changing. The CO{sub 2}-brine front, on the order of 1 km within a 20 m thick brine formation at 1900 m depth, with 30% CO{sub 2} and 70% brine saturations, respectively, produced a -10 Gal surface gravity anomaly. Such anomaly would be detectable in the field. The amount of CO{sub 2} in a coalbed methane test scenario did not produce a large enough surface gravity response; however, we would expect that for an industrial size injection, the surface gravity response would be measurable. Gravity inversions in all three scenarios illustrated that the general position of density changes caused by CO{sub 2} can be recovered, but not the absolute value of the change. Analysis of the spatial resolution and detectability limits shows that gravity measurements could, under certain circumstances, be used as a lower-cost alternative to seismic measurements.

Gasperikova, E.; Hoversten, G.M.

2008-07-15T23:59:59.000Z

495

Passive magnetic bearing system  

DOE Patents [OSTI]

An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

Post, Richard F.

2014-09-02T23:59:59.000Z

496

Stability of Interfaces with Self-Gravity, Relative Flow, and {ital B} Field  

SciTech Connect (OSTI)

Observations with the {ital Hubble} {ital Space} {ital T}{ital elescope} (Hester et al.) of spectacular {open_quotes}fingers{close_quotes} or {open_quotes}elephant trunks{close_quotes} of gas protruding from a large star-forming cloud in the Eagle Nebula stimulate renewed interest in the stability of interfaces between different media in molecular clouds. Instability and nonlinear growth of crenelations of interfaces can lead to mass concentrations that in turn lead to star formation. In an earlier study of the stability of interfaces, we took into account the important physical effects{emdash}the different densities and temperatures of the media, the relative motion (Kelvin-Helmholtz instability), the gravitational acceleration perpendicular to the interface (Rayleigh-Taylor instability), and self-gravity. A new {ital self}-{ital gravitational} {ital instability} of an interface was found that was independent of the wavelength of the perturbation. At short wavelengths, the perturbations are essentially distortional, but compression becomes important as the Jeans length is approached from below. The {ital e}-folding time for the instability is comparable with the free-fall collapse time for the denser fluid. In the present work, we generalize our earlier theory in two ways: by including ordered magnetic fields parallel to the interface, and by examining the stability of long cylindrical interfaces. We show that dynamically important magnetic fields in the media can quench instabilities if the fields are oriented in different directions (that is, crossed); however, for astronomically plausible geometries in which the fields are closer to being parallel, but of different strengths in the two media, instabilities are free to grow in directions normal to the fields. A cylindrical interface between an interior medium of density {rho}{sub 1} and an exterior medium of density {rho}{sub 2} provides a model for the long filaments of dense gas observed in some molecular clouds. We show that such an interface with {rho}{sub 1} {gt} {rho}{sub 2} is stable to {open_quotes}kink modes{close_quotes} but unstable to {open_quotes}sausage modes{close_quotes} owing to self-gravity for long axial wavelengths, {lambda}{sub {ital z}} {gt} 3.8{ital d}, where {ital d} is the diameter of the cylinder. This instability will tend to form prolate ellipsoidal density concentrations aligned with the cylinder axis. {copyright} {ital {copyright} .} {ital The American Astronomical Society}

Hunter, J.H. Jr. [Department of Astronomy, University of Florida, PO Box 112005, Gainesville, FL 32611-2055 (United States)] [Department of Astronomy, University of Florida, PO Box 112005, Gainesville, FL 32611-2055 (United States); Whitaker, R.W. [Los Alamos National Laboratory, EES-8, MS F659, Los Alamos, NM 87545 (United States)] [Los Alamos National Laboratory, EES-8, MS F659, Los Alamos, NM 87545 (United States); Lovelace, R.V. [Department of Astronomy, Cornell University, Ithaca, NY 14853-6801 (United States)] [Department of Astronomy, Cornell University, Ithaca, NY 14853-6801 (United States)

1998-12-01T23:59:59.000Z

497

ALIGNMENT BETWEEN FLATTENED PROTOSTELLAR INFALL ENVELOPES AND AMBIENT MAGNETIC FIELDS  

SciTech Connect (OSTI)

We present 350 {mu}m polarization observations of four low-mass cores containing Class 0 protostars: L483, L1157, L1448-IRS2, and Serp-FIR1. This is the second paper in a larger survey aimed at testing magnetically regulated models for core-collapse. One key prediction of these models is that the mean magnetic field in a core should be aligned with the symmetry axis (minor axis) of the flattened young stellar object inner envelope (aka pseudodisk). Furthermore, the field should exhibit a pinched or hourglass-shaped morphology as gravity drags the field inward toward the central protostar. We combine our results for the four cores with results for three similar cores that were published in the first paper from our survey. An analysis of the 350 {mu}m polarization data for the seven cores yields evidence of a positive correlation between mean field direction and pseudodisk symmetry axis. Our rough estimate for the probability of obtaining by pure chance a correlation as strong as the one we found is about 5%. In addition, we combine together data for multiple cores to create a source-averaged magnetic field map having improved signal-to-noise ratio, and this map shows good agreement between mean field direction and pseudodisk axis (they are within 15 Degree-Sign ). We also see hints of a magnetic pinch in the source-averaged map. We conclude that core-scale magnetic fields appear to be strong enough to guide gas infall, as predicted by the magnetically regulated models. Finally, we find evidence of a positive correlation between core magnetic field direction and bipolar outflow axis.

Chapman, Nicholas L.; Matthews, Tristan G.; Novak, Giles [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Davidson, Jacqueline A. [School of Physics, University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009 (Australia); Goldsmith, Paul F. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, MS 264-782, Pasadena, CA 91109 (United States); Houde, Martin [Department of Physics and Astronomy, University of Western Ontario, London, ON (Canada); Kwon, Woojin; Looney, Leslie W. [Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801 (United States); Li Zhiyun [Astronomy Department, University of Virginia, Charlottesville, VA 22904 (United States); Matthews, Brenda [Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Peng Ruisheng [Caltech Submillimeter Observatory, 111 Nowelo Street, Hilo, HI 96720 (United States); Vaillancourt, John E. [SOFIA Science Center, Universities Space Research Association, NASA Ames Research Center, MS 232-11, Moffett Field, CA 94035-0001 (United States); Volgenau, Nikolaus H. [California Institute of Technology, Owens Valley Radio Observatory, Big Pine, CA 93513 (United States)

2013-06-20T23:59:59.000Z

498

Pulse magnetic welder  

DOE Patents [OSTI]

A welder is described for automated closure of fuel pins by a pulsed magnetic process in which the open end of a length of cladding is positioned within a complementary tube surrounded by a pulsed magnetic welder. Seals are provided at each end of the tube, which can be evacuated or can receive tag gas for direct introduction to the cladding interior. Loading of magnetic rings and end caps is accomplished automatically in conjunction with the welding steps carried out within the tube.

Christiansen, D.W.; Brown, W.F.

1984-01-01T23:59:59.000Z

499

Magnetic Braids Anthony Yeates  

E-Print Network [OSTI]

flux function Main result Conclusion 2. Thermonuclear confinement devices. ITER (Internat'l Thermonuclear Experimental Reactor). Inside the KSTAR tokamak. Correspond to periodic magnetic braids. 4 / 22

Dundee, University of

500

Magnetic differential torque sensor  

SciTech Connect (OSTI)

A new torque sensor structure is presented. The basic idea is a simple torque sensor with a variable magnetic circuit excited by an axially magnetized permanent magnet ring. The circuit is constituted by iron toothed rings, whose teeth relative position changes whenever an applied torque twists the rotating shaft. A Hall probe measures the induction in an airgap where the induction is uniform. The new structure is an association of two previous ones, thus creating a differential system with the related advantages: diminution of thermal drifts, zero mean value for the signal. The new magnetic circuit is studied by calculating equivalent reluctances through energy calculations and by using electrical analogies.

Lemarquand, V.; Lemarquand, G. [Univ. de Savoie, Annecy-le-Vieux (France)] [Univ. de Savoie, Annecy-le-Vieux (France)

1995-11-01T23:59:59.000Z